Browsing by Author "Giavedoni, Luis"

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    Early Gag Immunodominance of the HIV-Specific T-Cell Response during Acute/Early Infection Is Associated with Higher CD8(+) T-Cell Antiviral Activity and Correlates with Preservation of the CD4(+) T-Cell Compartment
    (2013) Turk, Gabriela; Ghiglione, Yanina; Falivene, Juliana; Socias, Maria E.; Laufer, Natalia; Coloccini, Romina.; Rodriguez, Ana María; Ruiz, Maria; Pando, María; Giavedoni, Luis; Cahn, Pedro; Sued, Omar; Salomon, Horacio; Gherardi, María
    The important role of the CD8+ T-cell response on HIV control is well established. Moreover, the acute phase of infection represents a proper scenario to delineate the antiviral cellular functions that best correlate with control. Here, multiple functional aspects (specificity, ex vivo viral inhibitory activity [VIA] and polyfunctionality) of the HIV-specific CD8+ T-cell subset arising early after infection, and their association with disease progression markers, were examined. Blood samples from 44 subjects recruited within 6 months from infection (primary HIV infection [PHI] group), 16 chronically infected subjects, 11 elite controllers (EC), and 10 healthy donors were obtained. Results indicated that, although Nef dominated the anti-HIV response during acute/early infection, a higher proportion of early anti-Gag T cells correlated with delayed progression. Polyfunctional HIV-specific CD8+ T cells were detected at early time points but did not associate with virus control. Conversely, higher CD4+ T-cell set points were observed in PHI subjects with higher HIV-specific CD8+ T-cell VIA at baseline. Importantly, VIA levels correlated with the magnitude of the anti-Gag cellular response. The advantage of Gag-specific cells may result from their enhanced ability to mediate lysis of infected cells (evidenced by a higher capacity to degranulate and to mediate VIA) and to simultaneously produce IFN-γ. Finally, Gag immunodominance was associated with elevated plasma levels of interleukin 2 (IL-2) and macrophage inflammatory protein 1β (MIP-1β). All together, this study underscores the importance of CD8+ T-cell specificity in the improved control of disease progression, which was related to the capacity of Gag-specific cells to mediate both lytic and nonlytic antiviral mechanisms at early time points postinfection.
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    Early Skewed Distribution of Total and HIV-Specific CD8 T-Cell Memory Phenotypes during Primary HIV Infection Is Related to Reduced Antiviral Activity and Faster Disease Progression
    (2014-8) Ghiglione, Yanina; Falivene, Juliana; Ruiz, Maria; Laufer, Natalia; Socias, Maria E.; Cahn, Pedro; Giavedoni, Luis; Sued, Omar; Gherardi, María Magdalena; Salomon, Horacio; Turk, Gabriela
    The important role of the CD8+ T-cells on HIV control is well established. However, correlates of immune protection remain elusive. Although the importance of CD8+ T-cell specificity and functionality in virus control has been underscored, further unraveling the link between CD8+ T-cell differentiation and viral control is needed. Here, an immunophenotypic analysis (in terms of memory markers and Programmed cell death 1 (PD-1) expression) of the CD8+ T-cell subset found in primary HIV infection (PHI) was performed. The aim was to seek for associations with functional properties of the CD8+ T-cell subsets, viral control and subsequent disease progression. Also, results were compared with samples from Chronics and Elite Controllers. It was found that normal maturation of total and HIV-specific CD8+ T-cells into memory subsets is skewed in PHI, but not at the dramatic level observed in Chronics. Within the HIV-specific compartment, this alteration was evidenced by an accumulation of effector memory CD8+ T (TEM) cells over fully differentiated terminal effector CD8+ T (TTE) cells. Furthermore, higher proportions of total and HIV-specific CD8+ TEM cells and higher HIV-specific TEM/(TEM+TTE) ratio correlated with markers of faster progression. Analysis of PD-1 expression on total and HIV-specific CD8+ T-cells from PHI subjects revealed not only an association with disease progression but also with skewed memory CD8+ T-cell differentiation. Most notably, significant direct correlations were obtained between the functional capacity of CD8+ T-cells to inhibit viral replication in vitro with higher proportions of fully-differentiated HIV-specific CD8+ TTE cells, both at baseline and at 12 months post-infection. Thus, a relationship between preservation of CD8+ T-cell differentiation pathway and cell functionality was established. This report presents evidence concerning the link among CD8+ T-cell function, phenotype and virus control, hence supporting the instauration of early interventions to prevent irreversible immune damage.
