Characterizing Cytotoxic and Regulatory CD4+ T cells in Patients with Primary Open-Angle Glaucoma (POAG)

Abstract

Purpose : Our previous study has demonstrated that the count of inflammatory T helper cells type 1 (Th1), especially the heat shock protein (HSP)-specific Th1 cell subset, is upregulated in association with glaucomatous neurodegeneration in mouse models and patients with primary open-angle glaucoma (POAG). We hypothesize that an imbalance between regulatory and inflammatory T cell populations is a key contributing factor to neural damage in glaucoma. Here, we aimed to further investigate the T cell profile in patients with POAG.

Methods : Peripheral blood monocytes (PBMC) were collected from POAG patients and unaffected control subjects; the two groups were similar in age, gender, and body mass index. T-cell profiles of POAG and control subjects were characterized by flow cytometry for counts of interferon (IFN)-γ⁺ CD4⁺ Th1 cells, granzyme B (GZMB)⁺ CD4⁺ cytotoxic T cells (CTL), and IL-10⁺ LAG-3⁺ CD4⁺ T regulatory type 1 cells (Tr1) cells. Data were presented as percentage of cell counts over total CD4⁺ PBMC. Real-time quantitative polymerase chain reaction (qPCR) was used to assess LAG-3 mRNA expression in total PBMC, while serum levels of shedded LAG-3 protein were quantified by ELISA.

Results : Flow cytometry analysis of PBMC trended toward higher cell counts of both non-specific and HSP60-specific Th1 in 8 POAG patients (visual field mean deviation, –7.2 ± 6.3 dB), whose Tr1 cell counts were drastically lower than the 5 control subjects. CTL count did not differ. mRNA levels of LAG-3 in PBMC (n=36) were significantly downregulated (2.981 vs 0.4136 relative mRNA fold change, P<0.05), while serum levels of shedded LAG-3 (n=36) were significantly upregulated (1.438 vs 0.3964 ng/mL, P<0.001) in 22 POAG patients compared to 14 control subjects.

Conclusions : The downregulation of LAG-3 mRNA in PBMC, in conjunction with the shedding of ectopically expressed LAG-3, along with the respective cell counts of Tr1 and Th1 being decreased and increased in the PMBC of patients with POAG, further support an autoimmune mechanism underlying the neurodegeneration in glaucoma. These results underscore the presence of an imbalance between regulatory and inflammatory T-cell responses in POAG patients, suggesting a promising new avenue for the development of neuroprotective therapies.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.