Recombinant S100A8 Research Articles

SS31 alleviates LPS-induced acute lung injury by inhibiting inflammatory responses through the S100A8/NLRP3/GSDMD signaling pathway

BackgroundAcute 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.MethodsThe study applied transcriptome sequencing, immunofluorescence, PCR, immunofluorescence and other methods to explore the mechanism of SS31 in LPS induced ALI.ResultsTranscriptome 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.ConclusionsThe 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.

Intraperitoneal Administration of S100A8 Ameliorates Experimental Acute Colitis in Rats.

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.

Blocking S100A9-signaling is detrimental to the initiation of anti-tumor immunity.

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

S100A9 regulates M1 macrophage polarization and exacerbates steatotic liver ischemia-reperfusion injury

ObjectiveSteatotic livers exhibit higher susceptibility to ischemia reperfusion (IR) injury, which increase the risk of primary graft non-function following liver transplantation. S100A9 is identified as a pivotal innate immune sensor that regulates the progression of liver diseases. However, its significance in steatotic liver IR injury remains under-investigated. MethodsIn mice model, we generated S100A9 knockout (S100A9 KO) mice to investigate the role of S100A9 in IR-stimulated steatotic livers. In vitro, primary bone marrow-derived macrophages were utilized to explore the effect of S100A9 in regulating macrophage polarization and inflammation. ResultsS100A9 expression was markedly increased in steatotic livers of mice subjected to IR insult. S100A9 deletion significantly attenuated liver inflammatory injury, as evidenced by the diminished infiltration of both monocytes/macrophages and neutrophils (p < 0.05). The expression of proinflammatory factors was reduced (p < 0.05) at the same time. Additionally, S100A9-deficient livers demonstrated M1 polarization decrease and Toll-like receptor 4 (TLR4) suppression (p < 0.05). In vitro, genetic TLR4 inhibition led to nuclear factor kappa B (NF-κB) inactivation and subsequent M1 polarization decrease (p < 0.05) in macrophages treated with recombinant S100A9. ConclusionIn this study, we highlight the pivotal role of TLR4/NF-κB as a critical mediator of S100A9 in inducing M1 macrophage polorization- dependent inflammation in steatotic livers IR injury.

Changing expression system alters oligomerization and proinflammatory activity of recombinant human S100A9.

S100A9 is a Damage Associated Molecular Pattern (DAMP) that activates the innate immune system via Toll-like receptor 4 (TLR4). Despite many years of study, the mechanism of activation remains unknown. To date, much of the biochemical characterization of S100A9 has been performed using recombinant S100A9 expressed in E. coli (S100A9 ec ). TLR4 is the canonical receptor for LPS, a molecule found in the outer membrane of E. coli , raising the possibility of artifacts due to LPS contamination. Here we report characterization of LPS-free recombinant S100A9 expressed in insect cells (S100A9 in ). We show that S100A9 in does not activate TLR4. This difference does not appear to be due to LPS contamination, protein misfolding, purification artifacts, or differences in phosphorylation. We show instead that S100A9 in adopts an altered oligomeric state compared to S100A9 ec . Disrupting oligomer formation with the E. coli disaggregase SlyD restores activity to S100A9 in . Our results also indicate that the oligomeric state of S100A9 is a major factor in its ability to activate TLR4 and that this can be altered in unexpected ways by the recombinant expression system used to produce the protein.

Preliminary clinical analysis and pathway study of S100A8 as a biomarker for the diagnosis of acute deep vein thrombosis

Herein, we aimed to identify blood biomarkers that compensate for the poor specificity of D-dimer in the diagnosis of deep vein thrombosis (DVT). S100A8 was identified by conducting protein microarray analysis of blood samples from patients with and without DVT. We used ELISA to detect S100A8, VCAM-1, and ICAM-1 expression levels in human blood and evaluated their correlations. Additionally, we employed human recombinant protein S100A8 to induce human umbilical vein endothelial cells and examined the role of the TLR4/MAPK/VCAM-1 and ICAM-1 signaling axes in the pathogenic mechanism of S100A8. Simultaneously, we constructed a rat model of thrombosis induced by inferior vena cava stenosis and detected levels of S100A8, VCAM-1, and ICAM-1 in the blood of DVT rats using ELISA. The associations of thrombus tissue, neutrophils, and CD68-positive cells with S100A8 and p38MAPK, TLR4, and VCAM-1 expression levels in vein walls were explored. The results revealed that blood S100A8 was significantly upregulated during the acute phase of DVT and activated p38MAPK expression by combining with TLR4 to enhance the expression and secretion of VCAM-1 and ICAM-1, thereby affecting the occurrence and development of DVT. Therefore, S100A8 could be a potential biomarker for early diagnosis and screening of DVT.

