Activation of vascular bone morphogenetic protein signaling in diabetes mellitus

Predictive factors of thoracic aortic calcification in patients candidate for cardiac surgery

BACKGROUND

The presence of the severe thoracic aortic calcification (TAC) in cardiac surgery patients is associated with adverse post-operative outcome. However, the relationship between cardiovascular risk factors and aortic plaque burden remains unknown. The objective of this study was to determine the predictive factors of TAC in patients candidate for cardiac surgery.

METHODS

Patients who underwent thoracic CT scan prior to cardiac surgery between August 2020 to April 2021 were included. Of 556 patients, 209 (36.7%) had a thoracic aortic calcium score (TACS) ≥ 400 mm [3] and were compare with the remaining patients. Predictors of severe TAC were assessed through stepwise multivariable logistic regression analysis.

RESULTS

The patients with TACS ≥ 400 had a higher mean age (67.3 ± 7.1 vs. 55.7 ± 10.6; p < 0.001) with a higher frequency of diabetes mellitus (40.7% vs. 30.8%; p = 0.018), dyslipidemia (49.8% vs. 38.6%; p = 0.010), hypertension (60.8% vs. 44.7%; p < 0.001), opium addiction (18.2% vs. 11.2%; p = 0.023), peripheral vascular disease (PVD) (7.7% vs. 2.3%; p = 0.005) as compared with TACS < 400. The multiple determinants of TAC were PVD (OR = 2.86) followed by opium addiction, diabetes and age.

CONCLUSIONS

Thoracic CT scan prior to cardiac surgery for patients with older age, diabetes, opium addiction and PVD is recommended. Our study could serve as a foundation for future research endeavors aimed at establishing a risk score for TAC.

CDK1 inhibition reduces osteogenesis in endothelial cells in vascular calcification

Vascular calcification is a severe complication of cardiovascular diseases. Previous studies demonstrated that endothelial lineage cells transitioned into osteoblast-like cells and contributed to vascular calcification. Here, we found that inhibition of cyclin-dependent kinase (CDK) prevented endothelial lineage cells from transitioning to osteoblast-like cells and reduced vascular calcification. We identified a robust induction of CDK1 in endothelial cells (ECs) in calcified arteries and showed that EC-specific gene deletion of CDK1 decreased the calcification. We found that limiting CDK1 induced E-twenty-six specific sequence variant 2 (ETV2), which was responsible for blocking endothelial lineage cells from undergoing osteoblast differentiation. We also found that inhibition of CDK1 reduced vascular calcification in a diabetic mouse model. Together, the results highlight the importance of CDK1 suppression and suggest CDK1 inhibition as a potential option for treating vascular calcification.

Beyond the Basics: Unraveling the Complexity of Coronary Artery Calcification

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

Bile Acid Network and Vascular Calcification-Associated Diseases: Unraveling the Intricate Connections and Therapeutic Potential

Bile acids play a crucial role in promoting intestinal nutrient absorption and biliary cholesterol excretion, thereby protecting the liver from cholesterol accumulation and bile acid toxicity. Additionally, bile acids can bind to specific nuclear and membrane receptors to regulate energy expenditure and specific functions of particular tissues. Vascular calcification refers to the pathological process of calcium-phosphate deposition in blood vessel walls, which serves as an independent predictor for cardiovascular adverse events. In addition to aging, this pathological change is associated with aging-related diseases such as atherosclerosis, hypertension, chronic kidney disease, diabetes mellitus, and osteoporosis. Emerging evidence suggests a close association between the bile acid network and these aforementioned vascular calcification-associated conditions. Several bile acids have been proven to participate in calcium-phosphate metabolism, affecting the transdifferentiation of vascular smooth muscle cells and thus influencing vascular calcification. Targeting the bile acid network shows potential for ameliorating these diseases and their concomitant vascular calcification by regulating pathways such as energy metabolism, inflammatory response, oxidative stress, and cell differentiation. Here, we present a summary of the metabolism and functions of the bile acid network and aim to provide insights into the current research on the profound connections between the bile acid network and these vascular calcification-associated diseases, as well as the therapeutic potential.

A Supportive Role of Mesenchymal Stem Cells on Insulin-Producing Langerhans Islets with a Specific Emphasis on The Secretome

Type 1 Diabetes (T1D) is a chronic autoimmune disease characterized by a gradual destruction of insulin-producing β-cells in the endocrine pancreas due to innate and specific immune responses, leading to impaired glucose homeostasis. T1D patients usually require regular insulin injections after meals to maintain normal serum glucose levels. In severe cases, pancreas or Langerhans islet transplantation can assist in reaching a sufficient β-mass to normalize glucose homeostasis. The latter procedure is limited because of low donor availability, high islet loss, and immune rejection. There is still a need to develop new technologies to improve islet survival and implantation and to keep the islets functional. Mesenchymal stem cells (MSCs) are multipotent non-hematopoietic progenitor cells with high plasticity that can support human pancreatic islet function both in vitro and in vivo and islet co-transplantation with MSCs is more effective than islet transplantation alone in attenuating diabetes progression. The beneficial effect of MSCs on islet function is due to a combined effect on angiogenesis, suppression of immune responses, and secretion of growth factors essential for islet survival and function. In this review, various aspects of MSCs related to islet function and diabetes are described.

Beta cell dysfunction induced by bone morphogenetic protein (BMP)-2 is associated with histone modifications and decreased NeuroD1 chromatin binding

Insufficient insulin secretion is a hallmark of type 2 diabetes and has been attributed to beta cell identity loss characterized by decreased expression of several key beta cell genes. The pro-inflammatory factor BMP-2 is upregulated in islets of Langerhans from individuals with diabetes and acts as an inhibitor of beta cell function and proliferation. Exposure to BMP-2 induces expression of Id1-4, Hes-1, and Hey-1 which are transcriptional regulators associated with loss of differentiation. The aim of this study was to investigate the mechanism by which BMP-2 induces beta cell dysfunction and loss of cell maturity. Mouse islets exposed to BMP-2 for 10 days showed impaired glucose-stimulated insulin secretion and beta cell proliferation. BMP-2-induced beta cell dysfunction was associated with decreased expression of cell maturity and proliferation markers specific to the beta cell such as Ins1, Ucn3, and Ki67 and increased expression of Id1-4, Hes-1, and Hey-1. The top 30 most regulated proteins significantly correlated with corresponding mRNA expression. BMP-2-induced gene expression changes were associated with a predominant reduction in acetylation of H3K27 and a decrease in NeuroD1 chromatin binding activity. These results show that BMP-2 induces loss of beta cell maturity and suggest that remodeling of H3K27ac and decreased NeuroD1 DNA binding activity participate in the effect of BMP-2 on beta cell dysfunction.

Endothelial-to-mesenchymal transition: New insights into vascular calcification

With the continuous progress of atherosclerosis research, the significant pathological change of it--vascular calcification (VC), gains increasing attention. In recent years, numerous studies have demonstrated that it is an independent predictor of death risk of cardiovascular disease, and it has a strong correlation with poor clinical prognosis. As the world's population continues to age, the occurrence of VC is expected to reach its highest point in the near future. Therefore, it is essential to investigate ways to prevent or even reverse this process for clinical purposes. Endothelial-to-mesenchymal transition (EndMT) describes the progressive differentiation of endothelial cells into mesenchymal stem cells (MSCs) under various stimuli and acquisition of pluripotent cell characteristics. More and more studies show that EndMT plays a vital role in various cardiovascular diseases, including atherosclerosis, vascular calcification and heart valvular disease. EndMT is also involved in the formation and progression of VC. This review vividly describes the history, characteristics of EndMT and how it affects the endothelial cell process, then focuses on the relationship between vascular endothelium, EndMT, amino acid metabolism, and vascular calcification. Finally, it overviews the signal pathway of EndMT and drugs targeting EndMT, hoping to provide new ideas and a theoretical basis for studying potential therapeutic targets of VC.

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.

