Phase II, randomized, open-label, community-based trial to compare the safety and activity of combination therapy with recombinant interferon-alpha2b and zidovudine versus zidovudine alone in patients with asymptomatic to mildly symptomatic HIV infection. HIV Protocol C91-253 Study Team

Expression Pattern of Individual IFNA Subtypes in Chronic HIV Infection

Interferon-α (IFN-α) plays an important role in HIV pathogenesis. IFN-α consists of 13 individual IFN-α subtypes, which exhibit individual antiviral and immunomodulatory activities in HIV infection. Here, we determined the expression profiles of all IFN-α subtypes in treated and treatment-naive HIV⁺ patients and their impact on the induction of distinct HIV restriction factors. We collected blood samples of chronic HIV⁺ patients, which underwent antiretroviral therapy or were treatment-naive, and determined the individual expression levels of different IFN-α subtypes and HIV restriction factors. HIV infection transiently enhanced the expression of IFNA mRNA. The IFN-α response was dominated by the most abundantly expressed subtypes IFNA4, A5, A7, and A14 in all individuals. HIV infection affected the expression pattern of the IFN-α response, in particular for IFNA2 and IFNA16, which were elevated by chronic HIV infection. Elevated expression of HIV restriction factors was observed in chronically HIV-infected patients, which partly decreased during successful antiretroviral treatment. In vitro stimulation of peripheral blood mononuclear cells revealed that IFN-α6, -α14, and -α21 were most effective in inducing the expression of HIV restriction factors. These results indicate that HIV infection induces a specific expression pattern of IFN-α subtypes, which in turn induce the expression of various HIV restriction factors.

Interferons and HIV Infection: The Good, the Bad, and the Ugly

Whether type I interferons (IFNs) hinder or facilitate HIV disease progression is controversial. Type I IFNs induce the production of restriction factors that protect against mucosal HIV/SIV acquisition and limit virus replication once systemic infection is established. However, type I IFNs also increase systemic immune activation, a predictor of poor CD4⁺ T-cell recovery and progression to AIDS, and facilitate production and recruitment of target CD4⁺ T cells. In addition, type I IFNs induce CD4⁺ T-cell apoptosis and limit antigen-specific CD4⁺ and CD8⁺ T-cell responses. The outcomes of type I IFN signaling may depend on the timing of IFN-stimulated gene upregulation relative to HIV exposure and infection, local versus systemic type I IFN-stimulated gene expression, and the subtype of type I IFN evaluated. To date, most interventional studies have evaluated IFNα2 administration largely in chronic HIV infection, and few have evaluated the effects on tissues or the HIV reservoir. Thus, whether the effect of type I IFN signaling on HIV disease is good, bad, or so complicated as to be ugly remains a topic of hot debate.

Interferon Alpha Subtype-Specific Suppression of HIV-1 Infection In Vivo

Although all 12 subtypes of human interferon alpha (IFN-α) bind the same receptor, recent results have demonstrated that they elicit unique host responses and display distinct efficacies in the control of different viral infections. The IFN-α2 subtype is currently in HIV-1 clinical trials, but it has not consistently reduced viral loads in HIV-1 patients and is not the most effective subtype against HIV-1 in vitro We now demonstrate in humanized mice that, when delivered at the same high clinical dose, the human IFN-α14 subtype has very potent anti-HIV-1 activity whereas IFN-α2 does not. In both postexposure prophylaxis and treatment of acute infections, IFN-α14, but not IFN-α2, significantly suppressed HIV-1 replication and proviral loads. Furthermore, HIV-1-induced immune hyperactivation, which is a prognosticator of disease progression, was reduced by IFN-α14 but not IFN-α2. Whereas ineffective IFN-α2 therapy was associated with CD8(+) T cell activation, successful IFN-α14 therapy was associated with increased intrinsic and innate immunity, including significantly higher induction of tetherin and MX2, increased APOBEC3G signature mutations in HIV-1 proviral DNA, and higher frequencies of TRAIL(+) NK cells. These results identify IFN-α14 as a potent new therapeutic that operates via mechanisms distinct from those of antiretroviral drugs. The ability of IFN-α14 to reduce both viremia and proviral loads in vivo suggests that it has strong potential as a component of a cure strategy for HIV-1 infections. The broad implication of these results is that the antiviral efficacy of each individual IFN-α subtype should be evaluated against the specific virus being treated.

