In vitro antiviral activity of Lactobacillus casei and Bifidobacterium adolescentis against rotavirus infection monitored by NSP4 protein production.

AIMS: The aim of this study was to determine the antiviral activity of four probiotic metabolites (Lactobacillus and Bifidobacetrium species) against rotavirus in vitro infection monitored by the NSP4 protein production and Ca(2+) release. METHODS AND RESULTS: The antiviral effect of the metabolites was performed due a comparison between a blocking model and an intracelullar model on MA104 cells, with the response of NSP4 production and Ca(2+) liberation measured by flow cytometry. Significant results were obtained with the metabolites of Lactobacillus casei, and Bifidobacterium adolescentis in the reduction of the protein production (P = 0·04 and P = 0·014) and Ca(2+) liberation (P = 0·094 and P = 0·020) in the intracellular model, which suggests a successful antiviral activity against RV infection. CONCLUSIONS: This study demonstrates that probiotic metabolites were able to interfere with the final amount of intracellular NSP4 protein and a successful Ca(2+) regulation, which suggests a new approach to the mechanism exerted by probiotics against the rotavirus infection. SIGNIFICANCE AND IMPACT OF THE STUDY: A novel anti-rotaviral effect exerted by probiotic metabolites monitored by the NSP4 protein during the RV in vitro infection and the effect on the Ca(2+) release is reported; suggesting a reduction on the impact of the infection by decreasing the damage of the cells preventing the electrolyte loss.

Unraveling the benefits of Bacillus subtilis DSM 29784 poultry probiotic through its secreted metabolites: an in vitro approach.

The probiotic Bacillus subtilis 29784 (Bs29784) sustains chicken's intestinal health, enhancing animal resilience and performance through the production of the bioactive metabolites hypoxanthine (HPX), niacin (NIA), and pantothenate (PTH). Here, using enterocyte in vitro models, we determine the functional link between these metabolites and the three pillars of intestinal resilience: immune response, intestinal barrier, and microbiota. We evaluated in vitro the capacity of Bs29784 vegetative cells, spores, and metabolites to modulate global immune regulators (using HT-29-NF-κB and HT-29-AP-1 reporter cells), intestinal integrity (HT-29-MUC2 reporter cells and Caco-2 cells), and cytokine production (Caco-2 cells). Finally, we simulated intestinal fermentations using chicken's intestinal contents as inocula to determine the effect of Bs29784 metabolites on the microbiota and their fermentation profile. Bs29784 vegetative cells reduced the inflammatory response more effectively than spores, indicating that their benefit is linked to metabolic activity. To assess this hypothesis, we studied Bs29784 metabolites individually. The results showed that each metabolite had different beneficial effects. PTH and NIA reduced the activation of the pro-inflammatory pathways AP-1 and NF-κB. HPX upregulated mucin production by enhancing MUC2 expression. HPX, NIA, and PTH increased cell proliferation. PTH and HPX increased epithelial resilience to an inflammatory challenge by limiting permeability increase. In cecal fermentations, NIA increased acetate, HPX increased butyrate, whereas PTH increased acetate, butyrate, and propionate. In ileal fermentations, PTH increased butyrate. All molecules modulated microbiota, explaining the different fermentation patterns. Altogether, we show that Bs29784 influences intestinal health by acting on the three lines of resilience via its secreted metabolites. IMPORTANCE: Probiotics provide beneficial metabolites to its host. Here, we describe the mode of action of a commonly used probiotic in poultry, Bs29784. By using in vitro cellular techniques and simulated chickens' intestinal model, we show the functional link between Bs29784 metabolites and the three lines of animal resilience. Indeed, both Bs29784 vegetative cells and its metabolites stimulate cellular anti-inflammatory responses, strengthen intestinal barrier, and positively modulate microbiota composition and fermentative profile. Taken together, these results strengthen our understanding of the effect of Bs29784 on its host and explain, at least partly, its positive effects on animal health, resilience, and performance.