Serum Calcification Propensity and the Risk of Cardiovascular and All-Cause Mortality in the General Population: The PREVEND Study

RNA sequencing uncovers key players of cartilage calcification: potential implications for osteoarthritis pathogenesis

OBJECTIVE

OA is a joint disease linked with pathologic cartilage calcification, caused by the deposition of calcium-containing crystals by chondrocytes. Despite its clinical significance, the precise mechanisms driving calcification remain elusive. This study aimed to identify crucial players in cartilage calcification, offering insights for future targeted interventions against OA.

METHODS

Primary murine chondrocytes were stimulated with secondary calciprotein particles (CPP2) or left untreated (NT) for 6 h. Calcification was assessed by alizarin red staining. RNA was analysed by Bulk RNA sequencing. Differentially expressed (DE) genes were identified [cutoff: abs(LogFC)>1 and adjusted P-value < 0.05], and top 50 DE genes were cross-referenced with human OA datasets from previous studies (i.e. healthy vs. OA cartilage, or undamaged vs. damaged cartilage). RNA from NT and CPP2-stimulated primary human OA chondrocytes were used to validate genes by qPCR.

RESULTS

CPP2 induced crystal formation by chondrocytes and significantly modulated 1466 genes. Out of the top 50 DE genes in CPP2, 27 were confirmed in published OA cartilage datasets. Of those genes, some are described in calcification and/or OA (Errfi1, Ngf, Inhba, Col9a1). Two additional ones (Rcan1, Tnfrsf12a) appear novel and interesting in the context of calcification and OA. We validated modulation of these six genes in calcifying human chondrocytes from five patients. Ultimately, we unveiled two distinct gene families modulated by CPP2: the first comprised cytoskeletal genes (Actb, Tpm1, Cfl1, Tagln2, Lmna), while the second encompassed extracellular matrix genes (Fmod, Sparc, Col9a1, Cnmd).

CONCLUSION

CPP2 modulates genes in chondrocytes that could represent new targets for therapeutic interventions in OA.

The formation and function of calciprotein particles

Vertebrate extracellular fluids lie below the threshold for spontaneous calcium phosphate (Ca-Pi) precipitation; yet, they remain supersaturated enough to foster crystal growth if unchecked. Calciprotein particles (CPP) and their smaller precursor calciprotein monomers (CPM) have emerged as fast-acting "mineral buffers" that mitigate abrupt local oversaturation. Although these complexes typically contain only trace amounts of Ca-Pi relative to total plasma levels, they exhibit remarkably high turnover kinetics, with clearance from the circulation within minutes, far outpacing hormonal loops that operate on timescales of hours to days. By forming ephemeral colloidal assemblies, CPM/CPP help maintain fluid-phase stability and avert uncontrolled crystallization "accidents" in microenvironments such as the intestine or bone-remodeling sites. However, under chronic mineral stress, such as in chronic kidney disease, multiple inhibitory factors (e.g., fetuin-A, pyrophosphate) can become deficient, enabling persistent generation of more advanced, crystalline CPP species. These "modified" CPP can adsorb additional ligands (e.g., apolipoproteins, microbial remnants, growth factors) and have been linked to inflammatory and pro-calcific changes in vascular and immune cells. Despite their minor quantitative contribution, these rapidly mobilized colloids may exert outsized influence on vascular and skeletal homeostasis, underscoring the need to clarify their origins, biological roles, and potential therapeutic targeting in disorders of mineral metabolism.

Roxadustat increases markers of calcification in patients with end-stage kidney disease: prospective cohort study

To determine the effects of roxadustat on calcification when treating renal anemia in end-stage kidney disease (ESKD) patients. A prospective cohort study enrolled participants with ESKD that either received roxadustat or no roxadustat treatment. The primary outcome was the change in the degree of hydroxyapatite (HAP) crystals deposition. The secondary outcome was calcification propensity, a measure of calcification, allowing an evaluation of the conversion process from primary to secondary calciprotein particles. A total of 205 patients were enrolled, and 187 (91.2%) completed follow-up for inclusion in the analysis and were divided into the roxadustat group (n = 92) and the control group (n = 95) based on whether or not they were taking roxadustat regularly over a 6-mo period. After roxadustat administration for 6 mo, patients exhibited increases in total RBC counts, hematocrit, hemoglobin, calcium, total ferritin binding, intact fibroblast growth factor 23 (iFGF23), secreted phosphoprotein 24 (SPP24), and calcification propensity relative to pre-treatment levels. No significant differences were observed in patients who were not treated with roxadustat. The deposition degree of HAP crystals increased by 5% and 0.01% following treatment with roxadustat in the roxadustat group and control group, respectively. Linear regression analysis found that the use of roxadustat was an independent risk factor for calcification propensity and changes in the degree of HAP crystals deposition. Roxadustat treatment may increase iFGF23, SPP24, and calcification propensity in patients with ESKD when treating these patients for renal anemia. Therefore, the clinicians should aware of this risk when treating patients with prolyl hydroxylase domain inhibitors.

DXA and cardiovascular disease in rheumatoid arthritis: A scoping review

DXA technology is widely available today in many regions of the world. There is a growing realization of the value of DXA not only for osteoporosis management but also for sports medicine, sarcopenia, and the assessment of cardiovascular disease and mortality. Such features may be of particular interest for populations with a greater risk of these outcomes such as those with diabetes mellitus or rheumatoid arthritis. Recent systematic reviews and meta-analyses show DXA can robustly predict fractures, cardiovascular disease, dementia and mortality. Rheumatoid arthritis (RA) is a chronic inflammatory disease affecting multiple organs including synovial joints, bone and other tissues. People suffering from RA have a greater propensity to osteoporotic fracture, cardiovascular disease, infection and premature death, which is well recognised. RA is the only unique disease included in some fracture risk algorithms such as FRAX, and so RA patients are often referred for a DXA scan to evaluate their risk of osteoporosis. We have previously shown vertebral fractures, aortic calcification and cardiovascular disease are prevalent in our RA population, with strong association. In this paper we performed a scoping review of published literature in Medline and Embase to better understand the current status of DXA and cardiovascular disease in RA populations. 822 papers were identified in an initial search of which 7 papers reflecting 2,038 RA patients from 7 different countries were included. Study design included 4 cross-sectional, 2 longitudinal and 1 case-control. All included associations with various cardiovascular measures, while only 1 included clinical events as an outcome. Our results suggest this is an area which remains relatively unexplored but has substantial important clinical potential.

Pathophysiology of chronic kidney disease-mineral bone disorder (CKD-MBD): from adaptive to maladaptive mineral homeostasis

Chronic kidney disease-mineral bone disorder (CKD-MBD) is a multifaceted condition commonly seen in people with reduced kidney function. It involves a range of interconnected issues in mineral metabolism, bone health and cardiovascular calcification, which are linked to a lower quality of life and shorter life expectancy. Although various epidemiological studies show that the laboratory changes defining CKD-MBD become more common as the glomerular filtration rate declines, the pathophysiology of CKD-MBD is still largely unexplained. We herein review the current understanding of CKD-MBD, provide a conceptual framework to understand this syndrome, and review the genetic and environmental factors that may influence the clinical manifestation of CKD-MBD. However, a deeper understanding of the pathophysiology of CKD-MBD is needed to understand the phenotype variability and the relative contribution to organ damage of factors involved in CKD-MBD to develop more effective interventions to improve outcomes in patients with CKD.

Chronic kidney disease-mineral and bone disorder: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

In 2017, Kidney Disease: Improving Global Outcomes (KDIGO) published a Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD). Since then, new lines of evidence have been published related to evaluating disordered mineral metabolism and bone quality and turnover, identifying and inhibiting vascular calcification, targeting vitamin D levels, and regulating parathyroid hormone. For an in-depth consideration of the new insights, in October 2023, KDIGO held a Controversies Conference on CKD-MBD: Progress and Knowledge Gaps Toward Personalizing Care. Participants concluded that the recommendations in the 2017 CKD-MBD guideline remained largely consistent with the available evidence. However, the framework of the 2017 Guideline, with 3 major sections-biochemical abnormalities in mineral metabolism; bone disease; and vascular calcification-may no longer best reflect currently available evidence related to diagnosis and treatment. Instead, future guideline efforts could consider mineral homeostasis and deranged endocrine systems in adults within a context of 2 clinical syndromes: CKD-associated osteoporosis, encompassing increased fracture risk in patients with CKD; and CKD-associated cardiovascular disease, including vascular calcification and structural abnormalities, such as valvular calcification and left ventricular hypertrophy. Participants emphasized that the complexity of bone and cardiovascular manifestations of CKD-MBD necessitates personalized approaches to management.

