Expression of decorin and biglycan in rat gastric tissue: effects of ulceration and basic fibroblast growth factor

The small chondroitin/dermatan sulphate proteoglycans decorin and biglycan participate in organizing the network of collagen fibrils and interact with non-collagenous matrix proteins. In addition, via interactions with cytokines they are directly or indirectly involved in signalling, growth and cell differentiation. We aimed to analyse their expression in normal gastric tissue and during gastric ulcer healing.

Proteoglycan expression was studied by immunohistochemistry and in situ hybridization in acetic acid-induced gastric ulcers in rat during early phases and during chronic ulceration. The effects of treatment with an acid stable mutein of FGF-2 (bFGF) were also studied.

In normal gastric tissue, both proteoglycans were most strongly expressed in the submucosal layer. However, some epithelial cells were positive for biglycan and, surprisingly, also for decorin. In the early phase after ulcer induction exclusively decorin became induced in the muscularis mucosae, while biglycan became detectable in this layer only after 2 weeks. There was no up-regulation of either proteoglycan in other layers, nor could an effect of FGF-2 treatment be seen.

The expression of decorin could be observed for the first time in epithelial cells. Decorin, but not biglycan, appears as an early phase reactant in the muscularis mucosae in accordance with its putative role during angiogenesis and the prevention of apoptosis.