High Glucose And Angiotensin Ⅱ Costimulated The Expression Of Inflammatory Factors Via Modulation Of TLR4Pathway In Rat Mesangial Cells

Objective：To investigate whether there are synergistic action of combined use ofhigh glucose and angiotensin Ⅱon the expression of TLR4and activation of itsdownstream signaling cascade. To investigate whether the expression of TLR4downregulated by irbesartan intervention. To investigate whether angiotensinⅡis a ligandof TLR4and the synergistic relationship between AT1R and TLR4.Method：The research object was rat glomerular mesangial cells (HBZY-1). Thecells were divided into groups after serum-starved for24hours synchronization asfollows: normal control group (5.6mM D-glucose), high glucose group (25mMD-glucose), Angiotensin Ⅱ(10-7M) group, high glucose+Angiotensin Ⅱgroup,Angiotensin Ⅱ+AT1R blocker Irbesartan (10-5M) groulp, Angiotensin Ⅱ+Irbesartan+TLR4blocker（10ug/ml）group. Cells were collected and the expressionof TLR4, MyD88mRNA were detected by Real-time PCR, and the expression ofTLR4, MyD88protein were detected by Western blot,. The cell supernatant wascollected for detecting the expression of IL-6、MCP-1by ELISA.Result：Compared to control group, the expression of TLR4and MyD88mRNA forHBZY-1cells, exposed to25mM high glucose and10-7M Angiotensin II, incresesdobviously after12hours, and after24hours, the expression of IL-6and MCP-1werealso increased significantly (P＜0.01). For HBZY-1cells con-stimulated by highglucose and angiotensin Ⅱ,the expression of TLR4mRNA did not observe furtherincrease compared to high glucose group or Ang Ⅱgroup. But the downstream factorMyD88mRNA and protein,and the expression of inflammatory factors MCP-1andIL-6were increased significantly (P＜0.01). Irbesartan can down-regulate TLR4signaling pathway stimulated by Ang Ⅱ. Irbesartan, combined with TLR4blockerintervented HBZY-1, can further down regulate the expression of MyD88and itsdownstream factors.Conclusion：1. High glucose and Ang Ⅱ can induce the expression of inflammatory factorsvia the TLR4/MyD88signaling pathway, and have synergistic action. Angiotensin Ⅱ may be a ligand of TLR4.2. Irbesartan down-regulated the expression of inflammatory factors by blockingthe expression of TLR4. we speculate that it has synergistic relationship betweenTLR4and AT1R in cell signal transduction.