Polyfunctional CD8+ T-Cell Response to Autologous Peptides from Protease and Reverse Transcriptase of HIV-1 Clade B.

BACKGROUND: The diversity of the HIV proteome influences the cellular response and development of an effective vaccine, particularly due to the generation of viral variants with mutations located within CD8+ T-cell epitopes. These mutations can affect the recognition of the epitopes, that may result in the selection of HIV variants with mutated epitopes (autologous epitopes) and different CD8+ T-cell functional profiles. OBJECTIVE: To determine the phenotype and functionality of CD8+ T-cell from HIV-infected Colombian patients in response to autologous and consensus peptides derived from HIV-1 clade B protease and reverse transcriptase (RT). METHODS: By flow cytometry, we compared the ex vivo CD8+ T-cell responses from HIV-infected patients to autologous and consensus peptides derived from HIV-1 clade B protease and RT, restricted by HLA-B*35, HLA-B*44 and HLA-B*51 alleles. RESULTS: Although autologous peptides restricted by HLA-B*35 and HLA-B*44 did not show any differences compared with consensus peptides, we observed the induction of a higher polyfunctional profile of CD8+ T-cells by autologous peptides restricted by HLA-B*51, particularly by the production of interferon-γ and macrophage inflammatory protein-1ß. The response by different memory CD8+ T-cell populations was comparable between autologous vs. consensus peptides. In addition, the magnitude of the polyfunctional response induced by the HLA-B*51-restricted QRPLVTIRI autologous epitope correlated with low viremia. CONCLUSION: Autologous peptides should be considered for the evaluation of HIV-specific CD8+ Tcell responses and to reveal some relevant epitopes that could be useful for therapeutic strategies aiming to promote polyfunctional CD8+ T-cell responses in a specific population of HIV-infected patients.

Particular activation phenotype of T cells expressing HLA-DR but not CD38 in GALT from HIV-controllers is associated with immune regulation and delayed progression to AIDS.

The spontaneous control of HIV replication in HIV-controllers underlines the importance of these subjects for exploring factors related to delayed progression. Several studies have revealed fewer immune alterations and effector mechanisms related to viral control, mainly in peripheral blood, in these individuals compared to normal progressors. However, immune characterization of gut-associated lymphoid tissue (GALT), the major target of infection, has not been thoroughly explored in these subjects. We evaluated the following parameters in GALT samples from 11 HIV-controllers and 15 HIV-progressors: (i) frequency and activation phenotype of T cells; (ii) expression of transcription factors associated with immune response profiles; and (iii) frequency of apoptotic cells. Interestingly, HIV-controllers exhibited a particular activation phenotype, with predominance of T cells expressing HLA-DR but not CD38 in GALT. This phenotype, previously associated with better control of infection, was correlated with low viral load and higher CD4(+) T cell count. Furthermore, a positive correlation of this activation phenotype with higher expression of Foxp3 and RORγT transcription factors suggested a key role for Treg and Th17 cells in the control of the immune activation and in the maintenance of gut mucosal integrity. Although we evaluated apoptosis by measuring expression of cleaved caspase-3 in GALT, we did not find differences between HIV-controllers and HIV-progressors. Taken together, our findings suggest that predominance of HLA-DR(+) T cells, along with lower immune activation and higher expression of transcription factors required for the development of Treg and Th17 cells, is associated with better viral control and delayed progression to AIDS.

Spontaneous HIV Controllers Exhibit Preserved Immune Parameters in Peripheral Blood and Gastrointestinal Mucosa.

