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Objective(s): Particulate matter 2.5 (PM2.5), particles with an aerodynamic diameter less than 2.5 µm, affect lung function and increase respiratory disease incidence and mortality rate. The molecular mechanism of lung injury and epithelial damage after PM2.5 exposure is not completely clear. Materials and Methods: Mouth-nose exposure of mice was performed with PM2.5 or neutral saline. In vitro experiments were conducted to investigate the role of the S100A9/AMPK pathway in PM2.5- mediated lung injury. Results: PM2.5 exposure in mice caused lung epithelial damage, alveolar wall thickening, and alveolar wall structure destruction. The 16S rRNA sequencing results suggested that the microecology structure of lung tissue was altered after PM2.5 exposure. Proteomic sequencing was performed to explore the underlying mechanism, and 71 differentially expressed proteins were identified. KEGG database analysis of the up-regulated differential proteins revealed regulatory networks, including fat digestion and absorption, the AMPK signaling pathway, and the PPAR signaling pathway. Moreover, PM2.5 exposure in mice increased the level of S100A9 and ROS, leading to reduction of the ATP level. To achieve a sufficient energy supply by increasing fatty acid transfer and oxidation, activated AMPK up-regulates CD36 and CPT1, which leads to mitochondrial damage of PM2.5-exposed cells and injury or death of lung epithelial cells. siRNA-S100A9 and AMPK inhibitors significantly reduced the occurrence of cell damage. Conclusion: These results may help to clarify biomarkers and specific mechanisms of lung tissue injury induced by PM2.5 exposure. [ABSTRACT FROM AUTHOR]

The mortality rate of ovarian cancer (OC) remains the highest among female gynecological malignancies. Advanced age is the highest risk factor for OC development and progression, yet little is known about the role of the aged tumor microenvironment (TME). We conducted RNA sequencing and lipidomic analysis of young and aged gonadal adipose tissue from rat xenografts before and after OC formation. The rates of tumor formation (p = 0.047) and tumor volume (p = 0.002) were significantly higher in the aged rats than in their young counterparts. RNA sequencing data showed significant differences in gene expression profiles between the groups of young and aged rat adipose tissues (p < 0.05), including S100a8, S100a9, Il1rl1, Lcn2, C3, Hba-a1, Fcna, and Pnpla3. At the time of tumor generation, there were also changes in the lipid components within the gonadal adipose tissues of young and aged rats, with higher levels of free fatty acids (FFAs) and triglycerides (TGs) in aged rats. Furthermore, the aged TME showed changes in immune cell composition, especially inflammation-related cells, including neutrophils, myeloid dendritic cells, CD4+ T cells (non-regulatory), and mast cell activation (p < 0.05). The correlation between S100a8, S100a9, neutrophil, and omega-5, FFA 18:3 levels was also determined. Additionally, omega-5, which is downregulated in aged rats, inhibited OC cell proliferation in vitro (p < 0.001). Our study suggests that the aged TME promotes OC proliferation resulting from age-related changes in gene/pathway expression, lipid metabolism, and immune cell distribution. Targeting the aging adipose microenvironment, particularly lipid metabolism, is a promising therapeutic strategy for OC and warrants further investigation. Significance: The aging microenvironment contributes to OC development and progression because of changes in the immune response regulatory genes S100a8 and S100a9, secreted by adipocytes, preadipocytes, or neutrophils, and by altering omega-5 metabolism. [ABSTRACT FROM AUTHOR]

Abstract Background S100A8/A9, an innate immune protein, significantly regulates inflammatory processes and immune responses. While S100A8/A9 has been linked to various diseases, its association with head and neck squamous cell carcinoma (HNSCC) remains unclear. Methods Samples from the Cancer Genome Atlas (TCGA) were categorized into groups with low and high expression of S100A8/A9. R software, Sangerbox, UALCAN, GEPIA2, STRING, Cytoscape, TCGC Data Portal, miRcode, OncomiR and ENCORI databases were used to comprehensively study the expression, interactome and mutational profiles of S100A8/A9 and associated mechanism in HNSCC. Results The proteins S100A8/A9 were found to be associated with processes of ‘epithelium development’, ‘regulating pluripotency of stem cells’ and ‘regulation of immune system’. The most frequent mutation observed in the S100A8 protein was E93K (3/37, MU4401889), while for the S100A9 protein, it was R10C (4/37, MU4633862). Furthermore, the group expressing high levels of S100A8/A9 showed increased infiltration by dendritic cells and neutrophils, but decreased infiltration by M2 macrophages, compared to the group with low S100A8/A9 expression. S100A8/A9 was also found to interact with a variety of mRNA transcripts, several of which were involved in initiation and progression of HNSCC. Through LASSO-Cox method, 20 genes (CALML5, MSX1, FZD3, STC2, SLC2A3, TMEM198B, DYNC1I1, SPHK2, ALMS1.IT1, SPPL2B, PDGFA, BCORL1, TEX101, SGCE, DNAJC12, RRN3P1, HOXB9, TMEM150C, METTL7B and PSPN) were screening to construct a prognostic model to distinguish favorable and poor prognosis of HNSCC patients. Besides, our prognostic model was also validated in GSE41613 cohort. Conclusions S100A8/A9 may be a promising marker for the diagnostic and prognostic assessment of the HNSCC patients. Based on these insights, we have devised a new classification model for HNSCC, which has the potential to enhance the management and personalized treatment of HNSCC patients. The model should also be further optimized through the expansion of sample size and implemented experimental studies in future research.

Metastatic cancer is still one of the leading causes of death worldwide despite significant advancements in diagnosis and treatment. Biomarkers are one of the most promising diagnostic tools that are used alongside traditional diagnostic tools in cancer patients. DAMPs are intracellular molecules released in response to cellular stress, tissue injury, and cell death. There have been shown to be associated with worsening prognosis among such patients, and some DAMPs could potentially be used as predictive biomarkers of metastatic status. The goal of this study is to investigate DAMP expression and the probability that certain DAMPs could be predictive biomarkers of the metastatic stage in various cancer types. Forty cancer patients at Naresuan University Hospital, Thailand, were enrolled. Then, an investigation of HSP90, HMGB1, S100A9, and ATP expression and cytokine/chemokine profiling in serum was performed using an immunological-based assay. We assessed the predictive biomarker candidates and the association between DAMP expression and cytokines/chemokines using an ROC curve analysis and a correlation regression analysis. The results showed that HSP90 has strong potential as a metastatic predictive biomarker, with a cutoff value of 25.46 ng/mL (AUC 0.8207, sensitivity 82.61%, specificity 75.00%, 95% CI 0.6860–0.9553). This was followed by HMGB1 and S100A9, which exhibited sensitivity of 82.61 and 65.22%, and specificity of 68.75 and 56.25%, respectively. Interestingly, the candidate DAMPs negatively correlate with various serum cytokines, for example, HMGB1 vs. IL-15 (slope 88.05, R 0.3297, p-value 0.005), HMGB1 vs. IFN-γ (slope 2.235, R 0.3052, p-value 0.0013) and HSP90 vs. IFN-γ (slope 0.0614, R 0.2187, p-value 0.008), suggesting that they are highly elevated in advanced metastatic tumors, which is possibly associated with the immunomodulation effect. We postulated that HSP90, HMGB1, and S100A9 have the potential to be predictive biomarkers for supporting tumor metastasis categorization using histopathology. [ABSTRACT FROM AUTHOR]

