Secondary Calciprotein Particles Research Articles

Inhibition of skeletal muscle differentiation by calciprotein particles in human primary myoblasts.

Sarcopenia is a common complication of chronic kidney disease (CKD) and has a detrimental effect on prognosis. Previous studies have explored the role of secondary calciprotein particles (CPP2) in determining the progression of complications and poor outcomes in patients with CKD. However, no study has demonstrated that CPP2 impairs skeletal myogenesis. Our study revealed that CPP2 exposure inhibits skeletal myogenesis by suppressing myotube formation and expression of skeletal muscle-specific myosin heavy chain and actin in human primary myoblasts. Moreover, CPP2 exposure altered the expression patterns of lineage-determinative transcription factors responsible for regulating myotube differentiation marker genes. This study first demonstrated that CPP2 interferes with myoblast differentiation and myotube formation in vitro.

#372 Cross-sectional association between serum magnesium with cognition in patients undergoing hemodialysis: the Osaka Dialysis Complication Study

Abstract Background and Aims Impaired cognitive performance is common in patients with chronic kidney disease including those undergoing haemodialysis, although the mechanisms are not well understood by which chronic kidney disease affects cognitive function. Phosphate plays an important role in the development of aging phenotypes particularly in patients with chronic kidney disease. Phosphate toxicity is thought to be mediated by calciprotein particles, and a shorter T50 reflects a higher propensity of transformation of primary to secondary calciprotein particles. T50 is known to be affected by phosphate, fetuin-A, magnesium, and others. We examined possible relationship between cognitive function and CKD-MBD-related factors in patients undergoing haemodialysis. Method This was a cross-sectional study in 1207 patients on maintenance haemodialysis selected from the participants of Osaka Dialysis Complication Study (ODCS). Cognitive function was assessed by Modified Mini-Mental State examination (3MS). Associations of serum calcium, phosphate, intact PTH, magnesium, fetuin-A, and T50 with 3MS was examined by multiple regression models adjusted for age, sex, dialysis vintage, diabetic kidney disease, prior stroke, prior non-stroke cardiovascular disease, education level, SBP, DBP, Hb, BMI, serum albumin, and CRP. Results Serum magnesium and phosphate levels were significantly and positively associated with 3MS level independent of the potential confounders, whereas other factors were not. Conclusion We found positive associations of cognitive performance with serum magnesium and phosphate levels in haemodialysis patients, suggesting the roles of CKD-MBD-related factors in impaired cognition in this population.

Association of calciprotein particles with serum phosphorus among patients undergoing conventional and extended-hours haemodialysis.

Extended-hours haemodialysis (HD) is associated with better clinical outcomes than conventional HD. We investigated whether extended-hours HD and conventional HD have varying effects on blood levels of calciprotein particles (CPPs) and phosphorus, which have been identified as major pathogenic molecules for vascular calcification. Patients who underwent conventional or extended in-centre daytime HD between January and March 2020 were included. Plasma CPP levels, representing only secondary CPPs (CPP-II), were measured in pre-dialysis samples. Linear and non-linear associations between CPPs and serum phosphorus levels were examined across dialysis modalities. A total of 382 participants (185 undergoing extended-hours HD and 197 undergoing conventional HD) were included in the analysis. The median age of participants was 71years, 65% of the patients were men and the mean phosphorus level was 5.4mg/dl. Plasma CPP (CPP-II) levels were lower in the extended-hours HD group than in the conventional HD group [40018(arbitrary units) AU versus 75728AU; P<.01]. Multivariable linear regression analysis showed that extended-hours HD was associated with lower natural logarithmic plasma CPP (CPP-II) levels: -0.64 (95% confidence interval -0.74 to -0.55). A restricted cubic spline function indicated that extended-hours HD was associated with lower plasma CPP (CPP-II) levels across levels of serum phosphorus, with significant differences observed between groups, especially in hyperphosphataemic conditions (P for interaction <.01). The extended-hours HD group had lower CPP levels than the conventional HD group despite no significant differences in serum phosphorus levels, which may contribute to better clinical outcomes in patients on extended-hours HD.

