Effect of etanercept (Enbrel) on interleukin 6, tumor necrosis factor alpha, and markers of immune activation in HIV-infected subjects receiving interleukin 2

HIV-associated psoriasis: Epidemiology, pathogenesis, and management

People living with HIV (PLWH) are affected by a higher incidence skin disorders, which are often associated with high morbidity and mortality. In particular, psoriasis affects PLWH severely and for a longer time than the general population. Human immunodeficiency virus (HIV) infection is characterized by a progressive decrease in CD4⁺ T-cell count, and it could seem paradoxical that psoriasis exacerbations are more frequent in this subset of patients than the general population, even though it is commonly observed at any stage of infection. For a long time, there have been limited therapeutic choices for PLWH affected by psoriasis. The introduction of the combined antiretroviral therapy dramatically changed the natural course of both HIV and psoriasis in PLWH, leading to an improvement of quality and duration of life. However, the clinical severity of psoriasis in PLWH often requires the use of immunosuppressant drugs. Knowledge about their safety and efficacy are limited to case-reports, small case-series and studies, therefore their use has not yet entered the routine. Further studies are needed to determine if immunosuppressive drugs can be safely and effectively used in PLWH affected by psoriasis and other autoimmune disorders.

Rates of Serious Infections in HIV-Infected Patients Receiving Tumor Necrosis Factor Inhibitor Therapy for Concomitant Autoimmune Diseases

OBJECTIVE

To estimate the incidence of serious infections in patients with HIV infection and autoimmune disease who were treated with tumor necrosis factor (TNF) inhibitors, and to compare these rates by stratified viral load levels.

METHODS

Using a unified search strategy, 4 centers identified HIV-infected patients exposed to TNF inhibitors. Patient characteristics and infection data were assessed via chart review in all patients who were ≥18 years old and who received TNF inhibitor therapy after HIV diagnosis, between January 1999 and March 2015.

RESULTS

We studied 23 patients with 26 uses of TNF inhibitor therapy (86.7 person-years of followup). Two (8.7%) experienced at least 1 serious infection episode, for an overall incidence rate of 2.55 per 100 patient-years (95% confidence interval [95% CI] 0.28-9.23). The incidence rate per 100 patient-years was 3.28 (95% CI 0.04-18.26) among patients with a viral load >500 copies/ml at therapy initiation and 2.09 (0.03-11.65) among patients with a viral load ≤500 copies/ml.

CONCLUSION

This study suggests that the rate of serious infections in patients with HIV infection under active care who have received treatment with TNF inhibitors may be comparable to the rates observed in registry databases.

Targeting TNF and TNF Receptor Pathway in HIV-1 Infection: from Immune Activation to Viral Reservoirs

Several cellular functions such as apoptosis, cellular proliferation, inflammation, and immune regulation involve the tumor necrosis factor-α (TNF)/TNF receptor (TNFR) pathway. Human immunodeficiency virus 1 (HIV-1) interacts with the TNF/TNFR pathway. The activation of the TNF/TNFR pathway impacts HIV-1 replication, and the TNF/TNFR pathway is the target of HIV-1 proteins. A hallmark of HIV-1 infection is immune activation and inflammation with increased levels of TNF in the plasma and the tissues. Therefore, the control of the TNF/TNFR pathway by new therapeutic approaches could participate in the control of immune activation and impact both viral replication and viral persistence. In this review, we will describe the intricate interplay between HIV-1 proteins and TNF/TNFR signaling and how TNF/TNFR activation modulates HIV-1 replication and discuss new therapeutic approaches, especially anti-TNF therapy, that could control this pathway and ultimately favor the clearance of infected cells to cure HIV-infected patients.

