Increased luminal release of hyaluronan in uninvolved jejunum in active Crohn's disease but not in inactive disease or in relatives.

Recently obtained data suggest that there is a subclinic inflammatory activity in the apparently uninvolved intestinal mucosa in Crohn's disease (CD). As CD is characterized by an activation of connective tissue and fibrosis, we investigated the extent to which hyaluronan (HA), an essential component of the connective tissue, was released into the lumen of an isolated jejunal segment in CD patients and in relatives. Patients with active CD of the terminal ileum (CD activity index, CDAI, > 150; n = 14), patients with CD in remission (CDAI < 150 n = 10), first-degree relatives of the CD patients (n = 21) and healthy controls (n = 43) were orally intubated with a catheter allowing occlusion and perfusion of a segment of the proximal jejunum. The jejunal fluid concentration of HA was 65 +/- 45 micrograms/l in patients with active CD in the terminal ileum, significantly higher than the value for 43 healthy controls (42 +/- 23 micrograms/l; p < 0.05), and the corresponding values for patients in remission (42 +/- 23 micrograms/l) and for first-degree relatives of the CD patients (53 +/- 52 micrograms/l), were not increased compared to the control group. To localize HA in the tissue, small bowel biopsies were taken during surgery from patients with CD and from controls and affinity stained for HA. There was an intense staining for HA in the lamina propria of the villi, both in biopsies from patients with CD and from controls, but no staining in the epithelium.(ABSTRACT TRUNCATED AT 250 WORDS)