Vascular biology
Abstract
Clinical trials in patients with macular edema due to diabetic retinopathy or retinal vein occlusion (RVO) have shown that suppression of VEGF not only improves macular edema, but also reopens closed retinal vessels, prevents progression of vessel closure, and improves retinopathy. In this study, we show the molecular basis for those clinical observations. Increased retinal levels of VEGF in mice cause plugging of retinal vessels with leukocytes, vessel closure, and hypoxia. Suppression of VEGF reduces leukocyte plugging, causing reperfusion of closed vessels. Activation of VEGFR1 contributes to leukocyte recruitment, because it is significantly reduced by an anti-VEGFR1–neutralizing antibody. High VEGF increases transcriptional activity of NF-κB and expression of NF-κB target genes, particularly Vcam1. Injection of an anti-VCAM-1–neutralizing antibody reduces VEGF-induced leukocyte plugging. These data explain the broad range of benefits obtained by VEGF suppression in patients with ischemic retinopathies, provide an important insight into the pathogenesis of RVO and diabetic retinopathy, and suggest that sustained suppression of VEGF early in the course of these diseases may prevent vessel closure, worsening ischemia, and disease progression. This study also identifies VEGFR1 and VCAM-1 as molecular targets whose suppression could supplement VEGF neutralization for treatment of RVO and diabetic retinopathy.
Authors
Yuanyuan Liu, Jikui Shen, Seth D. Fortmann, Jiangxia Wang, Dietmar Vestweber, Peter A. Campochiaro
Abstract
Transcriptionally activated monocytes are recruited to the heart after acute myocardial infarction (AMI). After AMI in mice and humans, the number of extracellular vesicles (EVs) increased acutely. In humans, EV number correlated closely with the extent of myocardial injury. We hypothesized that EVs mediate splenic monocyte mobilization and program transcription following AMI. Some plasma EVs bear endothelial cell (EC) integrins, and both proinflammatory stimulation of ECs and AMI significantly increased VCAM-1–positive EV release. Injected EC-EVs localized to the spleen and interacted with, and mobilized, splenic monocytes in otherwise naive, healthy animals. Analysis of human plasma EV-associated miRNA showed 12 markedly enriched miRNAs after AMI; functional enrichment analyses identified 1,869 putative mRNA targets, which regulate relevant cellular functions (e.g., proliferation and cell movement). Furthermore, gene ontology termed positive chemotaxis as the most enriched pathway for the miRNA-mRNA targets. Among the identified EV miRNAs, EC-associated miRNA-126-3p and -5p were highly regulated after AMI. miRNA-126-3p and -5p regulate cell adhesion– and chemotaxis-associated genes, including the negative regulator of cell motility, plexin-B2. EC-EV exposure significantly downregulated plexin-B2 mRNA in monocytes and upregulated motility integrin ITGB2. These findings identify EVs as a possible novel signaling pathway by linking ischemic myocardium with monocyte mobilization and transcriptional activation following AMI.
