Uric acid promotes renal tubule epithelial-mesenchymal transition via activation of nucleotide-binding oligomerization domain-like receptor protein-3 inflammasome

Objective To investigate the effect and mechanism of uric acid on epithelial-mesenchymal transition of human renal tubular epithelial cells（HK-2 cells）. Methods HK-2 cells were cultured in vitro and treated with different concentrations of uric acid for different duration. The morphological changes of HK-2 cells were observed. Western blot was performed to detect the expression of α-smooth muscle actin（α-SMA）, E-cadherin, nucleotide-binding oligomerization domain-like receptor protein 3（NLRP3）, apoptosis-associated speck-like protein（ASC） and Caspase-1. Enzyme-linked immunosorbent assay（ELISA） was used to analyze the expression of interleukin-1β（IL-1β）. NLRP3 inhibitor MCC950 was also added to detect whether it could affect the proteins expression under the optimal concentration and duration of uric acid treatment. Results With the increasing concentration of uric acid, the morphology of HK-2 cells changed from cube to strip. The expressions of α-SMA, NLRP3, ASC and Caspase-1 gradually increased（P＜0.05） with the concentration and duration increment of uric acid, while the expression of E-cadherin gradually decreased（P＜0.05）. The expression of IL-1β gradually increased under the higher concentration 0, 0.1, 0.2, 0.4, 0.8 mmol/L:（9.56±1.47） vs（12.28±2.32） vs（14.89±1.23） vs（21.41±2.55） vs（26.60±3.97）ng/L, F=38.56, P＜0.05 and longer incubation time 0, 12, 24, 48, 72 h:（8.90±2.14） vs（10.97±1.12） vs（15.27±1.63） vs（22.43±3.91） vs（31.09±3.34）ng/L, F=59.13, P＜0.05 of uric acid. Compared with uric acid group, the expressions of α-SMA, NLRP3, ASC and Caspase-1 decreased in uric acid+MCC950 group（P＜0.05）, the expression of IL-1β decreased in uric acid+MCC950 group （21.67±2.71） vs（28.96±3.05）ng/L, t=3.99, P＜0.01, while the expression of E-cadherin increased（P＜0.05）. Conclusion Our study suggests that uric acid may promote renal tubule epithelial-mesenchymal transition via activation of NLRP3 inflammasome.