Localization of osteoprotegerin, tumor necrosis factor-related apoptosis-inducing ligand, and receptor activator of nuclear factor-kappaB ligand in Mönckeberg's sclerosis and atherosclerosis

The effects of vitamin D on different types of cells

Vitamin D is neccessary for regulation of calcium and phosphorus metabolism in bones, affects imunity, the cardiovascular system, muscles, skin, epithelium, extracellular matrix, the central nervous system, and plays arole in prevention of aging-associated diseases. Vitamin D receptor is expressed in almost all types of cells and its activation leads to modulation of different signaling pathways. In this review, we have analysed the current knowledge of 1,25-dihydroxyvitamin D3 or 25-hydroxyvitamin D3 effects on metabolism of cells important for the function of the cardiovascular system (endothelial cells, vascular smooth muscle cells, cardiac cells and pericytes), tissue healing (fibroblasts), epithelium (various types of epithelial cells) and the central nervous system (neurons, astrocytes and microglia). The goal of this review was to compare the effects of vitamin D on the above mentioned cells in in vitro conditions and to summarize what is known in this field of research.

Cardiovascular benefits and risks associated with calcium, vitamin D, and antiresorptive therapy in the management of skeletal fragility

Osteoporosis affects one in every five women over the age of 50 worldwide. With a rapidly ageing population, the prevalence of fragility fractures, considered a largely preventable consequence of osteoporosis, is expected to increase. Age is also a major risk for cardiovascular disease and mortality, thus highlighting the importance of cardiovascular profiling of osteoporosis interventions. Although calcium and vitamin D are essential for a healthy bone metabolism, excessive supplementation may be associated with increased risk. Conversely, early pre-clinical data have suggested a possible cardiovascular benefit from bisphosphonate therapy. This review evaluates the evidence behind the cardiovascular benefits and risks that may be associated with osteoporosis therapy.

Associations between bone mineral density and subclinical peripheral arterial disease in elderly men with type 2 diabetes mellitus

The association between peripheral arterial disease (PAD) and osteoporosis in elderly men with type 2 diabetes mellitus (T2DM) remains unclear. We demonstrated the association between subclinical PAD and decreased total hip bone mineral density (BMD) in men aged ≥ 55 years with T2DM, providing clinical clues for the early detection of decreased bone density in total hip.

PURPOSE

To investigate the association between subclinical peripheral arterial disease (PAD) and bone mineral density (BMD) at total hip, femoral neck, and lumbar spine (L_1-4) in elderly men with type 2 diabetes mellitus (T2DM).

METHODS

We identified 2,466 patients with confirmed diabetes in this retrospective cross-sectional study. A total of 272 men aged ≥ 55 years with T2DM (50 with subclinical PAD and 222 without PAD) were analyzed. Partial correlation analysis was conducted to explore the associations between ankle-brachial index (ABI) and BMD. Multivariate logistic regression analysis was performed to analyze the contributor for low bone density (T-score <  - 1.0).

RESULTS

Patients with T2DM and subclinical PAD (ABI ≤ 0.9) had significantly lower total hip BMD and T-score (BMD, 0.87 ± 0.14 vs. 0.92 ± 0.15 g/cm², P = 0.014; T-score, -1.30 [-1.70 to -0.45] vs. -0.80 [-1.40 to 0.00], P = 0.009) than those in the control group. The partial correlation analyses indicated that ABI significantly correlated with the total hip T-score (adjusted r = 0.166, P = 0.009). The logistic regression analysis indicated that subclinical PAD was an independent risk factor for the risk of decreased bone density in total hip (adjusted odds ratio [95% CI]: 8.933 [1.075-74.222], P = 0.043).  CONCLUSION: Subclinical PAD (ABI ≤ 0.9) could be used as a risk factor for decreased total hip BMD in men aged ≥ 55 years with T2DM, which provides clinical clues for the early detection of low bone density in total hip in such populations.

The Charcot Foot Reflects a Response to Injury That Is Critically Distorted by Preexisting Nerve Damage: An Imperfect Storm

It has been recognized since comprehensive descriptions by Jean-Martin Charcot in 1868 and 1883 that development of what is usually known as neuropathic osteoarthropathy (or the Charcot foot) requires the coincidence of neuropathy and inflammation. Despite this, detailed understanding of the causes has remained remarkably limited in the succeeding century and a half. The aim of this descriptive account is to draw particular attention to the processes involved in both the onset and resolution of the inflammation that is an essential component of active disease. The principal observation is that while neuropathy is common in people with diabetes, the inflammation and secondary skeletal damage that characterize neuropathic osteoarthropathy are observed in only a small minority of people with diabetes and with neuropathy. We therefore argue that the key to understanding the causes of the Charcot foot is to focus equally on those who have active disease as well as those who do not. Although neuropathy is essential for development of the disorder, neuropathy also has an adverse impact on the mechanisms involved in the onset of inflammation, and these may be critically affected in the majority of those who are susceptible. The Charcot foot is uncommon in people with diabetes (or any other cause of neuropathy) because the large majority of those with neuropathy may have also lost the capacity to mount the specific inflammatory reaction that is essential for its development.

Novel Biomarkers Detected by Proteomics Predict Death and Cardiovascular Events in Hemodialysis Patients

End-stage kidney disease increases mortality and the risk of cardiovascular (CV) disease. It is crucial to explore novel biomarkers to predict CV disease in the complex setting of patients receiving hemodialysis (HD). This study investigated the association between 92 targeted proteins with all-cause death, CV death, and composite vascular events (CVEs) in HD patients. From December 2010 to March 2011, 331 HD patients were included and followed prospectively for 5 years. Serum was analyzed for 92 CV-related proteins using Proseek Multiplex Cardiovascular I panel, a high-sensitivity assay based on proximity extension assay (PEA) technology. The association between biomarkers and all-cause death, CV death, and CVEs was evaluated using Cox-regression analyses. Of the PEA-based proteins, we identified 20 proteins associated with risk of all-cause death, 7 proteins associated with risk of CV death, and 17 proteins associated with risk of CVEs, independent of established risk factors. Interleukin-8 (IL-8), T-cell immunoglobulin and mucin domain 1 (TIM-1), and C-C motif chemokine 20 (CCL20) were associated with increased risk of all-cause death, CV death, and CVE in multivariable-adjusted models. Stem cell factor (SCF) and Galanin peptides (GAL) were associated with both decreased risk of all-cause death and CV death. In conclusion, IL-8, TIM-1, and CCL20 predicted death and CV outcomes in HD patients. Novel findings were that SCF and GAL were associated with a lower risk of all-cause death and CV death. The SCF warrants further study with regard to its possible biological effect in HD patients.

Narrative review of the systemic inflammatory reaction to cardiac surgery and cardiopulmonary bypass

Background

Data from large cardiac surgery registries have been depicting a downward trend of mortality and morbidities in the last 20 years. However, despite decades of medical evolution, cardiac surgery and cardiopulmonary bypass still provoke a systemic inflammatory response, which occasionally leads to worsened outcome. This article seeks to outline the mechanism of the phenomenon.

Methods

A thorough review of the literature has been performed. Criteria for considering studies for this non‐systematic review were as follows: observational and interventional studies investigating the systemic inflammatory response to cardiac surgery, experimental studies describing relevant molecular mechanisms, and essential review studies pertinent to the topic.

Results

The intrinsic variability of the inflammatory response to cardiac surgery, together with its heterogenous perception among clinicians, as well as the arduousness to early discriminate high‐responder patients from those who will not develop a clinically relevant reaction, concurred to hitherto unconclusive randomized controlled trials. Furthermore, peremptory knowledge about the pathophysiology of maladaptive inflammation following heart surgery is still lacking.

Conclusions

Systemic inflammation following cardiac surgery is a frequent entity that occasionally becomes clinically relevant. Specific genomic differences, age, and other preoperative factors influence the magnitude of the response, which elements display extreme redundancy and pleiotropism that the target of a single pathway cannot represent a silver bullet.