GSK3β Inhibition Reduced Vascular Calcification in Ins2Akita/+ Mice

Endothelial-mesenchymal transition (EndMT) drives the endothelium to contribute to vascular calcification in diabetes mellitus. In our previous study, we showed that glycogen synthase kinase-3β (GSK3β) inhibition induces β-catenin and reduces mothers against DPP homolog 1 (SMAD1) to direct osteoblast-like cells toward endothelial lineage, thereby reducing vascular calcification in Matrix Gla Protein (Mgp) deficiency. Here, we report that GSK3β inhibition reduces vascular calcification in diabetic Ins2^Akita/wt mice. Cell lineage tracing reveals that GSK3β inhibition redirects endothelial cell (EC)-derived osteoblast-like cells back to endothelial lineage in the diabetic endothelium of Ins2^Akita/wt mice. We also find that the alterations in β-catenin and SMAD1 by GSK3β inhibition in the aortic endothelium of diabetic Ins2^Akita/wt mice are similar to Mgp^-/- mice. Together, our results suggest that GSK3β inhibition reduces vascular calcification in diabetic arteries through a similar mechanism to that in Mgp^-/- mice.

Paracrine Signals in Calcified Conditioned Media Elicited Differential Responses in Primary Aortic Vascular Smooth Muscle Cells and in Adventitial Fibroblasts

Our goal was to determine if paracrine signals from different aortic layers can impact other cell types in the diabetic microenvironment, specifically medial vascular smooth muscle cells (VSMCs) and adventitial fibroblasts (AFBs). The diabetic hyperglycemic aorta undergoes mineral dysregulation, causing cells to be more responsive to chemical messengers eliciting vascular calcification. Advanced glycation end-products (AGEs)/AGE receptors (RAGEs) signaling has been implicated in diabetes-mediated vascular calcification. To elucidate responses shared between cell types, pre-conditioned calcified media from diabetic and non-diabetic VSMCs and AFBs were collected to treat cultured murine diabetic, non-diabetic, diabetic RAGE knockout (RKO), and non-diabetic RKO VSMCs and AFBs. Calcium assays, western blots, and semi-quantitative cytokine/chemokine profile kits were used to determine signaling responses. VSMCs responded to non-diabetic more than diabetic AFB calcified pre-conditioned media. AFB calcification was not significantly altered when VSMC pre-conditioned media was used. No significant changes in VSMCs signaling markers due to treatments were reported; however, genotypic differences existed. Losses in AFB α-smooth muscle actin were observed with diabetic pre-conditioned VSMC media treatment. Superoxide dismutase-2 (SOD-2) increased with non-diabetic calcified + AGE pre-conditioned VSMC media, while same treatment decreased diabetic AFBs levels. Overall, non-diabetic and diabetic pre-conditioned media elicited different responses from VSMCs and AFBs.

Growth hormone-releasing hormone agonist attenuates vascular calcification in diabetic db/db mice

Introduction

Vascular calcification (VC) is an independent risk factor for cardiovascular diseases. VC increases mortality of all-causes. VC is one of most common cardiovascular complications in type II diabetes. So far, no therapy has been proven to be effective in treatment of clinical VC. The present study investigated the therapeutic effects of MR409, an agonistic analog of growth hormone-releasing hormone (GHRH-A), on VC in diabetic db/db mice.

Method and result

Diabetic mice were injected with MR409 subcutaneously every day for 8 weeks. Long-term treatment with MR409 improved serum lipid profile and endothelium-dependent relaxation to acetylcholine, and reduced vascular structural injury in diabetic mice without affecting serum growth hormone level. Echocardiography showed that calcium plaques present in heart valve of diabetic mice disappeared in diabetic mice after treatment with MR409. MR409 inhibited vascular calcium deposition associated with a marked reduction in the expressions of osteogenic-regulated alkaline phosphatase (ALP) and transcription osteogenic marker gene Runx2 in diabetic mice. MR409 also inhibited vascular reactive oxygen species (ROS) generation and upregulated the expressions of anti-calcifying protein Klotho in diabetic mice.

Discussion

Our results demonstrate that GHRH-A MR409 can effectively attenuate VC and heart valve calcification, and protect against endothelial dysfunction and vascular injury in diabetic mice without significantly affecting pituitary-growth hormone axis. The mechanisms may involve upregulation of anti-calcifying protein Klotho and reduction in vascular ROS and the expression of redox sensitive osteogenic genes Runx2 and ALP. GHRH-A may represent a new pharmacological strategy for treatment of VC and diabetics associated cardiovascular complications.

Insights into bone morphogenetic proteins in cardiovascular diseases

Bone morphogenetic proteins (BMPs) are secretory proteins belonging to the transforming growth factor-β (TGF-β) superfamily. These proteins play important roles in embryogenesis, bone morphogenesis, blood vessel remodeling and the development of various organs. In recent years, as research has progressed, BMPs have been found to be closely related to cardiovascular diseases, especially atherosclerosis, vascular calcification, cardiac remodeling, pulmonary arterial hypertension (PAH) and hereditary hemorrhagic telangiectasia (HHT). In this review, we summarized the potential roles and related mechanisms of the BMP family in the cardiovascular system and focused on atherosclerosis and PAH.

Calcific Aortic Valve Stenosis with Aging and Current Development in its Pathophysiology

Aortic stenosis is the most common valvular heart disease affecting the elderly. While most patients have a prolonged asymptomatic phase, the development of symptoms ushers in a phase clinical deterioration that often leads to sudden death without an intervention. Treatment of aortic stenosis with valve replacement often relieves the symptoms but still leaves behind a remodeled left ventricle which may not recover. Understanding the pathophysiology of aortic stenosis and realizing that the disease process may be a more active biological entity rather than a passive degenerative process will help us prevent it. This review serves to summarize the latest literature on the pathophysiology of aortic stenosis in the elderly.

Cardiac valve calcification as a predictor of cardiovascular outcomes in peritoneal dialysis patients: an inverse probability of treatment weighting analysis

BACKGROUND

Cardiovascular events (CVE) are the leading cause of death in peritoneal dialysis (PD) patients. The predictive value of cardiac valve calcification (CVC) for CVE in dialysis patients remains controversial. In particular, such studies are limited in PD patients. We aimed to examine the predictive role of CVC for CVE and cardiovascular mortality in PD patients.

METHODS

A retrospective analysis was performed on patients who initiated PD in our hospital. According to the result of echocardiography, patients were divided into CVC group and non-CVC group. The differences in baseline demographic characteristics, biochemical variables, comorbidities, and clinical outcomes between the two groups were compared. Kaplan-Meier method was used to obtain survival curves. The Cox regression model was used to evaluate the influence of CVC for cardiovascular outcomes. The inverse probability of treatment weighting (IPTW) was used to eliminate influence of the confounders in the groups.

RESULTS

458 peritoneal dialysis patients were enrolled in this study. 77 patients were in CVC group and 381 patients in non-CVC group. The average follow-up time was (32 ± 21) months. At baseline, the absolute standardized difference (ASD) of age, BMI, history of CVE, diabetes, LVEF, LVMI, albumin, calcium, phosphorus, triglycerides, hsCRP, urine volume, Kt/V, statins and vitamin D intake rate were greater than 0.1 between the two groups. All of ASD dropped to less than 0.1 after IPTW, which meant that the balance had been reached between the two groups. Multivariable logistic analysis showed that advanced age, diabetes, and hyperphosphatemia were associated with CVC. The Kaplan-Meier survival curve showed the cumulative CVE-free survival rate and cardiovascular survival rate of CVC group were significantly lower than that of non-CVC group before and after IPTW (log-rank P < 0.05). After IPTW was used to eliminate the effect of confounders, multivariate Cox regression analysis still showed CVC was an independent risk factor for CVE (HR = 2.383, 95% CI 1.331~4.264, P = 0.003) and cardiovascular mortality (HR = 2.347, 95% CI 1.211~4.548, P = 0.012) in PD patients.

CONCLUSION

The prevalence of CVC is high in peritoneal dialysis patients. CVC is an independent risk factor for CVE and cardiovascular mortality in peritoneal dialysis patients.

Genome- and transcriptome-wide association studies show that pulmonary embolism is associated with bone-forming proteins

BACKGROUND

Pulmonary embolism (PE) is a leading cause of death in stroke patients and a severe health burden worldwide. There is a pressing need to understand the mechanisms by which it occurs and to identify at-risk patients efficiently and accurately.

OBJECTIVES

The aim of this paper was to analyze the genetic correlation between PE and human plasma proteins through genome-wide association study (GWAS) with transcriptome-wide association study (TWAS), in combination with mRNA expression profiling at three levels: DNA, RNA, and protein.

