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Formation of fluid-filled lumina by epithelial tissues is essential for organ development. How cells control the hydraulic and cortical forces to control lumen morphology is not well understood. Here, we quantified the mechanical role of tight junctions in lumen formation using MDCK-II cysts. We found that the paracellular ion barrier formed by claudin receptors is not required for the hydraulic inflation of a lumen. However, the depletion of the zonula occludens scaffold resulted in lumen collapse and folding of apical membranes. Combining quantitative measurements of hydrostatic lumen pressure and junctional tension with modeling enabled us to explain lumen morphologies from the pressure-tension force balance. Tight junctions promote lumen inflation by decreasing cortical tension via the inhibition of myosin. In addition, our results suggest that excess apical area contributes to lumen opening. Overall, we provide a mechanical understanding of how epithelial cells use tight junctions to modulate tissue and lumen shape. [Display omitted] • Depletion of ZO scaffold causes lumen collapse and apical membrane folding • The claudin permeability barrier is not necessary for hydraulic lumen inflation • Tight junctions promote lumen inflation by decreasing cortical tension • Lumen shape controlled by pressure-tension force balance and apical area constraints Mukenhirn et al. show that epithelial cells use tight junctions to control lumen shape, and the depletion of the tight junction scaffold leads to lumen collapse and increased cortical tension. Claudin-depleted MDCK-II cysts maintain lumen pressure and shape despite high ion permeability. [ABSTRACT FROM AUTHOR]

Objective: Endothelial dysfunction plays an important role in the pathogenesis of chronic kidney disease. Prostacyclin (PGI2), an endothelial cell‐produced endogenous prostaglandin, plays a crucial role in maintaining endothelial function. However, its effects on intestinal microcirculation and barrier function are not fully understood. We hypothesized that PGI2 improves intestinal microcirculation and barrier function via endothelial protective effects. Methods: ICR and ICGN (a spontaneous nephrotic model) mice were used in this study. Intestinal microcirculation was visualized in vivo to investigate PGI2 effects. Beraprost served as PGI2. PGI2 administration spanned 4 weeks, following which we assessed its influence on intestinal endothelial, intestinal barrier, and renal functions. Results: We visualized intestinal microcirculation and endothelial glycocalyx in the intestinal blood vessels. Beraprost administration induced a 1.2‐fold dilatation of the vascular diameter of the small intestine. Intestinal blood flow in ICGN mice was significantly reduced compared that in ICR mice but improved with beraprost administration. ICGN mice exhibited reduced serum albumin levels, decreased ambulation, an imbalance in intestinal reactive oxygen species (ROS)/nitric oxide (NO), and impaired tight junctions; all were ameliorated by beraprost administration. Conclusions: Beraprost improves intestinal microcirculation and barrier function by ameliorating ROS/NO imbalances, thereby reducing physical inactivity during renal failure. [ABSTRACT FROM AUTHOR]

Background: Altered gut metabolites, especially short-chain fatty acids (SCFAs), in feces and plasma are observed in patients with Parkinson's disease (PD). Objective: We aimed to investigate the colonic expression of two SCFA receptors, free fatty acid receptor (FFAR)2 and FFAR3, and gut barrier integrity in patients with PD and correlations with clinical severity. Methods: In this retrospective study, colonic biopsy specimens were collected from 37 PD patients and 34 unaffected controls. Of this cohort, 31 participants (14 PD, 17 controls) underwent a series of colon biopsies. Colonic expression of FFAR2, FFAR3, and the tight junction marker ZO-1 were assayed by immunofluorescence staining. The You Only Look Once (version 8, YOLOv8) algorithm was used for automated detection and segmentation of immunostaining signal. PD motor function was assessed with the Movement Disorder Society (MDS)-Unified Parkinson's Disease Rating Scale (UPDRS), and constipation was assessed using Rome-IV criteria. Results: Compared with controls, PD patients had significantly lower colonic expression of ZO-1 (p < 0.01) and FFAR2 (p = 0.01). On serial biopsy, colonic expression of FFAR2 and FFAR3 was reduced in the pre-motor stage before PD diagnosis (both p < 0.01). MDS-UPDRS motor scores did not correlate with colonic marker levels. Constipation severity negatively correlated with colonic ZO-1 levels (r = -0.49, p = 0.02). Conclusions: Colonic expression of ZO-1 and FFAR2 is lower in PD patients compared with unaffected controls, and FFAR2 and FFAR3 levels decline in the pre-motor stage of PD. Our findings implicate a leaky gut phenomenon in PD and reinforce that gut metabolites may contribute to the process of PD. [ABSTRACT FROM AUTHOR]

Capillary malformations (CM) are congenital vascular irregularities of capillary and venous blood vessels that appear in the skin, leptomeninges of the brain, and the choroid of the eye in the disorder known as Sturge Weber Syndrome (SWS). More common are non-syndromic CM found only in the skin, without brain or ocular involvement. A somatic activating mutation in GNAQ (p.R183Q) is found in ~ 90% of syndromic and non-syndromic CM specimens and is present in CD31pos endothelial cells isolated from brain and skin CM specimens. Endothelial expression of the GNAQ p.R183Q variant is sufficient to form CM-like vessels in mice. Given the distinct features and functions of blood vessels in the brain versus the skin, we examined the features of CM vessels in both tissues to gain insights into the pathogenesis of CM. Herein, we present morphologic characteristics of CM observed in specimens from brain and skin. The GNAQ p.R183Q variant allelic frequency in each specimen was determined by droplet digital PCR. Sections were stained for endothelial cells, tight junctions, mural cells, and macrophages to assess the endothelium as well as perivascular constituents. CM blood vessels in brain and skin were enlarged, exhibited fibrin leakage and reduced zona occludin-1 and claudin-5, and were surrounded by MRC1pos/LYVE1pos macrophages. In contrast, the CMs from brain and skin differ in endothelial sprouting activity and localization of mural cells. These characteristics might be helpful in the development of targeted and/or tissue specific therapies to prevent or reverse non-syndromic and syndromic CM. [ABSTRACT FROM AUTHOR]

Background: Inflammatory bowel disease (IBD) is a chronic condition characterized by recurrent episodes and an unclear etiology. Given the limitations of current therapeutic options, which include suboptimal efficacy and significant side effects, there is a pressing need to explore novel treatments. Probiotics derived from diverse species have been identified as a promising approach for managing IBD, owing to their anti-inflammatory properties and their ability to regulate gut flora, among other beneficial effects. Methods: In this study, three strains of lactic acid bacteria (LAB) were isolated from the feces of the scavenger spotted hyena (Crocuta crocuta), a scavenging mammal. Based on their capability to survive within and adhere to the gastrointestinal tract, along with their profile of antibiotic resistance, a high-quality strain of Lactobacillus acidophilus (LA) was selected and demonstrated to be safe for mice. Subsequently, the therapeutic efficacy of LA was evaluated using a dextran sulfate sodium (DSS)-induced model of ulcerative colitis in mice. Results: The results indicated that LA restored the disease activity index and improved histopathological lesions in the model group. It also reduced inflammation and oxidative stress and significantly restored the expression of mucins and intestinal tight junction (TJ) proteins (ZO-1, Occludin). Furthermore, LA corrected the DSS-induced disruption of the intestinal flora, leading to a significant decrease in the prevalence of potentially harmful bacterial genera, such as Bacteroides, and an increase in beneficial bacterial genera, including Lactobacillus. In conclusion, Lactobacillus acidophilus LA1, isolated from spotted hyena feces, has potential as a functional supplement for alleviating symptoms of IBD and regulating intestinal flora. [ABSTRACT FROM AUTHOR]

Oleanolic acid (OA) is a naturally occurring pentacyclic triterpene compound that has been reported to cause cholestatic liver injury. However, the regulation and pathogenic role of bile acids in OA‐induced development of cholestatic liver injury remains largely unclear. Farnesoid X receptor (FXR) is a metabolic nuclear receptor that plays an important role in bile acid homeostasis in the liver by regulating efflux transporters bile salt export pump (BSEP) and multidrug resistance‐associated protein 2 (MRP2). The aim of this study was to investigate the effect of OA on hepatocyte tight junction function and determine the role of FXR, BSEP, and MRP2 in the mechanism of impairment of transport of bile acids induced by OA. Both in vivo and in vitro models were used to characterize the OA‐induced liver injury. The liquid chromatography–tandem mass spectrometry (LC‐MS) was employed to characterize the efflux function of the transporters, and the results showed that OA caused a blockage of bile acids efflux. OA treatment resulted in decreased expression levels of the tight junction proteins zonula occludens‐1 and occludin. Immunofluorescence results showed that OA treatment significantly reduced the number of bile ducts and the immunofluorescence intensity. Pretreatment with agonists of FXR and MRP2, respectively, in animal experiments attenuated OA‐induced liver injury, while pretreatment with inhibitors of BSEP and MRP2 further aggravated OA‐induced liver injury. These results suggest that OA inhibits FXR‐mediated BSEP and MRP2, leading to impaired bile acid efflux and disruption of tight junctions between liver cells, resulting in liver damage. Oleanolic acid (OA) is a naturally occurring pentacyclic triterpene compound that has been reported to cause cholestatic liver injury. In this study, OA inhibits FXR‐mediated BSEP and MRP2, leading to impaired bile acid efflux and disruption of tight junctions between liver cells, resulting in liver damage. Activation of FXR and MRP2 mitigated OA‐induced liver injury, while inhibition of BSEP and MRP2 further aggravated OA‐induced liver injury. [ABSTRACT FROM AUTHOR]

