Changes and significance of vascular endothelial injury markers in patients with diabetes mellitus and pulmonary thromboembolism.

BACKGROUND: To investigate the changes and clinical significance of vascular endothelial injury markers in type 2 diabetes mellitus (T2DM) complicated with pulmonary embolism (PE). METHODS: This prospective study enrolled patients with T2DM hospitalized in one hospital from January 2021 to June 2022. Soluble thrombomodulin (sTM) (ELISA), von Willebrand factor (vWF) (ELISA), and circulating endothelial cells (CECs) (flow cytometry) were measured. PE was diagnosed by computed tomography pulmonary angiography (CTPA). RESULTS: Thirty participants were enrolled in each group. The plasma levels of sTM (151.22 ± 120.57 vs. 532.93 ± 243.82 vs. 1016.51 ± 218.00 pg/mL, P < 0.001) and vWF (9.63 ± 2.73 vs. 11.50 ± 2.17 vs. 18.02 ± 3.40 ng/mL, P < 0.001) and the percentage of CECs (0.17 ± 0.46 vs. 0.30 ± 0.08 vs. 0.56 ± 0.18%, P < 0.001) gradually increased from the control group to the T2DM group to the T2DM + PE group. sTM (OR = 1.002, 95%CI: 1.002-1.025, P = 0.022) and vWF (OR = 1.168, 95%CI: 1.168-2.916, P = 0.009) were associated with T2DM + PE. sTM > 676.68 pg/mL for the diagnosis of T2DM + PE achieved an AUC of 0.973, while vWF > 13.75 ng/mL achieved an AUC of 0.954. The combination of sTM and vWF above their cutoff points achieved an AUC of 0.993, with 100% sensitivity and 96.7% specificity. CONCLUSIONS: Patients with T2DM show endothelial injury and dysfunction, which were worse in patients with T2DM and PE. High sTM and vWF levels have certain clinical predictive values for screening T2DM accompanied by PE.

How does particulate air pollution affect barrier functions and inflammatory activity of lung vascular endothelium?

Both particulate matter and gaseous components of air pollution have already been shown to increase cardiovascular mortality in numerous studies. It is, however, important to note that on their way to the bloodstream the polluting agents pass the lung barrier. Inside the alveoli, particles of approximately 0.4-1 µm are most efficiently deposited and commonly undergo phagocytosis by lung macrophages. Not only the soluble agents, but also particles fine enough to leave the alveoli enter the bloodstream in this finite part of the endothelium, reaching thus higher concentrations in close proximity of the alveoli and endothelium. Additionally, deposits of particulate matter linger in direct proximity of the endothelial cells and may induce inflammation, immune responses, and influence endothelial barrier dysfunction thus increasing PM bioavailability in positive feedback. The presented discussion provides an overview of possible components of indoor PM and how endothelium is thus influenced, with emphasis on lung vascular endothelium and clinical perspectives.

Characterization of intravascular papillary endothelial hyperplasia: a multicentre cohort.

Intravascular papillary endothelial hyperplasia (IPEH) is an uncommon benign malformation of the skin and subcutaneous tissue. In this retrospective multicentre study, we aimed to investigate the clinical and pathological features of 261 patients with IPEH. IPEH is classified into three categories; in our study, the proportions were pure (50%), mixed (46%) and extravascular (4%). IPEH frequently stained positive for immunohistochemical markers such as CD31, CD34, smooth muscle actin and erythroblast transformation-specific-related gene. Clinicians' initial impression of the lesion often included ambiguous terms such as 'soft tissue mass'. There is an opportunity for increased awareness of this lesion and its consideration within a differential diagnosis.

Central Nervous System Stimulants Limit Caffeine Transport at the Blood-Cerebrospinal Fluid Barrier.

Caffeine, a common ingredient in energy drinks, crosses the blood-brain barrier easily, but the kinetics of caffeine across the blood-cerebrospinal fluid barrier (BCSFB) has not been investigated. Therefore, 127 autopsy cases (Group A, 30 patients, stimulant-detected group; and Group B, 97 patients, no stimulant detected group) were examined. In addition, a BCSFB model was constructed using human vascular endothelial cells and human choroid plexus epithelial cells separated by a filter, and the kinetics of caffeine in the BCSFB and the effects of 4-aminopyridine (4-AP), a neuroexcitatory agent, were studied. Caffeine concentrations in right heart blood (Rs) and cerebrospinal fluid (CSF) were compared in the autopsy cases: caffeine concentrations were higher in Rs than CSF in Group A compared to Group B. In the BCSFB model, caffeine and 4-AP were added to the upper layer, and the concentration in the lower layer of choroid plexus epithelial cells was measured. The CSF caffeine concentration was suppressed, depending on the 4-AP concentration. Histomorphological examination suggested that choroid plexus epithelial cells were involved in inhibiting the efflux of caffeine to the CSF. Thus, the simultaneous presence of stimulants and caffeine inhibits caffeine transfer across the BCSFB.

