Fig. 5

GARP expression on CD4⁺Foxp3⁺ T cell are progressively decreased in different severity of emphysema. A Representative flow cytometry plots of GARP expression are shown. B The proportions of Foxp3⁺GARP⁺ and Foxp3⁺GARP⁻ subsets among CD4⁺ T cells in all subjects. C Negative statistical correlation between frequency of circulating FoxP3⁺GARP⁺ and LAA% (C, Left). Positive statistical correlation between frequency of circulating FoxP3⁺GARP⁻ cells and LAA% (C, Right). r = − 0.63, p < 0.001 and r = 0.72, p < 0.001 by Pearson’s correlation. D Expression of Treg cell function-specific markers (CTLA-4 and TIGIT) and activation markers (Ki-67) in peripheral FoxP3⁺GARP⁺ cells. One-way ANOVA with post-hoc pairwise multiple comparisons using Tukey’s method. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001. E Representative staining of CD4⁺ T cells for GARP, CD127, and FOXP3 expression. CD4⁺ T cells were stained for CD127 and FOXP3 expression as resting T cells and for GARP and FOXP3 expression following 1 day of TCR activation. F Analysis of Foxp3⁺CD127⁻ T cells from all subjects