Vascular biology
Abstract
Elevated hematocrit is associated with cardiovascular risk; however, the causality and mechanisms are unclear. The JAK2V617F (Jak2VF) mutation increases cardiovascular risk in myeloproliferative disorders and in clonal hematopoiesis (CH). Jak2VF mice with elevated white blood cells, platelets and red blood cells (RBCs) display accelerated atherosclerosis and macrophage erythrophagocytosis. To investigate whether selective erythroid Jak2VF expression promotes atherosclerosis, we developed hyperlipidemic Erythropoietin Receptor Cre mice that express Jak2VF in the erythroid lineage (VFEpoR mice). VFEpoR mice without elevated blood cell counts showed increased atherosclerotic plaque necrosis, erythrophagocytosis and ferroptosis. Selective induction of erythrocytosis with low dose erythropoietin further exacerbated atherosclerosis with prominent ferroptosis, lipid peroxidation and endothelial damage. VFEpoR RBCs had reduced antioxidant defenses and increased lipid hydroperoxides. Phagocytosis of human or murine WT or JAK2VF RBCs by WT macrophages induced ferroptosis, which was prevented by the ferroptosis inhibitor Liproxstatin-1. Liproxstatin-1 reversed increased atherosclerosis, lipid peroxidation, ferroptosis and endothelial damage in VFEpoR mice and in Jak2VF chimeric mice simulating CH, but had no impact in controls. Erythroid lineage Jak2VF expression leads to qualitative and quantitative defects in RBCs that exacerbate atherosclerosis. Phagocytosis of RBCs by plaque macrophages promotes ferroptosis, suggesting a new therapeutic target to reduce RBC-mediated cardiovascular risk.
Authors
Wenli Liu, Nataliya K. Östberg, Mustafa Yalcinkaya, Huijuan Dou, Kaori Endo-Umeda, Yang Tang, Xintong Hou, Tong Xiao, Trevor Filder, Sandra Abramowicz, Yong-Guang Yang, Oliver Soehnlein, Alan R. Tall, Nan Wang
Abstract
Pericytes (PC) are abundant yet remain the most enigmatic and ill-defined cell population in the heart. Here, we investigated if PC can be reprogrammed to aid neovascularization. Primary PC from human and mouse hearts acquired cytoskeleton proteins typical of vascular smooth muscle cells (VSMC) upon exclusion of EGF/bFGF, which signal through ERK1/2, or exposure to the MEK-inhibitor PD0325901. Differentiated PC became more proangiogenic, more responsive to vasoactive agents, and insensitive to chemoattractants. RNA-Sequencing revealed transcripts marking the PD0325901-induced transition into proangiogenic, stationary VSMC-like cells, including the unique expression of two angiogenesis-related markers, aquaporin 1 (AQP1) and cellular retinoic acid-binding protein 2 (CRABP2), which were further verified at the protein level. This enabled us to trace PC during in vivo studies. In mice, implantation of Matrigel plugs containing human PC+PD0325901 promoted the formation of α-SMApos neovessels compared with PC only. Two-week oral administration of PD0325901 to mice increased the heart arteriolar density, total vascular area, arteriole coverage by PDGFRβposAQP1posCRABP2pos PC, and myocardial perfusion. Short-duration PD0325901 treatment of mice after myocardial infarction enhanced the peri-infarct vascularization, reduced the scar, and improved systolic function. In conclusion, myocardial PC have intrinsic plasticity that can be pharmacologically modulated to promote reparative vascularization of the ischemic heart.
