Dynamics and immunological signature of γδ T cells following antiretroviral therapy initiation in acute HIV-1 Infection

Abstract

Early antiretroviral therapy (ART) is essential for controlling HIV-1 replication and boosting immune function. γδ T cells, as a vital component of the innate immune system, are implicated in the antiviral response. However, their immunological profile during acute HIV-1 infection and the early stages of ART remains unclear. This study aimed to delineate the immunological landscape of γδ T cells in individuals with acute HIV-1 infection undergoing early ART. We enrolled 65 participants who initiated ART immediately post-diagnosis and assessed the phenotypes and functions of γδ T cells using flow cytometry. We demonstrated that early ART significantly increased the frequency of Vδ2 T cells, while the Vδ1 T cell frequency remained stable and showed an inverse relationship with CD4⁺ T cell counts after ART. Early ART normalized the activation and PD-1 expression in Vδ1 and Vδ2 T cells, aligning with healthy controls (HCs) levels. Nevertheless, the proliferation of these cells, particularly within the PD-1⁺ subset, remains elevated post-ART. We also noted a reduction in perforin secretion in PD-1⁺ Vδ1 and Vδ2 T cells of people living with HIV (PLWH). Furthermore, Vδ1 T cells were identified as the predominant regulatory T cells, with TGF-β production and co-expression of CD127 and CXCR4, negatively correlated with CD8⁺ T cell activation. Our study elucidates the dynamic immunological characteristics of γδ T cells in acute HIV-1 infection and early ART, contributing to the understanding of their role in HIV-1 pathogenesis and the potential for γδ T cell-based immunotherapeutic strategies.

Keywords: antiretroviral therapy (ART); early/acute HIV-1 infection; immune activation; regulatory T cells; γδ T cells.

Figure 1

Dynamic of γδ T cell subsets after early ART. Comparison of the frequencies of Vδ1 T cells (A), Vδ2 T cells (B) and Vδ1/Vδ2 ratios (C) among HCs, PLWAHs at baseline, week 24, 48 and 96 of early ART. Correlations of Vδ1 T cells with CD4⁺T cell counts (D) and plasma viral load (E) in PLWAHs at baseline. Correlations of Vδ2 T cells with CD4/CD8 ratios (F) and plasma viral load (G) in PLWAHs at baseline. (H, I) Correlation of Vδ1 T cells or Vδ2 T cells with CD4⁺T cell counts in PLWAHs after 96 weeks of ART. HCs, healthy controls; PLWAHs, people living with acute HIV-1 infection; **P < 0.01; ***P < 0.001; ****P < 0.0001.

Figure 2

The phenotypes of γδ T cell subsets in PLWAHs. Markers for immune activation, exhaustion, and cytolysis on γδ T cell subsets were detected by flow cytometry. The frequencies of CD38⁺HLA-DR⁺Vδ1 T cells (A), CD38⁺HLA-DR⁺Vδ2 T cells (B), PD-1⁺Vδ1 T cells (C), PD-1⁺Vδ2 T cells (D), CD56⁺Vδ1 T cells (E), CD56⁺Vδ2 T cells (F) were compared among HCs, PLWAHs at baseline, week 24, 48 and 96 of early ART. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.

Figure 3

Early ART insufficient for full γδ T cell proliferation recovery. Comparison of the frequencies of Ki67 expression in Vδ1 T cells (A) or Vδ2 T cells (B) among HCs and PLWAHs at different timepoints. (C, D) Percentage of Ki67 expression in PD-1⁺ and PD-1^- Vδ1 T cells or Vδ2 T cells in HCs, PLWAHs at baseline and after 96 weeks of early ART. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.

Figure 4

The cytotoxicity of γδ T cells. Comparison of the frequencies of perforin expression in Vδ1 T cells (A) or Vδ2 T cells (B) among HCs and PLWAHs at different timepoints. (C, D) Percentage of perforin expression in PD-1⁺ and PD-1^- Vδ1 T cells or Vδ2 T cells among HCs, PLWAHs at baseline and after 96 weeks of early ART. (E, F) Percentage of perforin expression in CD56⁺ and CD56^- Vδ1 T cells or Vδ2 T cells among HCs, PLWAHs at week 0 and week 96 after early ART. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.

Figure 5

Dynamic of regulatory γδ T cells in early HIV-1 infection. (A) The frequencies of Tregs in CD4⁺T cells, Vδ1 and Vδ2 T cells in HCs and PLWAHs. (B-D) Comparisons of the frequencies of Tregs in Vδ1, Vδ2 T cells and CD4⁺T cells among HCs and PLWAHs at different timepoints. (E, F) Correlations of the frequencies of Vδ1Tregs with CD8⁺T cell activation at baseline and 96 weeks of ART were calculated by Spearman rank’s correlation test. *P < 0.05; ***P < 0.001; ****P < 0.0001.

Figure 6

γδ T cells mediate immunosuppression through TGF-β secretion. (A) Comparison of the TGF-β secretion in CD4⁺T cells, Vδ1 and Vδ2 T cells in HCs and PLWAHs. Comparison of TGF-β expression in Vδ1 T cells (B), Vδ2 T cells (C), and CD4⁺T cells (D) among HCs and PLWAHs at different timepoints. (E, F) The expression of TGF-β in Vδ1 T cells were co-expressed with CD127 and CXCR4 in both HCs and PLWAHs. (G, H) Correlations of the frequencies of TGF-β⁺ Vδ1 T cells with CD8⁺T cell activation at baseline or 96 weeks of ART were calculated by Spearman rank’s correlation test. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.

Figure 7

Comparison of immune phenotypes between γδ T cells and CD4⁺T cells. (A-D) Frequencies of CD38⁺HLA-DR⁺, PD-1⁺, Ki67⁺ and PD-1⁺Ki67⁺ cells among CD4⁺T cells, Vδ1 T cells and Vδ2 T cells were compared between HCs and PLWAHs. (E, F) Correlations of the frequencies of CD38⁺HLA-DR⁺, PD-1⁺, Ki67⁺ and PD-1⁺Ki67⁺ cells, as well as CD4⁺T cell counts and CD4/CD8 ratios, between γδ T cells and CD4⁺T cells at baseline (E) and after 96 weeks of ART (F). Correlation coefficients were calculated using Spearman rank’s correlation test. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.