Progressive multifocal leukoencephalopathy

Inflammatory progressive multifocal leukoencephalopathy with human T-cell lymphotropic virus-1 coinfection

A middle-aged man with progressive multifocal leukoencephalopathy (PML) in a human T-cell lymphotropic virus type-1 (HTLV-1) carrier on haemodialysis presented with mild dysarthria and ataxia. Brain MRI revealed asymmetric T2-hyperintense lesions in the cerebral white matter, cerebellum and brainstem. A small amount of JC virus (JCV) genome in cerebrospinal fluid was detected by PCR and cerebellar biopsy demonstrated JCV-DNA presence. Pathological findings showed demyelinating lesions and glial cells with mildly enlarged nuclei, accompanied by T-lymphocytes, neutrophils and plasma cell infiltration. The CD4+/CD8+ratio was 0.83. High-dose corticosteroid therapy was effective for inflammatory PML lesions, and the administration of mefloquine combined with mirtazapine led to favourable outcome. The encephalitis in this case is considered to have occurred secondarily to JCV infection in the presence of HTLV-1 infection. Therefore, it is crucial to investigate the presence of HTLV-1 in order to understand the aetiology of this brain inflammation.

Neuropsychiatric Systemic Lupus Erythematosus: Molecules Involved in Its Imunopathogenesis, Clinical Features, and Treatment

Systemic lupus erythematosus (SLE) is an idiopathic chronic autoimmune disease that can affect any organ in the body, including the neurological system. Multiple factors, such as environmental (infections), genetic (many HLA alleles including DR2 and DR3, and genes including C4), and immunological influences on self-antigens, such as nuclear antigens, lead to the formation of multiple autoantibodies that cause deleterious damage to bodily tissues and organs. The production of autoantibodies, such as anti-dsDNA, anti-SS(A), anti-SS(B), anti-Smith, and anti-neuronal DNA are characteristic features of this disease. This autoimmune disease results from a failure of the mechanisms responsible for maintaining self-tolerance in T cells, B cells, or both. Immune complexes, circulating antibodies, cytokines, and autoreactive T lymphocytes are responsible for tissue injury in this autoimmune disease. The diagnosis of SLE is a rheumatological challenge despite the availability of clinical criteria. NPSLE was previously referred to as lupus cerebritis or lupus sclerosis. However, these terms are no longer recommended because there is no definitive pathological cause for the neuropsychiatric manifestations of SLE. Currently, the treatment options are primarily based on symptomatic presentations. These include the use of antipsychotics, antidepressants, and anxiolytic medications for the treatment of psychiatric and mood disorders. Antiepileptic drugs to treat seizures, and immunosuppressants (e.g., corticosteroids, azathioprine, and mycophenolate mofetil), are directed against inflammatory responses along with non-pharmacological interventions.

Misdiagnosed Progressive Multifocal Leukoencephalopathy (PML) in an HIV-Negative Patient With Discoid Lupus: A Case Report

Progressive multifocal leukoencephalopathy (PML) is a rare fetal disease that has been uprising since the 1980s. Accurate diagnosis can be challenging and requires a thorough clinical suspicion, particularly among individuals who do not have HIV infection. Further diagnostics studies including cerebrospinal fluid analysis are required for DNA polymerase chain reaction (PCR) and if negative, more invasive tests like Brain biopsy are required. Herein, we describe a rare case of a 64-year-old female with a history of discoid lupus for 30 years who was not on any medications and presented to the hospital multiple times with different neurological deficits. The initial diagnosis consistently pointed toward a stroke until a critical turning point when a cerebrospinal fluid sample tested positive for John Cunningham (JC) virus DNA. Unfortunately, by the time the disease was identified, it had already progressed significantly, resulting in the unfortunate demise of the patient. To our knowledge, this represents the second reported case of PML in a patient with discoid lupus who lacks other commonly observed risk factors for the disease. This finding underscores the significance of maintaining clinical attentiveness within this specific patient population.

Epileptic seizures associated with progressive multifocal leukoencephalopathy in HIV-infected patients in Korea

We investigated the incidence and risk factors of seizures related to progressive multifocal leukoencephalopathy (PML) in Korean patients infected with HIV. Of the 34 patients, 14 (41.2%) developed epileptic seizures during a median follow-up of 82 months. The median time from PML diagnosis to seizure onset was 44 months, ranging from 0 to 133 months. Patients with PML who developed seizures more commonly had cognitive impairment and multiple or diffuse lesions on brain MRI. These findings highlight the increased seizure risk among HIV-infected patients with PML at any stage of the disease, particularly in cases with extensive involvement.

iPSC-derived three-dimensional brain organoid models and neurotropic viral infections