Authors
Elisa Avolio, Rajesh Katare, Anita C. Thomas, Andrea Caporali, Daryl Schwenke, Michele Carrabba, Marco Meloni, Massimo Caputo, Paolo Madeddu
Abstract
As blood transitions from steady laminar flow (S-flow) in healthy arteries to disturbed flow (D-flow) in aneurysmal arteries, platelets are subjected to external forces. Biomechanical platelet activation is incompletely understood and is a potential mechanism behind antiplatelet medication resistance. While it was demonstrated that anti-platelet drugs suppress growth of abdominal aortic aneurysms (AAA) in patients, we revealed a certain degree of platelet reactivity persisted in spite of aspirin therapy urging us to consider additional anti-platelet therapeutic targets. Transcriptomic profiling of platelets from patients with AAA revealed upregulation of a signal transduction pathway common to olfactory receptors (ORs), and this was explored as a mediator of AAA progression. Healthy platelets subjected to D-flow ex vivo, platelets from patients with AAA, and platelets in murine models of AAA demonstrated increased membrane olfactory receptor 2L13 (OR2L13) expression. A drug screen identified a molecule activating platelet OR2L13 which limited both biochemical and biomechanical platelet activation as well as AAA growth. This observation was further supported by selective deletion of the OR2L13 ortholog in a murine model of AAA that accelerated aortic aneurysm growth and rupture. These studies reveal that ORs regulate platelet activation in AAA and aneurysmal progression through platelet-derived mediators of aortic remodeling.
Authors
Craig N. Morrell, Doran Mix, Anu Aggarwal, Rohan Bhandari, Matthew Godwin, A. Phillip Owens III, Sean P. Lyden, Adam Doyle, Krystin Krauel, Matthew T. Rondina, Amy Mohan, Charles J. Lowenstein, Sharon Shim, Shaun Stauffer, Vara Prasad Josyula, Sara K. Ture, David I. Yule, Larry E. Wagner III, John M. Ashton, Ayman Elbadawi, Scott J. Cameron
Abstract
Pericyte-mediated capillary constriction decreases cerebral blood flow in stroke after an occluded artery is unblocked. The determinants of pericyte tone are poorly understood. We show that a small rise in cytoplasmic Ca2+ concentration ([Ca2+]i) in pericytes activates chloride efflux through the Ca2+-gated anion channel TMEM16A, thus depolarizing the cell and opening voltage-gated calcium channels. This mechanism strongly amplifies the pericyte [Ca2+]i rise and capillary constriction evoked by contractile agonists and ischemia. In a rodent stroke model, TMEM16A inhibition slows the ischemia-evoked pericyte [Ca2+]i rise, capillary constriction and pericyte death, reduces neutrophil stalling and improves cerebrovascular reperfusion. Genetic analysis implicates altered TMEM16A expression in poor patient recovery from ischemic stroke. Thus, pericyte TMEM16A is a crucial regulator of cerebral capillary function, and a potential therapeutic target for stroke and possibly other disorders of impaired microvascular flow, such as Alzheimer’s disease and vascular dementia.
Authors
Nils Korte, Zeki Ilkan, Claire L. Pearson, Thomas Pfeiffer, Prabhav Singhal, Jason R. Rock, Huma Sethi, Dipender Gill, David Attwell, Paolo Tammaro
Abstract
The loss function of cerebral cavernous malformation (CCM) genes leads to most CCM lesions characterized by enlarged leaking vascular lesions in the brain. Although we previously showed that NOGOB receptor (NGBR) knockout in endothelial cells (ECs) results in cerebrovascular lesions in the mouse embryo, the molecular mechanism by which NGBR regulates CCM1/2 expression has not been elucidated. Here, we show that temporal genetic depletion of Ngbr in ECs at both postnatal and adult stages results in CCM1/2 expression deficiency and cerebrovascular lesions such as enlarged vessels, blood-brain barrier (BBB) hyperpermeability, and cerebral hemorrhage. To reveal the molecular mechanism, we used RNA-seq analysis to examine changes in the transcriptome. Surprisingly, we found that acetyltransferase HBO1 and histone acetylation were downregulated in NGBR deficient ECs. The mechanistic studies elucidated that NGBR is required for maintaining the expression of CCM1/2 in ECs via HBO1-mediated histone acetylation. ChIP-qPCR data further demonstrated that loss of NGBR impairs the binding of both HBO1 and acetylated H4K5/K12 on the promotor of CCM1 and CCM2 genes. Our findings on epigenetic regulation of CCM1 and CCM2 that modulated by NGBR and HBO1-mediated histone H4 acetylation provide a perspective on the pathogenesis of sporadic CCMs.
