Anti-VEGF agents: As appealing targets in the setting of COVID-19 treatment in critically ill patients.

Recently, the medications used for the severe form of the coronavirus disease-19 (COVID-19) therapy are of particular interest. In this sense, it has been supposed that anti-VEGF compounds would be good candidates in the face of "cytokine storm" and intussuscepted angiogenesis due to having an appreciable anti-inflammatory effect. Therefore, they can be subjected to therapeutic protocols to manage acute respiratory distress syndrome (ARDS). Since the compelling evidence emphasized that VEGFs contribute to the inflammatory process and play a mainstay role in disease pathogenesis, in this review, we aimed to highlight the VEGF's plausible participation in the cytokine storm exacerbation in COVID-19. Next, the recent clinical advances regarding the anti-VEGF medications, including humanized monoclonal antibody, immunosuppressant, a tyrosine kinase inhibitor, and a cytokine inhibitor, have been addressed in the setting of COVID-19 treatment in critically ill patients. Together, retrieving the increased level of VEGF subsets, as well as antagonizing VEGF related receptors, could be helpful for the treatment of COVID-19, especially in those suffering from ARDS.

Identification and characterization of two novel vascular endothelial growth factor genes in Litopenaeus vannamei.

Vascular endothelial growth factor (VEGF) signaling pathway induces endothelial cell proliferation, promotes cell migration, and inhibits apoptosis. Although three VEGF and two VEGF receptor genes have been identified in Litopenaeus vannamei and demonstrated their roles in WSSV infection, another two novel VEGF genes (LvVEGF4, LvVEGF5) were isolated and their involvements in the WSSV infection of shrimp were studied in the present study. The deduced amino acid sequences of both LvVEGF4 and LvVEGF5 contained a signal peptide, a typical PDGF/VEGF domain and a cysteine knot motif (CXCXCX). Tissue distribution analysis showed that LvVEGF4 was predominantly expressed in gill and hemocytes, while LvVEGF5 was mainly detected in hemocytes and intestine. WSSV infection could cause up-regulation of the transcriptional levels of LvVEGF4 and LvVEGF5. Their functions were studied by double-strand RNA interference. The results showed that knock-down of LvVEGF4 and LvVEGF5 led to a decrease of the viral copy number in WSSV infected shrimp. Yeast two-hybrid analysis showed that both LvVEGF4 and LvVEGF5 could interact with LvVEGFR1 rather than LvVEGFR2. In addition, knock-down of LvVEGF4 and LvVEGF5 could reduce the expressional levels of downstream genes FAK and PI3K. The present study provides new clues in demonstrating that the VEGF signaling pathway is involved in the process of WSSV infection in shrimp.

Targeting VEGF/VEGFR to Modulate Antitumor Immunity.

In addition to the crucial role in promoting the growth of tumor vessels, vascular endothelial growth factor (VEGF) is also immunosuppressive. VEGF can inhibit the function of T cells, increase the recruitment of regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs), and hinder the differentiation and activation of dendritic cells (DCs). Recent studies have investigated the role of antiangiogenic agents in antitumor immunity, especially in recent 3 years. Therefore, it is necessary to update the role of targeting VEGF/VEGFR in antitumor immunity. In this review, we focus on the latest clinical and preclinical findings on the modulatory role of antiangiogenic agents targeting VEGF/VEGFR in immune cells, including effector T cells, Tregs, MDSCs, DCs, tumor-associated macrophages, and mast cells. Our review will be potentially helpful for the development of combinations of angiogenesis inhibitors with immunological modulators.

Indirect and competitive enzyme-linked immunosorbent assays for monitoring the humoral response against human VEGF.

CIGB-247, a VEGF-based vaccine, was studied in a clinical trial. This advance demands the refinement of the methodologies for assessment of vaccine immune responses. This study aimed to improve the performance of ELISAs for detecting IgG antibodies against human VEGF and the blocking activity of the serum to inhibit the VEGF/VEGFR2 interaction. The best experimental conditions were established through the evaluation of several blocking buffers, immobilization surfaces, and plate suppliers using human sera as test samples. As a result, two controlled ELISAs were used in testing of elicited immune response against VEGF in patients immunized with CIGB-247.

