PEDF inhibits VEGF-induced vascular leakage through binding to VEGFR2 in acute myocardial infarction.

Pigment epithelium-derived factor (PEDF) could bind to vascular endothelial growth factor receptor 2 (VEGFR2) and inhibit its activation induced by VEGF. But how PEDF affects VEGFR2 pathway is still poorly understood. In this study, we elucidated the precise mechanism underlying the interaction between PEDF and VEGFR2, and subsequently corroborated our findings using a rat AMI model. PEDF prevented endocytosis of VE-cadherin induced by hypoxia, thereby protecting the endothelium integrity. A three-dimensional model of the VEGFR2-PEDF complex was constructed by protein-protein docking method. The results showed that the VEGFR2-PEDF complex was stable during the simulation. Hydrogen bonds, binding energy and binding modes were analyzed during molecular dynamics simulations, which indicated that hydrogen bonds and hydrophobic interactions were important for the recognition of VEGFR2 with PEDF. In addition, the results from exudation of fibrinogen suggested that PEDF inhibits vascular leakage in acute myocardial infarction and confirmed the critical role of key amino acids in the regulation of endothelial cell permeability. This observation is also supported by echocardiography studies showing that the 34mer peptide sustained cardiac function during acute myocardial infarction. Besides, PEDF and 34mer could inhibit the aggregation of myofiber in the heart and promoted the formation of a dense cell layer in cardiomyocytes, which suggested that PEDF and 34mer peptide protect against AMI-induced cardiac dysfunction. These results suggest that PEDF inhibits the phosphorylation of downstream proteins, thereby preventing vascular leakage, which provides a new therapeutic direction for the treatment of acute myocardial infarction.Communicated by Ramaswamy H. Sarma.

In vivo odorant input induces distinct synaptic plasticity of GABAergic synapses in developing zebrafish olfactory bulb.

In the first station of central odor processing, the main olfactory bulb, signal processing is regulated by synaptic interactions between glutamatergic and GABAergic inputs of the mitral cells (MCs), the major projection neurons. Our previous study has found that repetitive postsynaptic spiking within a critical time window after presynaptic activation by natural odorant stimulation results in persistent enhancement of glutamatergic inputs of MCs in larval zebrafish. Here we observed a long-term depression of GABAergic synapses induced by the same protocol. This long-term depression was mediated by presynaptic NMDA receptors (NMDARs). Further dissecting GABAergic neurotransmission revealed that the STDP-induction protocol induced persistent modification in recurrent and lateral inhibition with opposite directions and distinct requirements on NMDARs. Thus, at the plasticity level, different types of GABAergic inhibition may utilize different mechanisms to cooperate or compete with excitatory inputs to optimize patterns of olfactory bulb output.

Increased number of intratumoral IL-17+ cells, a harbinger of the adverse prognosis of triple-negative breast cancer.

INTRODUCTION: Triple negative breast cancer (TNBC) is an aggressive cancer subtype and lack of effective targeted therapies. It has been recently reported that Interleukin 17 (IL-17), a family of cytokines secreted in tumor microenvironment, affects tumor progression through a variety of molecular pathways. Its role in TNBC is so far still poorly explored. MATERIALS AND METHODS: We employed immunohistochemistry to evaluate the distribution of IL-17+ cells in TNBC with no special type features (TNBC-NST), their association with tumor microangiogenesis, as well as their impact on prognosis of the patients. RESULTS: In comparison to medullary carcinoma with triple-negative molecular features (TNBC-MC), we found a significant increase in IL-17+ cell infiltrates in intratumoral stroma and extratumoral stroma of TNBC-NST. Similarly, stromal cells with co-expression of CD4 and IL-17 were noted in intratumoral and extratumoral stroma in both TNBC-NST and TNBC-MC. In addition, intratumoral IL-17+ cells were positively associated with tumor cell expression of vascular endothelial growth factor A (VEGFA) and with intratumoral tumor microvascular density (MVD). Multivariate analysis identified that intratumoral IL-17+ cells (P = 0.018), MVD (P = 0.039), and TNM stage (P = 0.002) were independent prognostic factors for predicting poor PFS. CONCLUSION: The study indicates that IL-17 is overexpressed in intratumoral stromal cells of TNBC-NST. The overexpression of IL-17 might engage in active tumor microangiogenesis through its signal transduction pathways resulting in increased tumor secretion of VEGFA, and then promote tumor progression. IL-17 might serve as a potential new target for individualized therapy to TNBC-NST patients by development of specific antibodies. Additional study is deemed to further explore the role of IL-17+ stromal cells in breast cancer.

