Different meaning of CD38 molecule expression on CD4+ and CD8+ cells of children perinatally infected with human immunodeficiency virus type 1 infection surviving longer than five years

Accelerated Aging of T-cell Subsets among ART-Naïve HIV-Infected Chinese Men who Have Sex with Men: A Case-control Study

BACKGROUND

Evidence of lymphopoiesis, exhaustion, and premature aging in Chinese patients with human immunodeficiency virus (HIV) is very limited.

OBJECTIVE

To assess biological aging and immune senescence in Chinese healthy controls (HC) and ART-naïve HIV-infected men who have sex with men (MSM).

METHODS

This case-control study was conducted in Beijing Ditan Hospital from March 2018 to June 2019. The percentages of naïve (TN), central memory (TCM), effector memory (TEM), and terminally differentiated memory (TemRA) subsets of CD4 and CD8 T cells were studied, along with markers of senescence (CD28-CD57+) and activation (HLA-DR+). Telomere length of naïve (CD45RA+) and memory (CD45RO+) CD8 T cells was quantified by real-time PCR.

RESULTS

A total of 26 HIV-infected and 20 age-matched HC MSM were included. Compared to HC group, CD4/CD8 ratio of HIV-infected group was significantly reduced (0.30 vs. 1.70, P<0.001); significant differences emerged among all CD8 but not CD4 T cell subsets (all P<0.05). In HIV-infected group, the percentages of senescent cells (CD28-CD57+) in TN, TCM, TEM, and TemRA subsets of CD8 T cells were higher (all P<0.05); while a significant difference was only found in naïve CD4 T cells (P<0.05). HLA-DR expression was increased significantly in all CD4 and CD8 T cell subsets. Both naïve (CD45RA+) and memory (CD45RO+) CD8 T cells in this population had significantly shorter telomere length (P<0.01) compared to HC group.

CONCLUSION

HIV-infected MSM exhibit signs of accelerated immune senescence and biological aging, which particularly affects the CD8 T-cell subsets.

Vaccine-Induced CD8+ T Cell Responses in Children: A Review of Age-Specific Molecular Determinants Contributing to Antigen Cross-Presentation

Infections are most common and most severe at the extremes of age, the young and the elderly. Vaccination can be a key approach to enhance immunogenicity and protection against pathogens in these vulnerable populations, who have a functionally distinct immune system compared to other age groups. More than 50% of the vaccine market is for pediatric use, yet to date vaccine development is often empiric and not tailored to molecular distinctions in innate and adaptive immune activation in early life. With modern vaccine development shifting from whole-cell based vaccines to subunit vaccines also comes the need for formulations that can elicit a CD8+ T cell response when needed, for example, by promoting antigen cross-presentation. While our group and others have identified many cellular and molecular determinants of successful activation of antigen-presenting cells, B cells and CD4+ T cells in early life, much less is known about the ontogeny of CD8+ T cell induction. In this review, we summarize the literature pertaining to the frequency and phenotype of newborn and infant CD8+ T cells, and any evidence of induction of CD8+ T cells by currently licensed pediatric vaccine formulations. In addition, we review the molecular determinants of antigen cross-presentation on MHC I and successful CD8+ T cell induction and discuss potential distinctions that can be made in children. Finally, we discuss recent advances in development of novel adjuvants and provide future directions for basic and translational research in this area.

CD4+CD38+ central memory T cells contribute to HIV persistence in HIV-infected individuals on long-term ART

Background

Despite the effective antiretroviral treatment (ART) of HIV-infected individuals, HIV persists in a small pool. Central memory CD4⁺ T cells (Tcm) make a major contribution to HIV persistence. We found that unlike HLA-DR, CD38 is highly expressed on the Tcm of HIV-infected subjects receiving ART for > 5 years. It has been reported that the half-life of total and episomal HIV DNA in the CD4⁺CD38⁺ T cell subset, exhibits lower decay rates at 12 weeks of ART. Whether CD38 contributes to HIV latency in HIV-infected individuals receiving long-term ART is yet to be addressed.

Methods

Peripheral blood mononuclear cells (PBMCs) were isolated from the whole blood of HIV-infected subjects receiving suppressive ART. The immunophenotyping, proliferation and apoptosis of CD4⁺ T cell subpopulations were detected by flow cytometry, and the level of CD38 mRNA and total HIV DNA were measured using real-time PCR and digital droplet PCR, respectively. A negative binomial regression model was used to determine the correlation between CD4⁺CD38⁺ Tcm and total HIV DNA in CD4⁺ T cells.

Results

CD38 was highly expressed on CD4⁺ Tcm cells from HIV infected individuals on long-term ART. Comparing with HLA-DR⁻Tcm and CD4⁺HLA-DR⁺ T cells, CD4⁺CD38⁺ Tcm cells displayed lower levels of activation (CD25 and CD69) and higher levels of CD127 expression. The proportion of CD38⁺ Tcm, but not CD38⁻ Tcm cells can predict the total HIV DNA in the CD4⁺ T cells and the CD38⁺ Tcm subset harbored higher total HIV DNA copy numbers than the CD38⁻ Tcm subset. After transfected with CD38 si-RNA in CD4⁺ T cells, the proliferation of CD4⁺ T cells was inhibited.