Use of etanercept to treat rheumatoid arthritis in an HIV-positive patient: a case-based review

Rheumatoid arthritis (RA) is a relatively common autoimmune disease that is associated with progressive disability and systemic complications, with a relatively high socioeconomic burden. The treatment of RA has been revolutionized by the use of biological drugs, such as anti-tumor necrosis factor (TNF) agents. A wide spectrum of RA disease severity has been reported among patients with human immunodeficiency virus (HIV) infection. Yet, only a few cases using anti-TNF therapy have been described in this clinical population. Therefore, the aim of our case-based review was to describe the successful use of etanercept in a 38-year-old female patient with RA concomitant with HIV infection, who had been resistant to the first-line anti-rheumatic therapies. As per routine care guidelines, the patient was screened for hepatitis virus infection, latent tuberculosis, and other infectious conditions, prior to the initiation of etanercept treatment. CD4 cell count, HIV viral load, and adverse effects were closely monitored during the treatment. The HIV infection remained stable with etanercept treatment, without the need for anti-retrovirus agents. No adverse effects and serious infections were identified during the treatment. Therefore, anti-TNF therapy is a viable alternative for the treatment of RA in patients with HIV, who do not respond to conventional anti-rheumatic therapies. The relationship between TNF-α and HIV infection, as well as cautionary guidelines regarding the utilization of anti-TNF therapy in this clinical population, is discussed.

Systematic review of the efficacy and safety of biological therapy for inflammatory conditions in HIV-infected individuals

Biologic therapies are injectable immunomodulatory agents directed against specific immune cell or chemical targets. They have transformed the lives of HIV-uninfected individuals with severe inflammatory conditions including psoriasis, rheumatoid arthritis, and ulcerative colitis. The perceived increased infection risk associated with these agents means that HIV-infected individuals have not been included in randomised control trials of these drugs. The literature for use of biologic therapies in HIV-infected populations is limited to case reports and case series. There are additional data on use of rituximab, a monoclonal antibody against B lymphocytes, in the setting of HIV-associated haematological malignancy. We performed a systematic review of efficacy and safety of biologic therapy for inflammatory conditions in HIV-infected individuals. Our systematic review identified 37 treatment episodes with six different biologic agents encompassing 10 different inflammatory conditions. Broadly, efficacy of the agents studied was comparable to reports from HIV-uninfected patients. Both infectious and non-infectious sequelae were also comparable with trial data from HIV-uninfected patients. HIV control, even for the minority of individuals not receiving anti-retroviral therapy (ART) at the time of biologic therapy, was not adversely affected. However, detail was limited concerning ART regimens and both immunological and virological parameters of follow-up. Overall available literature is of very low quality and likely subject to publication bias of successful cases. Firm conclusions are not possible regarding the efficacy and safety of biologic agents in HIV-infected individuals; however, there appear to be sufficient data to warrant inclusion of individuals with well-controlled HIV in future trial studies.

Use of tumor necrosis factor (TNF) inhibitors in patients with HIV/AIDS

Patients with HIV and AIDS are living longer because of advancements in antiretroviral therapy. These patients are often susceptible to debilitating inflammatory disorders that are refractory to standard treatment. We discuss the relationship of tumor necrosis factor-alpha and HIV and then review 27 published cases of patients with HIV being treated with tumor necrosis factor-alpha inhibitors. This review is limited because no randomized controlled trials have been performed with this patient population. Regardless, we propose that reliable seropositive patients, who are adherent to medication regimens and frequent monitoring and have failed other treatment modalities, should be considered for treatment with tumor necrosis factor-alpha inhibitors.

Treatment of severe non-infectious uveitis in high-risk conditions (Part 2): systemic infections; management and safety issues

INTRODUCTION

Management of patients with severe immune-mediated uveitis requires the use of immunosuppressive (IS) drugs in selected cases. This may be particularly challenging in certain patients with associated conditions, which may increase the risk of side effects or modify guidelines for the use of such drugs. Chronic viral and mycobacterial infections in the setting of non-infectious uveitis create a number of diagnostic but also therapeutic dilemmas to clinicians because they can be exacerbated by IS therapies with detrimental effects.

