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Stewart GM, Cross TJ, Joyner MJ, Chase SC, Curry T, Lehrer-Graiwer J, Dufu K, Vlahakis NE, Johnson BD. Impact of Pharmacologically Left Shifting the Oxygen-Hemoglobin Dissociation Curve on Arterial Blood Gases and Pulmonary Gas Exchange During Maximal Exercise in Hypoxia. High Alt Med Biol 2021; 22:249-262. [PMID: 34152867 DOI: 10.1089/ham.2020.0159] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Stewart, Glenn M., Troy J. Cross, Michael J. Joyner, Steven C. Chase, Timothy Curry, Josh Lehrer-Graiwer, Kobina Dufu, Nicholas E. Vlahakis, and Bruce D. Johnson. Impact of pharmacologically left shifting the oxygen-hemoglobin dissociation curve on arterial blood gases and pulmonary gas exchange during maximal exercise in hypoxia. High Alt Med Biol. 22:249-262, 2021. Introduction: Physiological and pathological conditions, which reduce the loading of oxygen onto hemoglobin (Hb), can impair exercise capacity and cause debilitating symptoms. Accordingly, this study examined the impact of pharmacologically left shifting the oxygen-hemoglobin dissociation curve (ODC) on arterial oxygen saturation (SaO2) and exercise capacity. Methods: Eight healthy subjects completed a maximal incremental exercise test in hypoxia (FIO2: 0.125) and normoxia (FIO2: 0.21) before (Day 1) and after (Day 15) daily ingestion of 900 mg of voxelotor (an oxygen/Hb affinity modulator). Pulmonary gas exchange and arterial blood gases were assessed throughout exercise and at peak. Data for a 1,500 mg daily drug dose are reported in a limited cohort (n = 3). Results: Fourteen days of drug administration left shifted the ODC (p50 measured under standard conditions, Day 1: 28.0 ± 2.1 mmHg vs. Day 15: 26.1 ± 1.8 mmHg, p < 0.05). Throughout incremental exercise in hypoxia, SaO2 was systematically higher after drug (peak exercise SaO2 on Day 1: 71 ± 2 vs. Day 15: 81% ± 2%, p < 0.001), whereas oxygen extraction (Ca-vO2 diff) and consumption (VO2) were similar (peak exercise Ca-vO2 diff on Day 1: 11.5 ± 1.7 vs. Day 15: 11.0 ± 1.8 ml/100 ml blood, p = 0.417; peak VO2 on Day 1: 2.59 ± 0.39 vs. Day 15: 2.47 ± 0.43 l/min, p = 0.127). Throughout incremental exercise in normoxia, SaO2 was systematically higher after drug, whereas peak VO2 was reduced (peak exercise SaO2 on Day 1: 93.9 ± 1.8 vs. Day 15: 95.8% ± 1.0%, p = 0.008; peak VO2 on Day 1: 3.62 ± 0.55 vs. Day 15: 3.26 ± 52 l/min, p = 0.001). Conclusion: Pharmacologically increasing the affinity of Hb for oxygen improved SaO2 during hypoxia without impacting exercise capacity; however, left shifting the ODC in healthy individuals appears detrimental to exercise capacity in normoxia. Left shifting the ODC to different magnitudes and under more chronic forms of hypoxia warrants further study.
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Affiliation(s)
- Glenn M Stewart
- Human Integrative and Environmental Physiology Laboratory, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - Troy J Cross
- Human Integrative and Environmental Physiology Laboratory, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA.,Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
| | - Michael J Joyner
- Department of Anesthesia and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Steven C Chase
- Human Integrative and Environmental Physiology Laboratory, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
| | - Timothy Curry
- Department of Anesthesia and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Kobina Dufu
- Global Blood Therapeutics, South San Francisco, California, USA
| | | | - Bruce D Johnson
- Human Integrative and Environmental Physiology Laboratory, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
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Stewart GM, Chase S, Cross TJ, Wheatley-Guy CM, Joyner MJ, Curry T, Lehrer-Graiwer J, Dufu K, Vlahakis NE, Johnson BD. Effects of an allosteric hemoglobin affinity modulator on arterial blood gases and cardiopulmonary responses during normoxic and hypoxic low-intensity exercise. J Appl Physiol (1985) 2020; 128:1467-1476. [PMID: 32324473 DOI: 10.1152/japplphysiol.00185.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Numerous pathophysiological conditions induce hypoxemia-related cardiopulmonary perturbations, decrements in exercise capacity, and debilitating symptoms. Accordingly, this study investigated the efficacy of an allosteric hemoglobin modulator (voxelotor) to enhance arterial oxygen saturation during low-intensity exercise in hypoxia. Eight normal healthy subjects (36 ± 7 yr; 73.8 ± 9.5 kg; 3 women) completed a submaximal cycling test (60 W) under normoxic ([Formula: see text]: 0.21; O2 partial pressure: 144 mmHg) and hypoxic ([Formula: see text]: 0.125; O2 partial pressure: 82 mmHg) conditions before (day 1) and after (day 15) 14 days of oral drug administration. While stationary on a cycle ergometer and during exercise, ratings of perceived exertion (RPE) and dyspnea, oxygen consumption (V̇o2), and cardiac output (Q) were measured noninvasively, while arterial blood pressure (MAP) and blood gases ([Formula: see text], [Formula: see text], and [Formula: see text]) were measured invasively. The 14-day drug administration left shifted the oxygen-hemoglobin dissociation curve (ODC; p50 measured at standard pH and Pco2; day 1: 28.0 ± 2.1 mmHg vs. day 15: 26.1 ± 1.8 mmHg, P < 0.05). RPE, dyspnea, V̇o2, Q, and MAP were not different between day 1 and day 15. [Formula: see text] was similar during normoxia on day 1 and day 15 while stationary but higher during exercise (day 1: 95.2 ± 0.4% vs. day 15: 96.6 ± 0.3%, P < 0.05). [Formula: see text] was higher during hypoxia on day 15 while stationary (day 1: 82.9 ± 3.4% vs. day 15: 90.9 ± 1.8%, P < 0.05) and during exercise (day 1: 73.6 ± 2.5% vs. day 15: 84.8 ± 2.7%, P < 0.01). [Formula: see text] and [Formula: see text]were systematically higher and lower, respectively, after drug (P < 0.01), while the alveolar-arterial oxygen difference was unchanged suggesting hyperventilation contributed to the rise in [Formula: see text]. Oral administration of voxelotor left shifted the ODC and stimulated a mild hyperventilation, leading to improved arterial oxygen saturation without altering V̇o2 and central hemodynamics during rest and low-intensity exercise. This effect was more pronounced during submaximal hypoxic exercise, when arterial desaturation was more evident. Additional studies are needed to determine the effects of voxelotor during maximal exercise and under chronic forms of hypoxia.NEW & NOTEWORTHY In humans, a novel allosteric hemoglobin-oxygen affinity modulator was administered to comprehensively examine the cardiopulmonary consequences of stabilizing a portion of the available hemoglobin in a high-oxygen affinity state during submaximal exercise in normoxia and hypoxia. Oral administration of voxelotor enhanced arterial oxygen saturation during submaximal exercise without altering oxygen consumption and central hemodynamics; however, the partial pressure of arterial carbon dioxide was reduced and the partial pressure of arterial oxygen was increased implying that hyperventilation also contributed to the increase in oxygen saturation. The preservation of arterial oxygen saturation and content was particularly evident during hypoxic submaximal exercise, when arterial desaturation typically occurs, but this did not influence arterial-venous oxygen difference.