Reperfusion after cerebral ischemia leads to secondary damage to the nervous system, called cerebral ischemia/reperfusion injury (CIRI). The blood–brain barrier (BBB) consists of endothelial cells and tight junction (TJ) proteins, and its disruption aggravates CIRI. Two GSE datasets identified Tissue Factor Pathway Inhibitor 2 (TFPI2) as a differentially upregulated gene (Log2FC > 1, p < 0.01) in the cerebral cortex of ischemic rats, and TFPI2 affects angiogenesis of endothelial cells. Moreover, genes (c-Jun, c-Fos, FosL1) encoding subunits of Activator Protein-1 (AP-1), a transcription factor involved in IRI, were highly expressed in ischemic samples. Thus, the effects of the AP-1/TFPI2 axis on CIRI were explored. We determined increased TFPI2 expression in the cerebral cortex of rats receiving middle cerebral artery occlusion (MCAO) for 90 min and reperfusion (R) for 48 h. Then AAV2-shTFPI2 particles (5 × 1010 vg) were injected into the right lateral ventricle of rats 3 weeks before MCAO/R. TFPI2 knockdown decreased infarct size and neuronal injury in ischemic rats. It improved BBB integrity, demonstrated by reduced FITC-dextran leakage in brain tissues of MCAO/R-operated rats. Furthermore, it increased the expression of TJ proteins (Occludin, Claudin-5, TJP-1) in the cerebral cortex of rats with CIRI. Consistently, we found that TFPI2 knockdown mitigated cell damage in mouse endothelial bEND.3 cells with oxygen and glucose deprivation (ODG) for 6 h and reoxygenation (R) for 18 h (OGD/R) treatment. High co-expression of c-Jun and c-Fos significantly elevated TFPI2 promoter activity. c-Jun knockdown inhibited TFPI2 expression in OGD/R-treated bEND.3 cell. Collectively, our findings demonstrate that inhibition of the AP-1/TFPI2 axis alleviates CIRI. [ABSTRACT FROM AUTHOR]

Contact inhibition of proliferation is a critical cell density control mechanism governed by the Hippo signalling pathway. The biochemical signalling underlying cell density‐dependent cues regulating Hippo signalling and its downstream effectors, YAP, remains poorly understood. Here, we reveal that the tight junction protein ZO‐2 is required for the contact‐mediated inhibition of proliferation. We additionally determined that the well‐established molecular players of this process, namely Hippo kinase LATS1 and YAP, are regulated by ZO‐2 and that the scaffolding function of ZO‐2 promotes the interaction with and phosphorylation of YAP by LATS1. Mechanistically, YAP is phosphorylated when ZO‐2 brings LATS1 and YAP together via its SH3 and PDZ domains, respectively, subsequently leading to the cytoplasmic retention and inactivation of YAP. In conclusion, we demonstrate that ZO‐2 maintains Hippo signalling pathway activation by promoting the stability of LATS1 to inactivate YAP. [ABSTRACT FROM AUTHOR]

Cadmium is a contributing factor to cardiovascular diseases and highly toxic to vascular endothelial cells. It has a distinct mode of injury, causing the de-endothelialization of regions in the monolayer structure of endothelial cells in a concentration-dependent manner. However, the specific molecules involved in the cadmium toxicity of endothelial cells remain unclear. The purpose of this study was to identify the specific molecular mechanisms through which cadmium affects endothelial detachment. Cadmium inhibited the expression of claudin-5 and zonula occludens (ZO)-1, which are components of tight junctions (strongest contributors to intercellular adhesion), in a concentration- and time-dependent manner. Compared to arsenite, zinc, and manganese, only cadmium suppressed the expression of both claudin-5 and ZO-1 molecules. Moreover, the knockdown of claudin-5 and ZO-1 exacerbated cadmium-induced endothelial cell injury and expansion of the detachment area, whereas their overexpression reversed these effects. CRE-binding protein inhibition reduced cadmium toxicity, suggesting that CRE-binding protein activation is involved in the cadmium-induced inhibition of claudin-5 and ZO-1 expression and endothelial detachment. These findings provide new insights into the toxicological mechanisms of cadmium-induced endothelial injury and risk of cardiovascular disease. [ABSTRACT FROM AUTHOR]

Cerebral ischemia can lead to destruction of the blood—brain barrier (BBB), the main cause of cerebral edema and cerebral infarction. BBB damage is also one of the key factors affecting the result of drug therapy. We studied the protective effect of 5-day pretreatment with protocatechuic aldehyde (PAL) at doses of 10 and 20 mg/kg on BBB function and structure after middle cerebral artery occlusion/reperfusion (MCAO/R) in rats. The infarct volume, behavioral neurological deficit score, and Evans blue content in the brain were estimated. We also evaluated the content of nitric oxide (NO) and activities of inducible and neuronal NO synthases. Expression of aquaporin-4 (AQP-4), occludin, claudin-5, and MMP-3 in the brain tissues was estimated by Western blotting. The BBB ultrastructure was analyzed under an electron microscope. We revealed that PAL at both used doses significantly reduced the neurological deficit score, brain infarct volume, and Evans blue extravasation. Electron microscopy showed that PAL significantly improved the ultrastructure of BBB and alleviated its injury. Pretreatment with PAL increased expression of occludin and claudin-5 and reduced expression of AQP-4 and MMP-3. At the same time, the release of NO and activities of NO synthases were notably inhibited. Our results suggest that PAL can be a promising compound to attenuate cerebral ischemia resulting from occlusion/reperfusion injury via BBB protection. [ABSTRACT FROM AUTHOR]

The epidermis, the most superficial layer of the human skin, serves a critical barrier function, protecting the body from external pathogens and allergens. Dysregulation of epidermal differentiation contributes to barrier dysfunction and has been implicated in the pathology of various dermatological diseases, including atopic dermatitis (AD). Mucopolysaccharide polysulphate (MPS) is a moisturising agent used to treat xerosis in patients with AD. However, its mechanism of action on keratinocytes, the main constituents of the epidermis, remains unclear. In this study, we investigated the effect of MPS on keratinocytes by subjecting adult human epidermal and three‐dimensional cultured keratinocytes to MPS treatment, followed by transcriptome analysis. The analysis revealed that MPS treatment enhances keratinocyte differentiation and suppresses proliferation. We focused on amphiregulin (AREG), a membrane protein that belongs to the epidermal growth factor (EGF) family and possesses a heparin‐binding domain, as a significant target among the genes altered by MPS. MPS exerted an inhibitory effect directly on AREG, rather than on EGF receptors or other members of the EGF family. Furthermore, AREG leads to a reduction in epidermal barrier function, whereas MPS contributes to barrier enhancement via AREG inhibition. Collectively, these findings suggest that MPS modulates barrier function through AREG inhibition, offering insights into potential therapeutic strategies for skin barrier restoration. [ABSTRACT FROM AUTHOR]

Cosmetically applicable soluble agonists for Toll-like receptor 2 (TLR2), which can strengthen skin barrier function, were produced by fermentation of asparagus (Asparagus officinalis L.) extract supplemented with skimmed milk using Lactobacillus delbrueckii subsp. lactis TL24. Their molecular size was estimated to be >100 kDa. Their TLR2-stimulating activity was stable over 1 year at 4 °C, but it decreased by more than 95% within 10 and 4 months at 25 °C and 40 °C, respectively. The possibility of stabilization of TLR2-stimulating activity by powdering was tested, and we found that lyophilization with 10% or a higher amount of dextrin could stabilize the activity even at 40 °C. The powdered fermented product dose-dependently stimulated TLR2. It augmented the formation of tight junctions in normal human keratinocytes, as detected by fluorescence staining of occludin and ZO-1, whereas their protein and gene expression levels did not increase, suggesting that a change in subcellular localization of these proteins without significant changes in their amounts might be responsible. The powder nature has some benefits over the aqueous, besides stability, e.g., it can be dissolved just before application, allowing fresh material to be used each time, and it may widen a range of cosmetic applications in non-aqueous types of cosmetics. [ABSTRACT FROM AUTHOR]

Simple Summary: Traditional Chinese herbal resources are abundantly available in China and have garnered significant attention owing to their distinctive pharmacological attributes, such as their antibacterial, anti-inflammatory, and antiviral properties, and their ability to regulate their host's health. Nevertheless, a considerable amount of residue remains after the extraction of these herbal medicines. Presently, limited research on the utilization of this residue has led to both resource wastage and environmental pollution. Numerous studies have indicated that the extracted residue of the Isatidis Root still contains various organic components, including amino acids, alkaloids, flavonoids, and other nutrients. Consequently, this study's objective was to explore the potential of Isatidis Root residue as an unconventional feed resource. Our findings revealed that Isatis Root residue positively impacted the diarrhea rate and intestinal health of weaned piglets. Weaning stress can trigger diarrhea, cause intestinal damage, and disrupt the intestinal flora of piglets, ultimately resulting in retarded growth or even the death of the animals. Traditional Chinese medicine residues encompass numerous bioactive compounds and essential nutrients; however, their efficient utilization remains a challenge. Consequently, our study sought to explore the impact of traditional Chinese medicine residues, specifically Isatidis Root residue (IRR), on the growth performance, intestinal function, and occurrence of weaning diarrhea in newly weaned piglets. Forty healthy, castrated Duroc × Landrace × Yorkshire males, weaned at 21 days old and exhibiting similar body conditions, were randomly allocated into five groups, with eight piglets in each group. The results indicated that the dietary inclusion of IRR at concentrations ranging from 0.5% to 4.0% notably decreased the incidence of diarrhea in weaned piglets compared to the control group (p < 0.05). Serum LDL-C and globulin (GLB) contents were reduced in response to dietary IRR concentrations (0.5% to 4.0%), while serum albumin (ALB) and albumin/globulin (A/G) contents were enhanced (p < 0.05). Dietary 0.5%, 1.0%, and 2.0% IRR resulted in significant increases in villus height (VH) and villus height/crypt depth (V/C) ratios in the jejunum, V/C ratios in the ileum, and the number of villi goblet cells both in the jejunum and ileum. IRR also led to a significant decrease in the crypt depth (CD) of the jejunum and ileum (p < 0.05). Furthermore, the expression of IL-6 in the jejunum was significantly increased in IRR-fed piglets (0.5% to 4.0%) (p < 0.05). IRR demonstrated inhibitory effects on harmful bacteria in the gastrointestinal microbiome, including Campylobacter, Actinobacillus minor, and Ralstonia pickettii, indicating its broad-spectrum bacteriostatic properties. In conclusion, dietary IRR alleviated diarrhea in weaned piglets and improved gut function and microbial compositions. [ABSTRACT FROM AUTHOR]

