S100a8/9 (S100 Calcium Binding Protein a8/9) Promotes Cardiac Hypertrophy Via Upregulation of FGF23 (Fibroblast Growth Factor 23) in Mice.

BACKGROUND: S100a8/9 (S100 calcium binding protein a8/9) belongs to the S100 family and has gained a lot of interest as a critical regulator of inflammatory response. Our previous study found that S100a8/9 homolog promoted aortic valve sclerosis in mice with chronic kidney disease. However, the role of S100a8/9 in pressure overload-induced cardiac hypertrophy remains unclear. The present study was to explore the role of S100a8/9 in cardiac hypertrophy. METHODS AND RESULTS: Cardiomyocyte-specific S100a9 loss or gain of function was achieved using an adeno-associated virus system, and the model of cardiac hypertrophy was established by aortic banding-induced pressure overload. The results indicate that S100a8/9 expression was increased in response to pressure overload. S100a9 deficiency alleviated pressure overload-induced hypertrophic response, whereas S100a9 overexpression accelerated cardiac hypertrophy. S100a9-overexpressed mice showed increased FGF23 (fibroblast growth factor 23) expression in the hearts after exposure to pressure overload, which activated calcineurin/NFAT (nuclear factor of activated T cells) signaling in cardiac myocytes and thus promoted hypertrophic response. A specific antibody that blocks FGFR4 (FGF receptor 4) largely abolished the prohypertrophic response of S100a9 in mice. CONCLUSIONS: In conclusion, S100a8/9 promoted the development of cardiac hypertrophy in mice. Targeting S100a8/9 may be a promising therapeutic approach to treat cardiac hypertrophy.

Usp14 deficiency removes α-synuclein by regulating S100A8/A9 in Parkinson's disease.

Ubiquitin-proteasome system dysfunction triggers α-synuclein aggregation, a hallmark of neurodegenerative diseases, such as Parkinson's disease (PD). However, the crosstalk between deubiquitinating enzyme (DUBs) and α-synuclein pathology remains unclear. In this study, we observed a decrease in the level of ubiquitin-specific protease 14 (USP14), a DUB, in the cerebrospinal fluid (CSF) of PD patients, particularly females. Moreover, CSF USP14 exhibited a dual correlation with α-synuclein in male and female PD patients. To investigate the impact of USP14 deficiency, we crossed USP14 heterozygous mouse (USP14+/-) with transgenic A53T PD mouse (A53T-Tg) or injected adeno-associated virus (AAV) carrying human α-synuclein (AAV-hα-Syn) in USP14+/- mice. We found that Usp14 deficiency improved the behavioral abnormities and pathological α-synuclein deposition in female A53T-Tg or AAV-hα-Syn mice. Additionally, Usp14 inactivation attenuates the pro-inflammatory response in female AAV-hα-Syn mice, whereas Usp14 inactivation demonstrated opposite effects in male AAV-hα-Syn mice. Mechanistically, the heterodimeric protein S100A8/A9 may be the downstream target of Usp14 deficiency in female mouse models of α-synucleinopathies. Furthermore, upregulated S100A8/A9 was responsible for α-synuclein degradation by autophagy and the suppression of the pro-inflammatory response in microglia after Usp14 knockdown. Consequently, our study suggests that USP14 could serve as a novel therapeutic target in PD.

S100A8/9 modulates perturbation and glycolysis of macrophages in allergic asthma mice.

