Diagnostic accuracy of serum calprotectin measured by CLIA and EIA in juvenile idiopathic arthritis: a proof-of-concept study.

Objective: C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are used to assess disease activity in juvenile idiopathic arthritis (JIA). However, because these biomarkers do not always differentiate between active and inactive disease, there is a need for alternative markers such as serum calprotectin (sCal). The main aim of this proof-of-concept study was to assess the diagnostic accuracy of sCal in patients with JIA. Secondary aims were to identify the optimal sCal cut-off levels to define active disease and evaluate the association between these biomarkers and disease activity status. Methods: Serum samples were obtained from 25 pediatric patients with JIA. Serum calprotectin levels were determined by two different assays, the QUANTA FLASH chemiluminescence immunoassay (CLIA) from Inova Diagnostics and the solid-phase enzyme immunoassay (EIA) from Bühlmann Laboratories. Diagnostic accuracy was assessed for sCal CLIA, sCal EIA, CRP, and ESR. The results obtained by the CLIA and EIA methodologies were compared. We also evaluated the association between the individual each biomarkers (sCal CLIA, sCal EIA, CRP, and ESR) and disease activity (according to JADAS-27 criteria and the ACR criteria modified by Anink and colleagues). Results: For both sCal assays (CLIA and EIA), the optimal cut-off level (ROC analysis) was the same (2.3 µg/ml). Serum calprotectin levels measured by CLIA and EIA were strongly correlated with each other (Kendall's tau-b, 0.71; p < 0.001). Compared to ESR and CRP, sCal CLIA and EIA were both more accurate (i.e., greater sensitivity) in identifying patients with active disease. By contrast, ESR and CRP were more effective in identifying patients in remission (i.e., better specificity). Conclusion: This proof-of-concept study shows that determination of serum calprotectin levels with CLIA or EIA can accurately identify the presence of active disease in patients with JIA.

Pro-inflammatory protein S100A9 targeted by a natural molecule to prevent neurodegeneration onset.

Accumulation of the pro-inflammatory protein S100A9 has been implicated in neuroinflammatory cascades in neurodegenerative diseases (NDs) such as Alzheimer's disease (AD) and Parkinson's disease (PD). S100A9 co-aggregates with other proteins such as α-synuclein in PD and Aß in AD, contributing to amyloid plaque formation and neurotoxicity. The amyloidogenic nature of this protein and its role in chronic neuroinflammation suggest that it may play a key role in the pathophysiology of these diseases. Research into molecules targeting S100A9 could be a potential therapeutic strategy to prevent its amyloidogenic self-assembly and to attenuate the neuroinflammatory response in affected brain tissue. This work suggests that bioactive natural molecules, such as those found in the Mediterranean diet, may have the potential to alleviate neuroinflammation associated with the accumulation of proteins such as S100A9 in neurodegenerative diseases. A major component of extra virgin olive oil (EVOO), hydroxytyrosol (HT), with its ability to interact with and modulate S100A9 amyloid self-assembly and expression, offers a compelling approach for the development of novel and effective interventions for the prevention and treatment of ND. The findings highlight the importance of exploring natural compounds, such as HT, as potential therapeutic options for these complex and challenging neurological conditions.

S100A9 as a Key Myocardial Injury Factor Interacting with ATP5 Exacerbates Mitochondrial Dysfunction and Oxidative Stress in Sepsis-Induced Cardiomyopathy.

Purpose: 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.

Alarming and calming: Dual functions of S100A9 on Mycoplasma gallisepticun infection in avian cells.

Mycoplasma gallisepticum (MG) is the primary causative agent of chronic respiratory disease (CRD) in chickens, characterized by respiratory inflammation. S100A9 plays a pivotal role in modulating the inflammatory response to microbial pathogens. Our prior investigation revealed a significant upregulation of S100A9 in the lungs of chickens following MG infection. This study delves into the immunomodulatory effects of S100A9 during MG infection, demonstrating a notable increase in S100A9 levels in the lungs, immune organs, alveolar epithelial type II cells (AECII), and macrophage HD11 cells of MG-infected chicks and embryos. In MG-infected AECII cells, S100A9 overexpression significantly enhanced MG proliferation and adhesion, suppressed AVBD1, NFκB, pro-inflammatory factors (IL1ß and TNFα), and chemokines, reduced apoptosis, and promoted cell proliferation, thereby facilitating MG infection. Conversely, inhibiting S100A9 produced opposing effects. In MG-infected HD11 cells, S100A9 impeded MG proliferation and adhesion, increased AVBD1, NFκB, pro-inflammatory factors, and chemokines, and induced cell apoptosis while inhibiting proliferation. Additional results demonstrated that S100A9 facilitates MG infection by modulating the TLR7/NFκB/JAK/STAT pathway in AECII/HD11 cells. In summary, S100A9 exhibits a dual role in activating/inhibiting the natural immune response through TLR7/NFκB/JAK/STAT pathway regulation. This dual role promotes MG infection in AECII cells while enabling MG to evade immune surveillance by HD11 cells, ultimately enhancing the overall infection process. These findings advance our understanding of host-pathogen interactions during MG infection and underscore S100A9's potential as a therapeutic target for CRD in chickens.