[Novel mechanism for retinal vascular diseases].

I. A new therapeutic target for diabetic retinopathy. Recent reports state that succinate may be an independent retinal angiogenic factor. We evaluated concentrations in vitreous from proliferative diabetic retinopathy (PDR), and found that succinate increased significantly in PDR. Interestingly, levels of succinate from bevacizumab-pre-injected PDR were normal, suggesting that vascular endothelial growth factor (VEGF) had a positive feedback mechanism for succinate since succinate was previously reported to induce VEGF. II. A new understanding of central retinal vein occlusion (CRVO). We evaluated retinal blood flow velocity with laser speckle flowgraphy (LSFG) made in Japan, and found that cases in which both macular edema and retinal blood flow velocity improved after anti-VEGF therapy had better prognosis. In ischemic CRVO at final visit, mean retinal blood velocity was less than 50% of fellow eyes after 1st anti-VEGF therapy, suggesting that those cases might have poor prognosis. LSFG is useful for evaluation and decision in CRVO treatment. III. From exploration for mechanism in retinal vascular diseases to re-vascularization therapy. The standard treatment for retinal non-perfusion area is scatter laser photocoagulation, which is both invasive of the peripheral retina and may prove destructive. Re-vascularization is an ideal strategy for treatment of retinal non-perfusion area. To develop a new methods for re-vascularization in retinal non-perfusion area, we have designed experiments using a retina without vasculature differentiated from induced pluripotent stem(iPS) cells.

Monitoring brain tumor vascular heamodynamic following anti-angiogenic therapy with advanced magnetic resonance imaging in mice.

Advanced MR imaging methods have an essential role in classification, grading, follow-up and therapeutic management in patients with brain tumors. With the introduction of new therapeutic options, the challenge for better tissue characterization and diagnosis increase, calling for new reliable non-invasive imaging methods. In the current study we evaluated the added value of a combined protocol of blood oxygen level dependent (BOLD) imaging during hyperoxic challenge (termed hemodynamic response imaging (HRI)) in an orthotopic mouse model for glioblastoma under anti-angiogenic treatment with B20-4.1.1, an anti-VEGF antibody. In glioblastoma tumors, the elevated HRI indicated progressive angiogenesis as further confirmed by histology. In the current glioblastoma model, B20-treatment caused delayed tumor progression with no significant changes in HRI yet with slightly reduced tumor vascularity as indicated by histology. Furthermore, fewer apoptotic cells and higher proliferation index were detected in the B20-treated tumors compared to control-treated tumors. In conclusion, HRI provides an easy, safe and contrast agent free method for the assessment of the brain hemodynamic function, an additionally important clinical information.

[A case of glomerulopathy associated with the vascular endothelial growth factor inhibitor bevacizumab].

The patient was a 73-year-old Japanese female diagnosed with stage IIIc primary peritoneal cancer. After undergoing total hysterectomy and bilateral oophorectomy, she received regimens consisting of paclitaxel (PTX) and carboplatin (CBDCA). She subsequently developed recurrence four years after the disease onset and was treated with PTX, CBDCA and the vascular endothelial growth factor (VEGF) inhibitor bevacizumab (Bev). Although clinical remission was maintained with the administration of Bev monotherapy every three weeks, proteinuria was detected six months later, and gradually increased. The findings of a renal biopsy showed diffuse wrinkling and double contouring of the glomerular tufts under light microscopy, although no immune complex deposition was observed on immunostaining. Additionally, electron microscopy showed hypertrophy of glomerular endothelial cells and widening of the subendothelial spaces. These histopathological findings were fully consistent with those of reported patients treated with VEGF inhibitors. The proteinuria attenuated following the initiation of treatment with losartan. Therefore, the administration of renoprotective therapy contributed to the patient's ability to continue the anticancer regimen with Bev in this case.

Antiangiogenic therapy of brain tumors: the role of bevacizumab.