Background: Allergic asthma is the most prevalent asthma phenotype and is associated with the disorders of immune cells and glycolysis. Macrophages are the most common type of immune cells in the lungs. Calprotectin (S100A8 and S100A9) are two pro-inflammatory molecules that target the Toll-like receptor 4 (TLR4) and are substantially increased in the serum of patients with severe asthma. This study aimed to determine the effects of S100A8/A9 on macrophage polarization and glycolysis associated with allergic asthma. Methods: To better understand the roles of S100A8 and S100A9 in the pathogenesis of allergic asthma, we used ovalbumin (OVA)-induced MH-S cells, and OVA-sensitized and challenged mouse models (wild-type male BALB/c mice). Enzyme-linked immunosorbent assay, quantitative real-time polymerase chain reaction, flow cytometry, hematoxylin-eosin staining, and western blotting were performed. The glycolysis inhibitor 3-bromopyruvate (3-BP) was used to observe changes in glycolysis in mice. Results: We found knockdown of S100A8 or S100A9 in OVA-induced MH-S cells inhibited inflammatory cytokines, macrophage polarization biomarker expression, and pyroptosis cell proportion, but increased anti-inflammatory cytokine interleukin (IL)-10 mRNA; also, glycolysis was inhibited, as evidenced by decreased lactate and key enzyme expression; especially, knockdown of S100A8 or S100A9 inhibited the activity of TLR4/myeloid differentiation primary response gene 88 (MyD88)/Nuclear factor kappa-B (NF-κB) signaling pathway. Intervention with lipopolysaccharides (LPS) abolished the beneficial effects of S100A8 and S100A9 knockdown. The observation of OVA-sensitized and challenged mice showed that S100A8 or S100A9 knockdown promoted respiratory function, improved lung injury, and inhibited inflammation; knockdown of S100A8 or S100A9 also suppressed macrophage polarization, glycolysis levels, and activation of the TLR4/MyD88/NF-κB signaling pathway in the lung. Conversely, S100A9 overexpression exacerbated lung injury and inflammation, promoting macrophage polarization and glycolysis, which were antagonized by the glycolysis inhibitor 3-BP. Conclusion: S100A8 and S100A9 play critical roles in allergic asthma pathogenesis by promoting macrophage perturbation and glycolysis through the TLR4/MyD88/NF-κB signaling pathway. Inhibition of S100A8 and S100A9 may be a potential therapeutic strategy for allergic asthma.

Computational Deciphering of the Role of S100A8 and S100A9 Proteins and Their Changes in the Structure Assembly Influences Their Interaction with TLR4, RAGE, and CD36.

S100A8 and S100A9 belong to the calcium-binding, damage associated molecular pattern (DAMP) proteins shown to aggravate the pathogenesis of rheumatoid arthritis (RA) through their interaction with the TLR4, RAGE and CD36 receptors. S100A8 and S100A9 proteins tend to exist in monomeric, homo and heterodimeric forms, which have been implicated in the pathogenesis of RA, via interacting with Pattern Recognition receptors (PRRs). The study aims to assess the influence of changes in the structure and biological assembly of S100A8 and S100A9 proteins as well as their interaction with significant receptors in RA through computational methods and surface plasmon resonance (SPR) analysis. Molecular docking analysis revealed that the S100A9 homodimer and S100A8/A9 heterodimer showed higher binding affinity towards the target receptors. Most S100 proteins showed good binding affinity towards TLR4 compared to other receptors. Based on the 50 ns MD simulations, TLR4, RAGE, and CD36 formed stable complexes with the monomeric and dimeric forms of S100A8 and S100A9 proteins. However, SPR analysis showed that the S100A8/A9 heterodimers formed stable complexes and exhibited high binding affinity towards the receptors. SPR data also indicated that TLR4 and its interactions with S100A8/A9 proteins may play a primary role in the pathogenesis of RA, with additional contributions from CD36 and RAGE interactions. Subsequent in vitro and in vivo investigations are warranted to corroborate the involvement of S100A8/A9 and the expression of TLR4, RAGE, and CD36 in the pathophysiology of RA.

S100A8/A9 as a prognostic biomarker with causal effects for post-acute myocardial infarction heart failure.

Heart failure is the prevalent complication of acute myocardial infarction. We aim to identify a biomarker for heart failure post-acute myocardial infarction. This observational study includes 1062 and 1043 patients with acute myocardial infarction in the discovery and validation cohorts, respectively. The outcomes are in-hospital and long-term heart failure events. S100A8/A9 is screened out through proteomic analysis, and elevated circulating S100A8/A9 is independently associated with heart failure in discovery and validation cohorts. Furthermore, the predictive value of S100A8/A9 is superior to the traditional biomarkers, and the addition of S100A8/A9 improves the risk estimation using traditional risk factors. We finally report causal effect of S100A8/A9 on heart failure in three independent cohorts using Mendelian randomization approach. Here, we show that S100A8/A9 is a predictor and potentially causal medicator for heart failure post-acute myocardial infarction.

S100A8-enriched microglia populate the brain of tau-seeded and accelerated aging mice.

