Calcification In End-stage Renal Disease Patients Research Articles

The crosstalk between endothelial cells and vascular smooth muscle cells aggravates high phosphorus-induced arterial calcification

Arterial calcification is highly prevalent, particularly in patients with end-stage renal disease (ESRD). The osteogenic differentiation of vascular smooth muscle cells (VSMCs) is the critical process for the development of arterial calcification. However, the detailed mechanism of VSMCs calcification remains to be elucidated. Here, we investigated the role of exosomes (Exos) derived from endothelial cells (ECs) in arterial calcification and its potential mechanisms in ESRD. Accelerated VSMCs calcification was observed when VSMCs were exposed to ECs culture media stimulated by uremic serum or high concentration of inorganic phosphate (3.5 mM Pi). and the pro-calcification effect of the ECs culture media was attenuated by exosome depletion. Exosomes derived from high concentrations of inorganic phosphate-induced ECs (ECsHPi-Exos) could be uptaken by VSMCs and promoted VSMCs calcification. Microarray analysis showed that miR-670-3p was dramatically increased in ECsHPi-Exos compared with exosomes derived from normal concentrations of inorganic phosphate (0.9 mM Pi) induced ECs (ECsNPi-Exos). Mechanistically, insulin-like growth factor 1 (IGF-1) was identified as the downstream target of miR-670-3p in regulating VSMCs calcification. Notably, ECs-specific knock-in of miR-670-3p of the 5/6 nephrectomy with a high-phosphate diet (miR-670-3pEC-KI + NTP) mice that upregulated the level of miR-670-3p in artery tissues and significantly increased artery calcification. Finally, we validated that the level of circulation of plasma exosomal miR-670-3p was much higher in patients with ESRD compared with healthy controls. Elevated levels of plasma exosomal miR-670-3p were associated with a decline in IGF-1 and more severe artery calcification in patients with ESRD. Collectively, these findings suggested that ECs-derived exosomal miR-670-3p could promote arterial calcification by targeting IGF-1, which may serve as a potential therapeutic target for arterial calcification in ESRD patients.

Plasma Exosomes Derived From Patients With End-Stage Renal Disease and Renal Transplant Recipients Have Different Effects on Vascular Calcification.

End-stage renal disease (ESRD) patients usually develop extensive and progressive vascular calcification, and lots of calcification inhibitors as well as procalcifying factors are involved in the process. However, the mechanisms of vascular calcification in ESRD patients are still ill-defined. In the present study, we found that the plasma exosomes derived from ESRD patients (ESRD-Ex) promoted calcification of vascular smooth muscle cells (VSMCs) significantly, while plasma exosomes from renal transplant recipients (RTR-Ex) could partially attenuate VSMCs calcification. Moreover, the protein concentration of ESRD-Ex was significantly higher than plasma exosomes from the normal health control group (Nor-Ex) and RTR-Ex, and the content of both matrix gla protein (MGP) and Fetuin-A, the calcification inhibitors, were prominently lower in ESRD-Ex than those in Nor-Ex. The content of Annexin-A2, one of the calcification promoters, was significantly higher in ESRD-Ex and RTR-Ex than that in Nor-Ex. However, bone morphogenetic protein (BMP-2) and receptor activator for nuclear factor-κB ligand (Rankl) had no significant difference among the three groups. In addition, the content of Fetuin-A in RTR-Ex was higher than that in ESRD-Ex, although it was still lower than that in Nor-Ex. Furthermore, the levels of both Fetuin-A and MGP in plasma exosomes were negatively while the levels of Annexin-A2 in plasma exosomes was positively correlated to coronary artery calcification scores (CACS). These results indicated that ESRD-Ex significantly promoted VSMCs calcification, while renal transplantation could partially attenuate the procalcification effect of exosomes. Fetuin-A and MGP were decreased, but Annexin-A2 was increased in ESRD-Ex, and renal transplantation could increase the level of Fetuin-A rather than MGP.

