ß1 integrins play a critical role maintaining vascular integrity in the hypoxic spinal cord, particularly in white matter.

Interactions between extracellular matrix (ECM) proteins and ß1 integrins play an essential role maintaining vascular integrity in the brain, particularly under vascular remodeling conditions. As blood vessels in the spinal cord are reported to have distinct properties from those in the brain, here we examined the impact of ß1 integrin inhibition on spinal cord vascular integrity, both under normoxic conditions, when blood vessels are stable, and during exposure to chronic mild hypoxia (CMH), when extensive vascular remodeling occurs. We found that a function-blocking ß1 integrin antibody triggered a small degree of vascular disruption in the spinal cord under normoxic conditions, but under hypoxic conditions, it greatly enhanced (20-fold) vascular disruption, preferentially in spinal cord white matter (WM). This resulted in elevated microglial activation as well as marked loss of myelin integrity and reduced density of oligodendroglial cells. To understand why vascular breakdown is localized to WM, we compared expression levels of major BBB components of WM and grey matter (GM) blood vessels, but this revealed no obvious differences. Interestingly however, hypoxyprobe staining demonstrated that the most severe levels of spinal cord hypoxia induced by CMH occurred in the WM. Analysis of brain tissue revealed a similar preferential vulnerability of WM tracts to show vascular disruption under these conditions. Taken together, these findings demonstrate an essential role for ß1 integrins in maintaining vascular integrity in the spinal cord, and unexpectedly, reveal a novel and fundamental difference between WM and GM blood vessels in their dependence on ß1 integrin function during hypoxic exposure. Our data support the concept that the preferential WM vulnerability described may be less a result of intrinsic differences in vascular barrier properties between WM and GM, and more a consequence of differences in vascular density and architecture.

Activation of CaMKII/HDAC4 by SDF1 contributes to pulmonary arterial hypertension via stabilization Runx2.

Stromal derived factor 1 (SDF1) has been shown to be involved in the pathogenesis of pulmonary artery hypertension (PAH). However, the detailed molecular mechanisms remain unclear. To address this, we utilized primary cultured rat pulmonary artery smooth muscle cells (PASMCs) and monocrotaline (MCT)-induced PAH rat models to investigate the mechanisms of SDF1 driving PASMCs proliferation and pulmonary arterial remodeling. SDF1 increased runt-related transcription factor 2 (Runx2) acetylation by Calmodulin (CaM)-dependent protein kinase II (CaMKII)-dependent HDAC4 cytoplasmic translocation, elevation of Runx2 acetylation conferred its resistance to proteasome-mediated degradation. The accumulation of Runx2 further upregulated osteopontin (OPN) expression, finally leading to PASMCs proliferation. Blocking SDF1, suppression of CaMKII, inhibition the nuclear export of HDAC4 or silencing Runx2 attenuated pulmonary arterial remodeling and prevented PAH development in MCT-induced PAH rat models. Our study provides novel sights for SDF1 induction of PASMCs proliferation and suggests that targeting SDF1/CaMKII/HDAC4/Runx2 axis has potential value in the management of PAH.

Resolvin D1 attenuates Ang II-induced hypertension in mice by inhibiting the proliferation, migration and phenotypic transformation of vascular smooth muscle cells by blocking the RhoA/mitogen-activated protein kinase pathway.

The proliferation, migration and phenotypic transformation of vascular smooth muscle cells contribute to vascular remodeling and hypertension. Resolvin D1 (RvD1) is a specialized pro-resolving lipid mediator that has been shown to have anti-inflammatory effects and can protect against different cardiovascular diseases. However, the role and mechanism of RvD1 in hypertension are not clear. The current study investigated the role of RvD1 in Ang II-induced hypertensive mice and Ang II-stimulated rat vascular smooth muscle cells. The results showed that RvD1 treatment significantly attenuated hypertension and vascular remodeling, as indicated by decreases in blood pressure, aortic media thickness and collagen deposition. In addition, RvD1 inhibited the proliferation, migration and phenotypic transformation of vascular smooth muscle cells (VSMCs) in vivo and in vitro . Notably, the protective effects of RvD1 were mediated by the Ras homolog gene family member A (RhoA)/mitogen-activated protein kinase (MAPK) signaling pathway. In conclusion, our findings demonstrated the potential benefits of RvD1 as a promising therapeutic agent in the treatment of vascular remodeling and hypertension.

