Associated response in bone and lipids during hormone replacement therapy

High Cholesterol Deteriorates Bone Health: New Insights into Molecular Mechanisms

Many epidemiological studies show a positive connection between cardiovascular diseases and risk of osteoporosis, suggesting a role of hyperlipidemia and/or hypercholesterolemia in regulating osteoporosis. The majority of the studies indicated a correlation between high cholesterol and high LDL-cholesterol level with low bone mineral density, a strong predictor of osteoporosis. Similarly, bone metastasis is a serious complication of cancer for patients. Several epidemiological and basic studies have established that high cholesterol is associated with increased cancer risk. Moreover, osteoporotic bone environment predisposes the cancer cells for metastatic growth in the bone microenvironment. This review focuses on how cholesterol and cholesterol-lowering drugs (statins) regulate the functions of bone residential osteoblast and osteoclast cells to augment or to prevent bone deterioration. Moreover, this study provides an insight into molecular mechanisms of cholesterol-mediated bone deterioration. It also proposes a potential mechanism by which cellular cholesterol boosts cancer-induced bone metastasis.

Association of serum paraoxonase concentration with serum lipid levels and bone mineral density measurements in early postmenopausal women

OBJECTIVE

To determine the association of serum paraoxonase concentration with serum lipid levels and bone mineral density in early postmenopausal Turkish women.

DESIGN

One hundred healthy postmenopausal women were included in a cross-sectional study in a University hospital clinic. Blood was drawn from women who had bone mineral density (BMD) measurements during routine visits. BMD of the lumbar vertebrae was measured by dual-energy X-ray absorptiometry. The serum paraoxonase concentration and serum lipid levels were measured. Women were divided into two groups: those with normal lumbar vertebrae BMD and those with osteopenic lumbar vertebrae. Serum paraoxonase concentration was compared between the groups. The correlation between serum paraoxonase concentration and bone mass parameters was performed using Pearson's test.

RESULTS

The paraoxonase concentration in the osteopenic group was significantly lower than in the group with normal lumbar vertebrae BMD. The paraoxonase concentration was moderately correlated with total cholesterol, low density lipoprotein cholesterol and triglyceride levels among early postmenopausal Turkish women.

CONCLUSIONS

Early postmenopausal women with osteopenic lumbar vertebrae have significantly lower paraoxonase concentration than those with normal lumbar vertebrae BMD. Further studies are needed to clarify the associations between the osteoporosis risk factors and paraoxonase concentration during late postmenopausal years.

Clinical Efficacy of EH0202, a Kampo Formula, on the Health of Middle-Aged Women

To investigate the clinical effects of EH0202, a Japanese herbal supplement, on the menopausal symptoms and physical status of peri- and post-menopausal women. Thirty-two post-menopausal women (53.0±5.1 years) presented with menopausal complaints were enrolled in the clinical study. Patients were administered an herbal supplement, EH0202 (6 g/day for 6 months), and were assessed for improvement of their overall symptoms using the Greene Climacteric Scale and the Visual Analog Scale (VAS). Blood pressure, skin surface blood flow and plasma lipid profiles were measured before and 1, 3 and 6 months after EH0202 administration. There was a significant decrease in the climacteric scale score (P<0.001) and VAS (P<0.0001) after 6 months of EH0202 treatment. There was a significant decrease in systolic (P<0.001) and diastolic (P<0.05) blood pressure, and a significant decrease in facial skin surface blood flow (P<0.05) after 3 months of EH0202 administration. We observed a significant decrease in plasma TG and LDL-cholesterol concentrations after 3 months of EH0202 administration (P<0.05). EH0202 (MACH) reduced blood pressure, excess facial skin blood flow (flushing) and abnormal lipid levels, as well as clinically improved menopausal symptoms in post-menopausal women. In post-menopausal women, this product appears to help maintain normal biological function and improves quality of life.

Relationship between single nucleotide polymorphisms in CYP1A1 and CYP1B1 genes and the bone mineral density and serum lipid profiles in postmenopausal Japanese women taking hormone therapy

OBJECTIVE

The genetic variations of the genes encoding cytochrome P-450 enzymes are considered to play an important role in the metabolism of estradiol. The objective of this study was to evaluate the relationships among single nucleotide polymorphisms (SNPs) of cytochrome P-450 genes, lumbar bone mineral density (BMD), and serum lipids and to determine the effects of hormone therapy (HT).

DESIGN

The participants were 124 Japanese women who had been diagnosed with osteopenia or osteoporosis and were taking HT for 12 months. Seven single nucleotide polymorphisms in the CYP1A1 and CYP1B1 genes were characterized. Lumbar BMD and the levels of serum lipids were measured before and after HT.

RESULTS

A single nucleotide polymorphism in exon 3 of CYP1B1 was found to be significantly associated with the effect of HT on BMD and low-density lipoprotein cholesterol both in univariate and multivariate analyses. In the women with the GG genotype of L432V, the responses to HT of BMD and low-density lipoprotein cholesterol markedly decreased. The serum follicle-stimulating hormone level after HT was significantly higher in the women with the GG genotype of L432V.

