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Background: Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is an acute, diffuse, inflammatory lung injury caused by various endogenous or exogenous factors. It is currently widely recognized that an excessive inflammatory response resulting from immune imbalance constitutes a crucial pathogenic mechanism in ALI/ARDS. SS31 is a novel mitochondria-targeted antioxidant peptide. This article validates the role of SS31 in lipopolysaccharide (LPS)-induced ALI. Methods: The study applied transcriptome sequencing, immunofluorescence, PCR, immunofluorescence and other methods to explore the mechanism of SS31 in LPS induced ALI. Results: Transcriptome sequencing results indicate that LPS-induced ALI is closely associated with immune regulatory processes, the Toll-like receptor pathway, and the NF-κB signaling pathway. The role of SS31 in acute lung injury is closely related to biological processes, such as immune regulation and cell death. This study demonstrated that SS31 can inhibit the expression of inflammatory factors IL-6, IL-1β, IL-18, and TNF-α, and reduce the expression of pyroptosis-related proteins NLRP3, and GSDMD-N. Further analysis revealed that S100A8 may be a key gene in the effect of SS31. LPS stimulation leads to increased expression of S100A8, while SS31 decreases its expression. Recombinant protein S100A8 can attenuate the inhibitory effect of SS31 on IL-1β, IL-18, NLRP3, and GSDMD-N. Conclusions: The research results indicate that SS31 may inhibit the activation of the NLRP3 inflammasome and suppress inflammatory responses by regulating S100A8, thereby alleviating LPS-induced ALI in mice; this process may be related to pyroptosis. [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: 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]

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: Severe burns can lead to systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS) due to inflammationimmunity dysregulation. This study aimed to identify key immune-related molecules and potential drugs for immune regulation in severe burn treatment. Method: Microarray datasets GSE77791 and GSE37069 were analyzed to identify immune-related differentially expressed genes (DEGs), enriched pathways and prognosis-related genes. The DGIdb database was used to identify potentially clinically relevant smallmolecular drugs for hub DEGs. HubDEGs were validated by total RNA from clinical blood samples through qPCR. The efficacy of drug candidates was tested in a severe burn mouse model. Pathologic staining was used to observe organ damage. Enzyme Linked Immunosorbent Assay (ELISA) was used to detect the serum IL-1β, IL-6, TNF-α and MCP-1 contents. Activation of the NF-kB inflammatory pathway was detected by western blotting. Transcriptome sequencing was used to observe inflammatory-immune responses in the lung. Results: A total of 113 immune-related DEGs were identified, and the presence of immune overactivation was confirmed in severe burns. S100A8 was not only significantly upregulated and identified to be prognosis-related among the hub DEGs but also exhibited an increasing trend in clinical blood samples. Methotrexate, which targets S100A8, as predicted by the DGIdb, significantly reduces transcription level of S100A8 and inflammatory cytokine content in blood, organ damage (lungs, liver, spleen, and kidneys) and mortality in severely burned mice when combined with fluid resuscitation. The inflammatory-immune response was suppressed in the lungs. Conclusion: S100A8 with high transcription level in blood is a potential biomarker for poor severe burn prognosis. It suggested that methotrexate has a potential application in severe burn immunotherapy. Besides, it should be emphasized that fluid resuscitation is necessary for the function of methotrexate. [ABSTRACT FROM AUTHOR]

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]

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]

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]

Cancer stem cells (CSCs) are closely associated with tumor initiation, metastasis, chemoresistance, and recurrence, which represent some of the primary obstacles to cancer treatment. Targeting CSCs has become an important therapeutic approach to cancer care. Secoemestrin C (Sec C) is a natural compound with strong anti-tumor activity and low toxicity. Here, we report that Sec C effectively inhibited colorectal CSCs and non-CSCs concurrently, mainly by inhibiting proliferation, self-renewal, metastasis, and drug resistance. Mechanistically, RNA-seq analysis showed that the pro-inflammation pathway of the IL17 axis was enriched, and its effector S100A8 was dramatically decreased in Sec C-treated cells, whose roles in the stemness of CSCs have not been fully clarified. We found that the overexpression of S100A8 hindered the anti-CSCs effect of Sec C, and S100A8 deficiency attenuated the stemness traits of CSCs to enhance the Sec C killing activity on them. Meanwhile, the p38 signal pathway, belonging to the IL17 downstream axis, can also mediate CSCs and counter with Sec C. Notably, we found that S100A8 upregulation increased the p38 protein level, and p38, in turn, promoted S100A8 expression. This indicated that p38 may have a mutual feedback loop with S100A8. Our study discovered that Sec C was a powerful anti-colorectal CSC agent, and that the positive feedback loop of p38–S100A8 mediated Sec C activity. This showed that Sec C could act as a promising clinical candidate in colorectal cancer treatment, and S100A8 could be a prospective drug target. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: S100A8, a calcium-binding protein belonging to the S100 family, is involved in immune responses and multiple tumor pathogens. Diffuse large Bcell lymphoma (DLBCL) is one of the most common types of B-cell lymphoma and remains incurable in 40% of patients. However, the role of S100A8 and its regulation of the immune response in DLBCL remain unclear. Methods: The differential expression of S100A8 was identified via the GEO and TCGA databases. The prognostic role of S100A8 in DLBCL was calculated using the Kaplan-Meier curve. The function enrichment of differentially expressed genes (DEGs) was explored through GO, KEGG, GSEA, and PPI analysis. In our cohort, the expression of S100A8 was verified. Meanwhile, the biological function of S100A8 was applied after the inhibition of S100A8 in an in vitro experiment. The association between S100A8 and immune cell infiltration and treatment response in DLBCL was analyzed. Results: S100A8 was significantly overexpressed and related to a poor prognosis in DLBCL patients. Function enrichment analysis revealed that DEGs were mainly enriched in the IL-17 signaling pathway. Our cohort also verified this point. In vitro experiments suggested that inhibition of S100A8 should promote cell apoptosis and suppress tumor growth. Single-cell RNA sequence analysis indicated that S100A8 might be associated with features of the tumor microenvironment (TME), and immune infiltration analyses discovered that S100A8 expression was involved in TME. In terms of drug screening, we predicted that many drugs were associated with preferable sensitivity. Conclusion: Elevated S100A8 expression is associated with a poor prognosis and immune infiltration in DLBCL. Inhibition of S100A8 could promote cell apoptosis and suppress tumor growth. Meanwhile, S100A8 has the potential to be a promising immunotherapeutic target for patients with DLBCL. [ABSTRACT FROM AUTHOR]