Regular exercise as part of one's lifestyle is well-recognized for its beneficial effect on several diseases such as cardiovascular disease and obesity; however, many questions remain unanswered regarding the effects of exercise on the gut environment. This study aimed to investigate the impact of long-term endurance exercise on modulating inflammation and endoplasmic reticulum (ER) stress. Fifteen-week-old male Sprague-Dawley (SD) rats were subjected to six months of endurance treadmill training, while age-matched controls remained sedentary. Results showed that IL-6 mRNA levels in colon tissues were significantly higher in the exercise group compared to the sedentary group. Exercise activated a significant ER stress-induced survival pathway by increasing BiP and phosphorylation of eIF2α (p-eIF2α) expressions in the liver and colon, while decreasing CHOP in the liver. Gene expressions of MUC2, Occludin, and Claudin-2 were increased in the colon of the exercise group, indicating enhanced intestinal integrity. Furthermore, the data showed a positive correlation between microbiota α-diversity and BiP (r = 0.464~0.677, p < 0.05). Populations of Desulfovibrio C21 c20 were significantly greater in the exercise group than the sedentary group. Additionally, predicted functions of the gut microbial community in terms of enzymes and pathways supported the enhancement of fatty-acid-related processes by exercise. These findings suggest that prolonged endurance exercise can affect the colon environment, which is likely related to changes in inflammation, ER stress, mucin layers and tight junctions, associated with modifications in the gut microbiome. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purpose: Microglia-related inflammation is closely linked to the pathogenesis of retinal diseases. The primary objective of this research was to investigate the impact and mechanism of M1 phenotype microglia on the barrier function of retina microvascular endothelial cells. Methods: Quantitative polymerase chain reactions and western blot techniques were utilized to analysis the mRNA and protein expressions of M1 and M2 markers of human microglial clone 3 cell line (HMC3), as well as the levels of Notch ligands and receptors under the intervention of lipopolysaccharide (LPS) or interleukin (IL)-4. ELISA was utilized to detect the pro-inflammatory and anti-inflammatory cytokines from HMC3 cells. The cellular tight junction and apoptosis of human retinal microvascular endothelial cells (HRMECs) were assessed by western blot and fluorescein isothiocyanate-dextran permeability assay. The inhibitors of Notch1 and RNA interference (RNAi) targeting Jagged1 were used to assess their contribution to the barrier function of vascular endothelial cells. Results: Inducible nitric oxide synthase (iNOS) and IL-1β were considerably elevated in LPS-treated HMC3, while CD206 and Arg-1 markedly elevated under IL-4 stimulation. The conditioned medium derived from LPS-treated HMC3 cells promoted permeability, diminished the expression of zonula occludens-1 and Occludin, and elevated the expression of Cleaved caspase-3 in HRMECs. RNAi targeting Jagged1 or Notch1 inhibitor could block M1 HMC3 polarization and maintain barrier function of HRMECs. Conclusion: Our findings suggest that Jagged1-Notch1 signaling pathway induces M1 microglial cells to disrupt the barrier function of HRMECs, which may lead to retinal diseases. [ABSTRACT FROM AUTHOR]

As one of the most representative natural products among flavonoids, quercetin (QUE) has been reported to exhibit beneficial effects on gut health in recent years. In this study, we utilized a dextran sulfate sodium (DSS)-induced colitis mice model to explore the protective effects and underlying mechanisms of QUE on colitis. Our data demonstrated that QUE oral gavage administration significantly ameliorates the symptoms and histopathological changes associated with colitis. Additionally, the concentration of mucin-2, the number of goblet cells, and the expression of tight junction proteins (such as ZO-1, Occludin, and Claudin-1) were all found to be increased. Furthermore, QUE treatment regulated the levels of inflammatory cytokines and macrophage polarization, as well as the oxidative stress-related pathway (Nrf2/HO-1) and associated enzymes. Additionally, 16S rDNA sequencing revealed that QUE treatment rebalances the alterations in colon microbiota composition (inlcuding Bacteroidaceae, Bacteroides, and Odoribacter) in DSS-induced colitis mice. The analysis of network dynamics reveals a significant correlation between gut microbial communities and microenvironmental factors associated with inflammation and oxidative stress, in conjunction with the previously mentioned findings. Collectively, our results suggest that QUE has the potential to treat colitis by maintaining the mucosal barrier, modulating inflammation, and reducing oxidation stress, which may depend on the reversal of gut microbiota dysbiosis. [ABSTRACT FROM AUTHOR]

Changes to blood–brain barrier structure and function may affect the delivery of drugs into the brain. It is worthwhile to exploring more study on how the blood–brain barrier changes in structure and function and how that affects drug transport in high-altitude hypoxic environment. The DIA high-throughput sequencing technique indicate that the rats blood–brain barrier has been identified to have 7252 proteins overall and 8 tight junction proteins, among which Claudin-7 was a plateau-specific tight junction protein under high-altitude hypoxia, and based on the interaction network study, 2421 proteins are found to interact with one another, with ZO-1 being the primary target. The results of the projected gene function analysis demonstrated that changes in tight junction proteins are related to the control of TRP channels by inflammatory mediators, the wnt signaling pathway, the ABC transporter system, and drug metabolism-CYP450 enzyme regulation. Additionally, the electron microscopy, the Evans blue combination with confocal laser scanning microscopy, and the Western Blot and RT-qPCR revealed that high-altitude hypoxic environment induces blood–brain barrier tight junctions to open, blood–brain barrier permeability increases, ZO-1, Occludin, Claudin-5 protein and mRNA expression decreased. Our research implies that structural and functional alterations in the blood–brain barrier induced by high altitude hypoxia may impact drug transport inside the central nervous system, and that drug transporters and drug-metabolizing enzymes may be key players in this process. The alteration of tight junction proteins and mechanisms under high-altitude hypoxic environment [ABSTRACT FROM AUTHOR]

Mounting clinical evidence suggests that a comprised intestinal barrier contributes to the progression of nonalcoholic steatohepatitis (NASH); nevertheless, the precise mechanism remains elusive. This study unveils a significant upregulation of nuclear receptor‐binding SET domain protein 2 (NSD2) in the intestines of obese humans and mice subjected to a high‐fat cholesterol diet (HFCD). Intestine‐specific NSD2 knockout attenuated the progression of intestinal barrier impairment and NASH, whereas NSD2 overexpression exacerbated this progression. Mechanistically, NSD2 directly regulates the transcriptional activation of Ern1 by demethylating histone H3 at lysine 36 (H3K36me2), thus activating the ERN1–JNK axis to intensify intestinal barrier impairment and subsequently foster NASH progression. These findings elucidate the crucial role of NSD2‐mediated H3K36me2 in intestinal barrier impairment, suggesting that targeting intestinal NSD2 can represent a novel therapeutic approach for NASH. [ABSTRACT FROM AUTHOR]

Diabetes is associated with increased oxidative stress, leading to altered tight junction formation and increased apoptosis in colonic epithelial cells. These changes may lead to intestinal barrier dysfunction and corresponding gastrointestinal symptoms in patients with diabetes, including diarrhea. The aim of this study was to characterize the effect and mechanism of Resolvin D1 (RvD1) on diabetes‐induced oxidative stress and barrier disruption in the colon. Mice with streptozotocin‐induced diabetes were treated with RvD1 for 2 weeks, then evaluated for stool frequency, stool water content, gut permeability, and colonic transepithelial electrical resistance as well as production of reactive oxygen species (ROS), apoptosis, and expression of tight junction proteins Zonula Occludens 1 (ZO‐1) and occludin. The same parameters were assessed in human colonoid cultures subjected to elevated glucose. We found that RvD1 treatment did not affect blood glucose, but normalized stool water content and prevented intestinal barrier dysfunction, epithelial oxidative stress, and apoptosis. RvD1 also restored ZO‐1 and occludin expression in diabetic mice. RvD1 treatment increased phosphorylation of Akt and was accompanied by a 3.5‐fold increase in heme oxygenase‐1 (HO‐1) expression in the epithelial cells. The protective effects of RvD1 were blocked by ZnPP, a competitive inhibitor of HO‐1. Similar findings were observed in RvD1‐treated human colonoid cultures subjected to elevated glucose. In conclusion, Oxidative stress in diabetes results in mucosal barrier dysfunction, contributing to the development of diabetic diarrhea. Resolvins prevent ROS‐mediated mucosal injury and protect gut barrier function by intracellular PI3K/Akt activation and subsequent HO‐1 upregulation in intestinal epithelial cells. These actions result in normalizing stool frequency and stool water content in diabetic mice, suggesting that resolvins may be useful in the treatment of diabetic diarrhea. [ABSTRACT FROM AUTHOR]