Osteoclast-Mediated Cell Therapy as an Attempt to Treat Elastin Specific Vascular Calcification

Inflammation and stiffness in the arteries is referred to as vascular calcification. This process is a prevalent yet poorly understood consequence of cardiovascular disease and diabetes mellitus, comorbidities with few treatments clinically available. Because this is an active process similar to bone formation, it is hypothesized that osteoclasts (OCs), bone-resorbing cells in the body, could potentially work to reverse existing calcification by resorbing bone material. The receptor activator of nuclear kappa B-ligand (RANKL) is a molecule responsible for triggering a response in monocytes and macrophages that allows them to differentiate into functional OCs. In this study, OC and RANKL delivery were employed to determine whether calcification could be attenuated. OCs were either delivered via direct injection, collagen/alginate microbeads, or collagen gel application, while RANKL was delivered via injection, through either a porcine subdermal model or aortic injury model. While in vitro results yielded a decrease in calcification using OC therapy, in vivo delivery mechanisms did not provide control or regulation to keep cells localized long enough to induce calcification reduction. However, these results do provide context and direction for the future of OC therapy, revealing necessary steps for this treatment to effectively reduce calcification in vivo. The discrepancy between in vivo and in vitro success for OC therapy points to the need for a more stable and time-controlled delivery mechanism that will allow OCs not only to remain at the site of calcification, but also to be regulated so that they are healthy and functioning normally when introduced to diseased tissue.

Osteoprotegerin predicts cardiovascular events in patients treated with hemodialysis

BACKGROUND

Disturbances in bone mineral metabolism are associated with increased mortality and cardiovascular events (CVEs). However, the association between bone-associated protein biomarkers, mortality, and CVEs independent of cytokine activation remains unknown. This study aimed to investigate bone-associated protein biomarkers, and the association with inflammatory cytokines, and cardiovascular outcomes.

METHODS

This prospective study enrolled hemodialysis (HD) patients in Denmark between December 2010 and March 2011. Using a proximity extension proteomics assay, nine bone-associated proteins were examined: cathepsin D (CTSD), cathepsin L1 (CTSL1), dickkopf-related protein 1 (Dkk-1), fibroblast growth factor 23 (FGF-23), leptin, osteoprotegerin (OPG), receptor activator of nuclear factor kappa-Β ligand (RANKL), TNF-related apoptosis-inducing ligand (TRAIL), and TNF-related apoptosis-inducing ligand receptor 2 (TRAIL-R2). The importance of the bone-associated protein markers was evaluated by a random forest algorithm (RF). The association between bone-associated proteins with all-cause death, cardiovascular death, and CVEs was analyzed in multivariable Cox models adjusted for age, gender, comorbidities, laboratory data, and dialysis duration.

RESULTS

We enrolled 331 patients (63.7% men; mean [SD] age, 65 [14.6] years) in a prospective cohort study with five years follow-up. When adjusting for confounders, CTSL1 remained associated with all-cause death, and four biomarkers were associated with CVE. However, the association between bone markers and the outcomes was attenuated after adjusting for inflammatory proteins, and just OPG remained associated with CVE in the adjusted model. Evaluating the importance of bone markers by RF, OPG was the most important marker related to CVEs. OPG also improved the prediction of CVE when added clinical information alone in integrated discrimination improvement and net reclassification improvement analyses.

DISCUSSION

OPG, a well-known bone biomarker, was associated with CVEs independent of cytokine activity. In contrast, the association between CVEs and the remaining three bone-associated proteins (TRAIL-R2, CTSD, and CTSL1) was affected by cytokine inflammation activity.

TRAIL and Cardiovascular Disease-A Risk Factor or Risk Marker: A Systematic Review

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a pro-apoptotic protein showing broad biological functions. Data from animal studies indicate that TRAIL may possibly contribute to the pathophysiology of cardiomyopathy, atherosclerosis, ischemic stroke and abdominal aortic aneurysm. It has been also suggested that TRAIL might be useful in cardiovascular risk stratification. This systematic review aimed to evaluate whether TRAIL is a risk factor or risk marker in cardiovascular diseases (CVDs) focusing on major adverse cardiovascular events. Two databases (PubMed and Cochrane Library) were searched until December 2020 without a year limit in accordance to the PRISMA guidelines. A total of 63 eligible original studies were identified and included in our systematic review. Studies suggest an important role of TRAIL in disorders such as heart failure, myocardial infarction, atrial fibrillation, ischemic stroke, peripheral artery disease, and pulmonary and gestational hypertension. Most evidence associates reduced TRAIL levels and increased TRAIL-R2 concentration with all-cause mortality in patients with CVDs. It is, however, unclear whether low TRAIL levels should be considered as a risk factor rather than a risk marker of CVDs. Further studies are needed to better define the association of TRAIL with cardiovascular diseases.

Uremic serum-induced calcification of human aortic smooth muscle cells is a regulated process involving Klotho and RUNX2

Vascular calcification (VC) is common in subjects with chronic kidney disease (CKD) and is associated with increased cardiovascular risk. It is an active process involving transdifferentiation of arterial smooth muscle cells (SMCs) into osteogenic phenotype. We investigated the ability of serum from CKD subjects to induce calcification in human SMCs in vitro (calcific potential of sera: CP), and associated changes in expression of Runt-related transcription factor 2 (RUNX2), SM22α, and Klotho. Sera from subjects with CKD (18 stage 3, 17 stage 4/5, and 29 stage 5D) and 20 controls were added to human cultured SMCs and CP quantified. The CP of CKD sera was greater (P<0.01) than that of controls, though not influenced by CKD stage. Modification of diet in renal disease estimated glomerular filtration rate (MDRD-4 eGFR) (P<0.001), serum phosphate (P=0.042), receptor activator of nuclear factor κappa-B ligand (RANKL) (P=0.001), parathyroid hormone (PTH) (P=0.014), and high-density lipoprotein (HDL)/cholesterol ratio (P=0.026) were independent predictors of CP accounting for 45% of variation. Adding calcification buffer (CB: calcium chloride [7 mM] and β-glycerophosphate [7 mM]) increased the CP of control sera to approximate that of CKD sera. CP of CKD sera was unchanged. CKD sera increased RUNX2 expression (P<0.01) in human SMCs and decreased SM22α expression (P<0.05). Co-incubating control but not CKD serum with CB further increased RUNX2 expression (P<0.01). Both SM22α and Klotho expression decreased significantly (P<0.01) in the presence of CKD serum, and were virtually abolished with stage 5D sera. These findings support active regulation by CKD serum of in vitro VC by induction of RUNX2 and suppression of SM22α and Klotho.

miR-145 improves metabolic inflammatory disease through multiple pathways

Chronic inflammation plays a pivotal role in insulin resistance and type 2 diabetes, yet the mechanisms are not completely understood. Here, we demonstrated that serum LPS levels were significantly higher in newly diagnosed diabetic patients than in normal control. miR-145 level in peripheral blood mononuclear cells decreased in type 2 diabetics. LPS repressed the transcription of miR-143/145 cluster and decreased miR-145 levels. Attenuation of miR-145 activity by anti-miR-145 triggered liver inflammation and increased serum chemokines in C57BL/6 J mice. Conversely, lentivirus-mediated miR-145 overexpression inhibited macrophage infiltration, reduced body weight, and improved glucose metabolism in db/db mice. And miR-145 overexpression markedly reduced plaque size in the aorta in ApoE-/- mice. Both OPG and KLF5 were targets of miR-145. miR-145 repressed cell proliferation and induced apoptosis partially by targeting OPG and KLF5. miR-145 also suppressed NF-κB activation by targeting OPG and KLF5. Our findings provide an association of the environment with the progress of metabolic disorders. Increasing miR-145 may be a new potential therapeutic strategy in preventing and treating metabolic diseases such as type 2 diabetes and atherosclerosis.

