Holding the front line: maintaining barrier integrity in the mouth

Piela, Krystyna Monika (2026) Holding the front line: maintaining barrier integrity in the mouth. PhD thesis, University of Glasgow.

Abstract

Background:
The oral cavity is a unique microenvironment challenged by a wide range of factors including masticatory forces, environmental factors and a diverse oral microbiome. The gingival crevice is lined by non-keratinised sulcular and junctional epithelia; the latter attaches to the tooth surface and is only a few cells thick. It has a uniquely tailored defence system to maintain health, including the presence of distinct subsets of neutrophils displaying characteristic phenotypes following exposure to biofilms. Failure of this barrier homeostasis results in gingival inflammation and – in susceptible patients – in destructive periodontal disease. There is a clinical need for improved preventative and therapeutic options for periodontal disease. There are parallel economic drivers to develop preventative and therapeutic products for the multi-million-pound oral care market. In vitro models can offer a reductionist platform for testing novel actives, reducing use of animals and costs of identifying and testing interventions. There has been a recent shift to focus on maintenance of health, rather than aetiopathogenesis of disease. This thesis sought to identify components of the oral mucosal barrier that maintain its integrity with the aim of integrating them into an in vitro model that will accurately reflect in vivo conditions.

Methods:
Literature and data searches were performed, and data were synthesised to identify key components of a healthy oral barrier in three main areas: i) microbiome and microbe-derived soluble mediators; ii) host cells; and iii) host soluble mediators. Cell culture and flow cytometry were used to evaluate potential host cells for use in the model. TR146 epithelial cells and primary human neutrophils were utilised to create a modified chemotaxis assay to mimic the egress of neutrophils at the gingival epithelium upon stimulation with health- and periodontitis-associated biofilms.

Results:
The review identified microbial taxa at the phylum, genus and species levels that were associated with periodontal health (Chapter 3). A novel in vitro model of multispecies microbial biofilm was developed that emulated certain characteristics of a health-associated subgingival biofilm (Chapter 4). TR146 epithelial cells could be grown on the basolateral side of a porous transwell insert membrane and remain metabolically active. Primary neutrophils were identified as a suitable cell type to model the early immune response in vitro (Chapter 5). Multispecies biofilms, TR146 epithelial cells, and primary neutrophils were combined to develop a proof-of-concept in vitro model designed to represent the oral barrier at the gingival sulcus (Chapter 6).

Conclusion:
The work to date has identified key components of the proposed model system and provided preliminary proof-of-concept evidence that selected components can be combined. Further work is needed to optimise and validate the model across different configurations and challenge conditions, as well as methods for reliable neutrophil tracking and detection of cytokine responses. This work may help to identify potential targetable pathways to maintain oral health.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Supported by funding from the Biotechnology and Biological Sciences Research Council (BBSRC) through Training Grant BB/W510099/1 Industrial CASE CSV.
• Subjects: R Medicine > R Medicine (General); R Medicine > RK Dentistry
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing > Dental School
• Funder's Name: Biotechnology and Biological Sciences Research Council (BBSRC)
• Supervisor's Name: Culshaw, Professor Shauna and Malcolm, Dr. Jennifer
• Date of Award: 2026
• Depositing User: Theses Team
• Unique ID: glathesis:2026-86086
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 26 Jun 2026 11:16
• Last Modified: 26 Jun 2026 12:47
• URI: https://theses.gla.ac.uk/id/eprint/86086