Pathogenesis and molecular biology of progressive multifocal leukoencephalopathy, the JC virus-induced demyelinating disease of the human brain

Individuals infected with JC polyomavirus do not present detectable JC virus DNA in oropharyngeal fluids

JC virus (JCV) is ubiquitous in the human population. Primary infection normally occurs during childhood and is followed by a lifelong persistent infection. The main mode of transmission remains unknown. Several authors have hypothesized that JCV transmission occurs through the respiratory route, and that respiratory secretions could represent a possible source of viral particles. The present study intended to evaluate oropharyngeal fluids from patients infected with JCV, in order to ascertain if respiratory secretions could indeed constitute a source of exposure to this polyomavirus. Oropharyngeal washing samples from 25 patients co-infected with JCV and human immunodeficiency virus type 1 were evaluated for the presence of JCV DNA. Regardless of the titre of antibodies or the presence of viral urinary excretion, JCV genome was not detected in oropharyngeal samples collected from any of the patients infected with JCV included in this study, which may suggest that oropharyngeal fluids are an unlikely source for JCV infection.

Progressive multifocal leukoencephalopathy: a review of the neuroimaging features and differential diagnosis

Progressive multifocal leukoencephalopathy (PML) is an uncommon and often fatal demyelinating disease of human central nervous system, which is caused by reactivation of the polyomavirus JC (JCV). PML generally occurs in patients with profound immunosuppression such as AIDS patients. Recently, a number of PML cases have been associated with administration of natalizumab for treatment of multiple sclerosis (MS) patients. Diagnosis and management of PML became a major concern after its occurrence in multiple sclerosis patients treated with natalizumab. Diagnosis of PML usually rests on neuroimaging in the appropriate clinical context and is further confirmed by cerebrospinal fluid polymerase chain reaction (PCR) for JCV DNA. Treatment with antiretroviral therapies in HIV-seropositive patients or discontinuing natalizumab in MS patients with PML may lead to the development of immune reconstitution inflammatory syndrome (IRIS) which presents with deterioration of the previous symptoms and may lead to death. In patients under treatment with monoclonal antibodies in routine practice, or new ones in ongoing clinical trials, differentiating PML from new MS lesions on brain MRI is critical for both the neurologists and neuroradiologists. In this review, we discuss the clinical features, neuroimaging manifestations of PML, IRIS and neuroimaging clues to differentiate new MS lesions from PML. In addition, various neuroimaging features of PML on the non-conventional MR techniques such as diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI), and MR spectroscopy (MRS) are discussed.

Frequency and large T (LT) sequence of JC polyomavirus DNA in oligodendrocytes, astrocytes and granular cells in non-PML brain

Progressive multifocal leukoencephalopathy (PML) and JCV granular cell neuronopathy occur secondary to JCV polyomavirus (JCV) infection of oligodendrocytes and cerebellar granular cell neurons (CGNs) during immunosuppression. Pure populations of astrocytes, oligodendrocytes, CGNs and microglia from frontal cortex and cerebellum of 17 non-PML patients (9 immunocompetent; 8 immunosuppressed) were isolated by laser capture microdissection (LCM). JCV large T (LT) antigen DNA was detected by triple nested polymerase chain reaction (PCR). Sequence analysis was performed to assess LT gene variation. JCV DNA was detected in oligodendrocytes, astrocytes and CGNs of non-PML brains. The most common site for viral latency was cortical oligodendrocytes (65% of samples analyzed). Immunosuppressed patients were significantly more likely to harbor JCV DNA in CGN populations than immunocompetent patients (P = 0.01). Sequence analysis of the LT region revealed eight novel single nucleotide polymorphisms (SNPs) in four immunosuppressed patients. Of the eight novel SNPs detected, six were silent and two resulted in amino acid changes. JCV DNA is present within cells of the non-PML brain, known to be infected during PML and granular cell neuronopathy. This supports the argument for a brain only reservoir of JCV and supports the hypothesis that reactivation of latent brain JCV may be central to disease pathogenesis.

Human polyomavirus JC small regulatory agnoprotein forms highly stable dimers and oligomers: implications for their roles in agnoprotein function

JC virus (JCV) encodes a small basic phosphoprotein from the late coding region called agnoprotein, which has been shown to play important regulatory roles in the viral replication cycle. In this study, we report that agnoprotein forms highly stable dimers and higher order oligomer complexes. This was confirmed by immunoblotting and mass spectrometry studies. These complexes are extremely resistant to strong denaturing agents, including urea and SDS. Central portion of the protein, amino acids spanning from 17 to 42 is important for dimer/oligomer formation. Removal of 17 to 42 aa region from the viral background severely affected the efficiency of the JCV replication. Extracts prepared from JCV-infected cells showed a double banding pattern for agnoprotein in vivo. Collectively, these findings suggest that agnoprotein forms functionally active homodimer/oligomer complexes and these may be important for its function during viral propagation and thus for the progression of PML.

Progressive multifocal leukoencephalopathy (PML) development is associated with mutations in JC virus capsid protein VP1 that change its receptor specificity

Progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease caused by JC virus (JCV) infection of oligodendrocytes, may develop in patients with immune disorders following reactivation of chronic benign infection. Mutations of JCV capsid viral protein 1 (VP1), the capsid protein involved in binding to sialic acid cell receptors, might favor PML onset. Cerebrospinal fluid sequences from 37/40 PML patients contained one of several JCV VP1 amino acid mutations, which were also present in paired plasma but not urine sequences despite the same viral genetic background. VP1-derived virus-like particles (VLPs) carrying these mutations lost hemagglutination ability, showed different ganglioside specificity, and abolished binding to different peripheral cell types compared with wild-type VLPs. However, mutants still bound brain-derived cells, and binding was not affected by sialic acid removal by neuraminidase. JCV VP1 substitutions are acquired intrapatient and might favor JCV brain invasion through abrogation of sialic acid binding with peripheral cells, while maintaining sialic acid-independent binding with brain cells.

