Vascular Calcification In Diabetes Research Articles

Similarities and Differences of Vascular Calcification in Diabetes and Chronic Kidney Disease.

Presently, the mechanism of occurrence and development of vascular calcification (VC) is not fully understood; a range of evidence suggests a positive association between diabetes mellitus (DM) and VC. Furthermore, the increasing burden of central vascular disease in patients with chronic kidney disease (CKD) may be due, at least in part, to VC. In this review, we will review recent advances in the mechanisms of VC in the context of CKD and diabetes. The study further unveiled that VC is induced through the stimulation of pro-inflammatory factors, which in turn impairs endothelial function and triggers similar mechanisms in both disease contexts. Notably, hyperglycemia was identified as the distinctive mechanism driving calcification in DM. Conversely, in CKD, calcification is facilitated by mechanisms including mineral metabolism imbalance and the presence of uremic toxins. Additionally, we underscore the significance of investigating vascular alterations and newly identified molecular pathways as potential avenues for therapeutic intervention.

Efficacy and mechanism of Shenqi Compound in inhibiting diabetic vascular calcification

BackgroundShenqi Compound (SQC) has been used in clinic for several decades in the prevention and treatment of diabetes and its complications. But this is merely a heritage of experience. The primary aim of this study is to scientifically validate the therapeutic effects of SQC on diabetic vascular calcification (DVC) in an animal model and, simultaneously, uncover its potential underlying mechanisms.MethodSpontaneous diabetic rat- Goto Kakizaki (GK) rats were selected for rat modeling. We meticulously designed three distinct groups: a control group, a model group, and an SQC treatment group to rigorously evaluate the influence of SQC. Utilizing a comprehensive approach that encompassed methods such as pathological staining, western blot analysis, qRT-PCR, and RNA sequencing, we thoroughly investigated the therapeutic advantages and the underlying mechanistic pathways associated with SQC in the treatment of DVC.ResultThe findings from this investigation have unveiled the extraordinary efficacy of SQC treatment in significantly mitigating DVC. The underlying mechanisms driving this effect encompass multifaceted facets, including the restoration of aberrant glucose and lipid metabolism, the prevention of phenotypic transformation of vascular smooth muscle cells (VSMCs) into osteogenic-like states, the subsequent inhibition of cell apoptosis, the modulation of inflammation responses, the remodeling of the extracellular matrix (ECM), and the activation of the Hippo-YAP signaling pathway. Collectively, these mechanisms lead to the dissolution of deposited calcium salts, ultimately achieving the desired inhibition of DVC.ConclusionOur study has provided compelling and robust evidence of the remarkable efficacy of SQC treatment in significantly reducing DVC. This reduction is attributed to a multifaceted interplay of mechanisms, each playing a crucial role in the observed therapeutic effects. Notably, our findings illuminate prospective directions for further research and potential clinical applications in the field of cardiovascular health.Graphical

Intermedin alleviates diabetic vascular calcification by inhibiting GLUT1 through activation of the cAMP/PKA signaling pathway

Background and aimsVascular calcification (VC) is regarded as an independent risk factor for cardiovascular events in type 2 diabetic patients. Glucose transporter 1 (GLUT1) involves VC. Intermedin/Adrenomedullin-2 (IMD/ADM2) is a cardiovascular protective peptide that can inhibit multiple disease-associated VC. However, the role and mechanism of IMD in diabetic VC remain unclear. Here, we investigated whether IMD inhibits diabetic VC by inhibiting GLUT1. Methods and resultsIt was found that plasma IMD concentration was significantly decreased in type 2 diabetic patients and in fructose-induced diabetic rats compared with that in controls. Plasma IMD content was inversely correlated with fasting blood glucose level and VC severity. IMD alleviated VC in fructose-induced diabetic rats. Deficiency of Adm2 aggravated and Adm2 overexpression attenuated VC in high-fat diet-induced diabetic mice. In vitro, IMD mitigated high glucose-induced calcification of vascular smooth muscle cells (VSMCs). Mechanistically, IMD reduced advanced glycation end products (AGEs) content and the level of receptor for AGEs (RAGE). IMD decreased glucose transporter 1 (GLUT1) levels. The inhibitory effect of IMD on RAGE protein level was blocked by GLUT1 knockdown. GLUT1 knockdown abolished the effect of IMD on alleviating VSMC calcification. IMD receptor antagonist IMD17-47 and cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) inhibitor H89 abolished the inhibitory effects of IMD on GLUT1 and VSMC calcification. ConclusionsThese findings revealed that IMD exerted its anti-calcification effect by inhibiting GLUT1, providing a novel therapeutic target for diabetic VC.

