Highly active antiretroviral therapy and progressive multifocal leukoencephalopathy: effects on cerebrospinal fluid markers of JC virus replication and immune response

Challenges for clinical trials to treat progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy is a lethal complication of immunodeficiency for which no direct therapy has been achieved. The issues that have made this disease especially difficult to address are discussed, and an outline for development of future interventions is provided. A controlled trial of therapy utilizing an international group of trial groups is proposed.

Critical role of JC virus-specific CD4 T-cell responses in preventing progressive multifocal leukoencephalopathy

BACKGROUND

JC virus (JCV) is ubiquitous among the general population. However, only individuals with severely impaired immunity, mainly AIDS patients, develop progressive multifocal leukoencephalopathy (PML). Here, we examined the role of specific CD4 T cells in the control of JCV infection.

METHODS AND DESIGN

JCV-specific CD4 T-cell responses were investigated by assaying peripheral blood mononuclear cell proliferation in response to the purified virus. Four groups of individuals without PML were examined: 14 HIV-seronegative healthy donors and 25 HIV-infected patients without PML, separated into urinary JCV excretors (active infection) and non-excretors, according to JCV PCR on urine. Two groups of patients with PML were also studied: 14 HIV-infected patients with active PML; and 10 PML survivors on effective and prolonged antiretroviral therapy. All of the patients were PCR-positive for JCV in the cerebrospinal fluid at the time of diagnosis of PML.

RESULTS

No significant anti-JCV CD4 T-cell proliferation was found in any of the non-excretors tested. All nine healthy donors and seven of the 13 non-PML HIV-infected patients with urinary JCV excretion had positive JCV-specific CD4 T-cell responses. No significant response was found in the 14 patients with active PML, while nine of the 10 PML survivors had positive responses. Restoration of JCV-specific CD4 T-cell responses was associated with JCV clearance from the cerebrospinal fluid.

CONCLUSION

JCV-specific CD4 T-cell responses appear to play a critical role in the control of JCV infection, preventing PML development. Such responses can be restored in PML survivors following effective and prolonged antiretroviral therapy.

Clinical course and prognostic factors of progressive multifocal leukoencephalopathy in patients treated with highly active antiretroviral therapy

We analyzed survival rates, neurologic function, and prognostic factors for 118 consecutive patients with acquired immunodeficiency syndrome-associated progressive multifocal leukoencephalopathy (PML) treated with highly active antiretroviral therapy (HAART) in 11 hospitals throughout Spain. Seventy-five patients (63.6%) remained alive for a median of 114 weeks (2.2 years) after diagnosis of PML. Neurologic function of the survivors was categorized as cure or improvement in 33, stabilization or worsening in 40, and unknown in 2. The baseline CD4+ cell count was the only variable found with prognostic significance. The odds ratio of death was 2.71 (95% confidence interval, 1.19-6.15) for patients with CD4+ cell counts of <100 cells/microL, compared with patients who had CD4+ cell counts of > or =100 cells/microL. One-third of patients with PML died despite receipt of HAART; neurologic function improved in approximately one-half of the survivors. A CD4+ cell count of <100 cells/microL was associated with higher mortality.

Comparison of cell culture-grown JC virus (primary human fetal glial cells and the JCI cell line) and recombinant JCV VP1 as antigen for the detection of anti-JCV antibody by haemagglutination inhibition

JC virus (JCV) is the causative agent of the demyelinating disease progressive multifocal leucoencephalopathy (PML), which can be diagnosed by detection in the cerebrospinal fluid (CSF) of both JCV DNA and intrathecally-produced anti-JCV antibody. However, the restricted in-vitro species and cell tropism shown by JCV has made antigen production difficult and limited serological investigations both in PML diagnosis and for JCV epidemiology. In this study antigen prepared as a crude cell lysate of JCV-infected primary human fetal glial (PHFG) cells was compared in a haemagglutination inhibition (HI) assay with antigen produced from the JCV carrier cell line, JCI, and yeast-expressed JCV VP1. Forty-two sera were tested with each antigen and there was a high level of correlation between the assays: 96.5% between the HI assays with PHFG and JCI antigens and 98.1% between the HI assays with PHFG and recombinant VP1 (rVP1) antigens. The JCI antigen gave HI titres 19% lower than the PHFG antigen (P=0.022). Titres with the rVP1 antigen were 2% higher than with the PHFG antigen (P=0.83). When serum/CSF pairs from 11 PML patients were tested, the antibody index calculated in each case confirmed the production of intrathecal anti-JCV antibody. Antibody testing for JCV is no longer reliant on PHFG cells and JCV serological tests should be available more widely.

