Arterial calcification in chronic kidney disease: key roles for calcium and phosphate

Predictive nomogram model for severe coronary artery calcification in end-stage kidney disease patients

INTRODUCTION

The Agatston coronary artery calcification score (CACS) is an assessment index for coronary artery calcification (CAC). This study aims to explore the characteristics of CAC in end-stage kidney disease (ESKD) patients and establish a predictive model to assess the risk of severe CAC in patients.

METHODS

CACS of ESKD patients was assessed using an electrocardiogram-gated coronary computed tomography (CT) scan with the Agatston scoring method. A predictive nomogram model was established based on stepwise regression. An independent validation cohort comprised of patients with ESKD from multicentres.

RESULTS

369 ESKD patients were enrolled in the training set, and 127 patients were included in the validation set. In the training set, the patients were divided into three subgroups: no calcification (CACS = 0, n = 98), mild calcification (0 < CACS ≤ 400, n = 141) and severe calcification (CACS > 400, n = 130). Among the four coronary branches, the left anterior descending branch (LAD) accounted for the highest proportion of calcification. Stepwise regression analysis showed that age, dialysis vintage, β-receptor blocker, calcium-phosphorus product (Ca × P), and alkaline phosphatase (ALP) level were independent risk factors for severe CAC. A nomogram that predicts the risk of severe CAC in ESKD patients has been internally and externally validated, demonstrating high sensitivity and specificity.

CONCLUSION

CAC is both prevalent and severe in ESKD patients. In the four branches of the coronary arteries, LAD calcification is the most common. Our validated nomogram model, based on clinical risk factors, can help predict the risk of severe coronary calcification in ESKD patients who cannot undergo coronary CT analysis.

Current therapeutic approach of chronic kidney disease-mineral and bone disorder

Chronic kidney disease (CKD) has emerged as one of the leading noncommunicable diseases affecting >10% of the population worldwide. Bone and mineral disorders are a common complication among patients with CKD resulting in a poor life quality, high fracture risk, increased morbidity and cardiovascular mortality. According to Kidney Disease: Improving Global Outcomes, renal osteodystrophy refers to changes in bone morphology found in bone biopsy, whereas CKD-mineral and bone disorder (CKD-MBD) defines a complex of disturbances including biochemical and hormonal alterations, disorders of bone and mineral metabolism and extraskeletal calcification. As a result, the management of CKD-MBD should focus on the aforementioned parameters, including the treatment of hyperphosphatemia, hypocalcemia, abnormal PTH and vitamin D levels. Regarding the bone fragility fractures, osteoporosis and renal osteodystrophy, which constitute the bone component of CKD-MBD, anti-osteoporotic agents constitute the mainstay of treatment. However, a thorough elucidation of the CKD-MBD pathogenesis is crucial for the ideal personalized treatment approach. In this paper, we review the pathology and management of CKD-MBD based on the current literature with special attention to recent advances.

PALMD haploinsufficiency aggravates extracellular matrix remodeling in vascular smooth muscle cells and promotes calcification

Reduced PALMD expression is strongly associated with the development of calcified aortic valve stenosis; however, the role of PALMD in vascular calcification remains unknown. Calcified arteries were collected from mice to detect PALMD expression. Heterozygous Palmd knockout (Palmd+/-) mice were established to explore the role of PALMD in subtotal nephrectomy-induced vascular calcification. RNA sequencing was applied to detect molecular changes in aortas from Palmd+/- mice. Primary Palmd+/- vascular smooth muscle cells (VSMCs) or PALMD-silenced VSMCs by short interfering RNA were used to analyze PALMD function in phenotypic changes and calcification. PALMD haploinsufficiency aggravated subtotal nephrectomy-induced vascular calcification. RNA sequencing analysis showed that loss of PALMD disturbed the synthesis and degradation of the extracellular matrix (ECM) in aortas, including collagens and matrix metalloproteinases (Col6a6, Mmp2, Mmp9, etc.). In vitro experiments revealed that PALMD-deficient VSMCs were more susceptible to high phosphate-induced calcification. Downregulation of SMAD6 expression and increased levels of p-SMAD2 were detected in Palmd+/- VSMCs, suggesting that transforming growth factor-β signaling may be involved in PALMD haploinsufficiency-induced vascular calcification. Our data revealed that PALMD haploinsufficiency causes ECM dysregulation in VSMCs and aggravates vascular calcification. Our findings suggest that reduced PALMD expression is also linked to vascular calcification, and PALMD may be a potential therapeutic target for this disease. NEW & NOTEWORTHY We found that PALMD haploinsufficiency causes extracellular matrix dysregulation, reduced PALMD expression links to vascular calcification, and PALMD mutations may lead to the risk of both calcific aortic valve stenosis and vascular calcification.

Vascular smooth muscle cell phenotypic switching in atherosclerosis

Atherosclerosis (AS) is a complex pathology process involving intricate interactions among various cells and biological processes. Vascular smooth muscle cells (VSMCs) are the predominant cell type in normal arteries, and under atherosclerotic stimuli, VSMCs respond to altered blood flow and microenvironment changes by downregulating contractile markers and switching their phenotype. This review overviews the diverse phenotypes of VSMCs, including the canonical contractile VSMCs, synthetic VSMCs, and phenotypes resembling macrophages, foam cells, myofibroblasts, osteoblasts/chondrocytes, and mesenchymal stem cells. We summarize their presumed protective and pro-atherosclerotic roles in AS development. Additionally, we underscore the molecular mechanisms and regulatory pathways governing VSMC phenotypic switching, encompassing transcriptional regulation, biochemical factors, plaque microenvironment, epigenetics, miRNAs, and the cytoskeleton, emphasizing their significance in AS development. Finally, we outline probable future research directions targeting VSMCs, offering insights into potential therapeutic strategies for AS management.

In Vitro Models of Cardiovascular Calcification

Cardiovascular calcification, characterized by hydroxyapatite deposition in the arterial wall and heart valves, is associated with high cardiovascular morbidity and mortality. Cardiovascular calcification is a hallmark of aging but is frequently seen in association with chronic diseases, such as chronic kidney disease (CKD), diabetes, dyslipidemia, and hypertension in the younger population as well. Currently, there is no therapeutic approach to prevent or cure cardiovascular calcification. The pathophysiology of cardiovascular calcification is highly complex and involves osteogenic differentiation of various cell types of the cardiovascular system, such as vascular smooth muscle cells and valve interstitial cells. In vitro cellular and ex vivo tissue culture models are simple and useful tools in cardiovascular calcification research. These models contributed largely to the discoveries of the numerous calcification inducers, inhibitors, and molecular mechanisms. In this review, we provide an overview of the in vitro cell culture and the ex vivo tissue culture models applied in the research of cardiovascular calcification.

Key regulators of vascular calcification in chronic kidney disease: Hyperphosphatemia, BMP2, and RUNX2

Vascular calcification is quite common in patients with end-stage chronic kidney disease and is a major trigger for cardiovascular complications in these patients. These complications significantly impact the survival rate and long-term prognosis of individuals with chronic kidney disease. Numerous studies have demonstrated that the development of vascular calcification involves various pathophysiological mechanisms, with the osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs) being of utmost importance. High phosphate levels, bone morphogenetic protein 2 (BMP2), and runt-related transcription factor 2 (RUNX2) play crucial roles in the osteogenic transdifferentiation process of VSMCs. This article primarily reviews the molecular mechanisms by which high phosphate, BMP2, and RUNX2 regulate vascular calcification secondary to chronic kidney disease, and discusses the complex interactions among these factors and their impact on the progression of vascular calcification. The insights provided here aim to offer new perspectives for future research on the phenotypic switching and osteogenic transdifferentiation of VSMCs, as well as to aid in optimizing clinical treatment strategies for this condition, bearing significant clinical and scientific implications.

The Role of Mitochondrial Dysfunction in CKD-Related Vascular Calcification: From Mechanisms to Therapeutics

Vascular calcification (VC) is a common complication of chronic kidney disease (CKD) and is closely associated with cardiovascular events. The transdifferentiation of vascular smooth muscles (VSMCs) into an osteogenic phenotype is hypothesized to be the primary cause underlying VC. However, there is currently no effective clinical treatment for VC. Growing evidence suggests that mitochondrial dysfunction accelerates the osteogenic differentiation of VSMCs and VC via multiple mechanisms. Therefore, elucidating the relationship between the osteogenic differentiation of VSMCs and mitochondrial dysfunction may assist in improving VC-related adverse clinical outcomes in patients with CKD. This review aimed to summarize the role of mitochondrial biogenesis, mitochondrial dynamics, mitophagy, and metabolic reprogramming, as well as mitochondria-associated oxidative stress (OS) and senescence in VC in patients with CKD to offer valuable insights into the clinical treatment of VC.