Angiogenesis is one of the hallmarks of cancer, including brain tumors. Malignant gliomas have the highest degree of vascular proliferation among solid tumors; thus, angiogenic pathways represent an attractive target to interfere with tumor growth. Up to date VEGF pathway targeting with specific drugs has yielded interesting therapeutics results. In particular bevacizumab, a monoclonal antibody against VEGF-A, has shown clinical activity in malignant gliomas, especially glioblastomas, in terms of a high response rate on MRI and a significant increase in progression-free survival.

Peptide vaccines and targeting HER and VEGF proteins may offer a potentially new paradigm in cancer immunotherapy.

The ErbB family (HER-1, HER-2, HER-3 and HER-4) of receptor tyrosine kinases has been the focus of cancer immunotherapeutic strategies while antiangiogenic therapies have focused on VEGF and its receptors VEGFR-1 and VEGFR-2. Agents targeting receptor tyrosine kinases in oncology include therapeutic antibodies to receptor tyrosine kinase ligands or the receptors themselves, and small-molecule inhibitors. Many of the US FDA-approved therapies targeting HER-2 and VEGF exhibit unacceptable toxicities, and show problems of efficacy, development of resistance and unacceptable safety profiles that continue to hamper their clinical progress. The combination of different peptide vaccines and peptidomimetics targeting specific molecular pathways that are dysregulated in tumors may potentiate anticancer immune responses, bypass immune tolerance and circumvent resistance mechanisms. The focus of this review is to discuss efforts in our laboratory spanning two decades of rationally developing peptide vaccines and therapeutics for breast cancer. This review highlights the prospective benefit of a new, untapped category of therapies biologically targeted to EGF receptor (HER-1), HER-2 and VEGF with potential peptide 'blockbusters' that could lay the foundation of a new paradigm in cancer immunotherapy by creating clinical breakthroughs for safe and efficacious cancer cures.

Arsenite induces endothelial cell permeability increase through a reactive oxygen species-vascular endothelial growth factor pathway.

As a potent environmental oxidative stressor, arsenic exposure has been reported to exacerbate cardiovascular diseases and increase vascular endothelial cell monolayer permeability. However, the underlying mechanism of this effect is not well understood. In this paper, we test our hypothesis that reactive oxygen species (ROS)-induced vascular endothelial growth factor (VEGF) expression may play an important role in an arsenic-caused increase of endothelial cell monolayer permeability. The mouse brain vascular endothelial cell bEnd3 monolayer was exposed to arsenite for 1, 3, and 6 days. The monolayer permeability, VEGF protein release, and ROS generation were determined. In addition, VE-cadherin and zonula occludens-1 (ZO-1), two membrane structure proteins, were immunostained to elucidate the effects of arsenite on the cell-cell junction. The roles of ROS and VEGF in arsenite-induced permeability was determined by inhibiting ROS with antioxidants and immuno-depleting VEGF with a VEGF antibody. We observed that arsenite increased bEnd3 monolayer permeability, elevated the production of cellular ROS, and increased VEGF release. VE-cadherin and ZO-1 disruptions were also found in cells treated with arsenite. Furthermore, both antioxidant (N-acetyl cysteine and tempol) and the VEGF antibody treatments significantly lowered the arsenite-induced permeability of the bEnd3 monolayer as well as VEGF expression. VE-cadherin and ZO-1 disruptions were also diminished by N-acetyl cysteine and the VEGF antibody. Our data suggest that the increase in VEGF expression caused by ROS may play an important role in the arsenite-induced increase in endothelial cell permeability.

Complement-mediated inhibition of neovascularization reveals a point of convergence between innate immunity and angiogenesis.

Beyond its role in immunity, complement mediates a wide range of functions in the context of morphogenetic or tissue remodeling processes. Angiogenesis is crucial during tissue remodeling in multiple pathologies; however, the knowledge about the regulation of neovascularization by the complement components is scarce. Here we studied the involvement of complement in pathological angiogenesis. Strikingly, we found that mice deficient in the central complement component C3 displayed increased neovascularization in the model of retinopathy of prematurity (ROP) and in the in vivo Matrigel plug assay. In addition, antibody-mediated blockade of C5, treatment with C5aR antagonist, or C5aR deficiency in mice resulted in enhanced pathological retina angiogenesis. While complement did not directly affect angiogenesis-related endothelial cell functions, we found that macrophages mediated the antiangiogenic activity of complement. In particular, C5a-stimulated macrophages were polarized toward an angiogenesis-inhibitory phenotype, including the up-regulated secretion of the antiangiogenic soluble vascular endothelial growth factor receptor-1. Consistently, macrophage depletion in vivo reversed the increased neovascularization associated with C3- or C5aR deficiency. Taken together, complement and in particular the C5a-C5aR axes are potent inhibitors of angiogenesis.

