Heat-killed <i>Lacticaseibacillus paracasei</i> 6235 is more effective than live on DSS-induced colitis <i>via</i> modulation of intestinal microbiota and MAPK/NF-κB signaling pathways

This study compared the protective effects of both live <i>Lacticaseibacillus paracasei</i> 6235 (LLP 6235) and heat-killed <i>Lacticaseibacillus paracasei</i> 6235 (HK-LP 6235) on ulcerative colitis. Using a dextran sulfate sodium (DSS)-induced colitis mouse model, we evaluated physiological state, colon tissue integrity, inflammatory factors, tight junction (TJ) proteins, and intestinal microbiota variations. The findings demonstrated that both LLP 6235 and HK-LP 6235 have the capacity to mitigate colitis damage, enhance TJ protein levels, and restore colon morphology. In addition, these interventions modulated the intestinal inflammatory response by inhibiting pro-inflammatory factors and upregulating anti-inflammatory factors through the mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways. Moreover, treatment with LLP 6235 and HK-LP 6235 significantly altered intestinal microbiota diversity, increased the relative abundance of beneficial bacteria, and regulated the short-chain fatty acid (SCFA) levels. Spearman correlation analysis revealed a strong association between TJ proteins, SCFAs, intestinal microbiota, and inflammatory response, suggesting that LLP 6235 and HK-LP 6235 may provide an effective approach to colitis prevention. In conclusion, LLP 6235 and HK-LP 6235 have similar abilities; furthermore, HK-LP 6235 modulated the intestinal microbiota through lipid metabolic pathways, resulting in a greater improvement. Moreover, considering the high stability and safety of prebiotics and their wide applicability, HK-LP 6235 is recommended for use as a modulator of intestinal inflammatory diseases.