Intermedin alleviates diabetic vascular calcification by inhibiting GLUT1 through activating the cAMP/PKA signaling pathway

Intermedin alleviates diabetic vascular calcification by inhibiting GLUT1 through activating the cAMP/PKA signaling pathway

A novel protective role of lipoxin in inhibiting diabetic vascular calcification via YAP signalling: Health prevention and regulation

Vascular calcification is highly prevalent in diabetes patients, with detrimental consequences and no effective prevention and treatment strategies are currently available. Though the protective effect of lipoxin (LX) against vascular diseases has been demonstrated, its effect on diabetic vascular calcification remains unknown. AGEs dose-dependently induced calcification and the expression of osteogenesis-related markers, coupled with the activation of yes-associated protein (YAP). Mechanistically, YAP activation enhanced the AGE-induced osteogenic phenotype and calcification, but inhibition of YAP signalling alleviated this response. Further, an in vivo diabetic mouse model was established using a combination of a high-fat diet and multiple formulations of low-dose streptozotocin. Consistent with the in vitro results, diabetes promoted YAP expression and its subcellular localization in the nucleus in the arterial tunica media. The results demonstrate that LX attenuates the trans-differentiation and calcification of VSMCs in diabetes mellitus via YAP signalling, suggesting LX to be a potent therapeutic for preventing diabetic vascular calcification.

Impaired intracellular calcium homeostasis enhances protein O-GlcNAcylation and promotes vascular calcification and stiffness in diabetes

Vascular calcification is accelerated in patients with diabetes mellitus and increases risk of cardiovascular events and mortality. Vascular smooth muscle cells (VSMC) play a key role in regulating vascular tone and contribute significantly to the development of diabetic vasculopathy. In this study, the function of stromal interaction molecule 1 (STIM1), an important regulator for intracellular calcium homeostasis, in diabetic vascular calcification was investigated, and the underlying molecular mechanisms were uncovered.A SMC-specific STIM1 deletion mouse model (STIM1Δ/Δ) was generated by breeding the STIM1 floxed mice (STIM1f/f) with SM22α-Cre transgenic mice. Using aortic arteries from the STIM1Δ/Δ mice and their STIM1f/f littermates, we found that SMC-specific STIM1 deletion induced calcification of aortic arteries cultured in osteogenic media ex vivo. Furthermore, STIM1 deficiency promoted osteogenic differentiation and calcification of VSMC from the STIM1Δ/Δ mice. In the low-dose streptozotocin (STZ)-induced mouse model of diabetes, SMC-specific STIM1 deletion markedly enhanced STZ-induced vascular calcification and stiffness in the STIM1Δ/Δ mice. The diabetic mice with SMC-specific STIM1 ablation also exhibited increased aortic expression of the key osteogenic transcription factor, Runx2, and protein O-GlcNAcylation, an important post-translational modulation that we have reported to promote vascular calcification and stiffness in diabetes. Consistently, elevation of O-GlcNAcylation was demonstrated in aortic arteries and VSMC from the STIM1Δ/Δ mice. Inhibition of O-GlcNAcylation with a pharmacological inhibitor abolished STIM1 deficiency-induced VSMC calcification, supporting a critical role of O-GlcNAcylation in mediating STIM1 deficiency-induced VSMC calcification. Mechanistically, we identified that STIM1 deficiency resulted in impaired calcium homeostasis, which activated calcium signaling and increased endoplasmic reticulum (ER) stress in VSMC, while inhibition of ER stress attenuated STIM1-induced elevation of protein O-GlcNAcylation.In conclusion, the study has demonstrated a causative role of SMC-expressed STIM1 in regulating vascular calcification and stiffness in diabetes. We have further identified a novel mechanisms underlying STIM1 deficiency-induced impairment of calcium homeostasis and ER stress in upregulation of protein O-GlcNAcylation in VSMC, which promotes VSMC osteogenic differentiation and calcification in diabetes.

