Medial Calcification Research Articles

Role of Matrix Gla Protein in the Complex Network of Coronary Artery Disease: A Comprehensive Review.

Coronary artery disease (CAD) is widely recognized as one of the most important clinical entities. In recent years, a large body of accumulated data suggest that coronary artery calcification, a process highly prevalent in patients with CAD, occurs via well-organized biologic processes, rather than passively, as previously regarded. Matrix Gla protein (MGP), a vitamin K-dependent protein, emerged as an important inhibitor of both intimal and medial vascular calcification. The functionality of MGP hinges on two post-translational modifications: phosphorylation and carboxylation. Depending on the above-noted modifications, various species of MGP may exist in circulation, each with their respective level of functionality. Emerging data suggest that dysfunctional species of MGP, markedly, dephosphorylated-uncarboxylated MGP, might find its application as biomarkers of microvascular health, and assist in clinical decision making with regard to initiation of vitamin K supplementation. Hence, in this review we summarized the current knowledge with respect to the role of MGP in the complex network of vascular calcification with concurrent inferences to CAD. In addition, we discussed the effects of warfarin use on MGP functionality, with concomitant implications to coronary plaque stability.

MicroRNA-103a regulates the calcification of vascular smooth muscle cells by targeting runt-related transcription factor 2 in high phosphorus conditions.

Vascular calcification, such as atherosclerosis, is a serious complication of chronic kidney disease that is characterized by tunica media calcification, and has gained increasing attention from researchers. The commonly observed association between vascular calcification and osteoporosis suggests a link between bone and vascular disorders. As microRNAs (miRNAs) have a wide range of gene regulation functions, such as cell proliferation, apoptosis, stress and transdifferentiation, the current study aimed to determine whether miRNAs play a vital role in the calcification and osteoblastic differentiation of rat thoracic aorta vascular smooth muscle cells (VSMCs). Gene expression analysis was performed on seven miRNAs (miR-29a, -30b, -103a, -125b, -133a, -143 and -211) that maybe potentially involved in the differentiation of smooth muscle cells into osteoblastic cells. The results showed that the levels of miR-29a, -30b, -103a, -125b and -143 were markedly reduced in the VSMC calcification model, particularly miR-103a, whereas runt-related transcription factor 2 (RUNX2) expression was increased. Furthermore, it was found that the expression of RUNX2 was significantly decreased following the upregulation of miR-103a, and that the expression of RUNX2 was significantly increased by downregulating miR-103a in VSMCs. Therefore, it was concluded that miR-103a plays a notable role in the transdifferentiation of the VSMCs in high phosphorus-induced calcification by targeting the regulation of RUNX2, and may therefore constitute a new target for the diagnosis and treatment of vascular calcification.

Understanding the Clinical Implications of Intracranial Arterial Calcification Using Brain CT and Vessel Wall Imaging.

Background and Purpose: Intracranial arterial calcification (IAC) has been the focus of much attention by clinicians and researchers as an indicator of intracranial atherosclerosis, but correlations of IAC patterns (intimal or medial) with the presence of atherosclerotic plaques and plaque stability are still a matter of debate. Our study aimed to assess the associations of IAC patterns identified on computed tomography (CT) with the presence of plaque detected on vessel wall magnetic resonance imaging and plaque stability.Materials and Methods: Patients with stroke or transient ischemic attack and intracranial artery stenosis were recruited. IAC was detected and localized (intima or media) on non-contrast CT images. Intracranial atherosclerotic plaques were identified using vessel wall magnetic resonance imaging and matched to corresponding CT images. Associations between IAC patterns and culprit atherosclerotic plaques were assessed by using multivariate regression.Results: Seventy-five patients (mean age, 63.4 ± 11.6 years; males, 46) were included. Two hundred and twenty-one segments with IAC were identified on CT in 66 patients, including 86 (38.9%) predominantly intimal calcifications and 135 (61.1%) predominantly medial calcifications. A total of 72.0% of intimal calcifications coexisted with atherosclerotic plaques, whereas only 10.2% of medial calcifications coexisted with plaques. Intimal calcification was more commonly shown in non-culprit plaques than culprit plaques (25.9 vs. 9.4%, P = 0.008). The multivariate mixed logistic regression adjusted for the degree of stenosis showed that intimal calcification was significantly associated with non-culprit plaques (OR, 2.971; 95% CI, 1.036–8.517; P = 0.043).Conclusion: Our findings suggest that intimal calcification may indicate the existence of a stable form of atherosclerotic plaque, but plaques can exist in the absence of intimal calcification especially in the middle cerebral artery.