Progress in stem cell research has revolutionized the medical field for more than two decades. More recently, the discovery of induced pluripotent stem cells (iPSCs) has allowed for the development of advanced disease modeling and tissue engineering platforms. iPSCs are generated from adult somatic cells by reprogramming them into an embryonic-like state via the expression of transcription factors required for establishing pluripotency. In the context of the central nervous system (CNS), iPSCs have the potential to differentiate into a wide variety of brain cell types including neurons, astrocytes, microglial cells, endothelial cells, and oligodendrocytes. iPSCs can be used to generate brain organoids by using a constructive approach in three-dimensional (3D) culture in vitro. Recent advances in 3D brain organoid modeling have provided access to a better understanding of cell-to-cell interactions in disease progression, particularly with neurotropic viral infections. Neurotropic viral infections have been difficult to study in two-dimensional culture systems in vitro due to the lack of a multicellular composition of CNS cell networks. In recent years, 3D brain organoids have been preferred for modeling neurotropic viral diseases and have provided invaluable information for better understanding the molecular regulation of viral infection and cellular responses. Here we provide a comprehensive review of the literature on recent advances in iPSC-derived 3D brain organoid culturing and their utilization in modeling major neurotropic viral infections including HIV-1, HSV-1, JCV, ZIKV, CMV, and SARS-CoV2.

Dynamics and Patterning of 5-Hydroxytryptamine 2 Subtype Receptors in JC Polyomavirus Entry

The organization and dynamics of plasma membrane receptors are a critical link in virus-receptor interactions, which finetune signaling efficiency and determine cellular responses during infection. Characterizing the mechanisms responsible for the active rearrangement and clustering of receptors may aid in developing novel strategies for the therapeutic treatment of viruses. Virus-receptor interactions are poorly understood at the nanoscale, yet they present an attractive target for the design of drugs and for the illumination of viral infection and pathogenesis. This study utilizes super-resolution microscopy and related techniques, which surpass traditional microscopy resolution limitations, to provide both a spatial and temporal assessment of the interactions of human JC polyomavirus (JCPyV) with 5-hydroxytrypamine 2 receptors (5-HT₂Rs) subtypes during viral entry. JCPyV causes asymptomatic kidney infection in the majority of the population and can cause fatal brain disease, and progressive multifocal leukoencephalopathy (PML), in immunocompromised individuals. Using Fluorescence Photoactivation Localization Microscopy (FPALM), the colocalization of JCPyV with 5-HT₂ receptor subtypes (5-HT_2A, 5-HT_2B, and 5-HT_2C) during viral attachment and viral entry was analyzed. JCPyV was found to significantly enhance the clustering of 5-HT₂ receptors during entry. Cluster analysis of infected cells reveals changes in 5-HT₂ receptor cluster attributes, and radial distribution function (RDF) analyses suggest a significant increase in the aggregation of JCPyV particles colocalized with 5-HT₂ receptor clusters in JCPyV-infected samples. These findings provide novel insights into receptor patterning during viral entry and highlight improved technologies for the future development of therapies for JCPyV infection as well as therapies for diseases involving 5-HT₂ receptors.

Progressive Multifocal Leukoencephalopathy Mimicking Malignancy on 68Ga-FAPI PET/CT: Potential Advantages of FAPI

ABSTRACT

A 43-year-old man presented with weakness in his right upper limb for 2 months. Head MRI showed intracranial multiple abnormal signal foci. Malignancy was suspected. The patient was subsequently enrolled in the clinical trial of 68Ga-FAPI PET/CT. 68Ga-FAPI PET/CT showed intracranial multiple FAPI-avid foci. It was also highly suggestive of malignancy. However, the combination of clinical manifestations, imaging findings, cerebral spinal fluid examinations, and effective immunotherapy confirmed the diagnosis of progressive multifocal leukoencephalopathy. 68Ga-FAPI may have potential advantages in the diagnosis of progressive multifocal leukoencephalopathy.

Single-Center Experience on Progressive Multifocal Leukoencephalopathy (PML) cases, neuroimaging relevance, and management at West Virginia University (WVU)

Progressive Multifocal Leukoencephalopathy (PML) is an increasingly common and rapidly fatal demyelinating infection of CNS caused by the highly prevalent JCV in immunocompromised individuals belonging to all age groups and genders. HIV is the most common predisposing factor among other immunodeficient conditions leading to reactivation and multiple neurological symptoms. It has varied findings on MRI and diagnosis is confirmed by positive JC virus in CSF. We report 12 confirmed cases of PML from a single academic center. We comprehensively described clinical presentations, risk factors, CSF and neuroimaging findings, treatment and outcome for these cases of PML, a rare disease. The cases were almost equivalently distributed among young and old age groups and both genders. Positive JC virus on CSF was present in the majority of cases along with mild to severe reduction in lymphocyte counts. Significant MRI changes were present in all cases ranging from T2 hypertense signals to white matter lesions in various regions. Treatment with the reversion of immune-modulators, optimization of antiviral therapy (ART), plasmapheresis (PLEX), IVIG, Mirtazapine, oral steroids, and others was started as soon as the diagnosis was made in the majority of the cases. However, PML is a rapidly fatal illness and hence, survival was only seen in 4 cases in our study. The objective of this article is to highlight the importance of early diagnosis of PML with CSF findings and neuroimaging, early reversion of immunosuppressive medications, and careful monitoring and treatment of HIV cases with goals to reduce mortality, long-term morbidity, and deficits. This article is protected by copyright. All rights reserved.

