Plasma proteomics for prediction of subclinical coronary artery calcifications in primary prevention.

BACKGROUND AND AIMS: Recent developments in high-throughput proteomic technologies enable the discovery of novel biomarkers of coronary atherosclerosis. The aims of this study were to test if plasma protein subsets could detect coronary artery calcifications (CAC) in asymptomatic individuals and if they add predictive value beyond traditional risk factors. METHODS: Using proximity extension assays, 1,342 plasma proteins were measured in 1,827 individuals from the Impaired Glucose Tolerance and Microbiota (IGTM) study and 883 individuals from the Swedish Cardiopulmonary BioImage Study (SCAPIS) aged 50-64 years without history of ischaemic heart disease and with CAC assessed by computed tomography. After data-driven feature selection, extreme gradient boosting machine learning models were trained on the IGTM cohort to predict the presence of CAC using combinations of proteins and traditional risk factors. The trained models were validated in SCAPIS. RESULTS: The best plasma protein subset (44 proteins) predicted CAC with an area under the curve (AUC) of 0.691 in the validation cohort. However, this was not better than prediction by traditional risk factors alone (AUC = 0.710, P = .17). Adding proteins to traditional risk factors did not improve the predictions (AUC = 0.705, P = .6). Most of these 44 proteins were highly correlated with traditional risk factors. CONCLUSIONS: A plasma protein subset that could predict the presence of subclinical CAC was identified but it did not outperform nor improve a model based on traditional risk factors. Thus, support for this targeted proteomics platform to predict subclinical CAC beyond traditional risk factors was not found.

Association of Serum Osteoprotegerin With Vascular Calcification, and Cardiovascular and Graft Outcomes in Kidney Transplant Patients: Results From the KNOW-KT.

BACKGROUND: Vascular calcification and stiffness contribute to increased cardiovascular morbidity in patients with chronic kidney disease. This study investigated associations between serum osteoprotegerin (OPG) levels and vascular calcification or stiffness to assess cardiovascular and graft outcomes in kidney transplant patients. METHODS: The KoreaN cohort study for Outcome in patients With Kidney Transplantation was a prospective multicenter cohort study. Serum OPG levels were measured at baseline and 3 y after transplantation in 1018 patients. Patients were classified into high and low OPG groups according to median serum OPG levels. The median follow-up duration was 93.5 mo. RESULTS: The mean age was 45.8 ±â€…11.7 y and 62.9% were men. Patients with high OPG had significantly higher coronary artery calcium scores, abdominal aortic calcification scores, and brachial-ankle pulse wave velocities than those with lower OPG; these parameters remained significant for 5 y after transplantation. The 3-y OPG levels were lower than baseline values ( P < 0.001) and were positively correlated ( r = 0.42, P < 0.001). Multivariate Cox regression analysis showed that high OPG levels were significantly associated with posttransplant cardiovascular events ( P = 0.008) and death-censored graft loss ( P = 0.004). Similar findings regarding posttransplant cardiovascular events ( P = 0.012) and death-censored graft loss ( P = 0.037) were noted in patients with high OPG at the 3-y follow-up. Mediation analyses revealed that coronary artery calcium scores, abdominal aortic calcification scores, and brachial-ankle pulse wave velocities could act as mediators between serum OPG levels and posttransplant cardiovascular events. CONCLUSIONS: Serum OPG concentration is associated with vascular calcification and stiffness and could be a significant risk factor for cardiovascular outcomes and graft loss in patients undergoing kidney transplantation.

Organ aging signatures in the plasma proteome track health and disease.

Animal studies show aging varies between individuals as well as between organs within an individual1-4, but whether this is true in humans and its effect on age-related diseases is unknown. We utilized levels of human blood plasma proteins originating from specific organs to measure organ-specific aging differences in living individuals. Using machine learning models, we analysed aging in 11 major organs and estimated organ age reproducibly in five independent cohorts encompassing 5,676 adults across the human lifespan. We discovered nearly 20% of the population show strongly accelerated age in one organ and 1.7% are multi-organ agers. Accelerated organ aging confers 20-50% higher mortality risk, and organ-specific diseases relate to faster aging of those organs. We find individuals with accelerated heart aging have a 250% increased heart failure risk and accelerated brain and vascular aging predict Alzheimer's disease (AD) progression independently from and as strongly as plasma pTau-181 (ref. 5), the current best blood-based biomarker for AD. Our models link vascular calcification, extracellular matrix alterations and synaptic protein shedding to early cognitive decline. We introduce a simple and interpretable method to study organ aging using plasma proteomics data, predicting diseases and aging effects.

