Anti-inflammatory and antiatherogenic role of BMP receptor II in endothelial cells

Pulmonary Hypertension: Pharmacological and Non-Pharmacological Therapies

Pulmonary hypertension (PH) is a severe and chronic disease characterized by increased pulmonary vascular resistance and remodeling, often precipitating right-sided heart dysfunction and death. Although the condition is progressive and incurable, current therapies for the disease focus on multiple different drugs and general supportive therapies to manage symptoms and prolong survival, ranging from medications more specific to pulmonary arterial hypertension (PAH) to exercise training. Moreover, there are multiple studies exploring novel experimental drugs and therapies including unique neurostimulation, to help better manage the disease. Here, we provide a narrative review focusing on current PH treatments that target multiple underlying biochemical mechanisms, including imbalances in vasoconstrictor-vasodilator and autonomic nervous system function, inflammation, and bone morphogenic protein (BMP) signaling. We also focus on the potential of novel therapies for managing PH, focusing on multiple types of neurostimulation including acupuncture. Lastly, we also touch upon the disease's different subgroups, clinical presentations and prognosis, diagnostics, demographics, and cost.

The role of immune cells and inflammation in pulmonary hypertension: mechanisms and implications

Pulmonary hypertension (PH) is a malignant disease with progressive increase of pulmonary vascular pressure, which eventually leads to right heart failure. More and more evidences show that immune cells and inflammation play an important role in the occurrence and development of PH. In the context of pulmonary vascular diseases, immune cells migrate into the walls of the pulmonary vascular system. This leads to an increase in the levels of cytokines and chemokines in both the bloodstream and the surrounding tissues of the pulmonary vessels. As a result, new approaches such as immunotherapy and anti-inflammatory treatments are being considered as potential strategies to halt or potentially reverse the progression of PH. We reviewed the potential mechanisms of immune cells, cytokines and chemokines in PH development. The potential relationship of vascular cells or bone morphogenetic protein receptor 2 (BMPR2) in immune regulation was also expounded. The clinical application and future prospect of immunotherapy were further discussed.

LncRNA NIPA1-SO confers atherosclerotic protection by suppressing the transmembrane protein NIPA1

Long non-coding RNAs (lncRNAs) are emerging as important players in gene regulation and cardiovascular diseases. However, the roles of lncRNAs in atherosclerosis are poorly understood. In the present study, we found that the levels of NIPA1-SO were decreased while those of NIPA1 were increased in human atherosclerotic plaques. Furthermore, NIPA1-SO negatively regulated NIPA1 expression in human umbilical vein endothelial cells (HUVECs). Mechanistically, NIPA1-SO interacted with the transcription factor FUBP1 and the NIPA1 gene. The effect of NIPA1-SO on NIPA1 protein levels was reversed by the knockdown of FUBP1. NIPA1-SO overexpression increased, whilst NIPA1-SO knockdown decreased BMPR2 levels; these effects were enhanced by the knockdown of NIPA1. The overexpression of NIPA1-SO reduced while NIPA1-SO knockdown increased monocyte adhesion to HUVECs; these effects were diminished by the knockdown of BMPR2. The lentivirus-mediated-overexpression of NIPA1-SO or gene-targeted knockout of NIPA1 in low-density lipoprotein receptor-deficient mice reduced monocyte-endothelium adhesion and atherosclerotic lesion formation. Collectively, these findings revealed a novel anti-atherosclerotic role for the lncRNA NIPA1-SO and highlighted its inhibitory effects on vascular inflammation and intracellular cholesterol accumulation by binding to FUBP1 and consequently repressing NIPA1 expression.

Flow-induced reprogramming of endothelial cells in atherosclerosis

Atherosclerotic diseases such as myocardial infarction, ischaemic stroke and peripheral artery disease continue to be leading causes of death worldwide despite the success of treatments with cholesterol-lowering drugs and drug-eluting stents, raising the need to identify additional therapeutic targets. Interestingly, atherosclerosis preferentially develops in curved and branching arterial regions, where endothelial cells are exposed to disturbed blood flow with characteristic low-magnitude oscillatory shear stress. By contrast, straight arterial regions exposed to stable flow, which is associated with high-magnitude, unidirectional shear stress, are relatively well protected from the disease through shear-dependent, atheroprotective endothelial cell responses. Flow potently regulates structural, functional, transcriptomic, epigenomic and metabolic changes in endothelial cells through mechanosensors and mechanosignal transduction pathways. A study using single-cell RNA sequencing and chromatin accessibility analysis in a mouse model of flow-induced atherosclerosis demonstrated that disturbed flow reprogrammes arterial endothelial cells in situ from healthy phenotypes to diseased ones characterized by endothelial inflammation, endothelial-to-mesenchymal transition, endothelial-to-immune cell-like transition and metabolic changes. In this Review, we discuss this emerging concept of disturbed-flow-induced reprogramming of endothelial cells (FIRE) as a potential pro-atherogenic mechanism. Defining the flow-induced mechanisms through which endothelial cells are reprogrammed to promote atherosclerosis is a crucial area of research that could lead to the identification of novel therapeutic targets to combat the high prevalence of atherosclerotic disease.

Atherosclerosis from Newborn to Adult-Epidemiology, Pathological Aspects, and Risk Factors

Cardiovascular disease is the leading cause of mortality and morbidity throughout the world, accounting for 16.7 million deaths each year. The underlying pathological process for the majority of cardiovascular diseases is atherosclerosis, a slowly progressing, multifocal, chronic, immune-inflammatory disease that involves the intima of large and medium-sized arteries. The process of atherosclerosis begins in childhood as fatty streaks-an accumulation of lipids, inflammatory cells, and smooth muscle cells in the arterial wall. Over time, a more complex lesion develops into an atheroma and characteristic fibrous plaques. Atherosclerosis alone is rarely fatal; it is the further changes that render fibrous plaques vulnerable to rupture; plaque rupture represents the most common cause of coronary thrombosis. The prevalence of atherosclerosis is increasing worldwide and more than 50% of people with circulatory disease die of it, mostly in modern societies. Epidemiological studies have revealed several environmental and genetic risk factors that are associated with the early formation of a pathogenic foundation for atherosclerosis, such as dyslipidemia, hypertension, diabetes mellitus, obesity, and smoking. The purpose of this review is to bring together the current information concerning the origin and progression of atherosclerosis in childhood as well as the identification of known risk factors for atherosclerotic cardiovascular disease in children.

Human iPSCs as Model Systems for BMP-Related Rare Diseases

Disturbances in bone morphogenetic protein (BMP) signalling contribute to onset and development of a number of rare genetic diseases, including Fibrodysplasia ossificans progressiva (FOP), Pulmonary arterial hypertension (PAH), and Hereditary haemorrhagic telangiectasia (HHT). After decades of animal research to build a solid foundation in understanding the underlying molecular mechanisms, the progressive implementation of iPSC-based patient-derived models will improve drug development by addressing drug efficacy, specificity, and toxicity in a complex humanized environment. We will review the current state of literature on iPSC-derived model systems in this field, with special emphasis on the access to patient source material and the complications that may come with it. Given the essential role of BMPs during embryonic development and stem cell differentiation, gain- or loss-of-function mutations in the BMP signalling pathway may compromise iPSC generation, maintenance, and differentiation procedures. This review highlights the need for careful optimization of the protocols used. Finally, we will discuss recent developments towards complex in vitro culture models aiming to resemble specific tissue microenvironments with multi-faceted cellular inputs, such as cell mechanics and ECM together with organoids, organ-on-chip, and microfluidic technologies.

Expression of targets of the RNA-binding protein AUF-1 in human airway epithelium indicates its role in cellular senescence and inflammation

Introduction

The RNA-binding protein AU-rich-element factor-1 (AUF-1) participates to posttranscriptional regulation of genes involved in inflammation and cellular senescence, two pathogenic mechanisms of chronic obstructive pulmonary disease (COPD). Decreased AUF-1 expression was described in bronchiolar epithelium of COPD patients versus controls and in vitro cytokine- and cigarette smoke-challenged human airway epithelial cells, prompting the identification of epithelial AUF-1-targeted transcripts and function, and investigation on the mechanism of its loss.

