Modulation Of Vascular Permeability Research Articles

Keypoints in Cells and Atherogenesis

Endothelial dysfunction is the initial event in the atherogenic process, resulting from several events, such as expression of leukocyte binding sites, production of growth factors, chemotactic and vasoreactive molecules, ability to oxidize low-density lipoprotein (LDL) and respond to oxidized lipoproteins, ability to express procoagulant activity, and modulation of vascular permeability. Thus, the endothelium, when subjected to different conditions and factors, plays an active role in the development of atherosclerotic plaque. The expression of several adhesion molecules, such as intracellular adhesion molecule-1 (ICAM-1), E-selectin, vascular cell adhesion molecule-1 (VCAM-1), P-selectin in atherosclerotic plaques, mediating the interaction between endothelial cells and leukocytes, has been described. The modification of LDLs, in conjunction with other chemotactic factors produced by injured endothelial cells, recruit circulating monocytes into the subendothelial space, where they become macrophages. The proliferation of smooth muscle cells is an important event in the progression of arterial injury, occurring in 3 stages: smooth muscle cell replication still within the media layer; migration from the middle layer to the intima and proliferation within the intima. Apoptotic cells were evidenced in the atherosclerotic lesion, suggesting that apoptosis is part of the normal vascular healing process. The final stage of atherosclerotic lesion development is conversion of the fibrotic lesion to an advanced lesion, a lesion in which a thrombus forms as a result of plaque ulceration or intraplaque hemorrhage.

A Theoretical Model of the Mechanism by which Dietary Lipid Variance and Increased Oxysterols Allow Increased Formation of Soluble Endoglin in Preeclampsia

Endoglin (TGF‐β receptor III), an accessory receptor necessary for transforming growth factor‐β (TGF‐β) signaling, is essential during angiogenesis. Cleavage of endoglin by matrix metalloproteinase‐14 (MMP‐14) creates a soluble receptor (sEng) which is elevated in the sera of people with preeclampsia. Similarly to sflts which bind VEGF, sEng binds TGF‐β and impairs functions ranging from endothelial nitric oxide synthesis, vasodilation, and modulation of vascular permeability, to regulation of immune homeostasis, trophoblastic invasion and differentiation.Cleavage of endoglin to form sEng is upregulated in the presence of oxysterols. Initially, oxysterols were believed to upregulate MMP‐14 and down regulate its inhibiter TIMP3. However, in placental explants, expression MMP14 and TIMP3 mRNA were not altered by oxysterols and pravastatin did not decrease oxysterol‐induced upregulation of sEng. Membrane raft domains negatively regulate TGF‐β signaling, and aspirin, which disperses membrane rafts, induces TGF‐β signaling.This perspective considers the known changes in dietary lipids over the last 100 years, the possible effects of these changes on membrane raft formation, oxidative stress, and oxysterol formation, as well as the known effects of oxysterols on membrane thickness and fluidity and proposes an alternate mechanism by which oxysterols might increase sEng formation.

Fibrinogen/AKT/Microfilament Axis Promotes Colitis by Enhancing Vascular Permeability

Background & AimsIncreased vascular permeability (VP) has been indicated to play an important role in the pathogenesis of inflammatory bowel disease (IBD). However, the pathological causes of increased intestinal VP in IBD remain largely unknown.MethodFibrinogen level was measured in dextran sulphate sodium (DSS)-induced colitis and patients with ulcerative colitis. Gly-Pro-Arg-Pro acetate (GPRP), an Fg inhibitor, was used to detect the effect of Fg inhibition on the pathogenesis of DSS-induced colitis, as indicated by tissue damage, cytokine release and inflammatory cell infiltration. Miles assay was used to detect vascular permeability.ResultsThrough tandem mass tag–based quantitative proteomics, fibrinogen (Fg) was found to be upregulated in the colon of DSS-treated mice, which was consistent with increased Fg level in colon sample of patients with ulcerative colitis. Gly-Pro-Arg-Pro acetate (GPRP), an Fg inhibitor, significantly alleviated DSS-induced colitis as indicated by improvement of body weight loss and mortality. GPRP decreased colonic inflammation and VP in DSS-treated mice. In vivo, Fg enhanced VP as indicated by Miles assay, which was significantly inhibited by GRPR, AKT (serine/threonine kinase 1) inhibitors and low doses of Jasplakinolide which induced actin polymerization, while was dramatically enhanced by Cytochalasin D (an actin polymerization inhibitor). Moreover, activation of AKT was found in vessels of DSS-treated mice. In vitro, Fg induced activation of AKT and depolymerization of microfilament and promoted cell-to-cell disaggregation. Furthermore, inhibition of AKT decreased Fg-induced microfilament depolymerization.ConclusionsOur findings highlight the importance of Fg in regulating colitis by modulation of VP via activating AKT and subsequent depolymerization of microfilament and suggest Fg as an attractive target for anti-colitis treatment.

