Candice Marie Colbey Bhsc (Honsclass1)

Transcriptional and translational networks linking the immune system to health and disease Author Colbey, Candice M Published 2019-12-16 Thesis Type Thesis (PhD Doctorate) School School of Medical Science DOI https://doi.org/10.25904/1912/1384 Copyright Statement The author owns the copyright in this thesis, unless stated otherwise. Downloaded from http://hdl.handle.net/10072/390022 Griffith Research Online https://research-repository.griffith.edu.au Transcriptional and translational networks linking the immune system to health and disease Title Page Candice Marie Colbey BHSc (HonsClass1) School of Medical Science Griffith Health Griffith University Submitted in fulfilment of the requirements of the degree of Doctor of Philosophy June 2019 Synopsis The contents of this thesis are organised into seven chapters and one appendix • Chapter 1 includes two literature reviews that discuss important factors associated with the development of upper respiratory symptoms (URS) in elite athletes. The first review discusses URS, its incidence and prevalence in elite athletes as well as the effects that exercise has on the immune system at the level of immune gene expression, immune cell phenotype and immunometabolism. The second review was published in Sports Medicine and is presented here in its published form. This review discusses the relationship between exercise, the gut microbiota, the common mucosal immune system and the risk, prevalence and incidence of URS. • Chapter 2 reports the incidence of URS in a cross-sectional study of elite Australian athletes, during a 30-day period, three months prior to a summer Olympic Games. Based on epidemiological data, the cohort was split into the two groups that are studied throughout this thesis; a group that did not present with URS (asymptomatic group) and a group that reported URS for a minimum of two days in the previous month (URS group). The chapter assessed the relationship between lifestyle factors and URS and used several questionnaires relating to the areas of psychology, illness, injury, training load, sleep, energy availability and travel. The assessment of lifestyle factors is a quick and non-invasive method of inquiry that can be used to highlight factors that were or were not linked with the incidence of URS in elite athletes. • Chapter 3 presents an in-depth comparison of peripheral blood mononuclear cell (PBMC) phenotypes between the URS and asymptomatic groups. Immune cell phenotyping was performed to characterise PBMC sub-populations. Circulatory PBMCs are a relatively accessible and representative tissue for analysing the phenotypic and functional aspects of immune competency. Differences in immune phenotype can represent differences in immune function, which involves the reactions and processes of many cell types that represent the innate and adaptive response (1). Differences in immune function may reflect an athletes potential for developing URS (2). Immune cell phenotype was measured using mass cytometry, 2 using the CyTOF2 mass cytometer (Fluidigm, CA, USA) and data was evaluated using a traditional gating strategy in FlowJo_V10 software (Oregon, USA) as well as using an advanced machine learning approach using the Cytobank platform (Santa Clara, USA). • Chapter 4 compared the results of immune gene expression analysis using peripheral blood between the URS and the asymptomatic groups. An essential link between the genome and immune cell phenotype is gene expression. The study of gene expression can reveal key differences associated with illness (3). To undertake this analysis, novel digital gene expression technology from NanoString Technologies (NanoString Technologies, WA, USA) was used. • Chapter 5 compared the metabolic profile and mitochondrial parameters of PBMCs between the URS group and the asymptomatic groups using the Cell Mito Stress Test Kit (Agilent Technologies, Santa Clara, USA). For optimal immune function, it is crucial that the metabolic requirements of immune cells are met. Exercise training is a significant physiological stress for elite athletes. Meeting the energy and nutrient requirements to maintain healthy immune function, in addition to the requirements posed by the energy demand of exercise, can be difficult to achieve for elite athletes (4). Nutritional deficiencies increase the risk of poor immune function and immune cell metabolism (5). Early evidence examining metabolic demands within immune cells has demonstrated metabolic shifts in response to various stimuli and fluctuations in substrate availability (5). • Chapter 6 contains a small pilot study that compared the gut microbial profiles of a subset of the original cohort, between six female soccer players reporting URS and six asymptomatic female soccer players. The link between the gut microbiota and health is of growing interest. The gut microbiota is involved in digestion, nutrient production, metabolism, priming of the immune system in infancy and immune defence (6, 7). Although diet is the main contributor to gut microbial composition, a recent study comparing 40 elite rugby players to healthy, non-athletes, demonstrated that exercise was positively correlated with the composition of the gut microbiota (8). 