IMPORTANCE

The naturally occurring antiviral protein IFN-α2 is used to treat hepatitis viruses but has proven rather ineffective against HIV in comparison to triple therapy with the antiretroviral (ARV) drugs. Although ARVs suppress the replication of HIV, they fail to completely clear infections. Since IFN-α acts by different mechanism than ARVs and has been shown to reduce HIV proviral loads, clinical trials are under way to test whether IFN-α2 combined with ARVs might eradicate HIV-1 infections. IFN-α is actually a family of 12 distinct proteins, and each IFN-α subtype has different efficacies toward different viruses. Here, we use mice that contain a human immune system, so they can be infected with HIV. With this model, we demonstrate that while IFN-α2 is only weakly effective against HIV, IFN-α14 is extremely potent. This discovery identifies IFN-α14 as a more powerful IFN-α subtype for use in combination therapy trials aimed toward an HIV cure.

Soluble mediators of inflammation in HIV and their implications for therapeutics and vaccine development

From early in the HIV epidemic it was appreciated that many inflammatory markers such as neopterin and TNF-α were elevated in patients with AIDS. With the advent of modern technology able to measure a broad array of cytokines, we now know that from the earliest points of infection HIV induces a cytokine storm. This review will focus on how cytokines are disturbed in HIV infection and will explore potential therapeutic uses of cytokines. These factors can be used directly as therapy during HIV infection, either to suppress viral replication or prevent deleterious immune effects of infection, such as CD4+ T cell depletion. Cytokines also show great promise as adjuvants in the development of HIV vaccines, which would be critical for the eventual control of the epidemic.

Multiple levels of PKR inhibition during HIV-1 replication

Recent therapeutic approaches against HIV-1 include IFN in combination therapy for patients with coinfections or as an alternative strategy against the virus. These treatment options require a better understanding of the weak efficacy of the IFN-stimulated genes, such as the protein kinase RNA-activated (PKR), which results in viral progression. Activated PKR has a strong antiviral activity on HIV-1 expression and production in cell culture. However, PKR is not activated upon HIV-1 infection when the virus reaches high levels of replication, due to viral and cellular controls. PKR is activated by low levels of the HIV-1 trans-activation response (TAR) RNA element, but is inhibited by high levels of this double-stranded RNA. The viral Tat protein also counteracts PKR activation by several mechanisms. In addition, HIV-1 replicates only in cells that have a high level of the TAR RNA binding protein (TRBP), a strong inhibitor of PKR activation. Furthermore, increased levels of adenosine deaminase acting on RNA (ADAR1) are observed when HIV-1 replicates at high levels and the protein binds to PKR and inhibits its activation. Finally, the PKR activator (PACT) also binds to PKR during HIV-1 replication with no subsequent kinase activation. The combination of all the inhibiting pathways that prevent PKR phosphorylation contributes to a high HIV-1 production in permissive cells. Enhancing PKR activation by counteracting its inhibitory partners could establish an increased innate immune antiviral pathway against HIV-1 and could enhance the efficacy of the IFN treatment.

Adjuvant high-dose interferon-{alpha} for resected melanoma in a patient with HIV infection

Adjuvant interferon (IFN)-alpha remains the standard adjuvant therapy for intermediate and high-risk melanoma after definitive surgical resection. Data addressing the role and safety of adjuvant immunotherapy in HIV-infected patients with melanoma are lacking. We report on an HIV(+) patient who received IFN-alpha as adjuvant treatment for high-risk melanoma. To our knowledge, this is the first reported case of such an approach.

Safety, tolerability, and mechanisms of antiretroviral activity of pegylated interferon Alfa-2a in HIV-1-monoinfected participants: a phase II clinical trial

BACKGROUND

To our knowledge, the antiviral activity of pegylated interferon alfa-2a has not been studied in participants with untreated human immunodeficiency virus type 1 (HIV-1) infection but without chronic hepatitis C virus (HCV) infection.

METHODS

Untreated HIV-1-infected volunteers without HCV infection received 180 microg of pegylated interferon alfa-2a weekly for 12 weeks. Changes in plasma HIV-1 RNA load, CD4(+) T cell counts, pharmacokinetics, pharmacodynamic measurements of 2',5'-oligoadenylate synthetase (OAS) activity, and induction levels of interferon-inducible genes (IFIGs) were measured. Nonparametric statistical analysis was performed.

