Association between systemic calcified atherosclerosis and bone density

ENPP1 in Blood and Bone: Skeletal and Soft Tissue Diseases Induced by ENPP1 Deficiency

The enzyme ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) codes for a type 2 transmembrane glycoprotein that hydrolyzes extracellular ATP to generate pyrophosphate (PPi) and adenosine monophosphate, thereby contributing to downstream purinergic signaling pathways. The clinical phenotypes induced by ENPP1 deficiency are seemingly contradictory and include early-onset osteoporosis in middle-aged adults and life-threatening vascular calcifications in the large arteries of infants with generalized arterial calcification of infancy. The progressive overmineralization of soft tissue and concurrent undermineralization of skeleton also occur in the general medical population, where it is referred to as paradoxical mineralization to highlight the confusing pathophysiology. This review summarizes the clinical presentation and pathophysiology of paradoxical mineralization unveiled by ENPP1 deficiency and the bench-to-bedside development of a novel ENPP1 biologics designed to treat mineralization disorders in the rare disease and general medical population.

Vascular deficits contributing to skeletal fragility in type 1 diabetes

Over 1 million Americans are currently living with T1D and improvements in diabetes management have increased the number of adults with T1D living into later decades of life. This growing population of older adults with diabetes is more susceptible to aging comorbidities, including both vascular disease and osteoporosis. Indeed, adults with T1D have a 2- to 3- fold higher risk of any fracture and up to 7-fold higher risk of hip fracture compared to those without diabetes. Recently, diabetes-related vascular deficits have emerged as potential risks factors for impaired bone blood flow and poor bone health and it has been hypothesized that there is a direct pathophysiologic link between vascular disease and skeletal outcomes in T1D. Indeed, microvascular disease (MVD), one of the most serious consequences of diabetes, has been linked to worse bone microarchitecture in older adults with T1D compared to their counterparts without MVD. The association between the presence of microvascular complications and compromised bone microarchitecture indicates the potential direct deleterious effect of vascular compromise, leading to abnormal skeletal blood flow, altered bone remodeling, and deficits in bone structure. In addition, vascular diabetic complications are characterized by increased vascular calcification, decreased arterial distensibility, and vascular remodeling with increased arterial stiffness and thickness of the vessel walls. These extensive alterations in vascular structure lead to impaired myogenic control and reduced nitric-oxide mediated vasodilation, compromising regulation of blood flow across almost all vascular beds and significantly restricting skeletal muscle blood flow seen in those with T1D. Vascular deficits in T1D may very well extend to bone, compromising skeletal blood flow control, and resulting in reduced blood flow to bone, thus negatively impacting bone health. Indeed, several animal and ex vivo human studies report that diabetes induces microvascular damage within bone are strongly correlated with diabetes disease severity and duration. In this review article, we will discuss the contribution of diabetes-induced vascular deficits to bone density, bone microarchitecture, and bone blood flow regulation, and review the potential contribution of vascular disease to skeletal fragility in T1D.

Sex Differences in Carotid Atherosclerosis: A Systematic Review and Meta-Analysis

BACKGROUND

Over the last decades, several individual studies on sex differences in carotid atherosclerosis have been performed covering a wide range of plaque characteristics and including different populations. This systematic review and meta-analysis aims to summarize previously reported results on sex differences in carotid atherosclerosis and present a roadmap explaining next steps needed for implementing this knowledge in clinical practice.

METHODS

We systematically searched PubMed, Embase, Web of Science, Cochrane Central, and Google Scholar for eligible studies including both male and female participants reporting prevalence of imaging characteristics of carotid atherosclerosis and meta-analyzed these studies. Studies had to report at least the following: (1) calcifications; (2) lipid-rich necrotic core; (3) intraplaque hemorrhage; (4) thin-or-ruptured fibrous cap; (5) plaque ulceration; (6) degree of stenosis; (7) plaque size; or (8) plaque inflammation. We prespecified which imaging modalities had to be used per plaque characteristic and excluded ultrasonography.

RESULTS

We included 42 articles in our meta-analyses (ranging from 2 through 23 articles per plaque characteristic). Men had more frequently a larger plaque compared to women and, moreover, had more often plaques with calcifications (odds ratio=1.57 [95% CI, 1.23-2.02]), lipid-rich necrotic core (odds ratio=1.87 [95% CI, 1.36-2.57]), and intraplaque hemorrhage (odds ratio=2.52 [95% CI, 1.74-3.66]), or an ulcerated plaque (1.81 [95% CI, 1.30-2.51]). Furthermore, we found more pronounced sex differences for lipid-rich necrotic core in symptomatic opposed to asymptomatic participants.

CONCLUSIONS

In this systematic review and meta-analysis, we demonstrate convincing evidence for sex differences in carotid atherosclerosis. All kinds of plaque features-plaque size, composition, and morphology-were more common or larger in men compared to women. Our results highlight that sex is an important variable to include in both study design and clinical-decision making. Further investigation of sex-specific stroke risks with regard to plaque composition is warranted.

Gingival epithelial cell-derived microvesicles activate mineralization in gingival fibroblasts

Soft tissue calcification occurs in many parts of the body, including the gingival tissue. Epithelial cell-derived MVs can control many functions in fibroblasts but their role in regulating mineralization has not been explored. We hypothesized that microvesicles (MVs) derived from gingival epithelial cells could regulate calcification of gingival fibroblast cultures in osteogenic environment. Human gingival fibroblasts (HGFs) were cultured in osteogenic differentiation medium with or without human gingival epithelial cell-derived MV stimulation. Mineralization of the cultures, localization of the MVs and mineral deposits in the HGF cultures were assessed. Gene expression changes associated with MV exposure were analyzed using gene expression profiling and real-time qPCR. Within a week of exposure, epithelial MVs stimulated robust mineralization of HGF cultures that was further enhanced by four weeks. The MVs taken up by the HGF's did not calcify themselves but induced intracellular accumulation of minerals. HGF gene expression profiling after short exposure to MVs demonstrated relative dominance of inflammation-related genes that showed increases in gene expression. In later cultures, OSX, BSP and MMPs were significantly upregulated by the MVs. These results suggest for the first time that epithelial cells maybe associated with the ectopic mineralization process often observed in the soft tissues.

Catalysis-Independent ENPP1 Protein Signaling Regulates Mammalian Bone Mass

Biallelic ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) deficiency induces vascular/soft tissue calcifications in generalized arterial calcification of infancy (GACI), and low bone mass with phosphate-wasting rickets in GACI survivors (autosomal hypophosphatemic rickets type-2). ENPP1 haploinsufficiency induces early-onset osteoporosis and mild phosphate wasting in adults. Both conditions demonstrate the unusual combination of reduced accrual of skeletal mineral, yet excess and progressive heterotopic mineralization. ENPP1 is the only enzyme that generates extracellular pyrophosphate (PPi), a potent inhibitor of both bone and heterotopic mineralization. Life-threatening vascular calcification in ENPP1 deficiency is due to decreased plasma PPi; however, the mechanism by which osteopenia results is not apparent from an understanding of the enzyme's catalytic activity. To probe for catalysis-independent ENPP1 pathways regulating bone, we developed a murine model uncoupling ENPP1 protein signaling from ENPP1 catalysis, Enpp1T238A mice. In contrast to Enpp1asj mice, which lack ENPP1, Enpp1T238A mice have normal trabecular bone microarchitecture and favorable biomechanical properties. However, both models demonstrate low plasma Pi and PPi, increased fibroblast growth factor 23 (FGF23), and by 23 weeks, osteomalacia demonstrating equivalent phosphate wasting in both models. Reflecting findings in whole bone, calvarial cell cultures from Enpp1asj mice demonstrated markedly decreased calcification, elevated transcription of Sfrp1, and decreased nuclear β-catenin signaling compared to wild-type (WT) and Enpp1T238A cultures. Finally, the decreased calcification and nuclear β-catenin signaling observed in Enpp1asj cultures was restored to WT levels by knockout of Sfrp1. Collectively, our findings demonstrate that catalysis-independent ENPP1 signaling pathways regulate bone mass via the expression of soluble Wnt inhibitors such as secreted frizzled-related protein 1 (SFRP1), whereas catalysis dependent pathways regulate phosphate homeostasis through the regulation of plasma FGF23. © 2022 American Society for Bone and Mineral Research (ASBMR).