Conclusion

The current date indicates that CD4⁺CD38⁺ Tcm cells contribute to HIV persistence in HIV-infected individuals on long-term ART. Our study provides a potential target to resolve HIV persistence.

Elevated Eosinophils as a Feature of Inflammation Associated With Hypertension in Virally Suppressed People Living With HIV

Background

People living with HIV (PLWH) are at increased risk of cardiovascular disease, including hypertension, which persists despite effective plasma viral suppression on antiretroviral therapy. HIV infection is characterized by long‐term alterations in immune function, but the contribution of immune factors to hypertension in PLWH is not fully understood. Prior studies have found that both innate and adaptive immune cell activation contributes to hypertension.

Methods and Results

We hypothesized that chronic inflammation may contribute to hypertension in PLWH. To test this hypothesis, we enrolled a cohort of 70 PLWH (44% hypertensive) on a long‐term single antiretroviral therapy regimen for broad phenotyping of inflammation biomarkers. We found that hypertensive PLWH had higher levels of inflammatory cytokines, including tumor necrosis factor‐α receptor 1, interleukin‐6, interleukin‐17, interleukin‐5, intercellular adhesion molecule 1 and macrophage inflammatory protein‐1α. After adjustment for age, sex, and fat mass index, the circulating eosinophils remained significantly associated with hypertension. On the basis of these results, we assessed the relationship of eosinophils and hypertension in 2 cohorts of 50 and 81 039 similar HIV‐negative people; although eosinophil count was associated with prevalent hypertension, this relationship was abrogated by body mass index.

Conclusions

These findings may represent a unique linkage between immune status and cardiovascular physiological characteristics in HIV infection, which should be evaluated further.

Roles of CD38 in the Immune Response to Infection

CD38 is a multifunctional protein widely expressed in cells from the immune system and as a soluble form in biological fluids. CD38 expression is up-regulated by an array of inflammatory mediators, and it is frequently used as a cell activation marker. Studies in animal models indicate that CD38 functional expression confers protection against infection by several bacterial and parasitic pathogens. In addition, infectious complications are associated with anti-CD38 immunotherapy. Although CD38 displays receptor and enzymatic activities that contribute to the establishment of an effective immune response, recent work raises the possibility that CD38 might also enhance the immunosuppressive potential of regulatory leukocytes. This review integrates the current knowledge on the diversity of functions mediated by CD38 in the host defense to infection.

Relationship between CCR5(WT/Δ32) heterozygosity and HIV-1 reservoir size in adolescents and young adults with perinatally acquired HIV-1 infection

BACKGROUND

Several host factors contribute to human immunodeficiency virus (HIV) disease progression in the absence of combination antiretroviral therapy (cART). Among them, the CC-chemokine receptor 5 (CCR5) is known to be the main co-receptor used by HIV-1 to enter target cells during the early stages of an HIV-1 infection.

OBJECTIVE

We evaluated the association of CCR5^(WT/Δ32) heterozygosity with HIV-1 reservoir size, lymphocyte differentiation, activation and immunosenescence in adolescents and young adults with perinatally acquired HIV infection receiving cART.

METHODS

CCR5 genotype was analysed in 242 patients with vertically transmitted HIV-1 infection from Paediatric Spanish AIDS Research Network Cohort (coRISpe). Proviral HIV-1 DNA was quantified by digital-droplet PCR, and T-cell phenotype was evaluated by flow cytometry in a subset of 24 patients (ten with CCR5^(Δ32/WT) genotype and 14 with CCR5^(WT/WT) genotype).

RESULTS

Twenty-three patients were heterozygous for the Δ32 genotype but none was homozygous for the mutated CCR5 allele. We observed no difference in the HIV-1 reservoir size (455 and 578 copies of HIV-1 DNA per million CD4⁺ T cells in individuals with CCR5^(WT/WT) and CCR5^(Δ32/WT) genotypes, respectively; p 0.75) or in the immune activation markers between both genotype groups. However, we found that total HIV-1 DNA in CD4⁺ T cells correlated with the percentage of memory CD4⁺ T cells: a direct correlation in CCR5^(WT/Δ32) patients but an inverse correlation in those with the CCR5^(WT/WT) genotype.

CONCLUSIONS

This finding suggests a differential distribution of the viral reservoir compartment in CCR5^(WT/Δ32) patients with perinatal HIV infection, which is a characteristic that may affect the design of strategies for reservoir elimination.

Effect of cytomegalovirus co-infection on normalization of selected T-cell subsets in children with perinatally acquired HIV infection treated with combination antiretroviral therapy

Background

We examined the effect of cytomegalovirus (CMV) co-infection and viremia on reconstitution of selected CD4+ and CD8+ T-cell subsets in perinatally HIV-infected (PHIV+) children ≥ 1-year old who participated in a partially randomized, open-label, 96-week combination antiretroviral therapy (cART)-algorithm study.