METHODS

First, based on data from GWAS in European populations, we performed a linkage disequilibrium score regression (LDSC) analysis of plasma proteins and PE in 3,283 individuals and additionally analyzed the genetic association between PE and fracture. Then, we performed a TWAS on PE GWAS data using skeletal muscle and blood for gene expression references. Finally, we validated the genetic correlation between PE and human plasma proteins by co-matching the genes encoding the identified proteins and those identified using TWAS with the differentially expressed genes obtained from mRNA expression profiling of PE (Figure1).

RESULTS

We identified five plasma proteins associated with PE, including hydroxycarboxylic acid receptor 2, defensin 118, and bone morphogenetic protein (BMP) 7, as well as a relationship between PE and fracture. Comparison of genes encoding these proteins with genes obtained from TWAS and then with differentially expressed genes obtained from PE mRNA expression profiling revealed that PE was highly correlated with the BMP family of genes.

The dual-effects of PLGA@MT electrospun nanofiber coatings on promoting osteogenesis at the titanium-bone interface under diabetic conditions

The high failure risk of endosseous titanium implants under diabetes conditions appeals to strengthen the osteointegration on the titanium-bone (Ti-B) interface. Melatonin (MT) is a neurohormone involved in bone homeostasis, which can promote osteogenesis and inhibit ROS overproduction through multiple pathways, but its effects on the Ti-B interface in diabetes remain elusive. The biodegradable poly(lactic-co-glycolic acid) (PLGA) has excellent controlled and sustained release properties, low cytotoxicity, and biocompatibility. Our study fabricated a nanofiber in which MT was encapsulated in PLGA to generate a nanofiber coating on a polydopamine (PDA)-modified titanium surface using electrospinning technology. The surface characteristic showed that MT was fully encapsulated in the PLGA carrier, and PLGA@MT was strongly coupled to the titanium matrix. Furthermore, the PLGA@MT-Ti nanofiber could release MT for at least 30 days. In vitro cellular tests demonstrated that PLGA@MT-Ti directly stimulates osteogenesis on the Ti-B interface by activating the BMP-4/WNT pathway in a dose-dependent manner. The effect of suppressing diabetes-induced ROS overproduction and promoting cell proliferation was not proportional to the content of MT. In vivo experiments revealed that PLGA@MT-Ti screws promoted the bone formation and osteointegration in type 1 diabetes mellitus (T1DM) mice with tibial bone defects. Our findings demonstrate that PLGA@MT-Ti exerted dual effects through activating the BMP-4/WNT pathway and attenuating ROS overproduction to promote osteogenesis and osteointegration at the Ti-B interface, providing a novel strategy to fabricate biomaterial modification and biofunctionalization under diabetic conditions.

Different Metabolic Phenotypes of Obesity and Risk of Coronary Artery Calcium Progression and Incident Cardiovascular Disease Events: The CARDIA Study

BACKGROUND

To investigate whether obesity with or without metabolic syndrome is prospectively associated with coronary artery calcium (CAC) progression and incident cardiovascular disease events.

METHODS

A total of 1730 participants from the CARDIA study (Coronary Artery Risk Development in Young Adults) were included (age, 40.1±3.6 years; 38.3% men), who completed computed tomography of CAC at baseline (year 15: 2000-2001) and follow-up (year 20 or 25). Metabolically healthy obesity (MHO) was defined as body mass index≥30 kg/m² without any metabolic syndrome components in our main analysis. Sensitivity analyses were conducted for several conditions characterizing 4 metabolic phenotypes.

RESULTS

During a mean follow-up of 9.1 years, 439 participants had CAC progression. MHO subjects had a significantly higher risk of CAC progression than their metabolically healthy normal weight counterparts (adjusted hazard ratios [95% CIs] from 1.761 [1.369-2.264] to 2.047 [1.380-3.036]) depending on the definition of MHO adopted. Obesity with unhealthy metabolic profile remained the highest significant risk of CAC progression and cardiovascular disease events whatever the definitions adopted for metabolically unhealthy status. Up to 60% of participants with MHO converted to metabolically unhealthy obesity from year 15 to year 20 or year 25. Further sensitivity analysis showed that MHO throughout carried a similar risk of incident cardiovascular disease events compared with metabolically healthy normal weight throughout.

CONCLUSIONS

Different metabolic phenotypes of obesity beginning at a young age exhibit distinct risks of CAC progression and subsequent cardiovascular disease events in later midlife. MHO represents an intermediate phenotype between metabolically low- to high-risk obese individuals.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT00005130.

LRG1 Accelerates Wound Healing in Diabetic Rats by Promoting Angiogenesis via the Wnt/β-Catenin Signaling Pathway

Patients with diabetic wounds may end with lower extremity amputation or death. Leucine-rich α-2-glycoprotein 1 (LRG1) is an effective regulator of angiogenesis and essential for timely wound healing. However, its role in regulating angiogenesis in diabetic wounds remains unclear. This study aimed to investigate the pro-angiogenic function of exogenous LRG1 in diabetic wound healing and explore possible mechanisms. LRG1 expression patterns following injury in normal and diabetic wounds were determined by western blotting. Local injection of LRG1 was used to verify the effects on angiogenesis and wound healing in diabetic rats. Immunohistochemical staining for CD31 was used to analyze the vessel density. Human umbilical vein endothelial cells (HUVECs) cultured in hyperglycemia were used to explore how LRG1 promotes angiogenesis in diabetic wound healing. We found that the expression peak of LRG1 around the wounds was delayed in diabetic rats compared with that in normal rats. Exogenous administration of LRG1 significantly accelerated the wound closure rate and promoted angiogenesis in diabetic rats. In addition, exogenous LRG1 effectively restored the proliferation, migration, and tube formation ability of HUVECs under hyperglycemia. Mechanistically, LRG1 promoted angiogenesis and diabetic wound healing mainly by activating the Wnt/β-catenin pathway, which is inhibited in diabetic wounds. This research suggests that LRG1 promotes angiogenesis and wound closure in diabetic rats by improving angiogenesis via activation of the Wnt/β-catenin pathway. Hence, LRG1 may be a possible therapeutic strategy for diabetic foot treatment.

Salvianolic acid B ameliorates vascular endothelial dysfunction through influencing a bone morphogenetic protein 4-ROS cycle in diabetic mice

AIM

This study investigated the roles of bone morphogenetic protein-4 (BMP4) and ROS in diabetic endothelial dysfunction and explored whether Salvianolic acid B (Sal B) improved endothelial function by affecting BMP4-ROS in diabetic mice.

MAIN METHODS

db/db mice were orally administrated with Sal B (10 mg/kg/day) for one week while db/m + mice were injected with adenoviral vectors delivering BMP4 (3 × 10⁸ pfu) and then received one week-Sal B treatment. ROS levels were assayed by DHE staining. Protein expression and phosphorylation were evaluated by Western blot. Aortic rings were suspended in myograph for force measurement. Flow-mediated dilatations in the second-order mesenteric arteries were determined by pressure myograph.

KEY FINDINGS

We first revealed the existence of a BMP4-ROS cycle in db/db mice, which stimulated p38 MAPK/JNK/caspase 3 and thus participated in endothelial dysfunction. One week-treatment or 24 h-incubation with Sal B disrupted the cycle, suppressed p38 MAPK/JNK/caspase 3 cascade, and improved endothelium-dependent relaxations (EDRs) in db/db mouse aortas. Importantly, in vivo Sal B treatment also improved flow-mediated dilatation in db/db mouse second order mesenteric arteries. Furthermore, in vivo BMP4 overexpression induced oxidative stress, stimulated p38 MAPK/JNK/caspase 3, and impaired EDRs in db/m + mouse aortas, which were all reversed by Sal B.

SIGNIFICANCE

The present study demonstrates that Sal B ameliorates endothelial dysfunction through breaking the BMP4-ROS cycle and subsequently inhibiting p38 MAPK/JNK/caspase 3 in diabetic mice and provides evidence for the additional new mechanism underlying the benefit of Sal B against diabetic vasculopathy.