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S100A9 is an important alarmin in vivo, which plays a role in regulating inflammation and tumorigenesis. Recently, many studies have also explored the biological function and related mechanism of S100A9 in renal diseases, including acute kidney injury, chronic kidney disease, renal stone, renal transplantation, renal tumor, renal cyst, and urinary infection. They pointed out the potential role of S100A9 as a new diagnostic and therapeutic biomarker for renal diseases. In the current study, we conduct a review of these findings and summarize possible future study directions, which aims to help people understand the impact of S100A9 on renal diseases. [ABSTRACT FROM AUTHOR]

Background: Studies indicated that diverse cellular mechanisms including epithelial migration and hyper-proliferation, inflammatory responses, and enzymatic bone erosion were involved in the pathogenesis of cholesteatoma. S100A8 and S100A9, which are Ca2+-binding proteins belonging to the S100 family, can trigger the signaling pathways involved in the inflammatory processes, and a variety of cellular processes includes cell cycle progression, proliferation, and cell migration. However, the role of S100A8 and S100A9 and their associated inflammation and other signaling pathways in cholesteatoma have not been investigated yet. This study aimed to investigate the role of S100A8 and S100A9 in external auditory canal cholesteatoma and their potential pathological mechanisms. Methods: The study conducted histological staining, immunostaining, PCR, and Western blot to investigate the expression of S100A8/A9 and its related pathways in clinic EACC and the murine model of EACC. Results: Our data showed that there were increased mRNA and protein levels of S100A8 and S100A9 in clinical and animal models of EACC and the S100A8/A9 heterodimer protein was increased in the EACC model. Our study further demonstrated that the increased S100A8 and S100A9 were associated with apoptosis as well as inflammatory (TGF-β, IFN-γ, and IL-10) and angiogenetic (VEGF, HGF/SF, and c-Met) molecular pathways. The correlation analysis indicated that S100A8 and S100A9 were correlated with clinic staging, apoptosis, and inflammatory and angiogenetic factors. Conclusion: This study provided novel insight into the role of S100A8 and S100A9 associated with pathological mechanisms of EACC. [ABSTRACT FROM AUTHOR]

Background: S100A8/A9, an innate immune protein, significantly regulates inflammatory processes and immune responses. While S100A8/A9 has been linked to various diseases, its association with head and neck squamous cell carcinoma (HNSCC) remains unclear. Methods: Samples from the Cancer Genome Atlas (TCGA) were categorized into groups with low and high expression of S100A8/A9. R software, Sangerbox, UALCAN, GEPIA2, STRING, Cytoscape, TCGC Data Portal, miRcode, OncomiR and ENCORI databases were used to comprehensively study the expression, interactome and mutational profiles of S100A8/A9 and associated mechanism in HNSCC. Results: The proteins S100A8/A9 were found to be associated with processes of 'epithelium development', 'regulating pluripotency of stem cells' and 'regulation of immune system'. The most frequent mutation observed in the S100A8 protein was E93K (3/37, MU4401889), while for the S100A9 protein, it was R10C (4/37, MU4633862). Furthermore, the group expressing high levels of S100A8/A9 showed increased infiltration by dendritic cells and neutrophils, but decreased infiltration by M2 macrophages, compared to the group with low S100A8/A9 expression. S100A8/A9 was also found to interact with a variety of mRNA transcripts, several of which were involved in initiation and progression of HNSCC. Through LASSO-Cox method, 20 genes (CALML5, MSX1, FZD3, STC2, SLC2A3, TMEM198B, DYNC1I1, SPHK2, ALMS1.IT1, SPPL2B, PDGFA, BCORL1, TEX101, SGCE, DNAJC12, RRN3P1, HOXB9, TMEM150C, METTL7B and PSPN) were screening to construct a prognostic model to distinguish favorable and poor prognosis of HNSCC patients. Besides, our prognostic model was also validated in GSE41613 cohort. Conclusions: S100A8/A9 may be a promising marker for the diagnostic and prognostic assessment of the HNSCC patients. Based on these insights, we have devised a new classification model for HNSCC, which has the potential to enhance the management and personalized treatment of HNSCC patients. The model should also be further optimized through the expansion of sample size and implemented experimental studies in future research. [ABSTRACT FROM AUTHOR]

Background: Manual therapy (MT) has been widely used in China to treat local tissue inflammation for a long time. However, there is a lack of scientific evidence for using MT in anti‐inflammatory therapy, and its anti‐inflammatory mechanism needs further clarification. Methods: We utilized MT to treat cardiotoxin (CTX) injury‐induced skeletal muscle inflammation in C57BL6/J mice. We analyzed the underlying mechanism by integrating single‐cell RNA sequencing (scRNA‐seq) with molecular techniques. Hematoxylin and eosin (H&E) and immunohistochemical (IHC) staining were used to assess skeletal muscle inflammation and muscle fiber cross‐sectional area (CSA). scRNA‐seq, immunofluorescence, and western blot were performed to determine cellular and molecular outcome changes. Results: Compared with CTX injury‐induced skeletal muscle inflammatory mice, MT intervention significantly reduced proinflammatory cytokines interleukin (IL)‐1β, IL‐6, and tumor necrosis factor alpha (TNF‐α) expression levels; scRNA‐seq detected that neutrophil numbers and activity were maximum proportions increased in injured skeletal muscle among macrophage, T cells, B cells, endothelial cells, fast muscle cells, fibroblasts, and skeletal muscle satellite cells; and S100A9 gene expression was supreme in neutrophils. However, after treatment with MT, S100A9 protein expression and the numbers and activity of Ly6g+/Mpo+ neutrophils were significantly inhibited, thus reducing the inflammatory cytokine levels and exerting an anti‐inflammatory effect by early clearing neutrophils. Conclusion: MT can mitigate localized inflammation induced by injured skeletal muscle, achieved by decreasing S100A9 protein expression and clearing neutrophils in mice, which may help advance therapeutic strategies for skeletal muscle localized inflammation. [ABSTRACT FROM AUTHOR]

Simple Summary: This study investigated S100A8's immunological role in acute intestinal inflammation in rats. The rats that developed colitis after regularly drinking 3% dextran sulfate sodium (DSS), and those that were administered rat recombinant S100A8 (rr-S100A8) in addition to DSS were named the DSS + A8 group. The histological severity scores were lower in the DSS + A8 group compared to the DSS group. TNF-α production in the colon tissues was significantly suppressed in the DSS + A8 group. In vitro experiments showed that rr-S100A8 increased intracellular S100A8 mRNA levels in macrophages. The mRNA level of TNF-α significantly increased in macrophages treated with lipopolysaccharide and the anti-rat S100A8 antibody. S100A8 appeared to function as an anti-inflammatory protein by negatively regulating S100A9 and TNF-α production in macrophages. S100A8 is a protein that is abundant in neutrophils and macrophages (MΦ), but its role in inflammation remains unclear. This study aimed to assess the immunological role(s) of S100A8 in acute intestinal inflammation in rats and its role in MΦ. Rat recombinant S100A8 (rr-S100A8, 1.0 mg/kg) was intraperitoneally administered daily to rats with 3% dextran sulfate sodium (DSS) (DSS + A8 group)-induced experimental acute colitis. The histological severity score (6.50 ± 0.51, p = 0.038) in the DSS + A8 group rats remained lower than that (9.75 ± 1.48) of the rats without S100A8 (DSS group) administration. The tumor necrosis factor-alpha (TNF-α) production in the colon tissues of the rats in the DSS + A8 group (4.76 ± 0.90 pg/mL/g, p = 0.042) was significantly suppressed, compared with that of the DSS group (10.45 ± 2.04 pg/mL/g). To stimulate rat peritoneal MΦ, rr-S100A8, the anti-rat S100A8 antibody, and a lipopolysaccharide (LPS) were used in the in vitro experiments. In the MΦ stimulated with rr-S100A8 for 2 h, the mRNA level of intracellular S100A8 (47.41 ± 24.44, p = 0.002) increased in an autocrine manner, whereas that of S100A9 (0.24 ± 0.43, p = 0.782) was not significant. The TNF-α mRNA level in the MΦ treated with LPS and the anti-rat S100A8 antibody significantly increased (102.26 ± 18.60, p = 0.001) compared to that with LPS alone (16.9 ± 8.56). These results indicate that S100A8 can serve as an anti-inflammatory protein in acute inflammation by negatively regulating S100A9 and TNF-α production through inflammatory signaling pathways in MΦ. [ABSTRACT FROM AUTHOR]

