Coronary artery calcification and cardiovascular risk: the role of RANKL/OPG signalling

Fibroblast growth factor 23 and 25(OH)D levels are related to abdominal obesity and cardiovascular risk in patients with polycystic ovarian syndrome

Fibroblast growth factor 23 (FGF23) and Klotho are extensively studied in relation to bone metabolism and progression of chronic kidney disease. There is very limited information about their role in polycystic ovarian syndrome (PCOS). The aim of the present study was to investigate some bone markers in women with PCOS in relation to obesity and cardiovascular risk. In the study were included 80 patients, divided into three age-matched groups -Non-obese PCOS (n = 40); Obese PCOS (n = 20) and Obese control group (n = 20). Bone marker levels were measured by an enzyme-linked immunosorbent assay. Obese PCOS patients had higher levels of FGF23 and sRANKL, lower levels of 25(OH)D and higher prevalence of vitamin D deficiency compared to non-obese subjects. Patients with abdominal obesity (waist circumference >80 cm) independently of PCOS status had significantly higher levels of FGF23 (112.5 ± 86.5 vs. 73.4 ± 37.9 pg/ml; p = .023) and lower of 25(OH)D (35.8 ± 21.4 vs 47.8 ± 26.5 nmol/l; p = .034). Patients with PCOS at risk of cardiovascular diseases according to AE-PCOS consensus also had increased levels of FGF23 (111.6 ± 84.5 vs. 66.5 ± 35.1 pg/ml; p = .031) and decreased levels of 25(OH)D (31.9 ± 16.8 vs. 47.1 vs 28.4 nmol/l; p = .017) compared to those not at risk. There was no correlation between bone markers and blood glucose levels, insulin resistance or hormonal levels.

Association between fetuin-A and prognosis of CAD: A systematic review and meta-analysis

BACKGROUND

Fetuin-A is an anti-inflammation and anti-calcification factor involved in the course of coronary artery disease (CAD). But the association between serum fetuin-A level and the prognosis of CAD patients was still controversial. To clarify the association between serum fetuin-A level and the prognosis of CAD patients, we conducted the present meta-analysis.

METHODS

The included studies should be potentially relevant prospective studies published in English language before January 2019. The target population of the present meta-analysis was restricted to patients with CAD. The results of studies must report hazard ratio (HR) or Kaplan-Meier survival curve for all-cause mortality or incidence of secondary cardiovascular disease (CVD) events. The pooled HRs were analysed by the method of meta-analysis.

RESULTS

A total of four prospective studies, including 4256 participants with CAD disease, were chosen to be included. The pooled HR for all-cause mortality was 0.57 (95% CI: 0.37-0.87), showing a statistically significant association between high serum fetuin-A level and low all-cause mortality in CAD patients. For the incidence of secondary CVD events, the pooled HR was 0.86 (95% CI: 0.60-1.23), indicating no statistically significant association between serum fetuin-A level and incidence of secondary CVD events in CAD patients.

CONCLUSION

High serum fetuin-A level associated with lower all-cause mortality in patients with CAD. No association between serum fetuin-A level and incidence of secondary CVD events was found in patients with CAD.

Osteoprotegerin is Higher in Sepsis Than in Noninfectious SIRS and Predicts 30-Day Mortality of SIRS Patients in the Intensive Care

BACKGROUND

Systemic inflammatory response syndrome (SIRS) is a complex disease involving multiple pathways and organs. Biomarkers reflecting these pathways and organ function could correlate with the severity of the disease. Osteoprotegerin (OPG), mainly known for its role in bone metabolism, is also involved in the immune and vascular system and is therefore an interesting biomarker to study in SIRS patients. In this prospective observational study, we investigated the correlation of plasma OPG concentrations, sepsis, and 30-day mortality of SIRS patients in the intensive care unit (ICU).

METHODS

This observational, single-center, cohort study included 313 consecutive patients admitted to the ICU, with an anticipated stay of more than 48 h and SIRS on admission. Data from included patients were collected daily until discharge or death for a maximum of 10 days. Thirty-day mortality was retrospectively assessed. OPG concentrations were measured in the first 48 h after admission. The relation of OPG with no sepsis, sepsis, and septic shock was assessed with the Kruskal-Wallis test and the Mann-Whitney U-test. Cox proportional hazards regression was used to study OPG concentrations and 30-day mortality.

