Vascular calcification in chronic kidney disease: role of disordered mineral metabolism

Vascular calcification in chronic kidney disease associated with pathogenic variants in ABCC6

Vascular calcification is prevalent in chronic kidney disease (CKD). Genetic causes of CKD account for 10-20% of adult-onset disease. Vascular calcification is thought to be one of the most important risk factors for increased cardiovascular morbidity and mortality in CKD patients and is detectable in 80% of patients with end stage kidney disease (ESKD). Despite the high prevalence of vascular calcification in CKD, no single gene cause has been described. We hypothesized that variants in vascular calcification genes may contribute to disease pathogenesis in CKD, particularly in families who exhibit a predominant vascular calcification phenotype. We developed a list of eight genes that are hypothesized to play a role in vascular calcification due to their involvement in the ectopic calcification pathway: ABCC6, ALPL, ANK1, ENPP1, NT5E, SLC29A1, SLC20A2, and S100A12. With this, we assessed exome data from 77 CKD patients, who remained unsolved following evaluation for all known monogenic causes of CKD. We also analyzed an independent cohort (Ontario Neurodegenerative Disease Research Initiative (ONDRI), n = 520) who were screened for variants in ABCC6 and compared this to a control cohort of healthy adults (n = 52). We identified two CKD families with heterozygous pathogenic variants (R1141X and A667fs) in ABCC6. We identified 10 participants from the ONDRI cohort with heterozygous pathogenic or likely pathogenic variant in ABCC6. Replication in a healthy control cohort did not reveal any variants. Our study provides preliminary data supporting the hypothesis that ABCC6 may play a role in vascular calcification in CKD. By screening CKD patients for genetic causes early in the diagnostic pathway, patients with genetic causes associated with vascular calcification can potentially be preventatively treated with new therapeutics with aims to decrease mortality.

Relationship between arginine methylation and vascular calcification

In patients on maintenance hemodialysis (MHD), vascular calcification (VC) is an independent predictor of cardiovascular disease (CVD), which is the primary cause of death in chronic kidney disease (CKD). The main component of VC in CKD is the vascular smooth muscle cells (VSMCs). VC is an ordered, dynamic activity. Under the stresses of oxidative stress and calcium-‑phosphorus imbalance, VSMCs undergo osteogenic phenotypic transdifferentiation, which promotes the formation of VC. In addition to traditional epigenetics like RNA and DNA control, post-translational modifications have been discovered to be involved in the regulation of VC in recent years. It has been reported that the process of osteoblast differentiation is impacted by catalytic histone or non-histone arginine methylation. Its function in the osteogenic process is comparable to that of VC. Thus, we propose that arginine methylation regulates VC via many signaling pathways, including as NF-B, WNT, AKT/PI3K, TGF-/BMP/SMAD, and IL-6/STAT3. It might also regulate the VC-related calcification regulatory factors, oxidative stress, and endoplasmic reticulum stress. Consequently, we propose that arginine methylation regulates the calcification of the arteries and outline the regulatory mechanisms involved.

Peritoneal dialysis versus haemodialysis for people commencing dialysis

BACKGROUND

Peritoneal dialysis (PD) and haemodialysis (HD) are two possible modalities for people with kidney failure commencing dialysis. Only a few randomised controlled trials (RCTs) have evaluated PD versus HD. The benefits and harms of the two modalities remain uncertain. This review includes both RCTs and non-randomised studies of interventions (NRSIs).

OBJECTIVES

To evaluate the benefits and harms of PD, compared to HD, in people with kidney failure initiating dialysis.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies from 2000 to June 2024 using search terms relevant to this review. Studies in the Register were identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov. MEDLINE and EMBASE were searched for NRSIs from 2000 until 28 March 2023.

SELECTION CRITERIA

RCTs and NRSIs evaluating PD compared to HD in people initiating dialysis were eligible.

DATA COLLECTION AND ANALYSIS

Two investigators independently assessed if the studies were eligible and then extracted data. Risk of bias was assessed using standard Cochrane methods, and relevant outcomes were extracted for each report. The primary outcome was residual kidney function (RKF). Secondary outcomes included all-cause, cardiovascular and infection-related death, infection, cardiovascular disease, hospitalisation, technique survival, life participation and fatigue.

MAIN RESULTS

A total of 153 reports of 84 studies (2 RCTs, 82 NRSIs) were included. Studies varied widely in design (small single-centre studies to international registry analyses) and in the included populations (broad inclusion criteria versus restricted to more specific participants). Additionally, treatment delivery (e.g. automated versus continuous ambulatory PD, HD with catheter versus arteriovenous fistula or graft, in-centre versus home HD) and duration of follow-up varied widely. The two included RCTs were deemed to be at high risk of bias in terms of blinding participants and personnel and blinding outcome assessment for outcomes pertaining to quality of life. However, most other criteria were assessed as low risk of bias for both studies. Although the risk of bias (Newcastle-Ottawa Scale) was generally low for most NRSIs, studies were at risk of selection bias and residual confounding due to the constraints of the observational study design. In children, there may be little or no difference between HD and PD on all-cause death (6 studies, 5752 participants: RR 0.81, 95% CI 0.62 to 1.07; I2 = 28%; low certainty) and cardiovascular death (3 studies, 7073 participants: RR 1.23, 95% CI 0.58 to 2.59; I2 = 29%; low certainty), and was unclear for infection-related death (4 studies, 7451 participants: RR 0.98, 95% CI 0.39 to 2.46; I2 = 56%; very low certainty). In adults, compared with HD, PD had an uncertain effect on RKF (mL/min/1.73 m2) at six months (2 studies, 146 participants: MD 0.90, 95% CI 0.23 to 3.60; I2 = 82%; very low certainty), 12 months (3 studies, 606 participants: MD 1.21, 95% CI -0.01 to 2.43; I2 = 81%; very low certainty) and 24 months (3 studies, 334 participants: MD 0.71, 95% CI -0.02 to 1.48; I2 = 72%; very low certainty). PD had uncertain effects on residual urine volume at 12 months (3 studies, 253 participants: MD 344.10 mL/day, 95% CI 168.70 to 519.49; I2 = 69%; very low certainty). PD may reduce the risk of RKF loss (3 studies, 2834 participants: RR 0.55, 95% CI 0.44 to 0.68; I2 = 17%; low certainty). Compared with HD, PD had uncertain effects on all-cause death (42 studies, 700,093 participants: RR 0.87, 95% CI 0.77 to 0.98; I2 = 99%; very low certainty). In an analysis restricted to RCTs, PD may reduce the risk of all-cause death (2 studies, 1120 participants: RR 0.53, 95% CI 0.32 to 0.86; I2 = 0%; moderate certainty). PD had uncertain effects on both cardiovascular (21 studies, 68,492 participants: RR 0.96, 95% CI 0.78 to 1.19; I2 = 92%) and infection-related death (17 studies, 116,333 participants: RR 0.90, 95% CI 0.57 to 1.42; I2 = 98%) (both very low certainty). Compared with HD, PD had uncertain effects on the number of patients experiencing bacteraemia/bloodstream infection (2 studies, 2582 participants: RR 0.34, 95% CI 0.10 to 1.18; I2 = 68%) and the number of patients experiencing infection episodes (3 studies, 277 participants: RR 1.23, 95% CI 0.93 to 1.62; I2 = 20%) (both very low certainty). PD may reduce the number of bacteraemia/bloodstream infection episodes (2 studies, 2637 participants: RR 0.44, 95% CI 0.27 to 0.71; I2 = 24%; low certainty). Compared with HD; It is uncertain whether PD reduces the risk of acute myocardial infarction (4 studies, 110,850 participants: RR 0.90, 95% CI 0.74 to 1.10; I2 = 55%), coronary artery disease (3 studies, 5826 participants: RR 0.95, 95% CI 0.46 to 1.97; I2 = 62%); ischaemic heart disease (2 studies, 58,374 participants: RR 0.86, 95% CI 0.57 to 1.28; I2 = 95%), congestive heart failure (3 studies, 49,511 participants: RR 1.10, 95% CI 0.54 to 2.21; I2 = 89%) and stroke (4 studies, 102,542 participants: RR 0.94, 95% CI 0.90 to 0.99; I2 = 0%) because of low to very low certainty evidence. Compared with HD, PD had uncertain effects on the number of patients experiencing hospitalisation (4 studies, 3282 participants: RR 0.90, 95% CI 0.62 to 1.30; I2 = 97%) and all-cause hospitalisation events (4 studies, 42,582 participants: RR 1.02, 95% CI 0.81 to 1.29; I2 = 91%) (very low certainty). None of the included studies reported specifically on life participation or fatigue. However, two studies evaluated employment. Compared with HD, PD had uncertain effects on employment at one year (2 studies, 593 participants: RR 0.83, 95% CI 0.20 to 3.43; I2 = 97%; very low certainty).

AUTHORS' CONCLUSIONS

The comparative effectiveness of PD and HD on the preservation of RKF, all-cause and cause-specific death risk, the incidence of bacteraemia, other vascular complications (e.g. stroke, cardiovascular events) and patient-reported outcomes (e.g. life participation and fatigue) are uncertain, based on data obtained mostly from NRSIs, as only two RCTs were included.