Microglia in antiviral immunity of the brain and spinal cord

Viral infections of the central nervous system (CNS) are a significant cause of neurological impairment and mortality worldwide. As tissue resident macrophages, microglia are critical initial responders to CNS viral infection. Microglia seem to coordinate brain-wide antiviral responses of both brain resident cells and infiltrating immune cells. This review discusses how microglia may promote this antiviral response at a molecular level, from potential mechanisms of virus recognition to downstream cytokine responses and interaction with antiviral T cells. Recent advancements in genetic tools to specifically target microglia in vivo promise to further our understanding about the precise mechanistic role of microglia in CNS infection.

Site-Specific Small Molecule Labeling of an Internal Loop in JC Polyomavirus Pentamers Using the π-Clamp-Mediated Cysteine Conjugation

The major capsid protein VP1 of JC Polyomavirus assembles into pentamers that serve as a model for studying viral entry of this potentially severe human pathogen. Previously, labeling of viral proteins utilized large fusion proteins or non-specific amine- or cysteine-functionalization with fluorescent dyes. Imaging of these sterically hindered fusion proteins or heterogeneously labeled virions limits reproducibility and could prevent the detection of subtle trafficking phenomena. Here we advance the π-clamp-mediated cysteine conjugation for site-selective fluorescent labeling of VP1-pentamers. We demonstrate a one-step synthesis of a probe consisting of a bio-orthogonal click chemistry handle bridged to a perfluoro-biphenyl π-clamp reactive electrophile by a polyethylene glycol linker. We expand the scope of the π-clamp conjugation by demonstrating selective labeling of an internal, surface exposed loop in VP1. Thus, the π-clamp conjugation offers a general method to selectively bioconjugate tags-of-interest to viral proteins without impeding their ability to bind and enter cells.

Diagnosis, grading and management of toxicities from immunotherapies in children, adolescents and young adults with cancer

Cancer immunotherapies are associated with remarkable therapeutic response rates but also with unique and severe toxicities, which potentially result in rapid deterioration in health. The number of clinical applications for novel immune effector-cell therapies, including chimeric antigen receptor (CAR)-expressing cells, and other immunotherapies, such as immune-checkpoint inhibitors, is increasing. In this Consensus Statement, members of the Pediatric Acute Lung Injury and Sepsis Investigators (PALISI) Network Hematopoietic Cell Transplantation-Cancer Immunotherapy (HCT-CI) Subgroup, Paediatric Diseases Working Party (PDWP) of the European Society of Blood and Marrow Transplantation (EBMT), Supportive Care Committee of the Pediatric Transplantation and Cellular Therapy Consortium (PTCTC) and MD Anderson Cancer Center CAR T Cell Therapy-Associated Toxicity (CARTOX) Program collaborated to provide updated comprehensive recommendations for the care of children, adolescents and young adults receiving cancer immunotherapies. With these recommendations, we address emerging toxicity mitigation strategies, we advocate for the characterization of baseline organ function according to age and discipline-specific criteria, we recommend early critical care assessment when indicated, with consideration of reversibility of underlying pathology (instead of organ failure scores) to guide critical care interventions, and we call for researchers, regulatory agencies and sponsors to support and facilitate early inclusion of young patients with cancer in well-designed clinical trials.

Four cases of progressive multifocal leukoencephalopathy in iatrogenic immunocompromised patients

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system (CNS) caused by John Cunningham Virus (JCV). We report four PML cases in immunocompromised patients, respectively treated with (1) Natalizumab, (2) Rituximab, (3) autologous stem-cell transplantation, and (4) Tacrolimus. All patients underwent neurological examination, magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), JCV-DNA research on biological samples, and lymphocytes subpopulation study. All cases presented with motor, behavioural, and cognitive disorders. Visual, sensitive, and cerebellar deficits developed in three cases. MRI revealed widespread progressive demyelinating areas with active borders; three patients presented contrast enhancement. One patient developed inflammatory reconstitution syndrome (IRIS). At MRS, all cases presented decreased N-acetyl-aspartate (NAA) and three cases showed increased choline (Cho). In one patient, plasma and urine tested positive for JCV-DNA, while cerebrospinal fluid (CSF) analysis confirmed JCV in two patients. The fourth patient had a low JCV-DNA blood titer and brain biopsy showed subacute necrosis. Two patients had abnormal lymphocyte subpopulations. Three patients underwent therapy with Mirtazapine, one of whom received Mefloquine in add-on. No clinical response was registered. Clinical onset, MRI and MRS were highly suggestive of PML in all patients, despite three cases presented contrast enhancement. In three cases JCV-DNA detection in biological samples confirmed the diagnosis. The fourth patient fulfilled diagnosis of “presumptive PML”. Our data confirm the importance to complete the diagnostic workup despite the presence of findings not completely consistent with classical PML. We hypothesize that atypical characteristics could due to the clinical conditions leading to PML.

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Four cases of PML in iatrogenic immunocompromised patients.

