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BACKGROUND: Coeliac disease (CD) is caused by a T helper cell type 1 (Th1) response in the small intestinal mucosa to dietary gluten. Paradoxically, interleukin (IL)-12, the major Th1 inducing factor, is undetectable in the mucosa of active CD. IL-18 is a recently described cytokine capable of promoting T cell interferon (IFN)-gamma production and facilitating Th1 cell polarisation. AIM: To examine expression of IL-18 and IL-18-associated Th1 proteins in CD. METHODS: IL-18 and IFN-gamma RNA transcripts were determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). IL-18 and caspase-1 protein expression were assessed by western blotting. Caspase-1 activity was determined using a commercially available assay. RNA transcripts for the IL-18 receptor subunits, IL-1 receptor related protein (IL-1 Rrp) and accessory protein-like subunit (AcPL), and IL-18 induced Th1 specific T box transcription factor (T-bet) were measured by RT-PCR and Southern blotting. RESULTS: IL-18 RNA transcripts were found in all mucosal samples analysed, with no difference between CD patients and controls. By western blot analysis, a large protein of approximately 24 kDa, corresponding to the immature IL-18, was detected in all mucosal samples from CD patients and controls. In contrast, mature IL-18 was only seen in CD patients. Immunoreactivity corresponding to both immature and mature caspase-1 was present in both CD and control samples. Tissue homogenates from CD patients and controls expressed similar levels of caspase-1 activity. IL-1Rrp and AcPL were seen in all samples but were expressed at greater levels in the mucosa of CD patients. T-bet was also upregulated in CD. CONCLUSIONS: Active IL-18 is expressed in CD as well as other markers of Th1 polarisation.

Coeliac disease (CD) is caused by a CD4 T helper cell type 1 (Th1) response in the small intestinal mucosa to dietary gluten. As the major Th1 inducing cytokine, interleukin 12, is undetectable in CD gut mucosa, the mechanism by which Th1 effector cells are generated remains unknown. Interferon (IFN) alpha, a cytokine capable of promoting IFN-gamma synthesis, has been implicated in the development of Th1 mediated immune diseases. Here we report a case of CD-like enteropathy in a patient receiving IFN-alpha for chronic myeloid leukaemia. Morphological assessment of duodenal biopsies taken from the patient showed total villous atrophy, crypt cell hyperplasia, and a high number of CD3+ intraepithelial lymphocytes. Both antigliadin antibodies and antiendomysial antibodies were positive. RNA analysis revealed pronounced expression of IFN-gamma. Withdrawal of gluten from the diet resulted in a patchy improvement in intestinal morphology, normalisation of laboratory parameters, and resolution of clinical symptoms. By western blot analysis, IFN-alpha protein was seen in the duodenal mucosa from untreated CD patients but not in controls. This was associated with marked expression of IFN-gamma protein in CD mucosa. Collectively, these results suggest a role for IFN-alpha in promoting Th1 responses to gluten.

BACKGROUND: Degradation of the extracellular matrix and ulceration of the mucosa are major features of inflammatory bowel disease (IBD). One of the most important enzymes in degrading the matrix and produced in excess by cytokine activated stromal cells, is stromelysin-1. The activity of stromelysin-1 is controlled by tissue inhibitor of metalloproteinase (TIMP-1), its natural inhibitor. In model systems excess stromelysin-1 produces mucosal degradation. METHODS: Quantitative competitive RT-PCR was used to analyse stromelysin-1 and TIMP-1 transcripts; western blotting was used to measure the amount of stromelysin-1 and TIMP-1 protein in biopsy samples from children with IBD. RESULTS: In biopsies from patients with active Crohn's disease (n=24), ulcerative colitis (n=23), and controls (n=16), TIMP-1 transcripts and protein were abundant and unchanged. Stromelysin-1 transcripts and protein were markedly elevated in mucosal biopsies obtained from inflamed sites of patients with active IBD but were not elevated in adjacent endoscopically normal mucosa (n=10). Elevated levels of stromelysin-1 transcripts in active Crohn's disease (n=5) returned to normal levels following treatment with enteral nutrition. CONCLUSIONS: Stromelysin-1 is markedly overexpressed at inflamed sites in patients with IBD whereas TIMP-1 remains unaltered. Excess stromelysin-1 is likely to be responsible for loss of mucosal integrity in IBD.

BACKGROUND/AIM: Interleukin (IL) 12 is involved in the mucosal response during intestinal inflammation but its role is not fully understood. The response of human lamina propria T lymphocytes (T-LPL) to IL-12 in terms of interferon gamma (IFN-gamma) release and proliferation was investigated, exploring whether IL-15 and IL-7 cooperate with IL-12. The role of accessory molecules (CD2 and CD28) was also investigated. METHODS: Unstimulated and phytohaemagglutinin preactivated T-LPL cultures were incubated with or without the initial addition of cytokines, anti-CD2 or anti-CD28 antibodies. IFN-gamma mRNA was detected by reverse transcriptase polymerase chain reaction, and protein secretion was measured by enzyme linked immunosorbent assay (ELISA). RESULTS: IFN-gamma mRNA was induced in T-LPLs by IL-12 and IL-15 but not IL-7, whereas IFN-gamma was measured only in IL-12 stimulated T-LPL cultures. IL-12 induced IFN-gamma release was not abrogated by neutralising anti-IL-2 antibody or by cyclosporin A. IL-12 synergised with either anti-CD2 or anti-CD28 antibodies in inducing IFN-gamma synthesis. In preactivated T-LPLs, IL-7 enhanced IFN-gamma release induced by both IL-12 and anti-CD2, whereas IL-15 potentiated only IL-12 induced IFN-gamma synthesis. IL-12 did not induce proliferation of either unstimulated or preactivated T-LPLs and it did not enhance the CD2/CD28 stimulated T-LPL proliferative response. No transcript for IL-12 receptor beta1 subunit was detected in freshly isolated and activated T-LPLs whereas the beta2 subunit mRNA was consistently found in T-LPL samples. CONCLUSIONS: IL-12 induces human T-LPLs to produce and release IFN-gamma, and IL-15 and IL-7 cooperate with IL-12 in expanding the IFN-gamma mucosal response.