Molecular analysis of cerebrospinal fluid in viral diseases of the central nervous system

The use of nucleic acid (NA) amplification techniques has transformed the diagnosis of viral infections of the central nervous system (CNS). Because of their enhanced sensitivity, these methods enable detection of even low amounts of viral genomes in cerebrospinal fluid. Following more than 10 years of experience, the polymerase chain reaction or other NA-based amplification techniques are nowadays performed in most diagnostic laboratories and have become the test of choice for the diagnosis of several viral CNS infections, such as herpes encephalitis, enterovirus meningitis and other viral infections occurring in human immunodeficiency virus-infected persons. Furthermore, they have been useful to establish a viral etiology in neurological syndromes of dubious origin and to recognise unusual or poorly characterised CNS diseases. Quantitative methods have provided a valuable additional tool for clinical management of these diseases, whereas post-amplification techniques have enabled precise genome characterisation. Current efforts are aiming at further improvement of the diagnostic efficiency of molecular techniques, their speed and standardisation, and to reduce the costs. The most relevant NA amplification strategies and clinical applications of to date will be the object of this review.

Fatal immune restoration disease in human immunodeficiency virus type 1-infected patients with progressive multifocal leukoencephalopathy: impact of antiretroviral therapy-associated immune reconstitution

Immune reconstitution resulting from use of highly active antiretroviral therapy in patients infected with human immunodeficiency virus type 1 (HIV-1) has been associated with a significant decrease in infectious morbidity and with improved survival. Occasionally, patients with quiescent disease due to human cytomegalovirus or nontuberculous mycobacteria may experience paradoxical worsening due to "dysregulated" restitution of the immune system (that is, immune restoration disease [IRD]). Acquired immunodeficiency syndrome-related progressive multifocal leukoencephalopathy (PML) is uncommon and often improves with immune recovery. We describe 2 HIV-1-infected patients with PML that presented with paradoxical worsening after the patients had commenced active antiretroviral therapy. After they had a transient response to high-dose corticosteroid therapy, both patients died of progressive neurological deterioration. IRD in these patients with PML was unexpected and occurred soon after they had started receiving active antiretroviral therapy, during the period of improved antigen-specific T-helper cell function. Predictors of patients' proclivity for these adverse events are uncertain. Evaluation of targeted immunomodulatory therapy directed towards disease-specific IRD is critical and may play an important role in improved survival for patients who are at risk.

A pilot study of cidofovir for progressive multifocal leukoencephalopathy in AIDS

OBJECTIVE

To assess the safety, tolerability and effect of cidofovir for HIV-1 associated progressive multifocal leukoencephalopathy.

DESIGN

Prospective, open-label study in nine AIDS Clinical Trials Units.

PATIENTS AND METHODS

Twenty-four HIV-1-infected individuals, with neuroimaging and clinical findings consistent with PML, and symptoms for 90 days or less, whose diagnosis was confirmed by the detection of JC virus DNA in the cerebrospinal fluid or brain biopsy, received cidofovir 5 mg/kg intravenously at baseline and 1 week, followed by infusions every 2 weeks with the dose adjusted for renal function. Follow-up continued to 24 weeks. The safety of cidofovir and changes in neurological examination scores between baseline and week 8 were assessed.

RESULTS

Seventeen subjects were receiving potent antiretroviral agents. Survival at 12 weeks was 54%. The CD4 cell count at entry was significantly associated with survival (P = 0.02). Five subjects discontinued treatment because of toxicity: a 50% or greater decrease in intraocular pressure in either eye in four, and proteinuria in one. Overall, magnetic resonance imaging abnormalities and neurological examination scores worsened. Only two subjects experienced a 25% or greater improvement in neurological examination scores at week 8, which were significantly better in subjects with HIV-1-RNA levels of 500 copies/ml or less at entry compared with those with HIV-1-RNA levels over 500 copies/ml (P = 0.05).

