Development of intestinal tissue-resident T cells in early-life mice before and after weaning

Intestinal tissue-resident T cells have been poorly characterized during early-life. Here, we phenotypically characterized tissue-resident (intravascular staining negative) CD4⁺ and CD8α⁺ T cells in spleen and intestine (lamina propria and intraepithelial lymphocytes), in suckling and juvenile mice before and after weaning, respectively. While minor changes were observed in spleen T cells, significant changes in tissue-resident T cells frequency and phenotype were identified after weaning. Although differences were seen between CD4⁺ and CD8α⁺ T cells in lamina propria and intraepithelial lymphocytes, in general, an increase of CCR7^- CD44^hi, CD69⁺, CD103⁺, and P2X7R⁺ tissue-resident T cells were detected in the post-weaning period. Our study highlights the association of weaning with the development of intestinal tissue-resident T cells in early-life and suggests that dietary and microbial shifts during weaning play a crucial role in shaping tissue-resident T cell compartments.