SAT-185 The role of SIRT2/Mtch1 in vascular calcification of end-stage renal disease involved in ferroptosis

Vascular calcification (VC) is a common complication of end-stage renal disease (ESRD) and an important risk factor for the increase of cardiovascular events and mortality in patients with end-stage renal disease. At present, the mechanism of vascular calcification in ESRD patients has not been fully elucidated. The electrolyte imbalances, inflammation, oxidative stress, apoptosis, autophagy and so on are involved in vascular calcification. Among them, Oxidative stress plays an important role in diseases, and lipid peroxides produced in this process are closely related to ferroptosis. Therefore, this study is to explore the further mechanism of VC in ESRD patients. We used vascular smooth muscle cells to established calcification model pretreated with ferroptosis inducer Erastin(Era) and inhibitor Ferrostatin-1(Fer-1). Cells were separated to six groups: Ctrl, Fer, Era, CAL, CAL+Fer and CAL+Era. The cell samples were detedted by Label-free. Ferroptosis was observed by electron microscopy. Mitochondria were stained by mitotracker and its damage was observed by confocal. the production of lipid peroxides including MDA, SOD and NO in cells was detected. Proteins and mRNA expression were detected by western blot and RT-PCR, respectively. In calcified cell model, the level of RUNX2 and OPN were increased. Mitochondrial damage observed in confocal, ferroptosis observed under electron microscopy, MDA and NO production increased, while SOD production decreased. Erastin aggravated but Ferrostatin-1 alleviated calcification. On this basis, we screened out the protein Sirtuin2 (SIRT2) and Mtch1 related to ferroptosis and calcification by Label-free. Western blot demonstrated SIRT2 expression decreased and Mtch1 expression increased in calcified cell model. Fer-1 increased the expression of SIRT2 and thereby decreased Mtch1, while the pretreatment of Erastin inhibited the expression of SIRT2 increased and promoted Mtch1 expression. SIRT2 was involved in vascular calcification of ESRD related to ferroptosis, and its mechanism was regulating the expression of the apoptotic protein Mtch1.

Intelligent diagnosis of cardiac valve calcification in ESRD patients with peritoneal dialysis based on improved Takagi-Sugeno-Kang fuzzy system

Without a B-ultrasound result, if a doctor diagnoses a suspected patient using only the basic clinical features, such as age, gender, serum calcium, and urea clearance index (KT/V), the diagnostic accuracy will be very low (even less than 50%). To solve this problem, a machine learning technology is proposed to intelligently diagnose cardiac valve calcification in end-stage renal disease (ESRD) patients with peritoneal dialysis. Compared with classical classification technologies, the proposed method aims to develop a model that has both medical interpretability and high recognition performance. In terms of interpretability, the Takagi-Sugeno-Kang fuzzy system is considered a basic model due to its built-in interpretable ability. In addition, because the distribution of the positive class (cardiac valve calcification is positive) and negative class (cardiac valve calcification is negative) in the peritoneal dialysis patient dataset is unbalanced, a novel unbalanced TSK (Takagi-Sugeno-Kang) fuzzy system (B-TSK-FS) is developed using a novel unbalanced fuzzy learning mechanism. The corresponding results reveal that the B-TSK-FS method obtains promising results (the max testing accuracy is over 98%) compared with classical machine learning methods for intelligently diagnosing cardiac valve calcification in ESRD patients with peritoneal dialysis.

Pathogenesis and Management of Vascular Calcification in Patients with End-Stage Renal Disease.

Vascular calcification is common in patients with end-stage renal disease (ESRD). In addition to traditional cardiovascular risk factors, ESRD patients also have a number of nontraditional cardiovascular risk factors that may play an important role in the pathogenesis of vascular calcification. The transformation of vascular smooth muscle cells into osteoblast-like cells may be a key element in the pathogenesis of vascular calcification in the presence of calcium and phosphate deposition due to abnormal bone metabolism and impaired renal excretion. Vascular calcification causes increased arterial stiffness, left ventricular hypertrophy, decreased coronary artery perfusion, myocardial ischemia, and increased cardiovascular morbidity and mortality. Although current treatment strategies focus on correcting abnormal calcium, phosphate, parathyroid hormone, or vitamin D levels in ESRD patients, a better understanding of the mechanisms of abnormal tissue calcification may lead to the development of new therapeutic agents that are capable of reducing vascular calcification and improving the cardiovascular outcome of ESRD patients. This review summarizes the pathogenesis and management of vascular calcification in ESRD patients.

Assessment of Arterial Stiffening and Vascular Calcifications in End‐Stage Renal Disease Patients