The effect of sevelamer on serum calcification propensity in patients with chronic kidney disease: the results of a multicentre, double-blind, placebo-controlled, randomized clinical trial

Background

The serum calcification propensity test (or T50 test) might become a standard tool for the assessment of vascular calcification risk and T50 might be a valuable biomarker in clinical trials of treatments intended to slow the progression of vascular calcification. Literature data suggest that non-calcium-containing phosphate binders can influence T50 in chronic dialysed patients. However, it is not clear whether similar interventions are effective in patients at earlier stages of chronic kidney disease (CKD).

Methods

The FGF23 Reduction: Efficacy of a New phosphate binder in CHronic kidney disease (FRENCH) trial was a multicentre, double-blind, placebo-controlled, randomized trial of sevelamer carbonate in participants with stage 3b/4 CKD. In this subanalysis of the FRENCH data, T50 and other laboratory variables (including fetuin-A and ionized and total magnesium) were measured centrally at baseline and after 12 weeks of treatment.

Results

A total of 96 patients were screened and 78 (55 men and 23 women) met the inclusion criteria and were randomized to receive placebo (n = 39) or sevelamer carbonate (n = 39). The median patient age was 66 years [interquartile range (IQR) 56-72], the median eGFR was 25 ml/min/1.73 m2 (IQR 21-30) and the mean T50 was 335 minutes (standard deviation 82). In a linear regression model, T50 was independently associated with serum ionized magnesium, fetuin-A and bicarbonate levels and inversely associated with phosphate concentration. The within-group changes in the mean T50 between week 0 and week 12 were not significant in the sevelamer group or the placebo group {4.6 minutes [95% confidence interval (CI) -13.6-22.8; P = .61] and 7.8 minutes [95% CI -16.4-32.1; P = .51], respectively}. Furthermore, we did not observe significant changes in fetuin-A and magnesium levels.

Conclusion

A 12-week course of the non-calcium-containing phosphate binder sevelamer carbonate was not associated with a significant change in T50 in patients with stage 3b/4 CKD. Phosphate binders might not be an effective strategy for modifying serum calcification propensity in non-dialysis-dependent patients with CKD.

BMP-4 and fetuin A in systemic sclerosis patients with or without calcinosis

Introduction

Systemic sclerosis (SSc) is a connective tissue disease at the interface between inflammation and autoimmunity progressively leading to diffuse microvascular and fibrotic involvement of the skin and of multiple internal organs. Approximately, 20-40% of SSc patients suffer from cutaneous calcinosis, a debilitating manifestation due to calcium salt deposition in soft connective tissues, causing pain, ulceration, infection, and deformities, responsible of severe functional limitations. Pathomechanisms are poorly understood as well as markers/molecules capable to predict the risk of patients to develop calcinosis.

Methods

An observational study was performed in 51 female patients, 25 with and 26 without calcinosis to compare clinical and laboratory parameters and to evaluate pro- and anti-calcifying circulating markers and the in vitro serum calcification potential (T50). Moreover, calcinosis samples were analyzed to characterize their mineral composition.

Results and discussion

Data demonstrate statistically significant differences in the prevalence of clinical manifestations and ACA and Scl70 autoantibodies in SSc patient with calcinosis compared to those without calcinosis. In SSc patients with calcinosis, serum levels of BMP-4 are higher, fetuin A might be regarded as a potential circulating prognostic marker and a negative correlation was observed between T50 and the global score of clinical manifestations, suggesting a potential predictive role of pro- and anti-calcifying molecules in SSc patients. Furthermore, calcinosis samples were characterized by the co-existence of phosphate and carbonate minerals with different stability and solubility. Further investigations on circulating markers in larger patient cohorts, especially at the early stages and throughout the natural course of the disease, may clarify their pathogenetic role in the SSc-related cutaneous calcinosis.

The serum levels of gasdermin D in uremic patients and its relationship with the prognosis: a prospective observational cohort study

OBJECTIVE

This study aimed to explore the serum levels of gasdermin D (GSDMD) in uremic (end-stage kidney disease, ESKD) patients and their correlation with vascular calcification (VC) and clinical results.

METHODS

This prospective observational cohort study enrolled 213 ESKD patients who were undergoing regular maintenance hemodialysis (MHD) for > 3 months in our hospital from August 2019 to July 2022. The abdominal aortic calcification score (AACS) was used to assess the VC condition of patients with ESKD. Serum GSDMD, caspase-1, interleukin (IL)-6, IL-1β, IL-18 and C-reactive protein (CRP) levels were measured using enzyme-linked immunosorbent assay (ELISA). Demographic and clinical data were obtained. All patients were followed up for 1 year, and patients with major adverse cardiovascular events (MACE) were defined as having a poor prognosis. All data used SPSS 26.0 to statistical analyses.

RESULTS

The serum total cholesterol (TC) levels of patients in the AACS > 4 group were significantly elevated compared with those in the AACS ≤ 4 group. In addition, ESKD patients with an AACS > 4 had significantly higher serum levels of GSDMD, caspase-1, IL-6, IL-18 and IL-1β. Moreover, Pearson's analysis supported a positive correlation between GSDMD and caspase-1, IL-6, and IL-1β. In addition, we found that GSDMD levels were positively correlated with the clinical data (AACS scores and serum TC levels) of patients with ERSD. Additionally, ROC curves showed that the serum levels of GSDMD could be a potential predictive biomarker of moderate/severe VC and prognosis in patients with ESKD. Finally, the results of logistic regression indicated that GSDMD and AACS scores were risk factors for poor prognosis in patients with ESKD.

CONCLUSION

Serum GSDMD levels were remarkably elevated in patients with ESKD with moderate/severe calcification. In addition, serum levels of GSDMD could be a potential predictive biomarker of moderate/severe VC and prognosis in patients with ESKD.

Calciprotein particles induce arterial stiffening ex vivo and impair vascular cell function

Calciprotein particles (CPPs) are an endogenous buffering system, clearing excessive amounts of Ca2+ and PO43- from the circulation and thereby preventing ectopic mineralization. CPPs circulate as primary CPPs (CPP1), which are small spherical colloidal particles, and can aggregate to form large, crystalline, secondary CPPs (CPP2). Even though it has been reported that CPPs are toxic to vascular smooth muscle cells (VSMC) in vitro, their effect(s) on the vasculature remain unclear. Here we have shown that CPP1, but not CPP2, increased arterial stiffness ex vivo. Interestingly, the effects were more pronounced in the abdominal infrarenal aorta compared to the thoracic descending aorta. Further, we demonstrated that CPP1 affected both endothelial and VSMC function, impairing vasorelaxation and contraction respectively. Concomitantly, arterial glycosaminoglycan accumulation was observed as well, which is indicative of an increased extracellular matrix stiffness. However, these effects were not observed in vivo. Hence, we concluded that CPP1 can induce vascular dysfunction.

Exploring the Association of Smoking and Alcohol Consumption with Presence of and Severe Coronary Artery Calcification

Background

Despite the majority of studies have identified smoking as a risk factor for coronary artery calcification (CAC), some studies have not identified this relationship. Differences on results reached by studies on the association of alcohol consumption with CAC exist. Moreover, studies have almost exclusively investigated the association between smoking and alcohol consumption independently. Whether an interaction effect of alcohol on the association of smoking and CAC exists has hardly been investigated.

Methods

The data of 2431 adult patients who visited Fuwai Hospital, Chinese Academy of Medical Sciences from September, 2001 to December, 2023 and had Agaston coronary artery calcification score (CACS) reported were utilized. Patients who (1) underwent percutaneous coronary intervention, coronary bypass graft and heart transplantation, or (2) were complicated by acute medical conditions, chronic kidney disease or malignant neoplasms were excluded. Data from 1528 patients were eventually analyzed. Logistic regression was employed to investigate the association of smoking and alcohol consumption with presence of CAC and severe CAC. Interaction effects of alcohol consumption history on the association of current smoking and both presence of and severe CAC were examined.