RESULTS

OPG concentrations were higher in patients with sepsis and septic shock than in patients without sepsis. Furthermore, patients with OPG concentrations in the highest tertile at admission in the ICU have an increased risk of mortality within 30 days when compared to patients with OPG concentrations in the lowest and middle tertiles, independent of acute physiologic and chronic health evaluation (APACHE) and sequential organ failure assessment (SOFA) scores.

CONCLUSIONS

We show that OPG is a biomarker that correlates with sepsis and predicts mortality of SIRS patients in the ICU.

Receptor activator of NF-κB ligand (RANKL) increases the release of neutrophil products associated with coronary vulnerability

The “blood vulnerability”, resulting from the complex balance between serum molecules and inflammatory cell atherosclerotic activities, is a major determinant in the evaluation of the “global patient cardiovascular vulnerability”. In the present study, we focused on the role of the soluble receptor activator of nuclear factor kappa-B (NF-κB) ligand (RANKL, a potential marker of coronary calcification and vulnerability) in the release of neutrophilic proteases. Then, the association between these mediators and the degree of coronary calcification (assessed by coronary calcium score [CCS]) was investigated in 20 subjects (aged ≥65 years) asymptomatic for cardiovascular disease. Results showed that RANKL dose-dependently induced matrix metalloprotease (MMP)-8 and MMP-9 release from human primary neutrophils cultured in Teflon dishes (suspension condition, mimicking cells circulating in the blood stream). Conversely, when adherent to polystyrene, neutrophils became unresponsive to RANKL. RANKL did not influence the release of other neutrophilic products in suspension and adherence cultures as well as neutrophil migration. RANKL-induced release of MMPs was dependent on the activation of defined intracellular signalling pathways (PI3K/Akt and ERK1/2). In asymptomatic subjects, serum levels of RANKL, MMP-8 and MMP-9 positively correlated with CCS, reflecting a potential relationship between circulating RANKL and coronary calcification. In conclusion, RANKL increased the release of neutrophilic products potentially related to the “blood” vulnerability via defined intracellular pathways. Serum levels of RANKL might represent a potential biomarker of coronary calcification and related cardiovascular risk.

Increased phagocytic NADPH oxidase activity associates with coronary artery calcification in asymptomatic men

Vascular calcification is a common feature in atherosclerosis and associates with cardiovascular events. Oxidative stress may be involved in the pathogenesis of vascular calcification. Previous studies have shown that the phagocytic NADPH oxidase is associated with atherosclerosis. The objective of the present study was to investigate the association between phagocytic NADPH oxidase-mediated superoxide production and coronary artery calcium (CAC). NADPH oxidase-mediated superoxide production was determined by chemiluminescence and CAC by computed tomography in 159 asymptomatic men free of overt clinical atherosclerosis. Multivariate linear regression analyses were used to assess the relationship between CAC and NADPH oxidase-mediated superoxide production. Compared with individuals in the lowest score of CAC (= 0 Agatston units), those in the upper score (>400 Agatston units) showed higher superoxide production (p < 0.05). In correlation analysis, superoxide production positively (p < 0.01) correlated with CAC, which in multivariate analysis remained significant after adjusting for age, HDL-cholesterol, triglycerides, body mass index, smoking, arterial hypertension and diabetes mellitus. In conclusion, in a population of men without clinically overt atherosclerotic disease, increased NADPH oxidase-mediated superoxide production associated with enhanced CAC. Albeit descriptive, these findings suggest a potential involvement of phagocytic NADPH oxidase-mediated oxidative stress in CAC.

