Differential roles of vascular endothelial growth factor receptor-1 and receptor-2 in angiogenesis

Effects of Hyperglycemia on Angiogenesis in Human Placental Endothelial Cells

The placenta is a temporary organ that provides communication between the mother and fetus. Maternal diabetes and abnormal placental angiogenesis may be linked. We investigated the angiogenesis mechanism resulting from VEGF and glucose stimulation in PECs obtained from human term placenta. Immunohistochemistry was performed to characterize PECs obtained from human term placenta. D-glucose was added to the medium containing PECs to establish normoglycemic and hyperglycemic conditions. The expression levels of VEGF, VEGFR-1 and VEGFR-2 genes and proteins in PECs from the control and experimental groups were analyzed by RT-PCR and Western blotting, respectively. With 48-hours incubation, gene expressions increased due to hyperglycemia, while protein levels increased due to the combined effect of VEGF and hyperglycemia. While VEGFR-2 gene expression and protein amounts increased in 24-hours due to the combined effect of VEGF and hyperglycemia, the effect of VEGF stimulation and glucose level on VEGFR-2 decreased in 48-hour incubation with time. VEGF, VEGFR-1 and VEGFR-2 genes and proteins were affected by hyperglycemic conditions in PECs. Hyperglycemia occurring in various conditions such as gestational diabetes mellitus and diabetes mellitus may affect VEGF, VEGFR-1 and VEGFR-2 genes and proteins of PECs derived from human term placenta.

Chemotherapy in pediatric brain tumor and the challenge of the blood-brain barrier

BACKGROUND

Pediatric brain tumors (PBT) stand as the leading cause of cancer-related deaths in children. Chemoradiation protocols have improved survival rates, even for non-resectable tumors. Nonetheless, radiation therapy carries the risk of numerous adverse effects that can have long-lasting, detrimental effects on the quality of life for survivors. The pursuit of chemotherapeutics that could obviate the need for radiotherapy remains ongoing. Several anti-tumor agents, including sunitinib, valproic acid, carboplatin, and panobinostat, have shown effectiveness in various malignancies but have not proven effective in treating PBT. The presence of the blood-brain barrier (BBB) plays a pivotal role in maintaining suboptimal concentrations of anti-cancer drugs in the central nervous system (CNS). Ongoing research aims to modulate the integrity of the BBB to attain clinically effective drug concentrations in the CNS. However, current findings on the interaction of exogenous chemical agents with the BBB remain limited and do not provide a comprehensive explanation for the ineffectiveness of established anti-cancer drugs in PBT.

METHODS

We conducted our search for chemotherapeutic agents associated with the blood-brain barrier (BBB) using the following keywords: Chemotherapy in Cancer, Chemotherapy in Brain Cancer, Chemotherapy in PBT, BBB Inhibition of Drugs into CNS, Suboptimal Concentration of CNS Drugs, PBT Drugs and BBB, and Potential PBT Drugs. We reviewed each relevant article before compiling the information in our manuscript. For the generation of figures, we utilized BioRender software.

FOCUS

We focused our article search on chemical agents for PBT and subsequently investigated the role of the BBB in this context. Our search criteria included clinical trials, both randomized and non-randomized studies, preclinical research, review articles, and research papers.

FINDING

Our research suggests that, despite the availability of potent chemotherapeutic agents for several types of cancer, the effectiveness of these chemical agents in treating PBT has not been comprehensively explored. Additionally, there is a scarcity of studies examining the role of the BBB in the suboptimal outcomes of PBT treatment, despite the effectiveness of these drugs for other types of tumors.

Chemerin affects the expression of angiogenesis-related factors in the porcine endometrium during early pregnancy and the oestrous cycle: an in vitro study

CONTEXT

The appropriate course of angiogenesis in the endometrium is crucial for pregnancy establishment and maintenance. Very little is known about the factors linking vessel formation and immune system functioning.

AIMS

We hypothesised that chemerin, an adipokine known for its involvement in the regulation of energy balance and immunological functions, may act as a potent regulator of endometrial angiogenesis during early pregnancy in pigs.

METHODS

Porcine endometrial tissue explants were obtained from pregnant pigs on days 10-11, 12-13, 15-16 and 27-28, and on days 10-12 of the oestrous cycle. The explants were in vitro cultured for 24h in the presence of chemerin (100, 200ng/mL) or in medium alone (control). We evaluated the in vitro effect of chemerin on the secretion of vascular endothelial growth factors A-D (VEGF-A-D), placental growth factor (PlGF), basic fibroblast growth factor (bFGF) and angiopoietin 1 and 2 (ANG-1, ANG-2) with the ELISA method. The protein abundance of angiogenesis-related factor receptors, VEGF receptors 1-3 (VEGFR1-3), FGF receptors 1 and 2 (FGFR1-2) and ANG receptor (TIE2) was evaluated with the Western blot (WB) method. We also analysed the influence of chemerin on the phosphorylation of AMPK using WB.

KEY RESULTS

We found that in the studied endometrial samples, chemerin up-regulated the secretion of VEGF-A, VEGF-B and PlGF, and protein expression of VEGFR3. The adipokine caused a decrease in VEGF-C, VEGF-D and ANG-1 release. Chemerin effect on bFGF and ANG-2 secretion, and protein content of VEGFR1, VEGFR2, FGFR1, FGFR2 and TIE2 were dependent on the stage of pregnancy. Chemerin was found to down-regulate AMPK phosphorylation.

CONCLUSIONS

The obtained in vitro results suggest that chemerin could be an important factor in the early pregnant uterus by its influence on angiogenic factors' secretion and signalling.

IMPLICATIONS

The obtained results on the role of chemerin in the process of endometrial angiogenesis may, in the long term perspective, contribute to the elaboration of more effective methods of modifying reproductive processes and maintaining energy homeostasis in farm animals.

Endothelial cell plasticity in kidney fibrosis and disease

Renal endothelial cells demonstrate an impressive remodeling potential during angiogenic sprouting, vessel repair or while transitioning into mesenchymal cells. These different processes may play important roles in both renal disease progression or regeneration while underlying signaling pathways of different endothelial cell plasticity routes partly overlap. Angiogenesis contributes to wound healing after kidney injury and pharmaceutical modulation of angiogenesis may home a great therapeutic potential. Yet, it is not clear whether any differentiated endothelial cell can proliferate or whether regenerative processes are largely controlled by resident or circulating endothelial progenitor cells. In the glomerular compartment for example, a distinct endothelial progenitor cell population may remodel the glomerular endothelium after injury. Endothelial-to-mesenchymal transition (EndoMT) in the kidney is vastly documented and often associated with endothelial dysfunction, fibrosis, and kidney disease progression. Especially the role of EndoMT in renal fibrosis is controversial. Studies on EndoMT in vivo determined possible conclusions on the pathophysiological role of EndoMT in the kidney, but whether endothelial cells really contribute to kidney fibrosis and if not what other cellular and functional outcomes derive from EndoMT in kidney disease is unclear. Sequencing data, however, suggest no participation of endothelial cells in extracellular matrix deposition. Thus, more in-depth classification of cellular markers and the fate of EndoMT cells in the kidney is needed. In this review, we describe different signaling pathways of endothelial plasticity, outline methodological approaches and evidence for functional and structural implications of angiogenesis and EndoMT in the kidney, and eventually discuss controversial aspects in the literature.

PB101, a VEGF- and PlGF-targeting decoy protein, enhances antitumor immunity and suppresses tumor progression and metastasis

Antiangiogenic therapy is a recognized method for countering the immunosuppressive tumor microenvironment (TME) and improving anti-tumor immunity. PB101 is a glycosylated decoy receptor that binds to VEGF-A and PlGF with high affinity, based on the VEGFR1 backbone. Here, we elucidated PB101-induced remodeling of tumor angiogenesis and immunity, which enhances anti-PD-L1 immune checkpoint blockade. PB101 inhibited tumor growth by suppressing angiogenesis and enhancing CD8+ T cell infiltration into the tumors. PB101 induced robust reprogramming of antitumor immunity and activates intratumoral CD8+ T cells. Anti-tumor efficacy of PB101 is mostly dependent on CD8+ T cells and IFN-γ. PB101 reprograms tumor immunity in a manner distinct from that of the conventional VEGF decoy receptor, VEGF-trap. With its potent immune-modulating capability, PB101 synergizes with an anti-PD-L1, triggering strengthened antitumor immunity. Combining PB101 and anti-PD-L1 could establish durable protective immunity against tumor recurrence and metastasis. The findings of this study offer scientific rationales for further clinical development of PB101, particularly when used in combination with immune checkpoint inhibitors, as a potential treatment for advanced cancers.

Giant cavernous hemangioma of the liver with satellite nodules: Aspects on tumour/tissue interface: A case report

BACKGROUND

Giant hepatic cavernous hemangioma with multiple satellite nodules is a rare subtype of hepatic cavernous hemangioma, the most common vascular liver tumor. We report on a tumor with unusual histologic features: (1) Finger-like infiltration pattern; (2) lack of encapsulation; (3) blurred tumor/liver interface; and (4) massive satellitosis-referring to the article “Hepatic cavernous hemangioma: underrecognized associated histologic features”.