BACKGROUND: HIV infection induces several gradual alterations on the peripheral and mucosal immune systems, with different magnitudes between infected individuals. In this regard, spontaneous HIV controllers exhibit either low or undetectable viral loads in the absence of treatment along with decreased immune alterations compared to HIV progressors. Yet, it is unknown how similar immune peripheral and mucosal parameters are when comparing HIV controllers to uninfected individuals. METHODS: We evaluated a cohort of 11 HIV controllers who were compared to 20 seronegative donors. Peripheral blood (PB) and gut associated lymphoid tissue (GALT) samples were obtained to analyze the following: 1) the frequency and phenotype of immune cells by flow cytometry; 2) the expression of apoptotic molecules by immunohistochemistry; 3) the expression of transcriptional factors associated with T cell profiles by real time PCR; and 4) the serum level of microbial translocation by an enzymatic reaction. RESULTS: We found that HIV controllers have a conserved frequency of most immune cell populations in PB and GALT, but a reduced percentage of CD4 T cells. The immune activation levels were similar in both groups of individuals, as well as the expression of cleaved caspase-3, transcriptional factors, and the level of microbial translocation. Interestingly, the frequency of CD8 T cells expressing HLA-DR but not CD38, previously associated with high effector functions, were preserved in HIV controllers. CONCLUSIONS: Our results suggest that despite the infection, HIV controllers have preserved immune parameters, which can be associated with the spontaneous control of viral replication.

Statins increase the frequency of circulating CD4+ FOXP3+ regulatory T cells in healthy individuals.

Statins have been shown to modulate the number and the suppressive function of CD4(+)FOXP3(+) T cells (Treg) in inflammatory conditions. However, it is not well established whether statin could also affect Treg in absence of inflammation. To address this question, eighteen normocholesterolemic male subjects were treated with lovastatin or atorvastatin daily for 45 days. The frequency and phenotype of circulating Treg were evaluated at days 0, 7, 30, and 45. mRNA levels of FOXP3, IDO, TGF-ß, and IL-10 were measured in CD4(+) T cells. We found that both statins significantly increased Treg frequency and FOXP3 mRNA levels at day 30. At day 45, Treg numbers returned to baseline values; however, TGF-ß and FOXP3 mRNA levels remained high, accompanied by increased percentages of CTLA-4- and GITR-expressing Treg. Treg Ki-67 expression was decreased upon statin treatment. Treg frequency positively correlated with plasma levels of high-density lipoprotein cholesterol (HDL-c), suggesting a role for HDL-c in Treg homeostasis. Therefore, statins appear to have inflammation-independent immune-modulatory effects. Thus, the increase in Treg cells frequency likely contributes to immunomodulatory effect of statins, even in healthy individuals.

Spontaneous control of HIV replication, but not HAART-induced viral suppression, is associated with lower activation of immune cells.

HIV replication control is important to reduce AIDS progression. We determined frequency and activation status of immune cells in spontaneous HIV controllers vs. individuals with highly active antiretroviral therapy (HAART)-controlled viral load. HIV controllers exhibited significantly higher frequency of CD4 T cells and myeloid dendritic cells compared with HAART-controlled viral load. Additionally, HIV controllers have a significantly lower percentage of cells expressing activation markers on CD4 and CD8 T cells, myeloid dendritic cells, and natural killer cells. These findings suggest that during HIV infection, conservation of a normal frequency and physiological range of immune activation is associated with spontaneous, but not HAART-induced, control of viral replication.

Las células natural killer y su papel en la respuesta inmunitaria durante la infección por el virus de la inmunodeficiencia humana tipo-1 / Natural killer cells and their role in the immune response during Human immunodeficiency virus type-1 infection

Durante la infección por el virus de la inmunodeficiencia humana tipo-1 (VIH-1) se presentan alteraciones en la frecuencia, el fenotipo y la función de las células NK, lo cual reduce su capacidad antiviral y se correlaciona con el incremento de la carga viral y la progresión a sida. Sin embargo, los estudios en individuos que presentan resistencia natural al VIH-1 han mostrado que estas células intervienen en el control de la replicación viral, con efectos antivirales directos y con la activación de células dendríticas, otro componente de la inmunidad innata. A pesar de que estos linfocitos no poseen receptores antigénicos específicos, recientemente se ha reportado su capacidad para responder a péptidos del VIH-1. Aunque el mecanismo no está completamente elucidado, es indudable que este hallazgo abre un nuevo panorama en el estudio de nuevas alternativas terapéuticas o preventivas contra la infección por VIH-1 que involucren a las células NK (AU)

During human immunodeficiency virus type-1 (HIV-1) infection there are several changes in the frequency, phenotype and function of NK cells, altering their antiviral response. This is correlated with increased viral loads, and AIDS progression. However, studies in individuals with natural resistance to HIV-1 infection have shown that NK cells are very important incontrolling viral replication, not only for their antiviral activity, but also because of their effects on the activity of other innate immune cells, such as dendritic cells. NK cells do not have antigen receptors, but it has been recently reported that they can specifically respond to HIV-1 peptides. Although the mechanism is not fully elucidated, this finding open more options in the study of new therapeutic or preventative strategies against HIV-1 infection (AU)

In vivo effect of statins on the expression of the HIV co-receptors CCR5 and CXCR4.