Biomarkers Associated with Vascular Calcification in Peritoneal Dialysis

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BACKGROUND

Vascular calcification is strongly associated with cardiovascular disease and mortality. However, some factors related to vascular calcification in patients with end-stage renal disease receiving peritoneal dialysis (PD) remain unknown. This study aimed to evaluate the associations of osteoprotegerin (OPG), osteopontin (OPN), osteocalcin (OCN), fibroblast growth factor 23 (FGF-23), magnesium, and phosphate clearance with vascular calcification in PD subjects, assessed by plain radiographs. ♦

METHODS

Simple vascular calcification scores (SVCS) obtained from plain X-rays of the pelvis and hands, and the Kauppila Index (KI) from lateral lumbar X-rays were assessed in 76 adults receiving PD for ≥ 6 months (43 women, median age 39 years, median time on PD 1.4 years). Levels of OPG, OPN, OCN, and FGF-23 were determined by luminometry. ♦

RESULTS

Serum OPG levels were higher in subjects with vascular calcification (n = 22 with SVCS > 3; n = 19 with KI > 7) compared with those with less calcification (p < 0.001). Spearman's correlation coefficients between OPG and SVCS and KI were r = 0.49 and r = 0.51, respectively (both p < 0.001). Subjects with vascular calcification had significantly lower renal phosphate clearance. Multiple regression analysis showed that vascular calcification assessed by SVCS was associated with age (r = 0.2, p = 0.042), diabetes mellitus (r = 2.4, p < 0.001), body mass index (BMI) (r = 0.09, p = 0.037), and OPG (r = 0.22, p = 0.001). Vascular calcification assessed by KI was associated with age (r = 0.16, p < 0.001), time on PD (r = 0.54, p = 0.001) and OPG (r = 0.08, p = 0.04). Osteocalcin, OPN, FGF-23, and magnesium were not associated with vascular calcification. ♦

CONCLUSIONS

Higher levels of OPG were consistently associated with vascular calcification in subjects on PD.

Serum osteopontin levels are upregulated and predict disability after an ischaemic stroke

BACKGROUND

After an acute ischaemic stroke (AIS), several inflammatory biomarkers have been investigated, but their predictive role on functional recovery remains to be validated. Here, we investigated the prognostic relevance of biomarkers related to atherosclerotic plaque calcification, such as osteopontin (OPN), osteoprotegerin (OPG) and the receptor activator of nuclear factor kappa-B ligand (RANKL) in a cohort of patients with AIS (n = 90) during 90-day follow-up.

MATERIALS AND METHODS

Radiological and clinical examinations as well as blood sampling were performed at admission and at days 1, 7 and 90 from the event. Validated scores [such as modified Rankin scale (mRS) and the National Institutes of Health Stroke Scale (NIHSS)] were used to assess poststroke outcome. Serum levels of OPN, OPG and RANKL were measured by colorimetric enzyme-linked immunosorbent assay (ELISA).

RESULTS

When compared to the admission, OPN serum levels increased at day 7. Serum OPN levels at this time point were positively correlated with both ischaemic lesion volume and NIHSS at days 7 and 90. A cut-off of 30.53 ng/mL was identified for serum OPN by receiver operating characteristic (ROC) curve analysis. Adjusted logistic regression showed that serum OPN levels at day 7 predicted worse mRS at day 90 [OR 4.13 (95% CI 1.64-10.36); P = 0.002] and NIHSS [1.49 (95% CI 1.16-1.99); P = 0.007], independently of age, gender, hypertension and thrombolysis.

CONCLUSIONS

Serum levels of OPN, but not OPG and RANKL, peaked at day 7 after AIS and predicted worse neurological scores. Therefore, OPN might have a pathophysiological and clinical relevance after AIS.

The role of osteoprotegerin in cardiovascular disease

Osteoprotegerin (OPG) is a 401 amino acid N-glycosylated protein, which is highly expressed in a large number of tissues. OPG mainly binds to two ligands, i.e. RANKL (receptor activator of nuclear factor κB ligand) and TRAIL (tumor necrosis factor- related apoptosis-inducing ligand). Upon binding to the former ligand, OPG inhibits the activation of osteoclasts and promotes apoptosis of osteoclasts, whereas the binding of OPG with TRAIL prevents apoptosis of tumor cells. There is now emerging evidence that OPG participates in the pathogenesis of atherosclerosis and cardiovascular diseases by amplifying the adverse effects of inflammation and several traditional risk factors such as hyperlipidemia, endothelial dysfunction, diabetes mellitus, and hypertension. Some epidemiological studies also showed a positive association between OPG levels and cardiovascular morbidity and mortality. The aim of this article is to provide an overview of the main biochemical, physiological, and pathological aspects of OPG biology in cardiovascular disease.

