Inhibition Of VEGF Signaling Research Articles

Abstract Mo090: Altered Cardiac Cell Populations in Hypoplastic Left Heart Syndrome

Background: Congenital heart disease (CHD) affects ~1% of infants. Hypoplastic left heart syndrome (HLHS), a severe form of CHD in which the left ventricle is underdeveloped, is associated by a 15% incidence of heart failure by 6 years of age. Only 6% of HLHS patients have a genetic cause identified on exome sequencing, limiting the ability of patients to receive a diagnosis and potentially benefit from targeted treatments. Hypothesis: Novel HLHS genes are differentially expressed in HLHS cardiac tissues, or in cells with differential abundance in HLHS hearts. Goals: To use single nucleus RNA sequencing of HLHS patient cardiac tissues to identify candidate HLHS genes. Methods: Single nucleus RNA sequencing (nucSeq) was performed on paired left and right ventricular tissues (LV, RV) from 9 participants with HLHS. Left ventricular cardiac tissues from children (4) and adults (12) without CHD were used for comparison. Filtering with CellBender and Solo were used to remove low-quality nuclei. Analysis was performed in R using the Seurat package. Results: HLHS LV tissues had a higher proportion of cardiomyocytes than pediatric or adult control tissues, (78.7% vs 64.1%, p=0.005; 78.7 % vs 47.0%, p=1.8E-08, respectively), and a lower proportion of mural cells (3.1% vs 9.3%, p=3.9E-05; 3.1 % vs 23.5%, p=7.3E-15, respectively). By contrast, there were similar proportions of endothelial cells in the HLHS, pediatric and adult tissues (7.1%, 8.8% and 7.9%, respectively; p=0.56). Within HLHS tissues, the LV had a higher proportion of cardiomyocytes than the RV (78.7% vs 51.2%, p=4.8E-04) while the proportion of endothelial cells were similar in the LV and RV (7.3% and 9.1%, respectively; p=0.33). LV tissues from HLHS participants 2-18 years of age had fewer capillary endothelial cells than pediatric controls (31.2% vs 57.8%, p=0.001), and gene markers of HLHS endothelial cells included PBX1 , which is required for Hox D-3 mediated angiogenesis, as well as ARHGAP26 and RORA, inhibitors of VEGF signaling. Conclusion: HLHS cardiac tissues have a higher proportion of cardiomyocytes in the LV despite a smaller chamber size. Differences in gene expression that accompany the differences in cell proportion could identify novel HLHS genes as well as potential therapeutic targets.

Azithromycin induces neurotoxicity in zebrafish by interfering with the VEGF/Notch signaling pathway

Azithromycin (AZM) is a widely used antibiotic in both human and veterinary medicine, and its use has significantly increased during the COVID-19 pandemic. However, potential adverse effects of AZM on aquatic organisms have not been well studied. In this study, we explored the neurotoxicity of AZM in zebrafish and delved into its underlying mechanisms. Our results showed that AZM exposure resulted in a spectrum of detrimental effects in zebrafish, encompassing abnormal behaviors, damaged neuronal development, aberrant lateral line nervous system development, vascular malformations and perturbed expression of genes related to neural development. Moreover, we observed a concentration-dependent exacerbation of these neurotoxic manifestations with increasing AZM concentrations. Notably, AZM induced excessive cell apoptosis and oxidative stress damage. In addition, alterations in the expression levels of the genes involved in the VEGF/Notch signaling pathway were evident in AZM-exposed zebrafish. Consequently, we hypothesize that AZM may induce neurotoxicity by influencing the VEGF/Notch signaling pathway. To validate this hypothesis, we introduced a VEGF signaling inhibitor, axitinib, and a Notch signaling agonist, valproic acid, alongside AZM exposure. Remarkably, the administration of these rescue compounds significantly mitigated the neurotoxic effects induced by AZM. This dual verification provides compelling evidence that AZM indeed induces neurotoxicity during the early developmental stages of zebrafish, primarily through its interference with the VEGF/Notch pathway. Innovatively, our study reveals the molecular mechanism of AZM-induced neurotoxicity from the perspective of the close connection between blood vessels and nervous system. These findings provide new insights into the potential mechanisms underlying the neurotoxic effect of antibiotics and highlight the need for further investigation into the ecotoxicological effects of antibiotics on aquatic organisms and the potential risks to human health.

