Relationship of virologic, immunologic, and clinical parameters in infants with vertically acquired human immunodeficiency virus type 1 infection

Intra-host dynamics and co-receptor usage of HIV-1 quasi-species in vertically infected patients with phenotypic switch

HIV-1 infection through vertical transmission provides a good model to evaluate intra-host viral evolution and allows to gain insight into the dynamics of viral populations. Our aim was to assess the diversity and dynamics of X4- and R5-using HIV-1 variants in vertically infected children who presented a switch in SI/ NSI phenotype in MT-2 cell assays during chronic infection. Through molecular cloning and next generation sequencing of the C2-V5 env fragment, we investigated HIV-1 evolution and co-receptor usage based on V3 loop prediction bioinformatic tools of longitudinal samples obtained from 4 children. In all cases, the phylogenetic relationships were assessed by Maximum-Likelihood trees constructed with MEGA 6.0. In two cases, V3 loop sequences predicted exclusively R5-using and or X4-using strains, while in another two a higher degree of concordance was observed between the phenotypic and genotypic characteristics. In 3 of the 4 cases, C2-V5 env sequences from different time points were intermingled in phylogenetic trees, with no segregation neither by time or tropism. In only one case monophyletic clustering defined groups of sequences with different co-receptor usage. Comparison of amino acid frequency between isolates with SI and NSI phenotype allowed the identification of 9 possible genetic determinants in subtype F C2-V5 region of env associated to SI/ NSI phenotype in these patients, one of which had previously been reported for subtype B. Overall, we found a low degree of correlation between phenotypic and genotypic properties of HIV-1 quasispecies in patients under chronic infection. Whether HIV-1 subtype or other factors influence the evolution of HIV-1 in vivo will require further research.

Relevance of early detection of HIV type 1 SI/CXCR4-using viruses in vertically infected children

The aim of the study was to investigate the prevalence and persistence of syncytium-inducing (SI) strains in HIV-1-infected children along time of infection and to evaluate the influence of antiretroviral therapy and host factors on viral tropism. This is a retrospective analysis carried out in 267 HIV-1 vertically infected children from an Argentinean cohort. The viral phenotype was screened in MT-2 cells and coreceptor usage confirmed by the GHOST cell assay. Also, CD4(+) T cell count, viral load, antiretroviral therapy, and human CCR5-Δ32 and CCR2-64I genotypes were analyzed. A high frequency of HIV-1 SI/CXCR4-using variants (22%) was found among children within the first trimester of life, reaching 46% after 10 years of infection. At acute infection, zidovudine prophylaxis did not significantly affect the proportions of SI HIV-1 strains, while their presence was favored by the CCR5(+)/Δ32 genotype. Interestingly, the majority of the early SI strains did not persist over time, probably due to a higher susceptibility to antiretroviral (ARV) treatment or immunologic pressure. At the chronic stage, SI variants emerged even in the presence of HAART reaching 36% at 120 months of infection. Also the HIV-1 SI phenotype was associated with lower CD4(+) T cell counts all along the course of infection. These findings highlight the need to evaluate the presence of SI/CXCR4 variants early at primary infection. This will make it possible to optimize the use of CCR5 inhibitors in children who are apparently carriers of the R5 virus preventing early therapeutic failure due to the reemergence of SI strains from reservoirs.

Functional patterns of HIV-1-specific CD4 T-cell responses in children are influenced by the extent of virus suppression and exposure

BACKGROUND

Virus-specific CD4 T cells play a critical role in antiviral immunity. HIV-1-specific CD4 T cells in chronically infected adults are mostly composed of IFN-gamma-secreting cells, whereas a selective defect in IL-2-secreting CD4 T cells has been demonstrated. HIV-1-specific IL-2-secreting CD4 T cells are key components of effective immunity.

OBJECTIVE

To determine the function of HIV-1-specific CD4 T cells in HIV-1 vertically infected children after antiretroviral treatment (ART).

DESIGN

Twenty-three vertically HIV-infected children treated with ART for an extended period (mean 7 years) were retrospectively studied.

METHODS

The function of HIV-1-specific CD4 T cells was determined by their ability to secrete IL-2 and IFN-gamma after stimulation with HIV-1 p55 gag protein using polychromatic flow cytometry.

RESULTS

: Substantial differences in the patterns of CD4 T-cell responses were associated with different conditions of response to ART. Interestingly, children with suppression of viraemia below 50 HIV-1-RNA copies/ml of plasma for at least 2 years showed dominant IL-2 CD4 T-cell responses; children with viraemia below 50 copies but experiencing transient blips of viraemia showed polyfunctional (IL-2 plus IFN-gamma) CD4 T-cell responses; children with uncontrolled high viraemia levels had dominant IFN-gamma CD4 T-cell responses. Furthermore, the total frequency of HIV-1-specific CD4 T cells including IL-2 and IFN-gamma-secreting cells was significantly higher compared with HIV-infected adults with chronic infection.

CONCLUSION

The higher frequency of HIV-1-specific CD4 T cells in children compared with adults and the recovery of IL-2-secreting CD4 T cells after successful ART-mediated suppression of virus replication indicate a greater capacity of immune restoration in children than adults.

CD4(+) T-cell immunodeficiency is more dependent on immune activation than viral load in HIV-infected children on highly active antiretroviral therapy

OBJECTIVE

The aim of this study was to analyze the association between CD4(+) depletion and immune activation in HIV-1-infected children on highly active antiretroviral therapy (HAART).

DESIGN AND SETTING

We carried out a cross-sectional study to determine the profile of several immunologic parameters in 143 children on HAART for more than 24 weeks. Children were stratified according to current immunologic status (CD4 < or =15%, 15%-25%, and > or =25%) and viral load (VL) levels (<400 copies/mL; 400-10,000 copies/mL; and >10,000 copies/mL). We also studied 23 uninfected children as healthy controls.

METHODS

Viral load (HIV-RNA copies per milliliter) was quantified using reverse transcriptase polymerase chain reaction molecular assay. T-cell subsets were determined by multiparametric flow cytometry.

RESULTS

HIV-infected children with low percentage of CD4(+) had high memory (CD45RO(+)) and low naive (CD45RA(+)) CD4(+) and CD8(+) T-cell values. Furthermore, children with CD4(+) >25% had similar memory and naive CD4(+) values as the healthy control group, whereas memory and naive CD8(+) subsets were different from the healthy control values. In these HIV-infected children, when CD4(+) was depleted, the amount of naive plus central memory CD8(+) (CD28(+)CD57(-)) cells was decreased, whereas effector CD8(+) (CD28(-)CD57(+)) cells were upregulated, and these values were always higher than healthy control values. Furthermore, children with low percentage of CD4(+) showed significant upregulation of HLA-DR(+)CD38(+) and HLA-DR(+) in both CD4(+) and CD8(+) T-cells independent of VL levels.

CONCLUSIONS

Our data suggest that elevated immune activation could be responsible for CD4(+) depletion rather than HIV replication because immunologic status is associated directly to immune activation and not to VL levels in HIV-infected children on HAART.

Clinical Outcomes Improve with Highly Active Antiretroviral Therapy in Vertically HIV Type‐1–Infected Children

Background. Use of antiretroviral therapy has resulted in a decrease in morbidity and mortality rates in human immunodeficiency virus type 1 (HIV-1)-infected children.Methods. We performed a retrospective study involving 427 children to determine the effectiveness of different antiretroviral therapy protocols on clinical outcome. The follow-up period was divided into 5 calendar periods (CPs): CP1 (1980-1989), before antiretroviral therapy was administered; CP2 (1990-1993), when monotherapy was administered; CP3 (1994-1996), when combined therapy was administered; CP4 (1997-1998), when </=50% of children were receiving highly active antiretroviral therapy (HAART); and CP5 (1999-2003), when >/=60% of children were receiving HAART.Results. Children experienced a progressive increase in the CD4(+) cell count and decrease in the viral load from 1997 onwards. A lower number of AIDS cases and deaths occurred during CP5 than during the other CPs (P<.01), with a relative risk of an absence of AIDS of >20 and a relative risk of survival of >30. The AIDS rate was >50% in CP1; we observed a very strong decrease to 14% in CP2, to 16% in CP3, to 7% in CP4, and to 2% in CP5. The mortality rates in CP2 and CP3 were >6% and thereafter decreased to 0.5% in CP5. The relative risks for no hospital admission in CP4 and CP5 were >3.5. The total rates of hospital admission in CP1, CP2, and CP3 were >30%; we observed a decrease in CP4 and CP5. The duration of hospitalization decreased during the follow-up period, and it was higher in CP1 (~30 days) than in the other periods.Conclusions. We observed that HAART produces a decrease in adverse clinical outcomes (i.e., hospital admission, AIDS, and death) in children with vertical HIV-1 infection in Madrid, Spain.

HIV-1 infection of neurons might account for progressive HIV-1-associated encephalopathy in children

Direct and productive infection of neurons in vivo is still a matter of debate, although in vitro experiments have demonstrated that immature neuronal cells can be productively infected by various human immunodeficiency virus (HIV) strains. To address this controversy we have analyzed, using light microscopy and in situ hybridization (ISH), HIV-1 infected cells in brain tissue from four pediatric cases of HIV-1-associated encephalopathy (EP). HIV-1 RNA-expressing cells--therefore, actively infected cells--were detected by ISH in different amounts in all brain specimens from the four children. They mainly correspond to glial cells. However, in two of the four children, who had severe progressive EP, but not in the other two, who had the static form, HIV-1-infected neurons were clearly observed in the cortical brain samples. These results provide initial evidence that HIV-1 can actively infect neurons in vivo in children and show a cortical involvement of HIV brain infection in clear correlation with the clinical EP symptoms.