Natalizumab for the treatment of relapsing multiple sclerosis

Natalizumab is an α4-integrin antagonist approved as monotherapy for patients with relapsing multiple sclerosis (MS), based on demonstrated efficacy in the pivotal AFFIRM study (N = 942). Natalizumab monotherapy reduced risk of disability progression by 42%–54% and annualized relapse rate by 68% during a period of 2 years. Natalizumab was also associated with significant reductions in number of T2-hyperintense, gadolinium-enhancing, and T1-hypointense lesions and in volume of T2-hyperintense lesions (all p < 0.001) on magnetic resonance imaging. Furthermore, natalizumab-treated patients in AFFIRM experienced significant improvements from baseline in the physical and mental components of the Short Form-36 (p ≤ 0.01) and a 35% reduction in risk of clinically significant vision loss (p = 0.008 vs placebo). Natalizumab was well tolerated in phase 3 studies. Common adverse events were generally mild and included headache, fatigue, urinary tract infections, and arthralgia. Serious adverse events were similar between treatment groups. The incidence of serious hypersensitivity reactions associated with natalizumab was <1%. Progressive multifocal leukoencephalopathy was a rare complication of treatment, observed in 2 patients with MS who received natalizumab plus interferon β-1a. The robust clinical benefits of natalizumab, including benefits on patient-reported quality of life, make it an important addition to disease-modifying therapies available to patients with relapsing MS.

Progressive multifocal leukoencephalopathy in a patient with glioblastoma

Malignant gliomas are aggressive malignancies which inevitably recur despite multimodality treatment. In a subset of patients who are longer term survivors of this disease, progressive radiologic worsening can also occur from late effects of radiation rather than recurrent tumor, a differential diagnosis that is commonly considered in this setting. However, other causes for radiologic progression are not as well recognized and could potentially confound management leading to incorrect treatment decisions. Progressive multifocal leukoencephalopathy (PML) is a rare infectious demyelinating disease of the central nervous system seen primarily in immunocompromised patients, the early diagnosis and treatment of which remains a challenge. Here, we report a case of a long term survivor with glioblastoma whose diagnostic and therapeutic management was confounded by the development of PML. We review the radiological features and clinical course of this patient to highlight the dramatic neurological course in the setting of a highly malignant tumor, and emphasize the unusual changes in diffusion weighted images, and the need for clinical suspicion for early diagnosis of PML.

Infection by agnoprotein-negative mutants of polyomavirus JC and SV40 results in the release of virions that are mostly deficient in DNA content

BACKGROUND

Human polyomavirus JC (JCV) is the etiologic agent of a brain disease, known as progressive multifocal leukoencephalopathy (PML). The JCV genome encodes a small multifunctional phospho-protein, agnoprotein, from the late coding region of the virus, whose regulatory functions in viral replication cycle remain elusive. In this work, the functional role of JCV and SV40 agnoproteins in virion release was investigated using a point mutant (Pt) of each virus, where the ATG codon of agnoprotein was mutated to abrogate its expression.

RESULTS

Analysis of both viral protein expression and replication using Pt mutant of each virus revealed that both processes were substantially down-regulated in the absence of agnoprotein compared to wild-type (WT) virus. Complementation studies in cells, which are constitutively expressing JCV agnoprotein and transfected with the JCV Pt mutant genome, showed an elevation in the level of viral DNA replication near to that observed for WT. Constitutive expression of large T antigen was found to be not sufficient to compensate the loss of agnoprotein for efficient replication of neither JCV nor SV40 in vivo. Examination of the viral release process for both JCV and SV40 Pt mutants showed that viral particles are efficiently released from the infected cells in the absence of agnoprotein but were found to be mostly deficient in viral DNA content.

CONCLUSIONS

The results of this study provide evidence that agnoprotein plays an important role in the polyomavirus JC and SV40 life cycle. Infection by agnoprotein-negative mutants of both viruses results in the release of virions that are mostly deficient in DNA content.

Progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a disease of the central nervous system (CNS) with destructive infection of oligodendrocytes by JC virus. PML belongs to the opportunistic infections. It is observed in patients with HIV infection, lymphoid malignancies, after organ- and stem cell transplantations and more recently in the context of modern immune-therapies with monoclonal antibodies (mAb) like natalizumab, rituximab, infliximab and efalizumab. The natural course of PML is fatal within months. More recently, the Immune Reconstitution Inflammatory Syndrome (IRIS) has been observed in patients with HIV infection treated with combination antiretroviral therapy (cART) as well as patients in whom the PML-inducing immune therapy has been terminated. In PML-IRIS the immune system contributes to the elimination of JC virus from the CNS and if PML-IRIS emerges, PML can be survived but can lead as well to catastrophic outcomes with brain herniation and death. Therefore the management of IRIS requires special knowledge in JC virus biology and patient care. JC virus infection is possibly involved in a variety of additional neurological conditions and cancer. Much will be learned within the next years that could change our view on the understanding of JC virus and human disease.

Rituximab-associated progressive multifocal leukoencephalopathy in rheumatoid arthritis

OBJECTIVE

To describe the development of progressive multifocal leukoencephalopathy (PML) in patients with rheumatoid arthritis (RA) treated with rituximab.

DESIGN

Case study.

SETTING

Clinical care for patients with rheumatologic diseases. Most were referred to academic centers for care after diagnosis (Washington University, St Louis, Missouri; Karolinska Insitute, Stockholm, Sweden; and Royal Melbourne Hospital, Melbourne, Australia) while one was cared for in a neurology practice in Dallas, Texas, with consultation by an academic neurovirologist from the University of Colorado in Denver.

PATIENTS

Four patients developing PML in the setting of rituximab therapy for RA.

INTERVENTION

Rituximab therapy.

MAIN OUTCOME MEASURES

Clinical and pathological observations.

RESULTS

Four patients from an estimated population of 129 000 exposed to rituximab therapy for RA are reported in whom PML developed after administration of this drug. All were women older than 50 years, commonly with Sjögren syndrome and a history of treatment for joint disease ranging from 3 to 14 years. One case had no prior biologic and minimal immunosuppressive therapy. Progressive multifocal leukoencephalopathy presented as a progressive neurological disorder, with diagnosis confirmed by detection of JC virus DNA in the cerebrospinal fluid or brain biopsy specimen. Two patients died in less than 1 year from PML diagnosis, while 2 remain alive after treatment withdrawal. Magnetic resonance scans and tissue evaluation confirmed the frequent development of inflammatory PML during the course of the disease.

CONCLUSION

These cases suggest an increased risk, about 1 case per 25 000 individuals, of PML in patients with RA being treated with rituximab. Inflammatory PML may occur in this setting even while CD20 counts remain low.

Pathogenesis of progressive multifocal leukoencephalopathy--revisited

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system that is rare even though the proven etiological agent of PML, the polyomavirus JC (JC virus), is ubiquitous within the human population. The common feature of PML cases appears to be underlying immunosuppression, and PML has gained clinical visibility because of its association with human immunodeficiency virus and AIDS and its occurrence as a side effect of certain immunomodulatory drugs. A hypothesis has gained general acceptance that JC virus causes a primary infection in childhood and enters a latent state, after which immunosuppression allows viral reactivation leading to PML. Nonetheless, many important aspects of PML pathogenesis remain unclear, including the molecular bases of latency and reactivation, the site(s) of latency, the relationship of archetype and prototype virus and the mode of virus transmission within the body and between individuals. In this review, we will revisit these areas and examine what the available evidence suggests.