Ginkgolide B Blocks Vascular Remodeling after Vascular Injury via Regulating Tgfß1/Smad Signaling Pathway.

Coronary artery disease (CAD) is the most prevalent cardiovascular disease worldwide, resulting in myocardial infarction (MI) and even sudden death. Following percutaneous coronary intervention (PCI), restenosis caused by vascular remodeling is always formed at the stent implantation site. Here, we show that Ginkgolide B (GB), a naturally occurring terpene lactone, effectively suppresses vascular remodeling and subsequent restenosis in wild-type mice following left carotid artery (LCA) injury. Additional experiments reveal that GB exerts a protective effect on vascular remodeling and further restenosis through modulation of the Tgfß1/Smad signaling pathway in vivo and in human vascular smooth muscle cells (HVSMAs) but not in human umbilical vein endothelial cells (HUVECs) in vitro. Moreover, the beneficial effect of GB is abolished after incubated with pirfenidone (PFD, a drug for idiopathic pulmonary fibrosis, IPF), which can inhibit Tgfß1. In Tgfß1-/- mice, treatment with pirfenidone capsules and Yinxingneizhi Zhusheye (including Ginkgolide B) fails to improve vascular remodeling and restenosis. In conclusion, our data identify that GB could be a potential novel therapeutic agent to block vessel injury-associated vascular remodeling and further restenosis and show significant repression of Tgfß1/Smad signaling pathway.

DNA-dependent protein kinase catalytic subunit (DNA-PKcs) drives angiotensin II-induced vascular remodeling through regulating mitochondrial fragmentation.

BACKGROUND: DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is a novel instigator for mitochondrial dysfunction, and plays an important role in the pathogenesis of cardiovascular diseases. However, the role and mechanism of DNA-PKcs in angiotensin II (Ang II)-induced vascular remodeling remains obscure. METHODS: Rat aortic smooth muscle cells (SMC) and VSMC-specific DNA-PKcs knockout (DNA-PKcsΔVSMC) mice were employed to examine the role of DNA-PKcs in vascular remodeling and the underlying mechanisms. Blood pressure of mice was monitored using the tail-cuff and telemetry methods. The role of DNA-PKcs in vascular function was evaluated using vascular relaxation assessment. RESULTS: In the tunica media of remodeled mouse thoracic aortas, and renal arteries from hypertensive patients, elevated DNA-PKcs expression was observed along with its cytoplasmic translocation from nucleus, suggesting a role for DNA-PKcs in vascular remodeling. We then infused wild-type (DNA-PKcsfl/fl) and DNA-PKcsΔVSMC mice with Ang II for 14 days to establish vascular remodeling, and demonstrated that DNA-PKcsΔVSMC mice displayed attenuated vascular remodeling through inhibition of dedifferentiation of VSMCs. Moreover, deletion of DNA-PKcs in VSMCs alleviated Ang II-induced vasodilation dysfunction and hypertension. Mechanistic investigations denoted that Ang II-evoked rises in cytoplasmic DNA-PKcs interacted with dynamin-related protein 1 (Drp1) at its TQ motif to phosphorylate Drp1S616, subsequently promoting mitochondrial fragmentation and dysfunction, as well as reactive oxygen species (ROS) production. Treatment of irbesartan, an Ang II type 1 receptor (AT1R) blocker, downregulated DNA-PKcs expression in VSMCs and aortic tissues following Ang II administration. CONCLUSION: Our data revealed that cytoplasmic DNA-PKcs in VSMCs accelerated Ang II-induced vascular remodeling by interacting with Drp1 at its TQ motif and phosphorylating Drp1S616 to provoke mitochondrial fragmentation. Maneuvers targeting DNA-PKcs might be a valuable therapeutic option for the treatment of vascular remodeling and hypertension.

Infused juice concentrate of Japanese plum Prunus mume attenuates inflammatory vascular remodeling in a mouse model of hypertension induced by angiotensin II.

