Influence of Dll4 via HIF-1α-VEGF signaling on the angiogenesis of choroidal neovascularization under hypoxic conditions

Endothelial cells signaling and patterning under hypoxia: a mechanistic integrative computational model including the Notch-Dll4 pathway

Introduction: Several signaling pathways are activated during hypoxia to promote angiogenesis, leading to endothelial cell patterning, interaction, and downstream signaling. Understanding the mechanistic signaling differences between endothelial cells under normoxia and hypoxia and their response to different stimuli can guide therapies to modulate angiogenesis. We present a novel mechanistic model of interacting endothelial cells, including the main pathways involved in angiogenesis. Methods: We calibrate and fit the model parameters based on well-established modeling techniques that include structural and practical parameter identifiability, uncertainty quantification, and global sensitivity. Results: Our results indicate that the main pathways involved in patterning tip and stalk endothelial cells under hypoxia differ, and the time under hypoxia interferes with how different stimuli affect patterning. Additionally, our simulations indicate that Notch signaling might regulate vascular permeability and establish different Nitric Oxide release patterns for tip/stalk cells. Following simulations with various stimuli, our model suggests that factors such as time under hypoxia and oxygen availability must be considered for EC pattern control. Discussion: This project provides insights into the signaling and patterning of endothelial cells under various oxygen levels and stimulation by VEGFA and is our first integrative approach toward achieving EC control as a method for improving angiogenesis. Overall, our model provides a computational framework that can be built on to test angiogenesis-related therapies by modulation of different pathways, such as the Notch pathway.

Modulation of Hypoxia-Inducible Factors and Vascular Endothelial Growth Factor Expressions by Superfood Camu-Camu (Myrciaria dubia) Treatment in ARPE-19 and Fetal Human RPE Cells

Background

Anti-vascular endothelial growth factor (anti-VEGF) therapy via intravitreal injection is an effective treatment for patients with abnormal ocular neovascularization, such as age-related macular degeneration (AMD) and diabetic macular edema (DME). However, prolonged and frequent anti-VEGF treatment is associated with a risk of local and systemic adverse events, including geographic atrophy, cerebrovascular disease, and death. Furthermore, some patients do not adequately respond to anti-VEGF therapy. Hypoxia-inducible factor (HIF) is a transcription factor that controls the expression of hypoxia-responsive genes involved in angiogenesis, inflammation, and metabolism. The HIF/VEGF pathway plays an important role in neovascularization, and the inhibition of HIF activation could be an effective biomolecular target for neovascular diseases. The demand for disease prevention or treatment using functional foods such as superfoods has increased in recent years. Few reports to date have focused on the antineovascular effects of superfoods in the retinal pigment epithelium (RPE). In light of the growing demand for functional foods, we aimed to find novel HIF inhibitors from superfoods worked in RPE cells, which could be an adjuvant for anti-VEGF therapy.

Methods

Seven superfoods were examined to identify novel HIF inhibitor candidates using luciferase assay screening. We used the human RPE cell line ARPE-19 and fetal human RPE (fhRPE) to investigate the biomolecular actions of novel HIF inhibitors using quantitative PCR and western blotting.

Results

Under CoCl2-induced pseudohypoxic condition and 1% oxygen hypoxic incubation, camu-camu (Myrciaria dubia) showed HIF inhibitory effects determined by luciferase assays. Camu-camu downregulated HIF-1α and VEGFA mRNA expressions in a concentration-dependent manner. Camu-camu also inhibited HIF-1α protein expressions, and its inhibitory effect was greater than that of vitamin C, which is present at high levels in camu-camu.

Conclusion

The camu-camu extract suppressed the activation of HIF and VEGF in RPE cells. This could assist anti-VEGF therapy in patients with abnormal ocular neovascularization.

Endothelial cells signaling and patterning under hypoxia: a mechanistic integrative computational model including the Notch-Dll4 pathway

Several signaling pathways are activated during hypoxia to promote angiogenesis, leading to endothelial cell patterning, interaction, and downstream signaling. Understanding the mechanistic signaling differences between normoxia and hypoxia can guide therapies to modulate angiogenesis. We present a novel mechanistic model of interacting endothelial cells, including the main pathways involved in angiogenesis. We calibrate and fit the model parameters based on well-established modeling techniques. Our results indicate that the main pathways involved in the patterning of tip and stalk endothelial cells under hypoxia differ, and the time under hypoxia affects how a reaction affects patterning. Interestingly, the interaction of receptors with Neuropilin1 is also relevant for cell patterning. Our simulations under different oxygen concentrations indicate time- and oxygen-availability-dependent responses for the two cells. Following simulations with various stimuli, our model suggests that factors such as period under hypoxia and oxygen availability must be considered for pattern control. This project provides insights into the signaling and patterning of endothelial cells under hypoxia, contributing to studies in the field.

Inflammatory Cytokine-Induced HIF-1 Activation Promotes Epithelial-Mesenchymal Transition in Endometrial Epithelial Cells

The endometrium undergoes repeated proliferation and shedding during the menstrual cycle. Significant changes to this environment include fluctuations in the partial pressure of oxygen, exposure to a high-cytokine environment associated with intrauterine infection, and inflammation. Chronic endometritis is a condition wherein mild inflammation persists in the endometrium and is one of the causes of implantation failure and miscarriage in early pregnancy. It is thought that the invasion of embryos into the endometrium requires epithelial-mesenchymal transition (EMT)-associated changes in the endometrial epithelium. However, the effects of inflammation on the endometrium remain poorly understood. In this study, we investigated the effects of the intrauterine oxygen environment, hypoxia-inducible factor (HIF), and inflammation on the differentiation and function of endometrial epithelial cells. We elucidated the ways in which inflammatory cytokines affect HIF activity and EMT in an immortalized cell line (EM-E6/E7/TERT) derived from endometrial epithelium. Pro-inflammatory cytokines caused significant accumulation of HIF-1α protein, increased HIF-1α mRNA levels, and enhanced hypoxia-induced accumulation of HIF-1α protein. The combined effect of inflammatory cytokines and hypoxia increased the expression of EMT-inducing factors and upregulated cell migration. Our findings indicate that pro-inflammatory factors, including cytokines and LPS, work synergistically with hypoxia to activate HIF-1 and promote EMT in endometrial epithelial cells.

Activity-Dependent Neuroprotective Protein (ADNP): An Overview of Its Role in the Eye

Vision is one of the dominant senses in humans and eye health is essential to ensure a good quality of life. Therefore, there is an urgent necessity to identify effective therapeutic candidates to reverse the progression of different ocular pathologies. Activity-dependent neuroprotective protein (ADNP) is a protein involved in the physio-pathological processes of the eye. Noteworthy, is the small peptide derived from ADNP, known as NAP, which shows protective, antioxidant, and anti-apoptotic properties. Herein, we review the current state of knowledge concerning the role of ADNP in ocular pathologies, while providing an overview of eye anatomy.