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

IntroductionSerum calcification propensity (T50 time) is associated with mortality in dialysis patients. Several solitary interventions improve T50, but whether a combination of interventions yields further increases in T50 is unknown. We hypothesized that a combination of two interventions, namely increasing magnesium concentration while simultaneously substituting acetate for citrate in the dialysis fluid, leads to increases in T50 values. MethodsIn a randomized, controlled trial, 60 chronic hemodialysis patients 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 endpoint was the difference in T50 times between the S group and the Cit+Mg0.75 group. ResultsThere was no significant difference in T50 time between the S group compared to the Cit+Mg0.75 group (236 ± 77 vs. 265 ± 97 minutes, p=0.23). The size of secondary calciprotein particles (CPP-2Rh) 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). ConclusionThe combination of citrate-buffer with increased magnesium concentration in dialysate does not improve T50.

Differential associations of fetuin-A and calcification propensity with cardiovascular events and subsequent mortality in patients undergoing hemodialysis.

Fetuin-A inhibits precipitation of calcium-phosphate crystals by forming calciprotein particles (CPP). A novel T50 test, which measures transformation time from primary to secondary CPP, is an index for calcification propensity. Both lower fetuin-A and shorter T50 levels were associated with cardiovascular disease (CVD) risk in patients with chronic kidney disease (CKD). Extremely high risk for CVD death in advanced CKD patients consists of high-incidental CVD event and high mortality after CVD event. To date, it is unclear whether fetuin-A and/or T50 can equally predict each CVD outcome. This prospective cohort study examined patients undergoing maintenance hemodialysis. The exposures were fetuin-A and T50. The outcomes of interests were new CVD events and subsequent deaths. The patients were categorized into tertiles of fetuin-A or T50 (T1 to T3). We identified 190 new CVD events during the 5-year follow-up of the 513 patients and 59 deaths subsequent to the CVD events during 2.5-year follow-up. A lower fetuin-A but not T50 was significantly associated with new CVD events [subdistribution hazard ratio (HR) 1.73, 95% confidence interval (CI) 1.15-2.61, P=.009 for T1 vs T3]. In contrast, a shorter T50 but not fetuin-A was a significant predictor of deaths after CVD events (HR 3.31, 95% CI 1.42-7.74, P=.006 for T1+T2 vs T3). A lower fetuin-A was predictive of new CVD events, whereas a shorter T50 was more preferentially associated with subsequent death. These results indicate that fetuin-A and T50 are involved in cardiovascular risk in different manners.

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.

Bisphosphonate FYB-931 Prevents High Phosphate-Induced Vascular Calcification in Rat Aortic Rings by Altering the Dynamics of the Transformation of Calciprotein Particles.

Patients with chronic kidney disease develop vascular calcification, owing to impaired calcium and phosphate metabolism. The prevention of vascular calcification is important to improve the prognosis of such patients. In this study, we investigated whether treatment with FYB-931, a novel bisphosphonate compound, prevents vascular calcification in rat aortic rings cultured in high-phosphate medium for 9 days, assessed by measurement of the calcium content and the degree of calcium deposition, visualized using von Kossa staining. The effect on the transformation of calciprotein particles (CPPs) from primary to secondary CPPs was assessed using a fluorescent probe-based flow cytometric assay. FYB-931 dose-dependently prevented high phosphate-induced aortic calcification, but failed to rapidly cause the regression of high phosphate-induced vascular calcification once it had developed. Furthermore, the treatment dose-dependently inhibited the high phosphate-induced transformation from primary to secondary CPPs. In addition, the treatment with FYB-931 prevented the transformation from primary to secondary CPPs in vitamin D3-treated rats as a model of ectopic calcification, consistent with the results from rat aortic rings. In conclusion, treatment with FYB-931 prevents high phosphate-induced rat aortic vascular calcification by altering the dynamics of CPP transformation. This finding suggests that inhibition of the transformation from primary to secondary CPPs is an important target for the prevention of vascular calcification in patients with chronic kidney disease.

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.

Reduction of Calciprotein Particles in Adults Receiving Infliximab for Chronic Inflammatory Disease.