Long considered to fluctuate between pro- and anti-inflammatory states, it has now become evident that microglia occupy a variegated phenotypic landscape with relevance to aging and neurodegeneration. However, whether specific microglial subsets converge in or contribute to both processes that eventually affect brain function is less clear. To investigate this, we analyzed microglial heterogeneity in a tauopathy mouse model (K18-seeded P301L) and an accelerated aging model (Senescence-Accelerated Mouse-Prone 8, SAMP8) using cellular indexing of transcriptomes and epitopes by sequencing. We found that widespread tau pathology in K18-seeded P301L mice caused a significant change in the number and morphology of microglia, but only a mild overrepresentation of disease-associated microglia. At the cell population-level, we observed a marked upregulation of the calprotectin-encoding genes S100a8 and S100a9. In 9-month-old SAMP8 mice, we identified a unique microglial subpopulation that showed partial similarity with the disease-associated microglia phenotype and was additionally characterized by a high expression of the same calprotectin gene set. Immunostaining for S100A8 revealed that this population was enriched in the hippocampus, correlating with the cognitive impairment observed in this model. However, incomplete colocalization between their residence and markers of neuronal loss suggests regional specificity. Importantly, S100A8-positive microglia were also retrieved in brain biopsies of human AD and tauopathy patients as well as in a biopsy of an aged individual without reported pathology. Thus, the emergence of S100A8-positive microglia portrays a conspicuous commonality between accelerated aging and tauopathy progression, which may have relevance for ensuing brain dysfunction.

S100A8/A9 promotes endometrial fibrosis via regulating RAGE/JAK2/STAT3 signaling pathway.

Intrauterine adhesion (IUA) is characterized by endometrial fibrosis. S100A8/A9 plays an important role in inflammation and fibroblast activation. However, the role of S100A8/A9 in IUA remains unclear. In this study, we collect normal and IUA endometrium to verify the expression of S100A8/A9. Human endometrial stromal cells (hEnSCs) are isolated to evaluate fibrosis progression after S100A8/A9 treatment. A porcine IUA model is established by electrocautery injury to confirm the therapeutic effect of menstrual blood-derived stromal cells (MenSCs) on IUA. Our study reveals increased S100A8/A9 expression in IUA endometrium. S100A8/A9 significantly enhances hEnSCs proliferation and upregulates fibrosis-related and inflammation-associated markers. Furthermore, S100A8/A9 induces hEnSCs fibrosis through the RAGE-JAK2-STAT3 pathway. Transplantation of MenSCs in a porcine IUA model notably enhances angiogenesis, mitigates endometrial fibrosis and downregulates S100A8/A9 expression. In summary, S100A8/A9 induces hEnSCs fibrosis via the RAGE-JAK2-STAT3 pathway, and MenSCs exhibit marked effects on endometrial restoration in the porcine IUA model.

Association Between Clinicopathological Parameters and S100A8/A9 Expression According to Smoking History in Patients With Non-small Cell Lung Cancer.

BACKGROUND/AIM: Lung cancer is a major cause of cancer-related deaths worldwide, and chronic inflammation caused by cigarette smoke plays a crucial role in the development and progression of this disease. S100A8/9 and RAGE are associated with chronic inflammatory diseases and cancer. This study aimed to investigate the expression of S100A8/9, HMBG1, and other related pro-inflammatory molecules and clinical characteristics in patients with non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: We obtained serum and bronchoalveolar lavage (BAL) fluid samples from 107 patients and categorized them as never or ever-smokers. We measured the levels of S100A8/9, RAGE, and HMGB1 in the collected samples using enzyme-linked immunosorbent kits. Immunohistochemical staining was also performed to assess the expression of S100A8/9, CD11b, and CD8 in lung cancer tissues. The correlation between the expression of these proteins and the clinical characteristics of patients with NSCLC was also explored. RESULTS: The expression of S100A8/A9, RAGE, and HMGB was significantly correlated with smoking status and was higher in people with a history of smoking or who were currently smoking. There was a positive correlation between serum and BAL fluid S100A8/9 levels. The expression of S100A8/A9 and CD8 in lung tumor tissues was significantly correlated with smoking history in patients with NSCLC. Ever-smokers, non-adenocarcinoma histology, and high PD-L1 expression were significant factors predicting high serum S100A8/9 levels in multivariate analysis. CONCLUSION: The S100A8/9-RAGE pathway and CD8 expression were increased in smoking-related NSCLC patients. The S100A8/9-RAGE pathway could be a promising biomarker for chronic airway inflammation and carcinogenesis in smoking-related lung diseases.

Deficiency of S100A8/A9 attenuates pulmonary microvascular leakage in septic mice.

