Mauro Andreotti

Potent Immune Response against HIV-1 and Protection from Virus Challenge in hu-PBL-SCID Mice Immunized with Inactivated Virus-pulsed Dendritic Cells Generated in the Presence of IFN-α

A major challenge of AIDS research is the development of therapeutic vaccine strategies capable of inducing the humoral and cellular arms of the immune responses against HIV-1. In this work, we evaluated the capability of DCs pulsed with aldrithiol-2–inactivated HIV-1 in inducing a protective antiviral human immune response in SCID mice reconstituted with human PBL (hu-PBL-SCID mice). Immunization of hu-PBL-SCID mice with DCs generated after exposure of monocytes to GM-CSF/IFN-α (IFN-DCs) and pulsed with inactivated HIV-1 resulted in a marked induction of human anti–HIV-1 antibodies, which was associated with the detection of anti-HIV neutralizing activity in the serum. This vaccination schedule also promoted the generation of a human CD8+ T cell response against HIV-1, as measured by IFN-γ Elispot analysis. Notably, when the hu-PBL-SCID mice immunized with antigen-pulsed IFN-DCs were infected with HIV-1, inhibition of virus infection was observed as compared with control animals. These results suggest that IFN-DCs pulsed with inactivated HIV-1 can represent a valuable approach of immune intervention in HIV-1–infected patients.

IFN‐α‐conditioned dendritic cells are highly efficient in inducing cross‐priming CD8+ T cells against exogenous viral antigens

Dendritic cells (DC) generated after a short‐term exposure of monocytes to IFN‐α and GM‐CSF (IFN‐DC) are highly effective in inducing cross‐priming of CD8+ T cells against viral antigens. We have investigated the mechanisms responsible for the special attitude of these DC and compared their activity with that of reference DC. Antigen uptake and endosomal processing capabilities were similar for IFN‐DC and IL‐4‐derived DC. Both DC types efficiently cross‐presented soluble HCV NS3 protein to the specific CD8+ T cell clone, even though IFN‐DC were superior in cross‐presenting low amounts of viral antigens. Moreover, when DC were pulsed with inactivated HIV‐1 and injected into hu‐PBL‐SCID mice, the generation of virus‐specific CD8+ T cells was markedly higher in animals immunized with IFN‐DC than in mice immunized with CD40L‐matured IL‐4‐DC. Of interest, in experiments with purified CD8+ T cells, IFN‐DC were superior with respect to CD40L‐matured IL‐4‐DC in inducing in vitro cross‐priming of HIV‐specific CD8+ T cells. This property correlated with enhanced potential to express the specific subunits of the IL‐23 and IL‐27 cytokines. These results suggest that IFN‐DC are directly licensed for an efficient CD8+ T cell priming by mechanisms likely involving enhanced antigen presentation and special attitude to produce IL‐12 family cytokines.

Early immune reconstitution after potent antiretroviral therapy in HIV-infected children correlates with the increase in thymus volume

DesignDespite significant rises in total CD4 T cells, the process of immune reconstitution in adults with HIV infection treated with potent antiretroviral treatment results in a rather slow increase in phenotypically naive lymphocytes. In children more than in adults, thymic function may be at least partly restored when disease-induced immunosuppression is attenuated by pharmacological means. MethodsTwenty-five vertically infected and antiretroviral-experienced [zidovudine (ZDV)/ZDV plus didanosine (ddI)] children were prospectively followed during 12 months of treatment with lamivudine (3TC), stavudine (d4T) and indinavir (IDV). The plasma HIV viral load and phenotypic and functional cellular immunity-defining parameters were examined. The relationship between the degree of immune reconstitution and thymus volume assessed by nuclear magnetic resonance was also examined. ResultsAn early and steep increase in CD45RA+62L+ T cells was observed in parallel with a sustained decrease in plasma HIV RNA levels and a significant rise in total CD4 T cells. This increase was significantly greater than that observed in CD4+CD45RO+ T cells. Analysis of the CD4 T cell receptor (TCR) beta repertoire and T helper function showed the ability to reconstitute families almost completely absent at baseline, and a substantial improvement of antigen-specific responses by peripheral blood lymphocytes. The rise in CD4 cells and in CD4+CD45RA+62L+ T cells was statistically associated with changes in thymus size observed over time. ConclusionThese data suggest a relevant contribution of the thymus to reconstitution of the peripheral pool of T cells in vertically HIV-infected children treated with potent antiretroviral regimens.