RAGE Differentially Altered in vitro Responses in Vascular Smooth Muscle Cells and Adventitial Fibroblasts in Diabetes-Induced Vascular Calcification

The Advanced Glycation End-Products (AGE)/Receptor for AGEs (RAGE) signaling pathway exacerbates diabetes-mediated vascular calcification (VC) in vascular smooth muscle cells (VSMCs). Other cell types are involved in VC, such as adventitial fibroblasts (AFBs). We hope to elucidate some of the mechanisms responsible for differential signaling in diabetes-mediated VC with this work. This work utilizes RAGE knockout animals and in vitro calcification to measure calcification and protein responses. Our calcification data revealed that VSMCs calcification was AGE/RAGE dependent, yet AFBs calcification was not an AGE-mediated RAGE response. Protein expression data showed VSMCs lost their phenotype marker, α-smooth muscle actin, and had a higher RAGE expression over non-diabetics. RAGE knockout (RKO) VSMCs did not show changes in phenotype markers. P38 MAPK, a downstream RAGE-associated signaling molecule, had significantly increased activation with calcification in both diabetic and diabetic RKO VSMCs. AFBs showed a loss in myofibroblast marker, α-SMA, due to calcification treatment. RAGE expression decreased in calcified diabetic AFBs, and P38 MAPK activation significantly increased in diabetic and diabetic RKO AFBs. These findings point to potentially an alternate receptor mediating the calcification response in the absence of RAGE. Overall, VSMCs and AFBs respond differently to calcification and the application of AGEs.

Shifting osteogenesis in vascular calcification

Transitions between cell fates commonly occur in development and disease. However, reversing an unwanted cell transition in order to treat disease remains an unexplored area. Here, we report a successful process of guiding ill-fated transitions toward normalization in vascular calcification. Vascular calcification is a severe complication that increases the all-cause mortality of cardiovascular disease but lacks medical therapy. The vascular endothelium is a contributor of osteoprogenitor cells to vascular calcification through endothelial-mesenchymal transitions, in which endothelial cells (ECs) gain plasticity and the ability to differentiate into osteoblast-like cells. We created a high-throughput screening and identified SB216763, an inhibitor of glycogen synthase kinase 3 (GSK3), as an inducer of osteoblastic-endothelial transition. We demonstrated that SB216763 limited osteogenic differentiation in ECs at an early stage of vascular calcification. Lineage tracing showed that SB216763 redirected osteoblast-like cells to the endothelial lineage and reduced late-stage calcification. We also found that deletion of GSK3β in osteoblasts recapitulated osteoblastic-endothelial transition and reduced vascular calcification. Overall, inhibition of GSK3β promoted the transition of cells with osteoblastic characteristics to endothelial differentiation, thereby ameliorating vascular calcification.

Contributions of the Endothelium to Vascular Calcification

Vascular calcification (VC) increases morbidity and mortality and constitutes a significant obstacle during percutaneous interventions and surgeries. On a cellular and molecular level, VC is a highly regulated process that involves abnormal cell transitions and osteogenic differentiation, re-purposing of signaling pathways normally used in bone, and even formation of osteoclast-like cells. Endothelial cells have been shown to contribute to VC through a variety of means. This includes direct contributions of osteoprogenitor cells generated through endothelial-mesenchymal transitions in activated endothelium, with subsequent migration into the vessel wall. The endothelium also secretes pro-osteogenic growth factors, such as bone morphogenetic proteins, inflammatory mediators and cytokines in conditions like hyperlipidemia, diabetes, and renal failure. High phosphate levels caused by renal disease have deleterious effects on the endothelium, and induction of tissue non-specific alkaline phosphatase adds to the calcific process. Furthermore, endothelial activation promotes proteolytic destruction of the internal elastic lamina that serves, among other things, as a stabilizer of the endothelium. Appropriate bone mineralization is highly dependent on active angiogenesis, but it is unclear whether the same relationship exists in VC. Through its location facing the vascular lumen, the endothelium is the first to encounter circulating factor and bone marrow-derived cells that might contribute to osteoclast-like versus osteoblast-like cells in the vascular wall. In the same way, the endothelium may be the easiest target to reach with treatments aimed at limiting calcification. This review provides a brief summary of the contributions of the endothelium to VC as we currently know them.

Role of bone morphogenic protein-4 in gestational diabetes mellitus-related hypertension

Hyperglycaemia stimulates the synthesis and release of bone morphogenetic protein-4 (BMP-4) in vascular endothelial cells, which further induces peroxide production and inflammatory responses, leading to vascular endothelial dysfunction. However, the role of BMP-4 in gestational diabetes mellitus (GDM)-related vascular endothelial dysfunction remains unclear. In the present study, the hypothesis that the overexpression of BMP-4 would induce GDM-related hypertension by impairing vascular endothelial function was evaluated. An animal model of GDM was established in Sprague-Dawley (SD) rats. Based on blood pressure, rats were divided into control, GDM and GDM + hypertension (HT) groups. The expression levels of BMP-4, cyclooxygenase-2 (COX-2), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 1 (NOX-1) and vascular cell adhesion molecule 1 (VCAM-1) in the endothelium of the abdominal aorta of rats in each group were determined via immunohistochemistry and western blotting. Pregnant SD rats were divided into four groups, separately infused with BMP-4, BMP-4 + noggin, noggin or vehicle by osmotic pumps, and blood pressure and vasorelaxation were examined. Immunohistochemistry indicated that the expression levels of the four proteins were lower in the control group than in the GDM and GDM + HT groups. The positive expression rate of VCAM-1 was significantly lower in the control group than in the GDM and GDM+HT groups, and the differences were statistically significant (χ²=17.325, P<0.05; χ²=10.080, P<0.05). Western blotting revealed that the expression level of the COX-2 protein exhibited a sequential increase in the three groups. The expression level of COX-2 in the control and GDM groups was significantly lower than that in the GDM+HT group (3.358±1.286; P<0.05 and P<0.05, respectively). The expression level of VCAM-1 protein in the three groups also exhibited a significant sequential increase (F=31.732; P≤0.001). The expression level of VCAM-1 in the control and GDM groups was significantly lower than that in the GDM+HT group (2.698±0.223; P≤0.001 and P≤0.001, respectively). Infusion of BMP-4 increased systolic blood pressure (from 82 to 112 mmHg) and impaired vasorelaxation in pregnant SD rats after 2 weeks. Co-treatment with noggin completely blocked BMP-4-induced effects. Thus, the BMP-4/NOX-1/COX-2 signalling pathway may be involved in GDM-related hypertension, but VCAM-1 may be substantially associated with GDM-related hypertension. Furthermore, overexpression of BMP-4 could lead to hypertension by impairing endothelial function in pregnancy.

Off-target effects of oral anticoagulants - vascular effects of vitamin K antagonist and non-vitamin K antagonist oral anticoagulant dabigatran etexilate

INTRODUCTION

Vitamin K antagonists (VKA) and non-vitamin K oral antagonist anticoagulants (NOAC) are used in the clinic to reduce risk of thrombosis. However, they also exhibit vascular off-target effects. The aim of this study is to compare VKA and NOAC on atherosclerosis progression and calcification in an experimental setup.

MATERIAL AND METHODS

Female Apoe-/- mice (age 12 weeks) were fed Western-type diet as control or supplemented with dabigatran etexilate or warfarin for 6 or 18 weeks. Vascular calcification was measured in whole aortic arches using µCT and [18 F]-NaF. Atherosclerotic burden was assessed by (immuno)histochemistry. Additionally, in vitro effects of warfarin, thrombin, and dabigatran on primary vascular smooth muscle cells (VSMC) were assessed.

RESULTS

Short-term treatment with warfarin promoted formation of atherosclerotic lesions with a pro-inflammatory phenotype, and more rapid plaque progression compared with control and dabigatran. In contrast, dabigatran significantly reduced plaque progression compared with control. Long-term warfarin treatment significantly increased both presence and activity of plaque calcification compared with control and dabigatran. Calcification induced by warfarin treatment was accompanied by increased presence of uncarboxylated matrix Gla protein. In vitro, both warfarin and thrombin significantly increased VSMC oxidative stress and extracellular vesicle release, which was prevented by dabigatran.

CONCLUSION

Warfarin aggravates atherosclerotic disease activity, increasing plaque inflammation, active calcification, and plaque progression. Dabigatran lacks undesired vascular side effects and reveals beneficial effects on atherosclerosis progression and calcification. The choice of anticoagulation impacts atherosclerotic disease by differential off target effect. Future clinical studies should test whether this beneficial effect also applies to patients.

