Involvement of interleukin-4 and -10 in inflammatory bowel disease

Abstract

The pathogenesis of ulcerative colitis (UC) and Crohn's disease (CD) may be associated with a decreased production of cytokines suppressing macrophage and T-cell functions: interleukins (IL) -4 and IL-10. Serum concentrations of IL-4 and IL-10 were measured using an ELISA technique, and intestinal IL-4 and IL-10 mRNA was detected by a reverse transcriptase polymerase chain reaction (RT-PCR) in 34 patients with inflammatory bowel disease (IBD) (20 with UC and 14 with CD) and compared to 12 control subjects. The superoxide production was measured spectrophotometrically in activated PMNs initially incubated in the presence of IL-4 or IL-10. No differences were found in numbers of cells that might be potential IL-4 or IL-10 producers (T cells, macrophages, B cells, and mast cells) in biopsy specimens using immuno- and histochemistry. IL-4 mRNA was detectable in specimens from 77.8% of the UC patients (P>0.05) and 0% of the CD patients (PP0.05). Finally, the superoxide production was inhibited and delayed by the addition of IL-10 (P<0.01), whereas IL-4 only delayed this parameter. In conclusion, apart from the well-known suppressive effect on proinflammatory cytokine production, IL-4 delays and IL-10 inhibits superoxide generation. IL-4 mRNA expression is decreased in intestinal tissue from CD patients, while IL-10 mRNA expression is decreased in majority of UC patients, suggesting different immunopathogenesis of the two diseases.