Advanced Glycation End Products Induce Atherosclerosis via RAGE/TLR4 Signaling Mediated-M1 Macrophage Polarization-Dependent Vascular Smooth Muscle Cell Phenotypic Conversion

Objective. The objective of this study was to investigate the involved mechanisms of advanced glycation end product- (AGE-) exacerbated atherosclerosis (AS). Methods. Toll-like receptor 4 (TLR4) inhibitor was administrated to type 2 diabetes mellitus (T2DM) AS rats. Atherosclerotic plaque, M1 macrophage infiltration, and VSMCs phenotypes were evaluated. AGE-exposed primary macrophages were treated with specific siRNAs knocking down receptor for AGEs (RAGE) and TLR4. Phenotypes of M1 macrophage and VSMCs were identified by fluorescent stains. Contact and noncontact coculture models were established. VSMCs and macrophages were cocultured in these models. ELISA was used to detect inflammatory cytokine concentrations. Relative mRNA expression levels were determined by real-time PCR. Relative protein expression and phosphorylation levels were evaluated by Western blots assays. Results. TLR4 inhibitor treatment significantly reduced arterial stenosis, infiltration of M1 polarized macrophages, and contractile-to-synthetic phenotype conversion of VSMCs in DM AS animals. RAGE and TLR4 silencing dramatically reduced AGE-induced macrophage M1 polarization, inflammatory cytokine secretion, and RAGE/TLR4/forkhead box protein C2 (FOXC2)/signaling which inhibited delta-like ligand 4 (Dll4) expression in macrophages. AGE-treated macrophages induced VSMC phenotypic conversion via activating Notch pathway in a contact coculture model rather than a noncontact model. The VSMC phenotypic conversion induction capability of macrophages was attenuated by RAGE and TLR4 silencing. Conclusions. AGEs induced activation of RAGE/TLR4/FOXC2 signaling, which featured macrophage with Dll4 high expression during M1 polarization. These macrophages promoted contractile-synthetic phenotypic conversion of VSMCs through the Dll4/Notch pathway after direct cell-to-cell contacts.

Preliminary Research of Main Components of Dll4/ Notch-VEGF Signaling Pathway Under High-Glucose Stimulation in vitro

PURPOSE

To establish a high-glucose (HG) stressed cell model and study the expression of main components of the Dll4/Notch-VEGF signaling pathway under high-glucose stimulation.

METHODS

A model of HG-conditioned cells (human umbilical vein endothelial cells, HUVECs) was first established, and then the expression of Dll4, Notch1, Notch4 and VEGF in HG-stressed cells with or without Notch pathway blockage was analyzed by RT-PCR and Western blot. To observe cell migration, we also evaluated the Transwell assay.

RESULTS

HUVECs stimulated with 30mmol/L HG was selected as a cell model. RT-PCR and Western blot results showed that HG stimulation induced the expression of Dll4, Notch1 and VEGF and downregulated Notch4. The expressions were reversed after Notch pathway blockage; meanwhile, the blockage of Notch pathway inhibited cell migration under HG condition.

CONCLUSION

The function of Notch4 in responses to HG stimulation deserves further researching. Combination therapy by blocking Dll4/Notch and VEGF pathways may provide us with a new way for anti-neovascularization.

Rivaroxaban Suppresses Atherosclerosis by Inhibiting FXa-Induced Macrophage M1 Polarization-Mediated Phenotypic Conversion of Vascular Smooth Muscle Cells

Background: Factor Xa (FXa) is a mediator initiating and accelerating atherosclerosis (AS). Both macrophage and vascular smooth muscle cells (VSMCs) participate in AS progression. This study was aimed to investigate the mechanisms underlying the effects of the FXa inhibitor rivaroxaban on AS.

Methods: Rivaroxaban was administered to AS mice. Primary macrophages were exposed to FXa, treated with rivaroxaban, and transfected with siRNA silencing protease-activated receptor 2 (PAR2), hypoxia-inducible factor 1α (HIF1α), delta-like receptor 4 (Dll4), and Akt. Interaction between macrophages and VSMCs was assessed by co-culturing systems. Atherosclerotic lesions were evaluated by oil red O stain. Fluorescent staining was used to determine the cell phenotypes. Secretions of inflammatory cytokines and collagen were assessed by ELISA and Sircol assays. Western blotting was used to evaluate the protein expression and phosphorylation levels.

Results: Rivaroxaban reduced lesion area, accumulation of M1 macrophages, and contractile-synthetic phenotypic conversion of VSMCs in atherosclerotic plaques. FXa exposure induced polarization of macrophages toward M1 and Dll4 high expression, which were inhibited by PAR2, Akt1, and HIF1α silencing. Rivaroxaban treatment inhibited PAR2/Akt/HIF1α signaling activation and Dll4 expression in FXa-exposed macrophages. By cell-to-cell contact, M1 macrophages induced Notch signaling activation in VSMCs which committed contractile-synthetic conversion. Rivaroxaban treatment and Dll4 silencing incapacitated macrophage in inducing phenotypic conversion of VSMCs upon cell-to-cell contact.

Conclusion: Rivaroxaban suppresses AS by inhibiting FXa-induced PAR2/Akt/HIF1α signaling activation-mediated macrophage M1 polarization and high Dll4 expression. These macrophages facilitated VSMCs to perform contractile-synthetic phenotypic conversion upon macrophage-VSMCs cell-to-cell contact.

Effect of Porphyromonas gingivalis lipopolysaccharide on calcification of human umbilical artery smooth muscle cells co-cultured with human periodontal ligament cells

Periodontitis is an independent risk factor for coronary heart disease. Porphyromonas gingivalis lipopolysaccharide (Pg-LPS) was considered to be one of the main virulence factors. In addition, vascular smooth muscle cells transform into osteoblast-like cells in an arterial calcification process under chronic inflammatory conditions. The present study aimed to determine the calcification induced by Pg-LPS in human umbilical artery smooth muscle cells (HUASMCs) co-cultured with human periodontal ligament cells (HPDLCs). An in vitro co-culture system was established using Transwell inserts. HUASMC proliferation and alkaline phosphatase (ALP) activity were measured with a Cell Counting Kit-8 and an ALP kit, respectively. Calcium nodule formation was detected using alizarin red S staining. The effects of Pg-LPS on the mRNA expression of the calcification genes of ALP, core-binding factor α1 (Runx2) and bone sialoprotein (BSP) were assessed using reverse transcription-quantitative PCR. The results indicated that Pg-LPS increased HUASMC proliferation and ALP activity. Furthermore, among all of the groups, calcium nodule formation was most extensive in co-cultured cells in the mineralization-inducing medium containing Pg-LPS. In addition, the expression of specific osteogenic genes (Runx2, ALP and BSP) significantly increased in the presence of Pg-LPS and mineralization-inducing medium, which was further enhanced in co-culture with HPDLCs. In conclusion, co-culture with HPDLCs increased the effect of Pg-LPS to stimulate the calcification of HUASMCs. It was suggested that besides the inflammation, periodontitis may promote the occurrence of vascular calcification. The study indicated that periodontal treatment of subgingival scaling to reduce and/or control Porphyromonas gingivalis may decrease the occurrence or severity of vascular calcification.

The critical role of the interplays of EphrinB2/EphB4 and VEGF in the induction of angiogenesis

The significant role of VEGF (vascular endothelial growth factor) as an angiogenesis inducer is well recognized. Besides VEGF, EphrinB2/EphB4 also plays essential roles in vascular development and postnatal angiogenesis. Compared with classical proangiogenic factors, not only does EphrinB2/EphB4 promote sprouting of new vessels, it is also involved in the vessel maturation. Given their involvement in many physiologic and pathological conditions, EphB4 and EphrinB2 are increasingly recognized as attractive therapeutic targets for angiogenesis-related diseases through modulating their expression and function. Previous works mainly focused on the individual role of VEGF and EphrinB2/EphB4 in angiogenesis, respectively, but the correlation between EphrinB2/EphB4 and VEGF in angiogenesis has not been fully disclosed. Here, we summarize the structure and bidirectional signaling of EphrinB2/EphB4, provide an overview on the relationship between EphrinB2/EphB4 signaling and VEGF pathway in angiogenesis and highlight the associated potential usefulness in anti-angiogenetic therapy.