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Affiliation(s)
- Glenn M Stewart
- Human Integrative and Environmental Physiology Laboratory, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
| | - Steven Chase
- Human Integrative and Environmental Physiology Laboratory, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
| | - Troy J Cross
- Human Integrative and Environmental Physiology Laboratory, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
| | - Courtney M Wheatley-Guy
- Human Integrative and Environmental Physiology Laboratory, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
| | - Michael J Joyner
- Department of Anesthesia and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | - Timothy Curry
- Department of Anesthesia and Perioperative Medicine, Mayo Clinic, Rochester, Minnesota
| | | | - Kobina Dufu
- Global Blood Therapeutics, South San Francisco, California
| | | | - Bruce D Johnson
- Human Integrative and Environmental Physiology Laboratory, Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
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Lamontagne F, McIntyre L, Dodek P, Heels-Ansdell D, Meade M, Pemberton J, Skrobik Y, Seppelt I, Vlahakis NE, Muscedere J, Reece G, Ostermann M, Padayachee S, Alhashemi J, Walsh M, Lewis B, Schiff D, Moody A, Zytaruk N, Leblanc M, Cook DJ. Nonleg venous thrombosis in critically ill adults: a nested prospective cohort study. JAMA Intern Med 2014; 174:689-96. [PMID: 24638843 DOI: 10.1001/jamainternmed.2014.169] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Critically ill patients are at risk of venous thrombosis, and therefore guidelines recommend daily thromboprophylaxis. Deep vein thrombosis (DVT) commonly occurs in the lower extremities but can occur in other sites including the head and neck, trunk, and upper extremities. The risk of nonleg deep venous thromboses (NLDVTs), predisposing factors, and the association between NLDVTs and pulmonary embolism (PE) or death are unclear. OBJECTIVE To describe the frequency, anatomical location, risk factors, management, and consequences of NLDVTs in a large cohort of medical-surgical critically ill adults. DESIGN, SETTING, AND PARTICIPANTS A nested prospective cohort study in the setting of secondary and tertiary care intensive care units (ICUs). The study population comprised 3746 patients, who were expected to remain in the ICU for at least 3 days and were enrolled in a randomized clinical trial of dalteparin vs standard heparin for thromboprophylaxis. MAIN OUTCOMES AND MEASURES The proportion of patients who had NLDVTs, the mean number per patient, and the anatomical location. We characterized NLDVTs as prevalent or incident (identified within 72 hours of ICU admission or thereafter) and whether they were catheter related or not. We used multivariable regression models to evaluate risk factors for NLDVT and to examine subsequent anticoagulant therapy, associated PE, and death. RESULTS Of 3746 trial patients, 84 (2.2%) developed 1 or more non-leg vein thromboses (superficial or deep, proximal or distal). Thromboses were more commonly incident (n = 75 [2.0%]) than prevalent (n = 9 [0.2%]) (P < .001) and more often deep (n = 67 [1.8%]) than superficial (n = 31 [0.8%]) (P < .001). Cancer was the only independent predictor of incident NLDVT (hazard ratio [HR], 2.22; 95% CI, 1.06-4.65). After adjusting for Acute Physiology and Chronic Health Evaluation (APACHE) II scores, personal or family history of venous thromboembolism, body mass index, vasopressor use, type of thromboprophylaxis, and presence of leg DVT, NLDVTs were associated with an increased risk of PE (HR, 11.83; 95% CI, 4.80-29.18). Nonleg DVTs were not associated with ICU mortality (HR, 1.09; 95% CI, 0.62-1.92) in a model adjusting for age, APACHE II, vasopressor use, mechanical ventilation, renal replacement therapy, and platelet count below 50 × 10(9)/L. CONCLUSIONS AND RELEVANCE Despite universal heparin thromboprophylaxis, nonleg thromboses are found in 2.2% of medical-surgical critically ill patients, primarily in deep veins and proximal veins. Patients who have a malignant condition may have a significantly higher risk of developing NLDVT, and patients with NLDVT, compared with those without, appeared to be at higher risk of PE but not higher risk of death. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00182143.
