Toll样受体4信号激动对脂肪细胞肾素-血管紧张素系统的影响

摘要

目的：探讨Toll样受体4（TLR4）信号通路在脂肪细胞肾素-血管紧张素系统(RAS)激活的参与机制。方法诱导3T3-L1细胞分化为脂肪细胞，予TLR4特异性激动剂LPS干预，分为对照组、10、100、1000 ng/ml LPS组，应用RT-PCR法、Western-blot法测定TLR4、AGT、ATlR mRNA及蛋白表达并使用免疫荧光双染色法观察NF-κB p65亚基核转位变化；另设10μmol/L厄贝沙坦（AT1R阻滞剂）预处理+100 ng/ml LPS组，观察NF-κB p65亚基核转位情况。结果 LPS干预呈时间依赖性及浓度依赖性升高3T3-L1脂肪细胞TLR4、AGT和AT1R的mRNA表达水平；LPS干预12 h后，TLR4、AGT、AT1R蛋白表达亦呈浓度依赖性升高；各浓度LPS处理组NF-κB p65亚基核转位较对照组明显增强，而10μmol/L厄贝沙坦预处理减弱该效应。结论 TLR4信号通路激活后，上调AGT与AT1R的mRNA及蛋白表达，并激活NF-κB；预先阻断RAS减弱NF-κB的激活。提示TLR4信号激动可激活脂肪细胞局部RAS。%Objective To investigate the role of Toll-like receptor 4 (TLR4) signaling pathway in the activation of rennin-angiotensin system (RAS) in adipose cells. Methods 3T3- L1 cells induced with isobutylmethylxanthine, insulin and dexamethasone to differentiate into adipocytes were stimulated by LPS with or without irbesartan pretreatment. The expression levels of TLR4, angiotensinogen (AGT) and angiotensin II receptor type 1 (ATlR) mRNA in 3T3-L1 cells was determined by RT-PCR, and their protein expressions were detected with Western-blotting. Immunofluorescence double staining was used to observe the traslocation of NF-κB p65 subunit in the cells. Results Stimulation with LPS dose-and time-dependently increased the mRNA and protein expressions of TLR4, AGT and AT1R. LPS exposure resulted in enhanced translocation of NF-κB p65 subunit in the adipose cells, which was attenuated by irbesartan pretreatment. Conclusion Activation of TLR4 signaling pathway may trigger the activation of local RAS in adipose cells.