Predictive Value of Osteoprotegerin for Detecting Coronary Artery Calcification in Type 2 Diabetes Mellitus Patients in Correlation with Extent of Calcification Detected by Multidetector Computed Tomography

Background:

Osteoprotegerin (OPG) is a tumor necrosis factor receptor super-family member. It specifically acts on bone by increasing bone mineral density and bone volume. Recent studies have evidenced its close relation to the development of atherosclerosis and plaque destabilization. Elevated OPG level has also been associated with the degree of coronary calcification in the general population and it has been considered to be a marker of coronary atherosclerosis.

Objective:

The aim of this study was to determine the relation between OPG levels and Coronary Artery Calcification score (CACs) in Type 2 diabetic patients in comparison to healthy controls.

Methods:

Our study included 45 type 2 diabetic patients (mean age 51.7 years; 51.1% male) without evidence of previous CVD and 45 healthy age and sex matched subjects as control. All participants were subjected to full history, full examination and lab investigations. Serum OPG concentration was measured by an enzyme-linked immunosorbent assay (ELISA) and CAC imaging was performed using non contrast Multi detector CT of the heart.

Results:

Significant CAC (<10 Agatston units) was seen in 23 patients (51.11 %).

:

OPG was significantly high in diabetic patients in comparison to controls with mean 12.9±5.7 pmol/l in cases, and 8.6±0.5 pmol/l in controls (P value < 0.001).

:

The Coronary Artery Calcification Score (CACS) was positively correlated with age and duration of diabetes. The OPG was positively correlated with age, fasting blood sugar and duration of diabetes. The CACS showed a significantly positive correlation with OPG.

Conclusion:

Findings suggested that increasing in serum OPG was consistent with CAC and could be used for the early diagnosis of subclinical atherosclerosis.

Bilateral Lower Limb Disabling Claudication in a Young Man: A Case of Mönckeberg’s Arteriosclerosis

Mönckeberg’s arteriosclerosis, also called medial calcific sclerosis or Mönckeberg’s sclerosis, is a form of vessel hardening due to increased calcium deposits in the tunica media layer. There is disagreement over its clinical significance and aetiology and its relation to atherosclerosis and vascular calcification. Its clinical presentations and treatment are still debated. More effort should be directed on attempting to distinguish between atherosclerotic lesions and Mönckeberg’s lesions on the basis of age, location and the pattern of calcifications where there is considerable overlap between intimal or medial and involvement of the internal elastic lamina border between those planes. In-depth research is still needed to create consensus guidelines for the diagnosis and management of this condition. This article includes a review of the literature and a case report of a 22-year-old man with the condition.

The Correlation of Serum Osteoprotegerin with Non-Traditional Cardiovascular Risk Factors and Arterial Stiffness in Patients with Pre-Dialysis Chronic Kidney Disease: Results from the KNOW-CKD Study

BACKGROUND

Osteoprotegerin (OPG) plays protective roles against the development of vascular calcification (VC) which greatly contributes to the increased cardiovascular events in patients with chronic kidney disease (CKD). The present study aimed to find the non-traditional, kidney-related cardiovascular risk factors correlated to serum OPG and the effect of serum OPG on the arterial stiffness measured by brachial ankle pulse wave velocity (baPWV) in patients with the pre-dialysis CKD.

METHODS

We cross-sectionally analyzed the data from the patients in whom baPWV and the serum OPG were measured at the time of enrollment in a prospective pre-dialysis CKD cohort study in Korea.

RESULTS

Along with traditional cardiovascular risk factors such as age, diabetes mellitus, pulse pressure, and baPWV, non-traditional, kidney-related factors such as albuminuria, plasma level of hemoglobin, total CO₂ content, alkaline phosphatase, and corrected calcium were independent variables for serum OPG in multivariate linear regression. Reciprocally, the serum OPG was positively associated with baPWV in multivariate linear regression. The baPWV in the 3rd and 4th quartile groups of serum OPG were higher than that in the 1st quartile group after adjustments by age, sex and other significant factors for baPWV in linear mixed model.

CONCLUSION

Non-traditional, kidney-related cardiovascular risk factors in addition to traditional cardiovascular risk factors were related to serum level of OPG in CKD. Serum OPG level was significantly related to baPWV. Our study suggests that kidney-related factors involved in CKD-specific pathways for VC play a role in the increased secretion of OPG into circulation in patients with CKD.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01630486.

Osteoprotegerin and Cardiovascular Events in High-Risk Populations: Meta-Analysis of 19 Prospective Studies Involving 27 450 Participants

Background Osteoprotegerin is a cytokine involved in bone metabolism as well as vascular calcification and atherogenesis. Although circulating osteoprotegerin levels are robustly associated with incident cardiovascular disease ( CVD ) in the general population, its relevance as a biomarker among populations at high CVD risk is less clear. Methods and Results Three independent reviewers systematically searched PubMed, EMBASE , and Web of Science to identify prospective studies that had recruited participants on the basis of having conditions related to high CVD risk. A total of 19 studies were eligible for inclusion, reporting on 27 450 patients with diabetes mellitus (2 studies), kidney disease (7 studies), preexisting heart disease (5 studies), or recent acute coronary syndromes (5 studies) at baseline. Over a mean follow-up of 4.2 years, 4066 CVD events were recorded. In a random-effects meta-analysis, the pooled risk ratio for CVD events comparing people in the top versus the bottom tertile of osteoprotegerin concentration was 1.30 (95% confidence interval, 1.12-1.50; P<0.001; I2=68.3%). There was evidence for presence of publication bias ( P value from Egger's test=0.013). Correction for publication bias using the trim-and-fill method reduced the risk ratio to 1.21 (95% confidence interval, 1.03-1.42; P<0.001). The risk ratios did not vary significantly by population type, geographical region, statistical adjustment, sample or assay type, age, sex, or length of follow-up. Conclusions In populations at high CVD risk, elevated circulating osteoprotegerin levels are associated with a higher risk for future CVD events. The magnitude of association appears weaker than in the general population.

Role of osteoprotegerin/receptor activator of nuclear factor kappa B/receptor activator of nuclear factor kappa B ligand axis in nonalcoholic fatty liver disease

Concomitantly with the increase in the prevalences of overweight/obesity, nonalcoholic fatty liver disease (NAFLD) has worldwide become the main cause of chronic liver disease in both adults and children. Patients with fatty liver display features of metabolic syndrome (MetS), like insulin resistance (IR), glucose intolerance, hypertension and dyslipidemia. Recently, epidemiological studies have linked obesity, MetS, and NAFLD to decreased bone mineral density and osteoporosis, highlighting an intricate interplay among bone, adipose tissue, and liver. Osteoprotegerin (OPG), an important symbol of the receptor activator of nuclear factor-B ligand/receptor activator of nuclear factor kappa B/OPG system activation, typically considered for its role in bone metabolism, may also play critical roles in the initiation and perpetuation of obesity-related comorbidities. Clinical data have indicated that OPG concentrations are associated with hypertension, left ventricular hypertrophy, vascular calcification, endothelial dysfunction, and severity of liver damage in chronic hepatitis C. Nonetheless, the relationship between circulating OPG and IR as a key feature of MetS as well as between OPG and NAFLD remains uncertain. Thus, the aims of the present review are to provide the existent knowledge on these associations and to discuss briefly the underlying mechanisms linking OPG and NAFLD.

The role of OPG/RANKL in the pathogenesis of diabetic cardiovascular disease

Cardiovascular (CV) disease is the leading cause of mortality in patients with type 2 diabetes mellitus. A major factor in the pathogenesis of CV disease is vascular calcification (VC), which is accelerated in type 2 diabetes mellitus. Calcification of the vessel wall contributes to vascular stiffness and left ventricular hypertrophy whereas intimal calcification may predispose to plaque rupture and CV death. The pathogenesis of VC is complex but appears to be regulated by the osteoprotegerin (OPG)/receptor activator of nuclear factor-κB ligand (RANKL) signaling pathway, which is involved in bone remodeling. Within the bone, OPG prevents RANKL from binding to receptor activator of nuclear factor-κB and inhibiting bone resorption. Outside of the bone, the clinical significance of OPG blocking RANKL is not well understood, but OPG knockout mice that lack OPG develop early and severe VC. This minireview outlines some of the research on OPG/RANKL in the pathogenesis of VC and discusses potential therapies, which may reduce VC and CV burden in humans.