Efficient propagation of progressive multifocal leukoencephalopathy-type JC virus in COS-7-derived cell lines stably expressing Tat protein of human immunodeficiency virus type 1

The high incidence of progressive multifocal leukoencephalopathy (PML) in AIDS patients compared with many other immunosuppressive diseases suggests that HIV-1 infection is strictly related to the activation of JC virus (JCV) propagation. In this report, propagation of PML-type JCV in COS-7-derived cell lines stably expressing HIV-1 Tat (COS-tat cells) has been examined. In COS-tat cells, production of viral particles and replication of genomic DNA were markedly increased compared to COS-7 cells, as judged by HA and real-time PCR analyses. These results demonstrate that COS-tat cells provide a useful model system for studying HIV-1 Tat-mediated propagation of PML-type JCV.

Polyomavirus JC-targeted T-cell therapy for progressive multiple leukoencephalopathy in a hematopoietic cell transplantation recipient

Progressive multifocal leukoencephalopathy (PML) associated with polyomavirus JC (JCV) infection has been reported to be usually fatal in allogeneic hematopoietic SCT (HSCT) recipients. We present the case of a 19-year-old HSCT patient diagnosed with JCV-associated PML after prolonged immunosuppression for severe GVHD. No short-term neurological improvement was observed after antiviral treatment and discontinuation of immunosuppressive therapy. Donor-derived JCV Ag-specific CTLs were generated in vitro after stimulation with 15-mer peptides derived from VP1 and large T viral proteins. After adoptive CTL infusion, virus-specific cytotoxic cells were shown in the peripheral blood, JCV-DNA was cleared in the cerebrospinal fluid and the patient showed remarkable improvement. Adoptive T-lymphocyte therapy with JCV-specific CTLs was feasible and had no side effects. This case suggests that adoptive transfer of JCV-targeted CTLs may contribute to restore JCV-specific immune competence and control PML in transplanted patients.

JCV/BKV and SV40 viral load in lymphoid tissues of young immunocompetent children from an area of north-east Italy

Polyomavirus infection occurring during childhood is followed by a lifelong latency in immunocompetent subjects. The major site of polyomavirus persistence are the uroepithelial cells which leads to oral transmission. It has recently been hypothesized that tonsils could be a possible reservoir. The role of tonsil, adenoid, and peripheral blood mononuclear cells (PBMCs) as possible sites of JCV, BKV, and SV40 latency in young healthy children was assessed. Two hundred fifteen fresh specimens, including 57 tonsil, 80 adenoid, and 78 PBMC samples from 80 immunocompetent children (mean age 4.8 years) were analyzed to determine the viral load by quantitative real-time PCR. The human herpes virus 6 (HHV-6) was tested as a lymphotropic reference virus. Polyomavirus was detected in 5/80 (6.2%) children while HHV-6 infection affected 27/80 children (33.7%) (P < 0.001). SV40 was detected in one adenoid sample, while footprints of BKV were found in one adenoid and three tonsil samples. JCV was never found in all samples. Polyomavirus sequences were not detected in the 78 blood samples. One adenoid and two tonsils from three children (1.4%) were positive for both polyomavirus and HHV-6. Infections were characterized by low replication rates ranging typically from 1 x 10e(2)/5.5 x 10e(4) to 6.8 x 10e(3)/8.5 x 10e(4) viral copies/number of cells. In conclusion, tonsils and adenoids of children could effectively harbor BKV and SV40, although only very few cells proved to be infected. Nevertheless, the low prevalence of polyomavirus, in comparison with the lymphotropic HHV-6, suggests that these tissues are unlikely to be the preferred site of polyomavirus latency, at least in younger children.

Natalizumab and progressive multifocal leukoencephalopathy: what are the causal factors and can it be avoided?

Natalizumab (Tysabri) was the first monoclonal antibody approved for the treatment of relapsing forms of multiple sclerosis (MS). After its initial approval, 3 patients undergoing natalizumab therapy in combination with other immunoregulatory and immunosuppressive agents were diagnosed with progressive multifocal leukoencephalopathy (PML). The agent was later reapproved and its use restricted to monotherapy in patients with relapsing forms of MS. Since reapproval in 2006, additional cases of PML were reported in patients with MS receiving natalizumab monotherapy. Thus, there is currently no convincing evidence that natalizumab-associated PML is restricted to combination therapy with other disease-modifying or immunosuppressive agents. In addition, recent data indicate that risk of PML might increase beyond 24 months of treatment.

Demyelination as a complication of new immunomodulatory treatments

PURPOSE OF REVIEW

This review discusses demyelinating events of the nervous system that have been associated with new immunomodulatory treatments, in particular monoclonal antibodies (mAbs).

RECENT FINDINGS

Natalizumab, a mAb targeting the alpha-4 integrins, which is efficient in relapsing-remitting multiple sclerosis, has been associated with progressive multifocal leukoencephalopathy (PML). We will review the putative mechanisms linking natalizumab with JC virus, the agent of PML. Efalizumab, a mAb targeting a member of the integrin family, CD11a, was approved for the treatment of psoriasis, but had to be withdrawn in 2009 because of the occurrence of three cases of PML. Rituximab, an anti-CD20 mAb, is used in different neoplastic and autoimmune diseases and may soon enter the pharmacopeia of multiple sclerosis. It has been suggested that rituximab is a risk factor for PML; however, evidence of such a link is unclear. Antitumor necrosis factor-alpha agents are used in several autoimmune diseases. Several cases of demyelinating events of the nervous system have been reported, prompting a heightened surveillance of treated patients. Recent data are reassuring, suggesting that the incidence of such events is relatively low.

SUMMARY

Neurologists must become familiar with neurological complications of new immunomodulatory treatments, a field situated at the interface of neurology, immunology and infection.

Patients with sporadic colorectal cancer or advanced adenomatous polyp have elevated anti-JC virus antibody titer in comparison with healthy controls: a cross-sectional study

OBJECTIVE

JC virus (JCV) is thought to infect approximately 80% of the human population. Antibodies against JCV can be found in the sera of many people with and without colorectal carcinoma (CRC). We hypothesized that JCV antibody titer will be higher in CRC patients than in healthy controls.

AIM

To evaluate this hypothesis in a cohort of patients undergoing colonoscopy. We compared JCV antibody titers in patients with simple adenoma, advanced adenomatous polyp (AAP), CRC, and healthy controls, and evaluated JCV DNA in the tissue.

