Osvalda Rampon

Immune reconstitution in human immunodeficiency virus type 1-infected children with different virological responses to anti-retroviral therapy

Immune repopulation, despite virological failure, often occurs in children under highly active anti‐retroviral therapy (HAART). The aim of this study was to analyse the characteristics of immune repopulation and activation in children with and without virological response to HAART. Fourteen human immunodeficiency virus type 1 (HIV‐1)‐infected children with suppression of HIV‐1 plasma viraemia (virological responders, VR) and 16 virological non‐responders (VNR) to therapy were studied at baseline and after approximately 2 years of HAART. During therapy, CD4+ T cells increased in both groups, but were higher in the VR than in the VNR group. All CD4+ T cell subsets (naive, central memory, effector/memory and CD38+) increased significantly in VR children, while there was a significant increase only in naive cells in VNR children. Naive CD8+ T cells and T cell receptor rearrangement excision circles (TREC), an indicator of thymic output, increased in both VR and VNR children. Activated CD8+CD38+ T cells decreased in VR but remained high in VNR children. Levels of circulating lipopolysaccharide (LPS), an indicator of microbial translocation, further increased in VNR children. In conclusion, HAART induced an increase in naive cells in all children, regardless of their virological response. However, the persistence of viraemia resulted in an impaired expansion of memory CD4+ T cells susceptible to HIV‐1 infection, and together with the microbial translocation sustained the persistence of a high level of immune activation.

Rapid disease progression in HIV-1 perinatally infected children born to mothers receiving zidovudine monotherapy during pregnancy The Italian Register for HIV Infection in Children*

OBJECTIVE To investigate the outcome in children perinatally infected with HIV-1 whose mothers received zidovudine (ZDV) monotherapy in pregnancy. DESIGN Observational retrospective study of a prospectively recruited cohort. SETTING Italian Register for HIV Infection in Children. PATIENTS A group of 216 children perinatally infected with HIV-1, born in 1992-1997 and derived prospectively from birth: 38 children had mothers receiving ZDV monotherapy and for 178 children the mothers received no antiretroviral treatment during pregnancy. MAIN OUTCOME MEASURES The estimated probability of developing severe disease or severe immune suppression, survival probability [95% confidence interval (CI)] within 3 years, and the hazard ratio (95% CI), adjusted for year of birth, maternal clinical condition at delivery, birthweight and treatments (Pneumocystis carinii pneumonia chemoprophylaxis and/or antiretroviral therapy before the onset of severe disease, severe immune suppression or death) were compared. RESULTS Comparison of HIV-1-infected children whose mothers were treated with ZDV with children whose mothers were not treated showed that the former group had a higher probability of developing severe disease [57.3% (95% CI 40.9-74.3) versus 37.2% (95% CI 30.0-45.4); log-rank test 7.83, P = 0.005; adjusted hazard ratio 1.8 (95% CI 1.1-3.1)] or severe immune suppression [53.9% (95% CI 36.3-73.5) versus 37.5% (95% CI 30.0-46.2); log-rank test 5.58, P = 0.018; adjusted hazard ratio 2.4, (95% CI: 1.3-4.3)] and a lower survival [72.2% (95% CI 50.4-85.7) versus 81.0% (95% CI 73.7-86.5); log-rank test 4.23, P = 0.039; adjusted hazard ratio of death 1.9 (95% CI 1.1-3.6)]. CONCLUSIONS This epidemiological observation could stimulate virologic studies to elucidate whether this rapid progression depends on in utero infection or transmission of resistant virus. Findings may suggest a need to hasten HIV-1 diagnosis in infants of ZDV-treated mothers and undertake an aggressive antiretroviral therapy in those found to be infected.

Polymorphisms in the CCR5 Promoter Region Influence Disease Progression in Perinatally Human Immunodeficiency Virus Type 1–Infected Children

The effect of CC-chemokine receptor 5 (CCR5) promoter polymorphisms on the natural history of human immunodeficiency virus (HIV) disease was studied in 73 HIV-1-infected children. The CCR5(59338-59537) promoter haplotype, CCR5-59029A/G polymorphism, and CCR5Delta32 and CCR2-64I alterations were investigated. After exclusion of carriers of CCR5Delta32 or CCR2-64I, Kaplan-Meier analysis disclosed that children with the P1/P1(59353C,59356C,59402A) genotype progressed faster to disease than did children with other haplotypes (P=.016). When CCR2-64I carriers were included, this effect had borderline significance (P=.065) and was lost when CCR5Delta32 carriers were also considered (P=.387). The P1/P1 effect was strongest early after infection, when progression to disease was mainly associated with CCR5 coreceptor-using viruses. These results indicate that the P1/P1 genotype is predictive of rapid progression in HIV-1-infected children lacking CCR5Delta32 or CCR5-64I alleles. The observation of a linkage disequilibrium between P1 and 59029A might explain the previously reported association between 59029A homozygosity and rapid disease progression.

