ABSTRACT
BACKGROUND: It has been suggested that Crohn's disease (CD) is associated with an exaggerated T-helper 1 cytokine response manifested by increased production of interleukin (IL)-12. IL-12 is a heterodimeric protein comprising 2 disulfide-linked subunits designated p35 and p40. Recently, IL-12-related cytokines, IL-23 and IL-27, were described. Biologically active IL-23 is a heterodimer whose p40 subunit is identical to IL-12p40 whereas its p19 subunit is distantly related to IL-12p35. IL-27 consists of EBI3, an IL-12p40-related protein, and p28, a newly discovered IL-12p35-related polypeptide. AIM: We sought to determine whether mucosal expression of IL-23p19 and IL-27p28 transcripts correlate with the inflammatory activity in inflammatory bowel disease (IBD). PATIENTS/METHODS: Messenger RNA expression in colonic mucosa from patients with Crohn's disease (CD; n = 37) and ulcerative colitis (UC; n = 19), and in non-IBD control subjects (specific colitis [SC]; n = 16) and normal, nondiseased control patients (n = 12) was measured by reverse-transcribed real-time polymerase chain reaction. RESULTS: IL-23p19 was significantly increased in inflamed mucosa in CD (P = 0.0377) and to a lesser extent also in UC patients but not in SC patients. Elevation of IL-23p19 transcript levels in CD correlated with the severity of endoscopic lesions. IL-27p28 transcripts and EBI3 transcripts were significantly elevated only in active CD. DISCUSSION: IL-23p19, IL-27p28, and EBI3 transcripts are strongly up-regulated in CD. The stimulatory effects of these cytokines on naive T cells in addition to a strongly synergistic action with IL-12 to trigger interferon-gamma production may contribute to the perpetuation of the inflammatory process in patients with CD. Notably, increased expression of IL-23 and IL-27 transcripts in CD suggests a T helper 1-dominated immunologic function in this disease.
Subject(s)
Colitis, Ulcerative/metabolism , Crohn Disease/metabolism , Interleukins/biosynthesis , Adolescent , Adult , Aged , Aged, 80 and over , Case-Control Studies , Colitis, Ulcerative/genetics , Crohn Disease/genetics , Female , Humans , Interleukin-23 , Interleukin-23 Subunit p19 , Interleukins/genetics , Intestinal Mucosa , Male , Middle Aged , RNA, Messenger/analysis , RNA, Messenger/biosynthesis , Reverse Transcriptase Polymerase Chain Reaction , Transcription, Genetic , Up-RegulationABSTRACT
BACKGROUND AND AIMS: Immunoregulatory properties of cytokines may contribute to pathological immune reactions in inflammatory bowel disease. There is an urgent need for a simple and dependable means for quantitating inflammatory activity in mucosal biopsies and assessing relapse risk particularly in patients with active Crohn's disease (CD). PATIENTS AND METHODS: Cytokine and chemokine transcripts were quantified using real-time PCR in mucosal biopsy specimens from 70 patients with active inflammatory bowel disease (CD, n=45; ulcerative colitis n=25) and 16 patients with specific colitis (ischemic colitis, infectious colitis). Controls were 12 patients with noninflammatory conditions. CD patients with steroid-induced remission (n=20) were followed for up to 12 months. RESULTS: Compared to not-inflamed mucosa the vast majority of active CD tissue samples expressed significantly elevated transcript levels of IL-1beta, IL-8, IL-23, MRP-14, MIP2alpha, and MMP-1. Moreover, increased cytokine transcript levels were detected in both active ulcerative colitis and specific colitis. Importantly, TNF-alpha, IFN-gamma, CD40L, and IL-23 transcripts increased in active CD only. Transcript levels (MRP-14, IL-8, MMP-1, MIP2alpha) were correlated with clinical disease activity (CDAI) and endoscopic scoring indices. Medical treatment induced stable remission in 14 of 20 patients which was paralleled by a reduction in increased transcript levels. All six patients without normalization of MIP2alpha, MRP-14, TNF-alpha, and IL-1beta transcripts developed an early relapse (n=5) or chronic activity (n=1) during follow-up. CONCLUSION: Elevated proinflammatory cytokine transcripts in active CD may underlie disease reactivation and chronicity. Real-time PCR quantification is a simple and objective method for grading inflammation of intestinal mucosa and may be useful in identifying patients who would benefit from anti-inflammatory remission maintenance.