Role of antiretroviral therapies in mucocutaneous manifestations in HIV-infected children over a period of two decades

BACKGROUND

Human immunodeficiency virus (HIV) infection causes a severe cellular immunodeficiency, which results in a greater susceptibility to infectious, inflammatory and malignant conditions. Among these, pathologies of the skin seem to be those most frequently observed in HIV+ patients. However, there are few reports on how antiretroviral therapy affects skin disorders in HIV-infected children.

OBJECTIVE

To study the incidence and prevalence of skin disorders in a cohort of HIV-infected children, in relation to the antiviral therapy [nontreated, monotherapy, combined therapy and highly active antiretroviral therapy (HAART)] received, and their impact on immunological and virological markers. The treatments were those available in different calendar periods in the history of antiviral treatment.

MATERIALS AND METHODS

A retrospective, observational study in a cohort of 210 HIV-infected children was carried out. These children were followed up every 3 months throughout 22 years. The viral load (HIV RNA copies mL(-1)) was quantified using reverse transcriptase-polymerase chain reaction and the viral phenotype of HIV-1 isolates was determined by in vitro culture. T-lymphocyte subsets in peripheral blood were quantified by flow cytometry.

RESULTS

Mucocutaneous manifestations were diagnosed in 17% of the untreated infected children. Of the treated children in different treatment periods, 22% in the monotherapy period, 25% in the combined therapy period but only 10% on HAART had some type of mucocutaneous manifestation, concordant with a higher number of CD4+ T cells, a lower viral load and less cytopathic virus in the last group. Mucocutaneous manifestations of infectious aetiology were most frequently observed; they were detected in 13% of the children during the first calendar period (untreated children), 16% during the second and third periods (monotherapy and combined therapy) and only 5% in the last period (HAART). Interestingly, syncytium-inducing virus was present in 69% of all children with mucocutaneous manifestations of infectious aetiology.

CONCLUSION

Only in the last calendar period (HAART) was a significant decrease observed in the prevalence of mucocutaneous manifestations with HIV infection associated with an increase in CD4+ T cells. In addition, we found a strong association between children who had mucocutaneous manifestations with an infectious aetiology and a more cytopathic (X4/SI) viral phenotype.

Immunological changes after highly active antiretroviral therapy with lopinavir-ritonavir in heavily pretreated HIV-infected children

We evaluated the effect of salvage antiretroviral therapy with lopinavir/ritonavir (LPV/r) on the immune system of heavily antiretroviral pretreated HIV-infected children. We carried out a longitudinal study in 20 antiretroviral experienced HIV-infected children to determine the changes in several immunological parameters (T cell subsets, thymic function) every 3 months during 18 months of follow-up on salvage therapy with LPV/r. Statistical analyses were performed with the Wilcoxon test, taking as a reference the basal value at the entry in the study. HIV-infected children showed an increase of CD4+ T cells, a decrease in CD8+ T cells, and an increase in T cell rearrangement excision circle (TRECs) levels. The percentage of HIV children with undetectable viral load (VL < or = 400 copies/ml) increased significantly (p = 0.007) and the percentage with SI viral phenotype decreased significantly (p = 0.002) at the end of the study. Thus, the viral phenotype changed to NSI/R5 after salvage therapy with LPV/r. Interestingly, we observed a significant decrease of memory (CD4+ CD45RO+) and a moderate decrease of activated (CD4+ HLA-DR+, CD4+ HLA-DR+CD38, CD4+, CD45RO+HLA-DR+) CD4+ T cells during the follow-up. On the other hand, memory (CD8+ CD45RO+ and CD8+ CD45RO+CD38+), activated (CD8+ HLA-DR+CD38+, CD8+ HLA-DR+, CD8+ CD38+), and effector (CD8+ CD57+, CD8+ CD28(-)CD57+) CD8+ T cells had a very significant decrease during follow-up. Our data indicate an immune system reconstitution in heavily pretreated HIV-infected children in response to salvage therapy with LPV/r as a consequence of a decrease in immune system activation and an increase in thymic function.

Recomendaciones CEVIHP/SEIP/AEP/PNS respecto al tratamiento antirretroviral en niños y adolescentes infectados por el VIH

OBJECTIVE

To update antiretroviral recommendations in antiretroviral therapy (ART) in HIV-infected children and adolescents.

METHODS

Theses guidelines have been formulated by a panel of members of the Plan Nacional sobre el SIDA (PNS) and the Asociacion Espanola de Pediatria (AEP) by reviewing the current available evidence of efficacy, safety, and pharmacokinetics in pediatric studies. Three levels of evidence have been defined according to the source of data: Level A: randomized and controlled studies; Level B: Cohort and case-control studies; Level C: Descriptive studies and experts' opinion.

RESULTS

When to start ART should be made on an individual basis, discussed with the family, considering the risk of progression according to age, CD4 and viral load, the ART-related complications and adherence. The ART goal is to reach a maximum and durable viral suppression. This is not always possible, even with clinical and immunologic improvement. The difficulties of permanent adherence and side-effects are resulting in a more conservative trend to initiate ART, and to less toxic and simpler strategies. Currently, combinations of at least three drugs are of first choice both in acute and chronic infection. They must include 2 NA 1 1 NN or 2 NA 1 1 PI. ART is recommended in all symptomatic patients and, with few exceptions, in all infants in the first year of life. Older asymptomatic children should start ART according to CD4 count, especially CD4 percentage, that vary with age. Despite potent salvage therapies, it is common not to reach viral undetectability. Therapeutical options when ART fails are scarce due to cross-resistance. The cause of failure must be identified. Occasionally, there exists clinical and/or immunological progression, and a change of therapy with at least two new drugs still active for the patient, is warranted with the aim of increasing the CD4 count to a lower level of risk. Toxicity and adherence must be regularly monitored. Some aspects about post exposure prophylaxis and coinfection with HCV or HBV are discussed.

CONCLUSIONS

A higher level of evidence with regard to ART effectiveness and toxicity in pediatrics is currently available, leading to a more conservative and individualized approach. Clinical symptoms and CD4 count are the main determinants to start and change ART.

Homeostatic role of IL-7 in HIV-1 infected children on HAART: association with immunological and virological parameters

AIM

To investigate the role of IL-7 in HIV-infected children on highly active antiretroviral therapy (HAART) and its association with laboratory parameters related to disease progression.

PATIENTS AND METHODS

A cross-sectional study in 31 vertically HIV-infected children (median age 8.4 y) treated with HAART, and a longitudinal study in four of those same children was carried out. In both studies, viral load, CD4+ T-cell counts, thymic production of T cells by TCR rearrangement excision circles (TRECs), IL-7 plasma levels and viral phenotype were determined.

RESULTS

IL-7 levels were higher in HIV-infected children than in age-matched, uninfected controls. In addition, HIV children with CD4+ T cells between 200 and 500 T cells/mm3 had higher IL-7 levels and lower TREC values than HIV-infected children with CD4+ T cells >500 T cells/mm3. IL-7 levels were higher in children with syncytium-inducing (SI) phenotype than in those with non-syncytium-inducing (NSI) variants. During the follow-up of four HIV children, the decrease in viral load after HAART was always associated with a recovery of CD4+ T cells and TRECs, which was followed by a decrease in IL-7 returning to the levels present prior to the drop in CD4+ T cells. The four HIV-infected children had SI/X4 isolates in PBMC before HAART, and the viral phenotype switched to NSI/R5 after HAART.

CONCLUSION

Our data suggest that IL-7 plays a key role in the maintenance of T-cell homeostasis in HIV-infected children on HAART, both through peripheral expansion and through a thymus-dependent mechanism.

Positive virological outcome after lopinavir/ritonavir salvage therapy in protease inhibitor-experienced HIV-1-infected children: a prospective cohort study

BACKGROUND

Lopinavir/ritonavir has demonstrated antiviral activity in the HIV-infected patient.

OBJECTIVE

To analyse virological response to lopinavir/ritonavir therapy in previously protease inhibitor (PI)-experienced HIV-1-infected children.

MATERIALS AND METHODS

Sixty-seven HIV-1-children on lopinavir/ritonavir were studied in a multicentre prospective cohort observational study. The outcome variables were undetectable viral load (uVL; VL < or =400 copies/mL) and virological failure after uVL with a rebound of VL >400 copies/mL. VL and genotype of HIV-1-isolates were measured using standard assays.

RESULTS

83.5% of children had a 1 log10 VL decrease including 65.6% who reached uVL. Children with >2 changes of antiretroviral therapy (ART) or >5 drugs needed a median time of 3-4 months higher than children with < or =2 changes of ART or < or =5 drugs previous to lopinavir/ritonavir, to reach those values, and the relative proportions (RP) were 2.2 (P =0.038) and 1.9 (P=0.050), respectively. Children with CD4+>15% (P=0.122), VL < or =30,000 (P < 0.001) copies/mL, and age >12 years (P=0.096) achieved an earlier control of VL during the follow-up. The children with virological failure or rebound of VL had higher baseline VL and lower CD4+ T-lymphocytes/mm3 and had taken a greater number of drugs previous to lopinavir/ritonavir. HIV-children with a new nucleoside reverse transcriptase inhibitor (NRTI), or protease inhibitor (PI) or PI plus non-nucleoside reverse transcriptase inhibitors (NNRTI) in the current regimen had a better virological response than children without these new drugs. Also, children with <6 protease mutations had an RP of 2.31 of achieving uVL.