BACKGROUND: During the HIV-1 replication cycle, several molecules including chemokine receptors and cholesterol are crucial, and are therefore potential targets for therapeutic intervention. Indeed statins, compounds that inhibit cellular synthesis of cholesterol and have anti-inflammatory and immunomodulatory properties were shown to inhibit HIV-1 infection by R5 tropic strains but not by X4 strains in vitro, mainly by altering the chemokine receptor/ligands axes. Therefore, the objective of this study was to characterize in vivo, the capacity of statins to modulate in HIV seronegative and chronically HIV-1-infected adults the expression of CCR5 and CXCR4, of their ligands and the tropism of circulating HIV-1 strains. METHODS: Samples from asymptomatic HIV-1-infected adults enrolled in a clinical trial aimed at evaluating the antiretroviral activity of lovastatin were used to evaluate in vivo the modulation by lovastatin of CCR5, CXCR4, their ligands, and the shift in plasma viral tropism over one year of intervention. In addition, ten HIV negative adults received a daily oral dose of 40 mg of lovastatin or 20 mg of atorvastatin; seven other HIV negative individuals who received no treatment were followed as controls. The frequency and phenotype of immune cells were determined by flow-cytometry; mRNA levels of chemokine receptors and their ligands were determined by real-time PCR. Viral tropism was determined by PCR and sequencing, applying the clonal and clinical model of analyses. RESULTS: Our study shows that long-term administration of lovastatin in HIV-infected individuals does not induce a shift in viral tropism, or induce a significant modulation of CCR5 and CXCR4 on immune cells in HIV-infected patients. Similar results were found in HIV seronegative control subjects, treated with lovastatin or atorvastatin, but a significant increase in CCL3 and CCL4 transcription was observed in these individuals. CONCLUSIONS: These findings suggest that long-term administration of statins at therapeutic doses, does not significantly affect the expression of HIV-1 co-receptors or of their ligands. In addition it is important to point out that based on the results obtained, therapeutic administration of statins in HIV-infected patients with lipid disorders is safe in terms of selecting X4 strains.

Randomized clinical trial of lovastatin in HIV-infected, HAART naïve patients (NCT00721305).

BACKGROUND: Evidence suggests that statins may modify the immune response against HIV. The aim was to evaluate the antiretroviral and immunomodulatory effects of lovastatin in HIV-infected patients, naïve for antiretroviral therapy. METHODS: Randomized, double-blinded, placebo-controlled, phase-II clinical trial. Primary outcomes were plasma viral load and circulating CD4+ T cell count, after 6 and 12 months of treatment; secondary outcomes were CD8+ T cell count, expression of activation markers (CD38 and HLA-DR) on T cells, and clinical outcomes. With a power of 90% to detect both a decrease of 0.3 log10 in plasma HIV-1 RNA copies and an increase of 20% in the CD4+ T cell count, we estimated a required sample size of 110 HIV-infected patients (55 per group). The results were analyzed by a model of repeated measurements using Generalized Estimating Equations. RESULTS: Patients were randomized to receive either lovastatin (n = 55) or placebo (n = 57). During the 12-month follow-up, there was no effect of lovastatin either on viral load (estimated average change = 0.157 copies/mL; CI 95% = -0.099 to 0.414), or on the CD4+ T cell count (estimated average change = -26.1 cells/µL; CI 95% = -89.8 to 37.6). Moreover, there were no significant differences in secondary outcomes. CONCLUSIONS: Daily administration of lovastatin (40 mg) for one year in HIV-infected patients, naïve for antiretroviral therapy, had no significant effect on HIV replication, the CD4+ T cell count, or the activation level of T cells. (www.clinicaltrials.gov; ID NCT00721305).

