Dynamics of T cells subsets and lymphoproliferative responses during structured treatment interruption cycles and after definitive interruption of HAART in early chronic HIV type-1-infected patients

Cyclosporine A in addition to standard ART during primary HIV-1 infection: pilot randomized clinical trial

Background

Initiating ART during acute/recent HIV-1 infection reduces viral reservoir formation. It has been proposed that, during this phase, the size of the viral reservoir could be further reduced by the association of immunomodulatory therapy with ART. Contradictory results have emerged, however, from two trials evaluating the impact on immune recovery and the viral reservoir of adding cyclosporine A to ART during primary HIV-1 infection.

Patients and methods

Twenty patients with acute/recent HIV-1 infection were randomized to receive ART alone (tenofovir, emtricitabine and lopinavir/ritonavir) or associated with 8 weeks of cyclosporine A (0.3-0.6 mg/kg twice daily). The impact on viral load, immune response and integrated and non-integrated DNA viral reservoir at 0, 8 and 36 weeks of treatment was evaluated.

Results

The estimated median time from HIV-1 infection to ART onset was 63 days (IQR 53; 79.5) with 90% of patients at Fiebig V stage. No significant differences were observed in viral load decay, CD4 T cell recovery, immune response markers or the evolution of integrated DNA at week 8 (end of cyclosporine A) and week 36 between groups. However, non-integrated DNA significantly increased in the cyclosporine A arm between weeks 0 and 36. Cyclosporine A was well tolerated.

Conclusions

Adding cyclosporine A to ART during acute/recent infection did not improve immune recovery. However, unintegrated DNA increased in the cyclosporine A group, suggesting an anti-integration effect, a point warranting further research (ClinicalTrials.gov Identifier: NCT00979706).

The immunological and virological consequences of planned treatment interruptions in children with HIV infection

OBJECTIVES

To evaluate the immunological and viral consequences of planned treatment interruptions (PTI) in children with HIV.

DESIGN

This was an immunological and virological sub-study of the Paediatric European Network for Treatment of AIDS (PENTA) 11 trial, which compared CD4-guided PTI of antiretroviral therapy (ART) with continuous therapy (CT) in children.

METHODS

HIV-1 RNA and lymphocyte subsets, including CD4 and CD8 cells, were quantified on fresh samples collected during the study; CD45RA, CD45RO and CD31 subpopulations were evaluated in some centres. For 36 (18 PTI, 18 CT) children, immunophenotyping was performed and cell-associated HIV-1 DNA analysed on stored samples to 48 weeks.

RESULTS

In the PTI group, CD4 cell count fell rapidly in the first 12 weeks off ART, with decreases in both naïve and memory cells. However, the proportion of CD4 cells expressing CD45RA and CD45RO remained constant in both groups. The increase in CD8 cells in the first 12 weeks off ART in the PTI group was predominantly due to increases in RO-expressing cells. PTI was associated with a rapid and sustained increase in CD4 cells expressing Ki67 and HLA-DR, and increased levels of HIV-1 DNA.

CONCLUSIONS

PTI in children is associated with rapid changes in CD4 and CD8 cells, likely due to increased cell turnover and immune activation. However, children off treatment may be able to maintain stable levels of naïve CD4 cells, at least in proportion to the memory cell pool, which may in part explain the observed excellent CD4 cell recovery with re-introduction of ART.

Influence of episodes of intermittent viremia ("blips") on immune responses and viral load rebound in successfully treated HIV-infected patients

Presenting episodes of intermittent viremia (EIV) under combination antiretroviral therapy (cART) is frequent, but there exists some controversy about their consequences. They have been described as inducing changes in immune responses potentially associated with a better control of HIV infection. Conversely, it has been suggested that EIV increases the risk of virological failure. A retrospective analysis of a prospective, randomized double-blinded placebo-controlled study was performed. Twenty-six successfully treated HIV-infected adults were randomized to receive an immunization schedule or placebo, and after 1 year of follow-up cART was discontinued. The influence of EIV on T cell subsets, HIV-1-specific T cell immune responses, and viral load rebound, and the risk of developing genotypic mutations were evaluated, taking into account the immunization received. Patients with EIV above 200 copies/ml under cART had a lower proportion of CD4(+) and CD4(+)CD45RA(+)RO(-) T cells, a higher proportion of CD8(+) and CD4(+)CD38(+)HLADR(+) T cells, and higher HIV-specific CD8(+) T cell responses compared to persistently undetectable patients. After cART interruption, patients with EIV presented a significantly higher viral rebound (p=0.007), associated with greater increases in HIV-specific lymphoproliferative responses and T cell populations with activation markers. When patients with EIV between 20 and 200 copies/ml were included, most of the differences disappeared. Patients who present EIV above 200 copies/ml showed a lower CD4(+) T cell count and higher activation markers under cART. After treatment interruption, they showed greater specific immune responses against HIV, which did not prevent a higher virological rebound. EIV between 20 and 200 copies/ml did not have this deleterious effect.

