Interleukin 6, osteoprotegerin, sRANKL and bone metabolism in inflammatory bowel diseases

Cytokines are mediators of inflammatory processes in the course of inflammatory bowel disease (IBD) and participate in the bone metabolism. Interleukin 6 (IL-6) initiates osteoclastogenesis by modulating the activity of soluble receptor activator of nuclear factor kappa B ligand (sRANKL) and osteoprotegerin.

The aim of the study was to evaluate bone mineral density (BMD) by densitometry and the concentration of interleukin 6, osteoprotegerin (OPG) and sRANKL protein (sRANKL) by ELISA in patients with IBD in relation to the control group; to assess the relationship between IL-6, OPG, sRANKL and BMD; and to assess the impact of disease duration and number hospitalization on BMD.

The studied group included 37 patients with Crohn's disease (I - CD), 37 patients with ulcerative colitis (II - UC) and 37 healthy subjects - control group (III - CG).

The prevalence of osteoporosis and osteopenia was as follows: in I - CD, 18.92% and 32.43% in L2-L4; 13.51% and 35.13% in the neck, and in II - UC, 2.7% and 37.84% in L2-L4; 2.7%, and 29.73% in the femoral neck. The concentration of IL-6 correlated negatively with T-scores in the neck for the whole group, and in group I - CD, there was a significant positive correlation between serum OPG and IL-6.

The incidence of osteopenia and osteoporosis in patients with IBD is high and increases with the duration of the disease and the number of hospitalizations. Patients with CD are at a higher risk of skeletal pathology than patients with UC. IL-6 can modulate bone mineral density in the femoral neck especially in the course of CD.