High-dose vitamin C attenuates radiation-induced pulmonary fibrosis by targeting S100A8 and S100A9.

Radiation-induced pulmonary fibrosis (RIPF) is a frequently encountered late complication in patients undergoing radiation therapy, presenting a substantial risk to patient mortality and quality of life. The pathogenesis of RIPF remains unclear, and current treatment options are limited in efficacy. High-dose vitamin C has demonstrated potential when used in conjunction with other adjuvant therapies due to potent anticancer properties. However, the potential relationship between high-dose vitamin C and RIPF has not yet been explored in existing literature. In our study, the RIPF model and the LLC tumor model were used as two animal models to explore how high-dose vitamin C can improve RIPF without hampering the antitumour efficacy of radiotherapy. The impact of high-dose vitamin C on RIPF was assessed through various assays, including micro-CT, HE staining, Masson staining, and immunohistochemistry. Our results indicated that administering high-dose vitamin C 2 days before radiation and continuing for a duration of 6 weeks significantly inhibited the progression of RIPF. In order to explore the mechanism by which high-dose vitamin C attenuates RIPF, we utilized RNA-seq analysis of mouse lung tissue in conjunction with publicly available databases. Our findings indicated that high-dose vitamin C inhibits the differentiation of fibroblasts into myofibroblasts by targeting S100A8 and S100A9 derived from neutrophils. Additionally, the combination of high-dose vitamin C and radiation demonstrated enhanced inhibition of tumor growth in a murine LLC tumor model. These results revealed that the combination of radiotherapy and high-dose vitamin C may offer a promising therapeutic approach for the clinical management of thoracic tumors and the prevention of RIPF.

S100A9 inhibits and redirects prion protein 89-230 fragment amyloid aggregation.

Protein aggregation in the form of amyloid fibrils has long been associated with the onset and development of various amyloidoses, including Alzheimer's, Parkinson's or prion diseases. Recent studies of their fibril formation process have revealed that amyloidogenic protein cross-interactions may impact aggregation pathways and kinetic parameters, as well as the structure of the resulting aggregates. Despite a growing number of reports exploring this type of interaction, they only cover just a small number of possible amyloidogenic protein pairings. One such pair is between two neurodegeneration-associated proteins: the pro-inflammatory S100A9 and prion protein, which are known to co-localize in vivo. In this study, we examined their cross-interaction in vitro and discovered that the fibrillar form of S100A9 modulated the aggregation pathway of mouse prion protein 89-230 fragment, while non-aggregated S100A9 also significantly inhibited its primary nucleation process. These results complement previous observations of the pro-inflammatory protein's role in amyloid aggregation and highlight its potential role against neurodegenerative disorders.

Ginsenoside Rg1 Regulates Immune Microenvironment and Neurological Recovery After Spinal Cord Injury Through MYCBP2 Delivery via Neuronal Cell-Derived Extracellular Vesicles.

Spinal cord injury (SCI) is a severe neurological condition that frequently leads to significant sensory, motor, and autonomic dysfunction. This study sought to delineate the potential mechanistic underpinnings of extracellular vesicles (EVs) derived from ginsenoside Rg1-pretreated neuronal cells (Rg1-EVs) in ameliorating SCI. These results demonstrated that treatment with Rg1-EVs substantially improved motor function in spinal cord-injured mice. Rg1-EVs enhance microglial polarization toward the M2 phenotype and repressed oxidative stress, thereby altering immune responses and decreasing inflammatory cytokine secretion. Moreover, Rg1-EVs substantially diminish reactive oxygen species accumulation and enhanced neural tissue repair by regulating mitochondrial function. Proteomic profiling highlighted a significant enrichment of MYCBP2 in Rg1-EVs, and functional assays confirmed that MYCBP2 knockdown counteracted the beneficial effects of Rg1-EVs in vitro and in vivo. Mechanistically, MYCBP2 is implicated in the ubiquitination and degradation of S100A9, thereby promoting microglial M2-phenotype polarization and reducing oxidative stress. Overall, these findings substantiated the pivotal role of Rg1-EVs in neuronal protection and functional recovery following SCI through MYCBP2-mediated ubiquitination of S100A9. This research offers novel mechanistic insights into therapeutic strategies against SCI and supports the clinical potential of Rg1-EVs.

