目的 探讨甜菜碱对二甲基亚硝胺（DMN）致肝硬化大鼠的作用及机制。方法 将 40 只雄性 Wistar 大鼠随机分为正常组、模型组、易善复组（141.8 mg•kg-1）及甜菜碱低、高剂量组（100、400 mg•kg-1），每组 8 只。给予 0.5% DMN 溶液（2 mL•kg-1）腹腔注射复制肝硬化大鼠模型。灌胃给药，每天 1 次，持续 2 周。采用全自动生化分析仪检测血清丙氨酸氨基转移酶（ALT）活性；HE、天狼星红（SR）染色法观察肝脏组织病理变化；免疫组化法检测肝组织中 α-SMA、F4/80、CD68 表达情况；碱水解法测定肝组织中羟脯氨酸（Hyp）含量；Western Blot 法检测肝组织中 α-SMA、NLRP3、pro-Caspase1、IL-18 蛋白表达水平；Real-time qPCR 法检测肝组织中纤维化及炎症相关基因的表达水平。结果 与正常组比较，模型组大鼠肝小叶结构破坏，肝细胞肿胀坏死，伴有大量炎性细胞浸润，血清 ALT 水平显著升高（P＜0.01）；肝组织有大量胶原沉积，胶原阳性面积比及 Hyp 含量显著升高（P＜0.01）；肝组织中 F4/80、CD68 阳性面积比及 F4/80、CD68、TNF-α mRNA 表达水平均显著升高（P＜0.01）；肝组织纤维间隔有大量 α-SMA 阳性表达，α-SMA 阳性面积比及蛋白表达水平显著升高（P＜0.01），Acta2、Col1a1、TGF-β1 mRNA 表达显著上调（P＜0.01）；肝组织中 NLRP3、pro-Caspase1、IL-18 蛋白表达水平及 NLRP3、IL-1β、IL-18 mRNA 表达水平均显著升高（P＜0.01）。与模型组比较，甜菜碱低、高剂量组大鼠肝组织损伤及炎性细胞浸润均有不同程度改善，且甜菜碱高剂量组的血清 ALT 水平明显降低（P＜0.05）；甜菜碱低、高剂量组肝组织胶原沉积有不同程度减轻，胶原阳性面积比及 Hyp 含量显著下降（P＜0.05，P＜0.01）；肝组织中 F4/80、CD68 阳性面积比及 F4/80、CD68、TNF-α mRNA 表达水平均显著降低（P＜0.05，P＜0.01）；肝组织 α-SMA 阳性面积比及蛋白表达水平显著降低（P＜0.05，P＜0.01），Acta2、Col1a1、TGF-β1 mRNA 表达显著下调（P＜0.05，P＜0.01）；肝组织中 NLRP3、pro-Caspase1、IL-18 蛋白表达水平及 NLRP3、IL-1β、IL-18 mRNA 表达水平均显著降低（P＜0.05，P＜0.01）。结论 甜菜碱能明显减轻DMN 诱导的肝硬化大鼠肝组织炎性损伤、肝星状细胞活化及胶原沉积，其作用机制可能与抑制 NLRP3 炎症小体信号通路有关。

Objective To investigate the effect and mechanism of betaine on dimethylnitrosamine （DMN）-induced liver cirrhosis in rats. Methods Forty male Wistar rats were randomly divided into normal group， model group， Yishanfu （141.8 mg•kg-1 ） group，low- and high- dose （100，400 mg•kg-1 ） betaine groups，with eight rats in each group. A rat model of liver cirrhosis was replicated by intraperitoneally injected with 0.5% DMN solution （2 mg•kg-1 ）. Then the corresponding drugs were given orally once a day for two weeks. The activity of alanine aminotransferase （ALT） in serum was detected by biochemical analyzer. The pathological changes of liver tissue were observed by hematoxylin-eosin （HE） staining and Sirius red （SR） staining. The positive expressions of α -SMA，F4/80 and CD68 in liver tissue were determined by immunohistochemistry. The content of hydroxyproline （Hyp） in liver tissue was determined by alkaline hydrolysis method. Western Blot was used to determine the protein expressions of α-SMA，NLRP3，pro-Caspase1 and IL-18. The mRNA expression levels of fibrosis-related and inflammation-related genes in liver tissue were detected by real-time fluorescence quantitative polymerase chain reaction （qPCR） . Results Compared with the normal group，the structure of hepatic lobule of the rats in the model group was damaged. Also，the liver cells were swollen and necrotic，with a large amount of inflammatory cell infiltration. Serum ALT level was significantly increased （P＜0.01）. A large amount of collagen deposition in liver tissue was observed，Hyp content and percentage of collagen positive area were significantly increased （P＜0.01）. The percentage of positive area of F4/80 and CD68，as well as the mRNA expressions of F4/80，CD68 and TNF-α in liver tissue were significantly increased （P＜0.01）. Large amounts of α-SMA positive expression were found in fibrous septum of liver tissue. The percentage of positive area and protein expression of α -SMA were obviously increased （P＜0.01）. The mRNA levels of Acta2， Col1a1， TGF- β1 were significantly up-regulated （P＜0.01）. Moreover，the protein expression of NLRP3，pro-Caspase1 and IL-18，as well as the mRNA levels of NLRP3，IL-1β，and IL-18 of liver tissue were obviously increased （P＜0.01）. Compared with the model group，liver tissue and inflammatory cell infiltration in low- and high- dose betaine groups were improved to varying degrees， and serum ALT level in high-dose betaine group was obviously decreased （P＜0.05）. Collagen deposition in liver tissue of low- and high- dose betaine groups was reduced，Hyp content and percentage of collagen positive area were significantly decreased （P＜0.05，P＜0.01）. The percentage of positive area of F4/80 and CD68， as well as the mRNA expressions of F4/80，CD68 and TNF-α in liver tissue were significantly decreased （P＜0.05， P＜0.01）. The percentage of positive area and protein expression of α-SMA were obviously decreased （P＜0.05，P＜0.01）. The mRNA levels of Acta2，Col1a1，TGF-β1 were significantly down-regulated （P＜0.05，P＜0.01） . The protein expression of NLRP3，pro-Caspase1 and IL-18，as well as the mRNA levels of NLRP3，IL-1β，and IL-18 of liver tissue were obviously decreased （P＜0.05，P＜0.01）. Conclusion Betaine can alleviate inflammatory damage in liver tissue of DMN-induced cirrhotic rats，inhibit the activation of hepatic stellate cells （HSC），and reduce collagen deposition. The mechanism may be related to inhibition of NLRP3 inflammasome signaling pathway.

R285.5

国家自然科学基金重点项目（82130120）