Mechanisms of vascular calcification in chronic kidney disease

The role of exercise training on cardiovascular risk factors and heart disease in patients with chronic kidney disease G3-G5 and G5D: a Clinical Consensus Statement of the European Association of Preventive Cardiology of the ESC and the European Association of Rehabilitation in Chronic Kidney Disease

Cardiovascular (CV) morbidity and mortality is high in patients with chronic kidney disease (CKD). Most patients reveal a high prevalence of CV risk factors such as diabetes or arterial hypertension and many have manifest cardiovascular disease (CVD), such as coronary artery disease and chronic heart failure with an increased risk of clinical events including sudden cardiac death. Diabetes mellitus and hypertension contribute to the development of CKD and the prevalence of CKD is in the range of 20-65% in diabetic and 30-50% in hypertensive patients. Therefore, prevention and optimal treatment of CV risk factors and comorbidities are key strategies to reduce CV risk and improve survival in CKD. Beyond common CV risk factors, patients with CKD are often physically inactive and have low physical function leading to subsequent frailty with muscle fatigue and weakness, sarcopenia and increased risk of falling. Consequently, the economic health burden of CKD is high, requiring feasible strategies to counteract this vicious cycle. Regular physical activity and exercise training (ET) have been shown to be effective in improving risk factors, reducing CVD and reducing frailty and falls. Nonetheless, combining ET and a healthy lifestyle with pharmacological treatment is not frequently applied in clinical practice. For that reason, this Clinical Consensus Statement reviews the current literature and provides evidence-based data regarding the role of ET in reducing CV and overall burden in patients with CKD. The aim is to increase awareness among cardiologists, nephrologists, and healthcare professionals of the potential of exercise therapy in order to encourage implementation of ET in clinical practice, eventually reducing CV risk and disease, as well as reducing frailty in patients with CKD G3-G5D.

The biological function of demethylase ALKBH1 and its role in human diseases

AlkB homolog 1 (ALKBH1) is a member of the AlkB family of dioxygenases that are dependent on Fe(II) and α-ketoglutarate. Mounting evidence demonstrates that ALKBH1 exhibits enzymatic activity against various substrates, including N6-methyladenosine (m6A), N1-methyladenosine (m1A), N3-methylcytidine (m3C), 5-methylcytosine (m5C), N6-methyladenine (N6-mA, 6mA), and H2A, indicating its dual roles in different biological processes and involvement in human diseases. Up to the present, there is ongoing debate regarding ALKBH1's enzymatic activity. In this review, we present a comprehensive summary of recent research on ALKBH1, including its substrate diversity and pathological roles in a wide range of human disorders, the underlying mechanisms of its functions, and its dysregulation. We also explored the potential of ALKBH1 as a prognostic target.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

SNF472: a novel therapeutic agent for vascular calcification and calciphylaxis

Vascular calcification is a common complication in patients with chronic kidney disease (CKD) and is strongly associated with an increased risk of cardiovascular events and all-cause mortality. Calciphylaxis is a specific and life-threatening manifestation of vascular calcifications that usually affects individuals with advanced kidney function impairment or those undergoing dialysis. Currently, the treatment of vascular calcification and calciphylaxis in CKD lacks approved treatments and focuses on controlling risk factors. SNF472, the intravenous formulation of myo-inositol hexaphosphate, is a novel vascular calcification inhibitor currently undergoing phase 3 clinical trials, demonstrating its ability to directly inhibit the formation of calcium and phosphorus crystals, thereby blocking the production and deposition of ectopic calcium. The efficacy and safety of SNF472 in inhibiting vascular calcification have been confirmed in recent clinical studies. This review summarizes the results of studies related to SNF472 to provide a comprehensive overview of its mechanism of action, efficacy, safety, and ongoing clinical studies.

Activation of the IKK2/NF-κB pathway in VSMCs inhibits calcified vascular stiffness in CKD

IKK2/NF-κB pathway-mediated inflammation in vascular smooth muscle cells (VSMCs) has been proposed to be an etiologic factor in medial calcification and stiffness. However, the role of the IKK2/NF-κB pathway in medial calcification remains to be elucidated. In this study, we found that chronic kidney disease (CKD) induces inflammatory pathways through the local activation of the IKK2/NF-κB pathway in VMSCs associated with calcified vascular stiffness. Despite reducing the expression of inflammatory mediators, complete inhibition of the IKK2/NF-κB pathway in vitro and in vivo unexpectedly exacerbated vascular mineralization and stiffness. In contrast, activation of NF-κB by SMC-specific IκBα deficiency attenuated calcified vascular stiffness in CKD. Inhibition of the IKK2/NF-κB pathway induced cell death of VSMCs by reducing anti-cell death gene expression, whereas activation of NF-κB reduced CKD-dependent vascular cell death. In addition, increased calcification of extracellular vesicles through the inhibition of the IKK2/NF-κB pathway induced mineralization of VSMCs, which was significantly reduced by blocking cell death in vitro and in vivo. This study reveals that activation of the IKK2/NF-κB pathway in VSMCs plays a protective role in CKD-dependent calcified vascular stiffness by reducing the release of apoptotic calcifying extracellular vesicles.

Phosphate in Cardiovascular Disease: From New Insights Into Molecular Mechanisms to Clinical Implications

Hyperphosphatemia is a common feature in patients with impaired kidney function and is associated with increased risk of cardiovascular disease. This phenomenon extends to the general population, whereby elevations of serum phosphate within the normal range increase risk; however, the mechanism by which this occurs is multifaceted, and many aspects are poorly understood. Less than 1% of total body phosphate is found in the circulation and extracellular space, and its regulation involves multiple organ cross talk and hormones to coordinate absorption from the small intestine and excretion by the kidneys. For phosphate to be regulated, it must be sensed. While mostly enigmatic, various phosphate sensors have been elucidated in recent years. Phosphate in the circulation can be buffered, either through regulated exchange between extracellular and cellular spaces or through chelation by circulating proteins (ie, fetuin-A) to form calciprotein particles, which in themselves serve a function for bulk mineral transport and signaling. Either through direct signaling or through mediators like hormones, calciprotein particles, or calcifying extracellular vesicles, phosphate can induce various cardiovascular disease pathologies: most notably, ectopic cardiovascular calcification but also left ventricular hypertrophy, as well as bone and kidney diseases, which then propagate phosphate dysregulation further. Therapies targeting phosphate have mostly focused on intestinal binding, of which appreciation and understanding of paracellular transport has greatly advanced the field. However, pharmacotherapies that target cardiovascular consequences of phosphate directly, such as vascular calcification, are still an area of great unmet medical need.

Potential Role of Bone Scintigraphy in the Diagnosis of Calciphylaxis

Nonosseous abnormalities are often seen on bone scans and can be related to a wide variety of pathology ranging across vascular, infection, and inflammatory etiology. Diffuse soft tissue radiotracer uptake on bone scans is typically attributed to renal or metabolic derangements. Calciphylaxis is the deposition of calcium in small blood vessels, skin, and other organs leading to vascular obstruction and skin necrosis. It is a rare disorder with unknown pathophysiology. Diagnosis of calciphylaxis is challenging and requires an interdisciplinary approach including clinical findings, laboratory results, medical imaging, and skin biopsy. An early diagnosis is important as the disease is associated with high morbidity and mortality. The purpose of this review article is to highlight the role of bone scintigraphy in the evaluation of calciphylaxis and to correlate the findings with other imaging modalities and histopathology.

Shh-Gli2-Runx2 inhibits vascular calcification

BACKGROUND

In patients with chronic kidney disease (CKD), vascular calcification (VC) is common and is associated with a higher risk of all-cause mortality. Shh, one ligand for Hedgehog (Hh) signaling, participates in osteogenesis and several cardiovascular diseases. However, it remains unclear whether Shh is implicated in the development of VC.

METHODS

Inorganic phosphorus 2.6 mM was used to induce vascular smooth muscle cells (VSMCs) calcification. Mice were fed with adenine diet supplement with 1.2% phosphorus to induce VC.