Background: Calgranulin B (S100A9) was found to be strongly associated with milk protein percentage in dairy cattle in our previous genome-wide association study. Methods: SNPs in S100A9 were identified via pooled sequencing, and genotyping of 1054 cows was performed individually using MassArray with MALDI-TOFMS technology. Association analyses between the S100A9 SNPs and five milk production traits were conducted using SAS 9.2 software. Functional studies of S100A9 were conducted using quantitative PCR, Western blot, CCK-8, and immunofluorescence assays. Results: In the present study, we further verified that two SNPs in S100A9, g.17115387 C>A and g.17115176 C>A, were significantly associated with milk protein percentage. We found that S100A9 could affect the expressions of caseins CSN1S1, CSN2, and CSN3 in MAC-T cells by regulating the expressions of amino acid transporter genes. We investigated the effects of S100A9 on the PI3K-Akt, WNT, and mTOR pathways, which are well known to play important roles in mammary gland development and milk protein synthesis. Our results suggest that S100A9 regulates the expressions of the relevant genes in these pathways, and thus potentially influences the protein synthesis in the mammary gland. Conclusions: This study demonstrates the important role of the S100A9 gene in the milk protein trait of dairy cattle and provides new insights into the molecular mechanism of milk protein content. [ABSTRACT FROM AUTHOR]

S100A9, a multifunctional protein mainly expressed by neutrophils and monocytes, poses an immunological paradox. In virus infections or sterile inflammation, it functions as an alarmin attracting innate immune cells, as well as mediating proinflammatory effects through TLR4 signaling. However, in cancer, S100A9 levels have been shown to associate with poor prognosis and lack of response to immunotherapy. Its expression by myeloid cells has been related to an immune suppressive phenotype, the so-called myeloid derived suppressor cells (MDSCs). Targeting S100A9 in cancer has therefore been proposed as a potential way to relieve myeloid-mediated immune suppression. Surprisingly, we found that blocking the extracellular TLR4 signaling from S100A9 using the inhibitor Paquinimod, resulted in increased tumor growth and a detrimental effect on anti-PD-L1 efficacy in the CT26 tumor model. This effect was caused by a reduction in the tumor immune infiltration to about half of untreated controls, and the reduction was made up of a 5-fold decrease in Ly6Chigh monocytic cells. The suppressive Ly6G+ myeloid cells compartment was not reduced by Paquinimod treatment, suggesting alternative mechanisms by which S100A9 contributes to myeloid-mediated suppression. Intratumoral injection of recombinant S100A9 early after mice inoculation with CT26 cells had an anti-tumor effect. These findings indicate an important yet understudied role of S100A9 as an alarmin and immune stimulatory signal in cancer settings, and highlight the potential to exploit such signals to promote beneficial antitumor responses. [ABSTRACT FROM AUTHOR]

Regressing the accelerated degradation of skeletal muscle protein is a significant goal for cancer cachexia management. Here, we show that genetic deletion of Pgam5 ameliorates skeletal muscle atrophy in various tumor-bearing mice. pgam5 ablation represses excessive myoblast mitophagy and effectively suppresses mitochondria meltdown and muscle wastage. Next, we define BNIP3 as a mitophagy receptor constitutively associating with PGAM5. bnip3 deletion restricts body weight loss and enhances the gastrocnemius mass index in the age- and tumor size-matched experiments. The NH2-terminal region of PGAM5 binds to the PEST motif-containing region of BNIP3 to dampen the ubiquitination and degradation of BNIP3 to maintain continuous mitophagy. Finally, we identify S100A9 as a pro-cachectic chemokine via activating AGER/RAGE. AGER deficiency or S100A9 inhibition restrains skeletal muscle loss by weakening the interaction between PGAM5 and BNIP3. In conclusion, the AGER-PGAM5-BNIP3 axis is a novel but common pathway in cancer-associated muscle wasting that can be targetable. Abbreviation: AGER/RAGE: advanced glycation end-product specific receptor; BA1: bafilomycin A1; BNIP3: BCL2 interacting protein 3; BNIP3L: BCL2 interacting protein 3 like; Ckm-Cre: creatinine kinase, muscle-specific Cre; CM: conditioned medium; CON/CTRL: control; CRC: colorectal cancer; FUNDC1: FUN14 domain containing 1; MAP1LC3A/LC3A: microtubule associated protein 1 light chain 3 alpha; PGAM5: PGAM family member 5, mitochondrial serine/threonine protein phosphatase; S100A9: S100 calcium binding protein A9; SQSTM1/p62: sequestosome 1; TOMM20: translocase of outer mitochondrial membrane 20; TIMM23: translocase of inner mitochondrial membrane 23; TSKO: tissue-specific knockout; VDAC1: voltage dependent anion channel 1. [ABSTRACT FROM AUTHOR]

Abstract The calcium-binding protein S100A9 has emerged as a pivotal biomolecular actor in oncology, implicated in numerous malignancies. This comprehensive bioinformatics study transcends traditional boundaries, investigating the prognostic and therapeutic potential of S100A9 across diverse neoplastic entities. Leveraging a wide array of bioinformatics tools and publicly available cancer genomics databases, such as TCGA, we systematically examined the S100A9 gene. Our approach included differential expression analysis, mutational burden assessment, protein interaction networks, and survival analysis. This robust computational framework provided a high-resolution view of S100A9’s role in cancer biology. The study meticulously explored S100A9’s oncogenic facets, incorporating comprehensive analyses of its relationship with prognosis, tumor mutational burden (TMB), microsatellite instability (MSI), DNA methylation, and immune cell infiltration across various tumor types. This study presents a panoramic view of S100A9 expression across a spectrum of human cancers, revealing a heterogeneous expression landscape. Elevated S100A9 expression was detected in malignancies such as BLCA (Bladder Urothelial Carcinoma), CESC (Cervical squamous cell carcinoma and endocervical adenocarcinoma), COAD (Colon adenocarcinoma), ESCA (Esophageal carcinoma), and GBM (Glioblastoma multiforme), while reduced expression was noted in BRCA (Breast invasive carcinoma), HNSC (Head and Neck squamous cell carcinoma), and KICH (Kidney Chromophobe). This disparate expression pattern suggests that S100A9’s role in cancer biology is multifaceted and context-dependent. Prognostically, S100A9 expression correlates variably with patient outcomes across different cancer types. Furthermore, its expression is intricately associated with TMB and MSI in nine cancer types. Detailed examination of six selected tumors—BRCA, CESC, KIRC (Kidney renal clear cell carcinoma), LUSC (Lung squamous cell carcinoma), SKCM (Skin Cutaneous Melanoma); STAD (Stomach adenocarcinoma)—revealed a negative correlation of S100A9 expression with the infiltration of most immune cells, but a positive correlation with neutrophils, M1 macrophages, and activated NK cells, highlighting the complex interplay between S100A9 and the tumor immune environment. This bioinformatics synthesis posits S100A9 as a significant player in cancer progression, offering valuable prognostic insights. The data underscore the utility of S100A9 as a prognostic biomarker and its potential as a therapeutic target. The therapeutic implications are profound, suggesting that modulation of S100A9 activity could significantly impact cancer management strategies.