Long-term decay of the HIV-1 reservoir in HIV-1-infected children treated with highly active antiretroviral therapy.

To investigate the decay of the human immunodeficiency virus type 1 (HIV-1) reservoir in children receiving highly active antiretroviral therapy (HAART), we measured HIV-1 DNA in peripheral blood mononuclear cells from 14 children who achieved and maintained suppression of plasma viremia up to 48 months after the initiation of HAART. Levels of intracellular unspliced and multiply spliced HIV-1 RNA were used as markers of residual viral replication. During the first month of HAART, there were significant decays in levels of both plasma HIV-1 RNA and multiply spliced HIV-1 RNA, yet unspliced HIV-1 RNA persisted in most of the children. Greater HIV-1 DNA decay during the first month of HAART correlated with a higher concomitant increase in CD4(+) cell counts (P=.028) and a smaller subsequent HIV-1 DNA decay (P=.0012). Furthermore, HIV-1 DNA decayed faster from 1 to 9 months of HAART (median half-life, 5 months) than during the subsequent follow-up period (median half-life, 30 months). Moreover, after 9 months of HAART, HIV-1 DNA tended to decay more slowly in children with detectable levels of unspliced HIV-1 RNA. These findings suggest that clearance of the viral reservoir in HAART-treated children may be influenced by immune repopulation and residual viral replication and may help in refining long-term treatment strategies.

Current and future antiretroviral treatment options in paediatric HIV infection.

Because of a lack of prevention policies or problems in implementing prevention of mother-to-child transmission (P-MTCT), most of the 1500 daily new HIV infections in children aged <15 years are caused by MTCT. Fifteen percent of all HIV-infected individuals are children, but the vast majority lack access to highly active antiretroviral therapy (HAART), which can drastically reduce morbidity and mortality. There are 22 antiretroviral drugs currently approved by the US FDA for use in the treatment of HIV-infected adults and adolescents, but only 12 of these drugs are approved for use in children. Antiretroviral drugs belong to four major classes: nucleoside and nucleotide analogue reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors and fusion inhibitors. According to international guidelines developed by organizations including WHO, the Paediatric European Network for Treatment of AIDS (PENTA) and the US National Institutes of Health (US-NIH), the treatment of choice for HIV-infected children and adults is a combination of two NRTIs (backbone treatment) plus a third potent agent from a different class, either an NNRTI or a ritonavir-boosted protease inhibitor. There are specific challenges in treating HIV-infected children, including uncertainty about the best time to start treatment, the need for more paediatric formulations, the lack of pharmacokinetic studies for new drugs, and incomplete dosing guidelines. Furthermore, the most appropriate regimen for an individual child depends on a variety of factors, including the age of the child; the availability of appropriate drug formulations; the potency, complexity and toxicity of the drug regimen; the home situation; the child and caregiver’s ability to adhere to the regimen; and the child’s antiretroviral treatment history. In addition, antiretroviral drugs are not licensed for all age groups and the drugs are often not affordable. This review describes NNRTI and protease inhibitors as key components of first- and second-line antiretroviral therapy (ART), focusing on the rationale for choosing an NNRTI-versus protease inhibitor-based regimen based on the results of available phase II and III studies. Some of the new agents available for children as second-line and salvage therapy both on- and off-label are also discussed. The drug regimens described in this review are relevant to clinicians in developed and developing countries. The availability of new, potent compounds with different resistance and toxicity profiles may represent an alternative option to interclass switching and could redefine ART strategy, including the option of first-line NRTI-sparing regimens.

