Human vascular endothelial growth factor B: characterization of recombinant isoforms and generation of neutralizing monoclonal antibodies

An Anti-VEGF-B Antibody Reduces Abnormal Tumor Vasculature and Enhances the Effects of Chemotherapy

The vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs) are key regulators of blood vessel formation, including in tumors, where their deregulated function can promote the production of aberrant, leaky blood vessels, supporting tumor development. Here we investigated the VEGFR1 ligand VEGF-B, which we demonstrate to be expressed in tumor cells and in tumor stroma and vasculature across a range of tumor types. We examined the anti-VEGF-B-specific monoclonal antibody 2H10 in preclinical xenograft models of breast and colorectal cancer, in comparison with the anti-VEGF-A antibody bevacizumab. Similar to bevacizumab, 2H10 therapy was associated with changes in tumor blood vessels and intra-tumoral diffusion consistent with normalization of the tumor vasculature. Accordingly, treatment resulted in partial inhibition of tumor growth, and significantly improved the response to chemotherapy. Our studies indicate the importance of VEGF-B in tumor growth, and the potential of specific anti-VEGF-B treatment to inhibit tumor development, alone or in combination with established chemotherapies.

Simultaneous blockade of VEGF-B and IL-17A ameliorated diabetic kidney disease by reducing ectopic lipid deposition and alleviating inflammation response

The pathogenesis of diabetic kidney disease (DKD) is complicated. Current clinical treatments fail to achieve satisfactory efficacy in the prevention of DKD progression, it urgently needs novel and effective treatment for DKD. In this study, we firstly demonstrated that renal lipid metabolism abnormality and inflammation significantly changed in DKD conditions by mining public transcriptomic data of DKD patient samples. KEGG analysis further exhibited the critical role of vascular endothelial growth factor B (VEGF-B) and interleukin 17A (IL-17A) signal pathways in DKD progression, indicating that VEGF-B and IL-17A might be the promising targets for DKD treatment. Then the potential of a novel combination therapy, anti-VEGF-B plus anti-IL-17A antibody, was evaluated for DKD treatment. Our results demonstrated that simultaneous blockade of VEGF-B and IL-17A signaling with their neutralizing antibodies alleviated renal damage and ameliorated renal function. The therapeutic effectiveness was not only related to the reduced lipid deposition especially the neutral lipids in kidney but also associated with the decreased inflammation response. Moreover, the therapy alleviated renal fibrosis by reducing collagen deposition and the expression of fibronectin and α-SMA in kidney tissues. RNA-seq analysis indicated that differential expression genes (DEGs) in db/db mice were significantly clustered into lipid metabolism, inflammation, fibrosis and DKD pathology-related pathways, and 181 of those DEGs were significantly reversed by the combinatory treatment, suggesting the underlying mechanism of administration of anti-VEGF-B and anti-IL-17A antibodies in DKD treatment. Taken together, this study identified that renal lipid metabolism abnormality and inflammation were critically involved in the progression of DKD, and simultaneous blockade of VEGF-B and IL-17A signaling represents a potential DKD therapeutic strategy.

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.

Isotretinoin does not alter VEGF-A and VEGF-C levels: do retinoids behave differently in dose-dependent and/or in vivo/in vitro conditions?

BACKGROUND

It is seen that various forms of retinoids have different results on VEGF-A and VEGF-C levels when tested at different dosages, in different diseases and under different conditions such as in vivo or in vitro.

OBJECTIVE

To evaluate the effects of isotretinoin on VEGF-A and VEGF-C levels in humans.

METHODS

Blood samples at the third month of the patient group and blood samples of the control group were compared in terms of VEGF-A and VEGF-C concentrations.

RESULTS

No statistically significant difference was observed between the patient group and the control group in terms of VEGF-A and VEGF-C levels.

LIMITATIONS

Most of the patients discontinued treatment and could not reach the required number, the study was converted to case-control.

CONCLUSIONS

We think that 0.5 mg/kg/day isotretinoin has no effect on blood concentrations of VEGF-A and VEGF-C in humans. Therefore, there is a need for studies using isotretinoin in different doses and durations in humans in order to better evaluate its effects.