Results

RNA immunoprecipitation-sequencing (RIP-Seq) identified, in the human airway epithelial cell line BEAS-2B, 494 AUF-1-bound mRNAs enriched in their 3'-untranslated regions for a Guanine-Cytosine (GC)-rich binding motif. AUF-1 association with selected transcripts and with a synthetic GC-rich motif were validated by biotin pulldown. AUF-1-targets' steady-state levels were equally affected by partial or near-total AUF-1 loss induced by cytomix (TNFα/IL1β/IFNγ/10 nM each) and siRNA, respectively, with differential transcript decay rates. Cytomix-mediated decrease in AUF-1 levels in BEAS-2B and primary human small-airways epithelium (HSAEC) was replicated by treatment with the senescence- inducer compound etoposide and associated with readouts of cell-cycle arrest, increase in lysosomal damage and senescence-associated secretory phenotype (SASP) factors, and with AUF-1 transfer in extracellular vesicles, detected by transmission electron microscopy and immunoblotting. Extensive in-silico and genome ontology analysis found, consistent with AUF-1 functions, enriched RIP-Seq-derived AUF-1-targets in COPD-related pathways involved in inflammation, senescence, gene regulation and also in the public SASP proteome atlas; AUF-1 target signature was also significantly represented in multiple transcriptomic COPD databases generated from primary HSAEC, from lung tissue and from single-cell RNA-sequencing, displaying a predominant downregulation of expression.

Discussion

Loss of intracellular AUF-1 may alter posttranscriptional regulation of targets particularly relevant for protection of genomic integrity and gene regulation, thus concurring to airway epithelial inflammatory responses related to oxidative stress and accelerated aging. Exosomal-associated AUF-1 may in turn preserve bound RNA targets and sustain their function, participating to spreading of inflammation and senescence to neighbouring cells.

Design and Synthesis of Pyrazole-Based Macrocyclic Kinase Inhibitors Targeting BMPR2

Bone morphogenetic protein (BMP) signaling is mediated by transmembrane protein kinases that form heterotetramers consisting of type-I and type-II receptors. Upon BMP binding, the constitutively active type-II receptors activate specific type-I receptors by transphosphorylation, resulting in the phosphorylation of SMAD effector proteins. Drug discovery in the receptor tyrosine kinase-like (TKL) family has largely focused on type-I receptors, with few inhibitors that have been published targeting type-II receptors. BMPR2 is involved in several diseases, most notably pulmonary arterial hypertension, but also contributes to Alzheimer's disease and cancer. Here, we report that macrocyclization of the promiscuous inhibitor 1, based on a 3-amino-1H-pyrazole hinge binding moiety, led to a selective and potent BMPR2 inhibitor 8a.

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.

Adipokines, adiposity, and atherosclerosis

Characterized by a surplus of whole-body adiposity, obesity is strongly associated with the prognosis of atherosclerosis, a hallmark of coronary artery disease (CAD) and the major contributor to cardiovascular disease (CVD) mortality. Adipose tissue serves a primary role as a lipid-storage organ, secreting cytokines known as adipokines that affect whole-body metabolism, inflammation, and endocrine functions. Emerging evidence suggests that adipokines can play important roles in atherosclerosis development, progression, as well as regression. Here, we review the versatile functions of various adipokines in atherosclerosis and divide these respective functions into three major groups: protective, deteriorative, and undefined. The protective adipokines represented here are adiponectin, fibroblast growth factor 21 (FGF-21), C1q tumor necrosis factor-related protein 9 (CTRP9), and progranulin, while the deteriorative adipokines listed include leptin, chemerin, resistin, Interleukin- 6 (IL-6), and more, with additional adipokines that have unclear roles denoted as undefined adipokines. Comprehensively categorizing adipokines in the context of atherosclerosis can help elucidate the various pathways involved and potentially pave novel therapeutic approaches to treat CVDs.

The Role of Bone Morphogenetic Protein 4 in Microglial Polarization in the Process of Neuropathic Pain

Background

Neuropathic pain (NP) is known to be highly correlated with microglial polarization, of which the regulatory mechanism remains to be elucidated. Here, the aim of this study is to further investigate the relationship between bone morphogenetic protein 4 (BMP4) and microglial polarization in the process of NP.

Methods

Firstly, normal adult rats received intrathecal BMP4 administration to assess BMP4ʹs effect on microglial polarization. Secondly, a BMP4 antagonist – Noggin – was applied to a rat NP model achieved by L5 spinal nerve ligation (SNL) to investigate whether antagonizing BMP4 signaling could alleviate allodynia by reversing the imbalance of the M1/M2 polarization ratio. In both experiments, Von-Frey filaments were used to test the changes in the paw withdrawal threshold (PWT), and Western blotting, immuno-fluorescence, PCR and flow cytometry were further performed to investigate microglial activity and the expression patterns of M1 and M2 markers, respectively.

Results

Firstly, BMP4 administration induced a significant PWT decrease and microglial activation in normal rats; Western blotting, PCR and flow cytometry further revealed that M1 markers including CD16, MHCII, and TNF-α showed a marked elevation after BMP4 application; while M2 markers, such as Arg-1, CD204 and IL-4, peaked at an early stage (P1 or P4) and then fell to the Sham level on P7, leading to a persistent imbalance of the M1/M2 ratio throughout the 1st week. Secondly, Noggin treatment significantly relieved allodynia and microglial activation in SNL rats. Moreover, Noggin persistently downregulated the M1 marker levels and simultaneously induced a late-stage elevation of M2 markers expressions, thereby reversing the imbalance of the M1/M2 polarization ratio.

Conclusion

Our results indicate that BMP4 has the ability to induce microglial polarization. Antagonizing BMP4 signaling can relieve pain behavior via mitigating microglial activation and reversing the imbalance of the M1/M2 polarization ratio in the process of NP.

Signature transcriptome analysis of stage specific atherosclerotic plaques of patients

BACKGROUND

Inflammation plays an important role in all the stages of atherosclerotic plaque development. The current study aimed at assessing the altered expression of genes functioning in inflammation within the early stage (ES) and advanced stage (AS) atherosclerotic plaques obtained from patients undergoing coronary artery bypass grafting (CABG) surgery and identifying biomarker panel/s that may detect the status of plaque stages using peripheral blood samples.

METHODS

A section of ES and AS plaques and normal left internal mammary arteries (LIMA) were obtained from 8 patients undergoing the CABG surgery. Total RNA isolated was analyzed for mRNA and miRNA expression profile by Affymetrix arrays. A significant number of mRNAs was found to be differentially expressed in ES and AS plaque tissues relative to LIMA. The pathway analysis of differentially expressed mRNAs in the two plaque stages was also performed using DAVID Bioinformatics Database.

RESULTS

The mRNAs were found to be involved in critical inflammatory processes such as the toll-like receptor signaling pathway and cytokine-cytokine receptor interaction. Few miRNAs targeting these mRNAs were also altered in the two plaque conditions. QRT-PCR results showed a similar expression pattern of a few of the mRNAs and miRNAs in peripheral blood of the same patients relative to healthy controls.

CONCLUSION

Changes in mRNA and miRNA expression associated with various inflammatory processes occur in different atherosclerotic stage plaques as well as peripheral blood. Detection of such variations in patients' blood can be used as a possible prognostic tool to detect and/or predict the risk and stage of atherosclerosis.

The versatility and paradox of BMP signaling in endothelial cell behaviors and blood vessel function

Blood vessels expand via sprouting angiogenesis, and this process involves numerous endothelial cell behaviors, such as collective migration, proliferation, cell–cell junction rearrangements, and anastomosis and lumen formation. Subsequently, blood vessels remodel to form a hierarchical network that circulates blood and delivers oxygen and nutrients to tissue. During this time, endothelial cells become quiescent and form a barrier between blood and tissues that regulates transport of liquids and solutes. Bone morphogenetic protein (BMP) signaling regulates both proangiogenic and homeostatic endothelial cell behaviors as blood vessels form and mature. Almost 30 years ago, human pedigrees linked BMP signaling to diseases associated with blood vessel hemorrhage and shunts, and recent work greatly expanded our knowledge of the players and the effects of vascular BMP signaling. Despite these gains, there remain paradoxes and questions, especially with respect to how and where the different and opposing BMP signaling outputs are regulated. This review examines endothelial cell BMP signaling in vitro and in vivo and discusses the paradox of BMP signals that both destabilize and stabilize endothelial cell behaviors.