Background: We previously found that the respiratory epithelial cells could eliminate the invaded group A streptococcus (GAS) through autophagy induced by binding a fibronectin (Fn) binding protein (FnBp) expressed on the surface of GAS to plasma protein Fn and its receptor integrin α5β1 of epithelial cells. Is autophagy initiated by FnBp+ bacteria via FnBp-Fn-Integrin α5β1 axis a common event in respiratory epithelial cells? Methods: We chose Staphylococcus aureus (S. aureus/S. a) and Listeria monocytogenes (L. monocytogenes/L. m) as representatives of extracellular and intracellular FnBp+ bacteria, respectively. The FnBp of them was purified and the protein function was confirmed by western blot, viable bacteria count, confocal and pull-down. The key molecule downstream of the action axis was detected by IP, mass spectrometry and bio-informatics analysis. Results: We found that different FnBp from both S. aureus and L. monocytogenes could initiate autophagy through FnBp-Fn-integrin α5β1 axis and this could be considered a universal event, by which host tries to remove invading bacteria from epithelial cells. Importantly, we firstly reported that S100A8, as a key molecule downstream of integrin β1 chain, is highly expressed upon activation of integrin α5β1, which in turn up-regulates autophagy. Conclusions: Various FnBp from FnBp+ bacteria have the ability to initiate autophagy via FnBp-Fn-Integrin α5β1 axis to promote the removal of invading bacteria from epithelial cells in the presence of fewer invaders. S100A8 is a key molecule downstream of Integrin α5β1 in this autophagy pathway. [ABSTRACT FROM AUTHOR]

Background: The association between S100 calcium-binding protein A8 (S100A8) and angiogenesis has been reported in previous reports. This study focuses on the roles of S100A8 in the angiogenesis of human dermal microvascular endothelial cells (HDMECs) and in cutaneous wound healing in mice. Methods: Candidate genes related to angiogenesis activity were screened using a GSE83582 dataset. The overexpression DNA plasmid of S100A8 was transfected into HDMECs to analyze its effect on cell proliferation, migration, and angiogenesis. Full-thickness skin wounds were induced on mice, followed by adenovirus treatments to analyze the function of gene alteration in wound healing and pathological changes. The upstream regulator of S100A8 was predicted by bioinformatics analysis and verified by luciferase and immunoprecipitation assays. The role of the forkhead box A1 (FOXA1)-S100A8 interaction in p38 MAPK activation and angiogenesis were validated by rescue experiments. Results: S100A8 was identified as a gene significantly correlated with angiogenesis. The S100A8 upregulation promoted the proliferation, migration, and angiogenesis of HDMECs, and it promoted p38 MAPK phosphorylation. Treatment of SB203580, a p38 MAPK inhibitor, blocked the promoting effect of S100A8. FOXA1 was identified as an upstream factor of S100A8 promoting its transcription. FOXA1 overexpression in HDMECs increased p38 MAPK phosphorylation and enhanced the activity of cells, which were blocked by the S100A8 inhibition. Similar results were reproduced in vivo where FOXA1 overexpression accelerated whereas the S100A8 knockdown retarded the cutaneous wound healing in mice. Conclusion: FOXA1 mediates the phosphorylation of p38 MAPK through transcription activation of S100A8, thereby inducing angiogenesis and promoting cutaneous wound healing. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Major depressive disorder (MDD) affects more than 350 million people worldwide, and there is currently no laboratory test to diagnose it. This pilot study aimed to identify potential biomarkers in peripheral blood mononuclear cells (PBMCs) from MDD patients. Methods: We used tandem mass tagging coupled to synchronous precursor selection (mass spectrometry) to obtain the differential proteomic profile from a pool of PBMCs from MDD patients and healthy subjects, and quantitative PCR to assess gene expression of differentially expressed proteins (DEPs) of our interest. Results: We identified 247 proteins, of which 133 had a fold change ≥ 2.0 compared to healthy volunteers. Using pathway enrichment analysis, we found that some processes, such as platelet degranulation, coagulation, and the inflammatory response, are perturbed in MDD patients. The gene-disease association analysis showed that molecular alterations in PBMCs from MDD patients are associated with cerebral ischemia, vascular disease, thrombosis, acute coronary syndrome, and myocardial ischemia, in addition to other conditions such as inflammation and diabetic retinopathy. Conclusions: We confirmed by qRT-PCR that S100A8 is upregulated in PBMCs from MDD patients and thus could be an emerging biomarker of this disorder. This report lays the groundwork for future studies in a broader and more diverse population and contributes to a deeper characterization of MDD. [ABSTRACT FROM AUTHOR]

Immunogenic cell death (ICD) is known for releasing damage-associated molecular patterns (DAMPs) from tumor cells. We aimed to find ICD signals by assessing the variation of plasmatic DAMPs (HMGB1, S100A8) before-after standard of care (SoC) systemic treatment in patients with advanced solid tumors. Patients scheduled to start a new line of systemic treatment were included. Plasmatic concentrations of HMGB1 and S100A8 were measured (ng/mL) before and after three months of treatment. Fifty-two patients were included. Forty-four patients (85%) had metastases, and 8 (15%) were treated for stage III tumors. The most frequent tumor sites were colorectal (35%) and lung (25%). Forty-two patients (81%) received this treatment in the first-line setting. Thirty-six patients (69%) were treated chemotherapy (CT) alone, ten (19%) CT plus targeted therapy, two (3.8%) carboplatin-pemetrexed-pembrolizumab, three (5.8%) pembrolizumab alone and one (1.9%) cetuximab alone. Median plasmatic concentration of S100A8 was significantly higher before than after treatment in the whole population (3.78 vs. 2.91 ng/mL; p = 0.011) and more markedly in the subgroups of patients who experienced RECIST-assessed tumor response (5.70 vs. 2.63 ng/mL; p = 0.002). Median plasmatic concentration of HMGB1was not significantly different before and after treatment (10.23 vs. 11.85 ng/mL; p = 0.382) and did not differ depending on tumor response. Median PFS was not significantly different between patients whose plasma HMBG1 concentration decreased or increased (8.0 vs. 10.6 months; p = 0.29) after treatment. Median PFS was significantly longer in those patients in whom the plasma concentration of S100A8 decreased after treatment (12 vs. 4.7 months; p < 0.001). Median OS was not significantly different between patients whose plasma HMBG1 concentration decreased or increased (13.1 vs. 14.7 months; p = 0.46) after treatment. Median OS was significantly longer in those patients in whom the plasma concentration of S100A8 decreased after treatment (16.7 vs. 9.0 months; p < 0.001). Signals of ICD were not observed. S100A8 behaves as an inflammatory marker with decreased concentration after treatment, mostly in RECIST-responders. PFS and OS were significantly prolonged in those patients who experienced a decrease of S100A8 compared with those patients who experienced increase of plasma S100A8 at three months. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Matrix metalloproteinases (MMPs) and their major source, endometrial stromal cells (ESCs), play important roles in menstruation. However, other mechanisms in endometrial shedding may be unexplored. This study focused on four proteins: S100A8 and S100A9 (alarmins) are binding partners and induce MMPs, MMP-3 cycle-dependently plays a key role in the proteolytic cascade, and CD147, which has S100A9 as its ligand, induces MMPs. Immunostaining for these proteins was performed on 118 resected specimens. The percentage and location of each positive reaction in ESCs were measured and compared using Image J. The influence of leukocytes on S100A8 or S100A9 immunopositivity was also examined. From the premenstrual phase, S100A8 and MMP-3 began to have overlapping expressions in ESCs of the superficial layer, and ESC detachment was found within these sites. S100A9 was expressed from the late secretory phase and CD147 already from earlier. Later, the expression sites of S100A9 and CD147 included those of S100A8. Before menstruation, S100A8 or S100A9 expression was not affected by leukocytes. These results suggest that the local formation of S100A8/S100A9 complex, which occurs specifically in ESCs upon progesterone withdrawal, induces the local expression of MMP-3 and serves as a switch to the lysis phase. [ABSTRACT FROM AUTHOR]

