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Abstract
Formation of arterial vasculature, here termed arteriogenesis, is a central process in embryonic vascular development as well as in adult tissues. Although the process of capillary formation, angiogenesis, is relatively well understood, much remains to be learned about arteriogenesis. Recent discoveries point to the key role played by vascular endothelial growth factor receptor 2 in control of this process and to newly identified control circuits that dramatically influence its activity. The latter can present particularly attractive targets for a new class of therapeutic agents capable of activation of this signaling cascade in a ligand-independent manner, thereby promoting arteriogenesis in diseased tissues.
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Affiliation(s)
- Michael Simons
- From the Department of Internal Medicine, Yale Cardiovascular Research Center, Section of Cardiovascular Medicine (M.S., A.E.) and Departments of Cell Biology (M.S.) and Molecular Physiology (A.E.), Yale University School of Medicine, New Haven, CT.
| | - Anne Eichmann
- From the Department of Internal Medicine, Yale Cardiovascular Research Center, Section of Cardiovascular Medicine (M.S., A.E.) and Departments of Cell Biology (M.S.) and Molecular Physiology (A.E.), Yale University School of Medicine, New Haven, CT.
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2
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Unthank JL, McClintick JN, Labarrere CA, Li L, Distasi MR, Miller SJ. Molecular basis for impaired collateral artery growth in the spontaneously hypertensive rat: insight from microarray analysis. Physiol Rep 2013; 1:e0005. [PMID: 24303120 PMCID: PMC3831906 DOI: 10.1002/phy2.5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 05/08/2013] [Indexed: 01/08/2023] Open
Abstract
Analysis of global gene expression in mesenteric control and collateral arteries was used to investigate potential molecules, pathways, and mechanisms responsible for impaired collateral growth in the Spontaneously Hypertensive Rat (SHR). A fundamental difference was observed in overall gene expression pattern in SHR versus Wistar Kyoto (WKY) collaterals; only 6% of genes altered in collaterals were similar between rat strains. Ingenuity® Pathway Analysis (IPA) identified major differences between WKY and SHR in networks and biological functions related to cell growth and proliferation and gene expression. In SHR control arteries, several mechano-sensitive and redox-dependent transcription regulators were downregulated including JUN (-5.2×, P = 0.02), EGR1 (-4.1×, P = 0.01), and NFĸB1 (-1.95×, P = 0.04). Predicted binding sites for NFĸB and AP-1 were present in genes altered in WKY but not SHR collaterals. Immunostaining showed increased NFĸB nuclear translocation in collateral arteries of WKY and apocynin-treated SHR, but not in untreated SHR. siRNA for the p65 subunit suppressed collateral growth in WKY, confirming a functional role of NFkB. Canonical pathways identified by IPA in WKY but not SHR included nitric oxide and renin-angiotensin system signaling. The angiotensin type 1 receptor (AGTR1) exhibited upregulation in WKY collaterals, but downregulation in SHR; pharmacological blockade of AGTR1 with losartan prevented collateral luminal expansion in WKY. Together, these results suggest that collateral growth impairment results from an abnormality in a fundamental regulatory mechanism that occurs at a level between signal transduction and gene transcription and implicate redox-dependent modulation of mechano-sensitive transcription factors such as NFĸB as a potential mechanism.
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Affiliation(s)
- Joseph L Unthank
- Department of Surgery, Indiana University School of Medicine Indianapolis, Indiana, 46202 ; Department of Cellular and Integrative Physiology, Indiana University School of Medicine Indianapolis, Indiana, 46202 ; Indiana Center for Vascular Biology and Medicine, Indiana University School of Medicine Indianapolis, Indiana, 46202
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3
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Abstract
Peripheral arterial disease (PAD) is a common vascular disease that reduces blood flow capacity to the legs of patients. PAD leads to exercise intolerance that can progress in severity to greatly limit mobility, and in advanced cases leads to frank ischemia with pain at rest. It is estimated that 12 to 15 million people in the United States are diagnosed with PAD, with a much larger population that is undiagnosed. The presence of PAD predicts a 50% to 1500% increase in morbidity and mortality, depending on severity. Treatment of patients with PAD is limited to modification of cardiovascular disease risk factors, pharmacological intervention, surgery, and exercise therapy. Extended exercise programs that involve walking approximately five times per week, at a significant intensity that requires frequent rest periods, are most significant. Preclinical studies and virtually all clinical trials demonstrate the benefits of exercise therapy, including improved walking tolerance, modified inflammatory/hemostatic markers, enhanced vasoresponsiveness, adaptations within the limb (angiogenesis, arteriogenesis, and mitochondrial synthesis) that enhance oxygen delivery and metabolic responses, potentially delayed progression of the disease, enhanced quality of life indices, and extended longevity. A synthesis is provided as to how these adaptations can develop in the context of our current state of knowledge and events known to be orchestrated by exercise. The benefits are so compelling that exercise prescription should be an essential option presented to patients with PAD in the absence of contraindications. Obviously, selecting for a lifestyle pattern that includes enhanced physical activity prior to the advance of PAD limitations is the most desirable and beneficial.