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Clinical presentation was typical for PML.

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Diagnostic findings were not completely consistent with classical PML.

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Atypical findings do not exclude diagnosis when clinical data are highly suggestive.

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It is necessary to improve the diagnostic and therapeutic management of patients.

Human Coronaviruses and Other Respiratory Viruses: Underestimated Opportunistic Pathogens of the Central Nervous System?

Respiratory viruses infect the human upper respiratory tract, mostly causing mild diseases. However, in vulnerable populations, such as newborns, infants, the elderly and immune-compromised individuals, these opportunistic pathogens can also affect the lower respiratory tract, causing a more severe disease (e.g., pneumonia). Respiratory viruses can also exacerbate asthma and lead to various types of respiratory distress syndromes. Furthermore, as they can adapt fast and cross the species barrier, some of these pathogens, like influenza A and SARS-CoV, have occasionally caused epidemics or pandemics, and were associated with more serious clinical diseases and even mortality. For a few decades now, data reported in the scientific literature has also demonstrated that several respiratory viruses have neuroinvasive capacities, since they can spread from the respiratory tract to the central nervous system (CNS). Viruses infecting human CNS cells could then cause different types of encephalopathy, including encephalitis, and long-term neurological diseases. Like other well-recognized neuroinvasive human viruses, respiratory viruses may damage the CNS as a result of misdirected host immune responses that could be associated with autoimmunity in susceptible individuals (virus-induced neuro-immunopathology) and/or viral replication, which directly causes damage to CNS cells (virus-induced neuropathology). The etiological agent of several neurological disorders remains unidentified. Opportunistic human respiratory pathogens could be associated with the triggering or the exacerbation of these disorders whose etiology remains poorly understood. Herein, we present a global portrait of some of the most prevalent or emerging human respiratory viruses that have been associated with possible pathogenic processes in CNS infection, with a special emphasis on human coronaviruses.

Prevalence of Anti-JC Virus (JCV) Antibodies in the Multiple Sclerosis (MS) Population in Cyprus: A Retrospective Study

Background and Purpose

Progressive multifocal leukoencephalopathy (PML) is a debilitating disease of the central nervous system caused by the ubiquitous polyomavirus JC (JCV) in immunocompromised hosts. In recent years, a new subpopulation of patients at risk for PML has emerged, due to the growing use of immunomodulatory or immunosuppressive therapies in autoimmune diseases such as multiple sclerosis (MS). The anti-JCV antibody index is used as a stratification tool in assessing the risk of developing PML. The objective of this study was to retrospectively describe the prevalence of anti-JCV antibodies in the MS population in Cyprus.

Methods

We retrospectively collected the demographics of 214 MS patients in Cyprus who were screened for anti-JCV antibodies using the STRATIFY JCV™ assay between September 2011 and June 2018. Logistic regression analysis was used to examine the effect of demographic variables on seropositivity, and bivariate tests were used to assess the association between demographic characteristics and JCV AI index.

Results

A total of 214 MS patients in Cyprus were tested. Overall anti-JCV antibody prevalence was 45.8% (95% confidence interval 37.2%–55.8%). We could not establish a significant association between seropositivity and increasing age or sex. In the subgroup analysis of natalizumab-treated patients, the annual seroconversion rate was 4.5%.

Conclusions

Overall seroprevalence of anti-JCV antibodies in MS patients in Cyprus using the STRATIFY JCV assay was lower than the worldwide reported mean. Although previously reported, in our study, the anti-JCV antibody seropositivity was not associated with increasing age or sex.

Progressive Multifocal Leukoencephalopathy Diagnosed by Brain Biopsy, not by the DNA Test for JC Virus

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system caused by a lytic infection of oligodendrocytes due to the presence of JC polyomavirus (JCV). The disease occurs mostly in immunocompromised patients and is associated with a high mortality rate. The diagnosis of PML is based on a polymerase chain reaction (PCR) assay for JC viral DNA in cerebrospinal fluid (CSF). However, case reports of the diagnosis of PML established with brain biopsy despite negative JCV CSF PCR analysis when clinical and neuroimaging features are suggestive of PML have been published. A 44-year-old male with a 6-year history of acquired immunodeficiency syndrome developed mental confusion and memory impairment despite 3 months of highly active antiretroviral therapy. Magnetic resonance imaging revealed multiple subcortical white matter lesions in bilateral hemispheres and subcortical nuclei including the thalamus and basal ganglia. JCV DNA was not detected in CSF study, but a brain biopsy showed a high JCV DNA titer. The diagnosis of PML was established with brain biopsy. An early brain biopsy may be important in the diagnosis of PML in patients with clinical manifestations and neuroimaging findings if JCV DNA is undetectable in the CSF PCR.

