Arteriovenous malformations (AVMs) are high-flow lesions directly connecting arteries and veins. In the brain, AVM rupture can cause seizures, stroke, and death. Patients with AVMs exhibit reduced coverage of the vessels by pericytes, the mural cells of microvascular capillaries; however, the mechanism underlying this pericyte reduction and its association with AVM pathogenesis remains unknown. Notch signaling has been proposed to regulate critical pericyte functions. We hypothesized that Notch signaling in pericytes is crucial to maintain pericyte homeostasis and prevent AVM formation. We inhibited Notch signaling specifically in perivascular cells and analyzed the vasculature of these mice. The retinal vessels of mice with deficient perivascular Notch signaling developed severe AVMs, together with a significant reduction in pericytes and vascular smooth muscle cells (vSMC) in the arteries, while vSMCs were increased in the veins. Vascular malformations and pericyte loss were also observed in the forebrain of embryonic mice deficient for perivascular Notch signaling. Moreover, the loss of Notch signaling in pericytes downregulated Pdgfrb levels and increased pericyte apoptosis, pointing to a critical role for Notch in pericyte survival. Overall, our findings reveal a mechanism of AVM formation and highlight the Notch signaling pathway as an essential mediator in this process.
Taliha Nadeem, Wil Bogue, Bianca Bigit, Henar Cuervo
Proprotein convertase subtilisin/kexin type 9 (PCSK9) affects cholesterol homeostasis by targeting hepatic low-density lipoprotein receptor (LDLR) for lysosomal degradation. Clinically, PCSK9 inhibitors effectively reduce LDL cholesterol (LDL-C) level and the incidence of cardiovascular events. Because microRNAs (miRs) are integral regulators of cholesterol homeostasis, we investigated the involvement of miR-483 in regulating LDL-C metabolism. Using in silico analysis, we predicted that miR-483-5p targets the 3’UTR of PCSK9 mRNA. In HepG2 cells, miR-483-5p targeted the PCSK9 3’UTR, leading to decreased PCSK9 protein and mRNA expression, increased LDLR expression and enhanced LDL-C uptake. In hyperlipidemic mice and humans, serum levels of total cholesterol and LDL-C were inversely correlated with miR-483-5p level. In mice, hepatic miR-483 overexpression increased LDLR level by targeting Pcsk9, with a significant reduction in plasma total cholesterol and LDL-C levels. Mechanistically, the cholesterol-lowering effect of miR-483-5p was significant in mice receiving AAV8 PCSK9-3’UTR but not Ldlr-knockout mice or mice receiving AAV8 PCSK9-3’UTR (deltaBS) with the miR-483-5p targeting site deleted. Thus, exogenously administered miR-483 or similarly optimized compounds have potential to ameliorate hypercholesterolemia.
Jianjie Dong, Ming He, Jie Li, Ariane R. Pessentheiner, Chen Wang, Jin Zhang, Yameng Sun, Wei-Ting Wang, Yuqing Zhang, Junhui Liu, Shen-Chih Wang, Po-Hsun Huang, Philip L.S.M. Gordts, Zu-Yi Yuan, Sotirios Tsimikas, John Y-J Shyy
Resident vascular adventitial SCA1(+) progenitor (AdvSca1) cells are essential in vascular development and injury. However, the heterogeneity of AdvSca1 cells presents a unique challenge in understanding signaling pathways orchestrating their behavior in homeostasis and injury responses. Using smooth muscle cell (SMC) lineage tracing models, we identified a subpopulation of AdvSca1 cells (AdvSca1-SM) originating from mature SMCs that undergo reprogramming in situ and exhibit a multipotent phenotype. Here we employed lineage tracing and RNA sequencing to define the signaling pathways regulating SMC-to-AdvSca1-SM cell reprogramming and AdvSca1-SM progenitor cell phenotype. Unbiased hierarchical clustering revealed that genes related to hedgehog/WNT/beta-catenin signaling are significantly enriched in AdvSca1-SM cells, emphasizing the importance of this signaling axis in the reprogramming event. Leveraging AdvSca1-SM-specific expression of Gli1, we generated Gli1-CreERT2-ROSA26-YFP reporter mice to selectively track AdvSca1-SM cells. We demonstrated that physiologically relevant vascular injury or AdvSca1-SM cell-specific Klf4 depletion facilitated the proliferation and differentiation of AdvSca1-SM cells to a pro-fibrotic myofibroblast phenotype rather than macrophages. Surprisingly, AdvSca1-SM cells selectively contributed to adventitial remodeling and fibrosis, but little to neointima formation. Together, these findings strongly support therapeutics aimed at preserving the AdvSca1-SM cell phenotype as a viable anti-fibrotic approach.
