Ma Jing, Xu Yun, Zhang Min, Li Yi
Infectious Disease Department, The Second XIANGYA Hospital of Central South University, Changsha, Hunan, China.
Infectious Disease Department, The Second XIANGYA Hospital of Central South University, Changsha, Hunan, China.
Biochem Pharmacol. 2023 Apr;210:115467. doi: 10.1016/j.bcp.2023.115467. Epub 2023 Feb 26.
Geraniol (Ger), a natural acyclic monoterpene alcohol, has been reported to exert protective effects through anti-inflammation in Acute liver failure (ALF). However, its specific roles and precise mechanisms underlying anti-inflammatory effects in ALF have not yet fully explored. We aimed to investigated the hepatoprotective effects and mechanisms of Ger against ALF induced by lipopolysaccharide (LPS)/D-galactosamine (GaIN). In this study, the liver tissue and serum of LPS/D-GaIN-induced mice were collected. The degree of liver tissue injury was evaluated by HE and TUNEL staining. Serum levels of liver injury markers (ALT and AST) and inflammatory factors were measured by ELISA assays. PCR and western blotting were conducted to determine the expression of inflammatory cytokines, NLRP3 inflammasome-related proteins, PPAR-γ pathway-related proteins, DNA Methyltransferases and M1/M2 polarization cytokines. Immunofluorescence staining was used to assess the localization and expression of macrophage markers (F4/80 and CD86), NLRP3 and PPAR-γ. In vitro experiments were performed in macrophages stimulated with LPS with or without IFN-γ. Purification of macrophages and cell apoptosis was analyzed using flow cytometry. We found that Ger effectively alleviated ALF in mice, specified by the attenuation of liver tissue pathological damage, inhibition of ALT, AST and inflammatory factor levels, and inactivation of NLRP3 inflammasome. Meanwhile, downregulation M1 macrophage polarization may involve in the protective effects of Ger. In vitro, Ger reduced the activation of NLRP3 inflammasome and apoptosis through regulating PPAR-γ methylation by inhibiting M1 macrophage polarization. In conclusion, Ger protects against ALF through suppressing NLRP3 inflammasome-mediated inflammation and LPS-induced macrophage M1 polarization via modulating PPAR-γ methylation.
香叶醇（Ger）是一种天然的无环单萜醇，据报道其可通过抗炎作用对急性肝衰竭（ALF）发挥保护作用。然而，其在ALF中的具体作用以及抗炎作用的精确机制尚未得到充分研究。我们旨在研究香叶醇对脂多糖（LPS）/D-半乳糖胺（GaIN）诱导的ALF的肝保护作用及机制。在本研究中，收集了LPS/D-GaIN诱导小鼠的肝组织和血清。通过苏木精-伊红（HE）和末端脱氧核苷酸转移酶介导的缺口末端标记（TUNEL）染色评估肝组织损伤程度。采用酶联免疫吸附测定（ELISA）法检测肝损伤标志物（谷丙转氨酶和谷草转氨酶）及炎症因子的血清水平。进行聚合酶链反应（PCR）和蛋白质免疫印迹法以测定炎症细胞因子、NLRP3炎性小体相关蛋白、过氧化物酶体增殖物激活受体γ（PPAR-γ）途径相关蛋白、DNA甲基转移酶以及M1/M2极化细胞因子的表达。采用免疫荧光染色评估巨噬细胞标志物（F4/80和CD86）、NLRP3和PPAR-γ的定位及表达。在有或无干扰素-γ刺激的LPS刺激的巨噬细胞中进行体外实验。使用流式细胞术分析巨噬细胞的纯化及细胞凋亡情况。我们发现香叶醇可有效减轻小鼠的ALF，表现为肝组织病理损伤减轻、谷丙转氨酶、谷草转氨酶及炎症因子水平受到抑制以及NLRP3炎性小体失活。同时，M1巨噬细胞极化的下调可能参与了香叶醇的保护作用。在体外，香叶醇通过抑制M1巨噬细胞极化调节PPAR-γ甲基化，从而降低NLRP3炎性小体的激活及细胞凋亡。总之，香叶醇通过调节PPAR-γ甲基化抑制NLRP3炎性小体介导的炎症反应和LPS诱导的巨噬细胞M1极化，从而对ALF起到保护作用。
