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A Thesis Submitted for the Degree of PhD at the University of Warwick Permanent WRAP URL: http://wrap.warwick.ac.uk/80026 Copyright and reuse: This thesis is made available online and is protected by original copyright. Please scroll down to view the document itself. Please refer to the repository record for this item for information to help you to cite it. Our policy information is available from the repository home page. For more information, please contact the WRAP Team at: [email protected] warwick.ac.uk/lib-publications Dicarbonyl stress and dysfunction of the glyoxalase system in periodontal diseases By Amal Adnan Ashour A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Medicine Warwick Medical School, University of Warwick March 2016 1 Table of contents Table of contents .......................................................................................................... 2 Table of Figures ......................................................................................................... 12 List of Tables.............................................................................................................. 16 Acknowledgement...................................................................................................... 20 Dedication .................................................................................................................. 22 Declaration ................................................................................................................. 23 Abstract ...................................................................................................................... 24 Abbreviations ............................................................................................................. 26 1. Introduction .................................................................................................... 31 1.1 Periodontium and periodontal diseases .......................................................... 31 1.1.1 Components of periodontium ......................................................................... 32 1.1.1.1 Gingiva ........................................................................................................... 32 1.1.1.2 Periodontal ligament (PDL) ........................................................................... 34 1.1.1.3 Cementum ...................................................................................................... 38 1.1.1.4 Alveolar bone ................................................................................................. 38 1.1.2 Periodontal diseases ....................................................................................... 39 1.1.2.1 Gingivitis ........................................................................................................ 39 1.1.2.2 Periodontitis ................................................................................................... 41 1.1.2.3 Pathology of periodontitis .............................................................................. 42 1.1.3 Risk factors for periodontitis .......................................................................... 45 1.1.3.1 Non-modifiable risk factors ........................................................................... 45 1.1.3.2 Modifiable risk factors ................................................................................... 47 1.2 Diabetes .......................................................................................................... 48 1.2.1 Types of diabetes............................................................................................ 48 1.2.1.1 Type 1 diabetes mellitus................................................................................. 48 1.2.1.2 Type 2 diabetes mellitus................................................................................. 51 1.2.1.3 Other types of diabetes ................................................................................... 54 1.2.1.4 Gestational diabetes mellitus (GDM)............................................................. 54 1.2.1.5 Other diabetes complications ......................................................................... 55 1.3 Periodontitis in diabetes ................................................................................. 55 1.3.1 Association of diabetes with periodontitis ..................................................... 55 2 1.3.2 Factors contributing to development of periodontitis in patients with diabetes ........................................................................................................................ 56 1.3.2.1 Lipopolysaccharide (LPS), infection, pro-inflammatory mediators and polymorphnuclear neutrophils ....................................................................... 56 1.3.2.2 Collagen metabolism ...................................................................................... 57 1.3.2.3 Wound healing ............................................................................................... 58 1.3.2.4 Oxidative Stress ............................................................................................. 59 1.3.3 Periodontitis and insulin resistance ................................................................ 60 1.3.4 Other oral manifestations of diabetes mellitus ............................................... 60 1.3.5 Pathogenic mechanisms linking diabetes and periodontitis ........................... 60 1.3.6 Inflammation .................................................................................................. 62 1.3.7 Biochemical mechanisms of periodontitis ..................................................... 63 1.3.7.1 Inflamatory signaling ..................................................................................... 63 1.4 Glycation ........................................................................................................ 66 1.4.1 Definition of glycation ................................................................................... 66 1.4.2 Historical background of glycation ................................................................ 67 1.4.3 Molecular structures of advanced glycation end-products ............................. 72 1.4.4 Biochemical and physiological effects of protein glycation .......................... 72 1.4.5 Receptor of advanced glycation end products (RAGE) ................................. 74 1.4.6 Evidance for RAGE regulation of Glo1 ......................................................... 78 1.4.7 Evidence of involvement of glycation and RAGE in periodontal disease ..... 79 1.5 The Glyoxalase system .................................................................................. 80 1.5.1 Enzymatic defence against glycation ............................................................. 80 1.5.1.1 Glyoxalase system - definition and function .................................................. 81 1.5.1.2 Histological development of glyoxalase system ............................................ 82 1.5.1.3 Glyoxalase 1 - molecular properties, genetics and human polymorphism .... 84 1.5.1.4 Glyoxalase 2 - molecular properties, genetics and human polymorphism .... 88 1.5.1.5 D-Lactate ........................................................................................................ 89 1.5.1.6 S-D-Lactoylglutathione .................................................................................. 90 1.5.1.7 Non-glyoxalase detoxification of MG ........................................................... 91 1.5.2 Regulation of Glo1 gene expression .............................................................. 92 1.5.3 Copy number variation of GLO1 gene .......................................................... 94 1.5.4 Glyoxalase 1 - a critical role in enzymatic defence against glycation ........... 94 1.5.5 Glyoxalase inhibitors ..................................................................................... 95 3 1.6 Dicarbonyls .................................................................................................... 96 1.6.1 Dicarbonyl stress ............................................................................................ 96 1.6.2 Dicarbonyl glycation and protein damage ..................................................... 96 1.6.2.1 Physiological dicarbonyl and historical aspects ............................................. 96 1.6.2.2 Metabolic sources and reactions .................................................................... 97 1.6.3 DNA glycation by dicarbonyls ...................................................................... 99 1.6.4 Measurement of dicarbonyls ........................................................................ 100 1.6.5 Dicarbonyl proteome .................................................................................... 101 1.6.6 Clinical implications of dicarbonyls ............................................................ 103 1.6.7 Repair of glycated proteins .......................................................................... 103 1.7 Project-specific background ......................................................................... 105 1.7.1 Measurement of protein glycation, oxidation and nitration ......................... 105 1.7.1.1 Advances in measurement of protein glycation, oxidation and nitration adducts.........................................................................................................