Role of extracellular vesicles in allergic sensitization

Davis Tucis

Role of extracellular vesicles in allergic sensitization

Publication Date

July 27, 2026

Creator

Davis Tucis

University of Nottingham

Abstract

Introduction The escalating global prevalence of IgE-mediated allergic diseases, including food allergies such as egg allergy, represents a significant public health challenge, with implications for quality of life and healthcare systems worldwide. Affecting approximately 1.5% of children in Western countries and often persisting into adulthood, egg allergy exemplifies the growing burden of allergic conditions, characterized by severe symptoms that can escalate to life-threatening anaphylaxis. This rising incidence underscores an urgent need to unravel the complex mechanisms driving allergic sensitization—the initial immunological event triggered by first-time allergen exposure— to inform the development of effective therapeutic and preventive strategies for type 1 hypersensitivity. Despite advances in understanding allergen recognition and immune activation, the precise processes determining why certain individuals become sensitized remain incompletely elucidated, particularly the role of intercellular communication mediators. This PhD thesis investigates the immunomodulatory role of dendritic cell-derived extracellular vesicles (DC-EVs) in allergic sensitization, with a specific focus on their influence on naïve T-cell responses, using egg allergy as a model. Emerging evidence suggests that DC-EVs, potentially carrying allergens like ovalbumin (OVA), may serve as critical vectors in transmitting immunological signals, thereby shaping the trajectory of allergic immune responses. By exploring this hypothesis, the study addresses a critical knowledge gap, aiming to enhance our understanding of how these nanoscale vesicles contribute to the initiation and progression of allergic sensitization. Methods The research employed a novel human in vitro assay, meticulously developed and optimized across multiple chapters to investigate the role of DC-EVs in allergic sensitization. Methods included the isolation of peripheral blood mononuclear cells (PBMCs) from healthy and egg-allergic individuals, followed by CD14+ monocyte isolation and differentiation into DCs under optimized conditions (RPMI + 10% FBS for 5 days, then X-VIVO serum-free media, with 24-hour stimulation using 100 ng/ml LPS and/or OVA at 10 μg/ml). DCs were stimulated to generate EVs, which were isolated using size-exclusion chromatography and exposed to naïve T cells in three sequential doses. Flow cytometry was utilized to phenotype T cells and monitor cytokine production, including CD69, IFN-γ, IL-2, TNF-α, and IL-4. Results Chapter 4 established optimal DC culture conditions to ensure high viability and maturation, while Chapter 5 optimized EV isolation and characterization methods, adhering to MISEV 2024 guidelines. Key results, detailed in Chapter 6, revealed that DC-EVs do not act as the sole signal for naïve T-cell activation but function effectively as signal 3 when supported by anti-CD3 and anti-CD28 co-stimulation. Significant differences emerged between healthy and allergic groups, with healthy naïve T cells exhibiting a Th1-biased profile (higher IFN-γ and IL-2 expression) in control and unstimulated EV conditions, while allergic individuals showed a Th2 tendency. Exposure to LPS/OVA-stimulated DC-EVs in allergic individuals led to increased CD69 expression, indicating T-cell activation, alongside a marked reduction in IFN-γ and a rise in IL-4 production. This Th2 shift suggests that OVA-carrying DC-EVs may exacerbate allergic sensitization by promoting naïve T-cell differentiation toward a Th2 phenotype. Clustering analysis further confirmed inherent immunological differences between groups, which were modulated by EV source, highlighting the role of stimulatory context (e.g., LPS, OVA) in shaping EV immunogenicity. Conclusion In conclusion, this thesis demonstrates that DC-EVs play a pivotal role in allergic sensitization, particularly through their capacity to modulate naïve T-cell responses in an allergen-specific manner. The developed human assay provides a robust platform for future research, with implications for EV-based diagnostics and therapies targeting Th2-driven allergies. The findings underscore the importance of EV cargo and source in immune polarization, suggesting potential interventions to restore Th1/Th2 balance. However, limitations such as single-time-point cytokine measurements and unanalysed EV cargo necessitate further studies with time-course analyses and advanced profiling techniques. Continued research into EV diversity and their longitudinal effects remains essential to harness their full therapeutic potential, advancing the management of allergic diseases.

Item Type

ethesis

Thesis Type

PhD

Supervisors

Fairclough, Lucy