Evaluation of interleukin-1 and -6 in the etiopathogenesis of idiopathic osteoporosis and osteopenia in children.

INTRODUCTION: The aim of the study is to determine whether serum concentrations of interleukin (IL)-1and IL-6 correlate with indices of bone mineral metabolism in children with idiopathic osteoporosis and osteopenia. MATERIAL/METHODS: The study comprised 62 patients aged 6-18 years (20 with idiopathic osteoporosis, 22 with idiopathic osteopenia, and 20 controls). In 10 children, investigations were repeated after one year of treatment. Serum concentrations of IL-1alpha, IL-1beta, IL-1 receptor antagonist (IL-1ra), as well as IL-6 and its soluble receptor (IL-6sR) were determined by the ELISA method. In patients with decreased bone mass, selected calcium-phosphorus metabolism indices and bone turnover markers were assessed. RESULTS: Higher values of IL-6 were recorded in those with idiopathic osteoporosis than in controls (2.79 vs. 1.43; p<0.05). In these patients there was also a tendency towards higher values of IL-6sR (p=0.05). IL-1alpha and IL-1beta were not markedly elevated in any of the patients. No significant differences between groups regarding IL-1ra were observed. Negative correlation between IL-6, IL-1alpha, cytokine/receptor indices, and spinal bone mineral density was determined. Positive correlation was found between IL-alpha, IL-1/IL-1ra, and parathormon as well as between IL-1alpha, IL-6sR, and bone formation markers.markers. Increase in bone mass after treatment was accompanied by a decrease in IL-6sR. CONCLUSIONS: The higher serum levels of IL-6 in children with idiopathic osteoporosis/osteopenia and the decrease in IL-6sR after treatment reveal an involvement of IL-6 in the etiopathogenesis of these disturbances. The results suggest that IL-1 may also participate in the primary decrease of bone mass in children.