CONCLUSIONS

Highly active antiretroviral therapy (HAART) including lopinavir/ritonavir induces beneficial effects in terms of virological outcome responses, and it is an effective option for salvage therapy in PI-experienced HIV-1-infected children.

Salvage lopinavir-ritonavir therapy in human immunodeficiency virus-infected children

OBJECTIVE

To study the control of viral replication in human immunodeficiency virus (HIV)-infected children on different salvage therapies.

DESIGN AND SETTING

A retrospective observational study in 120 HIV-infected children was conducted. The children were divided into 3 groups according to their salvage therapies: (1) children receiving first line highly active antiretroviral therapy (HAART); (2) protease inhibitor-experienced children receiving second line HAART; (3) protease inhibitor-experienced children receiving HAART including lopinavir-ritonavir (LPV/r). The outcome variables examined were time to achieve viral load (VL) < or =400 copies/mL, success in achieving VL < or =400 copies/mL and time to virologic failure (VL >400 copies/mL).

METHODS

VL (HIV-RNA copies/mL) was quantified with reverse transcription-polymerase chain reaction molecular assay. For each protocol, survival analyses were conducted to determine the probability of achieving VL < or =400 copies/mL and rebound of VL.

RESULTS

VL < or =400 copies/mL was achieved by 52.4% of children receiving first line HAART, 48.3% receiving second line HAART and 71.5% receiving HAART including LPV/r. Children receiving HAART including LPV/r reached VL < or =400 copies/mL in a shorter time than children receiving second line HAART (P = 0.017), but quite similar to children receiving first line HAART. In terms of adjusted relative risk, children receiving HAART including LPV/r were 3.36 [95% confidence interval (95% CI), 1.59, 7.07] more likely to achieve VL < or =400 copies/mL than children receiving a different second line HAART. VL rebound occurred in 68.2% children receiving first line HAART, 73.4% receiving second line HAART and 32.4% receiving HAART including LPV/r. Children receiving HAART that includes LPV/r has less incidence of VL rebound (P=0.013) and 3.29 (95% CI 1.04, 10.3) times less risk to achieve a VL rebound than children receiving a different second line HAART.

CONCLUSIONS

HAART that includes LPV/r is able to control HIV replication more efficiently than other classic salvage antiretroviral therapies.

HIV-infected children with moderate/severe immune-suppression: changes in the immune system after highly active antiretroviral therapy

The objective of this study was to monitor the changes in the immune system of HIV-infected children with moderate or severe immunodeficiency after highly active antiretroviral therapy (HAART), comprising a follow-up study in 14 HIV-infected children on HAART at two time points separated approximately by 11.8 +/- 0.4 (9.9; 15.4) months. HIV-infected children had significantly lower TREC levels than the control group, but 1 year after HAART the levels increased significantly (P < 0.05). In contrast, viral load (VL) did not change significantly. A positive correlation between T cell receptor excision circle (TREC) levels and both CD4(+) T cell absolute counts (r = 0.558; P = 0.05) and percentages (r = 0.625; P = 0.030) was found. During follow-up on HAART, the percentages and absolute counts of naive CD4(+) and CD8(+) T cell subsets were increased significantly (P < 0.05). CD4(+) CD45RA(hi+) CD62L(+), CD4(+) CD45RA(+) and CD4(+) CD38(+) percentages, and the CD8(+) CD45RA(hi+) CD62L(+) counts reached similar values to the control group. Also, CD8(+) CD45RO(+) CD38(+) and CD8(+) CD45RO(+) percentages, and CD8(+) CD45RO(+) CD38(+) absolute counts (P < 0.05) decreased with respect to the baseline. Lymphoproliferative responses to pokeweed mitogen (PWM) before HAART were lower in HIV-infected children than the control group, but they recovered to normal levels after a year on HAART. Tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma production by PHA-activated peripheral blood mononuclear cells (PBMC) was lower before HAART (P < 0.001), but reached similar levels to the control group 1 year after HAART. In HIV-infected children IgG, IgG(1) and IgG(3) plasma levels decreased significantly after HAART. The immune system reconstitution induced by HAART in HIV-infected children seems to be the consequence of decreased immune system activation and naive T cell reconstitution, mainly of thymic origin.

Impact of highly active antiretroviral therapy on CD4+ T cells and viral load of children with AIDS: a population-based study

In this study, we sought to characterize the changes over time at the population level on CD4(+) T cells and plasma viral load (VL) levels of HIV-1-infected children with or without AIDS. We carried out a retrospective study in 114 HIV-infected children during the calendar period that a highly active antiretroviral therapy (HAART) protocol was used. The HAART protocol consisted of three drugs: nucleoside analogue HIV-1 reverse transcriptase inhibitors, and/or HIV protease inhibitors, and/or nonnucleoside analogue HIV-1 reverse transcriptase inhibitors. The mean of CD4(+) T cells percentage and log(10) VL per calendar year were stratified by AIDS diagnostic. As new HAART strategies become available, an increase of CD4(+) T cells and a decrease of VL were observed over time, in children with and without AIDS. In 2001, children with AIDS reached values of CD4(+) T cells and VL similar to children without AIDS. In conclusion, our study shows that the generalized use of HAART has permitted improvement in immunological and virological status of HIV-infected children without AIDS, and more importantly in children with AIDS.

Increased interleukin-7 plasma levels are associated with recovery of CD4+ T cells in HIV-infected children

To asses the role of interleukin 7 (IL-7) in the thymic reconstitution of CD4 T cells observed in children after successful antiretroviral therapy, a longitudinal study in five vertically HIV-1-infected children was carried out. Thymic function, IL-7 plasma levels, viral load, and T-lymphocytes subsets were determined every 2 or 3 months for about 90 months. In all the children, the drop in CD4+ T cells below 5-10% was associated with a marked increase in IL-7 plasma levels. The drastic decrease in viral load after treatment, led in all the cases to a recover of CD4 to levels higher than 30%, which was associated to an increase in thymic production of T cells and followed by a decrease in IL-7 to the normal levels. We conclude that the drop in CD4 in HIV children would induce an increase of IL-7 as part of a homeostatic mechanism. IL-7 would induce the thymus to produce new T cells to recover the normal levels of CD4 when the viral load was low and so the thymic function was not inhibited. The increase in the thymic production of new T cells recovers the CD4 population, and leads to a normalization of IL-7 levels.

Extensive implementation of highly active antiretroviral therapy shows great effect on survival and surrogate markers in vertically HIV-infected children

We performed a retrospective observational study of 253 children vertically infected with human immunodeficiency virus (1994-2001) to assess the effectiveness of antiretroviral therapies (ARTs) on survival and surrogate markers at the population level. Children were divided into 3 groups according to the ART protocols used during the follow-up period: calendar period (CP) 1 (1994-1996) received combined therapy with 2 nucleoside reverse transcriptase inhibitors (NRTIs); CP2 (1997-1998) received implementation of highly active ART (HAART) with 3 drugs (NRTIs, protease inhibitors, and non-NRTIs); and CP3 (1999-2001) received extensive HAART. The children in the CP3 group had statistically significant longer survival periods, lower virus load (VL), highest undetectable VL proportion, and highest CD4+ T cell counts. HAART is effective at the population level at decreasing VL, increasing CD4+ T cells, and increasing the survival in a higher percentage of HIV-infected children.

Virological phenotype switches under salvage therapy with lopinavir-ritonavir in heavily pretreated HIV-1 vertically infected children

OBJECTIVE

To investigate the effects of salvage therapy with lopinavir-ritonavir on HIV-1 phenotype in heavily antiretroviral experienced HIV-infected children.

DESIGN

Twenty antiretroviral experienced HIV-infected children were studied during a mean of time of 16.1 months from initiation of the treatment with lopinavir-ritonavir.

METHODS

Besides CD4 T cells, viral load and clinical status, we analyzed 91 serial viral isolates to study the phenotype, and biological clones derived from co-cultivation techniques.

RESULTS

We observed an increase in CD4 T cells, a statistically significant decrease in viral load and clinical benefits from 3 months after treatment. Ninety per cent of children had SI/X4 bulk isolates in peripheral blood mononuclear cells at study entry. The viral phenotype changed to non syncitium-inducing (NSI)/R5 in 94% of the children after a mean of 5.7 months (95% confidence interval, 2.1-9.3 months) of salvage therapy. The remaining 10% of children had NSI/R5 isolates at entry and at all follow-up study. Similar results were found at the clonal level. Thus, at study entry in PBMC of three children with bulk syncitium-inducing (SI) phenotype, we recovered 65 biologic clones, 56 being SI and nine NSI. After salvage therapy bulk isolates changed to NSI and of 40 biologic clones recovered only five were SI and the rest were NSI.

CONCLUSIONS

Our data suggest that lopinavir-ritonavir salvage therapy led not only to a viral load decrease but also to a phenotypic change. X4 virus appeared to be preferentially suppressed. Shifts in co-receptor usage may thereby contribute to the clinical efficacy of anti-HIV drugs in vertically infected infants.