Methods

Participants were categorized as CMV-naïve, CMV-positive (CMV+) viremic, and CMV+ aviremic, based on blood, urine, or throat culture, CMV IgG and DNA polymerase chain reaction measured at baseline. At weeks 0, 12, 20 and 40, T-cell subsets including naïve (CD62L+CD45RA+; CD95-CD28+), activated (CD38+HLA-DR+) and terminally differentiated (CD62L-CD45RA+; CD95+CD28-) CD4+ and CD8+ T-cells were measured by flow cytometry.

Results

Of the 107 participants included in the analysis, 14% were CMV+ viremic; 49% CMV+ aviremic; 37% CMV-naïve. In longitudinal adjusted models, compared with CMV+ status, baseline CMV-naïve status was significantly associated with faster recovery of CD8+CD62L+CD45RA+% and CD8+CD95-CD28+% and faster decrease of CD8+CD95+CD28-%, independent of HIV VL response to treatment, cART regimen and baseline CD4%. Surprisingly, CMV status did not have a significant impact on longitudinal trends in CD8+CD38+HLA-DR+%. CMV status did not have a significant impact on any CD4+ T-cell subsets.

Conclusions

In this cohort of PHIV+ children, the normalization of naïve and terminally differentiated CD8+ T-cell subsets in response to cART was detrimentally affected by the presence of CMV co-infection. These findings may have implications for adjunctive treatment strategies targeting CMV co-infection in PHIV+ children, especially those that are now adults or reaching young adulthood and may have accelerated immunologic aging, increased opportunistic infections and aging diseases of the immune system.

Early virological and immunological events in asymptomatic Epstein-Barr virus infection in African children

Epstein-Barr virus (EBV) infection often occurs in early childhood and is asymptomatic. However, if delayed until adolescence, primary infection may manifest as acute infectious mononucleosis (AIM), a febrile illness characterised by global CD8+ T-cell lymphocytosis, much of it reflecting a huge expansion of activated EBV-specific CD8+ T-cells. While the events of AIM have been intensely studied, little is known about how these relate to asymptomatic primary infection. Here Gambian children (14-18 months old, an age at which many acquire the virus) were followed for the ensuing six months, monitoring circulating EBV loads, antibody status against virus capsid antigen (VCA) and both total and virus-specific CD8+ T-cell numbers. Many children were IgG anti-VCA-positive and, though no longer IgM-positive, still retained high virus loads comparable to AIM patients and had detectable EBV-specific T-cells, some still expressing activation markers. Virus loads and the frequency/activation status of specific T-cells decreased over time, consistent with resolution of a relatively recent primary infection. Six children with similarly high EBV loads were IgM anti-VCA-positive, indicating very recent infection. In three of these donors with HLA types allowing MHC-tetramer analysis, highly activated EBV-specific T-cells were detectable in the blood with one individual epitope response reaching 15% of all CD8+ T-cells. That response was culled and the cells lost activation markers over time, just as seen in AIM. However, unlike AIM, these events occurred without marked expansion of total CD8+ numbers. Thus asymptomatic EBV infection in children elicits a virus-specific CD8+ T-cell response that can control the infection without over-expansion; conversely, in AIM it appears the CD8 over-expansion, rather than virus load per se, is the cause of disease symptoms.

Specific patterns of CD4-associated immunosenescence in vertically HIV-infected subjects

Vertical transmission of human immunodeficiency virus (HIV) represents an important world-wide health problem although the incidence in developed countries has been drastically reduced by the extensive use of highly active antiretroviral therapy. Vertically HIV-infected subjects have been exposed to the virus during the maturation of their immune systems and have suffered a persistent chronic activation throughout their lifetime; the consequences of this situation for their immune system are not fully understood. The objective of this study was to analyse immunosenescence-related parameters in different CD4 T-cell subsets. Fifty-seven vertically HIV-infected subjects and 32 age-matched healthy subjects were studied. Activation (HLA(-) DR(+) ), senescence (CD28(-) CD57(+) ) and proliferation (Ki67(+) ) were analysed on different CD4 T-cell subsets: naive (CD45RA(+) CD27(+) ), memory (CD45RO(+) CD27(+) ), effector memory (CD45RO(+) CD27(-) ) and effector memory RA (CD45RA(+) CD27(-) ). Compared with healthy subjects, vertically HIV-infected subjects showed increased naive and memory CD4 T-cell frequencies (p 0.035 and p 0.010, respectively) but similar frequencies of both effector subsets. Whereas naive CD4 T cells were not further altered, memory CD4 T cells presented increased levels of senescence and proliferation markers (p <0.001), effector memory CD4 T cells presented increased levels of activation, senescence and proliferation markers (p <0.001) and effector memory RA CD4 T cells presented increased levels of activation and senescence (p <0.001) compared with healthy subjects. Despite long periods of infection, vertically HIV-infected subjects show specific patterns of immunosenescence, revealing a preserved CD4 T-cell homeostasis for subset differentiation and distribution. Nevertheless, excepting the naive subpopulation, all subsets experienced some immunosenescence, pointing to uncertain consequences of the future aging process in these subjects.