AREAS COVERED

In this review, we will focus on very specific chronic infections that can be affected by IS therapies: human immunodeficiency virus infection, chronic hepatitis virus infection and tuberculosis. The main aim of this review is to provide an updated and comprehensive practical guide for practitioners regarding the therapeutic decision-making and management of patients with non-infectious uveitis affected by the aforementioned infectious conditions.

EXPERT OPINION

Clinicians should be aware of the risk of viral and mycobacterial reactivation of an underlying infection during IS therapy. However, most of these conditions do not represent an absolute contraindication if one were able to apply an appropriate prior screening and close monitoring of such therapy.

Novel investigational drugs targeting IL-6 signaling for the treatment of depression

INTRODUCTION

Elevated levels of IL-6 have been implicated in the pathophysiology and treatment of major depressive disorder (MDD). Convergent evidence suggests that IL-6 primarily mediates proinflammatory functions via the soluble IL-6 receptor/trans-signaling, and anti-inflammatory functions via a transmembrane receptor (IL-6R). A targeted approach to selectively inhibit IL-6 trans-signaling may offer putative antidepressant effects.

AREAS COVERED

This review addresses three primary domains. The first focuses on the biological role of IL-6 within inflammation and its signal transduction pathways. The second addresses the potential contributions of IL-6 to the pathophysiology of MDD, and the mechanisms that may mediate these effects. Finally, the article outlines the therapeutic benefits of incorporating anti-inflammatory properties into the pharmacological treatment of MDD, and proposes inhibition of IL-6 signaling as a viable treatment strategy.

EXPERT OPINION

To improve drug development for the treatment of MDD, there is a critical need to identify promising targets. Target identification will require guidance from a strategic framework such as The Research Domain Criteria, and convincing evidence relating known targets to brain function under both physiological and pathological conditions. Although current evidence provides rationale for administering anti-IL-6 treatments in MDD, further studies confirming safety, target affinity and therapeutic benefits are warranted.

Cytokine therapies in HIV-1 infection: present and future

Since the introduction of highly active antiretroviral therapy (HAART), HIV-related deaths have declined dramatically in the developed world. However, HAART is neither able to eradicate the virus nor are its immunomodulatory effects sufficient to effect complete control of the virus. In addition, the long-term use of HAART is complicated by drug-related toxicities and compliance issues, both of which impact upon the development of viral resistance. The failure of structured treatment interruption strategies in those with chronic HIV-infection combined with the above limitations, has prompted renewed interest in immunotherapy. Cytokines and therapeutic vaccination have been proposed as HAART-adjunctive and HAART-sparing treatments in HIV-infection, and the current and future role of cytokine therapy in this disease will be the subject of this review.

TNF and TNF receptor superfamily members in HIV infection: new cellular targets for therapy?

Tumor necrosis factor (TNF) and TNF receptors (TNFR) superfamily members are engaged in diverse cellular phenomena such as cellular proliferation, morphogenesis, apoptosis, inflammation, and immune regulation. Their role in regulating viral infections has been well documented. Viruses have evolved with numerous strategies to interfere with TNF-mediated signaling indicating the importance of TNF and TNFR superfamily in viral pathogenesis. Recent research reports suggest that TNF and TNFRs play an important role in the pathogenesis of HIV. TNFR signaling modulates HIV replication and HIV proteins interfere with TNF/TNFR pathways. Since immune activation and inflammation are the hallmark of HIV infection, the use of TNF inhibitors can have significant impact on HIV disease progression. In this review, we will describe how HIV infection is modulated by signaling mediated through members of TNF and TNFR superfamily and in turn how these latter could be targeted by HIV proteins. Finally, we will discuss the emerging therapeutics options based on modulation of TNF activity that could ultimately lead to the cure of HIV-infected patients.