Authors
Naveed Akbar, Janet E. Digby, Thomas J. Cahill, Abhijeet N. Tavare, Alastair L. Corbin, Sushant Saluja, Sam Dawkins, Laurienne Edgar, Nadiia Rawlings, Klemen Ziberna, Eileen McNeill, Oxford Acute Myocardial Infarction (OxAMI) Study, Errin Johnson, Alaa A. Aljabali, Rebecca A. Dragovic, Mala Rohling, T. Grant Belgard, Irina A. Udalova, David R. Greaves, Keith M. Channon, Paul R. Riley, Daniel C. Anthony, Robin P. Choudhury
Abstract
Lymphatic malformations are serious but poorly understood conditions that present therapeutic challenges. The goal of this study was to compare strategies for inducing regression of abnormal lymphatics and explore underlying mechanisms. CCSP-rtTA/tetO-VEGF-C mice, in which doxycycline regulates VEGF-C expression in the airway epithelium, were used as a model of pulmonary lymphangiectasia. After doxycycline was stopped, VEGF-C expression returned to normal, but lymphangiectasia persisted for at least 9 months. Inhibition of VEGFR-2/VEGFR-3 signaling, Notch, β-adrenergic receptors, or autophagy and antiinflammatory steroids had no noticeable effect on the amount or severity of lymphangiectasia. However, rapamycin inhibition of mTOR reduced lymphangiectasia by 76% within 7 days without affecting normal lymphatics. Efficacy of rapamycin was not increased by coadministration with the other agents. In prevention trials, rapamycin suppressed VEGF-C–driven mTOR phosphorylation and lymphatic endothelial cell sprouting and proliferation. However, in reversal trials, no lymphatic endothelial cell proliferation was present to block in established lymphangiectasia, and rapamycin did not increase caspase-dependent apoptosis. However, rapamycin potently suppressed Prox1 and VEGFR-3. These experiments revealed that lymphangiectasia is remarkably resistant to regression but is responsive to rapamycin, which rapidly reduces and normalizes the abnormal lymphatics without affecting normal lymphatics.
Authors
Peter Baluk, Li-Chin Yao, Julio C. Flores, Dongwon Choi, Young-Kwon Hong, Donald M. McDonald
Abstract
BACKGROUND. Lack of investigatory and diagnostic tools has been a major contributing factor to the failure to mechanistically understand lymphedema and other lymphatic disorders in order to develop effective drug and surgical therapies. One difficulty has been understanding the true changes in lymph vessel pathology from standard 2D tissue sections. METHODS. VIPAR (volume information-based histopathological analysis by 3D reconstruction and data extraction), a light-sheet microscopy–based approach for the analysis of tissue biopsies, is based on digital reconstruction and visualization of microscopic image stacks. VIPAR allows semiautomated segmentation of the vasculature and subsequent nonbiased extraction of characteristic vessel shape and connectivity parameters. We applied VIPAR to analyze biopsies from healthy lymphedematous and lymphangiomatous skin. RESULTS. Digital 3D reconstruction provided a directly visually interpretable, comprehensive representation of the lymphatic and blood vessels in the analyzed tissue volumes. The most conspicuous features were disrupted lymphatic vessels in lymphedematous skin and a hyperplasia (4.36-fold lymphatic vessel volume increase) in the lymphangiomatous skin. Both abnormalities were detected by the connectivity analysis based on extracted vessel shape and structure data. The quantitative evaluation of extracted data revealed a significant reduction of lymphatic segment length (51.3% and 54.2%) and straightness (89.2% and 83.7%) for lymphedematous and lymphangiomatous skin, respectively. Blood vessel length was significantly increased in the lymphangiomatous sample (239.3%). CONCLUSION. VIPAR is a volume-based tissue reconstruction data extraction and analysis approach that successfully distinguished healthy from lymphedematous and lymphangiomatous skin. Its application is not limited to the vascular systems or skin. FUNDING. Max Planck Society, DFG (SFB 656), and Cells-in-Motion Cluster of Excellence EXC 1003.
Authors
René Hägerling, Dominik Drees, Aaron Scherzinger, Cathrin Dierkes, Silvia Martin-Almedina, Stefan Butz, Kristiana Gordon, Michael Schäfers, Klaus Hinrichs, Pia Ostergaard, Dietmar Vestweber, Tobias Goerge, Sahar Mansour, Xiaoyi Jiang, Peter S. Mortimer, Friedemann Kiefer
Abstract
Atherosclerosis is considered both a metabolic and inflammatory disease; however, the specific tissue and signaling molecules that instigate and propagate this disease remain unclear. The liver is a central site of inflammation and lipid metabolism that is critical for atherosclerosis, and JAK2 is a key mediator of inflammation and, more recently, of hepatic lipid metabolism. However, precise effects of hepatic Jak2 on atherosclerosis remain unknown. We show here that hepatic Jak2 deficiency in atherosclerosis-prone mouse models exhibited accelerated atherosclerosis with increased plaque macrophages and decreased plaque smooth muscle cell content. JAK2’s essential role in growth hormone signalling in liver that resulted in reduced IGF-1 with hepatic Jak2 deficiency played a causal role in exacerbating atherosclerosis. As such, restoring IGF-1 either pharmacologically or genetically attenuated atherosclerotic burden. Together, our data show hepatic Jak2 to play a protective role in atherogenesis through actions mediated by circulating IGF-1 and, to our knowledge, provide a novel liver-centric mechanism in atheroprotection.