Stable flow-induced expression of KLK10 inhibits endothelial inflammation and atherosclerosis

Atherosclerosis preferentially occurs in arterial regions exposed to disturbed blood flow (d-flow), while regions exposed to stable flow (s-flow) are protected. The proatherogenic and atheroprotective effects of d-flow and s-flow are mediated in part by the global changes in endothelial cell (EC) gene expression, which regulates endothelial dysfunction, inflammation, and atherosclerosis. Previously, we identified kallikrein-related peptidase 10 (Klk10, a secreted serine protease) as a flow-sensitive gene in mouse arterial ECs, but its role in endothelial biology and atherosclerosis was unknown. Here, we show that KLK10 is upregulated under s-flow conditions and downregulated under d-flow conditions using in vivo mouse models and in vitro studies with cultured ECs. Single-cell RNA sequencing (scRNAseq) and scATAC sequencing (scATACseq) study using the partial carotid ligation mouse model showed flow-regulated Klk10 expression at the epigenomic and transcription levels. Functionally, KLK10 protected against d-flow-induced permeability dysfunction and inflammation in human artery ECs, as determined by NFκB activation, expression of vascular cell adhesion molecule 1 and intracellular adhesion molecule 1, and monocyte adhesion. Furthermore, treatment of mice in vivo with rKLK10 decreased arterial endothelial inflammation in d-flow regions. Additionally, rKLK10 injection or ultrasound-mediated transfection of Klk10-expressing plasmids inhibited atherosclerosis in Apoe-/- mice. Moreover, KLK10 expression was significantly reduced in human coronary arteries with advanced atherosclerotic plaques compared to those with less severe plaques. KLK10 is a flow-sensitive endothelial protein that serves as an anti-inflammatory, barrier-protective, and anti-atherogenic factor.

The role of TGF-β or BMPR2 signaling pathway-related miRNA in pulmonary arterial hypertension and systemic sclerosis

Pulmonary arterial hypertension (PAH) is a severe complication of connective tissue disease (CTD), causing death in systemic sclerosis (SSc). The past decade has yielded many scientific insights into microRNA (miRNAs) in PAH and SSc. This growth of knowledge has well-illustrated the complexity of microRNA (miRNA)-based regulation of gene expression in PAH. However, few miRNA-related SSc-PAH were elucidated. This review firstly discusses the role of transforming growth factor-beta (TGF-β) signaling and bone morphogenetic protein receptor type II (BMPR2) in PAH and SSc. Secondly, the miRNAs relating to TGF-β and BMPR2 signaling pathways in PAH and SSc or merely PAH were subsequently summarized. Finally, future studies might develop early diagnostic biomarkers and target-oriented therapeutic strategies for SSc-PAH and PAH treatment.

A review of BMP and Wnt signaling pathway in the pathogenesis of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic disease characterized by a progressive elevation in mean pulmonary arterial pressure. This occurs due to abnormal remodeling of small peripheral lung vasculature resulting in progressive occlusion of the artery lumen that eventually causes right heart failure and death. Current therapeutic options for PAH are limited and focused mainly on reversal of pulmonary vasoconstriction and proliferation of vascular cells. Although these treatments can relieve disease symptoms, PAH remains a progressive lethal disease.Bone morphogenetic proteins (BMPs) and their receptors were required for PAH-induced right ventricular hypertrophy. Emerging data suggest that restoration of BMP type II receptor (BMPR2) signaling in PAH is a promising alternative that could prevent and reverse pulmonary vascular remodeling. BMPR2 mutations have been identified in >70% of familial and roughly 15% of sporadic PAH cases. Wingless (Wnt) are a family of secreted glycoproteins with varying expression patterns and a range of functions, Wnt signaling pathway is divided into canonical signaling pathway and non-canonical signaling pathway. A recent study reports that interaction between BMP and Wnt closely associated with lung development, those cascade coordination regulation stem cell fate which determine lung branching morphogenes. The promoting effect of BMPR2 on proliferation, survival, and motility of endothelial cells was through recruiting Wnts signaling pathway, the interaction between BMP and Wnt closely associated with lung development.Therefore, in this review, we outline the latest advances of BMP and Wnt signaling pathway in the pathogenesis of PAH and disease progression.

The biology of bone morphogenetic protein signaling pathway in cerebrovascular system

Bone morphogenetic protein belongs to transcription growth factor superfamily β; bone morphogenetic protein signal pathway regulates cell proliferation, differentiation, and apoptosis among different tissues. Cerebrovascular system supplies sufficient oxygen and blood into brain to maintain its normal function. The disorder of cerebrovascular system will result into serious cerebrovascular diseases, which is gradually becoming a major threat to human health in modern society. In recent decades, many studies have revealed the underlying biology and mechanism of bone morphogenetic protein signal pathway played in cerebrovascular system. This review will discuss the relationship between the two aspects, aiming to provide new perspective for non-invasive treatment and basic research of cerebrovascular diseases.

The Relationship Between Circulating Bone Morphogenetic Protein-4 and Inflammation Cytokines in Patients Undergoing Thoracic Surgery: A Prospective Randomized Study

Background

Bone morphogenetic protein-4 (BMP4) has been identified as an inflammation regulator in the diseases of arteries and other organs. However, the relationship between circulating BMP4 and perioperative inflammation remains unclear.

Patients and Methods

Forty patients undergoing lobectomy were randomly allocated into the Control group (not receiving flurbiprofen) and the Flurb group (received 100mg flurbiprofen during surgery). Arterial blood was obtained before surgery (T1), at the end of surgery (T2), and 24 hours after surgery (T3) to test the plasma concentrations of BMP4, its antagonist Noggin, interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), and IL-10. The relationship between BMP4 and other variables and the effects of flurbiprofen on BMP4 changes were investigated.

Results

A total of 35 patients were included. Circulating BMP4 was positively correlated with IL-1β (P<0.01, r=0.575) and TNF-α (P<0.01, r=0.491), negatively correlated with IL-10 (P<0.01, r=−0.675), but not correlated with Noggin. The plasma concentrations of BMP4, IL-1β, and TNF-α increased at T2 (P<0.01, compared with T1) and decreased at T3 (P<0.05, compared with T2). BMP4 concentrations at T3 were significantly higher than at T1 in the Control group (P<0.05), while showing no significant difference in the Flurb group. However, in the Flurb group, the relative changes of BMP4 and IL-1β at T2 and T3 were significantly lower than those in the Control group.

Conclusion

Circulating BMP4 was elevated during surgery and highly correlated with inflammation cytokines. The elevation of BMP4 and inflammatory cytokines could be alleviated by flurbiprofen, indicating that BMP4 may exert pro-inflammatory properties via cyclooxygenase-II signaling pathways.

Inflammatory Mechanisms Contributing to Endothelial Dysfunction

Maintenance of endothelial cell integrity is an important component of human health and disease since the endothelium can perform various functions including regulation of vascular tone, control of hemostasis and thrombosis, cellular adhesion, smooth muscle cell proliferation, and vascular inflammation. Endothelial dysfunction is encompassed by complex pathophysiology that is based on endothelial nitric oxide synthase uncoupling and endothelial activation following stimulation from various inflammatory mediators (molecular patterns, oxidized lipoproteins, cytokines). The downstream signaling via nuclear factor-κB leads to overexpression of adhesion molecules, selectins, and chemokines that facilitate leukocyte adhesion, rolling, and transmigration to the subendothelial space. Moreover, oscillatory shear stress leads to pro-inflammatory endothelial activation with increased monocyte adhesion and endothelial cell apoptosis, an effect that is dependent on multiple pathways and flow-sensitive microRNA regulation. Moreover, the role of neutrophil extracellular traps and NLRP3 inflammasome as inflammatory mechanisms contributing to endothelial dysfunction has recently been unveiled and is under further investigation. Consequently, and following their activation, injured endothelial cells release inflammatory mediators and enter a pro-thrombotic state through activation of coagulation pathways, downregulation of thrombomodulin, and an increase in platelet adhesion and aggregation owing to the action of von-Willebrand factor, ultimately promoting atherosclerosis progression.

Serum anti-DIDO1, anti-CPSF2, and anti-FOXJ2 antibodies as predictive risk markers for acute ischemic stroke

BACKGROUND

Acute ischemic stroke (AIS) is a serious cause of mortality and disability. AIS is a serious cause of mortality and disability. Early diagnosis of atherosclerosis, which is the major cause of AIS, allows therapeutic intervention before the onset, leading to prevention of AIS.

METHODS

Serological identification by cDNA expression cDNA libraries and the protein array method were used for the screening of antigens recognized by serum IgG antibodies in patients with atherosclerosis. Recombinant proteins or synthetic peptides derived from candidate antigens were used as antigens to compare serum IgG levels between healthy donors (HDs) and patients with atherosclerosis-related disease using the amplified luminescent proximity homogeneous assay-linked immunosorbent assay.