Results

Smoking history was significantly associated with presence of CAC and severe CAC. Current alcohol consumption was also significantly associated with presence of CAC and severe CAC. After adjusting for confounders, alcohol consumption history demonstrated an interaction effect on the association of current smoking with both presence of and severe CAC. Using non-alcohol consumers not smoking at the time of the study as reference, current smokers with an alcohol consumption history suffered from an increased risk of presence of CAC and severe CAC.

Conclusions

Both smoking history and current alcohol consumption were associated with presence of and severe CAC. Alcohol consumption history demonstrated an interaction effect on the association of current smoking with both presence of and severe CAC.

Accelerated calciprotein crystallization time (T50) is correlated with impaired lung diffusion capacity in systemic sclerosis

Background

Systemic sclerosis (SSc) is a complex auto-immune disease characterized by vascular damage, inflammation, fibrosis and calcinosis, where pulmonary involvement is the leading cause of mortality. Calciprotein particles (CPPs) are increasingly formed upon disbalance of the physiological mineral buffering system and induce pro-inflammatory effects. This exploratory study investigated whether functional indicators of the endogenous mineral buffering system are dysregulated in SSc and linked to disease activity.

Methods

T50 (calciprotein crystallization test or serum calcification propensity) and hydrodynamic radius of secondary CPPs (CPP2) were determined in serum samples from 78 SSc patients and 44 controls without SSc, and were associated with disease activity markers of SSc.

Results

T50 was reduced and CPP2 radius was increased in SSc patients as compared to controls, indicating a deranged mineral buffering system. This was accompanied by slightly higher serum phosphate and PTH levels in SSc patients, while iFGF23 was not significantly modified. Longitudinally, all parameters remained unchanged over time in SSc patients, only iFGF23 increased. While the modified Rodnan skin score showed some inconsistent correlations with mineral buffering indicators, their association was not independent of other factors. However, lower T50 was significantly correlated to reduced lung diffusion capacity and this association remained significant in a multivariate linear regression model.

Conclusion

This study provides indications for a disturbed mineral buffering system in SSc. Increased serum calcification propensity (lower T50) is correlated with impaired lung diffusion capacity, suggesting a possible role of deranged mineral buffering in disease progression. Further studies are required to confirm these observations in larger cohorts and to investigate a putative functional relevance.

Serum Calcification Propensity Is Increased in Myocardial Infarction and Hints at a Pathophysiological Role Independent of Classical Cardiovascular Risk Factors

BACKGROUND

Vascular calcification is associated with increased mortality in patients with cardiovascular disease. Secondary calciprotein particles are believed to play a causal role in the pathophysiology of vascular calcification. The maturation time (T50) of calciprotein particles provides a measure of serum calcification propensity. We compared T50 between patients with ST-segment-elevated myocardial infarction and control subjects and studied the association of T50 with cardiovascular risk factors and outcome.

METHODS

T50 was measured by nephelometry in 347 patients from the GIPS-III trial (Metabolic Modulation With Metformin to Reduce Heart Failure After Acute Myocardial Infarction: Glycometabolic Intervention as Adjunct to Primary Coronary Intervention in ST Elevation Myocardial Infarction: a Randomized Controlled Trial) and in 254 matched general population controls from PREVEND (Prevention of Renal and Vascular End-Stage Disease). We also assessed the association between T50 and left ventricular ejection fraction, as well as infarct size, the incidence of ischemia-driven reintervention during 5 years of follow-up, and serum nitrite as a marker of endothelial dysfunction.

RESULTS

Patients with ST-segment-elevated myocardial infarction had a significantly lower T50 (ie, higher serum calcification propensity) compared with controls (T50: 289±63 versus 338±56 minutes; P<0.001). In patients with ST-segment-elevated myocardial infarction, lower T50 was associated with female sex, lower systolic blood pressure, lower total cholesterol, lower LDL (low-density lipoprotein) cholesterol, lower triglycerides, and higher HDL (high-density lipoprotein) cholesterol but not with circulating nitrite or nitrate. Ischemia-driven reintervention was associated with higher LDL (P=0.03) and had a significant interaction term for T50 and sex (P=0.005), indicating a correlation between ischemia-driven reintervention and T50 above the median in men and below the median in women, between 150 days and 5 years of follow-up.

CONCLUSIONS

Serum calcification propensity is increased in patients with ST-segment-elevated myocardial infarction compared with the general population, and its contribution is more pronounced in women than in men. Its lack of/inverse association with nitrite and blood pressure confirms T50 to be orthogonal to traditional cardiovascular disease risk factors. Lower T50 was associated with a more favorable serum lipid profile, suggesting the involvement of divergent pathways of calcification stress and lipid stress in the pathophysiology of myocardial infarction.

Association of diabetes with cardiovascular calcification and all-cause mortality in end-stage renal disease in the early stages of hemodialysis: a retrospective cohort study

BACKGROUND

The main goal of this study was to examine how diabetes, cardiovascular calcification characteristics and other risk factors affect mortality in end-stage renal disease (ESRD) patients in the early stages of hemodialysis.

METHODS

A total of 285 ESRD patients in the early stages of hemodialysis were enrolled in this research, including 101 patients with diabetes. Survival time was monitored, and general data, biochemical results, cardiac ultrasound calcification of valvular tissue, and thoracic CT calcification of the coronary artery and thoracic aorta were recorded. Subgroup analysis and logistic regression were applied to investigate the association between diabetes and calcification. Cox regression analysis and survival between calcification, diabetes, and all-cause mortality. Additionally, the nomogram model was used to estimate the probability of survival for these individuals, and its performance was evaluated using risk stratification, receiver operating characteristic, decision, and calibration curves.

RESULTS

Cardiovascular calcification was found in 81.2% of diabetic patients (82/101) and 33.7% of nondiabetic patients (62/184). Diabetic patients had lower phosphorus, calcium, calcium-phosphorus product, plasma PTH levels and lower albumin levels (p < 0.001). People with diabetes were more likely to have calcification than people without diabetes (OR 5.66, 95% CI 1.96-16.36; p < 0.001). The overall mortality rate was 14.7% (42/285). The risk of death was notably greater in patients with both diabetes and calcification (29.27%, 24/82). Diabetes and calcification, along with other factors, collectively predict the risk of death in these patients. The nomogram model demonstrated excellent discriminatory power (area under the curve (AUC) = 0.975 at 5 years), outstanding calibration at low to high-risk levels and provided the greatest net benefit across a wide range of clinical decision thresholds.

CONCLUSIONS

In patients with ESRD during the early period of haemodialysis, diabetes significantly increases the risk of cardiovascular calcification, particularly multisite calcification, which is correlated with a higher mortality rate. The risk scores and nomograms developed in this study can assist clinicians in predicting the risk of death and providing individualised treatment plans to lower mortality rates in the early stages of hemodialysis.

The effect of six-month oral vitamin K supplementation on calcification propensity time in individuals with type 2 diabetes mellitus: A post hoc analysis of a randomized, double-blind, placebo-controlled trial

BACKGROUND AND AIMS

Experimental studies suggested that vitamin K supplementation may retard arterial calcification. Recently, serum calcification propensity time (T50) has been suggested as a functional biomarker for arterial wall calcification propensity. In this post-hoc analysis of a clinical trial, we evaluated the effect of six-month oral vitamin K supplementation on T50 and assessed the correlation between T50 and imaging arterial calcification parameters in people with type 2 diabetes (T2DM).

METHODS

This double-blind, randomized, placebo-controlled trial included 68 participants (age = 69 ± 8 years, 76% male) with T2DM. Participants were assigned to menaquinone-7 (360 μg/day; n = 35) or placebo (n = 33). T50 was measured via nephelometry in serum collected at baseline, three and six months. Arterial calcification was measured at baseline and six months via 18F-Na PET-CT and conventional CT using Target-to-Background ratio (TBR) and Agatston score. Longitudinal analysis of covariance adjusted for baseline T50 was used to study the treatment effect. Spearman's correlation was used to assess the correlation between T50 and imaging calcification parameters.