The intraoperative intravascular lithotripsy to recruit a calcified radial artery for creating a distal radio-cephalic fistula.

Guidelines for vascular access recommend that the distal autogenous arteriovenous fistula (AVF) should be the first choice-access procedure for patients starting dialysis. Arteriosclerosis of radial artery may cause early failure, as well as failure of maturation of distal arteriovenous fistulas. To increase the incidence of distal AVFs, our team, specialized in vascular access surgery from 2004 onwards, has introduced Intraoperative Transluminal Angioplasty (ITA) under ultrasound (UG) or fluoroscopic guidance, to recruit inadequate arterials for creating distal fistulas. Intravascular lithotripsy (IL) is a novel approach to treat luminal and medial calcifications in patients with peripheral arterial disease and coronary disease. We believe that intraoperative IL may be an opportunity to recruit calcified radial arteries for creating distal radio-cephalic fistulas. Purpose of this study is to describe the intraoperative IL technical applied in our clinical experience. A 37-year-old diabetic patient with distal radio-cephalic fistula was recruited for the first IL experience. One year ago, a wrist radio-cephalic fistula was created in the right upper limb, with intraoperative UG radial artery angioplasty for extensive calcifications. The fistula was functioning but showed a delay in maturation. An angioplasty was unsuccessfully attempted to facilitate the maturation. Subsequently, a surgical revision of the fistula was performed, creating a new anastomosis immediately upstream of the previous one by performing an intraoperative IL UG of the radial artery. The fistula was immediately well functioning, and was cannulated with two needles after 1 month. It is currently being used with intradialytic adequate blood flow. The positive outcome of the case described in this paper, even if only anecdotal, could act as a trigger for further experiences with IL.

Regulatory role of mammalian target of rapamycin signaling in exosome secretion and osteogenic changes in smooth muscle cells lacking acid ceramidase gene

Acid ceramidase (murine gene code: Asah1) (50kDa) belongs to N-terminal nucleophile hydrolase family. This enzyme is located in the lysosome, which mediates conversion of ceramide (CER) into sphingosine and free fatty acids at acidic pH. CER plays an important role in intracellular sphingolipid metabolism and its increase causes inflammation. The mammalian target of rapamycin complex 1 (mTORC1) signaling on late endosomes (LEs)/lysosomes may control cargo selection, membrane biogenesis, and exosome secretion, which may be fine controlled by lysosomal sphingolipids such as CER. This lysosomal-CER-mTOR signaling may be a crucial molecular mechanism responsible for development of arterial medial calcification (AMC). Torin-1 (5mg/kg/day), an mTOR inhibitor, significantly decreased aortic medial calcification accompanied with decreased expression of osteogenic markers like osteopontin (OSP) and runt-related transcription factor 2 (RUNX2) and upregulation of smooth muscle 22α (SM22-α) in mice receiving high dose of Vitamin D (500000IU/kg/day). Asah1fl/fl /SMCre mice had markedly increased co-localization of mTORC1 with lysosome-associated membrane protein-1 (Lamp-1) (lysosome marker) and decreased co-localization of vacuolar protein sorting-associated protein 16 (VPS16) (a multivesicular bodies [MVBs] marker) with Lamp-1, suggesting mTOR activation caused reduced MVBs interaction with lysosomes. Torin-1 significantly reduced the co-localization of mTOR vs Lamp-1, increased lysosome-MVB interaction which was associated with reduced accumulation of CD63 and annexin 2 (exosome markers) in the coronary arterial wall of mice. Using coronary artery smooth muscle cells (CASMCs), Pi -stimulation significantly increased p-mTOR expression in Asah1fl/fl /SMCre CASMCs as compared to WT/WT cells associated with increased calcium deposition and mineralization. Torin-1 blocked Pi -induced calcium deposition and mineralization. siRNA mTOR and Torin-1 significantly reduce co-localization of mTORC1 with Lamp-1, increased VPS16 vs Lamp-1 co-localization in Pi -stimulated CASMCs, associated with decreased exosome release. Functionally, Torin-1 significantly reduces arterial stiffening as shown by restoration from increased pulse wave velocity and decreased elastin breaks. These results suggest that lysosomal CER-mTOR signaling may play a critical role for the control of lysosome-MVB interaction, exosome secretion and arterial stiffening during AMC.