The Role of a Neurovascular Signaling Pathway Involving Hypoxia-Inducible Factor and Notch in the Function of the Central Nervous System

In the neurovascular unit, the neuronal and vascular systems communicate with each other. O₂ and nutrients, reaching endothelial cells (ECs) through the blood stream, spread into neighboring cells, such as neural stem cells, and neurons. The proper function of neural circuits in adults requires sufficient O₂ and glucose for their metabolic demands through angiogenesis. In a central nervous system (CNS) injury, such as glioma, Parkinson’s disease, and Alzheimer’s disease, damaged ECs can contribute to tissue hypoxia and to the consequent disruption of neuronal functions and accelerated neurodegeneration. This review discusses the current evidence regarding the contribution of oxygen deprivation to CNS injury, with an emphasis on hypoxia-inducible factor (HIF)-mediated pathways and Notch signaling. Additionally, it focuses on adult neurological functions and angiogenesis, as well as pathological conditions in the CNS. Furthermore, the functional interplay between HIFs and Notch is demonstrated in pathophysiological conditions.

Establishment of a multilayered 3D cellular model of the retinal-blood barrier

Retinal disorders are leading causes of blindness. Still, treatment strategies are limited and the challenging anatomical barriers of the eye limit the evaluation and development of new therapeutics. Among these layers of barriers is the blood-retinal barrier, which separates the retina from the choroid by the Bruch's membrane. This work aimed to establish a 3D cellular model that recapitulates barrier properties of the BRB and diffusion through the vitreous, the main barriers encountered upon intravitreal injection. Several parameters were evaluated namely co-culture time of ARPE-19 and HUVECs and different biomaterial compositions of hydrogels to better mimic the human vitreous. The developed vitreous mimic has viscoelastic properties similar to human vitreous. Co-culture of human retinal and endothelial cells showed increased transepithelial resistance with longer co-culture times concomitant with reduced permeability to FITC-dextran 40 kDa. The proposed models lay the foundation of a platform for faster assessment of a large number of samples and without the use of animals.

Notch Signaling Pathway Is Involved in bFGF-Induced Corneal Lymphangiogenesis and Hemangiogenesis

BACKGROUND

Notch/Dll4 involvement in cornea neovascularization (CRNV) and lymphangiogenesis is unclear. This study aimed to explore the role of notch signaling in basic fibroblast growth factor- (bFGF-) induced corneal lymphangiogenesis and hemangiogenesis.

METHODS

Corneal stroma of C57BL/6 mice was implanted with bFGF- or phosphate-buffered saline- (PBS-) soaked pellets. Corneal lymphangiogenesis and neovascularization were evaluated by immunofluorescence. Vascular endothelial growth factor-A (VEGF-A), Delta-like ligand 4 (Dll4), and Notch1 mRNA and protein expression were examined on days 1, 3, 7, and 14 by real-time polymerase chain reaction and western blot. Corneal cells were treated with ranibizumab, dexamethasone, and γ-secretase inhibitor (GSI). Microspheres were used to evaluate corneal hemangiogenesis in vivo.

RESULTS

Corneal hemangiogenesis reached its peak on day 7 after bFGF implantation, and corneal lymphangiogenesis was significantly higher on day 7 and 14, compared with PBS. mRNA and protein expression of VEGF-A, Dll4, and Notch1 were higher in bFGF-induced animal models compared with controls. Corneal hemangiogenesis and lymphangiogenesis decreased after 7 days of ranibizumab or dexamethasone treatment. After adding GSI for 24 h in bFGF-induced cells, the expression of Notch1 and Dll4 were downregulated compared with that in the control group whereas the expression level of VEGF-A was upregulated. Fluorescent particle number was higher in the GSI group. Ranibizumab and dexamethasone decreased the fluorescence signal.

CONCLUSION

The notch signaling pathway plays a role in regulating VEGF expression, affecting corneal lymphangiogenesis and hemangiogenesis in mice. The molecular imaging probe technique can visualize the changes in the VEGF-A expression level of corneal limbus hemangiogenesis.

Activator of G-protein signaling 8 is involved in VEGF-induced choroidal neovascularization

Choroidal neovascularization (CNV) is associated with age-related macular degeneration (AMD), a major cause of vision loss among elderly people. Vascular endothelial cell growth factor (VEGF) is essential for the development and progression of AMD, and VEGF signaling molecules are effective targets for the treatment of AMD. We recently reported that activator of G-protein signaling 8 (AGS8), a receptor-independent Gβγ regulator, is involved in VEGF-induced angiogenesis in cultured endothelial cells (EC); however, the role of AGS8 in CNV is not yet understood. This study aimed to explore the role of AGS8 in CNV in cultured cells, explanted choroid tissue, and laser-induced CNV in a mouse AMD model. AGS8 knockdown in cultured choroidal EC inhibited VEGF-induced VEGFR-2 phosphorylation, cell proliferation, and migration. AGS8 knockdown also downregulated cell sprouting from mouse choroidal tissue in ex vivo culture. A mouse model of laser-induced CNV, created to analyze the roles of AGS8 in vivo, demonstrated that AGS8 mRNA was significantly upregulated in choroidal lesions and AGS8 was specifically expressed in the neovasculature. Local AGS8 knockdown in intravitreal tissue significantly inhibited laser-induced AGS8 upregulation and suppressed CNV, suggesting that AGS8 knockdown in the choroid has therapeutic potential for AMD. Together, these results demonstrate that AGS8 plays critical roles in VEGF-induced CNV.

Gamma-Secretase Inhibitor, DAPT, Prevents the Development of Retinopathy of Prematurity in a Rat Model by Regulating the Delta-Like Ligand 4/Notch Homolog-1 (DLL4/Notch-1) Pathway

Background

Retinopathy of prematurity (ROP), or retrolental fibroplasia, affects premature infants who have undergone intensive care with oxygen therapy. This study aimed to investigate the inhibitory effect of the gamma-secretase inhibitor, DAPT, on neovascularization and its mechanism in a rat model of ROP.

Material/Methods

Sixty neonatal Sprague-Dawley (SD) rats included the control group (n=20), the model group (n=20), and the DAPT-treated group (n=20). The rat model of ROP was established using repeat cycles of oxygen inhalation. Enzyme-linked immunosorbent assay (ELISA) measured serum levels of vascular endothelial growth factor (VEGF), VEGF receptor-1 (VEGFR-1), and VEGFR-2. Histology of the retinal tissue included immunohistochemistry for the expression of Notch homolog-1 (Notch-1) and delta-like ligand 4 (DLL4). Retinal mRNA levels of DLL4, Notch-1, VEGF, VEGFR-1, and VEGFR-2 were evaluated with quantitative real-time polymerase chain reaction (qRT-PCR).

Results

The rat model of ROP showed increased serum levels of VEGF, VEGFR-1, and VEGFR-2 compared with the control group, which were decreased in the DAPT group. Histology of the retinal tissue in the model group showed degeneration of the retinal ganglion cells, and immunohistochemistry showed increased expression of Notch-1 and DLL4 compared with the control group and DAPT group. Retinal tissue in the model group had increased mRNA levels of DLL4, Notch-1, VEGF, VEGFR-1, and VEGFR-2 compared with the control group, and the DAPT group.

Conclusions

In a rat model, treatment with DAPT reduced the retinal changes associated with ROP with a mechanism that involved VEGF and its receptors through the DLL4/Notch-1 pathway.