Subpoblaciones de células T CD8+ en niños asintomáticos infectados verticalmente por el VIH-1

BACKGROUND AND OBJECTIVE

HIV-infection has distinct patterns of disease progression with heterogeneous manifestations. We analyzed the subsets of CD8+ T cells in a group of long term asymptomatic (LTA) HIV-1-infected children who had stable CD4+ T cell counts (> 600/l).

PATIENTS AND METHODS

Cross-sectional study in HIV-1-vertically infected children older than 7 years who were rated into two groups according to the clinical and immunological classification: a) LTA: 7 asymptomatic HIV-1-infected children in A1, and b) rapid progressor (PR): 14 age-matched C3 HIV-1-infected children. Controls included 17 age-matched uninfected children. Characterization of CD8+ T-cell subsets was done by three-color flow cytometry.

RESULTS

LTA children displayed similar values of memory CD8+ T cells (CD8+CD45RO+, CD8+CD45RA-CD28+, CD8+ CD45RA-CD62L+) as controls but lower than PR children. LTA patients also showed similar values of naïve CD8+ T cells (CD8+CD45RA+CD62L+, CD8+CD45RA+CD28+, CD8+CD45RA+, CD8+CD28+ and CD8+CD62L+) as controls but higher values than PR children. The values of CD8+CD38+ T cells were similar in LTA and controls but lower in PR. However, LTA children had higher values of CD8+HLA-DR+CD38+ and CD8+HLA-DR+ T cells than controls. Additionally, LTA patients had higher values of pre-effector CD8+ T cells than controls yet the values of effector CD8+ T-cells were similar in both LTA and controls. Moreover, the LTA group had lower values of CD8+CD11b+ T cells than controls.

CONCLUSIONS

Asymptomatic HIV-1 infected children have an almost normal CD8+ subset distribution, with the exception of activated and pre-effector CD8+ T cells which were higher.

Viral Load and CD4+ T Lymphocyte Response to Highly Active Antiretroviral Therapy in Human Immunodeficiency Virus Type 1-Infected Children: An Observational Study

An observational study was performed involving 95 children with vertically transmitted human immunodeficiency virus type 1 infection to assess the sustainability of undetectable viral loads (VLs) and increased CD4+ T lymphocyte percentages after 48 months of highly active antiretroviral therapy (HAART). The median time to achieve a 10% increase in the CD4+ T lymphocyte percentage was 11.01 months. The median time to achieve an undetectable VL was 6.4 months. At the end of the study, 64.2% of the children had achieved an undetectable VL. Of the patients with an initial VL of >3.6 log10 copies/mL, 74.7% had a decrease in the VL of 1 log10 copies/mL. By contrast, of the patients who presented with an initial VL of >4.6 log10 copies/mL, 37.9% had a decrease of >2 log10 copies/mL. Higher VL at baseline, antiretroviral therapy regimens received before HAART, and multiple drug switches while receiving antiretroviral therapy were all inversely associated with an undetectable VL. A CD4+ T lymphocyte percentage of >25% was directly associated with undetectable VL during the follow-up period. In conclusion, first-line HAART induces beneficial virological and immunological outcome responses in children.

Neuroprotective effects of early antiretrovirals in vertical HIV infection

We performed a retrospective study of a series of 58 of 189 vertically HIV-1 infected children who went on to develop progressive HIV-1-associated encephalopathy to assess real-life effects of early antiretroviral therapy on neurologic outcome. Our findings clearly indicate that antiretroviral therapy before the onset of neurologic symptoms delayed presentation of progressive HIV-1-associated encephalopathy, with an additional beneficial effect on survival.

Characterizing the immune system after long-term undetectable viral load in HIV-1-infected children

Thirty two HIV-infected children, on highly active antiretroviral therapy (HAART) and > 500 CD4+ T cells/mm3, were rated according to the time-course of viral load (VL) during the whole follow-up period (> 18 months) in a longitudinal retrospective study. (a) uVL group: 15 children with VL below 400 copies/mL; (b) dVL group: 17 children with higher VL. The uVL group showed higher memory (CD4+CD45RO+) T cells than did dVL group, and higher number of memory activated CD4+CD45RO+HLA-DR+ than did control group (healthy age-matched uninfected children), whereas CD4+CD45RA(hi)+CD62L+ was similar. However, TCR rearrangement excision circles (TRECs) were higher in uVL group than in dVL group. uVL Group showed CD8+CD45RO+ and CD8+CD45RO+CD38- higher number than the control group, but lower than the dVL group. The percentage of CD8+CD45RA(hi)+CD62L+, CD8+CD45RA+, CD8+CD62L-, and CD8+CD28+ was higher in uVL group than in dVL group, and lower than in control group. The uVL group showed higher number of activated (HLA-DR+CD38+, HLA-DR+, HLA-DR+CD38-) CD4+ T cells and lower percentages of CD4+HLA-DR-CD38+ than dVL group. In activated CD8- T cell, the uVL group had lower CD8+HLA-DR+CD38+, CD8+HLA-DR+, and CD8+CD38+ than the dVL group. Preeffector (CD8+CD57-CD28- and CD8+CD45RA-CD62L-) T cells were lower in the uVL group than in dVL group. In the effector (CD8+CD57+, CD8+CD57+CD28-, and CD8+CD45RA+CD62L-) T cells, HIV-infected-children had higher values than control group. HIV-infected-children who respond to HAART had TRECs reconstitution, decreased immune activation, and lower effector CD8+ T cells. Moreover, successful HAART allow the increment of activated CD4+ T cells.

Recovery of T-cell subsets after antiretroviral therapy in HIV-infected children

BACKGROUND

Variation of percentageCD4+ T cells may accurately reflects the kinetics of a comprehensive immune recovery independently of the antiretroviral (ART) regimen. To test this we have investigated the relationship among peripheral blood T-cell subsets with the variation of percentageCD4+ T cells during follow up in 49 HIV-infected children.

METHODS

Children were divided into two groups according to the sign of slope percentageCD4+ T cell during follow up: Ps-group (positive slope) and Ns-group (negative percentageCD4 slope) indicative of immunological recovery or not, respectively. CD4+ and CD8+ T-cell subset percentages were examined by three-colour flow cytometry.

RESULTS

We found higher memory CD4+ and CD8+ T-cell percentages in the Ns-group than in the Ps-group, and inversely, higher naive CD4+ and CD8+ T cells in the Ps-group than in the Ns-group. CD4+ and CD8+ subsets in the Ps-group expressed higher levels of CD38+ and lower levels of HLA-DR+ compared with the Ns-group. We found a very strong positive correlation among the slope of percentageCD4+, CD4+ CD38+, whereas a negative correlation among the slope of percentageCD4+, the CD8+ CD28+ CD57+ and CD8+ CD57+ T-cell subsets.

CONCLUSION

Recovery of the CD4+ T-cell percentage induced by ART reflects a reduction in the chronic immune activation and a measurable reconstitution of the immune system and depends on naive CD4+ T cells.

Preserved immune system in long-term asymptomatic vertically HIV-1 infected children

The objective of this study was to study immune system status in long-term asymptomatic (LTA) HIV-1-infected children. A cross-sectional study was used, involving HIV-1-infected children over 7 years of age who were rated into two groups according to their clinical and immunological classification: (a) LTA: 7 asymptomatic HIV-1-infected children in A1; (b) Rapid progressor (RP): 14 age-matched C3 HIV-1-infected children. The control group consisted of 17 age-matched uninfected children. The characterization of CD4+ T-cell subsets was determined by three-colour flow cytometry. The proliferative response and cytokine production by activated peripheral blood T-cells were also measured. IL-7 levels were measured in serum. Thymic production of T-cells was quantified by TCR rearrangement excision circles (TRECs). The LTA children showed similar proliferative responses to PHA, PWM and anti-CD3+ anti-CD28, but lower responses to tetanus toxoid and streptokinase, in comparison with the controls but always higher responses in comparison with the RP group. The production of TNF-alpha and IFN-gamma was similar in the LTA and control groups, and both were higher than the levels in the RP group. The LTA group showed a lower percentage of memory CD4+ T-cells (CD4+ CD45RO+, CD4+ CD45RA-CD62L+) than the control and RP groups. The LTA group also showed lower percentages of CD4+ CD7- cells than the controls. As for naïve CD4+ T-cells (CD4+ CD45RA+ CD62L+), CD4+ CD45RA+ and CD4+ CD62L+ cells, the LTA group showed higher values than the control and RP groups. The LTA group showed higher percentages of CD4+ HLA-DR+ CD38+ than the controls, but lower values than the RP group. In contrast, the LTA group had percentages of CD4+ HLA-DR-CD38+ T-cells higher than both the control and RP groups, whereas CD4+ CD38+ levels were only higher in the LTA group in comparison with the controls. CD4+ HLA-DR+ CD38- and CD4+ HLA-DR+ cell numbers were lower in the LTA group in comparison with the RP group. We found almost normal values of TRECs and IL-7 in the LTA group, but lower values in the RP group. Moreover, we found an inverse relation between TREC levels and IL-7 in plasma from HIV-infected children. Asymptomatic HIV-1 infected children have a well preserved immune system similar to that of control uninfected children in spite of HIV-infection for more than 7 years. Moreover, our results identified new markers of HIV disease, such as TRECs and IL-7, that could be used to monitor disease.