Carbonylation of Runx2 at K176 by 4-Hydroxynonenal Accelerates Vascular Calcification

BACKGROUND

Vascular calcification, which is characterized by calcium deposition in arterial walls and the osteochondrogenic differentiation of vascular smooth muscle cells, is an actively regulated process that involves complex mechanisms. Vascular calcification is associated with increased cardiovascular adverse events. The role of 4-hydroxynonenal (4-HNE), which is the most abundant stable product of lipid peroxidation, in vascular calcification has been poorly investigated.

METHODS

Serum was collected from patients with chronic kidney disease and controls, and the levels of 4-HNE and 8-iso-prostaglandin F2α were measured. Sections of coronary atherosclerotic plaques from donors were immunostained to analyze calcium deposition and 4-HNE. A total of 658 patients with coronary artery disease who received coronary computed tomography angiography were recruited to analyze the relationship between coronary calcification and the rs671 mutation in aldehyde dehydrogenase 2 (ALDH2). ALDH2 knockout (ALDH2-/-) mice, smooth muscle cell-specific ALDH2 knockout mice, ALDH2 transgenic mice, and their controls were used to establish vascular calcification models. Primary mouse aortic smooth muscle cells and human aortic smooth muscle cells were exposed to medium containing β-glycerophosphate and CaCl2 to investigate cell calcification and the underlying molecular mechanisms.

RESULTS

Elevated 4-HNE levels were observed in the serum of patients with chronic kidney disease and model mice and were detected in calcified artery sections by immunostaining. ALDH2 knockout or smooth muscle cell-specific ALDH2 knockout accelerated the development of vascular calcification in model mice, whereas overexpression or activation prevented mouse vascular calcification and the osteochondrogenic differentiation of vascular smooth muscle cells. In patients with coronary artery disease, patients with ALDH2 rs671 gene mutation developed more severe coronary calcification. 4-HNE promoted calcification of both mouse aortic smooth muscle cells and human aortic smooth muscle cells and their osteochondrogenic differentiation in vitro. 4-HNE increased the level of Runx2 (runt-related transcription factor-2), and the effect of 4-HNE on promoting vascular smooth muscle cell calcification was ablated when Runx2 was knocked down. Mutation of Runx2 at lysine 176 reduced its carbonylation and eliminated the 4-HNE-induced upregulation of Runx2.

CONCLUSIONS

Our results suggest that 4-HNE increases Runx2 stabilization by directly carbonylating its K176 site and promotes vascular calcification. ALDH2 might be a potential target for the treatment of vascular calcification.

Dengue haemorrhagic fever in chronic kidney disease and heart failure: challenges in fluid management

Dengue haemorrhagic fever (DHF) is recognized to have high mortality in patients with chronic kidney disease (CKD) and heart failure (HF). They are at high risk of shock during the ascending limb of the critical phase of DHF, fluid overload during convalescence and bleeding throughout the entire illness. Physiological changes and medications used in CKD/HF make the diagnosis and monitoring of DHF difficult. Treatment with standard fluid regimens also poses a challenge due to the propensity for fluid overload. As a result, standard dengue guidelines do not provide recommendations on fluid management regimens in DHF with CKD/HF. This article provides a narrative review on the existing evidence for management of DHF in patients with volume-changed states such as HF, CKD and nephrotic/ nephritic syndromes. It will explore the relevant diagnostic and therapeutic dilemmas, acknowledge the challenges for developing guidelines and recommend strategies to improve fluid management in these groups of patients.

Effect of Paricalcitol Combined with Cinacalcet on Calcium and Phosphorus Metabolism in Patients Receiving Maintenance Hemodialysis

This study was designed to compare the beneficial effects of paricalcitol combined with or without cinacalcet on calcium and phosphorus metabolism in patients undergoing maintenance hemodialysis (MHD). A total of 140 patients who received MHD in our hospital from March 2021 to March 2022 were randomly divided into a control group (intravenous paricalcitol, n = 70) and a test group (intravenous paricalcitol combined with oral cinacalcet, n = 70). Clinical baseline data and relevant laboratory parameters before treatment were compared. Additionally, calcium, phosphorus, intact parathyroid hormone in serum were measured and compared between the 2 groups before treatment and 1, 2, 3, 4, 5, 6, 9, 10, and 12 months after treatment. As a result, comparison before treatment demonstrated no significant difference in baseline data such as age, sex, and most laboratory parameters between the 2 groups (P > .05), but there was a significant difference in mean corpuscular volume (P < .001). The serum phosphorus level decreased and calcium level increased significantly in the 2 groups after treatment, while the intact parathyroid hormone level showed no significant change within 12 months of treatment (P > .05). In addition, the combined treatment for 6-12 months caused a much lower phosphorus level (P < .05) and higher calcium level (P < .05) than the treatment with paricalcitol alone, and the difference increased with the extension of treatment time. Collectively, paricalcitol combined with cinacalcet, which is more effective than paricalcitol alone, has a positive effect on calcium and phosphorus metabolism in patients receiving MHD.

Automated Measurement of Vascular Calcification in Femoral Endarterectomy Patients Using Deep Learning

Atherosclerosis, a chronic inflammatory disease affecting the large arteries, presents a global health risk. Accurate analysis of diagnostic images, like computed tomographic angiograms (CTAs), is essential for staging and monitoring the progression of atherosclerosis-related conditions, including peripheral arterial disease (PAD). However, manual analysis of CTA images is time-consuming and tedious. To address this limitation, we employed a deep learning model to segment the vascular system in CTA images of PAD patients undergoing femoral endarterectomy surgery and to measure vascular calcification from the left renal artery to the patella. Utilizing proprietary CTA images of 27 patients undergoing femoral endarterectomy surgery provided by Prisma Health Midlands, we developed a Deep Neural Network (DNN) model to first segment the arterial system, starting from the descending aorta to the patella, and second, to provide a metric of arterial calcification. Our designed DNN achieved 83.4% average Dice accuracy in segmenting arteries from aorta to patella, advancing the state-of-the-art by 0.8%. Furthermore, our work is the first to present a robust statistical analysis of automated calcification measurement in the lower extremities using deep learning, attaining a Mean Absolute Percentage Error (MAPE) of 9.5% and a correlation coefficient of 0.978 between automated and manual calcification scores. These findings underscore the potential of deep learning techniques as a rapid and accurate tool for medical professionals to assess calcification in the abdominal aorta and its branches above the patella.

Phosphorus May Induce Phenotypic Transdifferentiation of Vascular Smooth Muscle Cells through the Reduction of microRNA-145

Phosphorus is a vital element for life found in most foods as a natural component, but it is also one of the most used preservatives added during food processing. High serum phosphorus contributes to develop vascular calcification in chronic kidney disease; however, it is not clear its effect in a population without kidney damage. The objective of this in vivo and in vitro study was to investigate the effect of high phosphorus exposure on the aortic and serum levels of miR-145 and its effect on vascular smooth muscle cell (VSMCs) changes towards less contractile phenotypes. The study was performed in aortas and serum from rats fed standard and high-phosphorus diets, and in VSMCs exposed to different concentrations of phosphorus. In addition, miR-145 silencing and overexpression experiments were carried out. In vivo results showed that in rats with normal renal function fed a high P diet, a significant increase in serum phosphorus was observed which was associated to a significant decrease in the aortic α-actin expression which paralleled the decrease in aortic and serum miR-145 levels, with no changes in the osteogenic markers. In vitro results using VSMCs corroborated the in vivo findings. High phosphorus first reduced miR-145, and afterwards α-actin expression. The miR-145 overexpression significantly increased α-actin expression and partially prevented the increase in calcium content. These results suggest that miR-145 could be an early biomarker of vascular calcification, which could give information about the initiation of the transdifferentiation process in VSMCs.

Empagliflozin Attenuates Vascular Calcification in Mice with Chronic Kidney Disease by Regulating the NFR2/HO-1 Anti-Inflammatory Pathway through AMPK Activation

Vascular calcification (VC) is associated with increased cardiovascular risks in patients with chronic kidney disease (CKD). Sodium-glucose cotransporter 2 inhibitors, such as empagliflozin, can improve cardiovascular and renal outcomes. We assessed the expression of Runt-related transcription factor 2 (Runx2), interleukin (IL)-1β, IL-6, AMP-activated protein kinase (AMPK), nuclear factor erythroid-2-related factor (Nrf2), and heme oxygenase 1 (HO-1) in inorganic phosphate-induced VC in mouse vascular smooth muscle cells (VSMCs) to investigate the mechanisms underlying empagliflozin's therapeutic effects. We evaluated biochemical parameters, mean artery pressure (MAP), pulse wave velocity (PWV), transcutaneous glomerular filtration rate (GFR), and histology in an in vivo mouse model with VC induced by an oral high-phosphorus diet following a 5/6 nephrectomy in ApoE^-/- mice. Compared to the control group, empagliflozin-treated mice showed significant reductions in blood glucose, MAP, PWV, and calcification, as well as increased calcium and GFR levels. Empagliflozin inhibited osteogenic trans-differentiation by decreasing inflammatory cytokine expression and increasing AMPK, Nrf2, and HO-1 levels. Empagliflozin mitigates high phosphate-induced calcification in mouse VSMCs through the Nrf2/HO-1 anti-inflammatory pathway by activating AMPK. Animal experiments suggested that empagliflozin reduces VC in CKD ApoE^-/- mice on a high-phosphate diet.