The ubiquitin-like protein FAT10 in hepatocellular carcinoma cells limits the efficacy of anti-VEGF therapy

IntroductionThe efficacy of anti-vascular endothelial growth factor (VEGF) therapy is limited. However, the key factors involved in limiting the efficacy of anti-VEGF therapy and the underlying mechanisms remain unclear. ObjectivesTo investigate the effects and mechanisms of human leukocyte antigen F locus-adjacent transcript 10 (FAT10), a ubiquitin-like protein, in limiting the efficacy of anti-VEGF therapy in hepatocellular carcinoma (HCC) cells. MethodsFAT10 was knocked out in HCC cells using the clustered regularly interspaced short palindromic repeats (CRISPR)–CRISPR-associated protein 9 technology. Bevacizumab (BV), an anti-VEGF monoclonal antibody, was used to evaluate the efficacy of anti-VEGF therapy in vivo. Mechanisms of FAT10 action were assessed by RNA sequencing, glutathione S-transferase pulldown assays and in vivo ubiquitination assays. ResultsFAT10 accelerated VEGF-independent angiogenesis in HCC cells which limited BV efficacy and BV-aggravated hypoxia and inflammation promoted FAT10 expression. FAT10 overexpression increased levels of proteins involved in several signaling pathways in HCC cells, resulting in upregulation of VEGF and multiple non-VEGF proangiogenic factors. Upregulation of multiple FAT10-mediated non-VEGF signals compensated for the inhibition of VEGF signaling by BV, enhancing VEGF-independent angiogenesis and promoting HCC growth. ConclusionsOur preclinical findings identify FAT10 in HCC cells as a key factor limiting the efficacy of anti-VEGF therapy and elucidate its underlying mechanisms. This study provides new mechanistic insights into the development of antiangiogenic therapies.

NOVA-II: Part 2 study to evaluate the safety and efficacy of OQL011 on VEGF inhibitor-associated hand-foot skin reaction in patients with cancer.

TPS741 Background: Hand-foot skin reaction (HFSR) is associated with the use of multi-targeted tyrosine kinase inhibitors sharing vascular endothelial growth factor receptor inhibitor (VEGFRi) activity (e.g., cabozantinib, regorafenib, sorafenib, sunitinib). HFSR results from impaired vascular repair mechanisms from inhibition of VEGF signaling and is characterized by painful palmoplantar lesions that may impact the quality of life and consistent dosing of anticancer agents. NOVA-II is a two-part, double-blind, randomized controlled trial evaluating OQL011, a nitroglycerin (NTG) topical ointment. Part 1 enrolled 31 subjects and studied OQL011 0.2% NTG for Grade ≥2 NCI CTCAE v5.0 palmar-plantar erythrodysesthesia (PPE). Part 1 safety and pharmacokinetic data support the continuance of NOVA-II, Part 2 dose-ranging study. The Part 1 inclusion criteria and primary endpoint were based on NCI CTCAE PPE. A unique investigator global assessment (IGA) was evaluated in Part 1 for HFSR severity (Grades 0-4) and has been revised utilizing Part 1 data for use as the primary endpoint for Part 2. We hypothesize that OQL011 containing NTG, a nitric oxide donor releasing free nitric oxide and activating guanylate cyclase in skin vessels, will mitigate HFSR symptoms and disease severity via local upregulation of the VEGF/VEGFR signaling pathways. Methods: NOVA-II Part 2 is a global, dose-ranging phase 2, double-blind, randomized controlled trial to evaluate the safety and efficacy of 3 doses of OQL011 (0.1%, 0.2%, and 0.5% NTG) compared to vehicle control for the treatment of moderate to severe VEGFRi associated HFSR. Part 2 will enroll up to 140 patients (randomized 1:1:1:1; vehicle: OQL011@ 0.1%: 0.2%: 0.5% NTG) with IGA Grade ≥3 (IGA scale 0-4). Subjects will apply the study drug (i.e., OQL011 or vehicle) to palmar and plantar surfaces TID and will be evaluated at Visit 1 (Day 0), Visit 2 (Day 14), and Visit 3 (Day 28). The primary endpoint is the proportion of patients achieving an IGA Grade ≤1 at Visit 2 (Day 14). A superiority test will be performed to compare each of the OQL011 doses to the vehicle, and the study drug exposure-response relationship will be explored. The correlation between IGA and NCI CTCAE v5.0 PPE, patient-reported outcomes including a numerical pain rating scale (NPRS), and Hand-foot Quality of Life (HF-QoL) questionnaire will be measured. Pharmacokinetics will be evaluated in a subset of subjects randomized 2:2:2:1, with 6 patients in each of the 3 OQL011 dose level groups and 3 patients in the vehicle group. PK samples will be collected on Day 0 at pre-dose, 5 min, 15 min, 30 min, 45 min, 1 h, 1.5 h, 2 h, 4 h, 6 h, and 8 h, after the first application of investigational drugs. Study enrollment for Part 2 is currently ongoing in the United States, India, and China. (NCT04088318) Clinical trial information: NCT04088318 .

