S1P1 and S1P3 are potential markers of cardiac microangiopathy in diabetes

The prevalence of diabetes is rising rapidly throughout the world, accompanying with the increased occurrence of cardiovascular diseases in clinic. For now, the diagnosis of diabetic cardiovascular diseases has mainly based on the measurement of glucose levels in blood and cardiac function via electrocardiogram and ultrasound cardiogram. However, growing evidence strongly suggests that the assessment of Sphingosine-1-phosphate receptor 1/3 (S1P1/3) own advantages over present measurements in predicting the risk of developing diabetic cardiovascular diseases. This hypothesis may provide concept foundation for improving early diagnosis of cardiac microangiopathy in diabetes.     

促血管生成素-1与血管通透性调节

Angiopoietin-1 (Ang-1) is a newly-found endothelium-specific proangiogenic factor and it had been proved essential roles in both vasculogenesis and angiogensis. Among them, its anti - leakage abihty may have great potential apphcations in chnical treatment of vascular hyper-permeability in a variety of diseases such as cancer, diabetic retinopathy, rheumatoid arthritis, asthma. In this review, some research progresses focused on this aspect are discussed.     

IL-1 and IFN-gamma increase vascular permeability.

We examined the effect of cytokines on vascular permeability in vivo. Wistar rats received intradermal injections of various cytokine preparations and the permeability index (delta PI) was calculated from the difference between the absorption values of cytokine- and vehicle-treated skin sections after the extraction of accumulated Evans blue vital dye. Injections of a mixture of recombinant interleukin-1 alpha and beta (Il-1 alpha, IL-1 beta) and interferon-gamma (IFN-gamma) caused a maximal increase of permeability after 30 min (delta PI = 2). The administration of single recombinant cytokines revealed that the increase of permeability is mainly due to the action of IL-1 beta (delta PI = 1.4) and IFN-gamma (delta PI = 2.9) (P less than 0.001) at doses of 1-20 microU per injection site. IL-1 alpha slightly increased vascular permeability, whereas recombinant IL-2 and recombinant tumour necrosis factor alpha had no significant effects. Histological observations revealed significantly increased numbers of degranulated mast cells in skin sections pretreated with IL-1 beta (P less than 0.005) or IFN-gamma (P less than 0.001). The cytokine-mediated rise of vascular permeability could be suppressed by pretreatment of the animals with the vasoactive amine antagonizing drugs methysergide, pizotifen and cyproheptadine. Our experiments indicate an important role of IL-1 beta and IFN-gamma as vasoactive substances besides their function as hormone-like messengers between leucocytes.     

Increase in vascular permeability induced by leukotriene b4 and the role of polymorphonuclear leukocytes

Leukotriene B₄ (LTB₄), a metabolite of arachidonic acid, is known to be a potent chemotactic and chemokinetic substance. We have used the hamster cheek pouch microcirculation model to study the effect of LTB₄ on vascular permeability and the involvement of neutrophil granulocytes in this response. Intravascular fluorescein-labeled dextran (mol wt 150,000) was used as a tracer of macromolecular permeability. Topical application of LTB₄ (150 nM-5 M) to the hamster cheek pouch resulted in an immediate increase in adhering leukocytes in postcapillary venules and later larger venules. Leukocyte accumulation was reversible, but continued longer the higher the dose of LTB₄ used. Subsequently, a dose-dependent increase in vascular permeability was seen at postcapillary and larger venules, with a maximum 10–20 min after application; the maximum occurred later the higher the dose of LTB₄. Depletion of neutrophil granulocytes by pretreatment of the animals with antineutrophil serum obtained from immunized rabbits significantly decreased the permeability response to LTB₄, whereas the response to histamine was unaffected. These results suggest that neutrophil granulocytes play a role in LTB₄-mediated permeability increase. LTB₄ may be of importance both for the leukocyte accumulation and for the edema formation seen in inflammatory reactions.     

The role of fibrin in the mechanism of vascular permeability

Summary The effect of nicotinic acid and heparin on vascular permeability was studied in dogs. The state of vascular permeability was determined by the rate of Evans blue elimination from the blood. Nicotinic acid and heparin had a marked intensifying effect on the fibrinolytic activity of the blood. Notwithstanding the intensified fibrinolysis, no disturbance of the vascular permeability was detected. This casts doubt both on the literature data concerning the presence of fibrin film on the internal surface of normal vessels and on the supposition concerning the fibrin participation in the mechanism of normal vascular permeability.Department of Pathological Physiology (Head, Professor I. A. Oivin), Kuban Medical Institute(Presented by Active Member AMN SSSR A. E. Braunshtein) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 54, No. 10, pp. 45–47, October, 1962     

HMGB1 in vascular diseases: Its role in vascular inflammation and atherosclerosis

The nuclear protein high mobility group box 1 (HMGB1) has been suggested to be involved in the pathogenesis of several vascular diseases such as systemic vasculitis and atherosclerosis. In systemic vasculitides including ANCA-associated vasculitis and Kawasaki disease, serum HMGB1 levels are higher in patients with active disease compared to healthy controls. In atherosclerotic disease, HMGB1 displays increased expression in nuclei and cytoplasm of macrophages and smooth muscle cells in the atherosclerotic lesions, and is implicated in the progression of the atherosclerotic plaque. Experimental models of acute coronary syndromes and cerebrovascular accidents show that HMGB1 is not only involved in the amplification of the inflammatory response during acute ischemic injury, but also in the recovery and remodeling process after ischemia. Patients with acute coronary syndromes or stroke present significantly higher serum levels of HMGB1 than healthy controls and levels are associated with disease severity and mortality. Here we review clinical and experimental studies dealing with the role of HMGB1 in vascular diseases.     