Abstract 2093: Protein O-GlcNAcylation is Important for Vascular Calcification in Diabetes

Abstract 2093: Protein O-GlcNAcylation is Important for Vascular Calcification in Diabetes

BMF-AS1/BMF Promotes Diabetic Vascular Calcification and Aging both In Vitro and In Vivo.

Vascular calcification and aging often increase morbidity and mortality in patients with diabetes mellitus (DM); however, the underlying mechanisms are still unknown. In the present study, we found that Bcl-2 modifying factor (BMF) and BMF antisense RNA 1 (BMF-AS1) were significantly increased in high glucose-induced calcified and senescent vascular smooth muscle cells (VSMCs) as well as artery tissues from diabetic mice. Inhibition of BMF-AS1 and BMF reduced the calcification and senescence of VSMCs, whereas overexpression of BMF-AS1 and BMF generates the opposite results. Mechanistic analysis showed that BMF-AS1 interacted with BMF directly and up-regulated BMF at both mRNA and protein levels, but BMF did not affect the expression of BMF-AS1. Moreover, knocking down BMF-AS1 and BMF suppressed the calcification and senescence of VSMCs, and BMF knockout (BMF-/-) diabetic mice presented less vascular calcification and aging compared with wild type diabetic mice. In addition, higher coronary artery calcification scores (CACs) and increased plasma BMF concentration were found in patients with DM, and there was a positive correlation between CACs and plasma BMF concentration. Thus, BMF-AS1/BMF plays a key role in promoting high glucose-induced vascular calcification and aging both in vitro and in vivo. BMF-AS1 and BMF represent potential therapeutic targets in diabetic vascular calcification and aging.

Abstract 15322: O-glcnac Modification on Runx2 Promotes Vascular Calcification

Vascular calcification is prevalent in patients with diabetes mellitus and well documented in animal models of diabetes. We have previously reported that vascular calcification in diabetes is associated with elevated vascular protein O -linked GlcNAc modification ( O -GlcNAcylation). The present studies sought to determine a causative link of O -GlcNAcylation with diabetic vascular calcification and the underlying molecular mechanisms. Using coronary arteries from diabetic subjects, we identified increased O -GlcNAcylation in the highly calcified lesions compared to those in the surrounding uncalcified areas. By generating a new mouse model with inducible SMC-specific deletion of the O -GlcNAc transferase (OGT), we demonstrated that smooth muscle cell (SMC)-specific OGT deletion significantly inhibited protein O -GlcNAcylation and calcification, and decreased aortic stiffness in the low-dose streptozotocin-induced diabetic mice. Consistent with the observations in human tissues, inhibition of vascular calcification by OGT ablation was associated with down-regulation of Runx2, the essential osteogenic regulator for vascular calcification. OGT deficiency in VSMC further attenuated Runx2-induced VSMC calcification. Immunoprecipitation analysis uncovered a direct O-GlcNAc modification on Runx2, which was abolished in the OGT-deficient VSMC. With a serial of Runx2 truncation mutants and point mutations on putative O -GlcNAcylation sites, we localized the essential Runx2 osteogenic functional domain between amino acids 391 and 432, and identified Runx2 T412 was responsible for Runx2 O -GlcNAcylation and Runx2-induced VSMC calcification. Inhibition of Runx2 O -GlcNAcylation by T412A mutation decreased Runx2 transcription activity and inhibited Runx2 binding with its key co-factors. Taken together, our studies have provided the first genetic proof demonstrating the causative effects of O -GlcNAcylation on vascular calcification in diabetes, and identified a novel mechanism underlying the essential role of O -GlcNAcylation of Runx2 in Runx2 osteogenic activity and Runx2-induced VSMC calcification. These results may shed lights on novel targets that are amenable to drug discovery for diabetic vascular calcification.