Effect of isotretinoin (13-cis-retinoic acid) on levels of soluble VEGF receptors (sVEGFR1, sVEGFR2, sVEGFR3) in patients with acne vulgaris

Background/aim: The effect of isotretinoin on soluble VEGFRs has not been previously investigated. This study evaluate the effects of isotretinoin (13-cis-retinoic acid) on soluble VEGFR1 (sVEGFR1), soluble VEGFR2 (sVEGFR2) and soluble VEGFR3 (sVEGFR3).Methods: The study included 38 patients (28 females, 10 males) receiving systemic isotretinoin treatment and 38 healthy individuals (28 females, 10 males) with similar age and gender characteristics. The blood samples of the patient group at third months and blood samples of the control group were compared in terms of sVEGFR1, sVEGFR2 and sVEGFR3 concentrations.Results: It was significant that sVEGFR1 was low and sVEGFR3 was high in patients receiving isotretinoin (p: .038, p: .021, respectively). There was no significant change in sVEGFR2 levels between the groups (p: .519).Conclusions: We think that the effect of isotretinoin on sVEGFR1, sVEGFR2 and sVEGFR3 may be secondary to its effects on the VEGF family. However, after clarifying the effect of isotretinoin on the VEGF family, we think that it can be used in some tumors and vascular diseases.

Vascular endothelial growth factor-B: Impact on physiology and pathology

Angiogenesis plays an important role in controlling tissue development and maintaining normal tissue function. Dysregulated angiogenesis is implicated in the pathogenesis of a variety of diseases, particularly diabetes, cancers, and neurodegenerative disorders. As the major regulator of angiogenesis, the vascular endothelial growth factor (VEGF) family is composed of a group of crucial members including VEGF-B. While the physiological roles of VEGF-B remain debatable, increasing evidence suggests that this protein is able to protect certain type of cells from apoptosis under pathological conditions. More importantly, recent studies reveal that VEGF-B is involved in lipid transport and energy metabolism, implicating this protein in obesity, diabetes and related metabolic complications. This article summarizes the current knowledge and understanding of VEGF-B in physiology and pathology, and shed light on the therapeutic potential of this crucial protein.

The VEGF signaling pathway in cancer: the road ahead

The vascular endothelial growth factor (VEGF) family of soluble protein growth factors consists of key mediators of angiogenesis and lymphangiogenesis in the context of tumor biology. The members of the family, VEGF-A (also known as VEGF), VEGF-B, VEGF-C, VEGF-D, and placenta growth factor (PIGF), play important roles in vascular biology in both normal physiology and pathology. The generation of a humanized neutralizing antibody to VEGF-A (bevacizumab, also known as Avastin) and the demonstration of its benefit in numerous human cancers have confirmed the merit of an anti-angiogenesis approach to cancer treatment and have validated the VEGF-A signaling pathway as a therapeutic target. Other members of the VEGF family are now being targeted, and their relevance to human cancer and the development of resistance to anti-VEGF-A treatment are being evaluated in the clinic. Here, we discuss the potential of targeting VEGF family members in the diagnosis and treatment of cancer.

Vascular endothelial growth factor (VEGF), VEGF receptors and their inhibitors for antiangiogenic tumor therapy

Vascular endothelial growth factor (VEGF) and its receptors (VEGFRs) have crucial roles in both physiological and pathological angiogenesis. The VEGF family consists of VEGF-A (generally called VEGF), VEGF-B, VEGF-C, VEGF-D, and placental growth factor (PlGF). These peptides show different affinities for VEGFR subtypes. VEGFR exists as three subtypes, VEGFR-1, VEGFR-2, and VEGFR-3, and is structurally related to platelet-derived growth factor receptors. All subtypes possess seven immunoglobulin-like domains in the extracellular region and a tyrosine kinase domain in the intracellular region. VEGF-A activates VEGFR-1 and VEGFR-2, whereas VEGF-B and PlGF bind to only VEFGR-1. VEGF-C and VEGF-D only bind to VEGFR-3. VEGFR-1 (fms-like tyrosine kinase-1, Flt-1) negatively regulates embryonic vasculogenesis and is involved in tumor angiogenesis via activation of monocytes and macrophages. VEGFR-2 (KDR in humans or Flk-1 in mice) is predominantly responsible for both embryonic vasculogenesis and tumor angiogenesis. In contrast, VEGFR-3 (Flt-4) regulates lymphangiogenesis. Consequently, VEGF-A and VEGFR-2 are currently the main targets for antiangiogenic therapy. Bevacizumab is a humanized monoclonal antibody against VEGF-A, and aflibercept (VEGF-Trap) is a soluble fusion protein of the extracelluar domain of VEGFR-1 and VEGFR-2 and the Fc region of immunoglobulin G (IgG). They neutralize VEGF-A, resulting in prevention of tumor angiogenesis. VEGFR tyrosine kinase inhibitors such as sunitinib and sorafenib are also effective in antiangiogenic tumor therapy by inhibiting VEGFR signaling. Anti-VEGF drugs are a promising therapy for cancer patients.

