The effect of long-term treatment with granulocyte colony-stimulating factor on hematopoiesis in HIV-infected individuals

The role of polymorphonuclear neutrophils during HIV-1 infection

It is well-recognized that human immunodeficiency virus type-1 (HIV-1) mainly targets CD4⁺ T cells and macrophages. Nonetheless, during the past three decades, a huge number of studies have reported that HIV-1 can directly or indirectly target other cellular components of the immune system including CD8⁺ T cells, B cells, dendritic cells, natural killer cells, and polymorphonuclear neutrophils (PMNs), among others. PMNs are the most abundant leukocytes in the human circulation, and are known to play principal roles in the elimination of invading pathogens, regulating different immune responses, healing of injured tissues, and maintaining mucosal homeostasis. Until recently, little was known about the impact of HIV-1 infection on PMNs as well as the impact of PMNs on HIV-1 disease progression. This is because early studies focused on neutropenia and recurrent microbial infections, particularly, during advanced disease. However, recent studies have extended the investigation area to cover new aspects of the interactions between HIV-1 and PMNs. This review aims to summarize these advances and address the impact of HIV-1 infection on PMNs as well as the impact of PMNs on HIV-1 disease progression to better understand the pathophysiology of HIV-1 infection.

Neutropenia during HIV infection: adverse consequences and remedies

Neutropenia frequently occurs in patients with Human immunodeficiency virus (HIV) infection. Causes for neutropenia during HIV infection are multifactoral, including the viral toxicity to hematopoietic tissue, the use of myelotoxic agents for treatment, complication with secondary infections and malignancies, as well as the patient's association with confounding factors which impair myelopoiesis. An increased prevalence and severity of neutropenia is commonly seen in advanced stages of HIV disease. Decline of neutrophil phagocytic defense in combination with the failure of adaptive immunity renders the host highly susceptible to developing fatal secondary infections. Neutropenia and myelosuppression also restrict the use of many antimicrobial agents for treatment of infections caused by HIV and opportunistic pathogens. In recent years, HIV infection has increasingly become a chronic disease because of progress in antiretroviral therapy (ART). Prevention and treatment of severe neutropenia becomes critical for improving the survival of HIV-infected patients.

Natural products and synthetic compounds as immunomodulators

Research on immunomodulation by natural products or synthetic derivatives is of key interest for anti-infective therapy for a number of reasons. Many plant remedies well-known in traditional medicine or refined natural products in clinical use exert their anti-infective effects not only (if at all) by directly affecting the pathogen. At least part of their effect is indirect, by stimulating natural and adaptive defense mechanisms of the host. These findings have now given many empirical therapies a rationale, scientific basis and thereby a means for 'intelligent' improvement. In discovering the molecular mechanisms by which known remedies exert their effects, chosen elements further down the 'chain of command' might be synthesized and applied directly for more rapid and selective cure, omitting unwanted side effects. The direct use of recombinant cytokines, often in combination with antibiotics, is one consequence of this rationale.

T-lymphocyte perturbation following large-scale apheresis and hematopoietic stem cell transplantation in HIV-infected individuals

Analysis and mathematical modeling of T-lymphocyte perturbation following administration of granulocyte colony stimulating factor (G-CSF) and two large-scale aphereses are reported. 74 HIV-1 positive antiretroviral-treated individuals were infused with gene- or sham-transduced CD34+ hematopoietic stem cells (HSC) in a Phase II clinical trial. T cell numbers were examined in four phases: 1) during steady state; 2) increases in peripheral blood (PB) following G-CSF administration; 3) depletion post-aphereses and 4) reconstitution post HSC infusion. The present analysis provides the first direct estimate of CD4+ T cell distribution and trafficking in HIV-infected individuals on stable HAART, indicating that CD4+ T lymphocytes in PB represent 5.5% of the pool of CD4+ T lymphocytes that traffic to PB.