Association between Bone Mineral Density and Coronary Atherosclerotic Plaque According to Plaque Composition: Registry for the Women Health Cohort for Bone, Breast, and Coronary Artery Disease Study

Background

Although biological links are unclear, low bone density and atherosclerosis are inversely associated. This study evaluated the association between bone mineral density (BMD) and coronary computed tomographic angiography (CCTA) findings, including coronary artery calcification (CAC) score and the presence, extent, and composition of coronary atherosclerotic plaque (CAP) in asymptomatic women.

Methods

A symptomatic women aged ≥40 years (N=2, 100; median age, 52 years; range, 40–80 years) were selected from a retrospective observational cohort and stratified into normal, osteopenia, and osteoporosis groups according to BMD T-score grades. We evaluated CAC score and assessed the presence, extent, and stenosis severity of CAP on CCTA. Additionally, CAP was categorized as calcified, mixed, or non-calcified according to calcified component valiums (>130 Hounsfield units).

Results

Osteopenia and osteoporosis were found in 28.8% and 5.3% of participants, respectively. CAC score and CAC severity significantly increased with decreased BMD grades (from normal to osteoporosis). The presence of CAP (overall, 15.6%; normal, 12.6%; osteopenia, 20.2%; osteoporosis, 28.8%; P<0.001) and number of segments with CAP significantly increased with decreased BMD grades. Furthermore, the number of segments with calcified or mixed plaques, excluding non-calcified plaques, increased with decreased BMD grades. Although most associations were attenuated or disappeared after adjusting for age and other covariates, calcified plaques showed a strong and age-independent association with BMD grades.

Conclusions

The presence and severity of CAC and CAP were significantly associated with BMD severity in asymptomatic women, particularly for the presence of calcified plaques. Further studies are required to determine the association between vascular calcification and bone health status.

Drug discovery of sclerostin inhibitors

Sclerostin, a protein secreted from osteocytes, negatively regulates the WNT signaling pathway by binding to the LRP5/6 co-receptors and further inhibits bone formation and promotes bone resorption. Sclerostin contributes to musculoskeletal system-related diseases, making it a promising therapeutic target for the treatment of WNT-related bone diseases. Additionally, emerging evidence indicates that sclerostin contributes to the development of cancers, obesity, and diabetes, suggesting that it may be a promising therapeutic target for these diseases. Notably, cardiovascular diseases are related to the protective role of sclerostin. In this review, we summarize three distinct types of inhibitors targeting sclerostin, monoclonal antibodies, aptamers, and small-molecule inhibitors, from which monoclonal antibodies have been developed. As the first-in-class sclerostin inhibitor approved by the U.S. FDA, the monoclonal antibody romosozumab has demonstrated excellent effectiveness in the treatment of postmenopausal osteoporosis; however, it conferred high cardiovascular risk in clinical trials. Furthermore, romosozumab could only be administered by injection, which may cause compliance issues for patients who prefer oral therapy. Considering these above safety and compliance concerns, we therefore present relevant discussion and offer perspectives on the development of next-generation sclerostin inhibitors by following several ways, such as concomitant medication, artificial intelligence-based strategy, druggable modification, and bispecific inhibitors strategy.

Associations between bone mineral density and coronary artery calcification: a systematic review and meta-analysis

Background:

The studies about the correlation between bone mineral density (BMD) and coronary arterial calcification (CAC) were still controversial. The aim of this study was to conduct a meta-analysis to evaluate the association between BMD and CAC.

Methods:

We systematically searched PubMed, Embase, Google scholar and Cochrane library for observational studies. We pooled odds ratio (OR) or correlation coefficient, and 95% confidence interval (CI) of the studies. Continuous data were pooled by mean difference (MD). Sub-group analysis was applied to investigate sources of heterogeneity. Funnel plots for publication bias was also performed.

Results:

Seventeen studies met the inclusion criteria. Pooled ORs for the prevalence of CAC in patients with low BMD versus patients with normal BMD was 2.11 (95% CI: 1.11 - 4.02, P = 0.02). The data pooled for comparing CAC score of low BMD and normal BMD patients is 33.77 (95% CI: 23.77 - 43.77, p = 0.000). The pooled ORs of multivariate logistic regression to predict the association were 1.00 (95% CI: 0.92 - 1.10, p = 0.95, age-adjusted), and 0.95 (95% CI: 0.86 - 1.05, p = 0.33, multivariable-adjusted). Cohort category and BMD assessment method were the main sources of heterogeneity.

Conclusions:

Low BMD is associated with higher prevalence and severity of CAC, especially in postmenopausal women. But the relation is not significant after adjusting age and other confounding variables. Low BMD and CAC may be two independent processes with aging. More large-scale studies with high-quality design are still needed to increase the understanding of them.

New Insights to the Crosstalk between Vascular and Bone Tissue in Chronic Kidney Disease-Mineral and Bone Disorder

Vasculature plays a key role in bone development and the maintenance of bone tissue throughout life. The two organ systems are not only linked in normal physiology, but also in pathophysiological conditions. The chronic kidney disease–mineral and bone disorder (CKD-MBD) is still the most serious complication to CKD, resulting in increased morbidity and mortality. Current treatment therapies aimed at the phosphate retention and parathyroid hormone disturbances fail to reduce the high cardiovascular mortality in CKD patients, underlining the importance of other factors in the complex syndrome. This review will focus on vascular disease and its interplay with bone disorders in CKD. It will present the very late data showing a direct effect of vascular calcification on bone metabolism, indicating a vascular-bone tissue crosstalk in CKD. The calcified vasculature not only suffers from the systemic effects of CKD but seems to be an active player in the CKD-MBD syndrome impairing bone metabolism and might be a novel target for treatment and prevention.

The Vessels-Bone Axis: Iliac Artery Calcifications, Vertebral Fractures and Vitamin K from VIKI Study

Vascular calcification and fragility fractures are associated with high morbidity and mortality, especially in end-stage renal disease. We evaluated the relationship of iliac arteries calcifications (IACs) and abdominal aortic calcifications (AACs) with the risk for vertebral fractures (VFs) in hemodialysis patients. The VIKI study was a multicenter cross-sectional study involving 387 hemodialysis patients. The biochemical data included bone health markers, such as vitamin K levels, vitamin K-dependent proteins, vitamin 25(OH)D, alkaline phosphatase, parathormone, calcium, and phosphate. VF, IACs and AACs was determined through standardized spine radiograms. VF was defined as >20% reduction of vertebral body height, and VC were quantified by measuring the length of calcium deposits along the arteries. The prevalence of IACs and AACs were 56.1% and 80.6%, respectively. After adjusting for confounding variables, the presence of IACs was associated with 73% higher odds of VF (p = 0.028), whereas we found no association (p = 0.294) for AACs. IACs were associated with VF irrespective of calcification severity. Patients with IACs had lower levels of vitamin K2 and menaquinone 7 (0.99 vs. 1.15 ng/mL; p = 0.003), and this deficiency became greater with adjustment for triglycerides (0.57 vs. 0.87 ng/mL; p < 0.001). IACs, regardless of their extent, are a clinically relevant risk factor for VFs. The association is enhanced by adjusting for vitamin K, a main player in bone and vascular health. To our knowledge these results are the first in the literature. Prospective studies are needed to confirm these findings both in chronic kidney disease and in the general population.