Relationship Between Sclerostin Levels and Coronary Artery Calcification and Plaque Composition.

OBJECTIVE: The primary function of sclerostin is the regulation of bone metabolism. Research investigating the cardiovascular effects of sclerostin had conflicting results. We aimed to study serum sclerostin levels in coronary artery plaque types. METHODS: Coronary calcium scores of 175 patients were evaluated. Patients with normal coronary arteries and calcium score of greater than zero constituted control (n = 47) and study groups (n = 83), respectively. Patients' plaques were further categorized as non-calcified plaque, calcified plaque, or mixed plaque (n = 45, n = 40, and n = 43, respectively). RESULTS: The study group had increased serum sclerostin levels than that of controls. Moreover, sclerostin levels were significantly higher in patients with calcified or mixed plaques compared to those without plaque or non-calcified plaque (median 248.5, 60.7-790.4) pg/mL and 1085.8 (185.8-3902.2) pg/mL versus 68.7 (34.0-141.3) pg/mL, and 67.7 (48.6-94.9) pg/mL, P < 0.001, respectively). Sclerostin showed a high correlation with coronary calcium scores (r = 0.95, P < 0.001). Serum sclerostin concentration of 106.27 pg/mL had 97.5% sensitivity and 67.4% specificity for the prediction of calcific plaque, whereas the level of 308.55 pg/mL had 95.3% sensitivity and 90.9% specificity for the prediction of mixed plaque. Coronary calcium scores, serum sclerostin, and C-reactive protein levels were significant predictors of 1-year major adverse cardiac events. CONCLUSIONS: Increased serum sclerostin level is a marker of coronary atherosclerosis burden and has a value for the prediction of 1-year major adverse cardiac events.

Serum osteocalcin concentration as an independent biomarker of osteoporosis in patients with chronic kidney disease.

OBJECTIVES: Osteocalcin, an osteoblast-derived hormone, is associated with the development of osteoporosis and arteriosclerosis in the general population. However, its role on the pathogenesis of osteoporosis and vascular calcification in patients with chronic kidney disease (CKD) is unclear. Here, we investigated the connection between osteocalcin, bone mineral density (BMD), and abdominal aortic calcification (AAC) in CKD patients. MATERIALS AND METHODS: In total, 95 patients with stage 2 to stage 5 CKD were enrolled. Serum osteocalcin levels were measured using an electrochemiluminescence immunoassay. BMD was determined by dual-energy X-ray absorptiometry, and AAC scores were generated from lateral lumbar radiograph findings. RESULTS: 95 patients were assigned into normal bone density (30.5%, n = 29), osteopenia (45.3%, n = 43), and osteoporosis (24.2%, n = 23) groups. The osteoporosis group was characterized by older age, higher female-to-male ratio, phosphorous levels, calcification scores, osteocalcin levels, and intact parathyroid hormone (PTH) levels, while with lower hemoglobin levels as compared to normal and osteopenia groups. Multivariate multinominal regression analysis showed age, female sex, intact PTH, and serum osteocalcin level were independent determinants of osteoporosis severity in CKD patients. Furthermore, serum osteocalcin level is positively correlated to intact PTH in multivariate linear regression model, indicating that osteocalcin might be a bone turnover marker in patients with CKD. Multivariate stepwise linear regression analysis revealed that age, diabetes mellitus, poorer renal function, rather than osteocalcin, have independent associations with AAC score. CONCLUSION: Elevated serum osteocalcin levels could be considered as a marker of osteoporosis rather than that of vascular calcification in patients with CKD.

Independent Association of Lipoprotein(a) and Coronary Artery Calcification With Atherosclerotic Cardiovascular Risk.

