Purpose: Thyroid-associated Ophthalmopathy (TAO) is one of the most
common orbital immunological diseases in adults. CD4+ helper T (Th) cells play
important roles in the pathogenesis of TAO. But the mechanisms regulating CD4+ T cell
activity is unclear. This study examines T cell immunoglobulin domain and mucin
domain 3 (TIM-3) expression in helper T cell type 1 (Th1), Th17, and regulatory T cells
in sufferers of TAO.
Methods: Participants were divided into 3 groups: patients with TAO, patients with
Graves’ disease but without orbitopathy (GD), and healthy control patients (HC).
Peripheral blood samples were collected for each patient in the designated group. Flow
cytometry methods assessed the frequency of Th1 (CD4+IFN-γ+), Th17 (CD4+IL-17+),
regulatory T cells (CD4+CD25hiCD127lo), and TIM-3 protein expression. Mean
fluorescence intensity (MFI) measured the magnitude of TIM-3 expression and the
percentage of TIM-3+ cells for each patient.
Results: Compared to the GD group, TAO patients possessed higher frequencies of
Th1 and Th17 cells in peripheral blood samples. The percentage of TIM-3+ Th1 and
Th17 cells was significantly lower in the TAO patients than the GD group. Across all
patients sampled, TIM-3+ cell percentage negatively correlated with Th1 cell frequency.
Th1 and Th17 cells exhibited significantly decreased expression of TIM-3 in TAO
patients compared to healthy controls. Regulatory T cells showed little TIM-3 expression
and we observed no significant differences in frequency between groups.
Conclusion: These results suggest a role for TIM-3 in the regulation of Th1 and Th17
cells and the pathogenesis of Graves’ ophthalmopathy.