Platelets in Vascular Calcification: A Comprehensive Review of Platelet-Derived Extracellular Vesicles, Protein Interactions, Platelet Function Indices, and their Impact on Cellular Crosstalk

Vascular calcification (VC) commonly accompanies the development of atherosclerosis, defined by the accumulation of calcium in the arterial wall, potentially leading to stroke and myocardial infarction. Severe and unevenly distributed calcification poses challenges for interventional procedures, elevating the risks of vascular dissection, acute vascular occlusion, restenosis, and other major adverse cardiovascular events. Platelets promote the development of atherosclerosis by secreting various inflammatory mediators, regulating cell migration, aggregation, adhesion, and initiating and expanding inflammatory responses. There is emerging evidence that platelets play a direct role in VC; however, this novel concept has not yet been critically assessed. This review describes the intricate mechanisms by which platelets promote VC, focusing on three key aspects and the potential opportunities for their therapeutic targeting: extracellular vesicles, platelet-regulatory proteins, and indices related to platelet function.

Intradialytic serum phosphate variations are associated with low PTH levels

BACKGROUND

Numerous studies have explored the role of kidney replacement therapy (KRT) in phosphorus (P) control among prevalent hemodialysis (HD) patients. However, whether the reduction of P achieved during KRT affects parathyroid hormone (PTH) levels is still a matter of debate.

METHODS

We conducted a retrospective observational study on the prevalent HD population at the Division of Nephrology, University Hospital of Verona, from January to December 2022. We Included clinically stable adult patients undergoing HD for over 6 months, with multiple recorded visits during the follow-up. Demographic, clinical, laboratory, and medication data were collected. Time-varying variables were updated at each study visit. The primary outcome of interest was PTH levels. The absolute intra-HD change in P (intra-HD ∆P), defined as the difference between pre- and post-HD P levels, served as the main exposure. Multivariable adjusted linear mixed models were used to investigate the relationship between intra-HD ∆P and PTH levels.

RESULTS

A total of 211 patients contributed to 904 study visits. A significant and positive relationship was observed between intra-HD ∆P and pre-HD P (β = 0.76, 95% CI 0.75, 0.78, p < 0.001) and urea reduction ratio (β = 0.38, 95% CI 0.35, 0.41; p < 0.001). An increase in intra-HD ∆P was significantly and independently associated with low PTH levels (β = - 0.16, 95% CI - 0.30, -0.03; p = 0.020).

CONCLUSIONS

The extent of intra-HD P reduction significantly correlates with low PTH levels. Strategies focused on optimizing or enhancing depurative efficiency in KRT can exert a substantial impact on managing positive phosphorus balance and secondary hyperparathyroidism. The assessment of intra-HD P reduction may play a pivotal role in the management and follow-up of secondary hyperparathyroidism in HD patients.

The mechanisms underlying acute myocardial infarction in chronic kidney disease patients undergoing hemodialysis

Cardiovascular disease (CVD) is a leading cause of death in chronic kidney disease (CKD). Hemodialysis is one of the main treatments for patients with end-stage kidney disease. Epidemiological data has shown that acute myocardial infarction (AMI) accounts for the main reason for death in patients with CKD under hemodialysis therapy. Immune dysfunction and changes in metabolism (including a high level of inflammatory cytokines, a disorder of lipid and mineral ion homeostasis, accumulation of uremic toxins et al.) during CKD can deteriorate stability of atherosclerotic plaque and promote vascular calcification, which are exactly the pathophysiological mechanisms underlying the occurrence of AMI. Meanwhile, the hemodialysis itself also has adverse effects on lipoprotein, the immune system and hemodynamics, which contribute to the high incidence of AMI in these patients. This review aims to summarize the mechanisms and further promising methods of prevention and treatment of AMI in CKD patients undergoing hemodialysis, which can provide an excellent paradigm for exploring the crosstalk between the kidney and cardiovascular system.

Dual-Drug Nanomedicine Assembly with Synergistic Anti-Aneurysmal Effects via Inflammation Suppression and Extracellular Matrix Stabilization

Abdominal aortic aneurysm (AAA) represents a critical cardiovascular condition characterized by localized dilation of the abdominal aorta, carrying a significant risk of rupture and mortality. Current treatment options are limited, necessitating novel therapeutic approaches. This study investigates the potential of a pioneering nanodrug delivery system, RAP@PFB, in mitigating AAA progression. RAP@PFB integrates pentagalloyl glucose (PGG) and rapamycin (RAP) within a metal-organic-framework (MOF) structure through a facile assembly process, ensuring remarkable drug loading capacity and colloidal stability. The synergistic effects of PGG, a polyphenolic antioxidant, and RAP, an mTOR inhibitor, collectively regulate key players in AAA pathogenesis, such as macrophages and smooth muscle cells (SMCs). In macrophages, RAP@PFB efficiently scavenges various free radicals, suppresses inflammation, and promotes M1-to-M2 phenotype repolarization. In SMCs, it inhibits apoptosis and calcification, thereby stabilizing the extracellular matrix and reducing the risk of AAA rupture. Administered intravenously, RAP@PFB exhibits effective accumulation at the AAA site, demonstrating robust efficacy in reducing AAA progression through multiple mechanisms. Moreover, RAP@PFB demonstrates favorable biosafety profiles, supporting its potential translation into clinical applications for AAA therapy.

Sevelamer-Induced Ischemic Enteritis

Sevelamer, a nonabsorbable dietary phosphate binder, is essential for patients with renal impairment since hyperphosphatemia is associated with an increase in all-cause mortality. Sevelamer is generally well tolerated; however, it is rarely been documented to cause gastrointestinal mucosal injury by forming sevelamer crystals and depositing within the gastrointestinal walls. We present a 35-year-old man with end-stage renal disease on peritoneal dialysis who developed abdominal pain and hematochezia. Initial imaging and endoscopic examination were concerning for ischemic enteritis, and histopathology revealed crystalloid structures surrounded by necrosis consistent with sevelamer-induced ischemic enteritis.

Zinc Action in Vascular Calcification

Although zinc's involvement in bone calcification is well-established, its role in vascular calcification, characterized by abnormal calcium and phosphorus deposition in soft tissues and a key aspect of various vascular diseases, including atherosclerosis, remains unclear. This review focuses on zinc's action in vascular smooth muscle cell (VSMC) calcification, including the vascular calcification mechanism. Accumulated research has indicated that zinc deficiency induces calcification in VSMCs and the aorta, primarily through apoptosis accompanied by a downregulation of smooth muscle cell markers. Moreover, zinc deficiency-induced vascular calcification operates independently of the action of alkaline phosphatase (ALP) activity, typically associated with osteogenic processes, but is partly regulated via inorganic phosphate transporter-1 (Pit-1). To date, research has shown that zinc regulates vascular calcification through a mechanism distinct from that of osteogenic calcification, providing insight into its dual effects on physiological and pathological calcification and thereby explaining the "zinc paradox," wherein zinc simultaneously increases osteoblastic calcification and decreases VSMC calcification.

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.

Coronary artery calcification: concepts and clinical applications

Vascular calcification is an important hallmark of atherosclerosis. Coronary artery calcification (CAC) implies the presence of coronary artery disease (CAD), irrespective of risk factors or symptoms, is concomitant with the development of advanced atherosclerosis. Coronary thrombosis is the most common clinical end event leading to acute coronary syndrome (ACS). The least common type of pathology associated with thrombosis is the calcified nodule (CN). It usually occurs in elderly patients with severely calcified and tortuous arteries. The prevalence of calcified nodules in patients with ACS may be underestimated due to the lack of easily recognisable diagnostic methods. In this review, the authors will focus on the classification, clinical significance, pathogenesis, and diagnostic evaluation and treatment of CAC to further explore the clinical significance of CN.

Serial longitudinal changes of coronary calcified plaques with clear outer borders under intensive lipid management: insights from optical coherence tomography

Percutaneous coronary intervention (PCI) for calcified lesions is one of the most challenging procedures related to worse clinical outcomes. To stabilize vulnerable plaques, intensive lipid management is recommended; however, the serial changes of calcified plaques under intensive lipid management are unknown. A total of 31 patients (mean age, 63 ± 10 years; men, 29 patients) who underwent PCI with intensive lipid management were retrospectively studied. We evaluated the serial longitudinal changes of calcified plaques with clear outer borders using optical coherence tomography (OCT) at two time points: at the time of PCI (baseline) and the chronic phase. The median interval from PCI to chronic phase was 287 (233-429) days. Twenty-eight patients (90.3%) had increased calcium volume at the chronic phase compared with those at baseline (2.6 [1.3-5.1] vs. 1.8 [0.7-4.3] mm2, p < 0.05), and the median increase rate of calcium volume was 27.4% at the chronic phase. According to the median increase rate of calcium volume (27.4%), patients were divided into the following two groups: rapid progression (≥ 27.4%, RP group) and non-rapid progression (< 27.4%, non-RP group). The RP group had more patients with diabetes, and diabetes was independently associated with rapid progression by multivariate analysis. Furthermore, patients with diabetes had significantly higher changes in calcium index and volume from the baseline to the chronic phase than those without diabetes. Coronary calcification progression during relatively short intervals was observed using OCT even under intensive lipid management. Diabetes was an independent predictor for rapid coronary calcification progression.

