A single injection of gain-of-function mutant PCSK9 adeno-associated virus vector induces cardiovascular calcification in mice with no genetic modification

BACKGROUND AND AIMS

Studying atherosclerotic calcification in vivo requires mouse models with genetic modifications. Previous studies showed that injection of recombinant adeno-associated virus vector (AAV) encoding a gain-of-function mutant PCSK9 into mice promotes atherosclerosis. We aimed to study cardiovascular calcification induced by PCSK9 AAV in C57BL/6J mice.

METHODS

10 week-old C57BL/6J mice received a single injection of AAV encoding mutant mPCSK9 (rAAV8/D377Y-mPCSK9). Ldlr(-/-) mice served as positive controls. Mice consumed a high-fat, high-cholesterol diet for 15 or 20 weeks. Aortic calcification was assessed by fluorescence reflectance imaging (FRI) of a near-infrared calcium tracer.

RESULTS

Serum levels of PCSK9 (0.14 μg/mL to 20 μg/mL, p < 0.01) and total cholesterol (82 mg/dL to 820 mg/dL, p < 0.01) increased within one week after injection and remained elevated for 20 weeks. Atherosclerotic lesion size was similar between PCSK9 AAV and Ldlr(-/-) mice. Aortic calcification was 0.01% ± 0.01 in PCSK9 AAV mice and 15.3% ± 6.1 in Ldlr(-/-) mice at 15 weeks (p < 0.01); by 20 weeks, the PCSK9 AAV mice aortic calcification grew to 12.4% ± 4.9. Tissue non-specific alkaline phosphatase activity was similar in PCSK9 AAV mice and Ldlr(-/-) mice at 15 and 20 weeks, respectively. As example of the utility of this model in testing modulators of calcification in vivo, PCSK9 AAV injection to sortilin-deficient mice demonstrated reduced aortic calcification by 46.3% (p < 0.05) compared to littermate controls.

CONCLUSIONS

A single injection of gain-of-function PCSK9 AAV into C57BL/6J mice is a useful tool to study cardiovascular calcification in mice with no genetic manipulation.

From skeletal to cardiovascular disease in 12 steps-the evolution of sclerostin as a major player in CKD-MBD

Canonical Wnt signaling activity contributes to physiological and adaptive bone mineralization and is an essential player in bone remodeling. Sclerostin is a prototypic soluble canonical Wnt signaling pathway inhibitor that is produced in osteocytes and blocks osteoblast differentiation and function. Therefore, sclerostin is a potent inhibitor of bone formation and mineralization. Accordingly, rodent sclerostin-deficiency models exhibit a strong bone phenotype. Moreover, blocking sclerostin represents a promising treatment perspective against osteoporosis. Beyond the bone field novel data definitely associate Wnt signaling in general and sclerostin in particular with ectopic extraosseous mineralization processes, as is evident in cardiovascular calcification or calciphylaxis. Uremia is characterized by parallel occurrence of disordered bone mineralization and accelerated cardiovascular calcification (chronic kidney disease - mineral and bone disorder, CKD-MBD), linking skeletal and cardiovascular disease-the so-called bone-vascular calcification paradox. In consequence, sclerostin may qualify as an emerging player in CKD-MBD. We present a stepwise review approach regarding the rapidly evolving field sclerostin participation in CKD-MBD. Starting from data originating in the classical bone field we look separately at three major areas of CKD-MBD: disturbed mineral metabolism, renal osteodystrophy, and uremic cardiovascular disease. Our review is intended to help the nephrologist revise the potential importance of sclerostin in CKD by focusing on how sclerostin research is gradually evolving from the classical osteoporosis niche into the area of CKD-MBD. In particular, we integrate the limited amount of available data in the context of pediatric nephrology.

Prevalence and risk factors for vascular calcification in Chinese patients receiving dialysis: baseline results from a prospective cohort study

OBJECTIVE

With limited data available on calcification prevalence in chronic kidney disease (CKD) patients on dialysis, the China Dialysis Calcification Study (CDCS) determined the prevalence of vascular/valvular calcification (VC) and association of risk factors in Chinese patients with prevalent hemodialysis (HD) or peritoneal dialysis (PD).

