Osteoprotegerin, s-RANKL, and selected interleukins in the pathology of bone metabolism in patients with Crohn's disease

Introduction: Crohn's disease (CD) promotes the development of osteopaenia/osteoporosis, the cytokine background of which is not fully known.

Aim: Evaluation of bone mineral density (BMD), the prevalence of osteopaenia and osteoporosis, and the determination of the levels of selected interleukins (IL), osteoprotegerin (OPG), and s-RANKL proteins in patients with CD in relation to a control group and assessment of the relationship between the tested cytokines, OPG, s-RANKL, and BMD.

Material and methods: Thirty-seven CD patients and 37 healthy volunteers (control group) were enrolled into the study. Densitometry of the lumbar spine (L2-L4) and of the femoral neck using the DXA technique was carried out. Serum levels of: IL-13, IL-4, IL-17, IL-1β, OPG, and s-RANKL were determined using the ELISA method. Progression-of-disease questionnaires were collected.

Results: The prevalence of osteoporosis and osteopaenia in the CD group was: 18.92% and 32.43% in L2-L4; 13.51% and 35.13% in the neck, respectively. The IL-13 and IL-1β concentrations were significantly higher and OPG was significantly lower in CD patients when compared to controls. In the case of all subjects: IL-13 correlated negatively with the BMD of the neck, IL-17 correlated negatively with the Z-score of L2-L4, and OPG correlated negatively with the IL-13. In the case of CD patients, IL-4 correlated negatively with the BMD of L2-L4.

Conclusions: The incidence of osteopaenia and osteoporosis in Polish CD patients is high. IL-13, IL-1β, and IL-4 seem to be connected with the pathology of decreased BMD in CD. It can be hypothesised that IL-13 may lower BMD by modulating OPG.