Two novel indigenous Levilactobacillus brevis probiotic strains MKMB04 and MKMB05 enhance longevity and protect intestinal barrier function through antioxidant and anti-inflammatory mechanisms

Aging is characterized by progressive oxidative stress, mitochondrial dysfunction, chronic inflammation and intestinal barrier impairment, contributing to increased susceptibility to age-associated disorders. Targeting redox imbalance and epithelial dysfunction represents a promising therapeutic strategy to promote healthy aging. In the present study, two novels indigenous Levilactobacillus brevis probiotic strains, MKMB04 and MKMB05, were evaluated for their longevity-promoting and barrier-protective potential using Caenorhabditis elegans and intestinal cell models. Dietary supplementation with MKMB04 and MKMB05 significantly extended the mean lifespan of wild-type N2 worms by 28.6% and 17.9%, respectively, with attenuated effects observed in daf-2 mutants, suggesting involvement of insulin/IGF-1 signaling. MKMB04 markedly enhanced endogenous antioxidant defenses, as evidenced by increased catalase activity and glutathione levels, alongside upregulation of key antioxidant and stress-response genes (ctl, gst, trx, skn-1, jnk-1 and pmk-1) and suppression of lipid metabolism and apoptotic markers In intestinal epithelial and immune cell models challenged with Salmonella, both strains significantly reduced intracellular reactive oxygen species and nitric oxide production, restored tight junction proteins (Claudin-1 and ZO-1), improved transepithelial electrical resistance and enhanced mitochondrial respiration. Furthermore, pro-inflammatory cytokines (TNF-α, IL-6, IL-1β and MCP-1) were suppressed, while anti-inflammatory mediators were elevated. While earlier reports on L. brevis have primarily focused on conventional probiotic traits, with only limited studies utilizing the C. elegans model, the present study integrates C. elegans-based validation with cell culture and genomic analysis to provide a comprehensive evaluation of strain-specific functionality. Collectively, these findings highlight MKMB04 and MKMB05 as potential probiotic candidates for promoting healthy aging and intestinal function.