HIF-1α contributes to Ang II-induced inflammatory cytokine production in podocytes

BACKGROUND: Studies have indicated that changed expression of hypoxia-inducible factor-1α (HIF-1α) in epithelial cells from the kidney could affect the renal function in chronic kidney disease (CKD). As Angiotensin II (Ang II) is a critical active effector in the renin-angiotensin system (RAS) and was proved to be closely related to the inflammatory injury. Meanwhile, researchers found that Ang II could alter the expression of HIF-1α in the kidney. However, whether HIF-1α is involved in mediating Ang II-induced inflammatory injury in podocytes is not clear. METHODS: Ang II perfusion animal model were established to assess the potential role of HIF-1α in renal injury in vivo. Ang II stimulated podocytes to observe the corresponding between HIF-1α and inflammatory factors in vitro. RESULTS: The expression of inflammatory cytokines such as MCP-1 and TNF-α was increased in the glomeruli from rats treated with Ang II infusion compared with control rats. Increased HIF-1α expression in the glomeruli was also observed in Ang II-infused rats. In vitro, Ang II upregulated the expression of HIF-1α in podocytes. Furthermore, knockdown of HIF-1α by siRNA decreased the expression of MCP-1 and TNF-α. Moreover, HIF-1α siRNA significantly diminished the Ang II-induced overexpression of HIF-1α. CONCLUSION: Collectively, our results suggest that HIF-1α participates in the inflammatory response process caused by Ang II and that downregulation of HIF-1α may be able to partially protect or reverse inflammatory injury in podocytes.