Hui Pei,1 Jie Qu,1 Jianming Chen,1 Guangju Zhao,1 ZhongQiu Lu1,2 1Emergency Department, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, People’s Republic of China; 2Wenzhou Key Laboratory of Emergency and Disaster Medicine, Wenzhou, People’s Republic of ChinaCorrespondence: ZhongQiu Lu, Email lzq_640815@163.comPurpose: Sepsis-induced cardiomyopathy (SICM) is a prevalent cardiac dysfunction caused by sepsis. Mitochondrial dysfunction is a crucial pathogenic factor associated with adverse cardiovascular adverse events; however, research on SICM remains insufficient.Methods: To investigate the factors contributing to the pathological progression of SICM, we performed a comprehensive analysis of transcriptomic data from the GEO database using bioinformatics and machine learning techniques. CRISPR-Cas9 S100A9 knockout mice and primary cardiomyocytes were exposed to lipopolysaccharide to simulate SICM. Transcriptome analysis and mass spectrometry of primary cardiomyocytes were used to determine the potential pathogenic mechanisms of S100A9. The mitochondrial ultrastructure and mitochondrial membrane potential (MMP) were detected using transmission electron microscopy and flow cytometry, respectively. Pink1/Parkin and Drp1 proteins were detected using Western blotting to evaluate mitochondrial autophagy and division. The mtDNA and mRNA levels of mitochondrial transcription factors and synthases were evaluated using real-time polymerase chain reaction.Results: Bioinformatics analysis identified 12 common differentially expressed genes, including SERPINA3N, LCN2, MS4A6D, LRG1, OSMR, SOCS3, FCGR2b, S100A9, S100A8, CASP4, ABCA8A, and NFKBIZ. Significant S100A9 upregulation was closely associated with myocardial injury exacerbation and cardiac function deterioration. GSEA revealed that myocardial contractile function, oxidative stress, and mitochondrial function were significantly affected by S100A9. Knocking out S100A9 alleviates the inflammatory response and mitochondrial dysfunction. The interaction of S100A9 with ATP5 enhanced mitochondrial division and autophagy, inhibited MMP and ATP synthesis, and induced oxidative stress, which are related to the Nlrp3-Nfkb-Caspase1 and Drp1-Pink1-Parkin signaling pathways. The expression of mitochondrial transcription factors (TFAM and TFBM) and ATP synthetases (ATP6 and ATP8, as well as COX1, COX2, and COX3) was further suppressed by S100A9 in SICM. Targeted S100A9 inhibition by paquinimod partially reversed myocardial mitochondrial dysfunction and oxidative stress.Conclusion: The interaction of S100A9 with ATP5 exacerbates myocardial damage in sepsis by inducing mitochondrial dysfunction and oxidative stress. Keywords: S100A9, SICM, bioinformatics analysis, mitochondrial dysfunction, ATP5

Chronic non-healing wounds are characterized by persistent inflammation, excessive matrix-degrading proteolytic activity and compromised extracellular matrix (ECM) synthesis. Previous studies showed that S100A8/A9 are strongly dysregulated in delayed wound healing and impair the proper function of immune cells. Here, we demonstrate an unrecognized pathological function of S100A9 overexpression in wounds with impaired healing that directly affects ECM functions in fibroblasts. S100A9 was analyzed in two different mouse models mimicking the features of the two most prominent types of non-healing wounds in humans. Db/db mice were used as a model for diabetes-associated impaired wound healing. Iron-overloaded mice were used to mimic the conditions of impaired wound healing in chronic venous leg ulcers. The skin wounds of both mouse models are characterized by delayed wound closure, high and sustained expression of pro-inflammatory mediators and a substantially decreased ECM deposition, all together the hallmarks of non-healing wounds in humans. The wounds of both mouse models also present a solid and prolonged expression of S100A8 and S100A9 that coincides with a compromised ECM deposition and that was confirmed in chronic wounds in humans. Mechanistically, we reveal that S100A9 directly affects ECM deposition by shifting the balance of expression of ECM proteins and ECM degrading enzymes in fibroblasts via toll-like-receptor 4-dependent signaling. Consequently, blocking S100A9 during delayed wound healing in db/db mice restores fibroblast ECM functions eliciting increased matrix deposition. Our data indicate that the dysregulation of S100A9 directly contributes to a compromised ECM deposition in chronic wounds and further suggests S100A9 as a promising therapeutic target to improve tissue repair in chronic wounds. [ABSTRACT FROM AUTHOR]

Atomic force microscopy (AFM) imaging enables the visualization of protein molecules with high resolution, providing insights into their shape, size, and surface topography. Here, we use AFM to study the aggregation process of protein S100A9 in physiological conditions, in the presence of calcium at a molar ratio 4Ca2+:S100A9. We find that S100A9 readily assembles into a worm-like fibril, with a period dimension along the fibril axis of 11.5 nm. The fibril's chain length extends up to 136 periods after an incubation time of 144 h. At room temperature, the fibril's bending stiffness was found to be 2.95 × 10 − 28 Nm2, indicating that the fibrils are relatively flexible. Additionally, the values obtained for the Young's modulus ( E x = 6.96 × 10 5 Pa and E y = 3.37 × 10 5 Pa) are four orders of magnitude lower than those typically reported for canonical amyloid fibrils. Our findings suggest that, under the investigated conditions, a distinct aggregation mechanism may be in place in the presence of calcium. Therefore, the findings reported here could have implications for the field of biomedicine, particularly with regard to Alzheimer's disease. [ABSTRACT FROM AUTHOR]

Colorectal cancer (CRC) is a frequent, worldwide tumor described for its huge complexity, including inter-/intra-heterogeneity and tumor microenvironment (TME) variability. Intra-tumor heterogeneity and its connections with metabolic reprogramming and epithelial–mesenchymal transition (EMT) were investigated with explorative shotgun proteomics complemented by a Random Forest (RF) machine-learning approach. Deep and superficial tumor regions and distant-site non-tumor samples from the same patients (n = 16) were analyzed. Among the 2009 proteins analyzed, 91 proteins, including 23 novel potential CRC hallmarks, showed significant quantitative changes. In addition, a 98.4% accurate classification of the three analyzed tissues was obtained by RF using a set of 21 proteins. Subunit E1 of 2-oxoglutarate dehydrogenase (OGDH-E1) was the best classifying factor for the superficial tumor region, while sorting nexin-18 and coatomer-beta protein (beta-COP), implicated in protein trafficking, classified the deep region. Down- and up-regulations of metabolic checkpoints involved different proteins in superficial and deep tumors. Analogously to immune checkpoints affecting the TME, cytoskeleton and extracellular matrix (ECM) dynamics were crucial for EMT. Galectin-3, basigin, S100A9, and fibronectin involved in TME–CRC–ECM crosstalk were found to be differently variated in both tumor regions. Different metabolic strategies appeared to be adopted by the two CRC regions to uncouple the Krebs cycle and cytosolic glucose metabolism, promote lipogenesis, promote amino acid synthesis, down-regulate bioenergetics in mitochondria, and up-regulate oxidative stress. Finally, correlations with the Dukes stage and budding supported the finding of novel potential CRC hallmarks and therapeutic targets. [ABSTRACT FROM AUTHOR]