S100A8 and S100A9 are multifunctional proteins that can initiate various signaling pathways and modulate cell function both inside and outside immune cells, depending on their receptors, mediators, and molecular environment. They have been reported as dysregulated genes and proteins in a wide range of cancers, including hematologic malignancies, from diagnosis to response to therapy. The role of S100A8 and S100A9 in hematologic malignancies is highlighted due to their ability to work together or as antagonists to modify cell phenotype, including viability, differentiation, chemosensitivity, trafficking, and transcription strategies, which can lead to an oncogenic phase or reduced symptoms. In this review article, we discuss the critical roles of S100A8, S100A9, and calprotectin (heterodimer or heterotetramer forms of S100A8 and S100A9) in forming and promoting the malignant bone marrow microenvironment. We also focus on their potential roles as biomarkers and therapeutic targets in various stages of hematologic malignancies from diagnosis to treatment. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Cancer cachexia, occurring in ~ 80% pancreatic cancer (PC) patients overall, is a paraneoplastic syndrome mediated by cancer-induced systemic inflammation and characterized by weight loss and skeletal muscle wasting. Identifying clinically relevant PC-derived pro-inflammatory factors with cachexigenic potential may provide novel insights and therapeutic strategies. Methods: Pro-inflammatory factors with cachexigenic potential in PC were identified by bioinformatic analysis. The abilities of selected candidate factors in inducing skeletal muscle atrophy were investigated. Expression levels of candidate factors in tumors and sera was compared between PC patients with and without cachexia. Associations between serum levels of the candidates and weight loss were assessed in PC patients. Results: S100A8, S100A9, and S100A8/A9 were identified and shown to induce C2C12 myotube atrophy. Tumors of PC patients with cachexia had markedly elevated expression of S100A8 (P = 0.003) and S100A9 (P < 0.001). PC patients with cachexia had significantly higher serum levels of S100A8, S100A9 and S100A8/A9. Serum levels of these factors positively correlated with percentage of weight loss [correlation coefficient: S100A8: 0.33 (P < 0.001); S100A9: 0.30 (P < 0.001); S100A8/A9: 0.24 (P = 0.004)] and independently predicted the occurrence of cachexia [adjusted odds ratio (95% confidence interval) per 1ng/ml increase: S100A8 1.11 (1.02–1.21), P = 0.014; S100A9 1.10 (1.04–1.16), P = 0.001; per 1 µg/ml increase: S100A8/A9 1.04 (1.01–1.06), P = 0.009]. Conclusions: Atrophic effects of S100A8, S100A9, and S100A8/A9 indicated them as potential pathogenic factors of PC-induced cachexia. In addition, the correlation with the degree of weight loss and prediction of cachexia in PC patients implicated their potential utility in the diagnosis of PC-induced cachexia. [ABSTRACT FROM AUTHOR]

Objectives: S100A8 is highly expressed in several inflammatory and oncological conditions. To address the current lack of a reliable and sensitive detection method for S100A8, we generated a monoclonal antibody with a high binding affinity to human S100A8 to enable early disease diagnosis. Results: A soluble recombinant S100A8 protein with a high yield and purity was produced using Escherichia coli. Next, mice were immunized with recombinant S100A8 to obtain anti-human S100A8 monoclonal antibodies using hybridoma technology. Lastly, the high binding activity of the antibody was confirmed and its sequence was identified. Conclusions: This method, including the production of antigens and antibodies, will be useful for the generation of hybridoma cell lines that produce anti-S100A8 monoclonal antibodies. Moreover, the sequence information of the antibody can be used to develop a recombinant antibody for use in various research and clinical applications. [ABSTRACT FROM AUTHOR]

Numerous pathogenic CALR exon 9 mutations have been identified in myeloproliferative neoplasms (MPN), with type 1 (52bp deletion; CALRDEL) and type 2 (5bp insertion; CALRINS) being the most prevalent. Despite the universal pathobiology of MPN driven by various CALR mutants, it is unclear why different CALR mutations result in diverse clinical phenotypes. Through RNA sequencing followed by validation at the protein and mRNA levels, we found that S100A8 was specifically enriched in CALRDEL but not in CALRINS MPN-model cells. The expression of S100a8 could be regulated by STAT3 based on luciferase reporter assay complemented with inhibitor treatment. Pyrosequencing demonstrated relative hypomethylation in two CpG sites within the potential pSTAT3-targeting S100a8 promoter region in CALRDEL cells as compared to CALRINS cells, suggesting that distinct epigenetic alteration could factor into the divergent S100A8 levels in these cells. The functional analysis confirmed that S100A8 non-redundantly contributed to accelerated cellular proliferation and reduced apoptosis in CALRDEL cells. Clinical validation showed significantly enhanced S100A8 expression in CALRDEL-mutated MPN patients compared to CALRINS-mutated cases, and thrombocytosis was less prominent in those with S100A8 upregulation. This study provides indispensable insights into how different CALR mutations discrepantly drive the expression of specific genes that contributes to unique phenotypes in MPN. [ABSTRACT FROM AUTHOR]

Human papillomavirus (HPV) infection has recently been linked to a subset of cancers affecting the oral cavity. However, the molecular mechanisms underlying HPV-driven oral squamous cell carcinoma (OSCC) onset and progression are poorly understood. Methods: We performed MS-based proteomics profiling based on HPV status in OSCC in young patients, following biological characterization and cell assays to explore the proteome functional landscape. Results: Thirty-nine proteins are differentially abundant between HPV (+) and HPV (−) OSCC. Among them, COPS3, DYHC1, and S100A8 are unfavorable for tumor recurrence and survival, in contrast to A2M and Serpine1, low levels of which show an association with better DFS. Remarkably, S100A8 is considered an independent prognostic factor for lower survival rates, and at high levels, it alters tumor-associated immune profiling, showing a lower proportion of M1 macrophages and dendritic cells. HPV (+) OSCC also displayed the pathogen-associated patterns receptor that, when activated, triggered the S100A8 and NFκB inflammatory responses. Conclusion: HPV (+) OSCC has a peculiar microenvironment pattern distinctive from HPV (−), involving the expression of pathogen-associated pattern receptors, S100A8 overexpression, and NFκB activation and responses, which has important consequences in prognosis and may guide therapeutic decisions. [ABSTRACT FROM AUTHOR]

