Vascular Calcification In Chronic Kidney Disease Patients Research Articles

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.

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.

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

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

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

ABSTRACT Introduction Vascular calcification (VC) which is the pathological mineral deposition in the vascular system, predominantly at the intimal and medial layer of the vessel wall, is an important comorbidity in patients with chronic kidney disease (CKD) leading to significant morbidity and mortality while necessitating appropriate treatment. Our review aims to provide an in-depth analysis of the current understanding of VC. Areas covered In this review, we first discuss the pathophysiology of VC in CKD patients, then we explain the methods to predict and assess VC. Afterwards, we provide the currently available as well as the potential therapeutic approaches of VC. We finally discuss our understanding regarding the current situation surrounding VC in our expert opinion section. Expert opinion Predicting, assessing and treating VC is crucial and the future advances in the field of research surrounding VC will potentially occur in one or more of these three areas of clinical management. There is a current lack of evidence and consensus regarding specific therapeutic options for alleviating VC and this situation may not necessitate VC to be determined, detected, and documented before the available options are implemented. Regardless, the prediction and assessment of VC is still important and requires further improvement together with the developments in therapeutic alternatives. The future has the potential to bring better research which would guide and improve the management of this patient group. A more specialized approach consisting of targeted therapies and more tailored management plans for patients with CKD and VC is on the horizon.

Hypoxia-inducible factor signaling in vascular calcification in chronic kidney disease patients.

Chronic kidney disease (CKD) affects approximately 15% of the adult population in high-income countries and is associated with significant comorbidities, including increased vascular calcifications which is associated with a higher risk for cardiovascular events. Even though the underlying pathophysiology is unclear, hypoxia-inducible factor (HIF) signaling appears to play a central role in inflammation, angiogenesis, fibrosis, cellular proliferation, apoptosis and vascular calcifications which is influenced by multiple variables such as iron deficiency anemia, serum phosphorus and calcium levels, fibroblast growth factor-23 (FGF-23) and Klotho. Along with the growing understanding of the pathology, potential therapeutic alternatives have emerged including HIF stabilizers and SGLT-2 inhibitors. The aim of this review is to discuss the role of HIF signaling in the pathophysiology of vascular calcification in CKD patients and to identify potential therapeutic approaches.

Periostin Augments Vascular Smooth Muscle Cell Calcification via β-Catenin Signaling.

Medial vascular calcification is common in chronic kidney disease (CKD) and is closely linked to hyperphosphatemia. Vascular smooth muscle cells (VSMCs) can take up pro-calcific properties and actively augment vascular calcification. Various pro-inflammatory mediators are able to promote VSMC calcification. In this study, we investigated the effects and mechanisms of periostin, a matricellular signaling protein, in calcifying human VSMCs and human serum samples. As a result, periostin induced the mRNA expression of pro-calcific markers in VSMCs. Furthermore, periostin augmented the effects of β-glycerophosphate on the expression of pro-calcific markers and aggravated the calcification of VSMCs. A periostin treatment was associated with an increased β-catenin abundance as well as the expression of target genes. The pro-calcific effects of periostin were ameliorated by WNT/β-catenin pathway inhibitors. Moreover, a co-treatment with an integrin αvβ3-blocking antibody blunted the pro-calcific effects of periostin. The silencing of periostin reduced the effects of β-glycerophosphate on the expression of pro-calcific markers and the calcification of VSMCs. Elevated serum periostin levels were observed in hemodialysis patients compared with healthy controls. These observations identified periostin as an augmentative factor in VSMC calcification. The pro-calcific effects of periostin involve integrin αvβ3 and the activation of the WNT/β-catenin pathway. Thus, the inhibition of periostin may be beneficial to reduce the burden of vascular calcification in CKD patients.

Vascular Calcification and the Gut and Blood Microbiome in Chronic Kidney Disease Patients on Peritoneal Dialysis: A Pilot Study.