BACKGROUND: Elevated lipoprotein(a) [Lp(a)] and coronary artery calcium (CAC) score are individually associated with increased atherosclerotic cardiovascular disease (ASCVD) risk but have not been studied in combination. OBJECTIVES: This study sought to investigate the independent and joint association of Lp(a) and CAC with ASCVD risk. METHODS: Plasma Lp(a) and CAC were measured at enrollment among asymptomatic participants of the MESA (Multi-Ethnic Study of Atherosclerosis) (n = 4,512) and DHS (Dallas Heart Study) (n = 2,078) cohorts. Elevated Lp(a) was defined as the highest race-specific quintile, and 3 CAC score categories were studied (0, 1-99, and ≥100). Associations of Lp(a) and CAC with ASCVD risk were evaluated using risk factor-adjusted Cox regression models. RESULTS: Among MESA participants (61.9 years of age, 52.5% women, 36.8% White, 29.3% Black, 22.2% Hispanic, and 11.7% Chinese), 476 incident ASCVD events were observed during 13.2 years of follow-up. Elevated Lp(a) and CAC score (1-99 and ≥100) were independently associated with ASCVD risk (HR: 1.29; 95% CI: 1.04-1.61; HR: 1.68; 95% CI: 1.30-2.16; and HR: 2.66; 95% CI: 2.07-3.43, respectively), and Lp(a)-by-CAC interaction was not noted. Compared with participants with nonelevated Lp(a) and CAC = 0, those with elevated Lp(a) and CAC ≥100 were at the highest risk (HR: 4.71; 95% CI: 3.01-7.40), and those with elevated Lp(a) and CAC = 0 were at a similar risk (HR: 1.31; 95% CI: 0.73-2.35). Similar findings were observed when guideline-recommended Lp(a) and CAC thresholds were considered, and findings were replicated in the DHS. CONCLUSIONS: Lp(a) and CAC are independently associated with ASCVD risk and may be useful concurrently for guiding primary prevention therapy decisions.

Impact of Fetuin-A, Lp(a), matrix gla protein and macrophage density on calcific aortic valve disease: a clinical study.

BACKGROUND: Calcific aortic valve disease (CAVD) has a substantial and increasing burden in the ageing population with occult onset.Present study aimed to assess association of clinical characteristics of these patients and occurrence of CAVD. METHODS: Patients diagnosed with CAVD and those receiving healthy medical examination in our hospital from January 2019 to February 2021 were enrolled in this retrospective study. Clinical characteristics, ultrasonic indicators, serological indicators and histology of CAVD were collected and compared among different groups. Logistic regression and Pearson correlation analysis was used to explore relationship between these indexes and occurrence of CAVD. RESULTS: DBP, SBP, LVESD, LVEDD, IVS, PW, AV Vmax, TC, TG, LDL-C, Fetuin-A, Lp(a) in severe group were higher than mild, moderate and control groups (P<0.05), while those indexes of patients in moderate group were higher than that in mild and controlled groups (P<0.05). Besides, theses indexes of patients in mild group were also higher than that of controlled one (P<0.05). However, LVEF, HDL-C and MGP of patients in severe group was the lowest (P<0.05), while those in moderate group were lower than mild and controlled groups. Moreover, these indexes in mild group were also lower than control group (P<0.05). In Logistic regression analysis, MGP, Fetuin-A and Lp(a) were all independently associated with occurrence of CAVD (P<0.05). In Pearson correlation analysis, Fetuin-A and Lp(a) were positively correlated with progression of the disease, while MGP and macrophage density were negatively correlated with it. CONCLUSIONS: Fetuin-A, MPG and Lp(a) were independently associated with the occurrence of CAVD, and they might be potential predictors for diagnosis of this disease.

Lipoprotein (a)-mediated vascular calcification: population-based and in vitro studies.