Nε-Carboxymethyl-Lysine Mediates Vascular Calcification in Diabetes Caused by Impaired Osteoclastic Resorption Activity Through NFATc1-GNPTAB.

Nε-carboxymethyl-lysine (CML) is closely associated with vascular calcification in diabetes. Osteoclasts are the only cells with bone resorption activity that have the potential to reverse calcification. This study aimed to investigate the mechanism of CML in the bone resorption activity of macrophage-derived osteoclasts in diabetic calcified plaques. Macrophage-derived osteoclasts were found to be present in calcified plaques of the anterior tibial artery in patients with diabetic amputation. Furthermore, in vitro studies showed that CML induced the differentiation of macrophages into osteoclasts, although, the bone resorption activity of these macrophage-derived osteoclasts was impaired. CML significantly increased the levels of NFATc1and GNPTAB. In vivo studies showed that there was more calcium deposition and less TRAP was less in the CML group while this effect was reversed after silencing of NFATc1. In conclusion, CML mediates NFATc1-GNPTAB to regulate bone resorption activity of osteoclasts in diabetic calcified plaques. CML promotes macrophage differentiation into osteoclasts, but their function is impaired in diabetic calcified plaques through NFATc1-GNPTAB, which eventually leads to the further progression of vascular calcification in diabetes.

Protective role of small extracellular vesicles derived from HUVECs treated with AGEs in diabetic vascular calcification

The pathogenesis of vascular calcification in diabetic patients remains elusive. As an effective information transmitter, small extracellular vesicles (sEVs) carry abundant microRNAs (miRNAs) that regulate the physiological and pathological states of recipient cells. In the present study, significant up-regulation of miR-126-5p was observed in sEVs isolated from human umbilical vein endothelial cells (HUVECs) stimulated with advanced glycation end-products (A-EC/sEVs). Intriguingly, these sEVs suppressed the osteogenic differentiation of vascular smooth muscle cells (VSMCs) by targeting BMPR1B, which encodes the receptor for BMP, thereby blocking the smad1/5/9 signalling pathway. In addition, knocking down miR-126-5p in HUVECs significantly diminished the anti-calcification effect of A-EC/sEVs in a mouse model of type 2 diabetes. Overall, miR-126-5p is highly enriched in sEVs derived from AGEs stimulated HUVECs and can target BMPR1B to negatively regulate the trans-differentiation of VSMCs both in vitro and in vivo.Graphical

Abstract 315: Augmentation Of Protein O -glcnacylation By Impaired Intracellular Calcium Homeostasis Promoted Vascular Calcification

Vascular calcification is accelerated in patients with diabetes mellitus and increases risk of cardiovascular events and mortality. Wes have demonstrated elevated protein O -GlcNAcylation promotes vascular calcification in diabetes. Increased O -GlcNAcylation is linked to impaired calcium signaling, which is critical for the development of vascular calcification in both humans and animal models. The present studies determined the role of an important regulator for intracellular calcium homeostasis, the stromal interaction molecule 1 (STIM1), in regulating O -GlcNAcylation and vascular calcification. Deletion of STIM1 induced osteogenic differentiation and calcification of VSMC, which was associated with decreased expression of the SMC marker genes and increased expression of the key osteogenic transcription factor, Runx2. By generating a SMC-specific STIM1 ablation mouse model, we determined that STIM1 ablation induced vascular calcification in aortic rings cultured ex vivo and in diabetic mice injected with low-dose streptozotocin in vivo. The diabetic mide with SMC-specific STIM1 ablation also exhibited increased aortic Runx2 expression and aortic stiffness (pulse wave velocity). Mechanistically, we identified that STIM1 deficiency impaired calcium homeostasis in VSMC, increased activation of the Ca 2+ /calmodulin-dependent protein kinase II and elevation of protein O -GlcNAcylation. Increased O -GlcNAcylation by STIM1 deficiency was further demonstrated in aortic arteries from the SMC-specific STIM1 ablation mice. The essential role of O -GlcNAcylation in mediating STIM1 deficiency-induced VSMC calcification was determined using a specific inhibitor for the O -GlcNAc transferase (OGT), the enzyme adding O -GlcNAc onto proteins. Inhibition of OGT abolished STIM1 deficiency-induced elevation of O -GlcNAcylation and VSMC. In conclusion, our studies have demonstrated a causative effect of SMC-expressed STIM1 on vascular calcification and stiffness in diabetes. We have further identified a novel link connecting STIM1 deficiency-induced impairment of calcium homeostasis and elevation of protein O -GlcNAcylation in VSMC that promotes osteogenic differentiation and calcification of VSMC.