[Complete immune and clinical recovery after highly active antiretroviral therapy in advanced vertically HIV-1 infected children]

BACKGROUND AND OBJECTIVE

The aim of this study was to evaluate the ability of long-term highly active antiretroviral therapy (HAART) to fully reconstitute the immune system in children with severe AIDS.

PATIENT AND METHOD

Lymphoproliferative responses (LPR) were evaluated by incorporation of [3H]-thymidine. Cytokine production in culture (IFN- gamma, IL-5) was quantified using commercially available specific ELISA assays. T-cells subsets were determined by 3-color flow cytometry and thymic production of T-cells was assessed by quantification of TCR rearrangement excision circles (TRECs).

RESULTS

We present a vertically HIV-1-infected child at clinical category C, with long-standing CD4+ T-cells below 50/l, who was monitored during 3-years after starting HAART by quantifying the viral load (VL), naïve, memory, and activated T-cell subsets, and thymical function as well as clinical events. VL was suppressed to undetectable levels since the beginning of HAART with d4T, 3TC, nelfinavir, and efavirenz resulting in a dramatic immune reconstitution, achieving normal CD4+ T-cells counts after 6 months (25%, 597 CD4+ T-cells/l) and perdurable undetectable VL levels. Naïve CD4 and CD8 T-cells increased in parallel to TCR rearrangement excision circles (TRECs) levels, with a concomitant decrease in T-cell activation markers. Interestingly, the patient showed an increase in the lymphoproliferative responses to PHA; the IFN-gamma production by PBMCs increased with HAART while the production of IL-5 diminished, thus indicating a switch of type 2 to type 1 response. He recovered clinically and immunologically (up to normal levels) and remains asymptomatic at present.

CONCLUSION

This report demonstrates that at least in these children, an immune and clinical recovery from an advanced stage of HIV-disease can be possible throught HAART.

Transmission of HIV-1 infection between trophoblast placental cells and T-cells take place via an LFA-1-mediated cell to cell contact

HIV-1 vertical transmission is thought to mainly take place by virus crossing the placental barrier. However, the mechanism by which HIV-1-infects placental cells remains to be elucidated. We have found that purified cytotrophoblasts as well as trophoblastic cell lines are susceptible to infection by different HIV-1 isolates as detected by DNA-PCR and release of infectious virus, although with very low efficiency. Purified trophoblast or trophoblastic cell lines express low levels of chemokine receptors CCR-5 and CXCR-4 but not CD4 on the cell surface. To test if those molecules were used as receptors for HIV-1 infection, placental cells were pretreated with antibodies to CD4, CC-chemokines, C-X-C chemokines. None of those treatments inhibited HIV-1 infection. In contrast, we have found that HIV-1 infection of placental cells was increased in cocultures of infected T-cell blasts and placental cells. More interestingly, antibodies to beta(2) integrins and to LFA-1 were able to significantly block infection of placental cells. Cell surface expression of ICAM-1, an adhesion molecule involved in attachment of leukocytes to placenta, was upregulated in HIV-1-infected placental cells. Placental cells were able to transfer HIV-1 infection to T-cell blasts. This transmission required cell to cell contact and was also inhibited by anti-LFA-1 antibodies. In summary our results suggest that placental trophoblast could be infected by HIV-1 by a mechanism involving T cell to placental contact. Moreover, placental infection enhanced ICAM-1 expression and leukocyte adherence, an event which was required to transfer HIV-1 infection to T cells. This provides an explanation of the virus passing through the placental barrier during in utero HIV-1 vertical transmission.

Low blood CD8+ T-lymphocytes and high circulating monocytes are predictors of HIV-1-associated progressive encephalopathy in children

OBJECTIVE

Human immunodeficiency virus type 1 (HIV-1)-associated progressive encephalopathy (PE) is a common and devastating complication of HIV-1 infection in children, whose risk factors have not yet been clearly defined. Regardless of the age of presentation, PE shortens life expectancy. Paradoxically, as survival of patients has been prolonged as a result of the use of antiretroviral therapy, the prevalence of PE has increased. Therefore, a predictive marker of PE emergence is critical. The objective of this study was to determine in an observational study whether any immunologic (CD4(+) and CD8(+) T-lymphocyte counts, monocyte counts) or virologic (viral load [VL], biological characteristics of viral isolates) marker might be predictive of PE and whether any particular marker may be involved in the timing of clinical onset of PE.

METHODS

A total of 189 children who were vertically infected with HIV-1 were studied retrospectively, 58 of whom fulfilled criteria of the American Academy of Neurology for PE. T-lymphocyte subsets and monocytes in peripheral blood were quantified by flow cytometry. HIV-1 RNA was measured in plasma using a quantitative reverse transcriptase polymerase chain reaction assay. Demographic, clinical, and viro-immunologic characteristics in infants were compared with control groups using logistic regression. Proportions were compared using the chi(2) test or Fisher exact test. For each child, immunologic and virologic markers were analyzed in parallel closely before clinical onset of PE and closely after PE onset and compared by using the Student t test for paired samples.

RESULTS

Overall, mortality of 58 HIV-1-infected children who developed PE was significantly higher than of children who did not develop this complication. Blood CD8(+) T-lymphocytes <25% in the first months of life suggested a relative risk of progressing to PE 4-fold higher than those with CD8(+) >25% (95% confidence interval: 1.2-13.9) and remained statistically significant after adjustment for treatment. When we compared the PE-positive group with the acquired immunodeficiency syndrome (AIDS)/PE-negative group (children who developed clinical category C and without neurologic manifestations) in a cross-sectional study within 12 months before PE or AIDS diagnosis, respectively, the %CD8(+) T-lymphocytes were significantly lower in the PE-positive group. Normalized absolute counts of CD8(+) T-lymphocytes with respect to seroreverting children were significantly lower in the group of children with encephalopathy with respect to the AIDS/PE-negative group (data not shown). It is interesting that a statistically significant increase was observed in circulating monocyte percentages and absolute counts shortly before the first neurologic symptoms compared with values after PE was established and with those from HIV-1-infected controls. With respect to AIDS-related events, PE was strongly associated with anemia and lymphoid interstitial pneumonitis in the PE-positive group with respect to a group of children with AIDS but without PE.

CONCLUSION

HIV-1 infection of the central nervous system (CNS) remains an important clinical concern. The first step toward PE prevention in HIV-1-infected children should be directed at predicting risk of PE and thus the prompt and reliable identification of infants who are at risk for CNS disease progression. Low blood CD8(+) T-lymphocytes is a strong early predictive marker of PE emergence in vertical HIV-1 infection. Indeed, among all of the immunologic and virologic variables assessed in this observational study, the only significant difference during the first months of life are the CD8(+) T-lymphocytes. A peak of significantly higher peripheral monocytes before the onset of PE with respect to established PE has not been previously described, and strengthens the growing evidence that an increased traffic of monocytes to the brain may be a key factor in triggering neurologic symptoms. The suppression of HIV-1 replication is dependent on the presence of a relatively small number of HIV-1-specifof HIV-1-specific CD8(+) T-lymphocytes, and it is possible that the duration of the neurologically asymptomatic phase for any given child may depend mostly on the magnitude of specific CD8(+) T-lymphocyte responses. Thus, a decrease of CD8(+) T-lymphocytes would diminish the host capacity to control viral infection, as reported in animal models, enabling infected macrophages to cross the blood-brain barrier. Our results advocate the use of CD8(+) T-lymphocyte and monocyte counts to follow-up HIV-1-infected children. We suggest that CD8(+) T-lymphocytes may be the nexus for many different aspects of the disease, namely loss of control of HIV-1 replication determining higher VL, increased traffic of activated and/or infected monocytes, spread of infection to immune sanctuaries, and finally clinical neurologic emergence of PE. Moreover, we suggest that CD8(+) T-lymphocytes or/and monocytes may be used as putative biological markers of neuropathogenicity. This might suggest their use in decision making of when to start more effective antiretroviral regimens for HIV-1 infection of the CNS and the need of new therapies either to preserve or to augment an adequate CD8(+) T-lymphocyte immune response. Early detection of children who are at risk for developing PE is particularly important because aggressive highly active antiretroviral therapy improves neurologic symptoms, allows possible use of neuroprotective treatment to prevent further development of encephalopathy, and emphasizes the relevance of developing therapies aimed to enhance CD8(+) T-lymphocyte function. In conclusion, the surrogate markers routinely used in clinical practice for HIV-1 infection (ie, CD4(+) T-lymphocyte counts and VL) seem to be insufficient to evaluate the clinical involvement of the CNS. Other systemic markers, as the recent proposed markers for PE evolution (cerebrospinal fluid VL by lumbar puncture and brain atrophy by cerebral magnetic resonance imaging) are undoubtedly more invasive than measuring CD8(+) T-lymphocyte and monocyte counts, when the neurologic manifestations of PE are still preventable.