RESULTS

Shh was decreased in VSMCs exposed to inorganic phosphorus, calcified arteries in mice fed with an adenine diet, as well as radial arteries from patients with CKD presenting VC. Overexpression of Shh inhibited VSMCs ostosteoblastic differentiation and calcification, whereas its silencing accelerated these processes. Likewise, mice treated with smoothened agonist (SAG; Hh signaling agonist) showed alleviated VC, and mice treated with cyclopamine (CPN; Hh signaling antagonist) exhibited severe VC. Additionally, overexpression of Gli2 significantly reversed the pro-calcification effect of Shh silencing on VSMCs, suggesting that Shh inhibited VC via Gli2. Mechanistically, Gli2 interacted with Runx2 and promoted its ubiquitin proteasomal degradation, therefore protecting against VC. Of interest, the pro-degradation effect of Gli2 on Runx2 was independent of Smurf1 and Cullin4B.

CONCLUSIONS

Our study provided deeper insight to the pathogenesis of VC, and Shh might be a novel potential target for VC treatment.

Potential Role of Bone Metabolism Markers in Kidney Transplant Recipients

BACKGROUND

The impact of treatments, suppressing the immune system, persistent hyperparathyroidism, and other risk factors on mineral and bone disorder (MBD) after kidney transplantation is well-known. However, there is limited knowledge about their effect on bone metabolism biomarkers. This study aimed to investigate the influence of kidney transplant on these markers, comparing them to patients undergoing hemodialysis and healthy individuals.

METHODS

In this cross-sectional study, three groups were included: kidney transplant patients (n = 57), hemodialysis patients (n = 26), and healthy controls (n = 31). Plasma concentrations of various bone metabolism biomarkers, including Dickkopf-related protein 1, osteoprotegerin, osteocalcin, osteopontin, sclerostin, and fibroblast growth factor 23, were measured. Associations between these biomarkers and clinical and laboratory data were evaluated.

RESULTS

A total of 114 patients participated. Transplant recipients had significantly lower levels of Dickkopf-related protein 1, osteoprotegerin, osteocalcin, osteopontin, sclerostin, and fibroblast growth factor 23 compared to hemodialysis patients. Alkaline phosphatase levels positively correlated with osteopontin (r = 0.572, p < 0.001), while fibroblast growth factor 23 negatively correlated with 25-hydroxyvitamin D (r = -0.531, p = 0.019). The panel of bone biomarkers successfully predicted hypercalcemia (area under the curve [AUC] = 0.852, 95% confidence interval [CI] = 0.679-1.000) and dyslipidemia (AUC = 0.811, 95% CI 0.640-0.982) in transplant recipients.

CONCLUSION

Kidney transplantation significantly improves mineral and bone disorders associated with end-stage kidney disease by modulating MBD markers and reducing bone metabolism markers, such as Dickkopf-related protein 1, osteoprotegerin, osteocalcin, osteopontin, and sclerostin. Moreover, the panel of bone biomarkers effectively predicted hypercalcemia and dyslipidemia in transplant recipients.

UVB-emitting LEDs for reptile lighting: Identifying the risks of nonsolar UV spectra

UVB lamps are used to provide reptiles housed indoors with the UV radiation necessary to synthesize vitamin D3 in their skin. Since 2019, UVB-LED lamps have been on sale for use in reptile husbandry. We performed spectral analysis and mapped the UV irradiance for 18 of these lamps. The positive benefits of UVB-LED lamps over traditional products include greater energy efficiency, freedom from mercury and easy installation without external ballasts. However, the spectra of all the UVB-LED lamps tested had little similarity to the solar UV spectrum. Some lamps emitted short-wavelength, non-terrestrial, radiation known to cause acute photo-kerato-conjunctivitis; we report one case. All lamps were lacking significant output in the range 315-335 nm, essential for natural self-regulation of cutaneous vitamin D3 synthesis, preventing overproduction. We describe a possible risk of serious hypervitaminosis D based on our spectral analysis. We call for long-term animal studies to assess this risk, in which the reptiles under these lamps are exposed to species-appropriate UV index levels according to their Ferguson Zone allocation and serum levels of vitamin D3 and 25(OH)D3 monitored. Spectral modifications of the lamps to make the spectrum more like sunlight may be an essential way of mitigating this risk.

Chronic Kidney Disease Associated with Ischemic Heart Disease: To What Extent Do Biomarkers Help?

Chronic kidney disease represents a complex and multifaceted pathology characterized by the presence of structural or functional renal anomalies associated with a persistent reduction in renal function. As the disease progresses, complications arise due to the chronic inflammatory syndrome, hydro-electrolytic disorders, and toxicity secondary to the uremic environment. Cardiovascular complications are the leading cause of death for these patients. Ischemic cardiac pathology can be both a consequence and complication of chronic kidney disease, highlighting the need to identify specific cardiorenal dysfunction biomarkers targeting pathophysiological mechanisms common to both conditions. This identification is crucial for establishing accurate diagnoses, prognoses, and risk stratifications for patients. This work is intended to elucidate the intricate relationship between chronic kidney disease and ischemic heart disease and to investigate the roles of cardiorenal biomarkers, including cardiac troponin, natriuretic peptides, galectin-3, copeptin, fibroblast growth factor 23 and its co-receptor Klotho, soluble suppression of tumorigenicity 2, and plasma growth differentiation factor 15.

Effect of iron administration on the aortic iron content and vascular calcification in phosphorus-loaded chronic kidney disease rats

BACKGROUND

Cardiovascular disease (CVD) is a major cause of morbidity and mortality in patients with chronic kidney disease (CKD) and could be related to oxidative stress. Vascular calcification (VC) has been established as a critical risk factor for accelerated CVD. In CKD, phosphorus (Pi), iron (Fe) and Nrf2 are modulators of VC and important agonists and antagonists of oxidative stress. The aim of this study was to determine whether Fe administration, which is commonly used to treat renal anemia, affects aortic Fe overload and VC, and whether Nrf2 and its related genes, ferritin H and HIF-1α, are involved in the development of VC.

METHODS

A CKD model was created in rats by administering adenine and simultaneously feeding a high-Pi diet. In addition to control and CKD rats without Fe administration (No-Fe group), Fe was administered orally (PO-Fe group) or intraperitoneally (IP-Fe group) to CKD animals to clarify the effects of Fe administration on the aortic Fe and calcium (Ca) contents and the involvement of Nrf2 and its induced antioxidative proteins, ferritin H and HIF-1α, in VC.

RESULTS

The aortic Fe content increased significantly in the IP-Fe group, which was closely correlated with liver HAMP (hepcidin) expression in all animals. Fe administration had no significant effect on the aortic Ca and Pi contents regardless of the route of Fe administration. The aortic mRNA level of Nrf2 was significantly increased in the IP-Fe group and correlated with serum Pi levels and aortic Fe contents, which could respond to oxidative stress. Notably, the mRNA level of Nrf2 was also significantly correlated with the mRNA levels of ferritin H and HIF-1α. Since we could not measure Nrf2 protein levels in this study, we confirmed the upregulation of HMOX1 and NQO1 mRNA expression in parallel with Nrf2 mRNA.

CONCLUSION

Parenteral Fe administration increased aortic Fe in parallel with the liver HAMP mRNA level but did not affect VC. Aortic Nrf2 mRNA levels correlated significantly with aortic Fe and serum Pi levels and with aortic mRNA levels of ferritin H and HIF-1α as well as HMOX1 and NQO1.

Mixed uremic osteodystrophy: an ill-described common bone pathology in patients with chronic kidney disease

Renal osteodystrophy (ROD) starts early and progresses with further loss of kidney function in patients with chronic kidney disease (CKD). There are four distinct types of ROD based on undecalcified bone biopsy results. Adynamic bone disease and osteomalacia are the predominant forms of low bone turnover, while hyperparathyroid bone disease and mixed uremic osteodystrophy (MUO) are typically associated with high bone turnover. MUO is a prevalent but poorly described pathology that demonstrates evidence of osteomalacia on top of the high bone formation/resorption. The prevalence of MUO ranges from 5 to 63% among different studies. The pathogenesis of MUO is multi-factorial. Altered phosphate homeostasis, hypocalcemia, vitamin D deficiency, increased FGF-23, interleukins 1 and 6, TNF-α, amyloid, and heavy metal accumulation are the main inducers of MUO. The clinical findings of MUO are usually non-specific. The use of non-invasive testing such as bone turnover markers and imaging techniques might help to suspect MUO. However, it is usually impossible to precisely diagnose this condition without performing bone biopsy. The principal management of MUO is to control the maladaptive hyperparathyroidism along with correcting any nutritional mineral deficiencies that may induce mineralization defect. MUO is a common but still poorly understood bone pathology category; it demonstrates the complexity and difficulty in understanding ROD. A large prospective bone biopsy-based studies are needed for better identification as proper diagnosis and management would improve the outcome of patients with MUO.