Impaired renal ischemia reperfusion recovery after bilateral renal artery ligation in rats treated with adenine: role of renal mitochondria

Vascular calcification (VC) and ischemia reperfusion (IR) injury is characterised to have mitochondrial dysfunction. However, the impact of dysfunctional mitochondria associated with vascular calcified rat kidney challenged to IR is not explored and is addressed in the present study. Male Wistar rats were treated with adenine for 20 days to induce chronic kidney dysfunction and VC. After 63 days, renal IR protocol was performed with subsequent recovery for 24 h and 7 days. Various mitochondrial parameters and biochemical assays were performed to assess kidney function, IR injury and its recovery. Adenine-induced rats with VC, decreased creatinine clearance (CrCl), and severe tissue injury demonstrated an increase in renal tissue damage and decreased CrCl after 24 h of IR (CrCl in ml: IR-0.220.02, VC-IR-0.050.01). Incidentally, the 24 h IR pathology in kidney was similar in both VC-IR and normal rat IR. But, the magnitude of dysfunction was higher with VC-IR due to pre-existing basal tissue alterations. We found severed deterioration in mitochondrial quantity and quality supported by low bioenergetic function in both VC basal tissue and IR challenged sample. However, post 7 days of IR, unlike normal rat IR, VC rat IR did not improve CrCl and corresponding mitochondrial damage in terms of quantity and its function were observed. Based on the above findings, we conclude that IR in VC rat adversely affect the post-surgical recovery, mainly due to the ineffective renal mitochondrial functional restoration from the surgery.

Screening of immune-related secretory proteins linking chronic kidney disease with calcific aortic valve disease based on comprehensive bioinformatics analysis and machine learning

BACKGROUND

Chronic kidney disease (CKD) is one of the most significant cardiovascular risk factors, playing vital roles in various cardiovascular diseases such as calcific aortic valve disease (CAVD). We aim to explore the CKD-associated genes potentially involving CAVD pathogenesis, and to discover candidate biomarkers for the diagnosis of CKD with CAVD.

METHODS

Three CAVD, one CKD-PBMC and one CKD-Kidney datasets of expression profiles were obtained from the GEO database. Firstly, to detect CAVD key genes and CKD-associated secretory proteins, differentially expressed analysis and WGCNA were carried out. Protein-protein interaction (PPI), functional enrichment and cMAP analyses were employed to reveal CKD-related pathogenic genes and underlying mechanisms in CKD-related CAVD as well as the potential drugs for CAVD treatment. Then, machine learning algorithms including LASSO regression and random forest were adopted for screening candidate biomarkers and constructing diagnostic nomogram for predicting CKD-related CAVD. Moreover, ROC curve, calibration curve and decision curve analyses were applied to evaluate the diagnostic performance of nomogram. Finally, the CIBERSORT algorithm was used to explore immune cell infiltration in CAVD.

RESULTS

The integrated CAVD dataset identified 124 CAVD key genes by intersecting differential expression and WGCNA analyses. Totally 983 CKD-associated secretory proteins were screened by differential expression analysis of CKD-PBMC/Kidney datasets. PPI analysis identified two key modules containing 76 nodes, regarded as CKD-related pathogenic genes in CAVD, which were mostly enriched in inflammatory and immune regulation by enrichment analysis. The cMAP analysis exposed metyrapone as a more potential drug for CAVD treatment. 17 genes were overlapped between CAVD key genes and CKD-associated secretory proteins, and two hub genes were chosen as candidate biomarkers for developing nomogram with ideal diagnostic performance through machine learning. Furthermore, SLPI/MMP9 expression patterns were confirmed in our external cohort and the nomogram could serve as novel diagnosis models for distinguishing CAVD. Finally, immune cell infiltration results uncovered immune dysregulation in CAVD, and SLPI/MMP9 were significantly associated with invasive immune cells.

CONCLUSIONS

We revealed the inflammatory-immune pathways underlying CKD-related CAVD, and developed SLPI/MMP9-based CAVD diagnostic nomogram, which offered novel insights into future serum-based diagnosis and therapeutic intervention of CKD with CAVD.

Correlation between Coronary Artery Disease with Other Arterial Systems: Similar, Albeit Separate, Underlying Pathophysiologic Mechanisms

Atherosclerosis is a multifactorial systemic disease that affects the entire arterial tree, although some areas are more prone to lipid deposits than others. Moreover, the histopathological composition of the plaques differs, and the clinical manifestations are also different, depending on the location and structure of the atherosclerotic plaque. Some arterial systems are correlated with each other more than in that they simply share a common atherosclerotic risk. The aim of this perspective review is to discuss this heterogeneity of atherosclerotic impairment in different arterial districts and to investigate the current evidence that resulted from studies of the topographical interrelations of atherosclerosis.

Cardiovascular Calcification Heterogeneity in Chronic Kidney Disease

Patients with chronic kidney disease (CKD) exhibit tremendously elevated risk for cardiovascular disease, particularly ischemic heart disease, due to premature vascular and cardiac aging and accelerated ectopic calcification. The presence of cardiovascular calcification associates with increased risk in patients with CKD. Disturbed mineral homeostasis and diverse comorbidities in these patients drive increased systemic cardiovascular calcification in different manifestations with diverse clinical consequences, like plaque instability, vessel stiffening, and aortic stenosis. This review outlines the heterogeneity in calcification patterning, including mineral type and location and potential implications on clinical outcomes. The advent of therapeutics currently in clinical trials may reduce CKD-associated morbidity. Development of therapeutics for cardiovascular calcification begins with the premise that less mineral is better. While restoring diseased tissues to a noncalcified homeostasis remains the ultimate goal, in some cases, calcific mineral may play a protective role, such as in atherosclerotic plaques. Therefore, developing treatments for ectopic calcification may require a nuanced approach that considers individual patient risk factors. Here, we discuss the most common cardiac and vascular calcification pathologies observed in CKD, how mineral in these tissues affects function, and the potential outcomes and considerations for therapeutic strategies that seek to disrupt the nucleation and growth of mineral. Finally, we discuss future patient-specific considerations for treating cardiac and vascular calcification in patients with CKD-a population in need of anticalcification therapies.

Calcium isotopes as a biomarker for vascular calcification in chronic kidney disease

Calcium balance is abnormal in adults with chronic kidney disease (CKD) and is associated with the development of vascular calcification. It is currently not routine to screen for vascular calcification in CKD patients. In this cross-sectional study, we investigate whether the ratio of naturally occurring calcium (Ca) isotopes, 44Ca and 42Ca, in serum could be used as a noninvasive marker of vascular calcification in CKD. We recruited 78 participants from a tertiary hospital renal center: 28 controls, 9 subjects with mild-moderate CKD, 22 undertaking dialysis and 19 who received a kidney transplant. For each participant, systolic blood pressure, ankle brachial index, pulse wave velocity, and estimated glomerular filtration rate were measured, along with serum markers. Calcium concentrations and isotope ratios were measured in urine and serum. While we found no significant association between urine Ca isotope composition (noted δ44/42Ca) between the different groups, δ44/42Ca values in serum were significantly different between healthy controls, subjects with mild-moderate CKD and those undertaking dialysis (P < 0.01). Receiver operative characteristic curve analysis shows that the diagnostic utility of serum δ44/42Ca for detecting medial artery calcification is very good (AUC = 0.818, sensitivity 81.8% and specificity 77.3%, P < 0.01), and performs better than existing biomarkers. Although our results will need to be verified in prospective studies across different institutions, serum δ44/42Ca has the potential to be used as an early screening test for vascular calcification.

The pathophysiology and management of vascular calcification in chronic kidney disease patients

INTRODUCTION

Vascular calcification (VC) which is the pathological mineral deposition in the vascular system, predominantly at the intimal and medial layer of the vessel wall, is an important comorbidity in patients with chronic kidney disease (CKD) leading to significant morbidity and mortality while necessitating appropriate treatment. Our review aims to provide an in-depth analysis of the current understanding of VC.

AREAS COVERED

In this review, we first discuss the pathophysiology of VC in CKD patients, then we explain the methods to predict and assess VC. Afterwards, we provide the currently available as well as the potential therapeutic approaches of VC. We finally discuss our understanding regarding the current situation surrounding VC in our expert opinion section.

EXPERT OPINION

Predicting, assessing and treating VC is crucial and the future advances in the field of research surrounding VC will potentially occur in one or more of these three areas of clinical management. There is a current lack of evidence and consensus regarding specific therapeutic options for alleviating VC and this situation may not necessitate VC to be determined, detected, and documented before the available options are implemented. Regardless, the prediction and assessment of VC is still important and requires further improvement together with the developments in therapeutic alternatives. The future has the potential to bring better research which would guide and improve the management of this patient group. A more specialized approach consisting of targeted therapies and more tailored management plans for patients with CKD and VC is on the horizon.