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.

Contribution of the ELRs to the development of advanced in vitro models

Developing in vitro models that accurately mimic the microenvironment of biological structures or processes holds substantial promise for gaining insights into specific biological functions. In the field of tissue engineering and regenerative medicine, in vitro models able to capture the precise structural, topographical, and functional complexity of living tissues, prove to be valuable tools for comprehending disease mechanisms, assessing drug responses, and serving as alternatives or complements to animal testing. The choice of the right biomaterial and fabrication technique for the development of these in vitro models plays an important role in their functionality. In this sense, elastin-like recombinamers (ELRs) have emerged as an important tool for the fabrication of in vitro models overcoming the challenges encountered in natural and synthetic materials due to their intrinsic properties, such as phase transition behavior, tunable biological properties, viscoelasticity, and easy processability. In this review article, we will delve into the use of ELRs for molecular models of intrinsically disordered proteins (IDPs), as well as for the development of in vitro 3D models for regenerative medicine. The easy processability of the ELRs and their rational design has allowed their use for the development of spheroids and organoids, or bioinks for 3D bioprinting. Thus, incorporating ELRs into the toolkit of biomaterials used for the fabrication of in vitro models, represents a transformative step forward in improving the accuracy, efficiency, and functionality of these models, and opening up a wide range of possibilities in combination with advanced biofabrication techniques that remains to be explored.

Histone deacetylase 6 suppression of renal tubular epithelial cell promotes interstitial mineral deposition via alpha-tubulin acetylation

Randall's plaque (RP) is derived from interstitial mineral deposition and is highly prevalent in renal calcium oxalate (CaOx) stone disease, which is predictive of recurrence. This study shows that histone deacetylase 6 (HDAC6) levels are suppressed in renal tubular epithelial cells in RP samples, in kidney tissues of hyperoxaluria rats, and in hyper-oxalate-treated or mineralized cultured renal tubular epithelial (MDCK) cells in vitro. Mineral deposition in MDCK cells was exacerbated by HDAC6 inhibition but alleviated by HDAC6 overexpression. Surprisingly, the expression of some osteogenic-associated proteins, were not increased along with the increasing of mineral deposition, and result of single-cell RNA sequencing of renal papillae samples revealed that epithelial cells possess lower calcific activity, suggesting that osteogenic-transdifferentiation may not have actually occurred in tubular epithelial cells despite mineral deposition. The initial mineral depositions facilitated by HDAC6 inhibitor were localized in extracellular dome rather than inside the cells, moreover, suppression of HDAC6 significantly increased the calcium content of co-cultured renal interstitial fibroblasts (NRK49F) and enhanced mineral deposition of indirectly co-cultured NRK49F cells, suggesting that HDAC6 may influence trans-MDCK monolayer secretion of mineral. Further experiments revealed that this regulatory role was partially alpha-tubulinLys40 acetylation dependent. Collectively, these results suggest that hyper-oxalate exposure led to HDAC6 suppression in renal tubular epithelial cells, which may contribute to interstitial mineral deposition by promoting alpha-tubulinLys40 acetylation. Therapeutic agents that influence HDAC6 activity may be beneficial in preventing RP and CaOx stone formation.

Empagliflozin ameliorates vascular calcification in diabetic mice through inhibiting Bhlhe40-dependent NLRP3 inflammasome activation

Type 2 diabetes mellitus (T2DM) patients exhibit greater susceptibility to vascular calcification (VC), which has a higher risk of death and disability. However, there is no specific drug for VC therapy. NLRP3 inflammasome activation as a hallmark event of medial calcification leads to arterial stiffness, causing vasoconstrictive dysfunction in T2DM. Empagliflozin (EMPA), a sodium-glucose co-transporter 2 inhibitor (SGLT2i), restrains hyperglycemia with definite cardiovascular benefits. Given the anti-inflammatory activity of EMPA, herein we investigated whether EMPA protected against VC in the aorta of T2DM mice by inhibiting NLRP3 inflammasome activation. Since db/db mice receiving a normal diet developed VC at the age of about 20 weeks, we administered EMPA (5, 10, 20 mg·kg-1·d-1, i.g) to 8 week-old db/db mice for 12 weeks. We showed that EMPA intervention dose-dependently ameliorated the calcium deposition, accompanied by reduced expression of RUNX2 and BMP2 proteins in the aortas. We found that EMPA (10 mg·kg-1·d-1 for 6 weeks) also protected against VC in vitamin D3-overloaded mice, suggesting the protective effects independent of metabolism. We showed that EMPA (10 mg·kg-1·d-1) inhibited the abnormal activation of NLRP3 inflammasome in aortic smooth muscle layer of db/db mice. Knockout (KO) of NLRP3 significantly alleviated VC in STZ-induced diabetic mice. The protective effects of EMPA were verified in high glucose (HG)-treated mouse aortic smooth muscle cells (MOVASs). In HG-treated NLRP3 KO MOVASs, EMPA (1 μM) did not cause further improvement. Bioinformatics and Western blot analysis revealed that EMPA significantly increased the expression levels of basic helix-loop-helix family transcription factor e40 (Bhlhe40) in HG-treated MOVASs, which served as a negative transcription factor directly binding to the promotor of Nlrp3. We conclude that EMPA ameliorates VC by inhibiting Bhlhe40-dpendent NLRP3 inflammasome activation. These results might provide potential significance for EMPA in VC therapy of T2DM patients.

Phenotypic switching of vascular smooth muscle cells in atherosclerosis, hypertension, and aortic dissection

Vascular smooth muscle cells (VSMCs) play a critical role in regulating vasotone, and their phenotypic plasticity is a key contributor to the pathogenesis of various vascular diseases. Two main VSMC phenotypes have been well described: contractile and synthetic. Contractile VSMCs are typically found in the tunica media of the vessel wall, and are responsible for regulating vascular tone and diameter. Synthetic VSMCs, on the other hand, are typically found in the tunica intima and adventitia, and are involved in vascular repair and remodeling. Switching between contractile and synthetic phenotypes occurs in response to various insults and stimuli, such as injury or inflammation, and this allows VSMCs to adapt to changing environmental cues and regulate vascular tone, growth, and repair. Furthermore, VSMCs can also switch to osteoblast-like and chondrocyte-like cell phenotypes, which may contribute to vascular calcification and other pathological processes like the formation of atherosclerotic plaques. This provides discusses the mechanisms that regulate VSMC phenotypic switching and its role in the development of vascular diseases. A better understanding of these processes is essential for the development of effective diagnostic and therapeutic strategies.

Hypoxia-Inducible Factor-1α Regulates High Phosphate-Induced Vascular Calcification via Type III Sodium-Dependent Phosphate Cotransporter 1

Vascular calcification (VC) has a high incidence in patients with chronic kidney disease, which is a worldwide public health problem and presents a heavy burden to society. Hypoxia-inducible factor (HIF)-1α, the active subunit of HIF-1, has been reported to play a vital role in high phosphate-induced VC. However, the underlying mechanism is still undetermined, and effective treatment is unavailable. In the present study, human aortic smooth muscle cells (HASMCs) were cultured under normal or high phosphate media conditions. HIF-1α small interfering RNA and overexpression plasmids were employed to regulate HIF-1α expression. Phosphonoformic acid was employed to restrain the function of type III sodium-dependent phosphate cotransporter 1 (Pit-1). The expression levels of HIF-1α, Pit-1, runt-related transcription factor 2 (Runx2), and smooth muscle 22 alpha (SM22α) were evaluated, and the calcium contents were also examined. Cell growth was assessed using an MTT assay. High phosphate stimulation caused an upregulation in HIF-1α and Pit-1 expression levels and induced calcium depositions in HASMCs. Upregulation of Runx2 expression accompanied by downregulation of SM22α expression was observed in the high phosphate group. Following the suppression of HIF-1α expression, there was a concomitant attenuation in Pit-1 expression, calcium deposition, the alteration of phenotypic transition marker genes, and vice versa. The most serious calcium deposition was noted in HASMCs cultured under high phosphate conditions which were pretreated with a HIF-1α overexpression plasmid. However, when the biological functions of Pit-1 were restrained, the putative serious calcium deposition was not formed even in HASMCs transfected with a HIF-1α overexpression plasmid. The findings confirmed that HIF-1α regulated Pit-1 expression and exerted its pro-calcifying effect through Pit-1, which identified HIF-1α and Pit-1 as therapeutic targets for high phosphate-induced VC.

