Osteoprotegerin and osteopontin are expressed at high concentrations within symptomatic carotid atherosclerosis

Relationships between Osteopontin, Osteoprotegerin, and Other Extracellular Matrix Proteins in Calcifying Arteries

Osteopontin (OPN) and osteoprotegerin (OPG) are glycoproteins that participate in the regulation of tissue biomineralization. The aim of the project is to verify the hypothesis that the content of OPN and OPG in the aorta walls increases with the development of atherosclerosis and that these proteins are quantitatively related to the main proteins in the extracellular arteries matrix. Quantitative and qualitative analyses of the OPN and OPG content in 101 aorta sections have been conducted. Additionally, an enzyme-linked immunosorbent assay (ELISA) test has been performed to determine the collagen types I-IV and elastin content in the tissues. Correlations between the biochemical data and patients' age/sex, atherosclerosis stages, and calcification occurrences in the tissue have been established. We are the first to report correlations between OPN or OPG and various types of collagen and elastin content (OPG/type I collagen correlation: r = 0.37, p = 0.004; OPG/type II collagen: r = 0.34, p = 0.007; OPG/type III collagen: r = 0.39, p = 0.002, OPG/type IV collagen: r = 0.27, p = 0.03; OPG/elastin: r = 0.42, p = 0.001; OPN/collagen type I: r = 0.34, p = 0.007; OPN/collagen type II: r = 0.52, p = 0.000; OPN/elastin: r = 0.61, p = 0.001). OPN overexpression accompanies calcium deposit (CA) formation with the protein localized in the calcium deposit, whereas OPG is located outside the CA. Although OPN and OPG seem to play a similar function (inhibiting calcification), these glycoproteins have different tissue localizations and independent expression regulation. The independent expression regulation presumably depends on the factors responsible for stimulating the synthesis of collagens and elastin.

The Role of Osteopontin in Atherosclerosis and Its Clinical Manifestations (Atherosclerotic Cardiovascular Diseases)-A Narrative Review

Atherosclerotic cardiovascular diseases (ASCVDs) are the most common and severe public health problem nowadays. Osteopontin (OPN) is a multifunctional glycoprotein highly expressed at atherosclerotic plaque, which has emerged as a potential biomarker of ASCVDs. OPN may act as an inflammatory mediator and/or a vascular calcification (VC) mediator, contributing to atherosclerosis progression and eventual plaque destabilization. In this article, we discuss the complex role of OPN in ASCVD pathophysiology, since many in vitro and in vivo experimental data indicate that OPN contributes to macrophage activation and differentiation, monocyte infiltration, vascular smooth muscle cell (VSMC) migration and proliferation and lipid core formation within atherosclerotic plaques. Most but not all studies reported that OPN may inhibit atherosclerotic plaque calcification, making it "vulnerable". Regarding clinical evidence, serum OPN levels may become a biomarker of coronary artery disease (CAD) presence and severity. Significantly higher OPN levels have been found in patients with acute coronary syndromes than those with stable CAD. In limited studies of patients with peripheral artery disease, circulating OPN concentrations may be predictive of future major adverse cardiovascular events. Overall, the current literature search suggests the contribution of OPN to atherosclerosis development and progression, but more robust evidence is required.

The Effect of PCSK9 Inhibition on the Stabilization of Atherosclerotic Plaque Determined by Biochemical and Diagnostic Imaging Methods

Atherosclerosis is a multifactorial, progressive, chronic inflammatory disease. Ultrasound and magnetic resonance imaging are the most accurate predictors of atherosclerotic plaque instability (MRI). Cytokines such as osteopontin, osteoprotegerin, and metalloproteinase 9 could be used as the most recent markers to identify and track the efficacy of anti-atherosclerotic therapy. Patients with USG and MRI-verified unstable atherosclerotic plaque were included in the study. Biomarker concentrations were measured and compared before and after PCSK9 inhibitor therapy. Additionally, concentrations prior to treatment were correlated with MRI images of the carotid artery. After treatment with alirocumab, the concentrations of MMP-9 (p < 0.01) and OPN, OPG (p < 0.05) decreased significantly. Furthermore, the results of OPN, OPG, and MMP 9 varied significantly depending on the type of atherosclerotic plaque in the MRI assay. In stable atherosclerotic plaques, the concentrations of OPN and OPG were greater (p < 0.01), whereas the concentration of MMP9 correlated with the instability of the plaque (p < 0.05). We demonstrated, probably for the first time, that alirocumab therapy significantly decreased the serum concentration of atherosclerotic plaque markers. In addition, we demonstrated the relationship between the type of atherosclerotic plaque as determined by carotid MRI and the concentration of these markers.

Osteoprotegerin and Ischemic Stroke Prognosis: A Prospective Multicenter Study and Mendelian Randomization Analysis

BACKGROUND

Osteoprotegerin was implicated in vascular injury and inflammatory responses, but its prognostic value in ischemic stroke remained unclear. We aimed to prospectively investigate the association between plasma osteoprotegerin and ischemic stroke prognosis combined with a Mendelian randomization analysis.

METHODS

Our prospective study follows the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) reporting guideline. We measured baseline plasma osteoprotegerin levels for 3490 ischemic stroke patients recruited between August 2009 and May 2013 in 26 hospitals across China. The primary outcome was a composite outcome of death and major disability at 3 months after ischemic stroke.

RESULTS

After adjustment for age, sex, admission National Institutes of Health Stroke Scale score, and other important covariates, elevated osteoprotegerin levels were associated with increased risks of primary outcome (odds ratio, 1.40 [95% CI, 1.05-1.88]), death (hazard ratio, 2.05 [95% CI, 1.04-4.08]), and composite outcome of death and vascular events (hazard ratio, 2.00 [95% CI, 1.15-3.48]) when 2 extreme quartiles were compared. Each 1-SD higher log-osteoprotegerin was associated with a 18% (95% CI, 6%-32%) increased risk of primary outcome, 69% (95% CI, 31%-118%) increased risk of death, and 53% (95% CI, 24%-89%) increased risk of composite outcome of death and vascular events, respectively. Multiple-adjusted spline regression model showed a linear association of osteoprotegerin with primary outcome (P for linearity <0.001). Adding osteoprotegerin to conventional risk factors did not significantly improve discriminatory power (C statistics, 0.817 versus 0.818; P=0.232) but did slightly improve the risk reclassification of primary outcome (net reclassification improvement: 13.68%, P<0.001; integrated discrimination improvement: 0.23%, P=0.039). In Mendelian randomization analysis, genetically determined high plasma osteoprotegerin was associated with increased risk of primary outcome (odds ratio, 5.74 [95% CI, 1.12-29.44]; P=0.036).

CONCLUSIONS

Elevated plasma osteoprotegerin was associated with poor prognosis of ischemic stroke, and genetically determined high plasma osteoprotegerin was associated with an increased risk of primary outcome in Mendelian randomization analysis.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT01840072.

Identification of potential drug targets for vascular dementia and carotid plaques by analyzing underlying molecular signatures shared by them

Background

Vascular dementia (VaD) and carotid atherosclerotic plaques are common in the elderly population, conferring a heavy burden on families and society. Accumulating evidence indicates carotid atherosclerotic plaques to be a risk factor for VaD. However, the underlying mechanisms for this association are mainly unknown.

Materials and methods

We analyzed temporal cortex gene expression data of the GSE122063 dataset and gene expression data of the GSE163154 dataset to identify commonly differentially expressed genes (DEGs). Then we performed functional enrichment analysis, immune cell infiltration and evaluation, correlation analysis between differentially expressed immune-related genes (DEIRGs) and immune cells, receiver operating characteristic (ROC) analysis, and drug-gene analysis.

