Vascular Endothelial Barrier Function Research Articles

Mechanisms underlying age-associated exacerbation of pulmonary veno-occlusive disease.

Pulmonary veno-occlusive disease (PVOD) is a rare but severe form of pulmonary hypertension characterized by the obstruction of pulmonary arteries and veins, causing increased pulmonary artery pressure and leading to right ventricular (RV) heart failure. PVOD is often resistant to conventional pulmonary arterial hypertension (PAH) treatments and has a poor prognosis, with a median survival time of 2 to 3 years after diagnosis. We previously showed that the administration of a chemotherapy agent mitomycin C (MMC) in rats mediates PVOD through the activation of the eukaryotic initiation factor 2 (eIF2) kinase protein kinase R (PKR) and the integrated stress response (ISR), resulting in the impairment of vascular endothelial junctional structure and barrier function. Here, we demonstrate that aged rats over one year exhibit more severe vascular remodeling and RV hypertrophy than young adult rats following MMC treatment. This is attributed to an age-associated elevation of basal ISR activity and depletion of protein phosphatase 1, leading to prolonged eIF2 phosphorylation and sustained ISR activation. Pharmacological blockade of PKR or ISR mitigates PVOD phenotypes in both age groups, suggesting that targeting the PKR-ISR axis could be a potential therapeutic strategy for PVOD.

Knockdown of fibrillin-1 suppresses retina-blood barrier dysfunction by inhibiting vascular endothelial apoptosis under diabetic conditions.

To investigate the effects of fibrillin-1 (FBN1) deletion on the integrity of retina-blood barrier function and the apoptosis of vascular endothelial cells under diabetic conditions. Streptozotocin (STZ)-induced diabetic mice were used to simulate the diabetic conditions of diabetic retinopathy (DR) patients, and FBN1 expression was detected in retinas from STZ-diabetic mice and controls. In the Gene Expression Omnibus (GEO) database, the GSE60436 dataset was selected to analyze FBN1 expressions in fibrovascular membranes from DR patients. Using lentivirus to knock down FBN1 levels, vascular leakage and endothelial barrier integrity were detected by Evans blue vascular permeability assay, fluorescein fundus angiography (FFA) and immunofluorescence labeled with tight junction marker in vivo. High glucose-induced monkey retinal vascular endothelial cells (RF/6A) were used to investigate effects of FBN1 on the cells in vitro. The vascular endothelial barrier integrity and apoptosis were detected by trans-endothelial electrical resistance (TEER) assay and flow cytometry, respectively. FBN1 mRNA expression was increased in retinas of STZ-induced diabetic mice and fibrovascular membranes of DR patients (GSE60436 datasets) using RNA-seq approach. Besides, knocking down of FBN1 by lentivirus intravitreal injection significantly inhibited the vascular leakage compared to STZ-DR group by Evans blue vascular permeability assay and FFA detection. Expressions of tight junction markers in STZ-DR mouse retinas were lower than those in the control group, and knocking down of FBN1 increased the tight junction levels. In vitro, 30 mmol/L glucose could significantly inhibit viability of RF/6A cells, and FBN1 mRNA expression was increased under 30 mmol/L glucose stimulation. Down-regulation of FBN1 reduced high glucose (HG)-stimulated retinal microvascular endothelial cell permeability, increased TEER, and inhibited RF/6A cell apoptosis in vitro. The expression level of FBN1 increases in retinas and vascular endothelial cells under diabetic conditions. Down-regulation of FBN1 protects the retina of early diabetic rats from retina-blood barrier damage, reduce vascular leakage, cell apoptosis, and maintain vascular endothelial cell barrier function.

