Role Of Vascular Endothelial Cells Research Articles

Microrna363-5p targets thrombospondin3 to regulate pathological cardiac remodeling.

Cardiac remodeling is an end-stage manifestation of multiple cardiovascular diseases, and microRNAs are involved in a variety of posttranscriptional regulatory processes. miR-363-5p targeting Thrombospondin3 (THBS3) has been shown to play an important regulatory role in vascular endothelial cells, but the roles of these two in cardiac remodeling are unknown. Firstly, we established an in vivo model of cardiac remodeling by transverse aortic narrow (TAC), and then we stimulated a human cardiomyocyte cell line (AC16) and a human cardiac fibroblast cell line (HCF) using 1μmol/L angiotensin II (Ang II) to establish an in vitro model of cardiac hypertrophy and an in vitro model of myocardial fibrosis, respectively. In all three of the above models, we found a significant decreasing trend of miR-363-5p, suggesting that it plays a key regulatory role in the occurrence and development of cardiac remodeling. Subsequently, overexpression of miR-363-5p significantly attenuated myocardial hypertrophy and myocardial fibrosis in vitro as evidenced by reduced the area of AC16, the cell viability of HCFs, the relative expression of the protein of fetal genes (ANP, BNP, β-MHC) and fibrosis marker (collagen I, collagen III, α-SMA), whereas inhibition of miR-363-5p expression showed the opposite trend. In addition, we also confirmed the targeted binding relationship between miR-363-5p and THBS3 by dual luciferase reporter gene assay, and the expression of THBS3 was directly inhibited by miR-363-5p. Moreover, overexpression of miR-363-5p with THBS3 simultaneously partially eliminated the delaying effect of miR-363-5p on myocardial hypertrophy and myocardial fibrosis in vitro. In conclusion, Overexpression of miR-363-5p attenuated the prohypertrophic and profibrotic effects of Ang II on AC16 and HCF by a mechanism related to the inhibition of THBS3 expression.

The long coiled-coil protein NECC2 regulates oxLDL-induced endothelial oxidative damage and exacerbates atherosclerosis development in apolipoprotein E −/− mice

Oxidized low density lipoprotein (oxLDL)-induced endothelial oxidative damage promotes the development of atherosclerosis. Caveolae play an essential role in maintaining the survival and function of vascular endothelial cell (VEC). It is reported that the long coiled-coil protein NECC2 is localized in caveolae and is associated with neural cell differentiation and adipocyte formation, but its role in VECs needs to be clarified. Our results showed NECC2 expression increased in the endothelium of plaque-loaded aortas and oxLDL-treated HUVECs. Down-regulation of NECC2 by NECC2 siRNA or compound YF-307 significantly inhibited oxLDL-induced VEC apoptosis and the adhesion factors expression. Remarkably, inhibition of NECC2 expression in the endothelium of apoE−/− mice by adeno-associated virus (AAV)-carrying NECC2 shRNA or compound YF-307 alleviated endothelium injury and restricted atherosclerosis development. The immunoprecipitation results confirmed that NECC2 interacted with Tyk2 and caveolin-1(Cav-1) in VECs, and NECC2 further promoted the phosphorylation of Cav-1 at Tyr14 b y activating Tyk2 phosphorylation. On the other hand, inhibiting NECC2 levels suppressed oxLDL-induced phosphorylation of Cav-1, uptake of oxLDL by VECs, accumulation of intracellular reactive oxygen species and activation of NF-κB. Our findings suggest that NECC2 may contribute to oxLDL-induced VEC injury and atherosclerosis via modulating Cav-1 phosphorylation through Tyk2. This work provides a new concept and drug target for treating atherosclerosis.