METHODS

Ninety-seven patients undergoing colonoscopy offered to participate in the study. Normal colonoscopy, simple adenoma, AAP, and CRC were found in 41, 19, 12, and 25 cases, respectively. A blood sample was taken for JCV DNA isolation and serology. In 18 patients with CRC or AAP tissue samples were taken for JCV DNA isolation and T-antigen (T-Ag) detection.

RESULTS

A positive correlation was found between a JCV antibody titer and advanced colonic pathology. The average titer for normal controls, simple polyp, AAP, and CRC was 2.61+/-0.72, 2.95+/-0.77, 3.33+/-0.76, and 3.30+/-0.50 log, respectively (P<0.001). Viral DNA could not be shown in the serum. The presence of neoplastic tissue T-Ag (in 33.3% of the patients) was not associated with a difference in the log titer of serum antibody.

CONCLUSIONS

In this study we showed that patients with advanced neoplasia, compared with patients with normal colonoscopy, harbor a higher JCV antibody titer in the serum. If confirmed, our finding may serve as a marker for CRC or for an earlier stage of AAP.

Role of N-linked glycosylation of the 5-HT2A receptor in JC virus infection

JC virus (JCV) is a human polyomavirus and the causative agent of the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML). JCV infection of host cells is dependent on interactions with cell surface asparagine (N)-linked sialic acids and the serotonin 5-hydroxytryptamine(2A) receptor (5-HT(2A)R). The 5-HT(2A)R contains five potential N-linked glycosylation sites on the extracellular N terminus. Glycosylation of other serotonin receptors is essential for expression, ligand binding, and receptor function. Also, glycosylation of cellular receptors has been reported to be important for JCV infection. Therefore, we hypothesized that the 5-HT(2A)R N-linked glycosylation sites are required for JCV infection. Treatment of 5-HT(2A)R-expressing cells with tunicamycin, an inhibitor of N-linked glycosylation, reduced JCV infection. Individual mutation of each of the five N-linked glycosylation sites did not affect the capacity of 5-HT(2A)R to support JCV infection and did not alter the cell surface expression of the receptor. However, mutation of all five N-linked glycosylation sites simultaneously reduced the capacity of 5-HT(2A)R to support infection and altered the cell surface expression. Similarly, tunicamycin treatment reduced the cell surface expression of 5-HT(2A)R. Mutation of all five N-linked glycosylation sites or tunicamycin treatment of cells expressing wild-type 5-HT(2A)R resulted in an altered electrophoretic mobility profile of the receptor. Treatment of cells with PNGase F, to remove N-linked oligosaccharides from the cell surface, did not affect JCV infection in 5-HT(2A)R-expressing cells. These data affirm the importance of 5-HT(2A)R as a JCV receptor and demonstrate that the sialic acid component of the receptor is not directly linked to 5-HT(2A)R.

Human polyomavirus JC (JCV) infection of human B lymphocytes: a possible mechanism for JCV transmigration across the blood-brain barrier

It has been suggested that JC virus (JCV) might travel to the central nervous system in infected B cells. Moreover, recent data suggest the presence of JCV in bone marrow plasma cells. However, the evidence for infection and replication of JCV in B cells is unclear. To address this question, we infected Epstein-Barr virus-transformed B cells with JCV and found that the viral genome decreased >1000-fold from days 0 to 20 after infection, which concurred with the absence of viral early and late messenger RNA transcripts and proteins. However, immunofluorescent images of B cells infected with fluorescein isothiocyanate-conjugated JCV demonstrated that JCV enters the B cells, and DNase protection assay confirmed the presence of intact JCV virions inside the B cells. Moreover, JCV-infected B cells were able to transmit infection to naive glial cells. These data confirm that JCV nonproductively infects B cells and possibly uses them as a vehicle for transmigration across the blood-brain barrier.

A mechanism of virus-induced demyelination

Myelin forms an insulating sheath surrounding axons in the central and peripheral nervous systems and is essential for rapid propagation of neuronal action potentials. Demyelination is an acquired disorder in which normally formed myelin degenerates, exposing axons to the extracellular environment. The result is dysfunction of normal neuron-to-neuron communication and in many cases, varying degrees of axonal degeneration. Numerous central nervous system demyelinating disorders exist, including multiple sclerosis. Although demyelination is the major manifestation of most of the demyelinating diseases, recent studies have clearly documented concomitant axonal loss to varying degrees resulting in long-term disability. Axonal injury may occur secondary to myelin damage (outside-in model) or myelin damage may occur secondary to axonal injury (inside-out model). Viral induced demyelination models, has provided unique imminent into the cellular mechanisms of myelin destruction. They illustrate mechanisms of viral persistence, including latent infections, virus reactivation and viral-induced tissue damage. These studies have also provided excellent paradigms to study the interactions between the immune system and the central nervous system (CNS). In this review we will discuss potential cellular and molecular mechanism of central nervous system axonal loss and demyelination in a viral induced mouse model of multiple sclerosis.

High expression of MeCP2 in JC virus-infected cells of progressive multifocal leukoencephalopathy brains

Mutations of the methyl CpG binding protein 2 (MeCP2) gene are a major cause of Rett syndrome. To investigate whether the expression of this gene was related to JC virus (JCV) infection, we examined brains of four progressive multifocal leukoencephalopathy (PML) patients. JCV infection was confirmed by immunohistochemical labeling with antibodies against JCV VP1, agnoprotein and large T antigen. MeCP2 expression was examined by immunohistochemistry using a specific polyclonal antibody against MeCP2. In normal brains and uninfected cortices of PML brains, MeCP2 expression was observed in the nuclei of neurons, but not observed in glial and endothelial cell nuclei. However, in PML brains intense immunolabeling was observed in abnormally enlarged glial nuclei of JCV-infected cells. Double immunolabeling using antibodies against large T antigen (visualized as blue) and MeCP2 (visualised as red) revealed dark red JCV-infected nuclei, which confirmed that the JCV infected nuclei expressed MeCP2. We conclude that MeCP2 is highly expressed in the JCV-infected nuclei of PML brain and these results may provide a new insight into the mechanism which regulates the MeCP2 expression in glial cells by the infection of JCV.

