Bifidobacterium lactis BL-99 modulates intestinal inflammation and functions in zebrafish models

This study was designed to explore the therapeutics and the mechanisms of a patented and marked gastric acid and intestine juice-resistant probiotics Bifidobacterium lactis BL-99 ( B . lactis BL-99) on the intestinal inflammation and functions in the zebrafish models. After feeding for 6 hours, B . lactis BL-99 was fully retained in the larval zebrafish intestinal tract and stayed for over 24 hours. B . lactis BL-99 promoted the intestinal motility and effectively alleviated aluminum sulfate-induced larval zebrafish constipation ( p < 0.01). Irregular high glucose diet induced adult zebrafish intestinal functional and metabolic disorders. After fed with B . lactis BL-99, IL-1β gene expression was significantly down-regulated, and IL-10 and IL-12 gene levels were markedly up-regulated in this model ( p < 0.05). The intestinal lipase activity was elevated in the adult zebrafish intestinal functional disorder model after B . lactis BL-99 treatment ( p < 0.05), but tryptase content had no statistical changes ( p > 0.05). B . lactis BL-99 improved the histopathology of the adult zebrafish intestinal inflammation, increased the goblet cell numbers, and up-and-down metabolites were markedly recovered after treatment of B . lactis BL-99 ( p < 0.05). These results suggest that B . lactis BL-99 could relieve intestinal inflammation and promote intestinal functions, at least in part, through modulating intestinal and microbial metabolism to maintain intestinal health.