Arteriolar neuropathology in cerebral microvascular disease

Cerebral microvascular disease (MVD) is an important cause of vascular cognitive impairment. MVD is heterogeneous in aetiology, ranging from universal ageing to the sporadic (hypertension, sporadic cerebral amyloid angiopathy [CAA] and chronic kidney disease) and the genetic (e.g., familial CAA, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy [CADASIL] and cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy [CARASIL]). The brain parenchymal consequences of MVD predominantly consist of lacunar infarcts (lacunes), microinfarcts, white matter disease of ageing and microhaemorrhages. MVD is characterised by substantial arteriolar neuropathology involving ubiquitous vascular smooth muscle cell (SMC) abnormalities. Cerebral MVD is characterised by a wide variety of arteriolar injuries but only a limited number of parenchymal manifestations. We reason that the cerebral arteriole plays a dominant role in the pathogenesis of each type of MVD. Perturbations in signalling and function (i.e., changes in proliferation, apoptosis, phenotypic switch and migration of SMC) are prominent in the pathogenesis of cerebral MVD, making 'cerebral angiomyopathy' an appropriate term to describe the spectrum of pathologic abnormalities. The evidence suggests that the cerebral arteriole acts as both source and mediator of parenchymal injury in MVD.

Different vitamin K forms in hemodialysis patients: a simple dietary supplement to battle vascular calcification—randomized controlled trial

Background and aim

Vascular calcification is a significant risk factor for cardiovascular diseases in patients with end-stage renal disease, particularly those on hemodialysis. Previous research on vitamin K found that it had a positive on calcification markers. However, clinical data is still limited. This study aimed to compare the efficacy and safety of vitamin K2 versus vitamin k1 on a calcification regulator in hemodialysis patients.

Methods

A prospective randomized placebo-controlled trial was conducted on 120 patients, who were divided into three groups; group 1: administered 10 mg of vitamin K1 (phytomenadione thrice weekly); group 2: administered 90 μg of vitamin k2 (MK-7); group 3: administered placebo for 3 months. Matrix Gla protein (MGP), calcium, phosphorous, and intact parathyroid hormone levels were measured.

Results

MK-7 significantly increased active MGP levels compared to phytomenadione and placebo groups (p<0.0001). No correlations were found between calcium, phosphorous, PTH, and MGP levels at baseline or after treatment.

Conclusion

Vitamin k supplementation was effective and tolerable in modulating MGP in hemodialysis patients, with MK-7 outperforming phytomenadione.

The BioHybrid Assay: A Novel Method for Determining Calcification Propensity

Vascular calcification is an active pathological process, characterised by cellular dysregulation and subsequent changes to the extracellular environment. In vivo detection of vascular calcification is only possible late stage via computed tomography, and there is no single biomarker for detecting progression of vascular calcification. There is an unmet clinical need to determine progression of vascular calcification in vulnerable patients. This is especially needed in chronic kidney disease (CKD) patients where there is a correlation of cardiovascular disease with declining renal status. We hypothesised that the entirety of circulating components should be taken into consideration with vessel wall cells to determine real-time vascular calcification development. In this protocol we describe the isolation and characterisation of human primary vascular smooth muscle cells (hpVSMCs), and the addition of human serum or plasma to hpVSMCs in a calcification assay and analysis. The BioHybrid analysis of biological changes to in vitro hpVSMC calcification is reflective of in vivo vascular calcification status. We suggest this analysis can discriminate between CKD patient cohorts and has the potential for wider application for risk factor determination in CKD and the general population.

Circulating Fibroblast Growth Factor-23 Levels Can Predict Rapid Kidney Function Decline in a Healthy Population: A Community-Based Study

BACKGROUND

Fibroblast growth factor-23 (FGF-23) associates with decreased kidney function in patients with chronic kidney disease (CKD). However, the correlation between circulating FGF-23 levels and the rate of renal function decline in healthy individuals is largely unknown. We aimed to evaluate the predictive performance of FGF-23 for rapid kidney function decline (RKFD) in a community-based study.

METHODS

A total of 2963 people residing in northern Taiwan were enrolled from August 2013 to May 2018 for an annual assessment of kidney function for five years. The baseline estimated glomerular filtration rates (eGFR) were calculated using the 2009 and 2021 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, which aggregates the values of serum creatinine and cystatin C (eGFRcr-cys). The outcome was RKFD-a 15% decrease in estimated glomerular filtration rate (eGFR) within the first four years, and a reduction in eGFR without improvement in the 5th year. A generalized additive model (GAM) was used to determine the cut-off value of FGF-23 to predict RKFD.

RESULTS

The incidence of RKFD was 18.0% (114/634). After matching for age and sex at a 1:1 ratio, a total of 220 subjects were analyzed. eGFRcr-cys was negatively correlated with total vitamin D level but seemed irrelevant to FGF-23. Multivariable logistic regression analysis showed that FGF-23, eGFRcr-cys, and urine albumin-to-creatinine ratio (UACR) were independent predictors of the possibility of RKFD. FGF-23 showed the best predictive performance for RKFD (AUROC: 0.803), followed by baseline eGFRcr-cys (AUROC: 0.639) and UACR (AUROC: 0.591). From the GAM, 32 pg/mL was the most appropriate cut-off value of FGF-23 with which to predict RKFD. The subgroup and sensitivity analyses showed consistent results that high-FGF-23 subjects had higher risks of RKFD.

CONCLUSIONS

Circulating FGF-23 level could be a helpful predictor for RKFD in this community-based population.

Fibroblast Growth Factor-23 in Pre-Dialysis Chronic Kidney Disease Patients and its Correlation with Carotid Artery Calcification

Introduction

Fibroblast growth factor 23 (FGF-23) is a phosphate metabolism regulator in patients with chronic kidney disease (CKD). The present study is aimed to examine the FGF-23 level in pre-dialysis patients with CKD and its correlation with carotid artery calcification (CAAC).

Methods

This cross-sectional study included patients with CKD and controls. The patients were compared with controls having similar distribution of age and sex to determine serum FGF-23 level in Indian healthy adult population. Detailed medical history, physical examination, and investigations were done for each patient. Atherosclerotic risk factors, cardiovascular comorbidities, and drug history were recorded. Carotid calcification was observed using carotid ultrasound.

Results

In total, 62 patients with a mean age of 50.0 years were enrolled. Majority of the patients had hypertension (66.1%), followed by diabetes (27.4%) and dyslipidemia (3.2%). Mean serum corrected calcium levels were significantly higher in patients with CAAC compared to the patients without CAAC (9.21 ± 1.34 vs. 8.53 ± 0.93 mg/dL; P = 0.014). The FGF-23 levels were significantly higher in patients with CAAC compared to those without CAAC (396.0 vs. 254.0 pg/mL; P = 0.008). CAAC was found to be present in both early and late stages of CKD. Multivariate analysis showed that log FGF-23 and serum corrected calcium remained as independent determinants of CAAC. The prevalence of CAAC increased with the ascending quartiles of FGF23.

Conclusion

In conclusion, FGF-23 was found to be independently associated with CAAC in CKD.

Diabetic foot disease in subjects with End-stage renal Disease: A nationwide study over 14 years highlighting an emerging threat

AIMS

To disclose prevalence, demographic, foot characteristics as well as management and lower-extremity amputations (LEAs) of subjects with end-stage renal disease (ESRD) on diabetic foot diseases (DFDs).

METHODS

Data were derived from the Taiwan National Health Insurance Research Database between 2004 and 2017. DFDs were defined as ulcers, infections, or severe peripheral arterial diseases (PADs) in patients with type 2 diabetes. Clinical characteristics were analyzed between subjects with and without ESRD.

RESULTS

Subjects with ESRD have increased impacts on the DFD population either from annual prevalence (2.7 % to 10.42 %, P for trend < 0.001), or proportional representation in LEAs (7.91 % to 26.37 %, P < 0.001) over 14 years. The annual trends for major-LEAs rates have decreased in both subjects with and without ESRD (13.67 % to 5.82 % and 3.48 % to 1.47 %, both P < 0.001). Notably, the concomitant increase of endovascular treatments (EVTs) (7.09 % to 29.41 %, P < 0.001) was associated with the decrease of major-LEAs (P for interaction < 0.001) in subjects with ESRD.

CONCLUSIONS

As the annual prevalence of subjects with ESRD has increased 3.9-fold over years, they now account for more than 30% of annual major-LEA of the total DFD population. Interdisciplinary team approach and aggressive EVTs might reduce major-LEAs in these patients.

Coronary artery calcification in patients with advanced chronic kidney disease

Introduction

Cardiovascular disease (CVD) is associated with higher morbidity and mortality rates in patients with chronic kidney disease (CKD). Studies have shown that vascular calcification is a major predictor of CVD. Vascular calcification in the CKD population is associated with various risk factors, and changes in bone and mineral metabolism have been linked to an increased risk of atherosclerosis. Therefore, we aimed to investigate the correlation between vascular calcification and bone metabolism, which is necessary to improve the survival and prognosis of patients with CKD.

Methods

We included 146 patients with CKD who received coronary artery calcification (CAC) scores at our hospital from May 2017 to November 2018. Spearman rank correlation analysis, Mann–Whitney U test, and Kaplan–Meier method were used to analyze laboratory data and all-cause mortality.

