Vascular Calcification In Chronic Kidney Disease Research Articles

#571 Vitamin D receptor from VSMCs regulates vascular calcification during CKD: a potential role for miR-145a

Abstract Background and Aims Vascular calcification (VC) is a highly prevalent complication of chronic kidney disease (CKD) and is associated with the higher morbidity-mortality of patients with CKD. Vitamin D receptor (VDR) has been proposed to play a role in the osteoblastic differentiation of vascular smooth muscle cells (VSMCs), but the involvement of vitamin D (1, 25D) in VC associated to CKD is controversial. Accumulating evidence points to microRNAs as important players in the process of VC and recent studies show that miR-145a expression decreases in VSMCs during VC. In addition, VDR has been considered as a potent regulator of these small molecules, while miR-145a was identified as a target for 1, 25D. Our aim was to determine the role of local vitamin D signalling in VSMCs during CKD-induced VC and the involvement of miR-145a in this process. Method We used epigastric arteries from CKD-affected patients and from individuals with normal renal function. In vivo, we employed an experimental model of CKD-induced VC in mice with conditional deletion of VDR in VSMC (Myh11-CreERT2+ VDRlox/lox), while in vitro, we used mouse VSMC with (VDRwt) or without VDR (VDRko) incubated in calcification media. Transfection experiments with mmu-miR-145a-5p mimic or mmu-miR-145a-5p inhibitor were carried out in mouse VDRwt VSMCs. Results CKD-affected patients showed an increase in VC, alongside an increased arterial expression of VDR compared with controls with normal renal function. Conditional gene silencing of VDR in arterial VSMCs led to a significant decrease of VC in the mouse model of CKD, despite similar levels of renal impairment and serum calcium and phosphate levels. This was accompanied by lower arterial expression of osteopontin (OPN) and lamin A, and a higher expression of sclerostin (SOST). Runx2 was increased in arteries of both CKD groups independently of the presence of VDR in VSMCs. Furthermore, CKD-affected mice showed a reduction of miR-145a expression in calcified arteries, which was significantly recovered in animals with deletion of VDR in VSMCs. In vitro, the absence of VDR prevented VC, inhibited the increase of OPN, and re-established the expression of miR-145a. Forced expression of miR-145a in vitro in VDRwt VSMCs blunted VC and decreased OPN levels. Mir-145a levels markedly decreased both in human and mouse VDRwt VSMCs incubated in calcification media and 1, 25D. Overexpression of miR-145a suppressed the levels of OPN induced by 1, 25D, while the inhibition of mir-145a led to a significant increase in OPN levels, even higher than in cells treated solely with 1, 25D. A predicted miR-145a-binding site was detected at the 3’UTR of OPN mRNA transcript, through the extended seed region of the miRNA, pointing to OPN as a possible target of mir-145a during VC in CKD. There were no significant differences in Runx2 levels in 1, 25D-treated cells after transfection with mir-145a mimic or inhibitor. Conclusion VDR is induced in calcified VSMCs during CKD where it can modulate the expression of promoters and inhibitors of VSMC transdifferentiation, as well as small noncoding RNA molecules such as mir-145a that modulate VC. The regulation of these pathways by VDR seems to be essential for the settings of CKD-induced VC, as deletion of VDR from VSMCs prevented it.

#2382 Renal tubule-derived EVs carrying complement 3 aggravate CKD vascular calcification by downregulating autophagy in vascular smooth muscle cells

