Enkephalin degradation in serum of patients with inflammatory bowel diseases

Background: Inflammatory bowel diseases (IBD) are a group of chronic and recurrent gastrointestinal disorders that are difficult to control. Recently, a new IBD therapy based on the targeting of the endogenous opioid system has been proposed. Consequently, due to the fact that endogenous enkephalins have an anti-inflammatory effect, we aimed at investigating the degradation of serum enkephalin (Met- and Leu-enkephalin) in patients with IBD. Methods: Enkephalin degradation in serum of patients with IBD was characterized using mass spectrometry methods. Calculated half-life (T-1/2) of enkephalins were compared and correlated with the disease type and gender of the patients. Additionally, statistical analysis was used to examine the dynamics of changes in terms of inhibition of enkephalins degradation within research groups. Results: Our research indicates that the degree of enkephalins degradation depends on the gender of the patients. The difference is most evident for the rate of Met-enkephalin degradation between men (mean T-1/2 = 13.61 min) and women (mean T-1/2 = 21.84 min) with Crohn's disease (CD). Conclusions: The most significant alternation of enkephalins degradation in serum samples of IBD patients, compared to control group, were observed in both Crohn's disease and ulcerative colitis (UC) female patients. We suggest that the differences observed between the genders in IBD patients may be explained by regulation of enkephalinases activity by estradiol. (c) 2018 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.