CASE SUMMARY

A 60-year-old man presented with increasing uncharacteristic abdominal discomfort and mildly elevated blood parameters of acute inflammation. Imaging revealed an unclear, giant liver tumor of the left liver lobe. A massive vascular tumor with extensive satellitosis broadly infiltrating the adjacent liver parenchyma was resected via hemihepatectomy of segments II/III. Histopathological diagnosis was giant hepatic cavernous hemangioma with multiple satellite nodules, featuring unusual characteristics hardly portrayed in the literature. Retrospectively, this particular morphology can explain the difficult pre- and perioperative diagnosis of a vascular liver tumor that is usually readily identifiable by modern imaging methods.

CONCLUSION

This case emphasizes the exact histological workup of tumor and tumor-induced parenchyma changes in radiologically unclassifiable liver tumors.

Molecular Ultrasound Imaging Depicts the Modulation of Tumor Angiogenesis by Acetylsalicylic Acid

Acetylsalicylic acid (ASA) is a well-established drug for heart attack and stroke prophylaxis. Furthermore, numerous studies have reported an anti-carcinogenic effect, but its exact mechanism is still unknown. Here, we applied VEGFR-2-targeted molecular ultrasound to explore a potential inhibitory effect of ASA on tumor angiogenesis in vivo. Daily ASA or placebo therapy was performed in a 4T1 tumor mouse model. During therapy, ultrasound scans were performed using nonspecific microbubbles (CEUS) to determine the relative intratumoral blood volume (rBV) and VEGFR-2-targeted microbubbles to assess angiogenesis. Finally, vessel density and VEGFR-2 expression were assessed histologically. CEUS indicated a decreasing rBV in both groups over time. VEGFR-2 expression increased in both groups up to Day 7. Towards Day 11, the binding of VEGFR-2-specific microbubbles further increased in controls, but significantly (p = 0.0015) decreased under ASA therapy (2.24 ± 0.46 au vs. 0.54 ± 0.55 au). Immunofluorescence showed a tendency towards lower vessel density under ASA and confirmed the result of molecular ultrasound. Molecular US demonstrated an inhibitory effect of ASA on VEGFR-2 expression accompanied by a tendency towards lower vessel density. Thus, this study suggests the inhibition of angiogenesis via VEGFR-2 downregulation as one of the anti-tumor effects of ASA.

Candidate Angiogenesis-Related Biomarkers in Patients with Laryngeal Carcinoma (AngLaC): A Prospective Cohort Study

OBJECTIVE

Angiogenesis is indeed a vital process in the progression of carcinomas, including that of larynx. Therefore, this study (AngLaC) aimed to identify candidate angiogenesis-related biomarkers in laryngeal carcinoma patients.

STUDY DESIGN

Prospective controlled cohort study.

SETTING

Tertiary referral center.

METHODS

In silico analyses of angiogenesis-related genes in laryngeal carcinoma were performed to determine candidate biomarkers. Serum levels of candidate biomarkers were determined via enzyme-linked immunosorbent assay in laryngeal carcinoma patients as well as in an age and gender-matched control group. The associations of the biomarkers with clinical parameters were investigated.

RESULTS

The study included 60 laryngeal carcinoma patients and 20 healthy controls. The serum levels of osteopontin, IGFBP-3, VEGF, sVEGFR-1, and VEGFR-2 were significantly higher in the patient group (p < .001, p ≤ .001, p < .001, p < .01, p < .01, respectively). High osteopontin and sVEGFR-1 levels were associated with locoregional-recurrence (p = .024, p = .016, respectively). IGFBP-3 had the highest diagnostic sensitivity (81.4%) and specificity (80%) among the molecules that were investigated (p < .001). High sVEGFR-1 and low VEGFR-2 levels were associated with poor overall-survival (p = .037, p = .027, respectively). High osteopontin and sVEGFR-1 levels were associated with poor disease-specific survival rates (p = .035, p = .018, respectively).

CONCLUSION

High serum levels of sVEGFR-1 and osteopontin as well as low serum levels of VEGFR-2 proved to be poor prognostic in terms of survival in laryngeal carcinoma. VEGF, sVEGFR1, VEGFR2, IGFBP-3, and osteopontin levels were found to be significantly increased in larynx cancer patients compared to the normal population. Further studies on osteopontin and sVEGFR-1 are required in order to determine their associations with recurrence.

Insights into the immunomodulatory regulation of matrix metalloproteinase at the maternal-fetal interface during early pregnancy and pregnancy-related diseases

Trophoblast immune cell interactions are central events in the immune microenvironment at the maternal-fetal interface. Their abnormalities are potential causes of various pregnancy complications, including pre-eclampsia and recurrent spontaneous abortion. Matrix metalloproteinase (MMP) is highly homologous, zinc(II)-containing metalloproteinase involved in altered uterine hemodynamics, closely associated with uterine vascular remodeling. However, the interactions between MMP and the immune microenvironment remain unclear. Here we discuss the key roles and potential interplay of MMP with the immune microenvironment in the embryo implantation process and pregnancy-related diseases, which may contribute to understanding the establishment and maintenance of normal pregnancy and providing new therapeutic strategies. Recent studies have shown that several tissue inhibitors of metalloproteinases (TIMPs) effectively prevent invasive vascular disease by modulating the activity of MMP. We summarize the main findings of these studies and suggest the possibility of TIMPs as emerging biomarkers and potential therapeutic targets for a range of complications induced by abnormalities in the immune microenvironment at the maternal-fetal interface. MMP and TIMPs are promising targets for developing new immunotherapies to treat pregnancy-related diseases caused by immune imbalance.

Analysis of mRNA Subcellular Distribution in Collective Cell Migration

The movement of groups of cells by collective cell migration requires division of labor between group members. Therefore, distinct cell identities, unique cell behaviors, and specific cellular roles are acquired by cells undergoing collective movement. A key driving force behind the acquisition of discrete cell states is the precise control of where, when, and how genes are expressed, both at the subcellular and supracellular level. Unraveling the mechanisms underpinning the spatiotemporal control of gene expression in collective cell migration requires not only suitable experimental models but also high-resolution imaging of messenger RNA and protein localization during this process. In recent times, the highly stereotyped growth of new blood vessels by sprouting angiogenesis has become a paradigm for understanding collective cell migration, and consequently this has led to the development of numerous user-friendly in vitro models of angiogenesis. In parallel, single-molecule fluorescent in situ hybridization (smFISH) has come to the fore as a powerful technique that allows quantification of both RNA number and RNA spatial distribution in cells and tissues. Moreover, smFISH can be combined with immunofluorescence to understand the precise interrelationship between RNA and protein distribution. Here, we describe methods for use of smFISH and immunofluorescence microscopy in in vitro angiogenesis models to enable the investigation of RNA and protein expression and localization during endothelial collective cell migration.

VEGF-targeting drugs for the treatment of retinal neovascularization in diabetic retinopathy

Diabetic retinopathy (DR) is the most common microangiopathic complication of diabetes mellitus, representing a major cause of visual impairment in developed countries. Proliferative DR (PDR) represents the last stage of this extremely complex retinal disease, characterized by the development of neovascularization induced by the abnormal production and release of vascular endothelial growth factor (VEGF). The term VEGF includes different isoforms; VEGF-A represents one of the most important pathogenic factors of DR. Anti-VEGF intravitreal therapies radically changed the outcome of DR, due to combined anti-angiogenic and anti-edematous activities. Nowadays, several anti-VEGF molecules exist, characterized by different pharmacological features and duration. With respect to PDR, although anti-VEGF treatments represented a fundamental step forward in the management of this dramatic complication, a big debate is present in the literature regarding the role of anti-VEGF as substitute of panretinal photocoagulation or if these two approaches may be used in combination. In the present review, we provided an update on VEGF isoforms and their role in DR pathogenesis, on current anti-VEGF molecules and emerging new drugs, and on the current management strategies of PDR. There is an overall agreement regarding the relative advantage provided by anti-VEGF, especially looking at the management of PDR patients requiring vitrectomy, with respect to laser. Based on the current data, laser approaches might be avoided when a perfectly planned anti-VEGF therapeutic strategy can be adopted. Conversely, laser treatment may have a role for those patients unable to guarantee enough compliance to anti-VEGF injections.Key messagesVEGF increased production, stimulated by retinal hypoperfusion and ischaemia, is a major pathogenic factor of neovascular complication onset in diabetic retinopathy and of DR stages progression.Nowadays, several anti-VEGF molecules are available in clinical practice and other molecules are currently under investigation. Each anti-VEGF molecule is characterized by different targets and may interact with multiple biochemical pathways within the eye.All the data agreed in considering anti-VEGF molecules as a first line choice for the management of diabetic retinopathy. Laser treatments may have a role in selected advanced cases and for those patients unable to guarantee enough compliance to intravitreal treatments schemes.

