西罗莫司预处理减轻大鼠肝脏缺血再灌注损伤的作用及其机制

目的 探讨西罗莫司(SRL)预处理减轻大鼠肝脏缺血再灌注损伤的作用及其机制.方法 将SD大鼠随机分为4组,每组12只.假手术对照组:开腹后仅用生理盐水纱布覆盖切口60min,关腹;假手术SRL组:手术方式同假手术对照组;实验对照组:开腹后夹闭肝门静脉左支、肝动脉左支及左肝管,60 min后开放血管;实验SRL组:手术方式同实验对照组.两SRL组大鼠术前2周开始给予SRL 2 mg·kg~(-1)·d~(-1)灌胃,术前6 h加用1次.而两对照组同期仅给予等体积无菌生理盐水灌胃.术后24 h分别采集各组大鼠的血液和肝组织,检测血清丙氨酸转氨酶(ALT)和天冬氨酸转氨酶(AST)水平,光镜下观察肝组织的病理学变化,采用流式细胞术检测肝组织中CD4~+ CD25~+ T淋巴细胞占单个核细胞的比例.采用实时聚合酶链反应检测肝组织中Foxp3 mRNA的表达,采用酶联免疫吸附试验检测血清巾转化生长因子-β(TGF-β)和白细胞介素10(IL-10)的含量.结果 假手术对照组和假手术SRL组血清ALT和AST均处于较低水平,而实验SRL组和实验对照组明显升高,且实验SRL组低于实验对照组(P<0.05).假手术对照组和假手术SRL组肝组织结构正常,实验对照组可见明显的片状坏死,实验SRL组肝小叶结构基本完整,未见明显细胞坏死.假手术对照组、假手术SRL组、实验对照组和实验SRL组CD4~+ CD25~+ T淋巴细胞占单个核细胞的比例分别为(6.12±1.87)%、(22.36±6.75)%、(4.53±1.02)%和(13.29±3.16)%.假手术SRL组Foxp3 mRNA的相对表达量以及血清中TGF-β和IL-10的含量明显高于假手术对照组(P<0.05),实验SRL组明显高于实验对照组(P<0.05).结论 SRL可以减轻大鼠肝脏缺血再灌注损伤,其机制可能与SRL诱导体内CD4~+ CD25~+ Foxp3~+ 调节性T淋巴细胞的分化以及增加TGF-β和IL-10的分泌抑制炎症反应有关.

Protective mechanism of sirolimus pretreatment against liver ischemia-reperfusion injury in rats

Objective To investigate the protective effect of sirolimus pretreatment against liver ischemia-reperfusion(I/R)injury in rat model and the possible mechanism.Methods Forty-eight male SD rats were randomized into four groups (12/group):A:sham group with saline,B:sham group with sirolimus,C:saline-operated group,D:sirolimus-operated group.The rats were pretreated with either saline or sirolimus (2 mg·kg~(-1)·d~(-1))by oral gavage for two weeks．The rat partial liver model of I/R injury was established,and the samples were collected at the 24th h after the I/R The serum ALT and AST levels were determined,the histologic changes were observed by HE staining under the light microscopy,the frequency of CD4~+ CD25~+ T cells among mononuclear cells in liver tissue was analyzed by using flow cytometry,the expression of Foxp3 mRNA was detected in liver tissue by real-time PCR,and the serum TGF-β,IL-10 levels were measured by enzyme-linked immunosorbent assay (ELISA).Results Serum ALT and AST levels were significantly decreased and the histological damage was significantly alleviated in the sirolimus-operated group as compared with saline-operated group(P<0.05).The percentage of CD4~+ CD25~+ T cells among mononuclear cells in groups A,B,C,and D was(6.12±1.87)%,(22.36±6.75)%,(4.53±1.02)% and(13.29±3.16)% respectively in liver tissue The expression levels of the Foxp3 mRNA were significantly higher in sirolimus group than in saline group(P<0.05).The ELISA showed that sirolimus could significantly increase the levels of TGF-β and IL-H)(P<0.05).Conclusion Pretreatment of sirolimus can effectively protect against liver ischemia-reperfusion injury in rats,which may be related to induction of CD4~+ CD25~+ Foxp3~+ T regulator cells by sirolimus,and the increase of TGF-β and IL-10 secretion to inhibit the imflammatory response.