1,25-Dihydroxyvitamin D3 mitigates high glucose-induced oxidative stress, inflammation, and extracellular matrix accumulation in glomerular mesangial cells via the ROS/TXNIP/NLRP3 pathway.

BACKGROUND

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) is a physiologically active form of vitamin D. Our study investigated the renoprotective functions of 1,25(OH)2D3 in diabetic nephropathy (DN) progression and its underlying mechanism targeting the ROS/TXNIP/NLRP3 inflammasome pathway.

METHODS

DN was induced in Wistar rats via high-fat diet (4 weeks) and streptozotocin injection (30 mg/kg, i.p.); hyperglycemic rats were randomized into DN and DN + 1,25(OH)2D3 (16 μg/kg, 12 weeks) groups. Rat mesangial HBZY-1 cells were maintained under normal glucose (5.5 mM), high glucose (25 mM), high glucose plus 1,25(OH)2D3 (1-50 nM), or high glucose plus N-acetylcysteine (NAC, 10 mM). Cell viability was assessed by the CCK-8 assay. Oxidative stress parameters (ROS via DCFH-DA fluorescence, MDA content, SOD activity) and pyroptosis markers (LDH release, PI/Hoechst 33342 nuclear staining) were quantified. Renal histopathology was performed using PAS and Masson trichrome staining. Biochemical analyses included serum creatinine, urea nitrogen, and 24-h urinary protein quantification. Molecular profiling encompassed ELISA (IL-1β, IL-6, TNF-α, IL-18, fibronectin, collagen IV), RT-qPCR (NOX2, NOX4, NLRP3, ASC), western blotting (TXNIP, NLRP3, ASC, caspase-1, IL-1β, IL-18, collagen IV, fibronectin, laminin), and TXNIP immunofluorescence.

RESULTS

1,25(OH)2D3 significantly attenuated high glucose-induced pathological alterations in HBZY-1 cells, including ROS overproduction, TXNIP upregulation, NLRP3 inflammasome activation, oxidative stress, inflammation, extracellular matrix (ECM) deposition, and pyroptotic cell death. Consistently, 1,25(OH)2D3 suppressed ROS/TXNIP/NLRP3/caspase-1 signaling, ameliorated renal dysfunction, and mitigated histopathological damage in DN rats.

CONCLUSION

1,25(OH)2D3 confers renoprotection in DN by inhibiting the ROS/TXNIP/NLRP3 inflammasome axis, thereby suppressing oxidative stress, inflammatory cytokine production, ECM accumulation, and pyroptotic cell death in glomerular mesangial cells and renal tissues.