Blood–testis barrier (BTB) genes are crucial for the cellular mechanisms of spermatogenesis as they protect against detrimental cytotoxic agents, chemicals, and pathogens, thereby maintaining a sterile environment necessary for sperm development. BTB proteins predominantly consist of extensive tight and gap junctions formed between Sertoli cells. These junctions form a crucial immunological barrier restricting the intercellular movement of substances and molecules within the adluminal compartment. Epithelial tight junctions are complex membrane structures composed of various integral membrane proteins, including claudins, zonula occludens-1, and occludin. Inter-testicular cell junction proteins undergo a constant process of degradation and renewal. In addition, the downregulation of genes crucial to the development and preservation of cell junctions could disrupt the functionality of the BTB, potentially leading to male infertility. Oxidative stress and inflammation may contribute to disrupted spermatogenesis, resulting in male infertility. L-cysteine is a precursor to glutathione, a crucial antioxidant that helps mitigate damage and inflammation resulting from oxidative stress. Preclinical research indicates that L-cysteine may offer protective benefits against testicular injury and promote the expression of BTB genes. This review emphasizes various BTB genes essential for preserving its structural integrity and facilitating spermatogenesis and male fertility. Furthermore, it consolidates various research findings suggesting that L-cysteine may promote the expression of BTB-associated genes, thereby aiding in the maintenance of testicular functions. [ABSTRACT FROM AUTHOR]

Background: Unbalanced gut microbiota is considered to cause dysfunction of the gut barrier function. Lactobacillus johnsonii MG, isolated from mouse feces as gut associating lactobacilli, enhanced gut barrier function in Caco‐2 cells via interaction with JAM‐2 in tight junctions. In this study, the anti‐inflammatory effects of L. johnsonii MG were investigated in a colitis mouse model developed by treating mice with 3% dextran sulfate sodium (DSS) for 9 days. Results: MG treatment of colitis mice resulted in fast recovery of the body weight and showed significant improvement in the disease activity index and histopathological scores. The histomorphological score increased by DSS treatment was significantly improved in the MG‐treated group. In the intestine, the expression of Ocln, Zo1, Itga6, Lama3, and Jam2 genes, which are involved in tight junction functions, were significantly upregulated in MG‐treated colitis mice. In the microflora analysis, the abundance of Ruminococcaceae, Bacteroides, and Lachnospiraceae were reduced in DSS‐treated mice and recovered by MG treatment. Conclusion: We reported the potential of L. johnsonii MG in the regeneration of crypts and integrity of matrix proteins in the gut of mice with colitis through its association with tight junctions. The experimental results provide new insights into the probiotic effect of tight junction associating L. johnsonii MG. [ABSTRACT FROM AUTHOR]

Background: Spinal cord injury (SCI) disrupts intestinal barrier function, thereby increasing antigen permeation and leading to poor outcomes. Despite the intestinal tract's anatomic and physiologic heterogeneity, studies following SCI have not comprehensively addressed intestinal pathophysiology with regional specificity. Aims and Methods: We used an experimental model of high thoracic SCI to investigate (1) regional mucosal oxidative stress using dihydroethidium labeling; (2) regional paracellular permeability to small- and large-molecular probes via Ussing chamber; (3) regional intestinal tight junction (TJ) protein expression; and (4) hindgut perfusion via the caudal mesenteric artery. Results: Dihydroethidium staining was significantly elevated within duodenal mucosa at 3-day post-SCI. Molar flux of [14C]-urea was significantly elevated in duodenum and proximal colon at 3-day post-SCI, while molar flux of [3H]-inulin was significantly elevated only in duodenum at 3-day post-SCI. Barrier permeability was mirrored by a significant increase in the expression of pore-forming TJ protein claudin-2 in duodenum and proximal colon at 3-day post-SCI. Claudin-2 expression remained significantly elevated in proximal colon at 3-week post-SCI. Expression of the barrier-forming TJ protein occludin was significantly reduced in duodenum at 3-day post-SCI. Caudal mesenteric artery flow was unchanged by SCI at 3 days or 3 weeks despite significant reductions in mean arterial pressure. Conclusion: These data show that T3-SCI provokes elevated mucosal oxidative stress, altered expression of TJ proteins, and elevated intestinal barrier permeability in the proximal intestine. In contrast, mucosal oxidative stress and intestinal barrier permeability were unchanged in the hindgut after SCI. This regional heterogeneity may result from differential sensitivity to reduced mesenteric perfusion, though further studies are required to establish a causal link. Understanding regional differences in intestinal pathophysiology is essential for developing effective treatments and standards of care for individuals with SCI. [ABSTRACT FROM AUTHOR]

Simple Summary: Acute heat stress in animals impairs the intestinal barrier function, particularly tight junction (TJ) depression, which occurs in pigs owing to the lack of functional sweat glands for evaporative heat loss. However, the mechanisms by which heat stress affects TJ regulation are not fully understood. We investigated the effect of heat stress on the TJ and its interaction with potential genes using transcriptomic analysis of the porcine jejunum. We found that heat stress reduced the expression of TJ proteins and induced alterations in genes involved in the actin cytoskeleton and filament-binding pathways. We aimed to investigate the impact of heat stress (HS) on the expression of tight junction (TJ) proteins and the interaction between genes affecting intestinal barrier function using transcriptomics in the porcine jejunum. Twenty-four barrows (crossbred Yorkshire × Landrace × Duroc; average initial body weight, 56.71 ± 1.74 kg) were placed in different temperatures (normal temperature [NT]; HS) and reared for 56 days. At the end of the experiment, jejunal samples were collected from three pigs per treatment for transcriptome and reverse-transcription quantitative polymerase chain reaction (RT-qPCR) analyses. We identified 43 differentially expressed genes, involving five Kyoto Encyclopedia of Genes and Genomes pathways, eight molecular functions, seven cellular components (CCs), and nine biological processes, using gene ontology enrichment analysis. Genes associated with the actin cytoskeleton, filament-binding pathways, and TJ proteins were selected and analyzed by RT-qPCR. Significant differences in relative mRNA expression showed that downregulated genes in the HS group included ZO1, CLDN1, OCLN, PCK1, and PCK2, whereas ACTG2, DES, MYL9, MYLK, TPM1, TPM2, CNN1, PDLIM3, and PCP4 were upregulated by HS (p < 0.05). These findings indicate that HS in growing-finishing pigs induces depression in gut integrity, which may be related to genes involved in the actin cytoskeleton and filaments of CC. [ABSTRACT FROM AUTHOR]

Background/Aim: Inflammatory bowel disease (IBD) is characterized by dysregulated immune responses and a multifactorial etiology. While imatinib has demonstrated efficacy in the treatment of immune-related diseases, its potential effects in IBD treatment remain underexplored. Materials and Methods: This study aimed to investigate the therapeutic effects of imatinib in colitis treatment. A dextran sulfate sodium (DSS)-induced colitis model was used to mimic IBD in mice. Imatinib was administered orally to mice simultaneously with DSS treatment. The effects of imatinib on DSS-induced colitis were evaluated by analyzing colitis-related pathology, including the disease activity index (DAI), histological lesions, inflammatory markers, and tight junction integrity. Additionally, western blot analysis and quantitative real-time polymerase chain reaction were used to assess inflammatory markers, tight-junction proteins, and cell death. Results: In the DSS-induced colitis model, imatinib treatment exerted protective effects by attenuating weight loss, restoring colon length, reducing spleen weight, and improving the DAI score and histological lesions. Additionally, imatinib reduced the level of proinflammatory cytokines, including TNF- α, IL-6, and IL-1β. Furthermore, imatinib treatment restored tight-junction integrity and decreased the expression of apoptosis marker proteins. Conclusion: Overall, imatinib treatment significantly alleviated the symptoms of DSS-induced colitis by influencing the expression of proinflammatory cytokines, tight junction proteins, and apoptotic markers in mice. These findings highlight imatinib as a potential therapeutic candidate for IBD. [ABSTRACT FROM AUTHOR]

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. Conclusions 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.

Early nutritional management approach greatly impacts broilers’ performance and resistance against coccidiosis. The current study explored the impact of post-hatch feeding with a combination of glutamine (Glut) and different levels of omega-3 on broiler chickens’ growth performance, muscle building, intestinal barrier, antioxidant ability and protection against avian coccidiosis. A total of six hundred Cobb 500 was divided into six groups: first group (fed basal diet and unchallenged (control) and challenged (negative control, NC) groups were fed a basal diet without additives, and the other groups were infected with Eimeria spp and supplemented with 1.5% Glut alone or with three different levels of omega-3 (0.25, 0.5 and 1%) during the starter period. Notable improvement in body weight gain was observed in the group which fed basal diet supplemented with glut and 1% omega 3 even after coccidia infection (increased by 25% compared challenged group) while feed conversion ratio was restored to control. Myogeneis was enhanced in the group supplemented with Glut and omega-3 (upregulation of myogenin, MyoD, mechanistic target of rapamycin kinase and insulin like growth factor-1 and downregulating of myostatin genes). Groups supplemented with Glut and higher levels of omega-3 highly expressed occluding, mucin-2, junctional Adhesion Molecule 2, b-defensin-1 and cathelicidins-2 genes. Group fed 1% Glut + omega-3 showed an increased total antioxidant capacity and glutathione peroxidase and super oxide dismutase enzymes activities with reduced levels of malondialdehyde, reactive oxygen species and H2O2. Post-infection, dietary Glut and 1% omega-3 increased intestinal interleukin-10 (IL) and secretory immunoglobulin-A and serum lysozyme, while decreased the elevated inflammatory mediators comprising interleukin IL-6, tumor necrosis factor-alpha, nitric oxide (NO) and inducible NO synthase. Fecal oocyst excretion and lesions score severity were lowered in the group fed 1% Glut and omega 3. Based on these findings, dietary Glut and omega-3 supplementation augmented restored overall broilers’ performance after coccidial challenge.

