Numerous pieces of evidence show that the PD-1 axis plays an significant role in autoimmune disorders, including inflammatory bowel disease (IBD), systemic lupus erythematosus (SLE), Type 1 diabetes (T1D), systemic vasculitis, myositis, autoimmune encephalomyelitis, autoimmune hepatitis, Behcet’s disease, myasthenia gravis, autoimmune uveitis, Sjogren’s syndrome, and ankylosing spondylitis (14, 57–61). This evidence concerns the gene PDCD1 and inflammatory bowel disease.