Results

We identified 41 overlapped DEGs between the VaD and carotid atherosclerosis plaque datasets. Functional enrichment analyses revealed that these overlapped DEGs were mainly enriched in inflammatory and immune-related processes. Immunocyte infiltration and evaluation results showed that M0 macrophages, M2 macrophages, and T cells gamma delta had a dominant abundance in carotid atherosclerosis plaque samples, and M0 macrophages showed a significantly different infiltration percentage between the early and advanced stage plaques group. Resting CD4 memory T cells, M2 macrophages, and naive B cells were the top three highest infiltrating fractions in VaD. Furthermore, B cells and NK cells showed a different infiltration percentage between VaD and matched controls. We identified 12 DEIRGs, and the result of correlation analysis revealed that these DEIRGs were closely related to differentially expressed immune cells. We identified five key DEIRGs based on ROC analysis. The drug-gene interaction analysis showed that four drugs (avacopan, CCX354, BMS-817399, and ASK-8007) could be potential drugs for VaD and carotid atherosclerotic plaques treatment.

Conclusion

Collectively, these findings indicated that inflammatory and immune-related processes be a crucial common pathophysiological mechanism shared by VaD and carotid plaques. This study might provide new insights into common molecular mechanisms between VaD and carotid plaques and potential targets for the treatment.

Identification Markers of Carotid Vulnerable Plaques: An Update

Vulnerable plaques have been a hot topic in the field of stroke and carotid atherosclerosis. Currently, risk stratification and intervention of carotid plaques are guided by the degree of luminal stenosis. Recently, it has been recognized that the vulnerability of plaques may contribute to the risk of stroke. Some classical interventions, such as carotid endarterectomy, significantly reduce the risk of stroke in symptomatic patients with severe carotid stenosis, while for asymptomatic patients, clinically silent plaques with rupture tendency may expose them to the risk of cerebrovascular events. Early identification of vulnerable plaques contributes to lowering the risk of cerebrovascular events. Previously, the identification of vulnerable plaques was commonly based on imaging technologies at the macroscopic level. Recently, some microscopic molecules pertaining to vulnerable plaques have emerged, and could be potential biomarkers or therapeutic targets. This review aimed to update the previous summarization of vulnerable plaques and identify vulnerable plaques at the microscopic and macroscopic levels.

Mechanistic insight into premature atherosclerosis and cardiovascular complications in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is associated with a significant risk of cardiovascular disease (CVD), which substantially increases disease mortality and morbidity. The overall mechanisms associated with the development of premature atherosclerosis and CVD in SLE remain unclear, but has been considered as a result of an intricate interplay between the profound immune dysregulation and traditional CVD risk factors. Aberrant systemic inflammation in SLE may lead to an abnormal lipid profile and dysfunction, which can further fuel the pro-atherosclerotic environment. The existence of a strong imbalance between endothelial damage and vascular repair/angiogenesis promotes vascular injury, which is the early step in the progression of atherosclerotic CVD. Profound innate and adaptive immune dysregulation, characterized by excessive type I interferon burden, aberrant macrophage, platelet and complements activation, neutrophil dysregulation and neutrophil extracellular traps formation, uncontrolled T cell activation, and excessive autoantibody production and immune complex formation, have been proposed to promote accelerated CVD in SLE. While designing targeted therapies to correct the dysregulated immune activation may be beneficial in the treatment of SLE-related CVD, much additional work is needed to determine how to translate these findings into clinical practice. Additionally, a number of biomarkers display diagnostic potentials in improving CVD risk stratification in SLE, further prospective studies will help understand which biomarker(s) will be the most impactful one(s) in assessing SLE-linked CVD. Continued efforts to identify novel mechanisms and to establish criteria for assessing CVD risk as well as predicting CVD progression are in great need to improve CVD outcomes in SLE.

Potential Protein Blood-Based Biomarkers in Different Types of Dementia: A Therapeutic Overview

Abstract:

Biomarkers capable of identifying and distinguishing types of dementia such as Alzheimer's disease (AD), Parkinson's disease dementia (PDD), Lewy body dementia (LBD), and frontotemporal dementia (FTD) have been become increasingly relentless. Studies of possible biomarker proteins in the blood that can help formulate new diagnostic proposals and therapeutic visions of different types of dementia are needed. However, due to several limitations of these biomarkers, especially in discerning dementia, their clinical applications are still undetermined. Thus, the updating of biomarker blood proteins that can help in the diagnosis and discrimination of these main dementia conditions is essential to enable new pharmacological and clinical management strategies, with specificities for each type of dementia. To review the literature concerning protein blood-based AD and non-AD biomarkers as new pharmacological targets and/or therapeutic strategies. Recent findings for protein-based AD, PDD, LBD, and FTD biomarkers are focused on in this review. Protein biomarkers were classified according to the pathophysiology of the dementia types. The diagnosis and distinction of dementia through protein biomarkers is still a challenge. The lack of exclusive biomarkers for each type of dementia highlights the need for further studies in this field. Only after this, blood biomarkers may have a valid use in clinical practice as they are promising to help in diagnosis and in the differentiation of diseases.

Bone-sparing effects of rituximab and body composition analysis in a cohort of postmenopausal women affected by rheumatoid arthritis - retrospective study

Objective

Osteoporosis is the most common bone tissue disease and it is characterized by a reduced bone mineral density (BMD). The main physiopathological mechanisms converge on the uncoupling between bone formation and resorption, thus leading to an enhanced risk of fractures. Several papers have documented the inverse relationships linking high inflammatory cytokines, anti-citrullinated protein antibodies, rheumatoid factor, and BMD in rheumatoid arthritis (RA). Rituximab (RTX) is a chimeric monoclonal antibody directed against the CD20 receptor of B cells. Since the Food and Drug Administration approved it for RA in 2006, there have been many clinical experiences regarding its use. Nevertheless, few studies evaluate the effect of rituximab on BMD. RA is a disease characterized by immune dysfunction with high levels of inflammatory cytokines, autoantibodies, and it is reasonable that a B cell depleting therapy could restore a physiological cytokine balance, thus exerting an osteoprotective effect on the bone tissue. The purpose of this paper is to highlight any difference in BMD and to assess differences in body composition over a retrospective 18-month follow-up period after RTX treatment with a B cell depleting therapy.

Material and methods

We analyzed by dual energy X-ray absorptiometry BMD expressed as g/cm² and body composition modifications over 18 months with RTX treatment of 20 postmenopausal RA patients.

Results

After eighteen months of therapy with RTX, a statistically significant increase in vertebral (L1–L4) BMD and the stability of femoral BMD were documented.

Conclusions

Rituximab is associated with an improvement of vertebral and preservation of femoral BMD, suggesting a bone-sparing effect due to B cell depletion. Furthermore, patients displayed a redistribution of fat masses toward the hip region.

Plasmatic osteopontin and vascular access dysfunction in hemodialysis patients: a cross-sectional, case-control study (The OSMOSIS Study)

BACKGROUND AND AIMS

Despite close follow-up of patients with native arteriovenous fistulas (AVFs), up to 10% experience thrombosis each year. The OSMOSIS Study (Osteopontin as a Marker of Stenosis) tested the hypothesis that the systemic osteopontin level, a pro-inflammatory mediator related to vascular remodelling and intimal hyperplasia, increases in AVF stenosis, and may be used in clinical surveillance.

METHODS

Our cross-sectional study compared the level of plasmatic osteopontin (pOPN) between patients with a well-functioning AVF (control group) and patients who required revision of their AVF due to stenosis (stenosis group). Blood samples were collected before dialysis (control group) or before intervention (stenosis group) from the AVF arm, and from the opposite arm as a within-subject control. pOPN level was measured by enzyme-linked immunosorbent assay.