Stimulated proliferative responses in vertically HIV-infected children on HAART correlate with clinical and immunological markers

The objective of the study was to investigate the relationship between various CD4+ T cell subsets and the ability of peripheral blood mononuclear cells (PBMC) to proliferate to several stimuli in vertically human immunodeficiency virus type 1 (HIV-1)-infected children. We studied 29 HIV-1-infected children on highly active antiretroviral therapy (HAART) (median duration: 12.3 months). T cell subsets were determined by flow cytometry. Plasma viral load (VL) was quantified using a standardized molecular method. Proliferative responses were evaluated by [3H]-thymidine incorporation. Decreased proliferative responses of PBMC to pokeweed mitogen (PWM) were found for HIV-1-infected children in Centers for Disease Control (CDC) clinical categories B and C when compared to the control group (P < 0.05). Similarly, children with < or = 15% CD4+ T cells showed a decrease in proliferative responses to PWM (P < 0.01), anti-CD3 + anti-CD28 (P < 0.01) and phytohaemagglutinin (PHA) (P < 0.05) with respect to the control group and to children with CD4+ T cells > or = 25%. Proliferative responses to PWM, anti-CD3+, anti-CD28 and PHA had a statistically significant positive correlation with CD3+/mm3, CD4+/mm3, % CD4 T cells, CD4/CD8 ratio and the percentage of naive T cell subsets (CD4+CD45RO-HLA-DR-, CD4+ CD45RA+ CD62L+, CD4+ CD45RA+), CD4+ CD62L+ and CD4+ T cells co-expressing CD38+ (CD4+ HLA-DR-CD38+, CD4+ CD38+). Moreover, we found a negative correlation between PBMC proliferative responses and % CD8 T cells, memory, memory-activated and activated CD4+ T cell subsets. Lower proliferative responses to PWM (P < 0.01) and PHA (P < 0.01) were associated with higher VL. Our data show that higher proliferative responses to PWM, anti-CD3 + anti-CD28 and PHA are associated with both non-activated and naive CD4+ T cell subsets in HIV-1-infected children on HAART.

Characterizing immune reconstitution after long-term highly active antiretroviral therapy in pediatric AIDS

In this study, we sought to characterize the T lymphocyte recovery in vertically HIV-1-infected children who respond to long-term highly active antiretroviral therapy (HAART). A 3-year longitudinal retrospective study was used to perform a cross-sectional study of 32 children rated according to the time course of CD4(+) T cell percentages in response to antiretroviral therapy and CDC clinical classification: (1) long-term asymptomatic (LTA group): 8 children in A1 during the whole follow-up period; (2) responsive to HAART (Rec group): 13 children in C3 before HAART who achieved CD4(+) T cell counts of > 500 cells/mm(3) after 3 years of HAART; and (3) nonresponsive to HAART (Non-Rec group): 11 children in C3 during the whole follow-up period despite 3 years of HAART. We also studied 17 healthy age-matched uninfected children as controls. Lymphoproliferative responses (LPRs) were evaluated by incorporation of [(3)H]thymidine, identification of T cell subsets by three-color flow cytometry, and determination of thymic production of T cells by quantification of T cell receptor rearrangement excision circles (TRECs). Interestingly, the Rec group showed an increase in percentage of CD4(+) T cells and a decrease in viral load, and recovered LPRs to mitogens and recall antigens, with values similar to those of the LTA group. Moreover, the Rec group produced similar percentages and absolute counts of naive (CD45RA(+)CD62L(+)) CD4(+) and CD8(+) T cells, and TRECs similar to those of the LTA group. In particular, the Rec group produced similar percentages of CD8(+)CD28(-)CD57(+) and CD8(+)CD28(-)CD57(-) T cell subsets compared with controls. Our data indicate that among children who have already progressed to AIDS and severe immunodeficiency but who respond to HAART, the immune system can recover and resemble those of nonprogressors or even uninfected children, in quantitative as well as in functional terms.

[Responses to antiretroviral treatments in vertically HIV-1-infected children]

BACKGROUND AND OBJECTIVE

Our goal was to determine the probability of achieving a fall-off of viral load (VL) and an increase of CD4+T-lymphocytes by 36 months from the initiation of antiretroviral therapy (ART) in a cohort of HIV-infected children according to their baseline data.

PATIENTS AND METHOD

This was retrospective multicenter observational study of virologic and immunologic markers in 128 HIV-1-vertically infected children on ART: 55 HIV-infected children on combination therapy (CT), and 73 HIV-infected children on highly active antiretroviral therapy (HAART). Viral load (VL) was quantified using a standard molecular assay. CD4+ and CD8+ T-cells subsets were determined by flow cytometry.

RESULTS

The median time for a 10% rise of CD4+ T-lymphocytes was 35.7 months (95% confidence interval [95% CI], 15.5-55.9) after starting CT, and 11 months (95% CI, 7,7-14.3) after starting HAART. The median time for a VL fall to < 400 copies/ml was 29.6 months (95% CI, 9.4-49.7) after starting CT, and the median time for a VL fall to < 400 copies/ml was 10.9 months (95% CI, 0-21.9) after starting HAART. A 10% increase of CD4+ T-cells over baseline was associated with HAART, low CD4+ T-cells and high VL. On the other hand, a VL fall lower than 400 copies/ml was associated with HAART and low baseline VL.

CONCLUSIONS

Our data indicate that HAART was better than CT in the control of VL and CD4+ T-cell increase. Also, baseline CD4+ T-cell and VL values helped to determine the response to ART in HIV-1 infected children.

Relevance of viral phenotype in the early AIDS outcome of pediatric HIV-1 primary infection

In infants the clinical course of HIV-1 infection is bimodal, differing considerably from that of adults. The effect of HIV-1 phenotypic features and plasma viral load on the clinical course of infection has been well established in adults, whereas in children it remains controversial. The aim of this study was to prospectively evaluate the effect of HIV-1 replication phenotypes during the first year of primary infection in the development of premature immunosuppression and early pediatric AIDS. In 62 vertically infected children replication rates of HIV-1 isolates from primary cultures and syncytium-inducing capability in MT-2 cell line were evaluated, together with plasma viral load. It was observed that rapid replication rate and syncytium-inducing phenotype accelerate the early onset of pediatric AIDS (p = 0.02 and p = 0.04, respectively). Rapid replication kinetics was the only significantly independent variable for early clinical outcome (risk ratio, 2.48; p = 0.02). Both viral properties contributed to rapid CD4+ T-cell depletion (p = 0.05 for rapid replication rate, p = 0.01 for syncytium-inducing viral phenotype). Plasma viral burden higher than 5.5 log(10) copies/mL after 6 mo of age tended to be associated with disease progression. In conclusion, initial HIV-1 biologic features in pediatric primary infection by vertical transmission may influence the progression to early immunosuppression and development of AIDS.

Production of new T cells by thymus in children: effect of HIV infection and antiretroviral therapy

The decrease in the number of CD4(+) T cells during HIV infection is the result of both peripheral destruction of cells by the virus and inadequate replacement of these cells. Aging and HIV infection lead to lower production of new T cells by the thymus, and, therefore, a complete restoration of the immune system is not generally achieved in infected adults after antiretroviral therapy. Because children have a completely functional thymus, we addressed the effects of HIV-1 infection on the production of new T cells in vertically infected children and whether the decrease of viral load after therapy results in a restoration of thymic function. To analyze the thymic function, T-cell receptor rearrangement excision circles were measured by quantitative PCR. Our results indicate that HIV-infected children have lower T-cell receptor rearrangement excision circle levels than age-matched uninfected children, likely due to an inhibitory effect of HIV on thymic function. Additionally, in some patients, the decrease in viral load after retroviral therapy allows the generation of new T cells by the thymus, thus recovering the normal number of CD4 cells.

[Immunologic recovery after 2-years on HAART in vertically HIV-infected children]

BACKGROUND

Our purpose was to carry out an analysis of T cells subsets involved in the recovery of the immune system in vertically HIV-1-infected children, on highly active antiretroviral therapy (HAART) over more than 24 months.

PATIENTS AND METHOD

Seventeen HIV-1-infected children were studied: a) Res-group (HIV-1-infected children who were HAART-responders): 10 children in category C3 at entry in the study who, after more than 24 months on HAART, recovered CD4+ T cells (> 25% and 500 CD4+ T-cells/ml) and may control viral replicación, and b) non-Res group (HIV-1-infected children who did not respond to HAART): 7 children in category C3 at entry in the study who, after more than 24 months on HAART, did not recover CD4+ T-cells (< 15% or 200 CD4+ T-cells/ml) and did not control viral replication. As control group, 12 HIV-1-uninfected children with similar ages were included in the study.

RESULTS

Children in the Res-group recovered the values of CD4+, CD8+ naïve (CD45RA+CD62L+) and memory (CD45RO+) T-cells until reaching the values of the control group. The differences were significant with regard to the non-Res group, except for the CD8+CD45RO+ T-cells of the Res and non-Res groups which were higher than the control group. Moreover, Res-group had values of CD8+HLA-DR+CD38+ T-cells lower than the non-Res group, yet both HIV-1 groups (Res and non-Res) had significantly higher values of CD4+ and CD8+ activated (HLA-DR+CD38+) T-cells than the control group.

CONCLUSIONS

The recovery of the immune system induced by HAART in HIV-1-infected children seems to be the consequence of the decrease of the immune system chronic activation and the recovery of naïve T-cells.

