Myeloperoxidase expression in human colonic mucosa is related to systemic oxidative balance in healthy subjects.

OBJECTIVES

To improve understanding of the preclinical stage of colonic inflammation by exploring the existence of a link between early inflammatory changes in the colonic mucosa and the systemic redox balance.

METHODS

Clinical characteristics, a fasting blood draw, and mucosal biopsies from the right, left, and sigmoid-rectum colonic tracts collected from 28 healthy individuals (14/14 males/females) who underwent colonoscopy. Myeloperoxidase (MPO) positive cells infiltrating colonic mucosa specimens were assessed by immunohistochemistry, and patients divided into high or low MPO expressing cells/optical field groups (MPO or MPO, respectively).The systemic oxidative balance has been studied through derived-Reactive Oxygen Metabolites (d-ROMs), Biological Antioxidant Potential (BAP), and Lipoperoxide-cholesterol Oxidizing (LP-CHOLOX) tests on serum.

RESULTS

MPO patients demonstrated an increased systemic oxidative stress compared to MPO individuals (P = 0.035), especially when MPO is referred to the left-sided colonic mucosa (P = 0.007). MPO subjects in the sigmoid-rectum showed a significant higher antioxidant capacity in the serum (P < 0.02). Sex-specific differences in MPO expression (male and female: 4.6 ± 3.2 and 2.6 ± 1.5 MPO-positive cells/optical field, respectively, P = 0.044), and a decreasing gradient in MPO expression moving from the cecum to the rectum (ascendant, descendant, and sigmoid-rectum: 3.7 ± 2.8, 3.1 ± 1.7, and 1.4 ± 0.5, respectively, P = 0.012) were also found and discussed.

DISCUSSION

The study is the first demonstrating a connection between systemic redox balance and MPO expression in the colonic mucosa, according to the colonic tract and patient gender. Further research evaluating the MPO expression in the human colon and its relationship with pathological conditions could benefit from these results.