RESULTS

The first screening using the protein array method identified death-inducer obliterator 1 (DIDO1), forkhead box J2 (FOXJ2), and cleavage and polyadenylation specificity factor (CPSF2) as the target antigens of serum IgG antibodies in patients with AIS. Then, we prepared various antigens including glutathione S-transferase-fused DIDO1 protein as well as peptides of the amino acids 297-311 of DIDO1, 426-440 of FOXJ2, and 607-621 of CPSF2 to examine serum antibody levels. Compared with HDs, a significant increase in antibody levels of the DIDO1 protein and peptide in patients with AIS, transient ischemic attack (TIA), and chronic kidney disease (CKD) but not in those with acute myocardial infarction and diabetes mellitus (DM). Serum anti-FOXJ2 antibody levels were elevated in most patients with atherosclerosis-related diseases, whereas serum anti-CPSF2 antibody levels were associated with AIS, TIA, and DM. Receiver operating characteristic curves showed that serum DIDO1 antibody levels were highly associated with CKD, and correlation analysis revealed that serum anti-FOXJ2 antibody levels were associated with hypertension. A prospective case-control study on ischemic stroke verified that the serum antibody levels of the DIDO1 protein and DIDO1, FOXJ2, and CPSF2 peptides showed significantly higher odds ratios with a risk of AIS in patients with the highest quartile than in those with the lowest quartile, indicating that these antibody markers are useful as risk factors for AIS.

CONCLUSIONS

Serum antibody levels of DIDO1, FOXJ2, and CPSF2 are useful in predicting the onset of atherosclerosis-related AIS caused by kidney failure, hypertension, and DM, respectively.

Significance of BMPR2 mutations in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a debilitating disease that results from progressive remodeling and inflammation of pulmonary arteries. PAH develops gradually, is difficult to diagnose, and has a high mortality rate. Although mutation in the bone morphogenetic protein receptor 2 (BMPR2) gene has been identified as the main genetic cause of PAH, the underlying pathways involving the pathophysiology of PAH are complex and still not fully understood. Endothelial dysfunction has been observed in PAH development that results in a multitude of disturbances in the cellular processes in pulmonary vessels. Changes in the pulmonary vasculature caused by the disruption of BMPR2 signaling are observed in three main vascular components; endothelial cells, smooth muscle cells, and fibroblasts. BMPR2 also has a prominent role in maintenance of the immune system. The disruption of BMPR2 signaling pathway causes an increased degree of inflammation and decreases the ability of the immune system to resolve it. Inflammatory processes and changes in pulmonary vasculature interact with one another, resulting in the progression of chronic PAH. In this review, we highlight the various components of vascular remodeling and immune response that are caused by disruption of BMPR2 signaling, including the clinical evidence and the prospects of these components as a potential target for PAH therapy. Indeed, development of drugs to target the pathogenic pathways involved in PAH may complement existing treatment regimens and improve patient prognosis.

Sex Dimorphism in Pulmonary Hypertension: The Role of the Sex Chromosomes

Pulmonary hypertension (PH) is a condition characterised by an abnormal elevation of pulmonary artery pressure caused by an increased pulmonary vascular resistance, frequently leading to right ventricular failure and reduced survival. Marked sexual dimorphism is observed in patients with pulmonary arterial hypertension, a form of pulmonary hypertension with a particularly severe clinical course. The incidence in females is 2-4 times greater than in males, although the disease is less severe in females. We review the contribution of the sex chromosomes to this sex dimorphism highlighting the impact of proteins, microRNAs and long non-coding RNAs encoded on the X and Y chromosomes. These genes are centrally involved in the cellular pathways that cause increased pulmonary vascular resistance including the production of reactive oxygen species, altered metabolism, apoptosis, inflammation, vasoconstriction and vascular remodelling. The interaction with genetic mutations on autosomal genes that cause heritable pulmonary arterial hypertension such as bone morphogenetic protein 2 (BMPR2) are examined. The mechanisms that can lead to differences in the expression of genes located on the X chromosomes between females and males are also reviewed. A better understanding of the mechanisms of sex dimorphism in this disease will contribute to the development of more effective therapies for both women and men.

Protective effect of baicalin against pulmonary arterial hypertension vascular remodeling through regulation of TNF-α signaling pathway

Pulmonary arterial hypertension (PAH) is a progressive cardiovascular disease with high mortality. However, there were no efficient medical drugs for PAH to enormously improve the survival and quality of life measures. The present study aimed to explore the protective effect of baicalin against experimental PAH in vivo and vitro. All the experimental rats received intraperitoneal injection of monocrotaline (MCT) to induce PAH model. Baicalin was given by intragastric administration from 2 days after MCT injection. Forty animals were randomly divided into four groups: Control, MCT, saline-, and baicalin-treated groups (n = 10 in each). Post-operation, hemodynamic data, and index of right ventricular hypertrophy (RVHI) were recorded to evaluate the inhibition of baicalin on MCT-induced PAH. Furthermore, pulmonary artery smooth muscle cells (PASMCs) model induced by tumor necrosis factor-α (TNF-α) was used to observe the inhibition of vascular cells proliferation in vitro. The results demonstrated that baicalin significantly attenuated MCT-induced right ventricular systolic pressure (RVSP), the index of right ventricular hypertrophy, and vessel wall thickness; inhibit inflammatory and cell proliferation induced by MCT or TNF-α, respectively. In addition, we found that baicalin might protect against experimental PAH via regulating the TNF-α/BMPR2 signaling pathway.

Approaches to treat pulmonary arterial hypertension by targeting bmpr2 - from cell membrane to nucleus

Pulmonary arterial hypertension (PAH) is estimated to affect between 10-50 people per million worldwide. The lack of cure and devastating nature of the disease means that treatment is crucial to arrest rapid clinical worsening. Current therapies are limited by their focus on inhibiting residual vasoconstriction rather than targeting key regulators of the cellular pathology. Potential disease-modifying therapies may come from research directed towards causal pathways involved in the cellular and molecular mechanisms of disease. It is widely acknowledged, that targeting reduced expression of the critical bone morphogenetic protein type-2 receptor (BMPR2) and its associated signalling pathways is a compelling therapeutic avenue to explore. In this review we highlight the advances that have been made in understanding this pathway and the therapeutics that are being tested in clinical trials and the clinic to treat PAH.

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.

3D curvature-instructed endothelial flow response and tissue vascularization

Vascularization remains a long-standing challenge in engineering complex tissues. Particularly needed is recapitulating 3D vascular features, including continuous geometries with defined diameter, curvature, and torsion. Here, we developed a spiral microvessel model that allows precise control of curvature and torsion and supports homogeneous tissue perfusion at the centimeter scale. Using this system, we showed proof-of-principle modeling of tumor progression and engineered cardiac tissue vascularization. We demonstrated that 3D curvature induced rotation and mixing under laminar flow, leading to unique phenotypic and transcriptional changes in endothelial cells (ECs). Bulk and single-cell RNA-seq identified specific EC gene clusters in spiral microvessels. These mark a proinflammatory phenotype associated with vascular development and remodeling, and a unique cell cluster expressing genes regulating vascular stability and development. Our results shed light on the role of heterogeneous vascular structures in differential development and pathogenesis and provide previously unavailable tools to potentially improve tissue vascularization and regeneration.

Protective effects of isorhamnetin on pulmonary arterial hypertension: in vivo and in vitro studies

Pulmonary arterial hypertension (PAH) is a malignant disease with high mortality and closely involves the bone morphogenetic protein (BMP) pathway. Mutations in BMPR2 caused proliferation of pulmonary artery smooth muscle cells (PASMCs) leading to PAH. Isorhamnetin, one of the main naturally occurring flavonoids extracted from Hippophae rhamnoides L, shows antiinflammatory and anti-proliferative properties. Nevertheless, the effects of isorhamnetin on PAH remain unclear. This study aimed to investigate whether isorhamnetin has protective effects against PAH and explore possible mechanisms. An in vivo model of PAH induced by monocrotaline (MCT) was employed, and sildenafil and isorhamnetin were orally administered for 21 consecutive days. An in vitro model induced by TNF-α was employed, and cell proliferation of HPASMCs was detected. Results indicated that isorhamnetin significantly improved hemodynamic, histopathological, and echocardiographic changes in MCT-induced PAH in rats. In vitro, isorhamnetin suppressed TNF-α-induced HPASMCs proliferation. Furthermore, isorhamnetin improved protein expression of BMPR2 and suppressed protein expression of TNF-α and IL-6 in rat lungs. Isorhamnetin improved protein expression of BMPR2 and p-smad1/5 and mRNA expression of Id1 and Id3 in HPASMCs. Isorhamnetin ameliorated MCT-induced PAH in rats and inhibited TNF-α-induced HPASMCs proliferation by a mechanism likely involving the regulation of the BMP signaling pathway.