Central nervous system involvement in rheumatoid arthritis patients and the potential implications of using biological agents

Central nervous system (CNS) involvement is quite unusual in patients with rheumatoid arthritis (RA), although cerebral vasculitis, rheumatoid nodules and meningitis have all been reported, and patients with RA may also have CNS comorbidities such as stroke and neuro-degenerative and demyelinating syndromes. It has been found that biological drugs, especially anti-tumour necrosis factor-alpha (anti-TNF-α) drugs, slightly increase the risk of developing demyelinating diseases, and they are consequently discouraged in patients with multiple sclerosis and related disorders. Furthermore, the risk of opportunistic CNS infections is increased in immunosuppressed patients. To review the current literature concerning CNS involvement in patients with RA (including RA-related forms and comorbidities) and the incidence of new-onset CNS diseases in patients with RA undergoing biological treatment (anti-TNF or non-anti-TNF drugs), the Medline database was searched using the key words 'rheumatoid arthritis', 'central nervous system', 'anti-TNF', 'abatacept', 'tocilizumab', 'rituximab' and 'anakinra'. Abstracts not in English were excluded. We selected 76 articles published between 1989 and 2017, which were divided into four groups on the basis of whether CNS involvement was RA-related or not and according to the type of biological agent used (TNF inhibitors or other agents). The RA-related diseases included aseptic meningitis, vasculitis and cerebral rheumatoid nodules, which benefit from immunosuppressive treatments. CNS comorbidities included stroke, seizures, dementia and neuropsychiatric disorders, which have been frequently described in biological agent-naïve patients with RA, and other rarely reported neurological diseases, such as extra-pyramidal syndromes and demyelinating disorders. CNS comorbidities are relatively frequent among patients with RA and may be related to systemic inflammation or concomitant medications. The use of anti-TNF drugs is associated with the risk of developing demyelinating diseases, and CNS infections have been described in patients treated with anti-TNF and non-anti-TNF agents. Non-anti-TNF drugs may be preferred in the case of demyelinating diseases, cerebral vasculitis or neurolupus. Patients with RA may suffer from CNS involvement as a manifestation of RA or as a comorbidity. The treatment of such medical conditions should be guided on the basis of their etiopathogenesis: steroids and immunosuppressants are useful in the case of RA-related CNS diseases but are often detrimental in other situations. Similarly, the choice of biological agents in patients with RA with CNS complications should be guided by a correct diagnosis in order to prevent further complications.

Management guidelines for paediatric patients receiving chimeric antigen receptor T cell therapy

In 2017, an autologous chimeric antigen receptor (CAR) T cell therapy indicated for children and young adults with relapsed and/or refractory CD19+ acute lymphoblastic leukaemia became the first gene therapy to be approved in the USA. This innovative form of cellular immunotherapy has been associated with remarkable response rates but is also associated with unique and often severe toxicities, which can lead to rapid cardiorespiratory and/or neurological deterioration. Multidisciplinary medical vigilance and the requisite health-care infrastructure are imperative to ensuring optimal patient outcomes, especially as these therapies transition from research protocols to standard care. Herein, authors representing the Pediatric Acute Lung Injury and Sepsis Investigators (PALISI) Network Hematopoietic Stem Cell Transplantation (HSCT) Subgroup and the MD Anderson Cancer Center CAR T Cell Therapy-Associated Toxicity (CARTOX) Program have collaborated to provide comprehensive consensus guidelines on the care of children receiving CAR T cell therapy.

A controlled inflammation and a regulatory immune system are associated with more favorable prognosis of progressive multifocal leukoencephalopathy

OBJECTIVE

In the present study, we analyzed the inflammatory profiles of brain tissues obtained from patients with progressive multifocal leukoencephalopathy (PML) due to John Cunningham (JC) virus infection to identify potential prognostic factors.

METHODS

The study included seven patients (two men, five women) who had been pathologically diagnosed with PML, and all of whom were HIV negative. Fixed brain samples were analyzed via hematoxylin and eosin (HE) staining and Klüver-Barrera (KB) staining. We then performed immunohistochemistry (IHC) specific to JC virus capsid proteins (VP1 and VP2/3) and lymphocyte surface markers (CD4, CD8, CD138, and PD-1).

RESULTS

The mean age at onset was 53.4, while the mean duration until biopsy/autopsy was 4.7 months. Four patients were included in the good prognosis (GP) group, while three were included in the poor prognosis (PP) group. Pathological analysis revealed a significantly larger number of CD4-positive T-cell infiltrations (P = .029) in the GP group, along with a preserved CD4:CD8 ratio. Larger numbers of CD138-positive plasma cells were also observed in the GP group (P = .029) than in the PP group. Linear regression analyses revealed a significant association between the numbers of CD138-positive plasma cells and PD-1-positive cells (R² = 0.80).

CONCLUSIONS

Viral loads in the cerebrospinal fluid, a controlled inflammatory response mediated by CD4- and CD8-positive T cells, and plasma cells are associated with PML prognosis. Our findings further indicate that regulatory plasma cells may regulate inflammatory T-cell activity via a PD-1/PD-L1 immuno-checkpoint pathway, thereby protecting the uninfected brain from excessive immune-mediated damage during an active JC virus infection.