Clinical use of anti-TNF therapy and increased risk of infections

Biologics such as antitumor necrosis factor (anti-TNF) drugs have emerged as important agents in the treatment of many chronic inflammatory diseases, especially in cases refractory to conventional treatment modalities. However, opportunistic infections have become a major safety concern in patients on anti-TNF therapy, and physicians who utilize these agents must understand the increased risks of infection. A literature review of the published data on the risk of bacterial, viral, fungal, and parasitic infections associated with anti-TNF therapy was performed and the clinical presentation, diagnostic tests, management, and prevention of opportunistic infections in patients receiving anti-TNF therapy were reviewed. Awareness of the therapeutic potential and associated adverse events is necessary for maximizing therapeutic benefits while minimizing adverse effects from anti-TNF treatments. Patients should be adequately vaccinated when possible and closely monitored for early signs of infection. When serious infections occur, withdrawal of anti-TNF therapy may be necessary until the infection has been identified and properly treated.

Reduced inflammation and lymphoid tissue immunopathology in rhesus macaques receiving anti-tumor necrosis factor treatment during primary simian immunodeficiency virus infection

BACKGROUND

Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections induce robust, generalized inflammatory responses that begin during acute infection and lead to pathological systemic immune activation, fibrotic damage of lymphoid tissues, and CD4⁺ T-cell loss, pathogenic processes that contribute to disease progression.

METHODS

To better understand the contribution of tumor necrosis factor (TNF), a key regulator of acute inflammation, to lentiviral pathogenesis, rhesus macaques newly infected with SIVmac239 were treated for 12 weeks in a pilot study with adalimumab (Humira), a human anti-TNF monoclonal antibody.

RESULTS

Adalimumab did not affect plasma SIV RNA levels or measures of T-cell immune activation (CD38 or Ki67) in peripheral blood or lymph node T cells. However, compared with untreated rhesus macaques, adalimumab-treated rhesus macaques showed attenuated expression of proinflammatory genes, decreased infiltration of polymorphonuclear cells into the T-cell zone of lymphoid tissues, and weaker antiinflammatory regulatory responses to SIV infection (ie, fewer presumed alternatively activated [ie, CD163⁺] macrophages, interleukin 10-producing cells, and transforming growth factor β-producing cells), along with reduced lymphoid tissue fibrosis and better preservation of CD4⁺ T cells.

CONCLUSIONS

While HIV/SIV replication drives pathogenesis, these data emphasize the contribution of the inflammatory response to lentiviral infection to overall pathogenesis, and they suggest that early modulation of the inflammatory response may help attenuate disease progression.

Successful use of antitumor necrosis factor-alpha biological therapy in managing human immunodeficiency virus-associated arthritis: three case studies from Saudi Arabia

Arthralgic disorders involving various rheumatic manifestations are commonly observed in HIV patients. Available therapies for HIV-associated rheumatic syndromes include non-steroidal anti-inflammatory drugs for pain management, disease-modifying antirheumatic drugs (e.g., methotrexate), and antitumor necrosis factor-alpha therapies. However, treatment of HIV-associated arthritis can be challenging, particularly in patients with co-infections like hepatitis viruses, and therapeutic strategies are not well defined. Here, we present three case reports on the use of antitumor necrosis factor-alpha agents for HIV-associated arthritis. We managed three cases of HIV-associated arthritis following initial presentation. All patients were on highly active antiretroviral therapy with stable HIV loads and CD4(+) cell counts. Data were reported for treatment of inflammatory arthritis using 5 months of etanercept followed by adalimumab for case 1, and 12 months of etanercept for case 2. In case 3, reactive arthritis was treated with 5 months of etanercept followed by adalimumab. In all three cases, significant improvement or resolution of arthritis was achieved following treatment with antitumor necrosis factor-alpha therapies. Moreover, these case studies demonstrated the safe and effective use of antitumor necrosis factor-alpha agents in HIV patients with hepatitis B and/or C virus co-infection. Our results indicate that antitumor necrosis factor-alpha therapies can be successfully used for HIV-infected patients with stable HIV loads and CD4(+) lymphocyte counts.

