Background: Estrogen deficiency in postmenopausal women causes an increased production of proinflammatory cytokines such as interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-α. These cytokines are associated with an increase of bone turnover and an acceleration of bone loss. Tumor necrosis factor-α is known to promote osteoclastogenesis via TNFR1, one of the tumor necrosis factor receptors (TNFR). Therefore, the purpose of the present report was to investigate the association of TNFR1 gene polymorphism with bone mineral density (BMD) in postmenopausal Japanese women.
Methods: The question of whether a polymorphism of the TNFR1 gene would correlate with osteoporosis in 320 unrelated healthy postmenopausal women in Japan, was investigated. A single nucleotide polymorphism (SNP) located at Pro12 (CCA to CCG) in exon 1 of TNFR1 was utilized.
Results: The subjects were categorized into three genotypes: AA, AG, and GG. The frequency of each genotype was 72.2%, 23.8%, and 4.0%, respectively. The association of this polymorphism with BMD of the lumbar spine and total body, and several bone metabolic markers was then examined. Concerning the TNFR1 gene, the AA group had significantly low total body BMD, compared with the AG + GG group (Z score; 0.285 vs 0.568; P = 0.03), although BMD of the lumbar spine was not statistically different.
Conclusion: These results suggest an association between this SNP of the TNFR1 gene and BMD, and an involvement of TNFR1 in postmenopausal osteoporosis among Japanese.