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Background: Pediatric acute appendicitis (AA) is a challenging pathology to diagnose. In the last decades, multiple biomarkers have been evaluated in different human biological samples to improve diagnostic performance. This study aimed to examine the diagnostic performance of serum, fecal and urinary calprotectin as well as the role of the APPY-1 biomarker panel in pediatric acute appendicitis. Methods: We conducted a systematic review of the literature that involved an extensive search in the main databases of medical bibliography (Medline, PubMed, Web of Science and SciELO). Two independent reviewers selected the relevant articles based on the previously defined inclusion and exclusion criteria. Methodological quality of the selected article was rated using the QUADAS2 index. Data extraction was performed by two independent reviewers. A synthesis of the results, a standardization of the metrics and two random-effect meta-analyses, one for serum calprotectin and one for APPY-1, were performed. Results: The research resulted in 173 articles. Thirty-eight duplicates were removed. Among the remaining 135 articles, we excluded 125 following the inclusion and exclusion criteria, resulting in the 10 studies included in this review. This systematic review included data from of 3901 participants (1276 patients with confirmed diagnosis of AA and 2625 controls). The age of the participants ranged from 0 to 21 years. Four of the studies compared serum calprotectin values and reported significant differences between groups, but inconsistent results regarding cutoff points, sensitivity and specificity. Two publications compared urinary values of calprotectin and presented inconsistent results regarding sensitivity and specificity as well. One publication evaluated the diagnostic performance of fecal calprotectin, but it did not provide data on measured values. Four studies evaluated the diagnostic performance of APPY-1 test in pediatric acute appendicitis. The calculated pooled sensitivity and specificity of those studies were 97.37 (95% CI 95.60–98.44) and 36.74 (95% CI 32.28–41.44), respectively, and the calculated pooled NLR, 0.0714 (95% CI 0.041–0.115). Conclusion: Serum calprotectin has limited diagnostic yield in pediatric acute appendicitis. Its performance seems to increase with the hours of clinical evolution and in advanced AA, although the evidence is limited. There is not enough evidence on the usefulness of urinary or fecal calprotectin in the diagnosis of pediatric acute appendicitis. On the other hand, the APPY-1 is a reliable test to exclude the diagnosis of AA in patients at low or moderate risk according to PAS and Alvarado Score. [ABSTRACT FROM AUTHOR]

Intense itching significantly reduces the quality of life, and atopic dermatitis is associated with psychiatric conditions, such as anxiety and depression. Psoriasis, another inflammatory skin disease, is often complicated by psychiatric symptoms, including depression; however, the pathogenesis of these mediating factors is poorly understood. This study used a spontaneous dermatitis mouse model (KCASP1Tg) and evaluated the psychiatric symptoms. We also used Janus kinase (JAK) inhibitors to manage the behaviors. Gene expression analysis and RT-PCR of the cerebral cortex of KCASP1Tg and wild-type (WT) mice were performed to examine differences in mRNA expression. KCASP1Tg mice had lower activity, higher anxiety-like behavior, and abnormal behavior. The mRNA expression of S100a8 and Lipocalin 2 (Lcn2) in the brain regions was higher in KCASP1Tg mice. Furthermore, IL-1β stimulation increased Lcn2 mRNA expression in astrocyte cultures. KCASP1Tg mice had predominantly elevated plasma Lcn2 compared to WT mice, which improved with JAK inhibition, but behavioral abnormalities in KCASP1Tg mice did not improve, despite JAK inhibition. In summary, our data revealed that Lcn2 is closely associated with anxiety symptoms, but the anxiety and depression symptoms caused by chronic skin inflammation may be irreversible. This study demonstrated that active control of skin inflammation is essential for preventing anxiety. [ABSTRACT FROM AUTHOR]

Background: Glycyrrhizic acid (GA), a saponin compound often used as a flavoring agent, can elicit anti-inflammatory and anti-tumor effects, and alleviate aging. However, the specific mechanism by which GA alters immune cell populations to produce these beneficial effects is currently unclear. Results: In this study, we systematically analyzed single-cell sequencing data of peripheral blood mononuclear cells from young mice, aged mice, and GA-treated aged mice. Our in vivo results show that GA reduced senescence-induced increases in macrophages and neutrophils, and increased numbers of lymphoid lineage subpopulations specifically reduced by senescence. In vitro, GA significantly promoted differentiation of Lin−CD117+ hematopoietic stem cells toward lymphoid lineages, especially CD8+ T cells. Moreover, GA inhibited differentiation of CD4+ T cells and myeloid (CD11b+) cells by binding to S100 calcium-binding protein 8 (S100A8) protein. Overexpression of S100A8 in Lin− CD117+ hematopoietic stem cells enhanced cognition in aged mice and the immune reconstitution of severely immunodeficient B-NDG (NOD.CB17-Prkdcscid/l2rgtm1/Bcgen) mice. Conclusions: Collectively, GA exerts anti-aging effects by binding to S100A8 to remodel the immune system of aged mice. [ABSTRACT FROM AUTHOR]

Myeloid‐derived suppressor cells (MDSCs) have been known to play a pivotal role in the induction of immune tolerance, which limits the benefits of immune checkpoint inhibitors (ICIs). Recent studies revealed that several chemotherapeutic agents decreased tumor‐infiltrating MDSCs. Therefore, combination therapy with cytotoxic chemotherapeutic agents and ICIs was approved for first‐line treatment for lung cancer. However, the impact of chemotherapeutic agents on MDSCs and an optimal partner of ICIs has not been fully investigated in thoracic tumors, including lung cancer and malignant pleural mesothelioma. In the present study, we found that treatment with 5‐FU and its oral formulation, S‐1, suppressed tumor progression and inhibited the accumulation of MDSCs in thoracic tumor‐bearing mice. Tumor‐infiltrating T cells and dendritic cells were significantly expanded in S‐1‐treated mice. 5‐FU suppressed the ability of tumor cells to recruit MDSCs, while it did not suppress the survival and differentiation of mouse MDSCs in vitro. We also revealed that 5‐FU or S‐1 significantly downregulated the expression of tumor‐derived Bv8 and S100A8. The knockdown of Bv8 or S100A8 in tumor cells suppressed tumor growth and MDSC recruitment in vivo. Furthermore, in comparison with pemetrexed, administration of S‐1 improved the synergistic therapeutic efficacy of anti‐PD‐1 antibodies with or without carboplatin. Our findings revealed a novel mechanism wherein S‐1 primed a favorable tumor microenvironment to provide the rationale for combination therapy with S‐1 and ICIs as the optimal therapy for thoracic cancer. [ABSTRACT FROM AUTHOR]

Uremic cardiomyopathy (UCM) is a characteristic cardiac pathology that is commonly found in patients with chronic kidney disease. This study dissected the mechanism of SPI1 in myocardial fibrosis and inflammation induced by UCM through S100A8/A9. An UCM rat model was established, followed by qRT-PCR and western blot analyses of SPI1 and S100A8/A9 expression in myocardial tissues. After alterations of SPI1 and S100A8/A9 expression in UCM rats, the blood specimens were harvested from the cardiac apex of rats. The levels of creatine phosphokinase-MB (CK-MB), blood creatinine, blood urea nitrogen (BUN), and inflammatory cytokines (interleukin [IL]-6, IL-1β, and tumor necrosis factor-α [TNF-α]) were examined in the collected blood. Collagen fibrosis was assessed by Masson staining. The expression of fibrosis markers [transforming growth factor (TGF)-β1, α-smooth muscle actin (SMA), Collagen 4a1, and Fibronectin], IL-6, IL-1β, and TNF-α was measured in myocardial tissues. Chromatin immunoprecipitation and dual-luciferase reporter gene assays were conducted to test the binding relationship between SPI1 and S100A8/A9. S100A8/A9 and SPI1 were highly expressed in the myocardial tissues of UCM rats. Mechanistically, SPI1 bound to the promoter of S100A8/A9 to facilitate S100A8/A9 transcription. S100A8/A9 or SPI1 knockdown reduced myocardial fibrosis and inflammation and the levels of CK-MB, blood creatinine, and BUN, as well as the expression of TGF-β1, α-SMA, Collagen 4a1, Fibronectin, IL-6, TNF-α, and IL-1β in UCM rats. SPI1 knockdown diminished S100A8/A9 transcription, thus suppressing myocardial fibrosis and inflammation caused by UCM. [ABSTRACT FROM AUTHOR]