SphK1 deficiency ameliorates the development of atherosclerosis by inhibiting the S1P/S1PR3/Rhoa/ROCK pathway

Background and aimsS1P is an important factor regulating the function of the vascular endothelial barrier. SphK1 is an important limiting enzyme for the synthesis of S1P. However, the role of the SphK1/S1P-mediated vascular endothelial barrier function in atherosclerosis has not been fully revealed. This study explored the roles and mechanisms of SphK1 on atherosclerosis in vivo and in vitro. MethodsIn vivo, ApoE−/− and SphK1−/−ApoE−/− mice were fed a high-fat diet to induce atherosclerosis. In vitro, ox-LDL induced HUVECs to establish a cell model. Aortic histological changes were measured by H&E staining, Oil Red O staining, EVG staining, Sirius scarlet staining, immunofluorescence, and Evans Blue Assay. Western blotting was performed to explore the specific mechanism. ResultsWe validated that deficiency of SphK1 resulted in a marked amelioration of atherosclerosis, as indicated by the decreased lipid accumulation, inflammatory factors, oxidative stress, aortic plaque area, inflammatory factor infiltration, VCAM-1 expression, and vascular endothelial permeability. Moreover, deficiency of SphK1 downregulated the expression of aortic S1PR3, Rhoa, ROCK, and F-actin. The results of administration with the SphK1 inhibitor PF-543 and the S1PR3 inhibitor VPC23019 in vitro further confirmed the conclusion that deficiency of SphK1 reduced S1P level and S1PR3 protein expression, inhibited Rhoa/ROCK signaling pathway, regulated protein expression of F-actin, improved vascular endothelial dysfunction and permeability, and exerted anti-atherosclerotic effects. ConclusionsThis study revealed that deficiency of SphK1 relieved vascular endothelial barrier function in atherosclerosis mice via SphK1/S1P/S1PR signaling pathway.

The role of FPR2-mediated ferroptosis in formyl peptide-induced acute lung injury against endothelial barrier damage and protective effect of the mitochondria-derived peptide MOTS-c

BackgroundAcute lung injury (ALI) has garnered significant attention in the field of respiratory and critical care due to its high mortality and morbidity, and limited treatment options. The role of the endothelial barrier in the development of ALI is crucial. Several bacterial pathogenic factors, including the bacteria-derived formyl peptide (fMLP), have been implicated in damaging the endothelial barrier and initiating ALI. However, the mechanism by which fMLP causes ALI remains unclear. In this study, we aim to explore the mechanisms of ALI caused by fMLP and evaluate the protective effects of MOTS-c, a mitochondrial-derived peptide. MethodsWe established a rat model of ALI and a human pulmonary microvascular endothelial cell (HPMVEC) model of ALI by treatment with fMLP. In vivo experiments involved lung histopathology assays, assessments of inflammatory and oxidative stress factors, and measurements of ferroptosis-related proteins and barrier proteins to evaluate the severity of fMLP-induced ALI and the type of tissue damage in rats. In vitro experiments included evaluations of fMLP-induced damage on HPMVEC using cell activity assays, assessments of inflammatory and oxidative stress factors, measurements of ferroptosis-related proteins, endothelial barrier function assays, and examination of the key role of FPR2 in fMLP-induced ALI. We also assessed the protective effect of MOTS-c and investigated its mechanism on the fMLP-induced ALI in vivo and in vitro. ResultsResults from both in vitro and in vivo experiments demonstrate that fMLP promotes the expression of inflammatory and oxidative stress factors, activates ferroptosis and disrupts the vascular endothelial barrier, ultimately contributing to the development and progression of ALI. Mechanistically, ferroptosis mediated by FPR2 plays a key role in fMLP-induced injury, and the Nrf2 and MAPK pathways are involved in this process. Knockdown of FPR2 and inhibition of ferroptosis can attenuate ALI induced by fMLP. Moreover, MOTS-c could protect the vascular endothelial barrier function by inhibiting ferroptosis and suppressing the expression of inflammatory and oxidative stress factors through Nrf2 and MAPK pathways, thereby alleviating fMLP-induced ALI. ConclusionOverall, fMLP disrupts the vascular endothelial barrier through FPR2-mediated ferroptosis, leading to the development and progression of ALI. MOTS-c demonstrates potential as a protective treatment against ALI by alleviating the damage induced by fMLP.

Designer high-density lipoprotein particles enhance endothelial barrier function and suppress inflammation.