TRPA1 deficiency aggravates dilated cardiomyopathy by promoting S100A8 expression to induce M1 macrophage polarization in rats.

Transient receptor potential ankyrin 1 (TRPA1) plays an important role in different cardiovascular diseases. However, the role of TRPA1 in dilated cardiomyopathy (DCM) remains unclear. Here, we aimed to investigate the role of TRPA1 in DCM induced by doxorubicin (DOX) and explore its possible mechanisms. GEO data were used to explore the expression of TRPA1 in DCM patients. DOX (2.5 mg/kg/week, 6 weeks, i.p.) was used to induce DCM. Bone marrow-derived macrophages (BMDMs) and neonatal rat cardiomyocytes (NRCMs) were isolated to explore the role of TRPA1 in macrophage polarization, cardiomyocyte apoptosis, and pyroptosis. In addition, DCM rats were treated with the TRPA1 activator, cinnamaldehyde to explore the possibility of clinical translation. TRPA1 expression was increased in left ventricular (LV) tissue in DCM patients and rats. TRPA1 deficiency aggravated the cardiac dysfunction, cardiac injury, and LV remodeling in DCM rats. In addition, TRPA1 deficiency promoted the M1 macrophage polarization, oxidative stress, cardiac apoptosis, and pyroptosis induced by DOX. RNA-seq results showed that TRPA1 knockout promoted the expression of S100A8, an inflammatory molecule that belongs to the family of Ca2+ -binding S100 proteins, in DCM rats. Furthermore, S100A8 inhibition attenuated M1 macrophage polarization in BMDMs isolated from TRPA1 deficiency rats. Recombinant S100A8 promoted the apoptosis, pyroptosis, and oxidative stress in primary cardiomyocytes stimulated with DOX. Finally, TRPA1 activation via cinnamaldehyde alleviated the cardiac dysfunction and reduced S100A8 expression in DCM rats. Taken together, these results suggested that TRPA1 deficiency aggravates DCM by promoting S100A8 expression to induce M1 macrophage polarization and cardiac apoptosis.

Abstract 5150: Improvement of hematopoiesis in primary low risk MDS with the TGFBR1 investigational inhibitor TP-6379

Abstract Background: The inflammaging modulator, S100A9, mediates immunosuppression and plays a key role in the pathogenesis of low-risk myelodysplastic syndrome (MDS). Specifically, S100A9’s feedforward activation in the bone marrow (BM) induces pyroptotic cell death of hematopoietic stem and progenitor cells (HSPC) and the activation and accumulation of myeloid-derived suppressor cells (MDSC). This process creates a suppressive microenvironment including the secretion of transforming growth factor β (TGFβ) that signals through the TGFβ receptor 1 (TGFBR1) to induce inhibitory processes that contribute to this phenotype. We hypothesize that targeting with an investigational TGFBR1 inhibitor, TP-6379, reduces immune suppression and restores hematopoiesis in MDS. Methods: Primary low risk MDS BM mononuclear cells (BMMNC) were obtained from the Moffitt Total Cancer Care Protocol and cultured in vitro with TP-6379. Healthy BMMNC were purchased, treated with or without recombinant S100A9 and TP-6379. Results: Treatment of primary MDS BMMNC (n=15) and S100A9-treated healthy BMMNC (n=5) with TP-6379 for 48 hours was observed to significantly improve proliferation of hematopoietic progenitor cells as measured by colony forming capacity. Total colonies, and BFU-E specific colonies, showed significant increase. This expansion of progenitors with treatment was validated by flow cytometric analysis of Lineage−HLA-DR−CD34+ HSPC and showed a reduction in genomic instability, measured by γH2AX. In addition, TP-6379 was observed to reduce the numbers of suppressive mediators; MDSC, T regs and senescent lymphocytes and increase the number of cytotoxic cells, including NK cells. Our analysis revealed that BMMNC with spliceosomal mutations, including SF3B1, have elevated sensitivity to TP-6379 treatment. Therefore, we tested wild type and SF3B1 K700E CRISPR knock-in K562 cells in the presence of TP-6379 for 48 hours. K562 is a well-established cell line model for study of MDS. The SF3B1 mutant expressing cells have significantly reduced BFU-E colony forming capacity, compared to wild type cells, concordant with higher pyroptosis activation and consistent with the BMMNC results. Hence, we measured phospho-SMAD activity, as a direct measure of TGFBR1 inhibition. SF3B1 mutant expressing cells were shown to be highly sensitive to TP-6379, with a significant loss of SMAD activation. Expression analysis of primary MDS, S100A9-treated healthy BMMNC cells and K562 SF3B1 mutant cells revealed elevated expression of SERPINE1 which was rescued by TP-6379 treatment. Conclusions: TP-6379 restores healthy hematopoiesis in low-risk MDS, which may translate into a strong therapeutic option in a disease with few clinical options. Importantly, our work also suggests a specific role for spliceosome dysfunction in bone marrow failure and a novel role for SERPINE1 in MDS and S100A9-induced suppression. Citation Format: Erika A. Eksioglu, Gabriela M. Wright, Jason M. Foulks, Matthew Lalonde, Steven L. Warner, Kenneth L. Wright. Improvement of hematopoiesis in primary low risk MDS with the TGFBR1 investigational inhibitor TP-6379. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5150.