Authors
Zhi Fang, Xiaoran Sun, Xiang Wang, Ji Ma, Thomas Palaia, Ujala Rana, Benjamin Miao, Louis Ragolia, Wenquan Hu, Qing Robert Miao
Abstract
Clearance of dying cells by efferocytosis is necessary for cardiac repair after myocardial infarction (MI). Recent reports have suggested a protective role for vascular endothelial growth factor C (VEGFC) during acute cardiac lymphangiogenesis post MI. Here we report that defective efferocytosis by macrophages after experimental MI leads to a reduction in cardiac lymphangiogenesis and Vegfc expression. Cell-intrinsic evidence for efferocytic-induction of Vegfc was revealed after adding apoptotic cells to cultured primary macrophages, which subsequently triggered Vegfc transcription and VEGFC secretion. Similarly, cardiac macrophages elevated Vegfc expression levels after MI, and mice deficient for myeloid Vegfc exhibited impaired ventricular contractility, adverse tissue remodeling and reduced lymphangiogenesis. These results were observed in mouse models of permanent coronary occlusion and clinically relevant ischemia and reperfusion. Interestingly, myeloid Vegfc deficiency also led to increases in acute infarct size, prior to the amplitude of the acute cardiac lymphangiogenesis response. RNA sequencing and cardiac flow cytometry revealed that myeloid Vegfc deficiency was also characterized by a defective inflammatory response, and macrophages-produced VEGFC was directly effective at suppressing pro-inflammatory macrophage activation. Taken together, our findings indicate that cardiac macrophages promote healing through the promotion of myocardial lymphangiogenesis and the suppression of inflammatory cytokines.
Authors
Kristofor E. Glinton, Wanshu Ma, Connor W. Lantz, Lubov S. Grigoryeva, Matthew DeBerge, Xiaolei Liu, Maria Febbraio, Mark Kahn, Guillermo Oliver, Edward B. Thorp
Abstract
Genetic variants at the SORT1 locus in humans causing increased SORT1 expression in liver are significantly associated with reduced plasma levels of LDL cholesterol and apolipoprotein B (apoB). However, the role of hepatic sortilin remains controversial, as genetic deletion of sortilin in mice has yielded variable and conflicting effects on apoB secretion. Sort1 knockout mice on a chow diet and several Sort1-deficient hepatocyte lines displayed no difference in apoB secretion. When these models were challenged with high fat or ER stress, the loss of Sort1 expression resulted in a significant increase in apoB-100 secretion. Sort1 overexpression studies yielded reciprocal results. Importantly, diabetic carriers of SORT1 variant have larger decreases in plasma apoB, TG, and VLDL and LDL particle number as compared to non-diabetics with the same variants. We conclude that under basal non-stressed conditions, loss of sortilin has little effect on hepatocyte apoB secretion, but that in the setting of lipid-loading or ER stress, sortilin deficiency leads to increased apoB secretion. These results are consistent with the directionality of effect in human genetics studies and suggest that under stress conditions, hepatic sortilin directs apoB toward lysosomal degradation rather than secretion, potentially serving as a quality control step in the apoB secretion pathway in hepatocytes.
Authors
Donna M. Conlon, Carolin V. Schneider, Yi-An Ko, Amrith Rodrigues, Kathy Guo, Nicholas J. Hand, Daniel J. Rader
Abstract
Sortilin has been positively correlated with vascular disorders in humans. No study has yet evaluated the possible direct effect of sortilin on vascular function. We used pharmacological and genetic approaches coupled with study of murine and human samples to unravel the mechanisms recruited by sortilin in the vascular system. Sortilin induced endothelial dysfunction of mesenteric arteries through NADPH oxidase 2 (NOX2) isoform activation, dysfunction that was prevented by knockdown of acid sphingomyelinase (ASMase) or sphingosine kinase 1. In vivo, recombinant sortilin administration induced arterial hypertension in WT mice. In contrast, genetic deletion of sphingosine-1-phosphate receptor 3 (S1P3) and gp91phox/NOX2 resulted in preservation of endothelial function and blood pressure homeostasis after 14 days of systemic sortilin administration. Translating these research findings into the clinical setting, we detected elevated sortilin levels in hypertensive patients with endothelial dysfunction. Furthermore, in a population-based cohort of 270 subjects, we showed increased plasma ASMase activity and increased plasma levels of sortilin, S1P, and soluble NOX2-derived peptide (sNOX2-dp) in hypertensive subjects, and the increase was more pronounced in hypertensive subjects with uncontrolled blood pressure. Our studies reveal what we believe is a previously unrecognized role of sortilin in the impairment of vascular function and in blood pressure homeostasis and suggest the potential of sortilin and its mediators as biomarkers for the prediction of vascular dysfunction and high blood pressure.