KLF2 mediates the suppressive effect of BDNF on diabetic intimal calcification by inhibiting HK1 induced endothelial-to-mesenchymal transition

Diabetic vascular calcification in the arterial intima is closely associated with endothelial-to-mesenchymal transition (EndMT). Glucose metabolism reprogramming is involved in EndMT. Although brain-derived neurotrophic factor (BDNF) and Krüppel-like family of transcription factor 2 (KLF2) play protective roles in the physiological activity of the vascular endothelium, the underlying mechanisms are unclear. Human umbilical vein endothelial cells (HUVECs) were incubated with diabetic osteogenic medium (DOM) to induce EndMT and accelerate osteogenic differentiation. Glycolysis in HUVECs was assessed by monitoring glucose uptake, lactate production, extracellular acidification rate and expression of key glycolytic enzymes. DOM induced EndMT and accelerated osteo-induction in HUVECs, which was alleviated by BDNF/tropomyosin receptor kinase B (TrkB) pathway. Mechanistically, DOM caused hyperactivation of glycolysis in HUVECs and inhibition of the BDNF/TrkB pathway. BDNF preserved KLF2 and downregulated hexokinase 1 (HK1) in HUVECs after DOM treatment. Furthermore, KLF2 interacted with HK1. Increased KLF2 alleviated HK1-mediated glucose metabolism abnormality. HK1 knockdown or a targeted glycolysis inhibitor suppressed EndMT, apoptosis, inflammation and vascular calcification of HUVECs after DOM exposure. This study suggests that KLF2 mediates the suppressive effect of BDNF on diabetic intimal calcification by inhibiting HK1-induced glucose metabolism reprogramming and the EndMT process.

Abstract MP48: Smooth Muscle Cell-Specific Deletion Of O-GlcNAc Transferase Impedes Atherosclerotic Lesion Formation In Western Diet-fed Apoe -/- Mice

