PT - JOURNAL ARTICLE AU - Sha Li AU - William Walters AU - Benoit Chassaing AU - Benyue Zhang AU - Qiaojuan Shi AU - Jillian Waters AU - Andrew T. Gewirtz AU - Cynthia A. Leifer AU - Ruth Ley TI - Gut microbiota influence B cell function in a TLR5-dependent manner AID - 10.1101/537894 DP - 2019 Jan 01 TA - bioRxiv PG - 537894 4099 - http://biorxiv.org/content/early/2019/02/07/537894.short 4100 - http://biorxiv.org/content/early/2019/02/07/537894.full AB - Toll-like receptor (TLR) 5-deficient mice display aberrantly low levels of flagellin-specific antibodies (Flic-IgA) secreted into the gut, combined with excess bacterial flagellin in the gut, and together these attributes define microbiome dysbiosis (T5-dysbiosis). How TLR5 signaling deficiency results in T5-dysbiosis is unclear. Here, we address the role of B cells in T-dysbiosis. We observed that B cells do not express TLR5, and that B cell transplantation from TLR5-/- mouse donors into B-cell deficient mice resulted in a slight reduction in Flic-IgA levels compared to B-cells from WT donors. Bone marrow transplants from WT and TLR5-/- donors into recipients of both genotypes confirmed that TLR5 signaling by non-hematopoietic cells is required for T5-dysbiosis. We observed TLR5 deficiency was associated with an expanded population of IgA+ B cells. TLR5-/- mice tended to have higher richness for the IgA gene hypervariable region (CDR3 gene) variants. Transplantation of microbiomes from TLR5-/- and WT microbiomes donors into germfree mice resulted in a higher proportion of IgA-secreting B cells, and higher overall fecal IgA and anti-Flic IgA for TLR5-/- microbiome recipients. This observation indicated that the TLR5-/- mouse microbiome elicits an anti-flagellin antibody response that requires TLR5 signaling. Together these results indicate that TLR5 signaling on epithelial cells influences B cell populations and antibody repertoire.