CONCLUSION

Cidofovir did not improve neurological examination scores at week 8. However, such scores were significantly better in subjects who entered with suppressed plasma HIV-1-RNA levels, which could be the result of control of HIV-1 infection itself or cidofovir.

JC virus load in progressive multifocal leukoencephalopathy: analysis of the correlation between the viral burden in cerebrospinal fluid, patient survival, and the volume of neurological lesions

JC virus (JCV) is the causative agent of progressive multifocal leukoencephalopathy (PML), a demyelinating central nervous system infection that mainly affects patients with acquired immunodeficiency syndrome. The diagnostic value of the detection of JCV DNA in cerebrospinal fluid (CSF) has been proved. A correlation between the JCV burden in CSF and the PML prognosis has been proposed. To our knowledge, the present study is the first to examine JCV burden in CSF in relation to the magnitude of neurological damage. An in-house quantitative polymerase chain reaction assay was used for measurement of the JCV burden in CSF samples from 12 patients with PML. A wide variation in JCV load (6.4 log) was found among the patient CSF samples, a finding that makes JCV load measurements worthwhile. Virus load values of >4.68 log were associated with shorter patient survival time. No correlation was found between the virus load values and the global volume of brain tissue damaged. Our data suggest that factors other than the volume of neurological lesions influence the shedding of JCV in the CSF.

Focal neurological disease in patients with acquired immunodeficiency syndrome

Focal neurological disease in patients with acquired immunodeficiency syndrome may be caused by various opportunistic pathogens and malignancies, including Toxoplasma gondii, progressive multifocal leukoencephalopathy (PML), cytomegalovirus (CMV), and Epstein-Barr virus-related primary central nervous system (CNS) lymphoma. Diagnosis may be difficult, because the findings of lumbar puncture, computed tomography (CT), and magnetic resonance imaging are relatively nonspecific. Newer techniques have led to improved diagnostic accuracy of these conditions. Polymerase chain reaction (PCR) of cerebrospinal fluid specimens is useful for diagnosis of PML, CNS lymphoma, and CMV encephalitis. Recent studies have indicated the diagnostic utility of new neuroimaging techniques, such as single-photon emission CT and positron emission tomography. The combination of PCR and neuroimaging techniques may obviate the need for brain biopsy in selected cases. However, stereotactic brain biopsy, which is associated with relatively low morbidity rates, remains the reference standard for diagnosis. Highly active antiretroviral therapy has improved the prognosis of several focal CNS processes, most notably toxoplasmosis, PML, and CMV encephalitis.

Progressive Multifocal Leukoencephalopathy

Progressive multifocal leukoencephalopathy is a subacute demyelinating disease that occurs in patients with defects in cell-mediated immunity, including those with AIDS and lymphoproliferative disorders. It is caused by reactivation of JC virus (JCV), which infects 70% to 90% of the population by adulthood, but remains latent in normal hosts. Once reactivated, JCV infects oligodendrocytes and astrocytes, with resultant cell lysis, leading to focal areas of demyelination and necrosis in cerebral white matter causing focal neurologic deficits and characteristic findings on MRI. Polymerase chain reaction for the detection of JCV is a sensitive and specific test, replacing brain biopsy as the initial diagnostic test in the appropriate clinical setting. Historically, the prognosis of progressive multifocal leukoencephalopathy is poor, with most patients dying within 6 months of diagnosis. Antiviral medications targeted against JCV have shown little success. However, with the use of highly active antiretroviral therapy, survival of AIDS patients with progressive multifocal leukoencephalopathy has improved.