BACKGROUND: We have reported a positive correlation between S100 calcium-binding protein (S100) A8/S100A9 and sepsis-induced lung damage before. However, limited knowledge exists concerning the biological role of S100A8/A9 in pulmonary vascular endothelial barrier dysfunction, as well as the diagnostic value of S100A8/A9 in sepsis. METHODS: Sepsis was induced in C57BL/6J mice and S100A9-knockout (KO) mice through the cecal ligation and puncture (CLP). Pulmonary vascular leakage was determined by measuring extravasated Evans blue (EB). Reverse transcription polymerase chain reaction and the histological score were used to evaluate inflammation and lung injury, respectively. Recombinant S100A8/A9 (rhS100A8/A9) was used to identify the effects of S100A8/A9 on endothelial barrier dysfunction in human umbilical vein endothelial cells (HUVECs). Additionally, the diagnostic value of S100A8/A9 in sepsis was assessed using receiver operating characteristic. RESULTS: S100A8/A9 expression was up-regulated in the lungs of CLP-operated mice. S100A9 KO significantly reversed CLP-induced hypothermia and hypotension, resulting in an improved survival rate. S100A9 KO also decreased the inflammatory response, EB leakage, and histological scores in the lungs of CLP-operated mice. Occludin and VE-cadherin expressions were decreased in the lungs of CLP-operated mice; However, S100A9 KO attenuated this decrease. Moreover, CLP-induced signal transducer and activator of transcription 3 (STAT3) and p38/extracellular signal-regulated kinase (ERK) signalling activation and apoptosis were mitigated by S100A9 KO in lungs. In addition, rhS100A8/A9 administration significantly decreased occludin and VE-cadherin expressions, increased the phosphorylated (p)-ERK/ERK, p-p38/p38, and B-cell leukaemia/lymphoma 2 protein (Bcl-2)-associated X protein/Bcl-2 ratios in HUVECs. CONCLUSION: The present study demonstrated S100A8/A9 aggravated sepsis-induced pulmonary inflammation, vascular permeability, and lung injury. This was achieved, at least partially, by activating the P38/STAT3/ERK signalling pathways. Moreover, S100A8/A9 showed the potential as a biomarker for sepsis diagnosis.

Prognostic significance of peripheral blood S100A12, S100A8, and S100A9 concentrations in idiopathic pulmonary fibrosis.

BACKGROUND: S100A12, S100A8, and S100A9 are inflammatory disease biomarkers whose functional significance in idiopathic pulmonary fibrosis (IPF) remains unclear. We evaluated the significance of S100A12, S100A8, and S100A9 levels in IPF development and prognosis. METHODS: The dataset was collected from the Gene Expression Omnibus (GEO) database and differentially expressed genes were screened using GEO2R. We conducted a retrospective study of 106 patients with IPF to explore the relationships between different biomarkers and poor outcomes. Pearson's correlation coefficient, Kaplan-Meier, Cox regression, and functional enrichment analyses were used to evaluate relationships between these biomarkers' levels and clinical parameters or prognosis. RESULTS: Serum levels of S100A12, S100A8, and S100A9 were significantly elevated in patients with IPF. The two most significant co-expression genes of S100A12 were S100A8 and S100A9. Patients with levels of S100A12 (median 231.21 ng/mL), S100A9 (median 57.09 ng/mL) or S100A8 (median 52.20 ng/mL), as well as combined elevated S100A12, S100A9, and S100A8 levels, exhibited shorter progression-free survival and overall survival. Serum S100A12 and S100A8, S100A12 and S100A9, S100A9 and S100A8 concentrations also displayed a strong positive correlation (rs2 = 0.4558, rs2 = 0.4558, rs2 = 0.6373; P < 0.001). S100A12 and S100A8/9 concentrations were independent of FVC%, DLCO%, and other clinical parameters (age, laboratory test data, and smoking habit). Finally, in multivariate analysis, the serum levels of S100A12, S100A8, and S100A9 were significant prognostic factors (hazard ratio 1.002, P = 0.032, hazard ratio 1.039, P = 0.001, and hazard ratio 1.048, P = 0.003). CONCLUSIONS: S100A12, S100A8, and S100A9 are promising circulating biomarkers that may aid in determining IPF patient prognosis. Multicenter clinical trials are needed to confirm their clinical value.

The Cxcr2+ subset of the S100a8+ gastric granylocytic myeloid-derived suppressor cell population (G-MDSC) regulates gastric pathology.