Activation of the IKK2-NFκB pathway in VSMCs inhibits calcified vascular stiffness in CKD by reducing the secretion of calcifying extracellular vesicles

IKK2-NFκB pathway mediated-inflammation in vascular smooth muscle cells (VSMCs) has been proposed to be an etiologic factor in medial calcification and stiffness. However, the role of the IKK2-NFκB pathway in medial calcification remains to be elucidated. In this study, we found that CKD induces inflammatory pathways through the local activation of the IKK2-NFκB pathway in VMSCs associated with calcified vascular stiffness. Despite reducing the expression of inflammatory mediators, complete inhibition of the IKK2-NFκB pathway in vitro and in vivo unexpectedly exacerbated vascular mineralization and stiffness. In contrast, activation of NFκB by SMC-specific IκB deficiency attenuated calcified vascular stiffness in CKD. Inhibition of the IKK2-NFκB pathway induced apoptosis of VSMCs by reducing anti-apoptotic gene expression, whereas activation of NFκB reduced CKD-dependent vascular cell death. In addition, increased calcifying extracellular vesicles through the inhibition of the IKK2-NFκB pathway induced mineralization of VSMCs, which was significantly reduced by blocking cell death. This study reveals that activation of the IKK2-NFκB pathway in VSMCs plays a protective role in CKD-dependent calcified vascular stiffness by reducing the release of apoptotic calcifying extracellular vesicles.

Arterial stiffness and biological parameters: A decision tree machine learning application in hypertensive participants

Arterial stiffness, measured by arterial stiffness index (ASI), could be considered a main denominator in target organ damage among hypertensive subjects. Currently, no reported ASI normal references have been reported. The index of arterial stiffness is evaluated by calculation of a stiffness index. Predicted ASI can be estimated regardless to age, sex, mean blood pressure, and heart rate, to compose an individual stiffness index [(measured ASI-predicted ASI)/predicted ASI]. A stiffness index greater than zero defines arterial stiffness. Thus, the purpose of this study was 1) to determine determinants of stiffness index 2) to perform threshold values to discriminate stiffness index and then 3) to determine hierarchical associations of the determinants by performing a decision tree model among hypertensive participants without CV diseases. A study was conducted from 53,363 healthy participants in the UK Biobank survey to determine predicted ASI. Stiffness index was applied on 49,452 hypertensives without CV diseases to discriminate determinants of positive stiffness index (N = 22,453) from negative index (N = 26,999). The input variables for the models were clinical and biological parameters. The independent classifiers were ranked from the most sensitives: HDL cholesterol≤1.425 mmol/L, smoking pack years≥9.2pack-years, Phosphate≥1.172 mmol/L, to the most specifics: Cystatin c≤0.901 mg/L, Triglycerides≥1.487 mmol/L, Urate≥291.9 μmol/L, ALT≥22.13 U/L, AST≤32.5 U/L, Albumin≤45.92 g/L, Testosterone≥5.181 nmol/L. A decision tree model was performed to determine rules to highlight the different hierarchization and interactions between these classifiers with a higher performance than multiple logistic regression (p<0.001). The stiffness index could be an integrator of CV risk factors and participate in future CV risk management evaluations for preventive strategies. Decision trees can provide accurate and useful classification for clinicians.

Severe Dystrophic Calcification of a Spinal Cord Stimulator Pulse Generator Pocket: A Case Report

A spinal cord stimulator is an important long-term treatment modality for refractory chronic pain of multiple etiologies. Hardware-related complications remain known adverse events associated with this intervention. Understanding the risk factors for development of such complications is important for optimizing the efficacy and longevity of spinal cord stimulators. This case report highlights an uncommon case of implantable pulse generator site calcification that was discovered incidentally on spinal cord stimulator explant.

The effect of chronic kidney disease on tissue formation of in situ tissue-engineered vascular grafts

Vascular in situ tissue engineering encompasses a single-step approach with a wide adaptive potential and true off-the-shelf availability for vascular grafts. However, a synchronized balance between breakdown of the scaffold material and neo-tissue formation is essential. Chronic kidney disease (CKD) may influence this balance, lowering the usability of these grafts for vascular access in end-stage CKD patients on dialysis. We aimed to investigate the effects of CKD on in vivo scaffold breakdown and tissue formation in grafts made of electrospun, modular, supramolecular polycarbonate with ureido-pyrimidinone moieties (PC-UPy). We implanted PC-UPy aortic interposition grafts (n = 40) in a rat 5/6th nephrectomy model that mimics systemic conditions in human CKD patients. We studied patency, mechanical stability, extracellular matrix (ECM) components, total cellularity, vascular tissue formation, and vascular calcification in CKD and healthy rats at 2, 4, 8, and 12 weeks post-implantation. Our study shows successful in vivo application of a slow-degrading small-diameter vascular graft that supports adequate in situ vascular tissue formation. Despite systemic inflammation associated with CKD, no influence of CKD on patency (Sham: 95% vs CKD: 100%), mechanical stability, ECM formation (Sirius red⁺, Sham 16.5% vs CKD 25.0%-p:0.83), tissue composition, and immune cell infiltration was found. We did find a limited increase in vascular calcification at 12 weeks (Sham 0.08% vs CKD 0.80%-p:0.02) in grafts implanted in CKD animals. However, this was not associated with increased stiffness in the explants. Our findings suggest that disease-specific graft design may not be necessary for use in CKD patients on dialysis.

Vascular calcification in CKD: New insights into its mechanisms

Vascular calcification (VC) is a common complication of chronic kidney disease (CKD) and contributes to an increased risk of cardiovascular morbidity and mortality. However, effective therapies are still unavailable at present. It has been well established that VC associated with CKD is not a passive process of calcium phosphate deposition, but an actively regulated and cell-mediated process that shares many similarities with bone formation. Additionally, numerous studies have suggested that CKD patients have specific risk factors and contributors to the development of VC, such as hyperphosphatemia, uremic toxins, oxidative stress and inflammation. Although research efforts in the past decade have greatly improved our knowledge of the multiple factors and mechanisms involved in CKD-related VC, many questions remain unanswered. Moreover, studies from the past decade have demonstrated that epigenetic modifications abnormalities, such as DNA methylation, histone modifications and noncoding RNAs, play an important role in the regulation of VC. This review seeks to provide an overview of the pathophysiological and molecular mechanisms of VC associated with CKD, mainly focusing on the involvement of epigenetic modifications in the initiation and progression of uremic VC, with the aim to develop promising therapies for CKD-related cardiovascular events in the future.

Soluble CD14 and Osteoprotegerin Associate with Ankle-Brachial Index as a Measure of Arterial Stiffness in Patients with Mild-to-Moderate Chronic Kidney Disease in a Five-Year Prospective Study

INTRODUCTION

Vascular lesions and arterial stiffness appear at early stages of chronic kidney disease (CKD) and follow an accelerated course with disease progression, contributing to high cardiovascular mortality. There are limited prospective data on mechanisms contributing to progression of arterial stiffness in mild-to-moderate CKD (stages 2-3).

METHODS

We applied an affinity proteomics approach to identify candidates of circulating biomarkers with potential impact on vascular lesions in CKD and selected soluble cluster of differentiation 14 (sCD14), angiogenin (ANG), and osteoprotegerin (OPG) for further analysis. We studied their association with ankle-brachial index (ABI) and carotid intima-media thickness, as measures of arteriosclerosis and atherosclerosis, respectively, in 48 patients with CKD stages 2-3, who were prospectively followed and intensively treated for 5 years, and 44 healthy controls.

RESULTS

Concentrations of sCD14 (p < 0.001), ANG (p < 0.001), and OPG (p < 0.05) were higher in patients with CKD 2-3 at baseline, and sCD14 (p < 0.001) and ANG (p < 0.001) remained elevated in CKD patients at follow-up. There were positive correlations between ABI and sCD14 levels (r = 0.36, p = 0.01) and between ABI and OPG (r = 0.31, p = 0.03) at 5 years. The changes in sCD14 during follow-up correlated to changes in ABI from baseline to 5 years (r = 0.41, p = 0.004).