Vascular Endothelial Growth Factor Receptor 2: Molecular Mechanism and Therapeutic Potential in Preeclampsia Comorbidity with Human Immunodeficiency Virus and Severe Acute Respiratory Syndrome Coronavirus 2 Infections

This review explored the role of vascular endothelial growth factor receptor-2 (VEGFR-2) in the synergy of preeclampsia (PE), human immunodeficiency virus (HIV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. Downregulation of VEGFR-2 in PE promotes endothelial dysfunction and prevents endothelial cell (EC) migration, proliferation, and differentiation. The HIV-1 accessory protein, tat (trans-activator of transcription), prevents VEGFR-2 signaling via the vascular endothelial growth factor A (VEGF-A) ligand. Combined antiretroviral therapy (cART) may cause immune reconstitution, impaired decidualization, and endothelial injury, thus may be a risk factor for PE development. The VEGF/VEGFR-2 interaction may be associated with SARS-CoV-2-related pulmonary oedema. Endothelial dysfunction and heightened inflammation are both associated with PE, HIV, and SARS-CoV-2 infection; therefore, it is plausible that both characteristics may be exacerbated in the synergy of these events. In addition, this review explored microRNAs (miR) regulating VEGFR-2. An overexpression of miR-126 is evident in PE, HIV, and SARS-CoV-2 infection; thus, modulating the expression of miR-126 may be a therapeutic strategy. However, the involvement of microRNAs in PE, HIV, and SARS-CoV-2 infection needs further investigating. Since these conditions have been evaluated independently, this review attempts to predict their clinical manifestations in their synergy, as well as independently; thereby providing a platform for early diagnosis and therapeutic potential in PE, HIV, and SARS-CoV-2 infection.

Nano‐gold micelles loaded Dox and Elacridar for reversing drug resistance of breast cancer

The aim of this study was to provide a new effective carrier for rescuing the sensitivity of drug-resistant in breast cancer cells. Nano-gold micelles loaded with Dox and Elacridar (FP-ssD@A-E) were chemically synthesised. With the increase in the amount of Dox and Elacridar, the encapsulation rate of FP-ssD@A-E gradually increased, and the drug loading rate gradually decreased. FP-ss@A-E had a sustained-release effect. Dox, Elacridar, FP-ss@AuNPs, and FP-ssD@A-E significantly improved cell apoptosis, in which, FP-ssD@A-E was the most significant. FP-ssD@A-E significantly decreased the cell viability and improved the Dox uptake. The levels of VEGFR-1, P-gp, IL-6, and i-NOS were significantly decreased after Dox, Dox + Elacridar, FP-ss@AuNPs, and FP-ssD@A-E treatment. It was worth noting that FP-ssD@A-E had the most significant effects. The prepared FP-ssD@A-E micelles, which were spherical in shape, uniform in particle size distribution, and had good drug loading performance and encapsulation efficiency.

Serum Levels of VEGF-A and Its Receptors in Patients in Different Phases of Hemorrhagic and Ischemic Strokes

Vascular endothelial growth factors (VEGFs) are important regulators of angiogenesis, neuroprotection, and neurogenesis. Studies have indicated the association of VEGF dysregulation with the development of neurodegenerative and cerebrovascular diseases. We studied the changes in serum levels of VEGF-A, VEGFR-1, and VEGFR-2 in patients at various phases of ischemic and hemorrhagic strokes. Quantitative assessment of VEGF-A, VEGFR-1, and VEGFR-2 in serum of patients with hemorrhagic or ischemic stroke was performed by enzyme immunoassay in the hyper-acute (1−24 h from the onset), acute (up to 1−7 days), and early subacute (7 days to 3 months) phases of stroke, and then compared with the control group and each other. Results of our retrospective study demonstrated different levels of VEGF-A and its receptors at various phases of ischemic and hemorrhagic strokes. In ischemic stroke, increased VEGFR-2 level was found in the hyper-acute (p = 0.045) and acute phases (p = 0.024), while elevated VEGF-A and reduced VEGFR-1 levels were revealed in the early subacute phase (p = 0.048 and p = 0.012, respectively). In hemorrhagic stroke, no significant changes in levels of VEGF-A and its receptors were identified in the hyper-acute phase. In the acute and early subacute phases there was an increase in levels of VEGF-A (p < 0.001 and p = 0.006, respectively) and VEGFR-2 (p < 0.001 and p = 0.012, respectively). Serum levels of VEGF-A and its receptors in patients with hemorrhagic and ischemic stroke indicate different pathogenic pathways depending on the phase of the disease.

Neuropilin-1 in the pathogenesis of preeclampsia, HIV-1, and SARS-CoV-2 infection: A review

This review explores the role of transmembrane neuropilin-1 (NRP-1) in pregnancy, preeclampsia (PE), human immunodeficiency virus type 1 (HIV-1) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. Since these conditions are assessed independently, this review attempts to predict their comorbid clinical manifestations. Dysregulation of NRP-1 contributes to the pathogenesis of PE by (a) impairing vascular endothelial growth factor (VEGF) signaling for adequate spiral artery remodeling and placentation, (b) inducing syncytiotrophoblast (ST) cell apoptosis and increasing ST-derived microparticle circulation and (c) by decreasing regulatory T cell activity predisposing maternal immune intolerance. Although NRP-1 is upregulated in SARS-CoV-2 placentae, its exploitation for SARS-CoV-2 internalization and increased infectivity may alter angiogenesis through the competitive inhibition of VEGF. The anti-inflammatory nature of NRP-1 may aid its upregulation in HIV-1 infection; however, the HIV-accessory protein, tat, reduces NRP-1 expression. Upregulated NRP-1 in macrophages and dendritic cells also demonstrated HIV-1 resistance/reduced infectivity. Notably, HIV-1-infected pregnant women receiving antiretroviral therapy (ART) to prevent vertical transmission may experience immune reconstitution, impaired decidualization, and elevated markers of endothelial injury. Since endothelial dysfunction and altered immune responses are central to PE, HIV-1 infection, ART usage and SARS-CoV-2 infection, it is plausible that an exacerbation of both features may prevail in the synergy of these events. Additionally, this review identifies microRNAs (miRNAs) mediating NRP-1 expression. MiR-320 and miR-141 are overexpressed in PE, while miR-206 and miR-124-3p showed increased expression in PE and HIV-1 infection. Additionally, miR-214 is overexpressed in PE, HIV-1 and SARS-CoV-2 infection, implicating treatment strategies to reduce these miRNAs to upregulate and normalize NRP-1 expression. However, inconsistencies in the data of the role and regulation of miRNAs in PE, HIV-1 and SARS-CoV-2 infections require clarification. This review provides a platform for early diagnosis and potential therapeutic intervention of PE, HIV-1, and SARS-CoV-2 infections independently and as comorbidities.

Oxidative stress: An essential factor in the process of arteriovenous fistula failure

For more than half a century, arteriovenous fistula (AVFs) has been recognized as a lifeline for patients requiring hemodialysis (HD). With its higher long-term patency rate and lower probability of complications, AVF is strongly recommended by guidelines in different areas as the first choice for vascular access for HD patients, and its proportion of application is gradually increasing. Despite technological improvements and advances in the standards of postoperative care, many deficiencies are still encountered in the use of AVF related to its high incidence of failure due to unsuccessful maturation to adequately support HD and the development of neointimal hyperplasia (NIH), which narrows the AVF lumen. AVF failure is linked to the activation and migration of vascular cells and the remodeling of the extracellular matrix, where complex interactions between cytokines, adhesion molecules, and inflammatory mediators lead to poor adaptive remodeling. Oxidative stress also plays a vital role in AVF failure, and a growing amount of data suggest a link between AVF failure and oxidative stress. In this review, we summarize the present understanding of the pathophysiology of AVF failure. Furthermore, we focus on the relation between oxidative stress and AVF dysfunction. Finally, we discuss potential therapies for addressing AVF failure based on targeting oxidative stress.

BMP3 inhibits TGFβ2-mediated myofibroblast differentiation during wound healing of the embryonic cornea

Often acute damage to the cornea initiates drastic tissue remodeling, resulting in fibrotic scarring that disrupts light transmission and precedes vision impairment. Very little is known about the factors that can mitigate fibrosis and promote scar-free cornea wound healing. We previously described transient myofibroblast differentiation during non-fibrotic repair in an embryonic cornea injury model. Here, we sought to elucidate the mechanistic regulation of myofibroblast differentiation during embryonic cornea wound healing. We found that alpha-smooth muscle actin (αSMA)-positive myofibroblasts are superficial and their presence inversely correlates with wound closure. Expression of TGFβ2 and nuclear localization of pSMAD2 were elevated during myofibroblast induction. BMP3 and BMP7 were localized in the corneal epithelium and corresponded with pSMAD1/5/8 activation and absence of myofibroblasts in the healing stroma. In vitro analyses with corneal fibroblasts revealed that BMP3 inhibits the persistence of TGFβ2-induced myofibroblasts by promoting disassembly of focal adhesions and αSMA fibers. This was confirmed by the expression of vinculin and pFAK. Together, these data highlight a mechanism to inhibit myofibroblast persistence during cornea wound repair.

VEGF and eNOS variants may influence intervertebral disc degeneration

BACKGROUND

Intervertebral disc degeneration (IDD) is a common and complex condition. Vascular endothelial growth factor (VEGF) is one of the key regulators of angiogenesis and vascular permeability. Nitric oxide (NO) plays a role in various physiological events. The endothelial nitric oxide synthase (eNOS) that catalyses NO generation are crucial for the regulation of NO level. This study aimed to evaluate the association between VEGF/ eNOS gene variants with IDD.

MATERIALS AND METHODS

Two hundred ninety-one subjects (111 IDD patients and 180 controls) were included in the present case-control study. VEGF -2549 insertion/deletion (I/D) and eNOS VNTR variants were analysed by PCR method. The results of this analysis were evaluated for statistical significance.

