1,25(OH)₂D₃ mitigates bronchopulmonary dysplasia via modulation of the TXNIP-NLRP3-GSDMD signaling pathway

Background: Bronchopulmonary dysplasia (BPD) is a chronic lung disease associated with preterm birth. Vitamin D (VitD) is essential for lung development and maturation.

Objective: To investigate the protective effects of 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃] on BPD and explore its potential mechanisms, focusing on the TXNIP-NLRP3-GSDMD inflammatory signaling pathway.

Methods: A hyperoxia-induced BPD model was established in Sprague-Dawley rats. Primary alveolar type II epithelial cells (AEC IIs) were exposed to normoxia or hyperoxia with or without 1,25(OH)₂D₃ and lipopolysaccharide (LPS), which was used as a general inflammatory stimulus. Lung histology and ultrastructure were evaluated by H&E staining and transmission electron microscopy. Oxidative stress, inflammatory responses, and protein expression were assessed by immunofluorescence, RT-qPCR, ELISA, and western blotting. Cell viability and oxidative status were analyzed using CCK-8, EdU, MDA, and SOD assays.

Results: 1,25(OH)₂D₃ improved AEC II viability and proliferation, reduced MDA levels (P < 0.05), and increased SOD activity (P < 0.05) under hyperoxic conditions. In addition, 1,25(OH)₂D₃ decreased inflammatory cytokine levels (IL-1β, IL-18, IL-6, IL-33, TNF-α) (P < 0.05) and reduced expression of proteins associated with the TXNIP-NLRP3-GSDMD pathway, which has been implicated in Pyroptosis. Lung injury and alveolar simplification were alleviated following 1,25(OH)₂D₃ treatment. Co-treatment with LPS partially reversed these effects.

Conclusion: 1,25(OH)₂D₃ is associated with the attenuation of hyperoxia-induced lung injury and modulation of the TXNIP-NLRP3-GSDMD inflammatory signaling pathway in BPD.