Elevated expression of hyaluronan and its CD44 receptor in the duodenal mucosa of coeliac patients

AIMS: Since hyaluronan (HA) metabolism is disturbed in some malignant tumours and in inflammatory diseases, we analysed HA and its receptor CD44 as well as the expression of the Ki67 nuclear protein, a marker of cell proliferation, in histological sections of duodenal biopsies of coeliac disease patients and controls. METHODS AND RESULTS: The study group consisted of 52 patients with coeliac disease in remission, 40 patients with newly diagnosed disease and 10 healthy control subjects. HA was detected with a specific biotinylated probe prepared from cartilage aggrecan and link protein, and CD44 with an antibody recognizing all forms of CD44 and another specific for its v6 variant. For the expression of the nuclear protein, monoclonal antibody MIB-1 was used. The percentage of HA-positive cells in surface epithelium was higher in newly diagnosed patients (13%) compared with patients in remission (11%) and controls (2%). In addition, HA intensity in the lamina propria was decreased in the newly diagnosed patients. In patients with active disease, 22-26% of the surface epithelium was CD44+, whereas the corresponding figure in patients in remission was 5%, and that of controls 1%. The more intensive MIB-1 labelling in the duodenal epithelium of coeliac patients without treatment was normalized after gluten-free diet. CONCLUSIONS: The HA-positive coat on surface epithelium seen even in patients in remission suggests persistent or even permanent changes in the epithelial permeability barrier in coeliac disease.