ANGI-03. NOVEL ROLE OF ENDOTHELIAL CELL AQUAPORIN-1 IN GLIOBLASTOMA VASCULAR PERMEABILITY AND TUMOR-ASSOCIATED EDEMA

Abstract Glioblastomas are the most common malignant brain tumors in adults, with a median survival of only 12-15 months. Glioblastomas are marked by an aberrant, leaky vasculature that promotes a hypoxic, immunosuppressive microenvironment. This aberrant vascularity not only affects treatment sensitivity but the integrity of the blood brain barrier (BBB). Disruption of the BBB can lead to increased flow of water into intercellular spaces, causing vasogenic edema. Increased intracranial pressure due to vasogenic edema in glioblastoma patients is a significant cause of morbidity and mortality. Severity of edema not only correlates with patient survival, but causes numerous harmful side effects, such as aphasia, cognitive decline, and acute herniation syndrome. Currently, the mainstay of treatment for brain tumor edema is glucocorticosteroids, such as dexamethasone. However, this treatment causes immune suppression and severe long-term adverse effects. To determine the potential role of vascular endothelial cells (ECs) in edema formation, we performed single cell RNAseq on a genetically engineered glioblastoma mouse model, which recapitulates the edema seen in human patients. We found that ECs from glioblastomas and normal brain tissue had distinct expression patterns, with selective expression of a water channel protein called Aquaporin-1 (AQP1) in glioblastoma ECs. In addition, siRNA-mediated AQP1 knockdown decreased GBM EC monolayer permeability. Inhibiting the water channel function of AQP1 alone through Bacopaside II treatment, however, did not alter EC monolayer permeability. Several tight junctions are downregulated in GBM ECs compared to normal brain ECs, and knocking down AQP1 via siRNA restored expression of the tight junction protein Claudin-5. These data suggest that AQP1 induces brain tumor edema by inhibiting tight junction protein expression via its non-water-channel function and that targeting AQP1 in glioblastoma ECs would be a novel therapeutic strategy to improve the BBB and decrease edema levels in vivo.

BMECs Ameliorate High Glucose-Induced Morphological Aberrations and Synaptic Dysfunction via VEGF-Mediated Modulation of Glucose Uptake in Cortical Neurons.

It has been demonstrated that diabetes cause neurite degeneration in the brain and cognitive impairment and neurovascular interactions are crucial for maintaining brain function. However, the role of vascular endothelial cells in neurite outgrowth and synaptic formation in diabetic brain is still unclear. Therefore, present study investigated effects of brain microvascular endothelial cells (BMECs) on high glucose (HG)-induced neuritic dystrophy using a coculture model of BMECs with neurons. Multiple immunofluorescence labelling and western blot analysis were used to detect neurite outgrowth and synapsis formation, and living cell imaging was used to detect uptake function of neuronal glucose transporters. We found cocultured with BMECs significantly reduced HG-induced inhibition of neurites outgrowth (including length and branch formation) and delayed presynaptic and postsynaptic development, as well as reduction of neuronal glucose uptake capacity, which was prevented by pre-treatment with SU1498, a vascular endothelial growth factor (VEGF) receptor antagonist. To analyse the possible mechanism, we collected BMECs cultured condition medium (B-CM) to treat the neurons under HG culture condition. The results showed that B-CM showed the same effects as BMEC on HG-treated neurons. Furthermore, we observed VEGF administration could ameliorate HG-induced neuronal morphology aberrations. Putting together, present results suggest that cerebral microvascular endothelial cells protect against hyperglycaemia-induced neuritic dystrophy and restorate neuronal glucose uptake capacity by activation of VEGF receptors and endothelial VEGF release. This result help us to understand important roles of neurovascular coupling in pathogenesis of diabetic brain, providing a new strategy to study therapy or prevention for diabetic dementia. Hyperglycaemia induced inhibition of neuronal glucose uptake and impaired to neuritic outgrowth and synaptogenesis. Cocultured with BMECs/B-CM and VEGF treatment protected HG-induced inhibition of glucose uptake and neuritic outgrowth and synaptogenesis, which was antagonized by blockade of VEGF receptors. Reduction of glucose uptake may further deteriorate impairment of neurites outgrowth and synaptogenesis.

Tyrosol attenuates lipopolysaccharide‑induced inflammation in HUVECs to promote vascular health against atherosclerosis challenge.