High-density lipoprotein (HDL) nanoparticles promote endothelial cell (EC) function and suppress inflammation, but their utility in treating EC dysfunction has not been fully explored. Here, we describe a fusion protein named ApoA1-ApoM (A1M) consisting of apolipoprotein A1 (ApoA1), the principal structural protein of HDL that forms lipid nanoparticles, and ApoM, a chaperone for the bioactive lipid sphingosine 1-phosphate (S1P). A1M forms HDL-like particles, binds to S1P, and is signaling competent. Molecular dynamics simulations showed that the S1P-bound ApoM moiety in A1M efficiently activated EC surface receptors. Treatment of human umbilical vein ECs with A1M-S1P stimulated barrier function either alone or cooperatively with other barrier-enhancing molecules, including the stable prostacyclin analog iloprost, and suppressed cytokine-induced inflammation. A1M-S1P injection into mice during sterile inflammation suppressed neutrophil influx and inflammatory mediator secretion. Moreover, systemic A1M administration led to a sustained increase in circulating HDL-bound S1P and suppressed inflammation in a murine model of LPS-induced endotoxemia. We propose that A1M administration may enhance vascular endothelial barrier function, suppress cytokine storm, and promote resilience of the vascular endothelium.

Receptor activity-modifying proteins of adrenomedullin (RAMP2/3): Roles in the pathogenesis of ARDS.

Acute respiratory distress syndrome (ARDS) is a life-threatening lung condition characterized by widespread inflammation and pulmonary edema. Adrenomedullin (AM), a bioactive peptide with various functions, is expected to be applied in treating ARDS. Its functions are regulated primarily by two receptor activity-modifying proteins, RAMP2 and RAMP3, which bind to the AM receptor calcitonin receptor-like receptor (CLR). However, the roles of RAMP2 and RAMP3 in ARDS remain unclear. We generated a mouse model of ARDS via intratracheal administration of lipopolysaccharide (LPS), and analyzed the pathophysiological significance of RAMP2 and RAMP3. RAMP2 expression declined with LPS administration, whereas RAMP3 expression increased at low doses and decreased at high doses of LPS. After LPS administration, drug-inducible vascular endothelial cell-specific RAMP2 knockout mice (DI-E-RAMP2−/−) showed reduced survival, increased lung weight, and had more apoptotic cells in the lungs. DI-E-RAMP2−/− mice exhibited reduced expression of Epac1 (which regulates vascular endothelial cell barrier function), while RAMP3 was upregulated in compensation. In contrast, after LPS administration, RAMP3−/− mice showed no significant changes in survival, lung weight, or lung pathology, although they exhibited significant downregulation of iNOS, TNF-α, and NLRP3 during the later stages of inflammation. Based on transcriptomic analysis, RAMP2 contributed more to the circulation-regulating effects of AM, whereas RAMP3 contributed more to its inflammation-regulating effects. These findings indicate that, while both RAMP2 and RAMP3 participate in ARDS pathogenesis, their functions differ distinctly. Further elucidation of the pathophysiological significance and functional differences between RAMP2 and RAMP3 is critical for the future therapeutic application of AM in ARDS.

The adrenomedullin system and risk of cardiogenic shock or death complicating acute coronary syndromes

