Angiogenesis最新文献

Reduction–oxidation factor-1 or apurinic/apyrimidinic endonuclease 1 (Ref-1/APE1) is a crucial redox-sensitive activator of transcription factors such as NF-κB, HIF-1α, STAT-3 and others. It could contribute to key features of ocular neovascularization including inflammation and angiogenesis; these underlie diseases like neovascular age-related macular degeneration (nAMD). We previously revealed a role for Ref-1 in the growth of ocular endothelial cells and in choroidal neovascularization (CNV). Here, we set out to further explore Ref-1 in neovascular eye disease. Ref-1 was highly expressed in human nAMD, murine laser-induced CNV and Vldlr^−/− mouse subretinal neovascularization (SRN). Ref-1’s interaction with a redox-specific small molecule inhibitor, APX2009, was shown by NMR and docking. This compound blocks crucial angiogenic features in multiple endothelial cell types. APX2009 also ameliorated murine laser-induced choroidal neovascularization (L-CNV) when delivered intravitreally. Moreover, systemic APX2009 reduced murine SRN and downregulated the expression of Ref-1 redox regulated HIF-1α target carbonic anhydrase 9 (CA9) in the Vldlr^−/− mouse model. Our data validate the redox function of Ref-1 as a critical regulator of ocular angiogenesis, indicating that inhibition of Ref-1 holds therapeutic potential for treating nAMD.

Angiogenesis describes the sprouting of blood vessels from existing vasculatures and it plays a pivotal role in disease progress such as diabetes, age-related macular degeneration and cancer. However, the most widely used anti-angiogenic agents targeting vascular endothelial growth factor (VEGF) pathway still lacked of specificity and therapeutic efficacy. To establish a method suitable for high-throughput drug screening and faithfully recapitulate the feature of in vivo angiogenesis, we generated a PECAM1-mRuby3-secNluc; ACTA2-EGFP dual reporter human pluripotent stem cell (hPSC) line and utilizing the cell line to establish a visualized and quantifiable in vitro angiogenesis model with stem cell-derived vascular organoid. Using this method, we evaluated the anti-angiogenic effect of VEGFR inhibitor and efficiently identified several potential candidates of pro- and anti-angiogenic therapy via bioluminescence-based quantification. Overall, our study provides a valuable platform for in vitro drug screenings.

Epistaxis greatly affects patients with hereditary hemorrhagic telangiectasia (HHT). Although few systemic treatment exist, nintedanib, is a good candidate thanks to its anti-angiogenic activity. Our main objective was to evaluate the efficacy of oral nintedanib on epistaxis duration in HHT patients with moderate to severe epistaxis. This multicenter phase 2 randomized, placebo-controlled, double-blind trial was conducted between June 2020 and February 2023. Inclusion criteria were being over 18 years old and having a confirmed HHT diagnosis with an epistaxis severity score greater than 4. Sixty patients were randomized to receive either nintedanib or placebo for 12 weeks with a 12 week follow-up. The primary endpoint was the proportion of patients achieving a reduction of at least 50% in mean monthly epistaxis duration comparing the 8 weeks before treatment to the last 8 weeks of treatment. Main secondary outcomes included monthly duration and frequency of epistaxis and hemoglobin levels. Of the 60 randomized patients, 56 completed the trial. Thirteen patients (43%) in the nintedanib group vs 8 (27%) in the placebo group met the primary endpoint (p = 0.28). We observed a significant decrease in median epistaxis (57% vs 27%, p = 0.013) and a significant increase in median hemoglobin levels (+ 18 vs − 1 g/L, p = 0.02) in the nintedanib vs the placebo group. Although we did not achieve our primary outcome, we observed a significant reduction in epistaxis duration and a significant increase in hemoglobin levels in patients treated with nintedanib. This supports the efficacy of nintedanib, and further studies are needed.

Neuropilin-1 (NRP1) regulates endothelial cell (EC) biology through modulation of vascular endothelial growth factor receptor 2 (VEGFR2) signalling by presenting VEGFA to VEGFR2. How NRP1 impacts VEGFA-mediated vascular hyperpermeability has however remained unresolved, described as exerting either a positive or a passive function. Using EC-specific Nrp1 knock-out mice, we discover that EC-expressed NRP1 exerts an organotypic role. In the ear skin, VEGFA/VEGFR2-mediated vascular leakage was increased following loss of EC NRP1, implicating NRP1 in negative regulation of VEGFR2 signalling. In contrast, in the back skin and trachea, loss of EC NRP1 decreased vascular leakage. In accordance, phosphorylation of vascular endothelial (VE)-cadherin was increased in the ear skin but suppressed in the back skin of Nrp1 iECKO mice. NRP1 expressed on perivascular cells has been shown to impact VEGF-mediated VEGFR2 signalling. Importantly, expression of NRP1 on perivascular cells was more abundant in the ear skin than in the back skin. Global loss of NRP1 resulted in suppressed VEGFA-induced vascular leakage in the ear skin, implicating perivascular NRP1 as a juxtacrine co-receptor of VEGFA in this compartment. Altogether, we demonstrate that perivascular NRP1 is an active participant in EC VEGFA/VEGFR2 signalling and acts as an organotypic modifier of EC biology.