Chronic Kidney Disease-Induced Vascular Calcification Impairs Bone Metabolism

An association between lower bone mineral density (BMD) and presence of vascular calcification (VC) has been reported in several studies. Chronic kidney disease (CKD) causes detrimental disturbances in the mineral balance, bone turnover, and development of severe VC. Our group has previously demonstrated expression of Wnt inhibitors in calcified arteries of CKD rats. Therefore, we hypothesized that the CKD-induced VC via this pathway signals to bone and induces bone loss. To address this novel hypothesis, we developed a new animal model using isogenic aorta transplantation (ATx). Severely calcified aortas from uremic rats were transplanted into healthy rats (uremic ATx). Transplantation of normal aortas into healthy rats (normal ATx) and age-matched rats (control) served as control groups. Trabecular tissue mineral density, as measured by μCT, was significantly lower in uremic ATx rats compared with both control groups. Uremic ATx rats showed a significant upregulation of the mineralization inhibitors osteopontin and progressive ankylosis protein homolog in bone. In addition, we found significant changes in bone mRNA levels of several genes related to extracellular matrix, bone turnover, and Wnt signaling in uremic ATx rats, with no difference between normal ATx and control. The bone histomorphometry analysis showed significant lower osteoid area in uremic ATx compared with normal ATx along with a trend toward fewer osteoblasts as well as more osteoclasts in the erosion lacunae. Uremic ATx and normal ATx had similar trabecular number and thickness. The bone formation rate did not differ between the three groups. Plasma biochemistry, including sclerostin, kidney, and mineral parameters, were similar between all three groups. ex vivo cultures of aorta from uremic rats showed high secretion of the Wnt inhibitor sclerostin. In conclusion, the presence of VC lowers BMD, impairs bone metabolism, and affects several pathways in bone. The present results prove the existence of a vasculature to bone tissue cross-talk. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Cross-sectional association of bone mineral density with coronary artery calcification in an international multi-ethnic population-based cohort of men aged 40-49: ERA JUMP study

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Significant association of atherosclerosis and bone mineral density has been reported.

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The association has been reported in postmenopausal women and elderly men.

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This study reported the association in an international cohort of middle-aged men.

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Coronary artery calcification was used as a biomarker of coronary atherosclerosis.

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Vertebral bone density was used as a surrogate marker of bone mineral density.

Introduction

Inverse associations of cardiovascular disease (CVD) and atherosclerosis with osteoporosis and bone mineral density (BMD) have been reported in post-menopausal women and elderly men. We aimed to investigate an association between vetebral bone density (VBD) and coronary artery cacification (CAC) in an international multi-ethnic cohort of middle-aged men in the EBCT and Risk Factor Assessment among Japanese and US Men in the Post-World-War-II birth cohort (ERA JUMP).

Methods

ERA JUMP examined 1134 men aged 40–49 (267 white, 84 black, and 242 Japanese Americans, 308 Japanese in Japan, and 233 Koreans in South Korea) free from CVD for CAC, and VBD, biomarkers of coronary atherosclerosis and BMD, respectively, with electron-beam computed tomography, and other risk factors. CAC was quantified with the Agatston method and VBD by computing the mean Hounsfield Unit (HU) value of the T12 to L3 vertebrae. To examine multivariable-adjusted associations of CAC with VBD, we used robust linear and logistic regressions.

Results

The mean VBD and median CAC were 175.4 HU (standard deviation: 36.3) and 0 (interquartile range: (0, 4.5)), respectively. The frequency of CAC was 19.0%. There was no significant interaction by race. VBD had a significant inverse association with CAC score (β = −0.207, p-value = 0.005), while a 10-unit increase in VBD was significantly associated with the frequency of CAC (odds ratio (95% confidence interval) = 0.929 (0.890–0.969)). Both associations remained significant after adjusting for covariates.

Conclusions

VBD had a significant inverse association with CAC in this international multi-ethnic cohort of men aged 40–49.

The relationship between volumetric thoracic bone mineral density and coronary calcification in men and women - results from the Copenhagen General Population Study

BACKGROUND

The association between low bone mineral density (BMD) and the presence of coronary artery calcium (CAC) as a marker of atherosclerosis is unclear. The aim of this study was to assess the potential relationship between volumetric thoracic bone mineral density and coronary calcification in a large population of men and women.

METHODS

Participants from the Copenhagen General Population Study underwent multidetector computed tomography. Volumetric thoracic BMD and CAC were assessed in the same scan. CAC was measured using calibrated mass score (cMS). cMS was dichotomized as cMS = 0 or cMS > 0. The association between BMD and cMS was analyzed using multiple logistic regression in men, premenopausal and postmenopausal women. The model was adjusted for age, BMI, hypertension, hypercholesterolemia, diabetes, known cardiovascular disease and smoking.

RESULTS

Of 2548 eligible participants, 1163 men and 1385 women, mean age 61 ± 10 were included in the study. Mean BMD was 138 ± 46 mg/cm³ for men and 151 ± 49 mg/cm³ women. In 696 men (67%) and 537 women (41%) cMS was found to be above zero. For men, a decrease in BMD of 100 mg/cm³ was associated to an odds ratio of 1.49 for cMS > 0 (95% confidence interval: 1.04-2.13, P = 0.03). In postmenopausal women, a decrease in BMD of 100 mg/cm³ was associated to an odds ratio of 1.47 for MS > 0 (95% confidence interval: 1.04-2.08, P = 0.03). For premenopausal women, no significant association was found between BMD and cMS (odds ratio = 0.74, 95% confidence interval: 0.36-1.52, P = 0.4).

CONCLUSION

Bone mineral density and coronary calcification are inversely related in both men and postmenopausal women, supporting the hypothesis that a direct relation between bone loss and development of atherosclerosis exists irrespective of gender.

The Bone-Vasculature Axis: Calcium Supplementation and the Role of Vitamin K

Calcium supplements are broadly prescribed to treat osteoporosis either as monotherapy or together with vitamin D to enhance calcium absorption. It is still unclear whether calcium supplementation significantly contributes to the reduction of bone fragility and fracture risk. Data suggest that supplementing post-menopausal women with high doses of calcium has a detrimental impact on cardiovascular morbidity and mortality. Chronic kidney disease (CKD) patients are prone to vascular calcification in part due to impaired phosphate excretion. Calcium-based phosphate binders further increase risk of vascular calcification progression. In both bone and vascular tissue, vitamin K-dependent processes play an important role in calcium homeostasis and it is tempting to speculate that vitamin K supplementation might protect from the potentially untoward effects of calcium supplementation. This review provides an update on current literature on calcium supplementation among post-menopausal women and CKD patients and discusses underlying molecular mechanisms of vascular calcification. We propose therapeutic strategies with vitamin K2 treatment to prevent or hold progression of vascular calcification as a consequence of excessive calcium intake.

Metabolic Alterations in Cardiopulmonary Vascular Dysfunction

Cardiovascular diseases (CVD) are the leading cause of death worldwide. CVD comprise a range of diseases affecting the functionality of the heart and blood vessels, including acute myocardial infarction (AMI) and pulmonary hypertension (PH). Despite their different causative mechanisms, both AMI and PH involve narrowed or blocked blood vessels, hypoxia, and tissue infarction. The endothelium plays a pivotal role in the development of CVD. Disruption of the normal homeostasis of endothelia, alterations in the blood vessel structure, and abnormal functionality are essential factors in the onset and progression of both AMI and PH. An emerging theory proposes that pathological blood vessel responses and endothelial dysfunction develop as a result of an abnormal endothelial metabolism. It has been suggested that, in CVD, endothelial cell metabolism switches to higher glycolysis, rather than oxidative phosphorylation, as the main source of ATP, a process designated as the Warburg effect. The evidence of these alterations suggests that understanding endothelial metabolism and mitochondrial function may be central to unveiling fundamental mechanisms underlying cardiovascular pathogenesis and to identifying novel critical metabolic biomarkers and therapeutic targets. Here, we review the role of the endothelium in the regulation of vascular homeostasis and we detail key aspects of endothelial cell metabolism. We also describe recent findings concerning metabolic endothelial cell alterations in acute myocardial infarction and pulmonary hypertension, their relationship with disease pathogenesis and we discuss the future potential of pharmacological modulation of cellular metabolism in the treatment of cardiopulmonary vascular dysfunction. Although targeting endothelial cell metabolism is still in its infancy, it is a promising strategy to restore normal endothelial functions and thus forestall or revert the development of CVD in personalized multi-hit interventions at the metabolic level.