Vascular calcification (VC) is a frequent condition in chronic kidney disease (CKD) and a well-established risk factor for the development of cardiovascular disease (CVD). Gut dysbiosis may contribute to CVD and inflammation in CKD patients. Nonetheless, the role of gut and blood microbiomes in CKD-associated VC remains unknown. Therefore, this pilot study aimed to explore the link between gut and blood microbiomes and VC in CKD patients on peritoneal dialysis (CKD-PD). Our results showed relative changes in specific taxa between CKD-PD patients with and without VC, namely Coprobacter, Coprococcus 3, Lactobacillus, and Eubacterium eligens group in the gut, and Cutibacterium, Pajaroellobacter, Devosia, Hyphomicrobium, and Pelomonas in the blood. An association between VC and all-cause mortality risk in CKD-PD patients was also observed, and patients with higher mortality risk corroborate the changes of Eubacterium eligens in the gut and Devosia genus in the blood. Although we did not find differences in uremic toxins, intestinal translocation markers, and inflammatory parameters among CKD-PD patients with and without VC, soluble CD14 (sCD14), a nonspecific marker of monocyte activation, positively correlated with VC severity. Therefore, gut Eubacterium eligens group, blood Devosia, and circulating sCD14 should be further explored as biomarkers for VC, CVD, and mortality risk in CKD.

Endoplasmic reticulum stress mediates parathyroid hormone-induced apoptosis in vascular smooth muscle cells

Vascular calcification is one of the most common complications of chronic kidney disease (CKD), which is closely associated with increased mortality and morbidity rates of CKD patients. It has been reported that increased parathyroid hormone (PTH) aggravates vascular calcification in CKD patients. However, the direct role of PTH in vascular smooth muscle cells (VSMCs) is less elucidated. Here, we present evidence that PTH promotes apoptosis of VSMCs and endoplasmic reticulum (ER) stress participates in this process. Human aorta vascular smooth muscle cells (HASMCs) were treated with different concentrations of PTH for various time. HASMC apoptosis was detected by flow cytometry. Expression of phosphorylated (p)-PERK, CHOP, IRE1, p-JNK, and cleaved caspase 3 was determined by Western blotting. We found that PTH induced HASMC apoptosis and increased the expression of cleaved caspase 3. Furthermore, PTH activated PERK-CHOP and IRE1-JNK ER stress pathways. Either inhibition of JNK by SP600125 or CHOP by siRNA ameliorated PTH-induced apoptosis in HASMCs. We therefore suggest that ER stress participates in PTH-induced apoptosis of VSMCs, which may be a possible mechanism of PTH-promoted vascular calcification in CKD patients.

Impact of obesity on vascular calcification in patients with chronic kidney disease.

The aim of this study was to compare vascular calcification (VC) in obese and non-obese chronic kidney disease (CKD) patients, using three methods for measuring VC. The study included 168 consecutive patients with CKD. Patients were divided into two groups by body mass index (BMI) - group 1 (BMI ≥ 30 kg/m2) and group 2 (BMI < 30 kg/m2), and according to estimated glomerular filtration rate (eGFR) - subgroup A (eGFR < 45 mL/min/1.73m2) and subgroup B (eGFR < 45 mL/min/1.73m2). VC was assessed by measuring abdominal aortic calcification (AAC), ankle-brachial index (ABI) and echocardiography. Group 1 patients were older (p=0.03). There was a relatively low number of diabetics in our study cohort: 41 patients, (24%). The number of diabetics was similar in both groups. The presence of AAC was more common in 1B and 2B than in 1A and 2A groups (p=0.005 and p=0.02) and in 1B group compared to 2B group (p = 0.05). In both groups, ABI ≥ 1.3 and ABI < 0.9 were more common in B subgroups. The presence of heart valvular lesions was very high in both groups. Spearman rank-order analysis of every cohort demonstrated significant correlation between AAC and heart valve lesions (Spearman R=0.3; p=0.01) and also between AAC and LVH (Spearman R=0.3; p=0.004). Analysis of variance of every cohort showed that in patients with ABI ≥ 1.3 and heart valve lesions, Kauppila score was significantly higher than in those with normal heart valves. Our study shows that obesity is not an independent predictor of VC in CKD patients. VC, assessed by three different methods, was more pronounced in obese patients with lower kidney function.

