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Human milk oligosaccharides (HMOs) and the milk fat globule membrane (MFGM) represent novel treatments for cow's milk allergy (CMA). They exhibit the beneficial attribute of diminishing nutrient damage when compared to conventional enzymatic digestion of milk proteins. However, the effects and mechanisms underlying the synergistic interaction between HMOs and the MFGM in allergy treatment remain unclear. Consequently, this study was undertaken to assess the protective properties of HMOs and the MFGM against CMA and to elucidate their potential mechanisms in a mouse model of β-lactoglobulin (BLG)-induced allergy. The findings demonstrated that HMOs and the MFGM could significantly reduce the allergy score and splenic index, and they diminished the levels of inflammatory mediators (total immunoglobulin E (IgE), specific IgE, histamine, and mMCP-1), while concurrently bolstering tight junctions ( ZO-1 , claudin-1 , and occludin ), and reducing intestinal permeability. Notably, HMOs and the MFGM exhibited optimal synergy. In addition, HMOs and the MFGM synergistically mitigated the immune response to Th2 overactivity in allergy by the promotion of Th1 and Treg cell responses, thereby suppressing the levels of inflammatory cytokines IL-4 and IL-5. Analysis of the gut microbiota and its metabolic activities revealed that HMOs and the MFGM increased the abundance of Lactobacillus and Butyricicoccus , leading to higher production of butyrate. Furthermore, these beneficial bacteria and the resultant butyrate also contributed to the suppression of allergy-associated bacterial populations such as Desulfovibrio and Rikenellaceae . In summary, HMOs and the MFGM acted in synergy to modulate inflammatory responses and ameliorate barrier damage, contributing to the mitigation of CMA, a process potentially linked to gut microbiota dynamics and the resultant butyrate metabolism. This effect may be related to the gut microbiota and its metabolic production of butyrate.

Background/aims: The etiology of irritable bowel syndrome (IBS) is associated with intestinal mucosal barrier damage. However, changes in the tight junction (TJ) proteins in IBS have not been fully elucidated. This study aimed to evaluate TJ protein changes in IBS patients and the relationship between aging and disease severity., Methods: Thirty-six patients with IBS fulfilling the Rome IV criteria and twenty-four controls were included. To evaluate the change of TJ in the colonic mucosa, quantitative reverse transcription polymerase chain reaction, western blot, and immunohistochemistry (IHC) were performed, respectively., Results: The entire IBS group (n = 36) exhibited decreased levels of claudin-1 and -2 mRNA compared to the control group (n = 24), with statistical significance (p < 0.05). Additionally, in western blot analyses, both claudin-1 and ZO-1 levels were significantly reduced in the IBS group compared to the control group (n = 24) (p < 0.05). IHC analysis further revealed that ZO-1 expression was significantly lower in the IBS group than in the control group (p < 0.001). This trend of reduced ZO-1 expression was also observed in the moderate-to-severe IBS subgroup (p < 0.001). Significantly, ZO-1 expression was notably lower in both the young- (p = 0.036) and old-aged (p = 0.039) IBS groups compared to their respective age-matched control groups. Subtype analysis indicated a more pronounced decrease in ZO-1 expression with advancing age., Conclusion: ZO-1 expression was especially decreased in the aged IBS group. These results suggest that ZO-1 might be the prominent TJ protein causing IBS in the aging population.

The 24 claudin ( CLDN ) genes in the human genome encode 26 representative CLDN family proteins. CLDNs are tetraspan‑transmembrane proteins at tight junctions. Because several CLDN isoforms, such as CLDN6 and CLDN18.2, are specifically upregulated in human cancer, CLDN‑targeting monoclonal antibodies (mAbs), antibody‑drug conjugates (ADCs), bispecific antibodies (bsAbs) and chimeric antigen receptor (CAR) T cells have been developed. In the present review, CLDN1‑, 4‑, 6‑ and 18.2‑targeting investigational drugs in clinical trials are discussed. CLDN18.2‑directed therapy for patients with gastric and other types of cancer is the most advanced area in this field. The mouse/human chimeric anti‑CLDN18.2 mAb zolbetuximab has a single‑agent objective response rate (ORR) of 9%, and increases progression‑free and overall survival in combination with chemotherapy. The human/humanized anti‑CLDN18.2 mAb osemitamab, and ADCs AZD0901, IBI343 and LM‑302, with single‑agent ORRs of 28‑60%, have been tested in phase III clinical trials. In addition, bsAbs, CAR T cells and their derivatives targeting CLDN4, 6 or 18.2 are in phase I and/or II clinical trials. AZD0901, IBI343, zolbetuximab and the anti‑CLDN1 mAb ALE.C04 have been granted fast track designation or priority review designation by the US Food and Drug Administration.

Background: The Madin-Darby canine kidney (MDCK) cell line constitutes a key component of influenza vaccine production, but its dependence on adherent growth limits cell culture density and hinders vaccine yield. There is evidence that the use of gene editing techniques to inhibit cell adhesion and establish an easily suspended cell line can improve vaccine yield; however, the mechanisms underlying MDCK cell adhesion are unclear. Methods: In this study, we used transcriptomics to analyse differentially expressed mRNAs and miRNAs in adherent and suspension cultures of MDCK cells. Results : We found that claudin-1 (CLDN1) expression was downregulated in the suspension MDCK cells and that CLDN1 promotes MDCK cell-extracellular matrix adhesion. Additionally, microRNA (miR)-175 expression was upregulated in the suspension MDCK cells. Importantly, we demonstrated that miR-175 inhibits MDCK cell adhesion by targeting the CLDN1 3'-untranslated region (UTR). These findings contribute to a more comprehensive understanding of the regulatory mechanisms modulating cell adhesion and provide a basis for establishing suspension-adapted, genetically engineered cell lines. Our work could also facilitate the identification of targets for tumour therapy.

Background: Vaccination is the best way to prevent influenza virus infection, and insufficient antibodies make it difficult to resist influenza virus invasion. Astragalus Polysaccharide (APS) has a boosting effect on immunity, so we evaluate the effect of APS as an immune adjuvant for H1N1 influenza vaccines in this study., Methods: The mice were immunized twice with influenza A (H1N1) vaccine and APS. Subsequently, the serum antibody levels were assessed using enzyme-linked immunosorbent assay (ELISA). The frequency of peripheral immune T cells was determined by flow cytometry. Following this, the immunized mice were exposed to a lethal dose of the virus, and changes in body weight and survival rates were recorded. Hematoxylin-eosin staining was employed to observe pathological alterations in lung and intestinal tissues. Western blot analysis was conducted to detect the expression of intestinal barrier function proteins (Occludin and Claudin-1). ELISA was utilized to measure the expression level of serum inflammatory cytokine TNF-α. Fresh mouse feces were collected after the initial immunization as well as after viral infection for 16S rRNA analysis aimed at detecting alterations in gut microbiota., Results: Compared to the Hemagglutinin (HA) group, the APS group demonstrated higher levels of immunoglobulin G (IgG), IgG1, and IgG3, as well as neutralizing antibody levels. Additionally, it increased the frequency of CD8 + cells to enhance resistance against lethal infection. On day 14 post-infection, the high-dose APS group exhibited a higher survival rate (71.40 %) compared to the HA group (14.28 %), along with faster weight recovery. Furthermore, APS was found to ameliorate alveolar damage in lung tissue and rectify intestinal structural disorder. It also upregulated the expression levels of tight junction proteins Occludin and Claudin-1 in intestinal tissue while reducing serum TNF-α expression levels. In addition, populations of Colidextribacter, Peptococcaceae, and Ruminococcaceae were the dominant gut microbiota in the APS group after viral infection., Conclusion: APS has an immune-enhancing effect and is expected to be a novel adjuvant in the H1N1 influenza vaccine., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Exposure to VEGF-A 165 a over several days leads to a persistent dysfunction of the very tight barrier formed by immortalized endothelial cells of the bovine retina (iBREC). Elevated permeability of the barrier is indicated by low cell index values determined by electric cell-substrate impedance measurements, by lower amounts of claudin-1, and by disruption of the homogenous and continuous staining of vascular endothelial cadherin at the plasma membrane. Because of findings that suggest modulation of VEGF-A's detrimental effects on the inner blood-retina barrier by the angiogenic growth factor angiopoietin-2, we investigated in more detail in vitro whether this growth factor indeed changes the stability of the barrier formed by retinal endothelial cells or modulates effects of VEGF-A. In view of the clinical relevance of anti-VEGF therapy, we also studied whether blocking VEGF-A-driven signaling is sufficient to prevent barrier dysfunction induced by a combination of both growth factors. Although angiopoietin-2 stimulated proliferation of iBREC, the formed barrier was not weakened at a concentration of 3 nM: Cell index values remained high and expression or subcellular localization of claudin-1 and vascular endothelial cadherin, respectively, were not affected. Angiopoietin-2 enhanced the changes induced by VEGF-A 165 a and this was more pronounced at lower concentrations of VEGF-A 165 a. Specific inhibition of the VEGF receptors with tivozanib as well as interfering with binding of VEGF-A to its receptors with bevacizumab prevented the detrimental effects of the growth factors; dual binding of angiopoietin-2 and VEGF-A by faricimab was marginally more efficient. Uptake of extracellular angiopoietin-2 by iBREC can be efficiently prevented by addition of faricimab which is also internalized by the cells. Exposure of the cells to faricimab over several days stabilized their barrier, confirming that inhibition of VEGF-A signaling is not harmful to this cell type. Taken together, our results confirm the dominant role of VEGF-A 165 a in processes resulting in increased permeability of retinal endothelial cells in which angiopoietin-2 might play a minor modulating role., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objective: This study aimed to investigate the expression of tight junction, its distribution pattern in oral lichen planus samples and its potential association with the severity of oral lichen planus., Materials and Methods: Cross-sectional study designs were conducted. Transcriptome sequencing was conducted using oral mucosal tissues from 22 patients with oral lichen planus and 11 healthy controls. Immunohistochemistry and quantitative reverse transcription PCR were performed to verify the expression of claudin-1, claudin-4, occludin and zonula occludens-1 in oral mucosal tissues from another 30 patients with oral lichen planus and 26 healthy controls. The relationship between tight junction protein expression and oral lichen planus severity was explored using correlation analysis., Results: 5603 and 2475 differentially expressed genes were upregulated and downregulated respectively, in oral lichen planus tissues. KEGG analysis showed that tight junctions including CLDN1, CLDN4, OCLN and TJP1 were downregulated in oral lichen planus. Claudin-1, claudin-4, occludin and zonula occludens-1 expression was verified to be significantly lower in oral lichen planus. Furthermore, correlation analyses showed that decreased occludin expression was positively related to oral lichen planus severity., Conclusion: Decreased expression of TJ barrier proteins may be associated with the development of oral lichen planus., (© 2024 Wiley Periodicals LLC.)

