Dectin-1 induces TRPV1 sensitization and contributes to visceral hypersensitivity of irritable bowel syndrome in male mice.

BACKGROUND: Visceral hypersensitivity is considered the core pathophysiological mechanism that causes abdominal pain in patients with irritable bowel syndrome (IBS). Fungal dysbiosis has been proved to contribute to visceral hypersensitivity in IBS patients. However, the underlying mechanisms for Dectin-1, a major fungal recognition receptor, in visceral hypersensitivity are poorly understood. This study aimed to explore the role of Dectin-1 in visceral hypersensitivity and elucidate the impact of Dectin-1 activity on the function of transient receptor potential vanilloid type 1 (TRPV1). METHODS: Visceral hypersensitivity model was established by the intracolonic administration of 0.1 mL TNBS (130 µg/mL in 30% ethanol) in the male mice. Fluconazole and nystatin were used as fungicides. Laminarin, a Dectin-1 antagonist and gene knockout (Clec7a-/-) mice were used to interrupt the function of Dectin-1. Colorectal distension-electromyogram recording was performed to assess visceral sensitivity. Immunostaining experiment was performed to determine the localization of Dectin-1 in dorsal root ganglion (DRG) neurons. Calcium imaging study was performed to assay TRPV1-mediated calcium influx in acutely dissociated DRG neurons. RESULTS: Pretreatment with fungicides, administration of laminarin or genetic deletion of Clec7a alleviated TNBS-induced visceral hypersensitivity in male mice. The expression of Dectin-1 was upregulated in the DRG and colon of TNBS-treated mice. Colocalization of Dectin-1 and TRPV1 was observed in DRG neurons. Importantly, pretreatment with curdlan, a Dectin-1 agonist, increased TRPV1-mediated calcium influx. CONCLUSIONS: Dectin-1 contributes to visceral hypersensitivity in IBS or in inflammatory bowel disease in remission and activation of Dectin-1 induces TRPV1 sensitization. SIGNIFICANCE STATEMENT: This work provides direct evidence for the functional regulation of TRPV1 channel by Dectin-1 activity, proposing a new mechanism underlying TRPV1 sensitization. Control of intestinal fungi might be beneficial for the treatment of refractory abdominal pain in patients with IBS or IBD in remission.

Intestinal dysbiosis exacerbates the pathogenesis of psoriasis-like phenotype through changes in fatty acid metabolism.

The intestinal microbiota has been associated with host immunity as well as psoriasis; however, the mechanism of intestinal microbiota regulating psoriasis needs to be demonstrated systematically. Here, we sought to examine its role and mechanism of action in the pathogenesis of psoriasis. We found that the severity of psoriasis-like skin phenotype was accompanied by changes in the composition of the intestinal microbiota. We performed co-housing and fecal microbial transplantation (FMT) experiments using the K14-VEGF transgenic mouse model of psoriasis and demonstrated that the transfer of intestinal microbiota from mice with severe psoriasis-like skin phenotype exacerbated psoriasiform skin inflammation in mice with mild symptoms, including increasing the infiltration and differentiation of Th17, and increased the abundance of Prevotella, while decreasing that of Parabacteroides distasonis, in the colon. These alterations affected fatty acid metabolism, increasing the abundance of oleic and stearic acids. Meanwhile, gentamicin treatment significantly reduced the abundance of Prevotella and alleviated the psoriasis-like symptoms in both K14-VEGF mice and imiquimod (IMQ)-induced psoriasis-like mice. Indeed, administration of oleic and stearic acids exacerbated psoriasis-like symptoms and increased Th17 and monocyte-derived dendritic cell infiltration in the skin lesion areas in vivo, as well as increased the secretion of IL-23 by stimulating DCs in vitro. At last, we found that, treatment of PDE-4 inhibitor alleviated psoriasis-like phenotype of K14-VEGF mice accompanied by the recovery of intestinal microbiota, including the decrease of Prevotella and increase of Parabacteroides distasonis. Overall, our findings reveal that the intestinal microbiota modulates host metabolism and psoriasis-like skin inflammation in mice, suggesting a new target for the clinical diagnosis and treatment of psoriasis.

Akkermansia muciniphila plays critical roles in host health.