Use of Filgrastim (r-metHuG-CSF) in Human Immunodeficiency Virus Infection

In 2008, an estimated 33.4 million individuals worldwide were infected with the human immunodeficiency virus (HIV) [1]. Only a few years ago, infection with HIV almost invariably culminated in the development of the acquired immunodeficiency syndrome (AIDS), characterized by severe depletion of CD4⁺ lymphocytes leading to derangements predominantly affecting cell-mediated immunity, but affecting humoral immunity as well [2]. In the later stages of AIDS, neutropenia and neutrophil functional deficits were common sequelae of HIV infection, other opportunistic infections, or HIV- or opportunistic infection-related treatment [3]. The care of the HIV-infected patient was palliative in nature, and the possibility that use of filgrastim (rHuG-CSF) might extend survival in late-stage AIDS patients with severe neutropenia or severe opportunistic infections, or might be a treatment for HIV infection itself, was explored [4]. Subsequently, however, the development of protease inhibitors and the widespread adoption of their use in multidrug regimens of highly active antiretroviral therapy (HAART) revolutionized the care of HIV-infected patients, and the number of patients dying from HIV decreased dramatically [5].

Current treatment strategies for patients with Hodgkin's lymphoma and HIV infection

Hodgkin's lymphoma is the most common non-AIDS-defining tumor diagnosed in HIV-infected patients. Although the introduction of highly active antiretroviral therapy (HAART) led to a decreased incidence of several malignancies among HIV-infected patients, the incidence of HIV-associated Hodgkin's lymphoma (HIV-HL) has been persistent in recent years. Its unusually aggressive tumor behavior includes a higher frequency of unfavorable histologic subtypes, high stage and extranodal involvement by the time of presentation and poor therapeutic outcome, in comparison with Hodgkin's lymphoma outside the HIV setting. Treatment of HIV-HL is challenging considering the underlying immunodeficiency caused by HIV itself and may increase the risk of opportunistic infections by inducing further immunosuppression. To address this delicate vulnerability of the HIV-infected host, tailored regimens, which are less aggressive than standard regimens for HIV-negative hosts, have been applied to achieve tumor control. The introduction of HAART has opened a new perspective in the treatment of HIV-associated malignancies. The improved control of HIV infection and the subsequently improved survival rates of HIV-infected patients has changed the goal from tumor control to cure and new treatment approaches with more potent regimens need to be evaluated to improve survival and quality of life in HIV-HL.

Increase in plasmacytoid and myeloid dendritic cells by progenipoietin-1, a chimeric Flt-3 and G-CSF receptor agonist, in SIV-Infected rhesus macaques

As in HIV-1 infection in humans, SIVsm infection of rhesus macaques causes a slow progressive loss of CD4 T-cells followed by the onset of AIDS. In addition, there is a loss of dendritic cells (DC) in peripheral blood, peripheral lymphoid tissues, and the skin. Increasing the number of CD4 T cells and DC may be an important step in restoring immune competence and thus delay disease progression. Recently, progenipoietins (ProGP), a new family of chimeric Flt3 and G-CSF receptor agonists, were demonstrated to possess the capacity to mobilize hematopoietic progenitor cells in normal rhesus monkeys. In addition, these molecules induced increased numbers of myeloid cells, including dendritic cells, in the blood. Here we demonstrate that SIVsm-infected macaques, treated with ProGP-1, developed increased numbers of both plasmacytoid (CD123+, CD11c-) and myeloid (both CD11b+, CD11c+, and CD123-, CD11c+ subsets) DC and CD4 and CD8 T cells in peripheral blood. Importantly, during treatment, no changes in plasma virus load were observed. After 14 to 20 days of treatment, antibodies were formed against ProGP in all animals. As a consequence, white blood cell levels returned to baseline in several animals. In other animals values only returned to baseline after termination of ProGP treatment. In conclusion, ProGP-1 may be used to generate a transient increase in DC as well as CD4 T-cell numbers, thereby creating a window of opportunity for immunotherapeutic intervention.

Filgrastim in patients with neutropenia: potential effects on quality of life

Treatment- and disease-related neutropenia are associated with a number of negative clinical effects such as febrile neutropenia, documented infection, hospitalisation for infection-related morbidity, infection-related mortality, and decreased ability to administer the planned chemotherapy dose on schedule. Reductions or delays in dosage have the ability to jeopardise the effectiveness of treatment by lowering response rates. Not only are clinical outcomes adversely affected, but these complications can have a negative influence on patient quality of life. Filgrastim is a haematopoietic growth factor that primarily acts to stimulate the proliferation and differentiation of neutrophil progenitor cells. Filgrastim is capable of reducing the incidence and severity of neutropenia and the complications that accompany it in patients with cancer or HIV infection. Although there are few data evaluating the effect of treatment with granulocyte colony-stimulating factor on quality of life, it is assumed that the benefits would be seen through both the reduction of treatment-related complications and the enhanced potential for long-term disease control. A new, longer-acting form of filgrastim is now available that has the potential to simplify the management of neutropenia and further improve patient quality of life by decreasing the number of necessary injections. Additional prospective controlled trials that contain quality-of-life issues as endpoints are needed.