[Two patients with progressive multifocal leukoencephalopathy with immune response against JC virus showing good long-term outcome by combination therapy of mefloquine, mirtazapine, and risperidone]

Patient 1 was a 59-year-old woman receiving prednisolone for idiopathic hypereosinophilia. Brain MRI of patient 1 disclosed slight gadolinium enhancement at lesions, indicating inflammation. Patient 2 was a 32-year-old woman with systemic lupus erythematosus under immunosuppressive therapy. Brain biopsy of patient 2 showed balanced infiltration of CD8+ and CD4+ T lymphocytes at the sites of lesions. Both subjects were diagnosed as having progressive multifocal leukoencephalopathy (PML) shortly after the onset of neurological symptoms and were treated with a combination of mefloquine, mirtazapine, and risperidone. Both patients remain alive with improved neurological symptoms even after long-term follow-up (24 months in patient 1 and 45 months in patient 2). Although the prognosis of PML is very poor, our findings suggest that pharmacotherapy may be effective for patients with well-controlled immune reactions against the JC virus.

COS-7-based model: methodological approach to study John Cunningham virus replication cycle

John Cunningham virus (JCV) is a human neurotropic polyomavirus whose replication in the Central Nervous System (SNC) induces the fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML). JCV propagation and PML investigation have been severely hampered by the lack of an animal model and cell culture systems to propagate JCV have been very limited in their availability and robustness. We previously confirmed that JCV CY strain efficiently replicated in COS-7 cells as demonstrated by the progressive increase of viral load by quantitative PCR (Q-PCR) during the time of transfection and that archetypal regulatory structure was maintained, although two characteristic point mutations were detected during the viral cycle. This short report is an important extension of our previous efforts in defining our reliable model culture system able to support a productive JCV infection.

Supernatants collected from transfected cells have been used to infect freshly seeded COS-7 cell line. An infectious viral progeny was obtained as confirmed by Western blot and immunofluorescence assay. During infection, the archetype regulatory region was conserved.

Importantly, in this study we developed an improved culture system to obtain a large scale production of JC virus in order to study the genetic features, the biology and the pathogenic mechanisms of JC virus that induce PML.

[Progressive multifocal encephalopathy in neurological practice]

Progressive multifocal leukoencephalopathy (PML) is considered so far as a rare rapidly progressive demyelinating CNS disease caused by the JC virus activation. Current data suggest that PML developed in people with impaired immunity. However, in some cases PML developed in the absence of severe immunological deficit. In clinical practice, the early diagnosis of PML is difficult because symptoms are mild and, therefore, the physician should be familiar with diagnostic criteria of this disease to make the correct diagnosis and start the symptomatic therapy as soon as possible. This will help to improve patient's state though there is no effective treatment of PML so far. Up to the present moment, antiviral medications, cytostatic drugs, serotonin receptor antagonists, plasmapheresis are widely used. These methods can be used only if the causes of PML have been identified while the patient needs urgent help. Thus, the schemes of pathogenetic treatment with the drugs with pleiotropic effects should be used.

Efficient propagation of archetype JC polyomavirus in COS-7 cells: evaluation of rearrangements within the NCCR structural organization after transfection

John Cunningham virus (JCPyV) is an ubiquitous human pathogen that causes disease in immunocompromised patients. The JCPyV genome is composed of an early region and a late region, which are physically separated by the non-coding control region (NCCR). The DNA sequence of the NCCR distinguishes two forms of JCPyV, the designated archetype and the prototype, which resulted from a rearrangement of the archetype sequence. To date, the cell culture systems for propagating JCPyV archetype have been very limited in their availability and robustness. Prior to this study, it was demonstrated that JCPyV archetype DNA replicates in COS-7 simian kidney cells expressing SV40 TAg and COS-7 cells expressing HIV-1 Tat. Based on these observations, the present study was conducted to reproduce an in vitro model in COS-7 cells transfected with the JCPyV archetype strain in order to study JCPyV DNA replication and analyze NCCR rearrangements during the viral life cycle. The efficiency of JCPyV replication was evaluated by quantitative PCR (Q-PCR) and by hemagglutination (HA) assay after transfection. In parallel, sequence analysis of JCPyV NCCR was performed. JCPyV efficiently replicated in kidney-derived COS-7 cells, as demonstrated by a progressive increase in viral load and virion particle production after transfection. The archetypal structure of NCCR was maintained during the viral cycle, but two characteristic point mutations were detected 28 days after transfection. This model is a useful tool for analyzing NCCR rearrangements during in vitro replication in cells that are sites of viral persistence, such as tubular epithelial cells of the kidney.

JC Polyomavirus Attachment and Entry: Potential Sites for PML Therapeutics

PURPOSE OF REVIEW

JC polyomavirus (JCPyV) is a significant human pathogen that causes an asymptomatic infection in the kidney in the majority of the population. In immunosuppressed individuals, the virus can become reactivated and spread to the brain, causing the fatal, demyelinating disease progressive multifocal leukoencephalopathy (PML). There are currently limited treatment options for this fatal disease. Attachment to receptors and entry into host cells are the initiating events in JCPyV infection and therefore an attractive target for therapeutics to prevent or treat PML. This review provides the current understanding of JCPyV attachment and entry events and the potential therapeutics to target these areas.