Knockdown of dickkopf2 inhibits vascular endothelia growth factor expression through the Wnt/β-catenin signaling pathway in human retinal pigment epithelial cells under hypoxic conditions

Hypoxia has been demonstrated to be a proangiogenic factor that induces vascular endothelial growth factor (VEGF) in retinal pigment epithelial (RPE) cells. Dickkopf2 (DKK2), originally known as Wnt antagonist, has recently been demonstrated to have an important regulatory role in angiogenesis; however, the specific role of DKK2 in RPE cells is not known. In the present study, the effects of DKK2 on VEGF expression under hypoxic conditions were investigated, as well as the molecular mechanisms involved. The results demonstrated that the expression of DKK2 was markedly increased under hypoxic conditions compared with normoxic conditions. Knockdown of DKK2 markedly attenuated the CoCl₂-induced expression of hypoxia-inducible factor (HIF)-1α and VEGF in RPE cells. Furthermore, knockdown of DKK2 markedly inhibited the expression of β-catenin induced by hypoxia. In conclusion, the findings of the present study demonstrate that knockdown of DKK2 inhibits the hypoxia-induced production of VEGF by suppressing the activation of the Wnt/β-catenin signaling pathway.

CoCl2 increases the expression of hypoxic markers HIF-1α, VEGF and CXCR4 in breast cancer MCF-7 cells

The aim of the present study was to investigate the effect of a hypoxic environment on the biological behavior of breast cancer MCF-7 cells, using CoCl₂ to mimic the hypoxia model in breast cancer cells. Using 50, 100, 150 and 200 µM CoCl₂ as a hypoxic inducer, a hypoxic model was established in MCF-7 cells in vitro. MTT, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) and western blotting assays were performed to detect MCF-7 cell proliferation under hypoxic conditions and the expression of the hypoxic markers hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF) and C-X-C motif chemokine receptor 4 (CXCR4) mRNA and that of the associated proteins. The RT-qPCR results revealed that there were no obvious changes in the expression of HIF-1α mRNA; however, the expression of CXCR4 and VEGF mRNA increased significantly following treatment with different CoCl₂ concentrations (P<0.05). The results of western blotting identified that CoCl₂ significantly induced the expression of HIF-1α, CXCR4 and VEGF proteins (P<0.05). The MTT assay revealed that different concentrations of CoCl₂ inhibited the proliferation of MCF-7 cells. The TUNEL assay demonstrated that CoCl₂ was able to trigger apoptosis of MCF-7 cells. Therefore, the results of the present study identified that CoCl₂ is able to control MCF-7 cell proliferation and apoptosis, also increasing the expression of HIF-1α, CXCR4 and VEGF. The present study may aid the discovery of a novel method to prevent cell damage and decrease cell proliferation in order to prevent the occurrence and development of breast cancer.

RETRACTED: Protective effects of total flavonoids in Caragana against hypoxia/reoxygenation-induced injury in human brain microvascular endothelial cells

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. An Expression of Concern for this article was previously published while an investigation was conducted (see related editorial: https://doi.org/10.1016/j.biopha.2022.113812). This retraction notice supersedes the Expression of Concern published earlier. Concern was raised about the reliability of the Transwell assay images shown in Figure 4A, which appear to contain similar features to those found in other publications, as detailed here: https://pubpeer.com/publications/FE1B7461C358F48E6838BF1622C291; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. An additional suspected image duplication within Figure 5A was also identified. The journal requested the corresponding author comment on these concerns and provide the associated raw data. The authors did not respond to this request and therefore the Editor-in-Chief decided to retract the article.

E-Prostanoid 3 Receptor Mediates Sprouting Angiogenesis Through Suppression of the Protein Kinase A/β-Catenin/Notch Pathway

Objective—

Angiogenesis is a hallmark of embryonic development and various ischemic and inflammatory diseases. Prostaglandin E2 receptor subtype 3 (EP3) plays an important role in pathophysiologic angiogenesis; however, the precise mechanisms remain unknown. Here, we investigated the role of EP3 in zebra fish embryo and mouse retina angiogenesis and evaluated the underlying mechanisms.

Approach and Results—

The EP3 receptor was highly expressed in the vasculature in both zebra fish embryos and murine fetal retinas. Pharmacological inhibition or genetic deletion of EP3 significantly reduced vasculature formation in zebra fish embryos and mouse retinas. Further characterization revealed reduced filopodia extension of tip cells in embryonic retinas in EP3-deficient mice. EP3 deletion activated Notch activity by upregulation of delta-like ligand 4 expression in endothelial cells (ECs). Inhibition of Notch signaling rescued the angiogenic defects in EP3-deficient mouse retinas. Moreover, EP3 deficiency led to a significant increase in β-catenin phosphorylation at Ser675 and nuclear accumulation of β-catenin in ECs. Knockdown or inhibition of β-catenin restored the impaired sprouting angiogenesis resulting from EP3 deficiency in ECs. The EP3 receptor depressed protein kinase A activity in ECs by coupling to Gαi. Inhibition of protein kinase A activity significantly reduced Ser675 phosphorylation and nuclear translocation of β-catenin, abolished the increased delta-like ligand 4 expression, and subsequently restored the impaired angiogenic capacity of EP3-deficient ECs both in vitro and in vivo.

Conclusions—

Activation of the EP3 receptor facilitates sprouting angiogenesis through protein kinase A–dependent Notch signaling, suggesting that EP3 and its downstream pathways maybe potential therapeutic targets in the treatment of ischemic diseases.

The interplay between the cellular hypoxic response and Notch signaling

The ability to sense and adapt to low oxygen levels (hypoxia) is central for most organisms and cell types. At the center of this process is a molecular mechanism, the cellular hypoxic response, in which the hypoxia inducible factors (HIFs) are stabilized by hypoxia, allowing the HIF proteins to act as master transcriptional regulators to adjust the cell to a low oxygen environment. In recent years, it has become increasingly appreciated that the cellular hypoxic response does not always operate in splendid isolation, but intersects with signaling mechanisms such as Notch signaling, a key regulatory signaling mechanism operating in most cell types controlling stem cell maintenance and differentiation. In this review, which is dedicated to the memory of Lorenz Poellinger,¹ we discuss how the intersection between Notch and the cellular hypoxic response was discovered and our current understanding of the molecular basis for the cross-talk. We also provide examples of where Notch and hypoxia intersect in various physiological and disease contexts.

Vascular endothelial growth factor-A165b ameliorates outer-retinal barrier and vascular dysfunction in the diabetic retina

Diabetic retinopathy (DR) is one of the leading causes of blindness in the developed world. Characteristic features of DR are retinal neurodegeneration, pathological angiogenesis and breakdown of both the inner and outer retinal barriers of the retinal vasculature and retinal pigmented epithelial (RPE)–choroid respectively. Vascular endothelial growth factor (VEGF-A), a key regulator of angiogenesis and permeability, is the target of most pharmacological interventions of DR. VEGF-A can be alternatively spliced at exon 8 to form two families of isoforms, pro- and anti-angiogenic. VEGF-A₁₆₅a is the most abundant pro-angiogenic isoform, is pro-inflammatory and a potent inducer of permeability. VEGF-A₁₆₅b is anti-angiogenic, anti-inflammatory, cytoprotective and neuroprotective. In the diabetic eye, pro-angiogenic VEGF-A isoforms are up-regulated such that they overpower VEGF-A₁₆₅b. We hypothesized that this imbalance may contribute to increased breakdown of the retinal barriers and by redressing this imbalance, the pathological angiogenesis, fluid extravasation and retinal neurodegeneration could be ameliorated. VEGF-A₁₆₅b prevented VEGF-A₁₆₅a and hyperglycaemia-induced tight junction (TJ) breakdown and subsequent increase in solute flux in RPE cells. In streptozotocin (STZ)-induced diabetes, there was an increase in Evans Blue extravasation after both 1 and 8 weeks of diabetes, which was reduced upon intravitreal and systemic delivery of recombinant human (rh)VEGF-A₁₆₅b. Eight-week diabetic rats also showed an increase in retinal vessel density, which was prevented by VEGF-A₁₆₅b. These results show rhVEGF-A₁₆₅b reduces DR-associated blood–retina barrier (BRB) dysfunction, angiogenesis and neurodegeneration and may be a suitable therapeutic in treating DR.