Introduction: Gastric myeloid-derived suppressor cells (MDSCs) are a prominent population that expands during gastric pre-neoplastic and neoplastic development in humans and mice. However, the heterogeneity of this population has circumvented the ability to study these cells or understand their functions. Aside from Schlafen-4+ (Slfn-4+) MDSCs in mouse studies, which constitute a subset of this population, limitations exist in characterizing the heterogeneity of the gastric CD11b+Ly6G+ population and targeting its different subsets. Here we identify S100a8 as a pan-specific marker for this population and utilize it to study the role of the S100a8+Cxcr2+ subset. Methods: We profiled gastric CD11b+Ly6G+ versus CD11b+Ly6G- myeloid cells by transcriptomic and single-cell RNA sequencing. We identified S100a8 as a pan-specific marker of the gastric granulocytic MDSC (G-MDSC) population, and generated S100a8CreCxcr2flox/flox to study the effects of Cxcr2 knockdown. Results: Following 6-months of Helicobacter felis infection, gastric CD11b+Ly6G+ G-MDSCs were highly enriched for the expression of S100a8, S100a9, Slfn4, Cxcr2, Irg1, Il1f9, Hcar2, Retnlg, Wfdc21, Trem1, Csf3R, Nlrp3, and Il1b. The expression of these distinct genes following 6mo H. felis infection marked heterogeneous subpopulations, but they all represented a subset of S100a8+ cells. S100a8 was identified as a pan-marker for CD11b+Ly6G+ cells arising in chronic inflammation, but not neutrophils recruited during acute gut infection. 6mo Helicobacter felis-infected S100a8CreCxcr2flox/flox mice exhibited worsened gastric metaplastic pathology than Cxcr2flox/flox mice, which was associated with dysregulated lipid metabolism and peroxidation. Conclusion: S100a8 is a pan-specific marker that can be used to target gastric G-MDSC subpopulations, of which the Cxcr2+ subset regulates gastric immunopathology and associates with the regulation of lipid peroxidation.

S100 Calcium-Binding Protein A8 Functions as a Tumor-Promoting Factor in Renal Cell Carcinoma via Activating NF-κB Signaling Pathway.

BACKGROUND: Renal cell carcinoma (RCC), arising from the renal tubular epithelium, is one of the most common types of genitourinary malignancies. Based on the Gene Expression Omnibus (GEO) database (GSE100666), S100 calcium-binding protein A8 (S100A8) was highly expressed in RCC tissues. S100A8, an inflammatory regulatory factor, has emerged as an important mediator associated with the occurrence and development of cancer. MATERIALS AND METHODS: The Gene Expression Omnibus (GEO) database was used to identify the key genes and investigate the main signaling pathways in RCC. Human RCC samples and corresponding adjacent normal tissues were collected in our hospital. The expression of S100A8 in human RCC samples was detected using western blotting and immunohistochemical analysis. S100A8 overexpression or knockdown was mediated by using Lipofectamine 3000 in human renal cell carcinoma cell line 786-O and ACHN cells. Basic experiments, including MTT and cell apoptosis assays, were utilized for investigating the function of S100A8 in RCC. Furthermore, the levels of inflammation were also evaluated in 786-O and ACHN cells. RESULTS: In the current study, we found that downregulation of S100A8 inhibited proliferation and promoted apoptosis in 786-O and ACHN RCC cells. Of note, S100A8 silencing downregulated the phosphorylation of NF-κB p65, thereby decreasing the levels of TNF-α, cleaved caspase1, and MMP9. By contrast, S100A8 upregulation could increase these expressions. CONCLUSION: Overall, S100A8 knockdown restrained RCC malignant biological properties, which was associated with the deactivation of the NF-κB signaling pathway. This present study demonstrates new insights that S100A8 may be a potential therapeutic target in RCC.

CD74 Promotes a Pro-Inflammatory Tumor Microenvironment by Inducing S100A8 and S100A9 Secretion in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive form of pancreatic cancer with a poor prognosis and low survival rates. The prognostic and predictive biomarkers of PDAC are still largely unknown. The receptor CD74 was recently identified as a regulator of oncogenic properties in various cancers. However, the precise molecular mechanism of CD74 action in PDAC remains little understood. We investigated the role of CD74 by silencing CD74 in the pancreatic cancer cell line Capan-1. CD74 knockdown led to reductions in cell proliferation, migration, and invasion and increased apoptosis. Moreover, silencing CD74 resulted in the decreased expression and secretion of S100A8 and S100A9. An indirect co-culture of fibroblasts and tumor cells revealed that fibroblasts exposed to conditioned media from CD74 knockdown cells exhibited a reduced expression of inflammatory cytokines, suggesting a role of CD74 in influencing cytokine secretion in the tumor microenvironment. Overall, our study provides valuable insights into the critical role of CD74 in regulating the oncogenic properties of pancreatic cancer cells and its influence on the expression and secretion of S100A8 and S100A9. Taken together, these findings indicate CD74 as a potential diagnostic biomarker and therapeutic target for pancreatic cancer.