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Affiliation(s)
- Francois Lamontagne
- Centre de recherche Clinique Étienne-Le Bel, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Lauralyn McIntyre
- Department of Medicine (Division of Critical Care), The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Peter Dodek
- Center for Health Evaluation and Outcome Sciences and Department of Medicine, St Paul's Hospital and University of British Columbia, Vancouver, British Columbia, Canada
| | - Diane Heels-Ansdell
- Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada
| | - Maureen Meade
- Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada5Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Julia Pemberton
- Department of Surgery, McMaster University, Hamilton, Ontario, Canada
| | - Yoanna Skrobik
- Department of Medicine, Hôpital Maisonneuve Rosemont, Montreal, Quebec, Canada
| | - Ian Seppelt
- Department of Intensive Care Medicine, Nepean Hospital, University of Sydney, Sydney, Australia
| | - Nicholas E Vlahakis
- Department of Pulmonary and Critical Care, Mayo Clinic, Rochester, Minnesota
| | - John Muscedere
- Department of Critical Care, Queen's University, Kingston, Ontario, Canada
| | - Graham Reece
- Department of Intensive Care Medicine, Blacktown Hospital, Sydney, Australia
| | - Marlies Ostermann
- Department of Critical Care, Guys and St Thomas Hospital, London, England
| | - Soundrie Padayachee
- Department of Ultrasonic Angiology, Guys and St Thomas Hospital, London, England
| | - Jamal Alhashemi
- Department of Anesthesia and Critical Care, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Michael Walsh
- Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada5Department of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Bradley Lewis
- Department of Radiology, Mayo Clinic, Rochester, Minnesota
| | - David Schiff
- Department of Radiology, McMaster University, Hamilton, Ontario, Canada
| | - Alan Moody
- Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
| | - Nicole Zytaruk
- Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada
| | - Martine Leblanc
- Department of Medicine, Hôpital Maisonneuve Rosemont, Montreal, Quebec, Canada
| | - Deborah J Cook
- Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada5Department of Medicine, McMaster University, Hamilton, Ontario, Canada
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Warkentin TE, Sheppard JAI, Heels-Ansdell D, Marshall JC, McIntyre L, Rocha MG, Mehta S, Davies AR, Bersten AD, Crozier TM, Ernest D, Vlahakis NE, Hall RI, Wood GG, Poirier G, Crowther MA, Cook DJ. Heparin-Induced Thrombocytopenia in Medical Surgical Critical Illness. Chest 2013; 144:848-858. [DOI: 10.1378/chest.13-0057] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Das S, Singh S, Dowding JM, Oommen S, Kumar A, Sayle TXT, Saraf S, Patra CR, Vlahakis NE, Sayle DC, Self WT, Seal S. The induction of angiogenesis by cerium oxide nanoparticles through the modulation of oxygen in intracellular environments. Biomaterials 2012; 33:7746-55. [PMID: 22858004 PMCID: PMC4590782 DOI: 10.1016/j.biomaterials.2012.07.019] [Citation(s) in RCA: 208] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 07/06/2012] [Indexed: 01/14/2023]
Abstract
Angiogenesis is the formation of new blood vessels from existing blood vessels and is critical for many physiological and pathophysiological processes. In this study we have shown the unique property of cerium oxide nanoparticles (CNPs) to induce angiogenesis, observed using both in vitro and in vivo model systems. In particular, CNPs trigger angiogenesis by modulating the intracellular oxygen environment and stabilizing hypoxia inducing factor 1α endogenously. Furthermore, correlations between angiogenesis induction and CNPs physicochemical properties including: surface Ce(3+)/Ce(4+) ratio, surface charge, size, and shape were also explored. High surface area and increased Ce(3+)/Ce(4+) ratio make CNPs more catalytically active towards regulating intracellular oxygen, which in turn led to more robust induction of angiogenesis. Atomistic simulation was also used, in partnership with in vitro and in vivo experimentation, to reveal that the surface reactivity of CNPs and facile oxygen transport promotes pro-angiogenesis.
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Affiliation(s)
- Soumen Das
- Department of Mechanical, Materials and Aerospace Engineering, Advanced Materials Processing Analysis Center, University of Central Florida, Orlando, Florida
| | - Sanjay Singh
- Burnett School of Biomedical Science, University of Central Florida, Orlando, Florida
| | - Janet M. Dowding
- Burnett School of Biomedical Science, University of Central Florida, Orlando, Florida
| | - Saji Oommen
- Div. Pulmonary & Critical Care, Mayo Clinic, Rochester, Minnesota, USA
| | - Amit Kumar
- Department of Mechanical, Materials and Aerospace Engineering, Advanced Materials Processing Analysis Center, University of Central Florida, Orlando, Florida
| | - Thi X. T. Sayle
- Department of Engineering and Applied Science, Cranfield University, Defence Academy of the United Kingdom, Shrivenham SN6 8LA, United Kingdom
| | - Shashank Saraf
- Department of Mechanical, Materials and Aerospace Engineering, Advanced Materials Processing Analysis Center, University of Central Florida, Orlando, Florida
| | - Chitta Ranjan Patra
- Department of Biochemistry and Molecular Biology Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | | | - Dean C. Sayle
- Department of Engineering and Applied Science, Cranfield University, Defence Academy of the United Kingdom, Shrivenham SN6 8LA, United Kingdom
| | - William T. Self
- Burnett School of Biomedical Science, University of Central Florida, Orlando, Florida
| | - Sudipta Seal
- Department of Mechanical, Materials and Aerospace Engineering, Advanced Materials Processing Analysis Center, University of Central Florida, Orlando, Florida
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Affiliation(s)
- Shahnaz Ajani
- Department of Medicine, Mayo Clinic, Rochester, Minnesota, USA
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Cook D, Meade M, Guyatt G, Walter S, Heels-Ansdell D, Warkentin TE, Zytaruk N, Crowther M, Geerts W, Cooper DJ, Vallance S, Qushmaq I, Rocha M, Berwanger O, Vlahakis NE. Dalteparin versus unfractionated heparin in critically ill patients. N Engl J Med 2011; 364:1305-14. [PMID: 21417952 DOI: 10.1056/nejmoa1014475] [Citation(s) in RCA: 286] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND The effects of thromboprophylaxis with low-molecular-weight heparin, as compared with unfractionated heparin, on venous thromboembolism, bleeding, and other outcomes are uncertain in critically ill patients. METHODS In this multicenter trial, we tested the superiority of dalteparin over unfractionated heparin by randomly assigning 3764 patients to receive either subcutaneous dalteparin (at a dose of 5000 IU once daily) plus placebo once daily (for parallel-group twice-daily injections) or unfractionated heparin (at a dose of 5000 IU twice daily) while they were in the intensive care unit. The primary outcome, proximal leg deep-vein thrombosis, was diagnosed on compression ultrasonography performed within 2 days after admission, twice weekly, and as clinically indicated. Additional testing for venous thromboembolism was performed as clinically indicated. Data were analyzed according to the intention-to-treat principle. RESULTS There was no significant between-group difference in the rate of proximal leg deep-vein thrombosis, which occurred in 96 of 1873 patients (5.1%) receiving dalteparin versus 109 of 1873 patients (5.8%) receiving unfractionated heparin (hazard ratio in the dalteparin group, 0.92; 95% confidence interval [CI], 0.68 to 1.23; P=0.57). The proportion of patients with pulmonary emboli was significantly lower with dalteparin (24 patients, 1.3%) than with unfractionated heparin (43 patients, 2.3%) (hazard ratio, 0.51; 95% CI, 0.30 to 0.88; P=0.01). There was no significant between-group difference in the rates of major bleeding (hazard ratio, 1.00; 95% CI, 0.75 to 1.34; P=0.98) or death in the hospital (hazard ratio, 0.92; 95% CI, 0.80 to 1.05; P=0.21). In prespecified per-protocol analyses, the results were similar to those of the main analyses, but fewer patients receiving dalteparin had heparin-induced thrombocytopenia (hazard ratio, 0.27; 95% CI, 0.08 to 0.98; P=0.046). CONCLUSIONS Among critically ill patients, dalteparin was not superior to unfractionated heparin in decreasing the incidence of proximal deep-vein thrombosis. (Funded by the Canadian Institutes of Health Research and others; PROTECT ClinicalTrials.gov number, NCT00182143.).