The Role of Osteoprotegerin as a Cardioprotective Versus Reactive Inflammatory Marker: the Chicken or the Egg Paradox

Cardiovascular disease is one of the most frequent causes of mortality and morbidity worldwide. Several variables have been identified as risk factors for cardiovascular disease. Recently, the role of receptor activator of nuclear factor kappa B, receptor activator of nuclear factor kappa B ligand, and the osteoprotegerin system has been recognized as more important in the pathogenesis of cardiovascular disease. Besides their roles in the regulation of bone resorption, these molecules have been reported to be associated with the pathophysiology of cardiovascular disease. There are conflicting data regarding the impact of osteoprotegerin, a glycoprotein with a regulatory role in the cardiovascular system. The aim of this review is to discuss the current knowledge and the role of osteoprotegerin in cardiovascular disease.

RANKL Inhibits the Production of Osteoprotegerin from Smooth Muscle Cells under Basal Conditions and following Exposure to Cyclic Strain

Receptor activator of nuclear factor-κB ligand (RANKL) promotes vascular calcification, while osteoprotegerin (OPG) opposes it by blocking RANKL activity. It remains unclear which vascular cell populations produce and secrete OPG/RANKL. This study characterizes the production of OPG/RANKL from human aortic endothelial and smooth muscle cells (HAECs and HASMCs) under various conditions. HAECs and HASMCs were exposed to inflammatory stimuli (tumor necrosis factor-α or hyperglycemia) or physiological levels of hemodynamic (cyclic) strain. After 72 h, both cells and supernatant media were harvested for assessment of OPG/RANKL production. Based on initial findings, the experiments involving HASMCs were then repeated in the presence of exogenous RANKL. OPG was produced and secreted by HASMCs and (to a considerably lesser degree) HAECs under basal conditions. Inflammatory stimuli upregulated OPG production in both cell populations. Cyclic strain significantly upregulated OPG production in HASMCs. Neither cell population produced RANKL. Exposing HASMCs to exogenous RANKL inhibited basal OPG production and completely abrogated the strain-mediated upregulation of OPG. These data suggest that HASMCs are a significant source of OPG within the vasculature but that RANKL, once present, downregulates this production and appears capable of preventing the "protective" upregulation of OPG seen with HASMCs exposed to physiological levels of cyclic strain.

Prevalence of Calcification in Human Femoropopliteal Arteries and its Association with Demographics, Risk Factors, and Arterial Stiffness

OBJECTIVE

Arterial calcification and stiffening increase the risk of reconstruction failure, amputation, and mortality in patients with peripheral arterial disease, but underlying mechanisms and prevalence are unclear.

APPROACH AND RESULTS

Fresh human femoropopliteal arteries were obtained from n=431 tissue donors aged 13 to 82 years (mean age, 53±16 years) recording the in situ longitudinal prestretch. Arterial diameter, wall thickness, and opening angles were measured optically, and stiffness was assessed using planar biaxial extension and constitutive modeling. Histological features were determined using transverse and longitudinal Verhoeff-Van Gieson and Alizarin stains. Medial calcification was quantified using a 7-stage grading scale and was correlated with structural and mechanical properties and clinical characteristics. Almost half (46%) of the femoropopliteal arteries had identifiable medial calcification. Older arteries were more calcified, but small calcium deposits were observed in arteries as young as 18 years old. After controlling for age, positive correlations were observed between calcification, diabetes mellitus, dyslipidemia, and body mass index. Tobacco use demonstrated a negative correlation. Calcified arteries were larger in diameter but had smaller circumferential opening angles. They were also stiffer longitudinally and circumferentially and had thinner tunica media and external elastic lamina with more discontinuous elastic fibers.

CONCLUSIONS

Although aging is the dominant risk factor for femoropopliteal artery calcification and stiffening, these processes seem to be linked and can begin at a young age. Calcification is associated with the presence of certain risk factors and with elastic fiber degradation, suggesting overlapping molecular pathways that require further investigation.

Associations of osteoprotegerin with coronary artery calcification among women with systemic lupus erythematosus and healthy controls

Objective We tested the hypothesis that higher circulating levels of osteoprotegerin (OPG) are related to higher levels of coronary artery calcification (CAC) among women with systemic lupus erythematosus (SLE) compared with healthy controls (HCs). Methods Among 611 women in two age- and race-matched SLE case-control studies, OPG was assayed in stored blood samples (HEARTS: plasma, n cases/controls = 122/124, and SOLVABLE: serum, n cases/controls = 185/180) and CAC was measured by electron beam computed tomography. Results In both studies, SLE patients had higher OPG and CAC levels than HCs. Higher OPG was associated with high CAC (>100 vs.100) among SLE, and with any CAC (>0 vs. 0) among HCs. Multivariable-adjusted OR (95% CI) for OPG tertile 3 vs. 1 was 3.58 (1.19, 10.76), p trend = 0.01 for SLE, and 2.28 (1.06, 4.89), p trend = 0.04 for HCs. Associations were attenuated when age-adjusted, but remained significant for HC women aged ≥ 40 and SLE women aged ≥ 50. ROC analyses identified 4.60 pmol/l as the optimal OPG cutpoint for predicting high CAC (>100) among SLE patients with sensitivity = 0.74 and specificity = 0.61, overall, but 0.92 and 0.52, respectively, for SLE patients aged ≥ 50. Conclusion Our cross-sectional results suggest that higher OPG levels are related to higher CAC levels among women with SLE vs. healthy controls.

Circulating osteoprotegerin levels are elevated in rheumatoid arthritis: a systematic review and meta-analysis

This study aimed to systemically review the evidence regarding the relationship between the circulating blood osteoprotegerin (OPG) level and rheumatoid arthritis (RA), as well as the potential influential factors. Research related to plasma/serum OPG levels in RA patients and healthy controls were gathered using PubMed, EMBASE, and The Cochrane Library database (up to Jan. 1, 2017). Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated by fixed-effects or random-effect model analysis. Heterogeneity test was performed by the Q statistic and quantified using I ², and publication bias was evaluated using a funnel plot and Egger's linear regression test. After searching databases, 443 articles were obtained, and 11 studies with 710 RA patients and 561 controls were finally included. Meta-analysis revealed that, compared with the control group, the OPG level was significantly higher in the RA group (P < 0.001), with the SMD of 1.02 and 95%CI (0.20, 1.84). Subgroup analyses showed that race, disease duration, body mass index (BMI), and disease activity score based on the assessment of 28 joints (DAS28) were positively associated with OPG level in RA patients. Our meta-analysis revealed a significantly higher circulating OPG level in RA patients, and it was influenced by race, disease duration, BMI, and DAS28.

Deletion of a Distal RANKL Gene Enhancer Delays Progression of Atherosclerotic Plaque Calcification in Hypercholesterolemic Mice

Receptor activator of NF-κB ligand (RANKL) is a TNF-like cytokine which mediates diverse physiological functions including bone remodeling and immune regulation. RANKL has been identified in atherosclerotic lesions; however, its role in atherosclerotic plaque development remains elusive. An enhancer located 75 kb upstream of the murine Rankl gene's transcription start site designated D5 is important for its calciotropic hormone- and cytokine-mediated expression. Here, we determined the impact of RANKL levels in atherosclerotic plaque development in the D5 enhancer-null (D5^-/- ) mice in an atherogenic Apoe^-/- background fed a high-fat diet (HFD). Rankl mRNA transcripts were increased in aortic arches and thoracic aortae of Apoe^-/- mice; however, this increase was blunted in Apoe^-/- ;D5^-/- mice. Similarly, higher Rankl transcripts were identified in splenic T lymphocytes in Apoe^-/- mice, and their levels were reduced in Apoe^-/- ;D5^-/- mice. When analyzed by micro-computed tomography (µCT), atherosclerotic plaque calcification was identified in six out of eight Apoe^-/- mice, whereas only one out of eight Apoe^-/- ;D5^-/- mice developed plaque calcification after 12 weeks of HFD. However, following 18 weeks of HFD challenge, all of Apoe^-/- and Apoe^-/- ;D5^-/- animals developed atherosclerotic plaque calcification. Likewise, atherosclerotic lesion sizes were site-specifically reduced in the aortic arch of Apoe^-/- ;D5^-/- mice at initial stage of atherosclerosis and this effect was diminished as atherosclerosis proceeded to a more advanced stage. Our data suggest that deletion of the RANKL D5 enhancer delays the progression of atherosclerotic plaque development and plaque calcification in hypercholesterolemic mice. This work provides important insight into RANKL's regulatory role in atherosclerosis. J. Cell. Biochem. 118: 4240-4253, 2017. © 2017 Wiley Periodicals, Inc.

