Restoration of CMV-specific-CD4 T cells with ART occurs early and is greater in those with more advanced immunodeficiency

Abstract

Objectives: Restoration of Cytomegalovirus-specific-CD4 T cell (CMV-Sp-CD4) responses partly accounts for the reduction of CMV-disease with antiretroviral-therapy (ART), but CMV-Sp-CD4 may also drive immune activation and immunosenescence. This study characterized the dynamics of CMV-Sp-CD4 after ART initiation and explored associations with CD4 T cell recovery as well as frequency of naïve CD4 T cells at week 96.

Methods: Fifty HIV-infected, ART-naïve Thai adults with CD4 T cell count ≤ 350 cells/µL and starting ART were evaluated over 96 weeks (ClinicalTrials.gov identifier NCT01296373). CMV-Sp-CD4 was detected by co-expression of CD25/CD134 by flow cytometry after CMV-antigen stimulation.

Results: All subjects were CMV sero-positive, 4 had quantifiable CMV-DNA (range 2.3-3.9 log10 copies/mL) at baseline but none had clinically apparent CMV-disease. Baseline CMV-Sp-CD4 response was positive in 40 subjects. Those with CD4 T cell count < 100 cells/µL were less likely to have positive baseline CMV-Sp-CD4 response (P=0.003). Positive baseline CMV-Sp-CD4 response was associated with reduced odds of quantifiable CMV-DNA (P=0.022). Mean CD4 T cell increase at week 96 was 213 cells/µL. This was associated positively with baseline HIV-VL (P=0.001) and negatively with age (P=0.003). The frequency of CMV-Sp-CD4 increased at week 4 (P=0.008), then declined. Those with lower baseline CMV-Sp-CD4 (P=0.009) or CDC category C (P<0.001) had greater increases in CMV-Sp-CD4 at week 4. At week 96, CD4 T cell count was positively (P<0.001) and the frequency of CMV-Sp-CD4 was negatively (P=0.001) associated with the percentage of naïve CD4 T cells.

Conclusions: Increases in CMV-Sp-CD4 with ART occurred early and were greater in those with more advanced immunodeficiency. The frequency of CMV-Sp-CD4 was associated with reduced naïve CD4 T cells, a marker associated with immunosenescence.

Figure 1. Gating strategies for CMV-SP-CD4 T cells.

All flow cytometry plots are from a single subject of the RESTORE study. Lymphocytes were identified using forward and side scatter (Figure 1A), followed by gating on CD4+ T cells (Figure 1B). Gates for CD25+ and CD134+ cells were placed based on comparison with negative control (Figure 1C) and PHA positive control (Figure 1D) to include cells highly co-expressing CD25 and CD134. A representative example of the dynamics of responses to CMV antigens over 96 weeks of follow-up in a RESTORE subject (Figure 1E-K).

Figure 2. Changes in CMV-Sp-CD4 T cell response.

(2a) Mean (95%CI) change in CMV-Sp-CD4 (% of CD4 T cells) when compared to baseline over 96 weeks of ART based on a random effects regression model (* P<0.05). (2B) Mean (95%CI) change in absolute CMV-Sp-CD4 count (cells/mL) when compared to baseline over 96 weeks of ART based on a random effects regression model (* P<0.05).