The calcium-binding protein S100A9 has emerged as a pivotal biomolecular actor in oncology, implicated in numerous malignancies. This comprehensive bioinformatics study transcends traditional boundaries, investigating the prognostic and therapeutic potential of S100A9 across diverse neoplastic entities. Leveraging a wide array of bioinformatics tools and publicly available cancer genomics databases, such as TCGA, we systematically examined the S100A9 gene. Our approach included differential expression analysis, mutational burden assessment, protein interaction networks, and survival analysis. This robust computational framework provided a high-resolution view of S100A9's role in cancer biology. The study meticulously explored S100A9's oncogenic facets, incorporating comprehensive analyses of its relationship with prognosis, tumor mutational burden (TMB), microsatellite instability (MSI), DNA methylation, and immune cell infiltration across various tumor types. This study presents a panoramic view of S100A9 expression across a spectrum of human cancers, revealing a heterogeneous expression landscape. Elevated S100A9 expression was detected in malignancies such as BLCA (Bladder Urothelial Carcinoma), CESC (Cervical squamous cell carcinoma and endocervical adenocarcinoma), COAD (Colon adenocarcinoma), ESCA (Esophageal carcinoma), and GBM (Glioblastoma multiforme), while reduced expression was noted in BRCA (Breast invasive carcinoma), HNSC (Head and Neck squamous cell carcinoma), and KICH (Kidney Chromophobe). This disparate expression pattern suggests that S100A9's role in cancer biology is multifaceted and context-dependent. Prognostically, S100A9 expression correlates variably with patient outcomes across different cancer types. Furthermore, its expression is intricately associated with TMB and MSI in nine cancer types. Detailed examination of six selected tumors—BRCA, CESC, KIRC (Kidney renal clear cell carcinoma), LUSC (Lung squamous cell carcinoma), SKCM (Skin Cutaneous Melanoma); STAD (Stomach adenocarcinoma)—revealed a negative correlation of S100A9 expression with the infiltration of most immune cells, but a positive correlation with neutrophils, M1 macrophages, and activated NK cells, highlighting the complex interplay between S100A9 and the tumor immune environment. This bioinformatics synthesis posits S100A9 as a significant player in cancer progression, offering valuable prognostic insights. The data underscore the utility of S100A9 as a prognostic biomarker and its potential as a therapeutic target. The therapeutic implications are profound, suggesting that modulation of S100A9 activity could significantly impact cancer management strategies. [ABSTRACT FROM AUTHOR]

Glioblastoma (GBM) is a highly heterogeneous disease with poor clinical outcomes. To comprehensively dissect the molecular landscape of GBM and heterogeneous macrophage clusters in the progression of GBM, this study integrates single-cell and bulk transcriptome data to recognize a distinct pro-tumor macrophage cluster significantly associated with the prognosis of GBM and develop a GBM prognostic signature to facilitate prior subtypes. Leveraging glioma single-cell sequencing data, we identified a novel pro-tumor macrophage subgroup, marked by S100A9, which might interact with endothelial cells to facilitate tumor progression via angiogenesis. To further benefit clinical application, a prognostic signature was established with the genes associated with pro-tumor macrophages. Patients classified within the high-risk group characterized with enrichment in functions related to tumor progression, including epithelial-mesenchymal transition and hypoxia, displays elevated mutations in the TERT promoter region, reduced methylation in the MGMT promoter region, poorer prognoses, and diminished responses to temozolomide therapy, thus effectively discriminating between the prognostic outcomes of GBM patients. Our research sheds light on the intricate microenvironment of gliomas and identifies potential molecular targets for the development of novel therapeutic approaches. [ABSTRACT FROM AUTHOR]

Background: Microglia and infiltrated macrophages (M/M) are integral components of the innate immune system that play a critical role in facilitating brain repair after ischemic stroke (IS) by clearing cell debris. Novel therapeutic strategies for IS therapy involve modulating M/M phenotype shifting. This study aims to elucidate the pivotal role of S100A9 in M/M and its downstream STAT6/PPARγ signaling pathway in neuroinflammation and phagocytosis after IS. Methods: In the clinical study, we initially detected the expression pattern of S100A9 in monocytes from patients with acute IS and investigated its association with the long‐term prognosis. In the in vivo study, we generated the S100A9 conditional knockout (CKO) mice and compared the stroke outcomes with the control group. We further tested the S100A9‐specific inhibitor paqunimod (PQD), for its pharmaceutical effects on stroke outcomes. Transcriptomics and in vitro studies were adopted to explore the mechanism of S100A9 in modulating the M/M phenotype, which involves the regulation of the STAT6/PPARγ signaling pathway. Results: S100A9 was predominantly expressed in classical monocytes and was correlated with unfavorable outcomes in patients of IS. S100A9 CKO mitigated infarction volume and white matter injury, enhanced cerebral blood flow and functional recovery, and prompted anti‐inflammation phenotype and efferocytosis after tMCAO. The STAT6/PPARγ pathway, an essential signaling cascade involved in immune response and inflammation, might be the downstream target mediated by S100A9 deletion, as evidenced by the STAT6 phosphorylation inhibitor AS1517499 abolishing the beneficial effect of S100A9 inhibition in tMCAO mice and cell lines. Moreover, S100A9 inhibition by PQD treatment protected against neuronal death in vitro and brain injuries in vivo. Conclusion: This study provides evidence for the first time that S100A9 in classical monocytes could potentially be a biomarker for predicting IS prognosis and reveals a novel therapeutic strategy for IS. By demonstrating that S100A9‐mediated M/M polarization and phagocytosis can be reversed by S100A9 inhibition in a STAT6/PPARγ pathway‐dependent manner, this study opens up new avenues for drug development in the field. [ABSTRACT FROM AUTHOR]

Immune response is pivotal in the secondary injury of spinal cord injury (SCI). Polarization of macrophages (MΦ) influences the immune response in the secondary injury, which is regulated by several immune-related proteins. M2Φ plays the immunomodulatory role in the central nervous system. This study used bioinformatic analysis and machine algorithms to screen hub immune-related proteins after SCI and experimentally investigate the role of the target protein in the M2Φ polarization and immunomodulation in rats and in vitro after SCI. We downloaded GSE151371 and GSE45006, hub immune-related genes were screened using machine learning algorithms, and the expression of S100A9 was verified by datasets. Allen's weight-drop injury SCI model in Sprague–Dawley rat and bone marrow-derived rat MΦ with myelin debris model were used to study the effects of S100A9 on M2Φ polarization and immunomodulation at the lesion site and in vitro. Bioinformatic analysis showed that S100A9 acts as a hub immune-related gene in the SCI patients and rats. S100A9 increased at the lesion site in SCI rats, and its inhibition reduced CD206 and ARG-1 expression. Exogenous S100A9 promoted CD206 and ARG-1 expression in MΦ. S100A9 also increased the expression of PD-L1 and decreased MHC II at the lesion site in SCI rats and MΦ with myelin debris, and enhanced mitochondrial activity in rat MΦ with myelin debris. In conclusion, S100A9 is an indispensable factor in the immune process in secondary injury following SCI. [ABSTRACT FROM AUTHOR]