Absence of the Vitamin D Receptor Inhibits Atherosclerotic Plaque Calcification in Female Hypercholesterolemic Mice

Epidemiological and clinical data suggest adverse cardiovascular outcomes with respect to vitamin D deficiency. Here, we explored the effects of vitamin D in atherosclerotic plaque calcification in vivo by utilizing vitamin D receptor (Vdr)-deficient mice in an Apoe^-/- background. Animals were fed a high-fat diet (HFD) for either 12 or 18 weeks and then examined for atherosclerotic plaque development. In order to prevent calcium deficiency, Vdr^-/- and Apoe^-/- ;Vdr^-/- animals were fed a high-calcium rescue diet prior to initiation of the HFD feeding and supplemented with high-calcium water during HFD feeding. Although calcium supplementation improved bone mass in Vdr^-/- and Apoe^-/- ;Vdr^-/- mice, neither strain was fully rescued. Systemic inflammatory responses observed in the absence of VDR were exaggerated in Apoe^-/- mice. Whereas, hyperlipidemic profiles seen in Apoe^-/- mice were ameliorated in the absence of VDR. Micro-computed tomography (µCT) analysis revealed that six out of eight Apoe^-/- animals developed atherosclerotic plaque calcification following 12 weeks of HFD feeding and 100% of the mice developed plaque calcification after 18 weeks. In contrast, although atherosclerotic lesions were evident in Apoe^-/- ;Vdr^-/- mice at 12 and 18 weeks of HFD challenge, none of these animals developed plaque calcification at either time point. The active vitamin D hormone, 1,25(OH)₂ D₃ likely increased calcification in aortic smooth muscle cells perhaps by directly modulating expression of Alpl, Rankl, and Opg. Our data suggest that the absence of VDR inhibits atherosclerotic plaque calcification in hypercholesterolemic Apoe^-/- mice, providing additional insight into the role of vitamin D in atherosclerotic plaque calcification. J. Cell. Biochem. 118: 1050-1064, 2017. © 2016 Wiley Periodicals, Inc.

Dyslipidemia and Diabetes Increase the OPG/TRAIL Ratio in the Cardiovascular System

Background. Dyslipidemia and diabetes are two of the most well established risk factors for the development of cardiovascular disease (CVD). Both of them usually activate a complex range of pathogenic pathways leading to organ damage. Here we hypothesized that dyslipidemia and diabetes could affect osteoprotegerin (OPG) and TNF-related apoptosis-inducing ligand (TRAIL) expression in the vessels and the heart. Materials and Methods. Gene and protein expression of OPG, TRAIL, and OPG/TRAIL ratio were quantified in the aorta and the hearts of control mice, dyslipidemic mice, and diabetic mice. Results. Diabetes significantly increased OPG and the OPG/TRAIL ratio expression in the aorta, while dyslipidemia was the major determinant of the changes observed in the heart, where it significantly increased OPG and reduced TRAIL expression, thus increasing cardiac OPG/TRAIL ratio. Conclusions. This work shows that both dyslipidemia and diabetes affect OPG/TRAIL ratio in the cardiovascular system. This could contribute to the changes in circulating OPG/TRAIL which are observed in patients with diabetes and CVD. Most importantly, these changes could mediate/contribute to atherosclerosis development and cardiac remodeling.

Osteoprotegerin and osteoprotegerin/TRAIL ratio are associated with cardiovascular dysfunction and mortality among patients with renal failure

PURPOSE

The high prevalence of cardiovascular morbidity and mortality among patients with chronic kidney disease (CKD) is observed especially in those undergoing dialysis. Osteoprotegerin (OPG) and its ligands, receptor activator of nuclear factor kappa-B ligand (RANKL) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) have been associated with cardiovascular complications. Our aim was to study their role as cardiovascular risk factors in stage 5 CKD patients.

PATIENTS AND METHODS

OPG, RANKL and TRAIL concentrations were measured in 69 hemodialyzed CKD patients and 35 healthy volunteers. In CKD patients, cardiovascular dysfunction was assessed with aortic pulse wave velocity (AoPWV), carotid artery intima-media thickness (CCA-IMT), coronary artery calcium score (CACS) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) serum concentrations. Cardiovascular and overall mortality data were collected during a 7-years follow-up.

RESULTS

OPG plasma concentrations were higher in CKD patients comparing to controls. Total soluble RANKL was lower and OPG/RANKL ratio higher in patients. Soluble TRAIL concentrations did not differ between the groups and OPG/TRAIL ratio was higher in CKD patients. OPG and OPG/TRAIL positively predicted long-term mortality (all-cause and cardiovascular) in CKD patients. OPG positively correlated with AoPWV, CCA-IMT and NT-proBNP whereas OPG/TRAIL with AoPWV and NT-proBNP. Described relationships were independent of classical and non-classical cardiovascular risk factors, with exception of age.

CONCLUSIONS

Our study confirmed the role of OPG as a biomarker of cardiovascular dysfunction and a predictor of mortality in stage 5 CKD. OPG/TRAIL ratio can be proposed as a predictor of cardiovascular dysfunction and mortality.

Roles and Clinical Applications of OPG and TRAIL as Biomarkers in Cardiovascular Disease

Cardiovascular diseases (CVD) remain the major cause of death and premature disability in Western societies. Assessing the risk of CVD is an important aspect in clinical decision-making. Among the growing number of molecules that are studied for their potential utility as CVD biomarkers, a lot of attention has been focused on osteoprotegerin (OPG) and its ligands, which are receptor activator of nuclear factor κB ligand (RANKL) and TNF-related apoptosis-inducing ligand. Based on the existing literature and on our experience in this field, here we review what the possible roles of OPG and TRAIL in CVD are and their potential utility as CVD biomarkers.

Distribution of alkaline phosphatase, osteopontin, RANK ligand and osteoprotegerin in calcified human carotid atheroma

Ectopic vascular calcification is a significant component of atherosclerotic disease. Osteopontin (OPN), Osteoprotegerin (OPG), Receptor Activator of NFκB Ligand (RANKL), and alkaline phosphatase (ALP) are each thought to play central roles in the calcification or demineralization of atherosclerotic lesions. Abnormalities in the balance of these proteins may lead to perturbations in bone remodeling and arterial calcification. The purpose of this study was to measure the distribution of these proteins in human carotid lesions and to elucidate possible mechanism(s) whereby they control the deposition or depletion of arterial calcification. Thirty-three patients who had undergone carotid endarterectomy (CEA) within the previous 18 months and 11 control patients were enrolled. CEA specimens were analyzed by EBCT for calcification content in terms of Agatston (AGAT) and Volume scores. CEA specimens were then cut into 5 mm segments which were homogenized and extracted. Extracts were analyzed for tissue levels of calcium, phosphorus, ALP, OPN, RANKL, and OPG. Fasting blood samples were analyzed for the same components. In CEA tissue segments, the calcification levels (CHA AGAT) were inversely associated with the levels of OPG (r = -0.432/-0.579, p < 0.05) and positively associated with the levels of RANKL (r = 0.332/0.415, p < 0.05). In turn, the tissue levels of OPG were associated with homologous serum levels of OPG (r = 0.820/0.389, p < 0.001), and the tissue levels of RANKL were associated with the serum levels of homologous RANKL (r = 0.739/0.666, p < 0.0001). This study suggests that serum levels of OPG and RANKL may be useful biomarkers for estimating the degree of calcification in carotid atherosclerotic lesions.

