Interleukin-33 Potentiates TGF-β Signaling to Regulate Intestinal Stem Cell Regeneration After Radiation Injury

Epithelial regeneration is critical for barrier maintenance and organ function after intestinal radiation injury. Accumulating evidence indicates that the interleukin family members play critical roles in intestinal stem-cell-mediated epithelial regeneration. However, little is known about the relationship between interleukin 33 (IL-33)/ST2 axis and intestinal regeneration after radiation injury. We demonstrate here that IL-33 expression significantly increased after radiation treatment. Deficiency of IL-33/ST2 promotes intestinal epithelial regeneration, resulting in a reduction of mortality during radiation-induced intestine injury. Using ex vivo organoid cultures, we show that recombinant IL-33 promotes intestinal stem cell differentiation. Mechanistically, the effects of IL-33 were mediated by activation of transforming growth factor-β signaling. Our findings reveal a fundamental mechanism by which IL-33 is able to regulate the intestinal crypt regeneration after tissue damage.