Endothelial responses to shear stress in atherosclerosis: a novel role for developmental genes

Flowing blood generates a frictional force called shear stress that has major effects on vascular function. Branches and bends of arteries are exposed to complex blood flow patterns that exert low or low oscillatory shear stress, a mechanical environment that promotes vascular dysfunction and atherosclerosis. Conversely, physiologically high shear stress is protective. Endothelial cells are critical sensors of shear stress but the mechanisms by which they decode complex shear stress environments to regulate physiological and pathophysiological responses remain incompletely understood. Several laboratories have advanced this field by integrating specialized shear-stress models with systems biology approaches, including transcriptome, methylome and proteome profiling and functional screening platforms, for unbiased identification of novel mechanosensitive signalling pathways in arteries. In this Review, we describe these studies, which reveal that shear stress regulates diverse processes and demonstrate that multiple pathways classically known to be involved in embryonic development, such as BMP-TGFβ, WNT, Notch, HIF1α, TWIST1 and HOX family genes, are regulated by shear stress in arteries in adults. We propose that mechanical activation of these pathways evolved to orchestrate vascular development but also drives atherosclerosis in low shear stress regions of adult arteries.

Endothelial responses to shear stress in atherosclerosis: a novel role for developmental genes

Flowing blood generates a frictional force called shear stress that has major effects on vascular function. Branches and bends of arteries are exposed to complex blood flow patterns that exert low or low oscillatory shear stress, a mechanical environment that promotes vascular dysfunction and atherosclerosis. Conversely, physiologically high shear stress is protective. Endothelial cells are critical sensors of shear stress but the mechanisms by which they decode complex shear stress environments to regulate physiological and pathophysiological responses remain incompletely understood. Several laboratories have advanced this field by integrating specialized shear-stress models with systems biology approaches, including transcriptome, methylome and proteome profiling and functional screening platforms, for unbiased identification of novel mechanosensitive signalling pathways in arteries. In this Review, we describe these studies, which reveal that shear stress regulates diverse processes and demonstrate that multiple pathways classically known to be involved in embryonic development, such as BMP-TGFβ, WNT, Notch, HIF1α, TWIST1 and HOX family genes, are regulated by shear stress in arteries in adults. We propose that mechanical activation of these pathways evolved to orchestrate vascular development but also drives atherosclerosis in low shear stress regions of adult arteries.

BMPR2 acts as a gatekeeper to protect endothelial cells from increased TGFβ responses and altered cell mechanics

Balanced transforming growth factor-beta (TGFβ)/bone morphogenetic protein (BMP)-signaling is essential for tissue formation and homeostasis. While gain in TGFβ signaling is often found in diseases, the underlying cellular mechanisms remain poorly defined. Here we show that the receptor BMP type 2 (BMPR2) serves as a central gatekeeper of this balance, highlighted by its deregulation in diseases such as pulmonary arterial hypertension (PAH). We show that BMPR2 deficiency in endothelial cells (ECs) does not abolish pan-BMP-SMAD1/5 responses but instead favors the formation of mixed-heteromeric receptor complexes comprising BMPR1/TGFβR1/TGFβR2 that enable enhanced cellular responses toward TGFβ. These include canonical TGFβ-SMAD2/3 and lateral TGFβ-SMAD1/5 signaling as well as formation of mixed SMAD complexes. Moreover, BMPR2-deficient cells express genes indicative of altered biophysical properties, including up-regulation of extracellular matrix (ECM) proteins such as fibrillin-1 (FBN1) and of integrins. As such, we identified accumulation of ectopic FBN1 fibers remodeled with fibronectin (FN) in junctions of BMPR2-deficient ECs. Ectopic FBN1 deposits were also found in proximity to contractile intimal cells in pulmonary artery lesions of BMPR2-deficient heritable PAH (HPAH) patients. In BMPR2-deficient cells, we show that ectopic FBN1 is accompanied by active β1-integrin highly abundant in integrin-linked kinase (ILK) mechano-complexes at cell junctions. Increased integrin-dependent adhesion, spreading, and actomyosin-dependent contractility facilitates the retrieval of active TGFβ from its latent fibrillin-bound depots. We propose that loss of BMPR2 favors endothelial-to-mesenchymal transition (EndMT) allowing cells of myo-fibroblastic character to create a vicious feed-forward process leading to hyperactivated TGFβ signaling. In summary, our findings highlight a crucial role for BMPR2 as a gatekeeper of endothelial homeostasis protecting cells from increased TGFβ responses and integrin-mediated mechano-transduction.

Inhibition of lysine-specific demethylase 1A suppresses neointimal hyperplasia by targeting bone morphogenetic protein 2 and mediating vascular smooth muscle cell phenotype

OBJECTIVES

Vascular disorders are associated with phenotypical switching of vascular smooth muscle cells (VSMCs). We investigated the effect of bone morphogenetic protein (BMP)-2 in controlling VSMC phenotype and vascular disorder progression. Lysine (K)-specific demethylase 1A (KDM1A) has been identified to target BMP-2 and is employed as a therapeutic means of regulating BMP-2 expression in VSMCs.

MATERIALS AND METHODS

VSMCs were stimulated with angiotensin II, and the expression of KDM1A and BMP-2 was detected. VSMC proliferation, apoptosis, and phenotype were evaluated. An in vivo aortic injury model was established, and VSMC behaviour was evaluated by the expression of key markers. The activation of BMP-2-associated signalling pathways was examined.

RESULTS

We confirmed the inhibitory effect of KDM1A on BMP-2 activity and demonstrated that KDM1A inhibition prevented VSMC transformation from a contractile to synthetic phenotype. In angiotensin II-treated VSMCs, KDM1A inhibition triggered a decrease in cell proliferation and inflammatory response. In vivo, KDM1A inhibition alleviated post-surgery neointimal formation and collagen deposition, preventing VSMCs from switching into a synthetic phenotype and suppressing disease onset. These processes were mediated by BMP-2 through canonical small mothers against decapentaplegic signalling, which was associated with the activation of BMP receptors 1A and 1B.

CONCLUSIONS

The regulatory correlation between KDM1A and BMP-2 offers insights into vascular remodelling and VSMC phenotypic modulation. The reported findings contribute to the development of innovative strategies against vascular disorders.

Smooth Muscle Contact Drives Endothelial Regeneration by BMPR2-Notch1-Mediated Metabolic and Epigenetic Changes

RATIONALE

Maintaining endothelial cells (EC) as a monolayer in the vessel wall depends on their metabolic state and gene expression profile, features influenced by contact with neighboring cells such as pericytes and smooth muscle cells (SMC). Failure to regenerate a normal EC monolayer in response to injury can result in occlusive neointima formation in diseases such as atherosclerosis and pulmonary arterial hypertension.

OBJECTIVE

We investigated the nature and functional importance of contact-dependent communication between SMC and EC to maintain EC integrity.

METHODS AND RESULTS

We found that in SMC and EC contact cocultures, BMPR2 (bone morphogenetic protein receptor 2) is required by both cell types to produce collagen IV to activate ILK (integrin-linked kinase). This enzyme directs p-JNK (phospho-c-Jun N-terminal kinase) to the EC membrane, where it stabilizes presenilin1 and releases N1ICD (Notch1 intracellular domain) to promote EC proliferation. This response is necessary for EC regeneration after carotid artery injury. It is deficient in EC-SMC Bmpr2 double heterozygous mice in association with reduced collagen IV production, decreased N1ICD, and attenuated EC proliferation, but can be rescued by targeting N1ICD to EC. Deletion of EC- Notch1 in transgenic mice worsens hypoxia-induced pulmonary hypertension, in association with impaired EC regenerative function associated with loss of precapillary arteries. We further determined that N1ICD maintains EC proliferative capacity by increasing mitochondrial mass and by inducing the phosphofructokinase PFKFB3 (fructose-2,6-bisphosphatase 3). Chromatin immunoprecipitation sequencing analyses showed that PFKFB3 is required for citrate-dependent H3K27 acetylation at enhancer sites of genes regulated by the acetyl transferase p300 and by N1ICD or the N1ICD target MYC and necessary for EC proliferation and homeostasis.

