The behavior of matrix metalloproteinase-9 in lymphocytic colitis, collagenous colitis and ulcerative colitis.

Matrix metalloproteinases play an important role in extracellular matrix remodelling. It has been proposed that matrix metalloproteinase-9 (MMP-9) is involved in epithelial damage in ulcerative colitis (UC). However, to our knowledge, no data are available in terms of MMP-9 expression in microscopic colitis. Determination of mucosal protein expression levels of MMP-9 in lymphocytic colitis (LC), collagenous colitis (CC) and UC. MMP-9 immunohistochemical expressions were analyzed in paraffin-embedded tissue samples by immunohistochemistry including patients with LC, CC, UC, active diverticulitis, inactive diverticular disease and healthy control subjects. UC was also subgrouped according to the severity of inflammation. Immunostaining was determined semiquantitatively. Independent colonic biopsies from healthy and severe UC cases were used for gene expression analyses. For further comparison MMP-9 serum antigen levels were also determined in patients with UC and control patients without macroscopic or microscopic changes during colonoscopy. MMP-9 mucosal expression was significantly higher in UC (26.7 ± 19.5%) compared to LC (6.6 ± 9.3%), CC (6.4 ± 7.6%), active diverticulitis (5.33 ± 2.4%), inactive diverticular disease (5.0 ± 2.2%) and controls (6.3 ± 2.6%) (P < 0.001). The immunohistochemical expression of MMP-9 in LC and CC was similar as compared to controls. MMP-9 expression was significantly higher in each inflammatory group of UC compared to controls (mild: 11.0 ± 2.8%, moderate: 23.9 ± 3.7%, severe UC: 52.6 ± 3.9% and 6.3 ± 2.6%, respectively, P < 0.005). The gene expression microarray data and RT-PCR results demonstrated a significantly higher expression of MMP-9 in severely active UC compared to healthy controls (P < 0.001). Significantly higher MMP-9 serum antigen concentrations were observed in UC patients compared with the control group (P < 0.05). MMP-9 seems to play no role in the inflammatory process of LC and CC. In contrast, the mucosal up-regulation of MMP-9 correlated with the severity of inflammation in UC. The increased MMP-9 expression could contribute to the severity of mucosal damage in active UC.

Allelic variation of the matrix metalloproteinase-9 gene is associated with collagenous colitis.

BACKGROUND: Collagenous colitis is a chronic inflammatory bowel disease of unknown origin characterized by a thickened subepithelial collagen layer. Differential expression of matrix-metalloproteinases (MMPs) have been implicated in the pathogenesis of collagenous colitis. The aim was to assess genetic polymorphisms of MMP-1, -7, and -9 in a case-control setting for susceptibility to collagenous colitis. METHODS: Seventy-five patients with symptomatic collagenous colitis and 334 healthy blood donors were genotyped for single nucleotide polymorphisms (SNPs) in MMP-1-1607, MMP-7-153, MMP-7-181, and MMP-9 exon 6 using TaqMan technology. Susceptibility to collagenous colitis was tested by comparison of the carrier status of the rare allele. RESULTS: The carrier frequency of the allele GG of the coding SNP MMP-9 in exon 6 was 24% in patients with collagenous colitis and 14.3% in healthy blood donors (P = 0.039). The carriage of the allele GG significantly increased the risk for collagenous colitis with an odds ratio of 1.9 (95% confidence interval: 1.0-3.5). None of the other SNPs of MMP-1, MMP-7-153, and MMP-7-181 were associated with collagenous colitis. CONCLUSIONS: Allelic variation in the MMP-9 gene may be part of a complex genetic risk profile for collagenous colitis. Further studies are needed to confirm this observation and to explore the functional role of this gene polymorphism in collagenous colitis.

Cyclooxygenase-2 immunoreactivity in collagenous colitis.

Collagenous colitis (CC) is an inflammatory bowel disease of unknown aetiology and pathogenesis. In ulcerative colitis and Crohn's disease, prostaglandins may be involved in the pathogenesis of inflammation, and increased expression of cyclo-oxygenase-2 (COX-2) has been detected. The purpose of this study was to examine the presence and cellular localization of COX-2 in colonic mucosa of patients with CC. Using immunohistochemistry, immunoflouresence and Western blot analysis, COX-2 expression was evaluated in colonic mucosal biopsies from 10 patients with active untreated CC, and compared with samples from eight normal controls, and samples from eight patients with ulcerative colitis or Crohn's disease. Specimens from patients with CC expressed COX-2 protein in increased amounts compared with controls, but similar to patients with ulcerative colitis and Crohn's disease. COX-2 expression was localized to the mononuclear cells of the lamina propria. COX-2 expression was most evident in macrophages. Co-localization of COX-2 and macrophages was increased in number in comparison with controls. In conclusion COX-2 is expressed in increased amounts primarily in the macrophage subpopulation of the inflammatory infiltrate of lamina propria in CC. Increased recruitment of macrophages, increased expression of COX-2 and increased prostaglandin synthesis may be involved in the pathogenesis of CC.

Budesonide treatment and expression of inducible nitric oxide synthase mRNA in colonic mucosa in collagenous colitis.

OBJECTIVE: In collagenous colitis, the production of nitric oxide in the colon is found to be 50 to 100-fold higher than in healthy controls. The role of nitric oxide in collagenous colitis is debated and it has been suggested that nitric oxide has a causative role in diarrhoea. The aim of this study was to examine the possible effect of budesonide treatment on the level of inducible nitric oxide synthase mRNA. METHODS: In 20 patients with collagenous colitis, clinical activity was assessed by registration of the daily stool frequency and stool weight. Sigmoidoscopy was performed and biopsies for histological examination and one biopsy for determination of inducible nitric oxide synthase mRNA was obtained in 16 patients. RESULTS: Budesonide treatment was followed by a significant reduction of inducible nitric oxide synthase mRNA (P<0.01) whereas no change was observed after placebo treatment. Significant correlations between inducible nitric oxide synthase mRNA and the grade of inflammation (rho=0.47; P<0.01), the daily stool weight (rho=0.51; P<0.005) and the daily stool frequency (rho=0.49; P<0.005) were observed. No significant association was observed between inducible nitric oxide synthase mRNA and the thickness of the collagen layer. CONCLUSIONS: In patients with collagenous colitis, treatment with budesonide results in a reduction of inducible nitric oxide synthase mRNA. The level of inducible nitric oxide synthase mRNA in colonic mucosa correlates with the inflammatory and clinical activity. The results support that nitric oxide is a central factor in the pathogenesis of collagenous colitis.