RESULTS

A total of 76 patients were included in the study. Baseline characteristics were similar between the groups (mean age, 70 years; men, 63%; AVF duration, 39 months), apart from prevalence of type 2 diabetes (T2D) (control group, 33%; stenosis group, 57%; p = 0.04). pOPN levels were similar between the AVF arm and the contralateral arm (551 ± 42 ng/mL vs. 521 ± 41 ng/mL, respectively, p = 0.11, paired t-test). Patients in the stenosis group displayed a higher pOPN level than patients in the control group (650.2 ± 59.8 ng/mL vs. 460.5 ± 61.2, respectively, p = 0.03; two-way ANOVA). T2D was not identified as an associated factor in a multivariate analysis (p = 0.50).

CONCLUSIONS

The level of pOPN in hemodialysis patients was associated with the presence of AVF stenosis requiring intervention. Thus, its potential as a diagnostic biomarker should be assessed in a vascular access surveillance program.

Osteoporosis Entwined with Cardiovascular Disease: The Implication of Osteoprotegerin and the Example of Statins

Beyond being epiphenomenon of shared epidemiological factors, the integration of Osteoporosis (OP) with Cardiovascular Disease (CVD) - termed "calcification paradox" - reflects a continuum of aberrant cardiometabolic status. The present review provides background knowledge on "calcification paradox", focusing on the endocrine aspect of vasculature orchestrated by the osteoblastic molecular fingerprint of vascular cells, acquired via imbalance among established modulators of mineralization. Osteoprotegerin (OPG), the well-established osteoprotective cytokine, has recently been shown to exert a vessel-modifying role. Prompted by this notion, the present review interrogates OPG as the potential missing link between OP and CVD. However, so far, the confirmation of this hypothesis is hindered by the equivocal role of OPG in CVD, being both proatherosclerotic and antiatherosclerotic. Further research is needed to illuminate whether OPG could be a biomarker of the "calcification paradox". Moreover, the present review brings into prominence the dual role of statins - cardioprotective and osteoprotective - as a potential illustration of the integration of CVD with OP. Considering that the statins-induced modulation of OPG is central to the statins-driven osteoprotective signalling, statins could be suggested as an illustration of the role of OPG in the bone/vessels crosstalk, if further studies consolidate the contribution of OPG to the cardioprotective role of statins. Another outstanding issue that merits further evaluation is the inconsistency of the osteoprotective role of statins. Further understanding of the varying bone-modifying role of statins, likely attributed to the unique profile of different classes of statins defined by distinct physicochemical characteristics, may yield tangible benefits for treating simultaneously OP and CVD.

Osteopontin and osteoprotegerin in atherosclerotic plaque - are they significant markers of plaque vulnerability?

Atherosclerosis (ATS) is still considered as a major, global health problem. For a deeper understanding of its pathogenesis, in the last years the research was translated from tissue visible events to molecular mechanisms. Osteopontin (OPN) and osteoprotegerin (OPG) are two molecules that have been associated with the initiation and progression of ATS lesions. The aim of our study was to assess the OPN and OPG expression in advanced stages of carotid ATS, to analyze the correlation between these markers and the ultrasonographic plaque properties, pointing out the identification of possible patterns that can predict plaque vulnerability and risks of restenosis. The study group comprised 49 consecutive patients (38 males and 11 females) diagnosed with carotid stenotic lesions by using ultrasonography. The carotid endarterectomy specimens were standardly processed for histopathological and immunohistochemical exams. The OPN and OPG expression was semi-quantitatively assessed. Our results sustained the relationship between histological American Heart Association (AHA) type and ultrasonographic classification (echogenic versus echolucent) (p<0.001). The semi-quantitative analysis showed that in most cases (31 plaques) OPG and OPN had opposite expressions, whereas in the remaining cases (18 plaques) the expression was similar. There were no correlations between low versus high expression of intra-plaque OPN and OPG (p=0.335). We found significant correlation for OPN and plaque echogenicity (p=0.011), but not for OPG (p=0.079). OPN expression (low versus high) was correlated with plaque type (stable versus unstable) (p=0.036), plaque ulceration (p=0.009) and inflammation (p<0.001). OPG expression (low versus high) did not reveal statistically significant differences with plaque type (stable versus unstable) and vulnerability plaque parameters, respectively. OPG and OPN co-exist in carotid atherosclerotic plaque demonstrating a modulatory role in inflammatory and calcification processes. OPG is strongly expressed in stable, calcified plaques, while OPN is poorly expressed in calcified plaques and in plaques without hemorrhage, ulceration, inflammation, or necrosis. Starting from the molecular mechanisms, further studies of biomarkers are important to identify new therapeutic resources meant to prevent and treat vascular calcification.

Plasma osteopontin as a biomarker of Alzheimer's disease and vascular cognitive impairment

Cerebrovascular disease (CeVD) and neurodegenerative dementia such as Alzheimer’s disease (AD) are frequently associated comorbidities in the elderly, sharing common risk factors and pathophysiological mechanisms including neuroinflammation. Osteopontin (OPN) is an inflammatory marker found upregulated in vascular diseases as well as in AD. However, its involvement in vascular dementia (VaD) and pre-dementia stages, namely cognitive impairment no dementia (CIND), both of which fall under the spectrum of vascular cognitive impairment (VCI), has yet to be examined. Its correlations with inflammatory cytokines in cognitive impairment also await investigation. 80 subjects with no cognitive impairment (NCI), 160 with CIND and 144 with dementia were included in a cross-sectional study on a Singapore-based memory clinic cohort. All subjects underwent comprehensive clinical, neuropsychological and brain neuroimaging assessments, together with clinical diagnoses based on established criteria. Blood samples were collected and OPN as well as inflammatory cytokines interleukin (IL)-6, IL-8 and tumor necrosis factor (TNF) were measured using immunoassays. Multivariate regression analyses showed significant associations between increased OPN and VCI groups, namely CIND with CeVD, AD with CeVD and VaD. Interestingly, higher OPN was also significantly associated with AD even in the absence of CeVD. We further showed that increased OPN significantly associated with neuroimaging markers of CeVD and neurodegeneration, including cortical infarcts, lacunes, white matter hyperintensities and brain atrophy. OPN also correlated with elevated levels of IL-6, IL-8 and TNF. Our findings suggest that OPN may play a role in both VCI and neurodegenerative dementias. Further longitudinal analyses are needed to assess the prognostic utility of OPN in disease prediction and monitoring.

[Calcification and atherosclerosis of the coronary arteries]

Calcification is a very common phenomenon in the coronary arteries, which is part of the atherosclerotic process, and the degree of calcification can predict clinical outcomes in patients at high risk of coronary events. Both the degree of calcification and the patterns of its distribution are of prognostic importance, but the relationship of coronary artery calcification with atherosclerotic plaque instability is extremely complex and not fully understood. This article is devoted to the study of calcification markers and their influence on the development of atherosclerotic foci.

A Randomised Controlled Trial Assessing the Effects of Peri-operative Fenofibrate Administration on Abdominal Aortic Aneurysm Pathology: Outcomes From the FAME Trial

OBJECTIVE

Experimental studies suggest that fenofibrate prevents abdominal aortic aneurysm (AAA) development by lowering aortic osteopontin (OPN) concentration and reducing the number of macrophages infiltrating the aortic wall. The current study examined the effects of a short course of fenofibrate on AAA pathology in people with large AAAs awaiting aortic repair.

METHODS

This randomised double blind parallel trial included male and female participants aged ≥ 60 years who had an asymptomatic AAA measuring ≥ 50 mm and were scheduled to undergo open AAA repair. Participants were allocated to fenofibrate (145 mg/day) or matching placebo for at least two weeks before elective AAA repair. Blood samples were collected at recruitment and immediately prior to surgery. AAA biopsies were obtained during aortic surgery. The primary outcomes were (1) AAA OPN concentration; (2) serum OPN concentration; and (3) number of AAA macrophages. Exploratory outcomes included circulating and aortic concentrations of other proteins previously associated with AAA. Outcomes assessed at a single time point were compared using logistic regression. Longitudinal outcomes were compared using linear mixed effects models.

