Background & aims: Several indices evaluate disease activity in ulcerative colitis, but most have drawbacks to their application (invasiveness, complexity, or lack of specificity), and discrepancies between them are frequent. Assuming that desquamation of epithelial and inflammatory cells increases in damaged colonic mucosa, we hypothesized that fecal excretion of human DNA is an index of mucosal inflammation and damage. The aim of our study was to determine whether excretion of human DNA is useful in the evaluation of disease activity in ulcerative colitis.
Methods: Thirty-one controls and 36 ulcerative colitis patients were included. Ulcerative colitis patients and controls underwent colonoscopic examination after preparation by gut lavage with polyethylene-glycol electrolyte solution. In patients, disease activity was established using the clinical index of Rachmilewitz and an endoscopic score. Feces and gut lavage fluid were obtained and DNA levels were measured by quantitative polymerase chain reaction of the human beta-globin gene.
Results: Fecal DNA excretion correlated with the clinical index (r = 0.59, P < 0.05) and the endoscopic score (r = 0.76, P < 0.01). Gut lavage fluid DNA levels also correlated with clinical and endoscopic activity scores (r = 0.41 and 0.51, respectively, P < 0.05). Fecal DNA excretion was significantly higher in patients with endoscopically or clinically active disease than in controls or patients in remission. Fecal DNA excretion discriminates between endoscopically active disease and remission (sensitivity 0.67, specificity 1.00, P < 0.01).
Conclusions: Excretion of human DNA in feces, as an expression of cellular desquamation, is a novel noninvasive technique to objectively assess disease activity in ulcerative colitis.