Results

In the 146 patients, chronic glomerulonephritis accounted for the most common cause of CKD, at approximately 39.0%. Spearman rank correlation analysis on the factors influencing vascular calcification in patients with CKD showed that CAC score was significantly and positively correlated with C-reactive protein, N-terminal/midregion osteocalcin (N-MID), N-terminal peptide of type 1 procollagen (P1NP), β-cross-linked C-telopeptide of type 1 collagen (β-CTx), and parathyroid hormone (P = 0.0423, P = 0.0432, P = 0.0235, P = 0.0061, P < 0.0001, respectively). Serum calcium levels were positively correlated with N-MID, P1NP, β-CTx, and iPTH (r = 0.19, r = 0.24, r = 0.21, r = 0.21, respectively), and serum phosphorus levels were positively correlated with N-MID, P1NP, β-CTx, and iPTH (r = 0.50, r = 0.37, r = 0.50, r = 0.55, respectively). However, no difference was found in CVC scores among patients with CKD in different stages and receiving different treatments. In the Kaplan–Meier analysis of all-cause hospitalization and mortality rates, patients with CAC > 400 had a higher risk.

Conclusion

We found that the primary cause of CKD is glomerulonephritis, and the CAC score is positively correlated with inflammatory and bone metabolism markers, with a higher risk of all-cause mortality and cardiovascular hospitalization when the CAC score is greater than 400.

A CT-based pelvic calcification score in kidney transplant patients is a possible predictor of graft and overall survival

OBJECTIVES

Computerized tomography (CT) is the most accurate method for evaluating pelvic calcifications, which are of utmost importance for planning kidney transplantation (KT). The aim of our study was to evaluate the incidence and distribution of iliac artery calcifications and correlate the novel pelvic calcification score (PCS) with cardiovascular risk factors and graft and overall survival in KT patients.

METHODS

We retrospectively included 118 KT patients operated at our institution with pretransplant pelvic CT. Calcification morphology, circumference and length of both common and external iliac arteries were independently scored by two uroradiologists. PCS was calculated as the total score sum of all three calcification features in all vessels. PCS correlation with graft and patient survival was performed.

RESULTS

Calcification in at least one vascular segment was found in 79% of patients. PCS was significantly higher in male patients (p = 0.006), patients over 55 years (p < 0.001), and patients on haemodialysis (p = 0.016). Patients with a PCS >3 had significantly shorter graft and overall survival rates (p = 0.041 and p = 0.039, respectively).

CONCLUSIONS

The extent of iliac artery calcification in KT recipients quantified by PCS on pretransplant CT correlates with graft and overall patient survival. A PCS over three was associated with worse clinical outcomes and could become a possible prognostic factor.

ADVANCES IN KNOWLEDGE

Our novel PCS is a robust method for quantifying iliac artery calcification burden. Since higher a PCS correlates with worse patient and graft survival, PCS has the potential to become a prognostic factor in kidney transplant patients.

Atherosclerosis Specific Features in Chronic Kidney Disease (CKD)

Atherosclerosis is the major cause of cardiovascular disease, leading to a high mortality rate worldwide. Several risk factors are known to favor atherogenesis, among which are high blood pressure, smoking, diabetes mellitus, and others. Chronic kidney disease is another serious health problem associated with significant health care costs, morbidity, and mortality. Chronic kidney disease shares several risk factors with atherosclerosis and cardiovascular diseases, such as hypertension and diabetes mellitus. Additional risk factors for cardiovascular disease development should be considered in patients with chronic kidney disease. Interestingly, patients suffering from chronic kidney disease are more prone to cardiovascular problems than the general population. Moreover, chronic kidney disease is characterized by an increased atherosclerotic burden from the very early stages. The purpose of this review was to summarize data on atherosclerosis in chronic kidney disease, highlighting the specific features of the disease combination.

A 6-Month clinical practice pilot study of sucroferric oxyhydroxide on nutritional status in patients on peritoneal dialysis

Background

Hyperphosphatemia is common in patients on peritoneal dialysis (PD). Restricting dietary phosphorus often leads to a decrease in protein intake, which may result in hypoalbuminemia. The high pill burden of phosphate binders may also contribute to compromised appetite and dietary intake. Hypoalbuminemia is associated with an increased risk of morbidity and mortality in PD patients. The goal of this study was to determine if sucroferric oxyhydroxide improves albumin and self-reported measures of appetite in PD patients.

Methods

We performed a prospective, open-label, 6-month, pilot study of 17 adult PD patients from the Denver Metro Area. Patients had to use automated peritoneal dialysis for ≥ 3 months, have a serum albumin ≤ 3.8 g/dL, and have serum phosphate ≥ 5.5 mg/dL or ≤ 5.5 mg/dL on a binder other than SO. SO was titrated to a goal serum phosphate of < 5.5 mg/dL. The primary outcome was change in serum phosphate, albumin, and phosphorus-attuned albumin (defined as albumin divided by phosphorus) over 6 months.

Results

The mean (SD) age and dialysis vintage was 55 ± 13 years and 3.8 ± 2.7 years, respectively. Participants’ serum phosphate significantly decreased with fewer phosphate binder pills/day after switching to SO. There was no change in serum albumin, appetite, or dietary intake. However, participants had significant improvements in phosphorus-attuned albumin.

Conclusion

The transition to SO improved phosphorus control, phosphorus-attuned albumin, and pill burden. There were no significant changes in self-reported appetite or dietary intake during the study. These findings suggest that PD patients maintained nutritional status with SO therapy.

Trial registration

First registered at ClinicalTrials.gov (NCT04046263) on 06/08/2019.

Vestibular Hair Cells Require CAMSAP3, a Microtubule Minus-End Regulator, for Formation of Normal Kinocilia

Kinocilia are exceptionally long primary sensory cilia located on vestibular hair cells, which are essential for transmitting key signals that contribute to mammalian balance and overall vestibular system function. Kinocilia have a “9+2” microtubule (MT) configuration with nine doublet MTs surrounding two central singlet MTs. This is uncommon as most mammalian primary sensory cilia have a “9+0” configuration, in which the central MT pair is absent. It has yet to be determined what the function of the central MT pair is in kinocilia. Calmodulin-regulated spectrin-associated protein 3 (CAMSAP3) regulates the minus end of MTs and is essential for forming the central MT pair in motile cilia, which have the “9+2” configuration. To explore the role of the central MT pair in kinocilia, we created a conditional knockout model (cKO), Camsap3-cKO, which intended to eliminate CAMSAP3 in limited organs including the inner ear, olfactory bulb, and kidneys. Immunofluorescent staining of vestibular organs demonstrated that CAMSAP3 proteins were significantly reduced in Camsap3-cKO mice and that aged Camsap3-cKO mice had significantly shorter kinocilia than their wildtype littermates. Transmission electron microscopy showed that aged Camsap3-cKO mice were in fact missing that the central MT pair in kinocilia more often than their wildtype counterparts. In the examination of behavior, wildtype and Camsap3-cKO mice performed equally well on a swim assessment, right-reflex test, and evaluation of balance on a rotarod. However, Camsap3-cKO mice showed slightly altered gaits including reduced maximal rate of change of paw area and a smaller paw area in contact with the surface. Although Camsap3-cKO mice had no differences in olfaction from their wildtype counterparts, Camsap3-cKO mice did have kidney dysfunction that deteriorated their health. Thus, CAMSAP3 is important for establishing and/or maintaining the normal structure of kinocilia and kidney function but is not essential for normal olfaction. Our data supports our hypothesis that CAMSAP3 is critical for construction of the central MT pair in kinocilia, and that the central MT pair may be important for building long and stable axonemes in these kinocilia. Whether shorter kinocilia might lead to abnormal vestibular function and altered gaits in older Camsap3-cKO mice requires further investigation.

Vascular Calcification in Chronic Kidney Disease: An Update and Perspective

Chronic kidney disease is a devastating condition resulting from irreversible loss of nephron numbers and function and leading to end-stage renal disease and mineral disorders. Vascular calcification, an ectopic deposition of calcium-phosphate salts in blood vessel walls and heart valves, is an independent risk factor of cardiovascular morbidity and mortality in chronic kidney disease. Moreover, aging and related metabolic disorders are essential risk factors for chronic kidney disease and vascular calcification. Marked progress has been recently made in understanding and treating vascular calcification in chronic kidney disease. However, there is a paucity of systematic reviews summarizing this progress, and investigating unresolved issues is warranted. In this systematic review, we aimed to overview the underlying mechanisms of vascular calcification in chronic kidney diseases and discuss the impact of chronic kidney disease on the pathophysiology of vascular calcification. Additionally, we summarized potential clinical diagnostic biomarkers and therapeutic applications for vascular calcification with chronic kidney disease. This review may offer new insights into the pathogenesis, diagnosis, and therapeutic intervention of vascular calcification.