Arteriovenous malformations (AVMs) are abnormal high flow shunts between arteries and veins with major negative impact on the cardiovascular system. Inherited loss-of-function (LOF) mutations in endoglin, encoding an endothelial cell (EC) expressed co-receptor for BMP9/10, causes the disease HHT1/Osler-Weber-Rendu, characterized by bleeding and AVMs. Here we observe increased activity of the downstream signalling complex mTORC1 within the retinal vasculature of HHT mouse models. To investigate its importance in AVM biology, concerning subvascular action, cell specificity, signalling strength and kinetics we combine timed genetic and antibody-based models of HHT with genetic mTORC1 inhibition or activation through EC specific deletion of Rptor or Tsc1. Results demonstrate that EC mTORC1 activation is secondary to endoglin LOF and mainly a consequence of systemic effects following AVM. While genetic EC inhibition of mTORC1 only showed tendencies towards reduced AVM severity, EC overactivation counterintuitively reduced it, implying that mTORC1 must be within a certain range to facilitate AVM. Complete inhibition of mTORC1 signalling by rapamycin provided the strongest therapeutic effect, pointing to potential involvement of RAPTOR-independent pathways or AVM-promoting effects of non-ECs in this pathology.

Hemodynamic cues are thought to control blood vessel hierarchy through a shear stress set point, where flow increases lead to blood vessel diameter expansion, while decreases in blood flow cause blood vessel narrowing. Aberrations in blood vessel diameter control can cause congenital arteriovenous malformations (AVMs). We show in zebrafish embryos that while arteries behave according to the shear stress set point model, veins do not. This behavior is dependent on distinct arterial and venous endothelial cell (EC) shapes and sizes. We show that arterial ECs enlarge more strongly when experiencing higher flow, as compared to vein cells. Through the generation of chimeric embryos, we discover that this behavior of vein cells depends on the bone morphogenetic protein (BMP) pathway components Endoglin and Alk1. Endoglin (eng) or alk1 (acvrl1) mutant vein cells enlarge when in normal hemodynamic environments, while we do not observe a phenotype in either acvrl1 or eng mutant ECs in arteries. We further show that an increase in vein diameters initiates AVMs in eng mutants, secondarily leading to higher flow to arteries. These enlarge in response to higher flow through increasing arterial EC sizes, fueling the AVM. This study thus reveals a mechanism through which BMP signaling limits vein EC size increases in response to flow and provides a framework for our understanding of how a small number of mutant vein cells via flow-mediated secondary effects on wildtype arterial ECs can precipitate larger AVMs in disease conditions, such as hereditary hemorrhagic telangiectasia (HHT).

Brain arteriovenous malformations (bAVMs) are a major cause of hemorrhagic stroke in children and young adults. These lesions are thought to result from somatic KRAS/BRAF mutations in brain endothelial cells (bECs). In this study, we introduce a new bAVM model by inducing a brain endothelial-specific Braf^V600E mutation using the Slc1o1c1(BAC)-CreER driver line. The pathological characteristics of this model resemble human bAVMs, including dilated and hyperpermeable vessels, as well as parenchymal hemorrhage. We observed that these lesions showed a typical reduction in pericyte coverage and disruption of the pericyte-endothelial cell connection. Additionally, we found that ANGPT2 levels were significantly increased in the endothelium of bAVM lesions, which may be a critical factor in the pericyte deficits of the malformed vessels. Treatment with an ANGPT2 neutralizing antibody confirmed that blocking ANGPT2 can restore pericyte density in bAVM lesions, improve pericyte coverage around microvessels, enhance tight junction protein coverage related to endothelial cells, and normalize endothelial barrier function. In summary, our findings suggest that increased ANGPT2 expression in endothelial cells with the Braf^V600E mutation is a key factor in pericyte deficiencies in bAVMs, highlighting the potential effectiveness of anti-ANGPT2 therapy in treating bAVMs.

Tumour angiogenesis supports malignant cells with oxygen and nutrients to promote invasion and metastasis. A number of cytokines released in situ participate in the recruitment of endothelial cells and pericytes to trigger the formation of novel blood vessels, which are often abnormal, leaky, and disorganized. Nicotinamide phosphoribosyltransferase is a key intracellular enzyme involved in NAD metabolism and is up regulated in many cancers to meet bioenergetic demands. Yet, the same protein is also secreted extracellularly (eNAMPT), where it acts as a pro-inflammatory cytokine. High plasma eNAMPT levels have been reported in breast cancer patients and correlate with aggressiveness and prognosis. We now report that in a triple-negative breast cancer model, enriching the tumour microenvironment with eNAMPT leads to abundant angiogenesis and increased metastatization. Atypically, the eNAMPT-mediated pro-angiogenic effect is mainly directed to NG2⁺ pericytes. Indeed, eNAMPT acts as chemoattractant for pericytes and coordinates vessel-like tube formation, in synergism with the classical factor PDGF-BB. Stimulation of pericytes by eNAMPT leads to a pro-inflammatory activation, characterized by the overexpression of key chemokines (CXCL8, CXCL1, CCL2) and VCAM1, via NF-κB signalling. All these effects were ablated by the use of C269, an anti-eNAMPT neutralizing antibody, suggesting that this might represent a novel anti-angiogenic pharmacological approach for triple-negative breast cancer.