Exploring the Past, Present, and Future of Anti-Angiogenic Therapy in Glioblastoma.

Glioblastoma, a WHO grade IV astrocytoma, constitutes approximately half of malignant tumors of the central nervous system. Despite technological advancements and aggressive multimodal treatment, prognosis remains dismal. The highly vascularized nature of glioblastoma enables the tumor cells to grow and invade the surrounding tissue, and vascular endothelial growth factor-A (VEGF-A) is a critical mediator of this process. Therefore, over the past decade, angiogenesis, and more specifically, the VEGF signaling pathway, has emerged as a therapeutic target for glioblastoma therapy. This led to the FDA approval of bevacizumab, a monoclonal antibody designed against VEGF-A, for treatment of recurrent glioblastoma. Despite the promising preclinical data and its theoretical effectiveness, bevacizumab has failed to improve patients' overall survival. Furthermore, several other anti-angiogenic agents that target the VEGF signaling pathway have also not demonstrated survival improvement. This suggests the presence of other compensatory angiogenic signaling pathways that surpass the anti-angiogenic effects of these agents and facilitate vascularization despite ongoing VEGF signaling inhibition. Herein, we review the current state of anti-angiogenic agents, discuss potential mechanisms of anti-angiogenic resistance, and suggest potential avenues to increase the efficacy of this therapeutic approach.

Sulfamethoxazole induces brain capillaries toxicity in zebrafish by up-regulation of VEGF and chemokine signalling

Sulfamethoxazole (SMX) is a widespread broad-spectrum bacteriostatic antibiotic. Its residual is frequently detected in the water and may therefore bioaccumulate in the brain of aquatic organisms via blood circulation. Brain capillaries toxicity is very important for brain development. However, little information is available in the literature to show the toxicity of SMX to brain development. To study the SMX’s brain toxic effects and the related mechanisms, we exposed zebrafish embryos to SMX at different concentrations (0 ppm, 1 ppm, 25 ppm, 100 ppm and 250 ppm) and found that high concentration (250 ppm) of SMX would not only caused an abnormal in malformation rate, hatching rate, body length and survival rate of zebrafish embryos, but also lead to brain oedema. In addition, SMX also induced cerebral ischaemia, aggravates oxidative stress, and changes genes related to oxidative stress (sod1, cat, gpx4, and nrf2). Furthermore, ischaemia caused by SMX could promote ectopic angiogenesis in brain via activating the angiogenesis-related genes (vegfab, cxcr4a, cxcl12b) from 24 h to 53 h. Inhibition of VEGF signalling by SU5416, or inhibition of chemokine downstream PI3K signalling by LY294002, could rescue the brain capillaries toxicity and brain oedema induced by SMX. Our results provide new evidence for the brain toxicity of SMX and its residual danger in the environment and aquatic organisms.

Part 1 results from NOVA-II, a randomized, double-blind, vehicle-controlled phase II study evaluating the safety and efficacy of OQL011 on VEGFR inhibitor associated hand-foot skin reaction in cancer patients.

