Pediatric ulcerative colitis associated with autoimmune diseases: a distinct form of inflammatory bowel disease?

Background: The pathogenesis of inflammatory bowel disease (IBD) is multifactorial, with some patients presenting additional autoimmune symptoms. Inflammatory colitis associated with autoimmune (AI) liver disease appears to have clinical features different from those of "classical" ulcerative colitis (CUC). The aim of this study was to describe these features, in order to differentiate a subgroup of colitis associated with autoimmunity (CAI) from CUC.

Methods: Twenty-eight consecutive children with inflammatory colitis associated with primary sclerosing cholangitis (PSC), celiac disease, or AI hepatitis were compared with a matched control group of 27 children with isolated UC. Clinical course, histology, as well as inflammatory profile in the colonic mucosa based on real-time polymerase chain reaction (PCR) were analyzed.

Results: In CAI the main digestive symptoms at disease onset were abdominal pain (12/28) and bloody strings in the stool (12/28), along with a high prevalence of autoimmune diseases in relatives, as compared with bloody diarrhea in the CUC group (26/27). At diagnosis, pancolitis was seen in 18/28 CAI patients compared with 8/27 in UC. In CAI, the pathological findings were different from CUC: 1) major lesions predominantly located in the right colon; 2) pseudo-villous appearance of the mucosa, and strong infiltration with eosinophils; 3) mild glandular lesions; and 4) differing inflammatory infiltrate with reduced FOXP3, interleukin (IL)-2, and thymic stromal lymphopoietin (TSLP) levels. Evolution in CAI was less aggressive, requiring less corticosteroids/immunomodulators.

Conclusions: Precise clinical, histological, and molecular analyses reveal marked differences between patients with CUC and those with associated AI phenomena, supporting the hypothesis of a distinct AI presentation of IBD.