Mammalian STE20-like kinase 1 (MST1) is involved in the occurrence of cancer and autoimmune diseases by regulating cell proliferation, differentiation, apoptosis and other functions. However, its role and downstream targets in rheumatoid arthritis (RA) remain unclear. The model of RA fibroblast-like synoviocytes (RA-FLSs) overexpressing MST1 was constructed by lentiviral transfection in vitro and analyzed the effects of MST1 on apoptosis, migration, invasion, and inflammation of RA-FLSs. The effect of MST1 on joint synovial membrane inflammation and bone destruction was observed in vivo by establishing a rat model of arthritis with complete Freund's adjuvant. MST1 is down-regulated in RA-FLSs, and up-regulation of MST1 inhibits the survival, migration, invasion and inflammation of RA-FLSs. Mechanistically, MST1 inhibits SIRT3/mTOR-signaling pathway, inducing decreased mitochondrial autophagy and increased mitochondrial fission, resulting in mitochondrial morphological abnormalities and dysfunction, and ultimately increased apoptosis. We have observed that activation of MST1 alleviates synovial inflammation and bone erosion in vivo. MST1 reduces the survival, migration, invasion and inflammation of FLSs by inhibiting the SIRT3/mTOR axis to reduce mitochondrial autophagy and promote mitochondrial division, thereby achieving the potential role of relieving rheumatoid arthritis.

Background and objectiveNeuropathic pain is a chronic condition characterized by aberrant signaling within the somatosensory system, affecting millions of people worldwide with limited treatment options. Herein, we aim at investigating the potential of a sigma-1 receptor (σ1R) antagonist in managing neuropathic pain.MethodsA Chronic Constriction Injury (CCI) model was used to induce neuropathic pain. The potential of (+)-MR200 was evaluated following daily subcutaneous injections of the compound. Its mechanism of action was confirmed by administration of a well-known σ1R agonist, PRE084.Results(+)-MR200 demonstrated efficacy in protecting neurons from damage and alleviating pain hypersensitivity in CCI model. Our results suggest that (+)-MR200 reduced the activation of astrocytes and microglia, cells known to contribute to the neuroinflammatory process, suggesting that (+)-MR200 may not only address pain symptoms but also tackle the underlying cellular mechanism involved. Furthermore, (+)-MR200 treatment normalized levels of the gap junction (GJ)-forming protein connexin 43 (Cx43), suggesting a reduction in harmful intercellular communication that could fuel the chronicity of pain.ConclusionsThis approach could offer a neuroprotective strategy for managing neuropathic pain, addressing both pain symptoms and cellular processes driving the condition. Understanding the dynamics of σ1R expression and function in neuropathic pain is crucial for clinical intervention.

Colitis is a global disease usually accompanied by intestinal epithelial damage and intestinal inflammation, and an increasing number of studies have found natural products to be highly effective in treating colitis. Anemoside B4 (AB4), an abundant saponin isolated from Pulsatilla chinensis (Bunge), whichwas found to have strong anti-inflammatory activity. However, the exact molecular mechanisms and direct targets of AB4 in the treatment of colitis remain to be discovered. The anti-inflammatory activities of AB4 were verified in LPS-induced cell models and 2, 4, 6-trinitrobenzene sulfonic (TNBS) or dextran sulfate sodium (DSS)-induced colitis mice and rat models. The molecular target of AB4 was identified by affinity chromatography analysis using chemical probes derived from AB4. Experiments including proteomics, molecular docking, biotin pull-down, surface plasmon resonance (SPR), and cellular thermal shift assay (CETSA) were used to confirm the binding of AB4 to itsmolecular target. Overexpression of pyruvate carboxylase (PC) and PC agonist were used to study the effects of PC on the anti-inflammatory and metabolic regulation of AB4 in vitro and in vivo. AB4 not only significantly inhibited LPS-induced NF-κB activation and increased ROS levels in THP-1 cells, but also suppressed TNBS/DSS-induced colonic inflammation in mice and rats. The molecular target of AB4 was identified as PC, a key enzyme related to fatty acid, amino acid and tricarboxylic acid (TCA) cycle. We next demonstrated that AB4 specifically bound to the His879 site of PC and altered the protein's spatial conformation, thereby affecting the enzymatic activity of PC. LPS activated NF-κB pathway and increased PC activity, which caused metabolic reprogramming, while AB4 reversed this phenomenon by inhibiting the PC activity. In vivo studies showed that diisopropylamine dichloroacetate (DADA),a PC agonist, eliminated the therapeutic effects of AB4 by changing the metabolic rearrangement of intestinal tissues in colitis mice. We identified PC as a direct cellular target of AB4 in the modulation of inflammation, especially colitis. Moreover, PC/pyruvate metabolism/NF-κB is crucial for LPS-driven inflammation andoxidative stress. These findings shed more light on thepossibilities ofPC as a potential new target for treating colitis.