CONCLUSION

Elevated levels of circulating sCD14 and OPG in patients with CKD 2-3 were significantly associated with ABI, a measure of arterial stiffness. An increase in sCD14 over time in CKD 2-3 patients was associated with a corresponding increase in ABI. Further studies are needed to examine if early intensive multifactorial medication to align with international treatment targets may influence cardiovascular outcomes.

Epidermal growth factor receptor inhibition prevents vascular calcifying extracellular vesicle biogenesis

Chronic kidney disease (CKD) increases the risk of cardiovascular disease, including vascular calcification, leading to higher mortality. The release of calcifying extracellular vesicles (EVs) by vascular smooth muscle cells (VSMCs) promotes ectopic mineralization of vessel walls. Caveolin-1 (CAV1), a structural protein in the plasma membrane, plays a major role in calcifying EV biogenesis in VSMCs. Epidermal growth factor receptor (EGFR) colocalizes with and influences the intracellular trafficking of CAV1. Using a diet-induced mouse model of CKD followed by a high-phosphate diet to promote vascular calcification, we assessed the potential of EGFR inhibition to prevent vascular calcification. Furthermore, we computationally analyzed 7,651 individuals in the Multi-Ethnic Study of Atherosclerosis (MESA) and Framingham cohorts to assess potential correlations between coronary artery calcium and single-nucleotide polymorphisms (SNPs) associated with elevated serum levels of EGFR. Mice with CKD developed widespread vascular calcification, associated with increased serum levels of EGFR. In both the CKD mice and human VSMC culture, EGFR inhibition significantly reduced vascular calcification by mitigating the release of CAV1-positive calcifying EVs. EGFR inhibition also increased bone mineral density in CKD mice. Individuals in the MESA and Framingham cohorts with SNPs associated with increased serum EGFR exhibit elevated coronary artery calcium. Given that EGFR inhibitors exhibit clinical safety and efficacy in other pathologies, the current data suggest that EGFR may represent an ideal target to prevent pathological vascular calcification in CKD.NEW & NOTEWORTHY Here, we investigate the potential of epidermal growth factor receptor (EGFR) inhibition to prevent vascular calcification, a leading indicator of and contributor to cardiovascular morbidity and mortality. EGFR interacts and affects the trafficking of the plasma membrane scaffolding protein caveolin-1. Previous studies reported a key role for caveolin-1 in the development of specialized extracellular vesicles that mediate vascular calcification; however, no role of EGFR has been reported. We demonstrated that EGFR inhibition modulates caveolin-1 trafficking and hinders calcifying extracellular vesicle formation, which prevents vascular calcification. Given that EGFR inhibitors are clinically approved for other indications, this may represent a novel therapeutic strategy for vascular calcification.

Calciprotein Particles Induce Endothelial Dysfunction by Impairing Endothelial Nitric Oxide Metabolism

BACKGROUND

Calciprotein particles (CPPs) are associated with the development of vascular calcifications in chronic kidney disease. The role of endothelial cells (ECs) in this process is unknown. Here, we investigated the interaction of CPPs and ECs, thereby focusing on endothelial nitric oxide metabolism and oxidative stress.

METHODS

CPPs were generated in calcium- and phosphate-enriched medium. Human umbilical vein endothelial cells were exposed to different concentrations of CPPs (0-100 µg/mL) for 24 or 72 hours. Ex vivo porcine coronary artery rings were used to measure endothelial cell-dependent vascular smooth muscle cell relaxation after CPP exposure. Serum samples from an early chronic kidney disease cohort (n=245) were analyzed for calcification propensity (measure for CPP formation) and nitrate and nitrite levels (NO_x).

RESULTS

CPP exposure for 24 hours reduced eNOS (endothelial nitric oxide synthase) mRNA expression and decreased nitrite production, indicating reduced nitric oxide bioavailability. Also, 24-hour CPP exposure caused increased mitochondria-derived superoxide generation, together with nitrotyrosine protein residue formation. Long-term (72 hours) exposure of human umbilical vein endothelial cells to CPPs induced eNOS uncoupling and decreased eNOS protein expression, indicating further impairment of the nitric oxide pathway. The ex vivo porcine coronary artery model showed a significant reduction in endothelial-dependent vascular smooth muscle cell relaxation after CPP exposure. A negative association was observed between NO_x levels and calcification propensity (r=-0.136; P=0.049) in sera of (early) chronic kidney disease patients.

CONCLUSIONS

CPPs cause endothelial cell dysfunction by impairing nitric oxide metabolism and generating oxidative stress. Our findings provide new evidence for direct effects of CPPs on ECs and pathways involved.

Serum OPG and RANKL Levels as Risk Factors for the Development of Cardiovascular Calcifications in End-Stage Renal Disease Patients in Hemodialysis

Cardiovascular calcifications (CVC) are frequently observed in chronic kidney disease (CKD) patients and contribute to their cardiovascular mortality. The aim of the present study was to investigate the impact of osteoprotegerin (OPG)/Receptor Activator of NF-κΒ (RANK)/RANK ligand (RANKL) pathway in the development and evolution of CVCs in hemodialysis patients. In total, 80 hemodialysis patients were assessed for the presence of vascular (abdominal aorta and muscular arteries) calcifications and results were correlated to serum OPG and RANKL levels and the OPG/RANKL ratio. Traditional cardiovascular risk factors and mineral bone disease parameters were also estimated. The presence of VCs was also evaluated 5 years after the initiation of the study, and results were correlated to the initial serum OPG levels. Age, diabetes mellitus, coronary artery disease and OPG levels (p < 0.001) were associated with VCs, whereas RANKL levels were not. Multivariate analysis though revealed that only OPG levels were significantly associated with abdominal aorta calcifications (p = 0.026), but they were not correlated with the progression of VCs. Serum OPG levels are positively and independently associated with VCs in HD patients, but not with their progression. RANKL levels did not show any associations, whereas further studies are needed to establish the significance of OPG/RANKL ratio.

Extensive Metastatic Vascular Calcification in a Patient with Chronic Renal Failure and Tubercular Osteomyelitis as Seen on F-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

A 48-year-old male with known tubercular osteomyelitis of the left elbow and chronic renal failure presented with PTH independent hypercalcemia and underwent F-18 fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) to look for any underlying malignancy that might be causing his hypercalcemia. The PET/CT did not reveal any malignancy, but extensive metastatic calcification of small- and medium-sized arteries was noted throughout the body with relative sparing of large vessels. Alkaline tissue such as lungs, gastric mucosa, and kidneys that are usually involved in metastatic calcification were also spared. The underlying pathology for this kind of metastatic calcification was most likely chronic granulomatous disease, which was tubercular osteomyelitis in this patient. We present the PET/CT scan images of this unusual case of metastatic vascular calcification.

Association of aortic arch and aortic valve calcifications with cardiovascular risk in patients on maintenance hemodialysis

Introduction

This study aimed to investigate the association of aortic arch calcification (AoAC) and aortic valve calcification (AVC) with major adverse cardiovascular events (MACE) and cardiovascular and all-cause mortality in patients on maintenance hemodialysis (MHD).

Methods

This study enrolled 297 adult patients with end-stage kidney disease who were on MHD. They were divided into those with an AoAC score <2 without AVC (n = 70, 23.6%), those with an AoAC score <2 with AVC (n = 96, 32.3%), and those with an AoAC score ≥2 regardless of AVC status (n = 131, 44.1%). We analyzed the risks of MACE, cardiovascular and overall mortality among the three groups using Cox proportional hazard analyses. Survival probabilities were estimated using the log-rank test via the Kaplan-Meier method.

Results

Kaplan-Meier analysis revealed that the MACE-free rate and the survival rates of cardiovascular and overall mortality were significantly higher in adult chronic hemodialysis patients with AoAC score <2 without AVC, followed by those with AoAC score <2 with AVC, and then those with AoAC score ≥2 (log-rank test; all p < 0.01). The grade of AoAC is a significant risk factor for MACE, cardiovascular mortality, and overall mortality after adjusting for age and gender Relative to AoAC score <2 without AVC, adult chronic hemodialysis patients with AoAC score ≥2 remained an independently significantly risk factor of MACE (adjusted hazard ratio, 2.17; 95% confidence interval 1.11-4.20; p = 0.023) after adjusting for age, sex, and all significant variables in baseline characteristics.

Conclusion

AoAC grade was positively correlated with a higher risk of MACE and cardiovascular and overall mortality. Furthermore, the presence of AVC modified the adverse cardiovascular risk associated with AoAC in patients on MHD.