Cidofovir in AIDS-associated progressive multifocal leukoencephalopathy: a monocenter observational study with clinical and JC virus load monitoring

A monocenter observational study was conducted to determine the clinical and virological effects of cidofovir added to highly active anti-retroviral therapy (HAART) in AIDS-associated progressive multifocal leukoencephalopathy (PML). Exposure to other anti-viral drugs or late initiation of cidofovir were exclusion criteria. Of the 53 consecutive patients with virologically proven PML admitted at the NeuroAIDS Unit of Bicêtre Hospital between May 1996 and July 2000 and having received HAART with or without cidofovir, 46 met the inclusion criteria. Cidofovir was initiated in most cases on compassionate grounds. The 22 patients treated with HAART only (HAART group) were compared to the 24 patients treated with HAART and cidofovir (CDV group). Survival, neurological outcome assessed by the expanded disability status scale (EDSS), and monitoring of the JC virus (JCV) load in CSF were investigated prospectively. At baseline (date of initiation or intensification of HAART), both groups were similar regarding CD4 cell count, plasma HIV load, CSF JCV load, EDSS, and demographic features. Both groups had similar response to HAART in terms of plasma HIV load and CD4 cell count. At month 6, CSF-JCV load was below the detection level in 8 out of 24 (33%) patients from the CDV group and 7 out of 18 (39%) patients from the HAART group (P = 0.71). One-year cumulative probability of being alive was 62% in the CDV group and 53% in the HAART group (P = 0.72). However, an additional benefit with respect to survival was observed in patients who were given cidofovir after adjustment to the following baseline variables (CSF-JCV load, CD4 cell count, and EDSS). Despite the addition of cidofovir to HAART, no significant benefit had been observed in neurological outcome, particularly in patients with an early worsening.

Epidemiology and prognosis of AIDS-associated progressive multifocal leukoencephalopathy in the HAART era

Whereas most AIDS-related neurologic disorders have reduced incidence since HAART therapy was introduced, we find that the incidence of progressive multifocal leukoencephalopathy (PML) did not significantly differ between the pre-HAART and the HAART period (OR 0.78; 95% CI 0.41-1.50). These findings were confirmed by the preliminary results of the Italian Register Investigative Neuro AIDS (IRINA) Study, a prospective multicenter study started in January 2000, which showed that PML was the second most frequently diagnosed neurologic disorder after TE. A similar proportion of cases were found in HAART-naïve and HAART-experienced patients in our experience. PML was more common in the presence of HIV RNA > 500 copies/ml. Most of the cases occurring in HAART-exposed patients developed within the first 6 months of therapy. As others have reported, we find a prolonged survival in PML subjects prescribed HAART (245 days in the group treated with HAART versus 66 days in the group not treated with HAART; P at log rank = 0.001). However despite the survival benefit, AIDS-associated PML still has a serious prognosis. In fact, PML had the lowest 1-year survival probability of any cerebral disorder in our study (P = 0.0005). Our findings also confirm that CSF JCV DNA burden at baseline is a useful prognostic indicator with a threshold of 4.7 log(10) JCV copies/ml (P at log rank = 0.01) in our experience. CSF JCV DNA load at 4 weeks of follow-up and clearance of JCV-DNA from CSF are associated with a better neurologic outcome and a longer survival.

JC virus-specific cytotoxic T lymphocytes in individuals with progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system caused by a reactivation of the polyomavirus JC (JCV) within a setting of immunosuppression. The nature of the immune response that contains replication of this virus is unknown. We have explored JCV-specific cellular immune responses in patients with PML and control subjects. JCV antigen-stimulated peripheral blood mononuclear cells (PBMC) of four human immunodeficiency virus (HIV)-infected patients who were survivors of PML and one HIV-uninfected patient recently diagnosed with PML lysed autologous B-lymphoblastoid cell lines expressing either the JCV T regulatory protein or the VP1 major capsid protein. This lysis was mediated by CD8(+) T lymphocytes and was major histocompatibility complex class I restricted. These cells were therefore cytotoxic T lymphocytes (CTL). JCV-specific CTL could not be detected in PBMC of three HIV-infected PML patients who had progressive neurologic disease and an eventual fatal outcome. These data suggest that the JCV-specific cellular immune response may play a crucial role in the containment of PML. This finding may also prove useful as a favorable prognostic marker in the clinical management of these patients.