Simple Summary: Mycoplasma capricolum subsp. capricolum (Mcc) is an important pathogen associated with diseases in goats, hindering the development of the livestock industry. We previously isolated the HN-B strain of Mcc from goats on Hainan Island, China. The genomic and biological characteristics of this strain were investigated. In this study, we infected mice and RAW264.7 cells with Mcc HN-B to explore its pathogenic mechanism in the host. Differentially expressed genes related to immune terms and pathways were identified using bioinformatic analyses. The expression of two inflammatory proteins, S100A8 and S100A9, was up-regulated in mouse lungs post Mcc HN-B infection. This study preliminarily elucidates the pathogenesis of Mcc in mice and paves the way for further research in goats. Mycoplasma capricolum subsp. capricolum (Mcc), a member of the Mycoplasma mycoides cluster, has a negative impact on the goat-breeding industry. However, little is known about the pathogenic mechanism of Mcc. This study infected mice using a previously isolated strain, Mcc HN-B. Hematoxylin and eosin staining, RNA sequencing, bioinformatic analyses, RT-qPCR, and immunohistochemistry were performed on mouse lung tissues. The results showed that 235 differentially expressed genes (DEGs) were identified. GO and KEGG enrichment analyses suggested that the DEGs were mainly associated with immune response, defensive response to bacteria, NF-kappa B signaling pathway, natural killer cell-mediated cytotoxicity, and T cell receptor signaling pathway. RT-qPCR verified the expression of Ccl5, Cd4, Cd28, Il2rb, Lck, Lat, Ptgs2, S100a8, S100a9, and Il-33. The up-regulation of S100A8 and S100A9 at the protein level was confirmed by immunohistochemistry. Moreover, RT-qPCR assays on Mcc HN-B-infected RAW264.7 cells also showed that the expression of S100a8 and S100a9 was elevated. S100A8 and S100A9 not only have diagnostic value in Mcc infection but also hold great significance in clarifying the pathogenic mechanism of Mcc. This study preliminarily elucidates the mechanism of Mcc HN-B-induced lung injury and provides a theoretical basis for further research on Mcc–host interactions. [ABSTRACT FROM AUTHOR]

Background: Estrogen receptor (ER) positive human epidermal growth factor receptor 2 (HER2) negative breast cancer (ER+/HER2−BC) and triple-negative breast cancer (TNBC) are two distinct breast cancer molecular subtypes, especially in tumor immune microenvironment (TIME). The TIME of TNBC is considered to be more inflammatory than that of ER+/HER2−BC. Natural killer (NK) cells are innate lymphocytes that play an important role of tumor eradication in TME. However, studies focusing on the different cell states of NK cells in breast cancer subtypes are still inadequate. Methods: In this study, single-cell mRNA sequencing (scRNA-seq) and bulk mRNA sequencing data from ER+/HER2−BC and TNBC were analyzed. Key regulator of NK cell suppression in ER+/HER2−BC, S100A9, was quantified by qPCR and ELISA in MCF-7, T47D, MDA-MB-468 and MDA-MB-231 cell lines. The prognosis predictability of S100A9 and NK activation markers was evaluated by Kaplan–Meier analyses using TCGA-BRAC data. The phenotype changes of NK cells in ER+/HER2−BC after overexpressing S100A9 in cancer cells were evaluated by the production levels of IFN-gamma, perforin and granzyme B and cytotoxicity assay. Results: By analyzing scRNA-seq data, we found that multiple genes involved in cellular stress response were upregulated in ER+/HER2−BC compared with TNBC. Moreover, TLR regulation pathway was significantly enriched using differentially expressed genes (DEGs) from comparing the transcriptome data of ER+/HER2−BC and TNBC cancer cells, and NK cell infiltration high/low groups. Among the DEGs, S100A9 was identified as a key regulator. Patients with higher expression levels of S100A9 and NK cell activation markers had better overall survival. Furthermore, we proved that overexpression of S100A9 in ER+/HER2-cells could improve cocultured NK cell function. Conclusion: In conclusion, the study we presented demonstrated that NK cells in ER+/HER2−BC were hypofunctional, and S100A9 was an important regulator of NK cell function in ER+BC. Our work contributes to elucidate the regulatory networks between cancer cells and NK cells and may provide theoretical basis for novel drug development. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) leads to progressive neurodegeneration and dementia. AD primarily affects older adults with neuropathological changes including amyloid-beta (Aβ) deposition, neuroinflammation, and neurodegeneration. We have previously demonstrated that systemic treatment with combined stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF) (SCF+G-CSF) reduces the Aβ load, increases Aβ uptake by activated microglia and macrophages, reduces neuroinflammation, and restores dendrites and synapses in the brains of aged APPswe/PS1dE9 (APP/PS1) mice. However, the mechanisms underlying SCF+G-CSF-enhanced brain repair in aged APP/PS1 mice remain unclear. This study used a transcriptomic approach to identify the potential mechanisms by which SCF+G-CSF treatment modulates microglia and peripheral myeloid cells to mitigate AD pathology in the aged brain. After injections of SCF+G-CSF for 5 consecutive days, single-cell RNA sequencing was performed on CD11b+ cells isolated from the brains of 28-month-old APP/PS1 mice. The vast majority of cell clusters aligned with transcriptional profiles of microglia in various activation states. However, SCF+G-CSF treatment dramatically increased a cell population showing upregulation of marker genes related to peripheral myeloid cells. Flow cytometry data also revealed an SCF+G-CSF-induced increase of cerebral CD45high/CD11b+ active phagocytes. SCF+G-CSF treatment robustly increased the transcription of genes implicated in immune cell activation, including gene sets that regulate inflammatory processes and cell migration. The expression of S100a8 and S100a9 was robustly enhanced following SCF+G-CSF treatment in all CD11b+ cell clusters. Moreover, the topmost genes differentially expressed with SCF+G-CSF treatment were largely upregulated in S100a8/9-positive cells, suggesting a well-conserved transcriptional profile related to SCF+G-CSF treatment in resident and peripherally derived CD11b+ immune cells. This S100a8/9-associated transcriptional profile contained notable genes related to pro-inflammatory and anti-inflammatory responses, neuroprotection, and Aβ plaque inhibition or clearance. Altogether, this study reveals the immunomodulatory effects of SCF+G-CSF treatment in the aged brain with AD pathology, which will guide future studies to further uncover the therapeutic mechanisms. [ABSTRACT FROM AUTHOR]

S100A8 (MRP8) and S100A9 (MRP14) are critical mediators of the inflammatory response; they are usually present as heterodimers because of the instability of homodimers. Studies have demonstrated that S100A8/A9 expression is significantly upregulated in several central nervous system (CNS) diseases. S100A8/A9 is actively released by neutrophils and monocytes; it plays a key role in regulating the inflammatory response by stimulating leukocyte recruitment and inducing cytokine secretion during inflammation. Additionally, S100A8/A9 can be used as a diagnostic biomarker for several CNS diseases and as a predictor of therapeutic response to inflammation-related diseases. In this work, we reviewed our current understanding of S100A8/A9 overexpression in inflammation and its importance in the development and progression of CNS inflammatory diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), and stroke, and the functional roles and therapeutic applications of S100A8/A9 in these diseases. Finally, we discussed the current barriers and future research directions of S100A8/A9 in CNS diseases.

BackgroundStudies indicated that diverse cellular mechanisms including epithelial migration and hyper-proliferation, inflammatory responses, and enzymatic bone erosion were involved in the pathogenesis of cholesteatoma. S100A8 and S100A9, which are Ca2+-binding proteins belonging to the S100 family, can trigger the signaling pathways involved in the inflammatory processes, and a variety of cellular processes includes cell cycle progression, proliferation, and cell migration. However, the role of S100A8 and S100A9 and their associated inflammation and other signaling pathways in cholesteatoma have not been investigated yet. This study aimed to investigate the role of S100A8 and S100A9 in external auditory canal cholesteatoma and their potential pathological mechanisms.MethodsThe study conducted histological staining, immunostaining, PCR, and Western blot to investigate the expression of S100A8/A9 and its related pathways in clinic EACC and the murine model of EACC.ResultsOur data showed that there were increased mRNA and protein levels of S100A8 and S100A9 in clinical and animal models of EACC and the S100A8/A9 heterodimer protein was increased in the EACC model. Our study further demonstrated that the increased S100A8 and S100A9 were associated with apoptosis as well as inflammatory (TGF-β, IFN-γ, and IL-10) and angiogenetic (VEGF, HGF/SF, and c-Met) molecular pathways. The correlation analysis indicated that S100A8 and S100A9 were correlated with clinic staging, apoptosis, and inflammatory and angiogenetic factors.ConclusionThis study provided novel insight into the role of S100A8 and S100A9 associated with pathological mechanisms of EACC.