[Different immune profiles according to the immunological and clinical progression in vertically HIV-infected children]

BACKGROUND

Our goal was to evaluate immunologic profile differences of HIV-infected children on antiretroviral treatment (ART). PATIENTS AND METHODDS: We studied 23 HIV-vertically infected children: a) N-A1 group: 10 HIV-infected children in A1 category; b) N-B2 group: 6 HIV-infected children in B2 category, and c) N-C3 group: 7 HIV-infected children in C3 category. We also studied 13 healthy age-matched HIV-negative children as controls. Cell proliferation was evaluated by incorporation of [3H]-Thymidine. The cytokine production in culture was quantified using commercially available specific ELISA assays. T-cell subsets were determined by flow cytometry.

RESULTS

Stimulation indexes of PHA, PWM, and anti-CD3+ anti-CD28 in N-A1 group were higher than in N-C3 group. In unstimulated PBMC, TNF-alpha production of HIV-infected children was higher than the control group (p < 0.05). However, in stimulated PBMC, TNF-alpha production in N-B2 and N-C3 groups was lower than the control group (p < 0.05). In HIV-infected children, CD8+ CD45RA+ CD62L+ T-cells were significantly lower (p < 0.01) and CD8+ CD45RO+ T-cells were higher (p < 0.05) than the control group. Moreover, in NA-1 group, CD4+ CD45RA+ CD62L+ T-cells were higher, and CD4+ CD45RO+ and CD8+ CD45RO+ T-cells were lower, than in N-B2 and N-C3 groups (p < 0.05). On the other hand, CD45RO+, CD45RO+ CD38+, HLA-DR+, CD38+ HLA-DR+ and CD38+ CD4+ and CD8+ T-cells were higher in N-C3 group than the N-A1 and control groups, except for CD4+ CD38+ T-cells. Activated CD8+ T-cells in N-A1 group were higher than in control group (p < 0.01).

CONCLUSION

Our data demonstrate that in spite of ART, there still remain important differences in the immunologic status of HIV-infected children depending on the HIV-infection stage.

Impact of antiretroviral protocols on dynamics of AIDS progression markers

AIMS

To assess the "real life" effectiveness of different antiretroviral therapies (ART).

METHODS

A retrospective multicentre observational study in 150 HIV-1 vertically infected children on the progression to AIDS (study A), and in 61 HIV-1 infected children on the evolution of the most relevant markers of progression (study B). All children were categorised into four groups: untreated (NT); on monotherapy (MT); on combination therapy (dual-ART); and on potent ART (HAART).

RESULTS

No child in the HAART group progressed to AIDS, whereas 14 children in the NT and seven in the MT groups progressed to AIDS, respectively, the differences being statistically significant. There was a mean increase of 8 units of %CD4+ per year; this was greater in the HAART group than in the other groups. The mean decrease in viral load was 0.65 log(10) copies/ml per year; this was greater in the HAART group than in the NT and MT groups. The HAART group had the lowest probability of returning to baseline %CD4+ and viral load.

CONCLUSION

Potent ART had the greatest protective effect against progression to AIDS in this observational study.

Viral phenotype affects the thymic production of new T cells in HIV-1-infected children

OBJECTIVE

To determine whether viral phenotype has any effect on thymic production of new T cells in HIV-1-infected children.

DESIGN

Differences in CD4+ T-cell counts and a marker of thymic output [T-cell antigen receptor (TCR) rearrangement excision circles (TRECs)], between HIV-1-infected children with non-syncytium-inducing (NSI) and syncytium-inducing (SI) viral strains were determined.

PATIENTS AND METHODS

A cross-sectional study in 90 samples from vertically HIV-1-infected-children (median age 4.9 years) treated with combination therapy, and a longitudinal study in three children that underwent a change from NSI to SI phenotype were carried out. Viral load, viral phenotype, CD4+ T-cell counts, and quantification of TRECs values were determined.

RESULTS

Children with SI virus showed significant lower levels of CD4+ T cells and a lower thymic production of new T cells than children with NSI. These reductions were independent of the treatment and the age of the children. However, there were no differences in viral load with the phenotype between those groups. In children with both NSI and SI viral phenotype, there was a significant correlation between CD4+ T-cell counts and TRECs values.

CONCLUSION

The decrease of CD4+ T cells in presence of T-tropic viruses would be mainly due to a lower production of new CD4+ T cells as consequence of the inhibitory effect of these T-tropic strains on thymic function. This effect is not due either to the amount of circulating virus or to the replication kinetics of those strains, but rather depends on the ability of T-tropic viruses to infect T-cell precursors using CXCR4 receptors, which are highly expressed in immature thymocytes.

Naïve and memory CD4+ T cells and T cell activation markers in HIV-1 infected children on HAART

The objective of this study was to investigate the relationship between peripheral blood CD4+ T cell subsets and routine viro-immunological markers in vertically HIV-1-infected children undergoing highly active antiretroviral therapy (HAART). CD4+ and CD8+ T cell subsets were examined by three-colour flow cytometry. Plasma viraemia was quantified by a standardized molecular assay. A negative correlation between the %CD4+ T cells and both viral load and the %CD8+ T cells was observed. A strong positive correlation between the %CD4 T cells and naïve, CD38+ and non-activated CD4+ T cell subsets was found, whereas the %CD4 T cells correlated negatively with the numbers of memory, activated and memory-activated CD4+ T cell subsets. Elevated percentages of CD8 T cells were associated with increased memory and CD4+ CD62L-T cell subsets, whereas the naïve and CD4+ HLA-DRCD38+ subsets negatively correlated with the CD8%. Co-expression of CD62L on memory CD4+ cells and high expression of HLA-DR (but not of CD38) were associated with high viral load. No association between viral load and naïve CD4+ T cells was observed. Specific CD4+ T cell subsets may be more informative than routine surrogate markers in defining the evolution of HIV infection and immune reconstitution in children.

[Relationship between T-cells subsets and prognostic markers in HIV-1-infected children]

BACKGROUND

To investigate the relationship between peripheral blood T-cell subsets and both CD4+ T-cell percentage and viral load (VL) in HIV-1-infected children.

PATIENTS AND METHOD

We studied 50 HIV-1-infected children on antiretroviral therapy. T-cell subsets were determined by flow cytometry. The VL was quantified using standardized molecular methods.

RESULTS

Memory (CD45RO+), activated memory (CD45RO+HLA-DR+) and CD45RA-CD62L+ (memory cells expressing L-selectin) CD4+ and CD8+ T-cells correlated positively with the VL and negatively with the percentage of CD4+ T-cells. Inversely, naive CD4+ and CD8+ T-cells (CD45RA+CD62L+) correlated positively with the percentage of CD4+ T-cells and negatively with the VL. HLA-DR+, CD38+ or HLA-DR+CD38+CD4+ and CD8+ T-cells correlated also positively with the VL and negatively with the percentage of CD4+ T-cells (with the exception of CD4+CD38+ which did not show any association with the VL). CD8+CD28+ T-cells correlated positively with the percentage of CD4+ T-cells and negatively with the VL, whereas CD8+ CD57+ and CD8+CD28-CD57+ exhibited an opposite association.

CONCLUSIONS

Our data suggest a relationship between the different lymphocyte subsets (memory, naïve, activated and effector T-cells) and the most commonly used markers in clinical practice, namely the viral load and the CD4+ T-cell percentage. Some of these subsets may be useful to determine the virologic and immunologic status in HIV-1-infected children.

Association of CD8+ T lymphocyte subsets with the most commonly used markers to monitor HIV type 1 infection in children treated with highly active antiretroviral therapy

In contrast to adults, there is no information about children concerning the effects of the new antiretroviral therapy on the chronic activation and expansion of CD8+ T cells. We have investigated the relationship between blood CD8(+) T cell subsets, with percent CD4+ cells (%CD4), percent CD8+ cells (%CD8), and plasma viral load (VL), in 39 vertically HIV-1-infected children receiving highly active antiretroviral therapy (HAART) (mean age, 7.6 years; range, 2-15.6 years). CD8+ subsets were examined by three-color multiparametric flow cytometry, and VL was quantified by standard assays. There was a strong positive correlation between activated CD8+ T cells and VL. An increase in memory and memory-activated CD8+ T cells correlated with increased VL, whereas nonactivated memory cells and CD28+ CD8+ T cells correlated negatively with VL. Naive and effector cells did not correlate with VL, although the CD8+ CD45RA -CD62L- subset correlated with increased VL. Activated CD8(+) T cells did not correlate with %CD4, but an increase in memory-activated and effector CD8+ T cells was associated with lower %CD4. Increased naive CD8+ and CD28 +CD8+ T cells showed a positive correlation with %CD4 and a negative correlation with %CD8. In conclusion, in HIV-1-infected children receiving HAART, the activation of CD8+ T cells is associated with high VL, whereas CD8 +CD28+ and nonactivated CD8+ memory cells are associated with lower viral load. Naive CD8+ and CD28 +CD8+ T cells are associated with an improved immunological status.