The role of vascular endothelial cells in acute and chronic vascular inflammatory response has long been recognized. Therefore, persistent vascular inflammation may lead to endothelial dysfunction, thus resulting in the release of pro-inflammatory cytokines and the expression of adhesion molecules, which in turn promote monocyte/macrophage adhesion. Inflammation serves a key role in the development of vascular diseases, such as atherosclerosis. Tyrosol is a natural polyphenolic compound with diverse biological functions, found in large quantities in olive oil or in Rhodiola rosea. The current study aimed to investigate the regulatory in vitro effects of tyrosol on pro-inflammatory phenotypes using Cell Counting Kit-8, cell adhesion assay, wound healing, ELISA, western blotting, duel-luciferase, reverse transcription-quantitative PCR and flow cytometry. The results showed that tyrosol significantly inhibited the adhesion of THP-1 human umbilical vein endothelial cells, reduced lipopolysaccharide-induced cell migration and decreased the release of pro-inflammatory factors and the expression levels of adhesion-related molecules, such as TNF-α, monocyte chemotactic protein-1, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. Previous studies indicate that NF-κB could serve a pivotal role in initiating the inflammatory responses of endothelial cells and particularly in regulating the expression of adhesion molecules and inflammatory factors. The results of the current study demonstrated that tyrosol was associated with decreased expression of adhesion molecules and monocyte-endothelial cell adhesion, thus suggesting that tyrosol could be a novel pharmacological approach for treating inflammatory vascular diseases.

MiR-145-5p targets MMP2 to protect brain injury in hypertensive intracerebral hemorrhage via inactivation of the Wnt/β-catenin signaling pathway.

BackgroundDifferences in microRNA (miRNA) expression after hypertensive intracerebral hemorrhage (HICH) have been reported in human and animal models. miRNA-145 plays an important role in vascular endothelial cells. The purpose of this work was to determine the role of miR-145-5p in HICH and the molecular mechanisms by which it acts.MethodsIn this study, we constructed a model of hemoglobin-induced HICH in rats and used thrombin-treated human brain microvascular endothelial cells (hBMECs) to create a HICH cell model. To determine brain damage, we tested the rats’ neurological performance and measured the cerebral water level of their brain tissue. Cell counting kit 8 (CCK8) was used to determine the viability of cells. Apoptosis was detected using the terminal TdT-mediated dUTP nick end labeling (TUNEL) assay and flow cytometry (FCM). Starbase and TargetScan were used to predict and confirm target genes. Luciferase reporter gene experiments were used to confirm the predictions. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were used to identify the associated genes and proteins.ResultsWe observed a reduction in miRNA-145-5p expression in both the HICH cell model and the rat model. miRNA-145-5p overexpression increased cell survival and preserved newly created blood vessels and vascular permeability in hBMECs. MiRNA-145-5p has been predicted to target matrix metalloproteinase 2 (MMP2). Additionally, MMP2 was identified as a miR-145-5p target gene and shown to be substantially expressed in the thrombin-treated hBMECs. MMP2 overexpression suppressed miR-145-5p-mediated effects and increased hBMECs’ malfunction. In comparison with controls, the HICH + AAV-miR-145-5p group performed better on behavioral tests and had less brain water. Additionally, miR-145-5p injection increased ZO-1 and occludin expressions, as determined by immunohistochemical staining in the HICH rat model.ConclusionsmiRNA-145-5p protects against brain injury following HICH by targeting MMP2, suggesting a possible therapeutic mechanism for HICH.

Sphingosine 1-phosphate and its regulatory role in vascular endothelial cells.

Sphingosine 1-phosphate (S1P) is a bioactive metabolite of sphingomyelin. S1P activates a series of signaling cascades by acting on its receptors S1PR1-3 on endothelial cells (ECs), which plays an important role in endothelial barrier maintenance, anti-inflammation, antioxidant and angiogenesis, and thus is considered as a potential therapeutic biomarker for ischemic stroke, sepsis, idiopathic pulmonary fibrosis, cancers, type 2 diabetes and cardiovascular diseases. We presently review the levels of S1P in those vascular and vascular-related diseases. Plasma S1P levels were reduced in various inflammation-related diseases such as atherosclerosis and sepsis, but were increased in other diseases including type 2 diabetes, neurodegeneration, cerebrovascular damages such as acute ischemic stroke, Alzheimer's disease, vascular dementia, angina, heart failure, idiopathic pulmonary fibrosis, community-acquired pneumonia, and hepatocellular carcinoma. Then, we highlighted the molecular mechanism by which S1P regulated EC biology including vascular development and angiogenesis, inflammation, permeability, and production of reactive oxygen species (ROS), nitric oxide (NO) and hydrogen sulfide (H₂S), which might provide new ways for exploring the pathogenesis and implementing individualized therapy strategies for those diseases.

Effect of Ulinastatin on Syndecan-2-Mediated Vascular Damage in IDH2-Deficient Endothelial Cells.