Protein delivery to the back of the eye: barriers, carriers and stability of anti-VEGF proteins

Utilization of the full clinical potential of many novel therapeutic proteins designed for diseases affecting the posterior segment of the eye has often been limited because of their inherent instability and the difficulty in overcoming various ocular barriers. Intravitreal injection is currently the only approved mode of administration, although it is suboptimal because it is painful and has to be done every 1-2 months as a result of high protein clearance rates from the vitreous humor. In this review, we discuss the status of protein drug delivery to back of the eye in terms of novel protein drugs developed, physiological barriers encountered, strategies for carrier design to overcome these limitations, and protein stability. We focus on the most promising approaches as well as on current shortcomings.

Cnidium officinale extract and butylidenephthalide inhibits retinal neovascularization in vitro and in vivo

BACKGROUND

Retinal neovascularization, which is the pathological growth of new blood vessels, is associated with retinopathy of prematurity, neovascular age-related macular degeneration, diabetic retinopathy and retinal vein occlusion. In this study, we evaluated the effect of an extract of Cnidium officinale Makino (COE) and its bioactive compound, butylidenephthalide (BP), on the migration and tube formation of human umbilical vein endothelial cells (HUVECs), and on retinal pathogenic neovascularization in the oxygen-induced retinopathy (OIR) mouse model.

METHOD

The HUVECs were incubated with COE and BP (0.1-10 μg/ml). The mice were exposed to 75 % oxygen for 5 days starting on the 7(th) postnatal day (P7-P12). Then, the mice were returned to room air and intraperitoneally injected with COE (100 mg/kg) and BP (5 mg/kg) once per day for 5 days (P12-P16). On P17, we measured retinal neovascularization and analyzed the angiogenesis-related proteins expression using protein arrays.

RESULTS

COE and BP inhibit the HUVECs migration and the tube formation in a dose-dependent manner. In addition, COE significantly decreased retinal neovascularization in the OIR mice. COE reduced the expression levels of AREG, ANG, DLL4, Endostatin, IGFBP-2 and VEGF. Additionally, BP also inhibited the retinal neovascularization and down-regulated the expression of AREG, ANG, DLL4 and VEGF.

CONCLUSION

These results suggest that COE and BP exerts antiangiogenic effects on retinal neovascularization by inhibiting the expression of AREG, ANG, DLL4 and VEGF, indicating that antiangiogenic activities of COE may be in part due to its bioactive compound, BP.

Involvement of human chorionic gonadotropin in regulating vasculogenic mimicry and hypoxia-inducible factor-1α expression in ovarian cancer cells

BACKGROUND

Human chorionic gonadotropin (hCG) can play a crucial role in angiogenesis. In the present study, we focused on hCG to gain insight into its potential effects on vasculogenic mimicry (VM) in ovarian cancer cells.

METHODS

Ovarian cancer OVCAR-3 cells were incubated with different concentrations of recombinant hCG in 3-dimensional cultures. VM was identified by morphological observations and vascular endothelial cell marker detection in OVCAR-3 cells. Expression of hCG, hypoxia-inducible factor-1α (HIF-1α), and the endothelial cell markers CD31, VEGF, and factor VIII were detected by reverse transcription polymerase chain reaction and western blotting. The effect of hCG on endothelial cell-marker expression in ovarian cancer cells was further explored using small interfering RNA (siRNA) and plasmid-based approaches.

RESULTS

Incubation of OVCAR-3 cells with recombinant hCG induced vessel-like network formation, which was accompanied by significant elevation of vascular marker expression. Attenuation of hCG expression by siRNA in OVCAR-3 cells suppressed the expression of endothelial cell markers and HIF-1α by tumour cells. Overexpression of hCG in OVCAR-3 cells resulted in increased expression of endothelial cell markers and HIF-1α.

CONCLUSIONS

HCG was crucial for changing the phenotype of OVCAR-3 cells to endothelial-like cells. The effect of hCG induction on VM in ovarian cancer cells is potentially associated with HIF-1α.

Mining for genes related to choroidal neovascularization based on the shortest path algorithm and protein interaction information

BACKGROUND

Choroidal neovascularization (CNV) is a serious eye disease that may cause visual loss, especially for older people. Many factors have been proven to induce this disease including age, gender, obesity, and so on. However, until now, we have had limited knowledge on CNV's pathogenic mechanism. Discovering the genes that underlie this disease and performing extensive studies on them can help us to understand how CNV occurs and design effective treatments.

METHODS

In this study, we designed a computational method to identify novel CNV-related genes in a large protein network constructed using the protein-protein interaction information in STRING. The candidate genes were first extracted from the shortest paths connecting any two known CNV-related genes and then filtered by a permutation test and using knowledge of their linkages to known CNV-related genes.

RESULTS

A list of putative CNV-related candidate genes was accessed by our method. These genes are deemed to have strong relationships with CNV.

CONCLUSIONS

Extensive analyses of several of the putative genes such as ANK1, ITGA4, CD44 and others indicate that they are related to specific biological processes involved in CNV, implying they may be novel CNV-related genes.

GENERAL SIGNIFICANCE

The newfound putative CNV-related genes may provide new insights into CNV and help design more effective treatments. This article is part of a Special Issue entitled "System Genetics" Guest Editor: Dr. Yudong Cai and Dr. Tao Huang.

Clinical effects of integrated psychological nursing in patients undergoing liver transplantation

AIM: To assess the clinical effects of integrated psychological nursing in patients undergoing liver transplantation.

METHODS: Forty patients who underwent liver transplantation at our hospital from November 2013 to May 2014 were randomly divided into either an observation group or a control group, with 20 cases in each group. The observation group received integrated psychological treatment, and the control group received telephone follow-up, only once a week, that did not involve any psychological nursing. Before and after the intervention, the self-rating anxiety scale (SAS), self-rating depression scale (SDS) and quality of life scale were used to measure the mental health status, depression and quality of life, respectively.

RESULTS: The SDS and SAS scores before intervention had no statistically significant differences between the two groups (P > 0.05). After intervention, the depression and anxiety scores in the observation group (36.672 ± 7.532; 29.971 ± 9.421) were significantly lower than those in the control group (40.283 ± 7.883; 43.612 ± 6.453) (P < 0.05). Before nursing intervention, quality of life scores showed no significant difference between the two groups (P > 0.05). After intervention, the quality of life score in the observation group was significantly higher than that in the control group (P < 0.05).

CONCLUSION: Integrated psychological intervention can significantly improve the mental health status and quality of life in patients undergoing liver transplantation.