TPS396 Background: Hand-foot skin reaction (HFSR) is associated with the use of multi-targeted tyrosine kinase inhibitors sharing vascular endothelial growth factor receptor inhibitory (VEGFRi) activity (e.g., cabozantinib, regorafenib, sorafenib, sunitinib). HFSR affects the palms and soles with edema, erythema, hyperkeratosis, pain, and bullae/blisters impacting quality-of-life, activities of daily living, and consistent VEGFRi dosing. HFSR incidence differs among VEGFRi, ranging from 5-69% (all grades) and 1-19% (grade 3). Topical urea has marginal benefit, and to date, there are no regulatory authority approved HFSR treatments. The pathogenesis of HFSR has been partially associated with impaired vascular repair mechanisms resulting from inhibition of VEGF signaling. Nitric oxide (NO) has been reported to induce VEGF upregulation at a moderate concentration. We hypothesized that topical stimulation of VEGF signaling through OQL011, an NO donor, will safely and effectively mitigate HFSR. Methods: NOVA-II is a phase 2, double-blind, randomized vehicle-controlled trial evaluating the safety and efficacy of OQL011 for the treatment of moderate to severe HFSR. Subjects receiving a VEGFRi (either mono- or combination therapy) and have Grade ≥2 HFSR per NCI CTCAE v5.0 for palmar plantar erythrodysesthesia (PPE) were eligible. For Part 1, 31 subjects were randomized (2:1) and received 0.2% OQL011 topical ointment or vehicle TID for 6 weeks. The primary endpoint is the proportion of patients who achieve an NCI CTCAE v5.0 for PPE Grade 0 or 1 by Week 3. An investigator global assessment (IGA) scale is being developed to assess HFSR recovery, and a secondary endpoint will measure the proportion of patients who have improvement in HFSR severity and achieve an IGA score of clear (0) or almost clear (1) by Week 3 and/or Week 6. A Chi-square test will be used to detect a difference between the treatment arm and the vehicle-control arm. Additionally, the IGA score will be validated by assessing the inter- & intra-rater reliability. The correlation between IGA, NCI CTCAE v5.0 for PPE, and patient outcomes including Visual Analog Scale of Pain, HFSR Quality of Life questionnaire will also be reported. This study began enrolling patients in December 2019 and completed the last patient Visit in August 2021. Data lock, unblinding and data analysis will be completed by mid-November. Clinical trial information: NCT04088318.

Roles of glomerular endothelial hyaluronan in the development of proteinuria.

Vascular endothelial cells are covered with glycocalyx comprising heparan sulfate, hyaluronan, chondroitin sulfate, and associated proteins. Glomerular endothelial glycocalyx is involved in protecting against induction of proteinuria and structural damage, but the specific components in glycocalyx that represent therapeutic targets remain unclear. Anti‐vascular endothelial growth factor (VEGF) therapy is associated with an increased risk of glomerular endothelial injury. This study investigated whether hyaluronan could provide a therapeutic target to protect against proteinuria. We conducted ex vivo and in vivo experiments to explore the effects of degrading glomerular hyaluronan by administering hyaluronidase and of supplementation with hyaluronan. We investigated hyaluronan expression using biotin‐labeled hyaluronan‐binding protein (HABP) in human kidney specimens or serum hyaluronan in endothelial injuries under inhibition of VEGF signaling. We directly demonstrated hyaluronan in glomerular endothelial layers using HABP staining. Ex vivo and in vivo experiments showed the development of proteinuria after digestion of hyaluronan in glomerular capillaries. Supplementation with hyaluronan after hyaluronidase treatment suppressed proteinuria. Mice in the in vivo study developed albuminuria after intraperitoneal injection of hyaluronidase with decreased glomerular hyaluronan and increased serum hyaluronan. In human kidneys with endothelial cell dysfunction and proteinuria due to inhibition of VEGF, glomerular expression of hyaluronan was reduced even in normal‐appearing glomeruli. Serum hyaluronan levels were elevated in patients with pre‐eclampsia with VEGF signaling inhibition. Our data suggest that hyaluronan itself plays crucial roles in preventing proteinuria and preserving the integrity of endothelial cells. Hyaluronan could provide a therapeutic target for preventing glomerular endothelial glycocalyx damage, including VEGF signaling inhibition.

VEGFR-Mediated Cytotoxic Activity of Pulicaria undulata Isolated Metabolites: A Biological Evaluation and In Silico Study.