Receptor activator of nuclear factor κB ligand/osteoprotegerin axis and vascular calcifications in patients with chronic kidney disease

Vascular calcifications are commonly observed in patients with chronic kidney disease (CKD) and contribute to the excessive cardiovascular morbidity and mortality rates observed in these patients populations. Although the pathogenetic mechanisms are not yet fully elucidated, recent evidence suggests a link between bone metabolism and the development and progression of vascular calcifications. Moreover, accumulating data indicate that receptor activator of nuclear factor κB ligand/osteoprotegerin axis which plays essential roles in the regulation of bone metabolism is also involved in extra-osseous bone formation. Further studies are required to establish the prognostic significance of the above biomarkers as predictors of the presence and severity of vascular calcifications in CKD patients and of cardiovascular morbidity and mortality. Moreover, randomized clinical trials are needed to clarify whether inhibition of osteoclast activity will protect from vascular calcifications.

Values of osteoprotegerin in aortic valve tissue in patients with significant aortic stenosis depend on the existence of concomitant coronary artery disease

INTRODUCTION

Calcific aortic valve stenosis (CAVS) is a serious clinical problem. The strongest predictor of CAVS progression is the amount of calcium in the aortic valve. The pathogenesis of CAVS is largely consistent with the pathogenesis of atherosclerosis; however, about 50% of patients with CAVS do not exhibit significant atherosclerosis. Cardiovascular calcification is currently considered an actively regulated process, in which the important role is attributed to the RANKL/RANK/OPG (receptor activator of nuclear factor κB ligand/RANK/osteoprotegerin) axis. We measured OPG levels in the tissue of calcified, stenotic aortic valves in relation to the presence or absence of coronary artery disease (CAD).

MATERIALS AND METHODS

Aortic valve samples were collected from 105 patients with calcified, mainly severe aortic stenosis, who were divided into two groups according to the presence of CAD. In Group A (n=44), there were normal coronary artery findings, while in Group B (n=61), there was angiographically demonstrated >50% stenosis of at least one coronary artery. The control Group C (n=21) consisted of patients without aortic stenosis and with normal angiographic findings on coronary arteries.

RESULTS

The highest tissue concentrations of OPG [median (pmol/L), 25th-75th percentile] were found in Group A [6.95, 3.96-18.37], which was significantly different compared to the other two groups (P=.026 and .001, respectively). The levels of OPG in Group B [4.15, 2.47-9.16] and in Group C [2.25, 1.01-5.08] did not differ significantly (P=.078); however, the lowest concentrations of OPG were found in Group C. Neither age nor gender in our study had effect on tissue levels of OPG (P=.994 for gender; P=.848 for age).

CONCLUSION

Calcified and narrowed aortic valves, compared to the normal valves, were accompanied by a change in tissue concentrations of OPG, which is, in addition, dependent on the presence or absence of CAD. The highest tissue concentrations of OPG in our work were found in patients with significant aortic stenosis without concomitant CAD.

Targeting local vascular and systemic consequences of inflammation on vascular and cardiac valve calcification

INTRODUCTION

Cardiac valve calcification and vascular calcification (VC) are associated with cardiovascular mortality in the general population and in patients with chronic kidney disease (CKD). CKD, diabetes mellitus, and atherosclerosis are among the causes of systemic inflammation that are associated with VC.

AREAS COVERED

This review collates clinical and experimental evidence that inflammation accelerates VC progression. Specifically, we review the actions of key pro-inflammatory cytokines and inflammation-related transcription factors on VC, and the role played by senescence. Inflammatory cytokines, such as the TNF superfamily and IL-6 superfamily, and inflammation-related transcription factor NF-κB promote calcification in cultured vascular smooth muscle cells, valvular interstitial cells, or experimental animal models through direct effects, but also indirectly by decreasing circulating Fetuin A or Klotho levels.

EXPERT OPINION

Experimental evidence suggests a causal link between inflammation and VC that would change the clinical approach to prevention and treatment of VC. However, the molecular basis remains unclear and little is known about VC in humans treated with drugs targeting inflammatory cytokines. The effect of biologicals targeting TNF-α, RANKL, IL-6, and other inflammatory mediators on VC, in addition to the impact of dietary phosphate in patients with chronic systemic inflammation, requires study.

Association of osteoprotegerin with peripheral artery disease in patients with type 2 diabetes

BACKGROUND

Osteoprotegerin plays a critical role in the pathogenesis of atherosclerosis. Elevated osteoprotegerin concentrations have been reported in microvascular complications of diabetes. Patients with diabetes are at increased risk of macrovascular complications, particularly peripheral artery disease (PAD).

AIM

To investigate the association between osteoprotegerin concentration and PAD in diabetes.

METHODS

In a cross-sectional setting, patients with type 2 diabetes for>5 years and no apparent diabetic foot ulcer were recruited. Patients underwent colour Doppler ultrasonography of lower limbs and were designated PAD+ if arterial narrowing was detected. Ankle-brachial index (ABI) was measured. Serum osteoprotegerin concentrations were determined.

RESULTS

Ninety-eight patients (47 PAD+, 51 PAD-) were recruited. Osteoprotegerin concentrations (median [interquartile range]) were significantly higher in PAD+ versus PAD- patients (0.80 [0.50-1.95] ng/mL vs 0.30 [0.25-0.40] ng/mL; P<0.001). In logistic regression, log-osteoprotegerin was a predictor of PAD in univariate and multivariable analyses. In the final multivariable model, adjusting for age, sex, body mass index, smoking, hypertension, glycaemic control, lipid profile, renal function and C-reactive protein, one standard deviation increase in log-osteoprotegerin was associated with a more than twofold increase in the risk of having PAD (odds ratio 2.26, 95% confidence interval 1.50-3.40). In PAD+ patients, osteoprotegerin was a significant predictor of disease severity, determined by ABI and percentage of vessel occlusion in univariate and multivariable models.

CONCLUSIONS

Osteoprotegerin concentrations are increased in patients with diabetes and PAD. Osteoprotegerin is an independent predictor of the presence and severity of PAD in diabetic patients.

Correlations between osteoprotegerin serum levels and body composition parameters in patients with sleep apnea syndrome and the possible influence on cardiovascular risk

INTRODUCTION

Osteoprotegerin (OPG) is a member of the tumor necrosis factor family and a key regulator in bone turnover; it plays a role in the development of many cardiovascular diseases and may be treated as a marker of vascular damage. Bioelectrical impedance analysis (BIA) is a reliable, non-invasive and effective technique for measuring body composition. The aim of the study was to evaluate correlations between osteoprotegerin serum levels and body composition parameters in sleep apnea patients and their influence on cardiovascular risk.

MATERIAL AND METHODS

A total of 125 patients with newly diagnosed OSA were enrolled in the study (including 34 females). The mean age was 54.48±8.81 years, mean AHI 33.16±20.44/h and mean BMI 33.76±7.18. A control group comprised 59 healthy subjects with mean age of 51.27±12.97 years and mean BMI 29.47±5.42. All subjects underwent a nocturnal respiratory polygraphy and body composition measurements were taken with bioelectrical impedance analysis. OPG serum levels were measured using the enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

In OSA patients OPG correlated negatively with muscle mass percentage (MM%), phase angle, fat free mass percentage (FFM%) and body cell mass percentage (BCM%), while there was a positive correlation between osteoprotegerin and fat mass percentage (FM%). We demonstrated higher OPG serum levels in OSA patients with cardiovascular diseases than in those without comorbidities (4.01 vs 3.46pmol/l, p<0.05).

