Progressive multifocal leukoencephalopathy revisited: Has the disease outgrown its name?

Interferon beta1-a and selective anti-5HT(2a) receptor antagonists inhibit infection of human glial cells by JC virus

JC virus (JCV) is the causative agent of progressive multifocal leukoenchaphalopathy (PML). The disease develops when JCV gains access to the central nervous system, infects and destroys oligodendrocytes. The disease is rapidly progressing, typically fatal and no effective therapies exist to treat or prevent PML. The recent occurrence of PML in multiple sclerosis patients being treated with Avonex (IFNbeta1-a) and Tysabri (Natalizumab) and the recent reports linking JCV infection to the 5HT(2a) serotonin receptor led us to evaluate the effects of IFNbeta1-a and a panel of 5HT(2a) receptor antagonists for their ability to modulate virus infection. IFNbeta1-a was found to be a potent inhibitor of both virus infection and viral early and late gene expression. In addition, several 5HT(2a) receptor antagonists inhibited initial infection of cells by JCV but were less effective at reducing viral loads in an already established infection.

Spinal cord lesions of progressive multifocal leukoencephalopathy in an acquired immunodeficiency syndrome patient

Progressive multifocal leukoencephalopathy (PML) is a deadly demyelinating disease of the central nervous system, which occurs in immunosuppressed individuals. This disease is caused by a reactivation of the polyomavirus JC (JCV). Clinical presentation can be variable from patient to patient as lesions can occur anywhere in the CNS white matter; however, they appear to spare the optic nerves and the spinal cord. The authors present a case of PML in the setting of acquired immunodeficiency syndrome (AIDS) who developed PML lesions in the spinal cord, discovered during the postmortem examination. This finding is significant because PML has recently been diagnosed in patients with multiple sclerosis (MS) treated with the novel immunomodulatory medication natalizumab. Indeed, spinal cord lesions are frequent in MS. Therefore clinicians should be aware that in addition to the brain, PML may also affect the spinal cord white matter.

HIV infection with immunodeficiency presenting with subacute cognitive decline: recent illustrative cases

We describe three recent patients in whom evaluation of subacute, progressive encephalopathy led to the initial diagnosis of human immunodeficiency virus infection. The clinical neurological picture of a predominance of abnormalities of mental function with few elementary neurological deficits, in conjunction with a paucity of systemic symptoms and lack of evidence for prior opportunistic infections preceding the encephalopathy are notable. The cognitive, behavioral, and neuropsychiatric disturbances are described in detail to illustrate the range of manifestations of disordered mental states associated with encephalopathy in individuals with HIV infection. The importance of a comprehensive and broad-minded work-up by brain magnetic resonance imaging, cerebrospinal fluid examination, and specific microbiological tests in delineating the potential multifactorial pathogenesis of the cerebral syndromes in relation to the HIV infection is emphasized. The gratifying long-term clinical improvements in parallel with resolution of neuroimaging and other laboratory abnormalities in response to antiretroviral drug treatment are reported.

Inflammatory progressive multifocal leukoencephalopathy in human immunodeficiency virus-negative patients

OBJECTIVE

Inflammatory progressive multifocal leukoencephalopathy (iPML) with enhancing magnetic resonance imaging (MRI) lesions and leukocyte infiltration occurs in human immunodeficiency virus (HIV)-infected individuals after highly active antiretroviral therapy (HAART) treatment. MRI diagnostic criteria for PML suggest that iPML does not occur in HIV-negative individuals.

METHODS

We studied pathologically proved PML (12 by biopsy, 9 with MRI, 32 at autopsy).

RESULTS

HIV-negative (2/5) and -positive (2/4) PML patients had enhancing MRI lesions, correlated with CD3(+) lymphocyte infiltration. Inflammatory infiltrates occurred in the majority of HIV-negative (7/8) and HIV-positive/HAART (17/20) cases (p > 0.2), but in only 2 of 16 HIV-positive/non-HAART cases (p < 0.001).

INTERPRETATION

iPML showed radiographic and pathological similarity in HIV-positive/HAART and HIV-negative patients. HIV-negative iPML necessitates further consideration of MRI criteria for PML.

Progressive multifocal leukoencephalopathy from JC virus in a patient with advanced mycosis fungoides

Progressive multifocal leukoencephalopathy is a central nervous system disease due to reactivation of the human polyoma JC virus in immunocompromised patients. Advanced mycosis fungoides patients are intrinsically immunosuppressed and susceptible to infections, but only rarely have been reported to develop progressive multifocal leukoencephalopathy. We report a case of progressive multifocal leukoencephalopathy developing in an advanced mycosis fungoides patient without prior history of immunosuppressive therapy.