CRISPR-Cas9 based knockout of S100A8 in mammary epithelial cells enhances cell proliferation and triggers oncogenic transformation via the PI3K-Akt pathway: Insights from a deep proteomic analysis.

S100A8 is a calcium-binding protein with multiple functions, including being a chemoattractant for phagocytes and playing a key role in the inflammatory response. Its expression has been shown to influence epithelial-mesenchymal transition (EMT) and metastasis in colorectal cancer. However, the role of S100A8 in cell proliferation and differentiation remains unknown. In this study, we used the CRISPR-Cas9 system to knock out S100A8 in healthy mammary epithelial cells and investigated the resulting changes in proteome profiling and signaling pathways. Our results showed that S100A8 knockout led to an increase in cell proliferation and migration, reduced cell-cell adhesion, and increased apoptosis compared to wildtype cells. Proteomics data indicated that S100A8 significantly affects cell cycle progression, cell proliferation, and cell survival through the PI3K-Akt pathway. Furthermore, our findings suggest that S100A8 function is associated with Pten expression, a negative regulator of the PI3K-Akt pathway. These results indicate that S100A8 dysregulation in healthy cells can lead to altered cellular physiology and higher proliferation, similar to cancerous growth. Therefore, maintaining S100A8 expression is critical for preserving healthy cell physiology. This study provides novel insights into the role of S100A8 in cell proliferation and differentiation and its potential relevance to cancer biology. SIGNIFICANCE: The study suggests that maintaining S100A8 expression is critical for preserving healthy cell physiology, and dysregulation of S100A8 in healthy cells can lead to altered cellular physiology and higher proliferation, similar to cancerous growth. Therefore, targeting the PI3K-Akt pathway or regulating Pten expression, a negative regulator of the PI3K-Akt pathway, may be potential strategies for cancer treatment by controlling S100A8 dysregulation. Additionally, S100A8 and S100A9 have been shown to promote metastasis of breast carcinoma by forming a metastatic milieu. However, the differential expression of S100A8 in tumors and its dual effects of antitumor and protumor make the relationship between S100A8 and tumors complicated. Currently, most research focuses on the function of S100A8 as a secretory protein in the microenvironment of tumors, and its function inside healthy cells without forming dimers remains unclear. Furthermore, the study provides insight into the role of S100A8 in cell proliferation and differentiation, which may have implications for other diseases beyond cancer. The functional role of S100A8 in normal mammary epithelial cells remains completely uncertain. Therefore, the objective of this study is to investigate the function of S100A8 on proliferation in mammary epithelial cells after its deletion and to elucidate the underlying proteins involved in downstream signaling. Our findings indicate that the deletion of S100A8 leads to excessive proliferation in normal mammary epithelial cells, reduces apoptosis, and affects cell-cell adhesion molecules required for cellular communication, resulting in a cancer-like phenotype.

Identification of S100A8 as a common diagnostic biomarkers and exploring potential pathogenesis for osteoarthritis and metabolic syndrome.

Background: Osteoarthritis (OA) is the most frequent musculoskeletal disease and the major contributor to disability worldwide. Metabolic syndrome (MetS) has been recognized as being associated with the pathogenesis of osteoarthritis. However, the exact mechanisms and links between the two are not clear. Methods: We downloaded clinical information data and gene expression profiles for OA and MetS from the database of Gene Expression Omnibus (GEO), and immune related gene (IRG) from the database of Immunology Database and Analysis Portal (IMMPORT). After screening OA-DEG and MetS-DEG, we identified the common immune hub gene by screening the overlapping genes between OA-DEG, MetS-DEG and IRG. Then we conducted single-gene analysis of S100A8, assessed the correlation of S100A8 with immune cell infiltration, and verified the diagnostic value of S100A8 in OA and MetS database respectively. Results: 323 OA-DEGs,101 MetS-DEGs and an immune-related hub gene, S100A8, were identified. In single gene analysis of S100A8 in OA samples, GSEA suggested that immune-related biological processes were more significantly enriched. The results of immune cell infiltration analysis showed that the enrichment fraction of M2 macrophages was significantly higher in the high S100A8-expressing group, and the level of S100A8 expression was positively correlated with M2 macrophage infiltration. The results of the dataset validation showed that S100A8 expression levels were significantly upregulated in the OA group and performed well in the diagnosis of OA. In single gene analysis of S100A8 in MetS samples, immune cell infiltration analysis showed that monocyte infiltration was higher in the S100A8 high expression samples and that there was a positive correlation between the two. Dataset validation showed that S100A8 is of high value for the diagnosis of MetS. In the validation of the dataset for the four metabolism-related diseases (obesity, diabetes, hypertension and hyperlipidaemia), S100A8 was expressed at higher levels in the disease group and also had a higher diagnostic value for the four metabolism-related diseases. Conclusion: S100A8 is a common hub gene and diagnostic biomarker for OA and MetS, and the immune regulation involved in S100A8 may play a central role in the pathogenesis of OA and MetS.