RECENT FINDINGS

JCPyV attachment and entry to host cells is mediated by α2,6-linked lactoseries tetrasaccharide c (LSTc) and 5-hydroxytryptamine receptors (5-HT₂Rs), respectively, and subsequent trafficking to the endoplasmic reticulum is required for infection. Recently, vaccines, monoclonal antibodies, and small molecules have shown promise as anti-viral and PML therapies.

SUMMARY

This review summarizes our current understanding of JCPyV attachment, entry, and trafficking and the development of potential PML therapeutics that inhibit these critical steps in JCPyV infection.

Brain Biopsy Is More Reliable than the DNA test for JC Virus in Cerebrospinal Fluid for the Diagnosis of Progressive Multifocal Leukoencephalopathy

The current standard diagnostic approach for progressive multifocal leukoencephalopathy (PML) is to perform a DNA test to identify the presence of the JC virus in cerebrospinal fluid (CSF). A 32-year-old woman with a 5-year history of systemic lupus erythematosus developed right hemiplegia and motor aphasia. MRI revealed a large white matter lesion in the left frontal lobe. JC virus DNA was undetectable in the CSF, but a brain biopsy showed typical histopathology and a high DNA load of the JC virus. The patient was treated with mefloquine and mirtazapine, and is currently alive at 24 months after onset. An early brain biopsy may therefore be important for making a timely diagnosis of PML.

Progressive Multifocal Leukoencephalopathy in a Kidney Transplant Recipient

Progressive multifocal leukoencephalopathy (PML) is a debilitating and often fatal viral disease of the central nervous system. A 39-year-old male kidney transplant recipient presented to our hospital with weakness of the left arm and leg, his immunosuppressive regimen consisted of tacrolimus, mycophenolate sodium, and meprednisone. Magnetic resonance imaging of the brain revealed hypercellularity in neural tissue and a lesion affecting the right ventral and lateral areas of the thalamus and the posterior limb of the internal capsule. The cerebrospinal fluid tested negative for bacteria, fungi, and acid-fast bacilli; cytology revealed no malignant cells. The clinical presentation, brain imaging, biopsy results showing a demyelinating process, and absence of atypical proliferation all suggested that the first diagnosis to be ruled out was PML. The weakness resolved after withdrawal of tacrolimus and mycophenolate sodium. On day 250 after presentation, no further neurologic deterioration was evident, and renal function was stable. The diagnosis of PML may not always be straightforward. Polymerase chain reaction for detecting John Cunningham virus was not available at our center or in the region. However, a negative result using polymerase chain reaction does not rule out PML.

Diagnostic Value and Safety of Stereotactic Biopsy in Acquired Immune Deficiency Syndrome Patients with Intracranial Lesions: Systematic Review and Meta-Analysis

OBJECTIVE

To evaluate the diagnostic value and safety of stereotactic biopsy in acquired immune deficiency syndrome (AIDS) patients with intracranial lesions via meta-analysis.

METHODS

Relevant cohort studies were identified through a literature search in PubMed, Embase, and Ovid from 1985 to October 1, 2016. Appropriate studies were identified per search criteria. Systematic review and meta-analysis were used to assess the diagnostic success rate, changed management rate, clinical improvement rate, mortality rate, morbidity rate, hemorrhage rate, hemorrhage in morbidity rate, and final histologic diagnosis results. Study-specific outcomes were combined per a random effects model. Outcomes were compared between the pre-highly active antiretroviral therapy (HAART) and post-HAART groups. Correlations between outcomes were assessed via meta-regression analysis.

RESULTS

A total of 19 cohort studies with 820 patients were included in this meta-analysis. The weighted proportions per the random effects model were 92.2% (95% confidence interval [CI; 89.3%-94.5%]) for diagnostic success rate, 5.1% (95% CI [2.5%-8.3%]) for morbidity, and 0.7% (95% CI [0%-1.9%]) for mortality. The most common procedure-related morbidity was hemorrhage at 3.3% (95% CI [1.1%-6.3%]). Hemorrhage in morbidity was 78.0% (95% CI [51.4%-97.4%]). Management changed and clinical improvement were 60.4% (95% CI [49.4%-71.0%]) and 34.0% (95% CI [22.2%-46.8%]), respectively. The 4 most common diagnoses were primary central nervous system lymphoma (27.8%; 95% CI [20.2%-36.1%]), progressive multifocal leukoencephalopathy (PML) (21.0%; 95% CI [14.3%-28.4%]), toxoplasma encephalitis (TE) (20.3%; 95% CI [14.3%-27.0%]), and human immunodeficiency virus (HIV) encephalitis (4.1%; 95% CI [1.4%-7.6%]). Multiple diagnoses rate was 1.2% (95% CI [0.0%-3.6%]). HIV encephalitis rate was significantly higher in the post-HAART group than the pre-HAART group (17.9% vs. 3.2%, respectively; P = 0.0024).