The IL-18/IL-18R1 signalling axis: Diagnostic and therapeutic potential in hypertension and chronic kidney disease

Chronic kidney disease (CKD) is inherently an inflammatory condition, which ultimately results in the development of end stage renal disease or cardiovascular events. Low-grade inflammatory diseases such as hypertension and diabetes are leading causes of CKD. Declines in renal function correlate with elevated circulating pro-inflammatory cytokines in patients with these conditions. The inflammasome is an important inflammatory signalling platform that has been associated with low-grade chronic inflammatory diseases. Notably, activation and assembly of the inflammasome causes the auto cleavage of pro-caspase-1 into its active form, which then processes the pro-inflammatory cytokines pro-interleukin (IL)-1β and pro-IL-18 into their active forms. Currently, the nod-like receptor protein 3 (NLRP3) inflammasome has been implicated in the development of CKD in pre-clinical and clinical settings, and the ablation or inhibition of inflammasome components have been shown to be reno-protective in models of CKD. While clinical trials have demonstrated that neutralisation of IL-1β signalling by the drug anakinra lowers inflammation markers in haemodialysis patients, ongoing preclinical studies are showing that this ability to attenuate disease is limited in progressive models of kidney disease. These results suggest a potential predominant role for IL-18 in the development of CKD. This review will discuss the role of the inflammasome and its pro-inflammatory product IL-18 in the development of renal fibrosis and inflammation that contribute to the pathophysiology of CKD. Furthermore, we will examine the potential of the IL-18 signalling axis as an anti-inflammatory target in CKD and its usefulness as diagnostic biomarker to predict acute kidney injury.

The Contribution of Extracellular Vesicles From Senescent Endothelial and Vascular Smooth Muscle Cells to Vascular Calcification

Vascular calcification is an irreversible pathological process associated with a loss of vascular wall function. This process occurs as a result of aging and age-related diseases, such as cardiovascular and chronic kidney diseases, and leads to comorbidities. During these age-related diseases, the endothelium accumulates senescent cells, which stimulate calcification in vascular smooth muscle cells. Currently, vascular calcification is a silent pathology, and there are no early diagnostic tools. Therefore, by the time vascular calcification is diagnosed, it is usually untreatable. Some mediators, such as oxidative stress, inflammation, and extracellular vesicles, are inducers and promoters of vascular calcification. They play a crucial role during vascular generation and the progression of vascular calcification. Extracellular vesicles, mainly derived from injured endothelial cells that have acquired a senescent phenotype, contribute to calcification in a manner mostly dependent on two factors: (1) the number of extracellular vesicles released, and (2) their cargo. In this review, we present state-of-the-art knowledge on the composition and functions of extracellular vesicles involved in the generation and progression of vascular calcification.

Plasma Biomarkers for Clinical Assessment of Bone Mineral Density in Heart Transplanted Patients—A Single-Center Study at Skåne University Hospital in Lund

We aimed to identify plasma biomarkers that predict changes in bone mineral density (BMD) and increase the understanding of impaired BMD after heart transplantation (HT). Twenty-eight adult patients were included. Data, including densitometry and 29 plasma proteins, before and 1 year after HT were analyzed. Pre-HT plasma levels of fibroblast growth factor 23 (FGF23) correlated with post-HT T score in lumbar spine, adjusted for age, gender, and BMI (1.72 [95% CI 1.33; 2.22], p = 0.011). Change (∆; post-HT—pre-HT) in plasma levels of melusin correlated to ∆T score from the lumbar spine (p = 0.028). ∆plasma levels of TR-AP, ITGB2, and Stromelysin-1 correlated to ∆T score from the femoral neck (p < 0.05). However, no correlations remained after adjustments for age, gender, and BMI. In conclusion, elevated plasma FGF23 pre-HT predicted an increase in lumbar BMD after HT. However, the results are surprising since FGF23 is known to be inversely correlated with BMD. This may partly be explained by the complex pathophysiology in this particular cohort. Due to the explorative nature of the study and the small sample size, further investigations of biochemical markers on bone metabolism in this patient population are encouraged.

Hypercalciuria switches Ca2+ signaling in proximal tubular cells, induces oxidative damage to promote calcium nephrolithiasis

Proximal tubule (PT) transports most of the renal Ca2+, which was usually described as paracellular (passive). We found a regulated Ca2+ entry pathway in PT cells via the apical transient receptor potential canonical 3 (TRPC3) channel, which initiates transcellular Ca2+ transport. Although TRPC3 knockout (-/-) mice were mildly hypercalciuric and displayed luminal calcium phosphate (CaP) crystals at Loop of Henle (LOH), no CaP + calcium oxalate (CaOx) mixed urine crystals were spotted, which are mostly found in calcium nephrolithiasis (CaNL). Thus, we used oral calcium gluconate (CaG; 2%) to raise the PT luminal [Ca2+]o further in TRPC3 -/- mice for developing such mixed stones to understand the mechanistic role of PT-Ca2+ signaling in CaNL. Expectedly, CaG-treated mice urine samples presented with numerous mixed crystals with remains of PT cells, which were pronounced in TRPC3 -/- mice, indicating PT cell damage. Notably, PT cells from CaG-treated groups switched their mode of Ca2+ entry from receptor-operated to store-operated pathway with a sustained rise in intracellular [Ca2+] ([Ca2+]i), indicating the stagnation in PT Ca2+ transport. Moreover, those PT cells from CaG-treated groups demonstrated an upregulation of calcification, inflammation, fibrotic, oxidative stress, and apoptotic genes; effects of which were more robust in TRPC3 ablated condition. Furthermore, kidneys from CaG-treated groups exhibited fibrosis, tubular injury and calcifications with significant reactive oxygen species generation in the urine, thus, indicating in vivo CaNL. Taken together, excess PT luminal Ca2+ due to escalation of hypercalciuria in TRPC3 ablated mice induced surplus CaP crystal formation and caused stagnation of PT [Ca2+]i, invoking PT cell injury, hence mixed stone formation.

Effects and safety of traditional Chinese medicine on the gut microbiota of an adult with chronic kidney disease: A protocol for systematic review and meta-analysis

BACKGROUND

Studies have reported that changes in the abundance of gut microbiota may explain the medically helpful responses towards traditional Chinese medicine (TCM), an essential part of alternative and complementary medicine, in treating chronic kidney disease (CKD). This study aimed to illuminate the changes in the abundance of gut microbiota of TCM with CKD.

METHODS

The meta-analysis was performed in the PubMed, Web of Science, EMBASE CNKI, WanFang, VIP, and CBM databases, from its inception to October 2021 to discriminate randomized controlled trials and examine the effects of TCM on CKD. Two researchers independently performed literature selection, data extraction, and quality assessment. The risk of bias of the included studies was estimated by taking into consideration the characteristics including random sequence generation, allocation concealment, blinding of patients, blinding of outcome assessment, completeness of outcome data, selective reporting, and other bias using Cochrane Collaboration's tool for assessing the risk of bias.

RESULTS AND CONCLUSIONS

From the perspective of intestinal flora, this study will provide high-quality evidence for the effectiveness and safety of TCM for CKD. It provides a new therapeutic approach for treating CKD with Chinese herbal medicine combined with Western medicine.

INPLASY REGISTRATION NUMBER

INPLASY2021100118.

Prognosis and risk factors for cardiac valve calcification in Chinese end-stage kidney disease patients on combination therapy with hemodialysis and hemodiafiltration

BACKGROUND

Cardiac valve calcification (CVC) is an important risk factor for cardiovascular complications. However, limited data are available concerning the prevalence, clinical features and risk factors for CVC in end-stage kidney disease (ESKD) patients. In this study, we aimed to assess these parameters in Chinese ESKD patients receiving combination therapy with hemodialysis and hemodiafiltration.

METHODS

We conducted a cross-sectional study on 293 ESKD patients undergoing combination therapy of hemodialysis and hemodiafiltration at the First Affiliated Hospital of Chongqing Medical University from October 2014 to December 2015. CVC was evaluated via echocardiography.

RESULTS

ESKD patients with CVC had a higher prevalence of diabetes mellitus, aortic and/or coronary artery calcification, arrhythmia, heart failure and coronary heart disease; increased systolic, diastolic and pulse pressure; longer duration of hemodialysis and hypertension; reduced hemoglobin, albumin and high-density lipoprotein cholesterol levels; and increased serum calcium and calcium-phosphorus product levels compared with those without CVC. Logistic regression analysis showed that increased dialysis duration (p = 0.006, OR = 2.25), serum calcium levels (p = 0.046, OR = 2.04) and pulse pressure (p < 0.001, OR = 3.22), the presence of diabetes (p = 0.037, OR = 1.81) and decreased serum albumin levels (p = 0.047, OR = 0.54) were risk factors for CVC. The correlation analysis indicated a significantly increased CVCs prevalence with an increase prevalence of heart failure, aortic and coronary artery calcification.

CONCLUSIONS

CVC represents a common complication and a danger signal for cardiovascular events in ESKD patients undergoing combination therapy of hemodialysis and hemodiafiltration. The presence of diabetes, increased pulse pressure, long dialysis duration, hypoalbuminemia and high serum calcium levels were independent risk factors for CVC.

Bone mineral density in pediatric heart transplanted patients: A retrospective single-center study at Skåne University Hospital in Lund 1988-2016

BACKGROUND

Impaired bone mineral density (BMD) and osteoporosis are commonly found in patients who have undergone heart transplantation (HT), which increases the risk for bone fractures which is associated with increased morbidity and mortality in adults. However, the long-term evolution of BMD after HT in pediatric patients has not been thoroughly investigated.

METHOD

Bone mineral density up to 10 years after HT was investigated in 30 patients who underwent HT at an age <20 years at Skåne University Hospital in Lund 1988-2016.

