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Updated: May 12, 2026
Induction of Ocular Surface Inflammation and Collection of Involved Tissues
Published on: August 4, 2022
Characterization of the ocular inflammatory response to AAV reveals divergence by sex and age
Alison J Clare1, Philip M Langer2, Amy Ward2
1Academic Unit of Ophthalmology, Translational Health Sciences, University of Bristol, BS8 1TD Bristol, UK; NIHR Biomedical Research Centre of Ophthalmology, Moorfields Eye Hospital, EC1V 2PD London, UK.
Abstract:
Progress for ocular adeno-associated virus (AAV) gene therapy has been hindered by AAV-induced inflammation, limiting dose escalation and long-term efficacy. Broadly, the extent of inflammatory responses alters with age and sex, yet these factors are poorly represented in pre-clinical development of ocular AAV gene therapies. Here, we combined clinical imaging, flow cytometry, and bulk sequencing of sorted microglia to interrogate the longitudinal inflammatory response following intravitreal delivery of AAV2 in young (3-month-old), middle aged (9-month-old), and old (18-month-old) Cx3cr1-creER:R26tdTomato+/- mice of both sexes. Young males and females exhibited a similar dynamic response, with peak inflammation evident at days 10-12 and signs of clinical resolution by day 28. However, the magnitude of the transcriptional response by microglia and adaptive T cell infiltrate differed between sexes. With age, increased and persistent inflammation were observed in both sexes, although old males maintained their microglia transcriptional AAV response signature. Contrarily, females demonstrated greater divergence in their inflammatory response across age, with enriched cellular stress and inflammatory gene expression in older mice and corresponding signs of retinal degeneration. These findings inform crucial sex and age differences for the therapeutic application of ocular gene therapy, highlighting the need to further understand these factors to overcome AAV immunogenicity.
Insights
Ocular gene therapy using adeno-associated virus (AAV) faces inflammation challenges. Age and sex significantly impact AAV-induced inflammation, affecting preclinical models and therapeutic outcomes.
Area of Science:
- Ophthalmology
- Immunology
- Gene Therapy
Background:
- Adeno-associated virus (AAV) gene therapy for ocular conditions is promising but limited by immune responses.
- Inflammation induced by AAV hinders dose escalation and long-term treatment efficacy.
- Preclinical models often overlook age and sex differences in AAV immunogenicity.
Purpose of the Study:
- To investigate the longitudinal inflammatory response to ocular AAV gene therapy across different ages and sexes.
- To characterize the role of microglia and T cells in age- and sex-dependent inflammation.
- To identify factors influencing AAV immunogenicity in ocular gene therapy.
Main Methods:
- Intravitreal delivery of AAV2 in young, middle-aged, and old mice of both sexes.
- Longitudinal monitoring using clinical imaging and flow cytometry.
- Bulk sequencing of sorted microglia to analyze transcriptional responses.
Main Results:
- Young males and females showed similar inflammation dynamics, resolving by day 28.
- Sex differences emerged in microglial transcriptional response and T cell infiltration.
- Older mice exhibited increased and persistent inflammation, with females showing greater divergence and signs of retinal degeneration.
Conclusions:
- Age and sex are critical factors influencing ocular AAV gene therapy outcomes.
- Inflammatory responses vary significantly with age and sex, impacting therapeutic efficacy.
- Further research into these factors is necessary to overcome AAV immunogenicity.