2015 AHA Late-Breaking Basic Science Abstracts.

### 23060 ### Validation Of Circulating MicroRnas As Biomarkers In Heart Failure In Two Large Independent Cohorts Antoni Bayes-Genis1, David Lanfear2, Maurice de Ronde3, Josep Lupon1, Joost Leenders4, Elisabet Zamora1, L. Keoki Williams2, De Antonio Marta5, Zhen Liu4, Koos Zwinderman3, Sara-Joan Pinto-Sietsma3, Yigal Pinto3; 1Universitat Autonoma de Barcelona, Barcelona, Spain; 2Henry Ford Hospital, Detroit, MI; 3Academic Med Cntr, Univ of Amsterdam, Amsterdam, Netherlands; 4Mirnext BV, Amsterdam, Netherlands; 5Germans Trias i Pujol Hosp, Badalona, Spain Background: Small studies suggested circulating microRNAs (circmiRs) as biomarkers for Heart Failure (HF). However, standardized approaches and quality assessment are not established, and results have been inconsistent, with little replication between studies. We aimed to implement quality standards to enable comparison between cohorts and assess which circmiRs may add prognostic information in HF. Methods: We measured 15 circmiRs in two independent cohorts totaling >2000 subjects. Cohort I (Barcelona) comprised of n=843 chronic HFrEF patients. Cohort II from Detroit comprised n= 1384 chronic HF patients (892 HFrEF, 492 HFpEF). Each sample was measured in duplicate, and normalized to an abundant and stable circmiR (miR-486-5p). Algorithms were installed to define each circmiR measurement as “valid”, “unmeasurable” or “invalid”. This allowed inclusion of valid low-level circmiR measurements while reducing noise from false amplification signals. Results: In general, between 20–40% of measurements were “invalid”, while miR-499a\_5p and -208a were “unmeasurable” in the majority of patients in both cohorts. Higher levels of circmiRs-133b, -1254, -622, -208a and -499a\_5p were significantly associated with risk of death in both cohorts, with hazard ratios ranging from 1.103 to 1.365 per log increase (p-values 0.001 to 0.05). However, adding these circmiRs to established predictors (age, renal function and NTproBNP) did not further augment the c-stat beyond 0.71 (cohort I) or 0.78 (cohort II). …

S1P control of endothelial integrity.

Sphingosine 1-phosphate (S1P), a lipid mediator produced by sphingolipid metabolism, promotes endothelial cell spreading, vascular maturation/stabilization, and barrier function. S1P is present at high concentrations in the circulatory system, whereas in tissues its levels are low. This so-called vascular S1P gradient is essential for S1P to regulate much physiological and pathophysiological progress such as the modulation of vascular permeability. Cellular sources of S1P in blood has only recently begun to be identified. In this review, we summarize the current understanding of S1P in regulating vascular integrity. In particular, we discuss the recent discovery of the endothelium-protective functions of HDL-bound S1P which is chaperoned by apolipoprotein M.

Abl Family Kinases Regulate Endothelial Barrier Function In Vitro and in Mice

The maintenance of endothelial barrier function is essential for normal physiology, and increased vascular permeability is a feature of a wide variety of pathological conditions, leading to complications including edema and tissue damage. Use of the pharmacological inhibitor imatinib, which targets the Abl family of non-receptor tyrosine kinases (Abl and Arg), as well as other tyrosine kinases including the platelet-derived growth factor receptor (PDGFR), Kit, colony stimulating factor 1 receptor (CSF1R), and discoidin domain receptors, has shown protective effects in animal models of inflammation, sepsis, and other pathologies characterized by enhanced vascular permeability. However, the imatinib targets involved in modulation of vascular permeability have not been well-characterized, as imatinib inhibits multiple tyrosine kinases not only in endothelial cells and pericytes but also immune cells important for disorders associated with pathological inflammation and abnormal vascular permeability. In this work we employ endothelial Abl knockout mice to show for the first time a direct role for Abl in the regulation of vascular permeability in vivo. Using both Abl/Arg-specific pharmacological inhibition and endothelial Abl knockout mice, we demonstrate a requirement for Abl kinase activity in the induction of endothelial permeability by vascular endothelial growth factor both in vitro and in vivo. Notably, Abl kinase inhibition also impaired endothelial permeability in response to the inflammatory mediators thrombin and histamine. Mechanistically, we show that loss of Abl kinase activity was accompanied by activation of the barrier-stabilizing GTPases Rac1 and Rap1, as well as inhibition of agonist-induced Ca2+ mobilization and generation of acto-myosin contractility. In all, these findings suggest that pharmacological targeting of the Abl kinases may be capable of inhibiting endothelial permeability induced by a broad range of agonists and that use of Abl kinase inhibitors may have potential for the treatment of disorders involving pathological vascular leakage.

