Adaptive immune responses against Lachnospiraceae-derived flagellins and their role in inflammatory bowel disease.

Adaptive immune responses, including B and T cell responses, play important roles in establishing and maintaining the mutualistic relationship between the host and intestinal microbiota. Host-microbiota mutualism is disrupted in various immune-mediated inflammatory diseases, including Crohn's disease (CD). Aberrant inflammatory memory CD4+ T cell responses contribute to disease chronicity in CD. One of the few identified microbial targets of the CD-associated immune response that has been extensively studied is Lachnospiraceae-derived flagellin protein. In this review, we provide an overview of current knowledge on innate, B, and T cell responses against Lachnospiraceae-derived flagellins in health and disease. We discuss the circumstances and immunological mechanisms that underlie these responses, as well as their clinical significance and potential as therapeutic targets.