Signal sequence as a determinant in expressing disulfide-stabilized single chain antibody variable fragments (sc-dsFv) against human VEGF.

Phage-displayed single chain variable fragment (scFv) libraries have been powerful tools in antibody engineering. But the scFv structures are frequently unstable due to the dissociation of the dimeric interface between the two variable domains. One solution is the sc-dsFv construct, where the single chain variable domain fragment is stabilized with an additional interface disulfide bond, leading to stable and homogeneous dimeric interface for the sc-dsFv structure. However, the phagemid system that is capable of effective expression for both sc-dsFv-pIII fusion proteins on phage surface and secreted non-fusion sc-dsFv in bacterial culture medium has not been demonstrated. In this work, a biological combinatorial approach was applied to optimize the signal sequence N-terminal to the sc-dsFv-pIII fusion protein encoded in a phagemid. The optimized sc-dsFv phage display systems were compatible with both the phage-based directed evolution procedure and the high throughput screening of the soluble sc-dsFv. The utility of the phagemid systems was demonstrated in generating anti-VEGF sc-dsFv with VEGF-binding affinity one order of magnitude higher than the corresponding scFv, due only to the interface disulfide bond in the sc-dsFv. Moreover, the protein stability of the sc-dsFv construct was unmatched by the corresponding scFv. These advantages of the sc-dsFv were gained through the interface disulfide bond of the sc-dsFv and the novel signal sequence in the phagemid.

VEGF in the muscular layer of placental blood vessels: immuno-expression in preeclampsia and intrauterine growth restriction and its association with the antioxidant status.

The pathophysiology of preeclampsia (PE), a disorder occurring in 5% of all pregnancies, remains largely unknown, but early placental hypoxia and oxidative stress are known to be involved in the mechanism of the syndrome. Maternal plasma and placental tissue samples were collected from PE, intrauterine growth restriction (IUGR), and normotensive pregnant patients. The immunohistochemical expression of vascular endothelial growth factor (VEGF), malondialdehyde (MDA) production and the activity of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase GSH-Px) were determined in the placental tissue. F2-isoprostane concentration and the ferric reducing ability of plasma (FRAP) were determined in maternal plasma. We found that the PE and IUGR groups showed a higher expression of VEGF in the muscular layer of fetal chorionic vessels. In addition, increased plasma F2 isoprostane levels and a significant reduction of FRAP in the plasma of PE women, as well as a lower activity of SOD in PE placentas and a higher activity of GSH-Px in IUGR placentas were found. Additionally, lower PlGF and higher sFlt1 levels were observed in the maternal plasma of PE and IUGR than control. We concluded that in a hypoxic environment, the placenta expresses VEGF in the muscular layer of fetal vessels. The development of PE could be related to the increased expression of VEGF, with decreased placental SOD activity and a decrease of both plasma F2-isoprostane and FRAP levels. In turn, the development of IUGR could be related to the association of decreased plasma FRAP levels and increased placental GSH-Px activity.

VEGF neutralizing antibody increases the therapeutic efficacy of vinorelbine for renal cell carcinoma.

Renal cell carcinoma (RCC) is currently one of the most treatment-resistant malignancies and affects approximately three in 10,000 people. The impact of this disease produces about 31,000 new cases in the United States per year; and 12,000 people in the United States alone die from RCC annually. Although several treatment strategies have been investigated for RCC, this cancer continues to be a therapeutic challenge. For this reason, the aim of our study is to develop a more effective combinational therapy to treat advanced RCC. We examined the effect of vinorelbine on the signalling pathways of two human renal cancer cell lines (A498 and 786-O) and also examined the in vivo effect of vinorelbine treatment alone and vinorelbine in combination with the anti-VEGF antibody 2C3 on A498 and 786-O tumour growth in nude mice. Tumour angiogenesis was measured by vWF staining, and apoptosis was determined by the TUNEL assay. We observed a significant tumour growth inhibition when using a combinational therapy of anti-VEGF antibody 2C3 and vinorelbine in both A498 and 786-O tumour-bearing mice. The results suggest a breakthrough treatment for advanced RCC.