RESULTS

Median baseline T50 was similar in the vitamin K (350 [321-394] minutes) and placebo groups (363 [320-398]). There was no significant difference in T50 between treatment arms over time (ẞ = 1.00, 95%C.I. = 0.94-1.07, p = 0.982). The correlation coefficient of T50 with TBR and Agatston score at baseline were -0.185 (p = 0.156) and -0.121 (p = 0.358), respectively.

CONCLUSIONS

No effect of vitamin K supplementation on T50 was observed in T2DM. Moreover, T50 did not correlate with TBR and Agatston score. Further research on vitamin K in arterial calcification and on the validity of T50 as arterial calcification marker is warranted.

Serum T50 predicts cardiovascular mortality in individuals with type 2 diabetes: A prospective cohort study

BACKGROUND AND AIMS

Individuals with type 2 diabetes (T2D) have a higher risk of cardiovascular disease, compared with those without T2D. The serum T50 test captures the transformation time of calciprotein particles in serum. We aimed to assess whether serum T50 predicts cardiovascular mortality in T2D patients, independent of traditional risk factors.

METHODS

We analyzed 621 individuals with T2D in this prospective cohort study. Cox regression models were performed to test the association between serum T50 and cardiovascular and all-cause mortality. Causes of death were categorized according to ICD-10 codes. Risk prediction improvement was assessed by comparing Harrell's C for models without and with T50. RESULTS: The mean age was 64.2 ± 9.8 years, and 61% were male. The average serum T50 time was 323 ± 63 min. Higher age, alcohol use, high-sensitive C-reactive protein, and plasma phosphate were associated with lower serum T50 levels. Higher plasma triglycerides, venous bicarbonate, sodium, magnesium, and alanine aminotransferase were associated with higher serum T50 levels. After a follow-up of 7.5[5.4-10.7] years, each 60 min decrease in serum T50 was associated with an increased risk of cardiovascular (fully adjusted HR 1.32, 95% CI 1.08-1.50, and p = 0.01) and all-cause mortality (HR 1.15, 95%CI 1.00-1.38, and p = 0.04). Results were consistent in sensitivity analyses after exclusion of individuals with estimated glomerular filtration rate <45 or <60 mL/min/1.73 m2 and higher plasma phosphate levels.

CONCLUSIONS

Serum T50 improves prediction of cardiovascular and all-cause mortality risk in individuals with T2D. Serum T50 may be useful for risk stratification and to guide therapeutic strategies aiming to reduce cardiovascular mortality in T2D.

Citrate-Buffered, Magnesium-Enriched Dialysate on Calcification Propensity in Hemodialysis Patients - The CitMag Study

Introduction

Serum calcification propensity (T50 time) is associated with mortality in patients on dialysis. Several solitary interventions improve T50. However, whether a combination of interventions yields further increases in T50 is unknown. We hypothesized that a combination of 2 interventions, namely increasing magnesium concentration while simultaneously substituting acetate for citrate in the dialysis fluid, leads to increases in T50 values.

Methods

In a randomized controlled trial, 60 patients on chronic hemodialysis were allocated to either continue on standard (S) dialysate (3 mmol/l acetate, 0.5 mmol/l magnesium) or a sequence of magnesium-enriched (Mg0.75) dialysate (3 mmol/l acetate, 0.75 mmol/l magnesium) for 2 weeks followed by combination treatment using citrate-buffered, magnesium-enriched (Cit+Mg0.75) dialysate (1 mmol/l citrate, 0.75 mmol/l magnesium) for 3 weeks. The primary end point was the difference in T50 times between the S group and the Cit+Mg0.75 group.

Results

There was no significant difference in T50 time between the S group and the Cit+Mg0.75 group (236 ± 77 vs. 265 ± 97 min, P = 0.23). The size (hydrodynamic radius) of secondary calciprotein particles did not differ between the S group and the Cit+Mg0.75 group (294 ± 95 vs. 309 ± 91 nm, P = 0.56). In longitudinal analyses, serum magnesium concentrations increased from 1.07 ± 0.17 to 1.24 ± 0.17 mmol/l with the Mg0.75 dialysate (P < 0.0001) but decreased again to 1.19 ± 0.16 mmol/l with the Cit+Mg0.75 dialysate (P < 0.0001).

Conclusion

The combination of citrate buffer with increased magnesium concentration in dialysate does not improve T50.

Association between lower extremity arterial calcification and coronary arterial calcification in a population at increased risk of cardiovascular disease

INTRODUCTION

There is conflicting evidence whether lower extremity arterial calcification coincides with coronary arterial calcification (CAC). The aims of this study were to investigate the associations between (1) femoral and crural calcification with CAC, and (2) femoral and crural calcification pattern with CAC.

RESEARCH DESIGN AND METHODS

This cross-sectional study included 405 individuals (74% men, 62.6±10.9 years) from the ARTEMIS cohort study at high risk of cardiovascular disease (CVD) who underwent a CT scan of the femoral, crural and coronary arteries. High CVD risk was defined as history/presence of cerebrovascular disease, coronary artery disease, abdominal aortic aneurysm, renal artery stenosis, peripheral artery disease or CVD risk factors: diabetes mellitus type 2, hypertension, hyperlipidemia. Calcification score within each arterial bed was expressed in Agatston units. Dominant calcification patterns (intimal, medial, absent/indistinguishable) were determined via a CT-guided histologically validated scoring algorithm. Multivariable-adjusted multinomial logistic regression analyses were used. Replication was performed in an independent population of individuals with diabetes mellitus type 2 (Early-HFpEF cohort study).

RESULTS

Every 100-point increase in femoral and crural calcification score was associated with 1.23 (95% CI=1.09 to 1.37, p<0.001) and 1.28 (95% CI=1.11 to 1.47, p=0.001) times higher odds of having CAC within tertile 3 (high) versus tertile 1 (low), respectively. The association appeared stronger for crural versus femoral arteries. Moreover, the presence of femoral intimal (OR=10.81, 95% CI=4.23 to 27.62, p<0.001), femoral medial (OR=10.37, 95% CI=3.92 to 27.38, p<0.001) and crural intimal (OR=6.70, 95% CI=2.73 to 16.43, p<0.001) calcification patterns were associated with higher odds of having CAC within tertile 3 versus tertile 1, independently from concomitant calcification score. This association appeared stronger for intimal versus medial calcification patterns. The replication analysis yielded similar results.

CONCLUSIONS

Higher femoral and crural calcification scores were associated with higher CAC. Moreover, the presence of femoral intimal, femoral medial and crural intimal calcification patterns was associated with increased CAC. It appears that arterial calcification is a systemic process which occurs simultaneously in various arterial beds.

The basics of phosphate metabolism

Phosphorus is an essential mineral that is, in the form of inorganic phosphate (Pi), required for building cell membranes, DNA and RNA molecules, energy metabolism, signal transduction and pH buffering. In bone, Pi is essential for bone stability in the form of apatite. Intestinal absorption of dietary Pi depends on its bioavailability and has two distinct modes of active transcellular and passive paracellular absorption. Active transport is transporter mediated and partly regulated, while passive absorption depends mostly on bioavailability. Renal excretion controls systemic Pi levels, depends on transporters in the proximal tubule and is highly regulated. Deposition and release of Pi into and from soft tissues and bone has to be tightly controlled. The endocrine network coordinating intestinal absorption, renal excretion and bone turnover integrates dietary intake and metabolic requirements with renal excretion and is critical for bone stability and cardiovascular health during states of hypophosphataemia or hyperphosphataemia as evident from inborn or acquired diseases. This review provides an integrated overview of the biology of phosphate and Pi in mammals.