RESULTS

There were no statistically significant differences in genotype and allele distribution of VEGF -2549 I/D/ eNOS VNTR variants between IDD patients and control subjects. We then evaluated the association between the allele frequencies of these variants and clinical features of IDD. Lumber IDD was more common in patients carrying VEGF I/D variant D allele (p < 0.001). Also, patients with lumbar disc herniation, cervical disc herniation, lumbar stenosis, and lumbar IDD had more 4 b allele (p = 0.005, p < 0.001, p < 0.001, and p = 0.03, respectively).

CONCLUSIONS

In conclusion, this study demonstrates first time that some clinical characteristics of IDD have been associated with allele frequencies of VEGF -2549 I/D/ eNOS VNTR variants.

Comparison of matrix metalloproteinase 9 and 14 levels in vitreous samples in diabetic and non-diabetic patients: a case control study

Background

MMP-9 plays a prominent role in inflammation and MMP-14 take part in angiogenesis. The objective of this study is to compare MMP-9 and MMP-14 levels between diabetic and non-diabetic patients.

Methods

The patients who scheduled for pars plana vitrectomy were included in our study. Patients are divided into 2 groups: the diabetic group and non-diabetic group. Age, gender, intraocular pressure(IOP), visual acuity (VA) were reported. Color fundus photography, fundus fluorescein angiography, optic coherence tomography (OCT) were performed before and after the operation. MMP-9 and MMP-14 levels in vitreous samples were analyzed with a reader device by ELISA method. Mann–Whitney U test and logistic regressions were used in statistical analysis, p < 0.05 accepted as statistically significant.

Results

70 eyes of 70 patients who received pars plana vitrectomy were enrolled in the study and divided into 2 groups: 34 patients in the diabetic group, 36 patients in the non-diabetic group. The average age of diabetic patients was 60.14 ± 10.20, and non-diabetic patients was 64.22 ± 11.16, respectively. The average MMP-9 (0.67 ± 0.66 ng/ml) and MMP-14 (0.16 ± 0.45 ng/ml) values in the diabetic group were significantly higher than the average MMP-9 (0.21 ± 0.05 ng/ml) and MMP-14 (and 0.07 ± 0.02 ng/ml) values in the non-diabetic group (P < 0.01). Also, it was observed that MMP-9 and MMP-14 levels increases as the diabetic disease duration increases. The risk of diabetes incidence increased with high levels of MMP-9 and MMP-14.

Conclusion

Due to the higher levels of MMP-9 and MMP-14 in the pathogenesis of diabetic retinopathy, these proteins may probably be among the therapeutic targets in the prevention and treatment of retinopathy.

Antilipidemic ezetimibe induces regression of endometriotic explants in a rat model of endometriosis with its anti-inflammatory and anti-angiogenic effects

To assess the potential therapeutic role of antilipidemic ezetimibe on endometriosis in an experimental rat model. A standard experimental endometriosis model was created with 18 Whistar-Albino rats, and after 1 month, the sizes of the endometriotic explants were measured. The rats were randomized as study and control groups. A total of 1 mg/kg/day ezetimibe and 1 ml/kg/day saline were administered orally to the study and control groups respectively for 28 days. At the end of 28 days, the explants were measured again, excised, and sent for histopathologic assessment for expression of tumor necrosis factor-alpha (TNF-α) and vascular endothelial growth factor (VEGF) and number of mast cells. At the end of the study period, the size of the endometriotic explants decreased significantly in the study group; but not in the control group (from 145.3 ± 120.5 to 89.8 ± 60.1 vs 174.72 ± 88.3 to 87.65 ± 27.1 cm3 respectively); however, the amount of post- and pretreatment differences in explant sizes was similar in the groups. The median TNF-α and VEGF levels were significantly lower in the ezetimibe group when compared to the control group (4 [3-4] vs 2 [1-3], p 0.029; 4 [3-4] vs 2 [2-3], p 0.002; respectively). And numbers of mast cells in all uterine layers were also lower in the ezetimibe group. Ezetimibe decreased the size of the endometriotic explants with its anti-inflammatory and anti-angiogenic properties. This agent alone or with combination of other agents may have a potential role in the treatment of endometriosis.

Aqueous Humor Cytokine Levels and Choroidal Thicknesses of Patients with Age‐related Macular Degeneration and Pachychoroid Neovasculopathy

Purpose: We sought correlations between the subfoveal choroidal thickness (SCT) and changes in the levels of aqueous humor cytokines before and after anti‐vascular endothelial growth factor (anti‐VEGF) treatment of patients with neovascular age‐related macular degeneration (nAMD) and pachychoroid neovasculopathy.Methods: We measured changes in the SCT and levels of aqueous humor cytokines (VEGF, soluble VEGF receptor‐2 [sVEGFR‐ 2], platelet‐derived growth factor [PDGF]‐AA, monocyte chemoattractant protein 1 [MCP‐1], interleukin [IL]‐6, and IL‐8) after anti‐ VEGF treatment of 11 eyes of 11 nAMD patients and nine eyes of nine pachychoroid neovasculopathy patients. The aqueous humor cytokine levels were compared between the two groups.Results: After anti‐VEGF treatment, the aqueous levels of VEGF and PDGF‐AA decreased significantly, whereas that of sVEGFR‐2 increased. The amount of change in sVEGFR‐2 concentration before and after anti‐VEGF treatment correlated with the SCT and its change after treatment. nAMD patients with relatively thin SCTs and smaller SCT changes after anti‐VEGF treatment showed greater increases in sVEGFR‐2 levels following treatment. We found significant correlations among the MCP‐1, IL‐6, and IL‐8 levels in the nAMD group, and between the sVEGFR‐2 and MCP‐1, and MCP‐1 and PDGF‐AA, levels in the pachychoroid neovasculopathy group.Conclusions: Patients with nAMD exhibited significant increases in aqueous sVEGFR‐2 levels following anti‐VEGF treatment and significant correlations among the levels of the inflammatory cytokines MCP‐1, IL‐6, and IL‐8, suggesting that angiogenic factors and inflammatory cytokines may affect the pathophysiologies of the two diseases differently.

Disentangling the association between retinal non-perfusion and anti-VEGF agents in diabetic retinopathy

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus (DM) and the leading cause of blindness in patients with DM. In the pathogenesis of DR, chronic hyperglycemia leads to biochemical and structural alterations in retinal blood vessels' wall, resulting in hyperpermeability and non-perfusion. Since vascular endothelial growth factor (VEGF) has been found to play a significant role in the pathogenesis of DR, this review sheds light on the effect of intravitreal anti-VEGF agents on retinal non-perfusion in patients with DR. Based on the existing literature, anti-VEGF agents have been shown to improve DR severity, although they cannot reverse retinal ischemia. The results of the published studies are controversial and differ based on the location of retinal non-perfusion, as well as the imaging modality used to assess retinal non-perfusion. In cases of macular non-perfusion, most of studies showed no change in both fundus fluorescein angiography (FFA) and optical coherence tomography (OCTA) in patients with DR treated with intravitreal anti-VEGF agents, while few studies reported worsening of non-perfusion with enlargement of foveal avascular zone (FAZ). Regarding peripheral ischemia, studies using wide-field-FFA demonstrated an improvement or stability in non-perfusion areas after anti-VEGF treatment. However, the use of wide-field-OCTA revealed no signs of re-perfusion of retinal vessels post anti-VEGF treatment. Further prospective studies with long follow-up and large sample size are still needed to draw solid conclusions.

Mechanoregulation of Vascular Endothelial Growth Factor Receptor 2 in Angiogenesis

The endothelial cells that compose the vascular system in the body display a wide range of mechanotransductive behaviors and responses to biomechanical stimuli, which act in concert to control overall blood vessel structure and function. Such mechanosensitive activities allow blood vessels to constrict, dilate, grow, or remodel as needed during development as well as normal physiological functions, and the same processes can be dysregulated in various disease states. Mechanotransduction represents cellular responses to mechanical forces, translating such factors into chemical or electrical signals which alter the activation of various cell signaling pathways. Understanding how biomechanical forces drive vascular growth in healthy and diseased tissues could create new therapeutic strategies that would either enhance or halt these processes to assist with treatments of different diseases. In the cardiovascular system, new blood vessel formation from preexisting vasculature, in a process known as angiogenesis, is driven by vascular endothelial growth factor (VEGF) binding to VEGF receptor 2 (VEGFR-2) which promotes blood vessel development. However, physical forces such as shear stress, matrix stiffness, and interstitial flow are also major drivers and effectors of angiogenesis, and new research suggests that mechanical forces may regulate VEGFR-2 phosphorylation. In fact, VEGFR-2 activation has been linked to known mechanobiological agents including ERK/MAPK, c-Src, Rho/ROCK, and YAP/TAZ. In vascular disease states, endothelial cells can be subjected to altered mechanical stimuli which affect the pathways that control angiogenesis. Both normalizing and arresting angiogenesis associated with tumor growth have been strategies for anti-cancer treatments. In the field of regenerative medicine, harnessing biomechanical regulation of angiogenesis could enhance vascularization strategies for treating a variety of cardiovascular diseases, including ischemia or permit development of novel tissue engineering scaffolds. This review will focus on the impact of VEGFR-2 mechanosignaling in endothelial cells (ECs) and its interaction with other mechanotransductive pathways, as well as presenting a discussion on the relationship between VEGFR-2 activation and biomechanical forces in the extracellular matrix (ECM) that can help treat diseases with dysfunctional vascular growth.