T-cell activation and neurodevelopmental outcomes in perinatally HIV-infected children

OBJECTIVE

To evaluate baseline T-cell activation and neurodevelopmental outcomes over time in a cohort of perinatally HIV-infected (PHIV-infected) children with severe disease.

DESIGN

Pediatric AIDS Clinical Trials Group protocol 366 (PACTG 366) was a partially randomized, open-label, multicenter 96-week antiretroviral treatment-algorithm study. Neurodevelopmental status, measured by age-dependent evaluations (Bayley scales of infant development-II; Wechsler preschool and primary scale of intelligence-revised; Wechsler intelligence scale for children-III), was a secondary outcome.

METHODS

Linear mixed models were used to assess the baseline and follow-up neurodevelopmental outcomes in relation to immune activation, measured by CD38 and human leukocyte antigen (HLA) DR expression on peripheral CD4(+) and CD8(+) T cells at study baseline. Models were adjusted for age, sex, race/ethnicity, baseline viral load, baseline CD4%, cytomegalovirus (CMV) infection status at entry, study treatment arms, central nervous system penetrance score of antiretroviral regimen at entry, and viral load response 16 weeks postentry.

RESULTS

Among 126 PACTG 366 enrollees who were at least 1 year old and had both immune activation and age-appropriate neurodevelopmental assessments at baseline, 80 (63%) were black non-Hispanic, 71 (56%) males, 122 (97%) were on antiretrovirals, and 45 (36%) were in Centers for Disease Control and Prevention (CDC) disease category C at entry. CD4(+)CD38(+)HLADR(+)%, CD4(+)CD38(-)HLADR(+)%, and CD8(+)CD38(+)HLADR(+)% were positively associated with full-scale Intelligence Quotient scores (FSIQ) (slope = 0.18, 0.70, and 0.15, respectively; P = 0.02, 0.03, and 0.04, respectively). CD4(+)CD38(+)HLADR(-)% was negatively associated with FSIQ (slope =  -0.16, P = 0.01).

CONCLUSION

Contrary to HIV-infected adults, in PHIV-infected children higher CD4(+)CD38(+)HLADR(+)% may be associated with a neuroprotective effect and higher percentage of CD4(+)CD38(+) but HLADR(-) T cells may be deleterious.

Further evidence that the expression of CD38 and HLA-DR(+) in CD8(+) lymphocytes does not correlate to disease progression in HIV-1 vertically infected children

BACKGROUND

In adults, an increase in CD8(+)CD38(+) T cell levels is a strong indicator of disease progression in HIV infection. However, in children, data are conflicting. Slow-progressing children (SPC) provide an exceptional resource for the investigation and clarification of the immunological and virological mechanisms of natural control of HIV infection and can be used to investigate prognostic indicators of disease progression.

OBJECTIVES

To investigate the immune activation status and T regulatory (Treg) cell levels in SPC.

STUDY DESIGN

A cross-sectional study was carried out on 28 children 8 years old and older who were vertically infected with HIV. The children were stratified into 3 groups according to their clinical outcome: SPC (anti-retroviral-therapy-naïve; ≥8 years-old; CD4 ≥20%; viral load <25,000 copies), IF/VF (anti-retroviral-therapy but with no therapeutic response), and IS/VS (anti-retroviral therapy with good therapeutic response). Uninfected children (NI) were assessed as healthy control group.

RESULTS

A higher percentage of activated CD8(+) T cells were found in all HIV infected children, regardless of the evolution of disease. The activation of CD8(+) T cells was not associated with either viral load or the percentage of CD4(+) T cells. In addition, Treg cell levels did not show any correlation with the clinical outcome or the activation status of CD8(+) T cells.

CONCLUSIONS

HIV-1-infected children presented an increased percentage of activated CD8(+) T cells and an unaltered percentage of Treg cells, regardless of their clinical evolution. Thus, these immunological parameters should not be used for prognostic evaluation.

HIV type 1 viremia on ART is positively associated with polyclonal T cell proliferation in subjects with T cell IFN-gamma secretion levels comparable to those of uninfected subjects

We investigated the association between plasma HIV-1 RNA, immune activation, and polyclonal T cell function in viremic subjects whether on or off antiretroviral therapy (ART). The surface expression of activation/functional molecules on T cells and monocytes as well as cytokine secretion and T cell proliferation were assessed in 23 HIV-1(-) and 79 HIV-1(+)-infected subjects with different levels of viral suppression and CD4(+) T cell count >250 cells/mm(3) for >6 months. Viral replication was associated with increased T cell and monocyte activation irrespective of ART. In subjects with a detectable viral load on ART, we found a positive association with anti-CD3/CD28-induced T cell proliferation compared to patients with undetectable viral load (<400 copies/ml). No difference among groups was observed for anti-CD3/CD28-mediated IFN-gamma responses. The presence of an unexpected positive association between polyclonal T cell proliferation and viral load in subjects with levels of T cell IFN-gamma responses comparable to those of uninfected subjects is of potential relevance to an increase in T cell activation response before the loss of polyclonal cytokine secretion and proliferation observed with disease progression. This finding suggests that T cell hyperresponsiveness may play a role in the pathogenesis of immune comorbidities on ART.