Syndecan-2 (SDC2), a cell-surface heparin sulfate proteoglycan of the glycocalyx, is mainly expressed in endothelial cells. Although oxidative stress and inflammatory mediators have been shown to mediate dysfunction of the glycocalyx, little is known about their role in vascular endothelial cells. In this study, we aimed to identify the mechanism that regulates SDC2 expression in isocitrate dehydrogenase 2 (IDH2)-deficient endothelial cells, and to investigate the effect of ulinastatin (UTI) on this mechanism. We showed that knockdown of IDH2 induced SDC2 expression in human umbilical vein endothelial cells (HUVECs). Matrix metalloproteinase 7 (MMP7) influences SDC2 expression. When IDH2 was downregulated, MMP7 expression was increased, as was TGF-β signaling, which regulates MMP7. Inhibition of MMP7 activity using MMP inhibitor II significantly reduced SDC2, suggesting that IDH2 mediated SDC2 expression via MMP7. Moreover, expression of SDC2 and MMP7, as well as TGF-β signaling, increased in response to IDH2 deficiency, and treatment with UTI reversed this increase. Similarly, the increase in SDC2, MMP7, and TGF-β signaling in the aorta of IDH2 knockout mice was reversed by UTI treatment. These findings suggest that IDH2 deficiency induces SDC2 expression via TGF-β and MMP7 signaling in endothelial cells.

The Role of RASGRP2 in Vascular Endothelial Cells—A Mini Review

RAS guanyl nucleotide-releasing proteins (RASGRPs) are important proteins that act as guanine nucleotide exchange factors, which activate small GTPases and function as molecular switches for intracellular signals. The RASGRP family is composed of RASGRP1–4 proteins and activates the small GTPases, RAS and RAP. Among them, RASGRP2 has different characteristics from other RASGRPs in that it targets small GTPases and its localizations are different. Many studies related to RASGRP2 have been reported in cells of the blood cell lineage. Furthermore, RASGRP2 has also been reported to be associated with Huntington’s disease, tumors, and rheumatoid arthritis. In addition, we also recently reported RASGRP2 expression in vascular endothelial cells, and clarified the involvement of xenopus Rasgrp2 in the vasculogenesis process and multiple signaling pathways of RASGRP2 in human vascular endothelial cells with stable expression of RASGRP2. Therefore, this article outlines the existing knowledge of RASGRP2 and focuses on its expression and role in vascular endothelial cells, and suggests that RASGRP2 functions as a protective factor for maintaining healthy blood vessels.

CRIF1 deficiency suppresses endothelial cell migration via upregulation of RhoGDI2.

Rho GDP-dissociation inhibitor (RhoGDI), a downregulator of Rho family GTPases, prevents nucleotide exchange and membrane association. It is responsible for the activation of Rho GTPases, which regulate a variety of cellular processes, such as migration. Although RhoGDI2 has been identified as a tumor suppressor gene involved in cellular migration and invasion, little is known about its role in vascular endothelial cell (EC) migration. CR6-interacting factor 1 (CRIF1) is a CR6/GADD45-interacting protein with important mitochondrial functions and regulation of cell growth. We examined the expression of RhoGDI2 in CRIF1-deficient human umbilical vein endothelial cells (HUVECs) and its role in cell migration. Expression of RhoGDI2 was found to be considerably higher in CRIF1-deficient HUVECs along with suppression of cell migration. Moreover, the phosphorylation levels of Akt and CREB were decreased in CRIF1-silenced cells. The Akt-CREB signaling pathway was implicated in the changes in endothelial cell migration caused by CRIF1 downregulation. In addition to RhoGDI2, we identified another factor that promotes migration and invasion of ECs. Adrenomedullin2 (ADM2) is an autocrine/paracrine factor that regulates vascular tone and other vascular functions. Endogenous ADM2 levels were elevated in CRIF1-silenced HUVECs with no effect on cell migration. However, siRNA-mediated depletion of RhoGDI2 or exogenous ADM2 administration significantly restored cell migration via the Akt-CREB signaling pathway. In conclusion, RhoGDI2 and ADM2 play important roles in the migration of CRIF1-deficient endothelial cells.

The Role of Coagulation and Complement Factors for Mast Cell Activation in the Pathogenesis of Chronic Spontaneous Urticaria.