Zeaxanthin inhibits hypoxia-induced VEGF secretion by RPE cells through decreased protein levels of hypoxia-inducible factors-1α

Hypoxia is the most important stimulus leading to upregulation of VEGF in the retina and this is caused by accumulation of hypoxia-inducible factors-1α (HIF-1α) protein. The effects of zeaxanthin, a natural phytochemical, on the VEGF and HIF-1α expression in the primary culture of human retinal pigment epithelial (RPE) cells were studied. An in vitro RPE cell hypoxia model was established by placing cells under 1% oxygen pressure or by adding cobalt chloride (CoCl2) to the culture medium. RPE cells and conditioned media were collected from cultures treated with and without zeaxanthin under normoxic and hypoxic conditions. VEGF and HIF-1α protein and RNA levels were measured by ELISA kits and RT-PCR, respectively. Hypoxia caused a significant increase of VEGF expression and accumulation of HIF-1α in RPE cells. Zeaxanthin at 50-150 μM significantly inhibited the expression of VEGF and accumulation of HIF-1α protein caused by hypoxia but did not affect expression of VEGF and HIF-1α under normoxic conditions. This is the first report on the effect of zeaxanthin on VEGF and HIF-1α levels in cultured RPE cells and suggests that zeaxanthin may have potential value in the prevention and treatment of various retinal diseases associated with vascular leakage and neovascularization.

Endostar inhibits hypoxia-induced cell proliferation and migration via the hypoxia-inducible factor-1α/vascular endothelial growth factor pathway in vitro

Endostar, a recombinant human endostatin, is recognized as one of the most effective angiogenesis inhibitors. The angiogenesis inhibitory effects of Endostar suggest a possible beneficial role of Endostar in choroidal neovascularization (CNV), which is predominantly induced by hypoxia. In our previous study, it was reported that Endostar may inhibit the proliferation and migration of RF/6A choroid‑retinal endothelial cells. However, the inhibitory effect of Endostar on hypoxia‑induced cell proliferation and migration in RF/6A cells has not yet been elucidated. Therefore, the present study investigated the effect of Endostar on hypoxia‑induced cell proliferation and migration in RF/6A cells and the possible mechanisms underlying this effect. Under chemical hypoxia conditions, cell viability was increased to 114.9±10.1 and 123.6±9.6% in cells treated with 100 and 200 µm CoCl2, respectively, compared with the control (P<0.01). Pretreatment with 10‑100 µg/ml Endostar significantly inhibited CoCl2‑induced cell proliferation (P<0.05), and pre‑treatment with 10 µg/ml Endostar for 24, 48 and 96 h attenuated CoCl2‑promoted cell migration by 60.5, 48.3 and 39.6%, respectively, compared with the control (P<0.001). In addition, pretreatment with 10 µg/ml Endostar reversed the cell cycle arrest at S phase and the increased expression of hypoxia‑inducible factor‑1α (HIF‑1α) and vascular endothelial growth factor (VEGF) mRNA in RF/6A cells treated with 200 µM CoCl2. These data indicate that Endostar inhibited CoCl2‑induced hypoxic proliferation and migration, and limited cell cycle progression in vitro possibly through the HIF‑1α/VEGF pathway.

Expression and function of Delta-like ligand 4 in a rat model of retinopathy of prematurity

The Delta-like ligand 4/Notch signaling pathway was shown to participate in the process of retinal development and angiogenesis. However, the function of the Delta-like ligand 4/Notch signaling pathway in retinopathy of prematurity requires further study. Retinopathy of prematurity was induced in 5-day-old Sprague-Dawley rats exposed to hyperoxia for 7 days, and then returned to room air. Reverse transcription-PCR and western blot revealed that Delta-like ligand 4 levels decreased at postnatal day 12 and increased at postnatal day 17 in retinopathy of prematurity rats. Flat-mounted adenosine diphosphatase stained retina and hematoxylin-eosin stained retinal tissue slices showed that the clock hour scores and the nuclei counts in retinopathy of prematurity rats were significantly different compared to normal control rats. After retinopathy of prematurity rats were intravitreally injected with Delta-like ligand 4 monoclonal antibody to inhibit the Delta-like ligand 4/Notch signaling pathway, there was a significant increase in the severity of retinal neovascularization (clock hours) in the intravitreally injected eyes. The nuclei count was highly correlated with the clock hour score. These results suggest that Delta-like ligand 4/Notch signaling plays an essential role in the process of physiological and pathological angiogenesis in the retina.

Preliminary study on retinal vascular and oxygen-related changes after long-term silicone oil and foldable capsular vitreous body tamponade

Silicone oil has been the only long-term vitreous substitute used in the treatment of retinal detachment since 1962 by Cibis. Nevertheless, its effects on retinal vascular morphology and oxygen supply to the retina are ambiguous in current research. We previously invented a foldable capsular vitreous body (FCVB) to use as a new vitreous substitute in the treatment of severe retinal detachment, but its effects on the retinal vessel were unknown. Therefore, in this study, a standard three-port pars plana vitrectomy (PPV) was performed on the right eye of each rabbit and then silicone oil and FCVB were injected into the vitreous cavity as vitreous substitutes. After 180 days of retention, the retinal vascular morphology did not display any distinct abnormalities, and hypoxia-induced factor-1alpha (HIF-1α) and vascular endothelial growth factor (VEGF) did not vary markedly during the observation period in silicone oil tamponade- and FCVB-implanted eyes. This study may suggest that silicone oil and FCVB tamponade in rabbit eyes did not cause retinal vascular pathologic changes or retinal hypoxia for 180 days.

Neuroprotective effect of ischemic preconditioning in focal cerebral infarction: relationship with upregulation of vascular endothelial growth factor

Neuroprotection by ischemic preconditioning has been confirmed by many studies, but the precise mechanism remains unclear. In the present study, we performed cerebral ischemic preconditioning in rats by simulating a transient ischemic attack twice (each a 20-minute occlusion of the middle cerebral artery) before inducing focal cerebral infarction (2 hour occlusion-reperfusion in the same artery). We also explored the mechanism underlying the neuroprotective effect of ischemic preconditioning. Seven days after occlusion-reperfusion, tetrazolium chloride staining and immunohistochemistry revealed that the infarct volume was significantly smaller in the group that underwent preconditioning than in the model group. Furthermore, vascular endothelial growth factor immunoreactivity was considerably greater in the hippocampal CA3 region of preconditioned rats than model rats. Our results suggest that the protective effects of ischemic preconditioning on focal cerebral infarction are associated with upregulation of vascular endothelial growth factor.

Hyperglycemia promotes vasculogenesis in choroidal neovascularization in diabetic mice by stimulating VEGF and SDF-1 expression in retinal pigment epithelial cells

To investigate the influence of hyperglycemia on the severity of choroidal neovascularization (CNV) in diabetic mice, especially the involvement of bone marrow-derived cells (BMCs) and underlying molecular mechanisms. The mice were randomly divided into control group, diabetes group and diabetes treated with insulin group, which were laser treated to induce CNV. The CNV severity was evaluated by fundus fluorescein angiography, HE staining and choroidal flatmount. The BMCs recruitment and differentiation in CNV were examined in GFP chimeric mice by choroidal flatmount and immunofluorescence. The bone marrow-derived mesenchymal stem cells (BMSCs) recruitment and migration were tested in vivo and in vitro. VEGF and SDF-1 production in vivo and in vitro were tested by realtime PCR and ELISA. The CNV severity and expression of VEGF and SDF-1 were enhanced in DM mice compared with control mice and that insulin treatment decreased CNV severity in DM mice. The DM mice demonstrated more BMCs and bone marrow-derived mesenchymal stem cells (BMSCs) recruited and incorporated into CNV, increased ratio of BMCs expressing endothelial cell marker or macrophage marker, and up-regulated expression of VEGF and SDF-1 in CNV. Human BMSCs migration and expression of VEGF and SDF-1 in retinal pigment epithelial (RPE) cells increased when cultured under high glucose. This study suggested that hyperglycemia enhanced the expression of VEGF and SDF-1 in RPE cells, and promoted recruitment and incorporation of BMCs and affected differentiation of BMCs in CNV, which led to more severe CNV in diabetic mice.