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Oommen S, Gupta SK, Vlahakis NE. Vascular endothelial growth factor A (VEGF-A) induces endothelial and cancer cell migration through direct binding to integrin {alpha}9{beta}1: identification of a specific {alpha}9{beta}1 binding site. J Biol Chem 2010; 286:1083-92. [PMID: 21071450 DOI: 10.1074/jbc.m110.175158] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Integrin α9β1 mediates accelerated cell adhesion and migration through interactions with a number of diverse extracellular ligands. We have shown previously that it directly binds the vascular endothelial growth factors (VEGF) A, C, and D and contributes to VEGF-induced angiogenesis and lymphangiogenesis. Until now, the α9β1 binding site in VEGF has not been identified. Here, we report that the three-amino acid sequence, EYP, encoded by exon 3 of VEGF-A is essential for binding of VEGF to integrin α9β1 and induces adhesion and migration of endothelial and cancer cells. EYP is specific for α9β1 binding and neither requires nor activates VEGFR-2, the cognate receptor for VEGF-A. Following binding to EYP, integrin α9β1 transduces cell migration through direct activation of the integrin signaling intermediates Src and focal adhesion kinase. This interaction is biologically important because it mediates in vitro endothelial cell tube formation, wound healing, and cancer cell invasion. These novel findings identify EYP as a potential site for directed pharmacotherapy.
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Affiliation(s)
- Saji Oommen
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA
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Abstract
Integrins are transmembrane heterodimeric receptors responsible for transducing and modulating signals between the extracellular matrix and cytoskeleton, ultimately influencing cell functions such as adhesion and migration. Integrin alpha9beta1 is classified within a two member sub-family of integrins highlighted in part by its specialized role in cell migration. The importance of this role is demonstrated by its regulation of numerous biological functions including lymphatic valve morphogenesis, lymphangiogenesis, angiogenesis and hematopoietic homeostasis. Compared to other integrins the signaling mechanisms that transduce alpha9beta1-induced cell migration are not well described. We have recently shown that Src tyrosine kinase plays a key proximal role to control alpha9beta1 signaling. Specifically it activates inducible nitric oxide synthase (iNOS) and in turn nitric oxide (NO) production as a means to transduce cell migration. Furthermore, we have also described a role for FAK, Erk and Rac1 in alpha9beta1 signal transduction. Here we provide an over view of known integrin alpha9beta1 signaling pathways and highlight its roles in diverse biological conditions.
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Affiliation(s)
- Shiv K Gupta
- Thoracic Disease Research Unit, Division of Pulmonary & Critical Care Medicine, Mayo Clinic, Rochester, MN, USA
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10
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Seyama K, Mitani K, Kumasaka T, Gupta SK, Oommen S, Liu G, Ryu JH, Vlahakis NE. Lymphangioleiomyoma cells and lymphatic endothelial cells: expression of VEGFR-3 in lymphangioleiomyoma cell clusters. Am J Pathol 2010; 176:2051-2; author reply 2052-4. [PMID: 20203284 DOI: 10.2353/ajpath.2010.091239] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Issaka RB, Oommen S, Gupta SK, Liu G, Myers JL, Ryu JH, Vlahakis NE. Vascular endothelial growth factors C and D induces proliferation of lymphangioleiomyomatosis cells through autocrine crosstalk with endothelium. Am J Pathol 2009; 175:1410-20. [PMID: 19717640 DOI: 10.2353/ajpath.2009.080830] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Lymphangioleiomyomatosis (LAM) is a potentially fatal lung disease characterized by nodules of proliferative smooth muscle-like cells. The exact nature of these LAM cells and their proliferative stimuli are poorly characterized. Herein we report the novel findings that the lymphangiogenic vascular endothelial growth factors (VEGF) C and D induce LAM cell proliferation through activation of their cognate receptor VEGF-R3 and activation of the signaling intermediates Akt/mTOR/S6. Furthermore, we identify expression of the proteoglycan NG2, a marker of immature smooth muscle cells, as a characteristic of LAM cells both in vitro and in human lung tissue. VEGF-C-induced LAM cell proliferation was in part a result of autocrine stimulation that resulted from cross talk with lymphatic endothelial cells. Ultimately, these findings identify the lymphangiogenic VEGF proteins as pathogenic growth factors in LAM disease and at the same time provide a novel pharmacotherapeutic target for a lung disease that to date has no known effective treatment.
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Affiliation(s)
- Rachel B Issaka
- Thoracic Disease Research Unit, Division of Pulmonary, Mayo Clinic, Rochester, MN 55905, USA
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Tsigrelis C, Armstrong MD, Vlahakis NE, Batsis JA, Baddour LM. Infective endocarditis due to community-associated methicillin-resistant Staphylococcus aureus in injection drug users may be associated with Panton-Valentine leukocidin-negative strains. ACTA ACUST UNITED AC 2009; 39:299-302. [PMID: 17454892 DOI: 10.1080/00365540601003803] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) isolates that cause infective endocarditis in injection drug users (IDUs) are distinct from CA-MRSA strains that cause endocardial infection as a complication of skin and soft tissue infections. We present a case of CA-MRSA infective endocarditis, review pertinent cases previously published, and describe the molecular characteristics of strains from IDUs and patients with skin and soft tissue infections.