NLRP3 inflammasome-dependent pyroptosis has been implicated in liver fibrosis progression. However, the definite intrahepatic cell types that undergo pyroptosis and the underlying mechanism as well as the clinical importance remain unclear. Here, augmented levels of pyroptosis-related indicators GSDMD, IL-1β, and IL-18 were verified in both liver fibrosis patients and CCl4-induced fibrotic mouse model. Confocal imaging of NLRP3 with albumin, F4/80 or α-SMA revealed that enhanced NLRP3 was mainly localized to kupffer cells (KCs), indicating that KCs are major cell types that undergo pyroptosis. Targeting pyroptosis by inhibitor MCC950 attenuated the severity and ameliorated liver function in fibrosis models. In addition, elevated S100A8 in liver fibrosis patients was correlated with pyroptosis-related indicators. S100A8 stimulated pyroptotic death of macrophages, which resulted in activation of human hepatic stellate cell line LX-2 cells and increased collagen deposition. Mechanistically, S100A8 activated TLR4/NF-κB signaling and upregulated its target genes NLRP3, pro-IL-1β, and pro-IL-18 expression, and induced reactive oxygen (ROS) abundance to activate NLRP3 inflammasome, finally leading to pyroptotic cell death in macrophages. More importantly, circulating GSDMD had the optimal predicting value for liver fibrosis progression. In conclusion, S100A8-mediated NLRP3 inflammasome-dependent pyroptosis by TLR4/NF-κB activation and ROS production in macrophages facilitates liver fibrosis progression. The identified GSDMD has the potential to be a biomarker for liver fibrosis evaluation. [ABSTRACT FROM AUTHOR]

Currently, no established biomarkers are recommended for the routine diagnosis of penile carcinoma (PeCa). The rising incidence of this human papillomavirus (HPV)–related cancer entity highlights the need for promising candidates. The Calprotectin subunits S100A8 and S100A9 mark myeloidderived suppressor cells in other HPV-related entities while their receptor CD147 was discussed to identify patients with PeCa at a higher risk for poor prognoses and treatment failure. We thus examined their expression using immunohistochemistry staining of PeCa specimens from 74 patients on tissue microarrays of the tumor center, the invasion front, and lymph node metastases. Notably, whereas the tumor center was significantly more intensively stained than the invasion front, lymph node metastases were thoroughly positive for both S100 subunits. An HPV-positive status combined with an S100A8+S100A9+ profile was related with an elevated risk for metastases. We observed several PeCa specimens with S100A8+S100A9+- infiltrating immune cells overlapping with CD15 marking neutrophils. The S100A8+S100A9+CD15+ profile was associated with dedifferentiated and metastasizing PeCa, predominantly of HPV-associated subtype. These data suggest a contribution of neutrophil-derived suppressor cells to the progression of HPV-driven penile carcinogenesis. CD147 was elevated, expressed in PeCa specimens, prominently at the tumor center and in HPVpositive PeCa cell lines. CD147+HPV+ PeCa specimens were with the higher-frequency metastasizing cancers. Moreover, an elevated expression of CD147 of HPV-positive PeCa cell lines correlated negatively with the susceptibility to IgA-based neutrophil-mediated tumor cell killing. Finally, stratifying patients regarding their HPV/S100A8/S100A9/CD15/CD147 profile may help identify patients with progressing cancer and tailor immunotherapeutic treatment strategies. [ABSTRACT FROM AUTHOR]

Background: Lymphocytic leukemia (LL) is a primary malignant tumor of hematopoietic tissue, which seriously affects the health of children and the elderly. The study aims to establish a new detection method for screening acute/chronic LL using time-resolved fluorescence immunoassay (TRFIA) via quantitative detection of S100 calcium binding protein A8 (S100A8) and leucine-rich alpha-2-glycoprotein 1 (LRG1) in serum. Methods: Here a sandwich TRFIA was optimized and established: Anti-S100A8/LRG1 caputre antibodies immobilized on 96-well plates captured S100A8/LRG1, and then banded together with the anti-S100A8/LRG1 detection antibodies labeled with Europium(III) (Eu3+)/samarium(III) (Sm3+) chelates. Finally time resolved fluorometry measured the fluorescence intensity. Results: The sensitivity of S100A8 was 1.15 ng/mL(LogY = 3.4027 + 0.4091 × LogX, R2 = 0.9828, P < 0.001, dynamic range: 2.1–10,000 ng/mL), and 3.2 ng/mL for LRG1 (LogY = 3.3009 + 0.4082 × LogX, R2 = 0.9748, P < 0.001, dynamic range: 4.0–10,000 ng/mL). The intra-assay and inter-assay CVs were low, ranging from 5.75% to 8.23% for S100A8 and 5.30% to 9.45% for LRG1 with high specificity and affinity in serum samples. Bland–Altman plots indicated TRFIA and ELISA kits have good agreement in clinical serum samples. Additionally, the cutoff values for S100A8 and LRG1 were 1849.18 ng/mL and 588.08 ng/mL, respectively. Conclusion: The present TRFIA method could be used for the quantitative detection of S100A8 and LRG1 in serum, and it has high sensitivity, accuracy and specificity. Clinically, this TRFIA method could be suitable for screening of LL via the quantitative detection of S100A8 and LRG1. [ABSTRACT FROM AUTHOR]

Background: Aging is a risk factor for several pathologies as Alzheimer's disease (AD). Great interest exists, therefore, in discovering diagnostic biomarkers and indicators discriminating biological aging and health status. To this aim, omic investigations of biological matrices, as saliva, whose sampling is easy and non-invasive, offer great potential.Objective: Investigate the salivary proteome through a statistical comparison of the proteomic data by several approaches to highlight quali-/quantitative variations associated specifically either to aging or to AD occurrence, and, thus, able to classify the subjects.Methods: Salivary proteomic data of healthy controls under-70 (adults) and over-70 (elderly) years old, and over-70 AD patients, obtained by liquid chromatography/mass spectrometry, were analyzed by multiple Mann-Whitney test, Kendall correlation, and Random-Forest (RF) analysis.Results: Almost all the investigated proteins/peptides significantly decreased in relation to aging in elderly subjects, with or without AD, in comparison with adults. AD subjects exhibited the highest levels of α-defensins, thymosin β4, cystatin B, S100A8 and A9. Correlation tests also highlighted age/disease associated differences. RF analysis individuated quali-/quantitative variations in 20 components, as oxidized S100A8 and S100A9, α-defensin 3, P-B peptide, able to classify with great accuracy the subjects into the three groups.Conclusion: The findings demonstrated a strong change of the salivary protein profile in relation to the aging. Potential biomarkers candidates of AD were individuated in peptides/proteins involved in antimicrobial defense, innate immune system, inflammation, and in oxidative stress. RF analysis revealed the feasibility of the salivary proteome to discriminate groups of subjects based on age and health status. [ABSTRACT FROM AUTHOR]