The use of albumin in the complications of cirrhosis: evidence and future perspectives

The therapeutic use of albumin in cirrhosis dates back to the 50s, when hypoalbuminemia was thought to play a crucial role in the pathophysiology of ascites. Today, while its efficacy in the treatment of ascites is still under investigation, it has been proved that albumin is able to improve patient outcome and survival in some specific complications of cirrhosis, such as the prevention of post-paracentesis circulatory dysfunction and the treatment of spontaneous bacterial peritonitis and hepatorenal syndrome. Beside its oncotic power, albumin carries other biological properties, the so called non-oncotic properties, including transportation and detoxification of several molecules, free radical scavenging, modulation of vascular permeability, activity on the immune system and on the haemostatic balance. Some experimental evidences indicate that not only albumin concentration but also its function is reduced in patients with cirrhosis. However, the clinical implications of such functional abnormalities is still unclear. We here present the available evidence on the use of albumin in cirrhosis and future perspectives.

α-1-Antitrypsin and IFN-γ Reduce the Severity of IC-Mediated Vasculitis by Regulation of Leukocyte Recruitment In Vivo

IC-mediated vasculitis (ICV) can be life threatening. The cellular and immune mechanisms controlling ICV are poorly understood. Therefore, we investigated the role of α-1-antitrypsin (α1AT) and IFN-γ in reducing the severity of ICV in a mouse model in vivo. To induce ICV, mice were challenged with the reverse passive Arthus reaction (RPA), the prototypic in vivo model for leukocytoclastic vasculitis (LcV), and the modulation of vascular permeability, edema formation, and leukocyte recruitment was studied. To further analyze the dynamics of RPA, we applied intravital microscopy in the dorsal skinfold chamber. α1AT continuously led to reduced leukocyte recruitment. α1AT interfered with neutrophil recruitment through a KC-dependent mechanism and reduced KC-elicited neutrophil activation. In contrast to α1AT, IFN-γ-reduced leukocyte recruitment during RPA was clearly independent of KC. We also revealed that the recruitment of neutrophils during RPA was a prerequisite for full KC expression. Thus, therapeutic administration of α1AT and IFN-γ might be beneficial for limiting the duration and severity of ICV.

The local modulation of vascular permeability by endothelial cell derived products.

Endothelin has been shown to suppress increased vascular permeability in the rat at doses of 0.01 pmol. The agonists used were nitric oxide and nitroprusside, which have the same activity as endothelial-derived relaxing factor. Histamine, 5-hydroxytryptamine, platelet activating factor and carrageenan were the other agonists used. It is proposed that endothelin and EDRF act as local hormones produced by endothelial cells to control local vascular permeability.

Coenzyme Q10: A novel gastroprotective effect via modulation of vascular permeability, prostaglandin E 2, nitric oxide and redox status in indomethacin-induced gastric ulcer model

Coenzyme Q10 is an essential cofactor in the mitochondrial electron transport pathway, and is endowed for its potent antioxidant capacity; characters that endorse its implication in several clinical practices and as a food supplement. Nevertheless, its potential gastro-protective effect, in acute models, has never been assessed, which is the objective of this study. Since indomethacin mediated gastropathy is multifaceted, including mitochondrial dysfunction and generation of reactive oxygen species, thus, the indomethacin-induced gastric injury serves as a convenient animal model for this work. Rats treated with indomethacin revealed mucosal hemorrhagic lesions, increased microvascular permeability and inhibited prostaglandin E 2 and mucus content. Redox imbalance was reflected by decreased mucosal glutathione (GSH), nitric oxide and glutathione peroxidase contents/activity, along with elevated lipid peroxides. Pretreatment with CoQ10 caused discernible decrease in indomethacin-induced gastric lesions, vascular permeability and lipid peroxide content. In addition, prostaglandin E 2 and GSH levels were restored, while those of nitric oxide and glutathione peroxidase were elevated significantly above normal; however, mucus formation was not altered significantly. The positive effects were comparable to those of sucralfate, the standard drug used herein, except for the mucus and prostaglandin E 2 levels that were increased above normal by sucralfate. CoQ10-mediated gastroprotective effect involves preservation of microvascular permeability, elevation of prostaglandin E 2, improvement of redox status, as well as boosting of nitric oxide. Nevertheless, maintaining gastric mucus content is ruled out.