Background and Objective: Epidemiological and clinical studies have shown that vascular calcification and arterial vascular stiffness are associated with all-cause and cardiovascular (CV) mortality in the general populations and end-stage renal disease (ESRD) patients. The objective of this study was the assessment of arterial stiffness and vascular calcification in ESRD patients in Sohag University Hospital. Patients and Methods: In this cross-sectional descriptive study, 100 patients with ESRD (63 males and 37 females) were included. The patients were on regular hemodialysis (HD) for 65.18 ± 50.25 months. Arterial stiffness was measured by brachial pulse pressure (PP). A simple vascular calcification score (SVCS) based on plain radiographic films of pelvis and hands was used for assessment of vascular calcification. The patients undergoing clinical evaluation and serum calcium, phosphorus and parathyroid hormone (PTH) were obtained. Results: PP > 70 mmHg was observed in 24 patients (24%) and vascular calcifications were detected in 50 patients (50%). SVCS ≥ 3 was observed in 36 patients (36%) and 10 patients (10%) had both SVCS ≥ 3 and PP > 70 mmHg. PP > 70 was significantly associated with presence of vascular disease (odds ratio; 5, 95% CI = 1.56 - 16.01; P = 0.007). In multivariate analysis, PP > 70 was independently associated with elevated systolic blood pressure (odds ratio; 1.34, 95% CI = 1.11 - 1.6; P = 0.002) and serum PTH (odds ratio; 1.004, 95% CI = 1 - 1.008; P = 0.03). SVCS ≥ 3 was association with age (odds ratio; 1.05, 95% CI = 1.02 - 1.09; P = 0.003) and presence of vascular disease (odds ratio; 3.19, 95% CI = 1.3 - 7.85; P = 0.01). Elevated systolic blood pressure was independently associated with SVCS ≥ 3 (odds ratio; 1.08, 95% CI = 1.03 - 1.14; P = 0.002). Conclusion: Arterial stiffness and vascular calcifications are common in patients with ESRD on regular hemodialysis. PP and SVCS are simple and inexpensive methods in assessment of vascular calcifications and arterial stiffness in hemodialysis patients. PP and SVCS may provide important information that may guide the management of these patients.

Hydrogen peroxide prevents vascular calcification induced ROS production by regulating Nrf-2 pathway

Background: Although vascular calcification in end-stage renal disease (ESRD) represents a ubiquitous human health problem, effective therapies with limited side effects are still lacking, and the precise mechanisms are not fully understood. The Nrf-2/ARE pathway is a pivotal to regulate anti-oxidative responses in vascular calcification upon ESRD. Although Nrf-2 plays a crucial role in atherosclerosis, pulmonary fibrosis, and brain ischemia, the effect of Nrf-2 and oxidative stress on vascular calcification in ESRD patients is still unclear. The aim of this research was to study the protective role of hydrogen peroxide in vascular calcification and the mechanism of Nrf-2 and oxidative stress on vascular calcification.Materials and methods: Here we used the rat vascular smooth muscle cell model of β-glycerophosphate-induced calcification resembling vascular calcification in ESRD to investigate the therapeutic effect of 0.01 mM hydrogen peroxide on vascular calcification and further explores the possible underlying mechanisms.Results: Our current report shows the in vitro role of 0.01 mM hydrogen peroxide in protecting against intracellular ROS accumulation upon vascular calcification. Both hydrogen peroxide and sulforaphane pretreatment reduced ROS production, increased the expression of Nrf-2, and decreased the expression of Runx2 following calcification.Conclusion: Our study demonstrates that 0.01 mM hydrogen peroxide can effectively protect rat aortic vascular smooth muscle cells against oxidative stress by preventing vascular calcification induced ROS production through Nrf-2 pathway. These data might define an antioxidant role of hydrogen peroxide in vascular calcification upon ESRD.

Vascular calcification in end-stage renal disease patients.

Vascular calcification is very common in patients with end-stage renal disease (ESRD) and has been found to be associated with mineral and bone disorders. There are two types of vascular calcification: intimal and medial calcification. The transformation of vascular smooth muscle cells into osteoblast-like cells seems to be a key element in the pathogenesis of medial calcification in the presence of calcium and phosphate deposition. Vascular calcification causes increased arterial stiffness by medial calcification, which leads to left ventricular hypertrophy and decreased coronary artery perfusion and causes myocardial ischemia by intimal calcification. Thus, vascular calcification is thought to be associated with increased cardiovascular morbidity and mortality. Although current treatment strategies focus on correcting abnormal calcium, phosphate, parathyroid hormone, or vitamin D levels in ESRD patients, a better understanding of the mechanisms of vascular calcification may lead to the development of new therapeutic strategies that are capable of reducing vascular calcification and improving the cardiovascular outcome of ESRD patients. This review summarizes the pathophysiology, diagnostic procedure and therapeutic implication of vascular calcification in ESRD patients.