Higher SLPI expression, lower immune activation, and increased frequency of immune cells in a cohort of Colombian HIV-1 controllers.

BACKGROUND: There are 2 new phenotypes of HIV-1-positive individuals who exhibit a spontaneous and sustained control of viral replication at least for 1 year without antiretroviral therapy (elite controllers <50 copies/mL and viremic controllers <2000 copies/mL). Mechanisms related to this spontaneous control of viral replication are poorly understood. METHODS: The study included HIV-1 controllers (patients with at least 1 year of HIV-1 diagnosis, highly active antiretroviral therapy naive, and with viral loads less than 2000 copies/mL) and HIV-1 progressors without antiretroviral therapy (viral load >2500 copies/mL, and CD4 T-cell count >250 cells/µL at the time of sampling). The expression of soluble factors, leukocyte protease inhibitor (SLPI) and human α-defensins-1 (HAD-1), was measured by real-time polymerase chain reaction from neutrophil cultures with or without HIV stimulation; the frequency and phenotype of innate and adaptive immune cells were determined by flow cytometry, and frequency of human leukocyte antigen alleles was determined by polymerase chain reaction sequence-specific oligonucleotide typing. RESULTS: As expected, HIV-1 controllers had higher CD4 T-cell counts and lower viral load when compared with HIV-1 progressor individuals; in addition, they exhibited lower expression of activation markers, higher frequency of myeloid dendritic cell, lower percentage of regulatory T cells and natural killer cells, and higher expression of SLPI. CONCLUSIONS: All together, these findings suggest that the control of the immune activation status and the production of antiviral proteins by innate immune cells could be associated to the mechanisms involved in the control of HIV-1 replication and better preservation of the CD4 T-cell count.

Mechanisms of human natural resistance to HIV: a summary of ten years of research in the Colombian population.

The natural history of human immunodeficiency virus type-1 (HIV-1) infection is a complex and variable process that, similarly to other infections, has clearly demonstrated the existence of mechanisms of human natural resistance. The resistance either inhibits the establishment of infection or delays disease progression. When there is continuous exposure to infectious viral particles, several genetic and immunological mechanisms are essential to lead to resistance to HIV-1 infection/progression. The objective of this manuscript was to review the different mechanisms so far proposed to be responsible for HIV-1 resistance and to present the main results derived from 10 years of research in this area among Colombian subjects. In particular, this review focuses on determining the mechanisms involved in the protection of a group of individuals repeatedly exposed to the virus but who remained exempt of serological and clinical evidence of HIV-1 infection. Although the studies carried out in our research group corroborated the protective role of some of the previously proposed mechanisms of protection, ongoing research worldwide has made it clear that the phenomenon of human natural resistance depends on multiple factors with an important genetic influence, and only multicenter studies involving individuals with different genetic backgrounds may determine more universal mechanisms of resistance. Increasing our knowledge in this field will contribute to the development of novel preventive and therapeutic measures.

Mecanismos de resistencia natural al VIH en seres humanos: un resumen de 10 años de investigación en población colombiana: [revisión] / Mechanisms of human natural resistance to HIV: a summary of ten years of research in the Colombian population: [review]

La historia natural de la infección por el virus de la inmunodeficiencia humana de tipo 1 (VIH-1) es un proceso variable y complejo que, en forma similar a otras infecciones, ha hecho evidente la existencia de mecanismos de resistencia natural que pueden inhibir el establecimiento de la infección o su progresión hacia estadios avanzados. Cuando hay una exposición continua a partículas virales infecciosas, varios mecanismos genéticos e inmunitarios son esenciales para que se establezca la resistencia. El objetivo de este manuscrito fue revisar todos los mecanismos de resistencia al VIH-1, hasta el momento propuestos en seres humanos, y presentar los resultados más importantes que se han obtenido en diferentes estudios realizados en los últimos 10 años de investigación en esta área, en individuos colombianos, particularmente enfocados en determinar los mecanismos involucrados en la protección de un grupo de personas que se han expuesto repetidamente al virus, pero que han permanecido sin evidencia clínica ni serológica de infección por el VIH-1. Aunque los estudios llevados a cabo por nuestro grupo de investigación han corroborado el papel protector de algunos de los mecanismos de protección previamente propuestos, la investigación actual en esta área, a nivel mundial, ha hecho evidente que el fenómeno de resistencia natural depende de múltiples factores con una gran influencia genética, y que sólo mediante estudios multicéntricos que involucren individuos con diferente componente genético, podrán establecerse los mecanismos universales de protección. Profundizar en el conocimiento en esta área permitirá el desarrollo de nuevas medidas preventivas y terapéuticas para la infección por el VIH-1.