Structural insights into the binding of vascular endothelial growth factor-B by VEGFR-1(D2): recognition and specificity

The formation of blood vessels (angiogenesis) is a highly orchestrated sequence of events involving crucial receptor-ligand interactions. Angiogenesis is critical for physiological processes such as development, wound healing, reproduction, tissue regeneration, and remodeling. It also plays a major role in sustaining tumor progression and chronic inflammation. Vascular endothelial growth factor (VEGF)-B, a member of the VEGF family of angiogenic growth factors, effects blood vessel formation by binding to a tyrosine kinase receptor, VEGFR-1. There is growing evidence of the important role played by VEGF-B in physiological and pathological vasculogenesis. Development of VEGF-B antagonists, which inhibit the interaction of this molecule with its cognate receptor, would be important for the treatment of pathologies associated specifically with this growth factor. In this study, we present the crystal structure of the complex of VEGF-B with domain 2 of VEGFR-1 at 2.7 A resolution. Our analysis reveals that each molecule of the ligand engages two receptor molecules using two symmetrical binding sites. Based on these interactions, we identify the receptor-binding determinants on VEGF-B and shed light on the differences in specificity towards VEGFR-1 among the different VEGF homologs.

Vascular endothelial growth factor B controls endothelial fatty acid uptake

The vascular endothelial growth factors (VEGFs) are major angiogenic regulators and are involved in several aspects of endothelial cell physiology. However, the detailed role of VEGF-B in blood vessel function has remained unclear. Here we show that VEGF-B has an unexpected role in endothelial targeting of lipids to peripheral tissues. Dietary lipids present in circulation have to be transported through the vascular endothelium to be metabolized by tissue cells, a mechanism that is poorly understood. Bioinformatic analysis showed that Vegfb was tightly co-expressed with nuclear-encoded mitochondrial genes across a large variety of physiological conditions in mice, pointing to a role for VEGF-B in metabolism. VEGF-B specifically controlled endothelial uptake of fatty acids via transcriptional regulation of vascular fatty acid transport proteins. As a consequence, Vegfb(-/-) mice showed less uptake and accumulation of lipids in muscle, heart and brown adipose tissue, and instead shunted lipids to white adipose tissue. This regulation was mediated by VEGF receptor 1 and neuropilin 1 expressed by the endothelium. The co-expression of VEGF-B and mitochondrial proteins introduces a novel regulatory mechanism, whereby endothelial lipid uptake and mitochondrial lipid use are tightly coordinated. The involvement of VEGF-B in lipid uptake may open up the possibility for novel strategies to modulate pathological lipid accumulation in diabetes, obesity and cardiovascular diseases.

Role and therapeutic potential of VEGF in the nervous system

The development of the nervous and vascular systems constitutes primary events in the evolution of the animal kingdom; the former provides electrical stimuli and coordination, while the latter supplies oxygen and nutrients. Both systems have more in common than originally anticipated. Perhaps the most striking observation is that angiogenic factors, when deregulated, contribute to various neurological disorders, such as neurodegeneration, and might be useful for the treatment of some of these pathologies. The prototypic example of this cross-talk between nerves and vessels is the vascular endothelial growth factor or VEGF. Although originally described as a key angiogenic factor, it is now well established that VEGF also plays a crucial role in the nervous system. We describe the molecular properties of VEGF and its receptors and review the current knowledge of its different functions and therapeutic potential in the nervous system during development, health, disease and in medicine.

Crystal structure of vascular endothelial growth factor-B in complex with a neutralising antibody Fab fragment

Vascular endothelial growth factor (VEGF) B effects blood vessel formation by binding to VEGF receptor 1. To study the specifics of the biological profile of VEGF-B in both physiological and pathological angiogenesis, a neutralising anti-VEGF-B antibody (2H10) that functions by inhibiting the binding of VEGF-B to VEGF receptor 1 was developed. Here, we present the structural features of the 'highly ordered' interaction of the Fab fragment of this antibody (Fab-2H10) with VEGF-B. Two molecules of Fab-2H10 bind to symmetrical binding sites located at each pole of the VEGF-B homodimer, giving a unique U-shaped topology to the complex that has not been previously observed in the VEGF family. VEGF-B residues essential for binding to the antibody are contributed by both monomers of the cytokine. Our detailed analysis reveals that the neutralising effect of the antibody occurs by virtue of the steric hindrance of the receptor-binding interface. These findings suggest that functional complementarity between VEGF-B and 2H10 can be harnessed both in analysing the therapeutic potential of VEGF-B and as an antagonist of receptor activation.