PGAM5 interacts with and maintains BNIP3 to license cancer-associated muscle wasting.

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.

Dry environment on the expression of lacrimal gland S100A9, Anxa1, and Clu in rats via proteomics.

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.

Overexpressing S100A9 ameliorates NK cell dysfunction in estrogen receptor-positive breast cancer.

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.

Direct targeting of S100A9 with Icariin counteracted acetaminophen­induced hepatotoxicity.

Acetaminophen (APAP) is a widely used antipyretic and analgesic medication, but its overdose can induce acute liver failure with lack of effective therapies. Icariin is a bioactive compound derived from the herb Epimedium that displays hepatoprotective activities. Here, we explored the protective effects and mechanism of icariin on APAP-induced hepatotoxicity. Icariin (25/50 mg/kg) or N-Acetylcysteine (NAC, 300 mg/kg) were orally administered in wild-type C57BL/6 mice for 7 consecutive days before the APAP administration. Icariin attenuated APAP-induced acute liver injury in mice, as measured by alleviated serum enzymes activities and hepatic apoptosis. In vitro, icariin pretreatment significantly inhibited hepatocellular damage and apoptosis by reducing the BAX/Bcl-2 ratio as well as the expression of cleaved-caspase 3 and cleaved-PARP depended on the p53 pathway. Moreover, icariin attenuated APAP-mediated inflammatory response and oxidative stress via the Nrf2 and NF-κB pathways. Importantly, icariin reduced the expression of S100A9, icariin interacts with S100A9 as a direct cellular target, which was supported by molecular dynamics simulation and surface plasmon resonance assay (equilibrium dissociation constant, KD = 1.14 µM). In addition, the genetic deletion and inhibition of S100A9 not only alleviated APAP-induced injury but also reduced the icariin's protective activity in APAP-mediated liver injury. These data indicated that icariin targeted S100A9 to alleviate APAP-induced liver damage via the following signaling pathways NF-κB, p53, and Nrf2.

Blood calprotectin as a biomarker for infection and sepsis - the prospective CASCADE trial.

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.

S100A8-Mediated Inflammatory Signaling Drives Colorectal Cancer Progression via the CXCL5/CXCR2 Axis.

Background: S100A8/S100A9 belong to the S100 calcium-binding protein family and play an essential role in the progression of chronic inflammation in diseases. It also regulates various biological processes such as tumor cell survival, apoptosis, and invasive metastasis. The extracellular form of S100A8/S100A9 functions by modulating cellular oxidative metabolism and facilitating inflammation-to-cancer progression. This modulation occurs through specific binding to receptors like RAGE and TLR4 and activation of signaling pathways including STAT3 and NF-κB. In tumor cells, S100A8 and S100A9 induce phenotypic changes by influencing calcium ion concentrations and other pathways. However, the precise function of high S100A8/S100A9 expression in colorectal cancer cells remains unclear. Methods: To explore the role of S100A8/S100A9 in colorectal cancer, we used immunohistochemistry and data from GEO and TCGA databases to analyze its expression in colorectal cancer cells, normal intestinal mucosa, and adjacent tissues. Functional models of high S100A8/S100A9 expression in colorectal cancer cells were established through transfection with overexpression plasmids. Protein microarrays, enzyme-linked immunosorbent assays (ELISAs), and real-time PCR were employed to assess the expression and secretion of 40 cytokines. MTT and Transwell invasion assays were conducted to evaluate changes in cell proliferation, invasion, and chemotaxis. Finally, tail vein and subcutaneous tumorigenesis assays assessed cell proliferation and migration in vivo. Results: We observed significantly higher expression of S100A8/S100A9 in colorectal cancer epithelial cells compared to normal intestinal mucosa and adjacent tissues. Overexpression of S100A8/S100A9 in mouse colon cancer cells CT26.WT led to differential increases in the secretion levels of various cytokines (CXCL5, CXCL11, GM-CSF, G-CSF, IL1a, IL1b, sTNF RI, and CCL3). Additionally, this overexpression activated signaling pathways such as STAT3, NF-κB, and ERK-MAPK. The synthesis and secretion of inflammatory factors could be inhibited by using NF-κB and ERK-MAPK pathway inhibitors. Moreover, S100A8 promotes the proliferation and invasion of colon cancer cells. Notably, the CXCR2 inhibitor (SB265610) effectively reversed the phenotypic changes induced by the CXCL5/CXCR2 biological axis. Conclusions: Our findings indicate that increased expression of S100A8 and S100A9 in colon cancer epithelial cells enhances the secretion of inflammatory factors by activating NF-κB, ERK-MAPK, and other signaling pathways. S100A8 facilitates colon cancer cell proliferation, invasion, and metastasis through the CXCL5/CXCR2 biological axis.

