Preventive of Lacticaseibacillus casei WLCA02 against Salmonella Typhimurium infection via strengthening the intestinal barrier and activating the macrophages

Abstract

Salmonella Typhimurium is a foodborne pathogen that causes gastrointestinal disease. This study aimed to screen probiotic strains to prevent S. Typhimurium infection and explore the corresponding mechanisms. Based on the excellent inhibitory effect, Lacticaseibacillus casei WLCA02 was selected and investigated for its potential protective mechanism against S. Typhimurium by different models, namely, the S. Typhimurium infection mice model, HT-29 epithelial cell model, and RAW264.7 macrophage model. Our results showed that supplementation of live and heat-killed WLCA02 could significantly reduce the Salmonella loads in mice, enhance the intestinal barrier via upregulating the expression of tight junction proteins (ZO-1 and Claudin-1) and the number of goblet cells, and alleviate the inflammation. Meanwhile, WLCA02 could reduce the internalization and mobility of S. Typhimurium, and activate the RAW264.7 macrophages and improve the inflammation caused by Salmonella. These results indicate that L. casei WLCA02 can potentially be developed as an antibacterial functional food.