Incidence and nature of infectious disease in patients treated with anti-TNF agents

Tumor necrosis factor alpha (TNF-alpha) inhibitors offer a targeted therapeutic strategy that contrasts with the nonspecific immunosuppressive agents traditionally used to treat most inflammatory diseases. These biologic agents have had a significant impact in ameliorating the signs and symptoms of inflammatory rheumatoid disease and improving patient function. From the onset of clinical trials, a central concern of cytokine blockade has been a potential increase in susceptibility to infections. Not surprisingly, a variety of infections have been reported in association with the use of TNF-alpha inhibitor agents. In particular, there is evidence suggesting an increased rate of granulomatous infections in patients treated with monoclonal TNF-alpha inhibitors. This review provides the incidence and nature of infections in patients treated with TNF-alpha inhibitor agents and reminds the clinician of the required vigilance in monitoring patients.

The implications of anti-tumour necrosis factor therapy for viral infection in patients with inflammatory bowel disease

INTRODUCTION

Anti-tumour necrosis factor (TNF) therapy is increasingly used in the management of inflammatory bowel disease; however, concerns have been raised regarding risk of infection with such drugs. Little is known about their effect upon viral infection.

SOURCES OF DATA

A search of PubMed using the terms 'infliximab', 'etanercept', 'adalimumab' or 'anti-TNF therapy' combined with the names of specific viruses was performed. A search of cited papers was used to identify further relevant reports.

AREAS OF AGREEMENT

Numerous reports of the use of anti-TNF in patients with chronic or latent viral infection appear in the literature. Specific problems related to hepatitis B virus and varicella zoster virus may exist. The safety profile of anti-TNF in chronic viral infection is generally reassuring.

AREAS OF CONTROVERSY

Numerous consensus statements relating to pre-treatment serology or vaccination have recently appeared; however, significant variation exists in their recommendations.

GROWING POINTS

Increasing awareness of the implications of anti-TNF therapy on viral infection may allow safer use of such drugs.

AREAS TIMELY FOR DEVELOPING RESEARCH

The clinical and cost-effectiveness of screening for viral infections prior to anti-TNF requires further study.

Problems encountered during anti-tumour necrosis factor therapy

Worldwide, over 400,000 patients have been treated with tumour necrosis factor (TNF)-alpha antagonists for indications that include rheumatoid arthritis, juvenile rheumatoid arthritis, inflammatory bowel disease, psoriatic arthritis and ankylosing spondylitis. Since their approval, concerns regarding safety have been raised. There is a risk of re-activation of granulomatous diseases, especially tuberculosis, and measures should be taken for detection and treatment of latent tuberculosis infections. Preliminary data suggest that anti-TNF therapy may be safe in chronic hepatitis C. However, TNF-alpha antagonists have resulted in re-activation of chronic hepatitis B if not given concurrently with antiviral therapy. Solid tumours do not appear to be increased with anti-TNF therapy. Variable rates of increased lymphoma risk have been described with anti-TNF therapy compared with the general population, although no increased risk was found compared with a rheumatoid arthritis population. Large phase II and III trials with TNF-alpha antagonists in advanced heart failure have shown trends towards a worse prognosis, and should therefore be avoided in this population. Both etanercept and infliximab are associated with the formation of autoantibodies, and these autoantibodies are rarely associated with any specific clinical syndrome. Rare cases of aplastic anaemia, pancytopenia, vasculitis and demyelination have been described with anti-TNF therapy. This chapter will discuss the safety profile and adverse events of the three commercially available TNF-alpha antagonists: etanercept, infliximab and adalimumab. The data presented in this review have been collected from published data, individual case reports or series, package inserts, the Food and Drug Administration postmarketing adverse events surveillance system, and abstracts from the American College of Rheumatology and European Congress of Rheumatology meetings for 2005.

