CCR9 and infection: CCR9 is a small intestinal chemokine homing receptor normally found on most mucosal T cells in the gastrointestinal tract, and that has been linked to celiac disease [20] It has been recently shown that the CCR9-CCL25 axis in mice promotes the development of a Th1 population with features of TRM cell that regulates the local immune environment and that CCR9 can exert a protective response against infections in the gastrointestinal tract [21].