In HIV type 1-infected children cytotoxic T lymphocyte responses are associated with greater reduction of viremia under antiretroviral therapy.

The evolution of the HIV-specific CD8+ T cell response in patients receiving potent combination therapy has been well documented in adult patients. However, no study reported whether baseline HIV-specific CD8+ T cell response is linked to treatment outcome. The aims of this study were to investigate both the impact of baseline memory cytotoxic T lymphocytes (CTL) on treatment outcome and the effect of potent therapy on memory HIV-specific CTL in HIV-1-infected pediatric patients. The study group comprised 30 children who started a first-line combination treatment including at least three drugs from two different classes and were longitudinally followed during treatment. Their memory HIV-specific responses were measured at baseline and during treatment, as well as their plasma viremia and CD4+ levels. The intensity of memory Gag-specific CTL and the breadth of the CTL response at the beginning of treatment were significantly correlated with lower plasma viral load during treatment, independently of baseline plasma viral load, CD4+ counts, and age. Children with partially controlled viral replication had enhanced Gag-specific CTL compared to their baseline value. This improvement of antiviral responses during treatment was not observed when viral replication was either fully suppressed or uncontrolled. In conclusion, our results show that higher baseline HIV-specific CTL are linked to lower viremia under combination therapy. This result adds further support to the hypothesis that cooperation between the antiviral immune response and antiviral drugs could be helpful for therapeutic management of HIV-infected patients.

Arterial stiffness and endothelial dysfunction in HIV-infected children.

BACKGROUND: The role of antiretroviral therapy in acceleration of atherosclerosis in HIV-infected adults is controversial, partly because of the confounding effects of the involvement of classic cardiovascular risk factors. OBJECTIVE: To study vascular function in HIV-infected children. DESIGN: Cross-sectional study of 49 HIV-infected children (34 receiving antiretroviral therapy and 15 never treated) and if 24 age- and sex-matched controls. METHODS: Automatic, computerized, ultrasonic procedure evaluation of geometric and mechanical properties of the common carotid artery, and of the endothelium-dependent dilation and endothelium-independent dilation. RESULTS: Relative systolodiastolic variations in diameter of the carotid artery in HIV-infected children were significantly lower than those in controls, but there was no significant difference in intima-media thickness. Cross-sectional compliance and distensibility were also significantly lower. Wall stiffness, assessed as the incremental elastic modulus, was larger in HIV-infected children. Endothelium-dependent dilation was lower in HIV-infected children but non-endothelium-dependent dilation was similar to that in controls. We did not find differences for any of the vascular variables between HIV-infected children receiving antiretroviral therapy and those never treated. All arterial variables were similar in children with and without dyslipidemia. CONCLUSIONS: HIV-infected children had a vascular dysfunction in the absence of cardiovascular risk factors. In this short series, no additional detrimental effects were observed after a mean of 5 years of antiretroviral therapy.

Poor recognition of HIV-1 Nef protein by CD8 T cells from HIV-1-infected children: impact of age.

Recognition of various HIV proteins by CD8 T cells from HIV-infected children was determined by two functional assays. First, using an Elispot assay, we show that 80% of patients recognized Gag, 77% recognized Pol, 61% recognized Env, 44% recognized Nef and 29% recognized Vif. Frequencies of Gag-, Pol-, and Env-specific IFN-gamma producing CD8 T cells were higher than frequencies of Nef and Vif-specific CD8 T cells. The poor recognition of Nef by ex vivo CD8 T cells was confirmed by CTL assays performed in HAART naïve children: 25% of children had positive response against Nef versus 44, 63 and 62% for Env, Gag, and Pol, respectively. Memory Gag-specific CTL were positively correlated with age, whereas Nef-specific CTL were negatively correlated with age. The poor Nef-specific CD8 T cell response in HIV-infected children contrasts with dominance of Nef-specific responses in infected adults.

Not all tetramer binding CD8+ T cells can produce cytokines and chemokines involved in the effector functions of virus-specific CD8+ T lymphocytes in HIV-1 infected children.