Functional In Vitro Assessment of VEGFA/NOTCH2 Signaling Pathway and pRB Proteasomal Degradation and the Clinical Relevance of Mucolipin TRPML2 Overexpression in Glioblastoma Patients

Glioblastoma (GBM) is the most malignant glioma with an extremely poor prognosis. It is characterized by high vascularization and its growth depends on the formation of new blood vessels. We have previously demonstrated that TRPML2 mucolipin channel expression increases with the glioma pathological grade. Herein by ddPCR and Western blot we found that the silencing of TRPML2 inhibits expression of the VEGFA/Notch2 angiogenic pathway. Moreover, the VEGFA/Notch2 expression increased in T98 and U251 cells stimulated with the TRPML2 agonist, ML2-SA1, or by enforced-TRPML2 levels. In addition, changes in TRPML2 expression or ML2-SA1-induced stimulation, affected Notch2 activation and VEGFA release. An increased invasion capability, associated with a reduced VEGF/VEGFR2 expression and increased vimentin and CD44 epithelial-mesenchymal transition markers in siTRPML2, but not in enforced-TRPML2 or ML2-SA1-stimulated glioma cells, was demonstrated. Furthermore, an increased sensitivity to Doxorubicin cytotoxicity was demonstrated in siTRPML2, whereas ML2-SA1-treated GBM cells were more resistant. The role of proteasome in Cathepsin B-dependent and -independent pRB degradation in siTRPML2 compared with siGLO cells was studied. Finally, through Kaplan-Meier analysis, we found that high TRPML2 mRNA expression strongly correlates with short survival in GBM patients, supporting TRPML2 as a negative prognostic factor in GBM patients.

How the structural properties of the indole derivatives are important in kinase targeted drug design?: A case study on tyrosine kinase inhibitors

Kinases are considered as important signalling enzymes that illustrate 20% of the druggable genome. Human kinase family comprises >500 protein kinases and about 20 lipid kinases. Protein kinases are responsible for the mechanism of protein phosphorylation. These are necessary for regulation of various cellular activities including proliferation, cell cycle, apoptosis, motility, growth, differentiation, etc. Their deregulation leads to disruption of many cellular processes leading to different diseases most importantly cancer. Thus, kinases are considered as valuable targets in different types of cancer as well as other diseases. Researchers around the world are actively engaged in developing inhibitors based on distinct chemical scaffolds. Indole represents as a versatile scaffold in the naturally occurring and bioactive molecules. It is also used as a privileged scaffold for the target-based drug design against different diseases. This present article aim to review the applications of indole scaffold in the design of inhibitors against different tyrosine kinases such as epidermal growth factor receptors (EGFRs), vascular endothelial growth factor receptors (VEGFRs), platelet-derived growth factor receptors (PDGFRs), etc. Important structure activity relationships (SARs) of indole derivatives were discussed. The present work is an attempt to summarize all the crucial structural information which is essential for the development of indole based tyrosine kinase inhibitors with improved potency.

Intravitreal Injection for Diabetic Macular Edema as Adjunctive Therapy for Proliferative Diabetic Retinopathy: A Retrospective Study

Purpose

To detect the impact of intravitreal injection (IVI) therapy with sole anti-vascular-endothelial-growth-factor (VEGF) or combined with steroids treating diabetic macular edema (DME) on activity of proliferative diabetic retinopathy (PDR) based on total number of panretinal photocoagulation (PRP) spots needed within 2 years.

Patients and Methods

A retrospective study of 102 eyes with primary-onset PDR and minimum follow-up of 24 months divided into 2 groups: Group 1 (G1) 40 eyes received only PRP and did not develop DME. Group 2 (G2) 62 eyes received additional IVI-therapy due to concomitant DME, with anti-VEGF only (subgroup 2a, G2a) or in combination with steroids (subgroup 2b, G2b). Main outcomes: central macular thickness (CMT, µm), best-corrected visual acuity (BCVA, LogMAR) and total number of needed PRP spots and IVI after 24 months.

Results

CMT was significantly higher in G2 compared to G1, initially (p < 0.01) and after 24 months (p = 0.01). CMT was significantly higher in G2b compared to G2a, both initially (p = 0.01) and after 24 months (p < 0.01). BCVA was significantly higher in G1 compared to G2, initially and after 24 months (p = 0.01). BCVA was not significantly different between the two subgroups, initially (p = 0.54) and after 24 months (p = 0.29). The total number of PRP spots was significantly higher in G1 compared to G2 (p < 0.01) but not significantly different between the subgroups (p = 0.8).

Conclusion

Regardless of severity of concomitant DME, IVI with sole anti-VEGF or combined with steroids reduced the total number of PRP spots needed within 2 years significantly indicating a favorable effect on activity of PDR.

Prognostic significance of VEGF signaling system components and matrix metalloproteinases in blood serum of gastric cancer patients

Analysis of long-term treatment results of 77 primary gastric cancer patients at stage I-IV of the tumor process followed during 1 - 41 months (median - 6.4 months) from the onset of specific treatment are presented depending on the basal levels of VEGF, soluble forms of its receptors (sVEGFR1, sVEGFR2) and matrix metalloproteinases (MMP-2, 7, 9) in blood serum. Overall survival assessed by Kaplan-Meyer analysis and with the help of Cox multiparametric regression model was applied as the criterion of prognostic value. It was found that at high (≥ 420 pg/ml) serum VEGF, the overall survival of patients with gastric cancer was statistically significantly lower than at the marker's levels below 420 pg/ml (p<0.011): 3-year's survival comprised 46,3±12,5% and 88,2±7,8% respectively. Median survival of patients with high VEGF level comprised 21.7 months, of those with low VEGF was not achieved during the whole follow-up period. Serum sVEGFR1, sVEGFR2, MMP-2, 7 and 9 levels were not significantly associated with the overall survival of patients included in this study. Only index M of TNM system and serum VEGF level demonstrated an independent prognostic value in multiparametric model (p=0.036). Thus, it was confirmed that VEGF signaling pathway plays an important role in gastric cancer, and its components - in the first place, VEGF A - are substantial factors of disease prognosis, and can also be useful for monitoring of treatment efficiency.

A Structural Overview of Vascular Endothelial Growth Factors Pharmacological Ligands: From Macromolecules to Designed Peptidomimetics

The vascular endothelial growth factor (VEGF) family of cytokines plays a key role in vasculogenesis, angiogenesis, and lymphangiogenesis. VEGF-A is the main member of this family, alongside placental growth factor (PlGF), VEGF-B/C/D in mammals, and VEGF-E/F in other organisms. To study the activities of these growth factors under physiological and pathological conditions, resulting in therapeutic applications in cancer and age-related macular degeneration, blocking ligands have been developed. These have mostly been large biomolecules like antibodies. Ligands with high affinities, at least in the nanomolar range, and accurate structural data from X-ray crystallography and NMR spectroscopy have been described. They constitute the main focus of this overview, which evidences similarities and differences in their binding modes. For VEGF-A ligands, and to a limited extent also for PlGF, a transition is now observed towards developing smaller ligands like nanobodies and peptides. These include unnatural amino acids and chemical modifications for designed and improved properties, such as serum stability and greater affinity. However, this review also highlights the scarcity of such small molecular entities and the striking lack of small organic molecule ligands. It also shows the gap between the rather large array of ligands targeting VEGF-A and the general absence of ligands binding other VEGF members, besides some antibodies. Future developments in these directions are expected in the upcoming years, and the study of these growth factors and their promising therapeutic applications will be welcomed.

Dietary supplementation with L-arginine between days 14 and 25 of gestation enhances NO and polyamine syntheses and the expression of angiogenic proteins in porcine placentae

Dietary supplementation with 0.4 or 0.8% L-arginine (Arg) to gilts between days 14 and 25 of gestation enhances embryonic survival and vascular development in placentae; however, the underlying mechanisms are largely unknown. This study tested the hypothesis that Arg supplementation stimulated placental expression of mRNAs and proteins that enhance angiogenesis, including endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor (VEGF), placental growth factor (PGF), GTP cyclohydrolase-I (GTP-CH1), ornithine decarboxylase (ODC1), and vascular endothelial growth factor receptors 1 and 2 (VEGFR1 and VEGFR2). Beginning on the day of breeding, gilts were fed daily 2 kg of a corn-soybean meal-based diet supplemented with 0.0 (control), 0.4, or 0.8% Arg. On day 25 of gestation, gilts were hysterectomized to obtain uteri and conceptuses for histochemical and biochemical analyses. eNOS and VEGFR1 proteins were localized to endothelial cells of maternal uterine blood vessels and to the uterine luminal epithelium, respectively. Compared with the control, dietary supplementation with 0.4 or 0.8% Arg increased (P < 0.05) the amounts of nitrite plus nitrate (NOx; oxidation products of NO) and polyamines in allantoic and amniotic fluids, concentrations of NOx, tetrahydrobiopterin (BH4, an essential cofactor for all NOS isoforms) and polyamines in placentae, as well as placental protein abundances of GTP-CH1 (the key enzyme for BH4 production) and ODC1 (the key enzyme for polyamine synthesis). Placental  mRNA levels for GTP-CH1, eNOS, PGF, VEGF, and VEGFR2 increased in response to both 0.4% and 0.8% Arg supplementation. Collectively, these results indicate that dietary Arg supplementation to gilts between days 14 and 25 of pregnancy promotes placental angiogenesis by increasing the expression of mRNAs and proteins for angiogenic factors as well as NO and polyamine syntheses.