The relationship between neutrophil‐to‐lymphocyte ratio and vascular calcification in end‐stage renal disease patients

Chronic inflammation was found to be correlated with coronary (CAC) and thoracic peri-aortic calcification (TAC) in end-stage renal disease (ESRD) patients. Neutrophil-to-lymphocyte ratio (NLR) was introduced as a potential marker to determine inflammation in cardiac and noncardiac disorders. Data regarding NLR and its association with TAC and CAC are lacking. We aimed to determine the relationship between NLR and vascular calcification in ESRD patients. This was a cross-sectional study involving 56 ESRD patients (22 females, 34 males; mean age, 49.9 ± 14.2 years) receiving peritoneal dialysis or hemodialysis for ≥6 months in the Dialysis Unit of Necmettin Erbakan University. TAC and CAC scores were measured by using an electrocardiogram-gated 64-multidetector computed tomography. NLR was calculated as the ratio of the neutrophils and lymphocytes. There was a statistically significant correlation between NLR, TACS and CACS in ESRD patients (r = 0.43, P = 0.001 and r = 0.30, P = 0.02, respectively). The stepwise linear regression analysis revealed that age, as well as NLR were independent predictors of TACS. However, increased age was the only independent predictor of CACS according to linear regression analysis. Simple calculation of NLR can predict vascular calcification in ESRD patients.

Inflammation Disrupts the LDL Receptor Pathway and Accelerates the Progression of Vascular Calcification in ESRD Patients

BackgroundChronic inflammation plays a crucial role in the progression of vascular calcification (VC). This study was designed to investigate whether the low-density lipoprotein receptor (LDLr) pathway is involved in the progression of VC in patients with end-stage renal disease (ESRD) during inflammation.Methods and ResultsTwenty-eight ESRD patients were divided into control and inflamed groups according to plasma C-reactive protein (CRP) level. Surgically removed tissues from the radial arteries of patients receiving arteriovenostomy were used in the experiments. The expression of tumour necrosis factor-α (TNF-α) and monocyte chemotactic protein-1 (MCP-1) of the radial artery were increased in the inflamed group. Hematoxylin-eosin and alizarin red S staining revealed parallel increases in foam cell formation and calcium deposit formation in continuous cross-sections of radial arteries in the inflamed group compared to the control, which were closely correlated with increased LDLr, sterol regulatory element binding protein-2 (SREBP-2), bone morphogenetic proteins-2 (BMP-2), and collagen I protein expression, as shown by immunohistochemical and immunofluorescent staining. Confocal microscopy confirmed that inflammation enhanced the translocation of the SREBP cleavage-activating protein (SCAP)/SREBP-2 complex from the endoplasmic reticulum to the Golgi, thereby activating LDLr gene transcription. Inflammation increased alkaline phosphatase protein expression and reduced α-smooth muscle actin protein expression, contributing to the conversion of the vascular smooth muscle cells in calcified vessels from the fibroblastic to the osteogenic phenotype; osteogenic cells are the main cellular components involved in VC. Further analysis showed that the inflammation-induced disruption of the LDLr pathway was significantly associated with enhanced BMP-2 and collagen I expression.ConclusionsInflammation accelerated the progression of VC in ESRD patients by disrupting the LDLr pathway, which may represent a novel mechanism involved in the progression of both VC and atherosclerosis.

The emerging role of phosphate in vascular calcification

Vascular calcification is recognized as a major contributor to cardiovascular disease (CVD) in end stage renal disease (ESRD) patients. Susceptibility to vascular calcification is genetically determined and actively regulated by diverse inducers and inhibitors. One of these inducers, hyperphosphatemia, promotes vascular calcification and is a nontraditional risk factor for CVD mortality in ESRD patients. Vascular smooth muscle cells (SMCs) respond to elevated phosphate levels by undergoing an osteochondrogenic phenotype change and mineralizing their extracellular matrix through a mechanism requiring sodium-dependent phosphate cotransporters. Disease states and cytokines can increase expression of sodium-dependent phosphate cotransporters in SMCs, thereby increasing susceptibility to calcification even at phosphate concentrations that are in the normal range.

Vascular and Other Tissue Calcification in Peritoneal Dialysis Patients

Cardiovascular disease is the leading cause of mortality in patients with end-stage renal disease (ESRD) and is attributed to a combination of traditional and non-traditional cardiovascular risk factors. In recent years, there has also been an increasing recognition of a very high prevalence of cardiovascular calcification in the ESRD population, including in patients receiving long-term peritoneal dialysis (PD). Numerous observational cohort studies have demonstrated the prognostic importance of cardiovascular calcifications in these patients. The mechanisms are not completely understood, but are likely multifactorial. The present article reviews the prevalence, clinical course, prognostic significance, and some contributing factors for vascular and valvular calcification in ESRD patients, including patients receiving PD therapy.

Modification of elastin by pentosidine is associated with the calcification of aortic media in patients with end-stage renal disease.