METHODS

CKD patients undergoing HD/PD for ≥6 months were enrolled. Prevalence data for calcification and medical history were documented at baseline. Coronary artery calcification (CAC) was assessed by electron beam or multi-slice computed tomography (EBCT/MSCT), abdominal aortic calcification (AAC) by lateral lumbar radiography, and cardiac valvular calcification (ValvC) by echocardiography. Serum phosphorus, calcium, intact parathyroid hormone (iPTH), and 25-hydroxyvitamin D and FGF-23 were evaluated. A logistic regression model was used to evaluate the association between risk factors and VC.

RESULTS

Of 1,497 patients, 1,493 (78.3% HD, 21.7% PD) had ≥1 baseline calcification image (final analysis cohort, FAC) and 1,423 (78.8% HD, 21.2% PD) had baseline calcification data complete (BCDC). Prevalence of VC was 77.4% in FAC (80.8% HD, 65.1% PD, p < .001) and 77.5% in BCDC (80.7% HD, 65.8% PD). The proportion of BCDC patients with single-site calcification were 20% for CAC, 4.3% for AAC, and 4.3% for cardiac valvular calcification (ValvC), respectively. Double site calcifications were 23.4% for CAC and AAC, 6.5% for CAC and ValvC, and 1.1% for AAC and ValvC, respectively. In total, 17.9% patients had calcification at all three sites.

CONCLUSIONS

High prevalence of total VC in Chinese CKD patients will supplement current knowledge, which is mostly limited, contributing in creating awareness and optimizing VC management.

Revisiting cardiovascular calcification: A multifaceted disease requiring a multidisciplinary approach

The presence of cardiovascular calcification significantly predicts patients' morbidity and mortality. Calcific mineral deposition within the soft cardiovascular tissues disrupts the normal biomechanical function of these tissues, leading to complications such as heart failure, myocardial infarction, and stroke. The realization that calcification results from active cellular processes offers hope that therapeutic intervention may prevent or reverse the disease. To this point, however, no clinically viable therapies have emerged. This may be due to the lack of certainty that remains in the mechanisms by which mineral is deposited in cardiovascular tissues. Gaining new insight into this process requires a multidisciplinary approach. The pathological changes in cell phenotype that lead to the physicochemical deposition of mineral and the resultant effects on tissue biomechanics must all be considered when designing strategies to treat cardiovascular calcification. In this review, we overview the current cardiovascular calcification paradigm and discuss emerging techniques that are providing new insight into the mechanisms of ectopic calcification.

TNAP as a therapeutic target for cardiovascular calcification: a discussion of its pleiotropic functions in the body

Cardiovascular calcification (CVC) is associated with increased morbidity and mortality. It develops in several diseases and locations, such as in the tunica intima in atherosclerosis plaques, in the tunica media in type 2 diabetes and chronic kidney disease, and in aortic valves. In spite of the wide occurrence of CVC and its detrimental effects on cardiovascular diseases (CVD), no treatment is yet available. Most of CVC involve mechanisms similar to those occurring during endochondral and/or intramembranous ossification. Logically, since tissue-nonspecific alkaline phosphatase (TNAP) is the key-enzyme responsible for skeletal/dental mineralization, it is a promising target to limit CVC. Tools have recently been developed to inhibit its activity and preclinical studies conducted in animal models of vascular calcification already provided promising results. Nevertheless, as its name indicates, TNAP is ubiquitous and recent data indicate that it dephosphorylates different substrates in vivo to participate in other important physiological functions besides mineralization. For instance, TNAP is involved in the metabolism of pyridoxal phosphate and the production of neurotransmitters. TNAP has also been described as an anti-inflammatory enzyme able to dephosphorylate adenosine nucleotides and lipopolysaccharide. A better understanding of the full spectrum of TNAP's functions is needed to better characterize the effects of TNAP inhibition in diseases associated with CVC. In this review, after a brief description of the different types of CVC, we describe the newly uncovered additional functions of TNAP and discuss the expected consequences of its systemic inhibition in vivo.