The natural history of human immunodeficiency virus type-1 (HIV-1) infection is a complex and variable process that, similarly to other infections, has clearly demonstrated the existence of mechanisms of human natural resistance. The resistance either inhibits the establishment of infection or delays disease progression. When there is continuous exposure to infectious viral particles, several genetic and immunological mechanisms are essential to lead to resistance to HIV-1 infection/progression. The objective of this manuscript was to review the different mechanisms so far proposed to be responsible for HIV-1 resistance and to present the main results derived from 10 years of research in this area among Colombian subjects. In particular, this review focuses on determining the mechanisms involved in the protection of a group of individuals repeatedly exposed to the virus but who remained exempt of serological and clinical evidence of HIV-1 infection. Although the studies carried out in our research group corroborated the protective role of some of the previously proposed mechanisms of protection, ongoing research worldwide has made it clear that the phenomenon of human natural resistance depends on multiple factors with an important genetic influence, and only multicenter studies involving individuals with different genetic backgrounds may determine more universal mechanisms of resistance. Increasing our knowledge in this field will contribute to the development of novel preventive and therapeutic measures.

Chloroquine modulates HIV-1-induced plasmacytoid dendritic cell alpha interferon: implication for T-cell activation.

Plasmacytoid dendritic cells (pDC) contribute to antiviral immunity mainly through recognition of microbial products and viruses via intracellular Toll-like receptor 7 (TLR7) or TLR9, resulting in the production of type I interferons (IFNs). Although interferons reduce the viral burden in the acute phase of infection, their role in the chronic phase is unclear. The presence of elevated plasma IFN-alpha levels in advanced HIV disease and its association with microbial translocation in chronic HIV infection lead us to hypothesize that IFN-alpha could contribute to immune activation. Blocking of IFN-alpha production using chloroquine, an endosomal inhibitor, was tested in a novel in vitro model system with the aim of characterizing the effects of chloroquine on HIV-1-mediated TLR signaling, IFN-alpha production, and T-cell activation. Our results indicate that chloroquine blocks TLR-mediated activation of pDC and MyD88 signaling, as shown by decreases in the levels of the downstream signaling molecules IRAK-4 and IRF-7 and by inhibition of IFN-alpha synthesis. Chloroquine decreased CD8 T-cell activation induced by aldrithiol-2-treated HIV-1 in peripheral blood mononuclear cell cultures. In addition to blocking pDC activation, chloroquine also blocked negative modulators of the T-cell response, such as indoleamine 2,3-dioxygenase (IDO) and programmed death ligand 1 (PDL-1). Our results indicate that TLR stimulation and production of IFN-alpha by pDC contribute to immune activation and that blocking of these pathways using chloroquine may interfere with events contributing to HIV pathogenesis. Our results suggests that a safe, well-tolerated drug such as chloroquine can be proposed as an adjuvant therapeutic candidate along with highly active antiretroviral therapy to control immune activation in HIV-1 infection.

Antiretroviral effect of lovastatin on HIV-1-infected individuals without highly active antiretroviral therapy (The LIVE study): a phase-II randomized clinical trial.