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Gupta SK, Vlahakis NE. Integrin alpha9beta1 mediates enhanced cell migration through nitric oxide synthase activity regulated by Src tyrosine kinase. J Cell Sci 2009; 122:2043-54. [PMID: 19470583 PMCID: PMC2723157 DOI: 10.1242/jcs.041632] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/04/2009] [Indexed: 12/31/2022] Open
Abstract
Integrins are important mediators of cell adhesion and migration, which in turn are essential for diverse biological functions, including wound healing and cancer metastasis. The integrin alpha9beta1 is expressed on numerous mammalian tissues and can mediate accelerated cell migration. As the molecular signaling mechanisms that transduce this effect are poorly defined, we investigated the pathways by which activated integrin alpha9beta1 signals migration. We found for the first time that specific ligation of integrin alpha9beta1 rapidly activates Src tyrosine kinase, with concomitant tyrosine phosphorylation of p130Cas and activation of Rac-1. Furthermore, activation of integrin alpha9beta1 also enhanced NO production through activation of inducible nitric oxide synthase (iNOS). Inhibition of Src tyrosine kinase or NOS decreased integrin-alpha9beta1-dependent cell migration. Src appeared to function most proximal in the signaling cascade, in a FAK-independent manner to facilitate iNOS activation and NO-dependent cell migration. The cytoplasmic domain of integrin alpha9 was crucial for integrin-alpha9beta1-induced Src activation, subsequent signaling events and cell migration. When taken together, our results describe a novel and unique mechanism of coordinated interactions of the integrin alpha9 cytoplasmic domain, Src tyrosine kinase and iNOS to transduce integrin-alpha9beta1-mediated cell migration.
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Affiliation(s)
- Shiv K Gupta
- Thoracic Disease Research Unit, Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, MN 55905, USA
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Vlahakis NE. Caveolin: Another reason why lipid membranes play an important role in ventilator-induced lung injury*. Crit Care Med 2009; 37:1819-20. [DOI: 10.1097/ccm.0b013e3181a1a028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Gupta SK, Vlahakis NE. Dispensable role of focal adhesion kinase in integrin alpha9beta1 mediated cell migration. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1029.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Shiv Kumar Gupta
- Pulmonary & Critical careMayo Clinic College of MedicineRochesterMN
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Vlahakis NE, Young BA, Atakilit A, Hawkridge AE, Issaka RB, Boudreau N, Sheppard D. Integrin alpha9beta1 directly binds to vascular endothelial growth factor (VEGF)-A and contributes to VEGF-A-induced angiogenesis. J Biol Chem 2007; 282:15187-96. [PMID: 17363377 DOI: 10.1074/jbc.m609323200] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vascular endothelial growth factor A (VEGF-A) is a potent inducer of angiogenesis. We now show that VEGF-A-induced adhesion and migration of human endothelial cells are dependent on the integrin alpha9beta1 and that VEGF-A is a direct ligand for this integrin. Adhesion and migration of these cells on the 165 and 121 isoforms of VEGF-A depend on cooperative input from alpha9beta1 and the cognate receptor for VEGF-A, VEGF receptor 2 (VEGF-R2). Unlike alpha3beta1or alphavbeta3 integrins, alpha9beta1 was also found to bind the 121 isoform of VEGF-A. This interaction appears to be biologically significant, because alpha9beta1-blocking antibody dramatically and specifically inhibited angiogenesis induced by VEGF-A165 or -121. Together with our previous findings that alpha9beta1 directly binds to VEGF-C and -D and contributes to lymphangiogenesis, these results identify the integrin alpha9beta1 as a potential pharmacotherapeutic target for inhibition of pathogenic angiogenesis and lymphangiogenesis.
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Affiliation(s)
- Nicholas E Vlahakis
- Lung Biology Center, University of California, San Francisco, California 94143-2922, USA.
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17
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Abstract
BACKGROUND Hereditary angioedema (HAE) is an infrequent disorder characterized by abnormalities in the levels and/or function of complement C1 esterase inhibitor. Clinical manifestations of HAE are due to recurrent episodic swelling of the subcutaneous or submucosal tissue. When swelling involves the gastrointestinal mucosa, patients may present with nausea, vomiting, diarrhea, and severe abdominal pain. However, HAE is almost never suspected as a potential cause of acute pancreatitis. OBJECTIVE To describe a patient with HAE-associated pancreatitis requiring intensive medical care that responded favorably to conservative and supportive measures. METHODS Various tests were performed, including abdominal imaging, measurement of pancreatic enzymes levels, liver function tests, measurement of complement levels, and endoscopic retrograde cholangiopancreatography. RESULTS The results of these tests confirmed the diagnosis of HAE-associated acute pancreatitis. No other obvious origin, such as gallstones or alcohol use, was identified. CONCLUSION This case illustrates the need for a high clinical suspicion of acute pancreatitis when caring for patients with HAE who present with abdominal symptoms. There continues to be an urgent need for better and additional therapeutic options for HAE patients, including those to prevent and abort ongoing attacks.