A novel quantitative approach to the measurement of abdominal aortic calcification as applied to the Canadian Multicenter Osteoporosis Study (CaMOS)

BACKGROUND AND AIMS

Lateral spine radiographs provide an inexpensive resource for characterizing abdominal aortic calcification (AAC). A widely accepted measurement of AAC is the semi-quantitative technique generated by the Framingham Heart Study (F-AAC-24). We sought to develop an analytical method to quantify ACC (Q_AAC) on lateral spine radiographs and compare the finding to conventional subjective measurements.

METHODS

Severity of AAC was quantified by measuring pixel intensities in the user-defined region of the aorta with internal standardization to the vertebral endplates and background calibration to the density of the vertebral body. The association between bone mineral density (BMD) measured by dual energy X-ray absorptiometry (DXA) and AAC measured by Q_AAC, F-AAC-24 and a modified Framingham score (F-AAC-12) was determined in 110 participants of the Canadian Multicenter Osteoporosis Study (CaMOS).

RESULTS

The inter-observer reliability for the Q_AAC was slightly higher than with the visual and semi-quantitative Framingham method and the pseudo-colored images illustrate the potential to meaningfully resolve severity of calcification. There was a significant negative association between Q_AAC and BMD measures of the hip and spine. This association remained significant after adjustment for age, sex, estimated glomerular filtration rate, phosphate and hypertension. Significant predictors of F-ACC-12 and 24 included age and hypertension.

CONCLUSIONS

The Q_AAC is a reproducible approach to measuring AAC. Whether it is capable of monitoring subtle calcific changes over time requires further study. This technique could be applied to large studies that seek to determine the impact of interventions that modify bone density as a treatment for vascular calcification and cardiovascular disease in the general population.

Coronary Artery Calcium Score and Bone Metabolism: A Pilot Study in Postmenopausal Women

Background

Since 1991 many studies evaluated the link between cardiovascular diseases and osteoporosis, two age-related conditions, but the main common pathologic pathway has not been determined yet. The histological similarity between arterial calcified plaque and bone matrix and involvement of similar cells and mediators provide a special field of research. Therefore in the present study, we aimed to evaluate the relationship between coronary artery calcium score (CACS) as a surrogate marker of atherosclerosis and bone mediators and parameters in postmenopausal women.

Methods

Eleven postmenopausal women who had CACS higher than 80 were enrolled into the study and underwent bone densitometry. In addition, their serum and urine samples were taken for measuring osteoprotegerin, osteocalcin, and β cross laps. Patients' 10-year probability of fracture was calculated by the World Health Organization fracture-risk assessment tool (FRAX).

Results

The regression analysis of our results showed the association between CACS and OC (std β=0.66, 95% confidence interval [CI] 5.47-72.27, P=0.027), femoral bone density (std β=−0.6, 95% CI -6864.34-14.27, P=0.05) and T-score (std β=−0.6, 95% CI −773.08-1.28, P=0.05) which remained significant after adjustment for age, weight, years since menopause and body mass index. No association was found between CACS and osteoprotegerin, spinal bone density and FRAX score.

Conclusions

In conclusion, this pilot study with small sample size showed the potential association between CACS and osteocalcin, femoral bone density and T-score. However, the relationship between CACS and osteoprotegerin, receptor activator of nuclear factor-kappa B ligand, FRAX score and other bone parameters remain to be clarified in larger sample size studies.

Decreased Bone Mineral Density Is an Independent Predictor for the Development of Atherosclerosis: A Systematic Review and Meta-Analysis

Background

There is conflicting evidence regarding the association between decreased bone mineral density (BMD) and atherosclerosis. To this end, we performed a systematic review and meta-analysis to clarify the association.

Methods

To identify relevant studies, PubMed, Embase, and the Cochrane Library were systematically searched up to November 2015. All observational and comparative studies directly investigating the relationship between decreased BMD and clinical consequences of atherosclerotic vascular abnormalities, including carotid artery calcification (CAC), cardiovascular disease (CAD), and coronary artery disease (CAD) were obtained, without limitation of language or publication year.

Results

A total of 25 studies involving 10,299 patients were included. The incidence of atherosclerotic vascular abnormalities was significantly increased in low BMD patients, compared to patients with normal BMD (OR, 1.81, 95% CI [1.01, 2.19], p<0.00001)). Similar results were also observed for postmenopausal women (OR, 2.23, 95% CI [1.72, 2.89], p<0.00001). Subgroup analyses of osteopenia, osteoporosis, and normal BMD also revealed that the combined ORs for the incidence of atherosclerotic vascular abnormalities increased as BMD decreased. Of note, after adjusting for age, sex, body mass index (BMI) and other vascular risk factors, decreased BMD remained significantly associated with the incidence of atherosclerotic vascular abnormalities (OR, 2.96, 95% CI [2.25, 3.88], p < 0.00001).

Conclusions

Based on the results of this study, decreased BMD is an independent predictor for the development of atherosclerosis in elderly individuals. Moreover, the risk of atherosclerotic vascular abnormalities increased as BMD decreased. Future studies focusing on individuals with different severities of atherosclerosis and comorbidities are of interest.

Relationship between osteopenic syndrome and severity of coronary artery disease detected with coronary angiography and Gensini score in men

Background

Many studies have shown that evidence supporting the relationship between low bone mineral density (BMD) and coronary artery disease (CAD) has been increasing. There is a significant increase of myocardial infarction in men with low BMD.

Purpose

We aimed to detect the relationship between BMD and CAD in patients whose CAD was detected with coronary angiography, and its severity and prevalence was detected with Gensini score.

Methods

A total of 55 patients were selected who were found to have single or multiple infarctions through using coronary angiography in the cardiology clinic. The CAD severity was evaluated by calculating the Gensini score. These patients were divided into two groups: mild CAD and severe CAD groups. Femur bone mineral density (FBMD) was measured with dual energy X-ray absorptiometry. T score values were determined to be normal if the values were >−1.0 (n=22, 40%), and osteopenia–osteoporosis (osteopenic syndrome) if the T score values were ≤−1 (n=33, 60%).

Results

The FBMD of severe CAD according to the Gensini risk score was found to be significantly lower. FBMD values in patients decreased as their Gensini scores increased.

Conclusion

There was a significant relationship between CAD and osteopenic syndrome. FBMD level in men with severe CAD is significantly low when compared with patients who have mild CAD.

The lipid theory in the pathogenesis of calcific aortic stenosis

AIMS

Biologically active phenomena, triggered by atherogenesis and inflammation, lead to aortic valve (AV) calcification. Lipids play an important role in activating the cell signaling leading to AV bone deposition. This review, based on evidence from animal and human studies, mainly focused on the involvement of lipids and atherogenic phenomena in the pathogenesis of calcific aortic stenosis (AS).

DATA SYNTHESIS

The role of elevated low density lipoproteins for the risk of both vascular atherosclerosis and AS has been elucidated. Lipid disorders act synergistically with other risk factors to increase prevalence of calcific AS. Atherosclerosis is also involved in the pathogenesis of bone demineralization, a typical hallmark of aging, which is associated with ectopic calcification at vascular and valvular levels. Animal studies have recently contributed to demonstrate that lipids play an important role in AS pathogenesis through the activation of molecular cell signalings, such as Wnt/Lrp5 and RANK/RANKL/Osteprotegerin, which induce the transition of valvular myofibroblasts toward an osteogenic phenotype with consequent valvular bone deposition. Although all these evidence strongly support the lipid theory in AS pathogenesis, lipids lowering therapies failed to demonstrate in controlled trials a significant efficacy to slow AS progression. Encouraging results from animal studies indicate that physical activity may counteract the biological processes inducing AV degeneration.