Effect of essential amino acid кetoanalogues and protein restriction diet on morphogenetic proteins (FGF-23 and Кlotho) in 3b-4 stages chronic кidney disease patients: a randomized pilot study

BACKGROUND

A low protein diet (LPD) with essential amino acid ketoanalogue supplementation (KA) may contribute in improving of chronic kidney disease (CKD), while the exact mechanisms of KA's effect are not established yet. We have conducted a prospective, randomized, controlled comparative study of LPD + KA and LPD alone in relation to serum Klotho, FGF-23 levels in CKD patients.

METHODS

79 non-diabetic CKD 3b-4 stage patients, compliant with LPD diet (0.6 g/kg of body weight/day), had been selected. The patients were randomized into two groups. The first group (42 patients) received LPD + КA. The second group (37 patients) continued the LРD alone. In addition to routine tests, serum Klotho, FGF-23 levels, as well as bioimpedance analysis, sphygmography (stiffness (augmentation) indices (AI), central (aortal) blood pressure) with a «SphygmaCor» device; echocardiography (valvular calcification score (VCS) and LVMMI), were performed.

RESULTS

There were body mass indices' decrease (p = 0.046), including muscle body mass in men (p = 0.027) and woman (p = 0.044) in the LPD group to the end of study (14th month). In addition, lower FGF-23 (p = 0.029), and higher sKlotho (p = 0.037) were detected in the LPD + KA group compared to the LPD one. The increase in AI (p = 0.034), VCS (p = 0.048), and LVMMI (p = 0.023) was detected more often in the LPD group at the end of study.

CONCLUSION

LPD + KA provides support for nutrition status and contributes to more efficient correction of FGF-23 and Klotho abnormalities that may result in cardiovascular calcification and cardiac remodeling decreasing in CKD. At the same time, a prolonged LPD alone may lead to malnutrition.

SNF472, a novel inhibitor of vascular calcification, could be administered during hemodialysis to attain potentially therapeutic phytate levels

BACKGROUND

Cardiovascular calcification (CVC) is a major concern in hemodialysis (HD) and the loss of endogenous modulators of calcification seems involved in the process. Phytate is an endogenous crystallization inhibitor and its low molecular mass and high water solubility make it potentially dialyzable. SNF472 (the hexasodium salt of phytate) is being developed for the treatment of calciphylaxis and CVC in HD patients. We aimed to verify if phytate is lost during dialysis, and evaluate SNF472's behaviour during dialysis.

METHODS

Dialyzability was assessed in vitro using online-hemodiafiltration and high-flux HD systems in blood and saline. SNF472 was infused for 20 min and quantified at different time points.

RESULTS

Phytate completely dialyzed in 1 h at low concentrations (10 mg/l) but not when added at 30 or 66.67 mg/l SNF472. In bypass conditions, calcium was slightly chelated during SNF472 infusion but when the system was switched to dialysis mode the calcium in the bath compensated this chelation.

CONCLUSION

Phytate dialyses with a low clearance. The administration of SNF472 as an exogenous source of phytate allows to attain supra-physiological levels required for its potential therapeutic properties. As SNF472 is infused during the whole dialysis session, the low clearance would not affect the drug's systemic exposure.

Roles of High Mobility Group Box 1 in Cardiovascular Calcification

Calcific disease of the cardiovascular system, including atherosclerotic calcification, medial calcification in diabetes and calcific aortic valve disease, is an important risk factor for many adverse cardiovascular events such as ischemic cardiac events and subsequent mortality. Although cardiovascular calcification has long been considered to be a passive degenerative occurrence, it is now recognized as an active and highly regulated process that involves osteochondrogenic differentiation, apoptosis and extracellular vesicle release. Nonetheless, despite numerous studies on the pathogenesis of cardiovascular calcification, the underlying mechanisms remain poorly understood. High mobility group box 1 (HMGB1), a nuclear protein bound to chromatin in almost all eukaryotic cells, acts as a damage-associated molecular pattern (DAMP) when released into the extracellular space upon cell activation, injury or death. Moreover, HMGB1 also functions as a bone-active cytokine participating in bone remodeling and ectopic calcification pathogenesis. However, studies on the roles of HMGB1 in promoting cardiovascular calcification are limited to date, and the mechanisms involved are still unclear. In this review, we summarize recent studies investigating the mechanism of cardiovascular calcification and discuss multiple roles of HMGB1 in its development.