JC virus-induced Progressive Multifocal Leukoencephalopathy

Progressive multifocal encephalopathy (PML) is a fatal demyelinating disease of the central nervous system (CNS), caused by the lytic infection of oligodendrocytes by a human polyomavirus, JC virus (JCV). PML is rare disease but mostly develops in patients with underlying immunosuppressive conditions, including Hodgkin's lymphoma, lymphoproliferative diseases, in those undergoing antineoplastic therapy and AIDS. However, consistent with the occurrence of PML under immunocompromised conditions, this disease seems to be also steadily increasing among autoimmune disease patients (multiple sclerosis and Crohn's disease), who are treated with antibody-based regimens (natalizumab, efalizumab and rituximab). This unexpected occurrence of the disease among such a patient population reconfirms the existence of a strong link between the underlying immunosuppressive conditions and development of PML. These recent observations have generated a new interest among investigators to further examine the unique biology of JCV.

Characterization of JC human polyomavirus infection in a Portuguese population

JC virus (JCV) is ubiquitous in the human population, infecting children asymptomatically. After primary infection, JCV persists in the host throughout life and is often excreted in the urine. Two hundred thirty-four urine samples and 78 serum samples, collected from 171 healthy individuals and 63 patients infected with HIV, were used to characterize JCV infection in a Portuguese population. Using PCR, JCV DNA was detected in 38% of the urine samples. A significant difference in the excretion rate was observed between patients infected with HIV (51%) and healthy individuals (33%). The frequency of JCV viruria increased with age in healthy individuals, but not in patients infected with HIV. JCV urinary load was determined by real-time quantitative PCR and was independent of gender, age, HIV infection, and CD4+ cell count. Overall, the JCV genotype detected most commonly was 1B, followed by genotypes 2B and 4. The detection and quantitation of JCV-specific antibodies were performed in serum samples by an established enzyme immunoassay (EIA). Antibodies to JCV were observed in 91% of the patients tested, irrespective of HIV infection. A positive correlation between JCV urinary load and antibody titers was demonstrated. The present study provides the first characterization of seroprevalence and urinary excretion of JCV in a Portuguese population and revealed similar results to those observed in other European countries. A comparison between healthy individuals and patients infected with HIV, despite identical values of seroprevalence, showed some differences in the pattern of urinary excretion. J. Med. Virol. 82:494-504, 2010. (c) 2010 Wiley-Liss, Inc.

Bone marrow-derived mesenchymal stem cells undergo JCV T-antigen mediated transformation and generate tumors with neuroectodermal characteristics

There is now accumulating evidence showing that some tumors may arise from transformed stem cells. In this study we demonstrate that adult bone marrow- derived mesenchymal stem cells (MSCs) undergo neoplastic transformation induced by the human polyomavirus JCV, early protein, T-antigen, and are tumorigenic when transplanted into the flanks of Nude mice as compared to non-transformed MSCs. Histologically, the tumors are heterogeneous with mesenchymal and neural crest characteristics as evidenced by expression of the neural crest markers p75, SOX-10, and S-100, with populations of tumor cells exhibiting characteristics of primitive neuroectodermal cells. In addition, a subset of T-antigen positive tumor cells exhibit a high proliferation index as detected by Ki-67 labeling, and co-express CD133, a marker which is expressed on cancer stem cells. These results show that tumors with neuroectodermal characteristics may arise from transformation of MSCs, a globally accessible adult stem cell with multipotent differentiation capacity. In light of earlier reports on the association of JCV with a broad variety of human tumors, our data suggests that T-antigen transformation of adult stem cells with a multipotent capacity can serve as a possible common origin for some of these cancers, and offers a novel model for oncogenesis.

Immune responses to JC virus in patients with multiple sclerosis treated with natalizumab: a cross-sectional and longitudinal study

BACKGROUND

Natalizumab is used to prevent relapses and progression of disability in patients with multiple sclerosis but has been associated with progressive multifocal leukoencephalopathy (PML). We aimed to better understand the associations between JC virus, which causes PML, and natalizumab treatment.

METHODS

We prospectively assessed patients with multiple sclerosis who started treatment with natalizumab. Blood and urine samples were tested for the presence of JC virus DNA with quantitative real-time PCR before treatment and at regular intervals after treatment onset for up to 18 months. At the same timepoints, by use of proliferation and enzyme-linked immunospot assays, the cellular immune responses against JC virus, Epstein-Barr virus, cytomegalovirus, myelin oligodendrocyte glycoprotein, and myelin oligodendrocyte basic protein (MOBP) were assessed. Humoral immune response specific to JC virus was assessed with an enzyme immunoassay. The same experiments were done on blood samples from patients with multiple sclerosis before and 10 months after the start of interferon beta treatment.

FINDINGS

We assessed 24 patients with multiple sclerosis who received natalizumab and 16 who received interferon beta. In patients treated with natalizumab, JC virus DNA was not detected in the blood at any timepoint. However, JC virus DNA was present in the urine of six patients and in most of these patients the concentrations of JC virus DNA were stable over time. Compared with pretreatment values, the cellular immune response was increased to cytomegalovirus at 6 months, to JC virus at 1, 9, and 12 months, and to Epstein-Barr virus and MOBP at 12 months. Humoral responses remained stable. There were no increases in cellular immune responses specific to the viruses or myelin proteins in the 16 patients treated with interferon beta.

INTERPRETATION

Natalizumab increases cellular immune responses specific to viruses and myelin proteins in the peripheral blood after 1 year, without evidence of viral reactivation.

FUNDING

Swiss National Foundation, Swiss Society for Multiple Sclerosis, and Biogen Dompé.

Progressive multifocal leukoencephalopathy in myelodysplastic syndrome involving pure red cell aplasia

Progressive multifocal leukoencephalopathy (PML) is a rare and fatal demyelinating disease of the central nervous system caused by JC polyomavirus (JCV) reactivation in an immunocompromised host. We describe a case of PML in a 76-year-old woman with myelodysplastic syndrome, who had been treated with azathioprine for a pure red cell aplasia-like condition. PML was diagnosed based on the neurologic symptoms, the magnetic resonance imaging patterns and the detection of JCV DNA in the cerebrospinal fluid. She died ten months after the diagnosis. An autopsy confirmed the diagnosis, and JCV DNA was detected in the cerebrum. Azathioprine might have triggered PML.

Genetic and epigenetic characteristics of gastric cancers with JC virus T-antigen

AIM

To clarify the significance of JC virus (JCV) T-antigen (T-Ag) expression in human gastric cancer.

METHODS

We investigated the relationship between T-Ag detected by immunohistochemistry and Epstein-Barr virus (EBV) infection, microsatellite instability (MSI), and genetic and epigenetic alterations in gastric cancers. Mutations in the p53, beta-catenin, KRAS, BRAF, PIK3CA genes were analyzed by polymerase chain reaction (PCR)-single strand conformation polymorphism and DNA sequencing. Allelic losses were determined by PCR at 7 microsatellite loci. Aberrant DNA methylation was analyzed by MethyLight assay.