CONCLUSIONS

This review indicates a robust interplay between lipids, inflammation, and calcific AS. This new pathophysiological scenario of such an emerging valvular disease paves the way to the next challenge of cardiovascular research: "prevent and care aortic valve stenosis".

Decreased bone mineral density is associated with coronary atherosclerosis in healthy postmenopausal women

Objective

This study aimed to assess the association between bone mineral density (BMD) and coronary atherosclerosis in healthy postmenopausal women.

Methods

We performed a retrospective review of 252 postmenopausal women who had visited a health promotion center for a routine checkup. BMD of the lumbar spine (L1-L4) and femoral neck was evaluated using dual-energy X-ray absorptiometry, and coronary atherosclerosis was assessed using 64-row multidetector computed tomography. Participants were divided into normal BMD and osteopenia-osteoporosis groups, according to the T-scores of their lumbar spine or femoral neck.

Results

Participants with osteopenia-osteoporosis had a significantly higher proportion of coronary atherosclerosis than did those with normal BMD at the lumbar spine (P=0.003) and femoral neck (P=0.004). Osteopenia-osteoporosis at the lumbar spine (odds ratio [OR], 2.86; 95% confidence interval [CI], 1.12 to 7.27) or femoral neck (OR, 3.35; 95% CI, 1.07 to 10.57) was associated with coronary atherosclerosis, after controlling for age and cardiovascular risk factors.

Conclusion

Decreased BMD is associated with coronary atherosclerosis in healthy postmenopausal women, independent of age and cardiovascular risk factors. Postmenopausal women with decreased BMD may have a higher risk of developing coronary atherosclerosis.

Thyroid hormone attenuates vascular calcification induced by vitamin D3 plus nicotine in rats

Thyroid hormones (THs) including thyroxine (T4) and triiodothyronine (T3) play critical roles in bone remodeling. However, the role and mechanism of THs in vascular calcification (VC) have been unclear. To explore the pathophysiological roles of T3 on VC, we investigated the changes in plasma and aortas of THs concentrations and the effect of T3 on rat VC induced by vitamin D3 plus nicotine (VDN). VDN-treated rat showed decreased plasma T3 content, increased vascular calcium deposition, and alkaline phosphatase (ALP) activity. Administration of T3 (0.2 mg/kg body weight IP) for 10 days greatly reduced vascular calcium deposition and ALP activity in calcified rat aortas when compared with controls. Concurrently, the loss of smooth muscle lineage markers α-actin and SM22a was restored, and the increased bone-associated molecules, such as runt-related transcription factor2 (Runx2), Osterix, and osteopontin (OPN) levels in calcified aorta, were reduced by administration of T3. The suppression of klotho in calcified rat aorta was restored by T3. Methimazole (400 mg/L) blocked the beneficial effect of T3 on VC. These results suggested that T3 can inhibit VC development.

Cardiovascular risk factor analysis in patients with a recent clinical fracture at the fracture liaison service

Patients with a low bone mineral density have an increased risk of cardiovascular diseases (CVD) and venous thromboembolic events (VTE). The aim of our retrospective chart review was to investigate the prevalence of CVD, VTE, hypertension (HT), and diabetes mellitus type 2 (DM2) in patients with a recent clinical fracture visiting the Fracture Liaison Service (FLS). Out of 3057 patients aged 50–90 years, 1359 consecutive patients, who agreed and were able to visit the FLS for fracture risk evaluation, were included (71.7% women; mean age 65.2 yrs). Based on medical history, 29.9% had a history of CVD (13.7%), VTE (1.7%), HT (14.9%), and DM2 (7.1%) or a combination. Their prevalence increased with age (21% in patients aged 50–59 years to 48% in patients aged >80 years) and was higher in men than in women (36% versus 27%), but independent of bone mineral density and fracture type. Careful evaluation of medical history with respect to these risk factors should be performed in patients with a recent clinical fracture before starting treatment with medications that increase the risk of VTE or cardiovascular events, such as raloxifene, strontium ranelate, or NSAIDs.

Association of volumetric bone mineral density with abdominal aortic calcification in African ancestry men

SUMMARY

We tested for association between cortical and trabecular volumetric bone mineral density (vBMD) with abdominal aortic calcification (AAC) prevalence in 278 Afro-Caribbean men. AAC was present in 68.3 % of the men. Greater cortical, but not trabecular, vBMD was associated with significantly decreased odds of AAC independent of traditional risk factors.

INTRODUCTION

The aim of this study is to assess the prevalence and correlates of AAC in a sample of 278 Afro-Caribbean men (mean age 56) and to test for a largely unexplored association between cortical and trabecular vBMD with AAC prevalence.

METHODS

Men were recruited consecutively as part of an ongoing prospective cohort study of body composition in men aged 40+. For this analysis, AAC was assessed by computed tomography of the abdomen from L3 to S1. Aortic calcium was scored using the Agatston method, and prevalence was defined as a score ≥10 to rule out false positives. Men also had BMD assessed using peripheral quantitative computed tomography at 4 % (trabecular vBMD) and 33 % (cortical vBMD) of the radius and tibia.

RESULTS

Abdominal aortic calcification was present in 68.3 % of the men. Significant independent predictors of AAC prevalence were increased age, increased BMI, hypertension, and current smoking. Age was the strongest predictor, with each SD (7.8 year) increase in age conferring 2.7 times increased odds of having AAC (P < 0.0001). A one SD greater cortical, but not trabecular, vBMD was associated with a significant decreased odds of AAC prevalence independent of other traditional risk factors (OR 0.65; 95 % CI 0.45-0.92).

CONCLUSIONS

Cortical vBMD is inversely associated with AAC presence. This finding suggests that there may be shared physiology between cortical bone compartment remodeling and vascular calcification.

Associations between bone mineral density and subclinical atherosclerosis: a cross-sectional study of a Chinese population

CONTEXT

The significance of associations between bone mineral density (BMD) and atherosclerosis in the Asian population is less clear.

OBJECTIVE

The aim of this study was to explore the population-level associations between BMD and subclinical atherosclerosis.

DESIGN AND SETTING

This was a community-based cross-sectional study conducted in Shenyang, China.

PARTICIPANTS

A total of 385 Chinese women and men aged 37-87 years were studied.

MAIN OUTCOME MEASURES

The BMD was measured at the total hip and lumbar spine using dual-energy x-ray absorptiometry. The ankle-brachial index (ABI), pulse wave velocity (PWV), and carotid intima-media thickness (CIMT) were measured to assess atherosclerosis. Multiple regression analysis was applied to study the associations. Multicolinearity was examined using the variance inflation factor, condition index, and variance proportions. Factor analysis and principal component regression were used to remove the problem of multicolinearity.

RESULTS

The differences of ABI, PWV, and CIMT among the normal BMD, osteopenia, and osteoporosis groups were not found. Total hip BMD was correlated with ABI in women after adjustment for age (r = 0.156). Sex-specific regression models included adjustment for age, body mass index, cigarette smoking, alcohol consumption, menopausal status (women), systolic blood pressure, diastolic blood pressure, triglycerides, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, fasting blood glucose, serum uric acid, estimated glomerular filtration rate, high-sensitivity C-reactive protein, and fibrinogen. Total hip BMD was associated with ABI in women after adjustment for age (per SD decrease in ABI: -0.130 g/cm(2), P = .022), but the association was borderline significant after full adjustment (P = .045). Total hip BMD and lumbar spine BMD were not associated with ABI, PWV, and CIMT after full adjustment in participants without a fracture history. The risk of osteoporosis was not associated with ABI, PWV, and CIMT.

CONCLUSIONS

Low BMD is not associated with subclinical atherosclerosis as assessed by ABI, PWV, and CIMT.

