Transcriptional profiling of mouse jejunal epithelia comparing Tcrbd-/-, DAOwt/wt mouse and Tcrbd-/-, DAOG181R/G181R Intestinal microbiota produce D-amino acids, which are bacteria-specific metabolites, for regulation of bacterial cell wall integrity. Host intestine releases D-amino acid oxidase (DAO) to degrade bacterial D-amino acids, which shapes gut microbial community. However, it is not clarified whether bacterial D-amino acids affect host s immunity. In the present study, we compared mRNA expression in ileal epithelial tissue of DAO null mice with that of control mice in the absence of both T cell receptor beta and delta (Tcrb/d). Transcriptome analysis revealed up-regulation of inflammatory cytokines such as TNFa, IL1b, and IFNg in the epithelial tissue. Up-regulation of such cytokines could promote survival of na ve B cells and increase IgA-producing plasma cells, which in turn results in enhancement of IgA production. These results indicate that DAO controls intestinal immune responses through regulation of na ve B cells and differentiation of mature B cells. Overall design: Total RNA from 5 mice of each genotype were mixed. Epithelial tissue of jejunum and ileum from Two genotype, Tcrbd-/-, DAOwt/wt vs. Tcrbd-/-, DAOG181R/G181R, Total RNA from 5 mice were mixed in one sample.