Abstract Background and Aims Vascular calcification (VC) is a serious complication of chronic kidney disease (CKD) patients, recognized in KDIGO guidelines as a leading risk factor for cardiovascular diseases. Despite acknowledgment, the mechanisms of VC in CKD remain unclear. The kidneys intricately regulate blood vessel pathophysiology. Clinical studies suggest a correlation between elevated blood complement levels in CKD and arterial calcification, hinting at complement involvement in CKD-associated VC. Renal-origin complement, a significant source of circulating complement, activates in CKD. Extracellular vesicles (EVs), mediating intercellular communication, transport complement-related proteins in various physiological and pathological processes. Studies suggest that plasma EV rather than EV-depleted plasma causes pathogenic calcium salt deposition in smooth muscle cells. This study explores how renal-origin EVs carrying complement mediate CKD-associated VC. Method From October 2021 to August 2023, data from 110 clinical patients were gathered, encompassing both blood C3 levels and CT images of the thoracic aorta. Subsequently, we conducted a scoring analysis of the CT images and carried out correlation analyses. A CKD-associated VC model was induced by feeding C57BL/6j mice an adenine and high-phosphate diet for 16 weeks. Techniques, including WB, PCR, and immunofluorescence, detected complement activation and localization in renal tissues. EVs were isolated from kidney tissue and plasma and identified by NTA, electron microscopy, WB, etc. WB examined C3 and tubular markers of EVs. At the same time, the Elisa method was used to detect C3 in plasma, plasma EV, and EV-depleted plasma. Immunofluorescence investigated tubular-derived EVs uptake in calcified arteries. Tubular-derived EVs, C3a, C3aR receptor inhibitors (SB290157), and autophagy inhibitors (3-MA) intervened in high-phosphate-induced vascular smooth muscle cells (VSMCs). PCR and WB assessed calcification indicators, complement receptors, and autophagy-related indicators. Alizarin Red staining observed calcification nodules. Transcriptome sequencing was performed on control, high-phosphate, and renal tubular-derived EV intervention groups of VSMCs. An in vivo model infused renal tubular-derived EVs and injected C3aR inhibitors and autophagy inhibitors, measuring complement activation and VC indicators. Results There is a correlation between C3 and thoracic aorta calcium score in CKD patients, with a correlation coefficient of 0.3750 (P < 0.01). The CKD-associated VC mice model revealed complement C3 activation in renal tubules, secreted into the blood through EVs. The C3 proportion of plasma EV in CKD patients was significantly higher than that in the control group, but there was no statistical difference between the EV-depleted plasma control group and the CKD group. Immunofluorescence indicated tubular-derived EV uptake by the calcified vascular wall. In vitro, tubular-derived EVs enhanced VSMC osteogenic differentiation and upregulated C3aR, mimicking C3a intervention effects. C3aR receptor inhibitors produced opposing effects. Transcriptome sequencing suggested renal tubular-derived EVs downregulated VSMC autophagy-related pathways; in vitro autophagy inhibition reversed osteogenic differentiation. In vivo, reinfusing renal tubular-derived EVs exacerbated complement activation and VC, while injecting C3aR inhibitors and autophagy inhibitors alleviated CKD-associated VC. Conclusion This study confirms that tubular-derived EVs carrying C3 downregulate autophagy in VSMCs, mediating CKD-associated VC. These findings provide insights into understanding CKD-associated VC initiation and progression, revealing potential therapeutic targets.

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

ABSTRACT 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.

Relationship between arginine methylation and vascular calcification

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

Food to Prevent Vascular Calcification in Chronic Kidney Disease.

Vascular calcification (VC) is a consequence of chronic kidney disease (CKD) which is of paramount importance regarding the survival of CKD patients. VC is far from being controlled with actual medication; as a result, in recent years, diet modulation has become more compelling. The concept of medical nutritional therapy points out the idea that food may prevent or treat diseases. The aim of this review was to evaluate the influence of food habits and nutritional intervention in the occurrence and progression of VC in CKD. Evidence reports the harmfulness of ultra-processed food, food additives, and animal-based proteins due to the increased intake of high absorbable phosphorus, the scarcity of fibers, and the increased production of uremic toxins. Available data are more supportive of a plant-dominant diet, especially for the impact on gut microbiota composition, which varies significantly depending on VC presence. Magnesium has been shown to prevent VC but only in experimental and small clinical studies. Vitamin K has drawn considerable attention due to its activation of VC inhibitors. There are positive studies; unfortunately, recent trials failed to prove its efficacy in preventing VC. Future research is needed and should aim to transform food into a medical intervention to eliminate VC danger in CKD.

Interaction of Sp1 and Setd8 promotes vascular smooth muscle cells apoptosis by activating Mark4 in vascular calcification.