ABSTRACTPatients with chronic inflammatory diseases (CID) experience accelerated loss of bone mineral density, which is often accompanied by increased vascular calcification. These disturbances can be attenuated by therapies for inflammation, such as the tumor necrosis factor inhibitor infliximab. Calciprotein particles (CPP) are circulating colloidal aggregates of calcium and phosphate together with the mineral‐binding protein fetuin‐A, which have emerged as potential mediators of vascular calcification. The precise origins of serum CPP are unclear, but bone turnover may be an important source. In this longitudinal observational study, we studied patients with CID undergoing treatment with infliximab to assess the temporal relationship between bone turnover and circulating CPP. Ten patients with active CID receiving infliximab induction therapy and an additional 3 patients with quiescent CID on maintenance infliximab therapy were studied for 8 weeks with repeated measures of bone turnover markers as well as CPP (calciprotein monomers [CPM], primary CPP [CPP‐I], and secondary CPP [CPP‐II]). Therapeutic response was appraised using validated disease activity scores. At baseline, those with active CID had elevated markers of bone resorption and suppressed bone formation markers as well as higher CPM and CPP‐I compared with those with quiescent CID. In responders, there was an early but transient reduction in resorption markers by week 1, but a more sustained increase in bone formation markers compared with non‐responders at week 8. This was accompanied by reductions in CPM (β = −6.5 × 103 AU [95% CI −11.1, −1.8], p = 0.006) and CPP‐I (β = −23.4 × 104 particles/mL [95% CI −34.8, −11.9], p < 0.001). In contrast, no significant changes in any markers were observed in non‐responders or those receiving maintenance therapy. Thus, CPP have a dynamic association with changes in bone turnover in response to infliximab therapy, adding to accumulating evidence of the role of bone as a determinant of systemic levels. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Effects of fetuin-A-containing calciprotein particles on posttranslational modifications of fetuin-A in HepG2 cells

Fetuin-A is an inhibitor of ectopic calcification that is expressed mainly in hepatocytes and is secreted into the circulation after posttranslational processing, including glycosylation and phosphorylation. The molecular weight (MW) of fully modified fetuin-A (FM-fetuin-A) is approximately 60 kDa in an immunoblot, which is much higher than the estimated MW by amino acid sequence. Under conditions of calcification stress such as advanced stage chronic kidney disease, fetuin-A prevents calcification by forming colloidal complexes, which are referred to as calciprotein particles (CPP). Since the significance of CPP in this process is unclear, we investigated the effect of synthetic secondary CPP on the level of FM-fetuin-A in HepG2 cells. Secondary CPP increased the level of FM-fetuin-A in dose- and time-dependent manners, but did not affect expression of mRNA for fetuin-A. Treatment with O- and/or N-glycosidase caused a shift of the 60 kDa band of FM-fetuin-A to a lower MW. Preincubation with brefeldin A, an inhibitor of transport of newly synthesized proteins from the endoplasmic reticulum to the Golgi apparatus, completely blocked the secondary CPP-induced increase in FM-fetuin-A. Treatment with BAPTA-AM, an intracellular calcium chelating agent, also inhibited the CPP-induced increase in the FM-fetuin-A level. Secondary CPP accelerate posttranslational processing of fetuin-A in HepG2 cells.

CD11b Signaling Prevents Chondrocyte Mineralization and Attenuates the Severity of Osteoarthritis.

Osteoarthritis (OA) is a progressive joint disease that is strongly associated with calcium-containing crystal formation (mineralization) by chondrocytes leading ultimately to cartilage calcification. However, this calcification process is poorly understood and treatments targeting the underlying disease mechanisms are lacking. The CD11b/CD18 integrin (Mac-1 or αMβ2), a member of the beta 2 integrin family of adhesion receptors, is critically involved in the development of several inflammatory diseases, including rheumatoid arthritis and systemic lupus erythematosus. We found that in a collagen-induced arthritis, CD11b-deficient mice exhibited increased cartilage degradation compared to WT control animals. However, the functional significance of CD11b integrin signaling in the pathophysiology of chondrocytes remains unknown. CD11b expression was found in the extracellular matrix and in chondrocytes in both healthy and damaged human and murine articular cartilage. Primary murine CD11b KO chondrocytes showed increased mineralization when induced in vitro by secondary calciprotein particles (CPP) and quantified by Alizarin Red staining. This increased propensity to mineralize was associated with an increased alkaline phosphatase (Alp) expression (measured by qRT-PCR and activity assay) and an enhanced secretion of the pro-mineralizing IL-6 cytokine compared to control wild-type cells (measured by ELISA). Accordingly, addition of an anti-IL-6 receptor antibody to CD11b KO chondrocytes reduced significantly the calcification and identified IL-6 as a pro-mineralizing factor in these cells. In the same conditions, the ratio of qRT-PCR expression of collagen X over collagen II, and that of Runx2 over Sox9 (both ratio being indexes of chondrocyte hypertrophy) were increased in CD11b-deficient cells. Conversely, the CD11b activator LA1 reduced chondrocyte mineralization, Alp expression, IL-6 production and collagen X expression. In the meniscectomy (MNX) model of murine knee osteoarthritis, deficiency of CD11b led to more severe OA (OARSI scoring of medial cartilage damage in CD11b: 5.6 ± 1.8, in WT: 1.2 ± 0.5, p < 0.05, inflammation in CD11b: 2.8 ± 0.2, in WT: 1.4 ± 0.5). In conclusion, these data demonstrate that CD11b signaling prevents chondrocyte hypertrophy and chondrocyte mineralization in vitro and has a protective role in models of OA in vivo.