Nafamostat mesilate (NM), a synthetic broad-spectrum serine protease inhibitor, has been commonly used for treating acute pancreatitis (AP) and other inflammatory-associated diseases in some East Asia countries. Although the potent inhibitory activity against inflammation-related proteases (such as thrombin, trypsin, kallikrein, plasmin, coagulation factors, and complement factors) is generally believed to be responsible for the anti-inflammatory effects of NM, the precise target and molecular mechanism underlying its anti-inflammatory activity in AP treatment remain largely unknown. The protection of NM against pancreatic injury and inhibitory effect on the NOD-like receptor protein 3 (NLRP3) inflammasome activation were investigated in an experimental mouse model of AP. To decipher the molecular mechanism of NM, the effects of NM on nuclear factor kappa B (NF-κB) activity and NF-κB mediated NLRP3 inflammasome priming were examined in lipopolysaccharide (LPS)-primed THP-1 cells. Additionally, the potential of NM to block the activity of histone deacetylase 6 (HDAC6) and disrupt the association between HDAC6 and NLRP3 was also evaluated. NM significantly suppressed NLRP3 inflammasome activation in the pancreas, leading to a reduction in pancreatic inflammation and prevention of pancreatic injury during AP. NM was found to interact with HDAC6 and effectively inhibit its function. This property allowed NM to influence HDAC6-dependent NF-κB transcriptional activity, thereby blocking NF-κB-driven transcriptional priming of the NLRP3 inflammasome. Furthermore, NM exhibited the potential to interfere the association between HDAC6 and NLRP3, impeding HDAC6-mediated intracellular transport of NLRP3 and ultimately preventing NLRP3 inflammasome activation. Our current work has provided valuable insight into the molecular mechanism underlying the immunomodulatory effect of NM in the treatment of AP, highlighting its promising application in the prevention of NLRP3 inflammasome-associated inflammatory pathological damage.

Autoinflammatory diseases (AIDs) constitute several disorders that are characterized by the presence of recurrent episodes of unprovoked inflammation due to dysregulated innate immune system in the absence of autoantibodies or infections. Most of them have a strong genetic background, with mutations in single genes involved in inflammation referred to monogenic AIDs. In this article, we will review the cardiac manifestations in various monogenic AIDs. Various cardiac manifestations can be seen in various monogenic AIDs, including pericarditis, valvular diseases, coronary diseases, cardiomyopathies, and pulmonary hypertension, especially in Familial Mediterranean fever (FMF). Monogenic AIDs can manifest a variety of cardiac lesions, the most common of which is pericardial effusion, which may be local pericardial inflammation secondary to systemic inflammatory responses. While, the pathogenesis and incidence are still unclear. More research is still needed to explore the relationship between monogenic AIDs and cardiac damage for better understanding these diseases.