RESULTS

Forty-three participants were randomised. After three withdrawals, 40 were followed until the time of surgery (21 allocated fenofibrate and 19 allocated placebo). As expected, serum triglycerides reduced significantly from recruitment to the time of surgery in participants allocated fenofibrate. No differences in any of the primary and exploratory outcomes were observed between groups.

CONCLUSION

A short course of 145 mg of fenofibrate/day did not lower concentrations of OPN or aortic macrophage density in people with large AAAs.

Bone mineral density and mortality in end-stage renal disease patients

Osteoporosis characterized by low bone mineral density (BMD) as assessed by dual-energy X-ray absorptiometry (DXA) is common among end-stage renal disease (ESRD) patients and associates with high fracture incidence and high all-cause mortality. This is because chronic kidney disease-mineral bone disorders (CKD-MBDs) promote not only bone disease (osteoporosis and renal dystrophy) but also vascular calcification and cardiovascular disease. The disturbed bone metabolism in ESRD leads to 'loss of cortical bone' with increased cortical porosity and thinning of cortical bone rather than to loss of trabecular bone. Low BMD, especially at cortical-rich bone sites, is closely linked to CKD-MBD, vascular calcification and poor cardiovascular outcomes. These effects appear to be largely mediated by shared mechanistic pathways via the 'bone-vascular axis' through which impaired bone status associates with changes in the vascular wall. Thus, bone is more than just the scaffolding that holds the body together and protects organs from external forces but is-in addition to its physical supportive function-also an active endocrine organ that interacts with the vasculature by paracrine and endocrine factors through pathways including Wnt signalling, osteoprotegerin (OPG)/receptor activator of nuclear factor-κB (RANK)/RANK ligand system and the Galectin-3/receptor of advanced glycation end products axis. The insight that osteogenesis and vascular calcification share many similarities-and the knowledge that vascular calcification is a cell-mediated active rather than a passive mineralization process-suggest that low BMD and vascular calcification ('vascular ossification') to a large extent represent two sides of the same coin. Here, we briefly review changes of BMD in ESRD as observed using different DXA methods (central and whole-body DXA) at different bone sites for BMD measurements, and summarize recent knowledge regarding the relationships between 'low BMD' and 'fracture incidence, vascular calcification and increased mortality' in ESRD patients, as well as potential 'molecular mechanisms' underlying these associations.

Osteoprotegerin promotes intimal hyperplasia and contributes to in-stent restenosis: Role of an αVβ3/FAK dependent YAP pathway

OBJECTIVE

Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) are related to in-stent-restenosis (ISR) following percutaneous coronary intervention (PCI). Osteoprotegerin (OPG) has been implicated in various vascular diseases. However, the effects of OPG on ISR and the underlying mechanism remained elusive. We here investigated the association between OPG and ISR, and to demonstrate the role and potential mechanisms of OPG in neointimal hyperplasia.

APPROACH AND RESULTS

From 2962 patients who received coronary angiography and follow-up coronary angiography at approximately one year, 291 patients were diagnosed with ISR, and another 291 gender- and age- matched patients without ISR were selected as controls. Serum OPG levels were significantly increased in patients with ISR. Multivariable logistic regression analysis indicated that OPG level was independently associated with the increased risk of ISR. In a mouse femoral artery wire injury model, upregulated OPG was evidenced in vascular tissue after injury. OPG deletion attenuated the vascular injury-induced neointimal hyperplasia and related gene expression in mice. OPG promoted neointimal hyperplasia and human aortic smooth muscle cell (hASMC) proliferation and migration through activation of yes-associated protein (YAP), a major downstream effector of the Hippo signaling pathway, whereas knockdown or inhibition of YAP in hASMCs blunted OPG-induced above effects. Moreover, we found that OPG, as a ligand for integrin αVβ3, mediated phosphorylation of focal adhesion kinase (FAK) and actin cytoskeleton reorganization, resulting in YAP dephosphorylation in hASMCs. OPG-dependent YAP and VSMC activation was prevented by treatment with αVβ3-blocking antibodies and inhibitors of FAK and actin stress fibers.

CONCLUSIONS

Increased serum OPG levels are associated with increased risk of ISR following PCI and OPG could promote neointimal hyperplasia in response to injury through integrin αVβ3 mediated FAK and YAP activation, indicating OPG/YAP inhibition might serve as an attractive novel target for the prevention of ISR after PCI.

Cardiovascular disease in systemic lupus erythematosus: an update

PURPOSE OF REVIEW

The mechanisms leading to the development of premature atherosclerosis and vascular injury in systemic lupus erythematosus (SLE) remain to be fully elucidated. This is a comprehensive review of recent research developments related to the understanding of cardiovascular disease (CVD) in lupus.

RECENT FINDINGS

SLE patients with lupus nephritis display significantly increased risk of myocardial infarction and CVD mortality than SLE patients without lupus nephritis. SLE disease-related parameters could be taken into consideration when calculating CVD risks. The type I interferon pathway is detrimental to the vasculature and may contribute to the development of insulin resistance. The level of low-density granulocytes, a distinct subset of proinflammatory neutrophils present in SLE, was independently associated with coronary plaque burden and endothelial dysfunction. Invariant natural killer T cells may promote an atheroprotective effect in SLE patients with asymptomatic atherosclerotic plaques. Oxidized lupus high-density lipoprotein promotes proinflammatory responses in macrophages.

SUMMARY

Recent discoveries have further strengthened the critical role of SLE-related immune dysregulation and metabolic disturbances in promoting accelerated CVD. Understanding how these pathogenic factors promote vascular injury may provide better molecular candidates for therapeutic targeting, and ultimately to improve CVD outcomes.

Plasma Osteoprotegerin Correlates with Stroke Severity and the Occurrence of Microembolic Signals in Patients with Acute Ischemic Stroke

Background

Instability of atherosclerotic plaques is associated with the occurrence of stroke. Microembolic signals (MESs) are an indicator of unstable plaque. A relationship between plasma osteoprotegerin (OPG) and ischemic stroke has already been identified. The aim of this study was to investigate whether plasma OPG levels have a relationship with MESs and to evaluate the feasibility of OPG as a biomarker of stroke severity and occurrence of MESs.

Methods

Our study consisted of 127 patients with large artery atherosclerosis stroke and 56 controls. Patients were classified into subgroups based on stroke severity and the occurrence of MESs. MES-monitoring was performed for 60 min using transcranial Doppler within 72 h of stroke onset. Stroke severity at admission was assessed by the National Institutes of Health Stroke Scale.

Results

Plasma OPG levels were significantly associated with stroke, MESs, and stroke severity at admission (adjusted OR [95% CI]: 1.002 [1.001–1.003] p < 0.001; 1.002 [1.001–1.003] p = 0.001; 1.001 [1.000–1.002] p = 0.028). When plasma OPG levels were used to determine the stroke severity, the area under the receiver-operating characteristic curve (AUC) was 0.734 (95% CI: 0.625-0.843) based on a cutoff value of 1998.44 pg/ml; the sensitivity and specificity of this test were 80.6% and 65.6%, respectively. Furthermore, when the levels of OPG were used to distinguish the presence of MESs, the AUC was 0.766 (95% CI: 0.672-0.860); the cutoff value was 2107.91 pg/ml. The sensitivity of this cutoff value was 68.8% and the specificity was 73.7%.

Conclusions

Plasma OPG levels correlate with stroke severity and the occurrence of MESs.

Serum osteopontin negatively impacts on intima-media thickness in patients with systemic lupus erythematosus

BACKGROUND

Ultrasound evaluation of carotid intima-media thickness (cIMT) has been extensively used for potentially improving cardiovascular (CV) risk stratification in several patients' categories. Subjects with systemic lupus erythematosus (SLE) have been investigated by both imaging and molecular biomarker approaches with contrasting results. Here, we focused on the role of osteopontin (OPN) as biomarker of subclinical atherosclerosis associated with SLE.