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.

Correlates for disease progression and prognosis during concurrent HIV/TB infection

Mycobacterium tuberculosis (Mtb) and the human immunodeficiency virus (HIV) are both life-threatening pathogens in their own right, but their synergic effects on the immune system during co-infection markedly enhance their effect on the host. This review focuses on the bidirectional interaction between HIV and Mtb and discusses the relevance of sputum smear examination, CD4+ counts, viral load at baseline and after initiation of anti-retroviral therapy, as well as additional existing and new potential immune correlates of disease progression and prognosis. These markers include beta2-microglobulin, neopterin, tumor necrosis factor receptor II (TNFRII), CD8+/CD38+, soluble urokinase plasminogen activator receptor (suPAR) and CXCL10 (or IP-10).

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.

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.

[Changes in CD4+ and CD8+ T-cell subsets in HIV-infected children differently correlate with viral replication and thymic function]

BACKGROUND AND OBJECTIVE

We intended to study the relationship between T-cell subsets with plasmatic detectable viral load (VL) and T-receptor excision circles (TREC).

PATIENTS AND METHOD

Twenty HIV-infected children on highly active antiretroviral therapy (HAART) were recruited in a 1-year longitudinal retrospective study. We analyzed the relationship between changes in peripheral blood T-cell subsets, VL and TREC markers by lineal regression.

RESULTS

Memory and activated CD4+ T-cells increases had a negative association with log10 TRECs increases. However, naive CD4+ T-cells increases had a positive association with log10 TRECs increases. In contrast, memory, activated and effector CD8+ T-cells increases positively correlated with log10 VL increases. On the other hand, naive CD8+ T-cells increases had a negative association with log10 VL increases.

CONCLUSIONS

CD4+ and CD8+ T-cells subsets change in a different way as a response to the changes produced by HAART in HIV vertically infected children. CD4+ T-cells are more dependent on thymic function and CD8+ T-cells are more dependent on viral replication. Thus, the decline in cellular activation would allow the production of more naive T-cells by the thymus.

CD38 expression in CD8+ T cells predicts virological failure in HIV type 1-infected children receiving antiretroviral therapy

An observational study of children vertically infected with human immunodeficiency virus type 1 (HIV-1) was performed to determine the role of CD38 expression in CD8(+) T cells as prognostic marker of virological failure in children receiving HAART. We studied 42 children who were receiving antiretroviral therapy and who had an undetectable virus load (uVL), and we found a negative correlation between CD38 expression in CD8(+) T cells and the duration of uVL. We selected 17 HIV-1-infected children with CD38 values close to the baseline level (i.e., the first uVL achieved), and we distributed the children into 2 groups on the basis of median CD38 value in CD8(+) T cells. Children with CD38 values in CD8(+) T cells that were higher than the median had a higher incidence and relative risk of virological failure than did those with values lower than the median. In conclusion, we demonstrate for the first time that CD8(+)CD38(+) T cell count is a good prognostic marker of therapeutic failure in HIV-1-infected children.

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.

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.

HIV, 'an evolving species'. Roles of cellular activation and co-infections

Each small variation of the genome of a species can be preserved if it is useful for the survival of the species in a given environment. Within this framework, the finality of the biological cycle of HIV consists in a search for harmony (biological coherence) with man, which is to say a stable condition. Cellular activation appears to be the strategy developed by HIV in order to achieve this coherence. The price of this strategy is the AIDS. The first contact between HIV and immune system appears to determine the subsequent clinical outcome and the future of HIV. Lymphocytic activation varies during the course of the vital cycle of HIV. For each individual, this lymphocytic activation depends on both the HLA repertoire acquired during thymic ontogenesis and the antigenic experience before and after HIV infection. Thus intercurrent infections alter the immune condition of the organism and influence the outcome of HIV. We described a synthetic analysis of the effects of HIV on the surface protein expression and the cellular activation pathways which should provide insights in the evolutionary relationship between HIV and man and should permit to do a more physiological therapeutic approach.

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.

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.