Lysyl oxidase-dependent extracellular matrix crosslinking modulates calcification in atherosclerosis and aortic valve disease

Extracellular matrix (ECM) is an active player in cardiovascular calcification (CVC), a major public health issue with an unmet need for effective therapies. Lysyl oxidase (LOX) conditions ECM biomechanical properties; thus, we hypothesized that LOX might impact on mineral deposition in calcific aortic valve disease (CAVD) and atherosclerosis. LOX was upregulated in calcified valves from two cohorts of CAVD patients. Strong LOX immunostaining was detected surrounding calcified foci in calcified human valves and atherosclerotic lesions colocalizing with RUNX2 on valvular interstitial cells (VICs) or vascular smooth muscle cells (VSMCs). Both LOX secretion and organized collagen deposition were enhanced in calcifying VICs exposed to osteogenic media. β-aminopropionitrile (BAPN), an inhibitor of LOX, attenuated collagen deposition and calcification. VICs seeded onto decellularized matrices from BAPN-treated VICs calcified less than cells cultured onto control scaffolds; instead, VICs exposed to conditioned media from cells over-expressing LOX or cultured onto LOX-crosslinked matrices calcified more. Atherosclerosis was induced in WT and transgenic mice that overexpress LOX in VSMC (TgLOXVSMC) by AAV-PCSK9D374Y injection and high-fat feeding. In atherosclerosis-challenged TgLOXVSMC mice both atherosclerosis burden and calcification assessed by near-infrared fluorescence (NIRF) imaging were higher than in WT mice. These animals also exhibited larger calcified areas in atherosclerotic lesions from aortic arches and brachiocephalic arteries. Moreover, LOX transgenesis exacerbated plaque inflammation, and increased VSMC cellularity, the rate of RUNX2-positive cells and both connective tissue content and collagen cross-linking. Our findings highlight the relevance of LOX in CVC and postulate this enzyme as a potential therapeutic target for CVC.

Upregulation of NOR-1 in calcified human vascular tissues: impact on osteogenic differentiation and calcification

Cardiovascular calcification is a significant public health issue whose pathophysiology is not fully understood. NOR-1 regulates critical processes in cardiovascular remodeling, but its contribution to ectopic calcification is unknown. NOR-1 was overexpressed in human calcific aortic valves and calcified atherosclerotic lesions colocalizing with RUNX2, a factor essential for osteochondrogenic differentiation and calcification. NOR-1 and osteogenic markers were upregulated in calcifying human valvular interstitial cells (VICs) and human vascular smooth muscle cells (VSMCs). Gain- and loss-of-function approaches demonstrated that NOR-1 negatively modulates the expression of osteogenic genes relevant for the osteogenic transdifferentiation (RUNX2, IL-6, BMP2, and ALPL) and calcification of VICs. VSMCs from transgenic mice overexpressing NOR-1 in these cells (TgNOR-1VSMC) expressed lower basal levels of osteogenic genes (IL-6, BMP2, ALPL, OPN) than cells from WT littermates, and their upregulation by a high-phosphate osteogenic medium (OM) was completely prevented by NOR-1 transgenesis. Consistently, this was associated with a dramatic reduction in the calcification of both transgenic VSMCs and aortic rings from TgNOR-1VSMC mice exposed to OM. Atherosclerosis and calcification were induce in mice by the administration of AAV-PCSK9D374Y and a high-fat/high-cholesterol diet. Challenged-TgNOR-1VSMC mice exhibited decreased vascular expression of osteogenic markers, and both less atherosclerotic burden (assessed in whole aorta and lesion size in aortic arch and brachiocephalic artery) and less vascular calcification (assessed either by near-infrared fluorescence imaging or histological analysis) than WT mice. Our data indicate that NOR-1 negatively modulates the expression of genes critically involved in the osteogenic differentiation of VICs and VSMCs, thereby restraining ectopic cardiovascular calcification.