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Affiliation(s)
- Tara L Haas
- Angiogenesis Research Group, Muscle Health Research Centre, Faculty of Health, York University, Toronto, Ontario, Canada
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4
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Shaw JH, Lloyd PG. Post-transcriptional regulation of placenta growth factor mRNA by hydrogen peroxide. Microvasc Res 2012; 84:155-60. [PMID: 22683469 DOI: 10.1016/j.mvr.2012.05.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 05/10/2012] [Accepted: 05/29/2012] [Indexed: 01/10/2023]
Abstract
In tissues containing pre-existing collateral vessels, occlusion of an upstream supply artery results in diversion of blood flow through these vessels, protecting the distal tissue from ischemia. The sudden rise in blood flow through collateral vessels exerts shear stress upon the vessel wall, thereby providing the initial stimulus for arteriogenesis. Arteriogenesis, the structural expansion of collateral circulation, involves smooth muscle cell (SMC) proliferation which leads to increased vessel diameter and wall thickness. Since shear is sensed at the level of endothelial cells (EC), communication from EC to the underlying SMC must occur as part of this process. We previously reported that endothelial cells (EC) exposed to shear stress release hydrogen peroxide (H(2)O(2)), and that H(2)O(2) can signal vascular SMC to increase gene and protein expression of placenta growth factor (PLGF), a known mediator of arteriogenesis. The purpose of the current study was to further elucidate the mechanism whereby PLGF is regulated by H(2)O(2). We found that a single, physiological dose of H(2)O(2) increases PLGF mRNA half-life, but has no effect on PLGF promoter activity, in human coronary artery SMC (CASMC). We further demonstrated that the H(2)O(2)-induced increase in PLGF mRNA levels partially relies on p38 MAPK, JNK and ERK1/2 pathways. Finally, we showed that chronic exposure to pathological levels of H(2)O(2) further increases PLGF mRNA levels, but does not result in a corresponding increase in PLGF secreted protein. These data suggest that PLGF regulation has an important translational component. To our knowledge, this is the first study to characterize post-transcriptional regulation of PLGF mRNA by H(2)O(2) in vascular SMC. These findings provide new insights into the regulation of this important growth factor and increase our understanding of PLGF-driven arteriogenesis.
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Affiliation(s)
- Jennifer H Shaw
- Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078, USA
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Teunissen PF, Horrevoets AJ, van Royen N. The coronary collateral circulation: Genetic and environmental determinants in experimental models and humans. J Mol Cell Cardiol 2012; 52:897-904. [DOI: 10.1016/j.yjmcc.2011.09.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 08/25/2011] [Accepted: 09/12/2011] [Indexed: 12/27/2022]
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Faber JE, Zhang H, Lassance-Soares RM, Prabhakar P, Najafi AH, Burnett MS, Epstein SE. Aging causes collateral rarefaction and increased severity of ischemic injury in multiple tissues. Arterioscler Thromb Vasc Biol 2011; 31:1748-56. [PMID: 21617137 DOI: 10.1161/atvbaha.111.227314] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Aging is a major risk factor for increased ischemic tissue injury. Whether collateral rarefaction and impaired remodeling contribute to this is unknown. We quantified the number and diameter of native collaterals and their remodeling in 3-, 16-, 24-, and 31-month-old mice. METHODS AND RESULTS Aging caused an "age-dose-dependent" greater drop in perfusion immediately after femoral artery ligation, followed by a diminished recovery of flow and increase in tissue injury. These effects were associated with a decline in collateral number, diameter, and remodeling. Angiogenesis was also impaired. Mechanistically, these changes were not accompanied by reduced recruitment of T cells or macrophages to remodeling collaterals. However, endothelial nitric oxide synthase signaling was dysfunctional, as indicated by increased protein nitrosylation and less phosphorylated endothelial nitric oxide synthase and vasodilator-stimulated phosphoprotein in collateral wall cells. The cerebral circulation exhibited a similar age-dose-dependent loss of collateral number and diameter and increased tortuosity, resulting in an increase in collateral resistance and infarct volume (eg, 6- and 3-fold, respectively, in 24-month-old mice) after artery occlusion. This was not associated with rarefaction of similarly sized arterioles. Collateral remodeling was also reduced. CONCLUSIONS Our findings demonstrate that aging causes rarefaction and insufficiency of the collateral circulation in multiple tissues, resulting in more severe ischemic tissue injury.