Bone mineral density is associated with site-specific atherosclerosis in patients with severe peripheral artery disease

Recent studies have highlighted a significant association between the severity of atherosclerosis and bone mineral density (BMD) among healthy subjects, although its connection to angiographically determined peripheral artery disease (PAD) has never been investigated. We evaluated the connection between the angiographic severity and site specificity of peripheral atherosclerosis and osteoporosis among patients with chronic lower limb ischemia. In our cross-sectional study we investigated 172 patients with PAD. The anatomic sites of the lesions were analyzed. The severity of atherosclerosis was diagnosed using the Bollinger angiographic score (BS). BMD was measured at the lumbar spine (l-BMD) and at femoral (f-BMD) and radial (r-BMD) sites by dual-energy X-ray absorptiometry. Dyslipidemia, the level of vitamin D(3), and different bone turnover markers were also noted. Among PAD patients, regardless of the lesion site, we did not find any association between BMD and BS. Among patients with iliac disease, BS was associated with l-BMD (p = 0.038, r = -0.467) and with f-BMD (p = 0.002, r = -0.642). The level of r-BMD among patients with iliac disease was not associated with BS (p = 0.233, r = -0.306). We did not find any difference between the group of patients with and that without dyslipidemia and low or normal levels of vitamin D(3). Our results show a connection between the severity of atherosclerosis and osteoporosis among patients with PAD, specific to the site of the lesion. The findings regarding dyslipidemia, bone markers, and site specificity support the hypothesis that reduced blood flow is the key factor responsible for the inverse association of BMD with atherosclerosis.

Association of abdominal aortic calcification with lifestyle and risk factors of cardiovascular disease

Background

Abdominal aortic calcification (AAC) is a marker of subclinical atherosclerotic disease and an independent predictor of subsequent vascular morbidity and mortality. This study was conducted to investigate the association of AAC with lifestyle and risk factors of cardiovascular disease.

Methods

The results of the abdominal computed tomography of 380 patients who visited Chungnam National University Hospital for a health checkup from January 1, 2008 to December 31, 2009 were reviewed. A six-point scale was used in grading the overall severity of the calcification in three areas of the abdominal aorta, including the area superior to the renal artery, the upper-half area inferior to the renal artery, and the lower-half area inferior to the renal artery, in addition to the common iliac artery. The association of the AAC severity with the age, lifestyle factors, and risk factors of cardiovascular disease was analyzed via multiple linear regression analysis.

Results

In the male subjects, the age, presence of dyslipidemia and smoking were positively related to AAC, but exercising was negatively related to AAC (total R² = 0.563). In the female subjects, the age and presence of diabetes mellitus, hypertension, and dyslipidemia were positively related to AAC, but exercising was negatively related to AAC (total R² = 0.547).

Conclusion

AAC was related to both the male and female subjects' age, presence of dyslipidemia, and exercising, to smoking in the male subjects and to the presence of diabetes mellitus and hypertension in the female subjects.

Association between circulating osteoblast progenitor cells and aortic calcifications in women with postmenopausal osteoporosis

BACKGROUND AND AIMS

Ectopic artery calcification has been documented in women with postmenopausal osteoporosis, in whom an imbalance in the number of circulating osteoprogenitor cells (OPCs) has been identified. Circulating OPCs form calcified nodules in vitro; however, it remains unknown whether an association exists between the number of circulating OPCs and aortic calcifications. We investigated the relationship between OPCs and aortic calcifications in women with postmenopausal osteoporosis.

METHODS AND RESULTS

The number of circulating OPCs was quantified by FACS analysis in 50 osteoporotic postmenopausal women. OPCs were defined as CD15-/alkaline-phosphatase(AP)+ cells coexpressing or not CD34. Participants underwent measurement of markers of bone metabolism, bone mineral density and abdominal aortic calcium (AAC) by 64-slice computed tomography. Patients with AAC were older, had lower 25(OH)vitamin D levels and higher circulating CD15-/AP+/CD34- cells than those without AAC. Significant correlates of AAC included age (rho = 0.38 p = 0.006), calcium (rho = 0.35 p = 0.01), 25(OH)vitamin D (rho = -0.31, p = 0.03) and the number of CD15-/AP+/CD34- cells (rho = 0.55 p < 0.001). In regression analyses, the log-transformed number of CD15-/AP+/CD34- cells was associated with the presence (OR = 6.45, 95% CI 1.03-40.1, p = 0.04) and severity (β = 0.43, p < 0.001) of AAC, independent of age, 25(OH)vitamin D, calcium and other potential confounders. Patients with low 25(OH)vitamin D and high CD15-/AP+/CD34- cells had higher median AAC than other patients (1927/μL, 862-2714/μL vs 147/μL, 0-1665/μL, p = 0.003).

CONCLUSION

In women with postmenopausal osteoporosis, the number of circulating CD15-/AP+/CD34- cells is significantly associated with increased aortic calcifications, that appear to be correlated also with reduced 25(OH)vitamin D levels.

[Prevalence of osteoporosis in patients with severe peripheral artery disease]

INTRODUCTION

Recent studies highlighted a significant association between bone mineral density and atherosclerosis. Cardiovascular disease is the main cause of death in Western countries, while the prevalence of osteoporosis reached 9% in Hungary.

AIM

The aim of this study was to investigate the prevalence of osteoporosis among patients with peripheral vascular disease.

METHODS

In a cross-sectional study bone mineral density using dual-energy X-ray absorptiometry in 172 patients with lower limb ischemia was investigated. According to previous medical history and blood tests, risk factors of atherosclerosis were also assessed and serum markers of bone turnover and other factors that could influence osteoporosis were evaluated.

RESULTS

Prior to bone mineral density screening, osteoporosis was known in 9% of patients. Based on osteodensitometric evaluation, 37% of the patients were diagnosed as having osteopenia and 31% as having osteoporosis. According to risk factors, different patient groups were created. Significantly more female than male patients had osteoporosis, while smoking, age and body mass index failed to affect the prevalence of osteoporosis.

CONCLUSION

These results suggest that patients with severe atherosclerosis need to be regularly screened and, if necessary, treated for osteoporosis.

Targeting of the osteoclastogenic RANKL-RANK axis prevents osteoporotic bone loss and soft tissue calcification in coxsackievirus B3-infected mice

Bone mineralization is a normal physiological process, whereas ectopic calcification of soft tissues is a pathological process that leads to irreversible tissue damage. We have established a coxsackievirus B3 (CVB3)-infected mouse model that manifests both osteoporosis and ectopic calcification specifically in heart, pancreas, and lung. The CVB3-infected mice showed increased serum concentrations of both cytokines including IL-1β, TNF-α, and the receptor activator of NF-κB ligand (RANKL) that stimulate osteoclast formation and of the osteoclast-derived protein tartrate-resistant acid phosphatase 5b. They exhibited more osteoclasts in bone, with no change in the number of osteoblasts, and a decrease in bone formation and the serum concentration of osteoblast-produced osteocalcin. These results indicate that CVB3-induced osteoporosis is likely due to upregulation of osteoclast formation and function, in addition to decreased osteoblast activity. In addition, the serum in the CVB3-infected mice contained a high inorganic phosphate content, which causes ectopic calcification. RANKL treatment induced an increase in the in vitro cardiac fibroblast calcification by inorganic phosphate via the upregulation of osteogenic BMP2, SPARC, Runx2, Fra-1, and NF-κB signaling. We finally observed that i.p. administration of RANK-Fc, a recombinant antagonist of RANKL, prevented bone loss as well as ectopic calcification in CVB3-infected mice. Thus, our results indicate that RANKL may contribute to both abnormal calcium deposition in soft tissues and calcium depletion in bone. In addition, our animal model should provide a tool for the development of new therapeutic agents for calcium disturbance in soft and hard tissues.