Calciprotein Particles Induce Cellular Compartment-Specific Proteome Alterations in Human Arterial Endothelial Cells

Calciprotein particles (CPPs) are indispensable scavengers of excessive Ca2+ and PO43- ions in blood, being internalised and recycled by liver and spleen macrophages, monocytes, and endothelial cells (ECs). Here, we performed a pathway enrichment analysis of cellular compartment-specific proteomes in primary human coronary artery ECs (HCAEC) and human internal thoracic artery ECs (HITAEC) treated with primary (amorphous) or secondary (crystalline) CPPs (CPP-P and CPPs, respectively). Exposure to CPP-P and CPP-S induced notable upregulation of: (1) cytokine- and chemokine-mediated signaling, Ca2+-dependent events, and apoptosis in cytosolic and nuclear proteomes; (2) H+ and Ca2+ transmembrane transport, generation of reactive oxygen species, mitochondrial outer membrane permeabilisation, and intrinsic apoptosis in the mitochondrial proteome; (3) oxidative, calcium, and endoplasmic reticulum (ER) stress, unfolded protein binding, and apoptosis in the ER proteome. In contrast, transcription, post-transcriptional regulation, translation, cell cycle, and cell-cell adhesion pathways were underrepresented in cytosol and nuclear compartments, whilst biosynthesis of amino acids, mitochondrial translation, fatty acid oxidation, pyruvate dehydrogenase activity, and energy generation were downregulated in the mitochondrial proteome of CPP-treated ECs. Differentially expressed organelle-specific pathways were coherent in HCAEC and HITAEC and between ECs treated with CPP-P or CPP-S. Proteomic analysis of mitochondrial and nuclear lysates from CPP-treated ECs confirmed bioinformatic filtration findings.

Humoral and cellular factors inhibit phosphate-induced vascular calcification during the growth period

Hyperphosphatemia is an independent and non-classical risk factor of cardiovascular disease and mortality in patients with chronic kidney disease (CKD). Increased levels of extracellular inorganic phosphate (Pi) are known to directly induce vascular calcification, but the detailed underlying mechanism has not been clarified. Although serum Pi levels during the growth period are as high as those observed in hyperphosphatemia in adult CKD, vascular calcification does not usually occur during growth. Here, we have examined whether the defence system against Pi-induced vascular calcification can exist during the growth period using mice model. We found that calcification propensity of young serum (aged 3 weeks) was significantly lower than that of adult serum (10 months), possibly due to high fetuin-A levels. In addition, when the aorta was cultured in high Pi medium in vitro, obvious calcification was observed in the adult aorta but not in the young aorta. Furthermore, culture in high Pi medium increased the mRNA level of tissue-nonspecific alkaline phosphatase (TNAP), which degrades pyrophosphate, only in the adult aorta. Collectively, our findings indicate that the aorta in growing mouse may be resistant to Pi-induced vascular calcification via a mechanism in which high serum fetuin-A levels and suppressed TNAP expression.

Ectopic Calcification: What Do We Know and What Is the Way Forward?

Ectopic calcification, or ectopic mineralization, is a pathologic condition in which calcifications develop in soft tissues [...].

Secondary calciprotein particle size is associated with patient mortality in peripheral artery disease

BACKGROUND AND AIMS

Secondary calciprotein particles (CPP-II) induce inflammation and contribute to vascular calcification. CPP-II size is associated with vascular calcification in patients with chronic kidney disease (CKD) and all-cause mortality in hemodialysis patients. Here, we investigate for the first time a possible role of CPP-II size in patients with peripheral artery disease (PAD) without severe CKD.

METHODS

We measured the hydrodynamic radius (Rh) of CPP-II by using dynamic light scattering in a cohort of 281 PAD patients. Mortality was evaluated over a period of ten years by central death registry queries. 35% of patients died during the observation period (median of 8.8 (6.2-9.0) years). Cox-regression analyses were performed to estimate hazard ratios (HR) and 95% confidence intervals (CI) and to allow for multivariable adjustment.

RESULTS

The mean CPP-II size was 188 (162-218) nm. Older patients, patients with reduced kidney function, and those with media sclerosis had larger CPP-II (p < 0.001, p = 0.008, and p = 0.043, retrospectively). There was no association between CPP-II size and overall atherosclerotic disease burden (p = 0.551). CPP-II size was independently significantly associated with all-cause (HR 1.33 (CI 1.01-1.74), p = 0.039) and cardiovascular mortality (HR 1.52 (CI 1.05-2.20), p = 0.026) in multivariable regression analyses.

CONCLUSIONS

Large CPP-II size is associated with mortality in PAD patients and might be a new feasible biomarker for the presence of media sclerosis in this patient population.

Assessment of a serum calcification propensity test for the prediction of all-cause mortality among hemodialysis patients

BACKGROUND

Vascular calcification is a major contributor to the high cardiac burden among hemodialysis patients. A novel in vitro T50-test, which determines calcification propensity of human serum, may identify patients at high risk for cardiovascular (CV) disease and mortality. We evaluated whether T50 predicts mortality and hospitalizations among an unselected cohort of hemodialysis patients.

METHODS

This prospective clinical study included 776 incident and prevalent hemodialysis patients from 8 dialysis centers in Spain. T50 and fetuin-A were determined at Calciscon AG, all other clinical data were retrieved from the European Clinical Database. After their baseline T50 measurement, patients were followed for two years for the occurrence of all-cause mortality, CV-related mortality, all-cause and CV-related hospitalizations. Outcome assessment was performed with proportional subdistribution hazards regression modelling.

RESULTS

Patients who died during follow-up had a significantly lower T50 at baseline as compared to those who survived (269.6 vs. 287.7 min, p = 0.001). A cross-validated model (mean c statistic: 0.5767) identified T50 as a linear predictor of all-cause-mortality (subdistribution hazard ratio (per min): 0.9957, 95% CI [0.9933;0.9981]). T50 remained significant after inclusion of known predictors. There was no evidence for prediction of CV-related outcomes, but for all-cause hospitalizations (mean c statistic: 0.5284).

CONCLUSION

T50 was identified as an independent predictor of all-cause mortality among an unselected cohort of hemodialysis patients. However, the additional predictive value of T50 added to known mortality predictors was limited. Future studies are needed to assess the predictive value of T50 for CV-related events in unselected hemodialysis patients.

Predicting progression of aortic stenosis by measuring serum calcification propensity

BACKGROUND

The aim of this prospective, double-blinded study in patients with aortic sclerosis was to determine whether a new calcification propensity measure in the serum could predict disease progression.

METHODS

We included 129 consecutive patients with aortic sclerosis as assessed during a routine clinical echocardiographic exam. Clinical, echocardiographic, and serum laboratory parameters were collected, including a new blood test providing an overall measure of calcification propensity by monitoring the maturation time of calciprotein particles (T50 test). The echocardiographic exam was repeated after 1 year. Multiple regression analysis was performed to identify independent predictors of the annual increase of peak transvalvular Doppler velocity (∆vmax). Furthermore, the accuracy of the T50 test to detect patients with the most marked stenosis progression was assessed by receiver operating characteristic (ROC)-analysis.

RESULTS

Mean age was 75 ± 9 years, 79% were men. The T50 was 271 ± 58 min. Overall, there was no significant stenosis progression between baseline and follow-up (∆vmax 3.8 ± 29.8 cm/s, p = ns). The T50 test was not found to be an independent linear predictor in multivariate testing. By ROC-analysis, however, a T50-value ≤ 242 min was able to significantly detect a ∆vmax above the 90th percentile (∆vmax ≥ 43 cm/s, AUC = 0.67, p = .04, Sensitivity = 69%, Specificity = 70%).

CONCLUSIONS

The T50 test showed a modest but significant ability to identify a pronounced aortic stenosis progression in patients with aortic sclerosis. The test could not be established as an independent linear predictor of disease progression, possibly due to the low valvular disease burden and short follow-up interval.

Serum Calcification Propensity Represents a Good Biomarker of Vascular Calcification: A Systematic Review

Vascular calcification contributes to cardiovascular morbidity and mortality. A recently developed serum calcification propensity assay is based on the half-transformation time (T50) from primary calciprotein particles (CPPs) to secondary CPPs, reflecting the serum’s endogenous capacity to prevent calcium phosphate precipitation. We sought to identify and review the results of all published studies since the development of the T50-test by Pasch et al. in 2012 (whether performed in vitro, in animals or in the clinic) of serum calcification propensity. To this end, we searched PubMed, Elsevier EMBASE, the Cochrane Library and Google Scholar databases from 2012 onwards. At the end of the selection process, 57 studies were analyzed with regard to the study design, sample size, characteristics of the study population, the intervention and the main results concerning T50. In patients with primary aldosteronism, T50 is associated with the extent of vascular calcification in the abdominal aorta. In chronic kidney disease (CKD), T50 is associated with the severity and progression of coronary artery calcification. T50 is also associated with cardiovascular events and all-cause mortality in CKD patients, patients on dialysis and kidney transplant recipients and with cardiovascular mortality in patients on dialysis, kidney transplant recipients, patients with ischemic heart failure and reduced ejection fraction, and in the general population. Switching from acetate-acidified dialysate to citrate-acidified dialysate led to a longer T50, as did a higher dialysate magnesium concentration. Oral administration of magnesium (in CKD patients), phosphate binders, etelcalcetide and spironolactone (in hemodialysis patients) was associated with a lower serum calcification propensity. Serum calcification propensity is an overall marker of calcification associated with hard outcomes but is currently used in research projects only. This assay might be a valuable tool for screening serum calcification propensity in at-risk populations (such as CKD patients and hemodialyzed patients) and, in particular, for monitoring changes over time in T50.

