IL-22 produced by both innate and adaptive lymphocytes is indispensable for maintaining colonic epithelial barrier by preventing cell death, stimulating proliferation of epithelial stem cells, and inducing protective factors such as mucins and antimicrobial peptides from goblet and Paneth cells, respectively.37,39,40 IL-22-deficient mice had increased morbidity and mortality after CDI despite a comparable degree of intestinal pathogen burden,41 as we have observed in PGRN-deficient mice in this study. The gene discussed is IL22; the disease is clostridium difficile infection.