Aortic calcification and bone metabolism: the relationship between aortic calcification, BMD, vertebral fracture, 25-hydroxyvitamin D, and osteocalcin

The aim of this study was to investigate the relationship between aortic calcification (AC) and low bone mineral density (BMD), 25(OH)D, C-terminal telopeptide (CTx), and osteocalcin levels in Asian women. We also tried to find the association between AC and the risk of vertebral fracture. We included 769 patients in this study. All patients underwent QCT. Aortic calcium score (ACS) was quantified by the Agatston scoring method. Spinal fracture was defined by lumbar spine radiography. Among 769 subjects, 96 had at least one vertebral fracture and 345 had AC. ACS positively correlated with age. Osteocalcin, CTx, 25(OH)D, total-hip trabecular BMD (tBMD), femoral neck tBMD, and vertebral tBMD were inversely related with ACS. However, cortical BMD (cBMD) did not correlate with ACS. Among these parameters, only osteocalcin significantly correlated with ACS, even after adjusting for age. We divided the subjects into two groups based on the presence of AC to determine the association between AC and vertebral fracture. Multivariate logistic regression analysis showed that age, tBMD of each site, and AC were associated with vertebral fractures. After adjusting for confounding factors, patients with AC had more than a threefold increased risk of vertebral fracture (OR = 3.29-3.57, P < 0.05 according to site). This study suggests that high ACS is related to low tBMD but not cBMD. Furthermore, our findings indicate that this relationship is definitely age-dependent. Finally, we found that AC is significantly associated with the prevalence of vertebral fracture in Asian women.

Serum lipid levels and bone mineral density in Greek postmenopausal women

Contradictory results have been reported regarding a relationship between serum lipid levels and bone mineral density. The purpose of this study was to further investigate a possible relationship between those parameters in Greek postmenopausal women. A total of 591 patients followed at a tertiary hospital were examined for seven different lipid factors in relation to dual-emission X-ray absorptiometry measurements at the lumbar spine. Lipoprotein-a was the only lipid measurement that univariately showed an almost significant trend of association with bone mass category (analysis of variance [ANOVA] p value 0.062 for Ln(Lipoprotein-a)). In multiple regression, it was noted that a non-significant negative trend of association of high density lipoprotein (HDL) cholesterol and Apolipoprotein AI with lumbar T-score (p value 0.058 and 0.075, respectively). In age subgroup analysis, Lipoprotein-a and Ln(Lipoprotein-a) presented a negative correlation with lumbar T-score for women with age ≥ 53 years (p value 0.043 and 0.070, respectively), while a negative correlation of HDL and Apolipoprotein AI levels with lumbar T-score remained in women with age < 53 years (p value 0.039 and 0.052, respectively). The findings do not support a strong relationship between lipid levels and bone mass measurements.

Association between Serum Cholesterol Level and Bone Mineral Density at Lumbar Spine and Femur Neck in Postmenopausal Korean Women

BACKGROUND

Blood lipid profiles have been suggested to be a risk factor for osteoporosis. However, the association between lipid profiles and bone mineral density (BMD) is still unclear. This study aimed to evaluate an association between blood lipid profiles and BMD through both a cross-sectional and a longitudinal study.

METHODS

Study subjects were 958 postmenopausal Korean women who have repeatedly undertaken laboratory tests and BMD measurements at lumbar spine and femur neck with an interval of 7.1 years. The associations between lipid profiles and BMD were examined using Spearman correlation analysis with an adjustment for age, smoking, alcohol drinking, physical activity, body mass index, and follow-up duration.

RESULTS

Lumbar spine BMD was not associated with total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), and high density lipoprotein cholesterol (HLD-C) regardless of when the measurement was performed. In an analysis using data measured at the beginning of the study, femur neck BMD was not associated with TC and LDL-C. However, femur neck BMD showed weak but significantly positive correlation with HDL-C (correlation coefficient, 0.077; 95% confidence interval, 0.005 to 0.149). When the analysis was repeated with data measured at the end of the follow-up, there was no significant correlation between femur neck BMD and any lipid profile. In addition, change in femur neck BMD during follow-up was not associated with the change in lipid profiles.

CONCLUSION

Although further study with a consideration of calcium intake and osteoporosis medication seems necessary, this study found no association between serum lipid profiles and BMD in postmenopausal Korean women.

Association between vascular calcification and osteoporosis in men with type 2 diabetes

Atherosclerotic vascular disease is common in diabetes, and some data support a link with bone loss. This study evaluates the association between osteoporosis and clinical and metabolic factors and chronic complications of diabetes. We studied 59 diabetic men aged 50-80 yr who were assessed with bone densitometry (dual-energy X-ray absorptiometry). Of them, 10.2% of the patients were found to have osteoporosis in the lumbar spine and 45.8% osteopenia, whereas in the femoral neck, 11.8% had osteoporosis and 49% had osteopenia. There was a significant association of osteoporosis in the lumbar spine L1-L4 (p=0.004) and in the femoral neck (p=0.036) with iliac artery calcification. In addition, there was no association with any other metabolic factors, clinical factors, or chronic complications of diabetes evaluated, except for an association between a previous personal history of fractures (p=0.016) and low bone mineral density in the femoral neck. In conclusion, we found a positive association between the iliac artery calcification and osteoporosis in type 2 diabetic male patients.

Mechanisms and clinical consequences of vascular calcification

Vascular calcification has severe clinical consequences and is considered an accurate predictor of future adverse cardiovascular events, including myocardial infarction and stroke. Previously vascular calcification was thought to be a passive process which involved the deposition of calcium and phosphate in arteries and cardiac valves. However, recent studies have shown that vascular calcification is a highly regulated, cell-mediated process similar to bone formation. In this article, we outline the current understanding of key mechanisms governing vascular calcification and highlight the clinical consequences. By understanding better the molecular pathways and genetic circuitry responsible for the pathological mineralization process novel drug targets may be identified and exploited to combat and reduce the detrimental effects of vascular calcification on human health.

Coexistence of osteoporosis (OP) and coronary artery disease (CAD) in the elderly: it is not just a by chance event

Cardiovascular disease (CVD) and OP are common age-related conditions. In both cross-sectional and longitudinal epidemiologic studies, low bone mass has been related to increased frequency of CVD. But available data in geriatric population is limited. In this study we aimed to seek the possible relationship between CAD and low bone mineral density (BMD) in a large number of geriatric patients. A total of 2235 patients aged 65 years or more were included in this cross-sectional study. All patients underwent a complete geriatric assessment and evaluated for CAD and cardiovascular risk factors. BMD was measured by dual-energy X-ray absorptiometry at the lumbar spine (L1-L4) and femoral neck. BMD results were classified into three groups; normal (T-score: ≥-1.0×S.D.), osteopenia (T-score between -1.0 and -2.5×S.D.), and OP (T-score: ≤-2.5×S.D.). CAD was present in 397 (29.7%) of 1335 patients with OP, in 199 (27.4%) of 726 patients with osteopenia and in 34 (19.5%) of 174 patients with normal BMD. Multivariate regression analysis revealed that presence of OP or osteopenia increased the prevalence of CAD as an independent correlate (OR=1.643; 95% CI=1.068-2.528, p=0.030). This study highlights the need for careful evaluation of elderly patients with low BMD for possible CAD.

(Sub)clinical cardiovascular disease is associated with increased bone loss and fracture risk; a systematic review of the association between cardiovascular disease and osteoporosis

Introduction

Both cardiovascular disease and osteoporosis are important causes of morbidity and mortality in the elderly. The co-occurrence of cardiovascular disease and osteoporosis prompted us to review the evidence of an association between cardiovascular (CV) disease and osteoporosis and potential shared common pathophysiological mechanisms.

Methods

A systematic literature search (Medline, Pubmed and Embase) was conducted to identify all clinical studies that investigated the association between cardiovascular disease and osteoporosis. Relevant studies were screened for quality according to guidelines as proposed by the Dutch Cochrane Centre and evidence was summarized.