Acute lymphoblastic leukemia (ALL) is the most common malignancy in children and relapsed B-ALL is the leading cause of mortality in children with leukemia due to a lack of response to treatment. S100A8 is a low molecular weight calcium-binding intracellular protein that is expressed in certain cells, and its increased expression is seen in most tumors as well as in relapsed childhood B-ALL cases. The present study indicates the important role of S100A8 in improving viability and resistance to chemotherapy in relapsed B-ALL lymphoblasts. S100A8 levels were compared in B-ALL and relapsed B-ALL lymphoblasts that were sensitive and resistant to Vincristine, respectively. S100A8 was inhibited in the lymphoblasts of two patients by antisense locked nucleic acid (LNA) GapmeRs and the decreased expression of S100A8 was evaluated using quantitative real-time PCR and ELISA. Then, the S100A8 antisense LNA GapmeRs-transfected cells were treated with Vincristine and the expression levels of S100A8 mRNA and S100A8 protein were re-determined. At all of these stages, cell viability and LC50 were assessed by MTT assay. The results showed that S100A8 levels in relapsed B-ALL lymphoblasts were significantly higher than B-ALL lymphoblasts. Moreover, the increase in S100A8 expression was proportionate to the increase in Vincristine resistance in these cells. The S100A8 knockdown procedure using antisense LNA GapmeRs decreased the cell viability and increased vincristine sensitivity in lymphoblasts of two patients, and it also increased the sensitivity to chemotherapy in relapsed B-ALL lymphoblasts. According to the findings of the present study, S100A8 is effective in developing lymphoblast resistance to chemotherapy, and its enhanced expression may contribute to shifting B-ALL into the relapse phase of the illness. As a result, S100A8 may be a valuable target for managing and improving relapses B-ALL. [ABSTRACT FROM AUTHOR]

Monocytes and macrophages are central players of the innate immune response and play a pivotal role in the regulation of inflammation. Thereby, they actively participate in all phases of the immune response, from initiating inflammation and triggering the adaptive immune response, through to the clearance of cell debris and resolution of inflammation. In this review, we described the mechanisms of monocyte and macrophage adaptation to rapidly changing microenvironmental conditions and discussed different forms of macrophage polarization depending on the environmental cues or pathophysiological condition. Therefore, special focus was placed on the tight regulation of the pro- and anti-inflammatory immune response, and the diverse functions of S100A8/S100A9 proteins and the scavenger receptor CD163 were highlighted, respectively. We paid special attention to the function of pro- and anti-inflammatory macrophages under pathological conditions. [ABSTRACT FROM AUTHOR]

Myocardial infarction (MI), a type of coronary heart disease, has had a significantly increased incidence in recent years. The balance of cardiomyocyte apoptosis and autophagy after MI is one of the main determinants of patient prognosis. Both affect myocardial fibrosis and ventricular remodeling and regulate cell survival. However, there are few studies on the regulation mechanism of cardiomyocyte autophagy and apoptosis in the early stage after MI. In this study, based on analyzing the scRNA-seq and mRNA-seq data of mice in the early stage of MI, we found that the expression of S100a8 and S100a9 increased first and then decreased in the early stage of MI, and their expression level changed with the number of neutrophils. Further, through the functional enrichment analysis of the differentially expressed genes, we found that S100a8 and S100a9 were simultaneously associated with autophagy and apoptosis and could regulate autophagy and apoptosis of cardiomyocytes through MAPK or PI3K-AKT signaling pathways. This study provides valuable insights for clarifying the pathogenesis of early stage MI and improving its early treatment. [ABSTRACT FROM AUTHOR]

Lung cancer is the leading cause of cancer-related death worldwide. Increasing evidence indicates a critical role for chronic inflammation in lung carcinogenesis. S100A8 is a protein with reported pro- and anti-inflammatory functions. It is highly expressed in myeloid-derived suppressor cells (MDSC) that accumulate in the tumor microenvironment and abrogate effective anti-cancer immune responses. Mechanisms of MDSC-mediated immunosuppression include production of reactive oxygen species and nitric oxide, and depletion of L-arginine required for T cell function. Although S100A8 is expressed in MDSC, its role in the lung tumor microenvironment is largely unknown. To address this, mouse recombinant S100A8 was repeatedly administered intranasally to mice bearing orthotopic lung cancers. S100A8 treatment prolonged survival from 19 days to 28 days (p < 0.001). At midpoint of survival, whole lungs and bronchoalveolar lavage fluid (BALF) were collected and relevant genes/proteins measured. We found that S100A8 significantly lowered expression of cytokine genes and proteins that promote expansion and activation of MDSC in lungs and BALF from cancer-bearing mice. Moreover, S100A8 enhanced activities of antioxidant enzymes and suppressed production of nitrite to create a lung microenvironment conducive to cytotoxic lymphocyte expansion and function. In support of this, we found decreased MDSC numbers, and increased numbers of CD4+ T cells and natural killer T (NK-T) cells in lungs from cancer-bearing mice treated with S100A8. Ex-vivo treatment of splenocytes with S100A8 protein activated NK cells. Our results indicate that treatment with S100A8 may favourably modify the lung microenvironment to promote an effective immune response in lungs, thereby representing a new strategy that could complement current immunotherapies in lung cancer. [ABSTRACT FROM AUTHOR]

Introduction: Lupus nephritis (LN) is a major risk factor of morbidity and mortality. Glomerular injury is associated with different pathogeneses and clinical presentations in LN patients. However, the molecular mechanisms involved are not well understood. This study aimed to explore the molecular characteristics and mechanisms of this disease using bioinformatics analysis. Methods: To characterize glomeruli in LN, microarray datasets GSE113342 and GSE32591 were downloaded from the Gene Expression Omnibus database and analyzed to determine the differentially expressed genes (DEGs) between LN glomeruli and normal glomeruli. Functional enrichment analyses and protein–protein interaction network analyses were then performed. Module analysis was performed using the Search Tool for the Retrieval of Interacting Genes/Proteins and Cytoscape software. Immunofluorescence staining was performed to identify the glomerular expression of S100A8 in various International Society of Nephrology/Renal Pathology Society (ISN/RPS) class LN patients. The image of each glomerulus was acquired using a digital imaging system, and the green fluorescence intensity was quantified using Image-Pro Plus software. Results: A total of 13 DEGs, consisting of 12 downregulated genes and one upregulated gene (S100A8), were identified in the microarray datasets. The functions and pathways associated with the DEGs mainly include inflammatory response, innate immune response, neutrophil chemotaxis, leukocyte migration, cell adhesion, cell–cell signaling, and infection. We also found that monocytes and activated natural killer cells were upregulated in both GSE113342 and GSE32591. Glomerular S100A8 staining was significantly enhanced compared to that in the controls, especially in class IV. Conclusions: The DEGs identified in the present study help us understand the underlying molecular mechanisms of LN. Our results show that glomerular S100A8 expression varies in different pathological types; however, further research is required to confirm the role of S100A8 in LN. [ABSTRACT FROM AUTHOR]