Generation and characterization of a defective HIV-1 Virus as an immunogen for a therapeutic vaccine

BACKGROUND

The generation of new immunogens able to elicit strong specific immune responses remains a major challenge in the attempts to obtain a prophylactic or therapeutic vaccine against HIV/AIDS. We designed and constructed a defective recombinant virus based on the HIV-1 genome generating infective but non-replicative virions able to elicit broad and strong cellular immune responses in HIV-1 seropositive individuals.

RESULTS

Viral particles were generated through transient transfection in producer cells (293-T) of a full length HIV-1 DNA carrying a deletion of 892 base pairs (bp) in the pol gene encompassing the sequence that codes for the reverse transcriptase (NL4-3/ΔRT clone). The viral particles generated were able to enter target cells, but due to the absence of reverse transcriptase no replication was detected. The immunogenic capacity of these particles was assessed by ELISPOT to determine γ-interferon production in a cohort of 69 chronic asymptomatic HIV-1 seropositive individuals. Surprisingly, defective particles produced from NL4-3/ΔRT triggered stronger cellular responses than wild-type HIV-1 viruses inactivated with Aldrithiol-2 (AT-2) and in a larger proportion of individuals (55% versus 23% seropositive individuals tested). Electron microscopy showed that NL4-3/ΔRT virions display immature morphology. Interestingly, wild-type viruses treated with Amprenavir (APV) to induce defective core maturation also induced stronger responses than the same viral particles generated in the absence of protease inhibitors.

CONCLUSIONS

We propose that immature HIV-1 virions generated from NL4-3/ΔRT viral clones may represent new prototypes of immunogens with a safer profile and stronger capacity to induce cellular immune responses than wild-type inactivated viral particles.

Immune reconstitution in severely immunosuppressed antiretroviral-naive HIV type 1-infected patients using a nonnucleoside reverse transcriptase inhibitor-based or a boosted protease inhibitor-based antiretroviral regimen: three-year results (The Advanz Trial): a randomized, controlled trial

Late diagnosis of HIV-1 infection is quite frequent in Western countries. Very few randomized clinical trials to determine the best antiretroviral treatment in patients with advanced HIV-1 infection have been performed. To compare immune reconstitution in two groups of very immunosuppressed (less than 100 CD4(+) cells/microl), antiretroviral-naive HIV-1-infected adults, 65 patients were randomly assigned in a 1:1 ratio to receive zidovudine + lamivudine + efavirenz (group A, 34 patients) or zidovudine + lamivudine + ritonavir-boosted indinavir (group B, 31 patients). The median (interquartile range) CD4(+) cell increase after 12 and 36 months was +199 (101, 258) and +299 (170, 464) cells/microl in the efavirenz arm and +136 (57, 235) and +228 (119, 465) cells/microl in the ritonavir-boosted indinavir arm (p > 0.05 for all time points). The proportion (95% confidence interval) of patients achieving HIV-1 RNA levels under 50 copies/ml was significantly greater in the efavirenz arm at 3 years by the intention-to-treat analysis [59% (41%, 75%) vs. 23% (10%, 41%)], whereas no differences were found in the on-treatment analysis. Immune activation (CD8(+)CD38(+) and CD8(+)CD38DR(+) T cells) was significantly lower for the efavirenz arm from month 6 to month 24. Adverse events were more frequent in the ritonavir-boosted indinavir arm. Almost all cases of disease progression and death were observed in the first year of treatment, with no significant differences between the two arms (p = 0.79 by the log-rank test). At 1 and 3 years, the immune reconstitution induced by an efavirenz-based regimen in very immunosuppressed patients was at least as potent as that induced by a ritonavir-boosted protease inhibitor-based antiretroviral regimen.

Treatment interruption in chronic HIV-1 infection: does it deliver?

PURPOSE OF REVIEW

This review sets out to overview treatment interruption in chronic HIV-1 infection: what treatment interruption promised, results from recent trials, and what the future holds.

RECENT FINDINGS

Recent studies have produced mixed results; several trials have been prematurely halted, whereas others have reported more positive outcomes. One consistent finding has been the identification of the CD4 T-cell count nadir as a critical parameter in determining the outcome of treatment interruption.

SUMMARY

The use of treatment interruption is still controversial, but it is becoming clear that certain individuals could benefit, and partial treatment interruption strategies warrant further investigation.

Influence of a vaccination schedule on viral load rebound and immune responses in successfully treated HIV-infected patients

Vaccination is recommended for HIV-infected patients. Transient increases of viral load (VL) and risk of developing resistance to HAART have been described. In addition, VL rebounds could increase HIV-specific immune responses. Twenty-six successfully treated HIV-infected adults were randomized to receive a vaccination schedule or placebo during 12 months. Afterward, HAART was discontinued. Influences of vaccination over VL, genotypic mutations, different T cell subsets, and HIV-1-specific immune responses were evaluated. Patients did not present any secondary effect. No differences in incidence of detectable VL determinations were detected between groups [relative risk 0.54 (95% CI 0.23-1.26)]. No relevant resistance mutations were detected. The vaccinated group showed a significant drop in CD4(+) T cells (p = 0.046) associated with increases in activated T cells. HIV-1-specific lymphoproliferative responses increased more in the vaccinated group during the vaccination period. Viral rebound dynamics after interrupting HAART were similar in both groups. A vaccination schedule in successfully treated HIV patients was safe, was not associated with an increase in detectable VL, and did not increase the risk of developing resistance mutations. However, it induced an increase in T cell activation and a drop in CD4(+) T cells, although these changes did not influence the VL rebound dynamics after HAART interruption.