Authors
Paola Di Pietro, Albino Carrizzo, Eduardo Sommella, Marco Oliveti, Licia Iacoviello, Augusto Di Castelnuovo, Fausto Acernese, Antonio Damato, Massimiliano De Lucia, Fabrizio Merciai, Paola Iesu, Eleonora Venturini, Raffaele Izzo, Valentina Trimarco, Michele Ciccarelli, Giuseppe Giugliano, Roberto Carnevale, Vittoria Cammisotto, Serena Migliarino, Nicola Virtuoso, Andrea Strianese, Viviana Izzo, Pietro Campiglia, Elena Ciaglia, Bodo Levkau, Annibale A. Puca, Carmine Vecchione
Abstract
Blood vessel abnormalization alters cancer cell metabolism and promotes cancer dissemination and metastasis. However, the biological features of the abnormalized blood vessels that facilitate cancer progression and whether they can be targeted therapeutically have not been fully investigated. Here, we found that an axon guidance molecule, fibronectin leucine-rich transmembrane protein 2 (FLRT2), is expressed preferentially in abnormalized vessels of advanced colorectal cancers in humans, and that its expression correlates negatively with long-term survival. Endothelial-specific deletion of Flrt2 in mice selectively pruned abnormalized vessels, resulting in a unique metabolic state termed “oxygen-glucose uncoupling”, which suppresses tumor metastasis. Moreover, Flrt2 deletion caused an increase in the number of mature vessels, resulting in a significant increase in the anti-tumor effects of immune checkpoint blockers. Mechanistically, we found that FLRT2 forms non-canonical inter-endothelial adhesions that safeguard against oxidative stress through homophilic binding. Together, our results demonstrate the existence of tumor-specific inter-endothelial adhesions that enable abnormalized vessels to facilitate cancer aggressiveness. Targeting this type of adhesion complex could be a safe and effective therapeutic option to suppress cancer progression.
Authors
Tomofumi Ando, Ikue Tai-Nagara, Yuki Sugiura, Dai Kusumoto, Koji Okabayashi, Yasuaki Kido, Kohji Sato, Hideyuki Saya, Sutip Navankasattusas, Dean Y. Li, Makoto Suematsu, Yuko Kitagawa, Elena Seiradake, Satoru Yamagishi, Yoshiaki Kubota
Abstract
Piezo1 forms mechanically-activated non-selective cation channels that contribute to endothelial response to fluid flow. Here we reveal an important role in the control of capillary density. Conditional endothelial-specific deletion of Piezo1 in adult mice depressed physical performance. Muscle microvascular endothelial cell apoptosis and capillary rarefaction were evident and sufficient to account for the effect on performance. There was selective upregulation of thrombospondin-2 (TSP2), an inducer of endothelial apoptosis, with no effect on thrombospondin-1 (TSP1), a related important player in muscle physiology. TSP2 was poorly expressed in muscle endothelial cells but robustly expressed in muscle pericytes, in which nitric oxide (NO) repressed the Tsp2 gene without effect on Tsp1. In the endothelial cells, Piezo1 was required for normal expression of endothelial nitric oxide synthase (eNOS). The data suggest an endothelial-pericyte partnership of muscle in which endothelial Piezo1 senses blood flow to sustain capillary density and thereby maintain physical capability.
Authors
Fiona Bartoli, Marjolaine Debant, Eulashini Chuntharpursat-Bon, Elizabeth L. Evans, Katie E. Musialowski, Gregory Parsonage, Lara C. Morley, T. Simon Futers, Piruthivi Sukumar, T. Scott Bowen, Mark T. Kearney, Laeticia Lichtenstein, Lee D. Roberts, David J. Beech
Copyright © 2022 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)