MATERIALS AND METHODS

Eighty females (age 18-65 years) affected by SLE and eighty age-matched healthy female controls without a clinical history of CV disease underwent ultrasound evaluation of cIMT and blood sample assay of high-sensitivity C-reactive protein (hs-CRP) and OPN.

RESULTS

Healthy controls and SLE patients significantly differed for CV risk factors (ie, waist circumference, hypertension and dyslipidaemia) and the inflammatory status. Noteworthy, an opposite association between cIMT and OPN was observed in the two study groups. Whereas OPN was positively associated with mean cIMT (r = 0.364; P = 0.001) in SLE patients, a negative correlation was found in healthy controls. Furthermore, in SLE patients increased circulating levels of OPN were associated with the use of hydroxychloroquine and the positivity for the anti-dsDNA autoantibodies. At linear regression analysis, only OPN remained independently associated with cIMT also after adjustment for age, smoking pack-year, Heart SCORE, disease length and steroid therapy length.

CONCLUSIONS

These results indicate that serum OPN levels were strongly associated with subclinical atherosclerosis in patients with LES and it might be a useful CV biomarker that requires additional validation in larger trials.

[Osteoprotegerin is a new marker of cardiovascular diseases]

Osteoprotegerin (OPG) is a glycoprotein that is a representative of the tumor necrosis factor-α receptor superfamily. Information about the possible role of OPG in the development of cardiovascular diseases has begun to appear in the literature in recent years. This review discusses the role of increasing the level of OPG in the development and progression of atherosclerosis and as a consequence of coronary heart disease and chronic heart failure.

Deletion of Osteopontin Enhances β₂-Adrenergic Receptor-Dependent Anti-Fibrotic Signaling in Cardiomyocytes

Cardiac β₂-adrenergic receptors (ARs) are known to inhibit collagen production and fibrosis in cardiac fibroblasts and myocytes. The β₂AR is a Gs protein-coupled receptor (GPCR) and, upon its activation, stimulates the generation of cyclic 3′,5′-adenosine monophosphate (cAMP). cAMP has two effectors: protein kinase A (PKA) and the exchange protein directly activated by cAMP (Epac). Epac1 has been shown to inhibit cardiac fibroblast activation and fibrosis. Osteopontin (OPN) is a ubiquitous pro-inflammatory cytokine, which also mediates fibrosis in several tissues, including the heart. OPN underlies several cardiovascular pathologies, including atherosclerosis and cardiac adverse remodeling. We found that the cardiotoxic hormone aldosterone transcriptionally upregulates OPN in H9c2 rat cardiac myoblasts—an effect prevented by endogenous β₂AR activation. Additionally, CRISPR-mediated OPN deletion enhanced cAMP generation in response to both β₁AR and β₂AR activation in H9c2 cardiomyocytes, leading to the upregulation of Epac1 protein levels. These effects rendered β₂AR stimulation capable of completely abrogating transforming growth factor (TGF)-β-dependent fibrosis in OPN-lacking H9c2 cardiomyocytes. Finally, OPN interacted constitutively with G_αs subunits in H9c2 cardiac cells. Thus, we uncovered a direct inhibitory role of OPN in cardiac β₂AR anti-fibrotic signaling via cAMP/Epac1. OPN blockade could be of value in the treatment and/or prevention of cardiac fibrosis.

Comparative Study of Protein Expression Levels of Five Plaque Biomarkers and Relation with Carotid Plaque Type Classification in Patients after Carotid Endarterectomy

Atherosclerosis is an inflammatory process resulting in local plaque deposition in the vessel wall of arteries with symptoms to various areas of vascular tree. Identification of patients with progressive advanced atherosclerotic disease is mainly based on the known characteristics of the vulnerable or recently ruptured plaque. Molecular and cellular features associated with the vulnerable plaque are considered potential diagnostic markers for plaque rupture and thrombosis. Here, protein expression levels of the metalloproteases MMP-1, MMP-9, osteopontin (OPN), and cytokines TNFα and IL-6 in tissue extracts of carotid plaques in patients after endarterectomy were estimated by Western immunoblotting, after SDS-PAGE analysis and evaluated based on the ultrasonographic plaque morphology. The gender and age effect was also examined. MMP-1, MMP-9, and IL-6 were expressed in higher levels compared to OPN and TNFa as well as in symptomatic (with type II and III carotid plaque classification) than asymptomatic (type IV) patients with differences considered statistically significant (P values <0.05). A significant positive correlation between MMP-1 and IL-6 (with Pearson correlation coefficient 0.748) is also notable. The data give further insight into the possible role of specific biomarker and enhance the need for further studies in order to clarify the proper one(s) for detection of the vulnerable plaque and help identify patients at risk for cardiovascular events.

Carotid intima media thickness and associations with serum osteoprotegerin and s-RANKL in children and adolescents with type 1 diabetes mellitus with increased risk for endothelial dysfunction

Background Although carotid intima media thickness (CIMT) is an established marker of endothelial dysfunction, limited data exist on relative laboratory biomarkers in youngsters with type 1 diabetes mellitus (T1DM). Our aim was to study CIMT and the biomarkers of the osteoprotegerin (OPG)/RANKL system in young T1DM patients and controls, and also in subgroups of patients with increased risk for endothelial dysfunction, such as those with overweight/obesity, poor metabolic control or the presence of microalbuminuria. Methods CIMT and OPG/RANKL of 56 T1DM children and adolescents were compared to 28 healthy controls. Results Anthropometric, laboratory, CIMT and OPG/RANKL measurements were similar between patients and controls. Overweight/obese patients had greater CIMT than the normal weight ones (0.50 vs. 0.44 mm, p=0.001). Microalbuminuric patients had greater CIMT (0.49 vs. 0.44 mm, p=0.035) than the normoalbuminuric ones, with no difference in terms of OPG/RANKL. In the microalbuminuric group, OPG (r=-0.90, p=0.036) and RANKL (r=-0.92, p=0.024) were significantly negatively associated with CIMT. Following linear regression analysis, in the total patients group, microalbuminuria was the only factor significantly associated with CIMT (beta±SE: 0.050±0.021, p=0.035), body mass index (BMI)-z-scores were negatively associated with OPG (beta±SE: -0.25±0.12, p=0.05), while in the microalbuminuric group, CIMT was negatively associated with OPG (beta±SE: -0.070±0.019, p=0.036). During the forward stepwise procedure, microalbuminuria and age were the only variables negatively associated with RANKL (b=-0.334, p=0.034, b=-35.95, p=0.013, respectively). Conclusions In T1DM pediatric patients, overweight/obesity and microalbuminuria were associated with greater CIMT and with impaired OPG/RANKL levels, as biochemical indices of calcification of the atherosclerotic plaque.

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.

Specific matrix metalloproteinases and calcification factors are associated with the vulnerability of human carotid plaque

The rupture of atherosclerotic plaque provokes the majority of acute cerebrovascular events. Studies have demonstrated that various matrix metalloproteinases (MMPs) may promote atherosclerotic plaque progression and rupture. However, results have been incongruous and the mechanisms of this remain obscured. Therefore, in the current study, carotid plaques were characterized by assessing the levels of MMPs and calcification factors, and evaluating their association with plaque vulnerability. Human carotid plaques were obtained from carotid endarterectomies, and classified into stable and vulnerable groups by ultrasonography and histological analyses. The mRNA and protein levels of MMPs, vascular endothelial growth factor (VEGF), bone sialoprotein 2 (BSP) and osteopontin were investigated by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. Immunohistochemistry was used to localize MMP-2 and MMP-14 in stable and vulnerable plaques. The activation of various associated signaling pathways was also investigated using western blotting. The mRNA levels of MMP-2, -7, -9 and -14 were elevated in vulnerable plaques, among which expression of MMP-2 and -14 were the highest. Consistent with the mRNA levels, the protein levels of MMP-2 and -14 were also elevated. Immunohistochemistry also demonstrated positive staining of MMP-2 and MMP-14 in vulnerable plaques. Factors that indicate neovascularization and calcification, including VEGF and BSP, were concurrently elevated in vulnerable plaques. In addition, the protein levels of extracellular regulated kinase (ERK) and protein kinase C (PKC) were upregulated in vulnerable plaques. The current study provides novel insights into the MMP profiles of vulnerability plaques, and may assist in the development of novel methods for the diagnosis of plaque vulnerability and the prevention of plaque rupture.