Authors
Tharini Sivasubramaniyam, Stephanie A. Schroer, Angela Li, Cynthia T. Luk, Sally Yu Shi, Rickvinder Besla, David W. Dodington, Adam H. Metherel, Alex P. Kitson, Jara J. Brunt, Joshua Lopes, Kay-Uwe Wagner, Richard P. Bazinet, Michelle P. Bendeck, Clinton S. Robbins, Minna Woo
Abstract
Lymphatic endothelium serves as a barrier to control fluid balance and immune cell trafficking to maintain tissue homeostasis. Long-term alteration of lymphatic vasculature promotes edema and fibrosis, which is an aggravating factor in the onset of cardiovascular diseases such as myocardial infarction. Apelin is a bioactive peptide that plays a central role in angiogenesis and cardiac contractility. Despite an established role of apelin in lymphangiogenesis, little is known about its function in the cardiac lymphatic endothelium. Here, we show that apelin and its receptor APJ were exclusively expressed on newly formed lymphatic vasculature in a pathological model of myocardial infarction. Using an apelin-knockout mouse model, we identified morphological and functional defects in lymphatic vasculature associated with a proinflammatory status. Surprisingly, apelin deficiency increased the expression of lymphangiogenic growth factors VEGF-C and VEGF-D and exacerbated lymphangiogenesis after myocardial infarction. Conversely, the overexpression of apelin in ischemic heart was sufficient to restore a functional lymphatic vasculature and to reduce matrix remodeling and inflammation. In vitro, the expression of apelin prevented the alteration of cellular junctions in lymphatic endothelial cells induced by hypoxia. In addition, we demonstrated that apelin controls the secretion of the lipid mediator sphingosine-1-phosphate in lymphatic endothelial cells by regulating the level of expression of sphingosine kinase 2 and the transporter SPNS2. Taken together, our results show that apelin plays a key role in lymphatic vessel maturation and stability in pathological settings. Thus, apelin may represent a novel candidate to prevent pathological lymphatic remodeling in diseases.
Authors
Florence Tatin, Edith Renaud-Gabardos, Anne-Claire Godet, Fransky Hantelys, Francoise Pujol, Florent Morfoisse, Denis Calise, Fanny Viars, Philippe Valet, Bernard Masri, Anne-Catherine Prats, Barbara Garmy-Susini
Abstract
BACKGROUND. Cannabidiol (CBD) is a nonpsychoactive phytocannabinoid used in multiple sclerosis and intractable epilepsies. Preclinical studies show CBD has numerous cardiovascular benefits, including a reduced blood pressure (BP) response to stress. The aim of this study was to investigate if CBD reduces BP in humans. METHODS. Nine healthy male volunteers were given 600 mg of CBD or placebo in a randomized, placebo-controlled, double-blind, crossover study. Cardiovascular parameters were monitored using a finometer and laser Doppler. RESULTS. CBD reduced resting systolic BP (–6 mmHg; P < 0.05) and stroke volume (–8 ml; P < 0.05), with increased heart rate (HR) and maintained cardiac output. Subjects who had taken CBD had lower BP (–5 mmHg; P < 0.05, especially before and after stress), increased HR (+10 bpm; P < 0.01), decreased stroke volume (–13 ml; P < 0.01), and a blunted forearm skin blood flow response to isometric exercise. In response to cold stress, subjects who had taken CBD had blunted BP (–6 mmHg; P < 0.01) and increased HR (+7 bpm; P < 0.05), with lower total peripheral resistance. CONCLUSIONS. This data shows that acute administration of CBD reduces resting BP and the BP increase to stress in humans, associated with increased HR. These hemodynamic changes should be considered for people taking CBD. Further research is required to establish whether CBD has a role in the treatment of cardiovascular disorders.