Akkermansia muciniphila, an intestinal microorganism, belongs to Verrucomicrobia, one of the most abundant microorganisms in the mammalian gut. It is a mucin-degrading bacterium that can colonise intestines of mammals such as humans and mice by utilising mucin as the only nitrogen and carbon source. When A. muciniphila colonises the intestine, its metabolites interact with the intestinal barrier, affecting host health by consolidating the intestinal barrier, regulating metabolic functions of the intestinal and circulatory systems, and regulating immune functions. This review summarised the mechanisms of A. muciniphila-host interactions that are relevant to host health. We focussed on characteristics of A. muciniphila in relation to its metabolites to provide a comprehensive understanding of A. muciniphila and its effects on host health and disease processes.

Interleukin-38 promotes skin tumorigenesis in an IL-1Rrp2-dependent manner.

Interleukin-38 (IL-38) is strongly associated with chronic inflammatory diseases; however, its role in tumorigenesis is poorly understood. We demonstrated that expression of IL-38, which exhibits high expression in the skin, is downregulated in human cutaneous squamous cell carcinoma and 7,12-dimethylbenzanthracene/12-O-tetradecanoyl phorbol-13-acetate-induced mouse skin tumorigenesis. IL-38 keratinocyte-specific knockout mice displayed suppressed skin tumor formation and malignant progression. Keratinocyte-specific deletion of IL-38 was associated with reduced expression of inflammatory cytokines, leading to reduced myeloid cell infiltration into the local tumor microenvironment. IL-38 is dispensable for epidermal mutagenesis, but IL-38 keratinocyte-specific deletion reduces proliferative gene expression along with epidermal cell proliferation and hyperplasia. Mechanistically, we first demonstrated that IL-38 activates the c-Jun N-terminal kinase (JNK)/activator protein 1 signal transduction pathway to promote the expression of cancer-related inflammatory cytokines and proliferation and migration of tumor cells in an IL-1 receptor-related protein 2 (IL-1Rrp2)-dependent manner. Our findings highlight the role of IL-38 in the regulation of epidermal cell hyperplasia and pro-tumorigenic microenvironment through IL-1Rrp2/JNK and suggest IL-38/IL-1Rrp2 as a preventive and potential therapeutic target in skin cancer.

Interleukin-37 promotes colitis-associated carcinogenesis via SIGIRR-mediated cytotoxic T cells dysfunction.

Interleukin-37b (hereafter called IL-37) was identified as fundamental inhibitor of natural and acquired immunity. The molecular mechanism and function of IL-37 in colorectal cancer (CRC) has been elusive. Here, we found that IL-37 transgenic (IL-37tg) mice were highly susceptible to colitis-associated colorectal cancer (CAC) and suffered from dramatically increased tumor burdens in colon. Nevertheless, IL-37 is dispensable for intestinal mutagenesis, and CRC cell proliferation, apoptosis, and migration. Notably, IL-37 dampened protective cytotoxic T cell-mediated immunity in CAC and B16-OVA models. CD8+ T cell dysfunction is defined by reduced retention and activation as well as failure to proliferate and produce cytotoxic cytokines in IL-37tg mice, enabling tumor evasion of immune surveillance. The dysfunction led by IL-37 antagonizes IL-18-induced proliferation and effector function of CD8+ T cells, which was dependent on SIGIRR (single immunoglobulin interleukin-1 receptor-related protein). Finally, we observed that IL-37 levels were significantly increased in CRC patients, and positively correlated with serum CRC biomarker CEA levels, but negatively correlated with the CD8+ T cell infiltration in CRC patients. Our findings highlight the role of IL-37 in harnessing antitumor immunity by inactivation of cytotoxic T cells and establish a new defined inhibitory factor IL-37/SIGIRR in cancer-immunity cycle as therapeutic targets in CRC.

Metabolic Syndrome and Psoriasis: Mechanisms and Future Directions.

Psoriasis is an immune-mediated systemic disease with associated comorbidities, including metabolic syndrome (MetS) which contributes substantially to premature mortality in patients with psoriasis. However, the pathological mechanisms underlying this comorbidity are unclear. Studies have shown that the pathological parameters of psoriasis mediate the development of MetS. We reviewed the potential mechanisms which mediate the association between psoriasis and MetS, including endoplasmic reticulum stress, pro-inflammatory cytokine releases, excess production of reactive oxygen species, alterations in adipocytokine levels and gut microbiota dysbiosis. Here, we highlight important research questions regarding this association and offer insights into MetS research and treatment.