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.

Prognostic significance of arterial stiffness and osteoprotegerin in patients with stable coronary artery disease

BACKGROUND

Arterial stiffness and vascular calcification significantly contribute to coronary atherosclerosis progression. The prognostic value of increased arterial stiffness and vascular calcification in subjects with stable coronary artery disease (CAD) after percutaneous coronary intervention(PCI) is currently under question.

MATERIALS AND METHODS

We randomly enrolled 262 patients with stable CAD 1 month after successful PCI. Carotid-femoral pulse wave velocity (PWV) was measured as a well-established index of central aortic stiffness. Osteoprotegerin (OPG) plasma levels were measured as a biomarker of vascular calcification. Patients were followed up prospectively up to 52 months. The primary endpoint was the composite of death from cardiovascular causes, myocardial infarction, stroke or hospitalization for cardiovascular causes.

RESULTS

During the follow-up period, 48 patients presented the primary composite endpoint. Subjects who presented the primary endpoint, compared to subjects free of cardiovascular events, had significantly increased PWV (9.45 ± 2.19 m/s vs 8.73 ± 2.07 m/s, P = .04) and OPG levels (4.21 ± 2.19 pmol/L vs 3.18 ± 1.74 pmol/L, P = .003). Survival analysis indicated that PWV predicted adverse cardiac events MACE (Hazard ratio = 1.29 95%CI: 1.07-1.57, P = .008) independently from confounders such as age, sex, smoking habits, ejection fraction, extent of coronary artery disease, hypertension and diabetes mellitus. Interestingly, for every increase in pulse wave velocity by 1 m/s, there is an anticipated increase in the risk of major adverse cardiovascular event (MACE) by 29%.

CONCLUSIONS

These findings extend the current knowledge concerning the role of arterial stiffness as powerful biomarkers in cardiovascular disease. Measurement of PWV might have a role in ascertaining prognosis and managing treatment in patients with stable CAD after PCI.

Osteopontin may be a driver of abdominal aortic aneurysm formation

OBJECTIVE

Previous in vitro and animal studies have suggested that osteopontin (OPN), an inflammatory extracellular matrix protein, is involved in the formation and growth of abdominal aortic aneurysms (AAAs). However, the mechanism by which this occurs continues to be nebulous. The relationship between OPN and inflammation-suppressing lymphocytes present in the human AAA condition was investigated and presented herein.

METHODS

Serum OPN concentrations were measured in healthy, risk factor-matched non-AAA and AAA patients by enzyme-linked immunosorbent assay (ELISA). Immunohistochemistry was used to determine the source of OPN secretion using aortic tissue collected from multiorgan donors and AAA patients undergoing open surgical repair. Vascular smooth muscle cells (VSMCs) were exposed to various inflammatory mediators, and OPN expression was evaluated by quantitative reverse transcriptase-polymerase chain reaction and ELISA. The inflammatory nature of OPN and the aortic wall was determined using a TR1 suppressor cell induction assay as a surrogate and characterized by ELISA and fluorescence-activated cell sorting.

RESULTS

OPN was found to be elevated in both the plasma and aortic homogenate of AAA patients compared with controls. On immunohistochemistry, OPN localized to the tunica media of the diseased aorta but was minimally expressed in healthy aorta. In vitro, cigarette smoke extract was the most potent stimulator of OPN secretion by VSMCs and increased both messenger RNA and supernatant concentrations. OPN demonstrated an ability to inhibit the induction of interleukin 10-secreting TR1 lymphocytes, a depleted population in the AAA patient, from naive precursors. Last, neutralizing receptor targets of OPN in the setting of AAA homogenate coincubation abrogated the inhibition of TR1 induction.

CONCLUSIONS

OPN, secreted by the VSMCs of the tunica media, is elevated in the circulating plasma and aortic wall of patients with AAA. It can inhibit the induction of the TR1 suppressor cell, leading to an overall proinflammatory state contributing to progressive aortic wall breakdown and dilation.

Osteoprotegerin rich tumor microenvironment: implications in breast cancer

Osteoprotegerin (OPG) is a soluble decoy receptor for tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL). It belongs to the tumor necrosis factor receptor superfamily (TNFRSF). OPG was initially discovered to contribute to homeostasis of bone turnover due to its capability of binding to receptor activator of nuclear factor-kappaB (NF-kB). However, apart from bone turnover, OPG plays important and diverse role(s) in many biological functions. Besides having anti-osteoclastic activity, OPG is thought to exert a protective anti-apoptotic action in OPG-expressing tumors by overcoming the physiologic mechanism of tumor surveillance exerted by TRAIL. Along with inhibiting TRAIL induced apoptosis, it can induce proliferation by binding to various cell surface receptors and thus turning on the canonical cell survival and proliferative pathways. OPG also induces angiogenesis, one of the hallmarks of cancer, thus facilitating tumor growth. Recently, the understanding of OPG and its different roles has been augmented substantially. This review is aimed at providing a very informative overview as to how OPG affects cancer progression especially breast cancer.

Osteoprotegerin concentration is associated with the presence and severity of peripheral arterial disease in type 2 diabetes mellitus

BACKGROUND

Osteoprotegerin plays a role in the development of several bone diseases. In addition, osteoprotegerin may contribute to the development of vascular disease. Little is known about the association between serum osteoprotegerin levels and the presence or severity of peripheral arterial disease (PAD). The aim of this study was to examine the association between serum osteoprotegerin levels and both the presence as well as the severity of lower extremity arterial disease in patients with type 2 diabetes (T2DM).

PATIENTS AND METHODS

The study included 165 consecutive patients with T2DM (57 % males, mean age 65.0 ± 0.7 years). PAD was diagnosed by measurement of the toe-brachial index (TBI). Serum osteoprotegerin was measured using ELISA.

RESULTS

The mean osteoprotegerin level was significantly higher in patients with PAD in comparison to patients without PAD (18.2 ± 1.0 vs. 13.1 ± 2.0 pmol/L, p = 0.014). Significant univariate correlations between TBI and osteoprotegerin level (r = -0.308; p < 0.001), age, body mass index, and HDL cholesterol were observed. In the multivariate linear regression analysis, serum osteoprotegerin (β = -0.005; p = 0.020), higher age, and male gender were significant predictors of TBI. When 25(OH) vitamin D was introduced into the mentioned model, OPG was no longer a significant predictor of TBI and was replaced in the model with vitamin D (β = 0.009, p = 0.001). This finding suggests a role of OPG as a mediator of the effects of 25(OH) vitamin D.

CONCLUSIONS

Serum osteoprotegerin level is significantly associated with both the presence and severity of PAD in patients with T2D. Osteoprotegerin might be a biomarker for the presence of atherosclerotic disease in patients with T2DM.