Associations of Serum Calciprotein Particle Size and Transformation Time With Arterial Calcification, Arterial Stiffness, and Mortality in Incident Hemodialysis Patients

Characteristics of the transformation of primary to secondary calciprotein particles (CPPs) in serum, including the size of secondary CPP (CPP2) aggregates and the time of transformation (T50), may be markers for arterial calcification in patients undergoing hemodialysis (HD). We examined the associations of CPP2 aggregate size and T50 with arterial calcification in incident HD patients. Prospective cohort study. Incident HD patients (n=402with available CPP2 measures and n=388with available T50 measures) from the Predictors of Arrhythmic and Cardiovascular Risk in End-Stage Renal Disease (PACE) Study PREDICTORS: Serum CPP2 size and T50 at baseline. Primary outcomes were baseline coronary artery and thoracic aorta calcifications. Exploratory outcomes included baseline arterial stiffness, measured by pulse wave velocity (PWV) and ankle brachial index, and longitudinally, repeat measures of PWV and all-cause mortality. Tobit regression, multiple linear regression, Poisson regression, linear mixed-effects regression, and Cox proportional hazards regression. Mean age was 55±13 years, 41% were women, 71% were Black, and 57% had diabetes mellitus. Baseline CPP2 size and T50 were correlated with baseline fetuin A level (r=-0.59 for CPP2 and 0.44 for T50; P<0.001 for both), but neither was associated with baseline measures of arterial calcification or arterial stiffness. Baseline CPP2 size and T50 were not associated with repeat measures of PWV. During a median follow-up of 3.5 (IQR, 1.7-6.2) years, larger CPP2 was associated with higher risk for mortality (HR, 1.17 [95% CI, 1.05-1.31] per 100nm larger CPP2 size) after adjusting for demographics and comorbid conditions, but there was no association between baseline T50 and risk for mortality. Possible imprecision in assays, small sample size, limited generalizability to incident HD populations with different racial composition, and residual confounding. In incident HD patients, neither CPP2 size nor T50 was associated with prevalent arterial calcification and stiffness. Larger CPP2 was associated with risk for mortality, but this finding needs to be confirmed in future studies.

Serum Calcification Propensity in Children on Chronic Hemodialysis

Serum Calcification Propensity in Children on Chronic Hemodialysis

Calciprotein Particles and Serum Calcification Propensity: Hallmarks of Vascular Calcifications in Patients with Chronic Kidney Disease.

Cardiovascular complications are one of the leading causes of mortality worldwide and are strongly associated with atherosclerosis and vascular calcification (VC). Patients with chronic kidney disease (CKD) have a higher prevalence of VC as renal function declines, which will result in increased mortality. Serum calciprotein particles (CPPs) are colloidal nanoparticles that have a prominent role in the initiation and progression of VC. The T50 test is a novel test that measures the conversion of primary to secondary calciprotein particles indicating the tendency of serum to calcify. Therefore, we accomplished a comprehensive review as the first integrated approach to clarify fundamental aspects that influence serum CPP levels and T50, and to explore the effects of CPP and calcification propensity on various chronic disease outcomes. In addition, new topics were raised regarding possible clinical uses of T50 in the assessment of VC, particularly in patients with CKD, including possible opportunities in VC management. The relationships between serum calcification propensity and cardiovascular and all-cause mortality were also addressed. The review is the outcome of a comprehensive search on available literature and could open new directions to control VC.