In the pediatric human immunodeficiency virus type-1 (HIV-1) infection, the presence of cytotoxic T lymphocytes (CTL) is associated with a slow progression to AIDS. The secretion of cytokines by CTLs may be critical in the control of viral infection. We used the combination of cell surface and intracellular staining to study the functionality of tetramer binding CD8+ T cells recognizing two HIV-1 immunodominant epitopes, in peripheral blood mononuclear cells from HIV-1-infected children. A fraction of tetramer positive CD8+ T cells produce cytokines (IFN-gamma, TNF-alpha) or chemokines (CCL4, CCL5) after ex vivo stimulation with the cognate peptide. There was a negative correlation between the plasma viral load and the percentage of CD8+ Tetramer Gag+ T cells secreting IFN-gamma. This is the first report in the context of pediatric HIV-1 infection showing that only a fraction of HIV-1-specific CD8+ T cells have the capacity to produce cytokines and chemokines implicated in their antiviral functions.

Longitudinal evaluation and risk factors of lipodystrophy and associated metabolic changes in HIV-infected children.

OBJECTIVE: To assess the rate of progression of lipodystrophy and the associated metabolic disturbances over a 2-year period in children and to assess risk factors associated with lipodystrophy and metabolic disturbances. DESIGN: Multicenter 2-year prospective study with a standardized evaluation. METHODS: One hundred thirty children (median age = 10 years, 64 boys and 66 girls) receiving antiretroviral therapy were recruited in 3 pediatric clinics. Lipodystrophy was defined based on 4 skinfold thickness measurements. Fasting lipids and glucose profile were measured in all children. RESULTS: The proportion of children presenting with lipodystrophy was 24.6%. Nineteen percent of children had high-density lipoprotein values less than 1 mmol/L. Twenty-two percent and 15% of children had values greater than 2 standard deviations for age and gender for cholesterol and triglycerides, respectively. A total of 13.2% showed insulin resistance. A total of 42.7% showed at least 1 of these biologic disturbances. Prospective follow-up showed no progression at all over 2 years, except for a doubling of the number of children with insulin resistance. In multivariate analyses, ethnicity, previous severe clinical condition, duration of HIV infection, and nucleoside reverse transcriptase inhibitor treatment were significantly associated with lipodystrophy. Tanner stage V of puberty, severe clinical symptoms and protease inhibitor treatment were independently associated with the risk of metabolic disturbances. CONCLUSIONS: Puberty seems to be the time when HIV-infected children taking potent antiretroviral therapy are more likely to develop lipodystrophy and metabolic complications, especially in children with a severe underlying HIV infection. Once developed, lipodystrophy and metabolic changes seem to be extremely stable with time.

Frequencies of ex vivo-activated human immunodeficiency virus type 1-specific gamma-interferon-producing CD8+ T cells in infected children correlate positively with plasma viral load.

HIV-specific CD8+ T cells are critical in controlling human immunodeficiency virus (HIV) replication. We present the evaluation of a gamma-interferon (IFN-gamma)-based enzyme linked immunospot (ELISPOT) assay for the quantification of HIV-specific CD8+ T cells from HIV-infected children. We studied 20 HLA-A*0201-positive HIV-infected children. The IFN-gamma production in response to stimulation with two HLA-A*0201-restricted immunodominant CD8 epitopes (SLYNTVATL [SL9] in Gag and ILKEPVHGV [IV9] in Pol) was tested using the ELISPOT assay. The results were compared to labeling with the corresponding tetramers. Among the 20 children, 18 had detectable responses against the SL9 and/or the IV9 epitope using the ELISPOT assay (medians, 351 and 134 spot-forming cells/10(6) peripheral blood mononuclear cells, respectively). Comparison of results from the tetramer and ELISPOT assays suggests that only a fraction of HIV-specific CD8+ T cells were able to produce IFN-gamma. Most importantly, we found that the frequencies of IFN-gamma-producing CD8+ T cells were positively correlated with the viral load whereas the frequencies of tetramer-binding CD8+ T cells were not. The high sensitivity of the ELISPOT assay and the fact that this functional assay provided information different from that of tetramer labeling support its use for measurement of HIV-specific CD8+ T cells. In conclusion, our results show that the ex vivo-activated IFN-gamma-producing HIV-specific CD8+ T-cell subset is dependent upon continuous antigenic stimulation.