Bone Morphogenetic Proteins and Diabetic Retinopathy

Bone morphogenetic proteins (BMPs) play an important role in bone formation and repair. Recent studies underscored their essential role in the normal development of several organs and vascular homeostasis in health and diseases. Elevated levels of BMPs have been linked to the development of cardiovascular complications of diabetes mellitus. However, their particular role in the pathogenesis of microvascular dysfunction associated with diabetic retinopathy (DR) is still under-investigated. Accumulated evidence from our and others’ studies suggests the involvement of BMP signaling in retinal inflammation, hyperpermeability and pathological neovascularization in DR and age-related macular degeneration (AMD). Therefore, targeting BMP signaling in diabetes is proposed as a potential therapeutic strategy to halt the development of microvascular dysfunction in retinal diseases, particularly in DR. The goal of this review article is to discuss the biological functions of BMPs, their underlying mechanisms and their potential role in the pathogenesis of DR in particular.

The synergistic promotion of osseointegration by nanostructure design and silicon substitution of hydroxyapatite coatings in a diabetic model

Accumulating evidence indicates much higher failure rates for biomedical titanium implants in diabetic patients. This phenomenon is attributed to impaired osteoblastic function, suppressed angiogenesis capacity, and abnormal osteoclast activation in diabetic patients. Our previous study demonstrated that titanium implants coated with highly crystalline nanostructured hydroxyapatite (nHA) promoted the osteogenic differentiation of bone marrow stromal cells (BMSCs) and bone-implant osseointegration under healthy conditions. Furthermore, recent studies showed that silicon-substituted biomaterials exhibited excellent osteogenesis and angiogenesis performance while repressing osteoclastogenesis. Hence, we proposed that a combination of nanostructural modification and Si substitution might produce synergetic effects to mitigate the impaired osseointegration of bone implants under diabetes mellitus (DM) conditions. To confirm this hypothesis, titanium implants coated with highly crystalline Si-substituted nHA (Si-nHA) were successfully fabricated via atmospheric plasma spraying combined with hydrothermal treatment. An in vitro study demonstrated that compared to the original HA coating, the nHA coating improved osteogenic and angiogenic differentiation and altered the OPG/RANKL ratio of DM-BMSCs. In addition, the Si-nHA coating further enhanced cell proliferation, improved osteogenic and angiogenic differentiation, and repressed osteoclastogenesis in DM-BMSCs. An in vivo study confirmed that the titanium implants coated with nHA or Si-nHA effectively promoted bone formation and bone-implant osseointegration in a diabetic rabbit model, with the Si-nHA coating exhibiting the best stimulatory effect. Collectively, the results suggest that the nanostructured topography and Si substitution act synergistically to ameliorate the poor bone regeneration and osseointegration associated with DM. Thus, the results provide a promising coating method for dental and orthopedic applications under diabetic conditions.

The Dual Role of Vitamin K2 in "Bone-Vascular Crosstalk": Opposite Effects on Bone Loss and Vascular Calcification

Osteoporosis (OP) and vascular calcification (VC) represent relevant health problems that frequently coexist in the elderly population. Traditionally, they have been considered independent processes, and mainly age-related. However, an increasing number of studies have reported their possible direct correlation, commonly defined as “bone-vascular crosstalk”. Vitamin K2 (VitK2), a family of several natural isoforms also known as menaquinones (MK), has recently received particular attention for its role in maintaining calcium homeostasis. In particular, VitK2 deficiency seems to be responsible of the so-called “calcium paradox” phenomenon, characterized by low calcium deposition in the bone and its accumulation in the vessel wall. Since these events may have important clinical consequences, and the role of VitK2 in bone-vascular crosstalk has only partially been explained, this review focuses on its effects on the bone and vascular system by providing a more recent literature update. Overall, the findings reported here propose the VitK2 family as natural bioactive molecules that could be able to play an important role in the prevention of bone loss and vascular calcification, thus encouraging further in-depth studies to achieve its use as a dietary food supplement.

Diabetes as a Risk Factor for Orthopedic Implant Surface Performance: A Retrieval and In Vitro Study

Orthopedic devices are often associated with increased risk for diabetic patients due to impaired wound healing capabilities. Adverse biological responses for immunocompromised patients at the implant-tissue interface can lead to significant bone resorption that may increase failure rates. The goal of this study was to characterize the surface of implants removed from diabetic patients to determine underlying mechanisms of diabetes-induced impaired osseointegration. Thirty-nine retrieved titanium and stainless-steel orthopedic devices were obtained from diabetic and non-diabetic patients, and compared to non-implanted controls. Optical Microscopy, Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, and X-ray Photoelectron Spectroscopy revealed changes in morphology, chemical composition, oxidation state, and oxide thickness of the retrieval specimens, respectively. Additionally, titanium disks were immersed for 28 days in simulated in vitro diabetic conditions followed by Inductively Coupled Plasma-Optical Emission Spectroscopy to quantify metal dissolution. Electrochemical testing was performed on specimens from retrievals and in vitro study. Aside from biological deposits, retrievals demonstrated surface discoloration, pit-like formations and oxide thinning when compared to non-implanted controls, suggesting exposure to unfavorable acidic conditions. Cyclic load bearing areas on fracture-fixation screws and plates depicted cracking and delamination. The corrosion behavior was not significantly different between diabetic and non-diabetic conditions of immersed disks or implant type. However, simulated diabetic conditions elevated aluminum release. This elucidates orthopedic implant failures that potentially arise from diabetic environments at the implant-tissue interface. Design of new implant surfaces should consider specific strategies to induce constructive healing responses in immunocompromised patients while also mitigating corrosion in acidic diabetic environments.

Emerging Role of Bone Morphogenetic Protein 4 in Metabolic Disorders

Bone morphogenetic proteins (BMPs) are a group of signaling molecules that belong to the TGF-β superfamily. Initially discovered for their ability to induce bone formation, BMPs are known to play a diverse and critical array of biological roles. We here focus on recent evidence showing that BMP4 is an important regulator of white/beige adipogenic differentiation with important consequences for thermogenesis, energy homeostasis, and development of obesity in vivo. BMP4 is highly expressed in, and released by, human adipose tissue, and serum levels are increased in obesity. Recent studies have now shown BMP4 to play an important role not only for white/beige/brown adipocyte differentiation and thermogenesis but also in regulating systemic glucose homeostasis and insulin sensitivity. It also has important suppressive effects on hepatic glucose production and lipid metabolism. Cellular BMP4 signaling/action is regulated by both ambient cell/systemic levels and several endogenous and systemic BMP antagonists. Reduced BMP4 signaling/action can contribute to the development of obesity, insulin resistance, and associated metabolic disorders. In this article, we summarize the pleiotropic functions of BMP4 in the pathophysiology of these diseases and also consider the therapeutic implications of targeting BMP4 in the prevention/treatment of obesity and its associated complications.

Vascular calcification of chronic kidney disease: A brief review

Vascular calcification (VC) is highly prevalent among patients with chronic kidney disease (CKD). There is growing evidence that there is more underlying this condition than the histological presentation of atherosclerotic plaque and arteriosclerosis and that the risk of cardiovascular disease in the context of CKD might be explained by the presence of VC. While VC has been observed in the absence of overt abnormal mineral metabolism, this association is coupled to abnormal homeostasis of minerals in patients with CKD, due to hyperphosphatemia and hypercalcemia. Furthermore, recent studies have shown that the differentiation of vascular smooth muscle cells into an osteogenic phenotype is highly regulated by pro-calcifying and anti-calcifying factors. There are several imaging modalities currently used in clinical practice to evaluate the extent and severity of VC; each has different advantages and limitations. Although there is no universally accepted method for the treatment of VC, there is growing evidence of the beneficial effects of medical therapy for the condition. This study discusses the mechanism underlying VC, imaging modalities used for evaluation of the condition, and possible treatments.

Insights into the mechanism of vascular endothelial cells on bone biology

In the skeletal system, blood vessels not only function as a conduit system for transporting gases, nutrients, metabolic waste, or cells but also provide multifunctional signal molecules regulating bone development, regeneration, and remodeling. Endothelial cells (ECs) in bone tissues, unlike in other organ tissues, are in direct contact with the pericytes of blood vessels, resulting in a closer connection with peripheral connective tissues. Close-contact ECs contribute to osteogenesis and osteoclastogenesis by secreting various cytokines in the paracrine or juxtacrine pathways. An increasing number of studies have revealed that extracellular vesicles (EVs) derived from ECs can directly regulate maturation process of osteoblasts and osteoclasts. The different pathways focus on targets at different distances, forming the basis of the intimate spatial and temporal link between bone tissue and blood vessels. Here, we provide a systematic review to elaborate on the function of ECs in bone biology and its underlying mechanisms based on three aspects: paracrine, EVs, and juxtacrine. This review proposes the possibility of a therapeutic strategy targeting blood vessels, as an adjuvant treatment for bone disorders.