Generation of a novel monoclonal antibody against inflammatory biomarker S100A8 using hybridoma technology.

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. A soluble recombinant S100A8 protein with a high yield and purity was produced usingEscherichia 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. 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.

S100A9 upregulated by IFNGR signaling blockade functions as a novel GVHD suppressor without compromising GVL in mice

AbstractAllogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative treatment for both malignant and nonmalignant hematologic disorders. However, graft-versus-host disease (GVHD) and malignant relapse limit its therapeutic success. We previously demonstrated that the blockade of interferon-gamma receptor (IFNGR) signaling in donor T cells resulted in a reduction in GVHD while preserving graft-versus-leukemia (GVL) effects. However, the underlying molecular mechanisms remain inconclusive. In this study, we found that S100A9 is a novel GVHD suppressor upregulated when IFNGR is blocked in T cells. Both Ifngr1−/− and S100a9-overexpressing T cells significantly reduced GVHD without compromising GVL, altering donor T-cell trafficking to GVHD target organs in our mouse model of allo-HSCT. In addition, in vivo administration of recombinant murine S100A9 proteins prolongs the overall survival of recipient mice. Furthermore, in vivo administration of anti-human IFNGRα neutralizing antibody (αhGR-Nab) significantly upregulates the expression of S100A9 in human T cells and improved GVHD in our mouse model of xenogeneic human peripheral blood mononuclear cell transplantation. Consistent with S100a9-overexpressing T cells in our allo-HSCT model, αhGR-Nab reduced human T-cell trafficking to the GVHD target organs. Taken together, S100A9, a downstream molecule suppressed by IFNGR signaling, functions as a novel GVHD suppressor without compromising GVL.

TLR9-Selective Therapeutic Targeting of MDS Clones with a CpG Payload-Delivery Strategy