Sizhao Lu, Austin J. Jolly, Keith A. Strand, Allison M. Dubner, Marie F. Mutryn, Karen S. Moulton, Raphael A. Nemenoff, Mark W. Majesky, Mary C.M. Weiser-Evans
Long non-coding RNAs (lncRNAs) play important roles in regulating diverse cellular processes in the vessel wall, including atherosclerosis. RNAseq profiling of intimal lesions revealed a lncRNA, VINAS (Vascular INfllammation and Atherosclerosis lncRNA Sequence), that is enriched in the aortic intima and regulates vascular inflammation. Aortic intimal expression of VINAS fell with atherosclerotic progression and rose with regression. VINAS knockdown reduced atherosclerotic lesion formation by 55% in LDLR-/- mice, independent of effects on circulating lipids, by decreasing inflammation in the vessel wall. Loss- and gain-of-function studies in vitro demonstrated that VINAS serves as a critical regulator of inflammation by modulating NF-κB and MAPK signaling pathways. VINAS knockdown decreased the expression of key inflammatory markers, such as MCP-1, TNF-α, IL-1β , COX-2, in endothelial (EC), vascular smooth muscle cells, and bone marrow-derived macrophages. Moreover, VINAS silencing decreased expression of leukocyte adhesion molecules VCAM-1, E-selectin, and ICAM-1 and reduced monocyte adhesion to ECs. DEPDC4, an evolutionary conserved human ortholog of VINAS with ~74% homology, shows similar regulation in human and pig atherosclerotic specimens. DEPDC4 knockdown replicated VINAS’ anti-inflammatory effects in human ECs. These findings reveal a novel lncRNA that regulates vascular inflammation, with broad implications for vascular diseases.
Viorel Simion, Haoyang Zhou, Jacob B. Pierce, Dafeng Yang, Stefan Haemmig, Yevgenia Tesmenitsky, Galina Sukhova, Peter H. Stone, Peter Libby, Mark W. Feinberg
Giant cell arteritis (GCA) is a common form of primary systemic vasculitis in adults with no reliable indicators of prognosis or treatment responses. We used single cell technologies to comprehensively map immune cell populations in the blood of patients with GCA and identified the CD66b+CD15+CD10lo/-CD64- band neutrophils and CD66bhiCD15+CD10lo/-CD64+/bright myelocytes/metamyelocytes to be unequivocally associated with both the clinical phenotype and response to treatment. Immature neutrophils were resistant to apoptosis, remained in the vasculature for a prolonged time, interacted with platelets, and extravasated into the tissue surrounding the temporal arteries of patients with GCA. We discovered that immature neutrophils generated high levels of extracellular reactive oxygen species, leading to enhanced protein oxidation and permeability of endothelial barrier in an in vitro co-culture system. The same populations were also detected in other systemic vasculitides. These findings link functions of immature neutrophils to disease pathogenesis, establishing a new clinical cellular signature of GCA and suggesting new therapeutic approaches in systemic vascular inflammation.
