22 T-cell Receptor β (TCR β) Complementarity-Determining Region 3 (CDR3) Sequencing Provides a Distinct Profile Defining IBD Patients and Identifies Unique TCR β CDR3 Regions Significantly Associated With Crohn's Disease or Ulcerative Colitis

Abstract

Background: Rotavirus (RV), the world's leading cause of severe viral gastroenteritis amongst children, primarily infects small intestinal epithelial cells (IECs) and is responsible for over 500,000 deaths and millions of physician visits/hospitalizations per year. While successful resolution of infection and protection against future infection is mediated by adaptive immunity, particularly mucosal IgA, relatively little is known how innate immunity contains acute infection and drives the adaptive immune response to this virus. In light of the broad role of MyD88 in signaling by TLRs and inflammasome cytokine receptors signaling, our goal was examine the consequence of absence of MyD88 in a mouse model of RV infection as means to mechanistically explore innate immunity to this virus. Methods: Suckling and adult mice (WT, MyD88KO, Caspase-1KO, and various bone-marrow irradiation chimeras) mice were inoculated with mouse-passaged RVEC strain. Infection was assessed by ELISA and qRT-PCR. RV replication was assessed by quantitating + to strand ratios. Diarrhea was scored visually. RV-specific immune responses were measured by fecal/serum ELISA. Results: Loss of MyD88 markedly impaired innate immunity to RV resulting in higher levels of virus in feces, intestinal lysates, and peripheral blood cells as well as increased RV replicative ability. Such increased RV levels correlated with a marked increase in the incidence and duration of diarrhea in neonatal mice. These results were fully phenocopied by loss of Caspase-1 and partially mimicked by loss of IL-1 and IL-18 suggesting a role for inflammasome signaling in innate control of RV infection. Such inability to control RV was not observed in irradiated WTmice reconstituted with MyD88KO or Caspase-1KO bone marrow nor could WT bone marrow restore innate immunity to RV in MyD88KO or Caspase-1KO mice suggesting a prominent role for inflammasome signaling in IEC in limiting RV infection/ pathogenesis. Loss of MyD88 also profoundly impaired adaptive immunity to RV. Specifically, MyD88KOmice produced less serum RV-specific IgG and IgA and have Th2 skewed antibody responses indicative of improper Th responses and isotype class switching. In contrast to the role of MyD88 in innate immunity, MyD88-mediated adaptive immunity was independent of Caspase-1, IL-1, and IL-18 and was mediated by MyD88 in bone marrow derived cells. Conclusion: Inflammasome signaling, in IECs, plays a major role in limiting RV infection and, consequently, the diarrheal disease that the great mortality/morbidity caused by this pathogen. TLR signaling in bone-marrow derived cells is important for driving the humoral immune responses that provide lasting protection against this pathogen.