Effects of cerium oxide nanoparticles on adenine-induced chronic kidney disease model rats

AIM

Cerium oxide, particularly in nanoparticle form (nanoceria), has been investigated for biomedical applications as a promising new agent for treating several pathologies. The aim of the present study was to characterize the pharmacologic effects of nanoceria in an animal model of chronic kidney disease.

METHODS

We created the chronic kidney disease animal model by feeding rats a 0.25% adenine diet. Male Wistar rats were divided into five groups: normal diet, 0.25% adenine diet, or adenine diet containing three different doses or durations of nanoceria treatment. Blood was collected weekly from the tail veins of each rat and analyzed for renal function markers. After 5 weeks, various biochemical markers in serum, plasma, and urine were also analyzed.

RESULTS

In the adenine-treated group, body weight was significantly decreased, and the kidneys lost much of their healthy reddish color and became lumpy and white in appearance. In addition, levels of serum creatinine, blood urea nitrogen, and plasma uremic toxins were significantly increased in adenine-treated rats compared with controls. Renal functional and structural damage in adenine diet model rats tended to be ameliorated by nanoceria ingestion. The high-dose cerium-treated group maintained reddish areas in the kidneys, and the increases in biomarker levels of creatinine, blood urea nitrogen, and inorganic phosphorus were markedly reduced, regardless of treatment duration.

CONCLUSIONS

Ingestion of nanoceria may be effective for improving or preventing renal damage caused by adenine. Geriatr Gerontol Int 2024; 24: 88-95.

Overexpression of miR-204-5p Alleviates Osteogenic Differentiation and Calcification of Human Aortic Vascular Smooth Muscle Cells by Targeting Calcium/Calmodulin-dependent Protein Kinase 1

ABSTRACT

Vascular calcification (VC), a major complication in chronic kidney disease (CKD), is predominantly driven by osteoblastic differentiation. Recent studies have highlighted the crucial role of microRNAs in CKD's pathogenesis. Here, our research focused on the effects of miR-204-5p and its molecular mechanisms within VC. We initially found a notable decrease in miR-204-5p levels in human aortic vascular smooth muscle cells stimulated with inorganic phosphate, using this as a VC model in vitro. Following the overexpression of miR-204-5p, a decrease in VC was observed, as indicated by alizarin red S staining and measurements of calcium content. This decrease was accompanied by lower levels of the osteogenic marker, runt-related transcription factor 2, and higher levels of α-smooth muscle actin, a marker of contractility. Further investigation showed that calcium/calmodulin-dependent protein kinase 1 (CAMK1), which is a predicted target of miR-204-5p, promotes VC. Conversely, overexpressing miR-204-5p reduced VC by suppressing CAMK1 activity. Overexpressing miR-204-5p also effectively mitigated aortic calcification in an in vivo rat model. In summary, our research indicated that targeting the miR-204-5p/CAMK1 pathway could be a viable strategy for mitigating VC in CKD patients.

Calcitriol combined with high-calcium and high-phosphorus diet induces vascular calcification model in chronic kidney disease rats

BACKGROUND

Cardiovascular diseases represent a significant complication arising from chronic kidney disease (CKD). Vascular calcification is an important risk factor for cardiovascular diseases. Reducing vascular calcification is therefore critical to reducing mortality in CKD patients.

HYPOTHESIS

This study aims to establish a vascular calcification model in rats with CKD by administering subcutaneous injections of calcitriol in combination with a high-calcium and high-phosphorus diet.

METHODS

The rats were divided into the CKD vascular calcification model group (subtotal nephrectomy+ [SNx+]) and the sham-operated control group (subtotal nephrectomy- [SNx-]). The rats in the SNx(+) group were administered high-calcium and high-phosphorus feeds following a 5/6 nephrectomy. Calcitriol (1 μg/kg, three times a week) was injected subcutaneously at weeks 0, 4, 8, and 12 after the operation. Measurements of body weight, urine, serum biochemical indicators and vascular calcification level were conducted in rats.

RESULTS

(1) Compared with the SNx(-) group, rats in the SNx(+) group experienced an increase in 24-h urine output, urinary phosphorus, and urinary microprotein excretion, along with the development of severe anemia. Additionally, there was a notable elevation in serum phosphorus, blood urea nitrogen, blood creatinine, fibroblast growth factor 23 (FGF-23), and intact parathyroid hormone levels, accompanied by severe hypoproteinemia at week 12. (2) The results of micro-compuyed tomography (μCT) and alizarin S staining of the thoracic aorta demonstrated an increase in vascular calcification in the SNx(+) group. (3) The expression levels of vascular calcification-related proteins were increased.

CONCLUSIONS

The administration of calcitriol combined with a high-calcium and high-phosphorus diet was found to induce vascular calcification in CKD rats, leading to a disturbance in mineral metabolism. Vascular calcification was effectively induced in CKD rats after 12 weeks of modeling, thereby presenting a novel approach for establishing a vascular calcification model in CKD rats, helping to elucidate this clinical condition and its underlying molecular mechanisms.

HDAC2 counteracts vascular calcification by activating autophagy in chronic kidney disease

Vascular calcification is a major risk factor for cardiovascular disease mortality, with a significant prevalence in chronic kidney disease (CKD). Pharmacological inhibition of histone acetyltransferase has been proven to protect against from vascular calcification. However, the role of Histone Deacetylase 2 (HDAC2) and molecular mechanisms in vascular calcification of CKD remains unknown. An in vivo model of CKD was established using mouse fed with a high adenine and phosphate diet, and an in vitro model was produced using human aortic vascular smooth muscle cells (VSMCs) stimulated with β-glycerophosphate (β-GP). HDAC2 expression was found to be reduced in medial artery of CKD mice and β-GP-induced VSMCs. Overexpression of HDAC2 attenuated OPN and OCN upregulation, α-SMA and SM22α downregulation, and calcium deposition in aortas of CKD. The in vitro results also demonstrated that β-GP-induced osteogenic differentiation was inhibited by HDAC2. Furthermore, we found that HDAC2 overexpression caused an increase in LC3II/I, a decrease in p62, and an induction of autophagic flux. Inhibition of autophagy using its specific inhibitor 3-MA blocked HDAC2's protective effect on osteogenic differentiation in β-GP-treated VSMCs. Taken together, these results suggest that HDAC2 may protect against vascular calcification by the activation of autophagy, laying out a novel insight for the molecular mechanism in vascular calcification of CKD.

The association of peritoneal dialysis and hemodialysis on mitral and aortic valve calcification associated mortality: a meta-analysis

Cardiac valve calcification (CVC), characterized by the accumulation of calcium in the heart valves, is highly prevalent among patients undergoing dialysis. This meta-analysis aimed to provide an updated summary of recent studies on the prognostic value of CVC in patients undergoing dialysis. We conducted a search of PubMed, Embase, and Web of Science to identify observational studies investigating cardiovascular or all-cause mortality associated with CVC in dialysis patients until March 2023. Hazard ratios (HRs) and the corresponding 95% confidence intervals (CIs) were calculated for the meta-analysis, and the strength and significance of the associations between CVC and mortality outcomes in dialysis patients were assessed. From 6218 initially identified studies, we included 10 critical studies with a total of 3376 dialysis patients in a further meta-analysis. Pooled analyses demonstrated a significant association between CVC and an elevated risk of all-cause and cardiovascular mortality in dialysis patients. In our study, we discovered HRs of 1.592 (95% CI 1.410-1.797) for all-cause mortality and 2.444 (95% CI 1.632-3.659) for cardiovascular mortality. Furthermore, subgroup analysis revealed elevated all-cause mortality among patients with mitral valve calcification (HR 1.572; 95% CI 1.200-2.060) compared to those with aortic valve calcification (HR 1.456; 95% CI 1.105-1.917). Similarly, patients undergoing peritoneal dialysis faced a greater risk for all-cause mortality (HR 2.094; 95% CI 1.374-3.191) than those on hemodialysis (HR 1.553; 95% CI 1.369-1.763). This highlights the possibility of CVC being an independent risk factor for dialysis patients, particularly in relation to mitral valve calcification or peritoneal dialysis.

Vascular Calcification: A Passive Process That Requires Active Inhibition

The primary cause of worldwide mortality and morbidity stems from complications in the cardiovascular system resulting from accelerated atherosclerosis and arterial stiffening. Frequently, both pathologies are associated with the pathological calcification of cardiovascular structures, present in areas such as cardiac valves or blood vessels (vascular calcification). The accumulation of hydroxyapatite, the predominant form of calcium phosphate crystals, is a distinctive feature of vascular calcification. This phenomenon is commonly observed as a result of aging and is also linked to various diseases such as diabetes, chronic kidney disease, and several genetic disorders. A substantial body of evidence indicates that vascular calcification involves two primary processes: a passive process and an active process. The physicochemical process of hydroxyapatite formation and deposition (a passive process) is influenced significantly by hyperphosphatemia. However, the active synthesis of calcification inhibitors, including proteins and low-molecular-weight inhibitors such as pyrophosphate, is crucial. Excessive calcification occurs when there is a loss of function in enzymes and transporters responsible for extracellular pyrophosphate metabolism. Current in vivo treatments to prevent calcification involve addressing hyperphosphatemia with phosphate binders and implementing strategies to enhance the availability of pyrophosphate.