Osteocalcin and vascular calcification in hemodialysis patients: an observational cohort study

BACKGROUND

Vascular calcification contributes to morbidity and mortality in patients with ESRD on maintenance hemodialysis.

AIMS

To study the relationship between osteocalcin and vascular calcification.

METHODS

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 a valvular thickening.

CONCLUSIONS

Functional vitamin K deficiency is present in maintenance hemodialysis patients and serum osteocalcin is not associated with cardiovascular calcification.

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 risk factors and predictive model for cardiac valve calcification in patients on maintenance peritoneal dialysis: a single-center retrospective study

BACKGROUND

Cardiovascular calcification includes cardiac valve calcification (CVC) and vascular calcification. We aimed to analyze risk factors for CVC, and construct a predictive model in maintenance peritoneal dialysis (MPD) patients.

METHODS

We retrospectively analyzed MPD patients who began peritoneal dialysis between January 2014 and September 2021. Patients were randomly assigned to the derivation cohort and validation cohort in a 7:3 ratio. The patients in the derivation cohort were divided into the CVC group and non-CVC group. Logistic regression was used to analyze risk factors, then the rms package in R language was used to construct a nomogram model to predict CVC.

RESULTS

1,035 MPD patients were included, with the age of 50.0 ± 14.2 years and 632 males (61.1%). Their median follow-up time was 25 (12, 46) months. The new-onset CVC occurred in 128 patients (12.4%). In the derivation cohort, multivariate logistic regression indicated old age, female, high systolic blood pressure (SBP), high calcium-phosphorus product (Ca × P), high Charlson comorbidity index (CCI) and long dialysis time were independent risk factors for CVC (p < 0.05). We constructed a nomogram model for predicting CVC in the derivation cohort, with a C index of 0.845 (95% CI 0.803-0.886). This model was validated with a C index of 0.845 (95%CI 0.781-0.909) in the validation cohort.

CONCLUSION

We constructed a nomogram model for CVC in MPD patients, using independent risk factors including age, sex, SBP, Ca × P, CCI and dialysis time. This model achieved high efficiency in CVC prediction.

Characteristics and complications of fracture in older adults with chronic kidney disease: a cross-sectional study

BACKGROUND

The aim of this study was to analyze the clinical characteristics of older fracture patients with chronic kidney disease (CKD) and to determine the risk factors of perioperative cardiovascular complications.

METHODS

We retrospectively reviewed clinical data of older fracture patients with CKD admitted to the Third Hospital of Hebei Medical University from January 2016 to October 2021. The data we collected included baseline characteristics and complications. We finally determined the risk factors of perioperative cardiovascular complications by using logistic regression.

RESULTS

We ended up enrolling 224 patients, and there were 91 (40.6%) males and 133 (59.4%) females, with a median age of 79 years. 80-84 years old was the age group with high incidence of fracture. The majority of fracture occurred indoors (130 cases, 58.0%) and morning (98 cases, 43.8%). Hip fracture was most common (183 cases, 81.7%), of which femoral neck fracture (101 cases, 45.0%) was the most prevalent. The most common comorbid condition was hypertension (171 cases, 76.3%), and anemia was the most common complication (148 cases, 66.1%). Age ≥ 80 years (OR = 2.023, 95% CI 1.110-3.688), previously combined with cardiovascular calcification (OR = 1.901, 95% CI 1.047-3.451) and admission hemoglobin level < 100 g/L (OR = 3.191, 95% CI 1.744-5.838) were independent risk factors of perioperative cardiovascular disease (CVD).

CONCLUSION

It was especially necessary to enhance fracture prevention for CKD. Patients whose age older than 80, hemoglobin less than 100 g/L on admission and have previous cardiovascular calcification are more likely to develop perioperative CVD. Such patients require reasonable decisions during the perioperative period to avoid the occurrence of CVD.

Soluble urokinase plasminogen activator receptor is associated with cardiovascular calcification in peritoneal dialysis patients

BACKGROUND

Cardiovascular disease (CVD) is an important cause of morbidity and mortality in peritoneal dialysis (PD) patients. Cardiovascular calcification (CVC) is highly prevalent in PD patients and could predict their cardiovascular mortality. Soluble urokinase plasminogen activator receptor (suPAR) is closely associated with coronary artery calcification in hemodialysis patients and is an important predictor of CVD. However, the role of suPAR in PD patients is poorly understood. We investigated the relationship between serum suPAR and CVC in PD patients.