Periostin Augments Vascular Smooth Muscle Cell Calcification via β-Catenin Signaling

Medial vascular calcification is common in chronic kidney disease (CKD) and is closely linked to hyperphosphatemia. Vascular smooth muscle cells (VSMCs) can take up pro-calcific properties and actively augment vascular calcification. Various pro-inflammatory mediators are able to promote VSMC calcification. In this study, we investigated the effects and mechanisms of periostin, a matricellular signaling protein, in calcifying human VSMCs and human serum samples. As a result, periostin induced the mRNA expression of pro-calcific markers in VSMCs. Furthermore, periostin augmented the effects of β-glycerophosphate on the expression of pro-calcific markers and aggravated the calcification of VSMCs. A periostin treatment was associated with an increased β-catenin abundance as well as the expression of target genes. The pro-calcific effects of periostin were ameliorated by WNT/β-catenin pathway inhibitors. Moreover, a co-treatment with an integrin αvβ3-blocking antibody blunted the pro-calcific effects of periostin. The silencing of periostin reduced the effects of β-glycerophosphate on the expression of pro-calcific markers and the calcification of VSMCs. Elevated serum periostin levels were observed in hemodialysis patients compared with healthy controls. These observations identified periostin as an augmentative factor in VSMC calcification. The pro-calcific effects of periostin involve integrin αvβ3 and the activation of the WNT/β-catenin pathway. Thus, the inhibition of periostin may be beneficial to reduce the burden of vascular calcification in CKD patients.

Bone Specific Alkaline Phosphatase and Serum Calcification Propensity Are Not Influenced by Etelcalcetide vs. Alfacalcidol Treatment, and Only Bone Specific Alkaline Phosphatase Is Correlated With Fibroblast Growth Factor 23: Sub-Analysis Results of the ETACAR-HD Study

Secondary hyperparathyroidism in chronic kidney disease poses a major risk factor for vascular calcification and high bone turnover, leading to mineralization defects. The aim was to analyze the effect of active vitamin D and calcimimetic treatment on fibroblast growth factor 23 (FGF23), serum calcification propensity (T50), a surrogate marker of calcification stress and bone specific alkaline phosphatase (BAP) in hemodialysis. This is a subanalysis of a randomized trial comparing etelcalcetide vs. alfacalcidol in 62 hemodialysis patients for 1 year. We compared the change of BAP and serum calcification propensity between the two medications and assessed the influence of FGF23 change over time. We found no significant differences in the change of BAP or serum calcification propensity (T50) levels from baseline to study end between treatment arms (difference in change of marker between treatment with etelcalcetide vs. alfacalcidol: BAP : 2.0 ng/ml [95% CI-1.5,5.4], p = 0.3; T50: –15 min [95% CI –49,19], p = 0.4). Using FGF23 change over time, we could show that BAP levels at study end were associated with FGF23 change (–0.14 [95% CI –0.21, –0.08], p &lt; 0.001). We did not observe the same association between FGF23 change and T50 (effect of FGF23 change on T50: 3.7 [95% CI –5.1, 12], p = 0.4; R2 = 0.07 vs. R2 = 0.06). No significant difference was found in serum calcification propensity (T50) values between treatment arms. FGF23 was not associated with serum calcification propensity (T50), but was negatively correlated with BAP underlying its role in the bone metabolism.

Clinical Trial Registration

[www.ClinicalTrials.gov], identifier [NCT03182699].

Serum Calcification Propensity T50 Associates with Disease Severity in Patients with Pseudoxanthoma Elasticum

Pseudoxanthoma elasticum (PXE) is a currently intractable genetic disorder characterized by progressive ectopic calcification in the skin, eyes and arteries. Therapeutic trials in PXE are severely hampered by the lack of reliable biomarkers. Serum calcification propensity T50 is a blood test measuring the functional anticalcifying buffer capacity of serum. Here, we evaluated T50 in PXE patients aiming to investigate its determinants and suitability as a potential biomarker for disease severity. Fifty-seven PXE patients were included in this cross-sectional study, and demographic, clinical, imaging and biochemical data were collected from medical health records. PXE severity was assessed using Phenodex scores. T50 was measured using a validated, nephelometry-based assay. Multivariate models were then created to investigate T50 determinants and associations with disease severity. In short, the mean age of patients was 45.2 years, 68.4% was female and mean serum T50 was 347 min. Multivariate regression analysis identified serum fetuin-A (p < 0.001), phosphorus (p = 0.007) and magnesium levels (p = 0.034) as significant determinants of T50, while no correlations were identified with serum calcium, eGFR, plasma PPi levels or the ABCC6 genotype. After correction for covariates, T50 was found to be an independent determinant of ocular (p = 0.013), vascular (p = 0.013) and overall disease severity (p = 0.016) in PXE. To conclude, shorter serum T50—indicative of a higher calcification propensity—was associated with a more severe phenotype in PXE patients. This study indicates, for the first time, that serum T50 might be a clinically relevant biomarker in PXE and may thus be of importance to future therapeutic trials.

Effect of nutritional calcium and phosphate loading on calciprotein particle kinetics in adults with normal and impaired kidney function

Plasma approaches metastability with respect to its calcium and phosphate content, with only minor perturbations in ionic activity needed to sustain crystal growth once nucleated. Physiologically, calcium and phosphate are intermittently absorbed from the diet each day, yet plasma concentrations of these ions deviate minimally post-prandially. This implies the existence of a blood-borne mineral buffer system to sequester calcium phosphates and minimise the risk of deposition in the soft tissues. Calciprotein particles (CPP), endogenous mineral-protein colloids containing the plasma protein fetuin-A, may fulfill this function but definitive evidence linking dietary mineral loading with their formation is lacking. Here we demonstrate that CPP are formed as a normal physiological response to feeding in healthy adults and that this occurs despite minimal change in conventional serum mineral markers. Further, in individuals with Chronic Kidney Disease (CKD), in whom mineral handling is impaired, we show that both fasting and post-prandial levels of CPP precursors are markedly augmented and strongly inversely correlated with kidney function. This study highlights the important, but often neglected, contribution of colloidal biochemistry to mineral homeostasis and provides novel insight into the dysregulation of mineral metabolism in CKD.

Plasma phosphate and all-cause mortality in individuals with and without type 2 diabetes: the Dutch population-based lifelines cohort study

Introduction

Individuals with type 2 diabetes have a substantially elevated cardiovascular risk. A higher plasma phosphate level promotes vascular calcification, which may adversely affect outcomes in individuals with type 2 diabetes. We hypothesized that the association between plasma phosphate and all-cause mortality is stronger in individuals with type 2 diabetes, compared to those without diabetes.

Methods

We analysed the association between plasma phosphate and all-cause mortality in the Dutch population-based Lifelines cohort and in subgroups with and without type 2 diabetes, using multivariable Cox regression adjusted for potential confounders. Effect modification was tested using multiplicative interaction terms.

Results

We included 57,170 individuals with 9.4 [8.8–10.4] years follow-up. Individuals within the highest phosphate tertile (range 1.00–1.83 mmol/L) were at higher risk of all-cause mortality (fully adjusted HR 1.18 [95% CI 1.02–1.36], p = 0.02), compared with the intermediate tertile (range 0.85–0.99 mmol/L). We found significant effect modification by baseline type 2 diabetes status (p-interaction = 0.003). Within the type 2 diabetes subgroup (N = 1790), individuals within the highest plasma phosphate tertile had an increased mortality risk (HR 1.73 [95% CI 1.10–2.72], p = 0.02 vs intermediate tertile). In individuals without diabetes at baseline (N = 55,380), phosphate was not associated with mortality (HR 1.12 [95% CI 0.96–1.31], p = 0.14). Results were similar after excluding individuals with eGFR < 60 mL/min/1.73 m².

