Cytokine-based modulation of immune function in HIV infection:

Antiretroviral therapy immunologic non-response in a Brazilian population: association study using pharmaco- and immunogenetic markers

Background

Antiretroviral therapy (ART) saved millions from HIV-1 infection and AIDS, but some patients do not experience adequate CD4+ T cells gain despite achieving viral suppression. The genetic component of this condition is not yet completely elucidated.

Objective

To identify predictive genetic markers of immune response to ART.

Methods

Case–control study. Out of 176 HIV-infected patients recruited in the city of Recife, Northeast Brazil, 67 patients with no immunologic response were the cases and the remaining 109 patients who responded were the controls. A set of 94 selected single nucleotide polymorphisms (SNPs) involved in antiretroviral drugs pharmacodynamic pathways and immune system homeostasis were genotyped, while the remaining 48 were ancestry informative markers (AIMs) for controlling for eventual hidden population structure.

Results

Male patients were overrepresented in non-responder group (p = 0.01). Non-responders also started with lower absolute CD4+ T cell counts (p < 0.001). We found five SNPs significantly associated with the outcome, being three more frequent in non-responders than responders: rs2243250 (IL4) A allele (p = 0.04), rs1128503 (ABCB1) A allele (p = 0.03) and rs707265 (CYP2B6) A allele (p = 0.02), whereas the other two were less frequent in non-responders: rs2069762 (IL2) C allele (p = 0.004) and rs4646437 (CYP3A4) A allele (p = 0.04).

Conclusion

Some significant univariate associations remained independently associated at multivariate survival analysis modeling, such as pre-treatment CD4+ T cells counts, IL2 and ABCB1 genotypes, and use of protease inhibitors, yielding a predictive model for the probability for immune response. More studies are needed to unravel the genetic basis of ART immunological non-response.

Perspectives on interleukin-7 therapy in HIV infection

PURPOSE OF REVIEW

HIV infection is characterized by depletion of CD4 T cells and altered immune function, leading to severe immune deficiency. Mechanisms leading to this T-cell depletion are not completely understood. Potent antiretroviral therapy restores T-cell counts and improves prognosis. Apart from antiviral therapy for the infection, immunotherapies such as interleukin-7 that influence T-cell homeostatic mechanisms are undergoing clinical evaluation. Because of its pleiotropic effects on developing and mature T cells, interleukin-7 may help to restore immune function during HIV infection.

RECENT FINDINGS

Recent studies explored the therapeutic use of interleukin-7 in simian immunodeficiency virus models and in HIV-infected patients. Interleukin-7 can help to restore CD4 T-cell number and function.

SUMMARY

Numerous recent findings highlight the importance of interleukin-7 pathway impairment in the pathogenesis of HIV infection. Notably, interleukin-7 levels increased with advancing CD4 T-cell lymphopenia, whereas interleukin-7 receptor expression is downregulated mainly on CD8 T cells. Therapeutic trials conducted in monkeys and in humans (phase I) have provided evidence on the role of interleukin-7 in thymopoiesis and in restoration of T-cell functions. Interleukin-7 appeared to be well tolerated and to have no deleterious effects on viral load. These results should be confirmed in larger phase I/II studies.

FOXP3 expression is upregulated in CD4T cells in progressive HIV-1 infection and is a marker of disease severity

Background

Understanding the role of different classes of T cells during HIV infection is critical to determining which responses correlate with protective immunity. To date, it is unclear whether alterations in regulatory T cell (Treg) function are contributory to progression of HIV infection.

Methodology

FOXP3 expression was measured by both qRT-PCR and by flow cytometry in HIV-infected individuals and uninfected controls together with expression of CD25, GITR and CTLA-4. Cultured peripheral blood mononuclear cells were stimulated with anti-CD3 and cell proliferation was assessed by CFSE dilution.

Principal Findings

HIV infected individuals had significantly higher frequencies of CD4⁺FOXP3⁺ T cells (median of 8.11%; range 1.33%–26.27%) than healthy controls (median 3.72%; range 1.3–7.5%; P = 0.002), despite having lower absolute counts of CD4⁺FOXP3⁺ T cells. There was a significant positive correlation between the frequency of CD4⁺FOXP3⁺ T cells and viral load (rho = 0.593 P = 0.003) and a significant negative correlation with CD4 count (rho = −0.423 P = 0.044). 48% of our patients had CD4 counts below 200 cells/µl and these patients showed a marked elevation of FOXP3 percentage (median 10% range 4.07%–26.27%). Assessing the mechanism of increased FOXP3 frequency, we found that the high FOXP3 levels noted in HIV infected individuals dropped rapidly in unstimulated culture conditions but could be restimulated by T cell receptor stimulation. This suggests that the high FOXP3 expression in HIV infected patients is likely due to FOXP3 upregulation by individual CD4⁺ T cells following antigenic or other stimulation.

Conclusions/Significance

FOXP3 expression in the CD4⁺ T cell population is a marker of severity of HIV infection and a potential prognostic marker of disease progression.

Immunological success is predicted by enfuvirtide but not interleukin-2 therapy in immunodepressed patients

OBJECTIVES

To evaluate the efficacy of adding interleukin-2 (IL-2) to an optimized background treatment in HIV-1 patients with advanced failure.

