Additionally, IL-22 has been most commonly considered a proinflammatory cytokine due to its expression in the lesions of patients with chronic inflammatory diseases, such as rheumatoid arthritis, Crohn’s disease, psoriasis, and atopic dermatitis by inducing other proinflammatory cytokines, such as IL-6, IL-8, and TNF-α [21]. Here, IL22 is linked to Crohn disease.