Monocyte-derived dendritic cells generated after a short-term culture with IFN-α and granulocyte-macrophage colony-stimulating factor stimulate a potent epstein-barr virus-specific CD8+ T cell response

Cellular immune responses are crucial for the control of EBV-associated lymphoproliferative diseases. To induce an anti-EBV cell-mediated immunity, we have used dendritic cells (DCs) generated by a 3-day culture of human CD14+ monocytes in the presence of GM-CSF and type I IFN (IFN-DCs) and pulsed with peptides corresponding to CTL EBV epitopes. The functional activity of IFN-DCs was compared with that of APCs differentiated by culturing monocytes for 3 days with GM-CSF and IL-4 and indicated as IL-4-DCs. Stimulation of PBLs from EBV-seropositive donors with EBV peptide-pulsed autologous IFN-DCs resulted in a stronger expansion of specific T lymphocytes producing IFN-γ with respect to stimulation with peptide-loaded IL-4-DCs, as assessed by ELISPOT assays. When purified CD8+ T cells were cocultured with EBV peptide-pulsed IFN-DCs or IL-4-DCs, significantly higher levels of specific cytotoxic activity were observed in CD8+ T cell cultures stimulated with IFN-DCs. Injection of peptide-pulsed IFN-DCs into SCID mice transplanted with autologous PBLs led to the recovery of a significantly greater number of EBV-specific human CD8+ T cells from the spleen and the peritoneal cavity with respect to that recovered from mice injected with peptide-pulsed IL-4-DCs. Moreover, a significant delay in lymphoma development was observed when peptide-pulsed IFN-DCs were injected into SCID mice reconstituted with PBMCs endowed with a high capability of lymphoma induction, whereas injection of unpulsed IFN-DCs was ineffective. Our results indicate that IFN-DCs efficiently promote in vitro and in vivo the expansion of CD8+ T lymphocytes acting as cytotoxic effectors against EBV-transformed cells.

Triple antiretroviral prophylaxis administered during pregnancy and after delivery significantly reduces breast milk viral load: A study within the Drug Resource Enhancement Against AIDS and Malnutrition Program.

Background:The administration of antiretroviral therapy to lactating women could represent a possible strategy to reduce postnatal HIV transmission. In this study, we assessed the effect of antiretroviral treatment on breast milk viral load and determined plasma and breast milk drug concentrations in pregnant women receiving highly active antiretroviral therapy (HAART). Methods:We studied 40 women receiving zidovudine, lamivudine, and nevirapine from 28 weeks of gestation to 1 month postpartum (group A) and 40 untreated pregnant women (group B). Blood and breast milk samples were collected at delivery and 7 days postpartum. Results:Women in group A had received a median of 85 days of therapy before delivery. Median breast milk concentrations of nevirapine, lamivudine, and zidovudine were 0.6, 1.8, and 1.1 times, respectively, those in maternal plasma. HIV RNA levels in breast milk were significantly lower in group A than in group B (median of 2.3 vs. 3.4 log at delivery and 1.9 vs. 3.6 log at day 7; P < 0.001 for both comparisons). Conclusions:Antiretroviral drugs administered during the last trimester of pregnancy and after delivery reach levels similar to or higher than plasma concentrations in breast milk and can significantly reduce HIV RNA levels. Our data support the potential role of maternal HAART prophylaxis in reducing the risk of breast-feeding-associated transmission.

HIV Persistence in the Gut Mucosa of HIV-Infected Subjects Undergoing Antiretroviral Therapy Correlates with Immune Activation and Increased Levels of LPS

We investigated the relationship between viral persistence in the gut, microbial translocation, and T cell activation during chronic HIV infection. Plasma levels of LPS, fraction of circulating CD8+CD38+ T cells, and levels of HIV-DNA in rectosigmoid biopsies and peripheral blood mononuclear cells were determined in 22 HIV-infected individuals and 10 healthy controls. We found that in untreated HIV-infected individuals, HIV-DNA load was higher in the gut mucosa than in the blood. Also, ART-treated patients exhibited lower levels of LPS and CD8+CD38+ T cells than untreated patients, but higher levels than controls. In ART-treated individuals, the level of HIV-DNA in the gut correlated with levels of LPS and fraction of CD8+CD38+ T cells. We concluded that in ART-treated individuals, higher levels of gut-associated HIV-DNA are associated with persistent immune activation and microbial translocation.

Microbial translocation is associated with residual viral replication in HAART-treated HIV+ subjects with <50 copies/ml HIV-1 RNA