CD38 expression on CD8(+) T cells as a prognostic marker in vertically HIV-infected pediatric patients

Increased expression of CD38 on CD8(+) T cells is associated with activation of the immune system, progression of HIV disease, and death in adults. The prognostic significance of these cells in HIV-infected children, where the picture is complicated by age-related differences in CD38 expression, remains controversial. Measuring the unimodal expression of CD38 on CD8(+) T cells in adults and children by flow cytometry is best accomplished by quantitating the antigen on the cell surface. To our knowledge, this technique has not previously been reported in a pediatric population. Vertically HIV-infected children were age matched for mild (n = 26) and severe (n = 23) clinical disease. Eleven age-matched HIV-negative controls were included for comparison. Quantitation of CD38 on CD8(+) T cells was performed at baseline and 1 y later. The ages of the children in the three clinical groups did not differ significantly (p = 0.6004). HIV-infected children had significantly increased CD38 measurements in comparison with the HIV-negative controls (p = 0.0131), and the severe disease group tended to have higher measurements than the mild disease group. Increased CD38(+)CD8(+) T cells were significant predictors of death within the first year (p = 0.043). These findings support the view that increased CD38 expression on CD8(+) T cells has the same prognostic significance in pediatric as in adult HIV disease.

[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.

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.

Comparison of CD8(+) T-cell subsets in HIV-infected rapid progressor children versus non--rapid progressor children

BACKGROUND

CD8(+) T-cell subsets have not been adequately described in HIV-infected (HIV(+)) children classified with respect to disease progression as rapid-progressors (RPs) and non-rapid progressors (non-RPs).

OBJECTIVE

The purpose of this investigation was to determine the distribution of CD8(+) T-cell subsets in HIV(+) children and correlate the findings with degree of immunosuppression and HIV viral burden.

METHODS

By means of 3-color flow cytometry, percentages of CD38(+)DR(+), CD28(+), and CD57(+) CD8(+) T-cell subsets were examined in RP (n = 15) and non-RP (n = 36) HIV(+) children and in HIV-exposed but uninfected (n = 11) and HIVunexposed (n = 8) children. The CD8(+) T-cell subsets were correlated with mean CD4(+) T-cell percentages and HIV RNA levels. Analysis of covariance was used for group comparisons for the control of the covariate of age.

RESULTS

The HIV-exposed and HIV-unexposed controls were not different from each other in CD8(+) T-cell subset percentages, except that the DR(-)CD38(+)CD8(+) T-cell percentages were higher in the exposed controls than in the unexposed controls. RPs had a higher mean percentage of DR(+)CD38(+)CD8(+) T cells than non-RPs and both control groups, and RPs had higher viremia than non-RPs. CD38(+)CD8(+) T-cell percentages did not correlate with viral burden as it has been seen to do in HIV(+) adults. Percentages of CD28(+)CD8(+) T cells were lower in HIV-infected children than in controls. There was a positive correlation of percentage of CD28(+)CD57(-)CD8(+) T cells with CD4(+) T-cell percentages in each HIV-infected group.

CONCLUSION

CD8(+) T cells become activated (dual expression of DR and CD38) and lose CD28, some acquiring CD57, in relation to rapidity of disease progression in pediatric HIV infection.

[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.

Immunophenotypic analysis of HIV-infected children: alterations within the first year of life, changes with disease progression, and longitudinal analyses of lymphocyte subsets

Perinatal infection with human immunodeficiency virus (HIV) results in tremendous activation of the pediatric immune system. An important component of understanding the pathogenesis of this disease is to characterize and quantify antigenic indicators of activation within the peripheral lymphocyte population. We measured T-lymphocyte activation and maturation antigens in a cohort of 112 HIV-infected children treated with antiretroviral therapy according to the current standard of care. Changes in expression of CD95, HLA-DR, and CD45RO were evident in 22 HIV-infected children younger than 1 year of age. A comparison of phenotypic profiles of children in mild, moderate, and severe immune categories revealed perturbations of CD28, CD38, CD45RA, CD45RO, CD95, and HLA-DR. Finally, a novel analysis of 56 HIV-infected children based on the repeated collection of data over time (median of seven observations over 33 months) demonstrated a strong negative correlation between the percentage CD4 and the percentage of CD45RO, CD95, and HLA-DR on both CD4 and CD8 cells. Our data implicate persistent immune activation, beginning within the first year of life, as a major driving force in the pathogenesis of perinatally acquired HIV disease.

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.

TT virus infection in human immunodeficiency virus type 1 infected mothers and their infants

Serum TT virus (TTV) DNA was determined in 83 human immunodeficiency virus type 1 (HIV 1) infected mothers [46 intravenous drug user and 37 non-intravenous drug user women] and their infants. Twenty-nine (34.9%) mothers were TTV infected. Infection was more frequent among intravenous drug user than non-intravenous drug user mothers [21/46 (45.6%) vs. 8/37 (21.6%); relative risk (RR): 2.1; 95% confidence limits (95% CL): 1.1-4.2; P = 0.023] and among intravenous drug users who carried on injecting than in those who had given it up [10/14 (71.4%) vs. 11/32 (34.3%); RR: 2.1 (95%CL: 1.2-3.7); P = 0. 021]. Infection was not related to age, CD4-positive T-lymphocyte counts, HIV 1 load, hepatitis B (HBV), G/GB-C (GBV-C/HGV), C (HCV) virus exposure. Eight (27.5%) infants born to TTV infected (but none of those born to TTV uninfected) mothers were TTV infected at a median age of 1.5 (range: 0.6-2.8) months. Infants born by vaginal/emergency caesarean delivery were more frequently infected than those born by elective caesarean delivery [7/16 (43.7%) vs. 1/13 (7.6%); RR: 2.1; 95%CL: 1.2-3.5; P = 0.033]. Infection in infants was not related to maternal CD4-positive T-lymphocyte counts, HIV 1 load, and HIV 1, HBV, GBV-C/HGV, or HCV transmission. No infant became TTV infected thereafter. No TTV infected child [follow-up: 31 (median; range: 6-60) months] showed signs of liver disease; five infants cleared TTV DNA after 22 (median; range: 6-60) months. TTV infection in HIV 1 infected women is prevalently related to intravenous drug user. The findings suggest that infants may acquire TTV at birth. Infection may persist without evident liver disease.

