Angiotensin-converting enzyme activity in stools of healthy subjects and patients with celiac disease

Angiotensin-converting enzyme (ACE) is a dipeptidylcarboxypeptidase that occurs in three types of cells: endothelial, epithelial, and neuroepithelial. ACE activity is present in plasma, urine, and vascular endothelium. High levels of ACE are found in the brush border of human small bowel. The aim of this study was to evaluate ACE activity in human stools and to find a correlation with the intestinal loss of epithelial cells. Fifteen healthy subjects (HS) (8 males, 7 females; age range 6–56 years), 20 patients with celiac disease (CD) (11 males, 9 females; age range 15–53 years), and 18 patients with CD in remission after a gluten-free diet (CD-GFD) (8 males, 10 females; age range 14–54 years) were enrolled in the study. The fecal ACE activity was measured in all groups. Fecal samples were kept at –20°C for a subsequent test. In HS, fecal ACE activity was 21.03±16.17 nmol/min/100 g (mean ±sd). In patients with CD with subtotal mucosa atrophy, ACE activity was significantly higher (113 ± 88.94) than in HS and CD on GFD (36.65±23.9). We have demonstrated ACE activity in human stools. ACE activity in stools seems to derive from the microvilli of the intestinal mucosa, thus suggesting the potential usefulness of ACE determination as an index of enterocyte damage.