Highly active antiretroviral therapy in patients infected with human immunodeficiency virus increases CD40 ligand expression and IL-12 production in cells ex vivo

Abstract

Highly active anti-retroviral therapy (HAART) restores CD4(+) T-cell numbers in the periphery; however, its efficacy in restoring functional immunity is not fully elucidated. Here we evaluated longitudinal changes in the expression of several key markers of T-cell activation, namely CD40 ligand (CD154), OX40 (CD134), or CD69, after anti-CD3/CD28 activation, as well as levels of IL-12 production after Staphylococcus aureus Cowan stimulation in 28 HIV-infected adult patients. Patients were followed up to 12 mo post-HAART initiation. Viral burdens and CD4 cell counts were measured at the same time points. A control group of 15 HIV-uninfected adult subjects was included for comparison. Significant increases in CD40L and OX40 expression, but not of CD69 expression, were observed over time in the overall patient population, and more particularly in patients with baseline CD4 counts lower than or equal to 200 cells/μL, or those with baseline viral loads lower than or equal to 10(5) RNA copies/mL. Similar increases were seen for IL-12 production. Viral loads were inversely associated with CD40L expression or IL-12 production in a mixed linear model analysis, while CD4 counts were directly associated. CD40L expression and IL-12 production were significantly correlated. In conclusion, HAART-mediated control of viral replication led to partial restoration of CD40L upregulation/expression, and to increased IL-12 production, but the magnitude of the response depended on the baseline characteristics of the treated patients.

FIG. 1.

Induction of T-cell activation markers increased following antiretroviral therapy. Changes in viral loads (A), CD4 counts (B), induced CD40L expression (C), induced CD69 expression (D), and induced OX40 expression (E) in all patients at baseline, 3 mo, 6 mo, and 12 months of HAART initiation. Slope (b) and significance (p) are shown for each analysis. T-cell activation markers (CD40L, CD69, and OX40) were measured by surface flow cytometry analysis after 24 h of TCR-induced T-cell stimulation using anti-CD3/28 coated beads. Results were expressed as percentages of CD4⁺ T cells expressing each T-cell activation marker.

FIG. 2.

HAART-induced increases in T-cell activation makers vary depending on patient baseline CD4 counts or viral loads. CD40L, OX40, and CD69 expression for each patient are shown at various time points following HAART initiation. Slope (b) and significance (p) are shown for each analysis. Results are shown as percentages of CD4⁺ T cells expressing each marker. Top panels (A, B, and C) show stratification according to baseline CD4 counts. Plots show variation in CD40L (A), CD69 (B), and OX40 (C) expression, when HIV patients were stratified according to baseline CD4 counts. CD4_H (blue lines) signifies high baseline CD4 counts (>200/μL), and CD4_L (red lines) signifies low baseline CD4 counts (≤200/μL). Bottom panels (D, E, and F) show stratification according to baseline VL. Similar plots show variations in CD40L (D), CD69 (E), and OX40 (F) expression when HIV patients were stratified according to baseline VL. VL_L (blue lines) signifies low baseline VL (<100,000 copies/mL), and VL_H (red lines) signifies high baseline VL (≥100,000 copies/mL). Color images available online at www.liebertonline.com/vim

FIG. 3.

IL-12 production increases in HAART-treated patients. IL-12 production was measured in supernatants of 24-h SAC-stimulated PBMCs. Log transformed levels are shown for each patient. Slope (b) and significance (p) are shown for each analysis. (A) Overall population. (B) Stratification according to baseline CD4 counts. CD4_H (blue lines) signifies high baseline CD4 counts (>200/μL). CD4_L (red lines) signifies low baseline CD4 counts (≤200/μL). (C) Stratification according to baseline VL. VL_L (blue lines) signifies low baseline VL (<100,000 copies/mL). VL_H (red lines) signifies high baseline VL (≥100,000 copies/mL). Color images available online at www.liebertonline.com/vim