Vascular calcification (VC) is directly related to high mortality in chronic kidney disease (CKD), and cellular apoptosis of vascular smooth muscle cells (VSMCs) is a crucial process in the initiation of VC. Microtubule affinity-regulating kinase 4 (Mark4), known as a serine/threonine protein kinase, can induce cell apoptosis and autophagy by modulating Akt phosphorylation. However, the potential functions and molecular mechanisms of Mark4 in VSMCs apoptosis and calcification need to be further explored. Initially, our data indicated that the mRNA expression of Mark4 was prominently elevated in high phosphorus-stimulated human VSMCs compared with the other members in Marks. Consistently, Mark4 expression was found to be significantly increased in the calcified arteries of both CKD patients and rats. In vitro, silencing Mark4 suppressed apoptosis-specific marker expression by promoting Akt phosphorylation, finally attenuating VSMCs calcification induced by high phosphate. Mechanically, the transcription factor Sp1 was enriched in the Mark4 promoter region and modulated Mark4 transcription. Moreover, SET domain-containing protein 8 (Setd8) was proved to interact with Sp1 and jointly participated in the transcriptional regulation of Mark4. Finally, rescue experiments revealed that Setd8 contributed to VSMCs apoptosis and calcification by modulating Mark4 expression. In conclusion, these findings reveal that Mark4 is transcriptionally activated by Sp1, which is interacted with Setd8, to promote VSMCs calcification through Akt-mediated antiapoptotic effects, suggesting that Mark4 represents a potent and promising therapeutic target for VC in CKD.

Extracellular Histones Promote Calcium Phosphate-Dependent Calcification in Mouse Vascular Smooth Muscle Cells.

Vascular calcification, a major risk factor for cardiovascular events, is associated with a poor prognosis in chronic kidney disease (CKD) patients. This process is often associated with the transformation of vascular smooth muscle cells (VSMCs) into cells with osteoblast-like characteristics. Damage-associated molecular patterns (DAMPs), such as extracellular histones released from damaged or dying cells, are suspected to accumulate at calcification sites. To investigate the potential involvement of DAMPs in vascular calcification, we assessed the impact of externally added histones (extracellular histones) on calcium and inorganic phosphate-induced calcification in mouse VSMCs. Our study found that extracellular histones intensified calcification. We also observed that the histones decreased the expression of VSMC marker genes, while simultaneously increasing the expression of osteoblast marker genes. Additionally, histones treated with DNase I, which degrades dsDNA, attenuated this calcification, compared with the non-treated histones, suggesting a potential involvement of dsDNA in this process. Elevated levels of dsDNA were also detected in the serum of CKD model mice, underlining its potential role in vascular calcification in CKD. Our findings suggest that extracellular histones could play a pivotal role in the vascular calcification observed in CKD.

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.

Roxadustat ameliorates vascular calcification in CKD rats by regulating HIF-2α/HIF-1α.

Vascular calcification (VC) is a common complication of chronic kidney disease (CKD). VC is a gene-regulated process similar to osteogenic differentiation. There are still no convincing schemes to prevent and reduce the development of VC. It has been reported that hypoxia-inducing factor 1α (HIF-1α) and endothelin-1(ET-1) are related to VC. In this study, we found that the expression of ET-1 and HIF-1α was enhanced after VC, the interaction between HIF-1α and ET-1 was confirmed by CO-IP and luciferase experiments. We found that ET-1 was an upregulated differential gene of calcified vascular smooth muscle cells (VSMCs) through gene sequencing. However, hypoxia-inducing factor 2α (HIF-2α) and HIF-1α have antagonistic effects on each other. HIF-1α is a pro-inflammatory cytokine, and HIF-2α can improve inflammation and fibrosis. Roxadustat, as a selective PHD3 inhibitor, preferentially activates HIF-2α. It is still unclear whether roxadustat improves VC in CKD by regulating the expression of HIF-2α/HIF-1α. Alizarin red staining and western blot as well as immunohistochemical results showed that roxadustat could significantly reduce the degree of vascular and VSMCs calcification in CKD rats. Serum HIF-1α and ET-1 were significantly decreased after roxadustat treatment. In addition, western blot results showed that roxadustat could decrease the expression of HIF-1α and ET-1 in vascular tissues and calcified VSMC, but HIF-2α expression significantly increased. Interestingly, our study confirmed that activation of HIF-1α or inhibition of HIF-2α reversed the ameliorating effect of roxadustat on VC, proving that the effect mediated by roxadustat is HIF-2α/HIF-1α dependent. We have demonstrated for the first time that roxadustat improves VC in CKD rats by regulating HIF-2α/HIF-1α, thus providing a new idea for the application of roxadustat in VC of CKD.

Antihypertensive treatment with hydrochlorothiazide-hydralazine combination aggravates medial vascular calcification in CKD rats with mineral bone disorder.