A Real-Time, Plate-Based BRET Assay for Detection of cGMP in Primary Cells.

Cyclic guanosine monophosphate (cGMP) is a second messenger involved in the regulation of numerous physiological processes. The modulation of cGMP is important in many diseases, but reliably assaying cGMP in live cells in a plate-based format with temporal resolution is challenging. The Förster/fluorescence resonance energy transfer (FRET)-based biosensor cGES-DE5 has a high temporal resolution and high selectivity for cGMP over cAMP, so we converted it to use bioluminescence resonance energy transfer (BRET), which is more compatible with plate-based assays. This BRET variant, called CYGYEL (cyclic GMP sensor using YFP-PDE5-Rluc8), was cloned into a lentiviral vector for use across different mammalian cell types. CYGYEL was characterised in HEK293T cells using the nitric oxide donor diethylamine NONOate (DEA), where it was shown to be dynamic, reversible, and able to detect cGMP with or without the use of phosphodiesterase inhibitors. In human primary vascular endothelial and smooth muscle cells, CYGYEL successfully detected cGMP mediated through either soluble or particulate guanylate cyclase using DEA or C-type natriuretic peptide, respectively. Notably, CYGYEL detected differences in kinetics and strength of signal both between ligands and between cell types. CYGYEL remained selective for cGMP over cAMP, but this selectivity was reduced compared to cGES-DE5. CYGYEL streamlines the process of cGMP detection in plate-based assays and can be used to detect cGMP activity across a range of cell types.

Serum Amyloid A Is Present in Human Saccular Intracranial Aneurysm Walls and Associates With Aneurysm Rupture.

Saccular intracranial aneurysm (sIA) rupture leads to a disabling subarachnoid hemorrhage. Chronic inflammation and lipid accumulation in the sIA wall contribute to wall degenerative remodeling that precedes its rupture. A better understanding of the pathobiological process is essential for improved future treatment of patients carrying sIAs. Serum amyloid A (SAA) is an acute-phase protein produced in response to acute and chronic inflammation and tissue damage. Here, we studied the presence and the potential role of SAA in 36 intraoperatively resected sIAs (16 unruptured and 20 ruptured), that had previously been studied by histology and immunohistochemistry. SAA was present in all sIAs, but the extent of immunopositivity varied greatly. SAA immunopositivity correlated with wall degeneration (p = 0.028) and rupture (p = 0.004), with numbers of CD163-positive and CD68-positive macrophages and CD3-positive T lymphocytes (all p < 0.001), and with the expression of myeloperoxidase, matrix metalloproteinase-9, prostaglandin E-2 receptor, and cyclo-oxygenase 2 in the sIA wall. Moreover, SAA positivity correlated with the accumulation of apolipoproteins A-1 and B-100. In conclusion, SAA occurs in the sIA wall and, as an inflammation-related factor, may contribute to the development of a rupture-prone sIA.

Role of endothelial glycocalyx in sliding friction at the catheter-blood vessel interface.

Catheterization is a common medical operation to diagnose and treat cardiovascular diseases. The blood vessel lumen is coated with endothelial glycocalyx layer (EGL), which is important for the permeability and diffusion through the blood vessels wall, blood hemodynamics and mechanotransduction. However EGL's role in catheter-blood vessel friction is not explored. We use a porcine aorta to mimic the blood vessel and a catheter loop was made to rub in reciprocating sliding mode against it to understand the role of catheter loop curvature, stiffness, normal load, sliding speed and EGL on the friction properties. Trypsin treatment was used to cause a degradation of the EGL. Decrease in catheter loop stiffness and EGL degradation were the strongest factors which dramatically increased the coefficient of friction (COF) and frictional energy dissipation at the aorta-catheter interface. Increasing sliding speed caused an increase but increase in normal load first caused a decrease and then an increase in the COF and frictional energy. These results provide the basic data for safety of operation and damage control during catheterization in patients with degraded EGL.

