ABCA1 deficiency contributes to podocyte pyroptosis priming via the APE1/IRF1 axis in diabetic kidney disease
Marie Ito, Gloria Michelle Ducasa, Judith Molina, Javier Varona Santos, Shamroop Kumar Mallela, Jin‐Ju Kim, Mengyuan Ge, Alla Mitrofanova, Alexis Sloan, Sandra Merscher, Imari Mimura, Alessia Fornoni
Abstract
Decreased ATP Binding Cassette Transporter A1 (ABCA1) expression and caspase-4-mediated noncanonical inflammasome contribution have been described in podocytes in diabetic kidney disease (DKD). To investigate a link between these pathways, we evaluated pyroptosis-related mediators in human podocytes with stable knockdown of ABCA1 (siABCA1) and found that mRNA levels of IRF1, caspase-4, GSDMD, caspase-1 and IL1β were significantly increased in siABCA1 compared to control podocytes and that protein levels of caspase-4, GSDMD and IL1β were equally increased. IRF1 knockdown in siABCA1 podocytes prevented increases in caspase-4, GSDMD and IL1β. Whereas TLR4 inhibition did not decrease mRNA levels of IRF1 and caspase-4, APE1 protein expression increased in siABCA1 podocytes and an APE1 redox inhibitor abrogated siABCA1-induced expression of IRF1 and caspase-4. RELA knockdown also offset the pyroptosis priming, but ChIP did not demonstrate increased binding of NFκB to IRF1 promoter in siABCA1 podocytes. Finally, the APE1/IRF1/Casp1 axis was investigated in vivo. APE1 IF staining and mRNA levels of IRF1 and caspase 11 were increased in glomeruli of BTBR ob/ob compared to wildtype. In conclusion, ABCA1 deficiency in podocytes caused APE1 accumulation, which reduces transcription factors to increase the expression of IRF1 and IRF1 target inflammasome-related genes, leading to pyroptosispriming.