Correlations of the expression of vascular endothelial growth factor B and its isoforms in hepatocellular carcinoma with clinico-pathological parameters

BACKGROUND

The vascular endothelial growth factor (VEGF) is involved in the growth of cancer cells through angiogenesis. At present the role of VEGF-B has not been clarified completely. We investigated correlations of the expression of VEGF-B and its isoforms, VEGF-B167 and VEGF-B186, by alternative splicing in hepatocellular carcinoma (HCC) with the pathological findings and prognosis.

METHODS

Forty-eight patients with HCC were investigated. We examined the mRNA expression of total VEGF-B, VEGF-B167 and VEGF-B186 in primary HCC and non-cancerous tissues using quantitative real-time reverse transcription polymerase chain reaction (RT-PCR) analysis.

RESULTS

In 16 (33.3%) of 48 HCCs, the expression of total VEGF-B increased compared with the corresponding non-cancerous liver tissues. Regarding the isoforms, the expression of VEGF-B167 and VEGF-B186 was increased in 17 (35.4%) of 48 and 33 (68.75%) of 48 HCCs, respectively. Cases with high expression level of total VEGF-B in HCC significantly correlated with the advanced pathological stage (P < 0.018), tumor multiplicity (P < 0.033), vascular invasion (P < 0.045) and lack of capsule formation (P < 0.027). The result in VEGF-B167 was similar to total VEGF-B.

CONCLUSIONS

Our results indicated that the expression of VEGF-B is correlated with tumor growth and invasiveness in HCC. VEGF-B167 seemed to be the clinically dominant isoform.

VEGF-B inhibits apoptosis via VEGFR-1-mediated suppression of the expression of BH3-only protein genes in mice and rats

Despite its early discovery and high sequence homology to the other VEGF family members, the biological functions of VEGF-B remain poorly understood. We revealed here a novel function for VEGF-B as a potent inhibitor of apoptosis. Using gene expression profiling of mouse primary aortic smooth muscle cells, and confirming the results by real-time PCR using mouse and rat cell lines, we showed that VEGF-B inhibited the expression of genes encoding the proapoptotic BH3-only proteins and other apoptosis- and cell death-related proteins, including p53 and members of the caspase family, via activation of VEGFR-1. Consistent with this, VEGF-B treatment rescued neurons from apoptosis in the retina and brain in mouse models of ocular neurodegenerative disorders and stroke, respectively. Interestingly, VEGF-B treatment at the dose effective for neuronal survival did not cause retinal neovascularization, suggesting that VEGF-B is the first member of the VEGF family that has a potent antiapoptotic effect while lacking a general angiogenic activity. These findings indicate that VEGF-B may potentially offer a new therapeutic option for the treatment of neurodegenerative diseases.

Vascular endothelial growth factor family of ligands and receptors: review

VEGF signaling often represents a critical rate-limiting step in physiological angiogenesis. The VEGF family comprises seven secreted glycoproteins that are designated VEGF-A, VEGF-B, VEGF-C, VEGF-D, VEGF-E, placental growth factor (PlGF) and VEGF-F. The VEGF family members bind their cognate receptors. The receptors identified so far are designated VEGFR-1, VEGFR-2, VEGFR-3 and the neuropilins (NP-1 and NP-2). We review in this article the biology of the VEGF ligands and the receptors.

Crystal structure of human vascular endothelial growth factor-B: identification of amino acids important for receptor binding

The development of blood vessels (angiogenesis) is critical throughout embryogenesis and in some normal postnatal physiological processes. Pathological angiogenesis has a pivotal role in sustaining tumour growth and chronic inflammation. Vascular endothelial growth factor-B (VEGF-B) is a member of the VEGF family of growth factors that regulate blood vessel and lymphatic angiogenesis. VEGF-B is closely related to VEGF-A and placenta growth factor (PlGF), but unlike VEGF-A, which binds to two receptor tyrosine kinases VEGFR-1 (Flt-1) and VEGFR-2 (Flk-1/KDR), VEGF-B and PlGF bind to VEGFR-1 and not VEGFR-2. There is growing evidence of a role for VEGF-B in physiological and pathological blood vessel angiogenesis. VEGF-B may provide novel therapeutic strategies for the treatment of vascular disease and be a potential therapeutic target in aberrant vessel formation. To help understand at the molecular level the differential receptor binding profile of the VEGF family of growth factors we have determined the crystal structure of human VEGF-B(10-108) at 2.48 Angstroms resolution. The overall structure is very similar to that of the previously determined cysteine-knot motif growth factors: VEGF-A, PlGF and platelet-derived growth factor-B (PDGF-B). We also present a predicted model for the association of VEGF-B with the second domain of its receptor, VEGFR-1. Based on this interaction and the present structural data of the native protein, we have identified several putative residues that could play an important role in receptor recognition and specificity.