Age related standards for total lymphocyte, CD4+ and CD8+ T cell counts in children born in Europe

Objective: Currently used reference values for immunologic markers in children are largely derived from cross-sectional data from historic, small sample size studies in predominantly white children. There is a lack of reliable age-related standards for immunologic markers, such as CD4+ cell counts, in particular in black children whose values according to recent reports may differ from those in white children. Standards are essential for diagnosing and monitoring childhood diseases such as pediatric human immunodeficiency virus (HIV) infection. Design: Prospective cohort study with data on 1781 uninfected children born to HIV-infected mothers in the European Collaborative Study. Methods: Age-related standards (centiles) for immunologic markers (CD4+ and CD8+ cell counts and total lymphocyte counts) up to 5 years in black and up to 10 years in white children were constructed using Generalized Additive Models for Location, Scale and Shape method, which allows for variability and skewness of the data. The optimal model was chosen according to the Akaike Information Criterion. Results: Patterns and values of total lymphocyte, CD4+ and CD8+ cell counts varied with age, especially in the first 3 years of life, but less so thereafter. Values of all 3 immunologic markers were substantially and significantly lower in black than in white children of the same age. Conclusions: We present age-related standards separately for black and white children to aid clinicians in the monitoring of childhood diseases. These standards may also contribute to the decision on an accurate cutoff for CD4+ cell counts for initiating treatment of HIV-infected children.

Regulatory T cells and chronic immune activation in human immunodeficiency virus 1 (HIV‐1)‐infected children

The function of CD4+ T cells with regulatory activity (Tregs) is the down‐regulation of immune responses. This suppressive activity may limit the magnitude of effector responses, resulting in failure to control human immunodeficiency virus 1 (HIV‐1) infection, but may also suppress chronic immune activation, a characteristic feature of HIV‐1 disease. We evaluated the correlation between viral load, immune activation and Tregs in HIV‐1‐infected children. Eighty‐nine HIV‐1‐infected children (aged 6–14 years) were included in the study and analysed for HIV‐1 plasmaviraemia, HIV‐1 DNA load, CD4 and CD8 cell subsets. Treg cells [CD4+ CD25highCD127lowforkhead box P3 (FoxP3high)] and CD8‐activated T cells (CD8+CD38+) were determined by flow cytometry. Results showed that the number of activated CD8+CD38+ T cells increased in relation to HIV‐1 RNA plasmaviraemia (r = 0·403, P < 0·0001). The proportion of Tregs also correlated positively with HIV‐1 plasmaviraemia (r = 0·323, P = 0·002), but correlated inversely with CD4+ cells (r = −0·312, P = 0·004), thus suggesting a selective expansion along with increased viraemia and CD4+ depletion. Interestingly, a positive correlation was found between the levels of Tregs and CD8+CD38+ T cells (r = 0·305, P = 0·005), and the percentage of Tregs tended to correlate with HIV‐1 DNA load (r = 0·224, P = 0·062). Overall, these findings suggest that immune activation contributes to the expansion of Treg cells. In turn, the suppressive activity of Tregs may impair effector responses against HIV‐1, but appears to be ineffective in limiting immune activation.

Cancer Rates After Year 2000 Significantly Decrease in Children With Perinatal HIV Infection: A Study by the Italian Register for HIV Infection in Children

PURPOSE To evaluate the impact of highly active antiretroviral therapy (HAART) on cancer incidence in HIV-infected children throughout a 20-year period. PATIENTS AND METHODS An observational population study was conducted on 1,190 perinatally HIV-infected children enrolled onto the Italian Register for HIV Infection in Children from 1985 to 2004 and never lost to follow-up (total observation time, 10,037.66 years). Cancer rates were calculated in the pre-HAART (1985 to 1995), early HAART (1996 to 1999), and late HAART (2000 to 2004) periods and compared using Poisson regression adjusted for age. The proportion of HAART-treated children increased from 4.1% in 1996 to 60.4% in 1999 and to 81.5% in 2004. In the same time frame, the proportion of children receiving HAART for at least 2 years increased from 3.1% to 77.0%. RESULTS Overall, 35 cancers occurred. Cancer rates were 4.49 (95% CI, 2.37 to 6.64), 4.09 (95% CI, 1.68 to 6.50), and 0.76 (95% CI, 0.00 to 1.80) per 1,000 children per year in 1985 to 1995, 1996 to 1999, and 2000 to 2004, respectively. Notably, there was no significant difference comparing the periods from 1985 to 1995 and 1996 to 1999 (P = .081). By contrast, cancer rates were significantly lower in the period from 2000 to 2004 than in 1996 to 1999 (P < .0001). Results were confirmed by separately analyzing data from children observed from birth (P = .418 for 1985 to 1995 v 1996 to 1999; P = .001 for 1996 to 1999 v 2000 to 2004). CONCLUSION Dramatically reduced cancer rates were observed only in the late HAART period in parallel to the increasing proportion of children receiving HAART therapy.