CONCLUSIONS

These results suggest that the L432V polymorphism in the CYP1B1 gene could therefore be used to predict the effect of HT on lumbar BMD and low-density lipoprotein cholesterol in Japanese women.

Association between serum cholesterol and bone mineral density

BACKGROUND

Hypercholesterolaemia has been associated with low bone mineral density (BMD) in some but not all studies.

OBJECTIVES

To examine the influence of age, menopausal status and hormone replacement therapy (HRT) on the relationship between serum cholesterol and BMD in women.

PATIENTS AND MEASUREMENTS

497 female participants (age range 20-81) comprising 224 premenopausal and 273 postmenopausal women (156 on HRT and 117 no HRT) underwent measurements of bone mineral density (BMD) and serum lipid profile.

RESULTS

Total serum cholesterol (TC) and low density lipoprotein (LDL) levels were higher and lumbar spine BMD was lower in postmenopausal women not taking HRT compared to those taking HRT. TC and LDL were negatively associated with BMD at all measured sites among postmenopausal women not taking HRT in univariate regression analysis (all p<0.05). High density lipoprotein (HDL) had inverse relationships with BMD at all sites in pre-menopausal women and those who were exposed to HRT (p<0.05). In fully adjusted regression models the relationships between TC and BMD remained significant at the lumbar spine and whole body (p<0.05) and between LDL and lumbar spine BMD only (p<0.05). For subjects in the other groups, no significant associations between TC or LDL and BMD were found. Significant interactions between total cholesterol and LDL levels with HRT were detected among post-menopausal women in the regression analyses (all p<0.05). No such interactions were found between HDL levels and HRT.

CONCLUSION

There is a modest inverse relationship between lumbar spine and whole body BMD and serum TC and LDL levels and in post-menopausal women and HDL in pre-menopausal women. HRT use appears to modify these relationships. The mechanisms of this relationship require further study.

Paraoxonase-1 activity as a marker of atherosclerosis is not associated with low bone mineral density in healthy postmenopausal women

The aging process is associated with an increasing prevalence of osteoporosis and atherosclerosis, but it is uncertain if these two conditions are interrelated. Serum paraoxonase-1 (PON1) is a high-density lipoprotein (HDL) associated enzyme that has been implicated in the pathogenesis of atherosclerosis. Our aims of the study were to investigate (1) serum paraoxonase and arylesterase activities and, lipid hydroperoxide (LOOH) levels in healthy postmenopausal women and (2) whether there were any associations between these enzyme activities and bone mineral density (BMD). A total of 97 generally healthy postmenopausal women were enrolled in the study. BMD was measured at lumbar spine (LS) and femoral neck (FN) with dual energy X-ray absorptiometry. Serum paraoxonase and arylesterase activities were measured spectrophotometrically. LOOH levels were measured by iodometric assay. In this population, 50 (51%) women had BMD T scores < -2.5 at the LS and/or FN defined as osteoporosis and 47 (49%) of them had normal BMDs. Serum paraoxonase, arylesterase, and LOOH activities were not significantly different between osteoporotic and nonosteoporotic postmenopausal women. There were also no correlations between paraoxonase, arylesterase, LOOH activities, and LS BMD and FN BMD. We conclude that there may be not good evidence to support a direct relationship between osteoporosis and atherosclerosis in these subjects. However, prospective studies with larger groups are needed to investigate this issue further.

Estrogen receptor alpha and beta polymorphisms: is there an association with bone mineral density, plasma lipids, and response to postmenopausal hormone therapy?

OBJECTIVE AND DESIGN

A cross-sectional segregation analysis of polymorphisms in the estrogen receptor (ER) genes (Pvull and Xbal in ERalpha, and Alul in ERAbeta with bone mineral density in the lumbar spine and forearm and with lipid profile was performed in 1098 postmenopausal women. Additionally, in a subpopulation of 280 women, who completed 1 year of treatment with estrogen plus progestin, the association between genotypes and the response to treatment in both plasma lipids and bone was investigated. In another untreated subpopulation of 443 women, genotype influence on the prevalence of vertebral fractures and on annual rate of bone loss during a mean follow-up period of 11 years was estimated.

RESULTS

Baseline plasma lipids, bone mineral density, annual rate of bone loss and prevalence of spinal fractures were not significantly associated with polymorphisms in the ERbeta gene. The ERA polymorphism was significantly associated with bone loss from the distal forearm (P = 0.04) but not with bone loss from the spine. After 1 year of treatment with hormone therapy there was also a significant association between the ERbeta polymorphism and the response in total cholesterol (P = 0.02); while the ERalpha gene polymorphisms did not significantly influence the response to hormone therapy.

CONCLUSIONS

In a large white population of postmenopausal women, ERalpha gene polymorphisms were not associated with bone mineral density or lipid profile at baseline or after hormone therapy. Conversely, the ERbeta genotype appeared to segregate with bone loss from the forearm and to modulate the decrease in total cholesterol during hormone therapy.