Discussion

High-normal plasma phosphate levels were associated with all-cause mortality in individuals with type 2 diabetes. The association was weaker and non-significant in those without diabetes. Measurement of phosphate levels should be considered in type 2 diabetes; whether lowering phosphate levels can improve health outcomes in diabetes requires further study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01499-4.

The emerging role of magnesium in CKD

Increasing evidence has suggested a clinical relevance of magnesium in the context of vascular calcification and mortality among patients with CKD. Hypomagnesemia is not rare among non-dialysis CKD patients despite their decreased glomerular filtration rates; the prevalence rate was about 15% even in CKD stages G4 and G5. Among several potential causes of hypomagnesemia, tubular dysfunction/interstitial fibrosis may play a pivotal role in the development of hypomagnesemia in CKD, which impairs tubular magnesium reabsorption. Magnesium deficiency may, in turn, be involved in the progression of CKD. An in vitro study has revealed that magnesium deficiency aggravates tubular cell death and inflammation induced by phosphate load. In a cohort study of patients with CKD, low-serum magnesium levels enhanced the risk of end-stage kidney disease related to high-serum phosphate levels, suggesting a close relationship between magnesium deficiency and phosphate toxicity. More importantly, magnesium has a potent capacity to inhibit the calcification of vascular smooth muscle cells induced by phosphate. A randomized trial has shown the efficacy of oral magnesium oxide in retarding the progression of coronary artery calcification among non-dialysis CKD patients. Thus, magnesium might provide better cardiovascular prognosis; indeed, hemodialysis patients with mild hypermagnesemia exhibited the lowest mortality rate. Further randomized trials are needed to assess the impact of magnesium in terms of hard clinical outcomes among CKD patients.

Serum Calcification Propensity and Calcification of the Abdominal Aorta in Patients With Primary Aldosteronism

Patients with primary aldosteronism (PA) are more susceptible to cardiovascular disease and mortality than patients with primary hypertension. This is mostly attributed to excess production of aldosterone and its effects on the development of vascular injury. A novel functional test (T₅₀) measures serum calcification propensity. Lower T₅₀-values predict higher cardiovascular risk. We investigated serum calcification propensity and vascular calcification in PA and resistant hypertension (RH). T₅₀ measurement was performed in patients with PA (n = 66) and RH (n = 28) at baseline and after 403 (279–640) and 389 (277–527) days of treatment. No significant differences in T₅₀-values were observed between the groups (371 ± 65 and 382 ± 44 min, in PA and RH group, respectively, p > 0.05). However, higher aldosterone-to-renin ratios were associated with lower T₅₀-values in PA-patients (r −0.282, p < 0.05). Furthermore, lower T₅₀-values were associated with increased abdominal aortic calcification measured by Agatston score in PA (r −0.534, p < 0.05). In both, PA and RH, higher atherosclerotic cardiovascular disease (ACSVD) scores (r −0.403, p < 0.05) and lower HDL (r 0.469, p < 0.05) was related to lower T₅₀-values in a linear regression model. Adrenalectomy or medical treatment did not increase T₅₀-values. In comparison to patients with stable T₅₀-values, PA patients with a decrease in T₅₀ after intervention had higher serum calcium concentrations at baseline (2.24 ± 0.11 vs. 2.37 ± 0.10 mmol/l, p < 0.05). This decline of T₅₀-values at follow-up was also associated with a decrease in serum magnesium (−0.03 ± 0.03 mmol/l, p < 0.05) and an increase in phosphate concentrations (0.11 ± 0.11 mmol/l, p < 0.05). Resistant hypertension patients with a decrease in T₅₀-values at follow-up had a significantly lower eGFR at baseline. In summary, these data demonstrate an association between a high aldosterone-to-renin ratio and low T₅₀-values in PA. Moreover, lower T₅₀-values are associated with higher ACSVD scores and more pronounced vascular calcification in PA. Thus, serum calcification propensity may be a novel modifiable risk factor in PA.

Genetic Determinants of Serum Calcification Propensity and Cardiovascular Outcomes in the General Population

Background:

Serum calciprotein particle maturation time (T50), a measure of vascular calcification propensity, is associated with cardiovascular morbidity and mortality. We aimed to identify genetic loci associated with serum T50 and study their association with cardiovascular disease and mortality.

Methods:

We performed a genome-wide association study of serum T50 in 2,739 individuals of European descent participating in the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) study, followed by a two-sample Mendelian randomization (MR) study to examine causal effects of T50 on cardiovascular outcomes. Finally, we examined associations between T50 loci and cardiovascular outcomes in 8,566 community-dwelling participants in the Rotterdam study.

Results:

We identified three independent genome-wide significant single nucleotide polymorphism (SNPs) in the AHSG gene encoding fetuin-A: rs4917 (p = 1.72 × 10−101), rs2077119 (p = 3.34 × 10−18), and rs9870756 (p = 3.10 × 10−8), together explaining 18.3% of variation in serum T50. MR did not demonstrate a causal effect of T50 on cardiovascular outcomes in the general population. Patient-level analyses revealed that the minor allele of rs9870756, which explained 9.1% of variation in T50, was associated with a primary composite endpoint of all-cause mortality or cardiovascular disease [odds ratio (95% CI) 1.14 (1.01–1.28)] and all-cause mortality alone [1.14 (1.00–1.31)]. The other variants were not associated with clinical outcomes. In patients with type 2 diabetes or chronic kidney disease, the association between rs9870756 and the primary composite endpoint was stronger [OR 1.40 (1.06–1.84), relative excess risk due to interaction 0.54 (0.01–1.08)].

Conclusions:

We identified three SNPs in the AHSG gene that explained 18.3% of variability in serum T50 levels. Only one SNP was associated with cardiovascular outcomes, particularly in individuals with type 2 diabetes or chronic kidney disease.

The Effects of Oral Sodium Bicarbonate on Renal Function and Cardiovascular Risk in Patients with Chronic Kidney Disease: A Systematic Review and Meta-Analysis

OBJECTIVE

Oral sodium bicarbonate is often used to correct acid-base disturbance in patients with chronic kidney disease (CKD). However, there is little evidence on patient-level benign outcomes to support the practice.

METHODS

We conducted a systematic review and meta-analysis to examine the efficacy and safety of oral sodium bicarbonate in CKD patients. A total of 1853 patients with chronic metabolic acidosis or those with low-normal serum bicarbonate (22-24 mEq/L) were performed to compare the efficacy and safety of oral sodium bicarbonate in patients with CKD.

RESULTS

There was a significant increase in serum bicarbonate level (MD 2.37 mEq/L; 95% CI, 1.03 to 3.72) and slowed the decline in estimated glomerular filtration rate (eGFR) (MD -4.44 mL/min per 1.73 m2, 95% CI, -4.92 to -3.96) compared with the control groups. The sodium bicarbonate lowered T50-time, an indicator of vascular calcification (MD -20.74 min; 95% CI, -49.55 to 8.08); however, there was no significant difference between the two groups. In addition, oral sodium bicarbonate dramatically reduced systolic blood pressure (MD -2.97 mmHg; 95% CI, -5.04 to -0.90) and diastolic blood pressure (MD -1.26 mmHg; 95% CI, -2.33 to -0.19). There were no statistically significant body weight, urine pH and mean mid-arm muscle circumference.

CONCLUSION

Treatment of metabolic acidosis with sodium bicarbonate may slow the decline rate of kidney function and potentially significantly improve vascular endothelial function in patients with CKD.

PROSPERO REGISTRATION NUMBER

CRD42020207185.