Beyond Antibodies: B Cells and the OPG/RANK-RANKL Pathway in Health, Non-HIV Disease and HIV-Induced Bone Loss

HIV infection leads to severe B cell dysfunction, which manifests as impaired humoral immune response to infection and vaccinations and is not completely reversed by otherwise effective antiretroviral therapy (ART). Despite its inability to correct HIV-induced B cell dysfunction, ART has led to significantly increased lifespans in people living with HIV/AIDS. This has in turn led to escalating prevalence of non-AIDS complications in aging HIV-infected individuals, including malignancies, cardiovascular disease, bone disease, and other end-organ damage. These complications, typically associated with aging, are a significant cause of morbidity and mortality and occur significantly earlier in HIV-infected individuals. Understanding the pathophysiology of these comorbidities and delineating clinical management strategies and potential cures is gaining in importance. Bone loss and osteoporosis, which lead to increase in fragility fracture prevalence, have in recent years emerged as important non-AIDS comorbidities in patients with chronic HIV infection. Interestingly, ART exacerbates bone loss, particularly within the first couple of years following initiation. The mechanisms underlying HIV-induced bone loss are multifactorial and complicated by the fact that HIV infection is linked to multiple risk factors for osteoporosis and fracture, but a very interesting role for B cells in HIV-induced bone loss has recently emerged. Although best known for their important antibody-producing capabilities, B cells also produce two cytokines critical for bone metabolism: the key osteoclastogenic cytokine receptor activator of NF-κB ligand (RANKL) and its physiological inhibitor osteoprotegerin (OPG). Dysregulated B cell production of OPG and RANKL was shown to be a major contributor to increased bone loss and fracture risk in animal models and HIV-infected humans. This review will summarize our current knowledge of the role of the OPG/RANK–RANKL pathway in B cells in health and disease, and the contribution of B cells to HIV-induced bone loss. Data from mouse studies indicate that RANKL and OPG may also play a role in B cell function and the implications of these findings for human B cell biology, as well as therapeutic strategies targeting the OPG/RANK–RANKL pathway, will be discussed.

Association of Osteopontin, Neopterin, and Myeloperoxidase With Stroke Risk in Patients With Prior Stroke or Transient Ischemic Attacks: Results of an Analysis of 13 Biomarkers From the Stroke Prevention by Aggressive Reduction in Cholesterol Levels Trial

BACKGROUND AND PURPOSE

Established risk factors do not fully identify patients at risk for recurrent stroke. The SPARCL trial (Stroke Prevention by Aggressive Reduction in Cholesterol Levels) evaluated the effect of atorvastatin on stroke risk in patients with a recent stroke or transient ischemic attack and no known coronary heart disease. This analysis explored the relationships between 13 plasma biomarkers assessed at trial enrollment and the occurrence of outcome strokes.

METHODS

We conducted a case-cohort study of 2176 participants; 562 had outcome strokes and 1614 were selected randomly from those without outcome strokes. Time to stroke was evaluated by Cox proportional hazards models.

RESULTS

There was no association between time to stroke and lipoprotein-associated phospholipase A₂, monocyte chemoattractant protein-1, resistin, matrix metalloproteinase-9, N-terminal fragment of pro-B-type natriuretic peptide, soluble vascular cell adhesion molecule-1, soluble intercellular adhesion molecule-1, or soluble CD40 ligand. In adjusted analyses, osteopontin (hazard ratio per SD change, 1.362; P<0.0001), neopterin (hazard ratio, 1.137; P=0.0107), myeloperoxidase (hazard ratio, 1.177; P=0.0022), and adiponectin (hazard ratio, 1.207; P=0.0013) were independently associated with outcome strokes. After adjustment for the Stroke Prognostic Instrument-II and treatment, osteopontin, neopterin, and myeloperoxidase remained independently associated with outcome strokes. The addition of these 3 biomarkers to Stroke Prognostic Instrument-II increased the area under the receiver operating characteristic curve by 0.023 (P=0.015) and yielded a continuous net reclassification improvement (29.1%; P<0.0001) and an integrated discrimination improvement (42.3%; P<0.0001).

CONCLUSIONS

Osteopontin, neopterin, and myeloperoxidase were independently associated with the risk of recurrent stroke and improved risk classification when added to a clinical risk algorithm.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique Identifier: NCT00147602.

Osteoprotegerin concentration and risk of cardiovascular outcomes in nine general population studies: Literature-based meta-analysis involving 26,442 participants

Background

Recent experimental and epidemiological studies have suggested that osteoprotegerin, a key regulator in bone metabolism, may be involved in vascular calcification and atherosclerosis. Our aim was to reliably quantify the associations of osteoprotegerin concentration and incidence of first-ever cardiovascular disease outcomes in the general population.

Methods

Using the electronic databases MEDLINE, EMBASE and Web of Science (January 1975 and April 2017, no language restrictions), nine relevant studies were identified involving a total of 26,442 participants recruited from the general population. Over a mean follow-up of 8.5 years, 2,160 cardiovascular disease, 2,123 coronary heart disease, and 1,102 stroke outcomes were recorded. Study-specific risk ratios were combined with random-effects meta-analysis.

Results

When comparing individuals in the top with those in the bottom third of osteoprotegerin concentration, the combined risk ratio was 1.83 (95% confidence interval: 1.46, 2.30; P<0.001; I² = 76.8%) for cardiovascular disease, 1.72 for coronary heart disease (1.26, 2.37; P = 0.001; I² = 83.5%), and 1.58 for stroke (1.18, 2.12; P = 0.002; I² = 65.2%). Associations appeared stronger at younger age (P = 0.018 for cardiovascular disease), in studies that did not employ statistical adjustment (P = 0.023 for cardiovascular disease and 0.018 for coronary heart disease), and potentially in studies that measured osteoprotegerin in plasma rather than in serum (P = 0.005 for cardiovascular disease and 0.018 for coronary heart disease). Magnitudes of associations did not differ according to the proportion of males, geographical region, or osteoprotegerin assay manufacturer. There was no evidence for publication bias for any of the outcomes assessed (all P>0.05).

Conclusions

Elevated osteoprotegerin concentration is associated with an increased risk of incident cardiovascular disease in the general population. The mechanisms underlying this observation deserve further investigation.

Urinary Osteopontin Predicts Incident Chronic Kidney Disease, while Plasma Osteopontin Predicts Cardiovascular Death in Elderly Men

BACKGROUND AND OBJECTIVES

The matricellular protein osteopontin is involved in the pathogenesis of both kidney and cardiovascular disease. However, whether circulating and urinary osteopontin levels are associated with the risk of these diseases is less studied.

DESIGN SETTING PARTICIPANTS AND MEASUREMENTS

A community-based cohort of elderly men (Uppsala Longitudinal Study of Adult Men [ULSAM]; n = 741; mean age: 77 years) was used to study the associations between plasma and urinary osteopontin, incident chronic kidney disease, and the risk of cardiovascular death during a median of 8 years of follow-up.

RESULTS

There was no significant cross-sectional correlation between plasma and urinary osteopontin (Spearman ρ = 0.07, p = 0.13). Higher urinary osteopontin, but not plasma osteopontin, was associated with incident chronic kidney disease in multivariable models adjusted for age, cardiovascular risk factors, baseline glomerular filtration rate, urinary albumin/creatinine ratio, and the inflammatory markers interleukin 6 and high-sensitivity C-reactive protein (odds ratio for 1 standard deviation [SD] of urinary osteopontin, 1.42, 95% CI 1.00-2.02, p = 0.048). Conversely, plasma osteopontin, but not urinary osteopontin, was independently associated with cardiovascular death (multivariable hazard ratio per SD increase, 1.35, 95% CI 1.14-1.58, p < 0.001, and 1.00, 95% CI 0.79-1.26, p = 0.99, respectively). The addition of plasma osteopontin to a model with established cardiovascular risk factors significantly increased the C-statistics for the prediction of cardiovascular death (p < 0.002).

CONCLUSIONS

Higher urinary osteopontin specifically predicts incident chronic kidney disease, while plasma osteopontin specifically predicts cardiovascular death. Our data put forward osteopontin as an important factor in the detrimental interplay between the kidney and the cardiovascular system. The clinical implications, and why plasma and urinary osteopontin mirror different pathologies, remain to be established.