BACKGROUND: Lipoprotein (a) [Lp(a)] is a causal risk factor for cardiovascular diseases, while its role in vascular calcification has not been well-established. Here, we investigated an association of Lp(a) with vascular calcification using population-based and in vitro study designs. METHODS: A total of 2806 patients who received coronary computed tomography were enrolled to assess the correlation of Lp(a) with the severity of coronary artery calcification (CAC). Human aortic smooth muscle cells (HASMCs) were used to explore mechanisms of Lp(a)-induced vascular calcification. RESULTS: In the population study, Lp(a) was independently correlated with the presence and severity of CAC (all p < 0.05). In vitro study showed that cell calcific depositions and alkaline phosphatase (ALP) activity were increased and the expression of pro-calcific proteins, including bone morphogenetic protein-2 (BMP2) and osteopontin (OPN), were up-regulated by Lp(a) stimulation. Interestingly, Lp(a) activated Notch1 signaling, resulting in cell calcification, which was inhibited by the Notch1 signaling inhibitor, DAPT. Lp(a)-induced Notch1 activation up-regulated BMP2-Smad1/5/9 pathway. In contrast, Noggin, an inhibitor of BMP2-Smad1/5/9 pathway, significantly blocked Lp(a)-induced HASMC calcification. Notch1 activation also induced translocation of nuclear factor-κB (NF-κB) accompanied by OPN overexpression and elevated inflammatory cytokines production, while NF-κB silencing alleviated Lp(a)-induced vascular calcification. CONCLUSIONS: Elevated Lp(a) concentrations are independently associated with the presence and severity of CAC and the impact of Lp(a) on vascular calcification is involved in the activation of Notch1-NF-κB and Notch1-BMP2-Smad1/5/9 pathways, thus implicating Lp(a) as a potential novel therapeutic target for vascular calcification.

Association of Matrix Metalloproteinase-2 (MMP-2) and MMP-9 Promoter Polymorphisms, Their Serum Levels, and Activities with Coronary Artery Calcification (CAC) in an Iranian Population.

The serum levels and activity of matrix metalloproteinases (MMPs) are associated with the risk of coronary artery calcification (CAC). We sought to investigate the association between MMP-2 -1575G>A (rs243866) and MMP-9 -1562 C>T (rs3918242) SNPs with MMP-2 and MMP-9 serum levels and activity in individuals with CAC. One hundred and fifty-five cases with CAC and 155 healthy individuals as control group from West of Iran were included and frequency of genotypes and alleles of rs243866 and rs3918242 in MMP-2 and MMP-9 genes were determined using PCR-RFLP. We also investigated the serum levels of MMP-2 and MMP-9 and their activity using ELISA and gelatin zymography, respectively. Additionally, serum biochemical parameters including FBS (fasting blood sugar), urea, creatinine, cholesterol, triglyceride, HDL (high-density lipoprotein), LDL (low-density lipoprotein), calcium, and phosphorus as well as blood pressure (systolic blood pressure (SBP) and diastolic blood pressure (DBP)) were measured. Our results showed that both serum levels of MMP-2 and MMP-9 (P < 0.001) and their activity (P < 0.001) were higher in individuals with CAC when compared to the control group. Carrying A and T alleles in MMP-2 -1575G>A (rs243866) and MMP-9 -1562 C>T (rs3918242) SNPs, respectively, may predispose the individuals to CAC by acting as the risk factors. Serum levels and activity of MMP-2 and MMP-9 were found to be higher in CAC cases when compared to the healthy controls. Carriers of A allele in rs243866 SNP and T allele in rs3918242 SNP were shown to have higher MMP-2 and MMP-9 serum levels and activity that may result in increased ECM degradation and support the initiation and development of calcification.

CircSamd4: A novel biomarker for predicting vascular calcification.