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Affiliation(s)
- James E Faber
- Department of Physiology, McAllister Heart Institute, University of North Carolina, Chapel Hill, 27599-7545, USA.
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Willis LM, Freeman L, Bickford PC, Quintero EM, Umphlet CD, Moore AB, Goetzl L, Granholm AC. Blueberry supplementation attenuates microglial activation in hippocampal intraocular grafts to aged hosts. Glia 2010; 58:679-90. [PMID: 20014277 PMCID: PMC2834232 DOI: 10.1002/glia.20954] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Transplantation of central nervous tissue has been proposed as a therapeutic intervention for age-related neurodegenerative diseases and stroke. However, survival of embryonic neuronal cells is hampered by detrimental factors in the aged host brain such as circulating inflammatory cytokines and oxidative stress. We have previously found that supplementation with 2% blueberry in the diet increases graft growth and neuronal survival in intraocular hippocampal grafts to aged hosts. In the present study we explored possible biochemical mechanisms for this increased survival, and we here report decreased microglial activation and astrogliosis in intraocular hippocampal grafts to middle-aged hosts fed a 2% blueberry diet. Markers for astrocytes and for activated microglial cells were both decreased long-term after grafting to blueberry-treated hosts compared with age-matched rats on a control diet. Similar findings were obtained in the host brain, with a reduction in OX-6 immunoreactive microglial cells in the hippocampus of those recipients treated with blueberry. In addition, immunoreactivity for the pro-inflammatory cytokine IL-6 was found to be significantly attenuated in intraocular grafts by the 2% blueberry diet. These studies demonstrate direct effects of blueberry upon microglial activation both during isolated conditions and in the aged host brain and suggest that this nutraceutical can attenuate age-induced inflammation.
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Affiliation(s)
- Lauren M. Willis
- Department of Neurosciences and the Center on Aging, Medical University of South Carolina, Charleston, SC, USA
| | - Linnea Freeman
- Department of Neurosciences and the Center on Aging, Medical University of South Carolina, Charleston, SC, USA
| | - Paula C. Bickford
- Department of Neurosurgery, Center for Excellence for Aging and Brain Repair, University of South Florida, Tampa, FL, USA
- James A. Haley Veterans' Hospital Medical Center, Tampa, FL, USA
| | - E. Matthew Quintero
- Department of Neurosciences and the Center on Aging, Medical University of South Carolina, Charleston, SC, USA
| | - Claudia D. Umphlet
- Department of Neurosciences and the Center on Aging, Medical University of South Carolina, Charleston, SC, USA
| | - Alfred B. Moore
- Department of Neurosciences and the Center on Aging, Medical University of South Carolina, Charleston, SC, USA
| | - Laura Goetzl
- Department of Ob/Gyn, Division of Maternal Fetal Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - Ann-Charlotte Granholm
- Department of Neurosciences and the Center on Aging, Medical University of South Carolina, Charleston, SC, USA
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Ziegler MA, Distasi MR, Bills RG, Miller SJ, Alloosh M, Murphy MP, Akingba AG, Sturek M, Dalsing MC, Unthank JL. Marvels, mysteries, and misconceptions of vascular compensation to peripheral artery occlusion. Microcirculation 2010; 17:3-20. [PMID: 20141596 PMCID: PMC2909670 DOI: 10.1111/j.1549-8719.2010.00008.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Peripheral arterial disease is a major health problem and there is a significant need to develop therapies to prevent its progression to claudication and critical limb ischemia. Promising results in rodent models of arterial occlusion have generally failed to predict clinical success and led to questions of their relevance. While sub-optimal models may have contributed to the lack of progress, we suggest that advancement has also been hindered by misconceptions of the human capacity for compensation and the specific vessels which are of primary importance. We present and summarize new and existing data from humans, Ossabaw miniature pigs, and rodents which provide compelling evidence that natural compensation to occlusion of a major artery (i) may completely restore perfusion, (ii) occurs in specific pre-existing small arteries, rather than the distal vasculature, via mechanisms involving flow-mediated dilation and remodeling (iii) is impaired by cardiovascular risk factors which suppress the flow-mediated mechanisms and (iv) can be restored by reversal of endothelial dysfunction. We propose that restoration of the capacity for flow-mediated dilation and remodeling in small arteries represents a largely unexplored potential therapeutic opportunity to enhance compensation for major arterial occlusion and prevent the progression to critical limb ischemia in the peripheral circulation.