MO583IN VITRO AND EX VIVO EXPERIMENTS OF VASCULAR CALCIFICATION

Abstract Background and Aims Vascular calcification (VC) is one major complication in patients with chronic kidney disease whereas a misbalance in calcium and phosphate metabolism plays a crucial role. The mechanisms underlying VC have not been entirely revealed to date. Therefore are the studies aiming at the identification and characterization of the mediators/uremic toxins involved in VC ongoing and highly relevant. However, currently many different protocols being used in the studies of vascular calcification processes. This complicates the comparison of study outcomes, composing systematic reviews, and meta-analyses. Moreover, the reproducibility of data is hampered, and the efficiency in calcification research through the lack of a standardized protocol is reduced. In this study, we developed a standardized operating protocol for in vitro and ex vivo approaches to aiming at the comparability of these studies. Method We analysed in vitro and ex vivo experimental conditions to study VC. Vascular smooth muscle cells (HAoSMCs) were used for in vitro experiments and aortas from Wistar rats were used for ex vivo experiments. The influence of the following conditions was studied in detail: • Phosphate and calcium concentrations in calcifying media. • Incubation time. • Fetal calf serum (FCS) concentration. The degree of calcification was estimated by quantification of calcium concentrations that were normalized to protein content (in vitro) or to the dry weight of the aortic ring (ex vivo). Additionally, the aortic rings were stained using the von Kossa method. Optimal conditions for investigating medial vascular calcification were detected and summarized in the step-by-step protocol. Results We were able to demonstrate that the degree and the location of VC in vascular smooth muscle cells and aortic rings were highly dependent on the phosphate and CaCl2 concentration in the medium as well as the incubation time. Furthermore, the VC was reduced upon increasing fetal calf serum concentration in the medium. An optimized protocol for studying vascular calcification in vitro and ex vivo was developed and validated. The final protocol (Figure 1) presented will help to standardize in vitro and ex vivo approaches to investigate the processes of vascular calcification. Conclusion In the current study, we developed and validated a standardized operating protocol for systematic in vitro and ex vivo analyses of medial calcification, which is essential for the comparability of the results of future studies.

MO009ROLE OF GDF-15, YKL-40, AND MMP-9 IN PATIENTS WITH ESKD: FOCUS ON SEX SPECIFIC ASSOCIATIONS WITH VASCULAR OUTCOMES AND ALL-CAUSE MORTALITY

Abstract Background and Aims This study was performed on behalf of the GOING-FWD Consortium. The importance of sex difference in the development of cardiovascular complications is well appreciated, however, further studies are warranted to assess if sex specific pathophysiological changes occur under uremic environment. Little is known about the relationship between the uremic phenotype and novel cardiovascular biomarkers like growth differentiation factor 15 (GDF-15), cartilage glycoprotein 39 (YKL-40), and matrix metalloproteinase 9 (MMP9), and if they have a sex specific effects in relation to inflammation, vascular remodelling, cardiovascular outcomes and all-cause mortality. Therefore, we hypothesise that there is a sex specific relationship between GDF-15, YKL-40, MMP9 and vascular outcomes defined as athero-/arteriosclerosis and vascular calcification. Method ESKD patients (n = 231), males (n = 152) and females (n = 79), not receiving renal replacement therapy were selected from two ongoing prospective CKD cohorts from the Division of Renal Medicine, Karolinska University Hospital, Sweden. Three putative CVD biomarkers, GDF-15, YKL-40 and MMP9 were analysed using enzyme-linked immunosorbent assay (ELISA) kits. Biomarker level/activity was analysed in the context of gut microbiota derived TMAO, vascular calcification (determined as CAC score on CT scans, aortic valve calcification (AVC) and medial calcification on epigastric artery biopsies), inflammatory response, oxidative stress and all-cause mortality. Results The levels of investigated biomarkers have not differed between female and male patients with ESKD. However, GDF-15 correlated with TMAO in females from more severe cohort that are not receiving renal replacement therapy yet, whereas in males increased GDF-15 level was associated with higher Agatston score on CT-scans, inflammatory biomarker (IL-6) and oxidative stress biomarker 8-OHdG. None of biomarkers was related to intimal medial calcification assessed in epigastric artery biopsies. Comorbidity analysis revealed elevated GDF-15 levels in both females and males, while increased MMP-9 levels were observed only in females with diabetes mellitus, but not with CVD. When assessing death of any cause in our cohorts, both deceased males and females had higher GDF-15 concentration (p = 0.01 and p < 0.001, respectively), meanwhile only YKL-40 level was increased in deceased males (p = 0.02). Conclusion In summary, here we report that in males GDF-15 and YKL-40 were related to vascular calcification, inflammageing and oxidative stress, while in females the relationship of GDF-15 with TMAO was observed. Higher MMP-9 level was seen in males without diabetes and in females with confirmed diabetes mellitus. YKL-40 increase in males and GDF-15 in both males and females were associated with all-cause mortality. Our findings suggest that sex specific associations exist and those could have a potential to affect development of cardiovascular complications in patients with ESKD.