Post-traumatic urethral stricture is a clinical challenge for both patients and clinicians. Targeting glutamine metabolism to suppress excessive activation of urethral fibroblasts (UFBs) is assumed to be a potent and attractive strategy for preventing urethral scarring and stricture. In cellular experiments, we explored whether glutaminolysis meets the bioenergetic and biosynthetic demands of quiescent UFBs converted into myofibroblasts. At the same time, we examined the specific effects of M2-polarized macrophages on glutaminolysis and activation of UFBs, as well as the mechanism of intercellular signaling. In addition, findings were further verified in vivo in New Zealand rabbits. It revealed that glutamine deprivation or knockdown of glutaminase 1 (GLS1) significantly inhibited UFB activation, proliferation, biosynthesis, and energy metabolism; however, these effects were rescued by cell-permeable dimethyl α-ketoglutarate. Moreover, we found that exosomal miR-381 derived from M2-polarized macrophages could be ingested by UFBs and inhibited GLS1-dependent glutaminolysis, thereby preventing excessive activation of UFBs. Mechanistically, miR-381 directly targets the 3'UTR of Yes-associated protein (YAP) mRNA to reduce its stability at the transcriptional level, ultimately downregulating expression of YAP, and GLS1. In vivo experiments revealed that treatment with either verteporfin or exosomes derived from M2-polarized macrophages significantly reduced urethral stricture in New Zealand rabbits after urethral trauma. Collectively, this study demonstrates that exosomal miR-381 from M2-polarized macrophages reduces myofibroblast formation of UFBs and urethral scarring and stricture by inhibiting YAP/GLS1-dependent glutaminolysis.

Triggering receptors expressed on myeloid cells-1 (TREM-1) has been shown to participate in inflammatory autoimmune diseases. Nevertheless, the detailed underlying mechanisms and therapeutic benefits by targeting TREM-1 remain elusive, especially in myeloid dendritic cells (mDCs) and systemic lupus erythematosus (SLE). Disorders of epigenetic processes including non-coding RNAs give rise to SLE, resulting in complicated syndromes. Here, we aim to address this issue and explore the miRNA to inhibit the activation of mDCs and alleviate the progress of SLE by targeting TREM-1 signal axis. Bioinformatics methods were used to analyze the differentially expressed genes (DEGs) between patients with SLE and healthy individuals by four mRNA microarray datasets from Gene Expression Omnibus (GEO). Then we identified the expression of TREM-1 and its soluble form (sTREM-1) in clinical samples by ELISA, quantitative real-time PCR and Western blot. Phenotypic and functional changes of mDCs elicited by TREM-1 agonist were determined. Three databases of miRNAs target prediction and a dual-luciferase reporter assay were used to screen and verify miRNAs that can directly inhibit TREM-1 expression in vitro. Moreover, pristane-induced lupus mice were injected with miR-150-5p agomir to evaluate the effects of miR-150-5p on mDCs in lymphatic organs and disease activity in vivo. We screened TREM-1 as one of the hub genes closely correlated with the progression of SLE and identified sTREM-1 in serum as a valuable diagnostic biomarker for SLE. Moreover, activation of TREM-1 by its agonist promoted activation and chemotaxis of mDCs and increased the production of inflammatory cytokines and chemokines, showing higher expression of IL-6, TNF-α, and MCP-1. We showed that lupus mice displayed a unique miRNA signature in spleen, among which miR-150 was the most significantly expressed miRNA that targeting TREM-1 compared with wild type group. Transfection of miRNA-150-5p mimics directly suppressed the expression of TREM-1 by binding to its 3' UTR. Our in vivo experiments first indicated that administration of miR-150-5p agomir effectively ameliorated lupus symptoms. Intriguingly, miR-150 inhibited the over activation of mDCs through TREM-1 signal pathway in lymphatic organs and renal tissues. TREM-1 represents a potentially novel therapeutic target and we identify miR-150-5p as one of the mechanisms to alleviate lupus disease, which is attributable for inhibiting mDCs activation through TREM-1 signaling pathway.

