Lactobacillus helveticus suppresses experimental rheumatoid arthritis by reducing inflammatory T cell responses

•Determination of a selection criterion to identify anti-inflammatory probiotics.•Validation of anti-inflammatory property using experimental rheumatoid arthritis (RA).•L. helveticus suppressed development and progression of RA.•L. helveticus reduced pro-inflammatory cytokines but increased IL-10 levels.•CD11c+ dendritic cells mediated phenotypic changes induced by L. helveticus. Although probiotics could confer health benefits to host physiology, their efficacy is strain specific. To identify anti-inflammatory probiotics, an ex vivo screening system was developed, and validated effector functions of selected candidates using experimental rheumatoid arthritis as an in vivo model. Lactobacillus helveticus HY7801 was selected as the best candidate. Oral administration of L. helveticus HY7801 prevented the development of collagen-induced experimental arthritis, and diminished disease progression and severity by reducing antigen specific IgG levels and inflammatory immune response. Administration of L. helveticus HY7801 may induce regulatory CD11c+ dendritic cells, which in turn induce a phenotypic alteration of immune cells by reducing pro-inflammatory cytokines (TNF-α, IFN-γ, and IL-17A) while enhancing anti-inflammatory cytokine (IL-10) by CD4+ T cells. This study suggests that screening of probiotic strains based on the IL-10highIL-12low selection criterion may be applicable to identify anti-inflammatory probiotics as an efficacious food for treating inflammatory immune responses including rheumatoid arthritis.