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Objective: To investigate the impact of intermittent interleukin-2 (IL-2) plus combination antiretroviral therapy (cART) on HIV-1 entry co-receptor use., Methods: Primary HIV-1 isolates were obtained from 54 HIV-1-positive individuals at baseline and after 12 months using co-cultivation of peripheral blood mononuclear cells (PBMC) with activated PBMC of HIV-negative healthy donors. HIV-1 co-receptor use was determined on U87-CD4 cells., Results: Fourteen out of the 21 (67%) IL-2-treated individuals harbouring a primary CCR5-dependent (R5) HIV-1 isolate at baseline confirmed an R5 virus isolation after 12 months in contrast to 3 out of 7 (43%) of those receiving cART only. After 12 months, only 1 R5X4 HIV-1 isolate was obtained from 21 cART+IL-2-treated individuals infected with an R5 virus at entry (5%) vs. 2/7 (29%) patients receiving cART alone, as confirmed by a 5-year follow-up on some individuals., Conclusions: Intermittent IL-2 administration plus cART may prevent evolution towards CXCR4 usage in individuals infected with R5 HIV-1.

We prospectively evaluated 28 triple-class experienced HIV-1-infected patients harbouring R5 virus, who received maraviroc, raltegravir and etravirine. By on-treatment analysis, 26 (92%) had less than 50 copies HIV-RNA/ml at week 48. The median (interquartile range) 48-week increase in CD4 cell counts was 267 (136-355) cells/microl. Three serious adverse events occurred: one recurrence of mycobacterial spondylodiscitis, one anal cancer, one Hodgkin lymphoma. Although long-term safety needs further study, this protease inhibitor and nucleoside analogue-sparing regimen showed sustained efficacy.

Background: T-cell mediated immunity likely plays an important role in controlling HIV-1 infection and progression to AIDS. Several candidate vaccines against HIV-1 aim at stimulating cellular immune responses, either alone or together with the induction of neutralizing antibodies, and assays able to measure CD8 and CD4 T-cell responses need to be implemented. At present, the IFN-gamma-based ELISPOT assay is considered the gold standard and it is broadly preferred as primary assay for detection of antigen-specific T-cell responses in vaccine trials. However, in spite of its high sensitivity, the measurement of the sole IFN-gamma production provides limited information on the quality of the immune response. On the other hand, the introduction of polychromatic flow-cytometry-based assays such as the intracellular cytokine staining (ICS) strongly improved the capacity to detect several markers on a single cell level., Results: The cumulative analysis of 275 samples from 31 different HIV-1 infected individuals using an ICS staining procedure optimized by our laboratories revealed that, following antigenic stimulation, IFN-gamma producing T-cells were also producing MIP-1beta whereas T-cells characterized by the sole production of IFN-gamma were rare. Since the analysis of the combination of two functions decreases the background and the measurement of the IFN-gamma+ MIP-1beta+ T-cells was equivalent to the measurement of the total IFN-gamma+ T-cells, we adopted the IFN-gamma+ MIP-1beta+ data analysis system to evaluate IFN-gamma-based, antigen-specific T-cell responses. Comparison of our ICS assay with ELISPOT assays performed in two different experienced laboratories demonstrated that the IFN-gamma+ MIP-1beta+ data analysis system increased the sensitivity of the ICS up to levels comparable to the sensitivity of the ELISPOT assay., Conclusion: The IFN-gamma+ MIP-1beta+ data evaluation system provides a clear advantage for the detection of low magnitude HIV-1-specific responses. These results are important to guide the choice for suitable highly sensitive immune assays and to build reagent panels able to accurately characterize the phenotype and function of responding T-cells. More importantly, the ICS assay can be used as primary assay to evaluate HIV-1-specific responses without losing sensitivity in comparison to the ELISPOT assay.

