Management of post-menopausal osteoporosis: something new on the horizon?

Genetic predictors of skeletal outcomes in healthy fertile women: the Bonturno study

Skeletal traits as height (Ht) or bone mineral density (BMD) are strongly inherited. Low-density lipoprotein receptor-related protein 5 (LRP5) and farnesyl diphosphonate synthase (FDPS) are candidate genes for bone phenotypes. From Bonturno study, we genotyped 570 healthy Caucasian women aged 20 to 50 years (yrs) for LRP5 rs4988321 (A/G) and rs3736228 (C/T) and FDPS rs2297480 (A/C) single nucleotide polymorphisms. Serum C-telopeptide of type I collagen (CTX), osteocalcin (OC), and N-terminal propeptide of type I procollagen (P1NP) were measured in BMD-evaluated subjects at lumbar spine (LS), total hip (TH) and femoral neck (FN) sites. LRP5 rs4988321 locus correlated with FN-BMD (P = 0.0230), while LRP5 rs3736228 genotypes differed in LS-BMD (P = 0.0428). When clustered by age, lower FN-BMD was detected in LRP5 GG (P = 0.030) subjects of 41 to 50 years but not in younger. Both LRP5 GG and CC genotypes showed higher age-adjusted values of OC, CTX and P1NP. Increased CTX values were in LRP5 GGCC subjects than in those having at least one LRP5 A plus T alleles (P = 0.0190). LRP5 CC, GG or GGCC subjects with at least one FDPS C allele showed higher levels of CTX and OC in 31 to 40 yrs or older subjects. In conclusion, LRP5 and FDPS loci age-specifically affect skeletal traits in healthy fertile women.

A newly developed snack effective for enhancing bone volume

BACKGROUND

The incidence of primary osteoporosis is higher in Japan than in USA and European countries. Recently, the importance of preventive medicine has been gradually recognized in the field of orthopaedic surgery with a concept that peak bone mass should be increased in childhood as much as possible for the prevention of osteoporosis. Under such background, we have developed a new bean snack with an aim to improve bone volume loss. In this study, we examined the effects of a newly developed snack on bone volume and density in osteoporosis model mice.

METHODS

Orchiectomy (ORX) and ovariectomy (OVX) were performed for C57BL/6J mice of twelve-week-old (Jackson Laboratory, Bar Harbar, ME, USA) were used in this experiment. We prepared and given three types of powder diet e.g.: normal calcium diet (NCD, Ca: 0.9%, Clea Japan Co., Tokyo, Japan), low calcium diet (LCD, Ca: 0.63%, Clea Japan Co.,) and special diet (SCD, Ca: 0.9%). Eighteen weeks after surgery, all the animals were sacrified and prepared for histomorphometric analysis to quantify bone density and bone mineral content.

RESULTS

As a result of histomorphometric examination, SCD was revealed to enhance bone volume irrespective of age and sex. The bone density was increased significantly in osteoporosis model mice fed the newly developmental snack as compared with the control mice. The bone mineral content was also enhanced significantly. These phenomena were revealed in both sexes.

CONCLUSION

It is shown that the newly developed bean snack is highly effective for the improvement of bone volume loss irrespective of sex. We demonstrated that newly developmental snack supplements may be a useful preventive measure for Japanese whose bone mineral density values are less than the ideal condition.

Age-specific effects of estrogen receptors' polymorphisms on the bone traits in healthy fertile women: the BONTURNO study

BACKGROUND

Skeletal characteristics such as height (Ht), bone mineral density (BMD) or bone turnover markers are strongly inherited. Common variants in the genes encoding for estrogen receptor alpha (ESR1) and beta (ESR2) are proposed as candidates for influencing bone phenotypes at the population level.

METHODS

We studied 641 healthy premenopausal women aged 20-50 years (yrs) participating into the BONTURNO study. Exclusion criteria were irregular cyclic menses, low trauma fracture, metabolic bone or chronic diseases. Serum C-telopeptide of type I collagen (CTX), osteocalcin (OC), and N-terminal propeptide of type I procollagen (P1NP) were measured in all enrolled subjects, who underwent to lumbar spine (LS), total hip (TH) and femoral neck (FN) BMD evaluation by DXA. Five hundred seventy Caucasian women were genotyped for ESR1 rs2234693 and rs9340799 and ESR2 rs4986938 polymorphisms.

RESULTS

Although no genotype differences were found in body parameters, subjects with combined ESR1 CCGG plus ESR2 AA-AG genotype were taller than those with opposite genotype (P = 0.044). Moreover, ESR1 rs2234693 genotypes correlated with family history of osteoporosis (FHO) and hip fracture (FHF) (P < 0.01), while ESR2 AA-AC genotypes were strongly associated with FHF (OR 2.387, 95% CI 1.432-3.977; P < 0.001).When clustered by age, 20-30 yrs old subjects, having at least one ESR1 rs2234693 C allele presented lower LS- (P = 0.008) and TH-BMD (P = 0.047) than TT genotypes. In 41-50 yrs age, lower FN-BMD was associated with ESR2 AA (P = 0.0180) subjects than in those with the opposite genotype. ESR1 rs2234693 and rs9340799 and ESR2 rs4986938 polymorphisms did not correlate with age-adjusted values of OC, CTX and P1NP.

CONCLUSION

These findings support the presence of age-specific effects of ESR1 and ESR2 polymorphisms on various skeletal traits in healthy fertile women.

Pharmacogenetics of bone treatments: the VDR and ERalpha gene story

Osteoporosis is a common skeletal disease with a strong genetic component characterized by reduced bone mass and increased risk of fragility fractures. Although osteoporosis is a worldwide problem, there are many differences in human ethnics regarding both disease morbidity and drug treatment efficacy. Polymorphisms of vitamin D receptor (VDR) and estrogen receptor-alpha (ERalpha) loci are proposed as genetic determinants of bone quality, skeletal geometry and bone turnover markers. Furthermore, varying responsiveness to vitamin D and estrogen-based treatments may reflect allele variation in their signaling pathway genes (e.g., VDR or ERalpha). Because of their specific ethnic distribution, VDR and ERalpha polymorphisms may be involved in reported human differences of osteoporosis treatment responses.