MO441CALPROTECTIN IS A NOVEL CONTRIBUTING FACTOR IN VASCULAR CALCIFICATION AND A PREDICTOR OF CARDIOVASCULAR OUTCOME IN CKD PATIENTS*

Abstract Background and Aims Vascular calcification, leading to aortic stiffening and heart failure, is decisive risk factor for cardiovascular (CV) mortality in patients with chronic kidney disease (CKD). Promoted by bone mineral disorder and systemic inflammation in CKD patients, vascular calcification is a complex mechanism involving osteochondrogenic differentiation of vascular smooth muscle cells (VSMCs) and abnormal deposition of minerals in the vascular wall. Despite intensive research efforts in recent years, available treatments have limited effect and none of them prevent or reverse vascular calcification. The aim of this study was to analyse the serum proteome of CKD stage 3-4 patients in order to unravel new molecular changes associated to CV morbid-mortality and to decipher the role of novel candidates on vascular calcification to provide potential new therapeutic agents. Method In this study we used serum samples from two independent cohorts: 112 CKD stage 3-4 patients with a 4 years follow-up for CV events and 222 CKD stage 5 patients exhibiting a broad range of calcification degree determined by histological quantification in the epigastric and/or iliac artery. Serum proteome analysis was performed using tandem mass-spectrometry in a subcohort of 66 CKD3-4 patients and validation of protein candidates was performed using ELISA in the two full cohorts. Human primary vascular smooth muscle cells and mouse aortic rings were used for calcification assays. Calcium content was quantified using QuantiChrom calcium assay kit and calcium deposition was visualized by Alizarin Red and Von Kossa staining. Results Among 443 proteins detected in the serum of CKD3-4 patients, 134 displayed significant modified abundance in patients with CV events (n=32) compared to patients without (n=34). One of the most prominent changes was increased level of calprotectin (up to 8.6 fold, P<.0001). Using ELISA, we validated that higher serum calprotectin levels were strongly associated with higher probability of developing CV complications and increased mortality in CKD stage 3-4 patients (Figure A). Moreover, we showed that higher serum calprotectin was associated with increased vascular calcification levels in CKD stage 5 patients (Figure B). In vitro, calprotectin promoted calcification of human VSMCs (p<0.0001) (Figures C-D) and in mouse aortic rings (p<0.0001) (Figure E-F). Interestingly, these effects were significantly attenuated by paquinimod, a calprotectin inhibitor (Figures C-F). Conclusion Circulating calprotectin is a novel predictor of CV outcome and mortality in CKD patients. Calprotectin also shows calcification-inducing properties and its blockade by paquinimod alleviates its effects. Future experiments will consist in deciphering the signalling pathways involved in the regulation of calcification by calprotectin and evaluating in vivo the therapeutic potential of paquinimod on the development of medial vascular calcification lesions associated with CKD.

MO750THE COMBINED PROGNOSTIC SIGNIFICANCE OF ALKALINE PHOSPHATASE AND INTRA-CRANIAL ARTERIAL CALCIFICATIONS IN HEMODIALYSIS PATIENTS