SUN-097 APOA1-MIMETIC PEPTIDES ENHANCE CELLULAR CLEARANCE OF CALCIPROTEIN PARTICLES AND ATTENUATE INFLAMMATORY PRIMING

Calciprotein particles (CPP) - colloidal nanoaggregates of calcium phosphate mineral, proteins and other biomolecules - have emerged as potential mediators of pro-inflammatory mineral stress in CKD. Transformation of CPP to the crystalline state (secondary CPP), as favoured by uraemia, enhances their inflammatory potential due to an enrichment of endogenous and bacteria-derived cargos that are able to ligate the innate immune sensor, Toll-like receptor 4 (TLR4). Unless overwhelmed, rapid removal of particles from the cell surface by scavenger receptor (SR)-A-mediated endocytosis restrains activation of TLR4 and licensing of downstream inflammatory cascades. Strategies aimed at augmenting immunologically-inert clearance of CPP by SR-A may abrogate the reaction to chronic mineral excess and lessen the inflammatory burden in CKD. However, in order to test whether exploiting such pathways may be beneficial, the native ligand for SR-A needed to be identified. We used a combination of genetic and biochemical approaches to elucidate the ligand for SR-A-mediated endocytosis of secondary CPP. Ligand-depleted sera were generated by immunoaffinity chromatography. CPP were synthesized in uraemic human serum supplemented with supersaturating concentrations of calcium and phosphate salts, isolated by gel filtration chromatography and dosed according to concentrations determined by nanoparticle tracking analysis (NTA). We used flow cytometry and live-cell confocal imaging to monitor the binding and internalisation of fluorescently-labelled CPP in BM-derived WT and SR-A-deficient murine macrophages as well as in human lines in which either SR-A or TLR4 had been deleted using CRISPR/Cas9 technology. A peptide mimetic of the ligand was synthesised along with scrambled control peptides. NFkB induction was evaluated using a luciferase reporter and inflammatory cytokine mRNA expression by qPCR. Ripening of CPP crystalline state is associated with an enrichment of Apo-A1. Exposure of human macrophage to labelled CPP synthesised in serum depleted of Apo-A1, resulted in an 80% decrease in cell-associated fluorescence relative to CPP from Apo-A1-replete serum. A similar reduction in uptake of Apo-A1-replete CPP2 was observed in macrophage derived from SR-A-/- mice and SR-A knockout human macrophage relative to their respective wild-type controls. Two patients with genetically confirmed Apo-A1 deficiency were found to have modestly elevated serum CPP levels compared to age- and gender-matched controls (n=20), but a markedly increased CPP-2 to CPP-1 ratio, consistent with an important role for Apo-A1 in CPP2 metabolism. Compared with Apo-A1-replete CPP2, those synthesised from Apo-A1-depleted, uraemic serum induced greater NFkB induction and cytokine mRNA levels (TNF-alpha & IL-6) at equivalent doses, but not in TLR4-knockout cells. Addition of an 18mer Apo-A1 mimetic peptide dose-dependently increased CPP2 uptake in macrophage, but this effect was absent in murine and human cells lacking SR-A. Reconstitution of Apo-A1-deplted CPP2 with mimetic peptide restored uptake and inhibited inflammatory signalling. Therapeutic enhancement of SR-A-dependent CPP uptake using Apo-A1 mimetics may help ameliorate the inflammatory response to chronic mineral dysregulation∖

The effect of increasing dialysate magnesium on calciprotein particles, inflammation and bone markers: post hoc analysis from a randomized controlled clinical trial.

The formation of calciprotein particles (CPPs) may be an important component of the humoral defences against ectopic calcification. Although magnesium (Mg) has been shown to delay the transition of amorphous calcium-/phosphate-containing primary CPP (CPP-1) to crystalline apatite-containing secondary CPP (CPP-2) ex vivo, effects on the endogenous CPP pool are unknown. We used post hoc analyses from a randomized double-blind parallel-group controlled clinical trial of 28 days treatment with high dialysate Mg of 2.0 mEq/L versus standard dialysate Mg of 1.0 mEq/L in 57 subjects undergoing maintenance hemodialysis for end-stage kidney disease. CPP load, markers of systemic inflammation and bone turnover were measured at baseline and follow-up. After 28 days of treatment with high dialysate Mg, serum total CPP (-52%), CPP-1 (-42%) and CPP-2 (-68%) were lower in the high Mg group (all P < 0.001) but were unchanged in the standard dialysate Mg group. Tumour necrosis factor-α (-20%) and interleukin-6 (-22%) were also reduced with high dialysate Mg treatment (both P < 0.01). High dialysate Mg resulted in higher levels of bone-specific alkaline phosphatase (a marker of bone formation) (+17%) but lower levels of tartrate-resistant acid phosphatase 5 b (a marker of bone resorption; -33%) (both P < 0.01). Inflammatory cytokines and bone turnover markers were unchanged in the standard dialysate Mg group over the same period. In this exploratory analysis, increasing dialysate Mg was associated with reduced CPP load and systemic inflammation and divergent changes in markers of bone formation and resorption.