Calcification of the media of arteries is common in patients with end-stage renal disease (ESRD) undergoing haemodialysis and is a major cause of arteriosclerosis. The aim of this study was to clarify the role of glycoxidative modification of elastin in the calcification of aortic media in this group of patients. Samples of tunica media were obtained from non-atherosclerotic areas of the aortas of cadavers of seven non-diabetic patients with ESRD (age 65.5 +/- 10.6 years) and 10 age-matched controls (age 61.1 +/- 10.3 years). The localization of pentosidine, a major glycoxidation product, and calcium deposits in the media were examined using immunohistochemical and von Kossa staining, followed by orcein staining for elastin fibres. Tissue levels of pentosidine and calcium were measured in elastase-digested media using reversed high-performance liquid chromatography and atomic absorption spectrophotometry, respectively. In aortic media, but not intima, immunostained pentosidine was observed along elastin fibres or in the extracellular spaces between them. Early calcification was manifest as small punctate calcified deposits along elastin fibres in the media. Advanced calcification was found as large, confluent calcified deposits in extracellular spaces between elastin fibres. Double staining showed co-localization of pentosidine and calcified deposits in the media. Both the staining density of pentosidine and calcification were more prominent in ESRD patients than in controls. The mean medial contents of both elastin-associated pentosidine and calcium were significantly higher in ESRD patients than in controls. In ESRD patients, the level of calcium in elastase-digested media correlated significantly with pentosidine levels, which increased in parallel with the duration of haemodialysis. Our results indicate that glycoxidative modification of elastin in aortic media may be involved in the enhancement of medial calcification in ESRD patients on haemodialysis.

Phosphate overload accelerates vascular calcium deposition in end-stage renal disease patients.

Cardiovascular disease is a major problem in end-stage renal disease (ESRD) patients, with calcification being one of the conspicuous features of arteriosclerotic vessels. In the present study, clinical analysis and in vitro cell culture were used to investigate factors promoting vascular calcification in ESRD patients. The aortic arch calcification score (AACS) was the method used to estimate vascular calcification by evaluation of the simple posterior-anterior view chest X-rays. Factors that relate significantly to vascular calcification and the AACS are the Ca x Pi, age, dialysis period, blood pressure, smoking and diabetes mellitus, but not total cholesterol or triglyceride. The Ca x Pi, which depends on the serum phosphate concentration, is the only specific factor with the possibility for correction in ESRD patients, and so control of serum phosphate concentration is an important factor for reducing vascular calcification. The effects of phosphate overload on calcium deposition in human vascular smooth muscle cells (hVSMCs) using a primary cell culture system were also investigated. hVSMCs were harvested from the radial artery in ESRD patients and it was found that they could secrete extracellular matrix with a high affinity for calcium in a high phosphate medium (Pi=5.4 mg/dl). Therefore, phosphate overload might stimulate the hVSMCs to accelerate the calcium deposition in ESRD patients. These results suggest that the control of phosphate excess is important for prevention of calcium deposition on arteriole walls in ESRD patients.

Cardiovascular calcification in patients with end-stage renal disease: A century-old phenomenon

The mortality risk from cardiovascular disease is increased in patients with end-stage renal disease (ESRD). This is due to both traditional and dialysis-specific factors. Recently, a number of the dialysis-specific risk factors have been implicated in the pathogenesis of cardiovascular calcification. These include: hyperphosphatemia, high calcium-phosphate (Ca x P) product, elevated parathyroid hormone levels, duration of dialysis, and treatment with calcium-containing phosphate binders and vitamin D analogs. The recent availability of electron beam computed tomography (EBCT) has triggered increased awareness of the occurrence of cardiovascular calcification in ESRD patients. Given the development of transient hypercalcemia with calcium-containing binders, a link between calcium load from use of calcium-containing phosphate binders and development coronary calcification has been proposed. However, a causal relationship between use of these agents and cardiovascular calcification has not been established. Moreover, this phenomenon had been recognized over a century ago, long before these phosphate binders became available. Although its pathogenesis is likely to be multifactorial, available data strongly implicate elevated serum phosphorus as the primary culprit. Furthermore, the risk of calcification may be aggravated by vitamin D therapy, particularly in patients with severe secondary hyperparathyroidism. Therefore, achieving vigorous control of serum phosphorus, Ca x P product and parathyroid hormone level might decrease cardiovascular calcification and improve survival of patients on maintenance hemodialysis. Since calcium acetate is the most cost-effective phosphate binder available, we recommend that it should remain the first line treatment of hyperphosphatemia in patients with ESRD.