Background: The role of Claudin-1 in tongue squamous cell carcinoma (TSCC) metastasis needs further clarification, particularly its impact on cell migration. Herein, our study aims to investigate the role of Claudin-1 in TSCC cell migration and its underlying mechanisms., Methods: 36 TSCC tissue samples underwent immunohistochemical staining for Claudin-1. Western blotting and immunofluorescence analyses were conducted to evaluate Claudin-1 expression and distribution in TSCC cells. Claudin-1 knockdown cell lines were established using short hairpin RNA transfection. Migration effects were assessed through wound healing assays. Furthermore, the expression of EMT-associated molecules was measured via western blotting., Results: Claudin-1 expression decreased as TSCC malignancy increased. Adenosine monophosphate-activated protein kinase (AMPK) activation led to increased Claudin-1 expression and membrane translocation, inhibiting TSCC cell migration and epithelial-mesenchymal transition (EMT). Conversely, Claudin-1 knockdown reversed these inhibitory effects on migration and EMT caused by AMPK activation., Conclusions: Our results indicated that AMPK activation suppresses TSCC cell migration by targeting Claudin-1 and EMT pathways., (© 2024 The Authors. Animal Models and Experimental Medicine published by John Wiley & Sons Australia, Ltd on behalf of The Chinese Association for Laboratory Animal Sciences.)

The disorder of the "gut-kidney axis" exacerbates renal function decline in chronic kidney disease (CKD), and current CKD therapy is insufficient to address this issue. Hirudin has a palliative effect on the decline of renal function. However, whether hirudin can delay CKD by regulating the "intestinal renal axis" disorder remains unclear. Unilateral ureteral ligation (UUO) induced CKD rat model, and the rats were treated with bifidobacterium and hirudin for 36 days. After 14 and 36 days of modeling, kidney and colon tissues were collected for pathology, western blot (WB) assay, and quantitative real-time PCR (qPCR) detection. Serum samples were collected for renal function testing. Fecal samples were used for 16S rRNA sequencing and research on fecal bacterial transplantation. Lipopolysaccharide combine with adenosine 5'-triphosphate (LPS + ATP)-induced intestinal epithelial cell injury was treated with a nod-like receptor pyrin domain-associated protein 3 (NLRP3) inhibitor and hirudin. Protein expression was detected using WB and qPCR. The kidneys and colons of the CKD rats exhibited varying degrees of lesions. Creatinine (CRE), blood urea nitrogen (BUN), N-acetyl-β-D-glucosidase (NAG) enzyme, and serum uremic toxins were elevated. The expression of claudin-1 and occludin was decreased, NLRP3 inflammatory-related proteins were increased, and the gut microbiota was disrupted. These pathological changes were more pronounced after 36 days of modeling. Meanwhile, high-dose hirudin treatment significantly improved these lesions and restored the intestinal flora to homeostasis in CKD rats. In vitro, hirudin demonstrated comparable effects to NLRP3 inhibitors by upregulating claudin-1 and occludin expression, and downregulating NLRP3 inflammatory-related proteins expression. The dysbiosis of the gut microbiota and impaired intestinal epithelial barrier function in CKD are associated with renal dysfunction in CKD. Hirudin delays the progression of CKD by regulating the disorder of the "gut-kidney axis" and inhibiting the activation of the NLRP3-ASC-caspase-1 pathway., (© 2024. The Author(s).)

Objective: To investigate the effect and molecular mechanism of isolongifolene (ISO) on the apoptosis of intestinal epithelial cells and 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced Crohn's disease (CD)-like colitis in mice., Methods: In the animal experiments, mice were randomly assigned to the wild type (WT) group, TNBS group and TNBS+ISO group, with 8 mice in each group. Colitis models of mice were established in the TNBS group and the TNBS+ISO group by rectal injection of TNBS. After modeling, the mice in the TNBS+ISO group were given ISO intervention via intragastric gavage (10 mg/kg), and the other two groups were given the same amount of normal saline via intragastric gavage. The mice were sacrificed on the 7th day. The changes in body mass, disease activity scores (DAI), and the colon length of mice were measured, and transepithelial electrical resistance (TEER) of the colon tissues was determined. The score of colon inflammation was calculated according to HE staining. The levels of intestinal mucosal inflammatory factors, including tumor necrosis factor alpha (TNF-α), interferon (IFN)-γ, interleukin (IL)-1β, and IL-6, were measured by RT-PCR and ELISA. The apoptosis of colon tissue cells was determined by TUNEL assay. The expressions of apoptotic proteins (cleaved caspase-3/caspase-3 and Bax), an anti-apoptotic protein (Bcl-2), and tight junction proteins (ZO-1 and claudin-1) were detected by Western blot and immunofluorescence. In the cell experiment, TNF-α was used to induce intestinal epithelial cell Caco-2 apoptosis model, which was treated with ISO. Then, intervention with the AMPK inhibitor Compound C was given. TUNEL assay, Western blot assay, and immunofluorescence assay were performed to measure apoptosis and the expression of apoptosis proteins in the Caco-2 cells. Gene Ontology (GO) enrichment analysis was performed to predict the biological function of ISO. Then, the mechanism involved was verified by examination of the mice and Caco-2 cells. Western blot was performed to determine the expression levels of p-AMPK/AMPK and p-PGC1α in the colon tissues from the mice of different groups and Caco-2 cells. The apoptosis of the cells was determined by TUNEL assay., Results: According to the results of the animal experiment, ISO could alleviate experimental colitis and intestinal barrier dysfunction, leading to improvements in body mass loss, colon length shortening, DAI score, inflammatory rating, and TEER values (all P <0.05) in mice. Furthermore, ISO decreased the expression of pro-inflammatory factors TNF-α, IFN-γ, IL-1β, and IL-6 and increased the expression of the tight junction proteins ZO-1 and claudin-1 (all P <0.05). In the cell experiment, in a TNF-α-induced intestinal epithelial cell model, ISO was also found to protect intestinal barrier against damage. ISO reduced the proportion of apoptotic intestinal epithelial cells, reduced the expression of cleaved-caspase-3/caspase-3 and Bax, and upregulated the level of Bcl-2 (all P <0.05). GO enrichment predictive analysis showed that the role of ISO in improving CD-like enteritis might be associated with the negative regulation of apoptosis. Verification of the mechanism showed that the expression of p-AMPK and p-PGC1α in the mice colon tissue was significantly upregulated after ISO intervention ( P <0.05). In contrast, the AMPK inhibitor Compound C increased the apoptosis rate of ISO-treated Caco-2 cells and decreased the relative expression levels of ZO-1 and claudin-1 ( P <0.05)., Conclusion: ISO reduces intestinal epithelial cell apoptosis at least in part by activating AMPK/PGC1α signaling pathway, thereby alleviating TNBS-induced intestinal barrier dysfunction and CD-like colitis in mice., Competing Interests: 利益冲突　所有作者均声明不存在利益冲突, (© 2024《四川大学学报（医学版）》编辑部 版权所有Copyright ©2024 Editorial Office of Journal of Sichuan University (Medical Sciences).)

Colorectal cancer (CRC) is the third-largest cancer worldwide. Lactobacillus can regulate the intestinal barrier and gut microbiota. However, the mechanisms of Lactobacillus that alleviate CRC remained unknown. This study aimed to explore the regulatory effect of Lactobacillus plantarum on CRC and its potential mechanism. CCFM8661 treatment significantly ameliorated CRC compared with phosphate-buffered solution (PBS) treatment in Apc Min/+ mice. In addition, conjugated linoleic acid (CLA) was proved to be the key metabolite for CCFM8661 in ameliorating CRC by molecular biology techniques. Peroxisome proliferator-activated receptor γ (PPAR-γ) was proved to be the key receptor in ameliorating CRC by inhibitor intervention experiments. Moreover, supplementation with CCFM8661 ameliorated CRC by producing CLA to inhibit NF-κB pathway and pro-inflammatory cytokines, up-regulate ZO-1, Claudin-1, and MUC2, and promote tumor cell apoptosis in a PPAR-γ-dependent manner. Metagenomic analysis showed that CCFM8661 treatment significantly increased Odoribacter splanchnicus , which could ameliorate CRC by repairing the intestinal barrier. Clinical results showed that intestinal CLA, butyric acid, PPAR-γ, and Lactobacillus were significantly decreased in CRC patients, and these indicators were significantly negatively correlated with CRC. CCFM8661 alleviated CRC by ameliorating the intestinal barrier through the CLA-PPAR-γ axis. These results will promote the development of dietary probiotic supplements for CRC.

Claudin-1 (CLDN1) is highly expressed in human lung adenocarcinoma-derived A549 cells and is involved in the augmentation of chemoresistance. However, the mechanism of chemoresistance is not fully understood. In the tumor microenvironment, cancer cells are exposed to stress conditions such as hypoxia and malnutrition. Here, we investigated the effect of CLDN1 expression on amino acid (AA) flux and chemoresistance using A549 cells. The expression of L-type AA transporters, LAT1 and LAT3, was decreased by CLDN1 silencing in A549 spheroids. A reduction in extracellular AA concentration increased the expression of these AA transporters in two-dimensional (2D) cultured cells. The paracellular AA flux except for Ser, Thr, Tyr, Ala, and Gly was enhanced by CLDN1 silencing. These results suggest that CLDN1 forms a paracellular barrier to some AAs, leading to the elevation of LAT1/3 expression in spheroids. The production of reactive oxygen species in the mitochondria and cytosol was decreased by CLDN1 silencing in spheroids, resulting in downregulation of the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its target antioxidant genes. CLDN1 silencing enhanced the cytotoxicity of anticancer drugs including doxorubicin and cisplatin, which was blocked by sulforaphane, an inducer of Nrf2 signaling. Similarly, the anticancer-induced toxicity was enhanced by Nrf2 silencing. In 2D cultured cells, the anticancer-induced toxicity was attenuated by AA deficiency and sulforaphane. We suggest that CLDN1 forms an AA barrier in spheroids, leading to the augmentation of Nrf2-dependent chemoresistance in A549 cells., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: It has been reported that High-Fructose (HF) consumption, considered one of the etiological factors of Metabolic Syndrome (MetS), causes changes in the gut microbiota and metabolic disorders. There is limited knowledge on the effects of metformin in HF-induced intestinal irregularities in male and female rats with MetS., Objectives: In this study, we investigated the sex-dependent effects of metformin treatment on the gut microbiota, intestinal Tight Junction (TJ) proteins, and inflammation parameters in HF-induced MetS., Methods: Fructose was given to the male and female rats as a 20% solution in drinking water for 15 weeks. Metformin (200 mg/kg) was administered by gastric tube once a day during the final seven weeks. Biochemical, histopathological, immunohistochemical, and bioinformatics analyses were performed. Differences were considered statistically significant at p < 0.05., Results: The metformin treatment in fructose-fed rats promoted glucose, insulin, Homeostasis Model Assessment of Insulin Resistance Index (HOMA-IR), and Triglyceride (TG) values in both sexes. The inflammation score was significantly decreased with metformin treatment in fructose-fed male and female rats (p < 0.05). Moreover, metformin treatment significantly decreased Interleukin-1 Beta (IL-1β) and Tumor Necrosis Factor-Alpha (TNF-α) in ileum tissue from fructose-fed males (p < 0.05). Intestinal immunoreactivity of Occludin and Claudin-1 was increased with metformin treatment in fructose-fed female rats. HF and metformin treatment changed the gut microbial composition. Firmicutes/Bacteroidetes (F/B) ratio increased with HF in females. In the disease group, Bifidobacterium pseudolongum; in the treatment group, Lactobacillus helveticus and Lactobacillus reuteri are the prominent species in both sexes. When the male and female groups were compared, Akkermansia muciniphila was prominent in the male treatment group., Conclusion: In conclusion, metformin treatment promoted biochemical parameters in both sexes of fructose-fed rats. Metformin showed a sex-dependent effect on inflammation parameters, permeability factors, and gut microbiota. Metformin has partly modulatory effects on fructose-induced intestinal changes., Competing Interests: Declarations Ethical approval This study was approved by Gazi University Animal Experiments Local Ethics Committee with the decision numbered G.U.ET-18.034. Conflict of interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the study reported in this paper., (© 2024. The Author(s).)