Abstract Introduction Cardiogenic shock (CS) is the leading cause of death due to acute coronary syndromes (ACS) and mortality remained nearly unchanged over the past two decades. Immediate revascularization of the infarct-related artery is the treatment strategy of choice to reduce CS-related mortality, but early identification of patients at high risk of CS and death is challenging. The adrenomedullin (ADM) system modulates vascular tone and endothelial barrier function and monitoring its activity may enhance early risk assessment of ACS patients prone to experience CS and ultimately death. Methods In 4293 ACS patients, prospectively recruited at 4 Swiss university hospitals, the 3 major ADM system components were assessed in plasma at the time of acute presentation by blinded study personnel: ADM-glycine (its inactive substrate), peptidylglycine α-amidating monooxygenase (PAM; the ADM-amidating enzyme), and the biologically active ADM-amide (bio-ADM). Patients were monitored for in-hospital development of CS and followed at 30 days and 1 year with external event adjudication. The relationship of each ADM system component with features of CS pathophysiology (such as proxies for the decrease in cardiac contractile mass, increase in cardiac stress or systemic inflammation) was estimated by means of partial correlation coefficients. Multivariable-adjusted regression models were fit to assess their independent association with CS development and death. Results Baseline ADM-glycine, PAM and bio-ADM levels were tightly linked to features of CS (Fig. 1), with each ADM system component associating with in-hospital CS (odds ratio, 95% confidence interval [CI] per doubling in each, 2.04, 1.79-2.33, P<.001; 1.91, 1.63-2.23, P<.001; 1.72, 1.11-2.66, P=.016). The association of each marker with CS remained robust after adjusting for established risk factors for in-hospital development of CS, including all hemodynamic-, patient-, and procedure-related variables informing the ORBI risk score (1.65, 1.35-2.00, P<.001; 1.50, 1.26-1.77, P<.001; and 1.87, 1.13-3.11, P=.015). Notably, integration of ADM-glycine, PAM, and bio-ADM into the ORBI risk prediction model conferred increased discriminative performance for the prediction of in-hospital CS (AUC, 0.76 vs. 0.81, P<.001), ranking the ADM system second among all variables informing the score (Fig. 2). While both ADM-glycine and bio-ADM independently associated with mortality risk at 30-days (multivariable-adjusted hazard ratio per doubling, 95% CI, 1.93, 1.54-2.42, P<.001; and 1.81, 1.34-2.44, P<.001) and 1-year (1.41, 1.18-1.68, P<.001; and 1.52, 1.24-1.87, P<.001), PAM showed no association with these outcomes (P>.05). Conclusions Monitoring key regulators of the ADM system improves early risk assessment of ACS patients at high risk of CS, with admission ADM-glycine and bio-ADM representing independent risk factors for 30-day and 1-year mortality post-ACS.

Nanofibrous Membrane Promotes and Sustains Vascular Endothelial Barrier Function.

The vascular endothelium serves as a physical barrier between the circulating blood and surrounding tissue and acts as a critical regulator of various physiological processes. In vitro models involving vasculature rely on the maintenance of the endothelial barrier function. In this study, we fabricated 2D aligned nanofibrous membranes with distinct pore sizes via electrospinning and investigated the effect of membrane pore size on endothelial barrier function. Our results demonstrated that the use of the nanofibrous membranes promoted the formation of a tight vascular endothelium and sustained barrier function for over one month in comparison with conventional transwell setups. Moreover, the examination of the nucleocytoplasmic localization of yes-associated protein (YAP) in the endothelial cells indicated that nanofibrous membrane promoted YAP expression and its nuclear localization, critical to endothelial barrier function. Furthermore, the comparison of permeability between random and aligned nanofibrous membranes underscored the importance of pore size in preserving barrier function. Our findings offer a valuable strategy for creating more physiologically relevant in vitro vascular models and contribute to the understanding of endothelial barrier formation and maintenance mechanisms.

D-2-hydroxyglutarate regulates human brain vascular endothelial cell proliferation and barrier function.

Gain-of-function mutations in isocitrate dehydrogenase (IDH) genes result in excessive production of (D)-2-hydroxyglutarate (D-2HG) which intrinsically modifies tumor cell epigenetics and impacts surrounding noncancerous cells through nonepigenetic pathways. However, whether D-2HG has a paracrine effect on endothelial cells in the tumor microenvironment needs further clarification. We quantified microvessel density by immunohistochemistry using tissue sections from 60 high-grade astrocytic gliomas with or without IDH mutation. Microvessel density was found to be reduced in tumors carrying an IDH mutation. Ex vivo experiments showed that D-2HG inhibited endothelial cell migration, wound healing, and tube formation by suppressing cell proliferation but not viability, possibly through reduced activation of the mTOR/STAT3 pathway. Further, D-2HG reduced fluorescent dextran permeability and decreased paracellular T-cell transendothelial migration by augmenting expression of junctional proteins thereby collectively increasing endothelial barrier function. These results indicate that D-2HG may influence the tumor vascular microenvironment by reducing the intratumoral vasculature density and by inhibiting the transport of metabolites and extravasation of circulating cells into the astrocytoma microenvironment. These observations provide a rationale for combining IDH inhibition with antitumor immunological/angiogenic approaches and suggest a molecular basis for resistance to antiangiogenic drugs in patients whose tumors express a mutant IDH allele.