Interleukin-6 release by cultured peripheral blood mononuclear cells inversely correlates with height velocity, bone age, insulin-like growth factor-I, and insulin-like growth factor binding protein-3 serum levels in children with perinatal HIV-1 infection

Spontaneous and phytohemagglutinin (PHA)-stimulated interleukin (IL)-6 release by cultured peripheral blood mononuclear cells was related to height velocity, bone age, insulin-like growth factor-I (IGF-I), and IGF binding protein-3 (IGFBP-3) serum level standard deviation scores (SDS) of 32 children [aged 91 (median; range 13-151) months] with human immunodeficiency virus-type 1 (HIV-1) perinatal infection and severe disease. Spontaneous and PHA-stimulated IL-6 release inversely correlated with height velocity, bone age, IGF-I, and IGFBP-3 SDS. Ten children with height velocity SDS </= -2, compared to 22 children with height velocity SDS > -2, showed higher spontaneous and PHA-stimulated IL-6 release and lower IGF-I and IGFBP-3 SDS (irrespective of CD4-positive T-lymphocyte counts, viral load, liver disease, or nutrition status). IL-6 overproduction may be a mechanism of IGF-I and IGFBP-3 down-regulation and impaired linear growth in children with perinatal HIV-1 infection. Growth-promoting strategies, including targeted anticytokine treatments, could be devised for such children.

Effects of the human CD38 glycoprotein on the early stages of the HIV-1 replication cycle

CD38 displays lateral association with the HIV-1 receptor CD4. This association is potentiated by the HIV-1 envelope glycoprotein gp120. The aim of this work was to evaluate the CD38 role in T cell susceptibility to HIV-1 infection. Using laboratory X4 HIV-1 strains and X4 and X4/R5 primary isolates, we found that CD38 expression was negatively correlated to cell susceptibility to infection, evaluated as percentage of infected cells, release of HIV p24 in the supernatants, and cytopathogenicity. This correlation was at first suggested by results obtained in a panel of human CD4(+) T cell lines expressing different CD38 levels (MT-4, MT-2, C8166, CEMx174, Supt-1, and H9) and then demonstrated using CD38 transfectants of MT-4 cells (the line with the lowest CD38 expression). To address whether CD38 affected viral binding, we used mouse T cells that are non-permissive for productive infection. Gene transfection in mouse SR.D10.CD4(-).F1 T cells produced four lines expressing human CD4 and/or CD38. Ability of CD4(+)CD38(+)cells to bind HIV-1 or purified recombinant gp120 was significantly lower than that of CD4(+)CD38(-) cells. These data suggest that CD38 expression inhibits lymphocyte susceptibility to HIV infection, probably by inhibiting gp120/CD4-dependent viral binding to target cells.-Savarino, A., Bottarel, F., Calosso, L., Feito, M. J., Bensi, T., Bragardo, M., Rojo, J. M., Pugliese, A., Abbate, I., Capobianchi, M. R., Dianzani, F., Malavasi, F., and Dianzani, U. Effects of the human CD38 glycoprotein on the early stages of theHIV-1 replication cycle.

Viral load and CD69 molecule expression on freshly isolated and cultured mitogen-stimulated lymphocytes of children with perinatal HIV-1 infection