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Affiliation(s)
- Damir Matesic
- Department of Pulmonary and Critical Care Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota 55901, USA
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Gupta SK, Vlahakis NE. Integrin alpha9beta1 promotes cell migration via Src kinase mediated nitric oxide synthesis. FASEB J 2007. [DOI: 10.1096/fasebj.21.6.lb5-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Shiv Kumar Gupta
- Thoracic Disease Research UnitMayo Clinic College of Medicine200‐First Street SWRochesterMN55905
| | - Nicholas E Vlahakis
- Thoracic Disease Research UnitMayo Clinic College of Medicine200‐First Street SWRochesterMN55905
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Rana R, Vlahakis NE, Daniels CE, Jaffe AS, Klee GG, Hubmayr RD, Gajic O. B-type natriuretic peptide in the assessment of acute lung injury and cardiogenic pulmonary edema*. Crit Care Med 2006; 34:1941-6. [PMID: 16691132 DOI: 10.1097/01.ccm.0000220492.15645.47] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE The role of plasma B-type natriuretic peptide (BNP) in critically ill patients with acute pulmonary edema is controversial. We postulated that a low BNP level would exclude cardiac dysfunction as the principal cause of pulmonary edema and therefore help in the diagnosis of acute lung injury. DESIGN A retrospective derivation cohort was followed by a prospective validation cohort of consecutive patients with acute pulmonary edema admitted to three intensive care units. BNP was measured within 24 hrs from onset. Critical care experts blinded to BNP results integrated clinical data with the course of disease and response to therapy and served as the reference standard. SETTING Three intensive care units at the tertiary center. PATIENTS Consecutive critically ill patients with acute pulmonary edema. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS In a derivation cohort of 84 patients, a BNP threshold of <or=250 pg/mL had a specificity of 87% and sensitivity of 48% for the diagnosis of acute lung injury. High specificity of BNP (90%, likelihood ratio of 3.9) was confirmed in a validation cohort of 120 consecutive patients, 52 (43%) of whom had acute lung injury. Notably, 32% of patients with acute lung injury had concomitant cardiac dysfunction. The median time from the onset of pulmonary edema to BNP testing was 3 hrs. The accuracy of BNP (area under receiver operator curve, 0.71) was comparable with pulmonary artery occlusion pressure (area under receiver operator curve, 0.66) and superior to ejection fraction (area under receiver operator curve, 0.60) in subgroups of patients in whom these tests were performed. The accuracy of BNP improved when patients with renal insufficiency were excluded (area under receiver operator curve, 0.82). CONCLUSION When measured early after the onset of acute pulmonary edema, a BNP level of <250 pg/mL supports the diagnosis of acute lung injury. The high rate of cardiac and renal dysfunction in critically ill patients limits the discriminative role of BNP. No level of BNP could completely exclude cardiac dysfunction.
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Affiliation(s)
- Rimki Rana
- Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, Mayo Clinic College of Medicine, Rochester, MN, USA
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Abstract
The clinical and experimental literature has unequivocally established that mechanical ventilation with large tidal volumes is injurious to the lung. However, uncertainty about the micromechanics of injured lungs and the numerous degrees of freedom in ventilator settings leave many unanswered questions about the biophysical determinants of lung injury. In this review we focus on experimental evidence for lung cells as injury targets and the relevance of these studies for human ventilator-associated lung injury. In vitro, the stress-induced mechanical interactions between matrix and adherent cells are important for cellular remodeling as a means for preventing compromise of cell structure and ultimately cell injury or death. In vivo, these same principles apply. Large tidal volume mechanical ventilation results in physical breaks in alveolar epithelial and endothelial plasma membrane integrity and subsequent triggering of proinflammatory signaling cascades resulting in the cytokine milieu and pathologic and physiologic findings of ventilator-associated lung injury. Importantly, though, alveolar cells possess cellular repair and remodeling mechanisms that in addition to protecting the stressed cell provide potential molecular targets for the prevention and treatment of ventilator-associated lung injury in the future.
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Affiliation(s)
- Nicholas E Vlahakis
- Thoracic Diseases Research Unit, Division of Pulmonary and Critical care Medicine, Department of Medicine, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
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24
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Vlahakis NE, Young BA, Atakilit A, Sheppard D. The lymphangiogenic vascular endothelial growth factors VEGF-C and -D are ligands for the integrin alpha9beta1. J Biol Chem 2004; 280:4544-52. [PMID: 15590642 PMCID: PMC1368959 DOI: 10.1074/jbc.m412816200] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mice homozygous for a null mutation of the integrin alpha9 subunit die 6-12 days after birth from bilateral chylothoraces suggesting an underlying defect in lymphatic development. However, until now the mechanisms by which the integrin alpha9beta1 modulates lymphangiogenesis have not been described. In this study we show that adhesion to and migration on the lymphangiogenic vascular endothelial growth factors (VEGF-C and -D) are alpha9beta1-dependent. Mouse embryonic fibroblasts and human colon carcinoma cells (SW-480) transfected to express alpha9beta1 adhered and/or migrated on both growth factors in a concentration-dependent fashion, and both adhesion and migration were abrogated by anti-alpha9beta1 function-blocking antibody. In SW-480 cells, which lack cognate receptors for VEGF-C and -D, both growth factors induced alpha9beta1-dependent Erk and paxillin phosphorylation. Human microvascular endothelial cells, which express both alpha9beta1 and VEGF-R3, also adhered to and migrated on both growth factors, and both responses were blocked by anti-alpha9beta1 antibody. Furthermore, in a solid phase binding assay recombinant VEGF-C and -D bound to purified alpha9beta1 integrin in a dose- and cation-dependent fashion showing that VEGF-C and VEGF-D are ligands for the integrin alpha9beta1. The interaction between alpha9beta1 and VEGF-C and/or -D may begin to explain the abnormal lymphatic phenotype of the alpha9 knock-out mice.
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Affiliation(s)
- Nicholas E. Vlahakis
- From the Lung Biology Center, University of California San Francisco, Box 2922, San Francisco, CA, 94143-2922
- Thoracic Disease Research Unit, Mayo Clinic College of Medicine, 200 First St SW, Rochester, MN 55905
| | - Bradford A. Young
- From the Lung Biology Center, University of California San Francisco, Box 2922, San Francisco, CA, 94143-2922
| | - Amha Atakilit
- From the Lung Biology Center, University of California San Francisco, Box 2922, San Francisco, CA, 94143-2922
| | - Dean Sheppard
- From the Lung Biology Center, University of California San Francisco, Box 2922, San Francisco, CA, 94143-2922
- § To whom correspondence should be addressed: Lung Biology Center, University of California, San Francisco, Box 2922, San Francisco, CA 94143-2922 Ph: 415-514-4270 Fax: 415-514-4278
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Abstract
Sirolimus is an immunosuppressive medication used in transplant recipients. To our knowledge, we describe the third reported case of alveolar hemorrhage in association with sirolimus. Fever, dyspnea, hemoptysis, and lung infiltrates resolved rapidly with cessation of sirolimus therapy both initially and after reinstitution of the drug. Unlike previous reports, our patient had no evidence of lymphocytic alveolitis but rather marked macrophage hemosiderosis, suggesting that sirolimus pulmonary toxicity may manifest through 2 separate mechanisms. Our case highlights an uncommon but potentially lethal manifestation of sirolimus pulmonary toxicity.
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Affiliation(s)
- Nicholas E Vlahakis
- Division of Pulmonary and Critical Care Medicine and Internal Medicine, Mayo Clinic College of Medicine, Rochester, Minn 55905, USA.