In multidrug resistant patients treatment interruptions allow the selection of archived wild-type drug-susceptible viruses that compete for the less fit drug-resistant strains. However, the selection of viruses with increased replicative capacity is often followed by a loss of CD4+ T cells. In addition, drug resistant variants later re-emerge limiting the overall clinical benefit of treatment interruption. Blood monocytes are a key component of the HIV reservoir and can be partially removed by a system for purging of myeloid cells (MYP). This study tested the safety and efficacy of MYP on multidrug resistant patients who underwent treatment interruption. Twelve patients were randomized to receive or not six cycles of MYP during treatment interruption. An optimized antiretroviral regimen was reintroduced after the reappearance of a drug susceptible genotype. Following therapy reintroduction, a long lasting increase in CD4+ T cell counts was observed only in the treatment interruption + MYP patients but not in the control patients. Five/six treatment interruption + MYP patients never experienced virological rebound during a median follow up period of 98 weeks. In contrast, 4/6 patients who did not receive MYP never reached complete viral suppression and had a virological rebound after a median of 16.5 weeks after treatment reintroduction. The difference between the two groups in the time to virological rebound was statistically significant (P = 0.021). A consistent decrease of HIV DNA load in CD14+ purified cells was observed only in treatment interruption + MYP patients. These data suggest that MYP can improve the immunological and virological response to treatment interruption., ((c) 2007 Wiley-Liss, Inc.)

The therapeutic armamentarium against HIV has recently gained a drug belonging to a novel class of antiretrovirals, the entry inhibitors. The last decade has driven an in-depth knowledge of the HIV entry process, unravelling the multiple engagements of the HIV envelope proteins with the cellular receptorial complex that is composed of a primary receptor (CD4) and a co-receptor (CCR5 or CXCR4). The vast majority of HIV-infected subjects exhibit biological viral variants that use CCR5 as a co-receptor. Individuals with a mutated CCR5 gene, both homo- and heterozygotes, appear to be healthy. For these and other reasons, CCR5 represents an appealing target for treatment intervention, although certain challenges can not be ignored. Promising small-molecule, orally bioavailable CCR5 antagonists are under development for the treatment of HIV-1 infection.

Interleukin-2 (IL-2) increases circulating CD4(+) lymphocytes in patients infected with human immunodeficiency virus-1. We studied Epstein-Barr virus (EBV) dynamics in 40 patients treated with antiretroviral therapy (ART) plus different IL-2 regimens. EBV-DNA tended to increase in both peripheral blood cells and plasma after continous infusion followed by intermittent subcutaneous high-dose IL-2, while EBV-DNA decreased in cells (p=0.0078) and disappeared in plasma after intermittent subcutaneous low-dose IL-2. Over 12 months, the dynamics of EBV differed between the two groups both in cells (p=0.0184) and plasma (p=0.0114). Thus, as a function of dose, IL-2 therapy may significantly affect the dynamics of EBV infection.

Background: Interleukin-2 (IL-2) has been investigated as an adjunct to antiretroviral therapy (ART) because of its well-demonstrated capacity of stably increasing the number of peripheral CD4+ T cell lymphocytes. However, IL-2-related adverse events (AEs), including fever, tachycardia, hypotension, and respiratory failure, are typically dose- and schedule-dependent and can potentially limit the application of IL-2 therapy in an outpatient setting. Nitric oxide (NO) is a potent vasodilator potentially responsible for some of the AEs caused by IL-2., Purpose: In this study, we determined NO production in a cohort of HIV-1 infected individuals receiving ART either alone or together with IL-2., Method: NO production, detected as plasma nitrate/nitrite levels by the Griess reaction, was evaluated in 3 groups of 10 individuals each. In the first group, subcutaneous (sc) administration of 12-15 million international units per day (MIU/d) of IL-2 was administered for 5 days every 8 weeks for 6 cycles together with ART; in the second group, IL-2 (6 MIU/d) was given sc for 5 days every 4 weeks for 12 cycles together with ART; whereas the third group received ART alone., Results: At baseline, the plasma nitrate/nitrite levels in the 2 groups of patients who received high and low doses of the cytokine along with ART were 28.5 +/- 18.1 micromol/L and 34.2 +/- 29.0 micromol/L, respectively. These levels were comparable to those of patients treated with only ART (18.6 +/- 22.4 micromol/L) and to those of 20 healthy controls (19.9 +/- 5.9 micromol/L). No significant increase of plasma nitrate/nitrite levels was observed by administration of either ART or ART+IL-2. In addition, NO production was not associated significantly with different levels of tumor necrosis factor-alpha, IL-6, or soluble IL-2 receptor alpha chain in 9 individuals with WHO grade 2 and 3 AEs., Conclusion: Our results indicate that NO is unlikely to be responsible for most side effects of IL-2 therapy in HIV-1 infected individuals. Because both IL-2 and virus multiplication have been reported to independently stimulate NO production, concomitant ART may curtail NO production through inhibition of HIV-1 replication.

