IL22 and graft versus host disease: Furthermore, IL-22 is involved in the pathogenesis of several autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis, sjögren syndrome, psoriasis [ 21], and skin diseases [ 41] but has protective, anti-apoptotic and anti-inflammatory effects in graft versus host disease [ 23], rheumatoid arthritis [ 24], and asthma [ 25].