Decreased faecal exoglycosidase activities identify a subset of patients with active Crohn's disease

1. α₁-Proteinase inhibitor (α₁-antitrypsin) is excreted in a deglycosylated form (M_r 38000) in the faeces of healthy subjects and in patients with quiescent Crohn's disease. By contrast, in most patients with active Crohn's disease, α₁-proteinase inhibitor is excreted in a glycosylated form (M_r 51000).

2. Faecal extracts containing deglycosylated α₁-proteinase inhibitor are able to deglycosylate α₁-proteinase inhibitor by an exoglycosidic process. Conversely, we demonstrate that in faecal extracts from patients excreting glycosylated α₁-proteinase inhibitor, glycosidase activities, such as N-acetyl-β-glucosaminidase (EC 3.2.1.30), α₁-mannosidase (EC 3.2.1.24) and particularly β-galactosidase (EC 3.2.1.23), are strongly decreased.

3. Degradation of glycosidases by proteases could not explain the decreased glycosidase activity in these faecal extracts.

4. Our data suggest that a modification of the bacterial colonic flora (or of its metabolic activity) occurs in most patients with active Crohn's disease and could be responsible for an impaired colonic salvage of carbohydrates.