Natural products play a remarkable role not only in the synthesis, design, and discovery of new drugs but also as the most prominent source of drugs and bioactive substances. Adding to the search for new sources of safe innovative antitumor drugs, here we reported a phytochemical study on Pulicaria undulata which revealed promising antiangiogenic agents. Six compounds were isolated and identified as xanthoxyline (1), stigmasterol (2), oleanolic acid (3), salvigenin (4), rhamnetin (5) and dihydroquercetin-4′-methyl ether (6) using nuclear magnetic resonance (NMR) spectroscopic techniques. Compound 3 and 4 are first reported in Pulicaria genus. Both the extract and isolated compounds were evaluated for in vitro antiproliferative activity against breast cancer cell line (MCF-7). In vivo antiproliferative activity against Ehrlich’s ascites carcinoma (EAC) were also assessed. The P. undulata extract and isolates showed significant reduction in tumor weight, decreased both serum vascular endothelial growth factor B (VEGF-B) levels and vascular endothelial growth factor receptor 2 (VEGFR-2) expression significantly compared to the control EAC group, suggesting an antiangiogenic activity through the inhibition of VEGF signaling. Besides, they displayed reduction in CD34 expression, confirming their antiangiogenic effect. Moreover, the potential affinity of isolated compounds to human estrogen nuclear receptor-alpha (hER-α), the most recognized modulator of VEGFR-2 expression, was virtually estimated through molecular modeling studies. The most promising activity profiles were assigned to the investigated flavonoids, compounds 4–6, as well as the alkyl-phenylketone, compound 1. Additionally, these four top active compounds showed respective high to intermediate docking scores while possessing preferential binding with hER-α critical pocket residues. Based on the provided data, these isolated compounds illustrated promising inhibitors of VEGF-stimulated angiogenesis, which could be a possible mechanism for their anticancer activity.

Inhibition of peripheral VEGF signaling rapidly reduces leucocyte obstructions in brain capillaries and improves cortical blood flow in an Alzheimer’s disease mouse model

AbstractBackgroundWe recently found that increased obstructions in capillaries caused by adhesion of leucocytes in the cortical microvascular leads to a ∼20% reduction of cerebral blood flow (CBF) in mouse models of Alzheimer’s disease. Here, we explore the contribution of peripheral Vascular Endothelial Growth Factor (VEGF) signaling at the luminal side of the brain microvasculature as a driver of capillary stalling and blood‐brain barrier (BBB) integrity in the APP/PS1 mouse model of AD.MethodThe number of stalled cortical capillaries and blood flow speeds were measured in cortical capillaries using high resolution in vivo two‐photon imaging, before and after one hour and two weeks of i.p. anti‐VEGF164 antibody injection. Capillary stalls were measured using the citizen science platform Stall Catchers. The blood‐brain barrier integrity was analyzed using immunohistochemistry.ResultWe found that inhibition of VEGF signaling in APP/PS1 mice reduces capillary stalling by ∼75% and improves average capillary speed by ∼50%. In contrast, no such effects were seen in wild‐type saline‐injected controls. The anti‐VEGF164 injection also reduced overall eNOS protein concentrations and increased the tight junction protein levels of occludin. Intriguingly, the few APP/PS1 capillaries that were still prone to obstructions after anti‐VEGF treatment had lower occludin concentrations between their endothelial cells than flowing capillaries. We further demonstrate that capillary stalling reductions and capillary speed improvements occur within an hour of intraperitoneal anti‐mouseVEGF164 injection. At the same time scale, anti‐VEGF treatment reduced Evan’s blue diffusion across the BBB.ConclusionThis data demonstrates that peripheral inhibition of VEGF‐signaling in APP/PS1 mice restores aberrant eNOS/occludin‐associated BBB permeability, and is associated with decreased capillary stalls and increased CBF.

Erlotinib plus bevacizumab vs erlotinib monotherapy as first-line treatment for advanced EGFR mutation-positive non-squamous non-small-cell lung cancer: Survival follow-up results of the randomized JO25567 study

ObjectivesThe JO25567 randomized Phase II study demonstrated a statistically significant progression-free survival (PFS) benefit with erlotinib plus bevacizumab compared with erlotinib monotherapy in chemotherapy-naïve Japanese patients with epidermal growth factor receptor mutation-positive (EGFR+) non-small-cell lung cancer (NSCLC). Here we present updated PFS and final overall survival (OS) data after a median follow-up of 34.7 months. Materials and methodsPatients with stage IIIB/IV or postoperative recurrent NSCLC were randomized to receive oral erlotinib 150 mg once daily (n = 77) or erlotinib in combination with intravenous bevacizumab 15 mg/kg every 21 days (n = 75) until disease progression or unacceptable toxicity. OS was analyzed using an unstratified Cox proportional hazards model. ResultsConsistent with the primary analysis, addition of bevacizumab to erlotinib was associated with a significant improvement in PFS (hazard ratio [HR] 0.52; 95 % confidence interval [CI]: 0.35–0.76; log-rank two-sided P = 0.0005; median 16.4 months vs 9.8 months, respectively). In contrast, a significant improvement in OS was not seen (HR 0.81; 95 % CI, 0.53–1.23; P = 0.3267; median 47.0 months vs 47.4 months, respectively). Post-study therapy was similar between the treatment arms and EGFR mutation type did not affect OS outcomes. The 5-year OS rate was numerically higher with erlotinib plus bevacizumab vs erlotinib monotherapy (41 % vs 35 %). Updated safety analyses confirmed the previously reported manageable tolerability profile, with no new safety issues. ConclusionAddition of bevacizumab to first-line erlotinib did not show significant improvement in OS in Japanese patients with stage IIIB/IV or postoperative recurrent EGFR+ NSCLC. Both treatment arms showed a similar median OS benefit (as long as 4 years), irrespective of individual patient characteristics. Results from ongoing studies evaluating the combination of EGFR and VEGF signaling inhibitors are eagerly awaited. Trial registrationJapicCTI-111390 and JapicCTI-142569.