Notch γ-secretase inhibitor dibenzazepine attenuates angiotensin II-induced abdominal aortic aneurysm in ApoE knockout mice by multiple mechanisms

Abdominal aortic aneurysm (AAA) is a life-threatening aortic disease in the elderly. Activation of Notch1 pathway plays a critical role in the development of AAA, but the underlying mechanisms remain poorly understood. In the present study, we explored the mechanisms by which Notch1 activation regulates angiotensin II (Ang II)-induced AAA formation and evaluated the therapeutic potential of a new Notch γ-secretase inhibitor, dibenzazepine (DBZ), for the treatment of AAA. Apolipoprotein E knockout (Apo E(-/-)) mice infused for 4 weeks with Ang II (1000 ng/kg/min, IP) using osmotic mini-pumps were received an intraperitoneal injection of either vehicle or 1 mg/kg/d DBZ. Notch1 signaling was activated in AAA tissue from both Ang II-infused Apo E(-/-) mice and human undergoing AAA repair in vivo, with increased expression of Notch intracellular domain (NICD) and its target gene Hes1, and this effect was effectively blocked by DBZ. Moreover, infusion of Ang II markedly increased the incidence and severity of AAA in Apo E(-/-) mice. In contrast, inhibition of Notch activation by DBZ prevented AAA formation in vivo. Furthermore, DBZ markedly prevented Ang II-stimulated accumulation of macrophages and CD4(+) T cells, and ERK-mediated angiogenesis, simultaneously reversed Th2 response, in vivo. In conclusion, these findings provide new insight into the multiple mechanisms of Notch signaling involved in AAA formation and suggest that γ-secretase inhibitor DBZ might be a novel therapeutic drug for treating AAAS.

Exploring leptin antagonism in ophthalmic cell models

Background

Emerging evidence suggests that angiogenic and pro-inflammatory cytokine leptin might be implicated in ocular neovascularization. However, the potential of inhibiting leptin function in ophthalmic cells has never been explored. Here we assessed mitogenic, angiogenic, and signaling leptin activities in retinal and corneal endothelial cells and examined the capability of a specific leptin receptor (ObR) antagonist, Allo-aca, to inhibit these functions.

Methods and Results

The experiments were carried out in monkey retinal (RF/6A) and bovine corneal (BCE) endothelial cells. Leptin at 50-250 ng/mL stimulated the growth of both cell lines in a dose-dependent manner. The maximal mitogenic response (35±7 and 27±3% in RF6A and BCE cells, respectively) was noted at 24 h of 250 ng/mL leptin treatments. Leptin-dependent proliferation was reduced to base levels with 10 and 100 nM Allo-aca in BCE and RF6A cells, respectively. In both cell lines, leptin promoted angiogenic responses, with the maximal increase in tube formation (163±10 and 133±8% in RF6A and BCE cultures, respectively) observed under a 250 ng/mL leptin treatment for 3 h. Furthermore, in both cell lines 250 ng/mL leptin modulated the activity or expression of several signaling molecules involved in proliferation, inflammatory activity and angiogenesis, such as STAT3, Akt, and ERK1/2, COX2, and NFκB. In both cell lines, leptin-induced angiogenic and signaling responses were significantly inhibited with 100 nM Allo-aca. We also found that leptin increased its own mRNA and protein expression in both cell lines, and this autocrine effect was abolished by 100-250 nM Allo-aca.

Conclusions

Our data provide new insights into the role of leptin in ocular endothelial cells and represent the first original report on targeting ObR in ophthalmic cell models.

Decorin inhibits angiogenic potential of choroid-retinal endothelial cells by downregulating hypoxia-induced Met, Rac1, HIF-1α and VEGF expression in cocultured retinal pigment epithelial cells

Choroidal neovascularization (CNV) is one of the most common causes of severe vision loss. Decorin, a multiple receptor tyrosine kinase inhibitor, has been recently shown to play an important regulatory role in angiogenic response. This study aims to investigate whether the overexpression of decorin in retinal pigment epithelial (RPE) cells under hypoxia alters the in vitro angiogenic ability of cocultured choroid-retinal endothelial cells and to explore the possible mechanisms involved. Human RPE cells (ARPE-19) were subjected to hypoxia with or without decorin pretreatment, and RNA interference technique was used to knock down the Met gene in ARPE-19 cells. Cell viability was determined using the Cell Counting Kit-8 assay. Expression of Met, Rac1 and hypoxia-inducible factor-1 alpha (HIF-1α) was evaluated by western blot and quantitative real-time polymerase chain reaction (qRT-PCR). Vascular endothelial growth factor (VEGF) expression was evaluated by enzyme-linked immunosorbent assay (ELISA) and qRT-PCR. We then constructed a recombinant lentiviral vector carrying the decorin gene to transduce ARPE-19 cells. The overexpression of decorin in transduced RPE cells was confirmed by qRT-PCR and western blot. The transduced RPE cells were then cocultured with rhesus macaque choroid-retinal endothelial cells (RF/6A) in a transwell coculture system to observe the effects of decorin overexpression in ARPE-19 cells on the proliferation, migration and tube formation of RF/6A cells. In response to hypoxia, the VEGF concentrations in the culture supernatants increased greatly at 24 and 48 h, and this effect was inhibited significantly and nearly equally in the presence of 50-200 nM decorin. Decorin pretreatment before hypoxia exposure effectively reduced the hypoxia-induced expression of Met, Rac1, HIF-1α and VEGF in ARPE-19 cells. Transfection of small interfering RNA against Met to ARPE-19 cells also resulted in significant downregulation of Rac1, HIF-1α and VEGF under hypoxia, and this effect was similar to that noted with decorin pretreatment alone or with their combination. Results from the coculture system showed that the overexpression of decorin in ARPE-19 cells significantly inhibited the proliferation, migration and tube formation of RF/6A cells. These results indicate that Met pathway activation plays an important role in the upregulation of VEGF in RPE cells under hypoxia. Decorin may interfere with angiogenesis by downregulating hypoxia-induced Met, Rac1, HIF-1α and VEGF expression in RPE cells, which suggests a potential strategy for the inhibition of CNV.

Epigallocatechin-3-gallate inhibits IGF-I-stimulated lung cancer angiogenesis through downregulation of HIF-1α and VEGF expression

BACKGROUND/AIMS

Numerous studies have shown that epigallocatechin-3-gallate (EGCG), a polyphenol component extracted from green tea, can inhibit the growth and induce apoptosis of various types of human tumor cells. In this study, we evaluated the inhibitory effects of EGCG on the proangiogenic capabilities of A549 cells.

METHODS

A549 cells starved in serum-free culture medium for 24 h were pretreated with EGCG at various concentrations (0, 10, 25, 50, and 100 μmol/l) for 1 h, followed by the addition of insulin-like growth factor-I (IGF-I) at the final concentration of 40 ng/ml and continued culturing for an additional 16 h. The in vitro angiogenesis analyzing test kit with ECMatrix™ gel was used to detect the formation of capillary tube-like structures. The mRNA expression of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) was determined by real-time PCR. The protein expression of HIF-1α and VEGF was detected by Western blotting and ELISA, respectively.