Fibroblast growth factor 23 and carotid intima media thickness in non-diabetic chronic kidney disease patients

ObjectivesTo clarify the relationship between fibroblast growth factor-23 (FGF23) and carotid intima-media thickness (CIMT) in nondiabetic chronic kidney disease (CKD) patients on conservative treatment.BackgroundCIMT is a reliable marker of subclinical atherosclerosis, and it has been associated with increased risk of cardiovascular events among CKD. Vascular calcification in CKD patients was independently correlated with FGF23.Patients and methodsThe study included 75 nondiabetic CKD patients on conservative treatment aged from 20 to 65 years as group 1 and 15 healthy individuals aged from 28 to 61 years, who have no medical history as a control group (group 2). Group 1 was subdivided into two groups: patients with increased CMIT and patients with normal CMIT. The study was conducted from October 2018 to May 2019. The patients were excluded if they have any of the following criteria: acute illness, CKD on dialysis, and patients with diabetes mellitus. The study was a case–control study. All patients and healthy individuals were subjected to the following: full history taking, general demographic data, including age, sex, height, weight, drug history, clinical examination, and laboratory investigations in the form of complete blood count, serum creatinine, and fasting and postprandial blood glucose. Estimated glomerular filtration rate (eGFR) was calculated by the Cockcroft–Gault formula as follows: eGFR=[140 − age (years)]×weight (kg)/serum creatinine (mg/dl)×72 [×0.85 if female], liver function tests (alanine transferase, aspartate transferase, serum albumin level), corrected serum calcium, serum phosphorus, lipid profile, carotid ultrasound, and intact FGF23.ResultsFGF23 levels and CIMT were significantly increasing across all the stages of CKD. The CIMT is significantly increasing in nondiabetic CKD patients with FGF23 levels of above 190 pg/ml. FGF23 levels positively correlated with the levels of creatinine, calcium, phosphrous, eGFR, hemoglobin, and albumin in nondiabetic CKD patients.ConclusionNondiabetic CKD patients had higher levels of FGF23 than controls. Nondiabetic CKD patients with increased CIMT had significantly higher phosphorus, creatinine, and FGF23 levels than those with normal CIMT. CIMT and FGF23 were significantly increased across all the stages of CKD. Increasing FGF23 concentrations across the stages of CKD reflect increasing CIMT and progression in CKD nondiabetic patients on conservative treatment.

MO740EFFECT OF DIPHOSPHONATES FOR VASCULAR CALCIFICATION IN CHRONIC KIDNEY DISEASE: A META-ANALYSIS

Abstract Background and Aims Vascular calcification is an independent predict factor of cardiovascular mortality and all-cause mortality in chronic kidney disease (CKD) patients. Animals experiments and clinical studies showed the inhibition effect of diphosphonates in vascular calcification, but the results of the studies remains controversial. This meta-analysis aims to evaluate the effects of diphosphonates on vascular calcification in patients with CKD. Method Randomized controlled trials (RCT) and non-RCTs of diphosphonates for the treatment of vascular calcification in CKD patients until September 2020 were searched in the database of PubMed, Embase, Cochrane library, CNKI and Wanfang. Literatures were screened according to the inclusion and exclusion criteria and quality was evaluated by two investigators independently. The standard deviation from mean (SMD) and 95% confidence interval (CI) were used to representthe counting data. Data extracted from the literatures were analyzed with Stata software (version 15.0). Results A total of 6 RCTs and 1 non-RCT with 272 patients were included, characteristics of the studies included are shown in Table 1. Meta-analysis indicated that diphosphonates inhibit vascular calcification in CKD [SMD =-0.297, 95% CI = (-0.591, -0.002), P = 0.049] (Figure 1). Etidronate is the most effective one in treating with vascular calcification (P = 0.020) (Figure 2). But there isn’t significant difference in aortic artery calcification and coronary artery calcification compared with the control group (P&amp;gt;0.05). There was no statistically significant difference in the change of blood calcium, blood phosphate, and serum parathyroid hormone between two groups (all P&amp;gt;0.05). Conclusion Diphosphonates can inhibit the progression of vascular calcification in CKD patients, and it hasn’t obvious effect on blood calcium, blood phosphate, and serum parathyroid hormone. Etidronate is the most promising therapeutic agent.