Porcine epidemic diarrhea (PED) is a highly contagious disease caused by the porcine epidemic diarrhea virus (PEDV), which results in significant economic losses. PEDV infection causes severe damage to the midgut barrier in the small intestine. YBX3, an important protein in tight junctions, promotes epithelial cell proliferation. However, its role in the process of PEDV infection remains unclear. In this study, we observed a significant increase in mRNA expression of YBX3 following PEDV infection. Additionally, the protein expression of YBX3 showed an initial increase followed by a decrease over time. Furthermore, treatment with 2% DSS resulted in a significant down-regulation of YBX3 mRNA and protein expression. Furthermore, we successfully generated knockout and overexpression cell lines of YBX3. Preliminary assays indicated that elevated expression of YBX3 inhibited the PEDV replication, while knockout of YBX3 had the opposite effect. In conclusion, our study has preliminarily revealed the functional role of YBX3 during PEDV infection. This finding lays the foundation for further investigation into its mechanism in future and also provides new insights into the mechanism of PEDV–host interactions. [ABSTRACT FROM AUTHOR]

Subways are widely used in major cities around the world, and subway fine particulate matter (PM2.5) is the main source of daily PM2.5 exposure for urban residents. Exposure to subway PM2.5 leads to acute inflammatory damage in humans, which has been confirmed in mouse in vivo studies. However, the concrete mechanism by which subway PM2.5 causes airway damage remains obscure. In this study, we found that subway PM2.5 triggered release of pro‐inflammatory cytokines such as interleukin 17E, tumor necrosis factor α, transforming growth factor β, and thymic stromal lymphopoietin from human bronchial epithelial cells (BEAS‐2B) in a dose–effect relationship. Subsequently, supernatant recovered from the subway PM2.5 group significantly increased expression of the aforementioned cytokines in BEAS‐2B cells compared with the subway PM2.5 group. Additionally, tight junctions (TJs) of BEAS‐2B cells including zonula occludens‐1, E‐cadherin, and occludin were decreased by subway PM2.5 in a dose‐dependent manner. Moreover, supernatant recovered from the subway PM2.5 group markedly decreased the expression of these TJs compared with the control group. Furthermore, inhibitors of toll‐like receptors (TLRs) and nuclear factor‐kappa B (NF‐κB), as well as chelate resins (e.g., chelex) and deferoxamine, remarkably ameliorated the observed changes of cytokines and TJs caused by subway PM2.5 in BEAS‐2B cells. Therefore, these results suggest that subway PM2.5 induced a decline of TJs after an initial ascent of cytokine expression, and subway PM2.5 altered expression of both cytokines and TJs by activating TLRs/NF‐κB‐dependent pathway in BEAS‐2B cells. The metal components of subway PM2.5 may contribute to the airway epithelial injury. [ABSTRACT FROM AUTHOR]

The healing process after acne lesion extraction provides a miniature model to study skin wound repair mechanisms. In this study, we aimed to identify solutions for acne scars that frequently occur on our faces. We performed acne scar cytokine profiling and found that Interleukin 8 (IL8) and Tissue inhibitor of metalloproteinases 2 (TIMP2) were significant factors at the wounded site. The effect of chlorogenic acid and taurine on human epidermal cells and irritated human skin was investigated. Chlorogenic acid and taurine regulated IL8 and TIMP2 expression and accelerated keratinocyte proliferation. Moreover, tight junction protein expression was upregulated by chlorogenic acid and taurine synergistically. Further, these compounds modulated the expression of several inflammatory cytokines (IL1α, IL1β, and IL6) and skin hydration related factor (hyaluronan synthase 3; HAS3). Thus, chlorogenic acid and taurine may exert their effects during the late stages of wound healing rather than the initial phase. In vivo experiments using SLS-induced wounds demonstrated the efficacy of chlorogenic acid and taurine treatment compared to natural healing, reduced erythema, and restored barrier function. Skin ultrasound analysis revealed their potential to promote denser skin recovery. Therefore, the wound-restoring effect of chlorogenic acid and taurine was exerted by suppression of inflammatory cytokines, and induction of cell proliferation, tight junction expression, and remodeling factors.

Abstract Background Airway epithelial cell (AEC) necroptosis contributes to airway allergic inflammation and asthma exacerbation. Targeting the tumor necrosis factor-like ligand 1 A (TL1A)/death receptor 3 (DR3) axis has a therapeutic effect on asthmatic airway inflammation. The role of TL1A in mediating necroptosis of AECs challenged with ovalbumin (OVA) and its contribution to airway inflammation remains unclear. Methods We evaluated the expression of the receptor-interacting serine/threonine-protein kinase 3(RIPK3) and the mixed lineage kinase domain-like protein (MLKL) in human serum and lung, and histologically verified the level of MLKL phosphorylation in lung tissue from asthmatics and OVA-induced mice. Next, using MLKL knockout mice and the RIPK3 inhibitor GSK872, we investigated the effects of TL1A on airway inflammation and airway barrier function through the activation of necroptosis in experimental asthma. Results High expression of necroptosis marker proteins was observed in the serum of asthmatics, and necroptosis was activated in the airway epithelium of both asthmatics and OVA-induced mice. Blocking necroptosis through MLKL knockout or RIPK3 inhibition effectively attenuated parabronchial inflammation, mucus hypersecretion, and airway collagen fiber accumulation, while also suppressing type 2 inflammatory factors secretion. In addition, TL1A/ DR3 was shown to act as a death trigger for necroptosis in the absence of caspases by silencing or overexpressing TL1A in HBE cells. Furthermore, the recombinant TL1A protein was found to induce necroptosis in vivo, and knockout of MLKL partially reversed the pathological changes induced by TL1A. The necroptosis induced by TL1A disrupted the airway barrier function by decreasing the expression of tight junction proteins zonula occludens-1 (ZO-1) and occludin, possibly through the activation of the NF-κB signaling pathway. Conclusions TL1A-induced airway epithelial necroptosis plays a significant role in promoting airway inflammation and barrier dysfunction in asthma. Inhibition of the TL1A-induced necroptosis pathway could be a promising therapeutic strategy.

AIM:To investigate the effects of overexpressing α-Klotho(KL)in RAW264.7 cells stimulated by oxidative stress on the proliferation, migration, tube-formation and tight junction of human umbilical vein endothelial cells(HUVECs).METHODS:RAW264.7 cells were categorized into control, 4-hydroxynonenal(4HNE), and 4HNE+KL groups, with F4/80 expression assessed via immunofluorescence staining. Three groups of conditional media were prepared for HUVECs and culture divided into Mø-NC, Mø-4HNE, and Mø-4HNE+KL groups. Cell proliferation was evaluated using CCK8 assay, while scratch test and Transwell assays were employed to measure cell migration. Additionally, tube-formation assay was conducted to assess cell tubule formation, and Western blot assay was utilized to detect the protein expression levels of Claudin 5, Occludin and ZO 1.RESULTS:The results of immunofluorescence staining showed that the fluorescence intensity of F4/80 of RAW264.7 cells in the 4HNE group was significantly enhanced compared with the control group, while that of F4/80 in the 4HNE+KL group was significantly decreased compared with the 4HNE group(all P

Abstract Background Sepsis is one of the most common clinical diseases, which is characterized by a serious and uncontrollable inflammatory response. LPS-induced inflammation is a critical pathological event in sepsis, but the underlying mechanism has not yet been fully elucidated. Methods The animal model was established for two batches. In the first batch of experiments, Adult C57BL/6J mice were randomly divided into control group and LPS (5 mg/kg, i.p.)group . In the second batch of experiments, mice were randomly divided into control group, LPS group, and LPS+VX765(10 mg/kg, i.p., an inhibitor of NLRP3 inflammasome) group. After 24 hours, mice were anesthetized with isoflurane, blood and intestinal tissue were collected for tissue immunohistochemistry, Western blot analysis and ELISA assays. Results The C57BL/6J mice injected with LPS for twenty-four hours could exhibit severe inflammatory reaction including an increased IL-1β, IL-18 in serum and activation of NLRP3 inflammasome in intestine. The injection of VX765 could reverse these effects induced by LPS. These results indicated that the increased level of IL-1β and IL-18 in serum induced by LPS is related to the increased intestinal permeability and activation of NLRP3 inflammasome. In the second batch of experiments, results of western blot and immunohistochemistry showed that Slit2 and Robo4 were significant decreased in intestine of LPS group, while the expression of VEGF was significant increased. Meanwhile, the protein level of tight junction protein ZO-1, occludin, and claudin-5 were significantly lower than in control group, which could also be reversed by VX765 injection. Conclusions In this study, we revealed that Slit2-Robo4 signaling pathway and tight junction in intestine may be involved in LPS-induced inflammation in mice, which may account for the molecular mechanism of sepsis.