Inflammatory molecules and their receptors serve as regulatory cues driving the proliferation of hematopoietic stem and progenitors (HSPC) in myelodysplastic syndromes (MDS). Recent studies indicate that inflammaging (inflammation in aging) in the bone marrow (BM) microenvironment contributes to hematopoietic impairment and MDS clone expansion. However, attempts to develop therapeutics targeting these processes have been hampered by potential off target effects due to the lack of identification of selective biomarkers to specifically target the MDS malignant clone. Therefore, a better understanding of the mechanisms of MDS inflammaging processes for selection and target of malignant clones remains a key goal. Several groups, including ours, have found that innate immune receptors are over expressed in MDS BM HSPC, including Toll-like receptors (TLRs). Overexpression of these receptors was associated with secretion of inflammatory cytokines and mediators including S100A9. S100A9, a Damage-Associated Molecular Pattern (DAMPs) molecule, causes pyroptosis of HSPC and induces genomic instability leading to MDS clonal expansion in an autocrine amplification loop. However, most of the TLRs and associated factors are hard to target due to their wide expression on healthy immune cells. We found that TLR9, usually an intracellular receptor, is upregulated and translocated to the surface of MDS progenitors, which thereby presents an opportunity for disease-specific targeting through its natural ligand, CpG oligonucleotides. TLR9 is one of the main pathogen recognition receptors expressed intracellularly in innate immune cells and recognizes bacterial nucleic acid moieties. Its gene expression has been previously found to be upregulated in MDS and now our work demonstrates a functional upregulation and translocation in low-risk disease. Flow cytometric sorting of low risk MDS BM cells with labeled CpG separated cells based on mutational burden suggesting that surface TLR9 is specific to malignant clones. Furthermore, pyroptotic release of nucleic acid DAMPs, such as RNA:DNA hybrids and our recently published biomarker oxidized mitochondrial DNA, is linked to the translocation of TLR9 from intracellular endosomes to the surface of these cells. This overexpression was validated in our unique inflammaging animal model, the S100A9 transgenic (Tg) mice, that phenocopies human MDS. Moreover, treatment of human BM mononuclear cells (MNC) with recombinant human S100A9 induced surface expression of TLR9, through the accumulation of S100A9-induced RNA:DNA hybrids and oxidized mitochondrial DNA. Therefore, this paradoxical surface expression of TLR9 in MDS BM HSPCs provides an opportunity to selectively target malignant cells through the targeted delivery of cytotoxins using our newly developed CpG-linked payload deliver strategy. CpG has been used safely in phase I and Phase II clinical trials where it has been shown to be well tolerated, although not effective as a stand-alone therapy. Therefore, we linked CpG to dendrimer particles (CpG-Den) providing a cationic lipid surface structure capable of disrupting cells only after internalization through TLR9. The CpG-Den linkage ratio can be manipulated to modify cytotoxicity strength and the particle size avoids leukocyte engulfment. Using both primary MDS BM MNC and BM MNC from S100A9Tg mice we demonstrate that treatment in vitro and in vivo with CpG-Den selectively targets surface TLR9+ HSPC, increasing healthy hematopoiesis in colony forming assays, and BM expression of HSPC, as well ameliorating anemia in vivo in the S100A9Tg mice. Use of this therapy also led to a decrease in suppressive myeloid cells likely aiding in the reduction of the inflammaging cycle. Localized targeting was confirmed in vivo by labeling CpG-Den with IR800 revealing specific accumulation in the mice BM. Our data supports TLR9-targeting potential in a proof-of-concept strategy to selectively target primary MDS malignant cells to restore and enhance hematopoiesis while avoiding toxicities.

S100A8 enhances IL-1β production from nasal epithelial cells in eosinophilic chronic rhinosinusitis

BackgroundChronic rhinosinusitis is classified into eosinophilic chronic rhinosinusitis (ECRS) and non-eosinophilic chronic rhinosinusitis (NECRS). ECRS is a refractory allergic disease involving a variety of immune and epithelial cells. S100A8 is a damage-associated molecular pattern that is closely related to allergic inflammation. However, the pathological implications of S100A8 in ECRS have not been clarified. MethodsWe evaluated the role of S100A8 in the pathogenesis of ECRS. Gene expression profiles of nasal polyps obtained from patients with ECRS or NECRS were evaluated using RNA sequencing. ResultsS100A8 was identified as a significantly upregulated gene in nasal polyps associated with ECRS. Immunohistochemistry consistently revealed intense S100A8 staining in nasal polyps from patients with ECRS. Human nasal epithelial cells expressed the receptor for advanced glycation end products and Toll-like receptor 4. Recombinant S100A8 protein induced interleukin-1β secretion in human nasal epithelial cells. ConclusionsOur data demonstrate that S100A8 results in production of interleukin-1β in the nasal epithelium, which may be involved in the pathogenesis of ECRS.

S100A9‑containing serum exosomes obtained from patients with burn injuries promote myocardial cell pyroptosis through NLRP3.