Ubiquitin-specific protease 47 is associated with vascular calcification in chronic kidney disease by regulating osteogenic transdifferentiation of vascular smooth muscle cells

Chronic kidney disease (CKD) has recently become a serious health and social concern. Vascular calcification, a common complication of CKD, is a risk factor that increases the incidence and mortality of cardiovascular events in patients with CKD. However, there are currently no effective therapeutic targets that can facilitate treatment with fewer side effects for vascular calcification in CKD. To identify potential therapeutic targets, we performed label-free quantification (LFQ) analyses of protein samples from rat aortic vascular smooth muscle cells (RASMCs) after high-phosphorus treatment by nano-UPLC-MS/MS. We determined that ubiquitin-specific protease 47 (USP47) may be associated with CKD vascular calcification by regulating the osteogenic transdifferentiation of the vascular smooth muscle cell (VSMC) phenotype, thus suggesting a novel and potentially effective therapeutic target for CKD vascular calcification. USP47 knockdown significantly reduced the expression of β-transducin repeat-containing protein (BTRC), serine/threonine-protein kinase akt-1 (AKT1), Klotho, fibroblast growth factor (FGF23), and matrix Gla protein (MGP) in RASMCs after high-phosphorus treatment. Consistent with the results of protein-protein interaction (PPI) analyses, USP47 may be involved in regulating osteogenic transdifferentiation markers, such as runt-related transcription factor 2 (RUNX2), Klotho, FGF23, and MGP through the BTRC/AKT1 pathway upon CKD vascular calcification. These data indicate that USP47 may be associated with vascular calcification in CKD by regulating osteogenic differentiation of VSMCs. USP47 may regulate osteogenic transdifferentiation in VSMCs upon CKD vascular calcification through a process involving the BTRC/AKT1 pathway. This study identified a novel potential therapeutic target for the treatment of vascular calcification in CKD.

The Vascular System: Anatomical, Physiological, Pathological, and Aging Considerations

The vascular system is one of the earliest recognized anatomical systems. It is composed of 3 parts; arterial, capillary, and venous, each with their own unique anatomy and physiology. Blood flow through this system is compromised in aging, atherosclerosis and peripheral vascular disease, and the practicing anesthesiologist must understand both the physiology and pathophysiology of the vascular tree.

Arterial Stiffness and the Canonical WNT/β-catenin Pathway

PURPOSE OF REVIEW

Arterial stiffness (AS) was mainly associated with cardiovascular morbidity and mortality in a hypertensive patient. Some risk factors contribute to the development of AS, such as aging, high blood pressure, vascular calcification, inflammation, and diabetes mellitus. The WNT/β-catenin pathway is implicated in numerous signaling and regulating pathways, including embryogenesis, cell proliferation, migration and polarity, apoptosis, and organogenesis. The activation of the WNT/β-catenin pathway is associated with the development of these risk factors.

RECENT FINDINGS

Aortic pulse wave velocity (PWV) is measured to determine AS, and in peripheral artery disease patients, PWV is higher than controls. An augmentation in PWV by 1 m/s has been shown to increase the risk of cardiovascular events by 14%. AS measured by PWV is characterized by the deregulation of the WNT/β-catenin pathway by the inactivation of its two inhibitors, i.e., DKK1 and sclerostin. Thus, this review focuses on the role of the WNT/β-catenin pathway which contributes to the development of arterial stiffness.

Physiological Mechanisms of Hypertension and Cardiovascular Disease in End-Stage Kidney Disease

PURPOSE OF REVIEW

In this article, we summarize recent advances in understanding hypertension and cardiovascular disease in patients with end-stage kidney disease.

RECENT FINDINGS

Factors such as anemia, valvular and vascular calcification, vasoconstrictors, uremic toxins, hypoglycemia, carbamylated proteins, oxidative stress, and inflammation have all been associated with the progression of cardiovascular disease in end-stage kidney disease but the causality of these mechanisms has not been proven. The high risk of cardiovascular mortality has not improved as in the general population despite many advancements in cardiovascular care over the last two decades. Mechanisms that increase hypertension risk in these patients are centered on the control of extracellular fluid volume; however, over-correction of volume with dialysis can increase risks of intradialytic hypotension and death in these patients. This review presents both recent and classic work that increases our understanding of hypertension and cardiovascular disease in end-stage kidney disease.

Effects of ferric citrate and intravenous iron sucrose on markers of mineral, bone, and iron homeostasis in a rat model of CKD-MBD

BACKGROUND

Anemia and chronic kidney disease-mineral and bone disorder (CKD-MBD) are common and begin early in CKD. Limited studies have concurrently compared the effects of ferric citrate (FC) versus intravenous (IV) iron on CKD-MBD and iron homeostasis in moderate CKD.

METHODS

We tested the effects of 10 weeks of 2% FC versus IV iron sucrose in rats with moderate CKD (Cy/+ male rat) and untreated normal (NL) littermates. Outcomes included a comprehensive assessment of CKD-MBD, iron homeostasis and oxidative stress.

RESULTS

CKD rats had azotemia, elevated phosphorus, parathyroid hormone and fibroblast growth factor-23 (FGF23). Compared with untreated CKD rats, treatment with FC led to lower plasma phosphorus, intact FGF23 and a trend (P = 0.07) toward lower C-terminal FGF23. FC and IV iron equally reduced aorta and heart calcifications to levels similar to NL animals. Compared with NL animals, CKD animals had higher bone turnover, lower trabecular volume and no difference in mineralization; these were unaffected by either iron treatment. Rats treated with IV iron had cortical and bone mechanical properties similar to NL animals. FC increased the transferrin saturation rate compared with untreated CKD and NL rats. Neither iron treatment increased oxidative stress above that of untreated CKD.

CONCLUSIONS

Oral FC improved phosphorus homeostasis, some iron-related parameters and the production and cleavage of FGF23. The intermittent effect of low-dose IV iron sucrose on cardiovascular calcification and bone should be further explored in moderate-advanced CKD.

Distinct role of mitochondrial function and protein kinase C in intimal and medial calcification in vitro

Introduction

Vascular calcification (VC) is a major risk factor for cardiovascular morbidity and mortality. Depending on the location of mineral deposition within the arterial wall, VC is classified as intimal and medial calcification. Using in vitro mineralization assays, we developed protocols triggering both types of calcification in vascular smooth muscle cells (SMCs) following diverging molecular pathways.

Materials and methods and results

Human coronary artery SMCs were cultured in osteogenic medium (OM) or high calcium phosphate medium (CaP) to induce a mineralized extracellular matrix. OM induces osteoblast-like differentiation of SMCs-a key process in intimal calcification during atherosclerotic plaque remodeling. CaP mimics hyperphosphatemia, associated with chronic kidney disease-a risk factor for medial calcification. Transcriptomic analysis revealed distinct gene expression profiles of OM and CaP-calcifying SMCs. OM and CaP-treated SMCs shared 107 differentially regulated genes related to SMC contraction and metabolism. Real-time extracellular efflux analysis demonstrated decreased mitochondrial respiration and glycolysis in CaP-treated SMCs compared to increased mitochondrial respiration without altered glycolysis in OM-treated SMCs. Subsequent kinome and in silico drug repurposing analysis (Connectivity Map) suggested a distinct role of protein kinase C (PKC). In vitro validation experiments demonstrated that the PKC activators prostratin and ingenol reduced calcification triggered by OM and promoted calcification triggered by CaP.

Conclusion

Our direct comparison results of two in vitro calcification models strengthen previous observations of distinct intracellular mechanisms that trigger OM and CaP-induced SMC calcification in vitro. We found a differential role of PKC in OM and CaP-calcified SMCs providing new potential cellular and molecular targets for pharmacological intervention in VC. Our data suggest that the field should limit the generalization of results found in in vitro studies using different calcification protocols.