Dupilumab Inhibits Vascular Leakage of Blood Proteins Into Atopic Dermatitis Skin

Atopic dermatitis (AD) skin lesions are associated with oozing, bleeding, and erythema. This suggests AD is associated with vascular changes. Dupilumab is an antibody to the alpha-subunit of interleukin (IL) 4 receptor that demonstrates strong efficacy in the treatment of AD. IL-4 is known to reduce the permeability barrier function of vascular endothelium. To examine the effects of dupilumab on vascular barrier function in AD skin. Using proteomic analysis, we evaluated the plasma protein composition in skin tapes of lesional and non-lesional skin of adults and adolescents with moderate-to-severe AD over the course of a 16-week treatment with dupilumab and compared those to matched healthy subjects. At baseline, 115 plasma proteins were detected in AD skin and globally increased (1.5-fold or greater) compared to healthy skin. Functionally, these proteins included immunoglobulins, proteins involved in the coagulation process, enzymes, protease inhibitors, transport proteins, acute-phase proteins, complement proteins, and other pleiotropic proteins. Noteworthy, fibrinogens, fibronectin, and heme-binding proteins haptoglobin and hemopexin were among the top proteins originating from plasma and were increased in AD lesional versus healthy skin at baseline (p<0.0001). Dupilumab treatment resulted in significantly reduced levels of plasma proteins in AD skin (p<0.0001), with the majority dropping to levels seen in healthy skin or no longer detectable at week 16. Inhibition of IL-4/IL-13 action by dupilumab significantly reduces the efflux of plasma proteins into AD skin. Several of these proteins, such as fibrinogens and fibronectin, are known to enhance Staphylococcus aureuscolonization and are associated with AD skin severity.

Zinc Protects against Tumor Necrosis Factor-Induced Disruption of Porcine Endothelial Cell Monolayer Integrity

Some nutrients influence the metabolic response of cytokines such as tumor necrosis factor. Inadequate levels of the essential trace element zinc may play a role in tumor necrosis factor-induced disruption of the vascular endothelial barrier function. To test this hypothesis, endothelial cells cultured on polycarbonate filters or culture plates were exposed to six different treatments for 3 d: medium 199 enriched with 5% fetal bovine serum (control), control+two levels of supplemental zinc (7.7 and 12.3 mumol/L medium), tumor necrosis factor (5 x 10(5) U/L) and tumor necrosis factor+the two levels of Zn as noted previously. Endothelial barrier function, expressed as albumin transfer across cultured endothelial monolayers, was not affected by Zn enrichment alone. Tumor necrosis factor treatment significantly increased albumin transfer compared with control cultures. The lower concentration of Zn partially and the higher concentration totally prevented the tumor necrosis factor-induced increase in albumin transfer. The increase in cytosolic release of [3H]adenine (marker of cell injury) induced by tumor necrosis factor was prevented by added Zn. Tumor necrosis factor treatment significantly decreased angiotensin-converting enzyme activity, and tumor necrosis factor also decreased activities of two other membrane-bound enzymes, total ATPase and Ca(2+)-ATPase. These activities all were restored by Zn enrichment. Tumor necrosis factor treatment caused a decrease in cellular Zn concentration, which was prevented when the culture media were enriched with Zn. These data suggest that an important relationship exists between Zn status and tumor necrosis factor-induced endothelial cell dysfunction.

Dupilumab inhibits vascular leakage of blood proteins into atopic dermatitis skin

Atopic dermatitis (AD) skin lesions are associated with oozing, bleeding, and erythema that are primarily driven by polarized type 2 immune responses. These suggest vascular changes in AD. Dupilumab is an antibody to the alpha-subunit of interleukin (IL)-4 receptor that demonstrates robust efficacy in the treatment of moderate-to-severe AD. IL-4 is known to reduce the permeability barrier function of vascular endothelium. The effect of dupilumab on vascular barrier function in AD is unknown.

