A probiotic provides protection against acute salmonellosis in mice: Possible role of innate lymphid NKP46+ cells

• L. rhamnosus JB1 Feeding to mice led to an increase in IL-22-producing RORγt-expressing NKp46+ cells in the Peyer's patches.
• L. rhamnosus JB1-fed mice infected with S. Typhimurium resulted in low bacterial loads in the Peyer's patches and colon.
• L. rhamnosus JB1 feeding to mice prolonged the survival time compared to control animals following S. Typhimurium challenge.

A subset of innate lymphoid cells (ILCs), which produce IL-22 and function in protection against microbial infection, is generated via a local process in gut that is conditioned by commensal bacteria. We investigated the possibility that modulation of ILCs may contribute to the protective effect of certain bacteria in relation to pathogen infection. We fed BALB/c mice with L. rhamnosus JB-1 and characterized Peyer's patches NKp46+ cells. Additionally, the effect of feeding L. rhamnosus JB-1 on S. enterica serovar Typhimurium infection was determined. L. rhamnosus JB-1-feeding resulted in lower bacterial loads of Salmonella Typhimurium in the Peyer's patches, mesenteric lymph nodes and colon; and was associated with high levels of IL-22, RORγt, and CD127 expression by NKp46+ cells indicating an increase in ILC3s. Our findings indicate that Lactobacillus feeding regulates the innate lymphoid cell population that may contribute to host defensive function during Salmonella infection.