Abstract
BackgroundThe gut microbiota is playing more important roles in host immune regulation than was initially expected. Since many benefits of microbes are highly strain-specific and their mechanistic details remain largely elusive, further identification of new probiotic bacteria with immunoregulatory potentials is of great interest.ResultsWe have screened our collection of probiotic lactic acid bacteria (LAB) for their efficacy in modulating host immune response. Some LAB are characterized by suppression of TNF-α induction when LAB culture supernatants are added to THP-1 cells, demonstrating the LAB’s anti-inflammatory potential. These suppressive materials were not inactivated by heat or trypsin. On the other hand, treatment of THP-1 directly with live bacterial cells identified a group of pro-inflammatory LAB, which stimulated significant production of TNF-α. Among those, we chose the Lactobacillus reuteri BM36301 as an anti-inflammatory strain and the L. reuteri BM36304 as a pro-inflammatory strain, and further studied their in vivo effects. We supplied C57BL/6 mice with these bacteria in drinking water while feeding them a standard diet for 20 weeks. Interestingly, these L. reuteri strains evoked different consequences depending on the gender of the mice. That is, males treated with anti-inflammatory BM36301 experienced less weight gain and higher testosterone level; females treated with BM36301 maintained lower serum TNF-α as well as healthy skin with active folliculogenesis and hair growth. Furthermore, while males treated with pro-inflammatory BM36304 developed higher serum levels of TNF-α and insulin, in contrast females did not experience such effects from this bacteria strain.ConclusionThe L. reuteri BM36301 was selected as an anti-inflammatory strain in vitro. It helped mice maintain healthy conditions as they aged. These findings propose the L. reuteri BM36301 as a potential probiotic strain to improve various aspects of aging issues.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-016-0686-7) contains supplementary material, which is available to authorized users.
Highlights
The gut microbiota is playing more important roles in host immune regulation than was initially expected
Characterization of probiotic lactic acid bacteria We have been isolating lactic acid bacteria (LAB) for years from various sources including humans, animals, plants, and food products. These Benebios Microorganisms (BM) collections are comprised of over 500 strains, with probiotic potentials revealed from their initial screenings
We examined the bacteria with respect to their general qualifications as probiotics (Table 1)
Summary
The gut microbiota is playing more important roles in host immune regulation than was initially expected. In order for dietary probiotics to effectively function in the gut, they should meet certain basic qualifications [14,15,16,17]. They must be able to withstand the challenging environment of gastric acids, digestive enzymes, or bile salts in the stomach and intestines. Their intrinsic antimicrobial activities against pathogens would be beneficial to hosts. It is desirable that they can adhere well enough to the mucosal layer in the gastrointestinal (GI) tract, especially since they need to compete with other pathogens for nutrient uptake
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