Genotypes in nine highly protease inhibitor (PI)-experienced patients were studied before and after lopinavir/ritonavir (LPV/r) treatment. Resistance to amprenavir was the rule both before and after LPV/r treatment. Treatment with LPV/r can select for the 50 V mutation. In this setting, significant differences in the inference of the amprenavir phenotype from genotype were observed when using different algorithms.

Objective: To verify whether the in vitro sensitivity of immature dendritic cells (iDC) to lysis by autologous natural killer (NK) cells from HIV-infected individuals might be correlated with HIV disease progression., Design: Both dendritic cells (DC) and interlekin (IL)-2 activated NK cells were obtained from 13 HIV-infected individuals early after seroconversion and not receiving highly active antiretroviral therapy (HAART) and from 14 individuals with chronic HIV infection under HAART. The rate of NK cell-mediated killing of autologous iDC was correlated with classical parameters of HIV evolution., Methods: Peripheral blood monocytes obtained from the Ficoll-derived leukocyte fraction after adherence to plastic were stimulated with granulocyte-macrophage colony stimulating factor plus IL-4 to induce their differentiation into iDC to be used as target cells in a standard 4-h cytotoxicity assay. A fraction of autologous leukocytes was stimulated with IL-2 to induce activation of NK cells to be used as effector cells., Results: During early HIV infection the extent of ex vivo lysis of monocyte-derived DC by activated autologous NK cells was inversely and directly correlated with the levels of viraemia and with the percentage of circulating CD4 T cells, respectively. In contrast, the capacity of NK cells to kill iDC was lost independently of the levels of plasma viraemia or the concurrence of HAART in chronically infected individuals. Addition of exogenous HIV Tat during the cytotoxicity assay inhibited NK cell-mediated lysis of DC., Conclusions: NK cell-mediated immune surveillance against infected DC may be effective only during early HIV infection and may not be restored by HAART.

Objective: In HIV-positive individuals administration of intermittent interleukin (IL)-2 in addition to highly active antiretroviral therapy (HAART) induces expansion of the peripheral T cell pool with dilution of signal joint T cell receptor excision circles (sjTREC) that cannot be used to measure thymic output. We analysed whether in vitro thymopoiesis could be used to predict in vivo thymic output in IL-2 treated subjects., Design and Methods: We correlated the relative variation of peripheral CD4 T cells over 12 months in HIV-positive subjects on HAART or HAART + IL-2 with the mean levels of both sjTREC and T cells developed in chimeric murine foetal thymic organ cultures (FTOC) reconstituted with circulating progenitors., Results: In contrast with HAART treated individuals in which these values were directly correlated, in subjects receiving HAART + IL-2 the increase of CD4 T cells in vivo was correlated to neither sjTREC number nor to reconstitution of FTOC, probably reflecting a main effect of IL-2 in the expansion of the peripheral T cell pool. Nevertheless, addition of IL-2 to HAART determined a significant increase of in vitro thymopoietic potential in individuals with undetectable viraemia., Conclusions: The increased T cell development in vitro after addition of IL-2 to HAART suggests that intermittent IL-2 administration may exert a positive influence on lymphopoiesis. In two subjects with positive viraemia treated with IL-2 we observed reduced in vitro development of T cell precursors suggesting that the positive influence of IL-2 on thymopoiesis could be secondary to the control of viral replication by HAART. These observations provide novel evidence in support of the potential beneficial use of IL-2 in HAART treated individuals.

The combination of interleukin 2 (IL-2) and antiretroviral therapy (ART) represents an emerging strategy in the treatment of patients infected with HIV. Aside from its immunomodulatory role, however, IL-2 may induce replication of human herpesvirus 8 (HHV-8)/Kaposi sarcoma (KS)-associated herpesvirus. We retrospectively evaluated HHV-8 plasma viremia and cellular load, as well as anti-HHV-8 antibody titers, in sequential samples from 84 patients receiving ART alone or in combination with IL-2. At baseline, HHV-8 plasma viremia was present only in 2 HHV-8-seropositive patients in whom KS subsequently developed during or immediately after termination of IL-2 therapy. The level of viremia increased during follow-up and peaked at the time of the clinical manifestation of KS. Moreover, transient peaks of HHV-8 viremia were temporally associated with administration of IL-2. HHV-8 plasma viremia was never detected in the other 47 patients receiving IL-2 nor in 35 controls treated only with ART. Thus, IL-2 therapy seems safe in most patients infected with both HIV and HHV-8, except for those with detectable HHV-8 viremia, who may not be eligible for IL-2 treatment.