Abstract Background and Aims Intra-cranial arterial calcification (ICAC) in hemodialysis (HD) patients has a prevalence of about 90%, and its severity is correlated with age, hemodialysis vintage and mineral bone disease. Elevated concentrations of calcium and phosphorus are not sufficient to induce medial calcification because of inhibition by pyrophosphate. Alkaline Phosphatase (ALP) promotes vascular calcification by hydrolyzing pyrophosphate. Epigenetic mechanisms regulation by Apabetalone downregulates pathways involved in vascular calcification. This study assessed the combined impact of ICAC and elevated serum ALP on mortality among chronic HD patients. Method vascular calcifications represented by ICAC were measured simultaneous with mineral bone disease parameters including serum ALP of chronic HD patients who underwent non-contrast brain computerized tomography (CT) from 2015 to 2018 in our institution. Results This retrospective study included 153 hemodialysis patients (mean age 71.3±12.1 years, 60.1% male). Of the total cohort, 12(7.8%) had no brain calcifications and 69 (45.1%) had multiple intracranial calcifications. Considering the patients with normal ALP and no calcification as the reference group yielded adjusted odds ratios for all-cause mortality of 4.6 (95%CI 1.7-12.7) among patients with brain calcifications and normal ALP, p=0.003, and odds ratios for all-cause mortality of 6.1 (95%CI 2.1-17.7) among patients with brain calcifications and increased ALP. Conclusion We founded an independent association between ICAC and the risk of death among hemodialysis patients. The combined effect of ICAC and increased ALP was significantly associated with higher odds-ratio for all-cause mortality in chronic HD patients and may contribute to the risk stratification of these patients.

MO578OSTEOCALCIN AND VASCULAR CALCIFICATION IN HEMODIALYSIS PATIENTS: AN OBSERVATIONAL COHORT STUDY

Abstract Background and Aims Vascular calcification contributes to morbidity and mortality in patients with ESRD on maintenance hemodialysis. to study the relationship between osteocalcin and vascular calcification. Method 160 patients with ESRD on maintenance hemodialysis and 60 age-and sex-matched healthy controls were recruited. Serum vitamin K2 and osteocalcin both intact and undercarboxylated were measured. Transthoracic echocardiography was done for valvular calcification and thickening, and carotid duplex was done for carotid intimal medial calcification and thickening. Results Hemodialysis patients have higher median serum vitamin K2 (p<0.001), higher undercarboxylated osteocalcin (p<0.001). Only older age, duration of hypertension, and duration of established cardiovascular disease are associated with carotid media-intimal calcification. Old age is a strong predictor of carotid media intimal thickening. Female sex is associated with valvular thickening. Conclusion Functional vitamin K deficiency is present in maintenance hemodialysis patients and serum osteocalcin is not associated with cardiovascular calcification.

Free Deoxycholic Acid Exacerbates Vascular Calcification in CKD through ER Stress-Mediated ATF4 Activation.

Our metabolome approach found that levels of circulating, free deoxycholic acid (DCA) is associated with the severity of vascular calcification in patients with CKD. However, it is not known whether DCA directly causes vascular calcification in CKD. Using various chemicals and animal and cell culture models, we investigated whether the modulation of DCA levels influences vascular calcification in CKD. CKD increased levels of DCA in mice and humans by decreasing urinary DCA excretion. Treatment of cultured VSMCs with DCA but no other bile acids (BAs) induced vascular calcification and osteogenic differentiation through endoplasmic reticulum (ER) stress-mediated activating transcription factor-4 (ATF4) activation. Treatment of mice with Farnesoid X receptor (FXR)-specific agonists selectively reduced levels of circulating cholic acid-derived BAs, such as DCA, protecting from CKD-dependent medial calcification and atherosclerotic calcification. Reciprocal FXR deficiency and DCA treatment induced vascular calcification by increasing levels of circulating DCA and activating the ER stress response. This study demonstrates that DCA plays a causative role in regulating CKD-dependent vascular diseases through ER stress-mediated ATF4 activation.

Contribution of Enhancer of Zeste Homolog 2 gene in Calcification Nidus Formation and Exosome Release in Arterial Smooth Muscle Cells