Clinical relevance of cytokine production in HIV-1 infection in children on antiretroviral therapy

In order to investigate the correlation among cytokine production and antiretroviral therapy (ART), viral load, CD4(+) and CD8(+) T lymphocytes, 55 human immunodeficiency virus (HIV)-1-infected children on ART or not, and 16 uninfected controls were studied. Peripheral blood mononuclear cells (PBMCs) of HIV-1-infected children and controls were cultured and spontaneous and mitogen-stimulated cytokines production was quantified in the supernatants. Viral load was quantified using standard molecular assay. CD4 and CD8 T-lymphocyte counts were determined by flow cytometry. Cytokine production by mitogen-stimulated PBMCs showed different profiles in HIV-1 children whether treated or not. The tumour necrosis factor (TNF)-alpha production was higher and the interleukin (IL)-10 production was lower in the HIV-1-untreated group than in the HIV-1-treated children and controls. The IL-2 production was reduced and the RANTES production was higher in both HIV-1 groups compared with the controls. The interferon (IFN)-gamma and the IL-5 production was significantly reduced in the HIV-1-treated children compared to the controls. Interestingly, the analysis of the correlation of HIV-1 phenotype with cytokine production indicated an increased RANTES production in relation to nonsyncytium-inducing viral phenotype with slow/low replication profile, whereas decreased IL-10 levels was associated to syncytium-inducing (SI) strains and rapid/high replication. Our findings suggest that AVT changes on the cytokine and chemokine production play an important role in the HIV pathogenesis.

[Prognostic markers of progression to AIDS in infants vertically infected by human immunodeficiency virus type-1]

BACKGROUND

To study the prognostic AIDS progression value of the percentage of CD4+, CD8+, and plasma viral load (VL) (copies/ml) in HIV-1-vertically infected children.

PATIENTS AND METHOD

We study a cohort of 115 HIV-1 infected children older than 12 months of age. The VL was quantified using standard molecular assay. CD4 and CD8 T lymphocytes were determined by flow cytometry.

RESULTS

The children with a median of VL > 4.5 log10 (p < 0.001) and percentage of CD8+ < 25% (p = 0.05) during follow-up, progressed faster to AIDS than children with a median of VL < 4.5 log10 and CD8 > 25%. The relative risk (RR) of AIDS progression was 7-fold higher in children with median VL above 4.5 log10. When considering VL as a continuous variable, risk of progression to AIDS is 3.5-fold higher for each increase of one log10 of VL. The percentage of CD8+ T-cells had a RR of AIDS progression of 0.95/% CD8+ at entry to the study and of 0. 19/% CD8+ during follow-up, indicating protection against progression to AIDS.

CONCLUSIONS

Our results indicate that each basal values at entry in the study and during the follow-up of the percentage of CD8+ and VL helps to determine the risk of AIDS progression in HIV-1-infected children. More interestingly, the use of the two predictive markers together had higher predictive value.

[Role of cytokines and chemokines in the non-progression of HIV infection in vertically infected children]

BACKGROUND

To study the cytokine production in vertically HIV-1-infected children with more of 7 years of HIV infection and different pattern of progression.

PATIENTS AND METHODS

We study 32 HIV-1-infected children: 8 NA children (age > 7 years, asymptomatic or with light symptoms, without antiretroviral treatment and TCD4+ > 25%); 10 NE1 children (> 6 years, symptomatic, with antiretroviral treatment and TCD4+ > 25%); 14 NE2-3 children (> 6 years, symptomatic, with antiretroviral treatment and TCD4+ < 25%) and 16 (C) controls, children non-VIH+. The peripheral mononuclear cells of HIV-infected children (PBLs) were cultivated and cytokine production was quantified in the supernatant.

RESULTS

The non-stimulated PBMC from HIV-infected children produced more TNF-alpha and less IL-2 that C-group. The production of IFN-gamma was lower in the groups NE1 and NE2-3 than in C-group. The production of IFN-gamma was higher in group NA than in NE2-3. In the phytohaemagglutinin (PHA) stimulated PBLs, the production of TNF-alpha was higher in NA and NE1 than in controls. The production of IL-2 was similar in NA and NE1 than in controls. The production of IL-2 was similar in NA and NE1 than in control group, but the groups NE2-3 produced less IL-2 than control and NE1 groups. The production of IFN-gamma and RANTES were significantly higher in NA than in controls. The groups NE1 and NE2-3 produced lower levels of IL-5 than control and NA groups. The groups NE2-3 produced lower levels of IL-10 than control group. The ratio IFN-gamma/IL-5 and IFN-gamma/IL-10 were higher in group NA than in control and NE1.

CONCLUSIONS

In non-progressors HIV-infected children the immune response is conserved and we have observed an increased Th1 response, while in progressors HIV-infected children receiving antiretroviral treatment we could observe a diminished Th2 response. Moreover, our data clearly indicate that the decrease of IL-2 is an early marker of HIV-infection.

Predictive markers of clinical outcome in vertically HIV-1-infected infants. A prospective longitudinal study

We have investigated the relationship between disease progression and several immunologic and virologic markers of HIV infection. Plasma samples from infants born to HIV-1-infected mothers were collected at birth and at 1, 2, 4, 6, 9, 12, 15, and 18 mo of age and subsequently were assayed every 6 mo for viral load, viral phenotype, and lymphocyte populations. A cutoff level of 25% indicative of a preserved immunologic status, both of CD4+ and CD8+ blood T cells, was associated with significant differences in disease progression (p = 0.04 and 0.02, respectively). Infants with median CD4+ T cells <25% had a relative risk of progression to AIDS 3.35-fold higher than those with CD4+ above this level (p = 0.05). The relative risk of progression to AIDS for infants with median CD8+ <25% was 4.95-fold higher than for those with CD8+ percent above this threshold (p = 0.03). Similarly, a cutoff level of viral load of 5.5 log10 copies/mL was indicative of a worse prognosis. Infants with median viral load >5.5 log10 copies/mL had a relative risk of progression to AIDS 23.72-fold higher (p = 0.0001) than those with median viral load below this threshold. Interestingly, changes from a slow replication and low titer to a rapid replication and high titer of virus and from nonsyncytium-inducing to syncytium-inducing viral phenotype were indicative of progression to AIDS. Our results indicate that biologic phenotype of viral isolates and CD8+ T-lymphocyte percentages in peripheral blood as well as viral load and CD4+ T-lymphocyte percentages could predict rapid progression to advanced HIV-1 disease in HIV-1-infected infants.

Adenoidal tissue mass as a clinical guide of disease evolution in vertically HIV-1 infected children

INTRODUCTION

it is known that in early-stage HIV-induced disease there is a discrepancy between the levels of viral burden and virus replication in peripheral blood versus lymphoid organs. HIV disease is active in the lymphoid tissue throughout the period of clinical latency. However, it is not known how long term progression of HIV infection is influenced by short-term changes in the adenoidal size.

OBJECTIVE

To assess the reliability of adenoidal-nasopharyngeal (AN) ratio in predicting clinical evolution of pediatric HIV infection.

METHODS

lateral radiographs of the nasopharynx in 94 Caucasian children born to HIV-1-infected mothers ranged from 6 months to 15 years (60 children infected with HIV-1 and 34 without HIV infection), and in a control group of 692 normal children were evaluated to obtain the AN ratio in order to identify the relationship of AN profiles with different stages of the disease. Patients were rated regarding their clinical and immunological status according to the Center for Disease Control Classification.

RESULTS

statistically significant differences between the groups of HIV-1-infected children, seroreverters and controls in the AN ratio were found (P < 0.001). Moreover, significant differences were also found in individual children that correlated with clinical progression.

CONCLUSION

examination of radiographic changes in adenoidal size by AN ratio in relation to clinical status during one year period in the whole group showed strong prognostic value. These findings may have important implications in the design of therapeutic strategies.

HIV-1 infection induces differentiation of immature neural cells through autocrine tumor necrosis factor and nitric oxide production

Immature neural cell lines could be productively infected by HIV-1. Interestingly, this infection was associated with a differentiation to a mature neuronal phenotype, characterized by the expression of mature neurofilaments and cell adhesion molecules, intercellular cell adhesion molecule-1, and vascular cell adhesion molecule-1. Infection also induced TNF-alpha and IL-1beta mRNA expression, as well as the synthesis of inducible nitric oxide synthase by neuroblastoma cells. Exogenous addition of TNF-alpha, but not of IL-1beta or many other cytokines, including nerve growth factor, mimicked those effects induced by infection. Moreover, blocking endogenous TNF-alpha or NO production in cultures of infected cells with a neutralizing anti-TNF-alpha antibody or inducible nitric oxide synthase inhibitors prevented the expression of the mature cell phenotype as well as expression of intercellular cell adhesion molecule-1 and vascular cell adhesion molecule-1. Addition of NO generators and TNF-alpha activated NF-kappaB- and intercellular cell adhesion molecule-1-dependent promoter transcription, whereas inducible nitric oxide synthase inhibitors prevented the transcriptional activation of intercellular cell adhesion molecule-1 promoter that was induced by TNF-alpha. Those results suggest that HIV can infect immature neural cells and this infection induces their neural development via a TNF-alpha- and NO-mediated mechanism.

Early HIV-specific cytotoxic T lymphocytes and disease progression in children born to HIV-infected mothers

The activities of HIV-specific cytotoxic T lymphocytes (CTLs) were evaluated in 10 HIV-infected children, born to infected mothers who did not receive AZT during pregnancy. CTL activities were present as early as 4 months of age. The five children that progressed to AIDS before 1 year of age had reduced in vivo and in vitro CTL activities, when compared with children who remained AIDS free after 1 year of age. The latter children had weak in vivo activated CTL responses but strong memory CTLs. No relation was found between viral load, lymphocyte populations, and CTL responses between birth and 6 months of age. Between 7 and 12 months old, children with broader in vitro activated CTLs had higher absolute numbers of CD4+ and CD8+ T lymphocytes and lower plasma viral load. These data support a beneficial role of CTLs in pediatric HIV infection.