514-P: Adaptive Downregulation of NLRP3 Inflammasome Expression in Human Renal Tubular Epithelia in the Hyperglycemic and Hyperuricemic Culture

Abstract

Background: Hyperuricemia has been an independent risk factor for diabetic kidney disease. Previous studies showed that hyperuricemia may induce interstitial infiltration of macrophages and activates its NLRP3 inflammasome. Meanwhile, there has been proved that an inner NLRP3 system exists in human tubular epithelia. Here we try to find how glucose and uric acid (UA) affect NLRP3 inflammasome in cultivating tubular epithelia. Methods: HK-2 cells were cultivated. Experiment was designed according to a 2×3×2 multifactorial style. Double glucose concentrations (5.5MM and 25MM) crossed with three escalated UA concentration (0MM, 0.2MM, and 0.4MM), as well as Mcc950 (0MM and 0.1MM), an specific blocker for NLRP3 inflammasome. Morphology of HK-2 cells were observed. Supernatant concentrations and gene expressions of pivotal factors involved in NLRP3 inflammasome pathway including NLRP3, ASC, caspase-1, IL-1β and IL-18 were detected. Results: 1) Morphology: As concentrations of glucose and UA increased, HK-2 cells obviously became floating and fragmental. 2) Genes: Except for Caspase-1, gene expressions of other four components were significantly inhibited in hyperglycemic state. Expressions of five genes were all decreased in euglycemic but unchanged in hyperglycemic state when UA increased. Mcc950 treatment significantly increased gene expressions of NLRP3, ASC, IL-1β and IL-18 in euglycemic but kept them unchanged in hyperglycemic state as UA increased. 3) ELISA: Supernatant IL-1β and IL-18, two effector molecules of NLRP3 inflammasome, were significantly decreased after stimulation with increased glucose or UA cascade. Interestingly, Mcc950 treatment further decreased concentrations of two molecules when UA stepwisely increased. Conclusions: The inner NLRP3 inflammasome counter-regulates effects of hyperglycemia and hyperuricemia. Mcc950 may block the downstream points to reduce IL-1β and IL-18 production directly. Disclosure C. Ciying: None. J. Ran: None. C. Chen: None. P. Zhu: None. R. Tan: None. Y. Liu: None. Funding Guangdong Science and Technology Project Fund (2014B030303002); Guangdong Provincial Academician Workstation Fund (2017B090904027)