BACKGROUND: Vascular calcification (VC) is usually associated with cardiovascular diseases (CVDs), which are one of the main causes of mortality in the world. This study aimed to analyze the expression of circular RNAs (circRNAs) in patients with VC and to evaluate biomarkers for the diagnosis of VC. METHODS: Calcified human aortic endothelial cells (HAECs) and the calcification in mouse aorta were detected by qRT-PCR. Subsequently, this was verified in the plasma of patients with coronary artery calcification (CAC). The plasma of 40 patients in the control group and 31 patients in the calcified group were detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR) to detect the level of circSamd4a in the blood. The diagnostic value was evaluated by logistic regression analysis and the working characteristics of subjects. RESULTS: In the HAECs, the qRT-PCR showed a significant decrease in the level of circSamd4a expression in the calcification group compared to the control group (p < 0.05). The calcified mouse aorta showed the same trend for circSamd4a expression, wherein the difference was statistically significant (p < 0.05); the expression of circSamd4a was significantly downregulated in the plasma of patients with VC (p < 0.01). The receiver operating characteristic (ROC) curves of circSamd4a in patients with VC and control group showed that the area under the curve (AUC) was 0.81 (95% CI: 0.707-0.913; p < 0.001). CONCLUSION: CircSamd4a showed a stable downward trend in different specimens, and had significant advantages as a biomarker for diagnosis of VC.

Serum fatty acid binding protein 4 levels are associated with abdominal aortic calcification in peritoneal dialysis patients.

BACKGROUND: Fatty acid binding protein 4 (FABP4) is an adipokine that was mainly derived from adipocytes and macrophages. Vascular calcification (VC) is highly prevalent in peritoneal dialysis (PD) patients and could predict their cardiovascular mortality. The pathogenesis of VC is complex, and adipokines may play an important role in it. This study aimed to examine the relationship between serum FABP4 and VC in PD patients. METHODS: Serum FABP4 was measured by enzyme-linked immunosorbent assay. According to the median value of serum FABP4, the participants were divided into the low FABP4 group and the high FABP4 group. Lateral plain X-ray films of abdomen were used to evaluate the abdominal aortic calcification (AAC) score. The participants were divided into the high AAC score group (AAC score ≥4, indicating moderate or heavy VC) and the low AAC score group (AAC score <4, indicating no or mild VC). RESULTS: 116 PD patients were involved in the study. The AAC score and the proportion of patients with an AAC score ≥4 of the high FABP4 group were significantly higher than those of the low FABP4 group. Serum FABP4 of the high AAC score group was significantly higher than that of the low AAC score group [164.5 (138.4, 362.8) ng/mL versus 144.7 (123.8, 170.1) ng/mL, p = 0.002]. Serum FABP4 was positively associated with the AAC score according to the multivariate linear regression analysis. In the multivariate logistic regression analysis, serum FABP4 was the independent influencer of an AAC score ≥4. CONCLUSIONS: Serum FABP4 is positively associated with the AAC score and is an independent marker of AAC in PD patients.

Hepatic and Vascular Vitamin K Status in Patients with High Cardiovascular Risk.

Vitamin K dependent proteins (VKDP), such as hepatic coagulation factors and vascular matrix Gla protein (MGP), play key roles in maintaining physiological functions. Vitamin K deficiency results in inactive VKDP and is strongly linked to vascular calcification (VC), one of the major risk factors for cardiovascular morbidity and mortality. In this study we investigated how two vitamin K surrogate markers, dephosphorylated-undercarboxylated MGP (dp-ucMGP) and protein induced by vitamin K absence II (PIVKA-II), reflect vitamin K status in patients on hemodialysis or with calcific uremic arteriolopathy (CUA) and patients with atrial fibrillation or aortic valve stenosis. Through inter- and intra-cohort comparisons, we assessed the influence of vitamin K antagonist (VKA) use, vitamin K supplementation and disease etiology on vitamin K status, as well as the correlation between both markers. Overall, VKA therapy was associated with 8.5-fold higher PIVKA-II (0.25 to 2.03 AU/mL) and 3-fold higher dp-ucMGP (843 to 2642 pM) levels. In the absence of VKA use, non-renal patients with established VC have dp-ucMGP levels similar to controls (460 vs. 380 pM), while in HD and CUA patients, levels were strongly elevated (977 pM). Vitamin K supplementation significantly reduced dp-ucMGP levels within 12 months (440 to 221 pM). Overall, PIVKA-II and dp-ucMGP showed only weak correlation (r2 ≤ 0.26) and distinct distribution pattern in renal and non-renal patients. In conclusion, VKA use exacerbated vitamin K deficiency across all etiologies, while vitamin K supplementation resulted in a vascular VKDP status better than that of the general population. Weak correlation of vitamin K biomarkers calls for thoughtful selection lead by the research question. Vitamin K status in non-renal deficient patients was not anomalous and may question the role of vitamin K deficiency in the pathogenesis of VC in these patients.