Research Progress on the Risk Factors and Outcomes of Human Carotid Atherosclerotic Plaques

Objective:

Atherosclerosis is an inflammatory process that results in complex lesions or plaques that protrude into the arterial lumen. Carotid atherosclerotic plaque rupture, with distal atheromatous debris embolization, causes cerebrovascular events. This review aimed to explore research progress on the risk factors and outcomes of human carotid atherosclerotic plaques, and the molecular and cellular mechanisms of human carotid atherosclerotic plaque vulnerability for therapeutic intervention.

Data Sources:

We searched the PubMed database for recently published research articles up to June 2016, with the key words of “risk factors”, “outcomes”, “blood components”, “molecular mechanisms”, “cellular mechanisms”, and “human carotid atherosclerotic plaques”.

Study Selection:

The articles, regarding the latest developments related to the risk factors and outcomes, atherosclerotic plaque composition, blood components, and consequences of human carotid atherosclerotic plaques, and the molecular and cellular mechanisms of human carotid atherosclerotic plaque vulnerability for therapeutic intervention, were selected.

Results:

This review described the latest researches regarding the interactive effects of both traditional and novel risk factors for human carotid atherosclerotic plaques, novel insights into human carotid atherosclerotic plaque composition and blood components, and consequences of human carotid atherosclerotic plaque.

Conclusion:

Carotid plaque biology and serologic biomarkers of vulnerability can be used to predict the risk of cerebrovascular events. Furthermore, plaque composition, rather than lesion burden, seems to most predict rupture and subsequent thrombosis.

Hairy/enhancer of Split Homologue-1 Suppresses Vascular Endothelial Growth Factor-induced Angiogenesis via Downregulation of Osteopontin Expression

Angiogenesis plays a critical role in the progression and vulnerability of atherosclerotic plaques; however, the orchestration of angiogenesis in atherosclerotic plaque formation remains unclear. The results of microarray analysis, real-time PCR and immunohistochemical analyses showed that Hairy/enhancer of split homologue-1 (Hes-1) expression was significantly decreased, while that of osteopontin (OPN) was increased, in atherosclerotic plaques. Meanwhile, immunofluorescence results demonstrated that both Hes-1 and OPN were expressed in endothelial cells (ECs) of neovessels in atherosclerotic plaques. The results of an in vitro study showed that Hes-1 was downregulated, while OPN was upregulated, in a time- and dose-dependent manner in human umbilical vein endothelial cells (HUVECs) by VEGF treatment. In addition, Hes-1 knockdown was found to have transcriptional promotion effect on OPN expression in HUVECs and enhance OPN-induced angiogenesis in response to VEGF. On the contrary, Hes-1 overexpression inhibited OPN expression in HUVECs and reduced angiogenesis in vitro and in vivo. The results of this study suggest that decreased Hes-1 expression in atherosclerotic plaques exaggerate VEGF-induced angiogenesis by upregulating OPN. Therefore, restoring Hes-1 expression and inhibiting OPN expression may be a promising strategy to prevent vulnerable plaque formation in patients with atherosclerosis.

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.

Fenofibrate in the management of AbdoMinal aortic anEurysm (FAME): study protocol for a randomised controlled trial

Background

Abdominal aortic aneurysm (AAA) is a slowly progressive destructive process of the main abdominal artery. Experimental studies indicate that fibrates exert beneficial effects on AAAs by mechanisms involving both serum lipid modification and favourable changes to the AAA wall.

Methods/design

Fenofibrate in the management of AbdoMinal aortic anEurysm (FAME) is a multicentre, randomised, double-blind, placebo-controlled clinical trial to assess the effect of orally administered therapy with fenofibrate on key pathological markers of AAA in patients undergoing open AAA repair. A total of 42 participants scheduled for an elective open AAA repair will be randomly assigned to either 145 mg of fenofibrate per day or identical placebo for a minimum period of 2 weeks prior to surgery. Primary outcome measures will be macrophage number and osteopontin (OPN) concentration within the AAA wall as well as serum concentrations of OPN. Secondary outcome measures will include levels of matrix metalloproteinases and proinflammatory cytokines within the AAA wall, periaortic fat and intramural thrombus and circulating concentrations of AAA biomarkers.

Discussion

At present, there is no recognised medical therapy to limit AAA progression. The FAME trial aims to assess the ability of fenofibrate to alter tissue markers of AAA pathology.

Trial registration

Australian New Zealand Clinical Trials Registry, ACTRN12612001226897. Registered on 20 November 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-016-1752-z) contains supplementary material, which is available to authorized users.

Serum osteoprotegerin and renal function in the general population: the Tromsø Study

Background

Serum osteoprotegerin (OPG) is elevated in patients with chronic kidney disease (CKD) and increases with decreasing renal function. However, there are limited data regarding the association between OPG and renal function in the general population. The aim of the present study was to explore the relation between serum OPG and renal function in subjects recruited from the general population.

Methods

We conducted a cross-sectional study with 6689 participants recruited from the general population in Tromsø, Norway. Estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration equations. OPG was modelled both as a continuous and categorical variable. General linear models and linear regression with adjustment for possible confounders were used to study the association between OPG and eGFR. Analyses were stratified by the median age, as serum OPG and age displayed a significant interaction on eGFR.

Results

In participants ≤62.2 years with normal renal function (eGFR ≥90 mL/min/1.73 m²) eGFR increased by 0.35 mL/min/1.73 m² (95% CI 0.13–0.56) per 1 standard deviation (SD) increase in serum OPG after multiple adjustment. In participants older than the median age with impaired renal function (eGFR <90 mL/min/1.73 m²), eGFR decreased by 1.54 (95% CI −2.06 to −1.01) per 1 SD increase in serum OPG.

Conclusions

OPG was associated with an increased eGFR in younger subjects with normal renal function and with a decreased eGFR in older subjects with reduced renal function. Our findings imply that the association between OPG and eGFR varies with age and renal function.

Plasma Osteopontin Levels and Adverse Cardiovascular Outcomes in the PEACE Trial

Osteopontin (OPN) is a secreted glycophosphoprotein that has a role in inflammation, immune response and calcification. We hypothesized that plasma OPN levels are associated with adverse cardiovascular outcomes in patients with stable coronary artery disease (CAD) and preserved ejection fraction (EF) enrolled in the PEACE trial. We measured plasma OPN levels at baseline in 3567 CAD patients (mean age 64.5 ± 8.1 years, 81% men) by a sandwich chemiluminescent assay (coefficient of variation = 4.1%). OPN levels were natural log (Ln) transformed prior to analyses. We assessed whether Ln OPN levels were associated with the composite primary endpoint of cardiovascular death, non-fatal myocardial infarction and hospitalization for heart failure using multiple event multivariable Cox proportional hazards regression. Adjustment was performed for: (a) age and sex; (b) additional potential confounders; and (c) a parsimonious set of statistically significant 10 variates. During a median follow-up of 4.8 years, 416 adverse cardiovascular outcomes occurred in 366 patients. Ln OPN was significantly associated with the primary endpoint; HR (95% CI) = 1.56 (1.27, 1.92); P <0.001, and remained significant after adjustment for age and sex [1.31 (1.06, 1.61); P = 0.01] and after adjustment for relevant covariates [1.24 (1.01, 1.52); P = 0.04]. In a secondary analysis of the individual event types, Ln OPN was significantly associated with incident hospitalization for heart failure: HR (95% CI) = 2.04 (1.44, 2.89); P <0.001, even after adjustment for age, sex and additional relevant covariates. In conclusion, in patients with stable CAD and preserved EF on optimal medical therapy, plasma OPN levels were independently associated with the composite incident endpoint of adverse cardiovascular outcomes as well as incident hospitalization for heart failure.