Fruit from the Prunus mume tree is a traditional food in Japan. Recently, bainiku-ekisu, an infused juice concentrate of Japanese Prunus mume, is attracting attention as a health promoting supplement. Angiotensin II (Ang II) plays a central role in development of hypertension. It has been reported that bainiku-ekisu treatment attenuates the growth-promoting signaling induced by Ang II in vascular smooth muscle cells. However, whether bainiku-ekisu has any effect on an animal model of hypertension remains unknown. Therefore, this study was designed to explore the potential anti-hypertensive benefit of bainiku-ekisu utilizing a mouse model of hypertension with Ang II infusion. Male C57BL/6 mice were infused with Ang II for 2 weeks and given 0.1% bainiku-ekisu containing water or normal water for 2 weeks with blood pressure evaluation. After 2 weeks, mice were euthanized, and the aortas were collected for evaluation of remodeling. Aortic medial hypertrophy was observed in control mice after Ang II infusion, which was attenuated in bainiku-ekisu group with Ang II infusion. Bainiku-ekisu further attenuated aortic induction of collagen producing cells and immune cell infiltration. Development of hypertension induced by Ang II was also prevented by bainiku-ekisu. Echocardiograph indicated protection of Ang II-induced cardiac hypertrophy by bainiku-ekisu. In vascular fibroblasts, bainiku-ekisu attenuated vascular cell adhesion molecule-1 induction, an endoplasmic reticulum stress marker, inositol requiring enzyme-1α phosphorylation, and enhancement in glucose consumption in response to Ang II. In conclusion, Bainiku-ekisu prevented Ang II-induced hypertension and inflammatory vascular remodeling. Potential cardiovascular health benefit to taking bainiku-ekisu should be further studied.

Inflammation and immunity in the pathogenesis of hypoxic pulmonary hypertension.

Hypoxic pulmonary hypertension (HPH) is a complicated vascular disorder characterized by diverse mechanisms that lead to elevated blood pressure in pulmonary circulation. Recent evidence indicates that HPH is not simply a pathological syndrome but is instead a complex lesion of cellular metabolism, inflammation, and proliferation driven by the reprogramming of gene expression patterns. One of the key mechanisms underlying HPH is hypoxia, which drives immune/inflammation to mediate complex vascular homeostasis that collaboratively controls vascular remodeling in the lungs. This is caused by the prolonged infiltration of immune cells and an increase in several pro-inflammatory factors, which ultimately leads to immune dysregulation. Hypoxia has been associated with metabolic reprogramming, immunological dysregulation, and adverse pulmonary vascular remodeling in preclinical studies. Many animal models have been developed to mimic HPH; however, many of them do not accurately represent the human disease state and may not be suitable for testing new therapeutic strategies. The scientific understanding of HPH is rapidly evolving, and recent efforts have focused on understanding the complex interplay among hypoxia, inflammation, and cellular metabolism in the development of this disease. Through continued research and the development of more sophisticated animal models, it is hoped that we will be able to gain a deeper understanding of the underlying mechanisms of HPH and implement more effective therapies for this debilitating disease.

Inhibition of pulmonary artery smooth muscle cells via the delivery of curcuminoid WZ35 by Cu-based metal organic frameworks.

Hypoxic pulmonary hypertension (HPH) is a life-threatening disease that occurs due to a lack of oxygen in the lungs, leading to an increase in pulmonary vascular resistance, right ventricular failure, and ultimately death. HPH is a multifactorial disorder that involves multiple molecular pathways, making it a challenge for clinicians to identify effective therapies. Pulmonary artery smooth muscle cells (PASMCs) play a crucial role in HPH pathogenesis by proliferating, resisting apoptosis, and promoting vascular remodelling. Curcumin, a natural polyphenolic compound, has shown potential as a therapeutic agent for HPH by reducing pulmonary vascular resistance, inhibiting vascular remodelling, and promoting apoptosis of PASMCs. Regulation of PASMCs could significantly inhibits HPH. However, curcumin has the disadvantages of poor solubility and low bioavailability, and its derivative WZ35 has better biosafety. Here, Cu-based metal organic frameworks (MOFCu ) was fabricated to encapsulate the curcumin analogue WZ35 (MOFCu @WZ35) for the inhibition of PASMCs proliferation. The authors found that the MOFCu @WZ35 could promote the death of PASMCs. Furthermore, the authors believed that this drug delivery system will effectively alleviate the HPH.

Purine synthesis suppression reduces the development and progression of pulmonary hypertension in rodent models.

