Purpose: In addition to its neuronal specificity, nerve growth factor (NGF) plays a role in immuno-inflammatory events. Cells involved in osteoporosis, in particular mesenchymal stem/stromal cells and monocytes/macrophages, are capable of producing NGF. The question was whether NGF might be involved in osteoporotic bone loss independent of age.

Methods: Sixty postmenopausal Hungarian women were studied for serum NGF-β and MCP-1 levels, total lumbar spine and forearm osteoporosis, and femoral neck osteoporosis. Biochemical data were measured by enzyme-linked immunosorbent assay and presented as geometric mean (95% CI). Dual-energy X-ray absorptiometry was used to measure bone mineral density (BMD) and T-score values in three bone regions. Multiple regression analysis was used to identify the independent variables involved in the elevated NGF-β levels.

Results: Serum NGF-β levels were significantly increased in the osteoporotic subgroup compared to the normal and osteopenic subgroups [15.85(8.99-27.91) vs. 12.42(8.28-18.64) pg/ml, p<0.004 and 12.49(9.36-16.65) pg/ml, p<0.002, respectively] in the total lumbar spine region. Using multiple regression analysis, serum MCP-1 levels alone and their interaction with lumbar spine BMD were significant with elevated serum NGF-β levels, age was not included in the model. Increased serum NGF-β levels were restricted to the lumbar spine, but not to forearm and femoral neck osteoporosis.

Conclusion: Increased serum NGF-β levels were associated with the severity of lumbar spine osteoporosis. Increased sympathetic and sensory neural activity may contribute to the presence of pain and neuropathy in osteoporosis.