Attachment of O-linked N-acetylglucosamine (O-GlcNAc) to nucleocytoplasmic proteins or ‘O-GlcNAcylation’ is a ubiquitous post-translational modification affecting numerous cellular processes. We and others have previously reported that augmented protein O-GlcNAcylation mediates upregulation of numerous genes associated with atherosclerosis. Recent studies suggest the role of O-GlcNAc transferase (OGT), a key regulator of O-GlcNAc signaling, in diabetic vascular calcification and wound healing. However, the role of OGT in the etiology of atherosclerosis is elusive. The goal of the current study was to interrogate whether OGT plays a direct role in the development of atherosclerosis. For this, we crossed tamoxifen-inducible male Myh11-CreERT2;OGT fl/y ;ApoE -/- mice with female OGT fl/+ ;ApoE -/- to generate SMC-specific OGT knockout on ApoE -/- background. To induce Cre recombinase activity, mice genotypes were injected i.p. with 60mg/Kg/day tamoxifen (peanut oil-vehicle control) once daily for 5 consecutive days beginning at 6 wks age. This was followed by a Western diet feeding regimen for additional 6-7 wks. Mice were harvested at 14 wks age after overnight fasting; plasma, aorta, and heart were collected for biochemical, molecular, and lesion studies. Immunoblotting confirmed loss of OGT expression in aortic vessels of tamoxifen-treated Cre tg ;OGT fl/y ;ApoE -/- mice (smOGT KO ;ApoE -/- ) vs. age-matched tamoxifen-treated Cre tg ;OGT +/y ;ApoE -/- littermates (smOGT WT ;ApoE -/- , with intact OGT). Aortic root morphometry revealed a significant reduction (2.5-fold) in lesion lipid burden in smOGT KO ;ApoE -/- mice compared with smOGT WT ;ApoE -/- . This was accompanied by attenuated PCNA (proliferation marker), osteopontin (SM synthetic marker), pERK (SM signaling regulator), YY1 (transcriptional repressor of SM contractile genes), and SRF (transcriptional regulator of SMC proliferation) expression in smOGT KO ;ApoE -/- vs. smOGT WT ;ApoE -/- aortic lysates, shown via immunoblotting. Interestingly, SMC-specific OGT deletion had no effect on plasma total cholesterol and total triglyceride levels. Taken together, these results demonstrate a protective role of SMC-specific loss of OGT on atherosclerotic lesion formation.

POSTN promotes diabetic vascular calcification by interfering with autophagic flux

Autophagy is a lysosomal degradative process that is closely related to the pathogenesis of vascular calcification. Recent evidence suggests that periostin (POSTN) is a unique extracellular matrix protein that is associated with diabetic vascular complications. The aim of current study is to investigate the role of POSTN in diabetic vascular calcification and the underlying mechanisms. Results showed that POSTN was highly upregulated in both calcified arteries of diabetic rats and AGEs-BSA mediated vascular smooth muscle cell (VSMC) calcification. POSTN blocked autophagic flux during the diabetic calcification process, as evidenced by increased protein expression of Beclin1, LC3-II, and P62, as well as the co-localization of LC3-II and LAMP1. Inhibition of POSTN alleviated AGEs-BSA-induced autophagic flux blockade, thereby attenuating AGEs-BSA-induced VSMC calcification. Mechanistically, the upregulation of POSTN impaired the fusion of autophagosomes and lysosome and resulted in the autophagic flux blockade in AGEs-BSA-treated VSMC. Furthermore, this autophagic blockade was intracellular ROS-dependent. In summary, this study uncovered a novel mechanism of POSTN in autophagy regulation of diabetic vascular calcification.

<p>Role of Sortilin and Matrix Vesicles in Nϵ-Carboxymethyl-Lysine-Induced Diabetic Atherosclerotic Calcification</p>

Background and AimsTo investigate the role of Sortilin and matrix vesicles (MVs) in Nε-Carboxymethyl-lysine (CML)-induced diabetic atherosclerotic calcification (AC).MethodsAt human level, the correlation between Sortilin and CD9 (marker proteins of MVs) in serum MVs and CML in serum was explored by enzyme-linked immunosorbent assay (ELISA) detection and Pearson correlation analysis. After a diabetic apoE-/- mouse model was constructed, the calcification of aorta and the expressions of related proteins under CML and MVs injection were observed by calcification staining, immunofluorescence staining, and Western blot. MVs levels released by smooth muscle cells (SMCs) under different treatments was detected by nanometer tracking analysis (NTA). After treating SMCs with MVs and Anti-Sortilin, cell calcification was observed by Alizarin red staining.ResultsSerological analysis of patients showed that the concentrations of Sortilin and CD9 in serum MVs were positively correlated with the concentration of CML in serum. Animal experiments showed that CML could promote the progression of diabetic AC and the high expression of Sortilin in plaques. Diabetic apoE-/- mouse tail vein injection of CML-induced SMCs-derived MVs obviously aggravated AC. Cell experiment results showed that a high concentration of CML significantly promoted the release of MVs from SMCs. MVs from this source could markedly worsen cell calcification, while the administration of GW4869 (a widely used extracellular vesicles biogenesis inhibitor) significantly reduced cell calcification. Finally, treatment of high concentrations of CML could also promote the recruitment of Sortilin to MVs, and administration of Anti-Sortilin could markedly reduce cell calcification caused by MVs.ConclusionWe proved that CML not only affects the release of MVs from SMCs but also affects the recruitment of Sortilin to MVs, thereby promoting diabetic AC. This discovery may provide a new strategy for targeted prevention of vascular calcification in diabetes.