Cav-1 (Caveolin-1) Deficiency Increases Autophagy in the Endothelium and Attenuates Vascular Inflammation and Atherosclerosis.

OBJECTIVE: Endothelial Cav-1 (caveolin-1) expression plays a relevant role during atherogenesis by controlling NO production, vascular inflammation, LDL (low-density lipoprotein) transcytosis, and extracellular matrix remodeling. Additional studies have identified cholesterol-rich membrane domains as important regulators of autophagy by recruiting ATGs (autophagy-related proteins) to the plasma membrane. Here, we investigate how the expression of Cav-1 in the aortic endothelium influences autophagy and whether enhanced autophagy contributes to the atheroprotective phenotype observed in Cav-1-deficient mice. Approach and Results: To analyze the impact of Cav-1 deficiency on regulation of autophagy in the aortic endothelium during the progression of atherosclerosis, we fed Ldlr-/- and Cav-1-/-Ldlr-/- mice a Western diet and assessed autophagy in the vasculature. We observe that the absence of Cav-1 promotes autophagy activation in athero-prone areas of the aortic endothelium by enhancing autophagic flux. Mechanistically, we found that Cav-1 interacts with the ATG5-ATG12 complex and influences the cellular localization of autophagosome components in lipid rafts, which controls the autophagosome formation and autophagic flux. Pharmacological inhibition of autophagy attenuates the atheroprotection observed in Cav-1-/- mice by increasing endothelial inflammation and macrophage recruitment, identifying a novel molecular mechanism by which Cav-1 deficiency protects against the progression of atherosclerosis. CONCLUSIONS: These results identify Cav-1 as a relevant regulator of autophagy in the aortic endothelium and demonstrate that pharmacological suppression of autophagic flux in Cav-1-deficient mice attenuates the atheroprotection observed in Cav-1-/- mice. Additionally, these findings suggest that activation of endothelial autophagy by blocking Cav-1 might provide a potential therapeutic strategy for cardiovascular diseases including atherosclerosis.

Tailoring of cardiovascular stent material surface by immobilizing exosomes for better pro-endothelialization function.

Stent intervention as available method in clinic has been widely applied for cardiovascular disease treatment for decades. However, the restenosis caused by late thrombosis and hyperplasia still limits the stents long-term application, and the essential cause is usually recognized as endothelial functionalization insufficiency of the stent material surface. Here, we address this limitation by developing a pro-endothelial-functionalization surface that immobilized a natural factors-loaded nanoparticle, exosome, onto the poly-dopamine (PDA) coated materials via electrostatic binding. This PDA/Exosome surface not only increased the endothelial cells number on the materials, but also improved their endothelial function, including platelet endothelial cell adhesion molecule-1 (CD31) expression, cell migration and nitric oxide release. The pro-inflammation macrophage (M1 phenotype) attachment and synthetic smooth muscle cell proliferation as the interference factors for the endothelialization were not only inhibited by the PDA/Exosome coating, while the cells were also regulated to anti-inflammation macrophage (M2 phenotype) and contractile smooth muscle cell, which may contribute to endothelialization. Thus, it can be summarized this method has potential application on surface modification of cardiovascular biomaterials.

Combination of curcumin and luteolin synergistically inhibits TNF-α-induced vascular inflammation in human vascular cells and mice.

Emerging evidence shows that phytochemicals, the secondary plant metabolites present in a large variety of foods, have the potential ability in reducing the risk of cardiovascular diseases. However, the dosages of phytochemicals in the cellular and animal studies are too high to reach in humans by relevant foods or dietary supplement intake. The aims of this study were to investigate whether and how combined curcumin and luteolin synergistically inhibit tumor necrosis factor-alpha (TNF-α)-induced monocytes adhesion endothelium, a crucial step of the development of endothelial dysfunction, both in human vascular cells and mouse aortic endothelium. Our results show that combined curcumin (1 µM) and luteolin (0.5 µM) synergistically (combination index is 0.60) inhibited TNF-α-induced monocytes adhesion to human EA.hy926 endothelial cells while the individual chemicals did not have such effect at the selected concentrations. We also found that TNF-α-enhanced protein expressions of vascular cell adhesion molecule 1 (VCAM-1), monocyte chemotactic protein-1 (MCP-1) and nuclear factor (NF)-κB translocation were synergistically reduced by the combined curcumin and luteolin in EA.hy 926 cells while the individual chemical did not have this inhibitory effect. Consistently, 2 weeks dietary intake of combined curcumin (500 mg/kg) and luteolin (500 mg/kg) in C57BL/6 mice synergistically prevented TNF-α-stimulated adhesion of mouse monocytes to aortic endothelium ex vivo as well as the TNF-α-increased aortic protein expression of MCP-1 and VCAM-1. Therefore, combined curcumin and luteolin at physiological concentrations synergistically inhibits TNF-α-induced monocytes adhesion to endothelial cells and expressions of MCP-1 and VCAM-1 via suppressing NF-κB translocation into the nucleus.

