SMAD2 and renal fibrosis: Studies on NLRP3 revealed suppressed activation of inflammasome and infiltration of macrophage in NLRP3 knock-out db/db mice and attenuated renal fibrosis through the blockage of the expression of profibrotic factors, such as transforming growth factor-β (TGF-β), mothers against decapentaplegic homolog 2 (Smad2), and Smad3 (26).