Role of the Scavenger Receptor CD36 in Accelerated Diabetic Atherosclerosis.

Diabetes mellitus entails increased atherosclerotic burden and medial arterial calcification, but the precise mechanisms are not fully elucidated. We aimed to investigate the implication of CD36 in inflammation and calcification processes orchestrated by vascular smooth muscle cells (VSMCs) under hyperglycemic and atherogenic conditions. We examined the expression of CD36, pro-inflammatory cytokines, endoplasmic reticulum (ER) stress markers, and mineralization-regulating enzymes by RT-PCR in human VSMCs, cultured in a medium containing normal (5 mM) or high glucose (22 mM) for 72 h with or without oxidized low-density lipoprotein (oxLDL) (24 h). The uptake of 1,1′-dioctadecyl-3,3,3′,3-tetramethylindocarbocyanine perchlorate-fluorescently (DiI) labeled oxLDL was quantified by flow cytometry and fluorimetry and calcification assays were performed in VSMC cultured in osteogenic medium and stained by alizarin red. We observed induction in the expression of CD36, cytokines, calcification markers, and ER stress markers under high glucose that was exacerbated by oxLDL. These results were confirmed in carotid plaques from subjects with diabetes versus non-diabetic subjects. Accordingly, the uptake of DiI-labeled oxLDL was increased after exposure to high glucose. The silencing of CD36 reduced the induction of CD36 and the expression of calcification enzymes and mineralization of VSMC. Our results indicate that CD36 signaling is partially involved in hyperglycemia and oxLDL-induced vascular calcification in diabetes.

Enhanced Vascular Calcification and Stiffness in Diabetic Mice with SMC‐specific STIM1 deficiency

Vasculopathy is a devastating complication in patients with diabetes mellitus, which increases the risk of morbidity and mortality. Vascular smooth muscle cells (VSMC) are the main vascular cells that regulate vascular tone and contribute predominantly to the development of vasculopathy. We have demonstrated an important role of VSMC in the development of vascular calcification and stiffness in diabetes. The present study investigated the function of stromal interaction molecule 1 (STIM1), an important regulator for intracellular calcium homeostasis, in regulating VSMC calcification in mouse model of diabetes, and uncovered the underlying molecular mechanisms.The effect of SMC‐expressed STIM1 in regulating vascular function in diabetes was determined in a SMC‐specific STIM1‐deficient mouse (STIM1Δ/Δ SMC), generated by breeding SM22α‐Cre mice with STIM1 floxed mice (STIM1f/f). SMC‐specific deletion in the STIM1Δ/Δ SMC mice was confirmed by immunohistochemical staining. Using the low‐dose streptozotocin (STZ)‐induced mouse model of diabetes, we found that SMC‐specific STIM1 deletion did not affect STZ‐induced hyperglycemia in mice. STZ‐induced vascular calcification and stiffness were enhanced in SMC‐specific STIM1 deficient mice comparing with their control littermates (STIM1f/f), which was associated with increased aortic expression of Runx2, the master osteogenic regulator. Furthermore, aortas from the STIM1Δ/Δ SMC mice exhibited increased protein O‐GlcNAcylation, an important post‐translational modulation that we have shown to promote vascular calcification and stiffness. Increased protein O‐GlcNAcylation was also determined in primary VSMC isolated from STIM1Δ/Δ SMC mice compared with those form the control littermates. STIM1 deficiency in VSMC promoted osteogenic differentiation and calcification of VSMC cultured in osteogenic media, which was attenuation by inhibition of protein O‐GlcNAcylation. Osteogenic media‐induced elevation of intracellular calcium flux was demonstrated in the STIM1 deficiency VSMC, which induced endoplasmic reticulum stress and activation of p38 MAPK pathway that contributed to increased O‐GlcNAcylation and VSMC calcification.In summary, our studies have determined a new causative effect of SMC‐expressed STIM1 on diabetic vascular calcification and stiffness, and identified a novel link connecting STIM1 and protein O‐GlcNAcylation in regulating endoplasmic reticulum stress and VSMC calcification.