BACKGROUND: Highly active antiretroviral therapy produces a significant decrease in HIV-1 replication and allows an increase in the CD4 T-cell count, leading to a decrease in the incidence of opportunistic infections and mortality. However, the cost, side effects and complexity of antiretroviral regimens have underscored the immediate need for additional therapeutic approaches. Statins exert pleiotropic effects through a variety of mechanisms, among which there are several immunoregulatory effects, related and unrelated to their cholesterol-lowering activity that can be useful to control HIV-1 infection. METHODS/DESIGN: Randomized, double-blinded, placebo controlled, single-center, phase-II clinical trial. One hundred and ten chronically HIV-1-infected patients, older than 18 years and naïve for antiretroviral therapy (i.e., without prior or current management with antiretroviral drugs) will be enrolled at the outpatient services from the most important centres for health insurance care in Medellin-Colombia. The interventions will be lovastatin (40 mg/day, orally, for 12 months; 55 patients) or placebo (55 patients). Our primary aim will be to determine the effect of lovastatin on viral replication. The secondary aim will be to determine the effect of lovastatin on CD4+ T-cell count in peripheral blood. As tertiary aims we will explore differences in CD8+ T-cell count, expression of activation markers (CD38 and HLA-DR) on CD4 and CD8 T cells, cholesterol metabolism, LFA-1/ICAM-1 function, Rho GTPases function and clinical evolution between treated and not treated HIV-1-infected individuals. DISCUSSION: Preliminary descriptive studies have suggested that statins (lovastatin) may have anti HIV-1 activity and that their administration is safe, with the potential effect of controlling HIV-1 replication in chronically infected individuals who had not received antiretroviral medications. Considering that there is limited clinical data available on this topic, all these findings warrant further evaluation to determine if long-term administration of statins may benefit the virological and immunological evolution in HIV-1-infected individuals before the use of antiretroviral therapy is required. TRIAL REGISTRATION: Registration number NCT00721305.

Invariant NKT cells from HIV-1 or Mycobacterium tuberculosis-infected patients express an activated phenotype.

The frequency, subsets and activation status of peripheral blood invariant NKT (iNKT) cells were evaluated in pulmonary tuberculosis (TB) patients and in chronically HIV-1-infected subjects. The absolute numbers of iNKT cells were significantly decreased in TB patients and in HIV-1+ individuals who were antiretroviral therapy naive or had detectable viremia despite receiving HAART. iNKT cell subset analysis demonstrated a decreased percentage of CD4(+) iNKT cells in HIV-1+ subjects, and a decreased percentage of double negative iNKT cells in TB patients. Peripheral blood iNKT cells from HIV-1+ and TB patients had significantly increased expression of CD69, CD38, HLA-DR, CD16, CD56, and CD62L. The expression of CD25 was significantly increased only on iNKT cells from TB patients. These findings indicate that peripheral blood iNKT cells in these two chronic infections show an up-regulated expression of activation markers, suggesting their role in the immune response to infection.

Effect of intrauterine HIV-1 exposure on the frequency and function of uninfected newborns' dendritic cells.

Immaturity of the neonatal immune system is considered an underlying factor for enhanced severity of infections in newborns. Functional defects of neonatal antigen-presenting cells lead to defective T-cell responses. T cells from uninfected neonates exposed in utero to HIV-1 (EU) exhibit phenotypic and functional alterations; however, the function of their circulating dendritic cells (DCs) has not been characterized. We hypothesized that an HIV-1-infected maternal environment may influence the infants' DC number, phenotype and function. EU exhibited a higher percentage of myeloid DCs (mDCs) than unexposed neonates, although this frequency remained lower than that observed in adults. Plasmacytoid DC (pDC) frequencies were similar in all groups, although both groups of infants tended to have lower frequencies than adults. After LPS stimulation, mDCs from EU up-regulated CD80, CD86 and B7-H1, whereas mDCs from unexposed infants upregulated B7-H1, but not CD80/CD86, and adult mDCs up-regulated mainly CD80 and CD86. IFN-alpha production was similar in all groups, indicating a normal pDC function. Therefore, in utero exposure to HIV-1 induces quantitative and qualitative changes in neonatal DCs, particularly in mDCs, which might be associated with alterations observed in T cells from these EU.

Abnormal humoral immune response to influenza vaccination in pediatric type-1 human immunodeficiency virus infected patients receiving highly active antiretroviral therapy.

