Background: In this study, we determined the serum levels of IL-17A and IL-10 in context with 1, 2 dihydroxy vitamin D3, parathormone and Ca²⁺/Pi ions to investigate their pathological or protective roles respectively in bone metabolism.

Methods: The bone mineral density (BMD) was determined for 1203 participants using energy X-ray absorptiometry. Subjects with a history of diseases and using bone metabolism medications were excluded and finally serum IL-10 was measured in 82 osteoporotic and 74 healthy individuals (mean age ±SD of 71.04±6.9 and 68.58±6.9 respectively). Also, the serum level of IL-17A was assessed in 42 osteoporotic and 39 non-osteoporotic subjects (mean age±SD of 69.40±6.7 and 70.77±7.1, respectively). Serum levels of 1, 25-dihydroxyvitamin D3, Ca²⁺/Pi ions and parathormone were extracted from AHAP cohort data bank.

Results: IL-17A was detectable in 7.42(16.67%) osteoporotic subjects and 3.39(7.69%) normal subjects. Surprisingly, patient subjects exhibited a higher level of serum IL-10 than normal subjects (P=0.023). We found that the serum parathormone levels tend to increase in patient group (P=0.003) in comparison to normal control with no correlation with Il-10 levels. There was no significant difference between the two groups in the serum levels of 1, 25-dihydroxyvitamin D3, Ca²⁺and P_i ions.

Conclusion: In reaction to chronic inflammation old osteoporotic patients independent of 1, 25 dihydroxy vitamin D3 may produce a higher level of IL-10 to dampen production of inflammatory cytokines including IL-17A which in turn leads to speeding up parathormone production ultimately reaching a new homeostasis status in bone metabolism with normal serum Ca²⁺ /Pi ions.