The biology of vascular endothelial growth factor-B (VEGF-B)

The formation of new blood vessels (angiogenesis) is critical for both embryonic development and a variety of normal postnatal physiological processes. Various pathological processes, most notably tumour growth and chronic inflammation, are also known to be dependent on the new vessel formation. Amongst the variety of factors that contribute to the regulation of this complex process, vascular endothelial growth factor (VEGF or VEGF-A) is arguably the most well characterised. The VEGF family of growth factors is now known to comprise of VEGF-A plus four additional members, including VEGF-B. In contrast to VEGF-A, surprisingly little is known about the precise biological role of VEGF-B. Unlike VEGF-A, which binds to the two receptor tyrosine kinases VEGFR-1 (Flt-1) and VEGFR-2 (Flk-1/KDR), VEGF-B binds only to VEGFR-1 and the functional significance of VEGFR-1 signalling has remained problematic. More recently, however, evidence has emerged suggesting a key role for VEGFR-1 signalling in pathological angiogenesis and this has raised the possibility that, like VEGF-A, VEGFR-1 specific ligands such as VEGF-B may provide for novel therapeutic strategies and/or represent new therapeutic targets. Here we review current knowledge of the biology of VEGF-B. We note that although analysis to date, including expression profiling and the generation of gene targetted mice, has provided only limited insights, future studies using recently generated recombinant proteins and antagonist monoclonal antibodies should provide for a more comprehensive understanding.

Transgenic Overexpression of Vascular Endothelial Growth Factor-B Isoforms by Endothelial Cells Potentiates Postnatal Vessel Growth In Vivo and In Vitro

Vascular endothelial growth factors (VEGFs) play significant roles in endothelial growth, survival, and function, and their potential use as therapeutic agents to promote the revascularization of ischemic tissues in being avidly explored. VEGF-A has received most attention, as it is a potent stimulator of vascular growth. Results in clinical trials of VEGF-A as a therapeutic agent have fallen short of high expectations because of serious edematous side effects caused by its activity in promoting vascular permeability. VEGF-B, a related factor, binds some of the VEGF-A receptors but not to VEGF receptor 2, which is implicated in the vascular permeability promoting activity of VEGF-A. Despite little in vitro evidence to date for the ability of Vegf-B to directly promote angiogenesis, recent data indicate that it may promote postnatal vascular growth in mice, suggesting that it may have potential therapeutic application. We have specifically studied the effects of VEGF-B on vascular growth in vivo and on angiogenesis in vitro by analyzing transgenic mice in which individual isoforms ( VEGFB 167 Tg and VEGFB 186 Tg) of VEGF-B are overexpressed in endothelial cells. VEGFB 167 Tg and VEGFB 186 Tg mice displayed enhanced vascular growth in the Matrigel assay in vivo and during cutaneous wound healing. In the aortic explant assay, explants from VEGFB 167 Tg and VEGFB 186 Tg mice displayed elevated vascular growth, suggesting a direct effect of VEGF-B isoforms in potentiating angiogenesis. These data support the use of VEGF-B as a therapeutic agent to promote vascular growth, in part, by potentiating angiogenesis. Furthermore, the lack of vascular permeability activity associated with either transgenic overexpression of the VEGF-B gene in endothelial cells or application of VEGF-B protein to the skin of mice in the Miles assay indicates that use of VEGF-B as a therapy should not be associated with edematous side effects.

A survey of the year 2002 commercial optical biosensor literature

We have compiled 819 articles published in the year 2002 that involved commercial optical biosensor technology. The literature demonstrates that the technology's application continues to increase as biosensors are contributing to diverse scientific fields and are used to examine interactions ranging in size from small molecules to whole cells. Also, the variety of available commercial biosensor platforms is increasing and the expertise of users is improving. In this review, we use the literature to focus on the basic types of biosensor experiments, including kinetics, equilibrium analysis, solution competition, active concentration determination and screening. In addition, using examples of particularly well-performed analyses, we illustrate the high information content available in the primary response data and emphasize the impact of including figures in publications to support the results of biosensor analyses.