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

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

The Combined Prognostic Significance of Alkaline Phosphatase and Intracranial Arterial Calcifications in Hemodialysis Patients.

INTRODUCTION: The prevalence of intracranial arterial calcification (ICAC) in maintenance hemodialysis (MHD) patients is about 90%, and its severity is correlated with age, hemodialysis vintage, and mineral bone disease. Elevated concentrations of calcium and phosphorus are not sufficient for medial calcification because of inhibition by pyrophosphate. Alkaline phosphatase (ALP) promotes calcification by hydrolyzing extracellular pyrophosphate. Epigenetic mechanisms involving ALP inhibition by apabetalone were investigated as a potential target for preventing vascular calcifications (VCs). This study assessed the combined impact of VCs and elevated serum ALP on mortality among chronic HD patients. METHODS: VCs represented by ICAC were measured simultaneously with mineral bone disease parameters including serum ALP of MHD patients who underwent noncontrast brain computed tomography from 2015 to 2018 in our institution. RESULTS: This retrospective study included 150 MHD patients (mean age 71.3 ± 12.1 years, 60.1% male). Of the total cohort, 12 (7.8%) had no brain calcifications and 69 (45.1%) had multiple intracranial calcifications. Considering the patients with normal ALP and no calcification as the reference group yielded adjusted odds ratios for all-cause mortality of 4.6 (95% CI: 1.7-12.7) among patients with brain calcifications and normal ALP (p = 0.003) and odds ratios for all-cause mortality of 6.1 (95% CI: 2.1-17.7) among patients with brain calcifications and elevated ALP (p= 0.001). CONCLUSION: We found an independent association between ICAC and the risk of death among MHD patients. The combined effect of ICAC and elevated ALP was associated with a higher odds ratio for all-cause mortality in MHD patients and may contribute to the risk stratification of these patients.

Secreted Frizzled-Related Protein 5 Ameliorates Vascular Calcification in a Rat Model of Chronic Kidney Disease through the Wnt/ß-Catenin Pathway.

INTRODUCTION: Vascular calcification (VC) is highly prevalent and a major cardiovascular risk factor in chronic kidney disease (CKD) patients. Secreted frizzled-related protein 5 (SFRP5), an inhibitor of the Wnt pathway, is an adipokine with a positive effect on metabolic and cardiovascular diseases. Our previous in vitro study showed that SFRP5 attenuates high phosphate-induced calcification in vascular smooth muscle cells by inhibiting the Wnt/ß-catenin pathway. Therefore, we hypothesized that SFRP5 may protect against CKD-associated VC (CKD-VC) through the same signalling. METHODS: The rat model of CKD with VC was induced by 0.75% adenine combined with 1.8% high phosphate diet, which were administered with adenovirus vectors of SFRP5. We evaluated the SFRP5 effect on VC by von Kossa staining and calcium content analysis and osteogenic markers by immunohistochemistry and Western blot. The components of Wnt/ß-catenin signalling were also evaluated. RESULTS: SFRP5 local and serum levels were significantly decreased in the CKD-VC rat model compared with the control group. Adenovirus-mediated overexpression of SFRP5 significantly inhibited VC, which was due to suppression of CKD-induced expression of calcification and osteoblastic markers. Additionally, SFRP5 abrogated activation of the Wnt/ß-catenin pathway that plays a major role in the pathogenesis of VC. The specificity of SFRP5 for inhibition of VC was confirmed using an empty adenovirus as a control. CONCLUSION: Our results suggest that SFRP5 ameliorates VC of CKD rats by inhibiting the expression of calcification and osteoblastic markers as well as the Wnt/ß-catenin pathway. Collectively, this study suggests that SFRP5 is a potential therapeutic target in CKD-VC.

High levels of osteoprotegerin are associated with coronary artery calcification in patients suspected of a chronic coronary syndrome.

