Fecal eosinophil granule-derived proteins reflect disease activity in inflammatory bowel disease

The aims of this study were: 1) to examine whether the fecal levels of eosinophil granule-derived proteins reflect disease activity in inflammatory bowel disease (IBD); and 2) to examine the extracellular release of these proteins from eosinophils and their stability in feces by an in vitro study.

We investigated 42 patients with ulcerative colitis (UC), 37 patients with Crohn's disease (CD), and 29 control subjects. The stool samples were collected at 4 degrees C over 48 h and were homogenized. The fecal levels of eosinophil cationic protein (ECP) and eosinophil protein X (EPX) were measured by radioimmunoassay. Fecal Hb (Hb), alpha1-antitrypsin (AT), and lactoferrin (Lf) were also measured by ELISA.

Fecal ECP and EPX concentrations were significantly increased in both active UC and active CD compared to inactive UC and inactive CD, respectively. Fecal EPX concentration correlated with the fecal Hb, AT, and Lf concentrations more closely than fecal ECP concentration. Even in the inactive stage, CD patients who relapsed within the following 3 months showed higher fecal ECP and EPX concentrations compared to the patients who did not. EPX was released extracellularly more efficiently than ECP (18.6% vs 6.3%, after incubation for 15 min at 25 degrees C). EPX was more stable in the feces than ECP.

The measurement of eosinophil granule-derived proteins in feces is useful for evaluating disease activity and predicting relapse in patients with IBD. EPX may be more suitable than ECP as a fecal eosinophil marker.