Phosphate intake, hyperphosphatemia, and kidney function

Phosphate is essential in living organisms and its blood levels are regulated by a complex network involving the kidneys, intestine, parathyroid glands, and the skeleton. The crosstalk between these organs is executed primarily by three hormones, calcitriol, parathyroid hormone, and fibroblast growth factor 23. Largely due to a higher intake of ultraprocessed foods, dietary phosphate intake has increased in the last decades. The average intake is now about twice the recommended dietary allowance. Studies investigating the side effect of chronic high dietary phosphate intake suffer from incomplete dietary phosphate assessment and, therefore, often make data interpretation difficult. Renal excretion is quickly adapted to acute and chronic phosphate intake. However, at the high ends of dietary intake, renal adaptation, even in pre-existing normal kidney function, apparently is not perfect. Experimental intervention studies suggest that chronic excess of dietary phosphate can result in sustained higher blood phosphate leading to hyperphosphatemia. Evidence exists that the price of the homeostatic response (phosphaturia in response to phosphate loading/hyperphosphatemia) is an increased risk for declining kidney function, partly due by intraluminal/tubular calcium phosphate particles that provoke renal inflammation. High dietary phosphate intake and hyperphosphatemia are progression factors for declining kidney function and are associated with higher cardiovascular disease and mortality risk. This is best established for pre-existing chronic kidney disease, but epidemiological and experimental data strongly suggest that this holds true for subjects with normal renal function as well. Here, we review the latest advances in phosphate intake and kidney function decline.

Physiological regulation of phosphate homeostasis

Phosphate homeostasis is dependent on the interaction and coordination of four main organ systems: thyroid/parathyroids, gastrointestinal tract, bone and kidneys, and three key hormonal regulators, 1,25-hydroxyvitamin D3, parathyroid hormone and FGF23 with its co- factor klotho. Phosphorus is a critical nutritional element for normal cellular function, but in excess can be toxic to tissues, particularly the vasculature. As phosphate, it also has an important interaction and inter-dependence with calcium and calcium homeostasis sharing some of the same controlling hormones, although this is not covered in our article. We have chosen to provide a current overview of phosphate homeostasis only, focusing on the role of two major organ systems, the gastrointestinal tract and kidneys, and their contribution to the control of phosphate balance. We describe in some detail the mechanisms of intestinal and renal phosphate transport, and compare and contrast their regulation. We also consider a significant example of phosphate imbalance, with phosphate retention, which is chronic kidney disease; why consequent hyperphosphatemia is important, and some of the newer means of managing it.

Genome-wide Meta-analysis Reveals New Gene Signatures and Potential Drug Targets of Hypertension

The prevalence of hypertension reported around the world is increasing and is an important public health challenge. This study was designed to explore the disease's genetic variations and to identify new hypertension-related genes and target proteins. We analyzed 22 publicly available Affymetrix cDNA datasets of hypertension using an integrated system-level framework involving differential expression genetic (DEG) analysis, data mining, gene enrichment, protein-protein interaction, microRNA analysis, toxicogenomics, gene regulation, molecular docking, and simulation studies. We found potential DEGs after screening out the extracellular proteins. We studied the functional role of seven shortlisted DEGs (ADM, EDN1, ANGPTL4, NFIL3, MSR1, CEBPD, and USP8) in hypertension after disease gene curation analysis. The expression profiling and cluster analysis showed significant variations and enriched GO terms. hsa-miR-365a-3p, hsa-miR-2052, hsa-miR-3065-3p, hsa-miR-603, hsa-miR-7113-3p, hsa-miR-3923, and hsa-miR-524-5p were identified as hypertension-associated miRNA targets for each gene using computational algorithms. We found functional interactions of source DEGs with target and important gene signatures including EGFR, AGT, AVP, APOE, RHOA, SRC, APOB, STAT3, UBC, LPL, APOA1, and AKT1 associated with the disease. These DEGs are mainly involved in fatty acid metabolism, myometrial pathways, MAPK, and G-alpha signaling pathways linked with hypertension pathogenesis. We predicted significantly disordered regions of 71.2, 48.8, and 45.4% representing the mutation in the sequence of NFIL3, USP8, and ADM, respectively. Regulation of gene expression was performed to find upregulated genes. Molecular docking analysis was used to evaluate Food and Drug Administration-approved medicines against the four DEGs that were overexpressed. For each elevated target protein, the three best drug candidates were chosen. Furthermore, molecular dynamics (MD) simulation using the target's active sites for 100 ns was used to validate these 12 complexes after docking. This investigation establishes the worth of systems genetics for finding four possible genes as potential drug targets for hypertension. These network-based approaches are significant for finding genetic variant data, which will advance the understanding of how to hasten the identification of drug targets and improve the understanding regarding the treatment of hypertension.

Phosphate in the Context of Cognitive Impairment and Other Neurological Disorders Occurrence in Chronic Kidney Disease

The nervous system and the kidneys are linked under physiological states to maintain normal body homeostasis. In chronic kidney disease (CKD), damaged kidneys can impair the central nervous system, including cerebrovascular disease and cognitive impairment (CI). Recently, kidney disease has been proposed as a new modifiable risk factor for dementia. It is reported that uremic toxins may have direct neurotoxic (astrocyte activation and neuronal death) and/or indirect action through vascular effects (cerebral endothelial dysfunction, calcification, and inflammation). This review summarizes the evidence from research investigating the pathophysiological effects of phosphate toxicity in the nervous system, raising the question of whether the control of hyperphosphatemia in CKD would lower patients’ risk of developing cognitive impairment and dementia.

Dose-dependent effect of impaired renal function on all-cause mortality in patients following percutaneous coronary intervention

Objective

To determine the risk prediction of various degrees of impaired renal function on all‐cause mortality in patients following percutaneous coronary intervention (PCI).

Background

Patients with chronic kidney disease (CKD) are at high risk of all‐cause mortality after PCI. However, there are less data of various degrees of impaired renal function to predict those risks.

Methods

This was a subgroup analysis of nationwide PCI registry of 22 045 patients. Patients were classified into six CKD stages according to preprocedure estimated glomerular filtration rate (eGFR) (ml/min/1.73 m²): I (≥90), II (60−89), III (30−59), IV (15−29), or V (<15) without or with dialysis. Baseline clinical and angiographic characteristics were compared among patients in each stage. One‐year all‐cause mortality was reported with risk prediction based on CKD stages and other risk factors.

Results

Patients with CKD stage I−V without and with on dialysis were found in 26.9%, 40.8%, 23.2%, 3.9%, 1.5%, and 3.7%, respectively. PCI procedural success and complication rates ranged from 94.0% to 96.2% and 2.8% to 6.1%, respectively. One‐year overall survival among CKD stages I−V was 96.3%, 93.1%, 84.4%, 65.2%, 68.0%, and 69.4%, respectively (p < .001 by log‐rank test). After adjusting covariables, the hazard ratios of all‐cause mortality for CKD stages II−V as compared to stage I by multivariate Cox regression analysis were 1.5, 2.6, 5.3, 5.9, and 7.0, respectively, (p < .001).

Conclusion

Among patients undergoing PCI, lower preprocedure eGFR is associated in a dose‐dependent effect with decreased 1‐year survival. This finding may be useful for risk classification and to guide decision‐making.

Imaging of Chronic Kidney Disease-Mineral and Bone Disorder

The characteristic radiological appearances of metabolic bone and soft tissue diseases in chronic renal failure are described and illustrated in the context of advancing understanding of the complex metabolic changes that occur in chronic kidney disease and its management.

Pediatric Mineral and Bone Disorder of Chronic Kidney Disease and Cardiovascular Disease

Chronic kidney disease is common and causes significant morbidity including shortened lifespans and decrease in quality of life for patients. The major cause of mortality in chronic kidney disease is cardiovascular disease. Cardiovascular disease within the chronic kidney disease population is closely tied with disordered calcium and phosphorus metabolism and driven in part by renal bone disease. The complex nature of renal, bone, and cardiovascular diseases was renamed as mineral and bone disorder of chronic kidney disease to encompass how bone disease drives vascular calcification and contributes to the development of long-term cardiovascular disease, and recent data suggest that managing bone disease well can augment and improve cardiovascular disease status. Pediatric nephrologists have additional obstacles in optimal mineral and bone disorder of chronic kidney disease management such as linear growth and skeletal maturation. In this article, we will discuss cardiovascular and bone diseases in chronic kidney disease and end-stage kidney disease patients with a focus on pediatric issues and concerns.