RESULTS

JCV T-Ag protein expression was found in 49% of 90 gastric cancer tissues. T-Ag positivity was not correlated with clinicopathological characteristics. T-Ag expression was detected in a similar percentage of EBV positive cancers (4 of 9, 44%) and EBV negative cancers (35 of 73, 48%). T-Ag expression was detected in a significantly lower percentage of MSI-H cancers (14%) than in non MSI-H cancers (55%, P = 0.005). T-Ag expression was detected in a significantly higher percentage of cancers with nuclear/cytoplasmic localization of beta-catenin (15 of 21, 71%) than in cancers without (42%, P = 0.018). p53 mutations were detected in a significantly lower percentage of T-Ag positive cancers (32%) than in T-Ag negative cancers (57%, P = 0.018). T-Ag positive gastric cancers showed a significant increase in the allelic losses and aberrant methylation compared with T-Ag negative gastric cancers (P = 0.008 and P = 0.003).

CONCLUSION

The results suggest that JCV T-Ag is involved in gastric carcinogenesis through multiple mechanisms of genetic and epigenetic alterations.

Archetype JC virus efficiently propagates in kidney-derived cells stably expressing HIV-1 Tat

Pathogenic JCV with rearranged regulatory regions (PML-type) causes PML, a demyelinating disease, in the brains of immunocompromised patients. On the other hand, archetype JCV persistently infecting the kidney is thought to be converted to PML-type virus during JCV replication in the infected host under immunosuppressed conditions. In addition, Tat protein, encoded by HIV-1, markedly enhances the expression of a reporter gene under control of the JCV late promoter. In order to examine the influence of Tat on JCV propagation, we used kidney-derived COS-7 cells, which only permit archetype JCV, and established COS-tat cells, which express HIV-1 Tat stably. We found that the extent of archetype JCV propagation in COS-tat cells is significantly greater than in COS-7 cells. On the other hand, COS-7 cells express SV40 T antigen, which is a strong stimulator of archetype JCV replication. The expression of SV40 T antigen was enhanced by HIV-1 Tat slightly according to real-time RT-PCR, this was not closely related to JCV replication in COS-tat cells. The efficiency of JCV propagation depended on the extent of expression of functional Tat. To our knowledge, this is the first report of increased production of archetype JCV in a culture system using cell lines stably expressing HIV-1 Tat. We propose here that COS-tat cells are a useful tool for studying the role of Tat in archetype JCV replication in the development of PML.

Monoclonal antibody-associated progressive multifocal leucoencephalopathy in patients treated with rituximab, natalizumab, and efalizumab: a Review from the Research on Adverse Drug Events and Reports (RADAR) Project

Progressive multifocal leucoencephalopathy (PML) is a serious and usually fatal CNS infection caused by JC polyoma virus. CD4+ and CD8+ T lymphopenia, resulting from HIV infection, chemotherapy, or immunosuppressive therapy, are the primary risk factors. The immune modulatory monoclonal antibodies rituximab, natalizumab, and efalizumab have received regulatory approval in the USA and Europe for treatment of non-Hodgkin lymphoma, rheumatoid arthritis, and chronic lymphocytic leukaemia (Europe only); multiple sclerosis and Crohn's disease; and psoriasis, respectively. Efalizumab and natalizumab administration is associated with CD4+ T lymphopenia and altered trafficking of T lymphocytes into the CNS, and rituximab leads to prolonged B-lymphocyte depletion. Unexpected cases of PML developing in people who receive these drugs have been reported, with many of the affected individuals dying from this disease. Herein, we review clinical findings, pathology, epidemiology, basic science, and risk-management issues associated with PML infection developing after treatment with these monoclonal antibodies.

The late adverse events of rituximab therapy--rare but there!

Rituximab, an anti CD20 monoclonal antibody, has now become a cornerstone in the treatment of many CD20 positive hematological malignancies and a variety of autoimmune disorders. In contrast to the acute allergic and cytokine associated reactions, late adverse events of rituximab are indeed uncommon but at the same time probably under-reported. In this review, we detail late adverse events reported since its use in hemato-oncological neoplasias and other disorders. These adverse events include the development of late-onset neutropenia, defects of immune reconstitution with associated immune compromise, infections, progressive multifocal leukoencephalopathy, reactivation of hepatitis, intestinal perforation and interstitial pneumonitis. Possible mechanisms involved in rituximab-associated complications and the pathogenesis of these adverse effects are reviewed and discussed. Evidence based graded recommendations for the management of these adverse effects are proposed.

Successful cidofovir therapy of progressive multifocal leukoencephalopathy preceding angioimmunoblastic T-cell lymphoma

Progressive multifocal leukoencephalopathy (PML) is a subacute demyelinating infectious disease, caused by the human polyomavirus JC (JCV), that usually occurs in immunocompromised patients. In this setting, PML has been observed in increasing numbers of patients with hematological malignancies, mostly lymphoproliferative B-cell disorders. Despite attempts with various drugs, PML has generally remained unresponsive to treatment. We report the successful use of cidofovir in a patient who developed PML 6 months before angioimmunoblastic T-cell lymphoma (AITL) was diagnosed. To the best of our knowledge, this is the first case of PML in AITL. Our case demonstrates the expanding clinical importance of PML in hematological conditions, and neurological symptoms and/or white matter changes on central nervous system imaging should arouse the suspicion of PML and lead to rapid cidofovir introduction. Progressive multifocal leukoencephalopathy (PML) is a subacute demyelinating infectious disease, caused by the human polyomavirus JC (JCV), that usually occurs in immunocompromised patients. In this setting, PML has been observed in increasing numbers of patients with hematological malignancies, mostly lymphoproliferative B-cell disorders. Despite attempts with various drugs, PML has generally remained unresponsive to treatment. We report the successful use of cidofovir in a patient who developed PML 6 months before angioimmunoblastic T-cell lymphoma (AITL) was diagnosed. To the best of our knowledge, this is the first case of PML in AITL. Our case demonstrates the expanding clinical importance of PML in hematological conditions, and neurological symptoms and/or white matter changes on central nervous system imaging should arouse the suspicion of PML and lead to rapid cidofovir introduction.

Progressive Multifocal Leukoencephalopathy Complicating Waldenström's Macroglobulinaemia

Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating neurological disorder caused by JC virus. Immunocompromised patients such as those with chronic lymphocytic leukemia, AIDS and following organ transplantation are at increased risk. We report a patient with PML complicating longstanding Waldenström's macroglobulinaemia. Although PML is a rare occurrence, the newer highly immunosuppressive treatment approaches for patients with lymphoproliferative disorders necessitate a high index of clinical suspicion. The diagnosis should be considered in patients with compatible clinical features who have received long-term immunosuppressive treatments recognized to impair cellular immunity.

