Effects of Immune Cells on Intestinal Stem Cells: Prospects for Therapeutic Targets.

The intestinal epithelium undergoes rapid cell turnover to maintain the integrity of the mucosal barrier, which is driven by the proliferation and differentiation of intestinal stem cells (ISCs). Due to their properties, ISCs are not only vulnerable targets during intestinal damage, but also act as the resources responsible for repair and regeneration. Moreover, the intestinal tract is the largest immune organ in the body, with the greatest number of immune cells including, but not limited to, macrophages, innate lymphoid cells and T cells. With the advance of intestinal organoid culture systems and single-cell RNA sequencing, the effects of immune cells on ISCs have been initially explored. As a component of the stem cell niche, these activated immune cells and their corresponding cytokines directly modulate apoptosis or survival of ISCs, leading to either destruction or protection of the intestinal epithelium in immune-mediated diseases, such as inflammatory bowel disease and graft-versus-host disease. In this review, we describe the effects of various immune cells on ISCs, as well as the mechanisms underlying these effects. We also highlight the remarkable role of ISCs in intestinal pathogenesis and raise the possibility of developing novel and effective therapeutic strategies for immune-mediated diseases based on ISCs.