The influence of interleukin-6 and tumor necrosis factor α gene polymorphisms on bone mineral density in postmenopausal women

Summary Proinflammatory cytokines, interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α), involved into osteoclastogenesis and responsible for bone resorption process, participate in the pathogenesis of the osteoporosis. In vitro studies have shown that single nucleotide polymorphisms of IL-6 and TNF-α genes could influence the transcription process of the genes and the cytokines level. Aim: Assessment of the influence of IL-6 and TNF-α gene polymorphisms on bone mineral density (BMD) and evaluation of their connection with osteoporosis prevalence in women from Wielkopolska region. Material and methods: In the group of 267 postmenopausal women (average age 58,5+/-5,9 years, average age of last period 49,8+/-3,9 years) bone mineral density in lumbar spine (L2-L4) was performed using dual energy X-ray absorptiometry (DXA). Genotypes frequencies were determined by polymerase chain reaction with restriction fragment length polymorphism (PCR/RFLP) using restriction enzymes Lwe I and Faq I, respectively. The connection between the polymorphisms of investigated genes and body mass index, age of menarche and menopause and length of reproductive age had been analyzed as well. Results: No statistically significant association was found between examined genetic factors and the value of bone mineral density in the investigated group of postmenopausal women. The frequencies of investigated genotypes were in compliance with Hardy-Weinberg equilibrium. The correspondence between evaluated clinical parameters and IL-6 i TNF-α genotypes frequencies has not been proven. Conclusions: The -174G/C polymorphism in the IL-6 and -308G/A polymorphism in TNF-α genes have no influence on bone mineral density value (BMD) in the investigated population of women from Wielkopolska region