IL-10-producing CD4⁺ T cells negatively regulate fucosylation of epithelial cells in the gut

Fucosylated glycans on the surface of epithelial cells (ECs) regulate intestinal homeostasis by serving as attachment receptors and a nutrient source for some species of bacteria. We show here that epithelial fucosylation in the ileum is negatively regulated by IL-10-producing CD4⁺ T cells. The number of fucosylated ECs was increased in the ileum of mice lacking T cells, especially those expressing αβ T cell receptor (TCR), CD4, and IL-10. No such effect was observed in mice lacking B cells. Adoptive transfer of αβTCR + CD4⁺ T cells from normal mice, but not IL-10-deficient mice, normalized fucosylation of ECs. These findings suggest that IL-10-producing CD4⁺ T cells contribute to the maintenance of the function of ECs by regulating their fucosylation.