As acute pancreatitis progresses to the severe form, a life‐threatening systemic inflammation is triggered. Although the mechanisms involved in this process are not yet well understood, it has been proposed that circulating exosomes may be involved in the progression of inflammation from the pancreas to distant organs. Here, the inflammatory capacity and protein profile of plasma exosomes obtained during the first 24 h of hospitalization of patients diagnosed with acute pancreatitis were characterized and compared with the final severity of the disease. We found that the final severity of the disease strongly correlates with the inflammatory capacity of exosomes in the early stages of acute pancreatitis. Exosomes isolated from patients with mild pancreatitis had no effect on macrophages, while exosomes isolated from patients with severe pancreatitis triggered NFκB activation, TNFα and IL1β expression, and free radical generation. To delve deeper into the mechanism involved, we performed a proteomic analysis of the different exosomes that allowed us to identify different groups of proteins whose concentration was also correlated with the clinical classification of pancreatitis. In particular, an increase in the amount of S100A8 and S100A9 carried by exosomes of severe pancreatitis suggests that the mechanism of action of exosomes is mediated by the effect of these proteins on NADPH oxidase. This enzyme is activated by S100A8/S100A9, thus generating free radicals and promoting an inflammatory response. Along these lines, we observed that inhibition of this enzyme abolished all the pro‐inflammatory effects of exosomes from severe pancreatitis. All this suggests that the systemic effects, and therefore the final severity of acute pancreatitis, are determined by the content of circulating exosomes generated in the early hours of the process. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

BACKGROUND: CD133 (prominin-1) is the most commonly used molecular marker of the cancer stem cells (CSCs) that maintain tumor progression and recurrence in colorectal cancer. However, the proteome of CSCs directly isolated from colorectal tumors based on CD133 expression has never been investigated. OBJECTIVE: To reveal biomarkers of CD133-positive colorectal CSCs. METHODS: Thirty colorectal tumor samples were collected from patients undergoing bowel resection. CD133-positive and CD133-negative cells were isolated by FACS. Comparative proteomic profiling was performed by LC-MS/MS analysis combined with label-free quantification. Verification of differentially expressed proteins was performed by flow cytometry or ELISA. CD133-knockout Caco-2 and HT-29 cell lines were generated using CRISPR-Cas9 gene editing. RESULTS: LC-MS/MS analysis identified 29 proteins with at least 2.5-fold higher expression in CD133-positive cells versus CD133-negative cells. Flow cytometry confirmed CEACAM5 overexpression in CD133-positive cells in all clinical samples analyzed. S100A8, S100A9, and DEFA1 were differentially expressed in only a proportion of the samples. CD133 knockout in the colon cancer cell lines Caco-2 and HT-29 did not affect the median level of CEACAM5 expression, but led to higher variance of the percentage of CEACAM5-positive cells. CONCLUSIONS: High CEACAM5 expression in colorectal cancer cells is firmly associated with the CD133-positive colorectal CSC phenotype, but it is unlikely that CD133 directly regulates CEACAM5 expression. [ABSTRACT FROM AUTHOR]

Gliomas, the most common form of brain cancer, can range from relatively slow-growing low-grade to highly aggressive glioblastoma that has a median overall survival of only 15 months despite multimodal standard therapy. Although immunotherapy with checkpoint inhibitors has significantly improved patient survival for some cancers, to date, these agents have not shown consistent efficacy against malignant gliomas. Therefore, there is a pressing need to better understand the impact of host inflammatory responses on the efficacy of emerging immunotherapy approaches for these resistant tumors. RAGE is a multi-ligand pattern recognition receptor that is activated in various inflammatory states such as diabetes, Alzheimer's disease, cystic fibrosis, and cancer. Low levels of RAGE can be found under normal physiological conditions in neurons, immune cells, activated endothelial, and vascular smooth muscle cells, but it is over-expressed under chronic inflammation due to the accumulation of its ligands. RAGE binds to a range of damage-associated molecular pattern molecules (DAMPs) including AGEs, HMGB1, S100s, and DNA which mediate downstream cellular responses that promote tumor growth, angiogenesis, and invasion. Both in vitro and in vivo studies have shown that inhibition of RAGE signaling can disrupt inflammation and cancer progression and metastasis. Here, we will review our current understanding of the role of RAGE pathway on glioma progression and how it could be exploited to improve the efficacy of immunotherapy approaches. [ABSTRACT FROM AUTHOR]

Immune cells harboring somatic mutations reportedly infiltrate cancer tissues in patients with solid cancers and accompanying clonal hematopoiesis. Loss‐of‐function TET2 mutations are frequently observed in clonal hematopoiesis in solid cancers. Here, using a mouse lung cancer model, we evaluated the activity of Tet2‐deficient immune cells in tumor tissues. Myeloid‐specific Tet2 deficiency enhanced tumor growth in mice relative to that seen in controls. Single‐cell sequencing analysis of immune cells infiltrating tumors showed relatively high expression of S100a8/S100a9 in Tet2‐deficient myeloid subclusters. In turn, treatment with S100a8/S100a9 promoted Vegfa production by cancer cells, leading to a marked increase in the tumor vasculature in Tet2‐deficient mice relative to controls. Finally, treatment of Tet2‐deficient mice with an antibody against Emmprin, a known S100a8/S100a9 receptor, suppressed tumor growth. These data suggest that immune cells derived from TET2‐mutated clonal hematopoiesis exacerbate lung cancer progression by promoting tumor angiogenesis and may provide a novel therapeutic target for lung cancer patients with TET2‐mutated clonal hematopoiesis. [ABSTRACT FROM AUTHOR]

aimed to explore the neuroprotective mechanism of Di Dang decoction (DDD) during acute intracerebral hemorrhage (AICH) stroke in Sprague Dawley rats through proteomic analysis. Methods: A total of 135 healthy Sprague Dawley rats were randomly divided into five groups: control (n = 27), model (n = 27), DDD low-dose (n = 27), DDD medium-dose (n = 27), and DDD high-dose (n = 27). AICH stroke in rats was induced by injecting autologous blood into the caudate nucleus. The modified Neurological Severity Score (mNSS) was used to evaluate the cerebral nerve function deficit. Hematoxylin and eosin (HE) staining was performed to observe the brain tissue at the lesion site. Albumin concentration was assessed on obvious blood-brain barrier damaged and brain water content was used to evaluate the brain injury. For quantitative proteomics, proteins were extracted from the cerebral cortices. Target proteins were identified using mass spectrometer-based targeted proteomic quantification. Results: mNSS score, HE staining results, albumin concentration, and brain water content showed the most significant improvements in the neuroprotective in the high-dose group 7 days after DDD exposure. Furthermore, quantitative proteomics analysis showed that, relative to the control group, S100a8 and S100a9 were downregulated by 0.614 (p = 0.033702) and 0.506 times (p = 0.000024) in the high-dose group. Compared with the control group, Col1a1 and Col1a2 were upregulated by 1.319 (p = 0.000184) and 1.348 (p = 0.014097) times in the high-dose group. These results were confirmed using mass spectrometer-based targeted proteomic quantification. Conclusion: Application of a high-dose DDD for 7 days in AICH stroke rats showed the most significant improvements in neuroprotective. Mechanistically, this effect was mediated by S100a8 and S100a9 protein downregulation and Col1a1 and Col1a2 upregulation. [ABSTRACT FROM AUTHOR]