Arterial stiffness and medial vascular calcification, leading to isolated systolic blood pressure (BP), are major cardiovascular risk factors in patients with chronic kidney disease (CKD) and mineral bone disorders (MBD). The impact of BP on MBD-induced medial vascular calcification in CKD remains uncertain. We investigated whether BP reduction improves arterial stiffness and medial vascular calcification in a rat model of CKD-MBD. CKD was induced in Wistar rats by subtotal nephrectomy. Then, MBD was generated by a Ca/P-rich diet with calcitriol supplementation to induce medial vascular calcification. Two antihypertensive treatments were evaluated: (1) the angiotensin AT1 receptor antagonist losartan, and (2) the combination of the thiazide diuretic hydrochlorothiazide and the direct vasodilator hydralazine (HCTZ/HY). After 5 weeks, mean BP (MBP), pulse pressure (PP), and pulse wave velocity (PWV) were determined. Vascular calcification was assessed in the thoracic aorta. While MBP was similar in CKD-MBD and control CKD rats, PP and PWV were increased in CKD-MBD rats. The heightened arterial stiffness in CKD-MBD rats was associated with diffused medial calcification along the thoracic aorta. Although both losartan and HCTZ/HY reduced MBP in CKD-MBD rats, losartan did not affect PP and PWV nor medial vascular calcification, whereas HCTZ/HY, unexpectedly, further increased arterial stiffness and medial vascular calcification. In the rat model of CKD-MBD, antihypertensive treatment with losartan did not affect arterial stiffness or medial vascular calcification. However, HCTZ/HY treatment aggravated arterial stiffness and vascular calcification despite a similar reduction of MBP, suggesting a blood pressure-independent mechanism for vascular calcification.

Chronic kidney disease mineral bone disorder in childhood and young adulthood: a ‘growing’ understanding

Chronic kidney disease (CKD) mineral and bone disorder (MBD) comprises a triad of biochemical abnormalities (of calcium, phosphate, parathyroid hormone and vitamin D), bone abnormalities (turnover, mineralization and growth) and extra-skeletal calcification. Mineral dysregulation leads to bone demineralization causing bone pain and an increased fracture risk compared to healthy peers. Vascular calcification, with hydroxyapatite deposition in the vessel wall, is a part of the CKD-MBD spectrum and, in turn, leads to vascular stiffness, left ventricular hypertrophy and a very high cardiovascular mortality risk. While the growing bone requires calcium, excess calcium can deposit in the vessels, such that the intake of calcium, calcium- containing medications and high calcium dialysate need to be carefully regulated. Normal physiological bone mineralization continues into the third decade of life, many years beyond the rapid growth in childhood and adolescence, implying that skeletal calcium requirements are much higher in younger people compared to the elderly. Much of the research into the link between bone (de)mineralization and vascular calcification in CKD has been performed in older adults and these data must not be extrapolated to children or younger adults. In this article, we explore the physiological changes in bone turnover and mineralization in children and young adults, the pathophysiology of mineral bone disease in CKD and a potential link between bone demineralization and vascular calcification.Graphical abstractA higher resolution version of the Graphical abstract is available as Supplementary information

Vitamin D Receptor From VSMCs Regulates Vascular Calcification During CKD: A Potential Role for miR-145a.

Vascular calcification (VC) is a highly prevalent complication of chronic kidney disease (CKD) and is associated with the higher morbidity-mortality of patients with CKD. VDR (vitamin D receptor) has been proposed to play a role in the osteoblastic differentiation of vascular smooth muscle cells (VSMCs), but the involvement of vitamin D in VC associated to CKD is controversial. Our aim was to determine the role of local vitamin D signaling in VSMCs during CKD-induced VC. We used epigastric arteries from CKD-affected patients and individuals with normal renal function, alongside an experimental model of CKD-induced VC in mice with conditional deletion of VDR in VSMC. In vitro, experiments in VSMC with or without VDR incubated in calcification media were also used. CKD-affected patients and mice with CKD showed an increase in VC, together with increased arterial expression of VDR compared with controls with normal renal function. Conditional gene silencing of VDR in VSMCs led to a significant decrease of VC in the mouse model of CKD, despite similar levels of renal impairment and serum calcium and phosphate levels. This was accompanied by lower arterial expression of OPN (osteopontin) and lamin A and higher expression of SOST (sclerostin). Furthermore, CKD-affected mice showed a reduction of miR-145a expression in calcified arteries, which was significantly recovered in animals with deletion of VDR in VSMC. In vitro, the absence of VDR prevented VC, inhibited the increase of OPN, and reestablished the expression of miR-145a. Forced expression of miR-145a in vitro in VDRwt VSMCs blunted VC and decreased OPN levels. Our study provides evidence proving that inhibition of local VDR signaling in VSMCs could prevent VC in CKD and indicates a possible role for miR-145a in this process.