Transcriptional Programming in Arteriosclerotic Disease: A Multifaceted Function of the Runx2 (Runt-Related Transcription Factor 2)

Despite successful therapeutic strategies in the prevention and treatment of arteriosclerosis, the cardiovascular complications remain a major clinical and societal issue worldwide. Increased vascular calcification promotes arterial stiffness and accelerates cardiovascular morbidity and mortality. Upregulation of the Runx2 (Runt-related transcription factor 2), an essential osteogenic transcription factor for bone formation, in the cardiovascular system has emerged as an important regulator for adverse cellular events that drive cardiovascular pathology. This review discusses the regulatory mechanisms that are critical for Runx2 expression and function and highlights the dynamic and complex cross talks of a wide variety of posttranslational modifications, including phosphorylation, acetylation, ubiquitination, and O-linked β-N-acetylglucosamine modification, in regulating Runx2 stability, cellular localization, and osteogenic transcriptional activity. How the activation of an array of signaling cascades by circulating and local microenvironmental factors upregulates Runx2 in vascular cells and promotes Runx2-mediated osteogenic transdifferentiation of vascular smooth muscle cells and expression of inflammatory cytokines that accelerate macrophage infiltration and vascular osteoclast formation is summarized. Furthermore, the increasing appreciation of a new role of Runx2 upregulation in promoting vascular smooth muscle cell phenotypic switch, and Runx2 modulated by O-linked β-N-acetylglucosamine modification and Runx2-dependent repression of smooth muscle cell-specific gene expression are discussed. Further exploring the regulation of this key osteogenic transcription factor and its new perspectives in the vasculature will provide novel insights into the transcriptional regulation of vascular smooth muscle cell phenotype switch, reprograming, and vascular inflammation that promote the pathogenesis of arteriosclerosis.

Epidemiological Research Advances in Vascular Calcification in Diabetes

Vascular calcification is the transformation of arterial wall mesenchymal cells, particularly smooth muscle cells (SMCs), into osteoblast phenotypes by various pathological factors. Additionally, vascular transformation mediates the abnormal deposition of calcium salts in the vascular wall, such as intimal and media calcification. Various pathological types have been described, such as calcification and valve calcification. The incidence of vascular calcification in patients with diabetes is much higher than that in nondiabetic patients, representing a critical cause of cardiovascular events in patients with diabetes. Because basic research on the clinical transformation of vascular calcification has yet to be conducted, this study systematically expounds on the risk factors for vascular calcification, vascular bed differences, sex differences, ethnic differences, diagnosis, severity assessments, and treatments to facilitate the identification of a new entry point for basic research and subsequent clinical transformation regarding vascular calcification and corresponding clinical evaluation strategies.

The role of bone morphogenetic protein signaling in vascular calcification

Vascular calcification is associated with atherosclerosis, chronic kidney disease, and diabetes, and results from processes resembling endochondral or intramembranous ossification, or from processes that are distinct from ossification. Bone morphogenetic proteins (BMP), as well as other ligands, receptors, and regulators of the transforming growth factor beta (TGFβ) family regulate vascular and valvular calcification by modulating the phenotypic plasticity of multipotent progenitor lineages associated with the vasculature or valves. While osteogenic ligands BMP2 and BMP4 appear to be both markers and drivers of vascular calcification, particularly in atherosclerosis, BMP7 may serve to protect against calcification in chronic kidney disease. BMP signaling regulators such as matrix Gla protein and BMP-binding endothelial regulator protein (BMPER) play protective roles in vascular calcification. The effects of BMP signaling molecules in vascular calcification are context-dependent, tissue-dependent, and cell-type specific. Here we review the current knowledge on mechanisms by which BMP signaling regulates vascular calcification and the potential therapeutic implications.

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.

miR-18a Inhibits BMP4 and HIF-1α Normalizing Brain Arteriovenous Malformations

RATIONALE

Brain arteriovenous malformations (AVMs) are abnormal tangles of vessels where arteries and veins directly connect without intervening capillary nets, increasing the risk of intracerebral hemorrhage and stroke. Current treatments are highly invasive and often not feasible. Thus, effective noninvasive treatments are needed. We previously showed that AVM-brain endothelial cells (BECs) secreted higher VEGF (vascular endothelial growth factor) and lower TSP-1 (thrombospondin-1) levels than control BEC; and that microRNA-18a (miR-18a) normalized AVM-BEC function and phenotype, although its mechanism remained unclear.

OBJECTIVE

To elucidate the mechanism of action and potential clinical application of miR-18a as an effective noninvasive treatment to selectively restore the phenotype and functionality of AVM vasculature.

METHODS AND RESULTS

The molecular pathways affected by miR-18a in patient-derived BECs and AVM-BECs were determined by Western blot, RT-qPCR (quantitative reverse transcription polymerase chain reaction), ELISA, co-IP, immunostaining, knockdown and overexpression studies, flow cytometry, and luciferase reporter assays. miR-18a was shown to increase TSP-1 and decrease VEGF by reducing PAI-1 (plasminogen activator inhibitor-1/SERPINE1) levels. Furthermore, miR-18a decreased the expression of BMP4 (bone morphogenetic protein 4) and HIF-1α (hypoxia-inducible factor 1α), blocking the BMP4/ALK (activin-like kinase) 2/ALK1/ALK5 and Notch signaling pathways. As determined by Boyden chamber assays, miR-18a also reduced the abnormal AVM-BEC invasiveness, which correlated with a decrease in MMP2 (matrix metalloproteinase 2), MMP9, and ADAM10 (ADAM metallopeptidase domain 10) levels. In vivo pharmacokinetic studies showed that miR-18a reaches the brain following intravenous and intranasal administration. Intranasal co-delivery of miR-18a and NEO100, a good manufacturing practices-quality form of perillyl alcohol, improved the pharmacokinetic profile of miR-18a in the brain without affecting its pharmacological properties. Ultra-high-resolution computed tomography angiography and immunostaining studies in an Mgp^-/- AVM mouse model showed that miR-18a decreased abnormal cerebral vasculature and restored the functionality of the bone marrow, lungs, spleen, and liver.

CONCLUSIONS

miR-18a may have significant clinical value in preventing, reducing, and potentially reversing AVM.

Arterial Stiffness: A Focus on Vascular Calcification and Its Link to Bone Mineralization

This review focuses on the association between vascular calcification and arterial stiffness, highlighting the important genetic factors, systemic and local microenvironmental signals, and underlying signaling pathways and molecular regulators of vascular calcification. Elevated oxidative stress appears to be a common procalcification factor that induces osteogenic differentiation and calcification of vascular cells in a variety of disease conditions such as atherosclerosis, diabetes mellitus, and chronic kidney disease. Thus, the role of oxidative stress and oxidative stress-regulated signals in vascular smooth muscle cells and their contributions to vascular calcification are highlighted. In relation to diabetes mellitus, the regulation of both hyperglycemia and increased protein glycosylation, by AGEs (advanced glycation end products) and O-linked β-N-acetylglucosamine modification, and its role in enhancing intracellular pathophysiological signaling that promotes osteogenic differentiation and calcification of vascular smooth muscle cells are discussed. In the context of chronic kidney disease, this review details the role of calcium and phosphate homeostasis, parathyroid hormone, and specific calcification inhibitors in regulating vascular calcification. In addition, the impact of the systemic and microenvironmental factors on respective intrinsic signaling pathways that promote osteogenic differentiation and calcification of vascular smooth muscle cells and osteoblasts are compared and contrasted, aiming to dissect the commonalities and distinctions that underlie the paradoxical vascular-bone mineralization disorders in aging and diseases.