Vascular Calcification in Chronic Kidney Disease: Distinct Features of Pathogenesis and Clinical Implication.

Chronic kidney disease (CKD) is associated with a higher prevalence of vascular calcification (VC) and cardiovascular disease. VC in CKD patients showed different pathophysiological features from those of the general population. The pathogenesis of VC in CKD is a highly organized process, and prior studies have suggested that patients with CKD have their own specific contributors to the phenotypic change of vascular smooth muscle cells (VSMCs), including uremic toxins, CKD-mineral and bone disease (CKD-MBD), inflammation, and oxidative stress. For the diagnosis and monitoring of VC in CKD, several imaging modalities, including plain radiography, ultrasound, and computed tomography have been utilized. VC in CKD patients has distinct clinical features and implications. CKD patients revealed a more intense and more prevalent calcification on the intimal and medial layers, whereas intimal calcification is predominantly observed in the general population. While a higher VC score is clearly associated with a higher risk of all-cause mortality and cardiovascular events, a greater VC score in CKD patients does not fully reflect the burden of atherosclerosis, because they have more calcification at equal volumes of atheromatous plaques. The primary goal of VC treatment in CKD is the prevention of VC progression, and the main management is to control the biochemical components of CKD-MBD. Cinacalcet and non-calcium-containing phosphate binders are the mainstay of VC prevention in CKD-MBD management. VC in patients with CKD is an ongoing area of research and is expected to advance soon.

MGP T-138C Polymorphism (TT Genotype) is Associated with Vascular Calcification Incidence in Indonesian Regular Hemodialysis Patients

BACKGROUND: Vascular calcification contributes greatly to the incidence of cardiovascular disease. Previously, vascular calcification was considered as a passive process caused by the mineral deposition from the circulation. Nowadays, researchers have found inhibitors and promoter factors from vascular calcification, one of which is the matrix gla protein (MGP). MGP levels depend on the gene that encodes them. The MGP T-138C polymorphism is one of the most common causes of vascular calcification.METHODS: This was a case-control study involving 86 chronic kidney disease (CKD) patients who underwent regular hemodialysis in Rasyida Kidney Hospital, Medan, Indonesia. Vascular calcification was determined from lateral and posteroanterior abdominal X-ray. The MGP T-138 C polymorphism was analyzed using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP).RESULTS: The TT/TC genotype associates with the incidence of vascular calcification with OR of 3.52, 95% CI: 1.23-10.106 (p-value&lt;0.001).CONCLUSION: There is an association between MGP T-138C polymorphism, particularly on T Allele with the incidence of vascular calcification in CKD patients undergoing regular hemodialysis.KEYWORDS: hemodialysis, T-138 C polymorphism, vascular calcification, matrix GLA protein

Mitoquinone attenuates vascular calcification by suppressing oxidative stress and reducing apoptosis of vascular smooth muscle cells via the Keap1/Nrf2 pathway