Chronic spontaneous urticaria (CSU) is a common skin disorder characterized by an almost daily recurrence of wheal and flare with itch for more than 6 weeks, in association with the release of stored inflammatory mediators, such as histamine, from skin mast cells and/or peripheral basophils. The involvement of the extrinsic coagulation cascade triggered by tissue factor (TF) and complement factors, such as C3a and C5a, has been implied in the pathogenesis of CSU. However, it has been unclear how the TF-triggered coagulation pathway and complement factors induce the activation of skin mast cells and peripheral basophils in patients with CSU. In this review, we focus on the role of vascular endothelial cells, leukocytes, extrinsic coagulation factors and complement components on TF-induced activation of skin mast cells and peripheral basophils followed by the edema formation clinically recognized as urticaria. These findings suggest that medications targeting activated coagulation factors and/or complement components may represent new and effective treatments for patients with severe and refractory CSU.

Endothelial Cells in Emerging Viral Infections.

There are several reasons to consider the role of endothelial cells in COVID-19 and other emerging viral infections. First, severe cases of COVID-19 show a common breakdown of central vascular functions. Second, SARS-CoV-2 replicates in endothelial cells. Third, prior deterioration of vascular function exacerbates disease, as the most common comorbidities of COVID-19 (obesity, hypertension, and diabetes) are all associated with endothelial dysfunction. Importantly, SARS-CoV-2's ability to infect endothelium is shared by many emerging viruses, including henipaviruses, hantavirus, and highly pathogenic avian influenza virus, all specifically targeting endothelial cells. The ability to infect endothelium appears to support generalised dissemination of infection and facilitate the access to certain tissues. The disturbed vascular function observed in severe COVID-19 is also a prominent feature of many other life-threatening viral diseases, underscoring the need to understand how viruses modulate endothelial function. We here review the role of vascular endothelial cells in emerging viral infections, starting with a summary of endothelial cells as key mediators and regulators of vascular and immune responses in health and infection. Next, we discuss endotheliotropism as a possible virulence factor and detail features that regulate viruses' ability to attach to and enter endothelial cells. We move on to review how endothelial cells detect invading viruses and respond to infection, with particular focus on pathways that may influence vascular function and the host immune system. Finally, we discuss how endothelial cell function can be dysregulated in viral disease, either by viral components or as bystander victims of overshooting or detrimental inflammatory and immune responses. Many aspects of how viruses interact with the endothelium remain poorly understood. Considering the diversity of such mechanisms among different emerging viruses allows us to highlight common features that may be of general validity and point out important challenges.

Effect of malignant-associated pleural effusion on endothelial viability, motility and angiogenesis in lung cancer.

Malignant pleural effusion (MPE) and paramalignant pleural effusion (PPE) remain debilitating complications in lung cancer patients with poor prognosis and limited treatment options. The role of vascular endothelial cells has not been explored in the pleural environment of lung cancer. By integrating MPE and PPE as malignant‐associated pleural fluid (MAPF), the current study aimed to evaluate the effect of MAPF on cell proliferation, migration and angiogenesis of HUVEC. First, increased capillaries were identified in the subpleural layer of lung adenocarcinoma. Compatible with pathological observations, the ubiquitous elevation of HUVEC survival was identified in MAPF culture regardless of the underlying cancer type, the driver gene mutation, prior treatments and evidence of malignant cells in pleural fluid. Moreover, MAPF enhanced HUVEC motility with the formation of lamellipodia and filopodia and focal adhesion complex. Tube formation assay revealed angiogenic behavior with the observation of sheet‐like structures. HUVEC cultured with MAPF resulted in a significant increase in MAPK phosphorylation. Accompanied with VEGFR2 upregulation in MAPF culture, there was increased expressions of p‐STAT3, HIF‐1α and Nf‐kB. VEGF/VEGFR2 blockade regressed endothelial migration and angiogenesis but not cell proliferation. Our data indicate the angiogenic activities of MAPF on vascular endothelial cells that revealed increased pleural capillaries in lung cancer. Targeting the VEGF/VEGFR2 pathway might modulate the angiogenic propensity of MAPF in future clinical investigations.