Improvement in immune parameters and human immunodeficiency virus-1 viral response in individuals treated with 16alpha-bromoepiandrosterone (HE2000)

A randomised, double-blind, placebo-controlled study examined the safety, tolerance, immunological effect and anti-human immunodeficiency virus (HIV) activity of sub-cutaneously administered HE2000 (16alpha-bromoepiandrosterone) as monotherapy in treatment-naïve patients with HIV-1. Twenty-four patients received five sequential daily doses of 50 or 100 mg of HE2000 or placebo every 6 weeks for up to three courses, and were followed thereafter for 3 months. HE2000 was safe, with transient injection site reactions being the main side-effect. Peripheral blood samples, collected serially, were analysed for changes in immune cell phenotypes. Significant increases were observed in the numbers of circulating dendritic cells, early activated (CD69+ CD25-) CD8 T-cells and T-NK cells after administration of 50-mg doses of HE2000 (p < 0.05). Gene expression in peripheral blood mononuclear cells was analysed by real-time RT-PCR. Before treatment, HIV-1-infected patients had significantly elevated transcripts for a number of inflammatory mediators (p < 0.012). After 50 mg or 100 mg HE2000, but not after placebo, there were significant sustained decreases in IL-1beta, TNF-alpha, IL-6 and Cox-2 transcripts (p < 0.05). There were no significant differences in CD4 cell numbers, although patients receiving 50-mg doses demonstrated a significant decrease in viral load (- 0.6 log; p < 0.01). Anti-HIV-1 T-cell responses were analysed serially using GAG-peptides to stimulate cytoplasmic IFN-gamma responses. After three courses, the 50-mg dose group demonstrated a significant increase in CD8 T-cell response against two distinct GAG peptide pools (p < 0.03). These findings suggest that immune-based therapies may be able to impact viral load by decreasing inflammation and/or stimulating CD8 T-cells.

Impact of Biologic Agents on Infectious Diseases

Until recently, inflammatory diseases, collagen vascular diseases, inflammatory bowel diseases, and multiple sclerosis were met with a limited offering for treatment. The introduction of biologic agents has revolutionized the approach to these diseases, offering many patients freedom from disease activity staving off resultant destruction to organs and joints with marked improvement in quality of life and disability. This article focuses on the development of serious infections associated with the use of biologic agents. Presented is a synthesis of case series, reports, and systematic reviews to elucidate implicated pathogens and clinical presentations in patients being treated with biologic agents and to form a cursory backbone for prevention and treatment strategies to which clinicians prescribing these agents or encountering patients already on these agents can readily refer. Maintenance of a high index of suspicion is imperative for the prevention and appropriate treatment of serious life-threatening infections in these patients.

Use of etanercept in human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) patients

BACKGROUND

Etanercept (Enbrel, Amgen, Thousand Oaks, CA), a soluble p75 tumor necrosis factor receptor:FC (TNFR:FC) fusion protein for plasma cytokines, specifically tumor necrosis factor-alpha (TNF-alpha), is used in the treatment of immune-mediated rheumatic diseases. To our knowledge, the use of etanercept in patients with human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) is relatively uncommon.

OBJECTIVE

The main purpose of this short review is to examine the safety of etanercept in patients with HIV/AIDS.

METHODS

A Medline search was conducted using the keywords etanercept and HIV and/or AIDS for any published articles between 1966 to the present (September 2004).

RESULTS

A case report, one case series, and one clinical trial pertained to the use of etanercept in HIV patients. No reports were found on the use of etanercept in AIDS. In addition, two case reports were found documenting the use of infliximab in HIV patients.

DISCUSSION

Preliminary reports indicate that the administration of etanercept does not appear to increase the morbidity or mortality rates in HIV. The inhibition of TNF-alpha may actually improve the symptoms of HIV/AIDS-associated aphthous ulcers, cachexia, dementia, fatigue, and fever, as well as help manage concomitant rheumatic diseases and psoriasis.

CONCLUSION

The use of etanercept shows promise for applications in disease management in patients with HIV/AIDS. Continued research efforts are necessary to establish the long-term safety and efficacy of etanercept and other biologic agents in this patient population.