Lihui Wang, Zhichao Ai, Tariq E. Khoyratty, Kristina Zec, Hayley L. Eames, Erinke van Grinsven, Alison Hudak, Susan Morris, David J. Ahern, Claudia Monaco, Evgeniy B. Eruslanov, Raashid Luqmani, Irina A. Udalova
Compromised muscle mitochondrial metabolism is a hallmark of peripheral arterial disease, especially in patients with the most severe clinical manifestation - critical limb ischemia (CLI). We asked whether inflexibility in metabolism is critical for the development of myopathy in ischemic limb muscles. Using Polg mtDNA mutator (D257A) mice, we reveal remarkable protection from hindlimb ischemia (HLI) due to a unique and beneficial adaptive enhancement of glycolytic metabolism and elevated ischemic muscle PFKFB3. Similar to the relationship between mitochondria from CLI and claudicating patient muscles, BALB/c muscle mitochondria are uniquely dysfunctional after HLI onset as compared to the BL6 parental strain. AAV-mediated over-expression of PFKFB3 in BALB/c limb muscles improved muscle contractile function and limb blood flow following HLI. Enrichment analysis of RNA sequencing data on muscle from CLI patients revealed a unique deficit in the Glucose Metabolism Reactome. Muscles from these patients express lower PFKFB3 protein and their muscle progenitor cells possess decreased glycolytic flux capacity in vitro. Here we show supplementary glycolytic flux as sufficient to protect against ischemic myopathy in instances where reduced blood flow related mitochondrial function is compromised pre-clinically. Additionally, our data reveal reduced glycolytic flux as a common characteristic of CLI patient limb skeletal muscle.
Terence E. Ryan, Cameron A. Schmidt, Michael D. Tarpey, Adam J. Amorese, Dean Yamaguchi, Emma Goldberg, Melissa R. Iñigo, Reema Karnekar, Allison R. O’Rourke, James M. Ervasti, Patricia Brophy, Thomas Green, P. Darrell Neufer, Kelsey H. Fisher-Wellman, Espen Spangenburg, Joseph McClung
Angiogenesis is essential for cardiac functional recovery after myocardial infarction (MI). HSPA12B is predominately expressed in endothelial cells and required for angiogenesis. Yes-associated protein (YAP) plays an important role in tumor angiogenesis. This study investigated the cooperative role of HSPA12B and YAP in angiogenesis post-MI. Silencing of either HSPA12B or YAP impairs hypoxia-promoted endothelial cell proliferation and angiogenesis. Deficiency of HSPA12B suppresses YAP expression and nuclear translocation following hypoxia. Knockdown of YAP attenuates hypoxia-stimulated HSPA12B nuclear translocation and abrogates HSPA12B-promoted endothelial cell angiogenesis. Mechanistically, hypoxia induced an interaction between endothelial HSPA12B and YAP. ChIP assay shows that HSPA12B is a target gene of YAP/transcriptional enhanced associated domain4 (TEAD4) and a co-activator in YAP-associated angiogenesis. In vivo studies using the MI model show that endothelial specific deficiency of HSPA12B (eHspa12b-/-) or YAP (eYap-/-) impairs angiogenesis and exacerbates cardiac dysfunction, when compared with wild type (WT) mice. MI increased YAP expression and nuclear translocation in WT hearts, but not in eHspa12b-/- hearts. HSPA12B expression and nuclear translocation were up-regulated in WT MI hearts, but not in eYap-/- MI myocardium. Our data demonstrated that endothelial HSPA12B is a novel target and co-activator for YAP/TEAD4 and cooperates with YAP to regulate endothelial angiogenesis post-MI.
Min Fan, Kun Yang, Xiaohui Wang, Yana Wang, Fei Tu, Tuanzhu Ha, Li Liu, David L. Williams, Chuanfu Li
Stem cell transplantation has emerged as a promising strategy in regenerative medicine. However, the poor survival and persistence of the transplanted cells, including mesenchymal stem cells (MSCs), in the hostile ischemic microenvironments represents a major therapeutic barrier. Here we report that plasminogen (Plg) stimulated MSC functions and promoted MSC survival during tissue repair after ischemia. Genetic Plg ablation abolished MSC survival, migration, and proliferation in mouse ischemic limbs, and abrogated MSC-mediated blood reperfusion, neovascularization, and tissue repair after ischemia, suggesting a critical role for Plg in MSC-mediated tissue repair. Furthermore, multiplex cytokine array analysis identified that Plg cleaved and activated cysteine-rich protein 61 (Cyr61), an ECM-associated growth factor, to stimulate MSC survival and migration. Overexpression with truncated Cyr61 in MSCs rescued blood reperfusion after hind limb ischemia in Plg-deficient mice. Finally, Plg-mediated Cyr61 cleavage promoted endothelial cell migration and neovascularization in vitro and in vivo. Our study reveals that Plg promotes MSC survival, persistence, and paracrine effects and improves postischemic neovascularization and tissue repair through Cyr61 cleavage and activation. Thus, targeting Plg/Cyr61 may offer exciting therapeutic opportunities for strengthening MSC therapy in ischemic diseases.
