The role of cryptopatch-derived intraepithelial lymphocytes in the development of chronic ileocecitis

Lympho-haemopoietic progenitors residing in murine gut cryptopatches (CPs) have been shown to generate intestinal extrathymic intraepithelial lymphocytes (IELs). However, the role of CPs in the development of intestinal inflammation remains unclear. To investigate the role of CPs in the development of intestinal inflammation, we examined SAMP1/Yit mice, which spontaneously develop a chronic intestinal inflammation localized to the terminal ileum and cecum. Here, we showed the sharp correlation between the disease onset and the decreased number of CPs, resulting in decreased number of both thymus-independent IELs including T-cell receptor γδ⁺ (TCRγδ⁺) and CD8αα⁺TCRα β⁺ cells but not thymus-dependent CD8αβ ⁺TCRαβ⁺ and CD4⁺TCRαβ ⁺ cells in SAMP1/Yit mice. These data provide the first suggestion that thymus-independent IELs derived from CP might play protective role against the onset and the development of intestinal inflammation.