Abstract Background Early in the host-response to infection, neutrophils release calprotectin, triggering several immune signalling cascades. In acute infection management, identifying infected patients and stratifying these by risk of deterioration into sepsis, are crucial tasks. Recruiting a heterogenous population of patients with suspected infections from the emergency department, early in the care-path, the CASCADE trial aimed to evaluate the accuracy of blood calprotectin for detecting bacterial infections, estimating disease severity, and predicting clinical deterioration. Methods In a prospective, observational trial from February 2021 to August 2022, 395 patients (n = 194 clinically suspected infection; n = 201 controls) were enrolled. Blood samples were collected at enrolment. The accuracy of calprotectin to identify bacterial infections, and to predict and identify sepsis and mortality was analysed. These endpoints were determined by a panel of experts. Results The Area Under the Receiver Operating Characteristic (AUROC) of calprotectin for detecting bacterial infections was 0.90. For sepsis within 72 h, calprotectin’s AUROC was 0.83. For 30-day mortality it was 0.78. In patients with diabetes, calprotectin had an AUROC of 0.94 for identifying bacterial infection. Conclusions Calprotectin showed notable accuracy for all endpoints. Using calprotectin in the emergency department could improve diagnosis and management of severe infections, in combination with current biomarkers. Clinical trial registration number DRKS00020521

The standard therapy for cardiovascular disease (CVD) is the administration of statins to reduce plasma cholesterol levels, but this requires lifelong treatment. We developed a CVD vaccine candidate that targets the pro-inflammatory mediator calprotectin by eliciting antibodies against the S100A9 protein. The vaccine, based on bacteriophage Qβ virus-like particles (VLPs) displaying S100A9 peptide epitopes, was formulated as a slow-release PLGA:VLP implant by hot-melt extrusion. The single-dose implant elicited S100A9-specific antibody titers comparable to a three-dose injection schedule with soluble VLPs. In an animal model of CVD (ApoE-/- mice fed on a high-fat diet), the implant reduced serum levels of calprotectin, IL-1β, IL-6 and MCP-1, resulting in less severe aortic lesions. This novel implant was therefore able to attenuate atherosclerosis over a sustained period and offers a novel and promising strategy to replace the repetitive administration of statins for the treatment of CVD.

Fibroblast growth factor‐2 (FGF2) is involved in the regulation of affective behaviour and shows antidepressant effects through the Akt and extracellular signal regulated kinase (ERK) 1/2 pathways. Nudix hydrolase 6 (NUDT6) protein is encoded from FGF2 gene's antisense strand and its role in the regulation of affective behaviour is unknown. Here, we overexpressed NUDT6 in the hippocampus and investigated its behavioural effects and the underlying molecular mechanisms affecting the behaviour. We showed that increasing hippocampal NUDT6 results in depression‐like behaviour in rats without changing FGF2 levels or activating its downstream effectors, Akt and ERK1/2. Instead, NUDT6 acted by inducing inflammatory signalling, specifically by increasing S100 calcium binding protein A9 (S100A9) levels, activating nuclear factor‐kappa B‐p65 (NF‐κB‐p65), and elevating microglia numbers along with a reduction in neurogenesis. Our results suggest that NUDT6 could play a role in major depression by inducing a proinflammatory state. This is the first report of an antisense protein acting through a different mechanism of action than regulation of its sense protein. The opposite effects of NUDT6 and FGF2 on depression‐like behaviour may serve as a mechanism to fine‐tune affective behaviour. Our findings open up new venues for studying the differential regulation and functional interactions of sense and antisense proteins in neural function and behaviour, as well as in neuropsychiatric disorders. Key points: Hippocampal overexpression of nudix hydrolase 6 (NUDT6), the antisense protein of fibroblast growth factor‐2 (FGF2), increases depression‐like behaviour in rats.Hippocampal NUDT6 overexpression triggers a neuroinflammatory cascade by increasing S100 calcium binding proteinA9 (S100A9) expression and nuclear NF‐κB‐p65 translocation in neurons, in addition to microglial recruitment and activation.Hippocampal NUDT6 overexpression suppresses neurogenesis.NUDT6 exerts its actions without altering the levels or downstream signalling pathways of FGF2. [ABSTRACT FROM AUTHOR]

Altered cardiac innate immunity is highly associated with the progression of cardiac disease states and heart failure. S100A8/A9 is an important component of damage-associated molecular patterns (DAMPs) that is critically involved in the pathogenesis of heart failure, thus considered a promising target for pharmacological intervention. In the current study, initially, we validated the role of S100A8/A9 in contributing to cardiac injury and heart failure via the overactivation of the β-adrenergic pathway and tested the potential use of paquinimod as a pharmacological intervention of S100A8/A9 activation in preventing cardiac dysfunction, collagen deposition, inflammation, and immune cell infiltration in β-adrenergic overactivation–mediated heart failure. This finding was further confirmed by the cardiomyocyte-specific silencing of S100A9 via the use of the adeno-associated virus (AAV) 9-mediated short hairpin RNA (shRNA) gene silencing system. Most importantly, in the assessment of the underlying cellular mechanism by which activated S100A8/A9 cause aggravated progression of cardiac fibrosis and heart failure, we discovered that the activated S100A8/A9 can promote fibroblast-macrophage interaction, independent of inflammation, which is likely a key mechanism leading to the enhanced collagen production. Our results revealed that targeting S100A9 provides dual beneficial effects, which is not only a strategy to counteract cardiac inflammation but also preclude cardiac fibroblast-macrophage interactions. The findings of this study also indicate that targeting S100A9 could be a promising strategy for addressing cardiac fibrosis, potentially leading to future drug development. [ABSTRACT FROM AUTHOR]

AIM: To investigate the underlying mechanism of dry environment (autumn dryness) affecting the lacrimal glands in rats. METHODS: Twenty Sprague-Dawley rats were randomly divided into two groups. The rats were fed in specific pathogen free environment as the control group (n=10), and the rats fed in dry environment as the dryness group (n=10). After 24d, lacrimal glands were collected from the rats. The tissues morphology was observed by hematoxylin-eosin (HE) staining. Tandem mass tags (TMT) quantitative proteomics analysis technology was used to screen the differential expressed proteins of lacrimal glands between the two groups, then bioinformatics analysis was performed. Further, the immunohistochemical (IHC) method was used to verify the target proteins. RESULTS: In dryness group, the lacrimal glands lobule atrophied, the glandular cavities enlarged, the sparse nuclear distribution and scattered inflammatory infiltration between the acinus were observed. The proteomics exhibited that a total of 195 up-regulated and 236 down-regulated differential expressed proteins screened from the lacrimal glands of rats. It was indicated that the biological processes (BP) of differential expressed proteins mainly included cell processes and single BP. The cellular compositions of differential expressed proteins mainly located in cells, organelles. The molecular functions of differential expressed proteins mainly included binding, catalytic activity. Moreover, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the differential expressed proteins mainly involved lysosome, complement and coagulation cascade, and ribosome pathway. The IHC result verified that the up-regulated expression proteins of Protein S100A9 (S100A9), Annexin A1 (Anxa1), and Clusterin (Clu) in lacrimal glands of rats in dryness group were higher than control group. CONCLUSION: The up-regulated expression proteins of S100A9, Anxa1, and Clu may be the potential mechanisms of dry eye symptoms caused by dry environment. This study provides clues of dry environments causing eye-related diseases for further studies.