CONCLUSIONS

Thus, SMC-EC contact is required for activation of Notch1 by BMPR2, to coordinate metabolism with chromatin remodeling of genes that enable EC regeneration, and to maintain monolayer integrity and vascular homeostasis in response to injury.

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.

Neutrophil extracellular traps and fibrocytes in ST-segment elevation myocardial infarction

Leukocyte-mediated inflammation is central in atherothrombosis and ST-segment elevation myocardial infarction (STEMI). Neutrophil extracellular traps (NETs) have been shown to enhance atherothrombosis and stimulate fibroblast function. We analyzed the effects of NETs on cardiac remodeling after STEMI. We measured double-stranded (ds)DNA and citrullinated histone H3 (citH3) as NET surrogate markers in human culprit site and femoral blood collected during primary percutaneous coronary intervention (n = 50). Fibrocytes were characterized in whole blood by flow cytometry, and in culprit site thrombi and myocardium by immunofluorescence. To investigate mechanisms of fibrocyte activation, isolated NETs were used to induce fibrocyte responses in vitro. Enzymatic infarct size was assessed using creatine-phosphokinase isoform MB area under the curve. Left ventricular function was measured by transthoracic echocardiography. NET surrogate markers were increased at the culprit site compared to the femoral site and were positively correlated with infarct size and left ventricular dysfunction at follow-up. In vitro, NETs promoted fibrocyte differentiation from monocytes and induced fibrocyte activation. Highly activated fibrocytes accumulated at the culprit site and in the infarct transition zone. Our data suggest that NETs might be important mediators of fibrotic remodeling after STEMI, possibly by stimulating fibrocytes.

Inflammation induces endothelial-to-mesenchymal transition and promotes vascular calcification through downregulation of BMPR2

Endothelial‐to‐mesenchymal transition (EndMT) has been unveiled as a common cause for a multitude of human pathologies, including cancer and cardiovascular disease. Vascular calcification is a risk factor for ischemic vascular disorders and slowing calcification may reduce mortality in affected patients. The absence of early biomarkers hampers the identification of patients at risk. EndMT and vascular calcification are induced upon cooperation between distinct stimuli, including inflammatory cytokines and transforming growth factor beta (TGF‐β) family members. However, how these signaling pathways interplay to promote cell differentiation and eventually vascular calcification is not well understood. Using in vitro and ex vivo analysis in animal models and patient‐derived tissues, we have identified that the pro‐inflammatory cytokines tumor necrosis factor alpha (TNF‐α) and interleukin‐1 beta (IL‐1β) induce EndMT in human primary aortic endothelial cells, thereby sensitizing them for BMP‐9‐induced osteogenic differentiation. Downregulation of the BMP type II receptor BMPR2 is a key event in this process. Rather than compromising BMP canonical signal transduction, loss of BMPR2 results in decreased JNK signaling in ECs, thus enhancing BMP‐9‐induced mineralization. Altogether, our results point at the BMPR2–JNK signaling axis as a key pathway regulating inflammation‐induced EndMT and contributing to calcification. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Epsin15 Homology Domains: Role in the Pathogenesis of Pulmonary Arterial Hypertension

Intersectin-1s (ITSN) deficiency and expression of a biologically active ITSN fragment, result of granzyme B cleavage under inflammatory conditions associated with pulmonary arterial hypertension (PAH), are characteristics of lung tissue of human and animal models of PAH. Recently, we have shown that this ITSN fragment comprising two Epsin15 homology domains (EH_ITSN) triggers endothelial cell (EC) proliferation and the plexiform arteriopathy in PAH. Limited evidence also indicates that the EH domains of endocytic proteins such as ITSN, upregulate compensatory endocytic pathways in cells with impaired vesicular trafficking. Thus, we sought to investigate whether the EH_ITSN may be involved in this compensatory mechanism for improving the EC endocytic dysfunction induced by ITSN deficiency and possibly contribute to PAH pathogenesis. We used stably-transfected human pulmonary artery ECs expressing the Myc-EH_ITSN (EC_EH-ITSN) and ITSN knockout heterozygous mice (K0^ITSN+/-) transduced with the Myc-EH_ITSN, in conjunction with functional assays: the biotin assay for caveolae internalization and 8 nm gold (Au)- and dinitrophenylated (DNP)-albumin perfusion of murine lung microvasculature. Pulmonary artery ECs of PAH patients (EC_PAH), ITSN knockdown ECs (EC_KD-ITSN), the monocrotaline (MCT)-induced mouse and rat models of PAH, as well as untreated animals, served as controls. ELISA via streptavidin-HRP or anti-DNP antibody (Ab), applied on ECs and lung lysates indicated greater than 30% increase in biotin internalization in EC_EH-ITSN compared to EC_Ctrl. Despite their endocytic deficiency, EC_PAH internalized biotin similar to EC_Ctrl which is twofold higher compared to EC_KD-ITSN. Moreover, the lung microvascular bed of Myc-EH_ITSN-transduced mice and MCT-treated animals showed greater than twofold increase in DNP-BSA transendothelial transport, all compared to untreated controls. Electron microscopy (EM) revealed the increased occurrence of non-conventional endocytic/transcytotic structures (i.e., caveolae clusters, tubulo-vesicular and enlarged endocytic structures, membranous rings), usually underrepresented. Most of these structures were labeled by Au-BSA, consistent with their involvement in the transendothelial transport. Furthermore, ITSN deficiency and EH_ITSN expression alter the subcellular localization of the EH-binding protein 1 (EHBP1) and cortical actin organization, altogether supporting the increase occurrence/trafficking of the alternative endocytic structures. Thus, the EH_ITSN by shifting the physiological vesicular (caveolae) transport toward the alternative endocytic pathways is a significant contributor to the dysfunctional molecular phenotype of EC_PAH.

Consequences of BMPR2 Deficiency in the Pulmonary Vasculature and Beyond: Contributions to Pulmonary Arterial Hypertension

Since its association with familial pulmonary arterial hypertension (PAH) in 2000, Bone Morphogenetic Protein Receptor II (BMPR2) and its related signaling pathway have become recognized as a key regulator of pulmonary vascular homeostasis. Herein, we define BMPR2 deficiency as either an inactivation of the receptor, decreased receptor expression, or an impairment of the receptor’s downstream signaling pathway. Although traditionally the phenotypic consequences of BMPR2 deficiency in PAH have been thought to be limited to the pulmonary vasculature, there is evidence that abnormalities in BMPR2 signaling may have consequences in many other organ systems and cellular compartments. Revisiting how BMPR2 functions throughout health and disease in cells and organs beyond the lung vasculature may provide insight into the contribution of these organ systems to PAH pathogenesis as well as the potential systemic manifestation of PAH. Here we review our knowledge of the consequences of BMPR2 deficiency across multiple organ systems.

Bone Morphogenetic Proteins in Vascular Homeostasis and Disease

It is well established that control of vascular morphogenesis and homeostasis is regulated by vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), Delta-like 4 (Dll4), angiopoietin, and ephrin signaling. It has become clear that signaling by bone morphogenetic proteins (BMPs), which have a long history of studies in bone and early heart development, are also essential for regulating vascular function. Indeed, mutations that cause deregulated BMP signaling are linked to two human vascular diseases, hereditary hemorrhagic telangiectasia and pulmonary arterial hypertension. These observations are corroborated by data obtained with vascular cells in cell culture and in mouse models. BMPs are required for normal endothelial cell differentiation and for venous/arterial and lymphatic specification. In adult life, BMP signaling orchestrates neo-angiogenesis as well as vascular inflammation, remodeling, and calcification responses to shear and oxidative stress. This review emphasizes the pivotal role of BMPs in the vascular system, based on studies of mouse models and human vascular disorders.

Effect of different combination of maternal and postnatal diet on adipose tissue morphology in male rat offspring

PURPOSE

Adipose tissue expansion can occur through several different ways and, under certain conditions, can be connected with chronic inflammation. TNF-α is one of the important cytokines involved in this process. Prolonged inflammation in obesity can lead to obesity-related insulin resistance and tissue dysfunction. The aim of our study was to investigate how different combination of maternal and postnatal diet affects offspring adipose tissue morphology and adipose tissue TNF-α expression.