AIMS: Proliferation of vascular smooth muscle cells (VSMCs) is a hallmark of pulmonary hypertension (PH). Proliferative cells utilize purine bases from the de novo purine synthesis (DNPS) pathways for nucleotide synthesis; however, it is unclear whether DNPS plays a critical role in VSMC proliferation during development of PH. The last two steps of DNPS are catalysed by the enzyme 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/inosine monophosphate cyclohydrolase (ATIC). This study investigated whether ATIC-driven DNPS affects the proliferation of pulmonary artery smooth muscle cells (PASMCs) and the development of PH. METHODS AND RESULTS: Metabolites of DNPS in proliferative PASMCs were measured by liquid chromatography-tandem mass spectrometry. ATIC expression was assessed in platelet-derived growth factor-treated PASMCs and in the lungs of PH rodents and patients with pulmonary arterial hypertension. Mice with global and VSMC-specific knockout of Atic were utilized to investigate the role of ATIC in both hypoxia- and lung interleukin-6/hypoxia-induced murine PH. ATIC-mediated DNPS at the mRNA, protein, and enzymatic activity levels were increased in platelet-derived growth factor-treated PASMCs or PASMCs from PH rodents and patients with pulmonary arterial hypertension. In cultured PASMCs, ATIC knockdown decreased DNPS and nucleic acid DNA/RNA synthesis, and reduced cell proliferation. Global or VSMC-specific knockout of Atic attenuated vascular remodelling and inhibited the development and progression of both hypoxia- and lung IL-6/hypoxia-induced PH in mice. CONCLUSION: Targeting ATIC-mediated DNPS compromises the availability of purine nucleotides for incorporation into DNA/RNA, reducing PASMC proliferation and pulmonary vascular remodelling and ameliorating the development and progression of PH.

A Bioengineered Model for Studying Vascular-Pericyte Interactions of the Placenta.

Investigating the complex cellular interactions of the placenta has remained, until now, a challenge in the field. Given the ethical limitations of studying human placentae, and the interspecies differences that exist between mammals, in vitro models are a valuable tool for investigating developmental and pathologic processes related to the human placenta. A number of in vitro models have been recently employed to investigate various aspects of placental development, with many focusing on the maternal-fetal interface including the trophoblasts and an endothelial barrier. One critical aspect in mimicking the physiology of the placenta is to include perfusable microvessels. As this organ is highly vascularized, it is pertinent to represent the exchange of oxygen and nutrients from the maternal blood to the embedded vessels of the fetus. Using hydrogel-laden microfluidics, it is now possible to bioengineer these and other microvessels in a reproducible manner. By using HUVEC, fetal-like vessels can be generated on a chip and can be studied in a controlled manner. This chapter introduces the concept of generating a triculture vasculature on-chip system, which can be employed to study placental pericyte-endothelial interactions. We describe strategies for generating the vessels on-chip, as well as for quantifying vascular morphology and function. This methodology allows for unique microvessel-related biological questions to be addressed, including how stromal cells impact vascular remodeling over time.

Swietenine Alleviates Vascular Remodelling by Enhancing Mitophagy of Pulmonary Arterial Smooth Muscle Cells in Experimental Pulmonary Hypertension.

BACKGROUND: Vascular remodelling during pulmonary hypertension (PH) is characterized by the phenotypic transformation of pulmonary arterial smooth muscle cells (PASMCs). Swietenine (Swi), extracted from the seeds of traditional medicine Swietenia mahagoni, has been used to treat cardiac remodelling, but the effect of Swi on PH is unknown. This study aims to evaluate the effect of Swi on hypoxia-induced phenotypic transformation of PASMCs in experimental PH. METHODS: In our research, C57BL/6 mice were treated with SU5416 and exposed to hypoxia for 4 weeks to establish HySu-PH model. Mice in the Swi treatment group were subjected to HySu with daily administration of Swi. Hemodynamic parameters, echocardiography, and degree of vascular muscularization were measured to evaluate the PH model. Proliferation of PASMC was assessed by Ki67 and EdU assay. Cell migration was detected by wound-healing assay. Mitophagy levels were evaluated by mito-tracker and lyso-tracker, autophagic flux, and protein expression of Pink1 and Lc3 II. The molecular docking was used to validate the interaction of Swi with Nrf2. Immunofluorescence and immunohistochemical staining were applied to determine the subcellular localization of Nrf2. RESULTS: The results showed that Swi attenuated hypoxia-induced increase of right ventricle systolic pressure, Fulton index, and vascular remodelling and decreased PASMC proliferation, migration, and enhanced mitophagy. Furthermore, the interaction of Swi with Nrf2 promoted the translocation of Nrf2 into the nucleus, resulting in the induction of Pink1. CONCLUSIONS: This study demonstrates that Swi prevents vascular remodelling in experimental PH through inhibition of phenotypic transformation and hyperproliferation of PASMCs caused by reversing hypoxia-induced inhibition of mitophagy.