RESULTS

EGCG significantly inhibited the formation of capillary tube-like structures on the surface of ECMatrix induced by IGF-I both in vitro and in vivo and reduced the level of hemoglobin in Matrigel plugs. In addition, EGCG was shown to significantly inhibit the IGF-I-induced upregulation of HIF-1α protein expression. Meanwhile, EGCG at the concentration of 25 and 100 μmol/l exhibited obvious inhibitory effects on IGF-I-induced VEGF expression (p < 0.01).

CONCLUSION

Our results suggest that EGCG has potent inhibitory effects on tumor angiogenesis induced by IGF-I in human non-small cell lung cancer cells, which may possibly contribute to the downregulation of HIF-1α and VEGF expression.

Association of Dll4/notch and HIF-1a -VEGF signaling in the angiogenesis of missed abortion

Background

Dll4/Notch and HIF-1a-VEGF have been shown to play an important role during angiogenesis, but there are no data about their roles and association in missed abortion. In this study, we investigated the association of Dll4/Notch and HIF-1a-VEGF signaling in missed abortion.

Methods

Women with missed abortion (n = 27) and healthy controls (n = 26) were included in the study. Real-time Reverse Transcription-PCR Analyses (RT-PCR) was used to analyze the mRNA levels of Dll4/Notch and HIF-1a-VEGF signaling molecules. The protein level for Dll4 was measured by immunohistochemistry.

Results

Compared with induced abortion, the expression of VEGF was statistically reduced while the level of VEGFR1 and Notch1 was significantly up-regulated in missed abortion. Though other molecules (VEGFR2 and Dll4) were marginally higher in missed abortion, no statistical difference was observed. The expression of HIF-1a was significantly up-regulated, and close negatively correlated with VEGF in missed abortion. Both in induced abortion and missed abortion, Dll4 was positively correlated with Notch1.

Conclusions

The early pregnancy is in a hypoxic environment, this may encourage the angiogenesis, but severe hypoxic may inhibit the angiogenesis. Aberrant Dll4/Notch and HIF-1a-VEGF signaling may have a role in missed abortion.

Dietary wolfberry upregulates carotenoid metabolic genes and enhances mitochondrial biogenesis in the retina of db/db diabetic mice

SCOPE

Our aim was to investigate whether dietary wolfberry altered carotenoid metabolic gene expression and enhanced mitochondrial biogenesis in the retina of diabetic mice.

METHODS AND RESULTS

Six-week-old male db/db and wild-type mice were fed the control or wolfberry diets for 8 weeks. At study termination, liver and retinal tissues were collected for analysis by transmission electron microscopy, real-time PCR, immunoprecipitation, Western blot, and HPLC. Wolfberry elevated zeaxanthin and lutein levels in the liver and retinal tissues and stimulated expression of retinal scavenger receptor class B type I, glutathione S-transferase Pi 1, and β,β-carotene 9',10'-oxygenase 2, and induced activation and nuclear enrichment of retinal AMP-activated protein kinase α2 (AMPK-α2). Furthermore, wolfberry attenuated hypoxia and mitochondrial stress as demonstrated by declined expression of hypoxia-inducible factor-1-α, vascular endothelial growth factor, and heat shock protein 60. Wolfberry enhanced retinal mitochondrial biogenesis in diabetic retinas as demonstrated by reversed mitochondrial dispersion in the retinal pigment epithelium, increased mitochondrial copy number, elevated citrate synthase activity, and upregulated expression of peroxisome proliferator-activated receptor γ co-activator 1α, nuclear respiratory factor 1, and mitochondrial transcription factor A.

CONCLUSION

Consumption of dietary wolfberry could be beneficial to retinoprotection through reversal of mitochondrial function in diabetic mice.

Hypoxia-induced arterial differentiation requires adrenomedullin and notch signaling

Hypoxia (low oxygen) and Notch signaling are 2 important regulators of vascular development, but how they interact in controlling the choice between arterial and venous fates for endothelial cells during vasculogenesis is less well understood. In this report, we show that hypoxia and Notch signaling intersect in promotion of arterial differentiation. Hypoxia upregulated expression of the Notch ligand Dll4 and increased Notch signaling in a process requiring the vasoactive hormone adrenomedullin. Notch signaling also upregulated Dll4 expression, leading to a positive feedback loop sustaining Dll4 expression and Notch signaling. In addition, hypoxia-mediated upregulation of the arterial marker genes Depp, connexin40 (Gja5), Cxcr4, and Hey1 required Notch signaling. In conclusion, the data reveal an intricate interaction between hypoxia and Notch signaling in the control of endothelial cell differentiation, including a hypoxia/adrenomedullin/Dll4 axis that initiates Notch signaling and a requirement for Notch signaling to effectuate hypoxia-mediated induction of the arterial differentiation program.

Notch signaling change in pulmonary vascular remodeling in rats with pulmonary hypertension and its implication for therapeutic intervention

Pulmonary hypertension (PH) is a fatal disease that lacks an effective therapy. Notch signaling pathway plays a crucial role in the angiogenesis and vascular remodeling. However, its roles in vascular remodeling in PH have not been well studied. In the current study, using hypoxia-induced PH model in rat, we examined the expression of Notch and its downstream factors. Then, we used vessel strip culture system and γ-secretase inhibitor DAPT, a Notch signaling inhibitor to determine the effect of Notch signaling in vascular remodeling and its potential therapeutic value. Our results indicated that Notch 1–4 were detected in the lung tissue with variable levels in different cell types such as smooth muscle cells and endothelial cells of pulmonary artery, bronchia, and alveoli. In addition, following the PH induction, all of Notch1, Notch3, Notch4 receptor, and downstream factor, HERP1 in pulmonary arteries, mRNA expressions were increased with a peak at 1–2 weeks. Furthermore, the vessel wall thickness from rats with hypoxia treatment increased after cultured for 8 days, which could be decreased approximately 30% by DAPT, accompanied with significant increase of expression level of apoptotic factors (caspase-3 and Bax) and transformation of vascular smooth muscle cell (VSMC) phenotype from synthetic towards contractile. In conclusion, the current study suggested Notch pathway plays an important role in pulmonary vascular remodeling in PH and targeting Notch signaling pathway could be a valuable approach to design new therapy for PH.

In-vivo investigation of laser-induced choroidal neovascularization in rat using spectral-domain optical coherence tomography (SD-OCT)

PURPOSE

This study investigated the in-vivo formation process of laser-induced choroidal neovascularization (CNV) in rat using high-resolution spectral-domain optical coherence tomography (SD-OCT), and compared the results to histological methods.

METHODS

Brown Norway rats (n = 60, 6-8 weeks of age) received 532-nm diode laser photocoagulation. SD-OCT and fluorescein angiography (FA) were performed in vivo 2, 5, 7, 14, and 21 days post-laser application. Haematoxylin and eosin (H&E) staining and immunohistochemistry for CD31, phosphorylated vascular endothelial factor receptor 2 (pVEGFR2) were conducted at each time point to observe the CNV in vitro. Choroidal flatmount preparations were observed using a confocal laser scanning microscope (CLSM) and a scanning electron microscope (SEM).

RESULTS

SD-OCT monitored the longitudinal morphological changes of laser-induced CNV. CNV reached its maximal size on day 7, and began a gradual reduction on day 14. FA revealed similar dynamic changes in leakage. CNV thickness, as assessed by SD-OCT, was consistent with H&E-stained sections at each time point. CLSM and SEM revealed the details of the fibrovascular membrane. CD31 and pVEGFR2 expression supported the results of SD-OCT and histology.

CONCLUSIONS

SD-OCT was a convenient and reliable tool for the imaging of the CNV formation process and quantification of the lesion size in vivo.