Abstract Ulcerative colitis (UC) is a chronic, recurrent inflammatory bowel disease. UC confronts with severe challenges including the unclear pathogenesis and lack of specific diagnostic markers, demanding for identifying predictive biomarkers for UC diagnosis and treatment. We perform immune infiltration and weighted gene co-expression network analysis on gene expression profiles of active UC, inactive UC, and normal controls to identify UC related immune cell and hub genes. Neutrophils, M1 macrophages, activated dendritic cells, and activated mast cells are significantly enriched in active UC. MMP-9, CHI3L1, CXCL9, CXCL10, CXCR2 and S100A9 are identified as hub genes in active UC. Specifically, S100A9 is significantly overexpressed in mice with colitis. The receiver operating characteristic curve demonstrates the excellent performance of S100A9 expression in diagnosing active UC. Inhibition of S100A9 expression reduces DSS-induced colonic inflammation. These identified biomarkers associated with activity in UC patients enlighten the new insights of UC diagnosis and treatment.

Xinyi Long,1 Fangfang Li,1 Sishi Tang,1 Jing Liu,1 Yunfeng Fu,2 Yanhui Feng3 1Department of Hematology, The Third Xiangya Hospital, Central South University, Changsha, 410013, People’s Republic of China; 2Department of Blood Transfusion, The Third Xiangya Hospital of Central South University, Changsha, 410013, People’s Republic of China; 3Department of Oncology, The Third Xiangya Hospital of Central South University, Changsha, 410013, People’s Republic of ChinaCorrespondence: Yanhui Feng, Department of Oncology, The Third Xiangya Hospital, Central South University, No. 138 Tongzipo Road, Yuelu District, Hexi, Changsha, Hunan Province, People’s Republic of China, Tel +86-13549656766, Email fengyanhui900@sohu.comPurpose: Immunological regimens are an important area of research for treating multiple myeloma (MM). Plasma cells play a crucial role in immunotherapy.Patients and Methods: In our study, we used both single-cell RNA sequencing (scRNA-seq) and bulk sequencing techniques to analyze MM patients. We analyzed each sample using gene set variation analysis (GSVA) based on immune-related gene sets. We also conducted further analyses to compare immune infiltration, clinical characteristics, and expression of immune checkpoint molecules between the H-S100A9 and L-S100A9 groups of MM patients.Results: We identified eight subpopulations of plasma cells, with S100A9 plasma cells being more abundant in patients with 1q21 gain and 1q21 diploid. CellChat analysis revealed that GAS and HGF signaling pathways were prominent in intercellular communication of S100A9 plasma cells. We identified 14 immune-related genes in the S100A9 plasma cell population, which allowed us to classify patients into the H-S100A9 group or the L-S100A9 group. The H-S100A9 group showed higher ESTIMATE, immune and stroma scores, lower tumor purity, and greater immune checkpoint expression. Patients with 1q21 gain and four or more copies had the lowest ESTIMATE score, immune score, stroma score, and highest tumor purity. Drug sensitivity analysis indicated that the H-S100A9 group had lower IC50 values and greater drug sensitivity compared to the L-S100A9 group. Quantitative reverse transcription (RT-q) PCR showed significantly elevated expression of RNASE6, LYZ, S100A8, S100A9, and S100A12 in MM patients compared to the healthy control group.Conclusion: Our study has identified a correlation between molecular subtypes of S100A9 plasma cells and the response to immunotherapy in MM patients. These findings improve our understanding of tumor immunology and provide guidance for developing effective immunotherapy strategies for this patient population.Keywords: multiple myeloma, single-cell sequencing, bulk transcription, tumor immune microenvironment, S100A9

Abstract Background S100A8 and S100A9 are members of Ca2+-binding EF-hand superfamily, mainly expressed by macrophages and neutrophils. Limited by the poor stability of homodimers, they commonly exist as heterodimers. Beyond acting as antibacterial cytokines, S100A8/A9 is also associated with metabolic and autoimmune diseases such as obesity, diabetes, and rheumatoid arthritis. While the involvement of S100A8/A9 in breast cancer development has been documented, its prognostic significance and the precise regulatory mechanisms remain unclear. Methods S100A8/A9 protein in breast cancer samples was evaluated by immunohistochemistry staining with tumor tissue microarrays. The serum S100A8 concentration in patients was measured by enzyme-linked immunosorbent assay (ELISA). The S100A8 secreted by breast cancer cells was detected by ELISA as well. Pooled analyses were conducted to explore the relationships between S100A8/A9 mRNA level and clinicopathological features of breast cancer patients. Besides, the effects of S100A8/A9 and DACH1 on patient outcomes were analyzed by tissue assays. Finally, xenograft tumor assays were adopted to validate the effects of DACH1 on tumor growth and S100A8/A9 expression. Results The level of S100A8/A9 was higher in breast cancer, relative to normal tissue. Increased S100A8/A9 was related to poor differentiation grade, loss of hormone receptors, and Her2 positive. Moreover, elevated S100A8/A9 predicted a worse prognosis for breast cancer patients. Meanwhile, serum S100A8 concentration was upregulated in Grade 3, basal-like, and Her2-overexpressed subtypes. Additionally, the results of public databases showed S100A8/A9 mRNA level was negatively correlated to DACH1. Stable overexpressing DACH1 in breast cancer cells significantly decreased the generation of S100A8. The survival analysis demonstrated that patients with high S100A8/A9 and low DACH1 achieved the shortest overall survival. The xenograft models indicated that DACH1 expression significantly retarded tumor growth and downregulated S100A8/A9 protein abundance. Conclusion S100A8/A9 is remarkedly increased in basal-like and Her2-overexpressed subtypes, predicting poor prognosis of breast cancer patients. Tumor suppressor DACH1 inhibits S100A8/A9 expression. The combination of S100A8/A9 and DACH1 predicted the overall survival of breast cancer patients more preciously.

Objective: This study probed into the effect of HNRNPL on ferroptosis in hepatocellular carcinoma (HCC) cells and related molecular mechanisms. Methods: Expression patterns of HNRNPL, Recombinant S100 Calcium Binding Protein A9 (S100A9) were analyzed in HCC tissues or cells. Following transfection, HCC cell activity was analyzed, followed by detection of levels of ROS, iron content, LPO, MDA, and GSH as well as the expression of ferroptosis-related proteins. For molecular mechanism, RIP, RNA pull-down assay and actinomycin D assay were implemented to verify the binding relationship between HNRNPL and S100A9. Finally, in vivo nude mouse xenograft tumor experiments were performed for further validate the crucial role of HNENPL expression in HCC. Results: HNRNPL and S100A9 were significantly overexpressed in HCC. sh-HNRNPL treatment led to a significant decrease in cellular activity, GSH content, and expression of GPX4 and SLC7A11, and a significant increase in iron content, LPO level, MDA, ROS content, and expression of ACSL4 and TFR1. In addition, after sh-HNRNPL was combined with oe-S100A9 or Fer-1, a ferroptosis inhibitor, both oe-S100A9 and Fer-1 reversed the promotional effect of sh-HNRNPL on ferroptosis of HCC cells when sh-HNRNPL acted alone. Mechanically, HNRNPL promoted S100A9 mRNA stability and expression through RBP. Furthermore, low expression of HNRNPL in vivo delayed the growth of xenograft tumors and the expression of ferroptosis-related proteins. Conclusion: HNRNPL promotes S100A9 mRNA stability and expression through RBP action, thereby promoting ferroptosis in HCC cells.