In Vivo Calpain Knockdown Using Delivery of siRNA.

Calpain is an intracellular Ca2+-dependent non-lysosomal cysteine protease expressed ubiquitously in mammals. In endothelial cells, dysregulation of calpain has been shown to be involved in a wide variety of pathological conditions such as angiogenesis, vascular inflammation, and diabetes. Cell- or tissue-targeted in vivo delivery of small interfering RNA (siRNA) is a powerful research tool in the analysis of protein function and has been proposed as an attractive therapeutic modality that is applicable against a large number of human diseases including cancer. In this chapter we describe a method to knockdown calpain 1 in mouse pulmonary vascular endothelium using delivery of siRNA/cationic liposome complex. This technique results in a greater than 80% reduction in calpain 1 protein levels 48 h after a single i.v. injection of calpain 1 siRNA (0.5 mg siRNA/kg)/cationic liposome complex. We also describe confocal imaging to verify the loss of calpain 1 expression in pulmonary microvessel endothelial cells and application of this technique in the mouse model of ventilator-induced lung injury.

Sphingosine-1-phosphate protects against brain microvascular endothelial junctional protein disorganization and barrier dysfunction caused by alcohol.

OBJECTIVE: S1P has known endothelial barrier-protective properties, but whether this extends to the BBB is unclear. We hypothesized that alcohol-induced disruption of brain microvascular endothelial barrier function and junctional protein organization can be ameliorated by S1P treatment. METHODS: Cultured primary HBMEC monolayers were used to characterize endothelial-specific mechanisms of BBB regulation. TER and apparent permeability coefficients for albumin, dextran-4 kDa, and sodium fluorescein were used as indices of barrier function. Junctional localization of Claudin-5, VE-cadherin, and ß-catenin was determined by immunofluorescence confocal microscopy. S1P was applied following treatment with alcohol. RESULTS: Alcohol significantly impaired HBMEC TER. Application of S1P after alcohol treatment resulted in a hastened recovery to the baseline HBMEC TER. Alcohol-treated HBMEC had a significantly higher mean permeability than control that was reversed by S1P. Alcohol caused the formation of gaps between cells. Treatment with S1P (after alcohol) increased junctional localization of VE-Cadherin, Claudin-5, and ß-catenin. CONCLUSIONS: Alcohol impairs the barrier function and junctional organization of HBMEC monolayers. S1P enhanced barrier function and restored junctions in the presence of alcohol, and thus may be useful for restoring BBB function during alcohol intoxication.

Simultaneous Study of the Recruitment of Monocyte Subpopulations Under Flow In Vitro.

The recruitment of monocytes from the blood to targeted peripheral tissues is critical to the inflammatory process during tissue injury, tumor development and autoimmune diseases. This is facilitated through a process of capture from free flow onto the luminal surface of activated endothelial cells, followed by their adhesion and transendothelial migration (transmigration) into the underlying affected tissue. However, the mechanisms that support the preferential and context-dependent recruitment of monocyte subpopulations are still not fully understood. Therefore, we have developed a method that allows the recruitment of different monocyte subpopulations to be simultaneously visualized and measured under flow. This method, based on time-lapse confocal imaging, allows for the unambiguous distinction between adherent and transmigrated monocytes. Here, we describe how this method can be used to simultaneously study the recruitment cascade of pro-angiogenic and non-angiogenic monocytes in vitro. Furthermore, this method can be extended to study the different steps of recruitment of up to three monocyte populations.

Highly Efficient In Vivo Targeting of the Pulmonary Endothelium Using Novel Modifications of Polyethylenimine: An Importance of Charge.