METHODS

Ten female Sprague Dawley rats, 9 weeks old, were randomly divided into two groups and fed either standard laboratory chow or food rich in saturated fatty acids during 6 weeks and then mated with the same male rat. After birth and lactation male rat offspring from both groups were divided into four subgroups depending on the diet they were fed until 22 weeks old. Samples of white adipose tissue were taken from the subcutaneous, epididymal, and perirenal fat pad. On tissue sections, histomorphometric analysis was conducted using CellProfiler program v 2.1.1, and immunohistochemical staining for TNF-α was performed.

RESULTS

Greater mean surface area of subcutaneous and epididymal adipocytes was found in groups of male rat offspring with altered diet. In perirenal adipose tissue, the highest number of adipocytes was measured in the group where both mother and offspring were fed a high-fat diet. Adipocyte staining intensity for TNF-α did not differ significantly between the groups.

CONCLUSIONS

Together with our previously published data, our results lead to the conclusion that alteration of postnatal diet can lead to TNF-α and adipocyte morphology changes.

Accelerated atherosclerosis development in C57Bl6 mice by overexpressing AAV-mediated PCSK9 and partial carotid ligation

Studying the role of a particular gene in atherosclerosis typically requires a time-consuming and often difficult process of generating double knockouts or transgenics on ApoE^-/- or LDL receptor (LDLR)^-/- background. Recently, it was reported that adeno-associated-virus-8 (AAV8)-mediated overexpression of PCSK9 (AAV8-PCSK9) rapidly induced hyperlipidemia. However, using this method in C57BL6 wild-type (C57) mice, it took ~3 months to develop atherosclerosis. Our partial carotid ligation model is used to rapidly develop atherosclerosis by inducing disturbed flow in the left common carotid artery within 2 weeks in ApoE^-/- or LDLR^-/- mice. Here, we combined these two approaches to develop an accelerated model of atherosclerosis in C57 mice. C57 mice were injected with AAV9-PCSK9 or AAV9-luciferase (control) and high-fat diet was initiated. A week later, partial ligation was performed. Compared to the control, AAV-PCSK9 led to elevated serum PCSK9, hypercholesterolemia, and rapid atherosclerosis development within 3 weeks as determined by gross plaque imaging, and staining with Oil-Red-O, Movat's pentachrome, and CD45 antibody. These plaque lesions were comparable to the atherosclerotic lesions that have been previously observed in ApoE^-/- or LDLR^-/- mice that were subjected to partial carotid ligation and high-fat diet. Next, we tested whether our method can be utilized to rapidly determine the role of a particular gene in atherosclerosis. Using eNOS^-/- and NOX1^-/y mice on C57 background, we found that the eNOS^-/- mice developed more advanced lesions, while the NOX1^-/y mice developed less atherosclerotic lesions as compared to the C57 controls. These results are consistent with the previous findings using double knockouts (eNOS^-/-_ApoE^-/- and NOX1^-/y_ApoE^-/-). AAV9-PCSK9 injection followed by partial carotid ligation is an effective and time-saving approach to rapidly induce atherosclerosis. This accelerated model is well-suited to quickly determine the role of gene(s) interest without generating double or triple knockouts.

Induced Pluripotent Stem Cell Model of Pulmonary Arterial Hypertension Reveals Novel Gene Expression and Patient Specificity

RATIONALE

Idiopathic or heritable pulmonary arterial hypertension is characterized by loss and obliteration of lung vasculature. Endothelial cell dysfunction is pivotal to the pathophysiology, but different causal mechanisms may reflect a need for patient-tailored therapies.

OBJECTIVES

Endothelial cells differentiated from induced pluripotent stem cells were compared with pulmonary arterial endothelial cells from the same patients with idiopathic or heritable pulmonary arterial hypertension, to determine whether they shared functional abnormalities and altered gene expression patterns that differed from those in unused donor cells. We then investigated whether endothelial cells differentiated from pluripotent cells could serve as surrogates to test emerging therapies.

METHODS

Functional changes assessed included adhesion, migration, tube formation, and propensity to apoptosis. Expression of bone morphogenetic protein receptor type 2 (BMPR2) and its target, collagen IV, signaling of the phosphorylated form of the mothers against decapentaplegic proteins (pSMAD1/5), and transcriptomic profiles were also analyzed.

MEASUREMENTS AND MAIN RESULTS

Native pulmonary arterial and induced pluripotent stem cell-derived endothelial cells from patients with idiopathic and heritable pulmonary arterial hypertension compared with control subjects showed a similar reduction in adhesion, migration, survival, and tube formation, and decreased BMPR2 and downstream signaling and collagen IV expression. Transcriptomic profiling revealed high kisspeptin 1 (KISS1) related to reduced migration and low carboxylesterase 1 (CES1), to impaired survival in patient cells. A beneficial angiogenic response to potential therapies, FK506 and Elafin, was related to reduced slit guidance ligand 3 (SLIT3), an antimigratory factor.

CONCLUSIONS

Despite the site of disease in the lung, our study indicates that induced pluripotent stem cell-derived endothelial cells are useful surrogates to uncover novel features related to disease mechanisms and to better match patients to therapies.

Bone Morphogenetic Protein 9 Protects against Neonatal Hyperoxia-Induced Impairment of Alveolarization and Pulmonary Inflammation

Aim: Effective treatment of premature infants with bronchopulmonary dysplasia (BPD) is lacking. We hypothesize that bone morphogenetic protein 9 (BMP9), a ligand of the TGF-β family that binds to the activin receptor-like kinase 1 (ALK1)-BMP receptor type 2 (BMPR2) receptor complex, may be a novel therapeutic option for BPD. Therefore, we investigated the cardiopulmonary effects of BMP9 in neonatal Wistar rats with hyperoxia-induced BPD.

Methods: Directly after birth Wistar rat pups were exposed to 100% oxygen for 10 days. From day 2 rat pups received BMP9 (2.5 μg/kg, twice a day) or 0.9% NaCl by subcutaneous injection. Beneficial effects of BMP9 on aberrant alveolar development, lung inflammation and fibrosis, and right ventricular hypertrophy (RVH) were investigated by morphometric analysis and cytokine production. In addition, differential mRNA expression of BMP9 and its receptor complex: ALK1, BMPR2, and Endoglin, and of the ALK1 downstream target transmembrane protein 100 (TMEM100) were studied during the development of experimental BPD. Expression of the BMP9 receptor complex and TMEM100 was studied in human endothelial and epithelial cell cultures and the effect of BMP9 on inflammatory cytokine production and TMEM100 expression was studied in endothelial cell cultures.

Results:ALK1, ALK2, BMPRII, TMEM100, and Endoglin were differentially expressed in experimental BPD, suggesting a role for BMP9-dependent signaling in the development of (experimental) BPD. TMEM100 was expressed in the wall of blood vessels, showing an elastin-like expression pattern in arterioles. Expression of TMEM100 mRNA and protein was decreased after exposure to hyperoxia. BMP9 treatment of rat pups with hyperoxia-induced experimental BPD reduced alveolar enlargement, lung septal thickness and fibrosis, and prevented inflammation, but did not attenuate vascular remodeling and RVH. The anti-inflammatory effect of BMP9 was confirmed in vitro. Highest expression of ALK1, BMPR2, and TMEM100 was observed in human endothelial cell cultures. Stimulation of human endothelial cell cultures with BMP9 reduced their pro-inflammatory cytokine response and induced TMEM100 expression in pulmonary arterial endothelial cells.

Conclusion: BMP9 protects against neonatal hyperoxia-induced BPD by improving aberrant alveolar development, inflammation and fibrosis, demonstrating its therapeutic potential for premature infants with severe BPD.