Authors
Khalid A. Jadoon, Garry D. Tan, Saoirse E. O’Sullivan
Abstract
Using transcriptional profiling of platelets from patients presenting with acute myocardial infarction, we identified myeloid-related protein-14 (MRP-14, also known as S100A9) as an acute myocardial infarction gene and reported that platelet MRP-14 binding to platelet CD36 regulates arterial thrombosis. However, whether MRP-14 plays a role in venous thrombosis is unknown. We subjected WT and Mrp-14–deficient (Mrp-14-/-) mice to experimental models of deep vein thrombosis (DVT) by stasis ligation or partial flow restriction (stenosis) of the inferior vena cava. Thrombus weight in response to stasis ligation or stenosis was reduced significantly in Mrp-14-/- mice compared with WT mice. The adoptive transfer of WT neutrophils or platelets, or the infusion of recombinant MRP-8/14, into Mrp-14-/- mice rescued the venous thrombosis defect in Mrp-14-/- mice, indicating that neutrophil- and platelet-derived MRP-14 directly regulate venous thrombogenesis. Stimulation of neutrophils with MRP-14 induced neutrophil extracellular trap (NET) formation, and NETs were reduced in venous thrombi harvested from Mrp-14-/- mice and in Mrp-14-/- neutrophils stimulated with ionomycin. Given prior evidence that MRP-14 also regulates arterial thrombosis, but not hemostasis (i.e., reduced bleeding risk), MRP-14 appears to be a particularly attractive molecular target for treating thrombotic cardiovascular diseases, including myocardial infarction, stroke, and venous thromboembolism.
Authors
Yunmei Wang, Huiyun Gao, Chase W. Kessinger, Alvin Schmaier, Farouc A. Jaffer, Daniel I. Simon
Abstract
Mechanisms of atherogenesis have been studied extensively in genetically engineered mice with disturbed cholesterol metabolism such as those lacking either the LDL receptor (
Authors
Srinivas D. Sithu, Marina V. Malovichko, Krista A. Riggs, Nalinie S. Wickramasinghe, Millicent G. Winner, Abhinav Agarwal, Rihab E. Hamed-Berair, Anuradha Kalani, Daniel W. Riggs, Aruni Bhatnagar, Sanjay Srivastava
Abstract
Non–transferrin-bound iron (NTBI) and free hemoglobin (Hb) accumulate in circulation following stored RBC transfusions. This study investigated transfusion, vascular disease, and mortality in guinea pigs after stored RBC transfusion alone and following cotransfusion with apo-transferrin (apo-Tf) and haptoglobin (Hp). The effects of RBC exchange transfusion dose (1, 3, and 9 units), storage period (14 days), and mortality were evaluated in guinea pigs with a vascular disease phenotype. Seven-day mortality and the interaction between iron and Hb as cocontributors to adverse outcome were studied. Concentrations of iron and free Hb were greatest after transfusion with 9 units of stored RBCs compared with fresh RBCs or stored RBCs at 1- and 3-unit volumes. Nine units of stored RBCs led to mortality in vascular diseased animals, but not normal animals. One and 3 units of stored RBCs did not cause a mortality effect, suggesting the concomitant relevance of NTBI and Hb on outcome. Cotransfusion with apo-Tf or Hp restored survival to 100% following 9-unit RBC transfusions in vascular diseased animals. Our data suggest that increases in plasma NTBI and Hb contribute to vascular disease–associated mortality through iron-enhanced Hb oxidation and enhanced tissue injury.
Authors
Jin Hyen Baek, Ayla Yalamanoglu, Yamei Gao, Ricardo Guenster, Donat R. Spahn, Dominik J. Schaer, Paul W. Buehler
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