S100A8 gene copy number and protein expression in breast cancer: associations with proliferation, histopathological grade and molecular subtypes.

BACKGROUND AND AIMS: Amplification of S100A8 occurs in 10-30% of all breast cancers and has been linked to poorer prognosis. Similarly, the protein S100A8 is overexpressed in a roughly comparable proportion of breast cancers and is also found in infiltrating myeloid-lineage cells, again linked to poorer prognosis. We explore the relationship between these findings. METHODS: We examined S100A8 copy number (CN) alterations using fluorescence in situ hybridization in 475 primary breast cancers and 117 corresponding lymph nodes. In addition, we studied S100A8 protein expression using immunohistochemistry in 498 primary breast cancers from the same cohort. RESULTS: We found increased S100A8 CN (≥ 4) in tumor epithelial cells in 20% of the tumors, increased S100A8 protein expression in 15%, and ≥ 10 infiltrating S100A8 + polymorphonuclear cells in 19%. Both increased S100A8 CN and protein expression in cancer cells were associated with high Ki67 status, high mitotic count and high histopathological grade. We observed no association between increased S100A8 CN and S100A8 protein expression, and only a weak association (p = 0.09) between increased CN and number of infiltrating S100A8 + immune cells. Only S100A8 protein expression in cancer cells was associated with significantly worse prognosis. CONCLUSIONS: Amplification of S100A8 does not appear to be associated with S100A8 protein expression in breast cancer. S100A8 protein expression in tumor epithelial cells identifies a subgroup of predominantly non-luminal tumors with a high mean age at diagnosis and significantly worse prognosis. Finally, S100A8 alone is not a sufficient marker to identify infiltrating immune cells linked to worse prognosis.

S100A9 is indispensable for survival of pneumococcal pneumonia in mice.

S100A8/A9 has important immunomodulatory roles in antibacterial defense, but its relevance in focal pneumonia caused by Streptococcus pneumoniae (S. pneumoniae) is understudied. We show that S100A9 was significantly increased in BAL fluids of patients with bacterial but not viral pneumonia and correlated with procalcitonin and sequential organ failure assessment scores. Mice deficient in S100A9 exhibited drastically elevated Zn2+ levels in lungs, which led to bacterial outgrowth and significantly reduced survival. In addition, reduced survival of S100A9 KO mice was characterized by excessive release of neutrophil elastase, which resulted in degradation of opsonophagocytically important collectins surfactant proteins A and D. All of these features were attenuated in S. pneumoniae-challenged chimeric WT→S100A9 KO mice. Similarly, therapy of S. pneumoniae-infected S100A9 KO mice with a mutant S100A8/A9 protein showing increased half-life significantly decreased lung bacterial loads and lung injury. Collectively, S100A9 controls central antibacterial immune mechanisms of the lung with essential relevance to survival of pneumococcal pneumonia. Moreover, S100A9 appears to be a promising biomarker to distinguish patients with bacterial from those with viral pneumonia. Trial registration: Clinical Trials register (DRKS00000620).

SCCA1/SERPINB3 suppresses antitumor immunity and blunts therapy-induced T cell responses via STAT-dependent chemokine production.

