Regulatory mechanisms,prophylaxis and treatment of vascular leakage following severe trauma and shock

Vascular leakage, or increased vascular permeability, is a common but important pathological process for various critical diseases, including severe trauma, shock, sepsis, and multiple organ dysfunction syndrome(MODS), and has become one of the most important causes of death for intensive care units(ICU) patients. Currently, although there has been some progress in knowledge of the pathogenesis of these vascular disorders, the detailed mechanisms remain unclear, and effective prophylaxis and treatment are still lacking. In this study, we aimed to provide a review of the literature regarding the regulatory mechanisms and prophylaxis as well as the treatment of vascular leakage in critical diseases such as severe trauma and shock, which could be beneficial for the overall clinical treatment of vascular leakage disorders.

Neutrophil-derived heparin binding protein triggers vascular leakage and synergizes with myeloperoxidase at the early stage of severe burns(With video)

Background:Burn shock caused by vascular leakage is one of the main causes of high mortality in severe burn injury.However,the pathophysiological mechanism of vascular leakage is still unclear.The purpose of this study was to explore the molecular mechanism of vascular leakage in the early stage of severe burn and provide a new target for the treatment of severe burns.Methods:Neutrophils were isolated from human peripheral blood by magnetic beads sorting.ELISA was used to detect neutrophil-derived granule proteins and glycocalyx injury products in plasma.The vascular leakage and neutrophil movement were assessed by in vivo laser confocal imaging in mice,and high-quality video were provided.Adhesion-related molecules were investigated by qRT-PCR.The damage to glycocalyx of mice vascular endothelial cellswas observed by transmission electron microscope and scanning electron microscope.Proteomic analysis,flow cytometry and immunofluorescence were used to further study the relationship between human peripheral blood neutrophil-derived hypochlorite(HOCl)and CD44 of human vascular endothelial cells.Results:In this study,we found that rapidly increasing activated neutrophils secrete heparin binding protein(HBP)andmyeloperoxidase(MPO)after severe burn injury.Increased HBP triggers vascular leakage with synergy of MPO,results in systemic edema and burn shock.Furthermore,we found that the MPO catalytic product HOCl but not MPO triggers CD44 extracellular domain shedding from vascular endothelial cells to damage the glycocalyx.Damage to the glycocalyx results in firm adhesion of neutrophils and increases vascular leakage.However,MPO inhibitors partially protect the glycocalyx of vascular endothelial cells.The combination of HBP and MPO inhibitors markedly reduces vascular leakage and systemic edema in the early stage of severe burns.Conclusions:Taken together,these data reveal that neutrophil-derived HBP and MPO play an important synergies role in triggering vascular leakage at the early stage of severe burns.Targeted intervention in these two biomolecules may introduce new strategies for helping to reduce large amount of fluid loss and subsequent burn shock.

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

AIM: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.METHODS: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.RESULTS: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.CONCLUSION: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.

Aqueous angiopoietin-like levels correlate with optical coherence tomography angiography metrics in diabetic macular edema

AIM:To quantitatively detect aqueous levels of angiopoietin-like(ANGPTL)3,ANGPTL4,and ANGPTL6 and investigate their correlation with optical coherence tomography angiography(OCTA)findings in patients with diabetic macular edema(DME).METHODS:This cross-sectional study included 23 patients(27 eyes)with type 2 diabetes and 16 control subjects(20 eyes).All patients underwent OCTA imaging and ultra-wide field fundus photography.Diabetic patients were categorized into two groups according to the presence or absence of diabetic retinopathy(DME group,14 patients,16 eyes);and non-diabetic retinopathy(NDR)group,9 patients,11 eyes,respectively.Aqueous levels of ANGPTL3,ANGPTL4,and ANGPTL6 were assessed using suspension array technology,and foveal-centered 3×3 mm2 OCTA scans were automatically graded to determine the central,inner,and full vessel density(CVD,IVD,FVD);central,inner,and full perfusion density(CPD,IPD,FPD),foveal avascular zone(FAZ)area,FAZ perimeter,and FAZ circularity index(FAZ-CI)on superficial capillary plexuses.Additionally,central subfield thickness(CST),cube volume(CV),and cube average thickness(CAT)were measured in a model of macular cube 512×128.RESULTS:Aqueous ANGPTL3 levels were not significantly different among the three groups(P>0.05).ANGPTL4 levels were significantly higher in the DME group than the control and NDR groups(P<0.0001 and P<0.001),while ANGPTL6 levels were significantly higher in the DME group than the control group(P<0.05).In the whole cohort,the aqueous ANGPTL3 levels correlated negatively with the IVD,FVD,IPD,and FPD,and positively with the CV and CAT.The aqueous ANGPTL4 levels correlated negatively with the CVD,IVD,FVD,CPD,IPD,and FPD,and positively with the FAZ perimeter,CST,CV,and CAT.The aqueous ANGPTL6 levels correlated negatively with the IVD,FVD,IPD,FPD,FAZCI and positively with CST,CV,CAT.CONCLUSION:ANGPTL4 and ANGPTL6 may be associated with vascular leakage in DME and may represent good targets for DME therapy.In addition,OCTA metrics may be useful for evaluating macular ischemia in DME.

AB018.Ocular hypertension promotes early mitochondrial fragmentation in retinal endothelial cells in a mouse model of glaucoma

Background:Retinal endothelial cells are very active and contribute to the integrity of the neurovascular unit.Vascular dysfunction has been proposed to contribute to the pathogenesis of glaucoma.Here,we evaluated the hypothesis that ocular hypertension triggers mitochondrial alterations in endothelial cells impairing the integrity of the blood retinal barrier(BRB).Methods:Ocular hypertension was induced by injection of magnetic microbeads into the anterior chamber of EndoMito-EGFP mice,a strain expressing green fluorescent protein selectively in the mitochondria of endothelial cells.Capillary density,mitochondrial volume,and the number of mitochondrial components were quantified in 3D-reconstructed images from whole-mounted retinas using Imaris software.Dynamin-related protein(DRP-1),mitofusin-2(MFN-2)and optic atrophy-1(OPA-1)expression were assessed by western blot analysis of enriched endothelial cells.Mitochondrial structure was evaluated by transmission electron microscopy(TEM)and oxygen consumption rate was monitored by Seahorse analysis.The integrity of the BRB was evaluated by quantifying Evans blue leakage.Results:Our data demonstrate that two and three weeks after ocular hypertension induction,the total mitochondria volume in endothelial cells decreased from 0.140±0.002µm3 from non-injured retinas to 0.108±0.005 and 0.093±0.007µm3,respectively in glaucomatous eyes(mean±S.E.M,ANOVA,P<0.001;N=6/group).Frequency distribution showed a substantial increase of smaller mitochondria complexes(<0.5µm3)in endothelial cells from glaucomatous retinas.Significant upregulation of DRP-1 was found in vessels isolated from glaucomatous retinas compared to the intact retinas,while MFN-2 and OPA-1 expression was not affected.Structural alteration in endothelial cell mitochondria was confirmed by TEM,which were accompanied by a 1.93-fold reduction in the oxygen consumption rate as well as 2.6-fold increase in vasculature leakage in glaucomatous retinas(n=3-6/group).In addition,this model did not trigger changes in the density of the vascular network,suggesting that mitochondrial fragmentation was not due to endothelial cell loss.Conclusions:This study shows that ocular hypertension leads to early alterations in the dynamic of endothelial cell mitochondria,contributing to vascular dysfunction in glaucoma.