Oxidative stress and apoptosis of vascular smooth muscle cells (VSMCs) are key to vascular calcification in patients with chronic kidney disease (CKD). The mitochondria-targeted antioxidant, mitoquinone (MitoQ), which reduces oxidative stress and apoptosis, has a protective effect in acute models of renal injury but whether MitoQ can attenuate vascular calcification in CKD patients is unknown. This study was conducted to investigate whether MitoQ can prevent calcification, both in vitro and in vivo. Adenine was used to induce calcification in rats, and inorganic phosphate was used to induce calcification in VSMCs. To elucidate the underlying molecular mechanism, a specific inhibitor of Nrf2, ML385, was used 1 h before MitoQ administration. Histological staining, ELISA, flow cytometry, alizarin red staining and western blotting were used to test this hypothesis. Administration of MitoQ alleviated calcification and oxidative stress. The anti-apoptotic effect of MitoQ was associated with upregulation of Bcl-2, downregulation of Bax, and increased Nrf2 expression. The effects of MitoQ were reversed by treatment with ML385. This study offers evidence that MitoQ attenuates vascular calcification by suppressing oxidative stress and apoptosis of VSMCs through the Keap1/Nrf2 pathway. MitoQ should be further investigated as a potential therapy to prevent vascular calcification in CKD patients.

Indoxyl sulfate promotes osteogenic differentiation of vascular smooth muscle cells by miR-155-5p-dependent downregulation of matrix Gla protein via ROS/NF-κB signaling

Vascular calcification (VC) is a major risk factor for increasing cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD). Indoxyl sulfate (IS), a representative uremic toxin, is closely associated with VC in CKD patients. Matrix Gla protein (MGP) plays pivotal role in VC as a calcification inhibitor. The aim of this work was to explore whether MGP was involved in IS-induced VC. Here, we demonstrated the role of MGP in the IS-induced osteogenic differentiation of human aortic smooth muscle cells (HASMCs). The methods included Von Kossa staining, immunohistochemistry, Alizarin Red staining, quantitative real-time PCR and western blotting. MGP was decreased in calcified arteries both in CKD patients and rats. In vitro, IS suppressed MGP expression in HASMCs by activating ROS/NF-κB signaling in parallel with osteogenic differentiation, which was mitigated by inhibiting ROS and NF-κB with diphenyleneiodonium and Bay11-7082. Further investigation showed that IS induced NF-κB-responsive microRNA (miR)-155-5p mediating MGP downregulation. Overexpression of miR-155-5p with mimics aggravated IS-induced MGP reduction and osteogenic differentiation. In contrast, these conditions were diminished by silencing miR-155-5p. We demonstrate that IS promotes the HASMCs phenotype switch by suppressing MGP expression via ROS/NF-κB/miR-155-5p signaling and provide a new insight for the pathogenesis of IS-induced VC.

Farnesoid X receptor activation inhibits TGFBR1/TAK1-mediated vascular inflammation and calcification via miR-135a-5p

Chronic inflammation plays a crucial role in vascular calcification. However, only a few studies have revealed the mechanisms underlying the development of inflammation under high-phosphate conditions in chronic kidney disease (CKD) patients. Here, we show that inflammation resulting from the activation of the TGFBR1/TAK1 pathway is involved in calcification in CKD rats or osteogenic medium-cultured human aortic smooth muscle cells (HASMCs). Moreover, miR-135a-5p is demonstrated to be a key regulator of the TGFBR1/TAK1 pathway, which has been reported to be decreased in CKD rats. We further reveal that farnesoid X receptor (FXR) activation increases miR-135a-5p expression, thereby inhibiting the activation of the TGFBR1/TAK1 pathway, ultimately resulting in the attenuation of vascular inflammation and calcification in CKD rats. Our findings provide advanced insights into the mechanisms underlying the development of inflammation in vascular calcification, and evidence that FXR activation could serve as a therapeutic strategy for retarding vascular calcification in CKD patients.