CONCLUSION

Our findings, combined with previous observations in other diseases, suggest that elevated OPG serum levels together with selected body composition parameters may be helpful in identifying OSA patients with increased cardiovascular risk.

Long Term Effect of High Glucose and Phosphate Levels on the OPG/RANK/RANKL/TRAIL System in the Progression of Vascular Calcification in rat Aortic Smooth Muscle Cells

Osteoprotegerin (OPG), receptor activator of NF-κB ligand (RANKL)/receptor activator of NF-κB (RANK) axis, and TNF-related apoptosis-inducing ligand (TRAIL) participate in vascular calcification process including atherosclerosis, but their contributions under high glucose (HG) and phosphate (HP) condition for a long-term period (more than 2 weeks) have not been fully determined. In this study, we evaluated the effects of HG and HP levels over 2 or 4 weeks on the progression of vascular calcification in rat vascular smooth muscle cells (VSMCs). Calcium deposition in VSMCs was increased in medium containing HG (30 mmol/L D-glucose) with β-glycerophosphate (β-GP, 12 mmol/L) after 2 weeks and increased further after 4 weeks. OPG mRNA and protein expressions were unchanged in HG group with or without β-GP after 2 weeks. However, after 4 weeks, OPG mRNA and protein expressions were significantly lower in HG group with β-GP. No significant expression changes were observed in RANKL, RANK, or TRAIL during the experiment. After 4 weeks of treatment in HG group containing β-GP and rhBMP-7, an inhibitor of vascular calcification, OPG expressions were maintained. Furthermore, mRNA expression of alkaline phosphatase (ALP), a marker of vascular mineralization, was lower in the presence of rhBMP-7. These results suggest that low OPG levels after long term HG and phosphate stimulation might reduce the binding of OPG to RANKL and TRAIL, and these changes could increase osteo-inductive VSMC differentiation, especially vascular mineralization reflected by increased ALP activity during vascular calcification.

Below-knee arterial calcification in type 2 diabetes: association with receptor activator of nuclear factor κB ligand, osteoprotegerin, and neuropathy

CONTEXT

Calcification of the arterial wall in diabetes contributes to the arterial occlusive process occurring below the knee. The osteoprotegerin (OPG)/receptor activator of nuclear factor κB ligand (RANKL) system is suspected to be involved in the calcification process.

OBJECTIVE

The aim of the study was to investigate whether there is a link between arterial calcification in type 2 diabetes and 1) conventional cardiovascular risk factors, 2) serum RANKL and OPG levels, and 3) neuropathy.

PATIENTS AND METHODS

We objectively scored, in a cross-sectional study, infrapopliteal vascular calcification using computed tomography scanning in 198 patients with type 2 diabetes, a high cardiovascular risk, and a glomerular filtration rate >30 mL/min. Color duplex ultrasonography was performed to assess peripheral arterial occlusive disease, and mediacalcosis. Peripheral neuropathy was defined by a neuropathy disability score >6. RANKL and OPG were measured in the serum by routine chemistry.

RESULTS

Below-knee arterial calcification was associated with arterial occlusive disease. In multivariate logistic regression analysis, the variables significantly and independently associated with the calcification score were age (odds ratio [OR] = 1.08; 95% confidence interval [CI] = 1.04-1.13; P < .0001), male gender (OR = 3.53; 95% CI = 1.54-8.08; P = .003), previous cardiovascular disease (OR = 2.78; 95% CI = 1.39-5.59; P = .005), and neuropathy disability score (per 1 point, OR = 1.21; 95% CI = 1.05-1.38; P = .006). The association with ln OPG, significantly associated with calcification score in univariate analysis (OR = 3.14; 95% CI = 1.05-9.40; P = .045), was no longer significant in multivariate analysis. RANKL and OPG/RANKL were not significantly associated with the calcification score.

CONCLUSIONS

Below-knee arterial calcification severity is clearly correlated with peripheral neuropathy severity and with several usual cardiovascular risk factors, but not with serum RANKL level.

Role of bone mineral density in the inverse relationship between body size and aortic calcification: results from the Baltimore Longitudinal Study of Aging

OBJECTIVE

There is a J-shaped relationship between body mass index (BMI) and cardiovascular outcomes in elderly patients (obesity paradox). Whether low BMI correlates with aortic calcification (AC) and whether this association is accounted for by bone demineralization is uncertain.

METHODS

Presence of AC was evaluated in 687 community-dwelling individuals (49% male, mean age 67 ± 13 years) using CT images of the thoracic, upper and lower abdominal aorta, and scored from 0 to 3 according to number of sites that showed any calcification. Whole-body bone mineral density (BMD) was evaluated by dual-energy X-ray absorptiometry. Predictors of AC were assessed by logistic regression, and the role of BMD using mediation analysis.

RESULTS

Age and cardiovascular risk factors were positively associated while both BMI (r = -0.11, p < 0.01) and BMD (r = -0.17, p < 0.0001) were negatively associated with AC severity. In multivariate models, lower BMI (OR 0.96, 95%CI 0.92-0.99, p = 0.01), older age, higher systolic blood pressure, use of lipid-lowering drugs and smoking were independent predictors of AC. A nonlinear relationship between BMI and AC was noticed (p = 0.03), with decreased AC severity among overweight participants. After adjusting for BMD, the coefficient relating BMI to AC was reduced by 14% and was no longer significant, whereas BMD remained negatively associated with AC (OR 0.82, 95%CI 0.069-0.96, p = 0.01), with a trend for a stronger relationship in older participants.

CONCLUSION

Low BMI is associated with increased AC, possibly through calcium mobilization from bone, resulting in low BMD. Prevention of weight loss and bone demineralization with aging may help reducing AC.

5-aza-2'-Deoxycytidine, a DNA methyltransferase inhibitor, facilitates the inorganic phosphorus-induced mineralization of vascular smooth muscle cells

AIM

Vascular calcification, an independent risk factor for cardiovascular disease in patients with chronic kidney disease(CKD), refers to the mineralization of vascular smooth muscle cells(VSMCs) caused by phenotypic changes toward osteoblast-like cells. DNA methylation, mediated by DNA methyltransferases(DNMTs), plays an important role in the differentiation of osteoblasts. We herein assessed the effects of a DNMT inhibitor on phenotypic changes in VSMCs and the development of vascular calcification.

METHODS

The effects of 5-aza-2'-deoxycytidine(5-aza-dC), a DNMT inhibitor, on human aortic smooth muscle cells(HASMCs) were evaluated. The expression and DNA methylation status of osteogenic genes were determined using RT-qPCR and bisulfite sequencing, respectively. Mineralization of HASMCs was induced by high concentrations of inorganic phosphate(Pi), as confirmed by quantitation of the calcium levels and von Kossa staining. Moreover, we examined the effects of the suppression of DNMT1 and/or alkaline phosphatase(ALP) on the mineralization of HASMCs.

RESULTS

5-aza-dC increased the expression and activity of ALP and reduced the DNA methylation levels of the ALP promoter region in the HASMCs. In addition, both treatment with 5-aza-dC and downregulation of the DNMT1 expression promoted the Pi-induced mineralization of HASMCs. Moreover, both treatment with phosphonoformic acid(PFA), a sodium-dependent phosphate transporter inhibitor, and suppression of the ALP expression inhibited the 5-aza-dC-promoted mineralization of HASMCs.

CONCLUSIONS

The present study showed that DNMT inhibitors facilitate the Pi-induced development of vascular calcification via the upregulation of the ALP expression along with a reduction in the DNA methylation level of the ALP promoter region.

Osteoprotegerin (OPG) as a biomarker for diabetic cardiovascular complications

Osteoprotegerin (OPG) is a glycoprotein involved in bone metabolisms and with a regulatory role in immune, skeletal and vascular systems. Recently, circulating OPG levels have emerged as independent biomarkers of cardiovascular disease (CVD) in patients with acute or chronic heart disease, as well as in the healthy population. Furthermore, OPG has been implicated in various inflammations and linked to diabetes and poor glycaemic control. This review focuses on the relations between circulating OPG levels and cardiovascular complications, with special emphasis on diabetic patients. OPG levels were observed to increase concurrently with the severity of diabetic complications, that is, with the highest circulating OPG levels observed in diabetic patients dying from CVD. Although the clinical prognostic use of OPG may seem far away, OPG does look promising as a biomarker in order to help the cardiologist to a better risk-stratification of the patients.