RESULTS

Eleven participants completed 12 weeks of therapy. The median plasma viral load decrease and change in CD4(+) T cell counts at week 12 were 0.61 log(10) copies/mL (90% confidence interval [CI], 0.20-1.18 log(10) copies/mL) and -44 cells/microL (90% CI, -95 to 85 cells/microL), respectively. There was no correlation between plasma viral load decreases and concurrent pegylated interferon plasma concentrations. However, participants with larger increases in OAS level exhibited greater decreases in plasma viral load at weeks 1 and 2 (r = -0.75 [90% CI, -0.93 to -0.28] and r = -0.61 [90% CI, -0.87 to -0.09], respectively; estimated Spearman rank correlation). Participants with higher baseline IFIG levels had smaller week 12 decreases in plasma viral load (0.66 log(10) copies/mL [90% CI, 0.06-0.91 log(10) copies/mL]), whereas those with larger IFIG induction levels exhibited larger decreases in plasma viral load (-0.74 log(10) copies/mL [90% CI, -0.93 to -0.21 log(10) copies/mL]).

CONCLUSION

Pegylated interferon alfa-2a was well tolerated and exhibited statistically significant anti-HIV-1 activity in HIV-1-monoinfected patients. The anti-HIV-1 effect correlated with OAS protein levels (weeks 1 and 2) and IFIG induction levels (week 12) but not with pegylated interferon concentrations.

Interferons and their use in persistent viral infections

In 2007, the world celebrated the 50th anniversary of the discovery of interferon (IFN) by Isaacs and Lindenmann. Subsequently, the IFN-alpha gene was cloned, fully sequenced and IFN-alpha was produced in recombinant form. Recombinant IFN-alpha is now used as the basis for treatment of chronic hepatitis C virus infection and can also be used to treat certain forms of chronic hepatitis B virus infections. IFNs have also been used in other viral infections, although with less success. The antiviral mechanisms of IFNs are reviewed in this chapter as well as the utility of IFNs in the treatment of persistent viral infections.

Interferons at age 50: past, current and future impact on biomedicine

The family of interferon (IFN) proteins has now more than reached the potential envisioned by early discovering virologists: IFNs are not only antivirals with a spectrum of clinical effectiveness against both RNA and DNA viruses, but are also the prototypic biological response modifiers for oncology, and show effectiveness in suppressing manifestations of multiple sclerosis. Studies of IFNs have resulted in fundamental insights into cellular signalling mechanisms, gene transcription and innate and acquired immunity. Further elucidation of the multitude of IFN-induced genes, as well as drug development strategies targeting IFN production via the activation of the Toll-like receptors (TLRs), will almost certainly lead to newer and more efficacious therapeutics. Our goal is to offer a molecular and clinical perspective that will enable IFNs or their TLR agonist inducers to reach their full clinical potential.

AIDS-associated Kaposi's sarcoma: is there still a role for interferon alfa?

Interferon alfa (IFNalpha) was one of the first agents to be used therapeutically in AIDS-associated Kaposi's sarcoma (KS) more than 25 years ago, and induces tumor regression in a subset of patients. Although much has been learned about the clinical role of IFNalpha in KS treatment, little is currently known about the mechanism(s) by which IFNalpha causes KS regression. This is despite a growing understanding of both KS pathogenesis and relevant IFNalpha activities. To a large extent other agents have supplanted IFNalpha as treatments for KS, but there may still remain a therapeutic role for IFNalpha, possibly in combination with other agents targeting angiogenesis and/or HHV-8-encoded human gene homologs that encode proteins involved in cell cycle regulation and signaling.

Treatment of hepatitis C virus and HIV co-infections

Hepatitis C coinfection is common in patients with HIV, particularly in injection-drug users. Hepatitis C virus levels tend to be higher in coinfected patients, and histologic progression is more rapid than in patients with HCV alone. The efficacy of interferon monotherapy in HIV patients with an adequate CD4 cell count is comparable to that observed in patients without HIV. The combination of interferon plus ribavirin and pegylated interferon will further improve response rates. Interferon therapy is associated with leukopenia and a decrease in absolute CD4 cell count. Some concern remains that ribavirin might reduce the activity of pyrimidine analogues such as zidovudine and stavudine, and HIV-RNA levels should be followed when these medications are given concurrently. It is hoped that in time, new drug development will make the multiple-drug therapeutic strategy that has been highly successful in the management of HIV feasible for the treatment of HCV.