Clinical tolerance and immunologic effects after single or repeated administrations of the synthetic immunomodulator murabutide in HIV-1-infected patients

Correction of the virus-induced deficits in innate immunity of HIV-infected subjects could well contribute to enhanced immune recovery and efficacious control of viral replication. The safe synthetic immunomodulator Murabutide (ISTAC Biotechnology, Lille, France) has been found to regulate the function of antigen-presenting cells and to selectively activate CD4 lymphocytes leading to dramatic suppression of HIV replication, in vitro. Therefore, as a first step toward the evaluation of the immunotherapeutic potential of Murabutide in HIV disease, we have conducted two phase 1/2 clinical trials to address the safety and the immunologic effects of Murabutide administration into HIV-infected subjects receiving antiretroviral therapy. The first study revealed that single administration of 5, 7, or 9 mg of Murabutide, to 6 patients per dose, was well tolerated. This was accompanied by a selective induction of cytokines and chemokines detectable in the serum, and the levels appeared to plateau at the 7-mg dose. The second study then evaluated the safety and biological effects of repeated administrations of 7 mg Murabutide, on 5 consecutive days, in 12 HIV-1-infected patients. A good clinical tolerance was noted throughout the study. Moreover, changes in several immune parameters, including downregulation of coreceptor expression on lymphocytes and improved lymphoproliferative responses, were detected during or/and up to 3 weeks after Murabutide administration. These encouraging results warrant further evaluation of longer periods or cycles of immunotherapy with Murabutide in HIV-infected subjects.

Treatment of hepatitis C and anemia in human immunodeficiency virus-infected patients

Because of shared modes of transmission, co-infection with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) is common. Co-infection with HIV increases HCV virus load, liver-related mortality, and the risk of sexual and perinatal transmission of HCV, and it may accelerate HCV disease progression. With combination interferon (IFN)-alpha 2b/ribavirin or pegylated IFN-alpha 2b/ribavirin therapy, long-term remission is possible for HCV-infected patients. Preliminary evidence suggests that the combination of IFN-alpha 2b/ribavirin can achieve similar response rates in HCV/HIV-co-infected individuals with no adverse effect on HIV RNA concentrations. Although adverse effects are more frequent with combination therapy than with IFN-alpha monotherapy, most are manageable. In addition, few instances of drug-drug antagonism have been reported among drugs used to treat each disease, although further study is necessary. Ribavirin-associated hemolytic anemia is a potential problem in a patient population that is already susceptible to anemia but is manageable with recombinant human erythropoietin (epoetin alfa).

Clinical tolerance and profile of cytokine induction in healthy volunteers following the simultaneous administration of ifn-alpha and the synthetic immunomodulator murabutide

As the therapeutic use of interferon-alpha (IFN-alpha) is limited by a dose-dependent toxicity and variable efficacy, ways of improving the therapeutic index of the cytokine are being sought. Murabutide (N-acetyl muramyl-L-alanyl-D-glutamine-O-n-butyl-ester) (ISTAC Biotechnology, Lille, France) is a safe synthetic and clinically acceptable immunomodulator that enhances the biologic activities of IFN-alpha in different experimental models. We evaluated in healthy human volunteers tolerance of the coadministration of Murabutide with increasing doses of IFN-alpha. The simultaneous administration of the two drugs was well tolerated without any increased or prohibiting toxicity, and all recipients experienced side effects that were similar to those observed after the administration of IFN-alpha alone. We also profiled the serum levels of cytokines induced following coinjection of the two drugs. We mostly detected an induction of anti-inflammatory cytokines and of human immunodeficiency virus type 1 (HIV-1)-suppressive beta-chemokines, in the absence of release of key proinflammatory cytokines. Therefore, the simultaneous administration of Murabutide and IFN-alpha is well tolerated and does not lead to increased toxicity. In addition, the selectivity in the profile of cytokines and chemokines induced following the coadministration of Murabutide and IFN-alpha points to the potential use of this combination in the treatment of inflammatory diseases and chronic viral infections.