The role of TNF-α and TNF superfamily members in the pathogenesis of calcific aortic valvular disease

Calcific aortic valve disease (CAVD) represents a slowly progressive pathologic process associated with major morbidity and mortality. The process is characterized by multiple steps: inflammation, fibrosis, and calcification. Numerous studies focalized on its physiopathology highlighting different "actors" for the multiple "acts." This paper focuses on the role of the tumor necrosis factor superfamily (TNFSF) members in the pathogenesis of CAVD. In particular, we discuss the clinical and experimental studies providing evidence of the involvement of tumor necrosis factor-alpha (TNF-α), receptor activator of nuclear factor-kappa B (NF-κB) ligand (RANKL), its membrane receptor RANK and its decoy receptor osteoprotegerin (OPG), and TNF-related apoptosis-inducing ligand (TRAIL) in valvular calcification.

Phosphate restriction significantly reduces mortality in uremic rats with established vascular calcification

The role of hyperphosphatemia in the pathogenesis of secondary hyperparathyroidism, cardiovascular disease, and progression of renal failure is widely known. Here we studied effects of dietary phosphate restriction on mortality and vascular calcification in uremic rats. Control and uremic rats were fed a high-phosphate diet and at 3 months a portion of rats of each group were killed. Serum phosphate and the calcium phosphate product increased in uremic rats, as did aortic calcium. Of the rats, 56% had positive aortic staining for calcium (von Kossa), RUNX2, and osteopontin. The remaining uremic rats were continued on diets containing high phosphate without and with sevelamer, or low phosphate, and after 3 more months they were killed. Serum phosphate was highest in uremic rats on high phosphate. Serum PTH and FGF-23 were markedly lower in rats on low phosphate. Mortality on high phosphate was 71.4%, with sevelamer reducing this to 37.5% and phosphate restriction to 5.9%. Positive aortic staining for von Kossa, RUNX2, and osteopontin was increased, but phosphate restriction inhibited this. Kidneys from low-phosphate and sevelamer-treated uremic rats had less interstitial fibrosis, glomerulosclerosis, and inflammation than those of uremic rats on high phosphate. Importantly, kidneys from rats on low phosphate showed improvement over kidneys from high-phosphate rats at 3 months. Left ventricles from rats on low phosphate had less perivascular fibrosis and smaller cardiomyocyte size compared to rats on high phosphate. Thus, intensive phosphate restriction significantly reduces mortality in uremic rats with severe vascular calcification.

Aortic valvular interstitial cells apoptosis and calcification are mediated by TNF-related apoptosis-inducing ligand

BACKGROUND/OBJECTIVES

Calcific aortic valvular disease (CAVD) is an actively regulated process characterized by the activation of specific osteogenic signaling pathways and apoptosis. We evaluated the involvement in CAVD of the TNF-related apoptosis-inducing ligand (TRAIL), an apoptotic molecule which induces apoptosis by interacting with the death receptor (DR)-4 and DR5, and whose activity is modulated by the decoy receptor (DcR)-1 and DcR2.

METHODS

Sections of calcific and normal aortic valves, obtained at surgery time, were subjected to immunohistochemistry and confocal microscopy for TRAIL immunostaining. Valvular interstitial cells (VICs) isolated from calcific (C-VICs) and normal (N-VICs) aortic valves were investigated for the gene and protein expression of TRAIL receptors. Cell viability was assayed by MTT. Von Kossa staining was performed to verify C-VIC ability to produce mineralized nodules. TRAIL serum levels were detected by ELISA.

RESULTS

Higher levels of TRAIL were detected in calcific aortic valves and in sera from the same patients respect to controls. C-VICs express significantly higher mRNA and protein levels of DR4, DR5, DcR1, DcR2 and Runx2 compared to N-VICs. C-VICs and N-VICs, cultured in osteogenic medium, express significantly higher mRNA levels of DR4, Runx2 and Osteocalcin compared to baseline. C-VICs and N-VICs were sensitive to TRAIL-apoptotic effect at baseline and after osteogenic differentiation, as demonstrated by MTT assay and caspase-3 activation. TRAIL enhanced mineralized matrix nodule synthesis by C-VICs cultured in osteogenic medium.

CONCLUSIONS

TRAIL is characteristically present within calcific aortic valves, and mediates the calcification of aortic valve interstitial cells in culture through mechanism involving apoptosis.

TRAIL-deficiency accelerates vascular calcification in atherosclerosis via modulation of RANKL

The osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) cytokine system, not only controls bone homeostasis, but has been implicated in regulating vascular calcification. TNF–related apoptosis-inducing ligand (TRAIL) is a second ligand for OPG, and although its effect in vascular calcification in vitro is controversial, its role in vivo is not yet established. This study aimed to investigate the role of TRAIL in vascular calcification in vitro using vascular smooth muscle cells (VSMCs) isolated from TRAIL^−/− and wild-type mice, as well as in vivo, in advanced atherosclerotic lesions of TRAIL^−/−ApoE^−/− mice. The involvement of OPG and RANKL in this process was also examined. TRAIL dose-dependently inhibited calcium-induced calcification of human VSMCs, while TRAIL^−/− VSMCs demonstrated accelerated calcification induced by multiple concentrations of calcium compared to wild-type cells. Consistent with this, RANKL mRNA was significantly elevated with 24 h calcium treatment, while OPG and TRAIL expression in human VSMCs was inhibited. Brachiocephalic arteries from TRAIL^−/−ApoE^−/− and ApoE^−/− mice fed a high fat diet for 12 w demonstrated increased chondrocyte-like cells in atherosclerotic plaque, as well as increased aortic collagen II mRNA expression in TRAIL^−/−ApoE^−/− mice, with significant increases in calcification observed at 20 w. TRAIL^−/−ApoE^−/− aortas also had significantly elevated RANKL, BMP-2, IL-1β, and PPAR-γ expression at 12 w. Our data provides the first evidence that TRAIL deficiency results in accelerated cartilaginous metaplasia and calcification in atherosclerosis, and that TRAIL plays an important role in the regulation of RANKL and inflammatory markers mediating bone turn over in the vasculature.

Comparison of osteoprotegerin and vascular endothelial growth factor in normoalbuminuric Type 1 diabetic and control subjects

BACKGROUND

The aim of the current study was to evaluate the association of osteoprotegerin and vascular endothelial growth factor (VEGF) with glycemic indices and diabetes status.

METHODS

A total of 44 normoalbuminuric Type 1 diabetic patients and 44 healthy control subjects, matched for age, body mass index, sex ratio, and lipid measures were enrolled. Univariate and multivariate logistic regression analyses were used to determine the association of osteoprotegerin and VEGF with diabetes status. Further, linear regression analysis was performed to investigate the roles of osteoprotegerin and VEGF as determinants of glycated hemoglobin (HbA1c).

RESULTS

Osteoprotegerin and VEGF were significantly elevated in diabetic subjects (2.76±0.85 vs 2.26±0.75 pmol/l and 187.1±92.7 vs 125.9±52.3 pg/ml, respectively, p<0.01) and were positively correlated with glycemic indices (i.e. fasting plasma glucose and HbA1c, p<0.001). After controlling for possible confounding factors, odds ratios (confidence interval) of osteoprotegerin and VEGF for diabetes were 2.532 (1.003-6.392) and 1.021 (1.002-1.041), respectively (p<0.05). Further, linear regression analysis revealed that the association of osteoprotegerin with HbA1c is independent of VEGF and vice versa (p<0.001).

CONCLUSION

Osteoprotegerin and VEGF are elevated in normoalbuminuric Type 1 diabetic subjects and are independently associated with glycemic indices and diabetes status.