Given that highly active antiretroviral therapy (HAART) has been demonstrated useful to restore immune competence in type-1 human immunodeficiency virus (HIV-1)-infected subjects, we evaluated the specific antibody response to influenza vaccine in a cohort of HIV-1-infected children on HAART so as to analyze the quality of this immune response in patients under antiretroviral therapy. Sixteen HIV-1-infected children and 10 HIV-1 seronegative controls were immunized with a commercially available trivalent inactivated influenza vaccine containing the strains A/H1N1, A/H3N2, and B. Serum hemagglutinin inhibition (HI) antibody titers were determined for the three viral strains at the time of vaccination and 1 month later. Immunization induced a significantly increased humoral response against the three influenza virus strains in controls, and only against A/H3N2 in HIV-1-infected children. The comparison of post-vaccination HI titers between HIV-1+ patients and HIV-1 negative controls showed significantly higher HI titers against the three strains in controls. In addition, post vaccination protective HI titers (defined as equal to or higher than 1:40) against the strains A/H3N2 and B were observed in a lower proportion of HIV-1+ children than in controls, while a similar proportion of individuals from each group achieved protective HI titers against the A/H1N1 strain. The CD4+ T cell count, CD4/CD8 T cells ratio, and serum viral load were not affected by influenza virus vaccination when pre- vs post-vaccination values were compared. These findings suggest that despite the fact that HAART is efficient in controlling HIV-1 replication and in increasing CD4+ T cell count in HIV-1-infected children, restoration of immune competence and response to cognate antigens remain incomplete, indicating that additional therapeutic strategies are required to achieve a full reconstitution of immune functions.

Characterization of human invariant natural killer T subsets in health and disease using a novel invariant natural killer T cell-clonotypic monoclonal antibody, 6B11.

Identification of human CD1d-restricted T-cell receptor (TCR)-invariant natural killer T (iNKT) cells has been dependent on utilizing combinations of monoclonal antibodies or CD1d tetramers, which do not allow for the most specific analysis of this T-cell subpopulation. A novel monoclonal antibody (clone 6B11), specific for the invariant CDR3 loop of human canonical Valpha24Jalpha18 TCR alpha chain, was developed and used to specifically characterize iNKT cells. In healthy individuals studied for up to 1 year, a wide but stable frequency of circulating iNKT cells (range: 0.01-0.92%) was observed, with no differences in frequency by gender. Four stable iNKT cell subsets were characterized in peripheral blood based on the expression of CD4 and CD8, with CD8(+) iNKT cells being a phenotypic and functionally different subset from CD4(+) and double negative iNKT cells; in particular, LAG-3 was preferentially expressed on CD8(+) iNKT cells. In addition, a strong negative linear correlation between the frequency of total iNKT cells and percentage of the CD4(+) subset was observed. In terms of their potential association with disease, patients at risk for type 1 diabetes had significantly expanded frequencies of double negative iNKT cells when compared to matched controls and first-degree relatives. Moreover, peripheral blood CD4(+) iNKT cells were the highest producers of interleukin-4, while the production of interferon-gamma and tumour necrosis factor-alpha was similar amongst all iNKT cell subsets. These differences in iNKT cell subsets suggest that in humans the relative ratio of iNKT cell subsets may influence susceptibility vs. resistance to immune-mediated diseases.

Abnormal humoral immune response to influenza vaccination in pediatric type-1 human immunodeficiency virus infected patients receiving highly active antiretroviral therapy

Given that highly active antiretroviral therapy (HAART) has been demonstrated useful to restore immune competence in type-1 human immunodeficiency virus (HIV-1)-infected subjects, we evaluated the specific antibody response to influenza vaccine in a cohort of HIV-1-infected children on HAART so as to analyze the quality of this immune response in patients under antiretroviral therapy. Sixteen HIV-1-infected children and 10 HIV-1 seronegative controls were immunized with a commercially available trivalent inactivated influenza vaccine containing the strains A/H1N1, A/H3N2, and B. Serum hemagglutinin inhibition (HI) antibody titers were determined for the three viral strains at the time of vaccination and 1 month later. Immunization induced a significantly increased humoral response against the three influenza virus strains in controls, and only against A/H3N2 in HIV-1-infected children. The comparison of post-vaccination HI titers between HIV-1+ patients and HIV-1 negative controls showed significantly higher HI titers against the three strains in controls. In addition, post vaccination protective HI titers (defined as equal to or higher than 1:40) against the strains A/H3N2 and B were observed in a lower proportion of HIV-1+ children than in controls, while a similar proportion of individuals from each group achieved protective HI titers against the A/H1N1 strain. The CD4+ T cell count, CD4/CD8 T cells ratio, and serum viral load were not affected by influenza virus vaccination when pre- vs post-vaccination values were compared. These findings suggest that despite the fact that HAART is efficient in controlling HIV-1 replication and in increasing CD4+ T cell count in HIV-1-infected children, restoration of immune competence and response to cognate antigens remain incomplete, indicating that additional therapeutic strategies are required to achieve a full reconstitution of immune functions.