Background: Early weaning is prone to damage intestinal barrier function, resulting in diarrhea, whereas rutin, as a natural flavonoid with multiple biological functions, shows potential in piglets. Therefore, the effects of dietary rutin on growth, antidiarrheal, barrier function, antioxidant status and cecal microbiota of weaned piglets were investigated with the control group (CON) (basal diet) and Rutin (basal diet+500 mg kg -1 rutin) groups fed for 14 days., Results: The results showed that dietary 500 mg kg -1 rutin significantly decreased diarrhea index, serum diamine oxidase activity and total aerobic bacterial population in mesenteric lymph nodes, whereas it significantly increased the gain-to-feed ratio (G:F) and serum growth hormone content, jejunal villus height and villus height to crypt depth ratio, and also enhanced jejunal claudin-1 and zonula occludens-1 mRNA and protein expression. Meanwhile, dietary rutin significantly decreased inflammation-associated mRNA expression, malondialdehyde (MDA) content, swollen mitochondrial number and mitochondrial area in the jejunum, whereas it increased the total superoxide dismutase (T-SOD) and glutathione peroxidase activities and activated the Nrf2 signaling pathway. Moreover, dietary rutin significantly increased Firmicutes abundance and decreased Campylobacterota abundance, which were closely associated with the decreased diarrhea index and MDA content or increased Claudin-1 expression and T-SOD activity., Conclusion: Dietary 500 mg kg -1 rutin increased G:F by improving intestinal morphology, and alleviated diarrhea by enhancing intestinal barrier, which might be associated with the enhanced antioxidant capacity via activating the Nrf2/Keap1 signaling pathway and the improved cecal microbial composition in weaned piglets. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)

Recent studies point to intestinal permeability as an important factor in the establishment and development of rheumatoid arthritis (RA). Tight junctions (TJs) play a major role in intestinal homeostasis. The alteration of this homeostasis is related to RA. Furthermore, RA patients present dysbiosis and a lower microbiota diversity compared to healthy individuals. A cross-sectional study including RA patients and sex- and age-matched healthy controls was performed. The quantification of TJ proteins was carried out by ELISA. Gut microbiota was evaluated by NGS platform Ion Torrent S. The inflammatory variables included were DAS28, CRP, inflammatory cytokines (IL-6, IL-1, TNF-α) and oxidised LDL. Claudin-1 levels showed significant differences between groups. Results evidenced a correlation between claudin-1 values and age ( r : -0.293; p < 0.05), IL6 ( r : -0.290; p < 0.05) and CRP ( r : -0.327; p < 0.05), and between zonulin values and both age ( r : 0.267; p < 0.05) and TNFα ( r : 0.266; p < 0.05). Moreover, claudin-1 and CRP levels are related in RA patients ( β : -0.619; p : 0.045), and in patients with high inflammatory activity, the abundance of the genus Veillonella is positively associated with claudin-1 levels ( β : 39.000; p : 0.004).

This study aims to explore the improvement effect of Sijunzi Decoction on intestinal barrier in diabetic mice. A type 2 diabetes mellitus(T2DM) model was established in C57BL/6J mice by feeding them with high-sugar and high-fat diet combined with streptozotocin(STZ). The T2DM mice were randomly divided into a control group, a T2DM group, a donepezil(DON) group, a rosiglitazone(RGZ) group, and Sijunzi Decoction groups(7. 5, 15, and 30 g·kg~(-1)), and orally administered for six weeks. The body weight and fasting plasma glucose(FBG) of mice were recorded. Fasting plasma insulin(FINS) and insulin resistance index(HOMA-IR) were observed to assess insulin resistance(IR). Intestinal flora and levels of serotonin(5-HT), lipopolysaccharide(LPS), and short-chain fatty acids(SCFAs) in serum were analyzed. Changes in colonic structure and tight junction proteins occludin, claudin-1,and ZO-1 were observed through HE staining and immunohistochemistry. Spontaneous alternation test was conducted to observe the effect on spatial memory ability. Compared with the results in the control group, FBG and HOMA-IR in the T2DM group were significantly increased(P&lt; 0. 01); species richness index(Sobs index), Shannon diversity index(Shannon index), and species abundance estimate index(Chao index) were decreased; LPS was significantly increased(P&lt; 0. 001), while the levels of 5-HT,SCFAs, occludin, claudin-1, and ZO-1 were significantly decreased(P&lt; 0. 01), indicating impaired colonic barrier function;spontaneous alternation accuracy was significantly decreased(P&lt;0. 05). After 6 weeks of Sijunzi Decoction treatment, compared with the results in the T2DM group, FBG and HOMA-IR in the Sijunzi Decoction 15 g·kg~(-1) group were significantly decreased(P&lt;0. 01);Sobs index, Shannon index, and Chao index were increased; LPS was significantly decreased(P&lt;0. 01), while the levels of 5-HT,SCFAs, occludin, claudin-1, and ZO-1 were significantly increased(P&lt; 0. 05), indicating improved colonic barrier function;spontaneous alternation accuracy was increased(P&lt;0. 001). In conclusion, Sijunzi Decoction has the effect of improving intestinal barrier in diabetic mice.

Introduction: Peritumoral brain edema (PTBE) has been widely reported with many brain tumors, especially with glioma. Since the blood-brain barrier (BBB) is essential for maintaining minimal permeability, any alteration in the interaction of BBB components, specifically in astrocytes and tight junctions (TJ), can result in disrupting the homeostasis of the BBB and making it severely leaky, which subsequently generates edema., Objective: This study aimed to evaluate the functional gliovascular unit of the BBB by examining changes in the expression of claudin (CLDN) genes and the expression of transient receptor potential (TRP) membrane channels, additionally to define the correlation between their expressions. The evaluation was conducted using in vitro spheroid swelling models and tumor samples from glioma patients with PTBE., Results: The results of the spheroid model showed that the genes TRPC3, TRPC4, TRPC5, and TRPV1 were upregulated in glioma cells either wild-type isocitrate dehydrogenase 1 (IDH1) or the IDH1 R132H mutant, with or without NaCl treatment. Furthermore, TRP genes appeared to adversely correlate with the up regulation of CLDN1, CLDN3, and CLDN5 genes. Besides, the upregulation of TRPC1 and TRPC4 in IDH1mt-R132H glioma cells. On the other hand, the correlation analysis revealed different correlations between different proteins in PTBE. CLDN1 exhibits a slight positive correlation with CLDN3. Similarly, TRPV1 displays a slight positive correlation with TRPC1. In contrast, TRPC4 shows a slight negative correlation with TRPC5. On the other hand, TRPC3 demonstrates a slight positive correlation with TRPC5, while the non-PTBE analysis highlights a moderate positive correlation between CLDN1 and TRPM4 while CLDN3 exhibits a moderate negative correlation with TRPC4. Additionally, CLDN5 demonstrates a slight negative correlation with TRPC4 but a moderate positive correlation with TRPC3. Furthermore, TRPC1 have a slight negative correlation with TRPV1, TRPC3 exhibiting a slight positive correlation with TRPC4, and TRPV1 showing a slight negative correlation with TRPC5., Conclusion: As a conclusion, the current study provided evidence of a slight negative correlation between TRPs and CLDN gene expression in PTBE patients and confirmatory results with some of the genes in cell model of edema., (© 2024 The Author(s). Cancer Medicine published by John Wiley & Sons Ltd.)

