Comparative Effects of Live and Heat-Killed Lacticaseibacillus paracasei HP7 on Intestinal Motility, Barrier-Related Markers, and Gut Microbiota in Delayed Transit Mice.

This study evaluated the effects of live and heat-killed Lacticaseibacillus paracasei HP7 on intestinal motility, host physiological responses, and gut microbiota in a mouse model of delayed intestinal transit. BALB/c mice were treated with live HP7 (HP7L), heat-killed HP7 (HP7K), or bisacodyl following loperamide administration. HP7L and HP7K improved intestinal motility-related parameters, including fecal output, stool consistency, fecal moisture content, and charcoal meal transit. HP7 treatment also modulated circulating gastrointestinal hormones and inflammatory cytokines, with changes in serotonin, ghrelin, peptide YY, IL-6, and IL-17A. In intestinal tissues, HP7 regulated the expression of genes related to neuroendocrine signaling, water transport, mucus production, and tight junction integrity, including Ghrl, Tac1, Slc6a4, Aqp3, Muc2, Tjp1, Tjp2, and Ocln. Histological analysis further showed reduced colonic tissue alterations and improved structural parameters. Microbiota analysis revealed that HP7L exerted broader effects on microbial community structure, whereas HP7K induced more selective taxonomic changes. Predicted functional profiling suggested that both HP7L and HP7K were associated with shifts in carbohydrate metabolism-related pathways, with HP7K showing additional predicted enrichment of pathways related to redox-associated metabolism, lipid metabolism, and microbial substrate utilization. These findings suggest that heat-killed HP7 retains biological activity and has potential as a postbiotic candidate for regulating intestinal motility.