The Features of Shared Genes among Transcriptomes Probed in Atopic Dermatitis, Psoriasis, and Inflammatory Acne: S100A9 Selection as the Target Gene.

BACKGROUND: Atopic dermatitis (AD), psoriasis (PS), and inflammatory acne (IA) are well-known as inflammatory skin diseases. Studies of the transcriptome with altered expression levels have reported a large number of dysregulated genes and gene clusters, particularly those involved in inflammatory skin diseases. OBJECTIVE: To identify genes commonly shared in AD, PS, and IA that are potential therapeutic targets, we have identified consistently dysregulated genes and disease modules that overlap with AD, PS, and IA. METHODS: Microarray data from AD, PS, and IA patients were downloaded from Gene Expression Omnibus (GEO), and identification of differentially expressed genes from microarrays of AD, PS, and IA was conducted. Subsequently, gene ontology and gene set enrichment analysis, detection of disease modules with known disease-associated genes, construction of the protein-protein interaction (PPI) network, and PPI sub-mapping analysis of shared genes were performed. Finally, the computational docking simulations between the selected target gene and inhibitors were conducted. RESULTS: We identified 50 shared genes (36 up-regulated and 14 down-regulated) and disease modules for each disease. Among the shared genes, 20 common genes in PPI network were detected such as LCK, DLGAP5, SELL, CEP55, CDC20, RRM2, S100A7, S100A9, MCM10, AURKA, CCNB1, CHEK1, BTC, IL1F7, AGTR1, HABP4, SERPINB13, RPS6KA4, GZMB, and TRIP13. Finally, S100A9 was selected as the target gene for therapeutics. Docking simulations between S100A9 and known inhibitors indicated several key binding residues, and based on this result, we suggested several cannabinoids such as WIN-55212-2, JZL184, GP1a, Nabilone, Ajulemic acid, and JWH-122 could be potential candidates for a clinical study for AD, PS, and IA via inhibition of S100A9-related pathway. CONCLUSION: Overall, our approach may become an effective strategy for discovering new disease candidate genes for inflammatory skin diseases with a reevaluation of clinical data.

S100A9 exacerbates sepsis-induced acute lung injury via the IL17-NFκB-caspase-3 signaling pathway.

BACKGROUND: Sepsis-induced acute lung injury (ALI) is associated with considerable morbidity and mortality in critically ill patients. S100A9, a key endothelial injury factor, is markedly upregulated in sepsis-induced ALI; however, its specific mechanism of action has not been fully elucidated. METHODS: The Gene Expression Omnibus database transcriptome data for sepsis-induced ALI were used to screen for key differentially expressed genes (DEGs). Using bioinformatics analysis methods such as Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and protein-protein interaction network analyses, the pathogenesis of sepsis-induced ALI was revealed. Intratracheal infusion of lipopolysaccharide (LPS, 10 mg/kg) induced ALI in wild-type (WT) and S100A9 knockout mice. Multiomics analyses (transcriptomics and proteomics) were performed to investigate the potential mechanisms by which S100A9 exacerbates acute lung damage. Hematoxylin-eosin, Giemsa, and TUNEL staining were used to evaluate lung injury and cell apoptosis. LPS (10 µg/mL)-induced murine lung epithelial MLE-12 cells were utilized to mimic ALI and were modulated by S100A9 lentiviral transfection. The impact of S100A9 on cell apoptosis and inflammatory responses were identified using flow cytometry and PCR. The expression of interleukin (IL)-17-nuclear factor kappa B (NFκB)-caspase-3 signaling components was identified using western blotting. RESULTS: Six common DEGs (S100A9, S100A8, IFITM6, SAA3, CD177, and MMP9) were identified in the six datasets related to ALI in sepsis. Compared to WT sepsis mice, S100A9 knockout significantly alleviated LPS-induced ALI in mice, with reduced lung structural damage and inflammatory exudation, decreased exfoliated cell and protein content in the lung lavage fluid, and reduced apoptosis and necrosis of pulmonary epithelial cells. Transcriptomic analysis revealed that knocking out S100A9 significantly affected 123 DEGs, which were enriched in immune responses, defense responses against bacteria or lipopolysaccharides, cytokine-cytokine receptor interactions, and the IL-17 signaling pathway. Proteomic analysis revealed that S100A9 knockout alleviated muscle contraction dysfunction and structural remodeling in sepsis-induced ALI. Multiomics analysis revealed that S100A9 may be closely related to interferon-induced proteins with tetratricopeptide repeats and oligoadenylate synthase-like proteins. LPS decreased MLE12 cell activity, accompanied by high expression of S100A9. The expression of IL-17RA, pNFκB, and cleaved-caspase-3 were increased by S100A9 overexpression and reduced by S100A9 knockdown in LPS-stimulated MLE12 cells. S100A9 knockdown decreases transcription of apoptosis-related markers Bax, Bcl and caspase-3, alleviating LPS-induced apoptosis. CONCLUSIONS: S100A9 as a key biomarker of sepsis-induced acute lung injury, and exacerbates lung damage and epithelial cell apoptosis induced by LPS via the IL-17-NFκB-caspase-3 signaling pathway.