Research advances of the roles of sphingosine-1-phosphate in acute lung injury

Sphingosine-1-phosphate (S1P) is the main metabolite produced in the process of phospholipid metabolism, which can promote proliferation, migration, and apoptosis of cells, and maintain the barrier function of vascular endothelium. The latest researches showed that S1P can alleviate acute lung injury (ALI) and the inflammation caused by ALI, while the dosage of S1P is still needed to be considered. Mesenchymal stem cells (MSCs) have been a emerging therapy with potential therapeutic effects on ALI because of their characteristics of self-replication and multi-directional differentiation, and their advantages in hematopoiesis, immune regulation, and tissue repair. S1P can promote differentiation of MSCs and participate in immune regulation, while MSCs can regulate the homeostasis of S1P in the body. The synergistic effect of S1P and MSC provides a new treatment method for ALI. This article reviews the production and biological function of S1P, receptor and signal pathway of S1P, the therapeutic effects of S1P on ALI, and the research advances of S1P combined with MSCs in the treatment of ALI, aiming to provide theoretical references for the development of S1P targeted drugs in the treatment of ALI and the search for new combined treatment schemes for ALI.

S1PR2/RhoA/ROCK1 pathway promotes inflammatory bowel disease by inducing intestinal vascular endothelial barrier damage and M1 macrophage polarization

Vascular and immune dysfunctions are thought to be related to the pathogenesis of inflammatory bowel disease (IBD), but behind this, the exact mechanism of mucosal vascular endothelial barrier dysfunction and macrophage phenotypic transition is not fully understood. Here, we explored the mechanistic role of sphingosine 1-phosphate receptor 2 (S1PR2) and its downstream G protein RhoA/Rho kinase 1 (ROCK1) signaling pathway in the intestinal endothelial barrier damage and M1 macrophage polarization in IBD. We found that the expression of S1PR2 in intestinal mucosal vascular endothelial cells and macrophages of IBD patients and DSS-induced colitis mice as well as vascular endothelial cells and macrophages treated with LPS in vitro was significantly increased. Knocking down or pharmacologically inhibiting S1PR2 significantly downregulated the expression of RhoA and ROCK1 in vascular endothelial cells and macrophages. Furthermore, inhibition of S1PR2 and ROCK1 reversed the impaired vascular barrier function and M1 macrophage polarization in vivo and in vitro, while reducing ER stress in vascular endothelial cells and glycolysis in macrophages. In addition, inhibition of ER stress or glycolysis reversed LPS-induced impairment of vascular endothelial cell barrier function and M1 macrophage polarization. Collectively, our results indicate that the S1PR2/RhoA/ROCK1 signaling pathway may participate in the pathogenesis of IBD by regulating vascular endothelial barrier function and M1 macrophage polarization.

Reducing the Damage of Ox-LDL/LOX-1 Pathway to Vascular Endothelial Barrier Can Inhibit Atherosclerosis.

Aim The destruction of the vascular endothelial barrier mediated by Ox-LDL is the initial link to atherosclerosis. Here, we aimed to determine whether the immunological intervention with Ox-ApoB polypeptide fragment (Ox-ApoB-PF) can block the deposition of Ox-LDL in vascular endothelial cells through LOX-1 receptors, thereby protecting the barrier function and survival status of vascular endothelial cells and inhibiting the progression of atherosclerosis. Methods and Results In order to determine the harm of Ox-LDL to vascular endothelial cells and the protective effect of immune intervention with Ox-ApoB-PF, we conducted a series of corresponding experiments in vitro and in vivo. The in vitro results showed that Ox-LDL can activate endothelial cell apoptosis pathway; reduce the expression of endothelial junction proteins; affect the migration, deformation, and forming ability; and ultimately destroy the vascular endothelial barrier function. The increased permeability of endothelial cells led to a sharp increase in the phagocytosis of Ox-LDL by macrophages under the endothelial layer. Meanwhile, Ox-LDL stimulation induced a significant upregulation of LOX-1 in endothelial cells and increased the expression of endothelial cell chemokines and adhesion factors. Ox-ApoB-PF antibodies can significantly reduce the abovementioned harmful effects. The in vivo results showed that active immune intervention through Ox-ApoB-PF can protect the endothelial barrier function; reduce macrophage deposition and the inflammatory response in plaques; alleviate lipid deposition in the plaques, as well as apoptosis and necrosis; and increase the ability of liver macrophages to clear Ox-LDL. Eventually, the progression of plaque and the formation of necrotic cores in plaques can be inhibited. Conclusions An Ox-ApoB-PF antibody may protect the endothelial cell physiological function and survival status by blocking the combination of Ox-LDL/LOX-1 in vascular endothelial cells. Immune intervention with Ox-ApoB-PF inhibits the occurrence and development of atherosclerotic lesions by protecting the vascular endothelial barrier function.