Purpose: This study aimed to investigate the impact of hepatocyte growth factor (HGF) on colonic morphology and gut microbiota in a rat model of short bowel syndrome (SBS)., Methods: SD rats underwent jugular vein catheterization for total parenteral nutrition (TPN) and 90% small bowel resection [TPN + SBS (control group) or TPN + SBS + intravenous HGF (0.3 mg/kg/day, HGF group)]. Rats were harvested on day 7. Colonic morphology, gut microflora, tight junction, and Toll-like receptor-4 (TLR4) were evaluated., Results: No significant differences were observed in the colonic morphological assessment. No significant differences were observed in the expression of tight junction-related genes in the proximal colon. However, the claudin-1 expression tended to increase and the claudin-3 expression tended to decrease in the distal colon of the HGF group. The Verrucomicrobiota in the gut microflora of the colon tended to increase in the HGF group. The abundance of most LPS-producing microbiota was lower in the HGF group than in the control group. The gene expression of TLR4 was significantly downregulated in the distal colon of the HGF group., Conclusion: HGF may enhance the mucus barrier through the tight junctions or gut microbiome in the distal colon., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Human breast milk promotes maturation of the infant gastrointestinal barrier, including the promotion of mucus production. In the quest to produce next generation infant milk formula (IMF), we have produced IMF by membrane filtration (MEM-IMF). With a higher quantity of native whey protein, MEM-IMF more closely mimics human breast milk than IMF produced using conventional heat treatment (HT-IMF). After a 4-week dietary intervention in young pigs, animals fed a MEM-IMF diet had a higher number of goblet cells, acidic mucus and mucin-2 in the jejunum compared to pigs fed HT-IMF (P < 0.05). In the duodenum, MEM-IMF fed pigs had increased trypsin activity in the gut lumen, increased mRNA transcript levels of claudin 1 in the mucosal scrapings and increased lactase activity in brush border membrane vesicles than those pigs fed HT-IMF (P < 0.05). In conclusion, MEM-IMF is superior to HT-IMF in the promotion of mucus production in the young gut., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Bronchopulmonary dysplasia (BPD) remains a significant challenge in neonatal care, the pathogenesis of which potentially involves altered lipid metabolism. Given the critical role of lipids in lung development and the injury response, we hypothesized that specific lipid species could serve as therapeutic agents in BPD. This study aimed to investigate the role of the lipid Phosphatidylcholine (PC) (16:0/14:0) in modulating BPD pathology and to elucidate its underlying mechanisms of action. Our approach integrated in vitro and in vivo methodologies to assess the effects of PC (16:0/14:0) on the histopathology, cellular proliferation, apoptosis, and molecular markers in lung tissue. In a hyperoxia-induced BPD rat model, we observed a reduction in alveolar number and an enlargement in alveolar size, which were ameliorated by PC (16:0/14:0) treatment. Correspondingly, in BPD cell models, PC (16:0/14:0) intervention led to increased cell viability, enhanced proliferation, reduced apoptosis, and elevated surfactant protein C (SPC) expression. RNA sequencing revealed significant gene expression differences between BPD and PC (16:0/14:0) treated groups, with a particular focus on Cldn1 (encoding claudin 1), which was significantly enriched in our analysis. Our findings suggest that PC (16:0/14:0) might protect against hyperoxia-induced alveolar type II cell damage by upregulating CLDN1 expression, potentially serving as a novel therapeutic target for BPD. This study not only advances our understanding of the role of lipids in BPD pathogenesis, but also highlights the significance of PC (16:0/14:0) in the prevention and treatment of BPD, offering new avenues for future research and therapeutic development., Competing Interests: Declaration of Competing Interest All authors declare no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The time for diabetic nephropathy (DN) to progress from mild to severe is long. Thus, methods to continuously repress DN are required to exert long-lasting effects mediated through epigenetic regulation. In this study, we demonstrated the ability of nicotinamide adenine dinucleotide (NAD) and its metabolites to reduce albuminuria through Sirt1- or Nampt-dependent epigenetic regulation. We previously reported that proximal tubular Sirt1 was lowered before glomerular Sirt1. Repressed glomerular Sirt1 was found to epigenetically elevate Claudin-1. In addition, we reported that proximal tubular Nampt deficiency epigenetically augmented TIMP-1 levels in Sirt6-mediated pathways, leading to type-IV collagen deposition and diabetic fibrosis. Altogether, we propose that the Sirt1/Claudin-1 axis may be crucial in the onset of albuminuria at the early stages of DN and that the Nampt/Sirt6/TIMP-1 axis promotes diabetic fibrosis in the middle to late stages of DN. Finally, administration of NMN, an NAD precursor, epigenetically potentiates the regression of the onset of DN to maintain Sirt1 and repress Claudin-1 in podocytes, suggesting the potential use of NAD metabolites as epigenetic medications for DN., (© 2024. The Authors.)

Growing evidence showed the capacity of (poly)phenols to exert a protective role on intestinal health. Nevertheless, the existing findings are still heterogeneous and the underlying mechanisms remain unclear. This study investigated the potential benefits of a red raspberry ( Rubus idaeus ) powder on the integrity of the intestinal barrier, focusing on its ability to mitigate the effects of tumor necrosis factor-α (TNF-α)-induced intestinal permeability. Human colorectal adenocarcinoma cells ( i.e. , Caco-2 cells) were used as a model to assess the impact of red raspberry on intestinal permeability, tight junction expression, and oxidative stress. The Caco-2 cells were differentiated into polarized monolayers and treated with interferon-γ (IFN-γ) (10 ng mL -1 ) for 24 hours, followed by exposure to TNF-α (10 ng mL -1 ) in the presence or absence of red raspberry extract (1-5 mg mL -1 ). The integrity of the intestinal monolayer was evaluated using transepithelial electrical resistance (TEER) and fluorescein isothiocyanate-dextran (FITC-D) efflux assay. Markers of intestinal permeability (claudin-1, occludin, and zonula occludens-1 (ZO-1)) and oxidative stress (8-hydroxy-2-deoxyguanosine (8-OHdG) and protein carbonyl) were assessed using ELISA kits. Treatment with red raspberry resulted in a significant counteraction of TEER value loss (41%; p < 0.01) and a notable reduction in the efflux of FITC-D (-2.5 times; p < 0.01). Additionally, red raspberry attenuated the levels of 8-OHdG (-48.8%; p < 0.01), mitigating the detrimental effects induced by TNF-α. Moreover, red raspberry positively influenced the expression of the integral membrane protein claudin-1 (+18%; p < 0.01), an essential component of tight junctions. These findings contribute to the growing understanding of the beneficial effects of red raspberry in the context of the intestinal barrier. The effect of red raspberry against TNF-α-induced intestinal permeability observed in our in vitro model suggests, for the first time, its potential as a dietary strategy to promote gastrointestinal health.

Hypoxia plays an important role in the pathological process of bladder outlet obstruction. Previous research has mostly focused on the dysfunction of bladder smooth muscle cells, which are directly related to bladder contraction. This study delves into the barrier function changes of the urothelial cells under exposure to hypoxia. Results indicated that after a 5-day culture, SV-HUC-1 formed a monolayer and/or bilayer of cell sheets, with tight junction formation, but no asymmetrical unit membrane was observed. qPCR and western blotting revealed the expression of TJ-associated proteins (occludin, claudin1 and ZO-1) was significantly decreased in the hypoxia group in a time-dependent manner. No expression changes were observed in uroplakins. When compared to normoxic groups, immunofluorescent staining revealed a reduction in the expression of TJ-associated proteins in the hypoxia group. Transepithelial electrical resistance (TEER) revealed a statistically significant decrease in resistance in the hypoxia group. Fluorescein isothiocyanate-conjugated dextran assay was inversely proportional to the results of TEER. Taken together, hypoxia down-regulates the expression of TJ-associated proteins and breaks tight junctions, thus impairing the barrier function in human urothelial cells., (© 2024 The Author(s). Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

Human microglia (HMC) are stress-induced inflammatory cells of the retina. It is unknown whether severe hypoglycaemia causes inflammation in microglia, affects the permeability of human retinal microvascular endothelial cells (HRMECs), and causes retinal damage. This study aimed to explore the effects of severe hypoglycaemia on retinal microglial inflammation and endothelial cell permeability and evaluate the damage caused by hypoglycaemia to the retina. The CCK-8 assay was used to measure cell viability. Western blotting was used to detect IL-1β, IL-6, TNF- α, claudin-1, and occludin expression. ELISA was used to detect IL-1β, IL-6, and TNF- α. Transmission electron microscopy (TEM) and haematoxylin and eosin staining were used to observe the retinal structure. Immunohistochemistry and immunofluorescence staining assays were also used to detect IL-1β, IL-6, TNF- α, claudin-1, and occludin expression. Severe hypoglycaemia promoted inflammation in HMC3 cells. Inflammation caused by hypoglycaemia leads to the decreased expression of tight junction proteins. In vivo, severe hypoglycaemia induced structural damage to the retina, increased the expression of inflammatory factors, and decreased the expression of tight junction proteins. Our results suggest that severe hypoglycaemia leads to acute retinal inflammation, affecting the permeability of HRMECs and causing retinal damage., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Microplastics, which are tiny plastic particles less than 5 mm in diameter, are widely present in the environment, have become a serious threat to aquatic life and human health, potentially causing ecosystem disorders and health problems. The present study aimed to investigate the effects of microplastics, specifically microplastics-polystyrene (MPs-PS), on the structural integrity, gene expression related to tight junctions, and gut microbiota in mice. A total of 24 Kunming mice aged 30 days were randomly assigned into four groups: control male (CM), control female (CF), PS-exposed male (PSM), and PS-exposed female (PSF)(n = 6). There were significant differences in villus height, width, intestinal surface area, and villus height to crypt depth ratio (V/C) between the PS group and the control group(C) (p <0.05). Gene expression analysis demonstrated the downregulation of Claudin-1, Claudin-2, Claudin-15, and Occludin, in both duodenum and jejunum of the PS group (p < 0.05). Analysis of microbial species using 16S rRNA sequencing indicated decreased diversity in the PSF group, as well as reduced diversity in the PSM group at various taxonomic levels. Beta diversity analysis showed a significant difference in gut microbiota distribution between the PS-exposed and C groups (R2 = 0.113, p<0.01), with this difference being more pronounced among females exposed to MPs-PS. KEGG analysis revealed enrichment of differential microbiota mainly involved in seven signaling pathways, such as nucleotide metabolism(p<0.05). The relative abundance ratio of transcriptional pathways was significantly increased for the PSF group (p<0.01), while excretory system pathways were for PSM group(p<0.05). Overall findings suggest that MPs-PS exhibit a notable sex-dependent impact on mouse gut microbiota, with a stronger effect observed among females; reduced expression of tight junction genes may be associated with dysbiosis, particularly elevated levels of Prevotellaceae., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Su et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objective: To investigate the role of the EGFR/MAPK signaling pathway in PM2.5 in promoting the MUC5AC hypersecretion in airway and exacerbating airway inflammation., Methods: By establishing rat model exposed to PM2.5, overexpressing miR-133b-5p and Claudin1, the content of IL-1 and TNF-α in serum were detected by ELISA, the pathology of lung tissue was observed by HE staining, p-EGFR, Claudin1, MUC5AC, p-ERK1/2, p-JNK, p-p38 in rats lung tissue were detected by immunohistochemical and WB, the expression level of miR-133b-5p in rats lung tissue were detected by qPCR., Results: After the rats were exposed to PM2.5, the content of inflammatory factors in serum increased, the inflammatory damage of lung tissues occurred, the expression of miR-133b-5p was down-regulated, and the expression of MUC5AC protein was increased. The ELISA test results showed that the expression of IL-1 and TNF-α in the model group was significantly higher than that in the control group, and the model +AG1478 treatment group was down-regulated compared with the model group, and the +miR-133b-5p agomir treatment group was significantly lower than that in the control group, the model group and the model +Claudin1 overexpression blank load group, and the model +Claudin1 overexpression group was down-regulated compared with the model group and the model +Claudin1 overexpression blank load group. The protein detection results showed that the expression of p-EGFR, MUC5AC, p-ERK1/2, p-JNK and p-p38 proteins was increased and the expression of Claudin1 protein was decreased in the model group compared with the control group. In the model + AG1478 treatment group, model + miR-133b-5p agomir treatment group and model + Claudin1 overexpression group, compared with the model group, p-EGFR, MUC5AC, p-ERK1/2, p-JNK, p-p38 protein expression was down-regulated, and Claudin1 protein expression was up-regulated., Conclusions: PM2.5 inhibited the expression of miR-133b-5p to activate the EGFR/MAPK signal pathway, induce the hypersecretion of MUC5AC, thus aggravating PM2.5-related airway inflammation in rats.