HIV-1 in adults changes the proportion of mitogen-stimulated lymphocytes expressing the CD69 activation molecule, but little is known about this molecule expression on lymphocytes of HIV-1-infected (HIV-1+) children. Freshly isolated CD3+, CD4+, CD8+ and CD19+ and phytohaemagglutinin (PHA)-stimulated CD3+, CD4+ and CD8+ lymphocytes co-expressing CD69 were investigated cross-sectionally (adopting a MoAb double-staining technique) in 24 HIV-1+ children with severe disease and given anti-retroviral therapy and in 24 age-matched healthy children. CD69 results in HIV-1+ children were correlated with plasma HIV-1 RNA load prospectively determined. HIV-1+ compared with healthy children had higher frequencies of freshly isolated CD3+CD69+ (2.4 +/- 2.2% versus 0.9 +/- 0.5%; P = 0.002) and CD8+CD69+ (1.5 +/- 1.1% versus 0. 5 +/- 0.2%; P < 0.0001) lymphocytes. The frequencies of CD4+CD69+ and CD19+CD69+ lymphocytes were similar. High viral load correlated with an elevated proportion of freshly isolated CD3+CD69+ and CD8+CD69+ lymphocytes. HIV-1+ children showed reduced frequencies of PHA-stimulated CD3+CD69+ (60.7 +/- 7.6% versus 86.1 +/- 7.6%; P < 0. 001), CD4+CD69+ (73.6 +/- 18.2% versus 92.6 +/- 5.1%; P < 0.001), and CD8+CD69+ (51.0 +/- 19.1% versus 65.3 +/- 15.4%; P = 0.007) lymphocytes. Virologic worsening within 6 months correlated with a low proportion of PHA-stimulated CD3+CD69+ and CD8+CD69+ lymphocytes. CD69 molecule expression reflected the coexistence of immune activation and immune deficiency in HIV-1 infection. Changes partly differed from those observed in HIV-1+ adults. CD8+CD69+ (but not CD4+CD69+) lymphocyte proportion correlated with virologic course, and an impaired ability of CD8+ lymphocytes to express CD69 upon PHA stimulation preceded a virologic worsening.

Low IgG3 and high IgG4 subclass levels in children with advanced human immunodeficiency virus-type 1 infection and elevated IgE levels

BACKGROUND

IgG3 and IgG4 levels are not always changed in children perinatally infected with human immunodeficiency virus-type 1 (HIV-1). Elevated IgE levels hallmark the TH1 to TH2 switch occurring in advanced infection and such an unbalanced cytokine network may affect the IgG subclass production.

OBJECTIVE

To examine the different behaviour of IgG3 and IgG4 in the light of elevated IgE levels.

METHODS

IgE and IgG subclass levels were cross-sectionally determined (by radioimmunoassay and enzyme-linked immunosorbent assay, respectively) in 54 HIV-1 perinatally infected children. IgE levels beyond the upper 95% confidence limits (95%CL) of the age-related reference values defined elevated IgE levels. Since immunoglobulin levels physiologically vary with age, individual z-scores of isotype levels were calculated using the upper 95%CL of age-related reference values.

RESULTS

Fifteen (27.7%) children had elevated IgE levels. They had lower IgG3 (mean +/- standard deviation: -1.4+/-0.9 versus 6.9+/-0.9; P < .0001) and higher IgG4 (3.1+/-0.6 versus 0.2+/-0.3; P < .0001) z-scores compared with children without elevated IgE levels. Similar IgG1 (11.7+/-1.8 versus 12.6+/-1.3) and IgG2 (-0.22+/-0.8 versus -0.19+/-0.6) z-scores were found. In children with elevated IgE levels, IgE and IgG3 z-scores inversely correlated (r = -0.867; P < .0001), IgE and IgG4 z-scores directly correlated (r = 0.831; P < .0001) and IgG3 and IgG4 z-scores inversely correlated (r = -0.745; P < .001).

CONCLUSION

Low IgG3 and high IgG4 levels may be present in HIV-1 advanced disease with elevated IgE levels. Changes may be in line with the TH1 to TH2 switch and contribute to disease progression.

Interleukin-6 synthesis and IgE overproduction in children with perinatal human immunodeficiency virus-type 1 infection

BACKGROUND

Unbalanced interleukin network and elevated IL-6 synthesis are suggested mechanisms of immunoglobulin overproduction in children with perinatal human immunodeficiency virus-type 1 (HIV-1) infection.

OBJECTIVE

To investigate whether elevated IL-6 synthesis is a general mechanism of immunoglobulin overproduction in perinatal HIV-1 infection.

METHODS

In vitro spontaneous and phytohaemoagglutinin (PHA)-stimulated IL-6 and IL-2 synthesis, serum IgE, IgG, IgA, and IgM levels, CD4+ T-lymphocyte counts, and HIV-1 RNA copy numbers were cross-sectionally determined in 31 children with perinatal HIV-1 infection. Children with immunoglobulin z-scores in the highest quartile were defined as children with high immunoglobulin level. Relationships between interleukin synthesis, high immunoglobulin levels, and HIV-1 related disease were studied.

RESULTS

Children with high IgE levels had higher spontaneous IL-6 synthesis (1337 +/- 138 pg/mL) compared with those without high IgE levels (861 +/- 194 pg/mL; P < .001). By contrast, spontaneous IL-6 synthesis was similar in children with or without high IgG, IgA, or IgM levels. Decreased PHA-stimulated IL-2 synthesis, low CD4+ lymphocyte counts, elevated HIV-1 RNA copy numbers, and severe disease correlated with high IgE (but not IgG, IgA, and IgM) levels. IgG, IgA, and IgM levels correlated with each other, but not with IgE levels.

CONCLUSION

The increased IL-6 synthesis in HIV-1+ children may affect IgE rather than other immunoglobulin isotype levels. Overall results suggest that IgE and IgG, IgA, IgM overproduction have distinct underlying mechanisms.