Association between dietary selenium intake and severe abdominal aortic calcification in the United States: a cross-sectional study

Abdominal aortic calcification (AAC) is an important predictor of cardiovascular disease. The purpose of the current study was to detect the association between dietary selenium intake and severe AAC. We included 2651 participants from the National Health and Nutrition Examination Survey (NHANES, 2013-2014). Dietary selenium intake was measured using the 24-hour recall method. AAC was quantified using the Kauppila score system based on dual-energy X-ray absorptiometry, with a score of >6 indicating severe AAC. The association between dietary selenium intake and severe AAC was analyzed by using a weighted multivariate logistic regression model, smooth curve fitting, and stratified subgroup analysis. After adjusting for multiple covariates, we found that higher dietary selenium intake was negatively associated with severe AAC incidence. When selenium intake was converted into tertiles, the highest tertile of dietary selenium intake was significantly associated with the incidence of severe AAC (odds ratio = 0.66). Smooth curve fitting revealed that this relationship was nonlinear. Subgroup analysis revealed that this negative association was present in participants with chronic kidney disease, but was absent when participants had hypertension or diabetes mellitus. Higher dietary selenium intake was negatively associated with severe AAC incidence in a nonlinear pattern, except in participants with diabetes mellitus or hypertension. However, further cohort studies are required to validate these findings.

Top Five Stories of the Cellular Landscape and Therapies of Atherosclerosis: Current Knowledge and Future Perspectives

Atherosclerosis (AS) is characterized by impairment and apoptosis of endothelial cells, continuous systemic and focal inflammation and dysfunction of vascular smooth muscle cells, which is documented as the traditional cellular paradigm. However, the mechanisms appear much more complicated than we thought since a bulk of studies on efferocytosis, transdifferentiation and novel cell death forms such as ferroptosis, pyroptosis, and extracellular trap were reported. Discovery of novel pathological cellular landscapes provides a large number of therapeutic targets. On the other side, the unsatisfactory therapeutic effects of current treatment with lipid-lowering drugs as the cornerstone also restricts the efforts to reduce global AS burden. Stem cell- or nanoparticle-based strategies spurred a lot of attention due to the attractive therapeutic effects and minimized adverse effects. Given the complexity of pathological changes of AS, attempts to develop an almighty medicine based on single mechanisms could be theoretically challenging. In this review, the top stories in the cellular landscapes during the initiation and progression of AS and the therapies were summarized in an integrated perspective to facilitate efforts to develop a multi-targets strategy and fill the gap between mechanism research and clinical translation. The future challenges and improvements were also discussed.

Re-analysis of single-cell transcriptomics reveals a critical role of macrophage-like smooth muscle cells in advanced atherosclerotic plaque

Aims: Smooth muscle cell (SMC) remodeling poses a critical feature in the development and progression of atherosclerosis. Although fate mapping and in silicon approaches have expanded SMC phenotypes in atherosclerosis, it still remains elusive about the contributions of individual SMC phenotypes and molecular dynamics to advanced atherosclerotic plaque. Methods: Using single-cell transcriptome, we investigated cellular compositions of human carotid plaque laden with atherosclerotic core, followed by in vivo experiments utilizing SMC-lineage tracing technology, bulk RNA sequencing (RNA-seq) and both in vivo and in vitro validation of the underlying molecular mechanism. Results: 5 functionally distinct SMC subtypes were uncovered based on transcriptional features (described as contractile, fibroblast-like, osteogenic, synthetic and macrophage-like) within the niche. A proinflammatory, macrophage-like SMC subtype displaying an intermediary phenotype between SMC and macrophage, exhibits prominent potential in destabilizing plaque. At the molecular level, we explored cluster-specific master regulons by algorithm, and identified interferon regulatory factor-8 (IRF8) as a potential stimulator of SMC-to-macrophage transdifferentiation via activating nuclear factor-κB (NF-κB) signaling. Conclusions: Our study illustrates a comprehensive cell atlas and molecular landscape of advanced atherosclerotic lesion, which might renovate current understanding of SMC biology in atherosclerosis.

Multiplexed MRM-based proteomics for identification of circulating proteins as biomarkers of cardiovascular damage progression associated with diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) increases the risk of coronary heart disease (CHD) by 2-4 fold, and is associated with endothelial dysfunction, dyslipidaemia, insulin resistance, and chronic hyperglycaemia. The aim of this investigation was to assess, by a multimarker mass spectrometry approach, the predictive role of circulating proteins as biomarkers of cardiovascular damage progression associated with diabetes mellitus.

METHODS

The study considered 34 patients with both T2DM and CHD, 31 patients with T2DM and without CHD, and 30 patients without diabetes with a diagnosis of CHD. Plasma samples of subjects were analysed through a multiplexed targeted liquid chromatography mass spectrometry (LC-MS)-based assay, namely Multiple Reaction Monitoring (MRM), allowing the simultaneous detection of peptides derived from a protein of interest. Gene Ontology (GO) Analysis was employed to identify enriched GO terms in the biological process, molecular function, or cellular component categories. Non-parametric multivariate methods were used to classify samples from patients and evaluate the relevance of the analysed proteins' panel.

RESULTS

A total of 81 proteins were successfully quantified in the human plasma samples. Gene Ontology analysis assessed terms related to blood microparticles, extracellular exosomes and collagen-containing extracellular matrix. Preliminary evaluation using analysis of variance (ANOVA) of the differences in the proteomic profile among patient groups identified 13 out of the 81 proteins as significantly different. Multivariate analysis, including cluster analysis and principal component analysis, identified relevant grouping of the 13 proteins. The first main cluster comprises apolipoprotein C-III, apolipoprotein C-II, apolipoprotein A-IV, retinol-binding protein 4, lysozyme C and cystatin-C; the second one includes, albeit with sub-grouping, alpha 2 macroglobulin, afamin, kininogen 1, vitronectin, vitamin K-dependent protein S, complement factor B and mannan-binding lectin serine protease 2. Receiver operating characteristic (ROC) curves obtained with the 13 selected proteins using a nominal logistic regression indicated a significant overall distinction (p < 0.001) among the three groups of subjects, with area under the ROC curve (AUC) ranging 0.91-0.97, and sensitivity and specificity ranging from 85 to 100%.

CONCLUSIONS

Targeted mass spectrometry approach indicated 13 multiple circulating proteins as possible biomarkers of cardiovascular damage progression associated with T2DM, with excellent classification results in terms of sensitivity and specificity.

Zinc Deficiency Promotes Calcification in Vascular Smooth Muscle Cells Independent of Alkaline Phosphatase Action and Partly Impacted by Pit1 Upregulation

Inorganic phosphate (Pi) is a critical determinant of calcification, and its concentration is regulated by alkaline phosphatase (ALP) and Pit1. ALP is a key regulator of osteogenic calcification and acts by modulating local inorganic phosphate (Pi) concentrations through hydrolyzing pyrophosphate in the extracellular matrix (ECM). Pit1, a sodium-dependent phosphate transporter, regulates calcification via facilitating phosphate uptake within the cells. To investigate whether zinc differentially regulates osteoblastic and vascular calcifications, we examined ALP activity and Pit1 in osteoblastic and vascular smooth muscle cells (VSMCs). Our findings demonstrate that calcification in osteoblastic MC3T3-E1 cells is decreased via diminished ALP action under zinc deficiency. In contrast, zinc-deficiency-induced calcification in VSMCs is independent of ALP action, as demonstrated by very weak ALP activity and expression in calcified VSMCs. In zinc-deficient A7r5 VSMC, P accumulation increased with increasing Na phosphate concentration (3-7 mM) but not with β-GP treatment, which requires ALP activity to generate Pi. Ca deposition also increased with Na phosphate in a dose-dependent manner; in contrast, β-GP did not affect Ca deposition. In osteoblastic cells, Pit1 expression was not affected by zinc treatments. In contrast, Pit1 expression is highly upregulated in A7r5 VSMC under zinc deficiency. Using phosphonoformic acid, a competitive inhibitor of Pit1, we showed that calcification is inhibited in both A7r5 and MC3T3-E1 cells, indicating a requirement for Pit1 in both calcifications. Moreover, the downregulation of VSMC markers under zinc deficiency was restored by blocking Pit1. Taken together, our results imply that zinc-deficiency-induced calcification in VSMC is independent of ALP action in contrast to osteoblastic calcification. Moreover, Pit1 expression in VSMCs is a target for zinc deficiency and may mediate the inhibition of VSMC marker expression under zinc deficiency.

