Although the involvement of helper T (Th) and regulatory T (Treg) cell-related immune molecules in pathogenesis of inflammatory bowel disease (IBD) is widely accepted, no discriminatory mucosal expression profiles of these molecules between ulcerative colitis (UC) and Crohn's disease (CD) have been clarified.
Mucosal expression of 17 cytokines and transcription factors related to Th1, Th2, Th17, and Treg were measured by quantitative PCR in endoscopic biopsies from inflamed (40 from UC [UCI] and 20 from CD [CDI]) and noninflamed (47, 22, and 25 from UC, CD, and controls, respectively) colon or ileum. The discriminatory power of these markers to differentiate between the 2 diseases was evaluated by linear discriminant analysis and, unsupervised, principal component analysis.
By univariate analysis, many targets were markedly increased in inflamed versus noninflamed areas. However, marker expression was almost comparable between UCI and CDI, with the largest difference in UCI-predominant interleukin (IL) 21 and IL-13 with area under the receiver operating characteristic curve (AUC) values of 0.704 and 0.664, respectively. In contrast, combinations of 2 to 7 markers improved UCI versus CDI discrimination with AUC = 0.875 to 0.975. Among these, a 5-maker set (interferon-γ, IL-12 p35, T-bet, GATA3, and IL-21) demonstrated an AUC of 0.949 and a misclassification rate of 8.3%. Principal component analysis also markedly separated UCI and CDI.
Inflamed mucosae from UC and CD could be discriminated with high accuracy using combinations of Th cell–related markers. Multigene analysis, possibly reflecting the underlying pathogenesis, is expected to be useful for diagnosis, monitoring and further defining distinctive characteristics in inflammatory bowel disease.