Enhancer of zeste homolog 2 (Ezh2) as a histone methyltransferasehas been reported to epigenetically control gene expression, and it is known to be involved in phenotypic transition and osteogenesis, playing a critical role in multiple inflammatory diseases. Lysosomal transient receptor potential mucolipin 1 (TRPML1) channels regulating lysosome interaction with multivesicular bodies (MVBs) and consequent exosome release play a crucial role in the SMC phenotype transition to osteogenic during arterial medial calcification (AMC). However, there is lack of evidence to show whether Ezh2 participates in the phenotypic transition and vascular calcification process. The aim of this study was to determine the role of Ezh2 in high phosphate (Pi)-induced calcification and to explore its contribution to the phenotype change and exosome secretion in vascular smooth muscle cells (SMCs) that is essential for AMC. Using aortic SMCs isolated from SMC-specific Ezh2 knockout (Ezh2fl/fl/SMCre) mice and wild-type littermates, we demonstrated that high Pi treatment increased more calcium deposition in aortic SMCs as shown by the presence of Alizarin Red-stained nodules when Ezh2 gene is deleted or its activity is inhibited by GSK126. Further, this calcium deposition was significantly decreased by MLSA-1, a TRPML-1 channel agonist in these cells. Correspondingly, Ezh2 gene deletion induced phenotypic change in Pi-treated SMCs, as depicted by decreased SM22-α (SMC marker) and increased expression of osteogenic gene osteopontin in Western blot analysis, indicating that Ezh2 contributes to phenotype change in SMCs leading to calcification nidus formation. Using nanoparticle tracking analysis, Pi-induced secretion of exosomes (100-150 nm in size) were found significantly increased in SMCs, which was augmented by Ezh2 gene deletion or GSK126, or attenuated by MLSA-1. Similarly, GSK126 significantly increased calcification and exosome secretion in Pi-treated and human aortic SMCs (HASMCs), while MLSA-1 markedly decreased calcium deposition and exosome release in these cells. These results suggest that a normal expression of Ezh2 genecritically controls phenotype transition and exosome secretion in arterial SMCs and its defect or deficiency may be an important molecular mechanism leading to AMC.

Enhanced Arterial Stiffening in Obese Mice with Smooth Muscle‐Specific Overexpression of Smpd1 gene

Arterial stiffening is a risk factor for cardiovascular morbidity. Recent studies have shown that lysosomal ceramide contributed to the phenotype change and exosome secretion in arterial smooth muscle cells (SMCs) during the development of arterial medial calcification. The present study was designed to investigate whether lysosomal ceramide produced from acid sphingomyelinase (ASM) contributes to arterial stiffening in diet-induced obesity. It was found that in a diet-induced mouse model of obesity by feeding mice high fat diet (HF), arterial stiffness as measured in vivo using a high-resolution Doppler ultrasound imaging was significantly enhanced in mice with a transgene of ASM (its mouse gene code is Smpd1), namely, Smpd1trg/SMCre mice as compared to their wild type littermates (WT/WT). This obesity-induced enhancement of arterial stiffening was further strengthened by administration of high sucrose water (30%). Smpd1trg/SMCre mice on the HF diet or HF diet with high sucrose water (HFHS) showed significantly increased glucose levels as compared to WT/WT without significant difference in the body weight. By Masson Trichrome staining, we observed markedly increased collagen deposition in Smpd1trg/SMCre mice treated with HF diet, which was further increased in HFHS group of mice compared to WT/WT. Furthermore, Smpd1trg/SMCre mice treated with HF or HFHS were shown to have significant increase in the expression of exosome markers such as CD63 and annexin-II (AnX2) in the coronary arterial wall as compared to WT/WT mice. In the plasma of Smpd1trg/SMCre mice, the number of exosomes also significantly increased as compared to WT/WT mice either on normal, HF or HFHS diet. All these data indicate that a transgene of ASM in Smpd1trg/SMCre mice leads to increased glucose and collagen levels associated with augmented exosomes secretion that may contribute to the enhancement of arterial stiffening during diet-induced obesity.

The Thermodynamics of Medial Vascular Calcification.

Medial vascular calcification (MVC) is a degenerative process that involves the deposition of calcium in the arteries, with a high prevalence in chronic kidney disease (CKD), diabetes, and aging. Calcification is the process of precipitation largely of calcium phosphate, governed by the laws of thermodynamics that should be acknowledged in studies of this disease. Amorphous calcium phosphate (ACP) is the key constituent of early calcifications, mainly composed of Ca2+ and PO43– ions, which over time transform into hydroxyapatite (HAP) crystals. The supersaturation of ACP related to Ca2+ and PO43– activities establishes the risk of MVC, which can be modulated by the presence of promoter and inhibitor biomolecules. According to the thermodynamic parameters, the process of MVC implies: (i) an increase in Ca2+ and PO43– activities (rather than concentrations) exceeding the solubility product at the precipitating sites in the media; (ii) focally impaired equilibrium between promoter and inhibitor biomolecules; and (iii) the progression of HAP crystallization associated with nominal irreversibility of the process, even when the levels of Ca2+ and PO43– ions return to normal. Thus, physical-chemical processes in the media are fundamental to understanding MVC and represent the most critical factor for treatments’ considerations. Any pathogenetical proposal must therefore comply with the laws of thermodynamics and their expression within the medial layer.