Longitudinal study of two cases of progressive multifocal leukoencephalopathy with a clinical benign evolution

Progressive multifocal leukoencephalopathy (PML) usually is a rapid and fatal demyelinating disease of the central nervous system (CNS), caused by JC virus (JCV). After the introduction of Highly active antiretroviral therapy (HAART), its prognosis has been modified in some cases but remains a relevant cause of morbidity in human immunodeficiency virus-seropositive (HIV+) patients. The authors report here two cases of PML, followed over time, sharing a benign course and a JCV antigen-specific T-cell response, but with different cerebrospinal fluid (CSF), magnetic resonance imaging (MRI), and clinical features. In both cases, JCV DNA detection in brain biopsies samples and specific antigenic response preceded its isolation in the CSF by several months. In one patient, during the first stage of the disease, the presence of CSF and MRI inflammatory findings, associated with the lack of JCV detection in the CSF, made the diagnosis more challenging. Given that to date a reformation of the laboratory parameters for PML diagnosis is strongly needed, this report highlights the following considerations: (a) indications for performing brain biopsy in HIV-related leukoencephalopathies of uncertain origin, and (b) the role of JCV immunologically specific T-cell response as an additional marker for PML diagnosis and indicator for good prognosis of the disease.

Chimeric immune receptors (CIRs) specific to JC virus for immunotherapy in progressive multifocal leukoencephalopathy (PML)

Progressive multifocal leukoencephalopathy (PML) is a deadly brain disease caused by the polyomavirus JC (JCV). The aim of this study is to develop 'designer T cells' armed with anti-JCV TCR-based chimeric immune receptors (CIRs) by gene modification for PML immunotherapy. Two T cell lines specific to two dominant CTL epitopes derived from JCV VP1 protein (termed p36 and p100) from an HLA-A0201+ PML survivor were generated for TCR cloning. Two distinct dominant TCR alpha chains (Valpha6 and Valpha12) and a unique TCR beta chain (Vbeta5.1) were cloned from the p36-specific cell line, while only one alpha (Valpha8.6) and one beta (Vbeta2) chains were dominant in the p100-specific line. Retroviral constructs encoding CIRs were created with the extracellular domains of TCR alpha and beta chains fused to the transmembrane and cytoplasmic portions of CD3zeta (ValphaCalphaCD3zeta or VbetaCbetaCD3zeta). Cellular expression and screening for binding specific peptide-HLA-A0201 tetramer confirmed the reactivity of the p100 TCRalphabeta and of one of the two pairs of p36 TCRalphabeta (Valpha12 and Vbeta5.1). Functional tests confirmed CIR-expressing T cells secreted cytokines and expressed potent cytotoxicity on contact with A0201+ B-lymphoblastoid line loaded with peptides and/or with HLA-A0201+ cells expressing native JCV VP1 protein. In conclusion, anti-JCV designer T cells were generated.

Remission of progressive multifocal leukoencephalopathy and primary central nervous system lymphoma in an HIV-infected patient

The coexistence of progressive multifocal leukoencephalopathy (PML) and primary central nervous system lymphoma (PCNSL) is a rare event, usually associated with a fatal outcome. We report the case of a human immunodeficiency virus (HIV)-infected individual presenting with both PML and PCNSL who made a remarkable recovery after highly active anti retroviral therapy (HAART) and radiation therapy, and discuss diagnostic and therapeutic aspects of both conditions.

Natalizumab (Tysabri) Treatment for Relapsing Multiple Sclerosis

BACKGROUND

Natalizumab (Tysabri), a humanized monoclonal antibody which binds to the alpha4beta1 integrins of leukocytes, blocks attachment to cerebral endothelial cells, thus reducing inflammation at the blood-brain barrier. Two pivotal randomized trials, 1 comparing active treatment to placebo and 1 comparing active treatment to placebo in relapsing multiple sclerosis (MS) patients receiving intramuscular interferon beta1alpha (Avonex), demonstrated significant efficacy for relapse control, decrease in sustained disability, and reduced numbers of new lesions on MRI.

REVIEW SUMMARY

Because of safety issues raised by the appearance of 2 cases of progressive multifocal leukoencephalopathy in MS patients exposed to natalizumab for relapsing MS treatment has been restricted. This review briefly outlines the inflammatory nature of MS plagues, the mechanism of action of natalizumab and the pathogenesis of progressive multifocal leukoencephalopathy. The mandatory guidelines for natalizumab use in the treatment of MS with natalizumab are explained. Special concerns facing the therapist electing to prescribe natalizumab are mentioned.

CONCLUSION

Natalizumab recently joined glatiramer acetate and beta interferon as an approved therapy for controlling relapsing MS. Unresolved safety issues currently restrict its use to monotherapy in patients who have had inadequate response to the other immunomodulating agents.

Treatment and treatment trials in multiple sclerosis

PURPOSE OF REVIEW

This review focuses on advances in current and novel treatment approaches in multiple sclerosis.