Oxidative stress contributes to vascular calcification in patients with chronic kidney disease

Vascular calcification (VC) is a major cause of mortality in patients with chronic kidney disease (CKD). While elevations in serum phosphorus contribute to VC, we provide evidence here for a major role of oxidative stress (OS) in VC pathogenesis without an apparent increase in serum phosphorus in early CKD. In a rat model for stage 5 CKD (CKD5), we observed 1) robust increases of VC and OS, 2) significant reductions of smooth muscle 22 alpha (SM22α) and calponin, and 3) upregulations in Runt-related transcription factor 2 (RUNX2) and collagen I in vascular smooth muscle cells (VSMCs). Inhibition of OS using MnTMPyP dramatically reduced these events without normalization of hyperphosphatemia. In CKD5 patients with VC (n = 11) but not in those without VC (n = 13), OS was significantly elevated. While the serum levels of calcium and phosphate were not altered in the animal model for early stage CKD (ECKD), OS, VC, SM22α, calponin, RUNX2, collagen I and NADPH oxidase 1 (NOX1) in VSMCs were all significantly changed. More importantly, serum (5%) derived from patients with ECKD (n = 30) or CKD5 (n = 30) induced SM22α and calponin downregulation, and RUNX2, collagen I, NOX1 upregulation along with a robust elevation of OS and calcium deposition in primary rat VSMCs. These alterations were all reduced by MnTMPyP, ML171 (a NOX1 inhibitor), and U0126 (an inhibitor of Erk signaling). Collectively, we provide a comprehensive set of evidence supporting an important role of OS in promoting VC development in CKD patients (particularly in those with ECKD); this was at least in part through induction of osteoblastic transition in VSMCs which may involve the Erk singling. Our research thus suggests that reductions in OS may prevent VC in CKD patients.

The interplay between mineral metabolism, vascular calcification and inflammation in Chronic Kidney Disease (CKD): challenging old concepts with new facts.

Chronic kidney disease (CKD) is one of the most powerful predictors of premature cardiovascular disease (CVD), with heightened susceptibility to vascular intimal and medial calcification associated with a high cardiovascular mortality. Abnormal mineral metabolism of calcium (Ca) and phosphate (P) and underlying (dys)regulated hormonal control in CKD-mineral and bone disorder (MBD) is often accompanied by bone loss and increased vascular calcification (VC). While VC is known to be a multifactorial process and a major risk factor for CVD, the view of primary triggers and molecular mechanisms complexity has been shifting with novel scientific knowledge over the last years. In this review we highlight the importance of calcium-phosphate (CaP) mineral crystals in VC with an integrated view over the complexity of CKD, while discuss past and recent literature aiming to highlight novel horizons on this major health burden. Exacerbated VC in CKD patients might result from several interconnected mechanisms involving abnormal mineral metabolism, dysregulation of endogenous calcification inhibitors and inflammatory pathways, which function in a feedback loop driving disease progression and cardiovascular outcomes. We propose that novel approaches targeting simultaneously VC and inflammation might represent valuable new prognostic tools and targets for therapeutics and management of cardiovascular risk in the CKD population.

Peroxisome Proliferator-Activated Receptor-γ Coactivator-1α Inhibits Vascular Calcification Through Sirtuin 3-Mediated Reduction of Mitochondrial Oxidative Stress.