Adrenomedullin Therapy in Moderate to Severe COVID-19.

The 2019 coronavirus (COVID-19) pandemic is still in progress, and a significant number of patients have presented with severe illness. Recently introduced vaccines, antiviral medicines, and antibody formulations can suppress COVID-19 symptoms and decrease the number of patients exhibiting severe disease. However, complete avoidance of severe COVID-19 has not been achieved, and more importantly, there are insufficient methods to treat it. Adrenomedullin (AM) is an endogenous peptide that maintains vascular tone and endothelial barrier function. The AM plasma level is markedly increased during severe inflammatory disorders, such as sepsis, pneumonia, and COVID-19, and is associated with the severity of inflammation and its prognosis. In this study, exogenous AM administration reduced inflammation and related organ damage in rodent models. The results of this study strongly suggest that AM could be an alternative therapy in severe inflammation disorders, including COVID-19. We have previously developed an AM formulation to treat inflammatory bowel disease and are currently conducting an investigator-initiated phase 2a trial for moderate to severe COVID-19 using the same formulation. This review presents the basal AM information and the most recent translational AM/COVID-19 study.

Translational studies of adrenomedullin and related peptides regarding cardiovascular diseases.

Adrenomedullin (AM) is a vasodilative peptide with various physiological functions, including the maintenance of vascular tone and endothelial barrier function. AM levels are markedly increased during severe inflammation, such as that associated with sepsis; thus, AM is expected to be a useful clinical marker and therapeutic agent for inflammation. However, as the increase in AM levels in cardiovascular diseases (CVDs) is relatively low compared to that in infectious diseases, the value of AM as a marker of CVDs seems to be less important. Limitations pertaining to the administrative route and short half-life of AM in the bloodstream (<30 min) restrict the therapeutic applications of AM for CVDs. In early human studies, various applications of AM for CVDs were attempted, including for heart failure, myocardial infarction, pulmonary hypertension, and peripheral artery disease; however, none achieved success. We have developed AM as a therapeutic agent for inflammatory bowel disease in which the vasodilatory effect of AM is minimized. A clinical trial evaluating this AM formulation for acute cerebral infarction is ongoing. We have also developed AM derivatives that exhibit a longer half-life and less vasodilative activity. These AM derivatives can be administered by subcutaneous injection at long-term intervals. Accordingly, these derivatives will reduce the inconvenience in use compared to that for native AM and expand the possible applications of AM for treating CVDs. In this review, we present the latest translational status of AM and its derivatives.

TET1s deficiency exacerbates oscillatory shear flow-induced atherosclerosis.

Background: TET1 has been implicated in regulating inflammation and cardiovascular disease, but a newly discovered short isoform of TET1 (termed TET1s) exhibits higher expression in adult tissues than full-length TET1. However, the precise role of TET1 in cardiovascular disease remains undefined.Methods and Results: Based on TET1-/- knockout mice (with deletion of both TET1 and TET1s ) and TET1cs/cs mice (with deletion of only TET1), we found that TET1s deletion in TET1-/- mice resulted in more serious atherosclerotic lesions in the whole aorta than TET1cs/cs in the ApoE-/- background mice fed a high-fat diet. Atherosclerotic lesions with Oil red staining were dramatically localized in the aortic arch, abdominal aorta and ligated LCA, where they were exposed to OSS. Furthermore, the OSS-induced depression of TET1s in vitro and in vivo increased inflammatory cell and red blood cell infiltration into the subendothelial layer by impairing the vascular intimal barrier. TET1s upregulation enhanced vascular endothelial barrier function by increasing gap protein connexin 40 (CX40) expression as measured by RNA-seq and was confirmed by CX40 knockdown. TET1s interaction with Sin3a increased the global and CX40 promoter histone H3K27 acetylation levels, but not DNA methylation, to induce CX40 expression.Conclusions: These data demonstrate the unexpected discovery that laminar shear stress induces TET1s expression to protect the vascular endothelial barrier by increasing CX40 expression in ECs and that TET1s overexpression may be the core step for OSS-induced atherosclerosis therapy.

