Sodium butyrate attenuates D-galactose-induced cellular senescence in WI-38 fibroblasts in vitro via modulation of HDAC activity, Nrf2/ARE pathway, and p53/p21/p16 signaling

Cellular senescence is closely associated with various age-related diseases. Sodium butyrate (NaB), a short-chain fatty acid and histone deacetylase (HDAC) inhibitor, exhibits potential anti-aging properties; however, its precise mechanisms remain unclear. This study aimed to investigate the protective effects of NaB against D-galactose (D-gal)-induced senescence in WI-38 human fibroblasts and elucidate the underlying mechanisms. WI-38 cells were co-treated with D-gal and NaB simultaneously to investigate whether NaB could mitigate D-gal-induced senescent changes. Senescence phenotypes were assessed by SA-β-Gal staining, ROS detection, and ELISA. Western blotting and chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) were performed to evaluate signaling pathways and histone acetylation, while siRNA knockdown validated Nrf2 function. NaB dose-dependently reduced SA-β-Gal-positive cells, ROS levels, and MDA content, while restoring SOD and GSH-Px activities and suppressing IL-6 and IL-1β secretion. Mechanistically, NaB promoted Nrf2 nuclear translocation by downregulating Keap1, thereby upregulating HO-1 and NQO1 expression. NaB also inhibited p53 phosphorylation and reduced p21 and p16 expression at both the mRNA and protein levels, as confirmed by RT-qPCR and Western blotting. Furthermore, NaB suppressed HDAC activity and restored H3K9ac and H3K27ac levels. Nrf2 knockdown reversed NaB’s protective effects. ChIP-qPCR revealed that NaB restored H3K9ac enrichment at p21 and p16 promoters. These results indicate that NaB may attenuate D-gal-induced cellular senescence through coordinated modulation of the Nrf2/ARE pathway, p53/p21/p16 signaling, and HDAC-mediated epigenetic regulation. These findings provide preliminary evidence supporting NaB as a candidate modulator of aging-associated cellular processes, warranting further validation in vivo .