Baoshentongluo Formula relieves podocyte injury in diabetic kidney disease through regulating mitophagy via PINK1/Parkin signaling pathway.

INTRODUCTION: Diabetic kidney disease (DKD) progression is strongly associated with podocyte mitochondrial dysfunction. The clinically effective Chinese herbal Baoshentongluo formula (BSTL) has demonstrated significant proteinuria reduction in DKD patients. HPLC-ESI-MS analysis identified characteristic bioactive components in BSTL including astragalosides, rehmanniosides, and tanshinones. However, the molecular mechanisms through which BSTL maintains podocyte homeostasis remain incompletely understood. METHODS: Mouse podocyte clone-5 (MPC-5) cells and db/db mice were used. Db/db mice were randomized into db/db and db/db + BSTL (16.5 g/kg/d, intragastric administration for 12 weeks). A group of m/m mice served as the control. Renal function, urinary albumin-to-creatinine ratio (UACR), histopathological analysis, apoptotic, and mitophagy-related protein levels were evaluated. MPC-5 cells were exposed to high glucose (HG, 30 mM) and BSTL drug-containing serum (8%) for 24 h grouping as control, HG, HG + BSTL, and HG + siPINK1. Podocyte apoptosis, mitophagy levels, and expression of PTEN-induced putative kinase 1 (PINK1) and E3 ubiquitin ligase (Parkin) were assessed. RESULTS: In db/db diabetic mice, oral administration of BSTL significantly lowered urinary albumin-to-creatinine ratio (P<0.05), improved glomerular filtration rate, and ameliorated renal histopathological changes, decreased LC3-II/LC3-I ratio, and downregulated expression of mitophagy-related proteins PINK1, Parkin, ATG5 and Beclin-1. Treatment with 8% BSTL-containing serum significantly attenuated HG-induced podocyte apoptosis (P<0.01) and suppressed excessive mitophagy, as evidenced by reduced TOM20/LC3 co-localization (P<0.01). Notably, BSTL treatment markedly reduced protein levels of both PINK1 and Parkin (P<0.01), key regulators of mitophagy initiation. Genetic silencing of PINK1 in podocytes phenocopied BSTL's protective effects, confirming the pathway specificity. DISCUSSION: Our integrated in vitro and in vivo findings establish that BSTL protects against DKD progression by selectively inhibiting PINK1/Parkin-dependent mitophagy in podocytes to inhibit podocyte injury, which provides both mechanistic insights and therapeutic potential for clinical DKD management.