Pulmonary vascular disease encompasses a wide range of serious afflictions with important clinical implications. There is critical need for the development of efficient, nonviral gene therapy delivery systems. Here, a promising avenue to overcome critical issues in efficient cell targeting within the lung via a uniquely designed nanosystem is reported. Polyplexes are created by functionalizing hyperbranched polyethylenimine (PEI) with biological fatty acids and carboxylate-terminated poly(ethylene glycol) (PEG) through a one-pot 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride/N-hydroxysuccinimide reaction. Following intravenous injection, polyplexes show an exceptionally high specificity to the pulmonary microvascular endothelium, allowing for the successful delivery of stabilized enhanced green fluorescent protein (eGFP) expressing messenger ribonucleic acid (mRNA). It is further shown, quantitatively, that positive surface charge is the main mechanism behind such high targeting efficiency for these polyplexes. Live in vivo imaging, flow cytometry of single cell suspensions, and confocal microscopy are used to demonstrate that positive polyplexes are enriched in the lung tissue and disseminated in 85-90% of the alveolar capillary endothelium, whilst being sparse in large vessels. Charge modification, achieved through poly(acrylic acid) or heparin coating, drives a highly significant reduction in both targeting percentage and targeting strength, highlighting the importance of specific surface charge, derived from chemical formulation, for efficient targeting of the pulmonary microvascular endothelium.

Coaxial Cell Printing of Freestanding, Perfusable, and Functional In Vitro Vascular Models for Recapitulation of Native Vascular Endothelium Pathophysiology.

3D printing technology is used to produce channels within hydrogels followed by endothelial cells (ECs)-seeding to establish in vitro vascular models. However, as built-in bulk hydrogels, it is difficult to incorporate additional cells and molecules into the crosslinked matrix to study the pathophysiological responses of healthy endothelium. In this study, freestanding in vitro vascular models (VMs) are developed using the coaxial cell printing technique and a vascular tissue-specific bioink. It has various advantages in plotting tubular cell-laden vessels with designed patterns, providing pump-driven circulating perfusion, generating endothelium without ECs-seeding, and implementing further expansions to study vascular pathophysiology. Following the maturation of endothelium, the VMs exhibit representative vascular functions (i.e., selective permeability, antiplatelets/leukocytes adhesion, and vessel remodeling under shear stress). Moreover, with the expansions of the VMs, the directional angiogenesis and inflammatory responses are demonstrated by giving asymmetric distributions of proangiogenic factors and an airway inflammatory ambience, respectively. Therefore, the freestanding, perfusable, and functional VMs can be useful devices to engineer diverse in vitro platforms for a wide range of biomedical applications, from modeling blood vessel relevant diseases to building vascularized tissues/organs.

Aberrant pro-atrial natriuretic peptide/corin/natriuretic peptide receptor signaling is present in maternal vascular endothelium in preeclampsia.

OBJECTIVE: Corin is a serine protease that converts pro-atrial natriuretic peptide (pro-ANP) to atrial natriuretic peptide (ANP), a cardiac hormone that regulates salt-water balance and blood pressure. ANP is degraded by natriuretic peptide receptor (NPR). This study was to determine if aberrant pro-ANP/corin/NPR signaling is present in maternal vascular system in preeclampsia. STUDY DESIGN: Maternal venous blood was obtained from 197 pregnant women (84 normotensive, 16 complicated with chronic hypertension (CHT), 11 mild and 86 severe preeclampsia). Plasma corin and pro-ANP concentrations were measured by enzyme-linked immunosorbent assay. Maternal subcutaneous fat tissue was obtained from 12 pregnant women with cesarean section delivery (6 normotensive and 6 preeclampsia). Vascular ANP and its receptors NPR-A, NPR-B, and NPR-C expression were examined by immunostaining of paraffin embedded subcutaneous fat tissue sections. RESULTS: Corin concentrations were significantly higher in mild (2.78 ±â€¯0.67 ng/ml, p < .05) and severe (2.53 ±â€¯0.18 ng/ml, p < .01) preeclampsia than in normotensive (1.58 ±â€¯0.08 ng/ml) and CHT (1.55 ±â€¯0.20 ng/ml) groups. Pro-ANP concentrations were significantly higher in CHT (1.59 ±â€¯0.53 ng/ml, p < .05) and severe preeclampsia (1.42 ±â€¯0.24 ng/ml, p < .01) than in normotensive (0.48 ±â€¯0.06 ng/ml) and mild preeclampsia (0.52 ±â€¯0.09 ng/ml) groups. ANP and NPR-B expression was undetectable in maternal vessels from normotensive and preeclamptic pregnancies, but reduced NPR-A expression and increased NPR-C expression was found in maternal vessel endothelium in preeclampsia. CONCLUSIONS: ANP is a vasodilator and NPR-C is a clearance receptor for ANP. The finding of upregulation of NPR-C expression suggests that circulating ANP clearance or degradation is increased in preeclampsia. These results also suggest that pro-ANP/corin/NPR signaling is dominant in the vascular system in preeclampsia.

