Leptin plays not only an important role in regulation of food intake, but also in the mechanism of
inflammation. The universal presence of
leptin in the cells of immune system and its secretion by these cells caused increasing interest in the role of this
hormone in
ulcerative colitis (UC). We determined the role of
leptin in 80 patients, aged from 18 to 69 years, including 50 patients with active UC and 30 patients with infectious
diarrhea. The tests were performed within 48 hours of the first symptoms, in the period of remission of UC and 8 weeks after resolution of infectious
diarrhea. Endoscopy was performed in each patient, and the biopsy samples were taken for the assessments of expression of
mRNA for
leptin, IL-1β,
IL-6 and TNF-α by RT-PCR and Western blot. Blood tests included concentrations of
leptin, IL-1β,
IL-6 and TNF-α. In addition, the plasma levels of
leptin, IL-1β,
IL-6 and TNF-α were assessed by ELISA. Serum concentrations of
leptin was significantly increased in patients with exacerbation of UC over that in patients with UC in remission. The serum
leptin concentration was significantly higher in patients with infectious
diarrhea, than the patients that recovered from infectious
diarrhea. The
leptin protein was overexpressed in the biopsy samples of the mucosa of large intestine compared to those with exacerbation of UC, and in patients after successful recovery from infectious
diarrhea. The
leptin mRNA was overexpressed in patients with infectious
diarrhea compared with that in the group of patients after successful recovery from this condition. Serum concentrations of
leptin failed to correlate with severity of exacerbation of UC and with extent of intestinal inflammatory lesions in patients with UC. However, the correlation was observed between serum concentrations of
leptin in patients with exacerbation of UC and serum concentrations of proinflammatory
cytokines IL-1β and TNF-α. We conclude that 1) the increased
leptin in exacerbated UC is related to the increased serum proinflammatory
cytokines IL-1β, TNF-α and IL-6 levels; 2) In patients with infectious
diarrhea, the concentrations of
leptin in intestinal mucosa correlates with serum concentrations of
cytokines IL-1β, IL-6 and TNF-α and with an increased expression of
leptin mRNA in intestinal mucosa but not with alterations in serum levels of this
hormone; 3)
leptin may serve as useful predictive marker of
inflammation in
inflammatory bowel disease (IBD).