Capsaicin-induced substance P release and sensory control of vascular permeability in the guinea-pig ureter

Substance P-immunoreactivity (SP-IR) in the guinea-pig ureter was found to be totally depleted after systemic capsaicin pretreatment. Removal of the inferior mesenteric ganglion (IMG) led to a total depletion of SP-IR from the rostral third of the ureter and to a partial depletion from the caudal third. Electrical stimulation of the IMG caused Evans blue extravasation mainly in the rostral third of both ureters, whereas stimulation of the right pelvic nerve caused Evans blue extravasation in the caudal third of the ureters on both sides. The responses to nerve stimulation were absent in capsaicin-pretreated animals. Furthermore, capsaicin caused release of SP-IR from ureter slices in vitro, this release was not inhibited by tetrodotoxin. Potassium (60 and 120 mM) also released SP-IR. It is concluded that SP-IR in the ureter is contained in capsaicin-sensitive sensory neurons reaching the ureter via both parasympathetic (caudal part) and sympathetic nerves (rostral part). Activation of these neurons by capsaicin leads to a peripheral release of SP-IR which most likely increases vascular permeability.     

Oncogenic S1P signalling in EBV‐associated nasopharyngeal carcinoma activates AKT and promotes cell migration through S1P receptor 3

Undifferentiated nasopharyngeal carcinoma (NPC) is a cancer with high metastatic potential that is consistently associated with Epstein–Barr virus (EBV) infection. In this study, we have investigated the functional contribution of sphingosine‐1‐phosphate (S1P) signalling to the pathogenesis of NPC. We show that EBV infection or ectopic expression of the EBV‐encoded latent genes (EBNA1, LMP1, and LMP2A) can up‐regulate sphingosine kinase 1 (SPHK1), the key enzyme that produces S1P, in NPC cell lines. Exogenous addition of S1P promotes the migration of NPC cells through the activation of AKT; shRNA knockdown of SPHK1 resulted in a reduction in the levels of activated AKT and inhibition of cell migration. We also show that S1P receptor 3 (S1PR3) mRNA is overexpressed in EBV‐positive NPC patient‐derived xenografts and a subset of primary NPC tissues, and that knockdown of S1PR3 suppressed the activation of AKT and the S1P‐induced migration of NPC cells. Taken together, our data point to a central role for EBV in mediating the oncogenic effects of S1P in NPC and identify S1P signalling as a potential therapeutic target in this disease. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Endothelin-1 induces the transactivation of vascular endothelial growth factor receptor-3 and modulates cell migration and vasculogenic mimicry in melanoma cells

Endothelin receptor B (ET_BR) is a G-protein-coupled receptor overexpressed in melanoma, blood, and lymphatic endothelial cells. Given that aberrant signal transduction can be mediated through cross talk between receptors, here, we explore the functional relationship between ET_BR and the vascular endothelial growth factor receptor (VEGFR)-3 system and how this cross talk might influence the aggressive behavior of melanoma cells. The expression of VEGFR-3 and its ligands, VEGF-C and VEGF-D, significantly increased after activating ET_BR by ET-1 in primary and metastatic melanoma cell lines. These effects, similarly to those induced by hypoxia, were mediated by hypoxia-inducible factor (HIF)-1α and HIF-2α. ET-1 caused the phosphorylation of VEGFR-3, which was accompanied by the activation of the downstream signaling molecules, such as MAPK and AKT. Inhibition of c-Src activity or silencing of the scaffold protein β-arrestin-1 reduced ET-1-induced VEGFR-3 phosphorylation, demonstrating that, upon ET-1 stimulus, β-arrestin-1 is involved with c-Src in the ET_BR-mediated VEGFR-3 transactivation. Moreover, ET-1 in combination with VEGF-C further increased VEGFR-3, MAPK, and AKT phosphorylation and markedly promoted cell migration and vasculogenic mimicry. Dual inhibition of ET_BR and VEGFR-3 was required for the effective inhibition of these effects, as well as for VEGFR-3 phosphorylation, demonstrating that ET_BR cross talk with VEGFR-3 enhances cell plasticity and motility. Finally, in melanoma xenografts, ET_BR antagonist inhibited tumor growth and the activation of the VEGF-C/VEGFR-3 axis, indicating that targeting ET_BR may improve melanoma treatment acting directly or indirectly by impairing ET_BR cross talk with VEGFR-3.     