POS-273 Antihypertensive treatment with a hydrochlorothiazide-based regimen enhances medial vascular calcification in CKD rats with mineral bone disorders

Increased arterial stiffness and medial vascular calcification are a major risk factors in patients with chronic kidney disease (CKD) due to mineral bone disorders (MBD). The impact of antihypertensive therapy on MBD-induced vascular calcification remains uncertain. The aim of the present study was to investigate whether the reduction in mean blood pressure reduces arterial stiffness and medial vascular calcification in CKD rats with MBD.

POS-746 PRE-KIDNEY TRANSPLANT MEDIAL ARTERIAL CALCIFICATION AND POST-TRANSPLANT HYPERTENSION BY A PROPENSITY SCORE WEIGHTING

Medial arterial calcification (MAC) is associated cardiovascular (CV) mortality in ESRD and kidney transplant patients partly from arterial stiffness. Its relationship with hypertension (HTN) is unclear can be confounded with factors. Female kidney transplant recipients were divided into 2 groups as per presence or absence MAC. The 2 groups were balanced based on age, race, cause of ESRD, type of donor (decreased or living donors), and pretransplant BMI and diabetes by using propensity score weighting. Association between MAC and post-transplant systolic and diastolic HTN (SHTN >130 or DHTN >80 mmHg, respectively) was examined by multiple logistic regression. Of 51 patients, mean age±SD was 57.08±10.47 years old. The majority were white (54.9%) followed by African American (35.3%) and others (9.8%) and 20 patients (39%) had pre-transplant MAC. Mean pretransplant SBP and DBP were 143.57±25.77 and 76.61±13.75 mmHg, respectively. Baseline characteristics including potential confounders were balanced by using propensity score weights estimated by a generalized boosted modeling (Figure 1 and 2). Among 20 patients in MAC group, 12 and 4 patients had SHTN and DHTN, respectively at 48 weeks posttransplantation (mean SBP 135.05±18.82 and DBP 71.53±8.65 mmHg); whereas, only 16 and 13 out of 31 patients in non-MAC had no SHTN and DHTN, respectively (mean SBP 129.87±17.18 and DBP 75.73±12.76 mmHg). After adjusted by age, race, cause of ESRD, dialysis modality, type of donor, induction immunosuppression, pretransplant BMI, SBP, DBP, diabetes, corrected calcium, and phosphorus, MAC group had 98 times lower the odds of having DHTN at 48-week posttransplantation compared to non-MAC group (odd ratio (OR) 0.02; 95%CI 0.0006 to 0.5031). However, MAC is associated with lower the odds of having SHTN but the association was not significant (OR 0.44; 95%CI 0.07 to 2.63). Pre-transplant MAC is associated with a long-term post-transplant DHTN, but not SHTN. This may be explained by arterial stiffness leading to decreased DBP. Since pretransplant MAC is a known associated risk for mortality in ESRD, it may not be reversible and causes carryover effect on the pathophysiology of posttransplant CV mortality.

ASSOCIATION BETWEEN PRE-TRANSPLANT MEDIAL ARTERIAL CALCIFICATION AND EARLY POST-KIDNEY TRANSPLANT HYPERTENSION FROM A PROPENSITY SCORE WEIGHTING ANALYSIS