Objectives: To investigate the effect of Peitu Yimu(strengthening spleen and soothing liver) acupuncture on intestinal mucosal barrier function and corticotropin-releasing factor (CRF)/CRF receptor 1 (CRFR1) pathway in rats with diarrhea-predominant irritable bowel syndrome (IBS-D), so as to explore its underlying mechanism in alleviating IBS-D., Methods: Forty female SD rats were randomly divided into blank, model, electroacupuncture (EA), and agonist groups, with 10 rats in each group. Except for the blank group, rats in the other groups were given folium sennae infusion by gavage combined with chronic unpredictable mild stress to establish IBS-D model. Rats in the EA group received acupuncture at "Tianshu"(ST25) and EA at "Zusanli"(ST36) and "Taichong"(LR3) (2 Hz/15 Hz) on one side for 20 min, with the side chosen alternately every other day, for 14 days after modeling. Rats in the agonist group received acupuncture 30 min after intravenous injection of CRFR1 agonist urocortin, with the same manipulation method and time as the EA group. Before and after intervention, visceral pain threshold and stool Bristol scores were measured. Elevated plus maze test and open field test were used to detect anxiety and depression like behavior of rats. ELISA was used to detect the contents of CRF and CRFR1 in rats serum. Immunohistochemistry was used to detect the positive expressions of CRF, CRFR1, zonula occludens protein 1(ZO-1), occlusal protein(Occludin), and closure protein 1 (Claudin-1) in colon tissue., Results: Compared with the blank group, the visceral pain threshold, open arm time percentage (OT%), total distance of movement in the open field test, and positive expression of ZO-1, Occludin, and Claudin-1 in colon were decreased ( P <0.01, P <0.05), while Bristol stool scores, serum CRF and CRFR1 contents, and positive expressions of CRF and CRFR1 in colon were increased ( P <0.01) in the model group. After intervention and compared with the model group, the visceral pain threshold, OT%, total distance of movement in the open field test, and positive expressions of ZO-1, Occludin, and Claudin-1 in colon were increased ( P <0.05, P <0.01), while Bristol stool scores, serum CRF and CRFR1 contents, and positive expressions of CRF and CRFR1 in colon were decreased ( P <0.01) in the EA group；the Bristol stool scores, serum CRF content, and CRF positive expression in colon were significantly decreased in the agonist group ( P <0.01)., Conclusions: Peitu Yimu acupuncture can significantly improve visceral hypersensitivity and anxiety-depression state in IBS-D rats. Its mechanism may be related to the inhibition of CRF/CRFR1 pathway and restoration of intestinal tight junction protein expressions.

Background: Food allergies could be regulated via Th1/Th2 balance, intestinal oxidative stress and inflammation, which were considered as food allergy-associated factors. Medicine-food homologous materials (MFHM) were considered as a significant factor with respect to preventing human diseases. To evaluate the associations between MFHM and food allergy-associated factors, two types of MFHM with the remarkable function of anti-oxidation and anti-inflammation, Gardeniae fructus (Gar) and Sophorae glos (Sop), were chosen., Results: By constructing an H 2 O 2 -induced oxidative stress model of Caco-2 cells and an intestinal inflammatory cell model of Caco-2 cells with tumor necrosis factor-α and interleukin (IL)-13, the contents of anti-oxidative enzymes (SOD and GSH), inflammatory factor (IL-8) and tight junction proteins (zonula occludens-1, occludin and claudin-1) in Caco-2 cells were determined. Moreover, the anti-allergic effects of digestive Sop and Gar were evaluated by measuring the levels of Th1/Th2/Treg cytokines in the spleen cells of sensitized mice. The results showed that the SOD and GSH were obviously increased and the gene and protein expression of IL-8 and claudin-1 were improved with the incubation of digested Sop. Th2 cytokine was reduced and Th1/Th2 balance was promoted on coincubation with ovalbumin (OVA) and digested Sop in the splenocytes. However, the digested Gar had no effect., Conclusion: The digested Sop not only had suppressive effects on intestinal oxidative stress and inflammation, but also had regulative effects on Th1/Th2 balance. This finding demonstrated that not all of the MFHM with anti-oxidant and anti-inflammatory effects have anti-allergic activities. The present study may be contributing toward establishing a screening model to identify the anti-allergic MFHM. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)

The transmembrane protein claudin-1 is critical for formation of the epidermal barrier structure called tight junctions (TJ) and has been shown to be important in multiple disease states. These include neonatal ichthyosis and sclerosing cholangitis syndrome, atopic dermatitis and various viral infections. To develop a model to investigate the role of claudin-1 in different disease settings, we used CRISPR/Cas9 to generate human immortalized keratinocyte (KC) lines lacking claudin-1 (CLDN1 KO). We then determined whether loss of claudin-1 expression affects epidermal barrier formation/function and KC differentiation/stratification. The absence of claudin-1 resulted in significantly reduced barrier function in both monolayer and organotypic cultures. CLDN1 KO cells demonstrated decreases in gene transcripts encoding the barrier protein filaggrin and the differentiation marker cytokeratin-10. Marked morphological differences were also observed in CLDN1 KO organotypic cultures including diminished stratification and reduced formation of the stratum granulosum. We also detected increased proliferative KC in the basale layer of CLDN1 KO organotypic cultures. These results further support the role of claudin-1 in epidermal barrier and suggest an additional role of this protein in appropriate stratification of the epidermis., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Different levels of EspP2 expression are seen in strains of Glaesserella parasuis with high and low pathogenicity. As a potential virulence factor for G. parasuis , the pathogenic mechanism of EspP2 in infection of host cells is not clear. To begin to elucidate the effect of EspP2 on virulence, we used G. parasuis SC1401 in its wild-type form and SC1401, which was made EspP2 -deficient. We demonstrated that EspP2 causes up-regulation of claudin-1 and occludin expression, thereby promoting the adhesion of G. parasuis to host cells; EspP2 -deficiency resulted in significantly reduced adhesion of G. parasuis to cells. Transcriptome sequencing analysis of EspP2-treated PK15 cells revealed that the Rap1 signaling pathway is stimulated by EspP2. Blocking this pathway diminished occludin expression and adhesion. These results indicated that EspP2 regulates the adhesion of Glaesserella parasuis via Rap1 signaling pathway.

Objectives: To observe the effects of moxibustion on intestinal barrier function and Toll-like receptor 4 (TLR4)/nuclear factor-κB p65 (NF-κB p65) signaling pathway in obese rats and explore the mechanism of moxibustion in the intervention of obesity., Methods: Fifty-five Wistar rats of SPF grade were randomly divided into a normal group (10 rats) and a modeling group (45 rats). In the modeling group, the obesity model was established by feeding high-fat diet. Thirty successfully-modeled rats were randomized into a model group, a moxibustion group, and a placebo-control group, with 10 rats in each one. In the moxibustion group, moxibustion was applied at the site 3 cm to 5 cm far from the surface of "Zhongwan" (CV 12), with the temperature maintained at (46±1 ) ℃. In the placebo-control group, moxibustion was applied at the site 8 cm to 10 cm far from "Zhongwan" (CV 12), with the temperature maintained at (38±1) ℃. The intervention was delivered once daily for 8 weeks in the above two groups. The body mass and food intake of the rats were observed before and after intervention in each group. Using ELISA methool, the levels of serum triacylglycerol (TG), total cholesterol (TC) and lipopolysaccharide (LPS) were detected and the insulin resistance index (HOMA-IR) was calculated. HE staining was used to observe the morphology of colon tissue. The mRNA expression of zonula occludens-1 (ZO-1), Occludin, Claudin-1, TLR4 and NF-κB p65 in the colon tissue was detected by quantitative real-time PCR; and the protein expression of ZO-1, Occludin, Claudin-1, TLR4 and NF-κB p65 was detected by Western blot in the rats of each group., Results: Compared with the normal group, the body mass, food intake, the level of HOMA-IR, and the serum levels of TC, TG and LPS were increased in the rats of the model group ( P< 0.01); those indexes in the moxibustion group were all reduced when compared with the model group and the placebo-control group respectively ( P< 0.01, P< 0.05). Compared with the normal group, a large number of epithelial cells in the mucosa of colon tissue was damaged, shed, and the inflammatory cells were infiltrated obviously in the interstitium in the rats of the model group. When compared with the model group, in the moxibustion group, the damage of the colon tissue was recovered to various degrees and there were few infiltrated inflammatory cells in the interstitium, while, the epithelial injury of the colon tissue was slightly recovered and the infiltrated inflammatory cells in the interstitium were still seen in the placebo-control group. The mRNA and protein expressions of ZO-1, Occludin and Caudin-1 were decreased in the model group compared with those in the normal group ( P <0.01). When compared with the model group and the placebo-control group, the mRNA and protein expressions of these indexes were increased in the moxibustion group ( P< 0.01, P <0.05). In the model group, the mRNA and protein expressions of TLR4 and NF-κB p65 were increased when compared with those in the normal group ( P< 0.01), and the mRNA and protein expressions of these indexes were reduced in the moxibustion group when compared with those in the model group and the placebo-control group ( P <0.01)., Conclusions: Moxibustion can reduce the body mass and food intake, regulate the blood lipid and improve insulin resistance in the rats of obesity. It may be related to alleviating inflammatory response through improving intestinal barrier function and modulating the intestinal TLR4/NF-κB p65 signaling pathway.