Anlotinib alters tumor immune microenvironment by downregulating PD-L1 expression on vascular endothelial cells

Aberrant vascular network is a hallmark of cancer. However, the role of vascular endothelial cells (VECs)-expressing PD-L1 in tumor immune microenvironment and antiangiogenic therapy remains unclear. In this study, we used the specimens of cancer patients for immunohistochemical staining to observe the number of PD-L1+ CD34+ VECs and infiltrated immune cells inside tumor specimens. Immunofluorescence staining and flow cytometry were performed to observe the infiltration of CD8+ T cells and FoxP3+ T cells in tumor tissues. Here, we found that PD-L1 expression on VECs determined CD8+ T cells’, FoxP3+ T cells’ infiltration, and the prognosis of patients with lung adenocarcinoma. Anlotinib downregulated PD-L1 expression on VECs through the inactivation of AKT pathway, thereby improving the ratio of CD8/FoxP3 inside tumor and remolding the immune microenvironment. In conclusion, our results demonstrate that PD-L1 high expression on VECs inhibits the infiltration of CD8+ T cells, whereas promotes the aggregation of FoxP3+ T cells into tumor tissues, thus becoming an “immunosuppressive barrier”. Anlotinib can ameliorate the immuno-microenvironment by downregulating PD-L1 expression on VECs to inhibit tumor growth.

Fatty Acid-binding Protein 4 Expression in Tumor Cells as a Potential Marker for Anaplastic Meningiomas.

Meningiomas are highly vascularized tumors originating from arachnoid cap cells of the leptomeninges. The majority of meningiomas are classified as World Health Organization (WHO) grade I and display a benign clinical course with a low risk of recurrence. In contrast, WHO grade III meningiomas carry a high risk of recurrence and poor prognosis. However, it is commonly recognized that histopathologic grading does not always reliably predict recurrence or progression of meningiomas. Fatty acid-binding protein 4 (FABP4) is a small molecular weight lipid chaperone that plays a proangiogenic role in vascular endothelial cells. FABP4 is not expressed in normal brain vasculature but is detected in some glioblastoma and arteriovenous malformations. The expression pattern of FABP4 in meningiomas have not been reported to date. We analyzed FABP4 expression in a cohort of paraffin-embedded meningioma specimens by immunohistochemistry and double immunofluorescence analyses. FABP4 expression was detected in a subset of endothelial cells in 47 of 48 meningioma samples analyzed. Interestingly, tumor cell-FABP4 expression was also detected in only 1 of 22 grade I, none of grade II, but 10 of 12 grade III meningiomas (P<0.0001). These results demonstrate that FABP4 is commonly expressed in meningioma vascular endothelial cells while tumor cell expression of FABP4 is primarily observed in anaplastic meningiomas. A combination of FABP4 immunostaining with histopathologic grading might provide a more accurate prediction of the biological behavior of meningiomas than histopathologic grading alone.

NEDD4 protects vascular endothelial cells against Angiotensin II-induced cell death via enhancement of XPO1-mediated nuclear export

NEDD4 is an E3 ubiquitin ligase containing the HECT domain, which regulates various cellular processes, but its role in vascular endothelial cells is unknown. In the present study, we found that NEDD4 bound directly to XPO1 by co-immunoprecipitation screening. In HUVECs (human umbilical vein endothelial cells), overexpression of NEDD4 reduced Ang II-induced ROS level and cell apoptosis. Ang II stimulation led to nuclear accumulation of cargoes, while overexpression of NEDD4 enhanced the XPO1-dependent nuclear export of its cargoes. KPT185, an inhibitor of XPO1, can abolished the protective effect of NEDD4 under Ang II treatment. In addition, NEDD4 could promote the interaction between XPO1 and RanBP3 via K63-linked ubiquitination of XPO1. These results suggested that NEDD4 played a protective role in vascular endothelial cell injury through regulating XPO1-mediated nuclear export.

Sensitization of Vascular Endothelial Cells to Ionizing Radiation Promotes the Development of Delayed Intestinal Injury in Mice.