Endothelial Cell-Derived Let-7c-Induced TLR7 Activation on Smooth Muscle Cell Mediate Vascular Wall Remodeling in Moyamoya Disease.

Moyamoya disease (MMD) is characterized by frequent migration and phenotypic transformation of vascular smooth muscle cells (VSMCs) in the intima layer of blood vessels. However, the underlying mechanism is unclear. Toll-like receptor (TLR) 7 is abundantly expressed in smooth muscle cells (SMCs) in multiple vascular diseases, which might be linked to the disease-associated vascular remodeling. In the present study, the expression of TLR7 in MMD vessels was examined using the superficial temporal artery (STA) and middle cerebral artery (MCA) from MMD patients. Furthermore, the effect of TLR7 activation on the VSMC phenotype switch in vitro and vascular remodeling in vivo was assessed using a 9.4Tesla MRI. Our results demonstrated that the TLR7 and microRNA Let-7c expression are upregulated in VSMCs and the plasma of MMD patients, respectively. Additionally, TLR7 stimulation by Let-7c or Imiquimod induces a synthetic phenotype switch in VSMCs. Mechanistic studies revealed that Akt/mTOR signaling is responsible for this TLR-induced VSMC phenotypic switch. The Let-7c or Imiquimod treatment also resulted in reduced blood flow of internal carotid arteries (ICAs) in an in vivo model, while TLR7 inhibition attenuated the ICA stenosis. Besides, Let-7c was also found to be elevated in the hypoxic endothelial cells. Taken together, our study demonstrates that Let-7c released by endothelial cells under hypoxic conditions may activate TLR7 on VSMCs, ultimately leading to the phenotype switch and vascular wall remodeling. These findings thus elucidate the putative mechanisms underlying progressive stenosis of blood vessels in MMD and provide prospective therapeutic targets for further exploration.

Regulatory B cells protect against chronic hypoxia-induced pulmonary hypertension by modulating the Tfh/Tfr immune balance.

Hypoxia-induced pulmonary hypertension (HPH) is a progressive and lethal disease characterized by the uncontrolled proliferation of pulmonary artery smooth muscle cells (PASMCs) and obstructive vascular remodelling. Previous research demonstrated that Breg cells were involved in the pathogenesis of pulmonary hypertension. This work aimed to evaluate the regulatory function of Breg cells in HPH. HPH mice model were established and induced by exposing to chronic hypoxia for 21 days. Mice with HPH were treated with anti-CD22 or adoptive transferred of Breg cells. The coculture systems of Breg cells with CD4+ T cells and Breg cells with PASMCs in vitro were constructed. Lung pathology was evaluated by HE staining and immunofluorescence staining. The frequencies of Breg cells, Tfh cells and Tfr cells were analysed by flow cytometry. Serum IL-21 and IL-10 levels were determined by ELISA. Protein levels of Blimp-1, Bcl-6 and CTLA-4 were determined by western blot and RT-PCR. Proliferation rate of PASMCs was measured by EdU. Compared to the control group, mean PAP, RV/(LV + S) ratio, WA% and WT% were significantly increased in the model group. Anti-CD22 exacerbated abnormal hemodynamics, pulmonary vascular remodelling and right ventricle hypertrophy in HPH, which ameliorated by adoptive transfer of Breg cells into HPH mice. The proportion of Breg cells on day 7 induced by chronic hypoxia was significantly higher than control group, which significantly decreased on day 14 and day 21. The percentage of Tfh cells was significantly increased, while percentage of Tfr cells was significantly decreased in HPH than those of control group. Anti-CD22 treatment increased the percentage of Tfh cells and decreased the percentage of Tfr cells in HPH mice. However, Breg cells restrained the Tfh cells differentiation and expanded Tfr cells differentiation in vivo and in vitro. Additionally, Breg cells inhibited the proliferation of PASMCs under hypoxic condition in vitro. Collectively, these findings suggested that Breg cells may be a new therapeutic target for modulating the Tfh/Tfr immune balance in HPH.

