Elevation of Tim-3 and PD-1 expression on T cells appears early in HIV infection, and differential Tim-3 and PD-1 expression patterns can be induced by common γ -chain cytokines

Abstract

Purpose: To explore the association between differential Tim-3 and PD-1 expression patterns and HIV disease progression, and to investigate the impact of common γ-chain cytokines on Tim-3 and PD-1 expression patterns on T cells.

Methods: Tim-3/PD-1 expression on the T cells of patients with early and chronic HIV infections was detected. The expression levels and functional profiles of T cells with differential Tim-3 and PD-1 expression patterns induced by γ-chain cytokines were studied.

Results: The elevation of differential Tim-3 and PD-1 expression patterns on T cells appeared early in HIV infection. Co-expression of Tim-3 and PD-1 (Tim-3+PD-1+) correlates with more severe exhaustion of T cells during HIV infection. In vitro stimulation of common γ-chain cytokines can induce differential expression patterns of Tim-3 and PD-1 on T cells. The enhancement of Tim-3 and PD-1 expression by common γ-chain IL-2 can inhibit the function of T cells re-stimulated by HIV gag and TCR, not by the re-stimulation of IL-2.

Conclusions: The elevation of differential Tim-3 and PD-1 expression patterns on T cells represents a state of T cell exhaustion and can be induced by common γ-chain cytokines. These findings provide insights into HIV pathogenesis and help inform immune intervention strategies.

Figure 1

Comparison of levels of differential expression patterns of Tim-3 and PD-1 (Tim-3+PD-1+, Tim-3-PD-1+, and Tim-3+PD-1−) on T cells in HIV-1 infected patients and normal controls. (a) Representative data regarding the expression patterns of Tim-3 and PD-1 in a normal control and in a chronic HIV-infected patient. (b) The percentages of differential Tim-3/PD-1 expression patterns on the CD4+ and CD8+ T cells of normal controls (NC, n = 9), early HIV-infected patients (EHI, n = 9), and chronic HIV-infected patients (CHI, n = 35). (c) The percentages of Tim-3/PD-1 expression patterns on the CD4+ and CD8+ T cells of chronic HIV-infected patients with different CD4+ T-cell counts (more than or less than 350 cells/μL) and viral loads (more than or less than 20,000 copies/mL).

Figure 2

Correlation between percentages of differential Tim-3/PD-1 expression patterns (Tim-3-PD-1+, Tim-3+PD-1+, and Tim-3+PD-1−) on CD4+ and CD8+ T cells and (a) CD4+ T-cell counts and (b) viral loads.

Figure 3

Functional study of Tim-3/PD-1 expression patterns on T cells. (a) PBMCs from HIV-infected patients (n = 4) were stimulated with TCR (anti-CD3/CD28) for 3 days, and IL-2 and IFN-γ production by T cells were detected. Distributions of Tim-3/PD-1 expression patterns on IFN-γ- and IL-2-producing T cells are indicated. (b) Statistical analysis of the distribution of differential Tim-3/PD-1 expression patterns on the IFN-γ- and IL-2-producing T cells (^* P < 0.05). (c) PBMCs from HIV-infected patients were stimulated with anti-CD3 and anti-CD28 (n = 4) antibodies or HIV gag peptides (n = 8) with or without blocking antibodies (anti-Tim-3 and PD-1). IFN-γ and IL-2 production by CD4+ and CD8+ T cells before and after the anti-Tim-3/PD-1 blockade were compared (^* P < 0.05).

Figure 4

Common γc cytokine-mediated induction of Tim-3/PD-1 expression patterns on T cells in PBMCs from HIV patients. Tim-3 and PD-1 expression on T cells were analyzed following a five-day period of stimulation and compared with those of cells cultured in control medium (n = 12). This figure compares the abilities of different common γc cytokines to induce the expression of the Tim-3+PD-1+, Tim-3-PD-1+ and Tim-3+PD-1− patterns on T cells (^* P < 0.05; ^** P < 0.01).

Figure 5

Functional consequences of γc cytokine-mediated modulation of Tim-3 and PD-1 expression on T cells. PBMCs prestimulated with IL-2 (n = 5) were harvested at 6 days after stimulation, washed, and then restimulated with HIV gag peptides, TCR, or IL-2 in the presence of blocking antibodies (anti-Tim-3/PD-1). IL-2 and IFN-γ production by CD4+ and CD8+T cells were detected by intracellular cytokine staining.