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Affiliation(s)
- Matthew A Ziegler
- Department of Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
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9
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Abstract
Arterial lumen narrowing and vascular occlusion is the actual cause of morbidity and mortality in atherosclerotic disease. Collateral artery formation (arteriogenesis) refers to an active remodelling of non-functional vascular anastomoses to functional collateral arteries, capable to bypass the site of obstruction and preserve the tissue that is jeopardized by ischaemia. Hemodynamic forces such as shear stress and wall stress play a pivotal role in collateral artery formation, accompanied by the expression of various cytokines and invasion of circulating leucocytes. Arteriogenesis hence represents an important compensatory mechanism for atherosclerotic vessel occlusion. As arteriogenesis mostly occurs when lumen narrowing by atherosclerotic plaques takes place, presence of cardiovascular risk factors (e.g. hypertension, hypercholesterolaemia and diabetes) is highly likely. Risk factors for atherosclerotic disease affect collateral artery growth directly and indirectly by altering hemodynamic forces or influencing cellular function and proliferation. Adequate collateralization varies significantly among atherosclerotic patients, some profit from the presence of extensive collateral networks, whereas others do not. Cardiovascular risk factors could increase the risk of adverse cardiovascular events in certain patients because of the reduced protection through an alternative vascular network. Likewise, drugs primarily thought to control cardiovascular risk factors might contribute or counteract collateral artery growth. This review summarizes current knowledge on the influence of cardiovascular risk factors and the effects of cardiovascular medication on the development of collateral vessels in experimental and clinical studies.
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Affiliation(s)
- D de Groot
- Laboratory of Experimental Cardiology, UMC Utrecht, the Netherlands
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Zhou X, Bohlen HG, Unthank JL, Miller SJ. Abnormal nitric oxide production in aged rat mesenteric arteries is mediated by NAD(P)H oxidase-derived peroxide. Am J Physiol Heart Circ Physiol 2009; 297:H2227-33. [PMID: 19783779 DOI: 10.1152/ajpheart.00325.2009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Previous work in our laboratory showed increased basal periarterial nitric oxide (NO) and H2O2 concentrations in the spontaneously hypertensive rat, characterized by oxidant stress, as well as impaired flow-mediated NO production that was corrected by a reduction of periarterial H2O2. Aging is also associated with an increase in vascular reactive oxygen species and results in abnormal vascular function. The current study was designed to assess the role of H2O2 in regulating NO production during vascular aging. In vivo, real-time NO and H2O2 concentrations were measured by microelectrodes in mesenteric arteries of retired breeder (aged; 8-12 mo) and young (2 to 3 mo) Wistar-Kyoto rats under conditions of altered flow. The results in aged rats revealed elevated basal NO (1,611+/-286 vs. 793+/-112 nM, P<0.05) and H2O2 concentrations (16+/-2 vs. 9+/-1 microM, P<0.05) and a flow-mediated increase in H2O2 but not NO production. Pretreatment of aged rats with the antioxidant apocynin lowered both basal H2O2 (8+/-1 microM) and NO (760+/-102 nM) to young levels and restored flow-mediated NO production. Similar results were obtained with the NAD(P)H oxidase inhibitor gp91ds-tat. In addition, acute incubation with topical polyethylene-glycolated catalase lowered the baseline NO concentration and restored flow-mediated NO production. Taken together, the data indicate that elevated baseline and suppressed flow-mediated NO production in aged Wistar-Kyoto rats are mediated by NAD(P)H oxidase-derived H2O2.
