Positive association between leptin serum levels and disease activity on endoscopy in inflammatory bowel disease: A case-control study

Abstract

Inflammatory bowel disease (IBD) includes ulcerative colitis (UC), Crohn's disease (CD) and indeterminate colitis. As these subtypes of IBD display important differences in the behavior of the natural course of the disease, the identification of non-invasive markers for IBD is important. The aim of the present study was to evaluate the serum levels of 10 adipokines and their association with endoscopic activity in IBD. The 10-protein profile (C-peptide, ghrelin, gastric inhibitory polypeptide, glucagon-like peptide-1, glucagon, insulin, leptin, plasminogen activator inhibitor-1, resistin and visfatin) was evaluated using serum from 53 participants (23 UC and 11 CD patients, as well as 19 controls) from Zacatecas (Mexico) by using the Bio-Plex Pro Human Diabetes 10-Plex Panel (Bio-Rad Laboratories, Inc.). Compared with those in the controls, leptin levels were significantly lower in patients with IBD (P=4.9×10^-4). In addition, serum leptin displayed differences between groups with and without disease activity on endoscopy (P<0.001). Among the study population, serum leptin levels of <5,494 pg/ml significantly increased the odds of IBD by 12.8-fold [odds ratio (OR)=12.8, 95% confidence interval (CI)=3.04-53.9, P=0.001]. In addition, patients with serum leptin levels of <2,498 pg/ml displayed 5.8-fold greater odds of disease activity on endoscopy among the study population (OR=5.8, 95% CI=1.52-22.4, P=0.013). No differences in the serum levels of the remaining proteins were identified between the groups. Among the study population, serum leptin was associated with an increased risk of IBD and with disease activity on endoscopy. Additional studies will be necessary to validate the use of leptin as a non-invasive biomarker of IBD severity.

Keywords: adipokines; bowel disease; endoscopic activity; inflammation; leptin.

Figure 1.

Serum concentrations of leptin and disease activity in groups with and without endoscopic activity. Leptin levels were determined at baseline and using the healthy control group as a reference, the serum leptin concentration (pg/ml) was compared between the patients with and without endoscopic activity in the (A) inflammatory bowel disease (B) Crohn's disease and (C) ulcerative colitis groups. Values are expressed as the mean ± standard deviation from duplicate readings.

Figure 2.

Modulation of the serum concentration of leptin with treatment. The IBD patients were stratified into 5-ASA, 5-ASA+azathioprine and 5-ASA+adalimumab groups according to their pharmacological therapy. The serum levels of leptin (pg/ml) in the (A) IBD, (B) Crohn's disease and (C) ulcerative colitis patients were compared with those in the control group as a reference. Values are expressed as the mean ± standard deviation from duplicate readings. IBD, inflammatory bowel disease; ASA, 5-aminosalicylic acid.

Figure 3.

Association of serum leptin concentration with the extent of the disease. (A) Comparison of serum leptin concentration (pg/ml) with extent of disease in UC patients. UC patients were classified into right colitis and pancolitis groups and compared with the healthy control group. (B) Comparison of serum leptin concentration (pg/ml) with extent of disease in CD patients. CD patients were classified into colon, colonic ileum and terminal ileum and compared with the healthy control group. Values are expressed as the mean ± standard deviation from duplicate readings. UC, ulcerative colitis; CD, Crohn's disease.