3 However, it is difficult to discern the extent to which diet and exercise shape the gut microbiota independently and to what extent these factors overlap and contribute to health (8). This pilot study used 16S rRNA sequencing using the Illumina MiSeqTM II system from Macrogen Inc. (Seoul, South Korea). To the best knowledge of this candidate, this study is the first comparison of the gut microbial profile in association with the incidence of URS. • Chapter 7 discusses the general conclusions of each study presented in this thesis and how this body of research contributes to understanding the association between exercise, the immune system and upper respiratory symptoms in elite athletes. 4 Statement of Originality This work has not previously been submitted for a degree or diploma in any university. To the best of my knowledge and belief, the thesis contains no material previously published or written by another person except where due reference is made in the thesis itself. Candice Marie Colbey 28th June 2019 5 Table of Contents Title Page 1 Synopsis 2 Statement of Originality 5 Table of Contents 6 Acknowledgements 10 Preface: The relationship of this thesis to the Stay Healthy Project 11 Chapter 1a 14 1.1 Introduction 15 1.2 The Immune System 17 1.3 The Evolution of Exercise Immunology 19 1.4 The Patterns and Prevalence of URS in Athletic Populations 19 1.5 The Aetiology of URS in Elite Athletes 25 1.6 Mechanisms of Exercise-Induced Modulation of Immune Cells 26 1.6.1 Mechanical Factors that Modulate Immune Cells 26 1.6.2 Endocrine Factors that Modulate Immune Cells 26 1.6.3 Metabolic factors that Modulate Immune Cells 27 1.7 Immune Profiling in Exercise Immunology 28 1.8 Changes to Immune Cells Following Acute Exercise 28 1.9 Habitual Exercise and Changes to Immune Cell Frequency 34 1.10 Changes in Immune Gene Expression Induced by Acute Exercise 37 1.11 Resting Immune Gene Expression in Athletes 39 1.12 Immunometabolism 40 Chapter 1b 43 Upper respiratory symptoms, gut health and mucosal immunity in athletes 43 1.13 The Research Gaps 59 1.14 The Thesis Objective 60 1.15 Thesis Aims 60 Chapter 2 61 2.1 Introduction 64 2.1.1 Rationale 65 2.2 Methods 66 2.2.1 Study Design 66 2.2.2 Determining the Incidence of URS in Australian Olympic athletes 66 2.2.3 Measuring Lifestyle Factors in Australian Olympic Athletes 67 2.2.4 Assessment of Clinical Measurements in Australian Olympic Athletes 69 2.2.4.1 Sample Collection 69 2.2.5 Measuring Serum Cytokines 69 2.2.5.1 General Method 69 6 2.2.5.2 Sample, control, blank and standard preparation 70 2.2.5.3 The bead and sample incubation 71 2.2.5.4 Secondary anti-body incubation and Streptavidin PE incubation 71 2.2.5.5 Measure fluorescence emissions and determination of analyte concentrations 71 2.2.6 Hormone Measurement 72 2.2.7 Measurement of CRP 73 2.2.8 Statistical Analysis 73 2.3 Results 75 2.3.1 Incidence of URS in Australian Olympic Athletes was over 50% 75 2.3.2 Group Characteristics: Sport was Associated with URS 75 2.3.3 Probiotic Supplementation, Low-energy Availability and Fatigue were Associated with a higher incidence of URS 76 2.3.4 No standard clinical markers were able to differentiate the groups 76 2.3.5 Determining the Likelihood that an Athlete would report URS 81 2.3.6 Determining the Likelihood that a Female Athlete would report URS 82 2.4 Discussion 85 2.4.1 Clinical Application 87 2.4.2 Limitations 88 2.4.3 Conclusion 89 Chapter 3 90 3.1 Introduction 92 3.1.1 Rationale 93 3.2 Methods 94 3.2.1 Participants 94 3.2.2 Blood Sample Collection 94 3.2.3 PBMC Isolation 94 3.2.4 Mass Cytometry 94 3.2.5 Marker Staining and Cell Preparation 97 3.2.6 Representative Gating Strategy used to identify PBMC populations 101 3.2.7 Hierarchical Gating and Statistical Analysis of PBMC frequency 104 3.2.8 The CITRUS analyses 104 3.2.8a Comparing PBMC frequency between the groups using CITRUS 105 3.2.8b Comparing the Expression of Functional Immune Markers between the groups 107 3.3 Results 108 3.3.1 Group Characteristics 108 3.3.2 The Frequency of PBMC subsets was Similar Between the Groups 108 3.3.3 Comparison of Immune Cell Frequency using CITRUS 109 3.3.4 The Frequency of PBMC subsets was similar using CITRUS 114 3.3.5 Comparing the Expression of Functional Markers using CITRUS 114 3.3.6 Functional Markers were Lower in Athletes

Load more