Regulatory Effects of O-GlcNAcylation in Vascular Smooth Muscle Cells on Diabetic Vasculopathy

Vascular complications from uncontrolled hyperglycemia are the leading cause of death in patients with diabetes mellitus. Previous reports have shown a strong correlation between hyperglycemia and vascular calcification, which increases mortality and morbidity in individuals with diabetes. However, the precise underlying molecular mechanisms of hyperglycemia-induced vascular calcification remain largely unknown. Transdifferentiation of vascular smooth muscle cells (VSMC) into osteoblast-like cells is a known culprit underlying the development of vascular calcification in the diabetic vasculature. Pathological conditions such as high glucose levels and oxidative stress are linked to enhanced osteogenic differentiation of VSMC both in vivo and in vitro. It has been demonstrated that increased expression of runt-related transcription factor 2 (Runx2), a bone-related transcription factor, in VSMC is necessary and sufficient for the induction of VSMC calcification. Addition of a single O-linked β-N-acetylglucosamine (O-GlcNAc) moiety to the serine/threonine residues of target proteins (O-GlcNAcylation) has been observed in the arteries of diabetic patients, as well as in animal models in association with the enhanced expression of Runx2 and aggravated vascular calcification. O-GlcNAcylation is a dynamic and tightly regulated process, that is mediated by 2 enzymes, O-GlcNAc transferase and O-GlcNAcase. Glucose is metabolized into UDP-β-D-N-acetylglucosamine, an active sugar donor of O-GlcNAcylation via the hexosamine biosynthetic pathway. Overall increases in the O-GlcNAcylation of cellular proteins have been closely associated with cardiovascular complications of diabetes. In this review, the authors provide molecular insights into cardiovascular complications, including diabetic vasculopathy, that feature increased O-GlcNAcylation in people with diabetes.

Homeobox D3, A Novel Link Between Bone Morphogenetic Protein 9 and Transforming Growth Factor Beta 1 Signaling

AIMS

Several signaling pathways contribute to endothelial-mesenchymal transitions and vascular calcification, including bone morphogenetic protein (BMP) and transforming growth factor (TGF) β signaling. The transcription factor homeobox D3 (Hoxd3) is known to regulate an invasive endothelial phenotype, and the aim of the study is to determine if HOXD3 modulates BMP and TGFβ signaling in the endothelium.

METHODS AND RESEARCH

We report that the endothelium with high BMP activity due to the loss of BMP inhibitor matrix Gla protein (MGP) shows induction of Hoxd3. HOXD3 is part of a BMP-triggered cascade. When activated by BMP9, activin receptor-like kinase (ALK) 1 induces HOXD3 expression. Hoxd3 promoter is a direct target of phosphorylated (p) SMAD1, a mediator of BMP signaling. High BMP activity further results in enhanced TGFβ signaling due to induction of TGFβ1 and its receptor, ALK5. This is mediated by HOXD3, which directly targets the Tgfb1 promoter. Finally, TGFβ1 and BMP9 stimulate the expression of MGP, which limits the enhanced ALK1 induction by counteracting BMP4. The cascade of BMP9-HOXD3-TGFβ also affects Notch signaling and angiogenesis through induction of Notch ligand Jagged 2 and suppression of Notch ligand delta-like 4 (Dll4).

CONCLUSION

The results suggest that HOXD3 is a novel link between BMP9/ALK1 and TGFβ1/ALK5 signaling.

TRANSLATIONAL PERSPECTIVE

BMP and TGFβ signaling are instrumental in vascular disease such as vascular calcification and atherosclerosis. This study demonstrated a novel type of cross talk between endothelial BMP and TGFβ signaling as mediated by HOXD3. The results provide a possible therapeutic approach to control dysfunctional BMP and TGFβ signaling by regulating HOXD3.

Excessive cholecalciferol supplementation increases kidney dysfunction associated with intrarenal artery calcification in obese insulin-resistant mice

Diabetes mellitus accelerates vascular calcification (VC) and increases the risk of end-stage renal disease (ESRD). Nevertheless, the impact of VC in renal disease progression in type 2 diabetes mellitus (T2DM) is poorly understood. We addressed the effect of VC and mechanisms involved in renal dysfunction in a murine model of insulin resistance and obesity (ob/ob), comparing with their healthy littermates (C57BL/6). We analyzed VC and renal function in both mouse strains after challenging them with Vitamin D₃ (VitD₃). Although VitD₃ similarly increased serum calcium and induced bone disease in both strains, 24-hour urine volume and creatinine pronouncedly decreased only in ob/ob mice. Moreover, ob/ob increased urinary albumin/creatinine ratio (ACR), indicating kidney dysfunction. In parallel, ob/ob developed extensive intrarenal VC after VitD₃. Coincidently with increased intrarenal vascular mineralization, our results demonstrated that Bone Morphogenetic Protein-2 (BMP-2) was highly expressed in these arteries exclusively in ob/ob. These data depict a greater susceptibility of ob/ob mice to develop renal disease after VitD₃ in comparison to paired C57BL/6. In conclusion, this study unfolds novel mechanisms of progressive renal dysfunction in diabetes mellitus (DM) after VitD₃in vivo associated with increased intrarenal VC and highlights possible harmful effects of long-term supplementation of VitD₃ in this population.

Expansive Vascular Remodeling and Increased Vascular Calcification Response to Cholecalciferol in a Murine Model of Obesity and Insulin Resistance

Objective- We hypothesized that ob/ob mice develop expansive vascular remodeling associated with calcification. Approach and Results- We quantified and investigated mechanisms of vascular remodeling and vascular calcification in ob/ob mice after vitamin D₃(VD) stimulation or PBS (control), compared with C57BL/6 mice. Both ob/ob (OBVD [VD-treated ob/ob mice]) and C57BL/6 (C57VD [VD-treated C57BL/6 mice]) received 8×10³ IU/day of intraperitoneal VD for 14 days. Control ob/ob (OBCT [PBS-treated ob/ob mice]) and C57BL/6 (C57CT [PBS-treated C57BL/6 mice]) received intraperitoneal PBS for 14 days. Hypervitaminosis D increased the external and internal elastic length in aortae from OBVD, resulting in increased total vascular area and lumen vascular area, respectively, which characterizes expansive vascular remodeling. OBVD decreased the aortic wall thickness, resulting in hypotrophic vascular remodeling. We demonstrated increased collagen deposition, elastolysis, and calcification in aortae from OBVD. Our results showed a positive correlation between expansive vascular remodeling and vascular calcification in OBVD. We demonstrated increased serum calcium levels, augmented Bmp (bone morphogenetic protein)-2 and osteochondrogenic proteins expression in OBVD aortae. Furthermore, aortae from OBVD increased oxidative stress, coincidently with augmented in situ MMP (matrix metalloproteinase) activity and exhibited no VDR (VD receptor) inhibition after VD. Conclusions- Our data provide evidence that obese and insulin-resistant mice (ob/ob) developed expansive hypotrophic vascular remodeling correlated directly with increased vascular calcification after chronic VD stimulation. Positive hypotrophic vascular remodeling and vascular calcification in this mouse model is possibly mediated by the convergence of absence VDR downregulation after VD stimulation, increased reactive oxygen species generation, and MMP activation.

The Role of Bone Morphogenetic Proteins in Diabetic Complications

The prevalence of diabetes has reached epidemic proportions and is placing a significant burden on healthcare systems globally. Diabetes has a detrimental impact on many organs in the human body, including accelerating the development of micro- and macrovascular complications. Current therapeutic options to treat diabetic complications have their limitations. Importantly, many slow but fail to reverse the progression of diabetic complications. Bone morphogenetic proteins (BMPs) are a highly conserved subgroup of the transforming growth factor β (TGFβ) superfamily, signaling via serine/threonine kinase receptors, that have recently been implicated in glucose homeostasis and insulin resistance in the setting of diabetes. Downstream of the receptors, the signal can be transduced via the canonical Smad-dependent pathway or the noncanonical Smad-independent pathways. BMPs are essential in organ development, tissue homeostasis, and, as expected, disease pathogenesis. In fact, deletion of BMPs can be embryonically lethal or result in severe organ abnormalities. This review outlines the BMP signaling pathway and its relevance to diabetic complications, namely, diabetic nephropathy, diabetes-associated cardiovascular diseases, and diabetic retinopathy. Understanding the complexities of BMP signaling and particularly its tissue-, cellular-, and time-dependent actions will help delineate the underlying pathogenesis of the disease and may ultimately be harnessed in the treatment of diabetes-induced complications. This would replicate progress made in numerous other diseases, including cancer and atherosclerosis.

