NLR family pyrin domain containing 3 (NLRP3) inflammasome accompanies chronic liver injury and is a critical mediator of inflammation-driven liver fibrosis. Sphingosine 1-phosphate (S1P)/S1P Receptor (S1PR) signaling participates in liver fibrogenesis by affecting bone marrow (BM)-derived monocytes/macrophage (BMM) activation. However, the relationship between S1P/S1PR signaling and NLRP3 inflammasome in BMMs remains unclear. Here, we found significantly elevated gene expression of NLRP3 inflammasome components (NLRP3, pro-interleukin-1β, and pro-interleukin-18) and the activation of NLRP3 inflammasome significantly elevated during murine chronic liver injury induced by a bile duct ligation operation, a methionine-choline–deficient and high-fat diet, or carbon tetrachloride intraperitoneal injection. Moreover, the increased expression of sphingosine kinase 1 (SphK1), the rate-limiting synthetic enzyme of S1P, was positively correlated with NLRP3 inflammasome components in both patients and mouse model livers. Flow cytometry analysis and immunofluorescence staining showed BMMs contributed to the significant proportion of NLRP3⁺ cells in murine inflammatory livers, but not Kupffer cells, dendritic cells, endothelial cells, T cells, and hepatocytes. Focusing on macrophages, S1P promoted NLRP3 inflammasome priming and activation in a dose-dependent manner. Blockade of S1PR₂ by JTE-013 (antagonist of S1PR₂) or S1PR₂-siRNA inhibited S1P-induced NLRP3 inflammasome priming and inflammatory cytokine (interleukin-1β and interleukin-18) secretion, whereas blockade of S1PR₁ or S1PR₃ had no such effect. in vivo, a β1,3-d-glucan-encapsulated siRNA particle (GeRP) delivery system is capable of silencing genes in macrophages specifically. Treatment with S1PR₂ siRNA-GeRPs markedly reduced NLRP3 inflammasome priming and activation and attenuated liver inflammation and fibrosis. Together, the conclusions indicated that targeting macrophage S1PR₂ retarded liver inflammation and fibrogenesis via downregulating NLRP3 inflammasome, which may represent an effective therapeutic strategy for chronic liver injury.

包含3（NLRP3）炎性小体的NLR家族吡啶结构域伴随着慢性肝损伤，并且是炎症驱动的肝纤维化的关键介质。1-磷酸鞘氨醇（S1P）/ S1P受体（S1PR）信号传导通过影响源自骨髓（BM）的单核细胞/巨噬细胞（BMM）的激活而参与肝纤维化。然而，尚不清楚BMM中S1P / S1PR信号传导与NLRP3炎性小体之间的关系。在这里，我们发现胆管结扎手术致小鼠慢性肝损伤期间，NLRP3炎性小体成分（NLRP3，pro-interleukin-1β和pro-interleukin-18）的基因表达显着升高，而NLRP3炎性小体的激活显着升高。缺乏蛋氨酸和高脂饮食，或腹腔注射四氯化碳。此外，S1P的限速合成酶鞘氨醇激酶1（SphK1）的表达增加与患者和小鼠模型肝中的NLRP3炎性体成分呈正相关。流式细胞仪分析和免疫荧光染色显示BMM占NLRP3的显着比例鼠炎症性肝脏中的⁺细胞，但不是库普弗细胞，树突状细胞，内皮细胞，T细胞和肝细胞。专注于巨噬细胞，S1P以剂量依赖的方式促进了NLRP3炎性体的引发和激活。S1PR的封锁₂由JTE-013（S1PR的拮抗剂₂）或S1PR ₂ -siRNA抑制S1P诱导的炎性NLRP3引发和炎性细胞因子（白介素1β和IL-18）的分泌，而S1PR的封锁₁或S1PR ₃没有这样的效果。体内，β1,3-d-葡聚糖包裹的siRNA粒子（GeRP）传递系统能够使巨噬细胞中的基因沉默。用S1PR ₂ siRNA-GeRPs处理可显着减少NLRP3炎性体引发和激活，并减轻肝脏炎症和纤维化。总之，这些结论表明，靶向巨噬细胞S1PR ₂通过下调NLRP3炎性体来延迟肝脏炎症和纤维化，这可能代表了慢性肝损伤的有效治疗策略。