Bone morphogenetic protein 9 (BMP9) and BMP10 enhance tumor necrosis factor-α-induced monocyte recruitment to the vascular endothelium mainly via activin receptor-like kinase 2

Bone morphogenetic proteins 9 and 10 (BMP9/BMP10) are circulating cytokines with important roles in endothelial homeostasis. The aim of this study was to investigate the roles of BMP9 and BMP10 in mediating monocyte-endothelial interactions using an in vitro flow adhesion assay. Herein, we report that whereas BMP9/BMP10 alone had no effect on monocyte recruitment, at higher concentrations both cytokines synergized with tumor necrosis factor-α (TNFα) to increase recruitment to the vascular endothelium. The BMP9/BMP10-mediated increase in monocyte recruitment in the presence of TNFα was associated with up-regulated expression levels of E-selectin, vascular cell adhesion molecule (VCAM-1), and intercellular adhesion molecule 1 (ICAM-1) on endothelial cells. Using siRNAs to type I and II BMP receptors and the signaling intermediaries (Smads), we demonstrated a key role for ALK2 in the BMP9/BMP10-induced surface expression of E-selectin, and both ALK1 and ALK2 in the up-regulation of VCAM-1 and ICAM-1. The type II receptors, BMPR-II and ACTR-IIA were both required for this response, as was Smad1/5. The up-regulation of cell surface adhesion molecules by BMP9/10 in the presence of TNFα was inhibited by LDN193189, which inhibits ALK2 but not ALK1. Furthermore, LDN193189 inhibited monocyte recruitment induced by TNFα and BMP9/10. BMP9/10 increased basal IκBα protein expression, but did not alter p65/RelA levels. Our findings suggest that higher concentrations of BMP9/BMP10 synergize with TNFα to induce the up-regulation of endothelial selectins and adhesion molecules, ultimately resulting in increased monocyte recruitment to the vascular endothelium. This process is mediated mainly via the ALK2 type I receptor, BMPR-II/ACTR-IIA type II receptors, and downstream Smad1/5 signaling.

BMP type II receptor as a therapeutic target in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic disease characterized by a progressive elevation in mean pulmonary arterial pressure. This occurs due to abnormal remodeling of small peripheral lung vasculature resulting in progressive occlusion of the artery lumen that eventually causes right heart failure and death. The most common cause of PAH is inactivating mutations in the gene encoding a bone morphogenetic protein type II receptor (BMPRII). Current therapeutic options for PAH are limited and focused mainly on reversal of pulmonary vasoconstriction and proliferation of vascular cells. Although these treatments can relieve disease symptoms, PAH remains a progressive lethal disease. Emerging data suggest that restoration of BMPRII signaling in PAH is a promising alternative that could prevent and reverse pulmonary vascular remodeling. Here we will focus on recent advances in rescuing BMPRII expression, function or signaling to prevent and reverse pulmonary vascular remodeling in PAH and its feasibility for clinical translation. Furthermore, we summarize the role of described miRNAs that directly target the BMPR2 gene in blood vessels. We discuss the therapeutic potential and the limitations of promising new approaches to restore BMPRII signaling in PAH patients. Different mutations in BMPR2 and environmental/genetic factors make PAH a heterogeneous disease and it is thus likely that the best approach will be patient-tailored therapies.

TNFα drives pulmonary arterial hypertension by suppressing the BMP type-II receptor and altering NOTCH signalling

Heterozygous germ-line mutations in the bone morphogenetic protein type-II receptor (BMPR-II) gene underlie heritable pulmonary arterial hypertension (HPAH). Although inflammation promotes PAH, the mechanisms by which inflammation and BMPR-II dysfunction conspire to cause disease remain unknown. Here we identify that tumour necrosis factor-α (TNFα) selectively reduces BMPR-II transcription and mediates post-translational BMPR-II cleavage via the sheddases, ADAM10 and ADAM17 in pulmonary artery smooth muscle cells (PASMCs). TNFα-mediated suppression of BMPR-II subverts BMP signalling, leading to BMP6-mediated PASMC proliferation via preferential activation of an ALK2/ACTR-IIA signalling axis. Furthermore, TNFα, via SRC family kinases, increases pro-proliferative NOTCH2 signalling in HPAH PASMCs with reduced BMPR-II expression. We confirm this signalling switch in rodent models of PAH and demonstrate that anti-TNFα immunotherapy reverses disease progression, restoring normal BMP/NOTCH signalling. Collectively, these findings identify mechanisms by which BMP and TNFα signalling contribute to disease, and suggest a tractable approach for therapeutic intervention in PAH.

Reduced BMP receptor II signalling underlies pulmonary arterial hypertension (PAH). Here, Hurst et al. show that TNFα subverts BMP signalling by increasing BMP6 expression and signalling via an alternative BMP receptor, ALK2, in pulmonary artery smooth muscle cells to drive abnormal proliferation and PAH.

Aortic calcification was associated with risk of fractures: A meta-analysis

OBJECTIVE

The objective of this meta-analysis was to systematically assess the association between aortic calcification (AC) and fractures.

METHOD

Relevant studies were identified through searching PubMed, EMBASE and Cochrane databases before August 2014. Two investigators extracted data independently from the included studies. A random-effects model was derived to composite the pooled HRs or ORs for association of aortic calcification with fractures.

RESULTS

A total of 15 articles (21927 subjects) were included in the final meta-analyses. Comparing with non-calcification subjects, patients with aortic calcification were associated with increased risk of fractures (OR = 2.97, 95% CI: 1.98-4.42). Stratified analysis indicated that patients with aortic calcification showed a higher risk of fractures in hemodialysis patients (OR = 1.89, 95% CI: 1.33-2.67; I2 = 0.0%, p= 0.781) and general population (OR = 2.90, 95% CI: 1.80-4.80; I2 = 33.0%, p= 0.225), respectively. Similar significant association between severe aortic calcification and fractures were also observed.

CONCLUSIONS

Patients with aortic calcification or severe aortic calcification were associated with higher risk of fractures.

BMPRII influences the response of pulmonary microvascular endothelial cells to inflammatory mediators

Mutations in the bone morphogenetic protein receptor (BMPR2) gene have been observed in 70 % of patients with heritable pulmonary arterial hypertension (HPAH) and in 11-40 % with idiopathic PAH (IPAH). However, carriers of a BMPR2 mutation have only 20 % risk of developing PAH. Since inflammatory mediators are increased and predict survival in PAH, they could act as a second hit inducing the development of pulmonary hypertension in BMPR2 mutation carriers. Our specific aim was to determine whether inflammatory mediators could contribute to pulmonary vascular cell dysfunction in PAH patients with and without a BMPR2 mutation. Pulmonary microvascular endothelial cells (PMEC) and arterial smooth muscle cells (PASMC) were isolated from lung parenchyma of transplanted PAH patients, carriers of a BMPR2 mutation or not, and from lobectomy patients or lung donors. The effects of CRP and TNFα on mitogenic activity, adhesiveness capacity, and expression of adhesion molecules were investigated in PMECs and PASMCs. PMECs from BMPR2 mutation carriers induced an increase in PASMC mitogenic activity; moreover, endothelin-1 secretion by PMECs from carriers was higher than by PMECs from non-carriers. Recruitment of monocytes by PMECs isolated from carriers was higher compared to PMECs from non-carriers and from controls, with an elevated ICAM-1 expression. CRP increased adhesion of monocytes to PMECs in carriers and non-carriers, and TNFα only in carriers. PMEC from BMPR2 mutation carriers have enhanced adhesiveness for monocytes in response to inflammatory mediators, suggesting that BMPR2 mutation could generate susceptibility to an inflammatory insult in PAH.

Blood Brothers: Hemodynamics and Cell-Matrix Interactions in Endothelial Function

SIGNIFICANCE

Alterations in endothelial function contribute to a variety of vascular diseases. In pathological conditions, the endothelium shows a reduced ability to regulate vasodilation (endothelial dysfunction) and a conversion toward a proinflammatory and leaky phenotype (endothelial activation). At the interface between the vessel wall and blood, the endothelium exists in a complex microenvironment and must translate changes in these environmental signals to alterations in vessel function. Mechanical stimulation and endothelial cell interactions with the vascular matrix, as well as a host of soluble factors, coordinately contribute to this dynamic regulation.

RECENT ADVANCES

Blood hemodynamics play an established role in the regulation of endothelial function. However, a growing body of work suggests that subendothelial matrix composition similarly and coordinately regulates endothelial cell phenotype such that blood flow affects matrix remodeling, which affects the endothelial response to flow.

CRITICAL ISSUES

Hemodynamics and soluble factors likely affect endothelial matrix remodeling through multiple mechanisms, including transforming growth factor β signaling and alterations in cell-matrix receptors, such as the integrins. Likewise, differential integrin signaling following matrix remodeling appears to regulate several key flow-induced responses, including nitric oxide production, regulation of oxidant stress, and activation of proinflammatory signaling and gene expression. Microvascular remodeling responses, such as angiogenesis and arteriogenesis, may also show coordinated regulation by flow and matrix.

FUTURE DIRECTIONS

Identifying the mechanisms regulating the dynamic interplay between hemodynamics and matrix remodeling and their contribution to the pathogenesis of cardiovascular disease remains an important research area with therapeutic implications across a variety of conditions. Antioxid. Redox Signal. 25, 415-434.