S100 calcium-binding protein A9 (S100A9) is highly expressed in the serum exosomes of patients with burn injuries. The present study aimed to investigate the underlying mechanisms of burn injury-associated exosomes in the regulation of myocardial cell pyroptosis. Reverse transcription-quantitative PCR and western blotting were used to examine relative mRNA and protein levels. The morphology of exosomes was visualized using transmission electron microscopy. The expression levels of IL-1β and IL-18 in cells were examined using ELISA kits. Finally, cell pyroptosis was examined using flow cytometry. When AC16 cells were treated with the serum exosomes obtained from patients with burn injuries, pyroptosis was significantly promoted and the expression levels of IL-1β and IL-18 were increased. NLR family pyrin domain containing 3 (NLRP3), S100A9, caspase-1 and Gasdermin D (GSDMD)-N expression levels were also upregulated. However, these were significantly reversed by anti-S100A9 antibodies. Thereafter, CY-09, an NLRP3 inhibitor, was revealed to restore the increase in pyroptosis and IL-18, IL-1β, caspase-1, NLRP3 and GSDMD-N expression levels caused by recombinant S100A9 to be similar to the control. These findings suggested that burn injury-associated exosomes containing S100A9 can affect AC16 cell pyroptosis through NLRP3.

Hepatic non-parenchymal S100A9-TLR4-mTORC1 axis normalizes diabetic ketogenesis

Unrestrained ketogenesis leads to life-threatening ketoacidosis whose incidence is high in patients with diabetes. While insulin therapy reduces ketogenesis this approach is sub-optimal. Here, we report an insulin-independent pathway able to normalize diabetic ketogenesis. By generating insulin deficient male mice lacking or re-expressing Toll-Like Receptor 4 (TLR4) only in liver or hepatocytes, we demonstrate that hepatic TLR4 in non-parenchymal cells mediates the ketogenesis-suppressing action of S100A9. Mechanistically, S100A9 acts extracellularly to activate the mechanistic target of rapamycin complex 1 (mTORC1) in a TLR4-dependent manner. Accordingly, hepatic-restricted but not hepatocyte-restricted loss of Tuberous Sclerosis Complex 1 (TSC1, an mTORC1 inhibitor) corrects insulin-deficiency-induced hyperketonemia. Therapeutically, recombinant S100A9 administration restrains ketogenesis and improves hyperglycemia without causing hypoglycemia in diabetic mice. Also, circulating S100A9 in patients with ketoacidosis is only marginally increased hence unveiling a window of opportunity to pharmacologically augment S100A9 for preventing unrestrained ketogenesis. In summary, our findings reveal the hepatic S100A9-TLR4-mTORC1 axis in non-parenchymal cells as a promising therapeutic target for restraining diabetic ketogenesis.

Shuangxinfang Prevents S100A9-Induced Macrophage/Microglial Inflammation to Improve Cardiac Function and Depression-Like Behavior in Rats After Acute Myocardial Infarction.

Background: Depression is a common complication of cardiovascular disease, which deteriorates cardiac function. Shuangxinfang (psycho-cardiology formula, PCF) was reported to alleviate myocardial ischemia injury and improve depression-like behavior. Interestingly, our previous proteomics study predicted that the protein S100A9 appeared as an important target, and macrophage/microglial inflammation might be involved in the process of PCF improving depression induced by acute myocardial infarction (AMI). This study aims to validate the proteomics results. Methods: AMI rat models were established in vivo, followed by the administration of PCF or ABR-215757 (also named paquinimod, inhibiting S100A9 binding to TLR4) for 5 days. Forced swimming test (FST) and open field test (OFT) were applied to record depression-like behavior, and echocardiography was employed to evaluate cardiac function. Morphological changes of cardiomyocytes were assessed by HE staining and TUNEL staining on day 7 after cardiac surgery, as well as Masson trichrome staining on day 21. Hippocampal neurogenesis was determined by Nissl staining, while 5-hydroxytryptamine (5-HT), tryptophan/kynurenine ratio, and brain-derived neurotrophic factor (BDNF) in the hippocampus were analyzed as biochemical indicators of depression. We employed RT-qPCR, western blotting, and immunofluorescence to detect the expression of pathway-related genes and proteins. Myocardial and hippocampal expression of inflammatory factors were performed by ELISA. The activation of macrophage and microglia was assessed via immunoreaction using CD68 and Iba1, respectively. For in vitro confirmation, BV2 cells were primed with recombinant protein S100A9 and then treated with PCF serum or ferulic acid to determine alterations in microglial inflammation. Results: Rats in the AMI group showed heart function deterioration and depression-like behavior. Coronary ligation not only brought about myocardial inflammation, cell apoptosis, and fibrosis but also reduced the neurogenesis, elevated the tryptophan/kynurenine ratio, and decreased the content of 5-HT. PCF could ameliorate the pathological and phenotypic changes in the heart and brain and inhibit the expression of the S100A9 protein, the activation of the microglial cell, and the secretion of IL-1β and TNF-α raised by AMI. ABR-215757 showed therapeutic effect and molecular biological mechanisms similar to PCF. Treatment with PCF serum or ferulic acid in vitro was proved to efficiently block the hyperactivation of BV2 cells and increment of cytokine contents induced by recombinant protein S100A9. Conclusion: We identify S100A9 as a novel and potent regulator of inflammation in both the heart and brain. Macrophage/microglia inflammation mediated by S100A9 is considered a pivotal pathogenic in depression after AMI and a major pathway for the treatment of PCF, suggesting that PCF is a promising therapeutic candidate for psycho-cardiology disease.

