Type IV collagen immunoreactivity of basement membrane in inflammatory-regenerative and dysplastic lesions of the flat colonic mucosa.

UNLABELLED The aim of this research is to establish by immunohistochemistry if there is a change in the expression of collagen type IV, as a substitute of basement membrane, in development of epithelial dysplasia in chronically inflamed colon mucosa. METHODS Biopsy specimens from 270 patients were examined: 74 were classified as inflammatory-regenerative and 196 as dysplastic lesions. There were 108 cases of mild dysplasia, 58 cases of moderate and 30 cases severe dysplasia, respectively. Visualisation of collagen IV and its way of expression within basement membrane of glandular crypts was performed by immunohistochemistry and then compared with findings in normal colon mucosa and colon adenocarcinoma tissue. RESULTS Changes in the expression of collagen IV comprised of its focal irregularities, diffuse thinning and/or thickening, focal interruptions or its complete absence. Significant changes in the expression of collagen IV in relation to normal mucosa already occur in inflammatory-regenerative mucosa. In mild dysplasia, these changes are more intensive in relation to those in inflammatory altered mucosa as well as at severe dysplasia in relation to moderate dysplasia. Changes in the expression of collagen IV in severe dysplasia are significantly more serious than in moderate dysplasia but are identical to those in colon adenocarcinoma tissue. CONCLUSION These findings suggest that change in the expression of collagen IV is in correlation to a degree of epithelial dysplasia that developed in flat chronically inflamed colon mucosa.