Published online Jun 21, 2013. doi: 10.3748/wjg.v19.i23.3602
Revised: April 1, 2013
Accepted: April 18, 2013
Published online: June 21, 2013
AIM: To study an assessment of the number of enterochromaffin cells and expression of hydroxyindole-O-methyltransferase in colonic mucosa and urine excretion of 6-sulfatoxymelatonin in patients with ulcerative colitis.
METHODS: The study included 30 healthy subjects (group I-C), 30 patients with ulcerative proctitis [group II-ulcerative proctitis (UP)] and 30 patients with ulcerative colitis [group III-ulcerative colitis (UC)] in acute phases of these diseases. The number of enterochromaffin cells (EC) was estimated in rectal and colonic mucosa. Bioptates were assembled from many different parts of the large intestine. Immunorective cells collected from various parts of the colon were counted according to the Eurovision DAKO (Dako A/S, Copenhagen, Denmark) System in the range of 10 fields in each bioptate at × 200 magnification. The level of mRNA expression of hydroxyindole-O-methyltransferase (HIOMT) in colonic mucosa was estimated with RT-PCR. Urine 6-sulfatoxymelatonin (6-HMS) excretion was determined immunoenzymatically using an IBL (IBL International GmbH, Hamburg, Germany) kit (RE 54031).
RESULTS: The number of EC cells in healthy subjects (C) was 132.40 ± 31.26. In patients of group II (UP) and group III (UC) the number of these cells was higher - 225.40 ± 37.35 (P < 0.001) and - 225.24 ± 40.50 (P < 0.001) respectively. Similar differences were related to HIOMT expression, which was 1.04 ± 0.36 in group C, 1.56 ± 0.56 (P < 0.01) in group UP and 2.00 ± 0.35 (P < 0.001) in group UC. Twenty-four hour 6-HMS urinary excretion was as follows: C - 16.32 ± 4.95 μg/24 h, UP - 26.30 ± 7.29 μg/24 h (P < 0.01), UC - 42.30 ± 12.56 μg/24h (P < 0.001). A correlation between number of EC cells and 6-HMS excretion was noted in all groups: r = 0.766 in patients with UP, r = 0.703 with UC and r = 0.8551 in the control group; the correlation between the results is statistically significant.
CONCLUSION: In the acute phases of both UP and UC, proliferation of EC cells and high expression of HIOMT and urine excretion of 6-HMS is noted. These changes may represent a beneficial response in the anti-inflammatory and defense mechanism.
Core tip: In the gastrointestinal tract melatonin is secreted mainly by enterochromaffin cells (EC). It appears that hydroxyindole-O-methyltransferase (HIOMT) is enzyme determining melatonin synthesis. This indoleamine exert, antioxidant, and anti-inflammatory effects. Its synthesis can be disturbed by pro-inflammatory cytokines. The obtained results noted the proliferation of EC cells and the increase of HIOMT expression in ulcerative colitis ulcerative colitis (UC). Positive correlation between the amount of EC cells and urinary 6-sulfatoxymelatonin excretion points to the increase of melatonin secretion in the colon, but its beneficial anti-inflammatory effect was insufficient. The results indicate that the supplementation of melatonin may be useful in complex treatment of UC.