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    Env-Specific IgA from Viremic HIV-Infected Subjects Compromises Antibody-Dependent Cellular Cytotoxicity
    (2016) Ruiz, Maria; Ghiglione, Yanina; Falivene, Juliana; Laufer, Natalia; Holgado, Maria Pia; Socias, Maria E.; Cahn, Pedro; Sued, Omar; Giavedoni, Luis; Salomon, Horacio; Gherardi, María Magdalena; Rodriguez, Ana María; Turk, Gabriela
    Elucidating the factors that modulate HIV-specific antibody-dependent cellular cytotoxicity (ADCC) will help in understanding its role in HIV immunity. The aim of this study was to determine whether IgA could modify the magnitude of ADCC in HIV infection, abrogating its protective role. Plasma samples from 20 HIV-positive (HIV(+)) subjects enrolled during primary HIV infection (PHI), 10 chronically infected subjects (chronic), and 7 elite controllers (EC) were used. ADCC was determined by using a fluorometric ADCC assay, before and after removal of plasma IgA. Data were analyzed by using nonparametric statistics. ADCC was documented in 80% of PHI enrollment samples and in 100% of PHI 12-month, chronic, and EC samples; it peaked after acute infection, reached a plateau in chronic infection, and decreased after initiation of antiretroviral treatment (ART). Significant associations between ADCC and disease progression were found only after removal of plasma IgA from 12-month PHI samples: the magnitude of ADCC not only increased after IgA removal but also correlated with CD4(+) T-cell preservation. This work provides evidence that gp120-specific IgA was capable of modifying ADCC responses during natural HIV infection for the first time and adds to similar evidence provided in other settings. Furthermore, it underscores the complexity of the ADCC phenomenon and will help in an understanding of its underlying mechanisms. Importance: Although the induction of ADCC-mediating antibodies in HIV-infected subjects has been extensively documented, the association of these antibodies with protection from disease progression is poorly understood. Here, we demonstrate that plasma IgA is a factor capable of modifying the magnitude of IgG-mediated ADCC in HIV infection, mitigating its beneficial effect. These results help in understanding why previous studies failed to demonstrate correlations between ADCC and disease progression, and they also contribute to the notion that an HIV vaccine should stimulate the production of ADCC-mediating IgG antibodies but not IgA.
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    Plasma cytokine levels and HIV-specific immune responses during acute/early HIV infection
    (2012) Turk, Gabriela; Laufer, Natalia; Rodriguez, Ana; Ghiglione, Yanina; Favilene, Jose; Ruiz, Maria; Sued, Omar; Giavedoni, Luis; Cahn, Pedro; Salomon, Horacio; Gherardi, Marisa
    Background It is believed that initial encounter between HIV and the human host triggers a complex series of events that dictate future disease course. Inter-individual differences among the host-players involved in these processes seem to early determine different rates of disease progression. Here we were aimed at studying the relationship between innate and adaptive soluble immune mediators, HIV-specific T-cell response and the course of acute infection. Go to: Methods Plasma levels of 37 cytokines were measured by Luminex technology in different groups of volunteers: 10 healthy donors (HD) and 50 HIV infected-subjects: 10 chronics, 12 aviremic controllers (EC) and 28 subjects enrolled during acute infection (AI). All HIV patients were off-HAART. Frozen PBMCs from the same individuals were used to determine HIV-specific T-cell responses by IFN-gamma ELISPOT. Data was compared inter- and intra-groups and correlated to viral load (VL), CD4 T cell counts and both virological (VL) and immunological (CD4 count) set-points (in AI), using parametric and non-parametric statistics. Go to: Results Compared to HD, cytokines significantly elevated during acute and chronic infection included IL-1alfa, IL-10, IP-10 and TNF-alfa. Conversely, IL-12p40 and the macrophage-derived chemokine (MDC) were only significantly elevated in chronics and not in AI subjects who showed similar levels to HD and even EC. Moreover, levels of IL-12p40, IL-12p70 and MDC directly correlated with CD4 T-cell count among chronics and both CD4 T-cell count and immunological set point in AI. Regarding HIV-specific T-cell response during AI, proportion of Gag-specific and Nef-specific cells significantly correlated (directly and inversely, respectively) with immunological set point. Go to: Conclusion Both early and late components of the immune system help preserve CD4 T-cell subset in HIV+ subjects: key cytokines involved in the initiation and regulation of cellular immune response and anti-Gag specificity of effector T-cells. These features should be taken into account during vaccine formulation design to boost favorable results.