METHODS

Abdominal aortic calcification (AAC) was assessed by lateral lumbar radiography, coronary artery calcification (CAC) by multi-slice computed tomography, and cardiac valvular calcification (ValvC) by echocardiography. CVC was defined as confirmed presence of calcification in one site (AAC, CAC, or ValvC). Patients were divided into CVC group and non-CVC group. Demographic characteristics, biochemical variables, comorbidities, PD regimen, serum suPAR, and medication were compared between the two groups. Logistic regression was conducted to determine association between serum suPAR and presence of CVC. The receiver-operator curve (ROC) was plotted to calculate the area under the curve (AUC) for suPAR to identify CVC and ValvC.

RESULTS

Of 226 PD patients, 111 (49.1%) had AAC, 155 (68.6%) had CAC, and 26 (11.5%) had ValvC. There were significant differences in age, BMI, diabetes, white blood cell, phosphorus, hs-CRP, suPAR, time on dialysis, total volume of dialysate, ultrafiltration, volume of urine, and Kt/V between CVC and non-CVC group. Serum suPAR was associated with CVC by multivariate logistic regression analysis in PD patients, especially in elderly patients. The levels of serum suPAR were closely related to the degree of AAC, CAC, and ValvC in PD patients. The incidence of CVC was higher in patients with higher levels of suPAR. The ROC curve showed that serum suPAR had a predictive value for CVC (AUC = 0.651), especially for ValvC (AUC = 0.828).

CONCLUSION

Cardiovascular calcification is prevalent in PD patients. High levels of serum suPAR are associated with cardiovascular calcification in PD patients, especially in elderly patients.

Maternal high-fat diet promotes calcified atherosclerotic plaque formation in adult offspring by enhancing transformation of VSMCs to osteochondrocytic-like phenotype

Aim

Maternal high-fat diet (HFD) is associated with the development of cardiovascular disease (CVD) in adult offspring. Atherosclerotic vascular calcification is well documented in patients with CVD. We examined the effect of maternal HFD on calcified plaque formation.

Methods and results

Seven-week-old female apo-E^−/− mice (C57BL6/J) were nourished either an HFD or a normal diet (ND) a week before mating, and during gestation and lactation. Offspring of both the groups were fed a high-cholesterol diet (HCD) from 8 weeks of age. Osteogenic activity of the thoracic aorta, assessed using an ex vivo imaging system, was significantly increased after 3 months of HCD in male offspring of HFD-fed dams (O-HFD) as compared with those of ND-fed dams (O-ND). Alizarin-red-positive area in the aortic root was significantly increased after 6 months of HCD in male O-HFD as compared to that of O-ND. Plaque size and Oil Red O-positive staining were comparable between the two groups. Primary cultured vascular smooth muscle cells (VSMCs) of the thoracic aorta were treated with phosphate and interleukinL-1β (IL-1β) to transform them into an osteochondrocytic-like phenotype. Intracellular calcium content and alkaline phosphatase activity were markedly higher in the VSMCs of O-HFD than in O-ND. IL-1β concentration in the supernatant of bone marrow-derived macrophages was markedly higher in O-HFD than in O-ND.

Conclusion

Our findings indicate that maternal HFD accelerates the expansion of atherogenic calcification independent of plaque progression. In vitro phosphate- and IL-1β-induced osteochondrocytic transformation of VSMCs was augmented in O-HFD. Inhibition of VSMCs, skewing toward osteochondrocytic-like cells, might be a potential therapeutic strategy for preventing maternal HFD-associated CVD development.

The impact of low and high dialysate calcium concentrations on cardiovascular disease and death in patients undergoing maintenance hemodialysis: a systematic review and meta-analysis

BACKGROUND

The optimal dialysate calcium (Ca) concentration for patients undergoing hemodialysis remains inconclusive, particularly concerning cardiovascular protection.