RESULTS

The total observed time was 235 person-years. Before HT, 86% had low BMD for chronologic age in the lumbar spine. In lumbar spine, BMD was significantly lower than normal for chronological age before HT (p = .034), but recovered at the 4th year (p = .009). In whole body, BMD was normal at the 4th annual check-up (p = .030) and remained so throughout the follow-up period. The median T score in the lumbar spine and femoral neck 10 years after HT did not differ between the two groups based on age at HT (<20 years vs 20 years or older; p = .779 in the lumbar spine and p = .388 in the femoral neck).

CONCLUSIONS

Patients who undergo HT at an age of <20 years have low BMD for chronological age already before HT, but BMD may recover completely within the first 4 years after HT. The results indicate no difference in BMD at 10 years after HT between pediatric and adult patients.

Tissue-Nonspecific Alkaline Phosphatase, a Possible Mediator of Cell Maturation: Towards a New Paradigm

Alkaline phosphatase (ALP) is a ubiquitous membrane-bound glycoprotein capable of providing inorganic phosphate by catalyzing the hydrolysis of organic phosphate esters, or removing inorganic pyrophosphate that inhibits calcification. In humans, four forms of ALP cDNA have been cloned, among which tissue-nonspecific ALP (TNSALP) (TNSALP) is widely distributed in the liver, bone, and kidney, making it an important marker in clinical and basic research. Interestingly, TNSALP is highly expressed in juvenile cells, such as pluripotent stem cells (i.e., embryonic stem cells and induced pluripotent stem cells (iPSCs)) and somatic stem cells (i.e., neuronal stem cells and bone marrow mesenchymal stem cells). Hypophosphatasia is a genetic disorder causing defects in bone and tooth development as well as neurogenesis. Mutations in the gene coding for TNSALP are thought to be responsible for the abnormalities, suggesting the essential role of TNSALP in these events. Moreover, a reverse-genetics-based study using mice revealed that TNSALP is important in bone and tooth development as well as neurogenesis. However, little is known about the role of TNSALP in the maintenance and differentiation of juvenile cells. Recently, it was reported that cells enriched with TNSALP are more easily reprogrammed into iPSCs than those with less TNSALP. Furthermore, in bone marrow stem cells, ALP could function as a "signal regulator" deciding the fate of these cells. In this review, we summarize the properties of ALP and the background of ALP gene analysis and its manipulation, with a special focus on the potential role of TNSALP in the generation (and possibly maintenance) of juvenile cells.

Tannic acid attenuates vascular calcification-induced proximal tubular cells damage through paracrine signaling

Vascular calcification is common in chronic kidney disease; however, the extent to which such condition can affect the renal microvasculature and the neighboring cell types is unclear. Our induced-calcification model in renal proximal tubular (PT) cells exhibited endoplasmic reticulum (ER) stress and oxidative damage, leading to apoptosis. Here, we utilized such calcification in mouse vascular smooth muscle (MOVAS-1) cells as a vascular calcification model, because it exhibited reactive oxygen species (ROS) generation, ER and oxidative stress, inflammatory, and apoptotic gene expressions. To demonstrate whether the vascular calcification condition can dictate the function of the adjacent PT cell layer, we utilized a Transwell multilayer culture system by combining those MOVAS-1 cells in the bottom chamber and polarized PT cells in the upper chamber to show the dimensional cross-signaling effect. Interestingly, calcification of MOVAS-1 cells, in this co-culture, induced H2O2 and lactate dehydrogenase (LDH) release leading to store-operated Ca2+ entry, ROS generation, and activation of oxidative, inflammatory, and apoptotic gene expressions in PT cells through paracrine signaling. Interestingly, application of tannic acid (TA) to either calcified MOVAS-1 or uncalcified PT cells diminished such detrimental pathway activation. Furthermore, the TA-mediated protection was much higher in the PT cells when applied on the calcified MOVAS-1 cells, and the delayed the pathological effects in neighboring PT cells can well be via paracrine signaling. Together, these results provide evidence of vascular calcification-induced PT cell damage, and the protective role of TA in preventing such pathological consequences, which can potentially be used as a nephroprotective remedy.

Elucidating the relationship between nutrition indices and coronary artery calcification in patients undergoing maintenance hemodialysis

Cardiovascular diseases (CVD) are common in maintenance hemodialysis (MHD) patients, and vascular calcification is associated with the incidence of CVD. Malnourished MHD patients are particularly prone to CVD events. Thus far, there is no clear explanation for the relationship of nutrition status with vascular calcification; therefore, we investigated the relationship between malnutrition and vascular calcification. One hundred thirty-one patients underwent laboratory testing, assessment of vascular calcification, modified quantitative subjective global assessment (MQSGA), bioelectrical impedance analysis (BIA), and anthropometric measurements. The patients were divided into two groups based on the presence or absence of coronary artery calcification (CAC), and nutritional statuses were compared between the two groups. The MQSGA score was higher in the CAC group (mean 10.9 ± 1.81) than in the no-CAC group (mean 10.2 ± 1.51); in addition, the mean phase angle (PA) value was significantly lower in the CAC group than in the no-CAC group. Stratification according to CAC score showed that age, Kt/V, incidence of valve calcification, incidence of abdominal aortic calcification, MQSGA score, and blood cell mass were related to the severity of CAC. In addition, quartile analysis revealed that MQSGA score and PA value were related to the incidence and severity of vascular calcification. Binary regression analysis showed that MQSGA score, age, hemoglobin level, and high-density lipoprotein level were independent risk factors for dialysis-related CAC. Patients on MHD who exhibited malnutrition were more likely to have vascular calcification, especially CAC. Namely, the higher the MQSGA score, the lower the PA, and the more likely the occurrence of CAC.

Overexpression of HOTAIR attenuates Pi-induced vascular calcification by inhibiting Wnt/β-catenin through regulating miR-126/Klotho/SIRT1 axis

Vascular calcification is one of the most common effects of macrovascular complications in patients in aging with chronic kidney disease and diabetes. Previous studies showed that HOTAIR attenuated vascular calcification via the Wnt/β-catenin-signaling pathway, yet the molecular mechanism has not been fully elucidated. This study aimed to identify the explicit molecular mechanism underlying HOTAIR regulated vascular calcification. In the phosphate (Pi)-induced calcification model of human aortic smooth muscle cells (HASMCs), we investigated whether HOTAIR was involved in the regulation of miR-126. The luciferase reporter was used to examine the effect of HOTAIR on miR-126 and miR-126 on Klotho 3'-UTR. Furthermore, we overexpressed Klotho to verify the regulation of Klotho on SIRT1, as well as their roles in mediating Pi-induced calcification in HASMCs via the Wnt/β-catenin signaling pathway. Finally, the results were verified in an in vivo mice calcification model. Overexpression of HOTAIR reduced the expression of miR-126 in Pi-induced HASMCs. Additionally, knockdown of miR-126 increased SIRT1 expression by regulating Klotho expression. An increased level of Klotho inhibited Wnt/β-catenin signaling pathway, which eventually attenuated Pi-induced HASMCs calcification. Luciferase reporter assay revealed that HOTAIR targeted miR-126 and miR-126 could directly target Klotho. Eventually, HOTAIR overexpression reversed Pi-induced calcium calcification in vivo mouse models. This study demonstrated that HOTAIR overexpression attenuated Pi-induced calcification by regulating the miR-126/Klotho/SIRT1 axis, thereby inhibiting the Wnt/β-catenin signaling pathway. It provides new potential target genes for the clinical treatment of vascular calcification.

Emerging role of exosomes in arterial and renal calcification

Exosomes are small, cell-derived vesicles of 30-100 nm that participate in cell-to-cell communication. They are released by many cells, such as dendritic cells (DC), lymphocytes, platelets, epithelial cells, endothelial cells (EC), and are found in most body fluids, including blood, saliva, urine, and breast milk. The exosomes released from cells within the cardiovascular system may contain either inhibitors of calcification in normal physiological conditions or promoters in the pathological environment [atherosclerosis (AS), and Chronic Kidney Disease (CKD)]. The exosomes of the vascular smooth muscle cells (VSMCs) are novel players in vascular repair processes and calcification. Several studies have shown that the cytoplasmic contents of exosomes are rich in a variety of proteins, nucleic acids, and lipids. Currently, exosomal micro RNAs and proteins are increasingly being recognized as biomarkers for the diagnosis of several diseases, including those of kidney and liver, as well as different types of cancer. In this review, we summarize recent advances in the role of exosomes in vascular calcification and their potential applications as diagnostic markers as well as a brief overview of the role of stem cell-derived exosomes in cardiovascular diseases.

Uremic Toxins in the Progression of Chronic Kidney Disease and Cardiovascular Disease: Mechanisms and Therapeutic Targets

Chronic kidney disease (CKD) is a progressive loss of renal function. The gradual decline in kidney function leads to an accumulation of toxins normally cleared by the kidneys, resulting in uremia. Uremic toxins are classified into three categories: free water-soluble low-molecular-weight solutes, protein-bound solutes, and middle molecules. CKD patients have increased risk of developing cardiovascular disease (CVD), due to an assortment of CKD-specific risk factors. The accumulation of uremic toxins in the circulation and in tissues is associated with the progression of CKD and its co-morbidities, including CVD. Although numerous uremic toxins have been identified to date and many of them are believed to play a role in the progression of CKD and CVD, very few toxins have been extensively studied. The pathophysiological mechanisms of uremic toxins must be investigated further for a better understanding of their roles in disease progression and to develop therapeutic interventions against uremic toxicity. This review discusses the renal and cardiovascular toxicity of uremic toxins indoxyl sulfate, p-cresyl sulfate, hippuric acid, TMAO, ADMA, TNF-α, and IL-6. A focus is also placed on potential therapeutic targets against uremic toxicity.