Premature aging and immune senescence in HIV-infected children.

Objective:Several pieces of evidence indicate that HIV-infected adults undergo premature aging. The effect of HIV and antiretroviral therapy (ART) exposure on the aging process of HIV-infected children may be more deleterious since their immune system coevolves from birth with HIV. Design:Seventy-one HIV-infected (HIV+), 65 HIV-exposed-uninfected (HEU), and 56 HIV-unexposed-uninfected (HUU) children, all aged 0–5 years, were studied for biological aging and immune senescence. Methods:Telomere length and T-cell receptor rearrangement excision circle levels were quantified in peripheral blood cells by real-time PCR. CD4+ and CD8+ cells were analysed for differentiation, senescence, and activation/exhaustion markers by flow cytometry. Results:Telomere lengths were significantly shorter in HIV+ than in HEU and HUU children (overall, P < 0.001 adjusted for age); HIV+ ART-naive (42%) children had shorter telomere length compared with children on ART (P = 0.003 adjusted for age). T-cell receptor rearrangement excision circle levels and CD8+ recent thymic emigrant cells (CD45RA+CD31+) were significantly lower in the HIV+ than in control groups (overall, P = 0.025 and P = 0.005, respectively). Percentages of senescent (CD28−CD57+), activated (CD38+HLA-DR+), and exhausted (PD1+) CD8+ cells were significantly higher in HIV+ than in HEU and HUU children (P = 0.004, P < 0.001, and P < 0.001, respectively). Within the CD4+ cell subset, the percentage of senescent cells did not differ between HIV+ and controls, but programmed cell death receptor-1 expression was upregulated in the former. Conclusions:HIV-infected children exhibit premature biological aging with accelerated immune senescence, which particularly affects the CD8+ cell subset. HIV infection per se seems to influence the aging process, rather than exposure to ART for prophylaxis or treatment.

Antiretroviral therapy for prevention of mother-to-child HIV transmission : focus on single-dose nevirapine.

Administration of potent antiretroviral combination therapy in the second and third trimester of pregnancy and during delivery, and for 6 weeks postpartum to the infant, may reduce HIV transmission from the mother to the child to <2% in formula-fed infants. In resource-constrained settings where women have limited access to antenatal care, use of shorter and more practical regimens, including nucleoside reverse transcriptase inhibitors (NRTIs) and/or non-NRTIs (NNRTIs) commenced later in pregnancy, has demonstrated efficacies ranging from 18% to 70% in breast- and bottle-fed populations. Because shorter interventions include regimens such as single-dose nevirapine or zidovudine monotherapy, which do not provide maximal suppression of viral replication, emergence of resistant mutations in mother and infant occurs frequently, primarily after exposure to drugs with low genetic barriers (i.e. those requiring only one genotypic mutation to develop resistance), such as nevirapine.Different studies have reported nevirapine resistance rates ranging from 25% to 69% in mothers receiving single-dose nevirapine alone. Because NNRTI-based combinations of antiretroviral agents are recommended as first-line therapy in countries where single-dose nevirapine is the main option for preventing mother-to-child transmission of HIV, concerns have been raised as to whether single-dose nevirapine prophylaxis can compromise the efficacy of subsequent NNRTI-based antiretroviral therapy regimens. However, although some studies have shown that nevirapine exposure may impact on short-term virological outcome, the clinical relevance of nevirapine resistance remains unclear, especially in women who start treatment >6 months after delivery or in those who are not severely immunocompromised. Furthermore, studies have shown that adding short-course (up to 7 days) zidovudine or zidovudine/lamivudine prophylaxis after delivery may dramatically reduce the occurrence of nevirapine resistance in both mothers and infants.Until data are available that allow a better understanding of the relevance of antiretroviral drug resistance acquired as a result of mother-to-child HIV transmission prophylaxis, women and children who have previously received single-dose nevirapine as part of a mother-to-child transmission prevention strategy should be considered eligible for NNRTI-based regimens and should not be denied access to antiretroviral therapy.