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Affiliation(s)
- Xiaosun Zhou
- Department of Surgery, Indiana University School of Medicine, 1001 W. 10th St., WD OPW 425F, Indianapolis, IN 46202-2879, USA
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Miller SJ, Coppinger BJ, Zhou X, Unthank JL. Antioxidants reverse age-related collateral growth impairment. J Vasc Res 2009; 47:108-14. [PMID: 19729957 DOI: 10.1159/000235965] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2008] [Accepted: 02/09/2009] [Indexed: 01/02/2023] Open
Abstract
Aging is a major risk factor for the development of cardiovascular diseases, including arterial occlusive disease. Oxidant stress increases with age, and may be a significant factor contributing to vascular dysfunction and disease. We have shown that aging and hypertension impair collateral growth, the natural compensatory response to arterial occlusive disease, and that antioxidants restore collateral growth in young hypertensive rats. The aim of this study was to test the hypothesis that oxidant stress mediates collateral growth impairment in nondiseased, aged rats. Ileal arteries were induced to become collaterals via ligation of adjacent arteries. Growth was assessed at 7 days by repeated in vivo measurements and comparison to same-animal control arteries. Collateral diameter enlargement did not occur in aged rats, but luminal expansion was stimulated by pretreatment with tempol. Co-administration of L-NAME with tempol prevented tempol-mediated collateral development. Expression of p22(phox) mRNA was increased in aged versus young rat arteries, suggesting NAD(P)H oxidase as a source of reactive oxygen species. Treatment with apocynin increased collateral growth capacity, whether administered prior to, or 7 days following, arterial ligation. The results suggest that antioxidant treatment may be useful in promoting collateral growth to compensate for age-related arterial occlusive disease.
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Affiliation(s)
- Steven J Miller
- Department of Surgery, Indiana University School of Medicine, Indianapolis, IN 46202-2879, USA.
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Distasi MR, Case J, Ziegler MA, Dinauer MC, Yoder MC, Haneline LS, Dalsing MC, Miller SJ, Labarrere CA, Murphy MP, Ingram DA, Unthank JL. Suppressed hindlimb perfusion in Rac2-/- and Nox2-/- mice does not result from impaired collateral growth. Am J Physiol Heart Circ Physiol 2009; 296:H877-86. [PMID: 19151256 PMCID: PMC2660231 DOI: 10.1152/ajpheart.00772.2008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Accepted: 01/12/2009] [Indexed: 11/22/2022]
Abstract
While tissue perfusion and angiogenesis subsequent to acute femoral artery occlusion are suppressed in NADPH oxidase 2 (Nox2)-null (Nox2(-/-)) mice, studies have not established the role of Nox2 in collateral artery enlargement. Rac2 is a small GTPase that binds Nox2 and activates Nox2-based NAD(P)H oxidase but, unlike Nox2, is primarily restricted to bone marrow-derived cells. In this study, we used Rac2-null (Rac2(-/-)) and Nox2(-/-) mice with a novel method of identifying primary hindlimb collaterals to investigate the hypothesis that collateral growth requires these molecules. When initial experiments performed with femoral ligation demonstrated similar perfusion and collateral growth in Rac2(-/-) and wild-type C57BL/6J (BL6) mice, subsequent experiments were performed with a more severe ischemia model, femoral artery excision. After femoral excision, tissue perfusion was suppressed in Rac2(-/-) mice relative to BL6 mice. Histological assessment of ischemic injury including necrotic and regenerated muscle fibers and lipid and collagen deposition demonstrated greater injury in Rac2(-/-) mice. The diameters of primary collaterals identified during Microfil injection with intravital microscopy were enlarged to a similar extent in BL6 and Rac2(-/-) mice. Intimal cells in collateral cross sections were increased in number in both strains and were CD31 positive and CD45 negative. Circulating leukocytes and CD11b(+) cells were increased more in Rac2(-/-) than BL6 animals. Experiments performed in Nox2(-/-) mice to verify that the unexpected results related to collateral growth were not unique to Rac2(-/-) mice gave equivalent results. The data demonstrate that, subsequent to acute femoral artery excision, perfusion recovery is impaired in Rac2(-/-) and Nox2(-/-) mice but that collateral luminal expansion and intimal cell recruitment/proliferation are normal. These novel results indicate that collateral luminal expansion and intimal cell recruitment/proliferation are not mediated by Rac2 and Nox2.
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Affiliation(s)
- Matthew R Distasi
- Department of Cellular and Integrative Physiology, Indiana Univ. School of Medicine, 1001 W. 10th St., WD OPW 425 E, Indianapolis, IN 46202, USA
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