Effects of Chronic Kidney Disease and Uremic Toxins on Extracellular Vesicle Biology

Vascular calcification (VC) is a cardiovascular complication associated with a high mortality rate, especially in patients with diabetes, atherosclerosis or chronic kidney disease (CKD). In CKD patients, VC is associated with the accumulation of uremic toxins, such as indoxyl sulphate or inorganic phosphate, which can have a major impact in vascular remodeling. During VC, vascular smooth muscle cells (VSMCs) undergo an osteogenic switch and secrete extracellular vesicles (EVs) that are heterogeneous in terms of their origin and composition. Under physiological conditions, EVs are involved in cell-cell communication and the maintenance of cellular homeostasis. They contain high levels of calcification inhibitors, such as fetuin-A and matrix Gla protein. Under pathological conditions (and particularly in the presence of uremic toxins), the secreted EVs acquire a pro-calcifying profile and thereby act as nucleating foci for the crystallization of hydroxyapatite and the propagation of calcification. Here, we review the most recent findings on the EVs’ pathophysiological role in VC, the impact of uremic toxins on EV biogenesis and functions, the use of EVs as diagnostic biomarkers and the EVs’ therapeutic potential in CKD.

The Crosstalk between Calcium Ions and Aldosterone Contributes to Inflammation, Apoptosis, and Calcification of VSMC via the AIF-1/NF-κB Pathway in Uremia

Vascular calcification is a major complication of maintenance hemodialysis patients. Studies have confirmed that calcification mainly occurs in the vascular smooth muscle cells (VSMC) of the vascular media. However, the exact pathogenesis of VSMC calcification is still unknown. This study shows that the crosstalk between calcium and aldosterone via the allograft inflammatory factor 1 (AIF-1) pathway contributes to calcium homeostasis and VSMC calcification, which is a novel mechanism of vascular calcification in uremia. In vivo results showed that the level of aldosterone and inflammatory factors increased in calcified arteries, whereas no significant changes were observed in peripheral blood. However, the expression of inflammatory factors markedly increased in the peripheral blood of uremic rats without aortic calcification and gradually returned to normal levels with aggravation of aortic calcification. In vitro results showed that there was an interaction between calcium ions and aldosterone in macrophages or VSMC. Calcium induced aldosterone synthesis, and in turn, aldosterone also triggered intracellular calcium content upregulation in macrophages or VSMC. Furthermore, activated macrophages induced inflammation, apoptosis, and calcification of VSMC. Activated VSMC also imparted a similar effect on untreated VSMC. Finally, AIF-1 enhanced aldosterone- or calcium-induced VSMC calcification, and NF-κB inhibitors inhibited the effect of AIF-1 on VSMC. These in vivo and in vitro results suggest that the crosstalk between calcium ions and aldosterone plays an important role in VSMC calcification in uremia via the AIF-1/NF-κB pathway. Local calcified VSMC induced the same pathological process in surrounding VSMC, thereby contributing to calcium homeostasis and accelerating vascular calcification.

Detection of calcified atheromas on panoramic radiographs of cirrhotic patients

BACKGROUND

The present study aimed to investigate the prevalence of calcified atheromas in carotid arteries (CACA) on panoramic radiographs of patients with liver cirrhosis (LC).

METHODS AND RESULTS

A case-control study of 67 individuals with LC (case group) and 67 healthy individuals (control group), matched by gender and age, was performed. In addition to demographic information, data on LC were also collected for the case group. Panoramic radiographs were evaluated by two previously calibrated examiners. The sample consisted predominantly of male individuals (n = 50; 74.62%), with mean age of 55 years old. In the case group, the mean value for the model of end-stage liver disease was 16, and the major aetiology of LC was alcoholism (n = 26; 38.8%). Thirteen (19.4%) LC patients had CACA, whereas only four (5.9%) healthy patients had this condition. LC patients are 3.72 times more likely to have CACA compared to healthy individuals (P = .02). The presence of nephropathies increases the risk of development of atheromas by 18.58 times in cirrhotic individuals (P = .04).

CONCLUSIONS

Cirrhotic patients are more likely to have CACA compared to healthy patients, and this risk increases significantly when kidney disease is involved.

High-phosphorus diets reduce aortic lesions and cardiomyocyte size and modify lipid metabolism in Ldl receptor knockout mice

The consumption of phosphorus in Western populations largely exceeds the recommended intake, while vitamin D supply is often insufficient. Both situations are linked to an increased cardiovascular risk. A 17-week two-factorial study with Ldl receptor^-/- mice was conducted to investigate the cardiovascular impact of dietary phosphorus [adequate (0.3%; P_0.3) vs. high (1.5%; P_1.5)] in combination with a low (50 IU/kg; D₅₀) or adequate vitamin D diet (1000 IU/kg; D₁₀₀₀). The data demonstrate that mice fed the P_1.5 vs. P_0.3 diets developed smaller vascular lesions (p = 0.013) and cardiac hypotrophy (p = 0.011), which were accompanied by diminished IGF1 and insulin signalling activity in their hearts. Vitamin D showed no independent effect on atherogenesis and heart morphology. Feeding P_1.5 vs. P_0.3 diets resulted in markedly reduced serum triacylglycerols (p < 0.0001) and cholesterol (p < 0.0001), higher faecal lipid excretion (p < 0.0001) and a reduced mRNA abundance of hepatic sterol exporters and lipoprotein receptors. Minor hypocholesterolaemic and hypotriglyceridaemic effects were also found in mice fed the D₁₀₀₀ vs. D₅₀ diets (p = 0.048, p = 0.026). To conclude, a high phosphorus intake strongly affected the formation of vascular lesions, cardiac morphology, and lipid metabolism, although these changes are not indicative of an increased cardiovascular risk.

Vascular Calcifications are Associated with Increased Mortality in Patients with Acute Mesenteric Ischemia

BACKGROUND

Vascular calcifications have been identified as predictors of mortality in several cardiovascular diseases but have not been investigated in context of acute mesenteric ischemia. The aim of this study was to investigate the impact of vascular calcifications in patients with acute mesenteric ischemia.

METHODS

Patients admitted for an acute mesenteric ischemia were retrospectively included. The presence of calcifications in the visceral aorta, the celiac trunk, the superior mesenteric artery, and the renal arteries was assessed on computed tomography scan images at the arterial phase. The calcification volumes were measured using the software Aquarius iNtuition Edition®.

RESULTS

The all-cause mortality was 55 out of 86 patients (63.9%) for a median follow-up of 3.5 days (1-243). The survival rate of patients with calcification in the superior mesenteric artery was significantly lower than that of those without calcification (22% vs. 55.6%, P = 0.019). Patients who died had significantly a higher frequency of calcifications in the superior mesenteric artery, the visceral aorta, the celiac trunk, and the renal arteries.

CONCLUSIONS

The presence of vascular calcifications in the superior mesenteric artery is associated with increased mortality in patients diagnosed with acute mesenteric ischemia. Further studies are required to identify the mechanisms underlying this association.

OGT knockdown counteracts high phosphate-induced vascular calcification in chronic kidney disease through autophagy activation by downregulating YAP

AIMS

Pathological vascular calcification (VC), a major risk factor for cardiovascular mortality, is a highly prevalent finding in patients with chronic kidney disease (CKD). We previously analyzed several pathways protecting against high phosphate-induced VC through induction of autophagy. Here, we explored how O-GlcNAc transferase (OGT) affected high phosphate-induced VC of CKD though mediation of autophagy.

MAIN METHODS

In the rats with CKD induced by 5/6 nephrectomy, the VC process was accelerated by a high phosphate diet. The calcification of vascular smooth muscle cells (VSMCs) was induced by high phosphate treatment. We then experimentally tested the effect of OGT on high phosphate-induced VC by conducting loss-of-function experiments. Co-immunoprecipitation and GST pull-down assays were performed to evaluate interaction between OGT and Yes-associated protein (YAP). In mechanistic studies of this pathway, we measured autophagy protein expression and autophagosome formation, as well as calcium deposition and calcium content in VSMCs and in vivo in response to altered expression of OGT and/or YAP.

KEY FINDINGS

OGT was up-regulated in high phosphate-induced VC models in vitro and in vivo. High phosphate-induced calcification in the rat aorta and VSMCs were suppressed by OGT silencing. OGT promoted the glycosylation of YAP to enhance its stability. Importantly, over-expressing YAP reduced autophagy and OGT expedited high phosphate-induced VC by inhibiting autophagy through upregulation of YAP.

SIGNIFICANCE

OGT silencing downregulated YAP to induce autophagy activation, thus suppressing high phosphate-induced VC, which highlighted a promising preventive target against high phosphate-induced VC in CKD.