Macrophage galectin-3 enhances intimal translocation of vascular calcification in diabetes mellitus.

The clinical risks and prognosis of diabetic vascular intimal calcification (VIC) and medial calcification (VMC) are different. This study aims to investigate the mechanism of VIC/VMC translocation. Anterior tibial arteries were collected from patients with diabetic foot amputation. The patients were then divided into VIC and VMC groups. There were plaques in all anterior tibial arteries, while the enrichment of galectin-3 in arterial plaques in the VIC group was significantly higher than that in the VMC group. Furthermore, a macrophage/vascular smooth muscle cell (VSMC) coculture system was constructed. VSMC-derived extracellular vesicles (EVs) was labeled with fluorescent probe. After macrophages were pretreated with recombinant galectin-3 protein, the migration of VSMC-derived EVs and VSMC-derived calcification was more pronounced. And anti-galectin-3 antibody can inhibit this process of EVs and calcification translocation. Then, lentivirus (LV)-treated bone marrow cells (BMCs) were transplanted into apolipoprotein E-deficient (ApoE-/-) mice, and a diabetic atherosclerosis mouse model was constructed. After 15 wk of high-fat diet, ApoE-/- mice transplanted with LV-shgalectin-3 BMCs exhibited medial calcification and a concentrated distribution of EVs in the media. In conclusion, upregulation of galectin-3 in macrophages promotes the migration of VSMC-derived EVs to the intima and induces diabetic vascular intimal calcification.NEW & NOTEWORTHY The clinical risk and prognosis of vascular intimal and medial calcification are different. Macrophage galectin-3 regulates the migration of vascular smooth muscle cell-derived extracellular vesicles and mediates diabetic vascular intimal/medial calcification translocation. This study may provide insights into the early intervention in diabetic vascular calcification.

Reticulocalbin 2 enhances osteogenic differentiation of human vascular smooth muscle cells in diabetic conditions

AimDiabetes accelerates pro-atherogenic and pro-osteogenic phenotypes of vascular smooth muscle cells (VSMCs), an important process for vascular calcification. Reticulocalbin 2 (RCN2) is a candidate gene for atherosclerosis and involved in vascular remodeling in hypertension. However, the role of RCN2 in VSMCs calcification under diabetic conditions is unclear. Materials and methodsExpression of RCN2 and Runt-related transcription factor 2 (Runx2) in femoropopliteal arterial plaques was compared between type 2 diabetes mellitus (DM) and non-DM patients using immunohistochemical staining (IHCS). Human aortic VSMCs (HAVSMCs) were analyzed under RCN2 gene knockdown and overexpression conditions. Alizarin red staining and intracellular calcium deposition quantification were used to observe calcification induced in vitro under normal glucose or high glucose combined with β-glycerol phosphoric acid conditions. The cells were investigated for gene modulation of osteogenic differentiation markers using Western blotting. Key findingsThe expression of RCN2 and Runx2 in femoropopliteal artery plaques was significantly higher in DM than in non-DM patients. In addition, a significant positive correlation was observed between RCN2 and Runx2 levels. RCN2 was highly expressed when HAVSMCs were treated with high glucose and the expression levels correlated with the calcification characteristics. RCN2 upregulated osteogenic transformation markers Runx2 and Osterix in HAVSMCs and downregulated contractile phenotype markers α-SMA and SM22α. SignificanceThe results from this study indicate RCN2 is a major factor in mediating the calcification process of HAVSMCs in diabetic conditions. Thus, RCN2 may serve as a future therapeutic target for vascular calcification in diabetes.