Exposure of the gastrointestinal (GI) tract to ionizing radiation can cause acute and delayed injury. However, critical cellular targets that regulate the development of radiation-induced GI injury remain incompletely understood. Here, we investigated the role of vascular endothelial cells in controlling acute and delayed GI injury after total-abdominal irradiation (TAI). To address this, we used genetically engineered mice in which endothelial cells are sensitized to radiation due to the deletion of the tumor suppressor p53. Remarkably, we found that VE-cadherin-Cre; p53FL/FL mice, in which both alleles of p53 are deleted in endothelial cells, were not sensitized to the acute GI radiation syndrome, but these mice were highly susceptible to delayed radiation enteropathy. Histological examination indicated that VE-cadherin-Cre; p53FL/FL mice that developed delayed radiation enteropathy had severe vascular injury in the small intestine, which was manifested by hemorrhage, loss of microvessels and tissue hypoxia. In addition, using dual-energy CT imaging, we showed that VE-cadherin-Cre; p53FL/FL mice had a significant increase in vascular permeability of the small intestine in vivo 28 days after TAI. Together, these findings demonstrate that while sensitization of endothelial cells to radiation does not exacerbate the acute GI radiation syndrome, it is sufficient to promote the development of late radiation enteropathy.

CircRNAs: Potential Targets for the Prevention and Treatment of Cerebrovascular Diseases

circRNAs, as a kind of non-coding RNA, are characterized by rich content, high stability, and tissue specificity, and have become a research focus in recent years. A large number of studies have found that circRNA and miRNA have the strongest binding capacity among competing endogenous RNAs, playing a role as a miRNA molecular sponge in cellular gene expression and playing an important role in many diseases. At present, studies have shown that circRNAs are closely related to cerebrovascular diseases and play a crucial role in vascular endothelial cells, metabolism of low-density lipoprotein, smooth muscle cells, inflammatory oxidative stress, ischemia-reperfusion, and other regulatory mechanisms. In order to systematically understand circRNA and its function, in order to understand the research progress of circRNA in regulating the molecular mechanism of cerebrovascular diseases, and in order to find potential markers and drug molecules in the field of cerebrovascular disease occurrence, development, diagnosis, and treatment targets, we reviewed the research progress of circRNA in the development of cerebrovascular disease.

Reversal of Osteoporotic Activity by Endothelial Cell-Secreted Bone Targeting and Biocompatible Exosomes.

Exosomes, also known as extracellular vesicles, are naturally occurring, biocompatible, and bioacive nanoparticles ranging from 40 to 150 nm in diameter. Bone-secreted exosomes play important roles in bone homeostasis, the interruption of which can lead to diseases such as osteoporosis, rheumatoid arthritis, and osteopetrosis. Though the relationship between vascular and bone homeostasis has been recognized recently, the role of vascular endothelial cell (EC)-secreted exosomes (EC-Exos) in bone homeostasis is not well understood. Herein, we found that EC-Exos show more efficient bone targeting than osteoblast-derived exosomes or bone marrow mesenchymal stem cell-derived exosomes. We also found that EC-Exos can be internalized by bone marrow-derived macrophages (BMMs) to alter their morphology. EC-Exos can inhibit osteoclast activity in vitro and inhibit osteoporosis in an ovariectomized mouse model. Sequencing of exosome miRNA revealed that miR-155 was highly expressed in EC-Exos-treated BMMs. The miR-155 level in EC-Exos was much higher than that in BMMs and ECs, indicating that miR-155 was endogenous cargo of EC-derived vesicles. Blockage of BMMs miR-155 levels reversed the suppression by EC-Exos of osteoclast induction, confirming that exosomal miR-155 may have therapeutic potential against osteoporosis. Taken together, our findings suggest that EC-Exos may be utilized as a bone targeting and nontoxic nanomedicine for the treatment of bone resorption disorders.

Endothelium-Derived Semaphorin 3G Regulates Hippocampal Synaptic Structure and Plasticity via Neuropilin-2/PlexinA4

The proper interactions between blood vessels and neurons are critical for maintaining the strength of neural circuits and cognitive function. However, the precise molecular events underlying these interactions remain largely unknown. Here, we report that the selective knockout of semaphorin 3G (Sema3G) in endothelial cells impaired hippocampal-dependent memory and reduced dendritic spine density in CA1 neurons in mice; these effects were reversed after restoration of Sema3G levels in the hippocampus by AAV transfection. We further show that Sema3G increased excitatory synapse density via neuropilin-2/PlexinA4 signaling and through activation of Rac1. These results provide the first evidence that, in the central nervous system, endothelial Sema3G serves as a vascular-derived synaptic organizer that regulates synaptic plasticity and hippocampal-dependent memory. Our findings highlight the role of vascular endothelial cells in regulating cognitive function through intercellular communication with neurons in the hippocampus.