Abstract
Purpose :
Besides glia-driven innate immune responses, antigen immunization/adoptive transfer in animal models and analysis of blood samples/autoantibodies/postmortem tissues in human support the activation of adaptive immunity during glaucomatous neurodegeneration. This study aimed to further explore T cell responses in human glaucoma.
Methods :
Blood samples were collected from 24 patients with glaucoma and 19 non-glaucomatous controls, and mononuclear cells were isolated by Histopaque density gradient centrifugation. To phenotype helper (Th) and cytotoxic fractions of T cells, isolated cells were stained with antibodies to CD4 or CD8, respectively, and distinctive markers, such as CD25, FoxP3 (Treg), IFN-γ (Th1), IL-4 (Th2), and IL-17 (Th17), for multicolor flow cytometry-based analysis of T cell subset distribution. In addition, in vitro assays determined the activation of antigen-specific T cells after stimulation with Dynabeads Human T-activator CD3/CD28/CD137 in the presence and absence of IL-2 or IL-7 (or human retinal antigens). After stimulation/expansion, T cell proliferation was determined by CD4, CD8, CD38 labeling and Click-iT EdU assay, and cytokine secretion in culture supernatant was measured by multi-analyte ELISArray.
Results :
A glaucoma-related shift was detectable by analysis of T cell subset distribution. Despite similar CD4 to CD8 ratios between glaucomatous and non-glaucomatous samples (p>0.05), there was a trend for altered pattern of pathogenic versus regulatory T cells in glaucomatous samples, most prominently including decreased ratios of CD4/CD25/FoxP3+ (CD4Treg) and CD8/CD25/FoxP3+ (CD8Treg) regulatory T cell populations relative to entire CD4+ or CD8+ populations (p<0.03). In addition, T cells isolated from glaucomatous samples exhibited approximately three-fold stimulated response as characterized by increased proliferation (p<0.01) and cytokine secretion (p<0.001).
Conclusions :
Along with the population shifts, alterations in proliferative activity and cytokine production of T cells are supportive of disrupted immune homeostasis towards autoimmunity in human glaucoma. Longitudinal information from continued analysis of covariates (different types and stages of glaucoma, intraocular pressure levels, systemic diseases, and treatments) in larger cohorts should help determine whether dysregulated T cell responses have neurodegenerative potential and/or serve as biomarkers for clinical predictions of glaucoma.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.