Systematic assessment of the antifungal mechanism of soil fumigant methyl isothiocyanate against Fusarium oxysporum

Fusarium oxysporum is an important phytopathogenic fungus, it can be controlled by the soil fumigant methyl isothiocyanate (MITC). However, the antimicrobial mechanism of MITC against F. oxysporum, especially at the transcriptional level, is still unclear. In this experiment, the antimicrobial mechanism of MITC against F. oxysporum was investigated. Our results indicated that when F. oxysporum was exposed to 6 mg/L MITC for 12 h, the inhibitory rate of MITC on F. oxysporum was 80%. Transmission electron microscopes showed that the cell wall and membrane of F. oxysporum had shrunk and folded, vacuoles increased, and mitochondria swelled and deformed. In addition, the enzyme activity of F. oxysporum treated with MITC showed a decrease of 32.50%, 8.28% and 74.04% in catalase, peroxidase and superoxide dismutase, respectively. Transcriptome sequencing of F. oxysporum was performed and the results showed that 1478 differentially expressed genes (DEGs) were produced in response to MITC exposure. GO and KEGG analysis showed that the DEGs identified were involved in substance and energy metabolism, signal transduction, transport and catalysis. MITC disrupted cell homeostasis by influencing the expression of some key genes involved in chitin synthase and detoxification enzymes production, but F. oxysporum also protected itself by up-regulating genes involved in energy synthesis (such as upregulating acnA, CS and LSC2 in TCA). qRT-PCR data validated the reliability of transcriptome data. Our research used biochemical and genetic techniques to identify molecular lesions in the mycelia of F. oxysporum exposed to MITC, and provide valuable insights into the toxic mechanism of pathogenic fungi mediated by MITC. These techniques are also likely to be useful for rapidly screening and identifying new, environmentally-friendly soil fumigants that are efficacious against fungal pathogens.

Association Between Serum Uric Acid and Abdominal Aortic Calcification in Adults Aged 40 to 80 years: A Retrospective Cross-Sectional Study

There are numerous causes of abdominal aortic calcification (AAC), among which the relationship between serum uric acid and AAC still needs to be investigated further. The aim of this research was to ascertain whether serum uric acid is correlated with AAC. Our study included 3007 participants. We described the study population characteristics and utilized univariate analysis, stratified analysis, multiple equation regression analysis, smoothed curve fitting, and threshold effects analysis. AAC Total 24 score is used to reflect the range of aortic calcification at each vertebral level. As serum uric acid increased, the AAC Total 24 score first decreased and then increased. The fold point is located when serum uric is at 3.5 mg/dL. After adjusting for 16 covariates, the beta values for the groups with moderate and high serum uric acid levels were 0.34 and 0.53, respectively, compared with the low serum uric acid tertile group (P < .05). Our research indicates a negative correlation between serum acid level and AAC when serum uric acid <3.5 mg/dl, but it is positively correlated with the formation of AAC when serum uric acid >3.5 mg/dl.

PRMT3 methylates HIF-1α to enhance the vascular calcification induced by chronic kidney disease

BACKGROUND

Medial vascular calcification is commonly identified in chronic kidney disease (CKD) patients and seriously affects the health and life quality of patients. This study aimed to investigate the effects of protein arginine methyltransferase 3 (PRMT3) on vascular calcification induced by CKD.

METHODS

A mice model of CKD was established with a two-step diet containing high levels of calcium and phosphorus. Vascular smooth muscle cells (VSMCs) were subjected to β-glycerophosphate (β-GP) treatment to induce the osteogenic differentiation as an in vitro CKD model.

RESULTS

PRMT3 was upregulated in VSMCs of medial artery of CKD mice and β-GP-induced VSMCs. The inhibitor of PRMT3 (SGC707) alleviated the vascular calcification and inhibited the glycolysis of CKD mice. Knockdown of PRMT3 alleviated the β-GP-induced osteogenic transfomation of VSMCs by the repression of glycolysis. Next, PRMT3 interacted with hypoxia-induced factor 1α (HIF-1α), and the knockdown of PRMT3 downregulated the protein expression of HIF-1α by weakening its methylation. Gain of HIF-1α reversed the PRMT3 depletion-induced suppression of osteogenic differentiation and glycolysis of VSMCs.

CONCLUSION

The inhibitory role of PRMT3 depletion was at least mediated by the regulation of glycolysis upon repressing the methylation of HIF-1α.

Establishment and evaluation of a nomogram prediction model for the risk of vascular calcification in stage 5 chronic kidney disease patients

Vascular calcification (VC) is a common complication of chronic kidney disease (CKD) that has a detrimental effect on patients' survival and prognosis. The aim of this study was to develop and validate a practical and reliable prediction model for VC in CKD5 patients. The medical records of 544 CKD5 patients were reviewed retrospectively. Multivariate logistic regression analysis was used to identify the independent risk factors for vascular calcification in patients with CKD5 and then created a nomogram prediction model. The area under the receiver operating characteristic curve (AUC), Hosmer-Lemeshow test, and decision curve analysis (DCA) were used to assess model performance. The patients were split into groups with normal and high serum uric acid levels, and the factors influencing these levels were investigated. Age, BUN, SUA, P and TG were independent risk factors for vascular calcification in CKD5 patients in the modeling group (P < 0.05). In the internal validation, the results of model showed that the AUC was 0.917. No significant divergence between the predicted probability of the nomogram and the actual incidence rate (x2 = 5.406, P = 0.753) was revealed by the calibration plot and HL test, thus confirming that the calibration was satisfactory. The external validation also showed good discrimination (AUC = 0.973). The calibration chart and HL test also demonstrated good consistency. Besides, the correlation analysis of serum uric acid levels in all CKD5 patients revealed that elevated uric acid levels may be related to gender, BUN, P, and TG.

SGK3 promotes vascular calcification via Pit-1 in chronic kidney disease

Rationale: Vascular calcification (VC) is a life-threatening complication in patients with chronic kidney disease (CKD) caused mainly by hyperphosphatemia. However, the regulation of VC remains unclear despite extensive research. Although serum- and glucocorticoid-induced kinase 3 (SGK3) regulate the sodium-dependent phosphate cotransporters in the intestine and kidney, its effect on VC in CKD remains unknown. Additionally, type III sodium-dependent phosphate cotransporter-1 (Pit-1) plays a significant role in VC development induced by high phosphate in vascular smooth muscle cells (VSMCs). However, it remains unclear whether SGK3 regulates Pit-1 and how exactly SGK3 promotes VC in CKD via Pit-1 at the molecular level. Thus, we investigated the role of SGK3 in the certified outflow vein of arteriovenous fistulas (AVF) and aortas of uremic mice. Methods and Results: In our study, using uremic mice, we observed a significant upregulation of SGK3 and calcium deposition in certified outflow veins of the AVF and aortas, and the increase expression of SGK3 was positively correlated with calcium deposition in uremic aortas. In vitro, the downregulation of SGK3 reversed VSMCs calcification and phenotype switching induced by high phosphate. Mechanistically, SGK3 activation enhanced the mRNA transcription of Pit-1 through NF-κB, downregulated the ubiquitin-proteasome mediated degradation of Pit-1 via inhibiting the activity of neural precursor cells expressing developmentally downregulated protein 4 subtype 2 (Nedd4-2), an E3 ubiquitin ligase. Moreover, under high phosphate stimulation, the enhanced phosphate uptake induced by SGK3 activation was independent of the increased protein expression of Pit-1. Our co-immunoprecipitation and in vitro kinase assays confirmed that SGK3 interacts with Pit-1 through Thr468 in loop7, leading to enhanced phosphate uptake. Conclusion: Thus, it is justifiable to conclude that SGK3 promotes VC in CKD by enhancing the expression and activities of Pit-1, which indicate that SGK3 could be a therapeutic target for VC in CKD.

Association between dietary calcium intake and severe abdominal aorta calcification among American adults: a cross-sectional analysis of the National Health and Nutrition Examination Survey

BACKGROUND

Evidence regarding the relationship between dietary calcium intake and severe abdominal aortic calcification (AAC) is limited. Therefore, this study aimed to investigate the association between dietary calcium intake and severe AAC in American adults based on data from the National Health and Nutrition Examination Survey (NHANES).

METHODS

The present cross-sectional study utilized data from the NHANES 2013-2014, a population-based dataset. Dietary calcium intake was assessed using two 24-h dietary recall interviews. Quantification of the AAC scores was accomplished utilizing the Kauppila score system, whereby severe AAC was defined as having an AAC score greater than 6. We used multivariable logistic regression models, a restricted cubic spline analysis, and a two-piecewise linear regression model to show the effect of calcium intake on severe AAC.