Hui Liu,1,2 Xuan Xu,3 Ji Li,3 Zheyu Liu,1 Yuwen Xiong,1 Mengli Yue,4 Pi Liu1 1Department of Gastroenterology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, People’s Republic of China; 2Gastroenterology Institute of Jiangxi Province, Nanchang, People’s Republic of China; 3Department of Gastroenterology, The People’s Hospital of Longhua, Shenzhen, People’s Republic of China; 4Affiliated Longhua People’s Hospital, The Third School of Clinical Medicine, Southern Medical University, Shenzhen, People’s Republic of ChinaCorrespondence: Pi Liu, Department of Gastroenterology, The First Affiliated Hospital, Jiangxi Medical College, Nanchang University, Nanchang, People’s Republic of China, Tel +86-13507913736, Email liupi126@sina.comPurpose: Capillary leak syndrome (CLS) is an intermediary phase between severe acute pancreatitis (SAP) and multiple organ failure. As a result, CLS is of clinical importance for enhancing the prognosis of SAP. Plakophilin2 (PKP2), an essential constituent of desmosomes, plays a critical role in promoting connections between epithelial cells. However, the function and mechanism of PKP2 in CLS in SAP are not clear at present.Methods: We detected the expression of PKP2 in mice pancreatic tissue by transcriptome sequencing and bioinformatics analysis. PKP2 was overexpressed and knocked down to assess its influence on cell permeability, the cytoskeleton, tight junction molecules, cell adhesion junction molecules, and associated pathways.Results: PKP2 expression was increased in the pancreatic tissues of SAP mice and human umbilical vein endothelial cells (HUVECs) after lipopolysaccharide (LPS) stimulation. PKP2 overexpression not only reduced endothelial cell permeability but also improved cytoskeleton relaxation in response to acute inflammatory stimulation. PKP2 overexpression increased levels of ZO-1, occludin, claudin1, β-catenin, and connexin43. The overexpression of PKP2 in LPS-induced HUVECs counteracted the inhibitory effect of SB203580 (a p38/MAPK signaling pathway inhibitor) on the p38/MAPK signaling pathway, thereby restoring the levels of ZO-1, β-catenin, and claudin1. Additionally, PKP2 suppression eliminated the enhanced levels of ZO-1, β-catenin, occludin, and claudin1 induced by dehydrocorydaline. We predicted that the upstream transcription factor PPARγregulates PKP2 expression, and our findings demonstrate that the PPARγactivator rosiglitazone significantly upregulates PKP2, whereas its antagonist GW9662 down-regulates PKP2. Administration of rosiglitazone significantly reduced the increase in HUVECs permeability stimulated by LPS. Conversely, PKP2 overexpression counteracted the GW9662-induced reduction in ZO-1, phosphorylated p38/p38, and claudin1.Conclusion: The activation of the p38/MAPK signaling pathway by PKP2 mitigates CLS in SAP. PPARγactivator rosiglitazone can up-regulate PKP2. Overall, directing efforts toward PKP2 could prove to be a feasible treatment approach for effectively managing CLS in SAP. Keywords: severe acute pancreatitis, plakophilin2, capillary leak syndrome, tight junction, p38/MAPK signaling pathway

Abstract Claudin-5 is one of the most essential tight junction proteins at the blood-brain barrier. A single nucleotide polymorphism rs10314 is located in the 3’-untranslated region of claudin-5 and has been shown to be a risk factor for schizophrenia. Here, we show that the pumilio RNA-binding protein, pumilio-1, is responsible for rs10314-mediated claudin-5 regulation. The RNA sequence surrounding rs10314 is highly homologous to the canonical pumilio-binding sequence and claudin-5 mRNA with rs10314 produces 25% less protein due to its inability to bind to pumilio-1. Pumilio-1 formed cytosolic granules under stress conditions and claudin-5 mRNA appeared to preferentially accumulate in these granules. Added to this, we observed granular pumilio-1 in endothelial cells in human brain tissues from patients with psychiatric disorders or epilepsy with increased/accumulated claudin-5 mRNA levels, suggesting translational claudin-5 suppression may occur in a brain-region specific manner. These findings identify a key regulator of claudin-5 translational processing and how its dysregulation may be associated with neurological and neuropsychiatric disorders. Graphical Abstract

Limonene, a dietary monocyclic monoterpene commonly found in citrus fruits and various aromatic plants, has garnered increasing interest as a gastrointestinal protectant. This study aimed to assess the effects of limonene on intestinal epithelial barrier function and investigate the involvement of cannabinoid receptor type‐1 (CB1R) in vitro. Additionally, the study focused on examining the metabolomic changes induced by limonene in the intestinal epithelial cells (Caco‐2). Initial analysis of transepithelial electrical resistance (TEER) revealed that both l‐limonene and d‐limonene, isomers of limonene, led to a dose‐ and time‐dependent increase in TEER in normal cells and those inflamed by pro‐inflammatory cytokines mixture (CytoMix). Furthermore, both types of limonene reduced CytoMix‐induced paracellular permeability, as demonstrated by a decrease in Lucifer yellow flux. Moreover, d‐limonene and l‐limonene treatment increased the expression of tight junction molecules (TJs) such as occludin, claudin‐1, and ZO‐1, at both the transcriptional and translational levels. d‐Limonene upregulates E‐cadherin, a molecule involved in adherens junctions (AJs). Mechanistic investigations demonstrated that d‐limonene and l‐limonene treatment significantly inhibited CB1R at the protein, while the mRNA level remained unchanged. Notably, the inhibitory effect of d‐limonene on CB1R was remarkably similar to that of pharmacological CB1R antagonists, such as rimonabant and ORG27569. d‐limonene also alters Caco‐2 cell metabolites. A substantial reduction in β‐glucose and 2‐succinamate was detected, suggesting limonene may impact intestinal epithelial cells' glucose uptake and glutamate metabolism. These findings suggest that d‐limonene's CB1R antagonistic property could effectively aid in the recovery of intestinal barrier damage, marking it a promising gastrointestinal protectant. [ABSTRACT FROM AUTHOR]

Objective: Vitamin D/Vitamin D receptor (VD/VDR) signaling and the Notch pathway are involved in intestinal barrier restoration in colitis; however, their relationship and underlying mechanism are largely unknown. Therefore, this study aimed to investigate the role and mechanism of VD/VDR and the Notch pathways in intestinal barrier protection. Methods: Genetic Vdr knockout (VDR KO) and VD deficient (VDd) mice were established, and colitis was induced by feeding 2.5% dextran sodium sulfate (DSS) water. Mechanistic studies, including real-time PCR, immunofluorescence, Western blotting and dual-luciferase reporter assays, were performed on cultured Caco-2 cells and intestinal organoids. Results: VD deficiency and VDR genetical KO increased the severity of DSS-induced colitis in mice, which presented a higher disease activity index score, increased intestinal permeability, and more severe intestinal histological damage than controls, accompanied by decreased and disrupted claudin-1 and claudin-3. Moreover, inhibition of Notch pathway by LY411,575 aggravated the severity of DSS-induced colitis and intestinal injury. In Caco-2 cells and intestinal organoids, the expression of Notch-1, N1ICD and Hes1 decreased upon downregulation or KO of VDR but increased upon paricalcitol (PAR, a VDR agonist) treatment. Meanwhile, PAR rescued claudin-1 and claudin-3 impairments that resulted from TNF-α exposure but failed to restore claudin-3 upon Notch inhibition. The dual-luciferase reporter assay further suggested that VD/VDR positively regulated the Notch signaling pathway by modulating Notch-1 transcription. Conclusion: VD/VDR positively modulates Notch activation by promoting Notch-1 transcription to maintain intestinal tight junction integrity and barrier function. This highlights the VD/VDR-Notch pathway as a potential new therapeutic target for protecting the intestinal barrier against ulcerative colitis. [ABSTRACT FROM AUTHOR]

Transmigration of circulating monocytes from the bloodstream to tissues represents an early hallmark of inflammation. This process plays a pivotal role during viral neuroinvasion, encephalitis, and HIV-associated neurocognitive disorders. How monocytes locally unzip endothelial tight junction-associated proteins (TJAPs), without perturbing impermeability, to reach the central nervous system remains poorly understood. Here, we show that human circulating monocytes express the TJAP Occludin (OCLN) to promote transmigration through endothelial cells. We found that human monocytic OCLN (hmOCLN) clusters at monocyte-endothelium interface, while modulation of hmOCLN expression significantly impacts monocyte transmigration. Furthermore, we designed OCLN-derived peptides targeting its extracellular loops (EL) and show that transmigration of treated monocytes is inhibited in vitro and in zebrafish embryos, while preserving vascular integrity. Monocyte transmigration toward the brain is an important process for HIV neuroinvasion and we found that the OCLN-derived peptides significantly inhibit HIV dissemination to cerebral organoids. In conclusion, our study identifies an important role for monocytic OCLN during transmigration and provides a proof-of-concept for the development of mitigation strategies to prevent monocyte infiltration and viral neuroinvasion. Synopsis: This study highlights the contribution of Occludin (OCLN) expressed by monocytes during transmigration. Targeting monocytic Occludin prevents monocyte transmigration, which is sufficient for potent inhibition of HIV neuroinvasion. Silencing monocytic OCLN decreases transmigration through endothelial cells, while its re-expression increases transmigration. Using a short peptide from the extracellular loop 2 of OCLN prevents transmigration of monocytes in vitro and in zebrafish. HIV-carrying monocyte transmigration is critical for HIV neuroinvasion of cerebral organoids. HIV neuroinvasion is abrogated by OCLN-derived peptides. This study highlights the contribution of Occludin (OCLN) expressed by monocytes during transmigration. Targeting monocytic Occludin prevents monocyte transmigration, which is sufficient for potent inhibition of HIV neuroinvasion. [ABSTRACT FROM AUTHOR]