#4372 TYK2-INDUCED STAT ACTIVATION IS ESSENTIAL FOR VASCULAR PRO-CALCIFIC EFFECTS OF LEUKEMIA INHIBITORY FACTOR

Abstract Background and Aims Hyperphosphatemia in chronic kidney disease (CKD) is closely linked to medial vascular calcification. Phosphate is able to induce pro-inflammatory effects in vascular smooth muscle cells (VSMC), which could actively augment calcification processes. This study investigated the role of the IL-6 family member leukemia inhibitory factor (LIF) during vascular calcification. Method Experiments were performed in primary human aortic VSMCs, ex vivo mouse aortic rings and cholecalciferol treated mice, as well as serum samples from CKD patients and healthy controls. Results Phosphate exposure induced LIF release in VSMCs, while supplementation of LIF aggravated calcification and expression of pro-calcific markers in VSMCs. Silencing of LIF or addition of soluble LIF receptor (LIFR) as putative LIF antagonist ameliorated the pro-calcific effects of phosphate. Similarly, effects of phosphate or LIF were blunted by silencing of LIFR or its coreceptor GP130 in VSMCs. Mechanistically, LIF induced phosphorylation of TYK2, which was required for STAT1/3 activation. TYK2 overexpression augmented VSMC calcification, while silencing of either TYK2 or STAT1/3 ameliorated phosphate- and LIF-induced expression of pro-calcific markers. Pharmacological inhibition of TYK2 ameliorated calcification in VSMCs, mouse aortic rings and mice after cholecalciferol treatment. Furthermore, calcification was ameliorated in TYK2-deficient mouse aortic rings and mice after cholecalciferol overload. In a pilot study, LIFR was reduced in serum from patients with CKD and LIFR levels were associated with serum calcification propensity. Conclusion Vascular calcification is augmented by LIF, which identifies a crucial role of TYK2 in the pro-calcific reprogramming of VSMCs. Inhibition of this signalling axis might be able to reduce the burden of vascular calcification in CKD.

Vascular calcification in CKD: New insights into its mechanisms.

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

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

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

Serum sclerostin in vascular calcification in CKD: a meta-analysis

Vascular calcification (VC) is recognized as a predictor of all-cause and CVD mortality in chronic kidney disease (CKD). VC in CKD is possibly associated with serum sclerostin. The study systematically investigated the role of serum sclerostin in VC in CKD. Following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols, a systematic search was performed of the PubMed, Cochrane Library, and EMBASE databases from inception to 11 November 2022, to identify relevant eligible studies. The data were retrieved, analyzed, and summarized. The hazard ratios (HRs) and odds ratios (ORs) with their corresponding confidence intervals (CIs) were derived and pooled. Thirteen reports (3125 patients) met the inclusion criteria and were included. Sclerostin was associated with the presence of VC (pooled OR = 2.75, 95%CI = 1.81–4.19, p < 0.01) and all-cause mortality (pooled HR = 1.22, 95%CI = 1.19–1.25, p < 0.01) among patients with CKD, but with a decreased risk of cardiovascular events (HR = 0.98, 95%CI = 0.97–1.00, p = 0.02). This meta-analysis suggests that serum sclerostin is associated with VC and all-cause mortality among patients with CKD.

Implications of Senescent Cell Burden and NRF2 Pathway in Uremic Calcification: A Translational Study.

Increased senescent cell burden and dysregulation of the nuclear factor erythroid 2-related factor 2 (NRF2) pathway have been associated with numerous age-related pathologies; however, their role in promoting vascular calcification (VC) in chronic kidney disease (CKD) has yet to be determined. We investigated whether senescence and NRF2 pathways may serve as drivers of uremia-induced VC using three complementary approaches: a novel model of induced VC in 5/6-nephrectomized rats supplemented with high phosphate and vitamin D; epigastric arteries from CKD patients with established medial calcification; and vascular smooth muscle cells (VSMCs) incubated with uremic serum. Expression of p16Ink4a and p21Cip1, as well as γ-H2A-positive cells, confirmed increased senescent cell burden at the site of calcium deposits in aortic sections in rats, and was similarly observed in calcified epigastric arteries from CKD patients through increased p16Ink4a expression. However, uremic serum-induced VSMC calcification was not accompanied by senescence. Expression of NRF2 and downstream genes, Nqo1 and Sod1, was associated with calcification in uremic rats, while no difference was observed between calcified and non-calcified EAs. Conversely, in vitro uremic serum-driven VC was associated with depleted NRF2 expression. Together, our data strengthen the importance of senescence and NRF2 pathways as potential therapeutic options to combat VC in CKD.

