Increased NOX1 and DOUX2 Expression in the Colonic Mucosa of Patients with Chronic Functional Constipation

Abstract

Aim To determine whether oxidative stress and inflammation are associated with constipation by examining the expression of the main producers of reactive oxygen species, NADPH oxidases, and pro-inflammatory cytokines in the colon of patients with chronic functional constipation. Methods The colonic biopsies were collected from 32 patients with chronic functional constipation and 30 healthy subjects who underwent colonoscopy. Colonic mucosal histology was observed. IL-1β, IL-6, IL-8 mRNA, and four members of NADPH oxidase (NOX1, NOX2, DOUX2 and NOX4) protein and mRNA were assessed by immunohistochemistry, western blotting and RT-PCR. Results The tissues from both patients and healthy subjects showed normal histological structure without increase of inflammatory cells. NOX1 protein and mRNA levels were significantly increased compared to controls (P<0.05). DOUX2 protein, but not mRNA, was increased by twofold compared to controls (P<0.05). The levels of NOX2 and NOX4 protein and mRNA demonstrated no significant difference between patients and control subjects. The levels of IL-1β and IL-6 mRNA were significantly higher in constipation patients (P<0.05), while IL-8 mRNA level was no different between the two groups. Conclusion NADPH oxidase and pro-inflammatory cytokine might be involved in the pathogeneses of chronic functional constipation.