AIM: To establish and evaluate a colonoids model of intestinal barrier dysfunction with irritable bowel syndrome (IBS). METHODS: The colonic recess of 20~22 g male C57BL/6 mice were isolated and cultured in matrix glue to proliferate and differentiate into 3D hollow spheres with colonic epithelioid structure. The following experiments were carried out: (1) Colonoids and colonic tissues of mice were detected by immunofluorescence to identify colonoids. (2) Fluorescein isothiocyanate dextran 4 (FD4) evaluated the epithelial barrier function of colonoids. (3) To explore the changes in the epithelial barrier of colonoids induced by interferon-γ (IFN-γ) at different concentrations and time points. FD4 and HE staining were used to evaluate the barrier function. RT-qPCR was used to detect the mRNA expression of occludin and zonula occludens-1 (ZO-1) in tight junctions of colonoids. Immunofluorescence was used to detect the distribution and localization of occludin and ZO-1 proteins. RESULTS: (1) The expression of EdU proliferation and intestinal epithelial cell lineage markers in colonoids was consistent with that in mouse colonic tissues. (2) In the control group, FD4 did not infiltrate the colonoids lumen, but FD4 significantly infiltrated the colonoids lumen induced by ethyl‐ ene glycol-bis (β-aminoethyl ether）-N, N, N', N'-tetraacetic acid (EGTA). (3) From 18 h, the IFN-γ at 60, 100, 200 and 240 ng/mL could significantly infiltrate into the cavity of colonoids (0. 033, 0. 032, 0. 042 and 0. 001), and the barri‐ er injury of colonoids could be seen by HE staining. After 18 h, all concentrations of IFN-γ could significantly decrease the mRNA expression of occludin and ZO-1, and the fluorescence of occludin and ZO-1 decreased significantly (P< 0. 05). CONCLUSION: (1) The cultured organoids are colonoids with complete epithelial barrier. (2) IFN-γ could in‐ duce the decrease of the transcriptional levels of occludin and ZO-1 in the tight junction of colonoids, the decrease of the expression of corresponding proteins, and the change of localization and distribution, thus increasing the epithelial perme-ability of colonoids. This model is highly consistent with the pathophysiological state of IBS colonic mucosal barrier dysfunction, which provides a new tool and method for studying the direction of colonic mucosal barrier dysfunction in IBS. [ABSTRACT FROM AUTHOR]

Objective: To investigate effect of Yiqi Huoxue Huazhuo Jiedu Prescription （YHHJP） on inflammatory factors of brain tissues, tight junction between brain and colon tissues, intestinal flora and bacterial metabolites in cerebral ischemia reperfusion injury （CIRI） rats based on brain-gut axis. Methods: Fifty male SD rats of SPF grade were randomly divided into sham-operation group （Sham）, model group （MCAO）, low, medium, high doses YHHJP groups （TCM-L/TCM-M/TCM-H）. Middle cerebral artery occlusion model was established according to Zea Longa methods. Neurological function defects were detected 3 days after administration. TTC staining was used to calculate infarct size of brain tissue. Pathological changes of brain tissue were observed by Nissl staining, and pathological changes of brain and colon tissues were observed by HE staining. IL-1β, IL-6, TNF-α in brain tissue and LPS content in serum were detected by ELISA, and D-LA content in serum was detected by biochemical method. Gene expressions of ZO-1 and Claudin-5 in brain tissue and gene expressions of ZO-1, Claudin-1 in colon tissue were studied by Real-time fluorescent quantitative PCR. Intestinal flora were detected by 16S rDNA high-throughput sequencing. Results: Compared with Sham group, pathological damage of brain and colon tissue were serious in MCAO group, intestinal flora structure was significantly different, neural function impairment was aggravated, infarct size was increased, IL-1β, IL-6, TNF-α contents in brain tissue, and LPS, D-LA contents in serum were increased, gene expressions of ZO-1 and Claudin-5 in brain tissue and gene expressions of ZO-1 and Claudin-1 in colon tissue were decreased significantly （P<0.05）. Compared with MCAO group, pathological damage of brain and colon tissue of rats were relieved in TCM-L, TCM-M, TCM-H groups, disturbance of intestinal microflora microecology was improved, neurological function impairment and infarct size were markedly decreased, IL-1β, IL-6, TNF-α contents in brain tissue were decreased, gene expressions of ZO-1 and Claudin-1 in colon tissue were increased significantly （P<0.05）; LPS and D-LA contents in serum were decreased in YHHJP medium and high doses groups, while gene expressions of ZO-1 and Claudin-5 in brain tissue were increased significantly （P< 0.05）. Conclusion: YHHJP has a good effect on improving CIRI, whose mechanism may be related to regulating diversity of intestinal flora, reducing release of intestinal bacterial metabolites LPS and D-LA, increasing gene expressions of tight junction proteins ZO-1, Claudin-5 and Claudin-1, and down-regulating secretion of proinflammatory cytokine. [ABSTRACT FROM AUTHOR]

Background: Although low-level laser therapy (LLLT) is a widely used noninvasive treatment because of photobiomodulation effects, its application for xerostomia remained uncertain. Tight junctions (TJs), mainly composed of claudins, occludin, and ZO family members, are crucial structures that determine material transport through paracellular pathway in salivary gland epithelial cells. This work aimed to investigate whether LLLT affected salivary secretion through epithelial TJs. Methods: Transepithelial electrical resistance (TER) measurement and paracellular permeability assay were applied to evaluate paracellular permeability in submandibular gland (SMG)-C6 cells after irradiation with 540 nm green light. Immunofluorescence and western blot were used to detect the expression of TJ proteins. Quantitative phosphoproteomics were performed to explore possible intracellular signals. Results: We found that irradiation with 540 nm green light significantly decreased TER values while increased paracellular transport in SMG-C6 cells. 540 nm green light-induced redistribution of claudin-1, -3, and -4, but not occludin or ZO-1. Moreover, above phenomena were abolished by preincubation with capsazepine, an antagonist of transient receptor potential vanilloid subtype 1. Notably, irradiation with 540 nm green light on the skin covering the whole submandibular gland regions promoted salivary secretion and attenuated lymphocytic infiltration in 21-week-old non-obese diabetic mice (n = 5 per group), a xerostomia animal model for Sjögren's syndrome. Through in-depth bioinformatics analysis and expression verification, ERK1/2 and EphA2 served as potential canonical and noncanonical signals underlying 540 nm green light. Conclusions: Our findings uncovered the novel therapeutic effects of 540 nm green light on xerostomia through regulation on the expression and distribution of TJs. [ABSTRACT FROM AUTHOR]

Ulcerative colitis (UC) is a prevalent inflammatory disorder that emerges in the colon and rectum, exhibiting a rising global prevalence and seriously impacting the physical and mental health of patients. Significant challenges remain in UC treatment, highlighting the need for safe and effective long-term therapeutic approaches. Heralded as a promising physical treatment, the rotating magnetic field (RMF) demonstrates safety, stability, manageability, and efficiency. This study delves into RMF's potential in mitigating DSS-induced UC in mice, assessing disease activity indices (DAI) and pathological alterations such as daily body weight, fecal occult blood, colon length, and morphological changes. Besides, several indexes have been detected, including serum concentrations of pro-inflammatory cytokines (IL6, IL-17A, TNF-α, IFN-γ) and anti-inflammatory cytokines (TGF-β, IL-4, IL-10), the ratio of splenic CD3+, CD4+, and CD8+ T cells, the rate of apoptotic colonic cells, the expression of colonic inflammatory and tight junction-associated proteins. The results showed that RMF had beneficial effects on the decrease of intestinal permeability, the restoration of tight junctions, and the mitigation of mitochondrial respiratory complexes (MRCs) by attenuating inflammatory dysfunction in colons of DSS-induced UC model of mice. In conclusion, this study demonstrates that RMF attenuates colonic inflammation, enhances colonic tight junction, and alleviates MRCs impairment by regulating the equilibrium of pro-inflammatory and anti-inflammatory cytokines in UC mice, suggesting the potential application of RMF in the clinical treatment of UC. • RMF mitigates disease activity indices and pathological alterations in UC mice. • RMF attenuates colonic inflammation and enhances colonic tight junction in UC mice. • RMF alleviates MRC impairment in UC mice. • RMF regulates the pro- and anti-inflammatory cytokine equilibrium in UC mice. • RMF is potentially available as a physical therapy for UC. [ABSTRACT FROM AUTHOR]

