Disruption of sulphated glycosaminoglycans in intestinal inflammation

We have studied the distribution and nature of sulphated glycosaminoglycans (GAGs) within normal and inflamed intestine. There is increasing evidence that these negatively charged polysaccharides, which both regulate the ability of albumin to leave the vasculature and inhibit thrombosis, may be affected by inflammatory cells and their products. We obtained samples of freshly resected intestinal tissue from eight controls, eleven patients with Crohn's disease, and six with ulcerative colitis. Sulphated GAGs were detected by means of a gold-conjugated poly-L-lysine probe, and the tissue density of anionic sites was assessed semiquantitatively by means of a Lennox graticule. In normal intestine there was staining in the vascular endothelium and the subepithelial basal lamina and throughout the extracellular matrix of the lamina propria and submucosa. Tissue from the patients with inflammatory bowel disease showed inflammation macroscopically and on histology. There were profound abnormalities of extracellular matrix GAGs, limited to the mucosa in ulcerative colitis and greatest in the submucosa in Crohn's disease. There was also substantial loss of GAGs from the subepithelial basal lamina in both disorders and from the vascular endothelium in submucosa in Crohn's disease. The extent of local GAG disruption was associated with the distribution of macrophages immunoreactive for tumour necrosis factor alpha and the activation marker RM 3/1. We suggest that inflammatory disruption of vascular and connective tissue GAGs may be an important pathogenetic mechanism, contributing to the leakage of protein and fluid, thrombosis, and tissue remodelling seen in inflammatory bowel disease.