[Mechanism of Qizhi Jiangtang capsule inhibits podocyte pyroptosis to improve kidney injury in diabetes nephropathy by regulating NLRP3/caspase-1/GSDMD pathway].

Objective To investigate the impact of Qizhi Jiangtang Capsule (QZJT) on renal damage in diabetic nephropathy (DN) mice via NOD like receptors family pyrin domain containing 3/caspase-1/ Gasdermin D (NLRP3/caspase-1/GSDMD) signaling pathway. Methods Mice were randomly allocated into six experimental groups: a normal control group (NC), a diabetic nephropathy model group (DN), a low-dose QZJT treatment group (L-QZJT), a high-dose QZJT treatment group (H-QZJT), a positive control group administered Shenqi Jiangtang Granules (SQJT), and an ML385 group (treated with an inhibitor of nuclear factor erythroid 2-related factor 2, Nrf2). Upon successful model induction, therapeutic interventions were commenced. Renal function impairment in the mice was evaluated through quantification of fasting blood glucose (FBG), 24-hour urinary albumin (UAlb), serum creatinine (SCr), blood urea nitrogen (BUN), and the kidney-to-body mass ratio (K/B). Renal tissue pathology was evaluated using HE and PAS staining. Serum levels of inflammatory cytokines IL-1β and IL-18 were quantified by ELISA. Levels of podocyte markers and proteins involved in relevant pathways were assessed using Western blot analysis. Results Compared with the NC group, FBG, 24 h UAlb, SCr, and BUN were increased in the DN group, and the K/B mass ratio was also increased. In contrast, compared with the DN group, FBG, 24 h UAlb, SCr, and BUN in both the low-dose (L-QZJT) and high-dose Quanzhou Jintang (H-QZJT) groups were decreased, and the K/B mass ratio was decreased as well. The therapeutic efficacy of H-QZJT was comparable to that of Shenqi Jiangtang Granules. QZJT ameliorated renal histopathological injury in DN mouse, increased the protein levels of Nephrin (a podocyte marker), and decreased the protein levels of NLRP3, apoptosis-associated speck-like protein containing CARD (ASC), pro-caspase-1, and GSDMD-N. After ML385 treatment, renal cells exhibited swelling and morphological changes, the inflammatory infiltrate area was enlarged, the protein levels of NLRP3, ASC, pro-caspase-1, and GSDMD-N were up-regulated, and the levels of IL-1β and IL-18 were increased. Conclusion QZJT may inhibit podocyte pyroptosis by acting on the Nrf2 to regulate the NLRP3/caspase-1/GSDMD pathway, thus improving renal damage in DN mouse.