The blood-brain barrier (BBB) and tight junction (TJ) proteins maintain the homeostasis of the central nervous system (CNS). The dysfunction of BBB allows peripheral T cells infiltration into CNS and contributes to the pathophysiology of multiple sclerosis (MS). Teriflunomide is an approved drug for the treatment of MS by suppressing lymphocytes proliferation. However, whether teriflunomide has a protective effect on BBB in MS is not understood. We found that teriflunomide restored the injured BBB in the EAE model. Furthermore, teriflunomide treatment over 6 months improved BBB permeability and reduced peripheral leakage of CNS proteins in MS patients. Teriflunomide increased human brain microvascular endothelial cell (HBMEC) viability and promoted BBB integrity in an in vitro cell model. The TJ protein claudin-1 was upregulated by teriflunomide and responsible for the protective effect on BBB. Furthermore, RNA sequencing revealed that the Wnt signaling pathway was affected by teriflunomide. The activation of Wnt signaling pathway increased claudin-1 expression and reduced BBB damage in cell model and EAE rats. Our study demonstrated that teriflunomide upregulated the expression of the tight junction protein claudin-1 in endothelial cells and promoted the integrity of BBB through Wnt signaling pathway., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Colon mucosal overexpression of reactive oxygen and nitrogen species (RONS) accelerates the development of inflammatory bowel disease (IBD) and destroys the mucosa and its barrier. IBD can be alleviated by removing RONS from the inflamed colon. The preparation of strong and efficient nanoantioxidants remains a challenge despite the development of numerous nanoantioxidants. In this paper, Zn-TA nanoparticles with fine hollow microstructure (HZn-TA) were successfully prepared and could be effectively used to treat IBD. In the first step, ZIF-8 nanoparticles were synthesized by a one-pot method. On this basis, HZn-TA nanoparticles were etched by TA, and a multifunctional nanase was developed for the treatment of IBD. RONS, including reactive oxygen species (ROS) and nitric oxide (NO), can be eliminated to increase cell survival following Hydrogen peroxide (H 2 O 2) stimulation, including reactive oxygen species (ROS) and nitric oxide (NO with hydrogen peroxide (H 2 O 2 ). In a model for preventing and delaying acute colitis, clearance of RONS has been shown to reduce intestinal inflammation in mice by reducing colon damage, proinflammatory cytokine levels, the spleen index, and body weight. Intestinal mucosal healing can be promoted by HZn-TA nanoparticles, which can upregulate zonula occludens protein 1 (ZO-1) and claudin-1 expression. Based on the results of this study, HZn-TA nanoparticles were able to effectively treat IBD with minimal adverse effects by being biocompatible, multienzyme active, and capable of scavenging RONS. Therefore, we pioneered the application of HZn-TA nanoparticles for the treatment of IBD, which are capable of clearing RONS without significant adverse effects. STATEMENT OF SIGNIFICANCE: ➢ HZn-TA nanoparticles were successfully prepared and could be effectively used to treat IBD. ➢ Intestinal mucosal healing can be promoted by HZn-TA nanoparticles, which can upregulate ZO-1 and claudin-1 expression. ➢ HZn-TA nanoparticles were able to effectively treat IBD with minimal adverse effects by being biocompatible, multienzyme active, and capable of scavenging RONS., Competing Interests: Declaration of competing interest The authors declare no competing financial interests., (Copyright © 2024 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Obstructive sleep apnea (OSA) is characterized by intermittent repeated episodes of hypoxia-reoxygenation. OSA is associated with cerebrovascular consequences. An enhanced blood-brain barrier (BBB) permeability has been proposed as a marker of those disorders. We studied in mice the effects of 1 day and 15 days intermittent hypoxia (IH) exposure on BBB function. We focused on the dorsal part of the hippocampus and attempted to identify the molecular mechanisms by combining in vivo BBB permeability (Evans blue tests) and mRNA expression of several junction proteins (zona occludens (ZO-1,2,3), VE-cadherin, claudins (1,5,12), cingulin) and of aquaporins (1,4,9) on hippocampal brain tissues. After 15 days of IH exposure we observed an increase in BBB permeability, associated with increased mRNA expressions of claudins 1 and 12, aquaporins 1 and 9. IH seemed to increase early for claudin-1 mRNA expression as it doubled with 1 day of exposure and returned near to its base level after 15 days. Claudin-1 overexpression may represent an immediate response to IH exposure. Then, after 15 days of exposure, an increase in functional BBB permeability was associated with enhanced expression of aquaporin. These BBB alterations are possibly associated with a vasogenic oedema that may affect brain functions and accelerate neurodegenerative processes.

Objective: T lymphocytes from visceral and subcutaneous white adipose tissues (vWAT and sWAT, respectively) can have opposing roles in the systemic metabolic changes associated with obesity. However, few studies have focused on this subject. Claudin-1 (CLDN1) is a protein involved canonically in tight junctions and tissue paracellular permeability. We evaluated T-lymphocyte gene expression in vWAT and sWAT and in the whole adipose depots in human samples., Methods: A Clariom D-based transcriptomic analysis was performed on T lymphocytes magnetically separated from vWAT and sWAT from patients with obesity (Cohort 1; N = 11). Expression of candidate genes resulting from that analysis was determined in whole WAT from individuals with and without obesity (Cohort 2; patients with obesity: N = 13; patients without obesity: N = 14)., Results: We observed transcriptional differences between T lymphocytes from sWAT compared with vWAT. Specifically, CLDN1 expression was found to be dramatically induced in vWAT T cells relative to those isolated from sWAT in patients with obesity. CLDN1 was also induced in obesity in vWAT and its expression correlates with genes involved in inflammation, fibrosis, and adipogenesis., Conclusion: These results suggest that CLDN1 is a novel marker induced in obesity and differentially expressed in T lymphocytes infiltrated in human vWAT as compared with sWAT. This protein may have a crucial role in the crosstalk between T lymphocytes and other adipose tissue cells and may contribute to inflammation, fibrosis, and alter homeostasis and promote metabolic disease in obesity., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of European Society of Endocrinology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objective: Disruption of the gingival epithelial barrier is often mediated by aging or the pathogen Porphyromonas gingivalis. This study examined the combined effects of aging and P. gingivalis exposure on gingival epithelial barrier molecules., Methods: In vitro experiments involved treating young- and senescence-induced primary human gingival epithelial progenitor cells (HGEPp) with P. gingivalis lipopolysaccharide (LPS). Transepithelial electrical resistance (TER) and paracellular permeability were measured. In vivo, male C57BL/6J mice aged 10 (young) and 80 (old) weeks were divided into four groups: young, old, young with P. gingivalis (Pg-Young) inoculation, and old with P. gingivalis (Pg-Old) inoculation. P. gingivalis was inoculated orally thrice a week for 5 weeks. The mice were sacrificed 30 days after the last inoculation, and samples were collected for further procedures. The junctional molecules (Claudin-1, Claudin-2, E-cadherin, and Connexin) were analyzed for mRNA expression using qRT-PCR and protein production using western blotting and immunohistochemistry. The alveolar bone loss and inflammatory cytokine levels in gingival tissues were also assessed., Results: LPS-treated senescent cells exhibited a pronounced reduction in TER, increased permeability to albumin protein, significant upregulation of Claudin-1 and Claudin-2, and significant downregulation of E-cadherin and Connexin. Furthermore, the Pg-Old group showed identical results with aging in addition to an increase in alveolar bone loss, significantly higher than that in the other groups., Conclusion: In conclusion, the host susceptibility to periodontal pathogens increases with age through changes in the gingival epithelial barrier molecules., (Copyright © 2024. Published by Elsevier B.V.)

Inulin-type fructan CP-A, a predominant polysaccharide in Codonopsis pilosula, demonstrates regulatory effects on immune activity and anti-inflammation. The efficacy of CP-A in treating ulcerative colitis (UC) is, however, not well-established. This study employed an in vitro lipopolysaccharide (LPS)-induced colonic epithelial cell model (NCM460) and an in vivo dextran sulfate sodium (DSS)-induced colitis mouse model to explore CP-A's protective effects against experimental colitis and its underlying mechanisms. We monitored the clinical symptoms in mice using various parameters: body weight, disease activity index (DAI), colon length, spleen weight, and histopathological scores. Additionally, molecular markers were assessed through enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qRT-PCR), immunofluorescence (IF), immunohistochemistry (IHC), and Western blotting assays. Results showed that CP-A significantly reduced reactive oxygen species (ROS), tumor necrosis factor-alpha (TNF-α), and interleukins (IL-6, IL-1β, IL-18) in LPS-induced cells while increasing IL-4 and IL-10 levels and enhancing the expression of Claudin-1, ZO-1, and occludin proteins in NCM460 cells. Correspondingly, in vivo findings revealed that CP-A administration markedly improved DAI, reduced colon shortening, and decreased the production of myeloperoxidase (MPO), malondialdehyde (MDA), ROS, IL-1β, IL-18, and NOD-like receptor protein 3 (NLRP3) inflammasome-associated genes/proteins in UC mice. CP-A treatment also elevated glutathione (GSH) and superoxide dismutase (SOD) levels, stimulated autophagy (LC3B, P62, Beclin-1, and ATG5), and reinforced Claudin-1 and ZO-1 expression, thereby aiding in intestinal epithelial barrier repair in colitis mice. Notably, the inhibition of autophagy via chloroquine (CQ) diminished CP-A's protective impact against colitis in vivo. These findings elucidate that CP-A's therapeutic effect on experimental colitis possibly involves mitigating intestinal inflammation through autophagy-mediated NLRP3 inflammasome inactivation. Consequently, inulin-type fructan CP-A emerges as a promising drug candidate for UC treatment., (Copyright © 2024 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.)

Objective: To investigate the protective effect of resveratrol on intestinal barrier in 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) mouse models and its mechanism for regulating TLR4/MyD88/NF-κB signaling to protect dopaminergic neurons., Methods: Fifty-two C57BL/6J mice were randomized into control group ( n = 12), MPTP group ( n =14), MPTP + resveratrol (30 mg/kg) group ( n =13), and MPTP + resveratrol (90 mg/kg) group ( n =13), and mouse models were established by intraperitoneal MPTP (30 mg/kg) injection for 7 days in the latter 3 groups. Behavioral tests were conducted to evaluate the effect of resveratrol on motor symptoms of the mice. Western blotting was used to detect the expression of TH, α -syn, ZO-1, Claudin-1, TLR4, MyD88, and NF-κB in the brain tissues of the mice. Immunohistochemistry, immunofluorescence, ELISA and transmission electron microscopy were used to verify the effect of resveratrol for suppressing inflammation and protecting the intestinal barrier., Results: Compared with those in the normal control group, the mice in MPTP group showed significant changes in motor function, number of dopaminergic neurons, neuroinflammation, levels of LPS and LBP, and expressions of tight junction proteins in the intestinal barrier. Resveratrol treatment significantly improved motor function of the PD mice ( P < 0.01), increased the number of neurons and TH protein expression ( P < 0.05), down-regulated the expressions of GFAP, Iba-1, and TLR4, lowered fecal and plasma levels of LPS and LBP ( P < 0.05), restored the expression levels of ZO-1 and Claudin-1 ( P < 0.01), and down-regulated the expressions of TLR4, MyD88, and NF-κB in the colon tissue ( P < 0.05). The mice with resveratrol treatment at 30 mg/kg showed normal morphology of the tight junction complex with neatly and tightly arranged intestinal villi., Conclusion: Resveratrol repairs the intestinal barrier by inhibiting TLR4/MyD88/NF-κB signaling pathway-mediated inflammatory response, thereby improving motor function and neuropathy in mouse models of MPTP-induced PD.