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26
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Abstract
Despite the common occurrence of musculoskeletal complaints in patients with infective endocarditis, infectious osteoarticular complications are diagnosed infrequently. Moreover, although enterococcal infection is the third most common cause of infective endocarditis, infectious osteoarticular complications are rare. We report a case of disk space infection in a patient with enterococcal endocarditis. Blood cultures and an L3-4 aspirate grew Enterococcus faecalis, and transthoracic echocardiography revealed a large vegetation on the posterior mitral valve leaflet. The osteoarticular infection resolved with antimicrobial treatment, but worsening heart failure necessitated valve replacement surgery. The patient had an uneventful recovery with no evidence of recurrence or complications. A review of the medical literature from 1966 through 1998 identified 13 additional cases, only 8 of which provided clinical and treatment data. We present the clinical and laboratory findings reported in these cases, along with data from our patient. This report highlights the rare occurrence of osteoarticular infection in the setting of enterococcal endocarditis and emphasizes early recognition and treatment.
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Affiliation(s)
- Nicholas E Vlahakis
- Division of Pulmonary and Critical Care Medicine and Internal Medicine, Mayo Clinic, Rochester, Minn 55905, USA.
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Abstract
The purpose of this review is to highlight areas in alveolar cell biology in which our understanding of the effects of mechanical stress have been advanced in the last year, focusing on intracellular signal transduction pathways, the surfactant system, and cell injury and repair. Mechano-transduction pathways are only now beginning to be elucidated in alveolar cells. The importance of the mitogen-activated protein kinase, G protein, and growth factor systems is emphasized. The research conducted in the last year has also stressed the importance of alveolar cell cross-talk, with surfactant exocytosis being facilitated through parathyroid hormone-related peptide and leptin and calcium in interstitial fibroblasts and endothelial cells, respectively. Finally, the importance of deformation-induced plasma membrane breaks is emphasized. Alveolar cells were found to exocytose intracellular lipid vesicles to the plasma membrane-not only to prevent cell breaks but also to reseal cell breaks. This dynamic process was a stronger determinant of cell breaks than the prestress properties of the cytoskeleton. All of these exciting findings provide further potential treatment targets for ventilator-induced lung injury.
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Affiliation(s)
- Nicholas E Vlahakis
- University of California San Francisco, Lung Biology Center, 1001 Potrero Avenue, San Francisco, 94110, USA.
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28
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Affiliation(s)
- Nicholas E Vlahakis
- Department of Internal Medicine, Stabile Building Room 8-62, Mayo Clinic and Foundation, 200 First Street SW, Rochester, MN 55905, USA.
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Vlahakis NE, Schroeder MA, Pagano RE, Hubmayr RD. Role of deformation-induced lipid trafficking in the prevention of plasma membrane stress failure. Am J Respir Crit Care Med 2002; 166:1282-9. [PMID: 12403699 DOI: 10.1164/rccm.200203-207oc] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Cells experience plasma membrane stress failure when the matrix to which they adhere undergoes large deformations. In the lung, such a mechanism might explain mechanical ventilation-associated cell injury. We have previously shown that in alveolar epithelial cells, deformation induces lipid trafficking to the plasma membrane, thereby accommodating the required increase in the cell surface area. We now show that cell wounding is strain amplitude and rate dependent and that under conditions of impaired exocytosis strain-induced cell wounding is significantly increased. In addition, the susceptibility of cells to mechanical injury was not correlated with changes in cell stiffness. Using a dual-labeling technique, we differentiated between cell populations that were reversibly and irreversibly injured and showed that interventions that impair deformation-induced lipid trafficking also reduce the likelihood of plasma membrane resealing. Our findings suggest that cell plasticity and remodeling responses such as deformation-induced lipid trafficking are more important for cytoprotection from strain injury than are the innate mechanical properties of the cell. We also conclude that in deformation experiments, tests of cell membrane integrity cannot be interpreted as tests of cell viability because an intact plasma membrane after deformation does not mean that no injury had occurred.
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Affiliation(s)
- Nicholas E Vlahakis
- Pulmonary and Critical Care Medicine Division, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
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30
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Abstract
Allergic bronchopulmonary aspergillosis (ABPA) is an underdiagnosed pulmonary disorder in asthmatic patients and patients with cystic fibrosis. Its clinical and diagnostic manifestations arise from an allergic response to multiple antigens expressed by fungi, most commonly Aspergillus fumigatus, colonizing the bronchial mucus. The clinical course is one of recurrent exacerbations characterized by chest infiltrates evident on chest x-ray films and associated with cough, wheeze, and sputum production that usually respond to oral corticosteroid treatment. Specific immunologic and radiologic markers of disease include elevation of the total serum IgE levels, presence of aspergillus IgE antibodies, and the occurrence of central bronchiectasis. Long-term treatment with corticosteroids is often required for effective management. The adverse effects of chronic corticosteroid use have led to attempts at treatment with antifungal agents such as itraconazole. Itraconazole has been reported anecdotally to be effective, and evidence for its effectiveness in randomized trials is still accruing. Consideration should be given to its use as a corticosteroid-sparing agent or for treatment of patients in whom corticosteroid response is poor. The natural history and prognosis of ABPA are not well characterized but may be complicated by progression to bronchiectasis and pulmonary fibrosis. If ABPA is diagnosed and treated before the development of bronchiectasis and fibrosis, these complications may be prevented.