Impact of class A, B and C CpG-oligodeoxynucleotides on in vitro activation of innate immune cells in human immunodeficiency virus-1 infected individuals.

Oligodeoxynucleotides (ODN) with unmethylated deoxycytidyl-deoxyguanosine dinucleotides (CpG-ODNs) stimulate Toll-like receptor 9 (TLR9) in plasmacytoid dendritic cells (pDC) and B cells and activate innate and adaptive immunity. Three classes of synthetic CpG-ODNs, class A, B and C, activate cells through TLR9; our goal was to evaluate their effect on cells from human immunodeficiency virus (HIV)-1(+) individuals. We compared the frequencies and the unstimulated activation status of immune effector cells in HIV-1(+) and HIV-1(-) individuals. Fewer pDC, myeloid dendritic cells (mDC), B cells, natural killer (NK) cells and invariant natural killer T cells (iNKT) were present in HIV-1(+) peripheral blood mononuclear cells (PBMC) and their baseline activation status was higher than HIV-1(-) PBMC. Exposure of HIV-1(+) PBMC to all classes of CpG-ODNs led to activation and maturation of pDC based on CD86, CD80, and CD83 expression similar to that of cells from HIV-1(-) individuals. The percentage of CpG-ODN stimulated pDC that express CD40 was dramatically higher when cells were obtained from HIV-1(+) than from HIV-1(-) individuals. B-lymphocytes were activated similarly in HIV-1(+) and HIV-1(-) individuals. mDC, NK and iNKT cell, which lack TLR9, were indirectly activated. Interferon-alpha (IFN-alpha) and interferon inducible protein 10 (IP-10) secretion was induced by class A or C but not class B CpG-ODN, but the concentrations were less than those produced by HIV-1(-) PBMC. HIV-1 infected individuals have fewer innate effector cells that are chronically activated, but these cells can be further activated by CpG-ODN, which suggests that synthetic CpG-ODNs could be used to enhance the immune system in HIV-1 infected individuals.

Células NK: generalidades y papel durante la infección por el virus de la inmunodeficiencia humana tipo 1 (VIH-1) / NK cels: characteristics and role during the infection by type-1 human inmunodeficiency virus (HIV-1)

Las células NK exhiben actividad espontánea contra células tumorales o células infectadas, particularmente por virus. Ellas se caracterizan por la expresión de las moléculas CD16 y CD56, y se subdividen en dos poblaciones, CD16Low/CD56Hi y CD16Hi/CD56Low, que difieren en las citoquinas que producen y en la capacidad citotóxica. La activación de las células NK está regulada por la expresión de receptores inhibidores y activadores que interactúan con diferentes ligandos de las células blanco. La actividad efectora de estas células incluye la lisis de las células blanco por diferentes mecanismos y la producción de citoquinas; las células NK participan por medio de estos factores solubles en diversos procesos fisiológicos, como la hematopoyesis y la regulación de otras células del sistema inmune. Durante la infección por el VIH-1, las células NK ayudan al control de la replicación viral tanto por mecanismos citotóxicos como por la producción de citoquinas, particularmente beta-quimoquinas. Sin embargo, el VIH-1 ha desarrollado mecanismos para evadir la respuesta antiviral mediada por las células NK. Adicionalmente, esta infección induce anormalidades cuantitativas y funcionales en estas células que puedenpresentarse muy temprano en la evolución de la enfermedad y que hacen parte de la inmunosupresión severa característica del SIDA.