Slug regulates the Dll4-Notch-VEGFR2 axis to control endothelial cell activation and angiogenesis

Slug (SNAI2), a member of the well-conserved Snail family of transcription factors, has multiple developmental roles, including in epithelial-to-mesenchymal transition (EMT). Here, we show that Slug is critical for the pathological angiogenesis needed to sustain tumor growth, and transiently necessary for normal developmental angiogenesis. We find that Slug upregulation in angiogenic endothelial cells (EC) regulates an EMT-like suite of target genes, and suppresses Dll4-Notch signaling thereby promoting VEGFR2 expression. Both EC-specific Slug re-expression and reduced Notch signaling, either by γ-secretase inhibition or loss of Dll4, rescue retinal angiogenesis in SlugKO mice. Conversely, inhibition of VEGF signaling prevents excessive angiogenic sprouting of Slug overexpressing EC. Finally, endothelial Slug (but not Snail) is activated by the pro-angiogenic factor SDF1α via its canonical receptor CXCR4 and the MAP kinase ERK5. Altogether, our data support a critical role for Slug in determining the angiogenic response during development and disease.

Zinc Finger Protein St18 Protects against Septic Death by Inhibiting VEGF-A from Macrophages

Zinc finger protein St18 was initially reported as candidate tumor suppressor gene, and also suggested that fibroblast St18 positively regulates NF-κB activation. Despite the pleiotropic functions of St18, little is known about its roles in macrophages. Here, we report that myeloid St18 is a potent inhibitor of VEGF-A. Mice lacking St18 in myeloid lineages exhibit increased retinal vasculature with enhanced serum VEGF-A concentrations. Despite the normal activation of NF-κB target genes, these mice are highly susceptible to LPS-induced shock, polymicrobial sepsis, and experimental colitis, accompanied by enhanced vascular and intestinal leakage. Pharmacological inhibition of VEGF signaling rescued the high mortality rate of myeloid-specific St18-deficient mice in response to inflammation. Mechanistically, St18 directly binds to Sp1 and attenuates its activity, leading to the suppression of Sp1 target gene VEGF-A. Using mouse genetic and pharmacological models, we reveal myeloid St18 as a critical septic death protector.

Hyaloid vasculature and mmp2 activity play a role during optic fissure fusion in zebrafish

Vertebrate retinal development requires timely and precise fusion of the optic fissure (OF). Failure of this event leads to congenital vision impairment in the form of coloboma. Recent studies have suggested hyaloid vasculature to be involved in OF fusion. In order to examine this link, we analyzed OF fusion and hyaloid vasculogenesis in the zebrafish pax2a noi mutant line. We first determined that pax2a−/− embryos fail to accumulate F-actin in the OF prior to basement membrane (BM) degradation. Furthermore, using 3D and live imaging we observed reduced OF hyaloid vascularization in pax2a−/− embryos. When examining the connection between pax2a loss of function and hyaloid vasculature, we observed significant reduction of talin1 expression, a regulator of hyaloid vasculature. In addition, cranial VEGF expression was found to be reduced in pax2a−/− embryos. Pharmacological inhibition of VEGF signaling phenocopied the pax2a−/− vasculature, F-actin and BM degradation phenotypes. Lastly, we determined that OF associated hyaloid vasculature is a source of mmp2, mmp14a and mmp14b expression and showed that mmp2 is functionally necessary for degradation of OF BM. Taken together we propose a pax2a driven mechanism that ensures proper and timely hyaloid vasculature invasion of the OF in order to facilitate availability of the BM remodeler mmp2.