DESIGN

Randomized, open-label, multicentre controlled trial.

METHODS

Patients with CD4 T-cell count of less than 200 cells/microl, plasma HIV-1 RNA of more than 10 000 copies/ml and a genotypic sensitivity score showing two or less active drugs were randomized to either eight IL-2 cycles with optimized background treatment or optimized background treatment alone. Optimization was made according to genotypic sensitivity score. Enfuvirtide was added in enfuvirtide-naive patients. Evaluation was performed at week 52 on the proportions of patients with CD4 cell count of at least 200 cells/microl (primary outcome), of patients with a CD4 cell count increase of at least 50 cells/microl from week 0, on plasma HIV-1 RNA and HIV-related events.

RESULTS

Fifty-six patients were analysed. Median age was 43 years, 61% were at Center for Disease Control and Prevention stage C, 43% had a genotypic sensitivity score of 0, median baseline CD4 cell count and plasma HIV-1 RNA values were 64 cells/microl and 4.9 log10 copies/ml, respectively. Treatment could be optimized in 23 patients. At week 52, in the IL-2 and control groups, the proportion of patients with CD4 cell count of at least 200 cells/microl (14 and 18%) or a CD4 cell count increase of at least 50 cells/microl (25 and 32%) and median plasma HIV-1 RNA were not significantly different. In multivariate analysis, optimization with enfuvirtide and baseline CD4 cell count were statistically associated with CD4 cell count of at least 200 cells/microl at week 52 (P = 0.003 and P = 0.01). Optimization with enfuvirtide was the only factor associated with a CD4 cell count gain of at least 50 cells/microl (P < 0.001). There was no difference in the rate of AIDS events between groups.

CONCLUSION

IL-2 failed to increase CD4 cell count in immunocompromised patients with multiple therapeutic failures. Enfuvirtide use was highly associated with success.

Interruption of antiretroviral therapy initiated during primary HIV-1 infection: impact of a therapeutic vaccination strategy combined with interleukin (IL)-2 compared with IL-2 alone in the ANRS 095 Randomized Study

HIV-specific T cell responses play a critical role in the control of infection. We evaluated the impact of immune-based interventions in patients first treated during primary HIV-1 infection (PHI). Forty-three patients were randomized within three groups, to receive either interleukin-2 (IL-2 group), or boosts of ALVAC-HIV (vCP1433) and LIPO-6T followed by interleukin-2 (Vac-IL2 group), compared with no immune intervention (control group), and were monitored for T cell responses. Impact of strategies on viral replication was subsequently assessed during long-term treatment interruption. HIV-specific CD4(+) T cell responses did not change during the study period in immunized patients relative to controls, and vaccination had only a transient effect on interferon-gamma-producing CD8 responses. Viral rebound after treatment interruption was similar in immunized patients and controls. Forty percent of patients had HIV RNA values <10,000 copies/ml 12 weeks after interruption. The cumulative time off treatment represented almost half the total follow-up period. Immunological and virological status during PHI and HIV DNA load at interruption were predictive of the level of viral rebound after treatment interruption, whereas HIV RNA level during PHI and HIV DNA level at interruption were predictive of the time off treatment. Treatment interruption is safe in patients treated early after primary HIV infection. On the basis of this pilot study, HIV immunizations and interleukin-2 appear to have no supplementary benefit.

Combined use of cytokines, hormones and therapeutic vaccines during effective antiretroviral therapy

Immune-based therapies using vaccines, cytokines and hormones are being considered in the context of effective antiretroviral therapy to induce immunologically defined long-term nonprogressor status in chronically infected HIV-1 patients. Such immunotherapy must allow induction or regeneration of anti-HIV-1 immune responses with the potential to control viremia, activate and eradicate viral reservoirs, and alleviate the immunosuppression caused by HIV-1, eventually possibly reaching the status of a virologically defined ‘elite controller’ with an absence of detectable viremia and no progression to disease over a long period of time. This article summarizes pilot studies utilizing therapeutic vaccines, cytokines and/or hormones in treated HIV-1 infection, and focuses on novel agents and immunotherapeutic options that may have the potential to augment or replace existing antiretroviral therapy with the aim of inducing nonprogressor status in the infected host.

In HIV-1 pathogenesis the die is cast during primary infection

The chronic stage of HIV-1 infection has been extensively described as a slowly evolving phase, in which the virus induces T-cell death slightly faster than the human body is able to recover. In contrast, T-cell and viral replication dynamics during primary infection have been less well studied. Recent studies in the SIV-macaque model and in HIV-positive patients during the acute infection period have highlighted the massive and irreversible depletion of CD4 memory T cells in the mucosa, particularly in the gut. Hence, gut-associated lymphoid tissue (GALT) plays a central role in the early stages of HIV-1 pathogenesis. Due to its particular cytokine expression pattern, GALT may favour the differential replication of certain HIV-1 subtypes during primary infection, particularly of subtype C. This could enhance the chance of a successful transmission. Moreover, these early events taking place in GALT during primary infection have major implications for therapy and vaccine design.