Quantitative PCR Analysis of TNF-α and IL-1β mRNA Levels in Pediatric IBD Mucosal Biopsies
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Inflammatory bowel disease (IBD) is associatedwith increased activation of intestinal immune cells,whose overproduction of proinflammatory cytokines suchas tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) is implicatedin mediating the sustained inflammatory response.Studies to date have largely reported qualitativedifferences in cytokine gene expression between IBD andcontrols. Our aim was to perform quantitative analysis ofintestinal mucosal mRNA expression in colonic biopsiesfrom pediatric IBD patients using a competitivepolymerase chain reaction. IL-1β and TNF-αwere expressed in all IBD and control biopsies.Compared to controls, IL-1β mRNA levels wereincreased in involved tissue from Crohn's disease (CD)patients, but not in histologically uninvolved CD or in ulcerative colitis (UC) mucosa. IL-1βexpression in the latter groups were equivalent to thosefound in tissue from patients with eosinophilic colitis(EOC). Significantly higher levels of IL-1β mRNA were found in uninvolved mucosa from CDpatients who presented with a relapse of diseaseactivity, as compared to newly diagnosed cases withhistological features of CD at an early stage.TNF-α mRNA transcripts were also significantly elevated ininvolved CD mucosa, but not in the other groups.TNF-α gene expression in CD-involved tissuedecreased with disease duration. Follow-up of thepatients revealed that high cytokine expression inuninvolved CD tissue correlated with an early clinicalrelapse. In conclusion, quantitative determination ofproinflammatory cytokine gene expression revealsdifferences between the type, severity, and clinical coursein patients with IBD.
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