Human mast cells synthesize and release angiogenin, a member of the ribonuclease A (RNase A) superfamily

ANG is a plasma protein with angiogenic and ribonucleolytic activity implicated in tumor growth, heart failure, wound healing, asthma, and the composition of the adult gut microflora. Human mast cells (HuMC) are similarly associated with modulation of vascular permeability, angiogenic processes, wound healing, and asthma. We hypothesized that HuMC express and secrete ANG in response to divergent stimuli. ANG expression was evaluated in the LAD2 HMC, the HMC-1, and CD34+-derived HuMC, following exposure to live Escherichia coli, TLR ligands, or neuropeptides and following FcepsilonRI aggregation. Expression and production of ANG were determined by microarray analysis, qRT-PCR, confocal microscopy, and ELISA. Microarray analysis showed that ANG is up-regulated by LAD2 cells exposed to live E. coli. qRT-PCR analysis revealed that LAD2, HMC-1, and HuMC constitutively expressed ANG mRNA and that it was up-regulated by exposure to E. coli. Activation of HuMC by FcepsilonRI aggregation resulted in release of small amounts of ANG (<100 pg/mL), whereas compound 48/80, NGF, LPS, PGN, and flagellin activated HuMC to secrete >160 pg/mL ANG. These observations demonstrate that HuMC store and secrete ANG to a variety of stimuli and suggest that MC-derived ANG is available in the subsequent inflammatory response.

Oligonucleotide NX1838 inhibits VEGF165-mediated cellular responses in vitro

VEGF (vascular endothelial growth factor) overproduction has been identified as a major factor underlying pathological angiogenesis in vivo, including such conditions as psoriasis, macular degeneration, and tumor proliferation. Endothelial cell tyrosine kinase receptors, KDR and Flt-1, have been implicated in VEGF responses including cellular migration, proliferation, and modulation of vascular permeability. Therefore, agents that limit VEGF-cellular interaction are likely therapeutic candidates for VEGF-mediated disease states (particularly agents blocking activity of VEGF165, the most frequently occurring VEGF isoform). To that end, a nuclease-resistant, VEGF165-specific aptamer NX1838 (2'-fluoropyrimidine, RNA-based oligonucleotide/40-kDa-PEG) was developed. We have assessed NX1838 inhibition of a variety of cellular events associated with VEGF, including cellular binding, signal transduction, calcium mobilization, and induction of cellular proliferation. Our data indicate that NX1838 inhibits binding of VEGF to HUVECs (human umbilical vein endothelial cells) and dose-dependently prevents VEGF-mediated phosphorylation of KDR and PLCgamma, calcium flux, and ultimately VEGF-induced cell proliferation. NX1838-inhibition of VEGF-mediated cellular events was comparable to that observed with anti-VEGF monoclonal antibody, but was ineffective as an inhibitor of VEGF121-induced HUVEC proliferation. These findings, coupled with nuclease stability of the molecule, suggest that NX1838 may provide therapeutic utility in vivo.

Topical treatment of venous ulcer with fibrin stabilizing factor: experimental investigation of effects on vascular permeability.

The clinical observation of distinct reduction of wound secretion tendency during treatment of venous leg ulcer with topically applied factor XIII let us speculate that this enzyme may be involved in modulation of vascular permeability. For experimental study porcine aortic endothelial cells were cultured on filter membrane to confluent monolayer. Endothelial covered filters then were used in a two-compartment modell creating an artificial luminal and abluminal compartment. To investigate the influence of factor XIII on endothelial barrier function, we measured the flux of trypan blue-labeled albumin through endothelial monolayers by spectrophotometer. Monolayers that were exposed to factor XIII showed a distinct (n = 10, p < 0.05) decrease of albumin flux in contrast to control. This effect was not dependent on serum substrates. Partially, the permeability reducing effect was due to a certain amount of albumin that is a stabilizing component of Fibrogammin HS. Although the mechanism is unclear at the moment, we conclude that reduction of endothelial permeability can be achieved by factor XIII which may play an important role in wound healing of venous leg ulcer.