PlGF Reduction Compromises Angiogenesis in Diabetic Foot Disease Through Macrophages

Diabetic foot disease (DFD) is a common and serious complication for diabetes and is characterized with impaired angiogenesis. In addition to the well-defined role of vascular endothelial growth factor (VEGF) -A and its defect in the pathogenesis of DFD, another VEGF family member, placental growth factor (PlGF), was also recently found to alter expression pattern in the DFD patients with undetermined mechanisms. This question was thus addressed in the current study. We detected attenuated PlGF upregulation in a mouse DFD model. In addition, the major cell types at the wound to express the unique PlGF receptor, VEGF receptor 1 (VEGFR1), were macrophages and endothelial cells. To assess how PlGF regulates DFD-associated angiogenesis, we injected recombinant PlGF and depleted VEGF1R specifically in macrophages by local injection of an adeno-associated virus (AAV) carrying siRNA for VEGFR1 under a macrophage-specific CD68 promoter. We found that the angiogenesis and recovery of the DFD were both improved by PlGF injection. The PlGF-induced improvement in angiogenesis and the recovery of skin injury were largely attenuated by macrophage-specific depletion of VEGF1R, likely resulting from reduced macrophage number and reduced M2 polarization. Together, our data suggest that reduced PlGF compromises angiogenesis in DFD at least partially through macrophages.

The Role of the VEGF Family in Coronary Heart Disease

The vascular endothelial growth factor (VEGF) family, the regulator of blood and lymphatic vessels, is mostly investigated in the tumor and ophthalmic field. However, the functions it enjoys can also interfere with the development of atherosclerosis (AS) and further diseases like coronary heart disease (CHD). The source, regulating mechanisms including upregulation and downregulation, target cells/tissues, and known functions about VEGF-A, VEGF-B, VEGF-C, and VEGF-D are covered in the review. VEGF-A can regulate angiogenesis, vascular permeability, and inflammation by binding with VEGFR-1 and VEGFR-2. VEGF-B can regulate angiogenesis, redox, and apoptosis by binding with VEGFR-1. VEGF-C can regulate inflammation, lymphangiogenesis, angiogenesis, apoptosis, and fibrogenesis by binding with VEGFR-2 and VEGFR-3. VEGF-D can regulate lymphangiogenesis, angiogenesis, fibrogenesis, and apoptosis by binding with VEGFR-2 and VEGFR-3. These functions present great potential of applying the VEGF family for treating CHD. For instance, angiogenesis can compensate for hypoxia and ischemia by growing novel blood vessels. Lymphangiogenesis can degrade inflammation by providing exits for accumulated inflammatory cytokines. Anti-apoptosis can protect myocardium from impairment after myocardial infarction (MI). Fibrogenesis can promote myocardial fibrosis after MI to benefit cardiac recovery. In addition, all these factors have been confirmed to keep a link with lipid metabolism, the research about which is still in the early stage and exact mechanisms are relatively obscure. Because few reviews have been published about the summarized role of the VEGF family for treating CHD, the aim of this review article is to present an overview of the available evidence supporting it and give hints for further research.

ETS1, ELK1, and ETV4 Transcription Factors Regulate Angiopoietin-1 Signaling and the Angiogenic Response in Endothelial Cells

Background

Angiopoietin-1 (Ang-1) is the main ligand of Tie-2 receptors. It promotes endothelial cell (EC) survival, migration, and differentiation. Little is known about the transcription factors (TFs) in ECs that are downstream from Tie-2 receptors.

Objective

The main objective of this study is to identify the roles of the ETS family of TFs in Ang-1 signaling and the angiogenic response.

Methods

In silico enrichment analyses that were designed to predict TF binding sites of the promotors of eighty-six Ang-1-upregulated genes showed significant enrichment of ETS1, ELK1, and ETV4 binding sites in ECs. Human umbilical vein endothelial cells (HUVECs) were exposed for different time periods to recombinant Ang-1 protein and mRNA levels of ETS1, ELK1, and ETV4 were measured with qPCR and intracellular localization of these transcription factors was assessed with immunofluorescence. Electrophoretic mobility shift assays and reporter assays were used to assess activation of ETS1, ELK1, and ETV4 in response to Ang-1 exposure. The functional roles of these TFs in Ang-1-induced endothelial cell survival, migration, differentiation, and gene regulation were evaluated by using a loss-of-function approach (transfection with siRNA oligos).

Results

Ang-1 exposure increased ETS1 mRNA levels but had no effect on ELK1 or ETV4 levels. Immunostaining revealed that in control ECs, ETS1 has nuclear localization whereas ELK1 and ETV4 are localized to the nucleus and the cytosol. Ang-1 exposure increased nuclear intensity of ETS1 protein and enhanced nuclear mobilization of ELK1 and ETV4. Selective siRNA knockdown of ETS1, ELK1, and ETV4 showed that these TFs are required for Ang-1-induced EC survival and differentiation of cells, while ETS1 and ETV4 are required for Ang-1-induced EC migration. Moreover, ETS1, ELK1, and ETV4 knockdown inhibited Ang-1-induced upregulation of thirteen, eight, and nine pro-angiogenesis genes, respectively.

Conclusion

We conclude that ETS1, ELK1, and ETV4 transcription factors play significant angiogenic roles in Ang-1 signaling in ECs.

CD146/Soluble CD146 Pathway Is a Novel Biomarker of Angiogenesis and Inflammation in Proliferative Diabetic Retinopathy

Purpose

Inflammation, angiogenesis and fibrosis are pathological hallmarks of proliferative diabetic retinopathy (PDR). The CD146/sCD146 pathway displays proinflammatory and proangiogenic properties. We investigated the role of this pathway in the pathophysiology of PDR.

Methods

Vitreous samples from 41 PDR and 27 nondiabetic patients, epiretinal fibrovascular membranes from 18 PDR patients, rat retinas, human retinal microvascular endothelial cells (HRMECs) and human retinal Müller glial cells were studied by ELISA, Western blot analysis, immunohistochemistry and immunofluorescence microscopy analysis. Blood-retinal barrier breakdown was assessed with fluorescein isothiocyanate-conjugated dextran.

Results

sCD146 and VEGF levels were significantly higher in vitreous samples from PDR patients than in nondiabetic patients. In epiretinal membranes, immunohistochemical analysis revealed CD146 expression in leukocytes, vascular endothelial cells and myofibroblasts. Significant positive correlations were detected between numbers of blood vessels expressing CD31, reflecting angiogenic activity of PDR, and numbers of blood vessels and stromal cells expressing CD146. Western blot analysis showed significant increase of CD146 in diabetic rat retinas. sCD146 induced upregulation of phospho-ERK1/2, NF-κB, VEGF and MMP-9 in Müller cells. The hypoxia mimetic agent cobalt chloride, VEGF and TNF-α induced upregulation of sCD146 in HRMECs. The MMP inhibitor ONO-4817 attenuated TNF-α-induced upregulation of sCD146 in HRMECs. Intravitreal administration of sCD146 in normal rats significantly increased retinal vascular permeability and induced significant upregulation of phospho-ERK1/2, intercellular adhesion molecule-1 and VEGF in the retina. sCD146 induced migration of HRMECs.

Conclusions

These results suggest that the CD146/sCD146 pathway is involved in the initiation and progression of PDR.

Crosstalk between MUC1 and VEGF in angiogenesis and metastasis: a review highlighting roles of the MUC1 with an emphasis on metastatic and angiogenic signaling

VEGF and its receptor family (VEGFR) members have unique signaling transduction system that play significant roles in most pathological processes, such as angiogenesis in tumor growth and metastasis. VEGF-VEGFR complex is a highly specific mitogen for endothelial cells and any de-regulation of the angiogenic balance implicates directly in endothelial cell proliferation and migration. Moreover, it has been shown that overexpressing Mucin 1 (MUC1) on the surface of many tumor cells resulting in upregulation of numerous signaling transduction cascades, such as growth and survival signaling pathways related to RTKs, loss of cell-cell and cell-matrix adhesion, and EMT. It promotes gene transcription of pro-angiogenic proteins such as HIF-1α during periods of oxygen scarcity (hypoxia) to enhance tumor growth and angiogenesis stimulation. In contrast, the cytoplasmic domain of MUC1 (MUC1-C) inhibits apoptosis, which in turn, impresses upon cell fate. Besides, it has been established that reduction in VEGF expression level correlated with silencing MUC1-C level indicating the anti-angiogenic effect of MUC1 downregulation. This review enumerates the role of MUC1-C oncoprotein and VEGF in angiogenesis and metastasis and describes several signaling pathways by which MUC1-C would mediate the pro-angiogenic activities of cancer cells.

Involvement of Cytokines in the Pathogenesis of Diabetic Macular Edema

Diabetic macular edema (DME) is a critical complication of diabetic retinopathy, a condition that arises from the breakdown of the blood–retinal barrier and the consequent increase in vascular permeability. Over the years, attempts have been made to treat DME by various approaches, including laser photocoagulation, steroid triamcinolone acetonide, and vitrectomy. However, treatment was unsatisfactory until research identified vascular endothelial growth factor (VEGF) as a factor in the pathogenesis of DME. Intraocular anti-VEGF agents show good efficacy in DME. Nevertheless, in some patients the condition recurs or becomes resistant to treatment, suggesting that other factors may be involved. Because inflammation and retinal hypoxia are seen in DME, research has examined the potential role of cytokines and other inflammatory mediators. In this review, we provide an overview of this research and describe feedback mechanisms that may represent a target for novel treatments.

