Table 1.
Patients' characteristics.
Figure 1.
Longitudinal follow-up of CD8 T-cell activation, CD4 cell counts and of plasma HIV-RNA levels in patients with primary HIV infection.
At baseline (Panel A), frequencies of CD38+HLA-DR+ CD8 T cells were compared in patients that remained untreated during the 6-month follow-up (n = 13, Untreated) and in patients that have been subsequently treated before M6 (n = 12, Subsequently treated). CD8 T-cell activation was longitudinally assessed in untreated patients (n = 13) by measuring the frequency of CD38+HLA-DR+ cells (Panel B) and of Ki-67+ cells (Panel C) among CD8+ T cells at baseline, day 15 (D15), month 1 (M1), month 3 (M3) and month 6 (M6). Panel D illustrates the proportion of CD38+HLA-DR+ cells among CD8 T cells in untreated patients, in ART-treated patients at M6 and in healthy controls (n = 14). CD4 T cell counts (Panel E) and plasma HIV-1 RNA levels (Panel F) were plotted as a function of time during the 6 months of follow-up in treated (blue lines) and untreated (red lines) patients. Data are expressed as mean ± SEM. Wilcoxon rank tests were performed and p values are indicated between indicated time points for untreated patients (Panels B, C, E, F). Mann-Whitney tests were performed to compare groups of patients (Panels A and D).
Figure 2.
Expression of chemokine receptors by Th17 cells during primary HIV infection.
Th1 and Th17 cells were assessed after 5 h PMA/ionomycin stimulation of fresh isolated CD4 T cells and defined by the expression of IFN-γ and IL-2 (Th1) or IL-17 (Th17). In each datasets, horizontal lines indicate the medians. Panels A-D show results at baseline; panel E illustrates both baseline and month 6 measurements. (Panel A) Frequency of CCR4, CCR6 and CXCR3 among bulk CD4 T cells, Th1 cells and Th17 cells. (Panel B) Correlation between the proportion of CCR6 expressing CD4 T cells and the Th17 frequency. Spearman's rank correlation coefficients ‘R’ and corresponding p values are indicated. (Panel C) Expression of CCR4, CCR6 and CXCR3 among Th17 cells in patients with high (>median) and low (<median) viral load at baseline. Median plasma HIV-RNA level was 5.65 log copies/mL. P values according to Mann-Whitney tests are indicated. (Panel D) Correlation between CCR6 expression on Th17 cells and plasma viral load. (Panel E) Expression of CCR6, coexpression of CCR6 and CXCR3 or CCR4 on Th17 cells at baseline and month 6 of follow-up. Wilcoxon rank tests were performed and p values are indicated.
Figure 3.
Th17 cell frequency and Th17/Treg ratio negatively correlate with CD8 T-cell activation level and viral load at baseline.
Th17 cell frequency was assessed as described in legend to Figure 2. The frequency of Treg cells was defined as CD4+CD25+CD127lowFoxP3+ cells among CD4 T cells ex-vivo; cytokine secreting Tregs were assessed following 5 hrs PMA/ionomycin stimulation of isolated CD4+CD25+ T-cells and defined as FoxP3+ cells expressing IL-10 and/or TGF-β. CD8 T-cell activation was defined by the percentage of CD8 T cells coexpressing CD38 and HLA-DR or CD8 T cells expressing Ki-67. Viral load was expressed as plasma HIV-1 RNA log10 copies/mL or HIV-1 DNA log copies/106 PBMCs. The Th17 frequency (Panel A), and the Th17/Treg ratio (Panel B) were illustrated as a function of T-cell activation and viral load in PHI patients (n = 27) at baseline. The Th17/cytokine+ Treg ratio (Panel C) was plotted as a function of plasma and cell-associated viral load. Spearman's rank correlation coefficients ‘R’ and corresponding p values are indicated on each panel.
Figure 4.
sCD14 and IL-1RA are associated with T-cell activation and negatively correlate with the Th17/Treg ratio at baseline.
Baseline plasma levels of sCD14 (Panel A) and IL-1RA (Panel B) were plotted as a function of the Th17/Treg ratio and of T-cell activation in study patients (n = 27). CD8 T-cell activation was defined by the proportion of CD8 T cells coexpressing CD38 and HLA-DR or expressing Ki-67. CD4 T-cell activation was defined by the percentage of CD4 T cells expressing HLA-DR. Spearman's rank correlation coefficients ‘R’ and corresponding p values are indicated on each panel.
Figure 5.
Intestinal mucosal integrity and microbial translocation markers during primary HIV infection.
Plasma levels of I-FABP (Panel A) and plasma EndoCAb IgM levels (Panel B) were measured in PHI patients at baseline and month 6 and in healthy donors. Purple lines indicate patients receiving antiretroviral therapy between baseline and month 6; grey lines indicate untreated patients. Mann-Whitney tests were performed to compare patients and healthy donors, Wilcoxon rank tests was used to compared baseline and month 6 values in all patients; significant p values are indicated. (Panel C) Number of patients with detectable peptidoglycans in plasma using SLP reagents. (Panel D) Plasma levels of 16S ribosomal DNA in PHI patients at baseline (n = 27) and month 6 (n = 25), in untreated chronically HIV-infected patients (n = 20) as well as in patients with sepsis and blood culture positive for Staphylococcus aureus (n = 10).
Figure 6.
The Th17/Treg ratio and monocyte activation markers at baseline predict the T-cell activation set point.
Panels depict the relationships between the Th17/Treg ratio (Panel A), plasma levels of sCD14 (Panel B) or IL-1RA (C) at baseline and CD8 T cell activation at month 6. The T-cell activation set point was defined as the frequency of CD8 T cells co-expressing CD38 and HLA-DR or expressing Ki-67 at month 6. Spearman's rank correlation coefficients ‘R’ and corresponding p values are indicated on each panel.
Figure 7.
Proposed model of interrelationships between HIV, immune activation and the Th17/Treg ratio.
HIV induces monocyte and T-cell activation either directly (e.g. through TLRs) or indirectly, through innate and adaptive responses. The Th17 to Treg ratio decreases as Tregs expand in HIV infection and Th17 cells are one of the preferential targets of the virus. HIV can induce IDO expression by antigen-presenting cells which leads to tryptophan (Trp) catabolites accumulation that inhibit Th17 cells and induce Tregs. This further accentuates the decrease in the Th17/Treg ratio. In addition, IL-1RA secreted by activated monocytes could inhibit Th17 cell development. Then, in a later phase of infection – and not in acute infection – the loss of Th17 cells might contribute to microbial translocation that participates in chronic immune activation.