A Reproducible Mouse Model of Moderate CKD With Early Manifestations of Osteoblastic Transition of Cardiovascular System

Chronic kidney disease (CKD) is a significant public health challenge with a substantial associated risk of mortality, morbidity, and health care expenditure. Culprits that lead to development and progression of CKD are multifaceted and heterogenous in nature. This notion underscores the need for diversification of animal models to investigate its pathophysiology, related complications, and to subsequently enable discovery of novel therapeutics. Importantly, animal models that could recapitulate complications of CKD in both genders are desperately needed. Cardiovascular disease is the most common cause of death in CKD patients that may be due in part to high prevalence of vascular calcification (VC). Using DBA/2 mice that are susceptible to development of VC, we sought to investigate the feasibility and reproducibility of a unilateral ischemia-reperfusion model followed by contralateral nephrectomy (UIRI/Nx) to induce CKD and its related complications in female and male mice. Our results demonstrate that irrespective of gender, mice faithfully displayed complications of moderate CKD following UIRI/Nx as evidenced by significant rise in serum creatinine, albuminuria, higher degree of collagen deposition, elevated expression of classic fibrotic markers, higher circulating levels of FGF-23, PTH and hepcidin. Moreover, we corroborate the osteoblastic transition of aortic smooth muscle cells and cardiomyocytes based on higher levels of osteoblastic markers namely, Cbfa-1, osteopontin, osteocalcin, and osterix. Our data confirms a viable, and consistent model of moderate CKD and its associated complications in both male and female mice. Furthermore, early evidence of osteoblastic transition of cardiovascular system in this model confirms its suitability for studying and implementing potential preventive and/or therapeutic approaches that are urgently needed in this field.

Arterial Stiffness Determinants for Primary Cardiovascular Prevention among Healthy Participants

Background: Arterial stiffness (AS), measured by arterial stiffness index (ASI), can be considered as a major denominator in cardiovascular (CV) diseases. Thus, it remains essential to highlight the risk factors influencing its increase among healthy participants. Methods: According to European consensus, AS is defined as ASI > 10 m/s. The purpose of this study was to investigate the determinants of the arterial stiffness (ASI > 10 m/s) among UK Biobank normotensive and healthy participants without comorbidities and previous CV diseases. Thus, a cross-sectional study was conducted on 22,452 healthy participants. Results: Participants were divided into two groups, i.e., ASI > 10 m/s (n = 5782, 25.8%) and ASI < 10 m/s (n = 16,670, 74.2%). All the significant univariate covariables were included in the multivariate analysis. The remaining independent factors associated with AS were age (OR = 1.063, threshold = 53.0 years, p < 0.001), BMI (OR = 1.0450, threshold = 24.9 kg/m2, p < 0.001), cystatin c (OR = 1.384, threshold = 0.85 mg/L, p = 0.011), phosphate (OR = 2.225, threshold = 1.21 mmol/L, p < 0.001), triglycerides (OR = 1.281, threshold = 1.09 mmol/L, p < 0.001), mean BP (OR = 1.028, threshold = 91.2 mmHg, p < 0.001), HR (OR = 1.007, threshold = 55 bpm, p < 0.001), Alkaline phosphate (OR = 1.002, threshold = 67.9 U/L, p = 0.004), albumin (OR = 0.973, threshold = 46.0 g/L, p < 0.001), gender (male, OR = 1.657, p < 0.001) and tobacco use (current, OR = 1.871, p < 0.001). Conclusion: AS is associated with multiple parameters which should be investigated in future prospective studies. Determining the markers of increased ASI among healthy participants participates in the management of future CV risk for preventive strategies.

Bone marrow mesenchymal stem cell-derived exosomal microRNA-381-3p alleviates vascular calcification in chronic kidney disease by targeting NFAT5

Vascular calcification (VC) is a significant complication of chronic kidney disease (CKD) and cellular apoptosis is one of the intricate mechanisms of VC. Bone marrow mesenchymal stem cell-derived exosome (BMSC-Exo) alleviates VC, but the mechanism remains unclear. We investigated the mechanism of BMSC-Exo using high phosphate stimulated Human aortic smooth muscle cells (HA-VSMCs) and 5/6 subtotal nephrectomy (SNx) rat models. We demonstrated that the effect of BMSC-Exo on the inhibition of cellular apoptosis and calcification partially depended on exosomal microRNA-381-3p (miR-381-3p) both in vivo and in vitro, and confirmed that miR-381-3p could inhibit Nuclear Factor of Activated T cells 5 (NFAT5) expression by directly binding to its 3′ untranslated region. Additionally, we found that severe calcification of arteries in dialysis patients was associated with decreased miR-381-3p and increased NFAT5 expression levels. Collectively, our findings proved that BMSC-Exo plays anti-calcification and anti-apoptosis roles in CKD by delivering enclosed miR-381-3p, which directly targets NFAT5 mRNA, and leads to a better understanding of the mechanism of CKD-VC.

Serum Sclerostin Level Is Negatively Associated with Bone Mineral Density in Hemodialysis Patients

Background and Objectives: Sclerostin and Dickkopf-1 (DKK1) modulate osteoblastogenesis, but their role in bone loss in hemodialysis (HD) patients is inconclusive. This study investigated relationships among lumbar bone mineral density (BMD), serum sclerostin, and DKK1 in HD patients. Materials and Methods: Blood samples were obtained from 75 HD patients. Dual-energy X-ray absorptiometry measured lumbar BMD of the lumbar vertebrae (L2−L4). Enzyme-linked immunosorbent assay revealed serum sclerostin and DKK1 concentrations. Results: There were 10 (13.3%), 20 (26.7%), and 45 (60%) patients defined as presenting with osteoporosis, osteopenia, or normal BMD, respectively. Age, alkaline phosphatase, urea reduction rate, fractional clearance index for urea, sclerostin level, and percentage of female patients are significantly negatively associated with the lumbar BMD and T-score, while the body mass index and waist circumference significantly positively associated with the lumbar BMD and T-score. Multivariate forward stepwise linear regression analysis indicated that serum sclerostin (β = −0.546, adjusted R2 change = 0.454; p < 0.001), age (β = −0.216, adjusted R2 change = 0.041; p = 0.007), and percentage of female HD patients (β = −0.288, adjusted R2 change = 0.072; p = 0.0018) were significantly negatively associated with lumbar BMD in HD patients. Conclusions: Advanced age, female gender, and serum sclerostin level, but not DKK1, were negatively associated with BMD in HD patients.

Salivary phosphate as a biomarker for human diseases

Phosphate is a common ingredient of the daily consumed foods and is absorbed in the intestine and is excreted in the urine through the kidney to maintain the homeostatic balance. For adults, the Recommended Dietary Allowance (RDA) for phosphorus is around 700 mg/day. The change in dietary habits resulted in far more phosphate consumption (almost double) than the RDA, contributing to increased cardiovascular diseases, kidney diseases, and tumor formation. Due to a lack of clinical appreciation for the long-term consequences of chronic phosphate burden on non-communicable disorders, it is rapidly becoming a global health concern. The possible association between dysregulated phosphate metabolism and obesity is not studied in-depth, mainly because such an association is believed to be nonexistent. However, in the animal model of obesity, serum phosphate level was higher than their non-obese controls. In a similar observation line, significantly higher salivary phosphate levels were detected in obese children compared to normal-weight children. Of clinical importance, despite the significant increase of salivary phosphate levels in obese children, the plasma phosphate levels did not change in samples collected from the same group of children. Such disparity between plasma and saliva raised the possibility that human salivary phosphate levels may be an early biomarker of childhood obesity.

Impact of renal function on the prognostic value of mineral metabolism in patients with chronic ischaemic heart disease patients with chronic ischaemic heart disease

BACKGROUND

Parathormone (PTH) is a component of the Mineral Metabolism (MM) system that has been shown recently to add prognostic value in pts. with stable coronary artery disease (SCAD) and average renal function. However, the influence of renal function on the prognostic role of PTH in pts. with SCAD has not been shown yet.

PURPOSE

To assess the influence of estimated glomerular filtration rate (eGFR) on the prognostic role of PTH and other MM markers in pts. with SCAD.

METHODS

We analyzed the prognostic value of MM markers (PTH, klotho, phosphate, calcidiol [25-hydroxyvitamin D], and fibroblast growth factor-23 [FGF23]) in 964 pts. with SCAD and eGFR<60ml/min/1.73 m² (LGFR) vs pts. with eGFR≥60ml/min/1.73 m² (HGFR) included in five hospitals of Madrid. The main outcome was the combination of death with ischemic events (any acute coronary syndrome, ischemic stroke or transient ischemic attack). eGFR was calculated by the Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI).

