Recombinant IL-25-treated mice showed less severe disease phenotype that was associated with decreased epithelial barrier damage and elevated levels of IL-4.109 Eosinophil-deficient mice showed severe epithelial damage and increased colitis, which shows the protective role of eosinophils.109 Another study,110 using the toxin transferase in C. difficile R20291-induced severe colitis, showed apoptosis of eosinophils. The gene discussed is IL25; the disease is colitis.