RESULTS

Out of the 2640 individuals examined, 10.9% had severe AAC. Following the adjustment for confounding variables, an independent association was discovered between an augmented intake of dietary calcium and the incidence of severe AAC. When comparing individuals in the second quartile (Q2) of dietary calcium intake with those in the lowest quartile (Q1), a decrease in the occurrence of severe AAC was observed (odds ratio: 0.66; 95% confidence interval: 0.44-0.99). Furthermore, the relationship between dietary calcium intake and severe AAC demonstrated an L-shaped pattern, with an inflection point observed at 907.259 mg/day. Subgroup analyses revealed no significant interaction effects.

CONCLUSION

The study revealed that the relationship between dietary calcium intake and severe AAC in American adults is L-shaped, with an inflection point of 907.259 mg/day. Further research is required to confirm this association.

Prevotella copri promotes vascular calcification via lipopolysaccharide through activation of NF-κB signaling pathway

Emerging evidence indicates that alteration of gut microbiota plays an important role in chronic kidney disease (CKD)-related vascular calcification (VC). We aimed to investigate the specific gut microbiota and the underlying mechanism involved in CKD-VC. We identified an increased abundance of Prevotella copri (P. copri) in the feces of CKD rats (induced by using 5/6 nephrectomy followed by a high calcium and phosphate diet) with aortic calcification via amplicon sequencing of 16S rRNA genes. In patients with CKD, we further confirmed a positive correlation between abundance of P. copri and aortic calcification scores. Moreover, oral administration of live P. copri aggravated CKD-related VC and osteogenic differentiation of vascular smooth muscle cells in vivo, accompanied by intestinal destruction, enhanced expression of Toll-like receptor-4 (TLR4), and elevated lipopolysaccharide (LPS) levels. In vitro and ex vivo experiments consistently demonstrated that P. copri-derived LPS (Pc-LPS) accelerated high phosphate-induced VC and VSMC osteogenic differentiation. Mechanistically, Pc-LPS bound to TLR4, then activated the nuclear factor κB (NF-κB) and nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome signals during VC. Inhibition of NF-κB reduced NLRP3 inflammasome and attenuated Pc-LPS-induced VSMC calcification. Our study clarifies a novel role of P. copri in CKD-related VC, by the mechanisms involving increased inflammation-regulating metabolites including Pc-LPS, and activation of the NF-κB/NLRP3 signaling pathway. These findings highlight P. copri and its-derived LPS as potential therapeutic targets for VC in CKD.

Phosphonoformic acid reduces hyperphosphatemia-induced vascular calcification via Pit-1

OBJECTIVE

This study aimed to examine the mechanism of hyperphosphatemia-induced vascular calcification (HPVC).

METHODS

Primary human aortic smooth muscle cells and rat aortic rings were cultured in Dulbecco's modified Eagle's medium supplemented with 0.9 mM or 2.5 mM phosphorus concentrations. Type III sodium-dependent phosphate cotransporter-1 (Pit-1) small interfering RNA and phosphonoformic acid (PFA), a Pit-1 inhibitor, were used to investigate the effects and mechanisms of Pit-1 on HPVC. Calcium content shown by Alizarin red staining, expression levels of Pit-1, and characteristic molecules for phenotypic transition of vascular smooth muscle cells were examined.

RESULTS

Hyperphosphatemia induced the upregulation of Pit-1 expression, facilitated phenotypic transition of vascular smooth muscle cells, and led to HPVC in cellular and organ models. Treatment with Pit-1 small interfering RNA or PFA significantly inhibited Pit-1 expression, suppressed phenotypic transition, and attenuated HPVC.

CONCLUSIONS

Our findings suggest that Pit-1 plays a pivotal role in the development of HPVC. The use of PFA as a Pit-1 inhibitor has the potential for therapeutic intervention in patients with HPVC. However, further rigorous clinical investigations are required to ensure the safety and efficacy of PFA before it can be considered for widespread implementation in clinical practice.

Beyond the Basics: Unraveling the Complexity of Coronary Artery Calcification

Coronary artery calcification (CAC) is mainly associated with coronary atherosclerosis, which is an indicator of coronary artery disease (CAD). CAC refers to the accumulation of calcium phosphate deposits, classified as micro- or macrocalcifications, that lead to the hardening and narrowing of the coronary arteries. CAC is a strong predictor of future cardiovascular events, such as myocardial infarction and sudden death. Our narrative review focuses on the pathophysiology of CAC, exploring its link to plaque vulnerability, genetic factors, and how race and sex can affect the condition. We also examined the connection between the gut microbiome and CAC, and the impact of genetic variants on the cellular processes involved in vascular calcification and atherogenesis. We aimed to thoroughly analyze the existing literature to improve our understanding of CAC and its potential clinical and therapeutic implications.

Outcomes of lower extremity peripheral arterial interventions in patients with and without chronic kidney disease or end-stage renal disease

INTRODUCTION

Peripheral arterial disease (PAD) is a progressive vascular condition characterized by the narrowing or blockage of arteries, primarily attributed to atherosclerosis. PAD's prevalence in the general population is estimated at approximately 5.9%. Notably however, among patients with chronic kidney disease (CKD), PAD's prevalence is substantially higher, ranging from 17% to 48%. This review paper emphasizes the pervasiveness of PAD and its intricate relationship with CKD and end-stage renal disease (ESRD). It demonstrates the importance of early detection, proactive screening, and understanding the formidable challenges associated with treating heavily calcified lesions.

EVIDENCE ACQUISITION

Comprehensive literature searches encompassed the PubMed/MEDLINE, Cochrane Library, and Embase databases, in order to identify studies involving lower extremity peripheral arterial interventions in patients both with and without CKD or ESRD. The search spanned the timeframe from January 2001 to July 2023. The search strategy included vocabulary terms concerning peripheral artery disease, lower extremities, revascularization, chronic kidney disease, and end-stage renal disease.

EVIDENCE SYNTHESIS

Initial searches were used to identify articles based on title. Exclusion criteria was then applied, and any redundant articles were removed. The articles abstracts were then reviewed, and relevant articles were selected. Once selected the articles were thoroughly reviewed including the references to find other relevant articles that were missed during the initial search process. In total 28 articles were selected and included for review of clinical data in regard to PAD outcomes in patients with advanced kidney disease.

CONCLUSIONS

The findings highlight the need for personalized approaches in diagnosing and treating PAD in CKD and ESRD patients. Interdisciplinary collaboration, such as those between nephrologists, vascular surgeons, and interventional radiologists, is vital to optimize outcomes. Further research should focus on innovative, tailored interventions to enhance limb preservation, reduce mortality, prolong patency, and cut healthcare costs.

Left ventricular strain and myocardial work in short-term peritoneal dialysis patients

BACKGROUND

Initiation of dialysis encompasses new cardiovascular challenges on patients with end-stage renal disease (ESRD). This study used two-dimensional speckle-tracking echocardiography (2D-STE) to investigate the change of left ventricular (LV) myocardial function undergoing peritoneal dialysis (PD) within 1-3 months.

METHODS

A total of 56 patients with ESRD and 27 healthy controls were enrolled in this prospective study. Mean duration of PD was 44.41 ± 16.44 days. We evaluated LV myocardial function of patients with ESRD in baseline and within 1-3 months after PD by 2D-STE with global longitudinal strains (GLS) and myocardial work (MW). Based on the level of serum phosphate before PD, patients were divided into two groups: the group with normal serum phosphate or hyperphosphatemia.

RESULTS

Compared with healthy controls, patients with ESRD had impaired GLS (p < .001) and increased global work index (GWI) (p = .034), global constructive work (GCW) (p < .001), global wasted work (GWW) (p < .001), and lower global work efficiency (GWE) (p = .002). After PD therapy, GWI (p = .001), GCW (p < .001), and GWW (p = .023) decreased and closed to healthy subjects (p > .05) and no significant improvement was observed in GLS (p = .387). GLS of basal segments worsened in the hyperphosphatemia group (p = .005) and GWW reduced remarkably in the group with normal serum phosphate after PD treatment (p = .008). The change of left ventricular internal diameter in diastole (LVIDd) was the only parameter influenced GWI in post-dialysis patients (β = 0.324, p = .013).

CONCLUSIONS

Short-term PD treatment improved LV MW in ESRD patients. They benefited more when receiving treatment before the increase of serum phosphorus.

C5a-C5aR1 induces endoplasmic reticulum stress to accelerate vascular calcification via PERK-eIF2α-ATF4-CREB3L1 pathway

AIMS

Vascular calcification (VC) predicts the morbidity and mortality in cardiovascular diseases. Vascular smooth muscle cells (VSMCs) osteogenic transdifferentiation is the crucial pathological basis for VC. To date, the molecular pathogenesis is still largely unclear. Notably, C5a-C5aR1 contributes to the development of cardiovascular diseases, and its closely related to physiological bone mineralization which is similar to VSMCs osteogenic transdifferentiation. However, the role and underlying mechanisms of C5a-C5aR1 in VC remain unexplored.