Plasma osteoprotegerin (OPG) and vascular smooth muscle cell (VSMC) derived extracellular vesicles (EVs) are important regulators in the process of vascular calcification (VC). In population studies, high levels of OPG are associated with events. In animal studies, however, high OPG levels result in reduction of VC. VSMC-derived EVs are assumed to be responsible for OPG transport and VC but this role has not been studied. For this, we investigated the association between OPG in plasma and circulating EVs with coronary artery calcium (CAC) as surrogate for VC in symptomatic patients. We retrospectively assessed 742 patients undergoing myocardial perfusion imaging (MPI). CAC scores were determined on the MPI-CT images using a previously developed automated algorithm. Levels of OPG were quantified in plasma and two EV-subpopulations (LDL and TEX), using an electrochemiluminescence immunoassay. Circulating levels of OPG were independently associated with CAC scores in plasma; OR 1.39 (95% CI 1.17-1.65), and both EV populations; EV-LDL; OR 1.51 (95% CI 1.27-1.80) and EV-TEX; OR 1.21 (95% CI 1.02-1.42). High levels of OPG in plasma were independently associated with CAC scores in this symptomatic patient cohort. High levels of EV-derived OPG showed the same positive association with CAC scores, suggesting that EV-derived OPG mirrors the same pathophysiological process as plasma OPG.

Development of the BioHybrid Assay: Combining Primary Human Vascular Smooth Muscle Cells and Blood to Measure Vascular Calcification Propensity.

BACKGROUND: Vascular calcification is an active process that increases cardiovascular disease (CVD) risk. There is still no consensus on an appropriate biomarker for vascular calcification. We reasoned that the biomarker for vascular calcification is the collection of all blood components that can be sensed and integrated into a calcification response by human vascular smooth muscle cells (hVSMCs). METHODS: We developed a new cell-based high-content assay, the BioHybrid assay, to measure in vitro calcification. The BioHybrid assay was compared with the o-Cresolphthalein assay and the T50 assay. Serum and plasma were derived from different cohort studies including chronic kidney disease (CKD) stages III, IV, V and VD (on dialysis), pseudoxanthoma elasticum (PXE) and other cardiovascular diseases including serum from participants with mild and extensive coronary artery calcification (CAC). hVSMCs were exposed to serum and plasma samples, and in vitro calcification was measured using AlexaFluor®-546 tagged fetuin-A as calcification sensor. RESULTS: The BioHybrid assay measured the kinetics of calcification in contrast to the endpoint o-Cresolphthalein assay. The BioHybrid assay was more sensitive to pick up differences in calcification propensity than the T50 assay as determined by measuring control as well as pre- and post-dialysis serum samples of CKD patients. The BioHybrid response increased with CKD severity. Further, the BioHybrid assay discriminated between calcification propensity of individuals with a high CAC index and individuals with a low CAC index. Patients with PXE had an increased calcification response in the BioHybrid assay as compared to both spouse and control plasma samples. Finally, vitamin K1 supplementation showed lower in vitro calcification, reflecting changes in delta Agatston scores. Lower progression within the BioHybrid and on Agatston scores was accompanied by lower dephosphorylated-uncarboxylated matrix Gla protein levels. CONCLUSION: The BioHybrid assay is a novel approach to determine the vascular calcification propensity of an individual and thus may add to personalised risk assessment for CVD.

Role of Vitamin K in CKD: Is Its Supplementation Advisable in CKD Patients?

BACKGROUND: Patients with CKD are at an increased risk of developing vascular calcification (VC) and bone complications which translate into a higher morbidity and mortality. The dephosphorylated and uncarboxylated matrix Gla protein (dp-ucMGP) is considered to be an indicator of vitamin K2 status and correlates with markers of VC. It is activated by γ-glutamyl carboxylase that converts inactive MGP into an active form, and vitamin K2 is a cofactor of this reaction. The active form of MGP is a known inhibitor of arterial wall calcification and plays an important role in bone turnover. Recent studies show poor vitamin K2 status in CKD patients. We aimed to review the literature for the association between vitamin K2 status and calcification and bone disease risk and the efficacy of vitamin K2 supplementation in CKD population. SUMMARY: Most CKD patients, including those on renal replacement therapy, have vitamin K2 deficiency. The dp-ucMGP level, a marker of vitamin K2 status, is decreased by vitamin K2 supplementation in CKD patients, but there is no unequivocal proof that it influences arterial calcification progression and bone complications. Key Messages: CKD population are at risk of vitamin K deficiency. Supplementation of vitamin K2 is safe and improves the serum markers of its deficiency. There is lack of strong evidence that vitamin K2 supplementation slows progression of calcification or reduces the frequency of bone complications. More prospective studies are needed.