Pax2a Regulates Endothelial Cell Invasion into the Optic Fissure Resulting in Degradation of the Basement Membrane by mmp2

Epithelial Sheet Fusion (ESF), a process by which two populations of epithelial cells fuse to create a continuous sheet, is a crucial aspect of embryogenesis. ESF can be observed in the development of many tissues, including fusion of the optic fissure (OF) during retinal development in vertebrates. Failure in fusion of the OF results in congenital coloboma, a leading cause of pediatric blindness. Unfortunately, majority of coloboma cases lack a definitive genetic cause. This is likely reflected by the fact that the molecular mechanisms driving OF ESF are still poorly understood. This study aims to identify the molecular machinery regulating ESF during OF fusion in zebrafish. To do so, we utilized a well characterized mutant line of zebrafish carrying a mutation in the Pax2a gene. Pax2a is a transcription factor known to be required for OF fusion and has been linked to cases of coloboma in many species. The mutant pax2anoi/noi line of zebrafish display a completely penetrant coloboma phenotype. To assess transcriptional differences between normal and abnormal OF fusion, RNA sequencing was performed comparing WT and pax2anoi/noi whole eye transcriptomes. The results indicated a down‐regulation of hyaloid vasculature regulators. Examining retinal vasculature in Tg[kdrl:mCherry], pax2anoi/noi mutants revealed a significant reduction and malformation of the hyaloid vasculature. Subsequently, OF fusion was analyzed in the absence of vasculature. Treatment with a pharmacological inhibitor of VEGF signaling, DMH‐4, completely inhibited the establishment of hyaloid vasculature in the retina. In the presence of DMH4, the OF failed to fuse. In order to understand the mechanism behind the reduction of vasculature in pax2noi/noi embryos we returned to the transcriptomic data and analyzed for angiogenic regulators. This analysis identified adamts1, an anti‐angiogenic protease which sequesters VEGF ligands, to be up‐regulated in pax2noi/noi embryos. As validation of our findings, overexpression of adamts1 mRNA in WT embryos successfully phenocopied the pax2noi/noi associated failure of OF fusion. Lastly, in order to determine the functional role of hyaloid vasculature cells during OF fusion we examined basement membrane remodeling. Matrix metalloproteinases (MMP’s) have the ability to degrade the BM. After characterizing expression of all zebrafish mmp’s, mmp2, mmp14a and mmp14b were found to be expressed in the OF. Using two‐color in‐situ hybridization we confirmed that mmp2 and mmp14 expression in OF is confined to the hyaloid vasculature cells. Furthermore, mmp2 and mmp14 expression is decreased in the OF in both DMH‐4 treated and Pax2 mutant embryos. Treatment with a pharmacological inhibitor specific to mmp2, ARP101 resulted in a failure of OF BM remodeling and subsequently fusion. Overall, our results show that pax2a negatively regulates adamts1 expression to enable proper vascularization of the developing retina. Vascularization is subsequently necessary for optic fissure fusion as hyaloid vasculature cells provide mmp2 necessary for the degradation of the OF BM and thus OF fusion.Support or Funding InformationLyman T. Johnson Fellowship, Knights Templar Career Starter Grant

Angiogenesis and Immunity in Renal Carcinoma: Can We Turn an Unhappy Relationship into a Happy Marriage?

The frontline treatment options for patients with metastatic renal cell carcinoma (mRCC) are evolving rapidly since the approval of combination immunotherapies by the U.S. Food and Drug Administration (USFDA) and the European Medicines Agency (EMA). In particular, in combination with vascular endothelial growth factor receptor (VEGFR) tyrosine-kinase inhibitors (TKIs), immune checkpoint inhibitors (ICIs) have significantly improved the outcome of patients with mRCC compared to TKI monotherapy. Here, we review the preclinical data supporting the combination of ICIs with VEGFR TKIs. The VEGF-signaling inhibition could ideally sustain immunotherapy through a positive modulation of the tumor microenvironment (TME). Antiangiogenetics, in fact, with their inhibitory activity on myelopoiesis that indirectly reduces myeloid-derived suppressor cells (MDSCs) and regulatory T cells’ (Tregs) frequency and function, could have a role in determining an effective anti-tumor immune response. These findings are relevant for the challenges posed to clinicians concerning the clinical impact on treatment strategies for mRCC.

Antiangiogenic activity of terpenoids from Euphorbia neriifolia Linn.

