IL-23 was reported to have higher expression level in the terminal ileum of AS patients and CD patients83 and mouse model studies have revealed that overexpression of IL-23 alone can cause spondyloarthritis.53, 84 Sherlock et al identified a population of IL-23-responsive cells from entheseal expressed IL-17 and IL-22 that developed in response to the IL-23 treatment.84 Clinical paw swelling scores were reduced by inhibiting IL-17 or IL-22, especially by inhibiting both. Here, IL17A is linked to Cowden disease.