Plasma exosomes confer hypoxic pulmonary hypertension by transferring LOX-1 cargo to trigger phenotypic switching of pulmonary artery smooth muscle cells.

The pulmonary vascular remodeling (PVR), the pathological basis of pulmonary hypertension (PH), entails pulmonary artery smooth muscle cells (PASMCs) phenotypic switching, but appreciation of the underlying mechanisms is incomplete. Exosomes, a novel transfer machinery enabling delivery of its cargos to recipient cells, have been recently implicated in cardiovascular diseases including PH. The two critical questions of whether plasma-derived exosomes drive PASMCs phenotypic switching and what cargo the exosomes transport, however, remain unclear. Herein, by means of transmission electron microscopy and protein detection, we for the first time, characterized lectin like oxidized low-density lipoprotein receptor-1 (LOX-1) as a novel cargo of plasma-derived exosomes in PH. With LOX-1 knockout (Olr1-/-) rats-derived exosomes, we demonstrated that exosomal LOX-1 could be transferred into PASMCs and thus elicited cell phenotypic switching. Of importance, Olr1-/- rats exhibited no cell phenotypic switching and developed less severe PH, but administration of wild type rather than Olr1-/- exosomes to Olr1-/- rats recapitulated the phenotype of PH with robust PASMCs phenotypic switching. We also revealed that exosomal LOX-1 triggered PASMCs phenotypic switching, PVR and ultimately PH via ERK1/2-KLF4 signaling axis. This study has generated proof that plasma-derived exosomes confer PH by delivering LOX-1 into PASMCs. Hence, exosomal LOX-1 represents a novel exploitable target for PH prevention and treatment.

A role for steroid 5 alpha-reductase 1 in vascular remodeling during endometrial decidualization.

Decidualization is the hormone-dependent process of endometrial remodeling that is essential for fertility and reproductive health. It is characterized by dynamic changes in the endometrial stromal compartment including differentiation of fibroblasts, immune cell trafficking and vascular remodeling. Deficits in decidualization are implicated in disorders of pregnancy such as implantation failure, intra-uterine growth restriction, and pre-eclampsia. Androgens are key regulators of decidualization that promote optimal differentiation of stromal fibroblasts and activation of downstream signaling pathways required for endometrial remodeling. We have shown that androgen biosynthesis, via 5α-reductase-dependent production of dihydrotestosterone, is required for optimal decidualization of human stromal fibroblasts in vitro, but whether this is required for decidualization in vivo has not been tested. In the current study we used steroid 5α-reductase type 1 (SRD5A1) deficient mice (Srd5a1-/- mice) and a validated model of induced decidualization to investigate the role of SRD5A1 and intracrine androgen signaling in endometrial decidualization. We measured decidualization response (weight/proportion), transcriptomic changes, and morphological and functional parameters of vascular development. These investigations revealed a striking effect of 5α-reductase deficiency on the decidualization response. Furthermore, vessel permeability and transcriptional regulation of angiogenesis signaling pathways, particularly those that involved vascular endothelial growth factor (VEGF), were disrupted in the absence of 5α-reductase. In Srd5a1-/- mice, injection of dihydrotestosterone co-incident with decidualization restored decidualization responses, vessel permeability, and expression of angiogenesis genes to wild type levels. Androgen availability declines with age which may contribute to age-related risk of pregnancy disorders. These findings show that intracrine androgen signaling is required for optimal decidualization in vivo and confirm a major role for androgens in the development of the vasculature during decidualization through regulation of the VEGF pathway. These findings highlight new opportunities for improving age-related deficits in fertility and pregnancy health by targeting androgen-dependent signaling in the endometrium.

Endothelial mechanosensing: A forgotten target to treat vascular remodeling in hypertension?