Modulation of PML protein expression regulates JCV infection

JC virus (JCV) is a human polyomavirus that infects the majority of the human population worldwide. It is responsible for the fatal demyelinating disease Progressive Multifocal Leukoencephalopathy. JCV binds to cells using the serotonin receptor 5-HT(2A)R and alpha(2-6)- or alpha(2-3)-linked sialic acid. It enters cells using clathrin-dependent endocytosis and traffics to the early endosome and possibly to the endoplasmic reticulum. Viral DNA is then delivered to the nucleus where transcription, replication, and assembly of progeny occur. We found that the early regulatory protein large T antigen accumulates in microdomains in the nucleus adjacent to ND-10 or PML domains. This observation prompted us to explore the role of these domains in JCV infection. We found that a reduction of nuclear PML enhanced virus infection and that an increase in nuclear PML reduced infection. Infection with JCV did not directly modulate nuclear levels of PML but our data indicate that a host response involving interferon beta is likely to restrict virus infection by increasing nuclear PML.

Frequent infection of cerebellar granule cell neurons by polyomavirus JC in progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) occurs most often in immunosuppressed individuals. The lesions of PML result from astrocyte and oligodendrocyte infection by the polyomavirus JC (JCV); JCV has also been shown to infect and destroy cerebellar granule cell neurons (GCNs) in 2 human immunodeficiency virus (HIV)-positive patients. To determine the prevalence and pattern of JCV infection in GCNs, we immunostained formalin-fixed paraffin-embedded cerebellar samples from 40 HIV-positive and 3 HIV-negative PML patients for JCV, and glial and neuronal markers. The JCV infection was detected in 30 patients (70%); 28 (93%) of them had JCV-infected cells in the GC layer; JCV-infected GCNs were demonstrated in 15 (79%) of 19 tested cases. The JCV regulatory T antigen was expressed more frequently and abundantly in GCNs than JCV VP1 capsid protein. None of 37 HIV-negative controls but 1 (3%) of 35 HIV-positive subjects without PML had distinct foci of JCV-infected GCNs. Thus, JCV infection of GCNs is frequent in PML patients and may occur in the absence of cerebellar white matter demyelinating lesions. The predominance of Tantigen over VP1 expression in GCNs suggests that they may be the site of early or latent central nervous system JCV infection. These results indicate that infection of GCNs is an important, previously overlooked, aspect of JCV pathogenesis in immunosuppressed individuals.

Progressive multifocal leukoencephalopathy after rituximab therapy in HIV-negative patients: a report of 57 cases from the Research on Adverse Drug Events and Reports project

Rituximab improves outcomes for persons with lymphoproliferative disorders and is increasingly used to treat immune-mediated illnesses. Recent reports describe 2 patients with systemic lupus erythematosus and 1 with rheumatoid arthritis who developed progressive multifocal leukoencephalopathy (PML) after rituximab treatment. We reviewed PML case descriptions among patients treated with rituximab from the Food and Drug Administration, the manufacturer, physicians, and a literature review from 1997 to 2008. Overall, 52 patients with lymphoproliferative disorders, 2 patients with systemic lupus erythematosus, 1 patient with rheumatoid arthritis, 1 patient with an idiopathic autoimmune pancytopenia, and 1 patient with immune thrombocytopenia developed PML after treatment with rituximab and other agents. Other treatments included hematopoietic stem cell transplantation (7 patients), purine analogs (26 patients), or alkylating agents (39 patients). One patient with an autoimmune hemolytic anemia developed PML after treatment with corticosteroids and rituximab, and 1 patient with an autoimmune pancytopenia developed PML after treatment with corticosteroids, azathioprine, and rituximab. Median time from last rituximab dose to PML diagnosis was 5.5 months. Median time to death after PML diagnosis was 2.0 months. The case-fatality rate was 90%. Awareness is needed of the potential for PML among rituximab-treated persons.

JC virus: an oncogenic virus in animals and humans?

JC virus (JCV) is a human polyomavirus of the Polyomaviridae family, which also includes BK virus and simian vacuolating virus 40 (SV40). JC virus was first isolated in 1971 from the brain of a patient with Progressive Multifocal Leukoencephalopathy (PML). Like other polyomaviruses, JCV has a restricted host range. The virus infects the majority of the human population with seroconversion occurring during adolescence. JCV has a limited and specific tissue tropism infecting the kidney and oligodendrocytes and astrocytes in the central nervous system (CNS). Initial JCV infection is generally asymptomatic in immunocompetent hosts, and it establishes a persistent infection in the kidney and possibly bone marrow. In immunocompromised individuals JCV can cause a lytic infection in the CNS and lead to development of the fatal, demyelinating disease PML. The name polyoma is derived from the Greek terms: poly, meaning many, and oma, meaning tumors, owing to the capacity of this group of viruses to cause tumors. JCV inoculation of small animal models and non-human primates, which are not permissive to a productive JCV infection, leads to tumor formation. Given the ubiquitous nature of the virus and its strong association with cancer in animal models, it is hypothesized that JCV plays a role in human cancers. However, the role for JCV in human cancers and tumor formation is not clear. Some researchers have reported an association of JCV with human cancers including brain tumors, colorectal cancers, and cancers of the gastrointestinal tract, while other groups report no correlation. Here, we review the role of JCV in cancers in animal models and present the findings on JCV in human cancers.

JC virus-specific immune responses in human immunodeficiency virus type 1 patients with progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a frequently fatal disease caused by uncontrolled polyomavirus JC (JCV) in severely immunodeficient patients. We investigated the JCV-specific cellular and humoral immunity in the Swiss HIV Cohort Study. We identified PML cases (n = 29), as well as three matched controls per case (n = 87), with prospectively cryopreserved peripheral blood mononuclear cells and plasma at diagnosis. Nested controls were matched according to age, gender, CD4(+) T-cell count, and decline. Survivors (n = 18) were defined as being alive for >1 year after diagnosis. Using gamma interferon enzyme-linked immunospot assays, we found that JCV-specific T-cell responses were lower in nonsurvivors than in their matched controls (P = 0.08), which was highly significant for laboratory- and histologically confirmed PML cases (P = 0.004). No difference was found between PML survivors and controls or for cytomegalovirus-specific T-cell responses. PML survivors showed significant increases in JCV-specific T cells (P = 0.04) and immunoglobulin G (IgG) responses (P = 0.005). IgG responses in survivors were positively correlated with CD4(+) T-cell counts (P = 0.049) and negatively with human immunodeficiency virus RNA loads (P = 0.03). We conclude that PML nonsurvivors had selectively impaired JCV-specific T-cell responses compared to CD4(+) T-cell-matched controls and failed to mount JCV-specific antibody responses. JCV-specific T-cell and IgG responses may serve as prognostic markers for patients at risk.