Angiogenesis is known to serve an important role in embryonic development, wound healing, tissue regeneration, and growth. Two new abietane-type diterpenoids (3, 5), a new lanosterol triterpenoid (8) and seven known compounds haven been isolated from the Euphorbia neriifolia Linn. The structures of all compounds were elucidated by spectroscopic analysis and comparing their NMR data with reported data. Furthermore, we found that compounds 6 and 9 had the antiangiogenic effects in vitro. They could inhibit HUVEC migration and microvessel sprouting in rat aortic rings. Moreover, compound 6 inhibited VEGFR and phosphorylation of Akt, but compound 9 only shown inhibitory effect on phosphorylation of Akt. Taken together, these results suggest that inhibition of VEGF signaling and downstream pathways may be responsible for the antiangiogenic activity of compounds 6 and 9.

Inhibition of Sphingosine Phosphate Receptor 1 Signaling Enhances the Efficacy of VEGF Receptor Inhibition.

Inhibition of VEGFR signaling is an effective treatment for renal cell carcinoma, but resistance continues to be a major problem. Recently, the sphingosine phosphate (S1P) signaling pathway has been implicated in tumor growth, angiogenesis, and resistance to antiangiogenic therapy. S1P is a bioactive lipid that serves an essential role in developmental and pathologic angiogenesis via activation of the S1P receptor 1 (S1P1). S1P1 signaling counteracts VEGF signaling and is required for vascular stabilization. We used in vivo and in vitro angiogenesis models including a postnatal retinal angiogenesis model and a renal cell carcinoma murine tumor model to test whether simultaneous inhibition of S1P1 and VEGF leads to improved angiogenic inhibition. Here, we show that inhibition of S1P signaling reduces the endothelial cell barrier and leads to excessive angiogenic sprouting. Simultaneous inhibition of S1P and VEGF signaling further disrupts the tumor vascular beds, decreases tumor volume, and increases tumor cell death compared with monotherapies. These studies suggest that inhibition of angiogenesis at two stages of the multistep process may maximize the effects of antiangiogenic therapy. Together, these data suggest that combination of S1P1 and VEGFR-targeted therapy may be a useful therapeutic strategy for the treatment of renal cell carcinoma and other tumor types.

Allergy-immunology glossary

Mast cells VEGF is a highly specific mitogen for vascular endothelial cells. Five VEGF isoforms are generated as a result of alternative splicing from a single VEGF gene. The expression of VEGF is potentiated in response to hypoxia, by activated oncogenes, and by a variety of cytokines. VEGF induces endothelial cell proliferation, promotes cell migration, and inhibits apoptosis. In vivo VEGF induces angiogenesis as well as permeabilization of blood vessels, and plays a central role in the regulation of vasculogenesis. Deregulated VEGF expression contributes to the development of solid tumors and to several additional diseases by promoting tumor angiogenesis. Consequently, inhibition of VEGF signaling abrogates the development of a wide variety of tumors. The various VEGF forms bind to two tyrosine-kinase receptors, VEGFR-1 (flt-1) and VEGFR-2 (KDR/flk-1), which are expressed almost exclusively in endothelial cells. 1 يناطبلا ومنلا لماع يئاعولا ٢

Therapeutic Inhibition of VEGF Signaling and Associated Nephrotoxicities.

Inhibition of vascular endothelial growth factor A (VEGFA)/vascular endothelial growth factor receptor 2 (VEGFR2) signaling is a common therapeutic strategy in oncology, with new drugs continuously in development. In this review, we consider the experimental and clinical evidence behind the diverse nephrotoxicities associated with the inhibition of this pathway. We also review the renal effects of VEGF inhibition's mediation of key downstream signaling pathways, specifically MAPK/ERK1/2, endothelial nitric oxide synthase, and mammalian target of rapamycin (mTOR). Direct VEGFA inhibition via antibody binding or VEGF trap (a soluble decoy receptor) is associated with renal-specific thrombotic microangiopathy (TMA). Reports also indicate that tyrosine kinase inhibition of the VEGF receptors is preferentially associated with glomerulopathies such as minimal change disease and FSGS. Inhibition of the downstream pathway RAF/MAPK/ERK has largely been associated with tubulointerstitial injury. Inhibition of mTOR is most commonly associated with albuminuria and podocyte injury, but has also been linked to renal-specific TMA. In all, we review the experimentally validated mechanisms by which VEGFA-VEGFR2 inhibitors contribute to nephrotoxicity, as well as the wide range of clinical manifestations that have been reported with their use. We also highlight potential avenues for future research to elucidate mechanisms for minimizing nephrotoxicity while maintaining therapeutic efficacy.