Deciphering the mechanisms by which probiotic Lactobacillus paracasei L5 mitigates methylglyoxal toxicity: Insights from the transcriptome and metabolome.

Methylglyoxal (MGO) is a highly cytotoxic α-dicarbonyl compound. Excessive accumulation of MGO in the body can induce oxidative stress and inflammatory responses, thereby increasing the risk of metabolic syndrome, diabetes, and neurodegenerative diseases. Conventional MGO scavengers are often associated with certain side effects, creating an urgent need for the development of safe, natural alternatives. Lactic acid bacteria (LAB), due to their safety and probiotic properties, have garnered significant attention as potential natural MGO scavengers. This study employed a Caco-2 cell-based model to screen for LAB strains capable of alleviating MGO-induced toxicity and further investigated the underlying mechanisms at the cellular, transcriptional, and metabolic levels. Lactobacillus paracasei L5 (L. paracasei L5) significantly attenuated MGO-induced cytotoxicity, increasing cell viability by approximately 28.01%. Its protective effects were manifested through the inhibition of intracellular reactive oxygen species (ROS) accumulation, the alleviation of MGO-induced inflammatory responses by regulating the secretion of pro-inflammatory mediators, and the upregulation of factors associated with the glyoxal detoxification system and antioxidant defense system. L. paracasei L5 significantly modulated transcriptional changes in the mitogen-activated protein kinase (MAPK) signaling pathway and the advanced glycation end-product receptor (AGE-RAGE) signaling pathway, both of which are closely associated with inflammatory mediators such as cyclooxygenase-2 (COX-2) COX-2) and inducible nitric oxide synthase (iNOS). Metabolomic analysis revealed that following treatment with L. paracasei L5, levels of gallic acid, 13,16, 19-docosatrienoic acid, nicotinamide adenine dinucleotide (NAD/NAD+), lysophosphatidylethanolamine (LysoPE), and lysophosphatidylcholine (LysoPC) underwent significant changes, suggesting that L. paracasei L5 is closely associated with metabolic reprogramming in the treatment system. Correlation analysis revealed that apoptosis was negatively correlated with differentially expressed genes, differentially expressed metabolites, antioxidant enzyme activity, and key signaling pathways. Overall, L. paracasei L5 alleviates MGO-induced inflammation and oxidative stress, an effect that may be related to its regulation of the MAPK and AGE-RAGE signaling pathways and improvement of energy metabolism. These results provide a mechanistic basis for the potential application of LAB in the prevention and alleviation of MGO-induced toxicity.