Impact of Early Versus Late Antiretroviral Treatment Initiation on Naive T Lymphocytes in HIV-1-Infected Children and Adolescents - The-ANRS-EP59-CLEAC Study

Abstract

Background: The early initiation of antiretroviral therapy (ART) in HIV-1-infected infants reduces mortality and prevents early CD4 T-cell loss. However, the impact of early ART on the immune system has not been thoroughly investigated in children over five years of age or adolescents. Here, we describe the levels of naive CD4 and CD8 T lymphocytes (CD4/CD8T_N), reflecting the quality of immune reconstitution, as a function of the timing of ART initiation (early (<6 months) versus late (≥24 months of age)).

Methods: The ANRS-EP59-CLEAC study enrolled 27 children (5-12 years of age) and nine adolescents (13-17 years of age) in the early-treatment group, and 19 children (L-Ch) and 21 adolescents (L-Ado) in the late-treatment group. T lymphocytes were analyzed by flow cytometry and plasma markers were analyzed by ELISA. Linear regression analysis was performed with univariate and multivariate models.

Results: At the time of evaluation, all patients were on ART and had a good immunovirological status: 83% had HIV RNA loads below 50 copies/mL and the median CD4 T-cell count was 856 cells/µL (interquartile range: 685-1236 cells/µL). In children, early ART was associated with higher CD8T_N percentages (medians: 48.7% vs. 31.0%, P = 0.001), and a marginally higher CD4T_N (61.2% vs. 53.1%, P = 0.33). In adolescents, early ART was associated with low CD4T_N percentages and less differentiated memory CD8 T cells. CD4T_N and CD8T_N levels were inversely related to cellular activation and gut permeability.

Conclusion: In children and adolescents, the benefits of early ART for CD8T_N were clear after long-term ART. The impact of early ART on CD4T_N appears to be modest, because pediatric patients treated late respond to HIV-driven CD4 T-lymphocyte loss by the de novo production of T_N cells in the thymus. Our data also suggest that current immune activation and/or gut permeability has a negative impact on T_N levels.

Clinical trial registration: ClinicalTrials.gov, identifier NCT02674867.

Keywords: HIV-1; T lymphocyte; adolescents; children; early ART; naive T lymphocyte.

Figure 1

CD4 T-cell subsets in patients treated early and late. T-cell phenotypes were assessed by flow cytometry on fresh whole blood ( Supplementary Material ). The percentage of each subset among total CD4 T lymphocytes is presented for children (A) and adolescents (B), on box and whiskers plots showing the minimum and maximum values. The early and late treatment groups were compared in Mann-Whitney tests; when significant, P values are shown on the graph. Subsets are presented from the least to the most differentiated, and were defined as naive T_N (CD45RA⁺CCR7⁺); recent thymic emigrants, T_RTE (CD45RA⁺CCR7⁺CD31⁺); CD31^negT_N (CD45RA⁺CCR7⁺CD31^-); central memory, T_CM (CD45RA^-CCR7⁺); transitional memory T_TM (CD45RA^-CCR7^-CD27⁺); effector memory T_EM (CD45RA^-CCR7^-CD27^-) and effector T_EF (CD45RA⁺CCR7^-CD27^-CD28-) cells. (C) The correlograms present Spearman’s rank correlation coefficients as symbols (upper quadrants) and values. Significant associations are indicated by symbols (*p < .05; **p < .01; ***p < .001). CD4 T-cell counts were used for correlation analyses.

Figure 2

Linear regression analysis of the associations between CD4T_N and demographic, virological and immunological factors in children and adolescents. Results from univariate (A, B) and multivariate (C, D) linear regressions are presented as estimates (β) and 95% confidence intervals. Significant associations are indicated by symbols (*p < .05; **p < .01; ***p < .001). Multivariate analysis included the covariables indicated on the plot. A and C: children; B and D: adolescents. Estimates are given per year, 100 CD4 T cells, and 1% activated CD4T_M.

Figure 3

CD8 T-cell differentiation subsets in patients with early and late treatment initiation. T-cell phenotypes were assessed by flow cytometry on fresh whole blood ( Supplementary Material ). The percentage of each subset among total CD8 T lymphocytes is presented for children (A) and adolescents (B) on box and whiskers plots showing the minimum and maximum values. Early and late treatment groups were compared in Mann-Whitney tests; when significant, P values are shown on the graph. Subsets are presented from the least to the most differentiated, and were defined as naive T_N (CD45RA⁺CCR7⁺); central memory T_CM (CD45RA^-CCR7⁺); effector memory T_EM27+28+ (CD45RA^-CCR7^-CD27⁺CD28⁺); T_EM27-28+ (CD45RA^-CCR7^- CD27^-CD28⁺); T_EM27+28- (CD45RA^-CCR7^- CD27⁺CD28^-); T_EM27-28- (CD45RA^-CCR7^- CD27^-CD28^-) and effector T_EF (CD45RA⁺CCR7^-CD27^-CD28-) cells. (C) The correlograms present Spearman’s rank correlation coefficients as symbols (upper quadrants) and values. Significant associations are indicated by symbols (*p < .05; **p < .01; ***p < .001). CD4 T-cell counts were used to calculate correlations.

Figure 4

Linear regression analysis of the associations between CD8T_N and demographic, virological and immunological factors in children and adolescents. Results from univariate (A, B) and multivariate (C, D) linear regressions are presented as estimates (β) and 95% confidence intervals. Significant associations are indicated by symbols (*p < .05; **p < .001; ***p < .0001). Multivariate analysis included the covariables indicated on the plot. Estimates are given per year, per 0.1 units of normalized viral suppression, per unit of normalized cumulative viremia, per point of CD4/CD8 ratio, and per 1% of activated CD4T_M.