Aims: Vascular calcification is associated with cardiovascular death in patients with chronic kidney disease (CKD). Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) plays an important role in various cardiovascular diseases. However, its role in vascular calcification remains unknown. Results: Adenine-induced rat CKD model was used to induce arterial medial calcification. The level of PGC-1α decreased in abdominal aorta of CKD rats. Overexpression of PGC-1α significantly ameliorated calcium deposition in rat abdominal aorta, isolated carotid rings, and cultured vascular smooth muscle cells (VSMCs). Mitochondrial reactive oxygen species (mtROS) increased in calcifying aorta and VSMCs. Upregulation of PGC-1α inhibited, whereas PGC-1α depletion promoted β-glycerophosphate-induced mtROS production and calcium deposition. Moreover, PGC-1α increased superoxide dismutase 1 (SOD1) and SOD2 contents in vivo and in vitro, whereas SOD2 deletion eliminated PGC-1α-mediated mtROS change and promoted calcium deposition. Mechanistically, sirtuin 3 (SIRT3) expression declined in calcifying aorta and VSMCs, while PGC-1α overexpression restored SIRT3 expression. Inhibition of SIRT3 by 3-TYP or siRNA (small interfering RNA) reduced PGC-1α-induced upregulation of SOD1 and SOD2, and abolished the protective effect of PGC-1α on calcification of VSMCs. Importantly, PGC-1α was reduced in calcified femoral arteries in CKD patients. In phosphate-induced human umbilical arterial calcification, upregulation of PGC-1α attenuated calcium nodule formation, while this protective effect was abolished by SIRT3 inhibitor. Innovation: We showed for the first time that PGC-1α is an important endogenous regulator against vascular calcification. Induction of PGC-1α could be a potential strategy to treat vascular calcification in CKD patients. Conclusions: PGC-1α protected against vascular calcification by SIRT3-mediated mtROS reduction.

Spironolactone dose‑dependently alleviates the calcification of aortic rings cultured in hyperphosphatemic medium with or without hyperglycemia by suppressing phenotypic transition of VSMCs through downregulation of Pit‑1.

Vascular calcification (VC) is highly prevalent in chronic kidney disease (CKD), especially in patients with end stage renal disease and is strongly associated with cardiovascular morbidity and mortality. Clinical observations have demonstrated that hyperphosphatemia and hyperglycemia can accelerate VC. Spironolactone (SPL) has been proven to improve cardiovascular outcomes in clinical trials and its protective effect on VC has been reported recently; however, the underlying mechanisms are not completely understood and require further investigation. Furthermore, the current CKD rat models that are used to research VC do not match well with the clinical characteristics of CKD patients. Aortic rings were obtained from male Sprague-Dawley rats, then cultured in different media with varying phosphorus and glucose concentrations to investigate the effects and the possible mechanisms, as well as the effective serum concentrations of SPL, on VC and type III sodium-dependent phosphate cotransporter-1 (Pit-1) expression. SPL dose-dependently alleviated VC by suppressing the phenotypic transition of vascular smooth muscle cell (VSMCs) through downregulation of Pit-1 in a high phosphorus medium and even in a high phosphorus combined with high glucose medium. The combined effects of hyperglycemia and hyperphosphatemia on the calcification of aortic rings ex vivo were demonstrated. In conclusion to the best of our knowledge, this article is the first report on the effective serum concentrations of SPL capable of protecting VSMCs from calcification and provides the first experimental evidence for the combined effects of hyperglycemia and hyperphosphatemia on VC of aortic rings. Additionally, the Pit-1 protein level may be a novel index for evaluating the magnitude of VC in CKD patients.

Emerging Role of Vitamins D and K in Modulating Uremic Vascular Calcification: The Aspect of Passive Calcification.

Vascular calcification is a critical complication in patients with chronic kidney disease (CKD) because it is predictive of cardiovascular events and mortality. In addition to the traditional mechanisms associated with endothelial dysfunction and the osteoblastic transformation of vascular smooth muscle cells (VSMCs), the regulation of calcification inhibitors, such as calciprotein particles (CPPs) and matrix vesicles plays a vital role in uremic vascular calcification in CKD patients because of the high prevalence of vitamin K deficiency. Vitamin K governs the gamma-carboxylation of matrix Gla protein (MGP) for inhibiting vascular calcification, and the vitamin D binding protein receptor is related to vitamin K gene expression. For patients with chronic kidney disease, adequate use of vitamin D supplements may play a role in vascular calcification through modulation of the calciprotein particles and matrix vesicles (MVs).