RESULTS

Age was 60.0 (52.0-72.0) years, 76.2% of patients were men, and eGFR was 80.4 (65.3-93.1) ml/min/1,73 m². Median follow-up was 5.39 (2.81-6.92) years. There were 790 pts. with HGFR and 174 with LGFR. In HGFR pts., predictors of ischemic events or death were plasma levels of calcidiol [HR=0.023 (0.94-0.99) p=0.023], FGF23 [HR=1.00 (1.00-1.003) p=0.036], non-HDL cholesterol [HR=1.01 (1.00-1.01) p=0.026] and high sensitivity troponin I [HR=5.12 (1.67-15.59) p=0.004], along with age [HR=1.03 (1.01-1.05) p=0.01], treatment with statins [HR=0.36 (0.19-0.68) p=0.002], nitrates [HR=1.13 (1.07-2.79) p=0.027], dihydropyridines [HR=1.71 (1.05-2.77) p=0.032], verapamil [HR=5.71 (1.35-24.1) p=0.018], and proton-pump inhibitors [HR=2.23 (1.36-3.68) p= 0.002]. In the LGFR subgroup, predictors of death or ischemic events were PTH plasma levels, [HR=1.01 (1.00-1.01) p=0.005], eGFR [HR=0.96 (0.94-0.99) p=0.004], age [HR=1.06 (1.02-1.10) p=0.003], caucasian race [HR=0.04 (0.004-0.380) p=0.005], and treatment with insulin [HR=2.6 (1.20-5.63) p=0.015].

CONCLUSIONS

In pts. with SCAD, PTH is an independent predictor of poor outcomes only in those with eGFR<60ml/min/1.73 m², while in pts. with eGFR≥60ml/min/1.73 m² calcidiol and FGF23 become the only components of MM that may predict prognosis. Then, renal function influences the predictive power of MM markers in pts. with SCAD.

Cardiovascular benefits from SGLT2 inhibition in type 2 diabetes mellitus patients is not impaired with phosphate flux related to pharmacotherapy

The beneficial cardiorenal outcomes of sodium-glucose cotransporter 2 inhibitors (SGLT2i) in patients with type 2 diabetes mellitus (T2DM) have been substantiated by multiple clinical trials, resulting in increased interest in the multifarious pathways by which their mechanisms act. The principal effect of SGLT2i (-flozin drugs) can be appreciated in their ability to block the SGLT2 protein within the kidneys, inhibiting glucose reabsorption, and causing an associated osmotic diuresis. This ameliorates plasma glucose elevations and the negative cardiorenal sequelae associated with the latter. These include aberrant mitochondrial metabolism and oxidative stress burden, endothelial cell dysfunction, pernicious neurohormonal activation, and the development of inimical hemodynamics. Positive outcomes within these domains have been validated with SGLT2i administration. However, by modulating the sodium-glucose cotransporter in the proximal tubule (PT), SGLT2i consequently promotes sodium-phosphate cotransporter activity with phosphate retention. Phosphatemia, even at physiologic levels, poses a risk in cardiovascular disease burden, more so in patients with type 2 diabetes mellitus (T2DM). There also exists an association between phosphatemia and renal impairment, the latter hampering cardiovascular function through an array of physiologic roles, such as fluid regulation, hormonal tone, and neuromodulation. Moreover, increased phosphate flux is associated with an associated increase in fibroblast growth factor 23 levels, also detrimental to homeostatic cardiometabolic function. A contemporary commentary concerning this notion unifying cardiovascular outcome trial data with the translational biology of phosphate is scant within the literature. Given the apparent beneficial outcomes associated with SGLT2i administration notwithstanding negative effects of phosphatemia, we discuss in this review the effects of phosphate on the cardiometabolic status in patients with T2DM and cardiorenal disease, as well as the mechanisms by which SGLT2i counteract or overcome them to achieve their net effects. Content drawn to develop this conversation begins with proceedings in the basic sciences and works towards clinical trial data.

An update on the phenotypic switching of vascular smooth muscle cells in the pathogenesis of atherosclerosis

Vascular smooth muscle cells (VSMCs) are involved in phenotypic switching in atherosclerosis. This switching is characterized by VSMC dedifferentiation, migration, and transdifferentiation into other cell types. VSMC phenotypic transitions have historically been considered bidirectional processes. Cells can adopt a physiological contraction phenotype or an alternative "synthetic" phenotype in response to injury. However, recent studies, including lineage tracing and single-cell sequencing studies, have shown that VSMCs downregulate contraction markers during atherosclerosis while adopting other phenotypes, including macrophage-like, foam cell, mesenchymal stem-like, myofibroblast-like, and osteochondral-like phenotypes. However, the molecular mechanism and processes regulating the switching of VSMCs at the onset of atherosclerosis are still unclear. This systematic review aims to review the critical outstanding challenges and issues that need further investigation and summarize the current knowledge in this field.

VEGFR3 tyrosine kinase inhibition aggravates cisplatin nephrotoxicity

Expansion of renal lymphatic networks, or lymphangiogenesis (LA), is well recognized during development and is now being implicated in kidney diseases. Although LA is associated with multiple pathological conditions, very little is known about its role in acute kidney injury. The purpose of this study was to evaluate the role of LA in a model of cisplatin-induced nephrotoxicity. LA is predominately regulated by vascular endothelial growth factor (VEGF)-C and VEGF-D, ligands that exert their function through their cognate receptor VEGF receptor 3 (VEGFR3). We demonstrated that use of MAZ51, a selective VEGFR3 inhibitor, caused significantly worse structural and functional kidney damage in cisplatin nephrotoxicity. Apoptotic cell death and inflammation were also increased in MAZ51-treated animals compared with vehicle-treated animals following cisplatin administration. Notably, MAZ51 caused significant upregulation of intrarenal phospho-NF-κB, phospho-JNK, and IL-6. Cisplatin nephrotoxicity is associated with vascular congestion due to endothelial dysfunction. Using three-dimensional tissue cytometry, a novel approach to explore lymphatics in the kidney, we detected significant vascular autofluorescence attributed to erythrocytes in cisplatin alone-treated animals. Interestingly, no such congestion was detected in MAZ51-treated animals. We found increased renal vascular damage in MAZ51-treated animals, whereby MAZ51 caused a modest decrease in the endothelial markers endomucin and von Willebrand factor, with a modest increase in VEGFR2. Our findings identify a protective role for de novo LA in cisplatin nephrotoxicity and provide a rationale for the development of therapeutic approaches targeting LA. Our study also suggests off-target effects of MAZ51 on the vasculature in the setting of cisplatin nephrotoxicity.NEW & NOTEWORTHY Little is known about injury-associated LA in the kidney and its role in the pathophysiology of acute kidney injury (AKI). Observed exacerbation of cisplatin-induced AKI after LA inhibition was accompanied by increased medullary damage and cell death in the kidney. LA inhibition also upregulated compensatory expression of LA regulatory proteins, including JNK and NF-κB. These data support the premise that LA is induced during AKI and lymphatic expansion is a protective mechanism in cisplatin nephrotoxicity.

Mid-term clinical outcomes and complications of primary total knee arthroplasty in hemodialysis patients: a retrospective comparative cohort study

Background

Numerous patients who receive hemodialysis (HD) undergo total knee arthroplasty (TKA) due to advanced knee joint arthritis. However, there are few studies that describe the clinical outcomes and complications of TKA in HD patients. This study investigated the mid-term results of TKA in patients undergoing HD.

Methods

This single-center retrospective study compared clinical and surgical outcomes following TKA in patients who were receiving HD with those who were not. We used propensity scores to match 21 knees of 18 patients who received HD to 706 knees of 569 patients who had not received HD, from a total of 727 knees (587 patients) that underwent primary unilateral TKA. The clinical outcomes were evaluated using the American Knee Society Score-knee (AKSS-knee) and AKSS-function scores. The primary surgical outcome measure was the number of knees with postoperative complications.

Results

In both the HD and non-HD groups, postoperative AKSS-knee and function scores significantly improved when compared to preoperative values. Postoperative AKSS-knee and function scores were not significantly different between the groups. The number of knees with postoperative complications was larger in the HD group than the non-HD group within the first postoperative month, 0–12 months, 12–24 months, 0–24 months, and two years after surgery. Additionally, in the HD group, more complications occurred in the first month than any subsequent month in the two years after surgery.

Conclusions

TKA improves AKSS-knee and function scores equivalently for HD patients and non-HD patients. However, HD patients develop more complications after TKA, especially within the first month. Therefore, surgeons who perform TKA for HD patients should obtain informed consent after explaining the possible complications, and HD patients should be carefully observed following TKA.