Interplay between BMPs and Reactive Oxygen Species in Cell Signaling and Pathology

The integration of cell extrinsic and intrinsic signals is required to maintain appropriate cell physiology and homeostasis. Bone morphogenetic proteins (BMPs) are cytokines that belong to the transforming growth factor-β (TGF-β) superfamily, which play a key role in embryogenesis, organogenesis and regulation of whole-body homeostasis. BMPs interact with membrane receptors that transduce information to the nucleus through SMAD-dependent and independent pathways, including PI3K-AKT and MAPKs. Reactive oxygen species (ROS) are intracellular molecules derived from the partial reduction of oxygen. ROS are highly reactive and govern cellular processes by their capacity to regulate signaling pathways (e.g., NF-κB, MAPKs, KEAP1-NRF2 and PI3K-AKT). Emerging evidence indicates that BMPs and ROS interplay in a number of ways. BMPs stimulate ROS production by inducing NOX expression, while ROS regulate the expression of several BMPs. Moreover, BMPs and ROS influence common signaling pathways, including PI3K/AKT and MAPK. Additionally, dysregulation of BMPs and ROS occurs in several pathologies, including vascular and musculoskeletal diseases, obesity, diabetes and kidney injury. Here, we review the current knowledge on the integration between BMP and ROS signals and its potential applications in the development of new therapeutic strategies.

The Vicious Cycle of Arterial Stiffness and Arterial Media Calcification

Arterial media calcification and arterial stiffness are independent predictors of cardiovascular mortality. Both processes reinforce one another, creating a vicious cycle in which transdifferentiation of endothelial cells and vascular smooth muscle cells play a central role. Physiological functioning of vascular smooth muscle cells in the arterial medial layer greatly depends on normal endothelial cell behavior. Endothelial or intimal layer cells are the primary sensors of pathological triggers circulating in the blood during, for example, ageing or inflammation, and often can be seen as initiators of this vicious cycle. As such, the search for treatment of arterial media calcification, which until now has been mainly concentrated at the level of the vascular smooth cell, may need to be expanded to intimal layer targets.

Metabolic Stress and Cardiovascular Disease in Diabetes Mellitus: The Role of Protein O-GlcNAc Modification

Mammalian cells metabolize glucose primarily for energy production, biomass synthesis, and posttranslational glycosylation; and maintaining glucose metabolic homeostasis is essential for normal physiology of cells. Impaired glucose homeostasis leads to hyperglycemia, a hallmark of diabetes mellitus. Chronically increased glucose in diabetes mellitus promotes pathological changes accompanied by impaired cellular function and tissue damage, which facilitates the development of cardiovascular complications, the major cause of morbidity and mortality of patients with diabetes mellitus. Emerging roles of glucose metabolism via the hexosamine biosynthesis pathway (HBP) and increased protein modification via O-linked β-N-acetylglucosamine (O-GlcNAcylation) have been demonstrated in diabetes mellitus and implicated in the development of diabetic cardiovascular complications. This review will discuss the biological outcomes of the glucose metabolism via the hexosamine biogenesis pathway and protein O-GlcNAcylation in regulating cellular homeostasis, and highlight the regulations and contributions of elevated O-GlcNAcylation to the pathogenesis of diabetic cardiovascular disease.

Beyond the bone: Bone morphogenetic protein signaling in adipose tissue

The bone morphogenetic proteins (BMPs) belong to the same superfamily as related to transforming growth factor β (TGFβ), growth and differentiation factors (GDFs), and activins. They were initially described as inducers of bone formation but are now known to be involved in morphogenetic activities and cell differentiation throughout the body, including the development of adipose tissue and adipogenic differentiation. BMP4 and BMP7 are the most studied BMPs in adipose tissue, with major roles in white adipogenesis and brown adipogenesis, respectively, but other BMPs such as BMP2, BMP6, and BMP8b as well as some inhibitors and modulators have been shown to also affect adipogenesis. It has become ever more important to understand adipose regulation, including the BMP pathways, in light of the strong links between obesity and metabolic and cardiovascular disease. In this review, we summarize the available information on BMP signaling in adipose tissue using preferentially articles that have appeared in the last decade, which together demonstrate the importance of BMP signaling in adipose biology.

S100/RAGE-Mediated Inflammation and Modified Cholesterol Lipoproteins as Mediators of Osteoblastic Differentiation of Vascular Smooth Muscle Cells

Arterial calcification is a feature of atherosclerosis and shares many risk factors including diabetes, dyslipidemia, chronic kidney disease, hypertension, and age. Although there is overlap in risk factors, anti-atherosclerotic therapies, including statins, fail to reduce arterial, and aortic valve calcifications. This suggests that low density lipoprotein (LDL) may not be the main driver for aortic valve disease and arterial calcification. This review focuses on modified LDLs and their role in mediating foam cell formation in smooth muscle cells (SMCs), with special emphasis on enzyme modified non-oxidized LDL (ELDL). In vivo, ELDL represents one of the many forms of modified LDLs present in the atherosclerotic vessel. Phenotypic changes of macrophages and SMCs brought about by the uptake of modified LDLs overlap significantly in an atherosclerotic milieu, making it practically impossible to differentiate between the effects from oxidized LDL, ELDL, and other LDL modification. By studying in vitro-generated modifications of LDL, we were able to demonstrate marked differences in the transcriptome of human coronary artery SMCs (HCASMCs) upon uptake of ELDL, OxLDL, and native LDL, indicating that specific modifications of LDL in atherosclerotic plaques may determine the biology and functional consequences in vasculature. Enzyme-modified non-oxidized LDL (ELDL) induces calcification of SMCs and this is associated with reduced mRNA levels for genes protective for calcification (ENPP1, MGP) and upregulation of osteoblastic genes. A second focus of this review is on the synergy between hyperlipidemia and accelerated calcification In vivo in a mouse models with transgenic expression of human S100A12. We summarize mechanisms of S100A12/RAGE mediated vascular inflammation promoting vascular and valve calcification in vivo.

Circulating osteogenic proteins are associated with coronary artery calcification and increase after myocardial infarction

BACKGROUND

Coronary artery calcification (CAC) and atherosclerotic inflammation associate with increased risk of myocardial infarction (MI). Vascular calcification is regulated by osteogenic proteins (OPs). It is unknown whether an association exists between CAC and plasma OPs and if they are affected by atherothrombotic inflammation. We tested the association of osteogenic and inflammatory proteins with CAC and assessed these biomarkers after MI.

METHODS

Circulating OPs (osteoprotegerin, RANKL, fetuin-A, Matrix Gla protein [MGP]) and inflammatory proteins (C-reactive protein, oxidized-LDL, tumoral necrosis factor-α, transforming growth factor [TGF]-β1) were compared between stable patients with CAC (CAC ≥ 100 AU, n = 100) and controls (CAC = 0 AU, n = 30). The association between biomarkers and CAC was tested by multivariate analysis. In patients with MI (n = 40), biomarkers were compared between acute phase and 1-2 months post-MI, using controls as a baseline.

RESULTS

MGP and fetuin-A levels were higher within individuals with CAC. Higher levels of MGP and RANKL were associated with CAC (OR 3.12 [95% CI 1.20-8.11], p = 0.02; and OR 1.75 [95% CI 1.04-2.94] respectively, p = 0.035). After MI, C-reactive protein, OPG and oxidized-LDL levels increased in the acute phase, whereas MGP and TGF-β1 increased 1-2 months post-MI.

CONCLUSIONS

Higher MGP and RANKL levels associate with CAC. These findings highlight the potential role of these proteins as modulators and markers of CAC. In addition, the post-MI increase in OPG and MGP, as well as of inflammatory proteins suggest that the regulation of these OPs is affected by atherothrombotic inflammation.

Emerging Strategies for Stem Cell Lineage Commitment in Tissue Engineering and Regenerative Medicine

Stem cells have transformed the fields of tissue engineering and regenerative medicine, and their potential to further advance these fields cannot be overstated. The stem cell niche is a dynamic microenvironment that determines cell fate during development and tissue repair following an injury. Classically, stem cells were studied in isolation of their microenvironment; however, contemporary research has produced a myriad of evidence that shows the importance of multiple aspects of the stem cell niche in regulating their processes. In the context of tissue engineering and regenerative medicine studies, the niche is an artificial environment provided by culture conditions. In vitro culture conditions may involve coculturing with other cell types, developing specific biomaterials, and applying relevant forces to promote the desired lineage commitment. Considerable advance has been made over the past few years toward directed stem cell differentiation; however, the unspecific differentiation of stem cells yielding a mixed population of cells has been a challenge. In this review, we provide a systematic review of the emerging strategies used for lineage commitment within the context of tissue engineering and regenerative medicine. These strategies include scaffold pore-size and pore-shape gradients, stress relaxation, sonic and electromagnetic effects, and magnetic forces. Finally, we provide insights and perspectives into future directions focusing on signaling pathways activated during lineage commitment using external stimuli.