Patients with cancer who have high serum levels of squamous cell carcinoma antigen 1 (SCCA1, now referred to as SERPINB3) commonly experience treatment resistance and have a poor prognosis. Despite being a clinical biomarker, the modulation of SERPINB3 in tumor immunity is poorly understood. We found positive correlations of SERPINB3 with CXCL1, CXCL8 (CXCL8/9), S100A8, and S100A9 (S100A8/A9) myeloid cell infiltration through RNA-Seq analysis of human primary cervical tumors. Induction of SERPINB3 resulted in increased CXCL1/8 and S100A8/A9 expression, which promoted monocyte and myeloid-derived suppressor cell (MDSC) migration in vitro. In mouse models, Serpinb3a tumors showed increased MDSC and tumor-associated macrophage (TAM) infiltration, contributing to T cell inhibition, and this was further augmented upon radiation. Intratumoral knockdown (KD) of Serpinb3a resulted in tumor growth inhibition and reduced CXCL1 and S100A8/A expression and MDSC and M2 macrophage infiltration. These changes led to enhanced cytotoxic T cell function and sensitized tumors to radiotherapy (RT). We further revealed that SERPINB3 promoted STAT-dependent expression of chemokines, whereby inhibition of STAT activation by ruxolitinib or siRNA abrogated CXCL1/8 and S100A8/ A9 expression in SERPINB3 cells. Patients with elevated pretreatment SCCA levels and high phosphorylated STAT3 (p-STAT3) had increased intratumoral CD11b+ myeloid cells compared with patients with low SCCA levels and p-STAT3, who had improved overall survival after RT. These findings provide a preclinical rationale for targeting SERPINB3 in tumors to counteract immunosuppression and improve the response to RT.

A positive feedback cycle between the alarmin S100A8/A9 and NLRP3 inflammasome-GSDMD signalling reinforces the innate immune response in Candida albicans keratitis.

OBJECTIVE: Fungal keratitis is a severe sight-threatening ocular infection, without effective treatment strategies available now. Calprotectin S100A8/A9 has recently attracted great attention as a critical alarmin modulating the innate immune response against microbial challenges. However, the unique role of S100A8/A9 in fungal keratitis is poorly understood. METHODS: Experimental fungal keratitis was established in wild-type and gene knockout (TLR4-/- and GSDMD-/-) mice by infecting mouse corneas with Candida albicans. The degree of mouse cornea injuries was evaluated by clinical scoring. To interrogate the molecular mechanism in vitro, macrophage RAW264.7 cell line was challenged with Candida albicans or recombinant S100A8/A9 protein. Label-free quantitative proteomics, quantitative real-time PCR, Western blotting, and immunohistochemistry were conducted in this research. RESULTS: Herein, we characterized the proteome of mouse corneas infected with Candida albicans and found that S100A8/A9 was robustly expressed at the early stage of the disease. S100A8/A9 significantly enhanced disease progression by promoting NLRP3 inflammasome activation and Caspase-1 maturation, accompanied by increased accumulation of macrophages in infected corneas. In response to Candida albicans infection, toll-like receptor 4 (TLR4) sensed extracellular S100A8/A9 and acted as a bridge between S100A8/A9 and NLRP3 inflammasome activation in mouse corneas. Furthermore, the deletion of TLR4 resulted in noticeable improvement in fungal keratitis. Remarkably, NLRP3/GSDMD-mediated macrophage pyroptosis in turn facilitates S100A8/A9 secretion during Candida albicans keratitis, thus forming a positive feedback cycle that amplifies the proinflammatory response in corneas. CONCLUSIONS: The present study is the first to reveal the critical roles of the alarmin S100A8/A9 in the immunopathology of Candida albicans keratitis, highlighting a promising approach for therapeutic intervention in the future.

Expression of S100A8 protein on B cells is associated with disease activity in patients with systemic lupus erythematosus.

BACKGROUND: Systemic lupus erythematosus (SLE) is an intractable disease characterized by autoantibody production and autoreactive B and T cell proliferation. Although several studies have revealed multiple genetic and environmental associations, the underlying mechanisms remain unknown. METHODS: We performed proteomics and transcriptomics using liquid chromatography-mass spectrometry and DNA microarray, using peripheral blood B cells from patients with SLE, and healthy controls (HC). We explored molecules associated with the pathophysiology of SLE by flow cytometry and B cell stimulation assay. RESULTS: We identified for the first time that expression of both S100A8 protein and mRNA were markedly upregulated in SLE B cells. The results obtained using flow cytometry showed that S100A8 was highly expressed on the surface of B cells of patients with active SLE (MFI; HC 102.5 ± 5.97, stable SLE 111.4 ± 12.87, active SLE 586.9 ± 142.9), and S100A8 on the cell surface was decreased after treatment (MFI; pre-treat 1094.5 ± 355.38, post-treat 492.25 ± 247.39); therefore, it is suggested that S100A8 may be a marker for disease activity. The mRNA expression of S100A8 was particularly upregulated in memory B cells of SLE (56.68 fold higher than HC), suggesting that S100A8 may be mainly secreted by memory B cells in the pathogenesis of SLE. CONCLUSIONS: Our results imply that the S100A8 proteins secreted from memory B cells may stimulate granulocytes and monocytes through pattern recognition receptors, activate the innate immune system, and are involved in the pathogenesis of SLE.