METHODS

We conducted a systematic review of 19 randomized controlled trials (RCTs) and a meta-analysis of eight RCTs to determine the optimal dialysate Ca concentration for cardiovascular protection. We compared outcomes in patients receiving maintenance hemodialysis treated with either a low-Ca dialysate (LCD) (1.125 or 1.25 mmol/L) or a high-Ca dialysate (HCD) (1.5 or 1.75 mmol/L). The outcomes were coronary artery calcification score (CACS), all-cause and cardiovascular death, cardiovascular function and structure, and serum biochemical parameters.

RESULTS

There was no significant difference between LCD and HCD concerning CACS (standardized mean difference [SMD] = -0.16, 95% confidence interval [CI]: [-0.38, 0.07]), the risk of all-cause death, and cardiovascular death in patients treated with chronic maintenance hemodialysis. Conversely, LCD was associated with a significantly lower intima-media thickness (SMD = -0.49, 95% CI [-0.94, -0.05]) and pulse wave velocity than HCD (SMD = -0.86, 95% CI [-1.21, -0.51]). Furthermore, LCD significantly decreased serum Ca levels (mean difference [MD] = 0.52 mg/dL, 95% CI [0.19, 0.85]) and increased serum parathyroid hormone levels (MD = 44.8 pg/mL, 95% CI [16.2, 73.3]) compared with HCD. Notably, most RCTs examined in our analysis did not include patients receiving calcimimetics.

CONCLUSIONS

Our meta-analysis showed no significant differences in cardiovascular calcification and death between LCD and HCD and revealed a paucity of RCTs on dialysate Ca concentrations, including those involving patients on calcimimetics, indicating the urgent need for further studies.

Significance of coronary artery calcification for predicting major adverse cardiovascular events: results from the NADESICO study in Japan

BACKGROUND

We aimed to determine the usefulness and sex differences of assessment of coronary artery calcification (CAC) with cardiovascular risk factors and major adverse cardiovascular events (MACE) in Japanese patients.

METHODS

In a nationwide, multicenter, prospective cohort study, 1187 patients with suspected coronary artery disease who underwent coronary computed tomography were enrolled. MACE included cardiovascular death, myocardial infarction, stroke, revascularization, and hospitalization for unstable angina, heart failure, or aortic disease. The concordance (C)-statistics were used to assess the relationships among the Suita risk score, CAC score, and incident MACE, with emphasis on sex differences.

RESULTS

The final analysis included 982 patients (mean age, 64.7 ± 6.6 years; 53.9 % male patients). MACE developed in 65 male and 21 female patients during a median follow-up of 1480 days. The C-statistics calculated using Suita score for MACE were 0.650, 0.633, and 0.569 in overall, male, and female patients, respectively. In overall patients, the C-statistic significantly increased in combined models of Agatston CAC scores of ≥100, 200, 300, or 400 and the Suita score. In each sex, the C-statistics significantly increased in the model that added an Agatston CAC score of ≥100 and ≥ 200 (+0.049 and + 0.057) in male patients, and ≥ 400 (+0.119) in females, respectively.

CONCLUSIONS

Adding assessment of Agatston CAC scores to Suita score was useful to improve the predictive ability for future MACE in Japanese patients. Agatston CAC scores of ≥100 or 200 in male and ≥ 400 in female patients in addition to Suita score improved the MACE risk prediction.

Lysyl oxidase expression in smooth muscle cells determines the level of intima calcification in hypercholesterolemia-induced atherosclerosis

INTRODUCTION

Cardiovascular calcification is an important public health issue with an unmeet therapeutic need. We had previously shown that lysyl oxidase (LOX) activity critically influences vascular wall smooth muscle cells (VSMCs) and valvular interstitial cells (VICs) calcification by affecting extracellular matrix remodeling. We have delved into the participation of LOX in atherosclerosis and vascular calcification, as well as in the mineralization of the aortic valve.

METHODS

Immunohistochemical and expression studies were carried out in human atherosclerotic lesions and experimental models, valves from patients with aortic stenosis, VICs, and in a genetically modified mouse model that overexpresses LOX in CMLV (TgLOXCMLV). Hyperlipemia and atherosclerosis was induced in mice through the administration of adeno-associated viruses encoding a PCSK9 mutated form (AAV-PCSK9D374Y) combined with an atherogenic diet.

