Thesis

Investigating tonsillar diseases using advanced optical microscopy

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Awarding institution
  • University of Strathclyde
Date of award
  • 2024
Thesis identifier
  • T17002
Person Identifier (Local)
  • 202087635
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Department, School or Faculty
Abstract
  • The paired palatine tonsils at the opening to the oropharynx are an important immune organ during adolescence. Due to their location inherently opening them to exogenous agents, they play a large role in immune defence. Their role also opens them to a variety of disease; acute recurrent tonsillitis is an infection of the palatine tonsil typically thought to be cause by Group A Streptococcal species. Tonsil hypertrophy due to obstructive sleep apnoea is characterised by enlarged tonsils. For both diseases, the only absolute cure is the complete removal of the tonsil via a routine tonsillectomy. This operation is not without risk and up to 20% of patients are readmitted to hospital within two weeks following surgery due to complications associated with bleeding. In many cases, antibiotic treatment does not suffice in the treatment of tonsillitis, leading to recurring infections. Biofilms are known to have increased antibiotic resistance, and have been shown to be involved in tonsillitis. This thesis aims to apply advanced optical microscopy and image analysis to quantify the biofilm presence on tonsil tissues, as well as to aid in discovery of biomarkers of tonsillitis infection. Imaging based studies of the palatine tonsil are often limited by the trade off between field of view and resolution which is present in optical microscopy. It is usually possible to image a large field of view with poor spatial resolution, or to image a small field of view with good spatial resolution. Within Chapter 2, the Mesolens, a novel optical microscope capable of imaging up to 6 mm x 6 mm (x 3 mm) with subcellular resolution, is used to investigate biofilm abundance and spatial distribution on both infected and hypertrophied tonsils. Studies are typically performed on fixed tissues; Chapter 2 aimed to investigate biofilm presence on fresh ex vivo whole mounts of tonsillar tissue, with as little alteration to its in vivo state as possible. Using these methods, it was shown that biofilms are equally distributed throughout the tonsil mass regardless of disease type. Within this Chapter, biofilms were detected in 100% of examined tonsil tissue mounts, which is in stark comparison to the approximately 70% of cases previously reported in literature. This is due to the combination of minimal sample preparation, no fixation step, and the large tissue volumes which could be imaged using the Mesolens. In Chapter 3, the Mesolens was used to image the distribution of bacteria and two interleukins within sections of tonsillar tissue. IL-17C is a cytokine which is selectively released in epithelial cells in response to bacterial stimulation, and had not previously been quantified in tonsil tissue. IL-1β is a pro-inflammatory cytokine which has previously been documented in tonsillitis, but with little information on its spatial distribution. It was hypothesized that, due to its production methods, IL-17C expression may be higher in tonsillitis patient tissue and therefore be a potential biomarker of disease. By using widefield mesoscopy and image analysis alongside standard molecular biology techniques, the ability to use IL-17C as a biomarker of infection was verified. IL-1β, however, could not be reliably identified as a biomarker for infection. The aforementioned methods involved the detection of structures or proteins within the tonsil tissue which had been stained with a fluorophore. However, it is possible to detect and differentiate between different cell types and disease types using the fluorescence lifetimes of endogenous fluorophores. Therefore, Chapter 4 aimed to use this property to determine if it was possible to use fluorescence lifetimes as an indicator of disease. Within this chapter, it was found that the τ1 lifetime component was significantly longer in ART than in OSA tissues, with no such significance witnessed in the other lifetime components.
Advisor / supervisor
  • McConnell, Gail
Resource Type
Note
  • This thesis was previously held under moratorium from 17th June 2024 until 17th June 2026.
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