Comparison of infarction size, complete ST-segment resolution incidence, mortality and re-infarction and target vessel revascularization between remote ischemic conditioning and ischemic postconditioning in ST-segment elevation myocardial infarction patients undergoing primary percutaneous coronary intervention.

INTRODUCTION: Due to higher morbidity and mortality, ST-segment elevation myocardial infarction (STEMI) causes many public health problems. AIM: To observe effects of remote ischemic conditioning (RIC) and ischemic postconditioning (IPC) on patients diagnosed as STEMI undergoing primary percutaneous coronary intervention (pPCI). MATERIAL AND METHODS: This meta-analysis was conducted using indirect comparison by conducting a network meta-analysis (NMA). We conducted searches by utilizing PubMed and the other databases to identify randomized controlled trials (RCTs) that described IPC or RIC treated patients diagnosed with STEMI during processes of pPCI. Enzymatic infarct size and infarction size were evaluated and cardiac events were assessed during the follow-up. RESULTS: Pooled results showed that lower enzymatic infarction size was associated with the RIC group compared to the IPC group (IPC vs. RIC: standardized mean difference (SMD) = 1.126; 95% confidence interval (CI): 0.756-1.677). Compared with IPC, RIC significantly reduced infarction size, which was assessed using cardiac magnetic resonance (CMR) (SMD = 1.113; 95% CI: 0.674-1.837). We noted a potential toward greater complete ST-segment resolution in RIC patients compared with IPC patients (odds ratio (OR) = 0.821; 95% CI: 0.166-4.051). No significant difference existed in all-cause mortality (OR = 2.211; 95% CI: 0.845-5.784), Target vessel revascularization (TVR) (OR = 0.045; 95% CI: 0.001-.662) or re-infarction (OR = 1.763; 95% CI: 0.741-4.193). CONCLUSIONS: This meta-analysis suggested RIC was correlated with significantly smaller infarction size compared to IPC. No significant superiority between RIC and IPC has been observed in this study on cSTR incidence, mortality and re-infarction or TVR.

[Levels of autoantibodies against AT1-receptor in hypertensive patients with acute coronary syndromes and its role in coronary artery vasoconstriction].

OBJECTIVE: To explore the levels of autoantibodies against AT1-receptor (AT1-AA) in hypertensive patients with acute coronary syndrome (ACS) and observe the in vitro effects of AT1-AA on resting tension of isolated anterior descending artery of vascular ring in male Wistar rats. METHODS: All patients were recruited from June 2007 to August 2008. There were hypertensive patients with ACS (n = 120), those with simple hypertension (n = 253) and those with simple ACS (n = 115). And the outpatients for health examination during the same period were selected as healthy control group (n = 188). The second extracellular loop amino acid sequences of peptides of ATI receptor was synthesized and used as antigen (AT1-Ag) and sialic acid-enzyme-linked immunosorbent assay (SA-ELISA) for detect the serum levels of AT1-AA. Microvascular ring tension technology was used to test the vascular loop resting tension of anterior descending coronary artery from rats induced by a high-fat diet. RESULTS: The positive rates of AT1-AA in patients with simple hypertension (35.2%) and those with simple ACS (30.4%) were significantly higher than those in healthy control group (7.2%, P < 0.01). And the positive rate of AT1-AA in hypertensive patients with ACS (43.3%) was significantly higher than that in those with simple hypertension (35.2%, P < 0.05) and that in healthy control group (7.2%, P < 0.05).Furthermore, AT1-AA increased the vascular loop resting tension of anterior descending coronary artery rings in rats induced by a high-fat diet in a dose-dependant manner. And the vasoconstrictive action of AT1-AA was equal to 46.4% of AngII's action. And such an action was blocked by losartan and antigens. CONCLUSION: The level of AT1-AA increases markedly in hypertensive patients with ACS. And AT1-AA induces vasoconstrictive effects on anterior descending artery rings in rats induced by a high-fat diet.