Abstract

To evaluate the effect of isorhamnetin on diabetic kidney disease and elucidate its underlying mechanisms. A high glucose-stimulated mouse podocyte (MPC-5) model was employed to evaluate the effects of isorhamnetin on podocyte injury, secretion of inflammatory cytokines, NLRP3 inflammasome activation, pyroptosis, mitochondrial function, cytosolic release of mtDNA, and activation of the cGAS-STING signaling pathway. Nigericin (an NLRP3 activator) and siRNA were used in combination to clarify the regulatory relationships between these pathways. Furthermore, a mouse model of diabetic kidney disease was established and treated with isorhamnetin via intragastric administration. Blood glucose and renal function parameters were measured, renal histopathological changes were examined, and alterations in podocyte marker proteins, inflammasome activation, pyroptosis, mitochondrial damage, and the cGAS-STING pathway in kidney tissues were analyzed. Isorhamnetin alleviated high glucose-induced abnormalities in podocyte marker proteins and cellular injury. It also inhibited NLRP3 inflammasome activation, thereby attenuating pyroptosis. Furthermore, isorhamnetin stabilized mitochondrial membrane potential, decreased mitochondrial ROS production, suppressed excessive opening of the mitochondrial permeability transition pore, alleviated mitochondrial damage, and reduced cytosolic mtDNA release, which in turn suppressed activation of the cGAS-STING pathway. Knockdown of STING inhibited high glucose-induced NLRP3-dependent pyroptosis. Consistently, isorhamnetin improved renal function in mice with diabetic kidney disease, attenuated glomerulosclerosis and fibrosis, and markedly suppressed mitochondrial damage, mtDNA leakage, cGAS-STING activation, and NLRP3-mediated pyroptosis and inflammatory responses in renal tissues.