Epithelial cell-intrinsic IKKβ expression regulates innate and adaptive immunity in the gut (42.4)

Abstract Intestinal epithelial cells (IECs) provide a primary physical barrier against commensal and pathogenic microorganisms in the gastrointestinal (GI) tract, but the influence of IECs on the regulation of immunity is unknown. Here we show that IEC-intrinsic IKKβ-dependent gene expression is a critical regulator of dendritic cell (DC) and CD4+ T cell responses in the gut. Following infection with the parasite Trichuris, littermate control mice develop pathogen-specific TH2 cytokine responses and eradicate infection while mice with an IEC-specific deletion of IKKβ (IkkbΔIEC mice) fail to do so. Further, IkkbΔIEC mice exhibit exacerbated production of DC-derived IL-12/23p40 and TNF-α, heightened levels of CD4+ T cell-derived IFN-γ and IL-17, and develop severe intestinal inflammation. Blockade of proinflammatory cytokines during Trichuris infection ablates the requirement for IKKβ in IECs to promote CD4+ TH2 cell-dependent immunity, identifying a critical role for IECs in limiting type 1 cytokine production in the GI tract. These results suggest that the balance of IKKβ-dependent gene expression is critical for intestinal immune homeostasis by promoting mucosal immunity and limiting chronic inflammation. This work is funded by the NIH, CCFA and the Irvington Institute.