Explore the intricate relationship between age, sex, and microbiota rhythmicity in individuals suffering from obesity and type 2 diabetes with this comprehensive research document. This in-depth analysis presents vital findings on how demographic factors influence gut microbiome patterns, shedding ...
EFFECTS OF AGE AND SEX ON MICROBIOTA RHYTHMICITY IN INDIVIDUALS
WITH TYPE 2 DIABETES AND OBESITY
BSc (Hons) Biomedical Science
University of Surrey
Faculty of Health and Medical Sciences
Submitted May 2023
,Abstract
The circadian clock and human gut microbiota are essential for maintaining the homeostatic balance of host health
and have been related to various metabolic diseases, such as type 2 diabetes and obesity (Zhao et al., 2022). Similar
to many other physiological activities in the human body, the gut microbiota displays a circadian pattern of activity.
The diversity and abundance of the gut microbiota fluctuate, with some bacterial species becoming more active at
specific time points during the day. This study used secondary data analysis to investigate how age and sex influence
the microbiome rhythmicity in individuals with obesity and type 2 diabetes. The method used in the study comprised
secondary data collection and analysis, including 24-hour faecal microbiota sampling from 1,942 individuals (Reitmeier
et al., 2020). Diurnal changes in the relative abundance of the three major phyla, Bacteroidetes, Firmicutes and
Proteobacteria, were measured for all variables. These three phyla are the most prevalent, and Bacteroidetes and
Firmicutes abundance was associated with metabolic diseases. The results indicated that age, sex, and disease state
substantially impacted microbiota rhythmicity over 24 hours. Particularly, the microbiota rhythmicity varied according
to sex and age in individuals with type 2 diabetes and obesity. Findings showed that females had higher microbiota
rhythmicity than males regardless of disease state, and healthy middle-aged females had higher microbiota
rhythmicity compared to elderly females. However, obese and type 2 diabetic elderly and middle-aged individuals had
no microbiota rhythmicity. These findings could have significant implications for the development of tailored
treatments and interventions for individuals with obesity and type 2 diabetes to enhance their overall health. In
conclusion, this study highlights the important role circadian rhythm play in changing the gut microbiota composition
and diversity at specific time points over 24 hours in healthy and unhealthy individuals.
Acknowledgement
First and foremost, I would like to express my gratitude to my supervisor Dr Silke Kiessling who guided and provided
continuous support to me throughout this research project. I appreciate Dr Silke’s willingness to make some time to
discuss and explain the project during the course of the project, as well as the generous feedback and suggestions to
help me make improvements. Dr Silke’s expertise, guidance and patience have been important in shaping my research
project and helping me navigate various data collection challenges.
Also, I would like to sincerely thank my personal tutor Dr Victoria Revell for their willingness to provide immense
support, guidance, and constructive feedback. Dr Revell’s constant motivation, unwavering support and dedication
have been invaluable in helping me to complete my research project. I am grateful for the time and effort Dr Revell
has invested in providing detailed feedback and advice throughout this project.
I would also like to thank my family for providing me with everything I needed to maintain my direction and stay
focused throughout my study. Their encouragement and support throughout this project helped me stay motivated
at difficult times and enabled me to complete this project. Lastly, I would like to express my thanks to all my friends,
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,who have made me smile through difficulties and gave me moral support throughout these years of study. Also, I
would like to convey my appreciation to everyone who has supported me in any respect throughout this project.
Table of Contents
Abstract .......................................................................................................................................................................... 1
Acknowledgement ......................................................................................................................................................... 1
Table of Contents ........................................................................................................................................................... 2
List of Abbreviations ...................................................................................................................................................... 3
1. Introduction ........................................................................................................................................................... 4
1.1 Circadian Rhythms ................................................................................................................................................... 4
1.2 Gut Microbiota ......................................................................................................................................................... 5
1.3 Literature Review ..................................................................................................................................................... 6
1.4 Project Aims and Hypothesis ................................................................................................................................... 7
2. Materials and Methods.......................................................................................................................................... 7
2.1 Secondary Experimental Model and Study ............................................................................................................. 7
2.2 Selection of Metagenomic Data .............................................................................................................................. 8
2.3 Production of Diurnal Profiles ................................................................................................................................. 8
2.4 Statistical Analysis of Data ....................................................................................................................................... 9
3. Results .................................................................................................................................................................... 9
3.1 Effect of sex on the alpha diversity and relative abundance of the microbiota composition in obese individuals.10
3.2 Effect of sex on the alpha diversity and relative abundance of the microbiota composition in type 2 diabetic
individuals .................................................................................................................................................................... 13
3.3 Effect of age on the alpha diversity and relative abundance of the microbiota composition in obese males and
females ......................................................................................................................................................................... 16
3.4 Effect of age on the alpha diversity and relative abundance of the microbiota composition in type 2 diabetic
males and females ....................................................................................................................................................... 19
4. Discussion ............................................................................................................................................................. 22
5. Conclusion ............................................................................................................................................................ 25
6. Glossary ................................................................................................................................................................ 26
7. Bibliography ......................................................................................................................................................... 27
8. Appendix .............................................................................................................................................................. 31
Appendix A: Non-significant microbial diversity and abundance in non-obese and obese individuals ..................... 31
Appendix B: Non-significant microbial diversity and abundance in non-T2D, pre-diabetic and T2D individuals ...... 33
Appendix C: Non-significant microbial diversity and abundance in non-obese and obese middle-aged and elderly
individualsalp ............................................................................................................................................................... 35
Appendix D: Non-significant microbial diversity and abundance in non-T2D, pre-diabetic and T2D middle-aged and
elderly individuals ........................................................................................................................................................ 37
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, List of Abbreviations
ANOVA Analysis of Variance Analysis
BMI Body Mass Index
DM Diabetes Mellitus
DNA Deoxyribonucleic Acid
HbA1c Haemoglobin A1C
KORA Cooperative Health Research in the Region of Augsburg
PCR Polymerase Chain Reaction
Per2 Period Circadian Regulator 2
rRNA Ribosomal Ribonucleic Acid
SEM Standard Error of the Mean
SCN Suprachiasmatic Nucleus
T2DM Type 2 Diabetes Mellitus
zOTU Zero-radius Operational Taxonomic Unit
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