Results

Seventy studies were included in this review. Due to a large heterogeneity in study population, design and outcome measures a formal meta-analysis was not possible. Six of the highest ranked studies (mean n = 2,000) showed that individuals with prevalent subclinical CV disease had higher risk for increased bone loss and fractures during follow-up compared to persons without CV disease (range of reported risk: hazard ratio (HR) 1.5; odds ratio (OR) 2.3 to 3.0). The largest study (n = 31,936) reported a more than four times higher risk in women and more than six times higher risk in men. There is moderate evidence that individuals with low bone mass had higher CV mortality rates and incident CV events than subjects with normal bone mass (risk rates 1.2 to 1.4). Although the shared common pathophysiological mechanisms are not fully elucidated, the most important factors that might explain this association appear to be, besides age, estrogen deficiency and inflammation.

Conclusions

The current evidence indicates that individuals with prevalent subclinical CV disease are at increased risk for bone loss and subsequent fractures. Presently no firm conclusions can be drawn as to what extent low bone mineral density might be associated with increased cardiovascular risk.

The metabolic syndrome and carotid intima-media thickness in relation to the parathyroid hormone to 25-OH-D(3) ratio in a general population

BACKGROUND

Parathyroid hormone (PTH) and vitamin D interactively regulate calcium fluxes across membranes, and thereby modulate insulin sensitivity, blood pressure, and arterial calcification. We hypothesized that lower calcium intake as reflected by circulating PTH and 25-OH-D₃ might be associated with the metabolic syndrome (MS) and arterial calcification.

METHODS

In a random population sample (n = 542; 50.5% women; mean age, 49.8 ± 13.1 years), we measured MS prevalence (International Diabetes Federation (IDF) and American Heart Association (AHA) criteria), PTH and 25-OH-D₃, serum and 24-h urinary calcium, MS components, carotid intima-media thickness (CIMT), and calcium intake from dairy products. We assessed associations in multivariable-adjusted analyses, using linear and logistic regressions.

RESULTS

The prevalence of MS was 21.0% (IDF criteria) and 23.6% (AHA criteria). MS prevalence, blood pressure, waist circumference, body mass index, fasting blood glucose, insulin and triglycerides, and CIMT increased (P ≤ 0.042) across quartiles of the PTH/25-OH-D₃ ratio, whereas serum and 24-h urinary calcium decreased (P ≤ 0.029). Waist circumference and fasting blood glucose decreased across quartiles of habitual calcium intake (P ≤ 0.04). In models that included MS (IDF) and PTH/25-OH-D₃, the regression coefficients relating CIMT to PTH/25-OH-D₃ ratio and MS were +51 µm (P = 0.013) and +19 µm (P = 0.45), respectively. Multivariable-adjusted analyses were confirmatory.

CONCLUSIONS

MS prevalence and CIMT were positively associated with PTH/25-OH-D₃. CIMT was not associated with MS. Prospective studies and intervention trials should address the causality of these associations.

The skeletal subsystem as an integrative physiology paradigm

Homeostatic bone remodeling depends on precise regulation of osteoblast-osteoclast coupling through intricate endocrine, immune, neuronal, and mechanical factors. The osteoblast-osteoclast model of bone physiology with layers of regulatory complexity can be investigated as a component of a local skeletal subsystem or as a part of a complete whole-body system. In this review, we flip the traditional investigative paradigm of scientific experimentation ("bottom-top research") to a "top-bottom" approach using systems biology. We first establish the intricacies of the two-cell model at the molecular signaling level. We then provide, on a systems level, an integrative physiologic approach involving many recognized organ-level subsystems having direct and/or indirect effects on bone remodeling. Lastly, a hypothetical model of bone remodeling based on frequency and amplitude regulatory mechanisms is presented. It is hoped that by providing a thorough model of skeletal homeostasis, future progress can be made in researching and treating skeletal morbidities.

Ethnic-specific risks for atherosclerotic calcification of the thoracic and abdominal aorta (from the Multi-Ethnic Study of Atherosclerosis)

The aims of this study were to (1) determine the association between ethnicity and thoracic aortic calcium (TAC) and abdominal aortic calcium (AAC) and (2) investigate associations between cardiovascular disease (CVD) risk factors and TAC and AAC. Participants were 1,957 men and women enrolled in the Multi-Ethnic Study of Atherosclerosis who had computed tomographic scans of the chest and abdomen. These scans were obtained at the same clinic visit and calcium scores were computed using the Agatston method. Regression analyses were conducted using relative risk regression. Mean age was 65 years and 50% were women. Forty percent were white, 26% Hispanic, 21% African-American, and 13% Chinese. Whites had the highest prevalence of AAC (80%), which was significantly higher than Hispanics (68%, p <0.001), African-Americans (63%, p <0.001), and Chinese (74%, p = 0.029). Similarly, whites had the highest prevalence of TAC (42%), which was significantly higher than in Hispanics (30%, p <0.01) and African-Americans (27%, p <0.001) but was not significantly different from that in Chinese (38%). Compared to whites and after adjustment for age, gender, body mass index, hypertension, diabetes, dyslipidemia, smoking, and family history of CVD, Hispanics and African-Americans, but not Chinese-Americans, had a significantly lower risk for the presence of any AAC or any TAC. In these models, diabetes, smoking, and dyslipidemia had stronger associations with AAC, whereas hypertension was stronger for TAC. In conclusion, compared to whites, African-Americans and Hispanics, but not Chinese, have evidence of less atherosclerosis in the thoracic and abdominal aortas, which does not appear to be accounted for by traditional CVD risk factors.

Vascular calcification and bone disease: the calcification paradox

Vascular calcification or ectopic mineralization in blood vessels is an active, cell-regulated process, increasingly recognized as a general cardiovascular risk factor. Remarkably, ectopic artery mineralization is frequently accompanied by decreased bone mineral density or disturbed bone turnover. This contradictory association, observed mainly in osteoporosis and chronic kidney disease, is called the 'calcification paradox'. Here, we review recent advances in our understanding of the calcification paradox, including protein expression patterns governing both normal and ectopic mineralization, the conversion of vascular smooth muscle cells to bone-like cells, and the regulatory pathways involved in both bone and vessel mineralization. Further elucidation of the mechanisms underlying the calcification paradox is crucial in order to develop preventive and therapeutic strategies to deal with vascular calcification and reduce the associated cardiovascular risk.

Association of reduction in bone mineral density with mortality in male hemodialysis patients

In the present study we examined the relationship of bone mineral density (BMD) reduction with increased mortality in hemodialysis patients. A single-center prospective observational study was conducted on 269 male hemodialysis patients. The BMD in the distal third of the radius (DR1/3) and in the ultradistal radius (UR), which are enriched with cortical and cancellous bone, respectively, was measured twice using dual-energy X-ray absorptiometry (DXA) with a 1-year interval. Subjects were divided into two groups based on the presence or absence of BMD reduction. Survival was followed for 61.0 months, after which time 104 patients (39%) had died. A significant BMD reduction at the UR and DR1/3 occurred in 182 (68%) and 195 (72%) patients, respectively. Patients with BMD reduction in the UR, in contrast to the DR1/3, had a significantly lower survival rate than those without BMD reduction (P = 0.01). In Cox regression analysis, the rate of BMD change at the UR, in addition to patient age, diabetes mellitus, and serum albumin, emerged as an independent predictor for increased mortality (HR = 0.970, 95% CI 0.945-0.996). Our results suggest that BMD reduction at the UR might be a clinically relevant marker that predicts an increased risk of mortality in male hemodialysis patients.

Atherosclerosis and osteoporosis: age-dependent degenerative processes or related entities?

Osteoporosis and atherosclerosis, two multifactorial and degenerative entities, are major public health problems. These diseases accompany the aging process and share common risk factors. Furthermore, several common pathophysiological factors have been suggested. These include similar molecular pathways involving bone and vascular mineralization, estrogen deficiency, parathyroid hormone, homocysteine, lipid oxidation products, inflammatory process, as well as vitamin D and K. Moreover, the use of statins, biphosphonates, beta-blockers and experimental dual-purpose therapies based on the biological linkage of the above entities may simultaneously benefit bone loss and vascular disease. This review considers a potential link between osteoporosis and atherosclerosis beyond aging. These common factors may lead to appropriate treatment strategies.