Protective effects of spironolactone on vascular calcification in chronic kidney disease.

BACKGROUND: Vascular calcification is common in chronic kidney disease (CKD) and associated with increased cardiovascular mortality. Aldosterone has been implicated as an augmenting factor in the progression of vascular calcification. The present study further explored putative beneficial effects of aldosterone inhibition by the mineralocorticoid receptor antagonist spironolactone on vascular calcification in CKD. METHODS: Serum calcification propensity was determined in serum samples from the MiREnDa trial, a prospective, randomized controlled clinical trial to investigate efficacy and safety of spironolactone in maintenance hemodialysis patients. Experiments were conducted in mice with subtotal nephrectomy and cholecalciferol treatment, and in calcifying primary human aortic smooth muscle cells (HAoSMCs). RESULTS: Serum calcification propensity was improved by spironolactone treatment in patients on hemodialysis from the MiREnDa trial. In mouse models and HAoSMCs, spironolactone treatment ameliorated vascular calcification and expression of osteogenic markers. CONCLUSIONS: These observations support a putative benefit of spironolactone treatment in CKD-associated vascular calcification. Further research is required to investigate possible improvements in cardiovascular outcomes by spironolactone and whether the benefits outweigh the risks in patients with CKD.

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 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.

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.

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 T50­indicative of a higher calcification propensity­was 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.

Association between Serum Zinc and Calcification Propensity (T50) in Patients with Type 2 Diabetes Mellitus and In Vitro Effect of Exogenous Zinc on T50.

Zinc inhibits vascular calcification in vivo and in vitro. Patients with type 2 diabetes mellitus show hypozincemia and are at an elevated risk of cardiovascular events. Recently, an in vitro test (T50-test) was developed for determination of serum calcification propensity and a shorter T50 means a higher calcification propensity. This cross-sectional study investigated the association between serum zinc and T50 in 132 type 2 diabetes mellitus patients with various kidney functions. Furthermore, the effect of exogenous zinc on T50 was also investigated in vitro using separately pooled serum samples obtained from healthy volunteers and patients with hemodialysis. We measured T50 levels using the established nephelometric method. The median (interquartile range) levels of T50 and serum zinc were 306 (269 to 332) min, and 80.0 (70.1 to 89.8) µg/dL, respectively. Serum zinc level showed a weak, but positive correlation with T50 (rs = 0.219, p = 0.012). This association remained significant in multivariable-adjusted analysis, and was independent of known factors including phosphate, calcium, and magnesium. Kidney function and glycemic control were not significantly associated with T50. Finally, in vitro experiments showed that addition of a physiological concentration of exogenous zinc chloride significantly increased serum T50. Our results indicate that serum zinc is an independent factor with a potential role in suppressing calcification propensity in serum.

Favourable serum calcification propensity with intraperitoneal as compared with subcutaneous insulin administration in type 1 diabetes.

BACKGROUND: Serum calcification propensity can be monitored using the maturation time of calciprotein particles in serum (T50 test). A shorter T50 indicates greater propensity to calcify; this is an independent determinant of cardiovascular disease. As the intraperitoneal (IP) route of insulin administration mimics the physiology more than the subcutaneous (SC) route in persons with type 1 diabetes (T1DM), we hypothesized that IP insulin influences determinants of calcium propensity and therefore result in a longer T50 than SC insulin administration. METHODS: Prospective, observational case-control study. Measurements were performed at baseline and at 26 weeks in age and gender matched persons with T1DM. RESULTS: A total of 181 persons, 39 (21.5%) of which used IP and 142 (78.5%) SC insulin were analysed. Baseline T50 was 356 (45) minutes. The geometric mean T50 significantly differed between both treatment groups: 367 [95% confidence interval (CI) 357, 376] for the IP group and 352 (95% CI 347, 357) for the SC group with a difference of -15 (95% CI -25, -4) minutes, in favour of IP treatment. In multivariable analyses, the IP route of insulin administration had a positive relation on T50 concentrations while higher age, triglycerides and phosphate concentrations had an inverse relation. CONCLUSION: Among persons with T1DM, IP insulin administration results in a more favourable calcification propensity time then SC insulin. It has yet to be shown if this observation translates into improved cardiovascular outcomes.

Serum calcification propensity in type 1 diabetes associates with mineral stress.

AIMS: Increased vascular calcification could be an underlying mechanism of cardiovascular complications in type 1 diabetes mellitus (T1DM). Calcificationpropensitycan be monitored by the maturation time of calciprotein particles in serum (T50 test). A high calcification propensity (i.e. low T50-value) is an independent determinant of mortality in various populations. Aim was to investigate T50levels with indices of calcium metabolism and disease status in T1DM patients. METHODS: As part of a prospective cohort study, T1DM patients were examined annually. At baseline T50 was determined in 216 (77%) patients (57% male) with a mean age of 45 (12) years, diabetes duration 22 [15.8, 30.4] years and HbA1c of 60 (12) mmol/mol (7.6 (1.0) %). Baseline data were collected in 2002 and follow-up data were collected in 2018. RESULTS: The T50 time was normally distributed with a mean of 339 (60) minutes. Patients in the highest tertile of T50 (range 369-466) were older, had lower phosphate and PTH and higher magnesium and vitamin D concentrations as compared to the middle (range 317-368) and lowest (range 129-316) tertiles, while eGFR was comparable between groups. During follow-up of 15 years, 43 patients developed a macrovascular complication and 26 patients died. In regression analysis, T50 was not a prognostic factor for the development of complications or mortality. CONCLUSIONS: The T50 time was associated with indices of increased mineral stress, but not with the development of long-term macrovascular complications.