Osteoprotegerin and soluble receptor activator of nuclear factor κB ligand in children with inflammatory bowel disease

Introduction: Osteoprotegerin (OPG) and receptor activator of nuclear factor κB ligand (RANKL) are cytokines that play a key role in bone metabolism but also in the immune system. Ulcerative colitis (UC) and Crohn’s disease (CD) are autoimmune inflammatory bowel diseases (IBD), affecting digestive system but also bone mineralization.

Aim: To evaluate serum concentrations of osteoprotegerin and the sRANKL and their relationship with certain parameters in children with IBD.

Material and methods: The study included 93 children treated at the Department of Pediatrics, Gastroenterology, Hepatology and Nutrition, Medical University of Gdansk:

18 with UC, 24 with CD, 51 healthy children. The OPG and sRANKL were detected with a commercial ELISA kit. Bone mineral density (BMD) was assessed by means of dual energy X-ray absorptiometry (DXA) in IBD patients.

Results: The higher concentrations of osteoprotegerin were in the IBD group (range 0.20-0.73 pmol/l, SD 1.35, median 4.10 pmol/l) than in the control group (0.03-0.2 pmol/l, SD 1.72, median 3.61 pmol/l). The concentration of sRANKL could be determined only in a fraction of patients; imore often measurable (p = 0.001) and of higher values in IBD children compared to the control group (p < 0.02). Children with more active disease had lower osteoprotegerin concentrations. Nearly 29% of patients had decreased BMD, more often boys than girls (p < 0.036). Children with lower BMD had significantly lower sRANKL concentration

(p < 0.03).

Conclusions: Evaluation of OPG and sRANKL does not seem to be useful in diagnosis of IBD in children with disorders of bone mineralization. The complete meaning of these cytokines remains unclear.