Role of Vascular Endothelial Growth Factor (VEGF) in Human Embryo Implantation: Clinical Implications

Vascular endothelial growth factor (VEGF) is a well-known angiogenic factor that plays a critical role in various physiological and pathological processes. VEGF also contributes to the process of embryo implantation by enhancing embryo development, improving endometrial receptivity, and facilitating the interactions between the developing embryo and the endometrium. There is a correlation between the alteration of VEGF expression and reproductive failure, including recurrent implantation failure (RIF) and recurrent miscarriage (RM). In order to clarify the role of VEGF in embryo implantation, we reviewed recent literature concerning the expression and function of VEGF in the reproductive system around the time of embryo implantation and we provide a summary of the findings reported so far. We also explored the effects and the possible underlying mechanisms of action of VEGF in embryo implantation.

Maternal endothelial dysfunction in HIV-associated preeclampsia comorbid with COVID-19: a review

This review assesses markers of endothelial dysfunction (ED) associated with the maternal syndrome of preeclampsia (PE). We evaluate the role of antiretroviral therapy (ART) in human immunodeficiency virus (HIV)-infected preeclamptic women. Furthermore, we briefly discuss the potential of lopinavir/ritonavir (LPV/r), dolutegravir (DTG) and remdesivir (RDV) in drug repurposing and their safety in pregnancy complicated by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In HIV infection, the trans-activator of transcription protein, which has homology with vascular endothelial growth factor, impairs angiogenesis, leading to endothelial injury and possible PE development despite neutralization of their opposing immune states. Markers of ED show strong evidence supporting the adverse role of ART in PE development and mortality compared to treatment-naïve pregnancies. Coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2 infection, exploits angiotensin-converting enzyme 2 (ACE 2) to induce ED and hypertension, thereby mimicking angiotensin II-mediated PE in severe cases of infection. Upregulated ACE 2 in pregnancy is a possible risk factor for SARS-CoV-2 infection and subsequent PE development. The potential effectiveness of LPV/r against COVID-19 is inconclusive; however, defective decidualization, along with elevated markers of ED, was observed. Therefore, the safety of these drugs in HIV-positive pregnancies complicated by COVID-19 requires attention. Despite the observed endothelial protective properties of DTG, there is a lack of evidence of its effects on pregnancy and COVID-19 therapeutics. Understanding RDV-ART interactions and the inclusion of pregnant women in antiviral drug repurposing trials is essential. This review provides a platform for further research on PE in the HIV-COVID-19 syndemic.

Clopidogrel-Induced Gastric Injury in Rats is Attenuated by Stable Gastric Pentadecapeptide BPC 157

Aim

Although Clopidogrel is safe in healthy volunteers, it can induce recurrence of gastric ulcers in high-risk patients. Here, we investigated the protective effect of the natural product, stable gastric pentadecapeptide 157 (BPC 157) on Clopidogrel-induced gastric injury.

Methods

We used acetic acid to induce gastric ulcer in Sprague Dawley rats. Clopidogrel alone or in combination with BPC 157 or L-NAME (nitric oxide system blockade) were administered after healing of acetic acid-induced ulcer. One percent methylcellulose solution was used as control. Ulcer recurrence rate and the ulcer index were compared between these groups. Gastric mucosal apoptosis rate, microscopic inflammation activity and angiogenesis markers vascular endothelial growth factor A (VEGF-A) and CD34 were examined by TUNEL, histological evaluations (HE) and immunohistochemistry (IHC). Pathways involved, expressions of endoplasmic reticulum (ER) stress apoptosis marker CHOP, angiogenic markers VEGF-A and its receptor VEGFR1, and endothelial NO synthase (eNOS) were all analyzed by Western blot.

Results

This study indicated that Clopidogrel significantly induced the gastric ulcers recurrence, severe inflammation and ER stress related apoptosis of the gastric mucosa, suppressed the synthesis of angiogenic markers and eNOS. Furthermore, Clopidrogel intervention resulted in the activation of protein kinase B (AKT) and p38 mitogen-activated protein kinase (p38/MAPK). BPC 157 attenuated the gastric mucosal damage caused by Clopidogrel and reversed these molecular effects. However, NO blockade L-NAME weakened the protective effect and thus the molecular effects of BPC 157 on gastric mucosa.

Conclusion

In conclusion, these results suggest that BPC 157 inhibited Clopidogrel-induced gastric mucosa injury partially by inhibition of gastric mucosa cell ER stress-mediated apoptosis and inflammation, and promoting gastric mucosa angiogenesis via VEGF-A/VEGFR1 mediated-AKT/p38/MAPK signaling pathways.

Dihydrotanshinone, a Natural Diterpenoid, Preserves Blood-Retinal Barrier Integrity via P2X7 Receptor

Activation of P2X7 signaling, due to high glucose levels, leads to blood retinal barrier (BRB) breakdown, which is a hallmark of diabetic retinopathy (DR). Furthermore, several studies report that high glucose (HG) conditions and the related activation of the P2X7 receptor (P2X7R) lead to the over-expression of pro-inflammatory markers. In order to identify novel P2X7R antagonists, we carried out virtual screening on a focused compound dataset, including indole derivatives and natural compounds such as caffeic acid phenethyl ester derivatives, flavonoids, and diterpenoids. Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) rescoring and structural fingerprint clustering of docking poses from virtual screening highlighted that the diterpenoid dihydrotanshinone (DHTS) clustered with the well-known P2X7R antagonist JNJ47965567. A human-based in vitro BRB model made of retinal pericytes, astrocytes, and endothelial cells was used to assess the potential protective effect of DHTS against HG and 2′(3′)-O-(4-Benzoylbenzoyl)adenosine-5′-triphosphate (BzATP), a P2X7R agonist, insult. We found that HG/BzATP exposure generated BRB breakdown by enhancing barrier permeability (trans-endothelial electrical resistance (TEER)) and reducing the levels of ZO-1 and VE-cadherin junction proteins as well as of the Cx-43 mRNA expression levels. Furthermore, HG levels and P2X7R agonist treatment led to increased expression of pro-inflammatory mediators (TLR-4, IL-1β, IL-6, TNF-α, and IL-8) and other molecular markers (P2X7R, VEGF-A, and ICAM-1), along with enhanced production of reactive oxygen species. Treatment with DHTS preserved the BRB integrity from HG/BzATP damage. The protective effects of DHTS were also compared to the validated P2X7R antagonist, JNJ47965567. In conclusion, we provided new findings pointing out the therapeutic potential of DHTS, which is an inhibitor of P2X7R, in terms of preventing and/or counteracting the BRB dysfunctions elicited by HG conditions.

Comprehensive Analysis of Differently Expressed and Methylated Genes in Preeclampsia

Preeclampsia (PE) is one of the mainly caused maternal and infant incidences and mortalities worldwide. However, the mechanisms underlying PE remained largely unclear. The present study identified 1716 high expressions of gene and 2705 low expressions of gene using GSE60438 database, and identified 7087 hypermethylated and 15120 hypomethylated genes in preeclampsia using GSE100197. Finally, 536 upregulated genes with hypomethylation and 322 downregulated genes with hypermethylation were for the first time revealed in PE. Gene Ontology (GO) analysis revealed that these genes were associated with peptidyl-tyrosine phosphorylation, skeletal system development, leukocyte migration, transcription regulation, T cell receptor and IFN-γ-involved pathways, innate immune response, signal transduction, cell adhesion, angiogenesis, and hemopoiesis. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis demonstrated that aberrantly methylated differentially expressed genes were involved in regulating adherens junction, pluripotency of stem cell regulation, immune processing, T cell receptor and NF-κB pathways, HTLV-I and HSV infections, leishmaniasis, and NK-induced cytotoxicity. Protein-protein interaction (PPI) network analysis identified several hub networks and key genes, including MAPK8, CCNF, CDC23, ABL1, NF1, UBE2E3, CD44, and PIK3R1. We hope these findings will draw more attention to these hub genes in future PE studies.

Giant Cavernous Hemangioma of the Liver in a Patient with Autosomal Dominant Polycystic Kidney Disease

Patient: Male, 41-year-old

Final Diagnosis: Autosomal dominant polycystic kidney disease

Symptoms: Pain

Medication: —

Clinical Procedure: Computed tomography • ultrasonography

Specialty: Gastroenterology and Hepatology • Medicine, General and Internal • Nephrology

Cytokines and Pathogenesis of Central Retinal Vein Occlusion

Central retinal vein occlusion (CRVO) causes macular edema and subsequent vision loss and is common in people with diseases such as arteriosclerosis and hypertension. Various treatments for CRVO-associated macular edema have been trialed, including laser photocoagulation, with unsatisfactory results. However, when the important pathogenic role of vascular endothelial growth factor (VEGF) in macular edema was identified, the treatment of CRVO was revolutionized by anti-VEGF therapy. However, despite the success of intraocular injection of anti-VEGF agents in many patients with CRVO, some patients continue to suffer from refractory or recurring edema. In addition, the expression of inflammatory cytokines increases over time, causing more severe inflammation and a condition that is increasingly resistant to anti-VEGF therapy. This indicates that the pathogenesis of macular edema in CRVO is more complex than originally thought and may involve factors or cytokines associated with inflammation and ischemia other than VEGF. CRVO is also associated with leukocyte abnormalities and a gradual reduction in retinal blood flow velocity, which increase the likelihood of it developing from the nonischemic type into the more severe ischemic type; in turn, this results in excessive VEGF expression and subsequent neovascular glaucoma. Here, we review the role of different factors and cytokines involved in CRVO pathogenesis and propose a mechanism that holds promise for the development of novel therapies.