Calcification Propensity in Serum and Cardiovascular Outcome in Peripheral Artery Disease

Peripheral artery disease (PAD) has been shown to be linked to elevated cardiovascular risk. The novel T₅₀ test quantifies calcification propensity of serum and has been associated with cardiovascular events and mortality in patients with chronic kidney disease (CKD) and in the general population. This study investigated the association of calcification propensity measured by the T₅₀ test in 287 patients with PAD without severe CKD. Major cardiovascular events (MACEs) including nonfatal stroke and nonfatal myocardial infarction and all-cause death (MACE + ) were evaluated after a median follow-up of 4 years and long-term cardiovascular and all-cause mortality after a median follow-up of 8.7 years by Kaplan-Meier and Cox regression analyses. Mean T₅₀ time was 268 ± 63 minutes in the study cohort (age 69 ± 10 years, 32% women, 47% diabetes). Low T₅₀ values that signify high calcification propensity were significantly associated with the occurrence of MACE+ (hazard ratio [HR]: 0.72; 95% confidence interval [CI]: 0.55-0.94). This association sustained multivariate adjustment for cardiovascular risk factors (CVRFs), Fontaine PAD stage, and prevalent media sclerosis (HR: 0.65; CI: 0.47-0.91). Cardiovascular mortality was significantly associated with T₅₀ after multivariate adjustment for CVRF (HR: 0.72; CI 0.53-0.99), but not all-cause mortality (HR: 0.80; CI: 0.64-1.01). In conclusion, calcification propensity associates with MACE+ and cardiovascular mortality in patients with PAD.

Gender-Related Differences in Chronic Kidney Disease-Associated Vascular Calcification Risk and Potential Risk Mediators: A Scoping Review

Vascular calcification (VC) involves the deposition of calcium apatite in vascular intima or media. Individuals of advanced age, having diabetes mellitus or chronic kidney disease (CKD) are particularly at risk. The pathogenesis of CKD-associated VC evolves considerably. The core driver is the phenotypic change involving vascular wall constituent cells toward manifestations similar to that undergone by osteoblasts. Gender-related differences are observed regarding the expressions of osteogenesis-regulating effectors, and presumably the prevalence/risk of CKD-associated VC exhibits gender-related differences as well. Despite the wealth of data focusing on gender-related differences in the risk of atherosclerosis, few report whether gender modifies the risk of VC, especially CKD-associated cases. We systematically identified studies of CKD-associated VC or its regulators/modifiers reporting data about gender distributions, and extracted results from 167 articles. A significantly higher risk of CKD-associated VC was observed in males among the majority of original investigations. However, substantial heterogeneity exists, since multiple large-scale studies yielded neutral findings. Differences in gender-related VC risk may result from variations in VC assessment methods, the anatomical segments of interest, study sample size, and even the ethnic origins of participants. From a biological perspective, plausible mediators of gender-related VC differences include body composition discrepancies, alterations involving lipid profiles, inflammatory severity, diversities in matrix Gla protein (MGP), soluble Klotho, vitamin D, sclerostin, parathyroid hormone (PTH), fibroblast growth factor-23 (FGF-23), and osteoprotegerin levels. Based on our findings, it may be inappropriate to monotonously assume that male patients with CKD are at risk of VC compared to females, and we should consider more background in context before result interpretation.

Phosphate and fibroblast growth factor 23 in diabetes

Diabetes is associated with a strongly elevated risk of cardiovascular disease, which is even more pronounced in patients with diabetic nephropathy. Currently available guideline-based efforts to correct traditional risk factors are only partly able to attenuate this risk, underlining the urge to identify novel treatment targets. Emerging data point towards a role for disturbances in phosphate metabolism in diabetes. In this review, we discuss the role of phosphate and the phosphate-regulating hormone fibroblast growth factor 23 (FGF23) in diabetes. We address deregulations of phosphate metabolism in patients with diabetes, including diabetic ketoacidosis. Moreover, we discuss potential adverse consequences of these deregulations, including the role of deregulated phosphate and glucose as drivers of vascular calcification propensity. Finally, we highlight potential treatment options to correct abnormalities in phosphate and FGF23. While further studies are needed to more precisely assess their clinical impact, deregulations in phosphate and FGF23 are promising potential target in diabetes and diabetic nephropathy.

The Emerging Role of Nutraceuticals in Cardiovascular Calcification: Evidence from Preclinical and Clinical Studies

Cardiovascular calcification is the ectopic deposition of calcium-phosphate crystals within the arterial wall and the aortic valve leaflets. This pathological process leads to increased vascular stiffness, reduced arterial elasticity, and aortic valve stenosis, increasing the risk of cardiovascular diseases. Although cardiovascular calcification is an increasing health care burden, to date no medical therapies have been approved for treating or preventing it. Considering the current lack of therapeutic strategies and the increasing prevalence of cardiovascular calcification, the investigation of some nutraceuticals to prevent this pathological condition has become prevalent in recent years. Recent preclinical and clinical studies evaluated the potential anti-calcific role of nutraceuticals (including magnesium, zinc, iron, vitamin K, and phytate) in the progression of vascular calcification, providing evidence for their dietary supplementation, especially in high-risk populations. The present review summarizes the current knowledge and latest advances for nutraceuticals with the most relevant preclinical and clinical data, including magnesium, zinc, iron, vitamin K, and phytate. Their supplementation might be recommended as a cost-effective strategy to avoid nutritional deficiency and to prevent or treat cardiovascular calcification. However, the optimal dose of nutraceuticals has not been identified and large interventional trials are warranted to support their protective effects on cardiovascular disease.

Propensity for Calcification in Serum Associates With 2-Year Cardiovascular Mortality in Ischemic Heart Failure With Reduced Ejection Fraction

Background: The propensity of serum to calcify, as assessed by the T₅₀-test, associates with mortality in patients with chronic kidney disease. In chronic heart failure, phosphate and fibroblast growth factor-23 (FGF-23), which are important components of the vascular calcification pathway, have been linked to patient survival. Here, we investigated whether T₅₀ associates with overall and cardiovascular survival in patients with chronic heart failure with reduced ejection fraction (HFrEF).

Methods: We measured T₅₀, intact and c-terminal FGF-23 levels in a cohort of 306 HFrEF patients. Associations with overall and cardiovascular mortality were analyzed in survival analysis and Cox-regression models.

Results: After a median follow-up time of 3.2 years (25th−75th percentile: 2.0–4.9 years), 114 patients (37.3%) died due to any cause and 76 patients (24.8%) died due to cardiovascular causes. 139 patients (45.4%) had ischemic and 167 patients (54.6%) had non-ischemic HFrEF. Patients with ischemic HFrEF in the lowest T₅₀-tertile had significantly greater 2-year cardiovascular mortality compared to patients in higher tertiles (p = 0.011). In ischemic but not in non-ischemic HFrEF, T₅₀ was significantly associated with cardiovascular mortality in univariate (p = 0.041) and fully adjusted (p = 0.046) Cox regression analysis. Significant associations of intact and c-terminal FGF-23 with all-cause and cardiovascular mortality in univariate Cox regression analysis did not remain significant after adjustment for confounding factors.

Conclusion: T₅₀ is associated with 2-year cardiovascular mortality in patients with ischemic HFrEF but not in non-ischemic HFrEF. More research on the role of T₅₀ measurements in coronary artery disease is warranted.

Calciprotein Particles: Balancing Mineral Homeostasis and Vascular Pathology

[Figure: see text].

Calciprotein Particles Cause Endothelial Dysfunction under Flow

Calciprotein particles (CPPs), which increasingly arise in the circulation during the disorders of mineral homeostasis, represent a double-edged sword protecting the human organism from extraskeletal calcification but potentially causing endothelial dysfunction. Existing models, however, failed to demonstrate the detrimental action of CPPs on endothelial cells (ECs) under flow. Here, we applied a flow culture system, where human arterial ECs were co-incubated with CPPs for 4 h, and a normolipidemic and normotensive rat model (10 daily intravenous injections of CPPs) to simulate the scenario occurring in vivo in the absence of confounding cardiovascular risk factors. Pathogenic effects of CPPs were investigated by RT-qPCR and Western blotting profiling of the endothelial lysate. CPPs were internalised within 1 h of circulation, inducing adhesion of peripheral blood mononuclear cells to ECs. Molecular profiling revealed that CPPs stimulated the expression of pro-inflammatory cell adhesion molecules VCAM1 and ICAM1 and upregulated transcription factors of endothelial-to-mesenchymal transition (Snail, Slug and Twist1). Furthermore, exposure to CPPs reduced the production of atheroprotective transcription factors KLF2 and KLF4 and led to YAP1 hypophosphorylation, potentially disturbing the mechanisms responsible for the proper endothelial mechanotransduction. Taken together, our results suggest the ability of CPPs to initiate endothelial dysfunction at physiological flow conditions.