To investigate the balancing mechanisms between decidualization-associated inflammation and pregnancy-related immunotolerance. Decidual samples from women with normal pregnancy (n = 58) or unexplained spontaneous miscarriage (n = 13), peripheral blood from normal pregnancy and endometria from non-pregnancy (n = 10) were collected. Primary endometrial stromal cells (ESCs), decidual stromal cells (DSCs), decidual immune cells (DICs) and peripheral blood mononuclear cells (PBMCs) were isolated. The plasmid carrying neuropilin-1 (NRP1) gene was transfected into ESC for overexpression. To induce decidualization in vitro, ESCs were treated with a combination of 10nM estradiol, 100nM progesterone and 0.5mM cAMP. Anti-Sema3a and anti-NRP1 neutralizing antibodies were applied to block the ligand-receptor interactions. RNA-seq analysis was performed to identify differentially expressed genes in DSCs and DICs, and NRP1 expression was verified by Western blotting and flow cytometry. The secretion of inflammatory mediators was measured using a multifactor cytometric bead array. The effects of Sema3a-NRP1 pathway on DICs were determined by flow cytometry. Statistical differences between groups were compared using the T test and one way or two-way ANOVA. Combined with five RNA-seq datasets, NRP1 was the only immune checkpoint changing oppositely between DSCs and DICs. The decreased expression of NRP1 in DSCs allowed intrinsic inflammatory responses required for decidualization, while its increased expression in DICs enhanced tolerant phenotypes beneficial to pregnancy maintenance. DSC-secreted Sema3a promoted immunosuppression in DICs via NRP1 binding. In women with miscarriage, NRP1 was abnormally elevated in DSCs but diminished in decidual macrophages and NK cells. NRP1 is a multifunctional controller that balances the inflammatory states of DSCs and DICs in gravid uterus. Abnormal expression of NRP1 is implicated in miscarriage.

Angiopoietin-like 4 (ANGPTL4) belongs to the angiopoietin-like protein family and mediates the inhibition of lipoprotein lipase activity. Emerging evidence suggests that ANGPTL4 has pleiotropic functions with anti- and pro-inflammatory properties. A thorough search on PubMed related to ANGPTL4 and inflammation was performed. Genetic inactivation of ANGPTL4 can significantly reduce the risk of developing coronary artery disease and diabetes. However, antibodies against ANGPTL4 result in several undesirable effects in mice or monkeys, such as lymphadenopathy and ascites. Based on the research progress on ANGPTL4, we systematically discussed the dual role of ANGPTL4 in inflammation and inflammatory diseases (lung injury, pancreatitis, heart diseases, gastrointestinal diseases, skin diseases, metabolism, periodontitis, and osteolytic diseases). This may be attributed to several factors, including post-translational modification, cleavage and oligomerization, and subcellular localization. Understanding the potential underlying mechanisms of ANGPTL4 in inflammation in different tissues and diseases will aid in drug discovery and treatment development.

ObjectiveLung cystic fibrosis (CF) is characterized by chronic infections and hyperinflammatory response of neutrophils and macrophages. P. aeruginosa (PA) and S. aureus (MSSA, MRSA) are major pathogens of advanced CF. The main goal of this study was to compare the inflammatory phenotype of murine C57BL/6 macrophages exposed to PA57 with that exposed to MSSA60, both strains isolated from the same patient with severe CF. In the present study, we used C57BL/6 mice sensitive to lung infection with P. aeruginosa.MethodsWe measured the release of cytokines and the expression of phenotypic markers of murine neutrophils and macrophages exposed to bacterial cells and biofilm components (i.e., EPS) of the selected bacteria. In addition, a quantitative proteomic approach was used for the characterization of proteome-wide changes in macrophages.ResultsNeutrophils stimulated with PA57 and MSSA60 strains produced hyperinflammatory pattern of cytokines. The pro-inflammatory impact of PA57 was significantly higher than that of MSSA60 (IL-6/IL-10 ratio: PA57 = 9.3 vs. MSSA60 = 1.7). Macrophages produced significantly lower amount of cytokines, but showed classical pattern of M1 markers (iNOS-High; arginase-1 and mannose receptor MRC1-Low). Importantly, as evidenced by proteomic analysis, PA57 and PA57-EPS were stronger inducers of M1 macrophage polarization than the MSSA60 counterparts.ConclusionsOur study demonstrated that strong biofilm P. aeruginosa strains, CF isolates, are dominant inducers of M1 macrophages, termed biofilm-associated macrophages (BAMs). We suggest that repolarization of detrimental BAMs might be a new therapeutic strategy to ameliorate the airway damage in CF.