IL-33 Increases the Magnitude of the Tissue-Resident Memory T Cell Response in Intestinal Tissues during Local Infection.

IL-33 plays an important role in the early programming of CD8 T cells; however, its contribution to the differentiation of tissue-resident memory T cells in vivo remains poorly defined. After infection of mice with Yersinia pseudotuberculosis, IL-33 expression was increased in the intestinal tissue, and this coincided with the expression of ST2 on T cells infiltrating the intestinal epithelium and lamina propria. Blocking IL-33 signaling after T cell infiltration of the intestinal tissue did not significantly impact the number or phenotype of tissue-resident memory T cells generated. However, overexpression of ST2 on T cells was able to increase expression of TCF1 and T cell number in the intestine compared with the lymphoid organs during infection. We also observed that enhanced accumulation and maintenance of ST2-overexpressing cells in the intestine postinfection were resolved. This points to a role for IL-33 in increasing the number of T cells that commit to intestinal tissue residency in vivo.