Objective: Medial arterial calcification (MAC) detected by mammography (MG) is exclusively in the medial layer of the arteries and associated with cardiovascular (CV) outcomes in end-stage renal disease (ESRD) patients. Association between MAC and hypertension (HTN) after successful kidney transplantation (KT) is unclear. Design and method: Female KT patients with pre-KT MG was divided into MAC and non-MAC groups. Baseline characteristics including age, race, and pre-KT diabetes were balanced by propensity score weighting (PSW). Association between MAC and systolic HTN (SBP <130 mmHg) and diastolic HTN (DBP <80 mmHg) at a 24-week post-KT is examined by multiple logistic regression. Results: Of 51 KT candidates, mean age ± SD was 50.08 ± 10.47 years old and 18 patients (35.29%) were Black and the remaining non-Black were 33 (64.71%). Twenty patients (39.23%) had MAC and 21 patients (41.18%) had diabetes. Among 20 patients in MAC group, 14 and 7 patients had SHTN and DHTN at a 24-week post-KT, respectively; whereas, 17 out of 30 patients (missing 1 patient) in non-MAC group had both SHTN and DHTN (MAC vs. non-MAC for SHTN p 0.341 and for DHTN p 0.133). Compared to non-MAC group, MAC group had higher mean SBP (137.45 ± 18.52 vs. 130.70 ± 17.67; p 0.2060); whereas, its mean DBP was lower (74.15 ± 14.17 vs. 78.73 ± 10.55; p 0.2253). By using generalized boosted modeling-based PSW to balance baseline characteristics (Figure 1A&B) and adjusting for potential confounders including age, race, cause of kidney disease, pre-KT diabetes, serum albumin, corrected calcium, phosphorus, dialysis modality, type of KT, donor age, induction immunosuppressive medications, MAC group had 89% lower the odds of having DHTN compared to non-MAC group (OR 0.11; 95%CI 0.02 to 0.84). However, MAC group appeared to have higher, but not significant, risk for SBP (OR 2.24, 95%CI 0.35 to 14.46). Conclusions: KT patients with pre-KT MAC had lower the risk of developing DHTN during early post-KT period. DHTN, which indicates vascular stiffness and increases risk of CV mortality in ESRD, may not explain CV risk in KT recipients. Pathophysiology of DHTN and CV diseases in KT patients after successful KT may be different from ESRD population.

POS-272 DIFFERENTIAL EFFECTS OF ENDOTHELIN ETA RECEPTOR BLOCKADE ON VASCULAR CALCIFICATION AND RENAL INJURY IN RATS WITH CHRONIC KIDNEY DISEASE

Endothelin ETA receptor blockade has been shown to reduce arterial stiffness and calcification without affecting renal function in a rat model of chronic kidney disease (CKD). In the present study, we investigated the differential effects of ETAreceptor blockade on vascular calcification and renal injury in CKD rats. CKD was induced in Wistar rats by renal mass ablation. Then, vascular calcification was induced by mineral imbalance with a calcium/phosphate-rich diet and vitamin D supplementation (Ca/P/VitD). One group of CKD+Ca/P/VitD rats was given the ETAreceptor antagonist atrasentan (10 mg/kg/day) for 6 weeks. Hemodynamic parameters, including systolic blood pressure (SBP), pulse pressure (PP) and pulse wave velocity (PWV) were determined. The thoracic aorta and the remnant kidney were harvested to assess vascular calcification and remodeling, and renal injuries. As expected, CKD+Ca/P/VitD rats developed arterial medial calcification associated with increased PWV and PP, indicating enhanced arterial stiffness. Renal injuries were comprised of mild focal and segmental glomerular sclerosis, diffused tubular atrophy and cortical and medullary interstitial fibrosis and inflammation. Although ETA receptor blockade improved vascular stiffness and calcification, unexpectedly, atrasentan aggravated renal injuries, including the tubular atrophy and the interstitial fibrosis and inflammation. In this rat model of CKD with vascular calcification, ETA receptor blockade reduced vascular stiffness and calcification, did not improve renal function due to aggravation of renal histological injuries.

The combination of hemodynamic alterations and endothelial dysfunction accelerates arterial media calcification in warfarin administered rats

The combination of hemodynamic alterations and endothelial dysfunction accelerates arterial media calcification in warfarin administered rats

Breast Arterial Calcification: A Potential Biomarker for Atherosclerotic Cardiovascular Disease Risk?

We aimed to summarize the current evidence regarding the association between breast arterial calcification (BAC) and atherosclerotic cardiovascular disease (ASCVD) in women and discuss the potential role of BAC in the risk stratification and preventive approaches for ASCVD. BAC has emerged as a potential women-specific risk marker for ASCVD. Although BAC presents as a medial calcification of the arteries, notably different from the intimal atherosclerotic process, current evidence supports a correlation between BAC and ASCVD risk factors or subclinical and clinical ASCVD, such as coronary artery disease or stroke. As millions of women undergo mammograms each year, the potential clinical application of BAC in enhanced ASCVD risk estimation, with no additional cost or radiation, has tremendous appeal. Although further research regarding optimal risk assessment and management in women with BAC is required, the presence of BAC should prompt healthy cardiovascular lifestyle modifications.