METHODS AND RESULTS

A cross-sectional clinical study was utilized to examine the association between C5a and VC. Chronic kidney diseases mice and calcifying VSMCs models were established to investigate the effect of C5a-C5aR1 in VC, evaluated by changes in calcium deposition and osteogenic markers. The cross-sectional study identified that high level of C5a was associated with increased risk of VC. C5a dose-responsively accelerated VSMCs osteogenic transdifferentiation accompanying with increased the expression of C5aR1. Meanwhile, the antagonists of C5aR1, PMX 53, reduced calcium deposition, and osteogenic transdifferentiation both in vivo and in vitro. Mechanistically, C5a-C5aR1 induced endoplasmic reticulum (ER) stress and then activated PERK-eIF2α-ATF4 pathway to accelerated VSMCs osteogenic transdifferentiation. In addition, cAMP-response element-binding protein 3-like 1 (CREB3L1) was a key downstream mediator of PERK-eIF2α-ATF4 pathway which accelerated VSMCs osteogenic transdifferentiation by promoting the expression of COL1α1.

CONCLUSIONS

High level of C5a was associated with increased risk of VC, and it accelerated VC by activating the receptor C5aR1. PERK-eIF2α-ATF4-CREB3L1 pathway of ER stress was activated by C5a-C5aR1, hence promoting VSMCs osteogenic transdifferentiation. Targeting C5 or C5aR1 may be an appealing therapeutic target for VC.

Lower limb arterial calcification and its clinical relevance with peripheral arterial disease

Lower limb arterial calcification (LLAC) is associated with an increased risk of mortality and it predicts poor outcomes after endovascular interventions in patients with peripheral artery disease (PAD). Detailed histological analysis of human lower artery specimens pinpointed the presence of LLAC in two distinct layers: the intima and the media. Intimal calcification has been assumed to be an atherosclerotic pathology and it is associated with smoking and obesity. It becomes instrumental in lumen stenosis, thereby playing a crucial role in disease progression. On the contrary, medial calcification is a separate process, systematically regulated and linked with age advancement, diabetes, and chronic kidney disease. It prominently interacts with vasodilation and arterial stiffness. Given that both types of calcifications frequently co-exist in PAD patients, it is vital to understand their respective mechanisms within the context of PAD. Calcification can be easily identifiable entity on imaging scans. Considering the highly improved abilities of novel imaging technologies in differentiating intimal and medial calcification within the lower limb arteries, this review aimed to describe the distinct histological and imaging features of the two types of LLAC. Additionally, it aims to provide in-depth insight into the risk factors, the effects on hemodynamics, and the clinical implications of LLAC, either occurring in the intimal or medial layers.

Vascular calcification progression and its association with mineral and bone disorder in kidney transplant recipients

BACKGROUND

The assessment and prevention of vascular calcification (VC) in kidney transplant recipients (KTRs) have not been systematically studied. We aimed to evaluate VC change one year after kidney transplantation (KT) and identify their influencing factors.

METHODS

95 KTRs (68 males; ages 40.2 ± 10.8 years) were followed one year after KT. Changes in bone mineral density (BMD) and bone metabolism biomarkers were assessed. Coronary artery calcification (CAC) and thoracic aortic calcification (TAC) were measured using 192-slice third-generation dual-source CT. The relationship between bone metabolism indicators and VC and the factors influencing VC were analyzed.

RESULTS

Postoperative estimated glomerular filtration rate was 79.96 ± 24.18 mL/min*1.73 m2. One year after KT, serum phosphorus, intact parathyroid hormone (iPTH), osteocalcin, type I collagen N-terminal peptide (NTx), type I collagen C-terminal peptide, and BMD decreased, 25-hydroxyvitamin D remained low, and VC increased. Post-CAC and TAC were negatively correlated with pre-femoral neck BMD, and TAC was positively correlated with post-calcium. CAC and TAC change were positively correlated with post-calcium and 25-hydroxyvitamin D. Increased CAC was positively associated with hemodialysis and pre-femoral neck osteopenia. CAC change was positively associated with prediabetes, post-calcium, and pre-CAC and negatively associated with preoperative and postoperative femoral neck BMD, and NTx change. Increased TAC was positively associated with age, prediabetes, preoperative parathyroid hyperplasia/nodule, post-calcium, and post-femoral neck osteopenia. TAC change was positively associated with age, diabetes, pre-triglyceride, pre-TAC, dialysis time, post-calcium and post-iPTH, and negatively associated with post-femoral neck BMD.

CONCLUSIONS

Mineral and bone disorders persisted, and VC progressed after KT, showing a close relationship.

MicroRNA regulators of vascular pathophysiology in chronic kidney disease

Coronary artery disease (CAD) is a severe comorbidity in chronic kidney disease (CKD) due to heavy calcification in the medial layer and inflamed plaques. Chronic inflammation, endothelial dysfunction and vascular calcification are major contributors that lead to artherosclerosis in CKD. The lack of specific symptoms and signs of CAD and decreased accuracy of noninvasive diagnostic tools result in delayed diagnosis leading to increased mortality. MicroRNAs (miRNAs) are post-transcriptional regulators present in various biofluids throughout the body. In the circulation, miRNAs have been reported to be encapsulated in extracellular vesicles and serve as stable messengers for crosstalk among cells. miRNAs are involved in pathophysiologic mechanisms including CAD and can potentially be extended from basic research to clinical translational practice.

Mineral and bone metabolism markers and mortality in diabetic patients on haemodialysis

BACKGROUND

Diabetic patients on haemodialysis have a higher risk of mortality than non-diabetic patients. The aim of this COSMOS (Current management of secondary hyperparathyroidism: a multicentre observational study) analysis was to assess whether bone and mineral laboratory values [calcium, phosphorus and parathyroid hormone (PTH)] contribute to this risk.

METHODS

COSMOS is a multicentre, open-cohort, 3-year prospective study, which includes 6797 patients from 227 randomly selected dialysis centres in 20 European countries. The association between mortality and calcium, phosphate or PTH was assessed using Cox proportional hazard regression models using both penalized splines smoothing and categorization according to KDIGO guidelines. The effect modification of the association between the relative risk of mortality and serum calcium, phosphate or PTH by diabetes was assessed.

RESULTS

There was a statistically significant effect modification of the association between the relative risk of mortality and serum PTH by diabetes (P = .011). The slope of the curve of the association between increasing values of PTH and relative risk of mortality was steeper for diabetic compared with non-diabetic patients, mainly for high levels of PTH. In addition, high serum PTH (>9 times the normal values) was significantly associated with a higher relative risk of mortality in diabetic patients but not in non-diabetic patients [1.53 (95% confidence interval 1.07-2.19) and 1.17 (95% confidence interval 0.91-1.52)]. No significant effect modification of the association between the relative risk of mortality and serum calcium or phosphate by diabetes was found (P = .2 and P = .059, respectively).

CONCLUSION

The results show a different association of PTH with the relative risk of mortality in diabetic and non-diabetic patients. These findings could have relevant implications for the diagnosis and treatment of chronic kidney disease-mineral and bone disorders.

Serum oxalate concentration is associated with coronary artery calcification and cardiovascular events in Japanese dialysis patients

Coronary artery calcification (CAC) is associated with cardiovascular disease (CVD). CAC might contain calcium oxalate, and a high serum oxalate (SOx) concentration is associated with cardiovascular mortality in dialysis patients. We assessed the associations between SOx and CAC or CVD events in Japanese hemodialysis patients. This cross-sectional and retrospective cohort study was done in 2011. Seventy-seven hemodialysis patients' Agatston CAC score was measured, and serum samples were collected. SOx concentrations were measured in 2021 by using frozen samples. Also, new-onset CVD events in 2011-2021 were retrospectively recorded. The association between SOx concentration and CAC score ≥ 1000, and new-onset CVD events were examined. Median SOx concentration and CAC score were 266.9 (229.5-318.5) µmol/L and 912.5 (123.7-2944), respectively. CAC score ≥ 1000 was associated with SOx [adjusted odds ratio (OR) 1.01, 95% confidence interval (CI), 1.00-1.02]. The number of new-onset CVD events was significantly higher in patients with SOx ≥ median value [hazard ratio (HR) 2.71, 95% CI 1.26-6.16]. By Cox proportional hazard models, new-onset CVD events was associated with SOx ≥ median value (adjusted HR 2.10, 95% CI 0.90-4.91). SOx was associated with CAC score ≥ 1000 and new-onset CVD events in Japanese hemodialysis patients.