Modulation of Secretion of Interleukin-6 in Brain-Derived Microvascular Endothelial Cells

Vascular permeability is tightly controlled, in particular in the cerebral microvasculature, thus factors able to modulate permeability are of physiological importance. Interleukin-6 (IL-6) can be released by many cell types including mononuclear phagocytes, fibroblasts and endothelial cells of various origins, and is involved in a variety of cellular responses, including modulation of vascular permeability. IL-6 is synthesized as a precursor propeptide which is proteolytically processed to the active hormone, then degraded, by as yet unknown enzymatic pathways. Unstimulated brain-derived microvessels, primary cells and cell lines, all secreted bioactive IL-6. Cell lines secreted IL-6 exclusively as a 25 kD peptide. In order to understand mechanisms regulating the secretion of IL-6 in cerebral endothelium, levels of IL-6 were measured in cell culture supernatants of brain-derived endothelial cells exposed to dexamethasone, forskolin or dibutyryl cAMP and inhibitors of serine-proteases. In primary cells an...

Inhibition of carrageenin-induced paw edema by a superoxide dismutase derivative that circulates bound to albumin

Although the possible involvement of superoxide radical and its metabolite(s) in the pathogenesis of various types of edema have been suggested, direct evidence supporting this concept is lacking. Since intravenously administered Cu 2+Zn 2+-type superoxide dismutase (SOD) rapidly disappeared from the circulation with a half-life of 4 min, the enzyme could not be used to test whether superoxide radicals played a critical role in the modulation of vascular permeability. We previously synthesized a SOD derivative (SM-SOD) by linking poly(styrene co-maleic acid butyl ester) (SM) to the enzyme (Ogino, T., Inoue, M., Ando, Y., Awai, M., Maeda, H. and Morino Y. (1988) Int. J. Pept. Protein Res. 32, 1583–1588); SM-SOD circulates bound to albumin with a half-life of 6 h. To test whether superoxide radicals play an important role in the regulation of vascular permeability, the effect of SM-SOD on experimental paw edema was studied in the rat. Subcutaneous injections of carrageenin to the paw rapidly induced local edema by increasing vascular permeability. Intravenous administration of SM-SOD markedly inhibited the carrageenin-induced increase in vascular permeability and suppressed the development of paw edema. In contrast, the same dose of SOD showed no such inhibitory effect. These results suggested that superoxide radical and/or its metabolite(s) might play a critical role in the pathogenesis of carrageenin-induced vasogenic edema.

Physiologic Regulation of Capillary Permeability

The review provides an update and overview of the role of exchange microvessels in the transfer of materials between circulating blood and metabolizing tissues. Following a presentation of the basic mechanisms governing transvascular movement of water and solutes, both active and passive modulation of vascular permeability are discussed. Some of the issues under current study are highlighted and a few of the questions awaiting answers are raised.

Modulatory role of eicosanoids in vascular changes during the preovulatory period in the rat.

Previous studies have demonstrated the involvement of eicosanoids (prostaglandins and hydroxyperoxides, including leukotrienes) in ovulation in several mammalian species. In this study, the role played by eicosanoids in the vascular changes that occur in the immediate preovulatory period after human chorionic gonadotropin (hCG) stimulation was examined in the rat. Changes in the ovarian uptake of two iodinated proteins were examined 30 minutes after i.v. injection of 125I-bovine serum albumin (BSA, Mr = 68,000) and 125I-alpha 2-macroglobulin (alpha 2M, Mr = 750,000). Uptake was measured during 30 min, 0, 3, 6, and 9 h after induction of ovulation by an i.p. injection of human chorionic gonadotropin (hCG, 10 IU). hCG enhanced the uptake of both iodinated proteins, with peak uptake values at 6 and 9 h. Intra-bursal injections of an ovulation inhibiting dose (0.5 mg/bursa) of indomethacin-a cycooxygenase inhibitor-and nordihydroguaiaretic acid (NDGA), esculetin, or caffeic acid--inhibitors of lipoxygenase--concomitantly with hCG attenuated the action of the hormone on 125I-BSA uptake. Indomethacin and esculetin were without effect on the uptake of alpha 2M. Ovarian and follicular blood flow was measured using 113Sn-microspheres. hCG increased ovarian and follicular blood flow with the most pronounced effect at the early time of 1.5 h. Indomethacin and NDGA did not attenuate this action of hCG. Accordingly, ovarian vascular resistance was reduced by hCG at 1.5, 6, and 9 h post-hCG, respectively, and indomethacin and NDGA had no significant effects. We suggest that one way in which eicosanoids are involved in follicular rupture is by their modulation of vascular permeability as revealed by uptake of the protein marker albumin.

The modulation of vascular permeability by prostaglandins through their effect on blood flow (Hyperemia)

The modulation of vascular permeability by prostaglandins through their effect on blood flow (Hyperemia)