Analysis of Combined Transcriptomes Identifies Gene Modules that Differentially Respond to Pathogenic Stimulation of Vascular Smooth Muscle and Endothelial Cells.

Smooth muscle cells (SMCs) and endothelial cells (ECs) are vital cell types composing the vascular medial wall and the atheroprotective inner lining, respectively. Current treatments for cardiovascular disease inhibit SMC hyperplasia but compromise EC integrity, predisposing patients to thrombosis. Therapeutics targeting SMCs without collateral damage to ECs are highly desirable. However, differential (SMC versus EC) disease-associated regulations remain poorly defined. We conducted RNA-seq experiments to investigate SMC-versus-EC differential transcriptomic dynamics, following treatment of human primary SMCs and ECs with TNFα or IL-1ß, both established inducers of SMC hyperplasia and EC dysfunction. As revealed by combined SMC/EC transcriptomes, after TNFα or IL-1ß induction, 174 and 213 genes respectively showed greater up-regulation in SMCs than in ECs (SMC-enriched), while 117 and 138 genes showed greater up-regulation in ECs over SMCs (EC-enriched). Analysis of gene interaction networks identified central genes shared in the two SMC-enriched gene sets, and a distinct group of central genes common in the two EC-enriched gene sets. Significantly, four gene modules (subnetworks) were identified from these central genes, including SMC-enriched JUN and FYN modules and EC-enriched SMAD3 and XPO1 modules. These modules may inform potential intervention targets for selective blockage of SMC hyperplasia without endothelial damage.

Assessment of endothelialization of aneurysm wall over time in a rabbit model through CD31 scoring.

BACKGROUND: Intracranial aneurysms represent a significant health concern and are poorly understood despite decades of research. Our study focused on understanding temporal patterns of endothelial cell distribution in different spatial locations within the aneurysm early after creation in a rabbit model. METHODS: Elastase induced saccular aneurysms were created in rabbits and harvested on day 1 (n=3) and after 2 (n=5), 4 (n=4), 8 (n=5), and 12 (n=6) weeks. Sham operated controls (n=3) were harvested on the same day. Aneurysm and control tissue samples were subjected to en face whole mount CD31 staining for endothelial cells. Semiquantitative scoring was performed on the basis of endothelial coverage of the vessel wall (proximal, middle, and distal portions of the aneurysm dome). Mixed effects models were used to assess the effect of time and aneurysm section on endothelial coverage. RESULTS: Aneurysmal segments were near completely de-endothelialized at 4 and 8 weeks but had re-endothelialized by 12 weeks. Compared with controls, aneurysms at all time points showed decreased endothelialization, but the difference was only significant compared with the 4 and 8 week groups. Both time (P=0.03) and aneurysm section (P=0.07) were significantly associated with the degree of endothelialization. Proximal locations showed increased endothelialization compared with distal locations (P=0.03). CONCLUSION: In experimental aneurysms of rabbits, endothelial cells regress during the first month after creation, followed by ascending re-endothelialization that stays incomplete. These findings suggest that re-population of endothelial cells comes from resident cells in the adjacent parent artery and that deranged hemodynamics may affect full reconstitution of endothelial cells long term.

NOTCH1 is a mechanosensor in adult arteries.

Endothelial cells transduce mechanical forces from blood flow into intracellular signals required for vascular homeostasis. Here we show that endothelial NOTCH1 is responsive to shear stress, and is necessary for the maintenance of junctional integrity, cell elongation, and suppression of proliferation, phenotypes induced by laminar shear stress. NOTCH1 receptor localizes downstream of flow and canonical NOTCH signaling scales with the magnitude of fluid shear stress. Reduction of NOTCH1 destabilizes cellular junctions and triggers endothelial proliferation. NOTCH1 suppression results in changes in expression of genes involved in the regulation of intracellular calcium and proliferation, and preventing the increase of calcium signaling rescues the cell-cell junctional defects. Furthermore, loss of Notch1 in adult endothelium increases hypercholesterolemia-induced atherosclerosis in the descending aorta. We propose that NOTCH1 is atheroprotective and acts as a mechanosensor in adult arteries, where it integrates responses to laminar shear stress and regulates junctional integrity through modulation of calcium signaling.