Multiple roles for Puralpha in cellular and viral regulation

Pur-alpha is a ubiquitous multifunctional protein that is strongly conserved throughout evolution, binds to both DNA and RNA and functions in the initiation of DNA replication, control of transcription and mRNA translation. In addition, it binds to several cellular regulatory proteins including the retinoblastoma protein, E2F-1, Sp1, YB-1, cyclin T1/Cdk9 and cyclin A/Cdk2. These observations and functional studies provide evidence that Puralpha is a major player in the regulation of the cell cycle and oncogenic transformation. Puralpha also binds to viral proteins such as the large T-antigen of JC virus (JCV) and the Tat protein of human immunodeficiency virus-1 (HIV-1) and plays a role in the cross-communication of these viruses in the opportunistic polyomavirus JC (JCV) brain infection, progressive multifocal leukoencephalopathy (PML). The creation of transgenic mice with inactivation of the PURA gene that encodes Puralpha has revealed that Puralpha is critical for postnatal brain development and has unraveled an essential role of Puralpha in the transport of specific mRNAs to the dendrites and the establishment of the postsynaptic compartment in the developing neurons. Finally, the availability of cell cultures from the PURA knockout mice has allowed studies that have unraveled a role for Puralpha in DNA repair.

Adaptive mutations in the JC virus protein capsid are associated with progressive multifocal leukoencephalopathy (PML)

PML is a progressive and mostly fatal demyelinating disease caused by JC virus infection and destruction of infected oligodendrocytes in multiple brain foci of susceptible individuals. While JC virus is highly prevalent in the human population, PML is a rare disease that exclusively afflicts only a small percentage of immunocompromised individuals including those affected by HIV (AIDS) or immunosuppressive drugs. Viral- and/or host-specific factors, and not simply immune status, must be at play to account for the very large discrepancy between viral prevalence and low disease incidence. Here, we show that several amino acids on the surface of the JC virus capsid protein VP1 display accelerated evolution in viral sequences isolated from PML patients but not in sequences isolated from healthy subjects. We provide strong evidence that at least some of these mutations are involved in binding of sialic acid, a known receptor for the JC virus. Using statistical methods of molecular evolution, we performed a comprehensive analysis of JC virus VP1 sequences isolated from 55 PML patients and 253 sequences isolated from the urine of healthy individuals and found that a subset of amino acids found exclusively among PML VP1 sequences is acquired via adaptive evolution. By modeling of the 3-D structure of the JC virus capsid, we showed that these residues are located within the sialic acid binding site, a JC virus receptor for cell infection. Finally, we go on to demonstrate the involvement of some of these sites in receptor binding by demonstrating a profound reduction in hemagglutination properties of viral-like particles made of the VP1 protein carrying these mutations. Collectively, these results suggest that a more virulent PML causing phenotype of JC virus is acquired via adaptive evolution that changes viral specificity for its cellular receptor(s).

JC virus is a highly prevalent human polyomavirus. Infection with this virus is generally benign and asymptomatic despite viral persistence in the kidney of many people. However, in immunocompromised individuals, very rarely, the infection can progress to become a potentially deadly brain disease called Progressive Multifocal Leukoencephalopathy (PML). The discrepancy between very high viral prevalence and low incidence of PML suggests that there could be some unique viral characteristics that regulate the progression from the asymptomatic infection to the PML. Identification of such factors will help us to understand the basis of PML development and hopefully will lead to the creation of new diagnostic and treatment tools for managing PML. In this work, we demonstrate that the part of the viral surface protein that is thought to be responsible for viral interaction with cellular receptors and infection acquires specific mutations that appear to be critical for the development of PML. These mutations are found more frequently than by simple chance and therefore are thought to be “positively selected.” Based on these results, we hypothesize that the specific mutations in the viral VP1 protein that we have identified are critical for the evolution of JC virus to the version associated with PML.

Treatment options for AIDS patients with progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a demyelinating viral disease produced by the John Cunningham (JC) virus, which is ubiquitously distributed. Up to 80% of adults seroconvert to JC virus. Classically, PML is a life-threatening AIDS-defining disease of the CNS, usually occurring in severely immunocompromised individuals. Until now, and despite several therapeutic attempts, there is no specific treatment for PML. Soon after the widespread use of combination antiretroviral therapy (CART), several studies showed prolonged survival for patients with AIDS-associated PML who were treated with CART. The outcome of PML in patients receiving CART is unpredictable at disease onset. Prognostic markers are needed. The JC virus DNA detection in cerebrospinal fluid by nucleic acid amplification techniques and the CD4+ cell count are the most promising parameters. Higher levels of CD4+ cell counts were independently associated with an improved survival in different clinical observations. A summary of the main current knowledge about AIDS-related PML is presented. The most effective strategy is to optimize CART to completely suppress HIV-1 viral load and allow the best CD4+ T-cell immune recovery. Nowadays, AIDS-related PML is no longer an ultimately fatal disease. A substantial number of HIV-1-infected patients with this condition can improve with CART.

Clinicopathological study of early progressive multifocal leukoencephalopathy incidentally found in a schizophrenia patient

A 58-year-old Japanese man developed psychomotor excitement and hallucinatory paranoia at age 53, which gradually developed to residual schizophrenia. He was administered various common tranquilizers until death. Myelodysplastic syndrome was noted 10 months before death. A routine autopsy was performed. The brain weighed 1365 g, and macroscopic observation revealed no remarkable findings. However, microscopic examination disclosed cells with enlarged and basophilic nuclei, and unusual astrocytes in the demyelinated foci, especially at the corticomedullary junctions in the temporal and occipital lobes. On the other hand, the white matter was relatively intact. Immunohistochemical analysis using anti-JC virus protein, VP-1 antibody, demonstrated JC virus-infected cells in not only abnormal glial cells and neurons but also normal-looking cells, which are suggestive of progressive multifocal leukoencephalopathy (PML). Immunostaining for GFAP revealed severe gliosis and some scattered abnormal enlarged nuclear cells in the lesions. Some clusters of CD8-positive lymphocytes were seen, which kill infected cells. PML could be considered a short-term disease preceding death, as "incidental PML" in this case. This is a rare autopsy case of early PML occurring in a schizophrenia patient with PML.