Serum Calcification Propensity and Clinical Events in CKD.

Patients with CKD are at high risk for cardiovascular disease, ESKD, and mortality. Vascular calcification is one pathway through which cardiovascular disease risks are increased. We hypothesized that a novel measure of serum calcification propensity is associated with cardiovascular disease events, ESKD, and all-cause mortality among patients with CKD stages 2-4. Among 3404 participants from the prospective, longitudinal Chronic Renal Insufficiency Cohort Study, we quantified calcification propensity as the transformation time (T50) from primary to secondary calciprotein particles, with lower T50 corresponding to higher calcification propensity. We used multivariable-adjusted Cox proportional hazards regression models to assess the associations of T50 with risks of adjudicated atherosclerotic cardiovascular disease events (myocardial infarction, stroke, and peripheral artery disease), adjudicated heart failure, ESKD, and mortality. The mean T50 was 313 (SD 79) minutes. Over an average 7.1 (SD 3.1) years of follow-up, we observed 571 atherosclerotic cardiovascular disease events, 633 heart failure events, 887 ESKD events, and 924 deaths. With adjustment for traditional cardiovascular disease risk factors, lower T50 was significantly associated with higher risk of atherosclerotic cardiovascular disease (hazard ratio [HR] per SD lower T50, 1.14; 95% confidence interval [95% CI], 1.05 to 1.25), ESKD within 3 years from baseline (HR per SD lower T50, 1.68; 95% CI, 1.52 to 1.86), and all-cause mortality (HR per SD lower T50, 1.16; 95% CI, 1.09 to 1.24), but not heart failure (HR per SD lower T50, 1.06; 95% CI, 0.97 to 1.15). After adjustment for eGFR and 24-hour urinary protein, T50 was not associated with risks of atherosclerotic cardiovascular disease, ESKD, and mortality. Among patients with CKD stages 2-4, higher serum calcification propensity is associated with atherosclerotic cardiovascular disease events, ESKD, and all-cause mortality, but this association was not independent of kidney function. This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2019_10_28_CJN04710419.mp3.

Serum Calcification Propensity and Coronary Artery Calcification Among Patients With CKD: The CRIC (Chronic Renal Insufficiency Cohort) Study

Coronary artery calcification (CAC) is prevalent among patients with chronic kidney disease (CKD) and increases risks for cardiovascular disease events and mortality. We hypothesized that a novel serum measure of calcification propensity is associated with CAC among patients with CKD stages 2 to4. Prospective cohort study. Participants from the Chronic Renal Insufficiency Cohort (CRIC) Study with baseline (n=1,274) and follow-up (n=780) CAC measurements. Calcification propensity, quantified as transformation time (T50) from primary to secondary calciprotein particles, with lower T50 corresponding to higher calcification propensity. Covariates included age, sex, race/ethnicity, clinical site, estimated glomerular filtration rate, proteinuria, diabetes, systolic blood pressure, number of antihypertensive medications, current smoking, history of cardiovascular disease, total cholesterol level, and use of statin medications. CAC prevalence, severity, incidence, and progression. Multivariable-adjusted generalized linear models. At baseline, 824 (65%) participants had prevalent CAC. After multivariable adjustment, T50 was not associated with CAC prevalence but was significantly associated with greater CAC severity among participants with prevalent CAC: 1-SD lower T50 was associated with 21% (95% CI, 6%-38%) greater CAC severity. Among 780 participants followed up an average of 3 years later, 65 (20%) without baseline CAC developed incident CAC, while 89 (19%) with baseline CAC had progression, defined as annual increase≥100 Agatston units. After multivariable adjustment, T50 was not associated with incident CAC but was significantly associated with CAC progression: 1-SD lower T50 was associated with 28% (95% CI, 7%-53%) higher risk for CAC progression. Potential selection bias in follow-up analyses; inability to distinguish intimal from medial calcification. Among patients with CKD stages 2 to 4, higher serum calcification propensity is associated with more severe CAC and CAC progression.