An ELISA for the quantitation of von Willebrand factor: osteoprotegerin complexes in plasma

BACKGROUND

Von Willebrand factor (VWF) is pivotal in arterial thrombosis, and osteoprotegerin (OPG) is besides being a bone protein also related to cardiovascular diseases. OPG can bind VWF, but the significance of this interaction is not known.

OBJECTIVES

The aim was to develop an assay for measurement of von Willebrand factor-osteoprotegerin complex (VWF:OPG) in human plasma. Furthermore, the significance of VWF:OPG complex as a marker of cardiovascular disease (CVD) was evaluated.

PATIENTS/METHODS

A sandwich ELISA for quantification of VWF:OPG was developed using a polyclonal rabbit anti-human VWF capturing antibody and a monoclonal anti-human OPG detecting antibody. Samples were quantified relative to a standard curve obtained from dilutions of a plasma pool from healthy individuals. The assay was evaluated in two groups of patients with CVD and two groups of asymptomatic individuals with and without documented coronary calcification (total n=118).

RESULTS AND CONCLUSIONS

The assay detected VWF:OPG complexes in human plasma, while no significant signal was observed when testing solutions containing VWF or recombinant OPG alone. Importantly, the ELISA assay was able to detect in vitro formed complexes between human VWF and recombinant OPG in a dose-dependent manner. There was a large inter-individual variation in plasma VWF:OPG levels, but we found no significant differences in the level of VWF:OPG complexes between the four groups. Thus, we conclude that increasing OPG plasma levels in atherosclerotic CVD are not derived from increased levels of complexed form of VWF and OPG, but are more likely due to increased amounts of OPG secreted into the circulation.

Inflammation, high-density lipoprotein and cardiovascular dysfunction

PURPOSE OF REVIEW

This review describes the evidence that supports the hypothesis that high-density lipoprotein (HDL) is atheroprotective due to its antiinflammatory effects and benefits on vascular health.

RECENT FINDINGS

Recent investigations have shown that HDL may inhibit atherosclerosis by promoting healthy endothelial function and by limiting or inhibiting the activation of macrophage and other immune cells. Receptors for HDL clearly regulate immune system function as well as cellular stress. Recent studies also suggest that participation of HDL in the process of reverse cholesterol transport may inhibit growth factor and cytokine receptor signaling by depleting cholesterol from lipid rafts. However, inflammation can also be associated with circulating dysfunctional HDL, which often possesses both prooxidative and proinflammatory properties.

SUMMARY

These studies suggest that HDL-based therapeutics have potential in treating both acute and chronic conditions associated with inflammation. These studies also reveal several other pathways that may be targeted for therapeutic drug development.

Receptor activator of nuclear factor kappa B ligand/osteoprotegerin pathway is a promising target to reduce atherosclerotic plaque calcification

Atherosclerotic plaque calcification represents a common pathophysiologic process in the advanced phases of the disease. Both inflammatory and vascular cells (such as osteoblast-like cells, osteoclast-like cells, dendritic cells, macrophages, smooth muscle cells, and endothelial cells) are active players in the balance between intraplaque bone deposition and resorption. Inflammatory processes underlying plaque calcification are regulated by soluble mediators that also contribute to plaque destabilization and increased vulnerability. Among different mediators, the receptor activator of nuclear factor-kappa B (NF-kappa B) ligand (RANKL)/osteoprogerin (OPG) system is a major determinant in inflammatory cell differentiation toward osteoclast-like cells. Thus, this system might be a promising parameter to be investigated as a marker of calcification-related cardiovascular risk and a therapeutic target. Despite some promising results, several limitations have been shown in the potential clinical use of serum RANKL/OPG to better assess the cardiovascular risk. At present, the potential relationship between RANKL/OPG and the content of calcium within the intima of the coronary arteries (CAC score, assessed by computed tomography) needs to be explored in large clinical studies. On the other hand, the antiatherosclerotic relevance of treatments antagonizing RANKL is still under investigation. Despite that clinical evidence is needed, this therapeutic approach might be of particular benefit in selective populations (such as rheumatoid arthritis patients) with an increased cardiovascular risk.