RECENT FINDINGS

New therapeutic approaches in multiple sclerosis are emerging. Orally available treatment strategies are more acceptable for patients and may improve adherence to therapy. An oral formulation of glatiramer acetate failed to demonstrate efficacy in a clinical trial, but other promising compounds are on the horizon, such as FTY720. Advances are currently being made in use of therapeutic monoclonal antibodies that specifically target key molecules involved in the immunopathogenesis of multiple sclerosis. Natalizumab directed against the adhesion molecule very late antigen-4 represents the first specific antibody to be added to our therapeutic armamentarium for multiple sclerosis. Further evidence that immunomodulation should be initiated as early as possible has been reported.

SUMMARY

Treatment of multiple sclerosis has changed dramatically over the past decade. Enhanced understanding of the immunopathological processes that underlie the disease, advances in biotechnology and development of powerful magnetic resonance imaging technologies, together with improvements in clinical trial design have led to a variety of valuable therapeutic approaches, which are currently being studied in detail.

Expert opinion: guidelines for the use of natalizumab in multiple sclerosis patients previously treated with immunomodulating therapies

Natalizumab (Tysabri) (anti-VLA4) is a novel agent for treatment of relapsing multiple sclerosis (MS) [Polman C.H., O'Connor P.W., Havrdova E. et al., 2006. A randomized, placebo-controlled trial of natalizumab for relapsing multiple sclerosis. N. Engl. J. Med. 354, 899-910.]. Controlled trials have shown considerable efficacy in preventing relapses, in excess of that seen for other EMEA-approved disease modulating drugs. While well-tolerated and generally safe, three cases of progressive multifocal leukoencephalopathy (PML) occurred in the context of 3 clinical trials encompassing some 3300 patients using this drug in multiple sclerosis and Crohn's disease. Immune compromised patients, such as those receiving immunosuppressive medications, are at a higher risk of developing PML. Natalizumab was recently approved for the treatment of relapsing forms of MS. This includes patients who had an inadequate response to other therapies and some of these patients will have already received immunosuppressants. These agents have the potential to cause prolonged effects on the immune system, even after dosing has been discontinued. Determining that these patients are not immunocompromised will be an important safety issue to consider prior to the initiation of natalizumab therapy. This short report summarizes interdisciplinary practical recommendations from specialists in neuroimmunology, rheumatology, transplantation medicine and clinical immunology.

Update on therapeutic monoclonal antibodies

Monoclonal antibodies are among the most important class of drugs introduced into the therapeutic armamentarium since the introduction of antimicrobials in the 1930s. The first therapeutic monoclonal antibody, the anti T-cell monoclonal antibody OKT4, was licensed in 1986. Since then, 18 additional antibodies have been licensed in the US, with many more in the pipeline. Before 1986, many monoclonal antibodies were available for laboratory studies, notably to identify specific cells in the blood and tissues. This is best illustrated by the cluster designation (CD) system for antigens present on hematopoietic cells, now numbering over 200.

Frequency and phenotype of JC virus-specific CD8+ T lymphocytes in the peripheral blood of patients with progressive multifocal leukoencephalopathy

JC virus (JCV)-specific CD8+ cytotoxic T lymphocytes (CTL) are associated with a favorable outcome in patients with progressive multifocal leukoencephalopathy (PML) and cross-recognize the polyomavirus BK virus (BKV). We sought to determine the frequency and phenotype in fresh blood of CD8+ T cells specific for two A*0201-restricted JCV epitopes, VP1(p36) and VP1(p100), and assess their impact on JC and BK viremia and viruria in 15 healthy subjects, eight human immunodeficiency virus-positive (HIV+) individuals, and nine HIV+ patients with PML (HIV+ PML patients) classified as survivors. After magnetic pre-enrichment of CD8+ T cells, epitope-specific cells ranged from 0.001% to 0.022% [corrected] by tetramer staining, with no significant difference among the three study groups. By use of seven-color flow cytometry, there was no predominant differentiation phenotype subset among JCV-specific CD8+ T cells in healthy individuals, HIV+ subjects, or HIV+ PML patients. However, in one HIV+ PML patient studied in the acute phase, there was a majority of activated effector memory cells. BKV DNA was undetectable in all blood samples by quantitative PCR, while a low JC viral load was found in the blood of only one HIV+ and two HIV+ PML patients. JCV and BKV DNA were detected in 33.3% and 13.3% of all urine samples, respectively, independent of the presence of JCV-specific CTL. The detection of JCV DNA in the urine was associated with the presence of a JCV VP1(p100) CTL response. Immunotherapies aiming at increasing the cellular immune response against JCV may be valuable in the treatment of HIV+ individuals with PML.

The cellular response in neuroinflammation: The role of leukocytes, microglia and astrocytes in neuronal death and survival

Neuroinflammation is a complex integration of the responses of all cells present within the CNS, including the neurons, macroglia, microglia and the infiltrating leukocytes. The initiating insult, environmental factors, genetic background and age/past experiences all combine to modulate the integrated response of this complex neuroinflammatory circuit. Here, we explore how these factors interact to lead to either neuroprotective versus neurotoxic inflammatory responses. We specifically focus on microglia and astrocytic regulation of autoreactive T cell responses.