Table 1.

Characteristic and clinical outcomes in inflammatory bowel disease patients with concurrent immune-mediated inflammatory diseases

IMIDs with high prevalence among patients with IBD	Possible shared immune cells contributing to pathogenesis	IBD phenotypes	IBD outcomes	Possible shared therapies
Asthma	Th2 cells	Indefinite	Indefinite	Indefinite
Psoriasis	Th1 cells, Th17 cells, and ILC3	Indefinite	Indefinite	Ustekinumab; TNF inhibitors
Rheumatoid arthritis	Th1 cells, Th17 cells, ILC1, and ILC3	Indefinite	Indefinite	Tofacitinib; TNF inhibitors
IMIDs affecting phenotypes or outcomes of IBD
PSC	Indefinite (leaky gut theory)	Severe right-sided colitis, rectal sparing, and backwash ileitis	PSC-IBD patients have fewer or no symptoms, and are less likely to require immunosuppressants, hospitalization, and surgery than IBD patients alone	Indefinite
Celiac disease	Th17 cells	CD patients with celiac disease are less likely to have ileocolonic involvement than CD patients alone	CD patients with celiac disease are less likely to require TNF inhibitors or azathioprine than CD patients alone. UC patients with celiac disease have an increased risk of colectomy	Indefinite
Takayasu arteritis	Th1 cells and Th17 cells	Discontinuous aphthous erosions/ulcers or focal mucosal inflammation	Indefinite	Tofacitinib; Ustekinumab; TNF inhibitors

IBD: Inflammatory bowel disease; PSC: Primary sclerosing cholangitis; IMIDs: Immune-mediated inflammatory diseases; TNF: Tumor necrosis factor; Th17 cells: Interleukin-17 producing T helper cells; Th1 cells: T helper 1 cells; Th2 cells: T helper 2 cells; CD: Crohn’s disease; UC: Ulcerative colitis; ILC: Innate lymphoid cell.