Short Communication: Natural killer cells and expression of KIR receptors in chronic HIV type 1-infected patients after different strategies of structured therapy interruption

Few data evaluating the NK cell profile during structured therapy interruption (STI) in chronic HIV-1 infection are available. Changes in NK cell percentages and KIR and NKG2A receptors were analyzed at baseline and after 2 years of follow-up in 121 patients on ART with CD4(+) >450 cells/ml and VL <200 copies/ml randomized in three arms according to the criteria employed to resume ART during STI: virological arm (VA n = 47, VL >30,000 copies/ml or CD4 <350 cells/ml), immunological arm (IA n = 37, CD4< 350 cells/ml), and a control arm (n = 37) in which ART was maintained. After 2 years of follow-up, a decrease in CD3(-)CD56(+) CD16(+) cell percentages in VA and IA patients, but not in CA patients, was observed. Those patients with higher decrease in CD3(-)CD56(+)CD16(+) cells had a higher decrease in CD4(+) cells (r = 0.35, p = 0.001) and higher increase in PVL (r = -0.26, p = 0.02). KIR and NKG2A receptor expression tended to increase in CA and decreased in the other two arms (more in IA than in VA). Patients who displayed a greater decrease in CD4(+) T cells and a greater rise in PVL after 2 years of follow-up had a significantly higher decrease in KIR and NKG2A receptors expressed in CD3(-)CD56(+) cells. Patients who presented the lowest levels of total NK cells and KIR and NKG2A receptor expression after STI showed the poorest virology or immunology outcomes. This finding suggests that STI could decrease the number of NK subsets, which is related to the worst clinical development in these patients.

Delipidated Retroviruses as Potential Autologous Therapeutic Vaccines—A Pilot Experiment

This pilot experiment in a simian immunodeficiency virus (SIV) chronic infection model aimed at extending our previous findings that vaccination with delipidated SIV resulted in more potent and diversified antiviral responses ( 1 ). Macaques chronically infected with SIVmac239 treated with antiretroviral therapy (ART) were vaccinated with autologous delipidated virus via consecutive lymph node targeted immunizations-1, 1 and 10 μg of virus spaced monthly. Results showed all animals had lasting viral load reduction approaching 1 log compared to set-point, and disease delay. Delipidation may enhance processing/ presentation of viral antigen eliciting potent antiviral control even at such late infection stage.

Treatment interruption strategies: how great are the risks?

PURPOSE OF REVIEW

This review brings together the results of recent definitive trials of treatment interruption strategies in order to evaluate the risks and to examine whether there is evidence to support this approach in clinical practice.

RECENT FINDINGS

Recent studies confirm that there is no clear benefit of treatment interruption in the settings of virological failure or acute infection. The most important recent data relate to the use of structured treatment interruption in the setting of chronic HIV disease. The SMART and Trivacan trials found that a CD4 lymphocyte count guided interruption strategy was clearly inferior to continuous therapy, but Staccato (using a higher threshold for treatment re-initiation) did not. The largest fixed-schedule treatment interruption trial also reported inferior clinical outcomes with interruption, although the evidence of harm was less clear in other smaller studies. A broad spectrum of clinical effects of treatment interruption was highlighted by this research.

SUMMARY

Overall, recent studies indicate that treatment interruption is associated with a variable degree of net harm. Continuous treatment should remain the strongly preferred approach, although, if it is carefully managed, there may be some clinical situations in which the benefits of a short period of interruption may potentially outweigh the risks.

MyD88-dependent immune activation mediated by human immunodeficiency virus type 1-encoded Toll-like receptor ligands

Immune activation is a major characteristic of human immunodeficiency virus type 1 (HIV-1) infection and a strong prognostic factor for HIV-1 disease progression. The underlying mechanisms leading to immune activation in viremic HIV-1 infection, however, are not fully understood. Here we show that, following the initiation of highly active antiretroviral therapy, the immediate decline of immune activation is closely associated with the reduction of HIV-1 viremia, which suggests a direct contribution of HIV-1 itself to immune activation. To propose a mechanism, we demonstrate that the single-stranded RNA of HIV-1 encodes multiple uridine-rich Toll-like receptor 7/8 (TLR7/8) ligands that induce strong MyD88-dependent plasmacytoid dendritic cell and monocyte activation, as well as accessory cell-dependent T-cell activation. HIV-1-encoded TLR ligands may, therefore, directly contribute to the immune activation observed during viremic HIV-1 infection. These data provide an initial rationale for inhibiting the TLR pathway to directly reduce the chronic immune activation induced by HIV-1 and the associated immune pathogenesis.