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Affiliation(s)
- N E Vlahakis
- Division of Pulmonary and Critical Care Medicine, Mayo Clinic, Rochester, Minn 55905, USA
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31
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Stroetz RW, Vlahakis NE, Walters BJ, Schroeder MA, Hubmayr RD. Validation of a new live cell strain system: characterization of plasma membrane stress failure. J Appl Physiol (1985) 2001; 90:2361-70. [PMID: 11356803 DOI: 10.1152/jappl.2001.90.6.2361] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Motivated by our interest in lung deformation injury, we report on the validation of a new live cell strain system. We showed that the system maintains a cell culture environment equivalent to that provided by conventional incubators and that its strain ouput was uniform and reproducible. With this system, we defined cell deformation dose (i.e., membrane strain amplitude)-cell injury response relationships in alveolar epithelial cultures and studied the effects of temperature on them. Deformation injury occurred in the form of reversible, nonlethal plasma membrane stress failure events and was quantified as the fraction of cells with uptake and retention of fluorescein-labeled dextran (FITC-Dx). The undeformed control population showed virtually no FITC-Dx uptake at any temperature, which was also true for cells strained by 3%. However, when the membrane strain was increased to 18%, ∼5% of cells experienced deformation injury at a temperature of 37°C. Moreover, at that strain, a reduction in temperature to 4°C resulted in a threefold increase in the number of cells with plasma membrane breaks (from 4.8 to 15.9%; P < 0.05). Cooling of cells to 4°C also lowered the strain threshold at which deformation injury was first seen. That is, at a 9% substratum strain, cooling to 4°C resulted in a 10-fold increase in the number of cells with FITC-Dx staining (0.7 vs. 7.5%, P < 0.05). At that temperature, A549 cells offered a 50% higher resistance to shape change (magnetic twisting cytometry measurements) than at 37°C. We conclude that the strain-injury threshold of A549 cells is reduced at low temperatures, and we consider temperature effects on plasma-membrane fluidity, cytoskeletal stiffness, and lipid trafficking as responsible mechanisms.
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Affiliation(s)
- R W Stroetz
- Thoracic Diseases Research Unit, Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
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32
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Abstract
Mechanical ventilation with a high tidal volume results in lung injury that is characterized by blebbing and breaks both between and through alveolar epithelial cells. We developed an in vitro model to simulate ventilator-induced deformation of the alveolar basement membrane and to investigate, in a direct manner, epithelial cell responses to deforming forces. Taking advantage of the novel fluorescent properties of BODIPY lipids and the fluorescent dye FM1-43, we have shown that mechanical deformation of alveolar epithelial cells results in lipid transport to the plasma membrane. Deformation-induced lipid trafficking (DILT) was a vesicular process, rapid in onset, and was associated with a large increase in cell surface area. DILT could be demonstrated in all cells; however, only a small percentage of cells developed plasma membrane breaks that were reversible and nonlethal. Therefore, DILT was not only involved in site-directed wound repair but might also have served as a cytoprotective mechanism against plasma membrane stress failure. This study suggests that DILT is a regulatory mechanism for membrane trafficking in alveolar epithelia and provides a novel biological framework within which to consider alveolar deformation injury and repair.
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Affiliation(s)
- N E Vlahakis
- Thoracic Diseases Research Unit, Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA. vlahakis@
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Abstract
In this review, we examine the hypothesis that plasma membrane stress failure is a central event in the pathophysiology of injury from alveolar overdistension. This hypothesis leads us to consider alveolar micromechanics and specifically the mechanical interactions between lung matrix and alveolar epithelial cell cytoskeleton and plasma membrane. We then explore events that are central to the regulation of plasma membrane tension and detail the lipid-trafficking responses of in vitro deformed and/or injured cells. We conclude with a reference to upregulation of stress-responsive genes after membrane injury and resealing.
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Affiliation(s)
- N E Vlahakis
- Thoracic Diseases Research Unit, Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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Abstract
Mechanical ventilation can injure the lung, causing edema and alveolar inflammation. Interleukin-8 (IL-8) plays an important role in this inflammatory response. We postulated that cyclic cell stretch upregulates the production and release of IL-8 by human alveolar epithelium in the absence of structural cell damage or paracrine stimulation. To test this hypothesis, alveolar epithelial cells (A549 cells) were cultured on a deformable silicoelastic membrane. When stretched by 30% for up to 48 h, the cells released 49 +/- 34% more IL-8 (P < 0.001) than static controls. Smaller deformations (20% stretch) produced no consistent increase in IL-8. Stretch of 4 h duration increased IL-8 gene transcription fourfold above baseline. Stretch had no effect on cell proliferation, cell viability as assessed by (51)Cr release assay, or the release of granulocyte-macrophage colony-stimulating factor and tumor necrosis factor-alpha. We conclude that deformation per se can trigger inflammatory signaling and that alveolar epithelial cells may be active participants in the alveolitis associated with ventilator-induced lung injury.
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Affiliation(s)
- N E Vlahakis
- Thoracic Diseases Research Unit, Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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Proctor DN, Halliwill JR, Shen PH, Vlahakis NE, Joyner MJ. Peak calf blood flow estimates are higher with Dohn than with Whitney plethysmograph. J Appl Physiol (1985) 1996; 81:1418-22. [PMID: 8889782 DOI: 10.1152/jappl.1996.81.3.1418] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Estimates of calf blood flow with venous occlusion plethysmography vary widely between studies, perhaps due to the use of different plethysmographs. Consequently, we compared calf blood flow estimates at rest and during reactive hyperemia in eight healthy subjects (four men and four women) with two commonly used plethysmographs: the mercury-in-silastic (Whitney) strain gauge and Dohn air-filled cuff. To minimize technical variability, flow estimates were compared with a Whitney gauge and a Dohn cuff on opposite calves before and after 10 min of bilateral femoral arterial occlusion. To account for any differences between limbs, a second trial was conducted in which the plethysmographs were switched. Resting flows did not differ between the plethysmographs (P = 0.096), but a trend toward lower values with the Whitney was apparent. Peak flows averaged 37% lower with the Whitney (27.8 +/- 2.8 ml.dl-1.min-1) than with the Dohn plethysmograph (44.4 +/- 2.8 ml.dl-1.min-1; P < 0.05). Peak flow expressed as a multiple above baseline was also lower with the Whitney (10-fold) than with the Dohn plethysmograph (14.5-fold; P = 0.02). Across all flows at rest and during reactive hyperemia, estimates were highly correlated between the plethysmographs in all subjects (r2 = 0.96-0.99). However, the mean slope for the Whitney-Dohn relationship was only 60 +/- 2%, indicating that over a wide range of flows the Whitney gauge estimate was 40% lower than that for the Dohn cuff. These results demonstrate that the same qualitative results can be obtained with either plethysmograph but that absolute flow values will generally be lower with Whitney gauges.
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Affiliation(s)
- D N Proctor
- Department of Anesthesiology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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Vlahakis NE, Litin SC. 70-year-old man with abdominal pain amd weight loss. Mayo Clin Proc 1996; 71:601-4. [PMID: 8642892 DOI: 10.4065/71.6.601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- N E Vlahakis
- Internal Medicine, Mayo Graduate School of Medicine, Mayo Clinic Rochester, Minnesota, USA
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