Cancer‐associated fibroblasts (CAFs) in the tumor microenvironment have been associated with tumor progression in breast cancer. Although crosstalk between breast cancer cells and CAFs has been studied, the effect of CAFs on non‐neoplastic breast epithelial cells is not fully understood to date. Here, we investigated the effect of CAFs on aggressive phenotypes in non‐neoplastic MCF10A breast epithelial cells. CAFs induced epithelial‐to‐mesenchymal transition (EMT) and invasive phenotype in MCF10A cells. S100A8, a potential prognostic marker in several cancers, was markedly increased in MCF10A cells by CAFs. S100A8 was crucial for CAFs‐induced invasive phenotype of MCF10A cells. Among cytokines increased by CAFs, interleukin (IL)‐8 induced S100A8 through transcription factors p65 NF‐κB and C/EBPβ. In a xenograft mouse model with MCF10A cells and CAFs, tumor was not developed, suggesting that coinjection with CAFs may not be sufficient for in vivo tumorigenicity of MCF10A cells. Xenograft mouse tumor models with MDA‐MB‐231 breast carcinoma cells provided an in vivo evidence for the effect of CAFs on breast cancer progression as well as a crucial role of IL‐8 in tumor growth and S100A8 expression in vivo. Using a tissue microarray of human breast cancer, we showed that S100A8 expression was correlated with poor outcomes. S100A8 expression was more frequently detected in cancer‐adjacent normal human breast tissues than in normal breast tissues. Together, this study elucidated a novel mechanism for the acquisition of invasive phenotype of non‐neoplastic breast cells induced by CAFs, suggesting that targeting IL‐8 and S100A8 may be an effective strategy against breast cancer. [ABSTRACT FROM AUTHOR]

Background: Periodontitis is one of major oral diseases, which has no consensus on early screening tool. This study aimed to compare the association and screening ability of S100A8 and S100A9 in saliva, blood and gingival crevicular fluid (GCF) for periodontitis status. Methods: We recruited 149 community Korean adults, 50 no or initial periodontitis (NIPERIO) and 99 established periodontitis (PERIO). Using clinical attachment loss and a panoramic radiograph, stage II–IV of new classification of periodontitis proposed at 2018 was considered cases as PERIO. Enzyme linked immunosorbent assay kit was used to quantify S100A8 and S100A9. T-test, analysis of covariance, Mann–Whitney test and correlation analysis were applied to compare the relationship of S100A8 and S100A9 in saliva, blood, and GCF for periodontitis. Receiver operating characteristic curve was applied for screening ability. Results: Among S100A8 and S100A9 in saliva, blood and GCF, S100A8 in saliva was significantly higher in PERIO than in NIPERIO (p < 0.05). However, S100A8 and S100A9 in GCF were higher in NIPERIO (p < 0.05). The screening ability of salivary S100A8 was 75% for PERIO, while that of GCF S100A8 was 74% for NIPERIO. Salivary S100A8 was positively correlated to blood S100A8 (p < 0.05). Conclusion: Salivary S100A8 could be a potential diagnostic marker for established periodontitis and be useful for screening established periodontitis. [ABSTRACT FROM AUTHOR]

While there is convincing evidence on the role of Aire-positive medullary thymic epithelial cells (mTEC) in the induction of central tolerance, the nature and function of post-Aire mTECs and Hassall's corpuscles have remained enigmatic. Here we summarize the existing data on these late stages of mTEC differentiation with special focus on their potential to contribute to central tolerance induction by triggering the unique pro-inflammatory microenvironment in the thymus. In order to complement the existing evidence that has been obtained from mouse models, we performed proteomic analysis on microdissected samples from human thymic medullary areas at different differentiation stages. The analysis confirms that at the post-Aire stages, the mTECs lose their nuclei but maintain machinery required for translation and exocytosis and also upregulate proteins specific to keratinocyte differentiation and cornification. In addition, at the late stages of differentiation, the human mTECs display a distinct pro-inflammatory signature, including upregulation of the potent endogenous TLR4 agonist S100A8/S100A9. Collectively, the study suggests a novel mechanism by which the post-Aire mTECs and Hassall's corpuscles contribute to the thymic microenvironment with potential cues on the induction of central tolerance. [ABSTRACT FROM AUTHOR]

Humanized mouse models are attractive experimental models for analyzing the development and functions of human dendritic cells (DCs) in vivo. Although various types of DC subsets, including DC type 3 (DC3s), have been identified in humans, it remains unclear whether humanized mice can reproduce heterogeneous DC subsets. CD14, classically known as a monocyte/macrophage marker, is reported as an indicator of DC3s. We previously observed that some CD14+ myeloid cells expressed CD1c, a pan marker for bona fide conventional DC2 (cDC2s), in humanized mouse models in which human FLT3L and GM-CSF genes were transiently expressed using in vivo transfection (IVT). Here, we aimed to elucidate the identity of CD14+CD1c+ DC-like cells in humanized mouse models. We found that CD14+CD1c+ cells were phenotypically different from cDC2s; CD14+CD1c+ cells expressed CD163 but not CD5, whereas cDC2s expressed CD5 but not CD163. Furthermore, CD14+CD1c+ cells primed and polarized naïve CD4+ T cells toward IFN-γ+ Th1 cells more profoundly than cDC2s. Transcriptional analysis revealed that CD14+CD1c+ cells expressed several DC3-specific transcripts, such as CD163, S100A8, and S100A9, and were clearly segregated from cDC2s and monocytes. When lipopolysaccharide was administered to the humanized mice, the frequency of CD14+CD1c+ cells producing IL-6 and TNF-α was elevated, indicating a pro-inflammatory signature. Thus, humanized mice are able to sustain development of functional CD14+CD1c+ DCs, which are equivalent to DC3 subset observed in humans, and they could be useful for analyzing the development and function of DC3s in vivo. [ABSTRACT FROM AUTHOR]

Psoriasis is one of the most common immune-mediated inflammatory skin diseases. Expression and secretion of two pro-inflammatory molecules of the S100-alarmin family, S100A8 and S100A9, in keratinocytes is a hallmark of psoriasis, which is also characterized by an altered differentiation of keratinocytes. Dimers of S100A8/S100A9 (calprotectin) bind to Toll-like receptor 4 and induce an inflammatory response in target cells. Targeted deletion of S100A9 reduced the inflammatory phenotype of psoriasis-like inflammation in mice. A role of S100-alarmins in differentiation and activation of keratinocytes was suggested but has been never shown in primary keratinocytes. We now confirm that induction of S100-alarmins in an imiquimod-induced murine model of psoriasis-like skin inflammation was associated with an increased expression of interleukin (IL)-1α, IL-6, IL-17A, or TNFα. This association was confirmed in transcriptome data obtained from controls, lesional and non-lesional skin of psoriasis patients, and a down-regulation of S100-alarmin expression after IL-17 directed therapy. However, analyzing primary S100A9−/− keratinocytes we found that expression of S100A8/S100A9 has no significant role for the maturation and inflammatory response pattern of keratinocytes. Moreover, keratinocytes are no target cells for the pro-inflammatory effects of S100A8/S100A9. However, different cytokines, especially IL-17A and F, highly abundant in psoriasis, strongly induced expression of S100-alarmins preferentially during early maturation stages of keratinocytes. Our data indicate that expression of S100A8 and S100A9 does not primarily influence maturation or activation of keratinocytes but rather represents the inflammatory response of these cells during psoriasis. [ABSTRACT FROM AUTHOR]