Abstract P063: Serum Calcification Propensity and Cardiovascular Disease Events Among Patients With Chronic Kidney Disease: the CRIC Study

Introduction: Patients with chronic kidney disease (CKD) are at high risk for cardiovascular disease (CVD) events and vascular calcification is one pathway by which risk is increased. Hypothesis: We assessed the hypothesis that a novel measure of serum calcification propensity is associated with CVD events among patients with CKD stages 2-4. Methods: Among 3397 participants from the prospective longitudinal Chronic Renal Insufficiency Cohort (CRIC) Study, calcification propensity was quantified at baseline as the transformation time (T 50 ) from primary to secondary calciprotein particles, with lower T 50 corresponding to higher calcification propensity. CVD events are reported every six months and confirmed by medical record adjudication. Multivariable-adjusted Cox proportional hazards regression models, stratified by study site, were used to assess the associations of T 50 with risks of atherosclerotic CVD events (myocardial infarction, stroke, and peripheral artery disease) and congestive heart failure (CHF) events. Results: Over an average 7.1-year follow-up, we observed 571 atherosclerotic CVD events (312 myocardial infarction, 120 stroke, and 139 peripheral artery disease events) and 633 CHF events. The mean (standard deviation) T 50 was 313.4 (79.1) minutes. After adjustment for traditional CVD risk factors, lower T 50 was significantly associated with higher risk of atherosclerotic CVD, but not with risk of CHF. The addition of T 50 modestly improved atherosclerotic CVD event discrimination beyond ACC/AHA atherosclerotic CVD risk score variables (c-statistic 0.713 vs. 0.710; p&lt;0.001). Adjustment for kidney function attenuated the association between T 50 and CVD events (Table). Conclusions: Among patients with CKD stages 2-4, higher serum calcification propensity is significantly associated with atherosclerotic CVD events, but not with CHF events. Future studies should evaluate whether T 50 and its determinants represent novel therapeutic targets.

Serum Calcification Propensity and Fetuin-A: Biomarkers of Cardiovascular Disease in Kidney Transplant Recipients

Background: “T50,” shortened transformation time from primary to secondary calciprotein particles may reflect deranged mineral metabolism predisposing to vascular calcification and cardiovascular disease (CVD). The glycoprotein fetuin-A is a major T50 determinant. Methods: The Folic Acid For Vascular Outcome Prevention In Transplantation (FAVORIT) cohort is a completed, large, multiethnic controlled clinical trial cohort of chronic, stable kidney transplant recipients (KTRs). We conducted a longitudinal case-cohort analysis using a randomly selected subcohort of patients, and all individual cases who developed CVD. Serum T50 and fetuin-A were determined in this total of n = 685 FAVORIT trial participants at randomization. Results: During a median surveillance of 2.18-years, 311 incident or recurrent CVD events occurred. Shorter T50 (minutes) or reduced fetuin-A concentrations (g/L) were associated with CVD after adjustment for treatment assignment, systolic blood pressure, age, sex, race, preexisting CVD and diabetes, smoking, body mass index, total cholesterol/HDL cholesterol, kidney allograft vintage and type, calcineurin inhibitor, or lipid-lowering drug use, estimated glomerular filtration rate, and urinary albumin/creatinine: tertile 1 (lowest) to tertile 3 (highest) comparisons, T50, (hazard ratio [HR] 1.86; 95% CI 1.20–2.89); fetuin-A, (HR 2.25; 95% CI 1.38–3.69). Elevated high sensitivity c-reactive protein (hsCRP) was an effect modifier of both these associations. Conclusions: Shortened T50, as well as reduced fetuin-A levels, ostensible promoters of vascular calcification, remained associated with greater risk for CVD outcomes, after adjustment for major CVD risk factors, measures of kidney function and damage, and KTR clinical characteristics and demographics, in a large, multiethnic cohort of long-term KTRs. Increased hsCRP was an effect modifier of these CVD risk associations.