Pigment Epithelium-Derived Factor (PEDF) Improves Ischemic Cardiac Functional Reserve Through Decreasing Hypoxic Cardiomyocyte Contractility Through PEDF Receptor (PEDF-R).

BACKGROUND: Pigment epithelium-derived factor (PEDF), which belongs to the noninhibitory serpin family, has shown the ability to stimulate several physiological processes, such as antiangiogenesis, anti-inflammation, and antioxidation. In the present study, the effects of PEDF on contractility and calcium handling of rat ventricular myocytes were investigated. METHODS AND RESULTS: Adult Sprague-Dawley rat models of acute myocardial infarction (AMI) were surgically established. PEDF-lentivirus was delivered into the myocardium along and away from the infarction border to overexpress PEDF. Video edge detection was used to measure myocyte shortening in vitro. Intracellular Ca(2+) was measured in cells loaded with the Ca(2+) sensitive fluorescent indicator, Fura-2-acetoxymethyl ester. PEDF local overexpression enhanced cardiac functional reserve in AMI rats and reduced myocardial contracture bordering the infracted area. Exogenous PEDF treatment (10 nmol/L) caused a significant decrease in amplitudes of isoproterenol-stimulated myocyte shortening, Ca(2+) transients, and caffeine-evoked Ca(2+) transients in vitro. We then tested a potential role for PEDF receptor-mediated effects on upregulation of protein kinase C (PKC) and found evidence of signaling through the diacylglycerol/PKCα pathway. We also confirmed that pretreatment of cardiomyocytes with PEDF exhibited dephosphorylation of phospholamban at Ser(16), which could be attenuated with PKC inhibition. CONCLUSIONS: The results suggest that PEDF depresses myocyte contractility by suppressing phosphorylation of phospholamban and Ca(2+) transients in a PKCα-dependent manner through its receptor, PEDF receptor, therefore improving cardiac functional reserve during AMI.

PEDF improves cardiac function in rats with acute myocardial infarction via inhibiting vascular permeability and cardiomyocyte apoptosis.

Pigment epithelium-derived factor (PEDF) is a pleiotropic gene with anti-inflammatory, antioxidant and anti-angiogenic properties. However, recent reports about the effects of PEDF on cardiomyocytes are controversial, and it is not known whether and how PEDF acts to inhibit hypoxic or ischemic endothelial injury in the heart. In the present study, adult Sprague-Dawley rat models of acute myocardial infarction (AMI) were surgically established. PEDF-small interfering RNA (siRNA)-lentivirus (PEDF-RNAi-LV) or PEDF-LV was delivered into the myocardium along the infarct border to knockdown or overexpress PEDF, respectively. Vascular permeability, cardiomyocyte apoptosis, myocardial infarct size and animal cardiac function were analyzed. We also evaluated PEDF's effect on the suppression of the endothelial permeability and cardiomyocyte apoptosis under hypoxia in vitro. The results indicated that PEDF significantly suppressed the vascular permeability and inhibited hypoxia-induced endothelial permeability through PPARγ-dependent tight junction (TJ) production. PEDF protected cardiomyocytes against ischemia or hypoxia-induced cell apoptosis both in vivo and in vitro via preventing the activation of caspase-3. We also found that PEDF significantly reduced myocardial infarct size and enhanced cardiac function in rats with AMI. These data suggest that PEDF could protect cardiac function from ischemic injury, at least by means of reducing vascular permeability, cardiomyocyte apoptosis and myocardial infarct size.

[In vivo transfection of hepatocyte growth factor gene induces pulmonary angiogenesis in rabbits with hyperkinetic pulmonary hypertension].

