Hsa-Mir-203/Myd88 Axis Mediates The Protective Effect Of Hispidulin On Lps-Induced Apoptosis In A Human Renal Tubular Epithelial Line, Hk-2

Acute kidney injury (AKI), commonly occurring as complications of sepsis, cardiac surgery, and liver or kidney transplantation, is a critical care syndrome. It is well known that lipopolysaccharide (LPS) shock is a common triggering factor for AKI. This study is aimed to examine the effect of flavonoid compound hispidulin on LPS-induced AKI. For this, renal tubular epithelial cell HK-2 was treated with LPS to establish an in vitro model of AKI. The effect of hispidulin on HK-2 cell viability was examined using CCK-8 assay. Cell apoptosis was determined by TUNEL and flow cytometry. Apoptosis marker proteins were determined by using western blot. The levels of pro-inflammatory cytokines were determined by ELISA assay and qRT-PCR. The translocation of NF-kappa B was determined by western blot. The effect of MyD88 on the cytoprotective activities of hispidulin was examined by overexpressing MyD88 in HK-2 cells. Our results showed that hispidulin was not able to produce a cytotoxic effect on HK-2 cells at tested concentrations. However, hispidulin could protect HK-2 cells from LPS-induced cell injury. Our results also showed that hispidulin was able to attenuate LPS-induced HK-2 cell apoptosis. In addition, LPS led to an inflammatory response in HK-2 cells, evidenced by NF-kappa B p65 activation as well as increased expression and release of inflammatory cytokine IL-6 and TNF-alpha, which could be reversed by pretreatment with hispidulin. Overexpression MyD88 was found to significantly dampen the cytoprotective activities of hispidulin against LPS insult. More importantly, MyD88 was identified as a direct target of hsa-miR-203, and hispidulin was found to regulate the expression of MyD88 via upregulating hsa-miR-203. Our results showed that hispidulin attenuates LPS-induced HK-2 damage via regulating hsa-miR-203/MyD88 axis.