Hederacoside C ameliorates colitis via restoring impaired intestinal barrier through moderating S100A9/MAPK and neutrophil recruitment inactivation.

Hederacoside C (HSC) has attracted much attention as a novel modulator of inflammation, but its anti-inflammatory mechanism remains elusive. In the present study, we investigated how HSC attenuated intestinal inflammation in vivo and in vitro. HSC injection significantly alleviated TNBS-induced colitis by inhibiting pro-inflammatory cytokine production and colonic epithelial cell apoptosis, and partially restored colonic epithelial cell proliferation. The therapeutic effect of HSC injection was comparable to that of oral administration of mesalazine (200 mg·kg−1·d−1, i.g.). In LPS-stimulated human intestinal epithelial Caco-2 cells, pretreatment with HSC (0.1, 1, 10 μM) significantly inhibited activation of MAPK/NF-κB and its downstream signaling pathways. Pretreatment with HSC prevented LPS-induced TLR4 dimerization and MyD88 recruitment in vitro. Quantitative proteomic analysis revealed that HSC injection regulated 18 proteins in the colon samples, mainly clustered in neutrophil degranulation. Among them, S100A9 involved in the degranulation of neutrophils was one of the most significantly down-regulated proteins. HSC suppressed the expression of S100A9 and its downstream genes including TLR4, MAPK, and NF-κB axes in colon. In Caco-2 cells, recombinant S100A9 protein activated the MAPK/NF-κB signaling pathway and induced inflammation, which were ameliorated by pretreatment with HSC. Notably, HSC attenuated neutrophil recruitment and degranulation as well as S100A9 release in vitro and in vivo. In addition, HSC promoted the expression of tight junction proteins and repaired the epithelial barrier via inhibiting S100A9. Our results verify that HSC ameliorates colitis via restoring impaired intestinal barrier through moderating S100A9/MAPK and neutrophil recruitment inactivation, suggesting that HSC is a promising therapeutic candidate for colitis.

Intranasal Delivery of Recombinant S100A8 Protein Delays Lung Cancer Growth by Remodeling the Lung Immune Microenvironment.

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.

Generation of Monoclonal Antibodies for Sensitive Detection of Pro-Inflammatory Protein S100A9

The calcium-binding protein S100A9 regulates inflammatory processes and the immune response. It is overexpressed in a variety of inflammatory and oncologic conditions. In this study, we produced a recombinant human S100A9 (hS100A9) antigen with high yield and purity and used it to generate a hybridoma cell culture-based monoclonal anti-hS100A9 antibody. We selected five anti-hS100A9 antibodies from cell supernatants that showed high antigen binding efficiency and identified the nucleotide sequences of three antibodies: two with high effective concentration values and one with the lowest value. The antigen and antibody development procedures described herein are useful for producing large amounts of monoclonal antibodies against hS100A9 and other antigens of interest. The nucleotide sequences of the anti-hS100A9 monoclonal antibody revealed herein will be helpful in the generation of recombinant antibodies or antibody fragments against hS100A9.