Therapeutic Clinical Implications of Crosstalk amongst Gut Microbiota, Bone Health and Vascular Calcification in Chronic Kidney Disease: A Narrative Review

Earlier we had reviewed the part of epigenetic modifications in Diabetic Kidney Disease (DKD), other etiological factors in Chronic Kidney Disease (CKD) besides role of bilirubin in DKD, role of probiotics and prebiotics in obesity, T2DM, NAFLD. Here our objective was to evaluate the part of gut microbiota (GM), bone health and vascular calcification in CKD in this Narrative Review’. Decontrolling of GM might possess part in vascular along with bone disease in case of CKD randomized trial particular. With the reduction in glomerular filtration rate (GFR), escalated production of urea as well as uric acid ensues along with bacterial proteolytic fermentation changes the gut microbiome balance. Diets possessing lesser quantities of fibers along with utilization of medicines like Vitamin K antagonists as well as phosphate binders, iron delivery, antibiotics further aid in alterations in GM diversity in case of CKD patients. Simultaneously both bone disease along with vascular disease usually accompany CKD. Thus here we concentrate on gut dysbiosis, vascular calcification bone demineralization in addition to their interdependence namely the Gut- vascular -bone-axis in CKD is getting validated with greater proof. The part of diet metabolites of gut microbial origin like p-cresyl sulfate, Indoxyl sulfate, Trimethylamine-N-oxide(TMAO), short chain fatty acids(SCFA) Vitamin K deficiency, inflammatory cytokines expression are detailed. This interdependence might open up innovative avenues regarding treatment as well as avoidance for enhancement of cardiovascular along with bone health. Various studies are trying to find the appropriate utilization of various Probiotics as well as Prebiotics supplementation without escalation of inimical actions.

Vascular calcification in chronic kidney disease: contribution of ferroptosis?

Vascular calcification associated with chronic kidney disease (CKD) is an active, regulated process. Apoptosis of vascular smooth muscle cells has long been known to play a major role in its pathogenesis, with apoptotic bodies derived from these cells acting as nucleating structures for calcium crystal formation and deposition. Ye etal. now show in experimental models invitro and invivo that ferroptosis can also contribute to the development of vascular calcification in CKD.

Intermedin Alleviates Vascular Calcification in CKD through Sirtuin 3-Mediated Inhibition of Mitochondrial Oxidative Stress.

Vascular calcification (VC) is a common pathophysiological process of chronic kidney disease (CKD). Sirtuin 3 (Sirt3), a major NAD+-dependent protein deacetylase predominantly in mitochondria, is involved in the pathogenesis of VC. We previously reported that intermedin (IMD) could protect against VC. In this study, we investigated whether IMD attenuates VC by Sirt3-mediated inhibition of mitochondrial oxidative stress. A rat VC with CKD model was induced by the 5/6 nephrectomy plus vitamin D3. Vascular smooth muscle cell (VSMC) calcification was induced by CaCl2 and β-glycerophosphate. IMD1-53 treatment attenuated VC in vitro and in vivo, rescued the depressed mitochondrial membrane potential (MMP) level and decreased mitochondrial ROS levels in calcified VSMCs. IMD1-53 treatment recovered the reduced protein level of Sirt3 in calcified rat aortas and VSMCs. Inhibition of VSMC calcification by IMD1-53 disappeared when the cells were Sirt3 absent or pretreated with the Sirt3 inhibitor 3-TYP. Furthermore, 3-TYP pretreatment blocked IMD1-53-mediated restoration of the MMP level and inhibition of mitochondrial oxidative stress in calcified VSMCs. The attenuation of VSMC calcification by IMD1-53 through upregulation of Sirt3 might be achieved through activation of the IMD receptor and post-receptor signaling pathway AMPK, as indicated by pretreatment with an IMD receptor antagonist or AMPK inhibitor blocking the inhibition of VSMC calcification and upregulation of Sirt3 by IMD1-53. AMPK inhibitor treatment reversed the effects of IMD1-53 on restoring the MMP level and inhibiting mitochondrial oxidative stress in calcified VSMCs. In conclusion, IMD attenuates VC by improving mitochondrial function and inhibiting mitochondrial oxidative stress through upregulating Sirt3.