Novel biomarkers related to oxidative stress and immunity in chronic kidney disease.

Introduction: The incidence of chronic kidney disease (CKD) has been increasing in recent years, gradually becoming a global health crisis. Due to limited treatment options, novel molecular pathways are urgently required to advance the treatment and diagnosis of CKD. Materials and methods: The characteristics of differentially expressed genes (DEGs) in CKD patients were analyzed using Gene Expression Omnibus (GEO) database, and genes related to oxidative stress were retrieved from the Genecard database. Subsequently, a comprehensive approach was applied, including immune infiltration analysis, weighted gene co-expression network analysis (WGCNA) and protein-protein interaction (PPI) network analysis, to identify hub genes among differentially expressed immune-related oxidative stress genes (DEIOSGs). Validation of hub genes was performed using an external data set, and diagnostic potential capability was evaluated through receiver operating curve (ROC) analysis. In animal experiments, the expression of hub genes in CKD was confirmed by inducing a CKD model through a 5/6 nephrectomy procedure. Finally, the relationship between these hub genes and clinical characteristics were assessed using the Nephroseq v5 database. Results: 29 DEIOSGs were identified by comprehensive bioinformatics analysis. PPI analysis screened the hub genes NCF2, S100A9, and SELL. ROC analysis demonstrated excellent diagnostic efficacy. Further validation from other databases and animal experiments confirmed a substantial upregulation in the expression of hub genes in CKD. Additionally, clinical correlation analysis established a clear link between hub gene expression and renal function deterioration. Conclusions: Our study confirms NCF2, S100A9, and SELL as diagnostic biomarkers associated with immune response and oxidative stress in CKD, suggesting their potential as novel targets for CKD diagnosis and treatment.

scRNA-Seq and Bulk-Seq Analysis Identifies S100A9 Plasma Cells as a Potentially Effective Immunotherapeutic Agent for Multiple Myeloma.

Purpose: 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.

S100A9 Exacerbates the Inflammation in Rosacea through Toll-Like Receptor 4/MyD88/NF-κB Signaling Pathway.

Rosacea is a chronic inflammatory skin disorder characterized by immune response-dependent erythema and pustules. S100A9, a proinflammatory alarmin, has been associated with various inflammation-related diseases. However, the specific role of S100A9 in rosacea remains unexplored. Therefore, our objective was to unravel the role of S100A9 in the pathogenesis of rosacea and its underlying molecular mechanisms. In this study, we show that expression levels of S100A9 were elevated in both the lesions and serum of patients with papulopustular rosacea as well as in lesions of the LL37-induced rosacea-like mouse model. Moreover, the upregulation of S100A9 was correlated with clinical severity and levels of inflammatory cytokines. In addition, we demonstrated that S100A9 promoted the production of proinflammatory factors in HaCaT cells by activating toll-like receptor 4/MyD88/NF-κB signaling pathways. Notably, inhibition of S100A9 suppressed the progression of rosacea-like dermatitis and inflammatory responses in the LL37-induced rosacea-like mouse model through toll-like receptor 4/MyD88/NF-κB signaling pathways. In conclusion, this study illustrated that S100A9 participates in the pathogenesis of rosacea by upregulating toll-like receptor 4/MyD88/NF-κB signaling pathways, thereby promoting rosacea-associated skin inflammation. These results not only expand our understanding of the potential role of S100A9 in the development of rosacea but also offer greater insight toward targeted therapies.

FGF2 gene's antisense protein, NUDT6, plays a depressogenic role by promoting inflammation and suppressing neurogenesis without altering FGF2 signalling.

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.