Products by the sphingosine kinase/sphingosine 1-phosphate (S1P) lyase pathway but not S1P stimulate mitogenesis

Sphingosine 1-phosphate (S1P) functions as a ligand for the S1P/EDG family receptors. For years, intracellular signaling roles for S1P have also been suggested, especially in cell proliferation. Now, we have generated several mouse F9 embryonic carcinoma cell lines varying in expression of the S1P-degrading enzyme, S1P lyase (SPL) and/or sphingosine kinase (SPHK1). All these cell lines accumulated S1P compared to the wild-type F9 cells, but the amounts varied. We investigated the ability of these cells to proliferate under low serum conditions, as measured by a thymidine uptake assay. Although F9 cells over-expressing SPHK1 did exhibit enhanced DNA synthesis, other S1P-accumulating cells (SPL-null cells and SPL-null cells over-expressing SPHK1) did not. The overproduction of both SPL and SPHK1 resulted in the most striking mitogenic effect. Moreover, nM concentrations of sphingosine (or dihydrosphingosine) stimulated DNA synthesis in an SPL-dependent manner. These results indicate that products by the SPL pathway, not S1P itself, function in mitogenesis.     

Regulation of microvascular permeability by vascular endothelial growth factors

Generation of new blood vessels from pre-existing vasculature (angiogenesis) is accompanied in almost all states by increased vascular permeability. This is true in physiological as well as pathological angiogenesis, but is more marked during disease states. Physiological angiogenesis occurs during tissue growth and repair in adult tissues, as well as during development. Pathological angiogenesis is seen in a wide variety of diseases, which include all the major causes of mortality in the west: heart disease, cancer, stroke, vascular disease and diabetes. Angiogenesis is regulated by vascular growth factors, particularly the vascular endothelial growth factor family of proteins (VEGF). These act on two specific receptors in the vascular system (VEGF-R1 and 2) to stimulate new vessel growth. VEGFs also directly stimulate increased vascular permeability to water and large-molecular-weight proteins. We have shown that VEGFs increase vascular permeability in mesenteric microvessels by stimulation of tyrosine auto-phosphorylation of VEGF-R2 on endothelial cells, and subsequent activation of phospholipase C (PLC). This in turn causes increased production of diacylglycerol (DAG) that results in influx of calcium across the plasma membrane through store-independent cation channels. We have proposed that this influx is through DAG-mediated TRP channels. It is not known how this results in increased vascular permeability in endothelial cells in vivo. It has been shown, however, that VEGF can stimulate formation of a variety of pathways through the endothelial cell, including transcellular gaps, vesiculovacuolar organelle formation, and fenestrations. A hypothesis is outlined that suggests that these all may be part of the same process.     

Endothelial functional responses and increased vascular permeability induced by polycations

Polycations such as poly-L-lysine powerfully stimulated cultured endothelial cells from pig aorta to release prostacyclin and cytoplasmic purines in a dose (charge)-dependent and molecular weight (size) dependent manner. Neutral or anionic polymers were inactive. Qualitatively similar findings were made in vivo where poly-L-lysine induced charge and size-dependent local edema formation after intradermal injection in the rabbit. Pretreatment of cultured endothelium with heparin or trypsin (but not neuraminidase) effectively reduced the response of the cells to subsequent exposure to poly-L-lysine suggesting an interaction of polycations with integral membrane proteins. Edema responses to poly-L-lysine were reduced in the presence of indomethacin suggesting that generation of an endogenous vasodilator prostaglandin, perhaps endothelial cell-derived, was an important component of the response. Poly-L-lysine-induced edema formation was not dependent on endogenous histamine release but was reduced by locally administered trasylol while soybean trypsin inhibitor failed to inhibit the response. Our results indicate that polycations such as poly-L-lysine can induce responses of vascular endothelium in vitro and in vivo and that the effects are not only charge-related but are also dependent on the size of the polycation. We suggest that naturally occurring polycations such as those derived from leukocytes and platelets may play an important role in various pathologic processes and that this may be closely related to their size.     

Physiological regulation of vascular permeability by endogenous glucocorticoids and active oxygen

A copper chelator, diethyldithiocarbamate (DDC), injection and adrenalectomy induce significant paw swelling by low doses of serotonin, histamine, or bradykinin, which can result in mild swelling in non-treated mice. Dexamethasone, Cu,Zn-superoxide dismutase (SOD), and hydroxyl radical scavengers suppressed the DDC-provoked edema, but only dexamethasone suppressed the edema of adrenalectomized mice. Adrenal stimulation by SOD is exclusive in that the suppression of edema by SOD began about 1 h prior to that by glucocorticoid. In order to explain the data obtained, the existence of a vascular permeability inhibitory protein (called “vasoregulin”) was assumed. This protein must be synthesized constantly somewhere in the body and continuously inactivated by active oxygen in vivo. Local levels of vasoregulin may limit the responses of vascular permeability against the chemical mediators. This hypothesis was also supported by the edema-enhancing effects of protein/RNA synthesis inhibitors.