Tight junctions (TJs) are important factors constituting the physical barriers of the skin, and their suppression has been described in various conditions, such as aged skin and atopic dermatitis lesions. However, the methods for improving skin TJ function remain insufficient. Therefore, to obtain compounds that can improve TJ function, we developed a novel high-throughput screening system termed live-cell immunostaining to evaluate cell surface-localized claudin-1 (CLDN1) with high selectivity using normal human epidermal keratinocytes (NHEKs). Heparinoid and phospho-pyridoxal (p-Pyr), a metabolite of pyridoxine, were identified as hit compounds. In addition, heparinoid was strongly suggested to increase CLDN1 expression by inhibiting epidermal growth factor receptor signaling. By contrast, p-Pyr did not enhance CLDN1 expression, but it accelerated the translocation of CLDN1 to the cell surface. Finally, we confirmed that heparinoid and p-Pyr improved barrier function in NHEKs in a transepithelial electrical resistance assay. In conclusion, heparinoid and p-Pyr could potentially ameliorate skin conditions by improving TJ function., (© 2024. The Author(s).)

Scope: Torreya grandis kernel has traditionally been used to remove intestinal parasites and increases intestinal motility. However, the effect of Torreya grandis kernel oil (TKO) on constipation has not yet been investigated. Therefore, mouse model is used to investigate the effect of TKO on slow transit constipation (STC) and its possible mechanism., Methods and Results: The effects of TKO on intestinal motility of STC mice are evaluated by fecal weight, fecal water content, colon length, defecation test, and intestinal propulsion test. The mechanism of TKO alleviating STC is explored by detecting biochemical analysis, histological analysis, western blot, qRT-PCR, immunohistochemistry, and gut microbiota analysis. The results reveal that TKO effectively promotes defecation and intestinal motility, increases the level of endothelin-1, and restores the histopathological morphology of the colon under LOP pretreatment. The expression levels of occludin, claudin-1, and zonula occludens-1 (ZO-1) mRNA and protein are up-regulated in mice receiving TKO treatment. The colonic 5-hydroxytryptamine 3R/4R (5-HT3R/5-HT4R) expressions are also increased by TKO supplementation. Additionally, TKO rescues LOP-caused disorders of the gut microbiota., Conclusion: Consumption of TKO is beneficial to STC recovery, and it can alleviate LOP-induced STC by up-regulating the colonic expressions of Occludin/Claudin-1/ZO-1 and 5-HT3R/5-HT4R., (© 2023 Wiley-VCH GmbH.)

Hepatocellular carcinoma (HCC) has a high incidence and dismal prognosis, making it a significant global health burden. To change this, the development of new therapeutic strategies is imminent. The claudin (CLDN) family, as key components of tight junctions (TJs), plays an important role in the initiation and development of cancer. Dysregulated expression of CLDNs leads to loss of intercellular adhesion and aberrant cell signaling, which are closely related to cancer cell invasion, migration, and epithelial-mesenchymal transition (EMT). CLDN1, CLDN3, CLDN4, CLDN5, CLDN6, CLDN7, CLDN9, CLDN10, CLDN11, CLDN14, and CLDN17 are aberrantly expressed in HCC, which drives the progression of the disease. Consequently, they have tremendous potential as prognostic indicators and therapeutic targets. This article summarizes the aberrant expression, molecular mechanisms, and clinical application studies of different subtypes of CLDNs in HCC, with a particular emphasis on CLDN1., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Objectives: As a critical component of the epithelial barrier, tight junctions (TJs) are essential in nasal mucosa against pathogen invasion. However, the function of TJs has rarely been reported in nasal inverted papilloma (NIP). This study aims to investigate the potential factors of TJs' abnormality in NIP., Methods: We assessed the expression of ZO-1, occludin, claudin-1, claudin-3, and claudin-7 in healthy controls and NIP by real-time quantitative polymerase chain reaction and immunofluorescent staining. The correlation between TJs expression and neutrophil count, T H 1/T H 2/T H 17 and regulatory T cell biomarkers, and the proportion of nasal epithelial cells was investigated., Results: Upregulation of ZO-1, occludin, claudin-1, and claudin-7, along with downregulation of claudin-3, was found in NIP compared to control (all p < 0.05). An abnormal proportion with a lower number of ciliated cells (control vs. NIP: 37.60 vs. 8.67) and goblet cells (12.52 vs. 0.33) together with a higher number of basal cells (45.58 vs. 124.00) in NIP. Meanwhile, claudin-3 was positively correlated with ciliated and goblet cells (all p < 0.01). Additionally, neutrophils were excessively infiltrated in NIP, negatively correlated with ZO-1, but positively with claudin-3 (all p < 0.05). Furthermore, FOXP3, IL-10, TGF-β1, IL-5, IL-13, and IL-22 levels were induced in NIP (all p < 0.01). Occludin level was negatively correlated with IL-10, IL-5, IL-13, and IL-22, whereas ZO-1 was positively with TGF-β1 (all p < 0.05)., Conclusion: Nasal epithelial barrier dysfunction with TJs anomalies is commonly associated with abnormal proliferation and differentiation of epithelial cells and imbalance of immune and inflammatory patterns in NIP., Level of Evidence: NA Laryngoscope, 134:552-561, 2024., (© 2023 The American Laryngological, Rhinological and Otological Society, Inc.)

Tobacco smoke contains various carcinogenic ingredients such as nicotine, acrolein, and benzopyrene; however, their effects on cancer treatment are not fully understood. Claudin-1 (CLDN1), a component of tight junctions, is involved in the increased resistance to anticancer drugs. In this study, we found that acrolein increases the mRNA and protein levels of CLDN1 in RERF-LC-AI cells derived from human lung squamous cell carcinoma (SCC). Acrolein increased the p-extracellular signal-regulated kinase (ERK) 1/2 levels without affecting the p-Akt level. The acrolein-induced elevation of CLDN1 expression was attenuated by U0126, a mitogen-activated protein kinase kinas (MEK) inhibitor. These results indicate that the activation of MEK/ERK pathway is involved in the acrolein-induced elevation of CLDN1 expression. In a spheroid model, acrolein suppressed the accumulation and toxicity of doxorubicin (DXR), which were rescued by CLDN1 silencing. The acrolein-induced effects were also observed in lung SCC-derived EBC-1 and LK-2 cells. Acrolein also increased the expression level of nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor that regulates antioxidant and detoxifying genes, which were inhibited by CLDN1 silencing. In spheroid cells, the levels of reactive oxygen species were enhanced by acrolein, which was inhibited by CLDN1 silencing. Taken together, acrolein may reduce the anticancer drug-induced toxicity in human lung SCC cells mediated by high CLDN1 expression followed by the upregulation of Nrf2 signaling pathway., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Akira Ikari reports financial support was provided by Japan Society for the Promotion of Science. Akira Ikari reports financial support was provided by Smoking Research Foundation. Akira Ikari reports financial support was provided by Kobayashi Foundation for Cancer Research. Akira Ikari reports financial support was provided by Koshiyama Research Foundation. Akira Ikari reports financial support was provided by Takeda Science Foundation. Hiroaki Eguchi reports financial support was provided by Japan Science Society. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Peyer's patches (PPs) are part of the gut-associated lymphatic tissue (GALT) and represent the first line of the intestinal immunological defense. They consist of follicles with lymphocytes and an overlying subepithelial dome with dendritic cells and macrophages, and they are covered by the follicle-associated epithelium (FAE). A sealed paracellular pathway in the FAE is crucial for the controlled uptake of luminal antigens. Quercetin is the most abundant plant flavonoid and has a barrier-strengthening effect on tight junctions (TJs), a protein complex that regulates the paracellular pathway. In this study, we aimed to analyze the effect of quercetin on porcine PPs and the surrounding villus epithelium (VE). We incubated both tissue types for 4 h in Ussing chambers, recorded the transepithelial electrical resistance (TEER), and measured the unidirectional tracer flux of [ 3 H]-mannitol. Subsequently, we analyzed the expression, protein amount, and localization of three TJ proteins, claudin 1, claudin 2, and claudin 4. In the PPs, we could not detect an effect of quercetin after 4 h, neither on TEER nor on the [ 3 H]-mannitol flux. In the VE, quercetin led to a higher TEER value, while the [ 3 H]-mannitol flux was unchanged. The pore-forming claudin 2 was decreased while the barrier-forming claudin 4 was increased and the expression was upregulated. Claudin 1 was unchanged and all claudins could be located in the paracellular membrane by immunofluorescence microscopy. Our study shows the barrier-strengthening effect of quercetin in porcine VE by claudin 4 upregulation and a claudin 2 decrease. Moreover, it underlines the different barrier properties of PPs compared to the VE.

This study investigates the intricate composition and spatial distribution of tight junction complex proteins during early mouse neurulation. The analyses focused on the cranial neural tube, which gives rise to all head structures. Neurulation brings about significant changes in the neuronal and non-neuronal ectoderm at a cellular and tissue level. During this process, precise coordination of both epithelial integrity and epithelial dynamics is essential for accurate tissue morphogenesis. Tight junctions are pivotal for epithelial integrity, yet their complex composition in this context remains poorly understood. Our examination of various tight junction proteins in the forebrain region of mouse embryos revealed distinct patterns in the neuronal and non-neuronal ectoderm, as well as mesoderm-derived mesenchymal cells. While claudin-4 exhibited exclusive expression in the non-neuronal ectoderm, we demonstrated a neuronal ectoderm specific localization for claudin-12 in the developing cranial neural tube. Claudin-5 was uniquely present in mesenchymal cells. Regarding the subcellular localization, canonical tight junction localization in the apical junctions was predominant for most tight junction complex proteins. ZO-1 (zona occludens protein-1), claudin-1, claudin-4, claudin-12, and occludin were detected at the apical junction. However, claudin-1 and occludin also appeared in basolateral domains. Intriguingly, claudin-3 displayed a non-canonical localization, overlapping with a nuclear lamina marker. These findings highlight the diverse tissue and subcellular distribution of tight junction proteins and emphasize the need for their precise regulation during the dynamic processes of forebrain development. The study can thereby contribute to a better understanding of the role of tight junction complex proteins in forebrain development.

