Angiotensin II Increases Oxidative Stress and Induces Glomerular Sclerosis via Toll-like Receptor 4

Background: Angiotensin II (AngII) increases reactive oxygen species (ROS) and induces glomerular sclerosis. Toll-like receptor 4 (TLR4)-mediated inflammation enhances the renal impairment in renal inflammatory diseases. The relationship between TLR4 and AngII-induced glomerular sclerosis is unknown. Methods: Mice lacking TLR4 function (Tlr4) and wild-type (WT) mice were randomized into groups treated with AngII, norepinephrine (NE) or a sub-depressor dose of the AngII receptor blocker irbesartan along with AngII for 2 weeks. We then assessed the expressions of NADPH oxidase and monocyte chemoattractant protein-1 (MCP-1) and the inflammatory cell recruitment in the glomeruli. We also evaluated the mesangial matrix proliferation and ROS. Results: AngII and NE equally increased the systolic blood pressure compared to the control mice (p<0.05). In the WT mice treated with AngII, we observed glomerular sclerosis, an increase in NADPH oxidase, MCP-1 and the infiltration of macrophages as well as ROS content in the glomeruli compared to the control mice (p<0.05), whereas the Tlr4 mice showed little effects of AngII on these indices. In addition, the sub-depressor-dose irbesartan treatment reversed these changes. NE had little effects on these indices. Conclusions: TLR4 plays an important role in AngII-induced oxidative stress, inflammation and glomerular sclerosis through the AT1 receptor.