The role of microenvironment in tumor angiogenesis

Tumor angiogenesis is necessary for the continued survival and development of tumor cells, and plays an important role in their growth, invasion, and metastasis. The tumor microenvironment—composed of tumor cells, surrounding cells, and secreted cytokines—provides a conducive environment for the growth and survival of tumors. Different components of the tumor microenvironment can regulate tumor development. In this review, we have discussed the regulatory role of the microenvironment in tumor angiogenesis. High expression of angiogenic factors and inflammatory cytokines in the tumor microenvironment, as well as hypoxia, are presumed to be the reasons for poor therapeutic efficacy of current anti-angiogenic drugs. A combination of anti-angiogenic drugs and antitumor inflammatory drugs or hypoxia inhibitors might improve the therapeutic outcome.

Epsins in vascular development, function and disease

Epsins are a family of adaptor proteins involved in clathrin-dependent endocytosis. In the vasculature, epsins 1 and 2 are functionally redundant members of this family that are expressed in the endothelial cells of blood vessels and the lymphatic system throughout development and adulthood. These proteins contain a number of peptide motifs that allow them to interact with lipid moieties and a variety of proteins. These interactions facilitate the regulation of a wide range of cell signaling pathways. In this review, we focus on the involvement of epsins 1 and 2 in controlling vascular endothelial growth factor receptor signaling in angiogenesis and lymphangiogenesis. We also discuss the therapeutic implications of understanding the molecular mechanisms of epsin-mediated regulation in diseases such as atherosclerosis and diabetes.

Role of VEGF-A and LRG1 in Abnormal Angiogenesis Associated With Diabetic Nephropathy

Diabetic nephropathy (DN) is an important public health concern of increasing proportions and the leading cause of end-stage renal disease (ESRD) in diabetic patients. It is one of the most common long-term microvascular complications of diabetes mellitus that is characterized by proteinuria and glomerular structural changes. Angiogenesis has long been considered to contribute to the pathogenesis of DN, whereas the molecular mechanisms of which are barely known. Angiogenic factors associated with angiogenesis are the major candidates to explain the microvascular and pathologic finds of DN. Vascular endothelial growth factor A (VEGF-A), leucine-rich α-2-glycoprotein 1, angiopoietins and vasohibin family signal between the podocytes, endothelium, and mesangium have important roles in the maintenance of renal functions. An appropriate amount of VEGF-A is beneficial to maintaining glomerular structure, while excessive VEGF-A can lead to abnormal angiogenesis. LRG1 is a novel pro-angiogenic factors involved in the abnormal angiogenesis and renal fibrosis in DN. The imbalance of Ang1/Ang2 ratio has a role in leading to glomerular disease. Vasohibin-2 is recently shown to be in diabetes-induced glomerular alterations. This review will focus on current understanding of these angiogenic factors in angiogenesis and pathogenesis associated with the development of DN, with the aim of evaluating the potential of anti-angiogenesis therapy in patients with DN.

Novel Nargenicin A1 Analog Inhibits Angiogenesis by Downregulating the Endothelial VEGF/VEGFR2 Signaling and Tumoral HIF-1α/VEGF Pathway

Targeting angiogenesis is an attractive strategy for the treatment of angiogenesis-related diseases, including cancer. We previously identified 23-demethyl 8,13-deoxynargenicin (compound 9) as a novel nargenicin A1 analog with potential anticancer activity. In this study, we investigated the antiangiogenic activity and mode of action of compound 9. This compound was found to effectively inhibit in vitro angiogenic characteristics, including the proliferation, invasion, capillary tube formation, and adhesion of human umbilical vein endothelial cells (HUVECs) stimulated by vascular endothelial growth factor (VEGF). Furthermore, compound 9 suppressed the neovascularization of the chorioallantoic membrane of growing chick embryos in vivo. Notably, the antiangiogenic properties of compound 9 were related to the downregulation of VEGF/VEGFR2-mediated downstream signaling pathways, as well as matrix metalloproteinase (MMP)-2 and MMP-9 expression in HUVECs. In addition, compound 9 was found to decrease the in vitro AGS gastric cancer cell-induced angiogenesis of HUVECs by blocking hypoxia-inducible factor-1α (HIF-1α) and VEGF expression in AGS cells. Collectively, our findings demonstrate for the first time that compound 9 is a promising antiangiogenic agent targeting both VEGF/VEGFR2 signaling in ECs and HIF-1α/VEGF pathway in tumor cells.

Relationships among Retinal Nonperfusion, Neovascularization, and Vascular Endothelial Growth Factor Levels in Quiescent Proliferative Diabetic Retinopathy

Purpose: To investigate the relationships among the retinal nonperfusion (NP) area, neovascularization (NV) area, and aqueous humor vascular endothelial growth factor (VEGF) levels in quiescent proliferative diabetic retinopathy (PDR). Methods: Forty-seven eyes from 47 patients with treatment-naïve PDR that did not show macular edema or vitreous hemorrhage were enrolled. NP area, NV number, and NV area were quantitatively measured using ultra-widefield fluorescein angiography in an automated manner. Aqueous humor VEGF level was measured using a bead assay. Results: The NP areas of the total, posterior pole, peripheral retinae, and NV area positively correlated with each other (all p < 0.034). NV number correlated with total NP area, peripheral NP area, and NV area (all p ≤ 0.001). VEGF levels were significantly positively correlated with total, posterior polar, and peripheral NP areas and NV area (r = 0.575, 0.422, 0.558, and 0.362, respectively; all p ≤ 0.012). In eyes with NV in the disc area, the VEGF level was higher compare to eyes without NV in the disc area (208.89 ± 192.77 pg/mL vs. 103.34 ± 132.66, p = 0.010). A multiple linear regression model using NP area, NV area, and NVD demonstrated good prediction for VEGF level (R2 = 0.417, p < 0.001) and revealed a significant contribution of the peripheral NP area in predicting the VEGF level (β = 0.497, p = 0.002). Conclusions: Aqueous humor VEGF levels in quiescent PDR eyes were associated with NP and NV areas, which had positive correlations with each other. In addition, the NP area of the peripheral retina was the most important predictor of VEGF level.

Progress on ocular siRNA gene-silencing therapy and drug delivery systems

Age-related macular degeneration (AMD) and glaucoma are global ocular diseases with high blindness rate. RNA interference (RNAi) is being increasingly used in the treatment of these disorders with siRNA drugs, bevasiranib, AGN211745 and PF-04523655 for AMD, and SYL040012 and QPI-1007 for glaucoma. Administration routes and vectors of gene drugs affect their therapeutic effect. Compared with the non-viral vectors, viral vectors have limited payload capacity and potential immunogenicity. This review summarizes the progress of the ocular siRNA gene-silencing therapy by focusing on siRNA drugs for AMD and glaucoma already used in clinical research, the main routes of drug delivery and the non-viral vectors for siRNA drugs.

Galectin-1 studies in proliferative diabetic retinopathy

PURPOSE

Galectin-1 regulates endothelial cell function and promotes angiogenesis. We investigated the hypothesis that galectin-1 may be involved in the pathogenesis of proliferative diabetic retinopathy (PDR).

METHODS

Vitreous samples from 36 PDR and 20 nondiabetic patients, epiretinal fibrovascular membranes from 13 patients with PDR, rat retinas and human retinal Müller glial cells were studied by enzyme-linked immunosorbent assay (ELISA), immunohistochemistry and Western blot analysis. In vitro angiogenesis assays were performed and the adherence of leukocytes to galectin-1-stimulated human retinal microvascular endothelial cells (HRMECs) was assessed.

RESULTS

The ELISA analysis revealed that galectin-1 and vascular endothelial growth factor (VEGF) levels were significantly higher in vitreous samples from PDR patients than in those from nondiabetics (p < 0.001 for both comparisons). A significant positive correlation was found between the levels of galectin-1 and VEGF (r = 0.354; p = 0.022). In epiretinal membranes, immunohistochemical analysis showed that galectin-1 was expressed in vascular endothelial cells expressing CD31, myofibroblasts expressing α-smooth muscle actin and leukocytes expressing CD45. The galectin-1 receptor neuropilin-1 was expressed on vascular endothelial cells. CD31 staining was used as a marker to assess microvessel density (MVD). Significant positive correlation was detected between MVD in epiretinal membranes and the number of blood vessels expressing galectin-1 (r = 0.848; p < 0.001). Western blot analysis demonstrated significant increase of galectin-1 protein in rat retinas after induction of diabetes. ELISA analysis revealed that hydrogen peroxide and cobalt chloride (CoCl₂ ) induced upregulation of galectin-1 in Müller cells. Treatment with galectin-1 induced upregulation of VEGF in Müller cells and increased leukocyte adhesion to HRMECs. The galectin-1 inhibitor OTX008 attenuated VEGF-induced HRMECs migration and CoCl₂ -induced upregulation of NF-κB, galectin-1 and VEGF in Müller cells.

CONCLUSIONS

These results suggest that galectin-1is involved in the pathogenesis of PDR.