LMP-420, a small-molecule inhibitor of TNF-alpha, reduces replication of HIV-1 and Mycobacterium tuberculosis in human cells

Background

Co-infections of human immunodeficiency virus (HIV) and Mycobacterium tuberculosis (M. Tb) are steadily increasing and represent a major health crisis in many developing countries. Both pathogens individually stimulate tumor necrosis factor-alpha (TNF) release from infected cells and TNF, in turn, enhances the replication of each. A recent report on a Phase I clinical trial suggested that etanercept (soluble TNF receptor) might be beneficial in treating HIV/M. Tb co-infected patients. We sought to determine if a small molecule inhibitor of TNF synthesis and activity could block replication of either organism and thus be a potential adjunct to existing drugs targeting these agents.

Results

LMP-420, a novel anti-inflammatory agent that inhibits TNF, was tested for HIV-1 inhibition both alone and in combination with AZT (3' -azido-3-deoxythymidine). LMP-420 alone was tested against M. Tb. HIV-1 infected human peripheral blood mononuclear cells (PBMC) or M. Tb-infected human alveolar macrophages (AM) were treated with a single dose of LMP-420 and viral or bacterial replication determined after 7 or 5 days respectively. Viral replication was determined from supernatant p24 levels measured by ELISA. M. Tb replication was determined by bacterial culture of macrophage lysates. LMP-420 alone inhibited HIV replication over 7 days with an IC₅₀ of ~300 nM. Combination of LMP-420 with AZT doubled the level of HIV inhibition observed with AZT alone. LMP-420 alone inhibited the replication of virulent M. Tb by >80%, more than that observed with anti-TNF antibody alone.

Conclusion

Inhibition of TNF with inexpensive, small-molecule, orally-active drugs may represent a useful strategy for enhancing the activity of currently-available antiviral and anti-M. Tb agents, particularly in those areas where co-infections with these pathogens act to synergistically enhance each other.

Safety of antitumour necrosis factor (anti-TNF) therapy in patients with chronic viral infections: hepatitis C, hepatitis B, and HIV infection

Tumour necrosis factor alpha (TNFalpha) is a pivotal cytokine in host defences with broad ranging effects on the innate and adaptive immune systems. Clinically, TNFalpha inhibitors have demonstrated remarkable efficacy in a wide range of autoimmune and inflammatory disorders but clearly at the cost of heightened susceptibility to a variety of infections in those treated with these agents. Most reports to date have described increased susceptibility to intracellular pathogens in patients with underlying chronic viral infections, but little in the way of adverse event reporting in these patients has occurred. While the reported experience to date is rather limited, TNFalpha inhibitors have displayed a reasonable safety profile in the setting of some chronic viral infections and in certain circumstances have demonstrated adjunctive activity in the treatment of these infections. Given the high prevalence of chronic viral infections in patients who are candidates for anti-TNF therapy and the potential for these agents in the treatment of chronic viral illness, additional studies are urgently needed to assess the risks and benefits of such therapy in these populations.

T-cell and neuronal apoptosis in HIV infection: implications for therapeutic intervention

The pathogenesis of HIV infection involves the selective loss of CD4+ T cells contributing to immune deficiency. Although loss of T cells leading to immune dysfunction in HIV infection is mediated in part by viral infection, there is a much larger effect on noninfected T cells undergoing apoptosis in response to activation stimuli. In the subset of patients with HIV dementia complex, neuronal injury, loss, and apoptosis are observed. Viral proteins, gp120 and Tat, exhibit proapoptotic activities when applied to T cell and neuronal cultures by direct and indirect mechanisms. The pathways leading to cell death involve the activation of one or more death receptor pathways (i.e., TNF-alpha, Fas, and TRAIL receptors), chemokine receptor signaling, cytokine dysregulation, caspase activation, calcium mobilization, and loss of mitochondrial membrane potential. In this review, the mechanisms involved in T-cell and neuronal apoptosis, as well as antiapoptotic pathways potentially amenable to therapeutic application, are discussed.