1. An experiment was conducted to determine differences in the expression of genes encoding intestinal barrier proteins between fast, medium and slow-growing chickens. Chicken breeds Athens Canadian Random Bred (ACRB), Longenecker's Heritage (LHR), RedBro, Hubbard H1 (HH1), Cobb500 and Ross708 were raised from hatch for 35 d. 2. Ileal samples were collected at embryonic day E19 (−2 days post-hatch), hatch and d 7, 14, 21, 28 and 35 post-hatch to assess the expression of genes encoding tight junction proteins (claudins, CLDN; occludin, OCLN; zonula occludens, ZO; and junctional adhesion molecules, JAM), mucin (Muc2), immunoglobulin A (IgA), polymeric immunoglobulin receptor (pIgR) and fatty acid binding protein (FABP2). 3. Expression of CLDN-1 was increased (p < 0.0001) in LHR compared to Cobb500 while CLDN-5 was increased (p < 0.0001) in ACRB, HH1, RedBro and Ross708 compared to LHR as well as in ACRB compared to Cob500. Occludin was upregulated (p = 0.01) in ACRB and LHR compared to Ross708 at d 14 post-hatch. Expression of ZO-1 was upregulated (p = 0.001) in LHR compared to Ross708, HH1 and Cobb500. Tight junction genes, except CLDN-4, JAM-2 and JAM-3 were downregulated (p < 0.0001) at hatch and d 7 post-hatch. Expression of Muc2 was increased (p < 0.0001) in LHR compared to RedBro and from −2 d to d 7 post-hatch. 4. Immunoglobulin A was increased (p = 0.001) in LHR compared to Ross708 and HH1 at −2 d post-hatch and in LHR compared to ACRB, Cobb500 and Ross708 at hatch. In addition, IgA expression was increased in all breeds at d 14 post-hatch while pIgR was upregulated (p = 0.02) in Cobb500 and Ross708 compared to ACRB, HH1, LHR and RedBro at hatch. 5. The gene expression patterns suggest that selection for growth may have not induced changes in junctional complexes and immune defence genes. However, the results confirmed that the expression of these genes is age dependent. [ABSTRACT FROM AUTHOR]

Various metabolic diseases caused by a high‐fat diet (HFD) are closely related to gut microbiota dysbiosis and epithelial barrier dysfunction. Polycan, a type of β‐glucan, is effective in treating anti‐obesity and metabolic diseases caused by HFD. However, the effect of Polycan on dysbiosis and epithelial barrier damage is still unknown. In this study, the effects of Polycan on dysbiosis and intestinal barrier damage were investigated using HFD‐induced obese model mice. C57BL/6 mice were fed a HFD for 12 weeks and treated with two different doses of Polycan (250 and 500 mg/kg) orally administered during weeks 9 to 12. Polycan supplementation increased the expression of tight junction genes (zonula occludens‐1, occludin, and claudin‐3) and short‐chain fatty acid (SCFA) content while reducing toxic substances (phenol, p‐cresol, and skatole). Most significantly, Polycan enriched SCFA‐producing bacteria (i.e., Phocaeicola, Bacteroides, Faecalibaculum, Oscillibacter, Lachnospiraceae, and Muribaculaceae), and decreased the Firmicutes/Bacteroidetes ratio and toxic substances‐producing bacteria (i.e., Olsenella, Clostridium XVIII, and Schaedlerella). Furthermore, microbial functional capacity prediction of the gut microbiota revealed that Polycan enriched many SCFA‐related KEGG enzymes while toxic substance‐related KEGG enzymes were depleted. These findings indicated that Polycan has the potential to alleviate HFD‐induced intestinal barrier damage by modulating the function and composition of the gut microbiota. [ABSTRACT FROM AUTHOR]

Cell-cell contact formation of polarized epithelial cells is a multi-step process that involves the co-ordinated activities of Rho family small GTPases. Consistent with the central role of Rho GTPases, a number of Rho guanine nucleotide exchange factors (GEFs) and Rho GTPase-activating proteins (GAPs) have been identified at cell-cell junctions at various stages of junction maturation. As opposed to RhoGEFs and RhoGAPs, the role of Rho GDP dissociation inhibitors (GDIs) during cell-cell contact formation is poorly understood. Here, we have analyzed the role of RhoGDI1/ARHGDIA, a member of the RhoGDI family, during cell-cell contact formation of polarized epithelial cells. Depletion of RhoGDI1 delays the development of linear cellcell junctions and the formation of barrier-forming tight junctions. In addition, RhoGDI1 depletion impairs the ability of cells to stop migration in response to cell collision and increases the migration velocity of collectively migrating cells. We also find that the cell adhesion receptor JAM-A promotes the recruitment of RhoGDI1 to cell-cell contacts. Our findings implicate RhoGDI1 in various processes involving the dynamic reorganization of cell-cell junctions. [ABSTRACT FROM AUTHOR]

The production of nanoparticles has recently surged due to their varied applications in the biomedical, pharmaceutical, textile, and electronic sectors. However, this rapid increase in nanoparticle manufacturing has raised concerns about environmental pollution, particularly its potential adverse effects on human health. Among the various concerns, inhalation exposure to nanoparticles poses significant risks, especially affecting the respiratory system. Airway epithelial cells play a crucial role as the primary defense against inhaled particulate matter and pathogens. Studies have shown that nanoparticles can disrupt the airway epithelial barrier, triggering inflammatory responses, generating reactive oxygen species, and compromising cell viability. However, our understanding of how different types of nanoparticles specifically impact the airway epithelial barrier remains limited. Both in vitro cell culture and in vivo murine models are commonly utilized to investigate nanoparticle-induced cellular responses and barrier dysfunction. This review discusses the methodologies frequently employed to assess nanoparticle toxicity and barrier disruption. Furthermore, we analyze and compare the distinct effects of various nanoparticle types on the airway epithelial barrier. By elucidating the diverse responses elicited by different nanoparticles, we aim to provide insights that can guide future research endeavors in assessing and mitigating the potential risks associated with nanoparticle exposure. [ABSTRACT FROM AUTHOR]

Diabetes mellitus, as a chronic metabolic disorder, significantly impacts the pancreas and among other organs, affects duodenal function. Emerging evidence suggests that probiotics can exert beneficial effects on gut health and metabolism. In our previous research, we evaluated the probiotic Lactobacillus paraplantarum BGCG11 primarily for its protective properties against diabetic rats' damaged liver and kidneys. In this work, we further examined the effects of probiotic strain BGCG11 on the function of the duodenum and pancreas in diabetic rats. We explored the potential mechanisms underlying the probiotic's effects, focusing on general indicators of diabetes, the architecture and morphology of pancreatic islets, duodenal integrity (measuring the transfer of fluid and serum zonulin level), and the modulation of gut microbiota composition. Our findings reveal the protective and regulatory roles of L. paraplantarum BGCG11 in mitigating diabetes-induced pancreatic and duodenal dysfunction regardless of its application time (pre- or post-treatment), highlighting its therapeutic potential in managing diabetes-related gastrointestinal complications. [ABSTRACT FROM AUTHOR]

Circadian rhythm plays an important role in intestinal homeostasis and intestinal immune function. Circadian rhythm dysregulation was reported to induce intestinal microbiota dysbiosis, intestinal barrier disruption, and trigger intestinal inflammation. However, the relationship between intestinal microbiota metabolites and the circadian rhythm of the intestinal barrier was still unclear. Urolithin A (UA), a kind of intestinal microbial metabolite, was selected in this study. Results showed UA influenced on the expression rhythm of the clock genes BMAL1 and PER2 in intestinal epithelial cells. Furthermore, the study investigated the effects of UA on the expression rhythms of clock genes (BMAL1 and PER2) and tight junctions (OCLN, TJP1, and CLND1), all of which were dysregulated by inflammation. In addition, UA pre-treatment by oral administration to female C57BL/6 mice showed the improvement in the fecal IgA concentrations, tight junction expression (Clnd1 and Clnd4), and clock gene expression (Bmal1 and Per2) in a DSS-induced colitis model induced using DSS treatment. Finally, the Nrf2-SIRT1 signaling pathway was confirmed to be involved in UA's effect on the circadian rhythm of intestinal epithelial cells by antagonist treatment. This study also showed evidence that UA feeding showed an impact on the central clock, which are circadian rhythms in SCN. Therefore, this study highlighted the potential of UA in treating diseases like IBD with sleeping disorders by improving the dysregulated circadian rhythms in both the intestinal barrier and the SCN. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Intestinal dysbiosis is believed to play a role in the development of necrotizing enterocolitis (NEC). The efficacy of JNK‐inhibitory peptide (CPJIP) in treating NEC was assessed. Treatment with CPJIP led to a notable reduction in p‐JNK expression in IEC‐6 cells and NEC mice. Following LPS stimulation, the expression of RNA and protein of claudin‐1, claudin‐3, claudin‐4 and occludin was significantly decreased, with this decrease being reversed by CPJIP administration, except for claudin‐3, which remained consistent in NEC mice. Moreover, the expression levels of the inflammatory factors TNF‐α, IL‐1β and IL‐6 were markedly elevated, a phenomenon that was effectively mitigated by the addition of CPJIP in both IEC‐6 cells and NEC mice. CPJIP administration resulted in improved survival rates, ameliorated microscopic intestinal mucosal injury, and increased the total length of the intestines and colon in NEC mice. Additionally, CPJIP treatment led to a reduction in serum concentrations of FD‐4, D‐lactate and DAO. Furthermore, our results revealed that CPJIP effectively inhibited intestinal cell apoptosis and promoted cell proliferation in the intestine. This study represents the first documentation of CPJIP's ability to enhance the expression of tight junction components, suppress inflammatory responses, and rescue intestinal cell fate by inhibiting JNK activation, ultimately mitigating intestinal severity. These findings suggest that CPJIP has the potential to serve as a promising candidate for the treatment of NEC. [ABSTRACT FROM AUTHOR]