BACKGROUND Recent data have shown that plasma levels of lipopolysaccharide (LPS) are a quantitative indicator of microbial translocation in HIV infected individuals. OBJECTIVES To assess the impact of residual viral replication on plasma LPS in HAART-treated HIV+ subjects with <50copies/ml HIV-1 RNA and to evaluate LPS changes during repeated HAART interruptions not exceeding 2-month duration. STUDY DESIGN LPS was measured in 44 HIV+ subjects at T0 (during HAART) and at day 15 of the first and fourth HAART interruption. Ten uninfected, healthy donors were studied as well. Residual plasma HIV-1 RNA was measured at T0 by an ultra-ultrasensitive method with limit of detection of 2.5copies HIV-1 RNA/ml. Subjects with less than 2.5copies/ml (fully suppressed - FS) were compared to those with 2.5-50copies/ml (partially suppressed - PS). RESULTS At T0, plasma LPS levels were comparable in FS and uninfected subjects, whereas in PS they were higher than in uninfected subjects (p=0.049). After 4 HAART interruptions, they did not change significantly. However, LPS values were lower in FS than in PS (p=0.020). An inverse correlation was found between CD4 and LPS levels (p=0.044) in PS group only. CONCLUSIONS A reduced degree of microbial translocation was seen in subjects with a more complete suppression of viral replication. Repeated HAART interruptions had no significant impact on plasma LPS levels.

Residual viraemia in subjects with chronic HIV infection and viral load < 50 copies/ml: the impact of highly active antiretroviral therapy.

Objective:To determine factors associated with < 2.5 copies/ml plasma HIV RNA in subjects treated with highly active antiretroviral therapy (HAART) and with viraemia < 50 copies/ml. Design:Cross-sectional analysis of 84 HIV-positive patients taking HAART with plasma HIV RNA < 50 copies/ml for at least 6 months and no history of virological failure. Methods:Current HAART therapy was based on a non-nucleoside reverse transcriptase inhibitor (NNRTI) in 66%, a protease inhibitor in 26% and nucleoside reverse transcriptase inhibitors in 7%. Viraemia levels were measured using a modified ultrasensitive Roche Amplicor HIV-1 Monitor test able to quantify plasma HIV RNA to a lower limit of 2.5 copies /ml; proviral DNA was measured with a real-time polymerase chain reaction assay. Analysis of variance and multiple logistic regression analysis were utilized to test for associations between residual replication and other variables. Results:Residual HIV viraemia > 2.5 copies/ml was found in 50% of subjects; 94% of subjects had detectable proviral DNA (≥ 20 copies/106 peripheral blood mononuclear cells) and 21% had archived mutations. Usage of a NNRTI-based HAART was the only independent predictor of viral suppression below the cut-off value of the modified ultrasensitive assay. Conclusions:In our population, NNRTI-based HAART seems to have a stronger impact on residual replication than protease inhibitor-based HAART. This finding may be considered in therapeutic decisions such as the choice of initial HAART regimen and the interruption or simplification of treatment.

Correlation between HIV-1 viral load quantification in plasma, dried blood spots, and dried plasma spots using the Roche COBAS Taqman assay

BACKGROUND The use of simplified methods for viral load determination could greatly increase access to treatment monitoring of HIV patients in resource-limited countries. OBJECTIVE The aim of the present study was to optimize and evaluate the performance of the Roche COBAS Taqman assay in HIV-RNA quantification from dried blood spots (DBS) and dried plasma spots (DPS). STUDY DESIGN EDTA blood samples from 108 HIV-infected women were used to prepare 129 DBS and 76 DPS on Whatman 903 card. DBS and DPS were stored at -20 degrees C. HIV-1 RNA was extracted from DBS/DPS using the MiniMAG system (bioMerieux). Amplification and detection were performed using the Roche COBAS TaqMan assay. Plasma viral load results were used as standard. RESULTS There was a high correlation between measures of viral load in plasma and in DBS/DPS (r=0.96 and 0.85 respectively, P<0.001). Overall, viral load values in DBS and DPS tended to be lower than in plasma with mean (SD) differences of 0.32 log(0.22) for DBS and of 0.35 (0.33) for DPS. Detection rates were 96.4% for DBS and 96.1% for DPS in samples with corresponding plasma values >3.0 log copies/ml. Samples with HIV-RNA below 50 copies/ml were correctly identified in 18/19 DBS and in 7/7 DPS. CONCLUSIONS Both DBS and DPS provided results highly correlated to the plasma values. High detection rate was obtained with both DBS and DPS when HIV-RNA was >3.0 log copies/ml. Our results support the use of DBS/DPS to detect virologic failure in resource-limited settings.

Novel Quinolinonyl Diketo Acid Derivatives as HIV-1 Integrase Inhibitors: Design, Synthesis, and Biological Activities

Novel quinolinonyl diketo acids were designed to obtain integrase (IN) inhibitors selectively active against the strand transfer (ST) step of the HIV integration process. Those new compounds are characterized by a single aryl diketo acid (DKA) chain in comparison to 4, a bifunctional diketo acid reported by our group as an anti-IN agent highly potent against both the 3′-processing and ST steps. Compound 6d was the most potent derivative in IN enzyme assays, while 6i showed the highest potency against HIV-1 in acutely infected cells. The selective inhibition of ST suggested the newly designed monofunctional DKAs bind the IN−DNA acceptor site without affecting the DNA donor site.