Lactobacillus fermentum 2-14 mitigates the cytotoxicity induced by methylglyoxal by activating the AMPK-autophagy signaling axis.

Methylglyoxal (MGO), a reactive dicarbonyl formed during the food processing, induces oxidative stress, inflammation and apoptosis. However, there are little effective methods to reduce MGO-induced cytotoxicity. Here, we screened 35 lactic acid bacteria and identified Lactobacillus fermentum 2-14 as the most effective strain in restoring Caco-2 cell viability and reducing LDH cytotoxicity under MGO challenge. Mechanistically, L. fermentum 2-14 attenuated MGO-induced ROS accumulation, apoptosis and inflammatory responses, and promoted autophagy, as indicated by increased LC3 puncta and autolysosome formation using an RFP-GFP-LC3 reporter. Using integrative transcriptomics and metabolomics, we further suggested that L. fermentum 2-14 activates the AMPK pathway by increasing the level of pyruvate in Caco-2 cells. Supplementing with pyruvate partially mimicked the protective effect in an AMPK- and autophagy-dependent manner. Collectively, our findings indicate that L. fermentum 2-14 mitigates MGO cytotoxicity via a pyruvate-AMPK-autophagy axis, supporting the development of probiotic-based strategies to counter food-derived dicarbonyl stress.