Cysteine/Cystine Redox State in Lung Injury and Fibrosis Público

Abstract

Acute lung injury (ALI) and idiopathic pulmonary fibrosis (IPF) are lung diseases with significant morbidity and mortality. Glutathione (GSH) is oxidized in both ALI and IPF, but little is known about the regulation of the precursor cysteine (Cys) pool. The studies described in this dissertation establish that the redox state (Eh) of the Cys/cystine (CySS) couple is a biomarker of oxidative stress in experimental ALI and IPF, and varies independently from the redox state of the GSH/glutathione disulfide (GSSG) couple during inflammation, injury, and fibrosis in the lung. In the first study, we identified that plasma Eh Cys/CySS is highly oxidized relative to Eh GSH/GSSG during the acute lung injury induced by endotoxin. In vitro, oxidized Eh Cys/CySS increased adhesion of leukocytes to the pulmonary endothelium, suggesting that early oxidation of Cys/CySS may potentiate neutrophil influx into the lungs. To further understand the relationship between Eh Cys/CySS and inflammation, we modified Eh Cys/CySS and determined levels of the pro-inflammatory cytokine, interleukin (IL) -1. Results showed that oxidized Eh Cys/CySS increased IL-1 levels in monocytes, and that dietary treatment to protect against plasma Eh Cys/CySS oxidation decreased plasma and lung levels of IL-1 in endotoxin-challenged mice. Analysis of Eh Cys/CySS and IL-1 in human plasma revealed a significant positive association between oxidized Eh Cys/CySS and IL-1, independent of age, gender, and BMI. Additionally, we examined plasma Cys and GSH redox states during the resolution of inflammation in response to exogenously infused bone marrow derived mesenchymal stem cells (BMDMSC). Results showed a sequential preservation of systemic Cys and GSH pools in response to BMDMSC infusion. Because lung injury is an upstream event in fibrosis, we assessed the dynamics of Cys redox state in a model of lung fibrosis. Results showed oxidation of plasma EhCys/CySS in the absence of changes to Eh GSH/GSSG. Furthermore, oxidation of EhCys/CySS in the lung lining fluid was associated with the induction of pro-fibrotic markers in the lung, suggesting that oxidation of Cys/CySS during lung injury may contribute to fibrosis.

Table of Contents

CHAPTER I INTRODUCTION Page 1. LOW-MOLECULAR WEIGHT THIOL/DISULFIDE REDOX SYSTEMS .........2 1.1. Cysteine ..........................................................................................................2 1.2. Cysteine/Cystine Redox State ........................................................................4 1.3. Glutathione ...................................................................................................10 2. ALVEOLAR EPITHELIUM, ENDOTHELIUM, INTERSTITIUM AND PULMONARY IMMUNE SYSTEM .............................................................. 14 2.1. Alveolar Epithelium .....................................................................................14 2.2. Pulmonary Endothelium ...............................................................................16 2.3. Pulmonary Interstitium and Fibroblasts .......................................................17 2.4. Pulmonary Immune System .........................................................................18 3. ACUTE LUNG INJURY (ALI) ..............................................................................20 3.1. Historical Perspective ..................................................................................20 3.2. Epidemiology and Risk Factors ....................................................................21 3.3. Pathogenesis of ALI ....................................................................................23 3.4. Animal models of ALI ..................................................................................25 3.5. Bone Marrow-Derived Mesenchymal Stem Cells as a Therapy in ALI ......28 4. IDIOPATHIC PULMONARY FIBROSIS (IPF) ...................................................32 4.1. Historical Perspective ..................................................................................32 4.2. Epidemiology and Risk Factors ...................................................................34 4.3. Pathogenesis of IPF .....................................................................................38 4.4. Animal models of IPF ..................................................................................42

5.OXIDATIVE STRESS AND GSH DEFICIENCY IN ALI and IPF ....................... 46 5.1. GSH and Cys as Determinants of Cytokine and Growth Factor Production ............................................................................46 5.2 Oxidative Stress and GSH deficiency in ALI ...............................................49 5.2.1. Oxidative Stress in ALI .....................................................................49 5.2.2. GSH Deficiency in ALI .....................................................................51 5.3. Thiol Antioxidants in Experimental and Clinical ALI ................................58 5.4. Oxidative Stress and GSH deficiency in IPF ..............................................65 5.4.1. Oxidative Stress in IPF ......................................................................65 5.4.2. GSH Deficiency in IPF ......................................................................67 5.5. Thiol Antioxidants in Experimental and Clinical IPF .................................71 6. ROLE OF CYS/CYSS REDOX STATE IN ALI AND IPF ..................................... 75 7. STATEMENT OF PURPOSE ...................................................................................... 77 CHAPTER II SEQUENTIAL OXIDATION OF PLASMA CYSTEINE AND GLUTATHIONE REDOX STATES IN ENDOTOXIN-INDUCED LUNG INJURY 1. ABSTRACT ........................................................................................................81 2. INTRODUCTION ...............................................................................................82 3. MATERIALS AND METHODS ..........................................................................84 4. RESULTS ............................................................................................................89 4.1. Cytokine expression and Immunohistochemistry ...........................................89 4.2. Effect of endotoxin on food intake and body weight .....................................94 4.3. Endotoxin-induced oxidation of plasma Cys/CySS redox state correlates with the initiation of lung injury .....................................................96 4.4. Oxidation of plasma GSH/GSSG redox state followed oxidation

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School	Laney Graduate School
Department	Biological and Biomedical Sciences
Degree	PhD
Submission	Dissertation
Language	English
Research Field	Health Sciences, Nutrition Health Sciences, Pathology Health Sciences, Immunology
Palavra-chave	oxidative stress glutathione acute lung injury inflammation diet idiopathic pulmonary fibrosis
Committee Chair / Thesis Advisor	Jones, Dean P, Emory University Rojas, Mauricio, Emory University
Committee Members	Brown, Lou Ann, Emory University Mora, Ana Lucia, Emory University Ziegler, Thomas R, Emory University Abramson, Jerome, Emory University

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