Immunohistochemical aspects of endometrial glands in dysfunctional uterine hemorrhage.

The authors present a specific aspect of the modifications of the endometrium in dysfunctional uterine hemorrhages that is the behavior of the endometrial glands. These glands are studied from a immunohistochemical point of view, regarding both the normal endometrium (inclusively at the age of two years) and the endometrium in dysfunctional uterine hemorrhages. The antigens used were VGEF and PCNA. The result was a different reaction of the glandular structures to these antigens in the cases of patients with dysfunctional uterine hemorrhage.

Treating age-related macular degeneration - interaction of VEGF-antagonists with their target.

The neutralization of VEGF is the current treatment of choice for age-related macular degeneration. Current approaches include anti-VEGF-antibodies and -Fab Fragments, aptamers, soluble receptors (Traps) and siRNA. The molecular properties of VEGF and its antagonists are reviewed and the pathways of action of these substances are discussed.

Recommendations from the Spanish Oncology Genitourinary Group for the treatment of metastatic renal cancer.

For almost the last two decades, interleukin-2 and interferon-alpha have been the only systemic treatment options available for metastatic renal cell carcinoma. However, in recent years, five new targeted therapies namely sunitinib, sorafenib, temsirolimus, everolimus and bevacizumab have demonstrated clinical activity in these patients. With the availability of new targeted agents that are active in this disease, there is a need to continuously update the treatment algorithm of the disease. Due to the important advances obtained, the Spanish Oncology Genitourinary Group (SOGUG) has considered it would be useful to review the current status of the disease, including the genetic and molecular biology factors involved, the current predicting models for development of metastases as well as the role of surgery, radiotherapy and systemic therapies in the early- or late management of the disease. Based on this previous work, a treatment algorithm was developed.

Immunotherapy against angiogenesis-associated targets: evidence and implications for the treatment of malignant glioma.

Angiogenesis, the growth of new blood vessels from previously existing vasculature, is a requirement for tumor growth and metastasis. The first US FDA-approved drugs targeting angiogenesis have shown potential in the treatment of malignant gliomas. Immunotherapy as a treatment modality lends itself well to specifically targeting angiogenesis in tumors and may represent a powerful tool in the treatment of malignant gliomas. This review focuses on developments in immunotherapy targeting angiogenesis and tumor-vascular-specific endothelial cells using a variety of immunotherapeutic strategies including monoclonal antibodies and conjugated immunotoxins, as well as cellular, peptide, DNA and dendritic cell vaccines.

Tumor necrosis factor-mediated interactions between inflammatory response and tumor vascular bed.

Solid tumor therapy with chemotherapeutics greatly depends on the efficiency with which drugs are delivered to tumor cells. The typical characteristics of the tumor physiology promote but also appose accumulation of blood-borne agents. The leaky tumor vasculature allows easy passage of drugs. However, the disorganized vasculature causes heterogeneous blood flow, and together with the often-elevated interstitial fluid pressure, this state results in poor intratumoral drug levels and failure of treatment. Manipulation of the tumor vasculature could overcome these barriers and promote drug delivery. Targeting the vasculature has several advantages. The endothelial lining is readily accessible and the first to be encountered after systemic injection. Second, endothelial cells tend to be more stable than tumor cells and thus less likely to develop resistance to therapy. Third, targeting the tumor vasculature can have dual effects: (i) manipulation of the vasculature can enhance concomitant chemotherapy, and (ii) subsequent destruction of the vasculature can help to kill the tumor. In particular, tumor necrosis factor alpha is studied. Its action on solid tumors, both directly through tumor cell killing and destruction of the tumor vasculature and indirectly through manipulation of the tumor physiology, is complex. Understanding the mechanism of TNF and agents with comparable action on solid tumors is an important focus to further develop combination immunotherapy strategies.