The endothelium is a mechanosensitive organ whose pleiotropic actions regulate vessel structure to adjust tissue perfusion. To do so, it possesses ion channels, receptor complexes, and signaling pathways responding to blood flow, whose activation will either maintain vascular integrity and quiescence or, on the contrary, remodel the vessel's structure in both health and disease. Recent studies have demonstrated the crucial role of endothelial inflammation, endothelial to mesenchymal transition (EndMT), and perturbed hemodynamics in the progression of pulmonary arterial hypertension and essential hypertension. These two distinct diseases share some common mechanistic cues, pointing towards new potential therapeutic approaches to treat them. In this review, we summarize these common mechanisms to map future drug development strategies targeting flow sensing mechanisms and vascular remodeling.

DNA-PKcs participated in hypoxic pulmonary hypertension.

BACKGROUND: Hypoxic pulmonary hypertension (HPH) is a common complication of chronic lung disease, which severely affects the survival and prognosis of patients. Several recent reports have shown that DNA damage and repair plays a crucial role in pathogenesis of pulmonary arterial hypertension. DNA-dependent protein kinase catalytic subunit (DNA-PKcs) as a part of DNA-PK is a molecular sensor for DNA damage that enhances DSB repair. This study aimed to demonstrate the expression and potential mechanism of DNA-PKcs on the pathogenesis of HPH. METHODS: Levels of DNA-PKcs and other proteins in explants of human and rats pulmonary artery from lung tissues and pulmonary artery smooth muscle cells (PASMC) were measured by immunohistochemistry and western blot analysis. The mRNA expression levels of DNA-PKcs and NOR1 in PASMCs were quantified with qRT-PCR. Meanwhile, the interaction among proteins were detected by Co-immunoprecipitation (Co-IP) assays. Cell proliferation and apoptosis was assessed by cell counting kit-8 assay(CCK-8), EdU incorporation and flow cytometry. Rat models of HPH were constructed to verify the role of DNA-PKcs in pulmonary vascular remodeling in vivo. RESULTS: DNA-PKcs protein levels were both significantly up-regulated in explants of pulmonary artery from HPH models and lung tissues of patients with hypoxemia. In human PASMCs, hypoxia up-regulated DNA-PKcs in a time-dependent manner. Downregulation of DNA-PKcs by targeted siRNA or small-molecule inhibitor NU7026 both induced cell proliferation inhibition and cell cycle arrest. DNA-PKcs affected proliferation by regulating NOR1 protein synthesis followed by the expression of cyclin D1. Co-immunoprecipitation of NOR1 with DNA-PKcs was severely increased in hypoxia. Meanwhile, hypoxia promoted G2 + S phase, whereas the down-regulation of DNA-PKcs and NOR1 attenuated the effects of hypoxia. In vivo, inhibition of DNA-PKcs reverses hypoxic pulmonary vascular remodeling and prevented HPH. CONCLUSIONS: Our study indicated the potential mechanism of DNA-PKcs in the development of HPH. It might provide insights into new therapeutic targets for pulmonary vascular remodeling and pulmonary hypertension.

Vascular peroxidase 1 promotes phenotypic transformation of pulmonary artery smooth muscle cells via ERK pathway in hypoxia-induced pulmonary hypertensive rats.

AIMS: Vascular peroxidase 1 (VPO1) plays an important role in mediation of vascular remodeling with pulmonary arterial hypertension (PAH). This study aims to determine whether VPO1 can promote phenotypic transformation of pulmonary artery smooth muscle cells (PASMCs) and the underlying mechanisms. MAIN METHODS: Sprague-Dawley (SD) rats were exposed to 10 % O2 for 21 days to establish the model of vascular remodeling in pulmonary arterial hypertension. PASMCs were incubated with 3 % O2 for 48 h to induce phenotypic transformation. Western blot was performed to detect the expressions of target proteins. The 5-ethynyl-2'-deoxyuridine (EdU) assay was conducted to measure the proliferation of PASMCs. KEY FINDINGS: In the rats exposed to hypoxia, there were increases in right ventricular systolic pressure, pulmonary vascular remodeling and phenotypic transformation of PASMCs (the down-regulated contractile proteins of α-smooth muscle actin, smooth muscle 22α while the up-regulated synthetic proteins of osteopontin, cyclinD1), accompanied by up-regulation of VPO1, increase of hypochlorous acid (HOCl) production and elevation of the phosphorylation of ERK. In the cultured PASMCs exposed to hypoxia, similar results were achieved but they were reversed by VPO1 small interfering RNA (VPO1 siRNA) or HOCl inhibitor. Replacement of hypoxia with NaOCl could induce PASMCs phenotypic transformation and activate the ERK signaling. Furthermore, ERK inhibitor (PD98059) could also attenuate hypoxia-induced PASMCs phenotypic transformation. SIGNIFICANCE: VPO1 play a pivotal role in promotion of phenotypic transformation of PASMCs under hypoxic condition through activation of VPO1/HOCl/ERK pathway. It might serve as a potential target for prevention of pulmonary vascular remodeling.