RESULTS

LOX expression is increased in the neointimal layer of atherosclerotic lesions from human coronary arteries and in VSMC-rich regions of atheromas developed both in the brachiocephalic artery of control (C57BL/6J) animals transduced with PCSK9D374Y and in the aortic root of ApoE-/- mice. In TgLOXCMLV mice, PCSK9D374Y transduction did not significantly alter the enhanced aortic expression of genes involved in matrix remodeling, inflammation, oxidative stress and osteoblastic differentiation. Likewise, LOX transgenesis did not alter the size or lipid content of atherosclerotic lesions in the aortic arch, brachiocephalic artery and aortic root, but exacerbated calcification. Among lysyl oxidase isoenzymes, LOX is the most expressed member of this family in highly calcified human valves, colocalizing with RUNX2 in VICs. The lower calcium deposition and decreased RUNX2 levels triggered by the overexpression of the nuclear receptor NOR-1 in VICs was associated with a reduction in LOX.

CONCLUSIONS

Our results show that LOX expression is increased in atherosclerotic lesions, and that overexpression of this enzyme in VSMC does not affect the size of the atheroma or its lipid content, but it does affect its degree of calcification. Further, these data suggest that the decrease in calcification driven by NOR-1 in VICs would involve a reduction in LOX. These evidences support the interest of LOX as a therapeutic target in cardiovascular calcification.

Osteopontin stabilization and collagen containment slows amorphous calcium phosphate transformation during human aortic valve leaflet calcification

Calcification of aortic valve leaflets is a growing mortality threat for the 18 million human lives claimed globally each year by heart disease. Extensive research has focused on the cellular and molecular pathophysiology associated with calcification, yet the detailed composition, structure, distribution and etiological history of mineral deposition remains unknown. Here transdisciplinary geology, biology and medicine (GeoBioMed) approaches prove that leaflet calcification is driven by amorphous calcium phosphate (ACP), ACP at the threshold of transformation toward hydroxyapatite (HAP) and cholesterol biomineralization. A paragenetic sequence of events is observed that includes: (1) original formation of unaltered leaflet tissues: (2) individual and coalescing 100's nm- to 1 μm-scale ACP spherules and cholesterol crystals biomineralizing collagen fibers and smooth muscle cell myofilaments; (3) osteopontin coatings that stabilize ACP and collagen containment of nodules preventing exposure to the solution chemistry and water content of pumping blood, which combine to slow transformation to HAP; (4) mm-scale nodule growth via ACP spherule coalescence, diagenetic incorporation of altered collagen and aggregation with other ACP nodules; and (5) leaflet diastole and systole flexure causing nodules to twist, fold their encasing collagen fibers and increase stiffness. These in vivo mechanisms combine to slow leaflet calcification and establish previously unexplored hypotheses for testing novel drug therapies and clinical interventions as viable alternatives to current reliance on surgical/percutaneous valve implants.

Roles of Lysyl oxidases (LOX(L)) in pathologic calcification

Calcification of tissues involves the formation and deposition of calcium-containing crystals in the extracellular matrix (ECM). While this process is normal in bones, it becomes pathological when it occurs in cardiovascular and musculoskeletal soft tissues. Pathological calcification (PC) triggers detrimental pathways such as inflammation and oxidative stress, contributing to tissue damage and dysregulated tissue biomechanics, ultimately leading to severe complications and even death. The underlying mechanisms of PC remain elusive. Emerging evidence suggests a significant role of lysyl oxidases (LOX(L)) in PC. LOX(L) are a group of five enzymes involved in collagen cross-linking and ECM maturation. Beyond their classical role in bone mineralization, recent investigations propose new non-classical roles for LOX(L) that could be relevant in PC. In this review, we analyzed and summarized the functions of LOX(L) in cardiovascular and musculoskeletal PC, highlighting their deleterious roles in most studies. To date, specific inhibitors targeting LOX(L) isoforms are under development. New therapeutic tools targeting LOX(L) are warranted in PC and must avoid adverse effects on physiological bone mineralization.