PPARγ/CD36信号通路在结核分枝杆菌感染巨噬细胞脂质代谢中的作用

Role of PPARγ/CD36 signaling pathway in macrophage lipid metabolism after Mycobacterium tuberculosis infection

目的探讨过氧化物酶体增殖物激活受体γ(peroxisome proliferator-activated receptorγ,PPARγ)/CD36通路在结核分枝杆菌(Mycobacterium tuberculosis,Mtb)感染巨噬细胞脂质代谢中的作用。方法以THP-1源性巨噬细胞建立感染模型,将实验分为对照组、Mtb组、Mtb+罗格列酮(rosiglitazone,ROZ)组和Mtb+GW9662组。分别采用Western blot和RT-PCR检测巨噬细胞中PPARγ蛋白和基因表达水平;油红O染色法检测细胞内脂质情况;全自动生化分析仪检测细胞培养上清中总胆固醇(total cholesterol,TC)、甘油三酯(triglycerides,TG)、低密度脂蛋白(low density lipoprotein,LDL-C)和高密度脂蛋白(high density lipoprotein,HDL-C)浓度;免疫组织化学法检测细胞中CD36表达;CCK-8检测巨噬细胞增殖率。结果Mtb感染显著升高巨噬细胞中PPARγ表达(P<0.001)、促进细胞内脂质聚集及CD36表达,降低细胞培养上清中TC、TG、LDL-C和HDL-C含量(P<0.001)和细胞增殖率(P<0.001)。PPARγ激动剂ROZ可显著增强Mtb感染所致的细胞内脂质聚集及CD36表达、进一步下调细胞培养上清中脂质水平及各细胞增殖率,而PPARγ拮抗剂GW9662则逆转上述作用。结论PPARγ通过影响CD36表达在Mtb感染巨噬细胞脂质代谢中发挥一定作用。

Objective To investigate the role of peroxisome proliferator-activated receptorγ(PPARγ)/CD36 signaling pathway in macrophage lipid metabolism after Mycobacterium tuberculosis(Mtb)infection.Methods THP-1-derived macrophages were infected with Mtb.Four groups were included in this study,which were control group,Mtb infection group,Mtb+rosiglitazone(ROZ,PPARγagonist)group and Mtb+GW9662(PPARγantagonist)group.Western blot and RT-PCR were used to detect the expression of PPARγin macrophages at protein and mRNA levels,respectively.The lipids in cells were detected by oil red O staining.The concentrations of total cholesterol(TC),triglycerides(TG),low density lipoprotein(LDL-C)and high density lipoprotein(HDL-C)in the supernatant of cell culture were detected by automatic biochemical analyzer.The expression of CD36 was detected by immunohistochemistry.CCK-8 was used to detect the proliferation rate of macrophages.Results Mtb infection significantly increased the expression of PPARγin macrophages(P<0.001),promoted intracellular lipid aggregation and CD36 expression and decreased the levels of TC,TG,LDL-C and HDL-C in the supernatant of cell culture(P<0.001)and cell proliferation rate(P<0.001).PPARγagonist significantly enhanced the intracellular lipid accumulation and CD36 expression that were induced by Mtb infection and down-regulated the lipid level in the supernatant of cell culture and cell proliferation rate,while PPARγantagonist reversed the above effects.Conclusions PPARγplayed a role in lipid metabolism in Mtb-infected macrophages through affecting CD36 expression.