Serum uric acid is associated with coronary artery calcification in early chronic kidney disease: a cross-sectional study.

BACKGROUND: Although uric acid (UA) is regarded as a risk factor for cardiovascular disease, whether UA is an independent risk factor contributing to coronary artery calcification in chronic kidney disease (CKD) is not well known. We evaluated whether UA level is associated with coronary artery calcium (CAC) score in a predialysis CKD cohort. METHODS: A total of 1,350 subjects who underwent coronary computed tomography as part of the KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease were analysed. We conducted a logistic regression analysis to evaluate the association between UA and the presence of CAC. RESULTS: CAC was detected in 705 (52.2 %) patients, and the level of UA was significantly higher in CAC > 0 patients. UA showed a positive relationship with CAC > 0 in age- and sex-adjusted logistic regression analysis (Odds ratio (OR) 1.11, 95 % confidence interval (CI) 1.04-1.19, P = 0.003). However, UA showed no association with CAC > 0 in multivariate analysis. Further analysis showed that UA showed a positive association with CAC > 0 only in estimated glomerual filtration rate (eGFR) > 60 ml/min/1.73 m2 (OR 1.23, 95 % CI 1.02-1.49, P = 0.036) but not in eGFR 30-59 ml/min/1.73 m2 (OR 0.92, 95 % CI 0.78-1.08, P = 0.309) or < 30 ml/min/1.73 m2 (OR 0.92, 95 % CI 0.79-1.08, P = 0.426). CONCLUSIONS: UA level was significantly associated with CAC in early CKD, but not in advanced CKD.

Serum free fatty acids are associated with severe coronary artery calcification, especially in diabetes: a retrospective study.

BACKGROUND: Serum free fatty acid (FFA) concentrations are associated with coronary heart disease and diabetes mellitus (DM). Few studies focused on the relationship between serum FFA levels and coronary artery calcification (CAC). METHODS: This was a retrospective, single-centered study recruiting patients underwent FFA quantification, coronary angiography and intravascular ultrasound (IVUS). CAC severity was assessed with the maximum calcific angle (arc) of the calcified plaque scanned by IVUS. Patients with an arc ≥ 180° were classified into the severe CAC (SCAC) group, and those with an arc < 180° were classified into the non-SCAC group. Clinical characteristics, serum indices were compared between 2 groups. Logistic regression, receiver operating characteristic (ROC) curves and area under the curves (AUC) were performed. RESULTS: Totally, 426 patients with coronary artery disease were consecutively included. Serum FFA levels were significantly higher in the SCAC group than non-SCAC group (6.62 ± 2.17 vs. 5.13 ± 1.73 mmol/dl, p < 0.001). Logistic regression revealed that serum FFAs were independently associated with SCAC after adjusting for confounding factors in the whole cohort (OR 1.414, CI 1.237-1.617, p < 0.001), the non-DM group (OR 1.273, CI 1.087-1.492, p = 0.003) and the DM group (OR 1.939, CI 1.388-2.710, p < 0.001). ROC analysis revealed a serum FFA AUC of 0.695 (CI 0.641-0.750, p < 0.001) in the whole population. The diagnostic predictability was augmented (AUC = 0.775, CI 0.690-0.859, p < 0.001) in the DM group and decreased (AUC = 0.649, CI 0.580-0.718, p < 0.001) in the non-DM group. CONCLUSIONS: Serum FFA levels were independently associated with SCAC, and could have some predictive capacity for SCAC. The association was strongest in the DM group.