OBJECTIVE: To investigate the effect of adenoviral-mediated exogenous HGF (Ad-HGF) gene transfer on lung angiogenesis in the rabbit lung in rabbits with hyperkinetic pulmonary artery hypertension. METHODS: A thoracotomy was performed through a midsternal incision in 1-month-old immature rabbit and an anastomosis between the left innominate artery and the pulmonary trunk was made to establish a chronic patent left to right shunt. Three months later, animals were randomly assigned to receive either Ad-HGF (2 x 10(9) Pfu in 0.2 ml PBS, H1 group), repeated administration of Ad-HGF after one week (H 2 group), Ad-GFP (2 x 10(9) Pfu in 0.2 ml PBS, G group), or PBS (0.2 ml, C group) by the intratracheal method of gene transfection. After two weeks, reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical examination was performed to identify HGF mRNA and HGF protein expression. The capillary density and small pulmonary artery density were determined by immunostained with antibodies against factor VIII and alpha-SMA. After 1 month, the collateral vessels were evaluated by angiogram under digital subtraction angiography (DSA). RESULTS: Two weeks after Ad-HGF transfection, 484 bp bands could be found by RT-PCR in H1 and H2 groups, but not in other groups. The expression of HGF protein could be detected on alveolar epithelium and pulmonary vessel endothelium by immunohistochemistry examination. The number of factor VIII-positive pulmonary capillaries was also significantly increased in the H1 and H2 groups compared with the C and G groups (P < 0.05). The capillary density reached (17.0 +/- 3.3) mm(2) and (19.7 +/- 2.8) mm(2) in the H1 and H2 group, respectively, whereas it remained (13.2 +/- 3.2) mm(2) in the C group and (13.5 +/- 2.4) mm(2) in the G group (P < 0.05). One month after Ad-HGF transfection, the number of small pulmonary arteries was significantly increased in H1 and H2 group compared with control groups (P < 0.05). The collateral vessels were more abundant in HGF transfection groups than that in the two control groups reviewed by angiogram under digital subtraction angiography (DSA). CONCLUSION: In vivo gene transfection with HGF by means of the intra-tracheal injection could induce pulmonary angiogenesis in the early stage and small pulmonary arterial angiogenesis in later stage.

[Delayed disappearance of h-VEGF165 mRNA and protein under regulation of hypoxic response element].

Transfer of vascular endothelial growth factor (VEGF) gene to ischemic myocardium may provide a useful approach for angiogenesis and improve cardiac performance. However, uncontrolled expression of VEGF in vivo may result in certain side effects, such as hemangioma formation, retinopathy, and tumor development. We investigated the feasibility of using the nine copies of hypoxic response element (HRE) to control the expression of human VEGF(165) (h-VEGF(165)) under anoxic condition at cell level and also observed the synchron of h-VEGF(165) mRNA and protein expressions. Recombinant adeno-associated viral (rAAV) vector was prepared by using the three-plasmid system and cotransfected to human embryo kidney 293T cells by the calcium phosphate precipitates method. The rAAV vector was purified by chloroform-PEG8000/NaCl-chloroform and added to cultured myocardiocytes. Myocardiocytes of Sprague-Dawley rat were cultured in serum-free medium and then randomly divided into eight groups. Group I: cultured under normoxic conditions (21% O2) for 8 h as control; Group II: cultured under anoxic conditions (1% O2) for 8 h; Group III: cultured under normoxic conditions (21% O2) for 8 h with gene transfer; Group IV: cultured under anoxic conditions (1% O2) for 8 h with gene transfer; Group V, VI, VII: cultured under anoxic conditions (1% O2) for 8 h with gene transfer and then tured to normoxic conditions (21% O2) for 4, 8 or 12 h, respectively; Group VIII: cultured under anoxic conditions (1% O2) for 20 h with gene transfer. After completion of cell culture, the amount of h-VEGF(165) protein in culture supernatant was quantified by using enzyme linked immunosorbent assay (ELISA). Expression of h-VEGF(165) protein in cultured cardiacmyocytes was also evaluated by immunofluorescence. RT-PCR was employed to detect the expression of h-VEGF(165) mRNA. The results revealed that there were no expressions of h-VEGF(165) mRNA and protein in groups I, II, III, VI and VII. After gene transfer, the expressions of h-VEGF(165) protein and mRNA were significantly higher in groups IV and VIII than those in other groups (P<0.01); Immunofluorescence positive cells were observed in groups IV, V and VIII. RT-PCR revealed that a 484-bp strip can be found in groups IV and VIII, but unavailable in other groups. We conclude that HRE is a promising regulator for h-VEGF(165) gene expression following the changes of oxygen environment. HRE can induce the expression of h-VEGF(165) gene after hypoxia, but in normal oxygen condition, the expression of h-VEGF(165) was inhibited. Although expression of h-VEGF(165) mRNA ceased in normal oxygen condition under the control of HRE, expression of h-VEGF(165) protein was hysteretic to h-VEGF(165) mRNA expression.