Comprehensive proteomics analyses of IL-15 driven activation of intestinal intraepithelial lymphocytes

Intestinal intraepithelial lymphocytes (IEL) are an abundant population of tissue-resident T cells that protect the gut from pathogens and maintain intestinal homeostasis. The cytokine IL-15 is trans-presented by epithelial cells to IEL in complex with the IL-15 receptor α chain (IL-15Rα) and plays essential roles both in maintaining IEL homeostasis, and in inducing IEL activation in response to epithelial stress. When overproduced, IL-15 is a key driver of the gluten-induced enteropathy Coeliac disease, through cytotoxic activation of IEL. To better understand how IL-15 directly regulates both homeostatic and inflammatory functions of IEL, we performed quantitative proteomics of IL-15/Rα-stimulated murine IEL, sorted into their 3 main subpopulations, TCRγδ CD8αα, TCRαβ CD8αβ and TCRαβ CD8αα expressing IEL. The data reveal that high IL-15/Rα stimulation licenses cell cycle activation, upregulates the biosynthetic machinery in IEL, increases mitochondrial respiratory capacity and induces expression of cell surface immune receptors and adhesion proteins that potentially drive IEL activation.