Role of caveolin-1 in chronic postsurgical pain in rats.

Chronic postsurgical pain (CPSP) has a high incidence, but the underlying mechanisms remain elusive. Previous studies have indicated that caveolin-1 (Cav-1) plays a notable role in pain modulation. To study the role of Cav-1 in CPSP in the present study, a rat model of skin/muscle incision and retraction (SMIR) was established. Under anesthesia, skin and superficial muscle of the medial thigh were incised and a small pair of retractors inserted. It was revealed that SMIR increased the expression of Cav-1 in the dorsal root ganglion (DRG) and the injured tissue around the incision. Furthermore, the infiltration of endothelial cells and macrophages in the injured tissue around the incision increased constantly, and the vascular permeability increased due to the destruction of the vascular endothelial barrier function around the injured tissue. Cav-1 was mainly expressed by CD68-positive macrophages and CD34-positive endothelial cells in the injured tissues around the incision, while it was also primarily localized in the medium and large neurofilament 200-positive neurons and a small number of calcitonin gene-related peptide- and isolectin B4-positive small and medium-sized neurons in the DRG. The results demonstrated that the sustained high expression levels of Cav-1 in the injured tissue around the incision could lead to the dysfunction of the vascular endothelial barrier and, thus, could induce the inflammatory response through the lipoprotein transport of endothelial cells, thereby resulting in peripheral sensitization. In addition, the sustained high expression levels of Cav-1 in the DRG could sensitize large-sized neurons and change the transmission mode of noxious stimuli. The findings of the present study indicated that a Cav-1-mediated process could participate in neuronal transmission pathways associated with pain modulation.

Bivalirudin Attenuates Thrombin-Induced Endothelial Hyperpermeability via S1P/S1PR2 Category: Original Articles.

Aims: To explore the role of the Sphingosine 1-Phosphate (S1P)/Receptor2 (S1PR2) pathway in thrombin-induced hyperpermeability (TIP) and to test whether bivalirudin can reverse TIP via the S1P-S1PRs pathway.Methods and Results: Using western blot, we demonstrated that Human umbilical vein endothelial cells (HUVECs) that were cultured with 2 U/ml thrombin showed significantly increased S1PR2 expression while S1PR1and three kept unchanged. Such increment was attenuated by JTE-013 pretreatment and by presence of bivalirudin. Exposure of 2 U/ml of thrombin brought a higher level of S1P both intracellularly and extracellularly within the HUVECs by using ELISA detecting. Thrombin induced S1P and S1PR2 increment was restored by usage of PF543 and bivalirudin. Bivalirudin alone did not influenced the level of S1P and S1PR1,2, and S1PR3 compare to control group. As a surrogate of cytoskeleton morphology, phalloidin staining and immunofluorescence imaging were used. Blurry cell edges and intercellular vacuoles or spaces were observed along thrombin-exposed HUVECs. Presence of JTE-013 and bivalirudin attenuated such thrombin-induced permeability morphological change and presence of heparin failed to show the protective effect. Transwell chamber assay and probe assay were used to measure and compare endothelial permeability in vitro. An increased TIP was observed in HUVECs cultured with thrombin, and coculture with bivalirudin, but not heparin, alleviated this increase. JTE-013 treatment yielded to similar TIP alleviating effect. In vivo, an Evans blue assay was used to test subcutaneous and organ microvascular permeability after the treatment of saline only, thrombin + saline, thrombin + bivalirudin, thrombin + heparin or thrombin + JTE-013. Increased subcutaneous and organ tissue permeability after thrombin treatment was observed in thrombin + saline and thrombin + heparin groups while treatment of bivalirudin and JTE-013 absent this effect.Conclusion: S1P/S1PR2 mediates TIP by impairing vascular endothelial barrier function. Unlike heparin, bivalirudin effectively blocked TIP by inhibiting the thrombin-induced S1P increment and S1PR2 expression, suggesting the novel endothelial protective effect of bivalirudin under pathological procoagulant circumstance.