S100A9-containing serum exosomes of burn injury patients promote permeability of pulmonary microvascular endothelial cells

Microvascular hyperpermeability is a leading mechanism responsible for occurrence of edema in remote organs and tissues in patients with burn injury. Accumulated evidence has shown that exosomes can be transported into target cells, where they are capable of regulating biological functions and physiology. Of exosomal proteins contributing to enhanced inflammation and vascular permeability, S100 calcium binding protein A9 (S100A9) has received increasing attention. Here we hypothesized that S100A9-containing serum exosomes of patients with burn injury contribute to pathogenesis of hyperpermeability of microvascular structure in lung by transferring signaling molecules into it and activating downstream signaling pathways, ultimately leading to disruption of the tight junctions (TJs) and endothelial barrier. A use of enzyme-linked immunosorbent assay revealed that total serum concentrations of S100A9 were significantly augmented in burn injury patients in comparison to normal controls. With use of human pulmonary microvascular endothelial cells (HPMECs) as an in vitro model, we found that patients' serum exosomes were effectively internalized by HPMECs. We further found that serum exosomes of stage II/II burn patients inhibited zonula occludens (ZO-1) and occludin protein levels, which are essential for TJs integrity and endothelial barrier function, but activated p38 MAPK signaling pathway in HPMECs. As expected, such exosomes-mediated effects on HPMECs were reversed by a simultaneous treatment of anti-S100A9 neutralizing antibody. Finally, we found that a recombinant human S100A9 treatment led to inhibition of expression of occludin and ZO-1 but an activation of p38 signaling in HPMECs, and that such effects were reversed when p38 activity was repressed, implying that S100A9 may stimulate p38 activity to inhibit ZO-1 and occludin in HPMECs. Collectively, these data suggest that S100A9-containing serum exosomes may play a critical role in contributing to pulmonary microvascular hyperpermeability, thus supporting that blocking exosomes' access to HPMECs could hold a promise strategy for treatment of lung edema resulting from burn injuries.

Anemoside B4 ameliorates TNBS-induced colitis through S100A9/MAPK/NF-\u03baB signaling pathway

BackgroundDespite the increased morbidity of ulcerative colitis (UC) in the developing countries, available treatments remain unsatisfactory. Therefore, it is urgent to discover more effective therapeutic strategies. Pulsatilla chinensis was widely used for the treatment of inflamed intestinal diseases including UC for thousands of years in China. Anemoside B4, the most abundant triterpenoid saponin isolated from P. chinensis, exerts anti-inflammatory and antioxidant effects and may be the most active compounds, which is responsible for the therapeutic effects. However, the mechanism how anemoside B4 executes its biological functions is still elusive.MethodsHere, we used the 2, 4, 6-trinitrobenzene sulfonic acid (TNBS)-induced colitis rat model to evaluate the therapeutic effect of anemoside B4. Blood samples of colitis rats were collected for hematology analysis. The inflammation-associated factors were investigated by enzyme-linked immunosorbent assay (ELISA). Cell proliferation and apoptosis was determined with EdU cell proliferation assay and TUNEL assay. The proteins regulated by anemoside B4 were identified by label-free quantitative proteomics. The significantly down-regulated proteins were verified by Western blotting analysis. mRNA expression was analyzed by quantitative real-time RT-PCR.ResultsThe results showed that anemoside B4 ameliorated TNBS-induced colitis symptoms, including tissue damage, inflammatory cell infiltration, and pro-inflammatory cytokine production, apoptosis and slowed proliferation in colon. Quantitative proteomic analyses discovered that 56 proteins were significantly altered by anemoside B4 in the TNBS-induced rats. These proteins mainly clustered in tricarboxylic acid (TCA) cycle and respiratory electron transport chain. Among the altered proteins, S100A9 is one of the most significantly down-regulated proteins and associated with NF-κB and MAPK signaling pathways in the pathogenesis of UC. Further experiments revealed that anemoside B4 suppressed the expression of S100A9 and its downstream genes including TLR4 and NF-κB in colon. In vitro, anemoside B4 could inhibit the NF-κB signaling pathway induced by recombinant S100A9 protein in human intestinal epithelial Caco-2 cells. Moreover, anemoside B4 inhibits neutrophils recruitment and activation in colon induced by TNBS.ConclusionsOur results demonstrate that anemoside B4 prevents TNBS-induced colitis by inhibiting the NF-κB signaling pathway through deactivating S100A9, suggesting that anemoside B4 is a promising therapeutic candidate for colitis.