HIV-infected individuals with 200-500 CD4(+) T cell/microl were enrolled in a controlled study of three interleukin 2 (IL-2) plus antiretroviral therapy (ART) regimens: (1) continuous intravenous administration of 12 million international units (MIU) of IL-2 followed by subcutaneous high-dose IL-2 (7.5 MIU, twice daily) for 5 days every 8 weeks; (2) high-dose subcutaneous IL-2 for 5 days every 8 weeks; (3) low-dose (3 MIU, twice daily) subcutaneous IL-2 for 5 days every 4 weeks; and (4) ART alone. Serum concentrations of IL-2, soluble IL-2 receptor (sIL-2R), tumor necrosis factor alpha (TNF-alpha), and IL-6 were determined. A progressive decrease over time of the circulating levels of IL-2 was observed in individuals receiving the highest doses of IL-2, but not in those belonging to the low-dose arm. Conversely, increased levels of sIL-2R were observed in all cytokine-treated individuals. The levels of TNF-alpha increased in the high-dose IL-2 regimens, but decreased in individuals receiving low-dose IL-2. IL-2-related toxicity was significantly correlated to the peak IL-2 serum levels, and was substantially lower in those individuals receiving low-dose IL-2. In conclusion, intermittent IL-2 administration causes the elevation of peripheral CD4(+) T cells, but also a profound cytokine response and systemic toxicity. The latter was correlated to the peak serum level of IL-2, but not to those of TNF-alpha and IL-6.

The effect of Highly Active Antiretroviral Therapy (HAART) on binding and neutralizing antibody responses to human immunodeficiency virus type-1 (HIV-1) during primary and chronic infection was investigated. Seven patients HAART treated during primary infection, six HAART treated during chronic infection and five patients treated only with ZVD (Zidovudine) were analysed. HAART inhibited the development of anti env antibodies during primary infection. Administering HAART during primary infection usually did not substantially affect the development of weak neutralizing antibody responses against autologous virus. However, we demonstrated that very early treatment, during seroconversion, induce in some cases, a strong neutralizing antibodies against autologous virus. These results may be relevant for understanding how HAART may elicit a strong protective responses and may be useful in developing new strategies designed to achieve a long term control of the HIV infection.

To evaluate the safety and efficacy of 3 regimens of intermittent subcutaneous (sc) interleukin (IL)--2 in a phase 2 study, 61 antiviral drug-experienced human immunodeficiency virus (HIV)--positive patients were randomly assigned to one of the following study arms: antiretroviral therapy (ART) plus IL-2 (12 million IU [MIU] by continuous intravenous infusion, followed by 7.5 MIU twice a day, sc, every 8 weeks); ART plus IL-2 (7.5 MIU twice a day, sc, every 8 weeks); ART plus IL-2 (3 MIU twice a day, sc, every 4 weeks); or ART alone. A significant increase of circulating CD4 cells was observed in IL-2--treated subjects, compared with those given ART alone. Low doses of IL-2 were better tolerated. Despite the incomplete suppression of viral replication, IL-2 with ART did not increase either plasma viremia or cell-associated HIV DNA levels. Low doses of intermittent sc IL-2 induced a stable increase of peripheral CD4 cells that was indistinguishable from those associated with higher, less well-tolerated doses of IL-2.

Intermittent administration of recombinant interleukin-2 (rIL-2) to individuals infected with human immunodeficiency virus (HIV) has been shown to raise and maintain the absolute number of circulating CD4(+) T cells to normal or near normal levels. One of the signaling pathways triggered by IL-2 is the Janus kinase-signal transducer and activator of transcription (JAK-STAT). In particular, IL-2 activates the tyrosine kinases JAK1 and JAK3 and the transcription factors STAT3 and STAT5. We have previously observed that most HIV(+) individuals, unlike healthy seronegative controls, show a constitutive activation of STAT1 and a C-terminal truncated isoform of STAT5 (STAT5 Delta). In the present study, we have analyzed the protein level and activation state of STAT5 isoforms expressed in peripheral blood mononuclear cells of two HIV-infected individuals who showed a good or a poor response to intermittent IL-2 administration, respectively, and of a single individual before and after initiation of Zidovudine monotherapy. We provide evidence that both therapeutic interventions enhanced the expression and activation of the C-terminal truncated isoform of STAT5 (STAT5 Delta) in vivo., (Copyright 2001 Academic Press.)