Ethnopharmacological Relevance: An essential factor related to the acute alcoholic liver injury is damage to the intestinal mucosal barrier. Yajieshaba (YJSB) is a commonly used formulation of Dai people in China and protects the liver., Aim of the Study: This study investigated whether YJSB can prevent acute alcoholic liver injury by regulating the intestinal mucosal barrier., Materials and Methods: The mice received 0.39 g/kg, 1.17 g/kg, and 3.51 g/kg dose YJSB for 7 days, a mouse model of acute alcoholic liver injury was established by a single instillation of 56% alcohol. Plasma biochemical markers were analyzed, liver injury was identified by histopathology, lipopolysaccharide (LPS), nuclear factor-k-gene binding (NF-κB), hepatic inflammatory factors, oxidative stress factors and reactive oxygen species (ROS) content was analyzed. The morphological changes of intestinal histology were observed by H&E staining, and the ultrastructure of ileal cells was observed by transmission electron microscopy. Immunofluorescence and Western blot was used to determine the expression levels of transporters and enzymes involved in Claudin 1, Occludin and zona occludens 1 (ZO-1) homeostasis in the liver and intestine., Results: The findings showed that YJSB reduced the levels of aspartate aminotr ansferase (AST), alanine aminotransferase (ALT) and total bile acid (TBA), both of which are indicators of liver function and had a protective effect against liver injury. In the liver homogenate, YJSB reduced the level of LPS, NF-κB, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6), decreased the level of superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH-PX) and catalase (CAT) and ROS. The results of hematoxylin and eosin (H&E) staining and transmission electron microscopy analysis revealed that YJSB reduced the degree of damage to intestinal tissue and intracellular organelles, implying that YJSB can reduce the "attack factor" that causes intestinal barrier damage, increase the "defense factor" that protects the intestinal barrier. The results of immunohistochemistry and Western blotting analysis showed that YJSB could increase the expression of claudin 1, occludin, and ZO-1 proteins, suggesting that the mechanism of action of YJSB against acute alcohol liver injury involves the upregulation of the expression of the intestinal barrier-related proteins and the repair of the damaged intestinal barrier., Conclusions: YJSB can block LPS, oxidative stress factors, and other harmful substances in the blood and protect the liver resisting acute alcoholic liver injury., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Ethnopharmacological Relevance: Ilex rotunda Thunb. (IR) is widely used for gastrointestinal diseases by Yao physician, and it has a better clinical curative effect on ulcerative colitis (UC). However, the main active components and mechanism of IR in the treatment of UC remain to be clarified., Aim of the Study: To investigate the main active components and mechanism of IR in the treatment of UC., Materials and Methods: Ten biological active components of IR were quantified by UPLC-MS/MS. In vitro, Caco2 cell monolayers were stimulated by lipopolysaccharide, and were treated with 10 biologically active components individually to investigate the protective role of the components of IR in mucosal barrier damage. In vivo, a mouse model of UC was induced by dextran sulfate sodium and administered with the candidate active components of IR. On day 8, the serum and colon tissue were collected for histological and molecular analysis to investigate the main active components and mechanism of IR., Results: Ziyuglycoside I, ziyuglycoside II, syringin, and pedunculoside in IR reduced phenol red transmission of the monolayer, and inhibited the protein expression of oncostatin M and oncostatin M receptor in Caco2 cells. Notably, ziyuglycoside II and syringin decreased the transepithelial electrical resistance of the monolayer, and promoted the protein expression of Occludin, Claudin-1 and zonula occludens-1 (ZO-1) in Caco2 cells. In vivo, ziyuglycoside II and syringin improved the symptoms of UC mice, including body weight, disease activity score, shortening of colon length, damaging of acidic mucus layer, histopathological changes, and protein expression of Occludin, Claudin-1, and ZO-1. Pedunculoside reduced the neutrophils and inflammatory response in the UC mice. Moreover, when the combination of ziyuglycoside II, syringin and pedunculoside was used for the treatment of UC, syringin and pedunculoside enhanced the therapeutic effect of ziyuglycoside II. Finally, RNA sequencing and RT-qPCR analysis revealed that ziyuglycoside II + syringin + pedunculoside and IR coregulated up to 42.7% of genes, and mainly reduced the overexpression of C-X-C motif ligand 1(CXCL1), oncostatin M receptor (OSMR), interleukin 1 receptor type I (IL1R1), tumor necrosis factor receptor superfamily member 9 (TNFRSF9), C-X-C motif chemokine 13 (CXCL13), oncostatin M (OSM), and interleukin 6 (IL-6) in the cytokine-cytokine interaction pathways., Conclusions: The combination of ziyuglycoside II, syringin, and pedunculoside protects against UC by modulating the intestinal mucosal barrier and inhibiting the cytokine-cytokine interaction pathways, and the effect is relatively equivalent to that of the water extract of Ilex rotunda Thunb., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of competing interest associated with this publication., (Copyright © 2023. Published by Elsevier B.V.)

Ethnopharmacological Relevance: Ulcerative colitis (UC) is one of non-specific inflammatory bowel disease that mainly affects the colon. Recently, UC has become a significant social and economic problem worldwide. Baitouweng decoction (BD), a traditional Chinese medicine described in the "Treatise on Febrile Diseases", has been used for centuries to treat intestinal diseases. However, its underlying mechanism remains largely unexplored., Aim of Study: In this study, we aimed to investigate the effect of BD on autophagy for repairing the colonic barrier in DSS-induced colitis mice and explored its role in regulating the autophagic signaling pathway AMPK/mTOR., Materials and Methods: Mice with colitis were treated with 3% dextran sulfate sodium (DSS) for 7 days. The effectiveness of BD in treating DSS-induced colitis was evaluated through body weight, disease activity index (DAI), colon length, pathological changes, organ index, and proportion of blood cells. Moreover, intestinal epithelial permeability was analyzed by examining FITC-dextran leakage, the bacterial load of mesenteric lymph nodes (MLNs), and bacterial infiltration of colon tissues. Barrier function was evaluated by assessing the number and proportion of colonic goblet cells and the expression of tight junction proteins, including ZO-1, claudin-1, and occludin. Furthermore, the levels of autophagy were assessed by examining the number of autophagosomes and the expression of the autophagy-related proteins LC3, Beclin1, and P62. Additionally, network pharmacology research was conducted to analyze the potential mechanisms underlying the medicinal effects, as indicated by the role of AMPK/mTOR in regulating the autophagic signaling pathway., Results: BD improved colitis symptoms in mice by restoring body weight and colon length and reducing inflammatory cell infiltration. Additionally, BD decreased the diffusion of FITC-dextran and bacterial translocation in MLNs, as well as bacterial infiltration of the colonic mucosa. The number and proportion of colonic goblet cells, the expression of ZO-1, Claudin-1, and Occludin, and the levels of autophagy were also increased by BD. Network pharmacology analysis suggested that BD might affect intestinal autophagy through the AMPK signaling pathway, which was confirmed by the activation of AMPK phosphorylation and the downregulation of mTOR expression following BD treatment., Conclusion: Our study demonstrated that BD repaired the intestinal epithelial barrier in DSS-induced colitis mice by activating AMPK phosphorylation and inhibiting mTOR expression to promote autophagy., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023. Published by Elsevier B.V.)

Background: Gut epithelium is the first natural barrier against Trichinella spiralis larval invasion, but the mechanism by which larval penetration of gut epithelium is not completely elucidated. Previous studies showed that proteases secreted by T. spiralis intestinal infective larvae (IIL) degraded tight junctions (TJs) proteins of gut epithelium and mediated larval invasion. A new T. spiralis serine proteinase (TsSPc) was identified in the IIL surface proteins and ES proteins, rTsSPc bound to the intestinal epithelial cell (IECs) and promoted larval invasion of IECs. The aim of this study was to characterize the interacted proteins of TsSPc and IECs, and to investigate the molecular mechanisms of TsSPc mediating larval invasion of gut mucosa., Methodology/principal Finding: IIFT results showed natural TsSPc was detected in infected murine intestine at 6, 12 hours post infection (hpi) and 3 dpi. The results of GST pull-down, mass spectrometry (MS) and Co-IP indicated that rTsSPc bound and interacted specifically with receptor for activated protein C kinase 1 (RACK1) in Caco-2 cells. rTsSPc did not directly hydrolyze the TJs proteins. qPCR and Western blot showed that rTsSPc up-regulated RACK1 expression, activated MAPK/ERK1/2 pathway, reduced the expression levels of gut TJs (occludin and claudin-1) and adherent protein E-cad, increased the paracellular permeability and damaged the integrity of intestinal epithelial barrier. Moreover, the RACK1 inhibitor HO and ERK1/2 pathway inhibitor PD98059 abolished the rTsSPc activating ERK1/2 pathway, they also inhibited and abrogated the rTsSPc down-regulating expression of occludin, claudin-1 and E-cad in Caco-2 monolayer and infected murine intestine, impeded larval invasion and improved intestinal epithelial integrity and barrier function, reduced intestinal worm burdens and alleviated intestinal inflammation., Conclusions: rTsSPc bound to RACK1 receptor in gut epithelium, activated MAPK/ERK1/2 pathway, decreased the expression of gut epithelial TJs proteins and disrupted the epithelial integrity, consequently mediated T. spiralis larval invasion of gut epithelium. The results are valuable to understand T. spiralis invasion mechanism, and TsSPc might be regarded as a vaccine target against T. spiralis invasion and infection., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Song et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Six female littermate piglets were used in an experiment to evaluate the mRNA expression in tissues from piglets given one or two 1 mL injections of iron dextran (200 mg Fe/mL). All piglets in the litter were administered the first 1 mL injection < 24 h after birth. On day 7, piglets were paired by weight (mean body weight = 1.72 ± 0.13 kg) and one piglet from each pair was randomly selected as control (CON) and the other received a second injection (+Fe). At weaning on day 22, each piglet was anesthetized, and samples of liver and duodenum were taken from the anesthetized piglets and preserved until mRNA extraction. differential gene expression data were analyzed with a fold change cutoff (FC) of |1.2| P < 0.05. Pathway analysis was conducted with Z-score cutoff of P < 0.05. In the duodenum 435 genes were significantly changed with a FC ≥ |1.2| P < 0.05. In the duodenum, Claudin 1 and Claudin 2 were inversely affected by + Fe. Claudin 1 (CLDN1) plays a key role in cell-to-cell adhesion in the epithelial cell sheets and was upregulated (FC = 4.48, P = 0.0423). Claudin 2 (CLDN2) is expressed in cation leaky epithelia, especially during disease or inflammation and was downregulated (FC = -1.41, P = 0.0097). In the liver, 362 genes were expressed with a FC ≥ |1.2| P < 0.05. The gene most affected by a second dose of 200 mg Fe was hepcidin antimicrobial peptide (HAMP) with a FC of 40.8. HAMP is a liver-produced hormone that is the main circulating regulator of Fe absorption and distribution across tissues. It also controls the major flows of Fe into plasma by promoting endocytosis and degradation of ferroportin (SLC4A1). This leads to the retention of Fe in Fe-exporting cells and decreased flow of Fe into plasma. Gene expression related to metabolic pathway changes in the duodenum and liver provides evidence for the improved feed conversion and growth rates in piglets given two iron injections preweaning with contemporary pigs in a companion study. In the duodenum, there is a downregulation of gene clusters associated with gluconeogenesis (P < 0.05). Concurrently, there was a decrease in the mRNA expression of genes for enzymes required for urea production in the liver (P < 0.05). These observations suggest that there may be less need for gluconeogenesis, and possibly less urea production from deaminated amino acids. The genomic and pathway analyses provided empirical evidence linking gene expression with phenotypic observations of piglet health and growth improvements., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science.)