Hao Duan, Zhenqiang He, Maohuan Lin, Yanling Wang, Fan Yang, R. Alan Mitteer, Hyun-Jun Kim, Eujing Yeo, Hongyu Han, Ling Qin, Yi Fan, Yanqing Gong
Prostaglandin E2 and its cognate EP1–4 receptors play important roles in blood pressure (BP) regulation. Herein, we show that endothelial cell–specific (EC-specific) EP4 gene–knockout mice (EC-EP4–/–) exhibited elevated, while EC-specific EP4-overexpression mice (EC-hEP4OE) displayed reduced, BP levels compared with the control mice under both basal and high-salt diet–fed conditions. The altered BP was completely abolished by treatment with l–NG-nitro-l-arginine methyl ester (l-NAME), a competitive inhibitor of endothelial nitric oxide synthase (eNOS). The mesenteric arteries of the EC-EP4–/– mice showed increased vasoconstrictive response to angiotensin II and reduced vasorelaxant response to acetylcholine, both of which were eliminated by l-NAME. Furthermore, EP4 activation significantly reduced BP levels in hypertensive rats. Mechanistically, EP4 deletion markedly decreased NO contents in blood vessels via reducing eNOS phosphorylation at Ser1177. EP4 enhanced NO production mainly through the AMPK pathway in cultured ECs. Collectively, our findings demonstrate that endothelial EP4 is essential for BP homeostasis.
Hu Xu, Bingying Fang, Shengnan Du, Sailun Wang, Qingwei Li, Xiao Jia, Chengzhen Bao, Lan Ye, Xue Sui, Lei Qian, Zhilin Luan, Guangrui Yang, Feng Zheng, Nanping Wang, Lihong Chen, Xiaoyan Zhang, Youfei Guan
Despite advances in lipid-lowering therapies, people with diabetes continue to experience more limited cardiovascular benefits. In diabetes, hyperglycemia sustains inflammation and preempts vascular repair. We tested the hypothesis that the receptor for advanced glycation end-products (RAGE) contributes to these maladaptive processes. We report that transplantation of aortic arches from diabetic, Western diet–fed Ldlr—/— mice into diabetic Ager—/— (Ager, the gene encoding RAGE) versus WT diabetic recipient mice accelerated regression of atherosclerosis. RNA-sequencing experiments traced RAGE-dependent mechanisms principally to the recipient macrophages and linked RAGE to interferon signaling. Specifically, deletion of Ager in the regressing diabetic plaques downregulated interferon regulatory factor 7 (Irf7) in macrophages. Immunohistochemistry studies colocalized IRF7 and macrophages in both murine and human atherosclerotic plaques. In bone marrow–derived macrophages (BMDMs), RAGE ligands upregulated expression of Irf7, and in BMDMs immersed in a cholesterol-rich environment, knockdown of Irf7 triggered a switch from pro- to antiinflammatory gene expression and regulated a host of genes linked to cholesterol efflux and homeostasis. Collectively, this work adds a new dimension to the immunometabolic sphere of perturbations that impair regression of established diabetic atherosclerosis and suggests that targeting RAGE and IRF7 may facilitate vascular repair in diabetes.
Laura Senatus, Raquel López-Díez, Lander Egaña-Gorroño, Jianhua Liu, Jiyuan Hu, Gurdip Daffu, Qing Li, Karishma Rahman, Yuliya Vengrenyuk, Tessa J. Barrett, M. Zahidunnabi Dewan, Liang Guo, Daniela Fuller, Aloke V. Finn, Renu Virmani, Huilin Li, Richard A. Friedman, Edward A. Fisher, Ravichandran Ramasamy, Ann Marie Schmidt
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