Methylation-mediated silencing of PTPRD induces pulmonary hypertension by promoting pulmonary arterial smooth muscle cell migration via the PDGFRB/PLCγ1 axis.

OBJECTIVE: Pulmonary hypertension is a lethal disease characterized by pulmonary vascular remodeling and is mediated by abnormal proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs). Platelet-derived growth factor BB (PDGF-BB) is the most potent mitogen for PASMCs and is involved in vascular remodeling in pulmonary hypertension development. Therefore, the objective of our study is to identify novel mechanisms underlying vascular remodeling in pulmonary hypertension. METHODS: We explored the effects and mechanisms of PTPRD downregulation in PASMCs and PTPRD knockdown rats in pulmonary hypertension induced by hypoxia. RESULTS: We demonstrated that PTPRD is dramatically downregulated in PDGF-BB-treated PASMCs, pulmonary arteries from pulmonary hypertension rats, and blood and pulmonary arteries from lung specimens of patients with hypoxic pulmonary arterial hypertension (HPAH) and idiopathic PAH (iPAH). Subsequently, we found that PTPRD was downregulated by promoter methylation via DNMT1. Moreover, we found that PTPRD knockdown altered cell morphology and migration in PASMCs via modulating focal adhesion and cell cytoskeleton. We have demonstrated that the increase in cell migration is mediated by the PDGFRB/PLCγ1 pathway. Furthermore, under hypoxic condition, we observed significant pulmonary arterial remodeling and exacerbation of pulmonary hypertension in heterozygous PTPRD knock-out rats compared with the wild-type group. We also demonstrated that HET group treated with chronic hypoxia have higher expression and activity of PLCγ1 in the pulmonary arteries compared with wild-type group. CONCLUSION: We propose that PTPRD likely plays an important role in the process of pulmonary vascular remodeling and development of pulmonary hypertension in vivo .

Endothelial Cell TGF-ß (Transforming Growth Factor-Beta) Signaling Regulates Venous Adaptive Remodeling to Improve Arteriovenous Fistula Patency.

BACKGROUND: Arteriovenous fistulae (AVF) are the gold standard for vascular access for hemodialysis. Although the vein must thicken and dilate for successful hemodialysis, excessive wall thickness leads to stenosis causing AVF failure. Since TGF-ß (transforming growth factor-beta) regulates ECM (extracellular matrix) deposition and smooth muscle cell (SMC) proliferation-critical components of wall thickness-we hypothesized that disruption of TGF-ß signaling prevents excessive wall thickening during venous remodeling. METHODS: A mouse aortocaval fistula model was used. SB431542-an inhibitor of TGF-ß receptor I-was encapsulated in nanoparticles and applied to the AVF adventitia in C57BL/6J mice. Alternatively, AVFs were created in mice with conditional disruption of TGF-ß receptors in either SMCs or endothelial cells. Doppler ultrasound was performed serially to confirm patency and to measure vessel diameters. AVFs were harvested at predetermined time points for histological and immunofluorescence analyses. RESULTS: Inhibition of TGF-ß signaling with SB431542-containing nanoparticles significantly reduced p-Smad2-positive cells in the AVF wall during the early maturation phase (days 7-21) and was associated with decreased AVF wall thickness that showed both decreased collagen density and decreased SMC proliferation. SMC-specific TGF-ß signaling disruption decreased collagen density but not SMC proliferation or wall thickness. Endothelial cell-specific TGF-ß signaling disruption decreased both collagen density and SMC proliferation in the AVF wall and was associated with reduced wall thickness, increased outward remodeling, and improved AVF patency. CONCLUSIONS: Endothelial cell-targeted TGF-ß inhibition may be a translational strategy to improve AVF patency.