Association between circulatory levels of adipokines and bone mineral density in postmenopausal women

Objective:Epidemiological evidence indicates that excess fat may be beneficial for bone health, offering protective effects against the onset of postmenopausal osteoporosis. Experimental data suggest that this link might be due to the direct effect of adipokines on bone tissue. Confirmatory evidence of this association, however, remains limited.Methods:The levels of a panel of selected adipokines including interleukin (IL)-6, -8, -1, adipsin, lipocalin-2/neutrophil gelatinase-associated ipocalin, tumor necrosis factor alpha, monocyte chemoattractant protein-1, plasminogen activator inhibitor-1, hepatocyte growth factor, resistin, leptin, and adiponectin in a group of osteopenic and osteoporotic postmenopausal women were compared with those of unaffected women (n=127).Results:Univariate analysis revealed that leptin and adiponectin were significantly correlated with bone mineral density (BMD). In particular, leptin was positively associated with BMD of the spine (r=0.22, P<0.05), femoral neck (r=0.23, P<0.05), trochanter (r=0.20, P<0.05), and total hip (r=0.27, P<0.01), whereas adiponectin was inversely correlated with BMD at the trochanter (r=-0.21, P<0.05). No correlations were, however, significant after adjusting for body fat variables. Stratification of the sample according to IL-6 levels revealed that adiponectin remained significantly inversely associated with BMD, regardless of fat levels and age (=-0.29, P<0.05; r(2)=0.198) in the subgroup of participants with low levels of IL-6.Conclusions:Our data suggest that circulating adiponectin is inversely associated with markers of bone health in postmenopausal women, and that the interaction is influenced by IL-6 levels.