CONCLUSIONS

Stereotactic biopsy is a safe and effective way of diagnosing intracranial lesions in patients with AIDS. It is helpful for the differential diagnosis and for choosing a suitable therapy. The 4 most common intracranial lesions in patients with AIDS are lymphoma, PML, TE, and HIV encephalitis.

Safety and diagnostic value of brain biopsy in HIV patients: a case series and meta-analysis of 1209 patients

Early brain biopsy may be indicated in HIV patients with focal brain lesion. This study aimed to evaluate and compare the safety and diagnostic value of brain biopsy in HIV patients in the pre-highly active antiretroviral therapy (HAART) versus post-HAART era via meta-analysis. Appropriate studies were identified per search criteria. The local database was retrospectively reviewed to select a similar patient cohort. Patient demographics, brain biopsy technique, histopathology and patient outcomes were extracted from each study. Study-specific outcomes were combined per random-effects model. Outcomes were compared between the pre-HAART and post-HAART era. Correlations between outcomes and baseline characteristics were assessed via meta-regression analysis. The proportions of histopathological diagnosis were tabulated and compared between the pre- and post-HAART era. Survival analysis was performed for patients in the post-HAART era. A total of 26 studies (including the local database) with 1209 patients were included in this meta-analysis. The most common indications for brain biopsy were diagnosis unlikely to be toxoplasmosis (n=8, 42.1%), focal brain lesion (n=5, 26.3%) or both (n=3, 15.8%). The weighted proportions for diagnostic success were 92% (95% CI 90.0% to 93.8%), change in management 57.7% (45.9% to 69.1%) and clinical improvement 36.6% (26.3% to 47.5%). Morbidity and mortality were 5.7% (3.6% to 8.3%) and 0.9% (0.3% to 1.9%), respectively. Diagnostic success rate was significantly higher in the post-HAART than the pre-HAART era (97.5% vs 91.9%, p=0.047). The odds ratio (OR) for diagnostic success in patients with contrast-enhanced lesions was 2.54 ((1.25 to 5.15), p<0.01). The median survival for HIV patients who underwent biopsy in the post-HAART era was 225 days (90-2446). Brain biopsy in HIV patients is safe with high diagnostic yield. Early brain biopsy should be considered in patients without classic presentation of toxoplasmosis encephalitis.

Progressive Multifocal Leukoencephalopathy with Balanced CD4/CD8 T-Cell Infiltration and Good Response to Mefloquine Treatment

A 53-year-old man was admitted for sub-acute progressive dementia and Gerstmann syndrome. MRI demonstrated lesions in the white matter involving the left parietal lobe, accompanied by speckled or faint linear peripheral enhancement. Brain biopsy revealed JC virus infection in oligodendrocytes and balanced infiltration of CD8+ and CD4+ T lymphocytes. We diagnosed progressive multifocal leukoencephalopathy (PML) with controlled inflammation. The finding of CD4/CD8 T cells in the infected PML brain suggested therapeutically valuable immune system involvement, which we decided to preserve by withholding corticosteroids. We treated the patient with risperidone, cytarabine and mefloquine to suppress virus replication, but not with the corticosteroid that is conventionally used in inflammatory PML cases. The patient was discharged three months after admission, and one year later, his score on the Mini-Mental State Examination had recovered to 26/30, from 5/30 on admission.

Posterior Reversible Encephalopathy Syndrome After Transplantation: a Review

Posterior reversible encephalopathy syndrome (PRES) is a rare neurological disease. Recently, an increase in the number of transplantations has led to more cases being associated with PRES than what was previously reported. Calcineurin inhibitors (CNIs) are major risk factors for PRES in posttransplantation patients. The mechanisms of the development of PRES remain to be unclear. The typical clinical symptoms of PRES include seizures, acute encephalopathy syndrome, and visual symptoms. The hyperintense signal on fluid-attenuated inversion recovery image is the characteristic of the imaging appearance in these patients. In addition, other abnormal signals distributed in multiple locations are also reported in some atypical cases. Unfortunately, PRES is often not recognized or diagnosed too late due to complicated differential diagnoses, such as ischemic stroke, progressive multifocal leukoencephalopathy, and neurodegenerative diseases. Thus, this review emphasizes the importance of considering the possibility of PRES when neurological disturbances appear after solid organ transplantation or hematopoietic cell transplantation. Moreover, this review demonstrates the molecular mechanisms of PRES associated with CNIs after transplantation, which aims to help clinicians further understand PRES in the transplantation era.

Human polyomavirus JC replication and non-coding control region analysis in multiple sclerosis patients under natalizumab treatment

In the last years, the treatment of multiple sclerosis (MS) patients with natalizumab has been associated with the occurrence of progressive multifocal leukoencephalopathy (PML) caused by human polyomavirus JC (JCV). Here, we have shown a significant correlation between patients with JC viruria and positive JC-specific antibody response and patients without JCV-specific antibodies after 1 year of natalizumab (p = 0.0006). Furthermore, JCV-specific quantitative PCR on urine and plasma samples, collected at the enrollment (t0) and every 4 months (t1, t2, t3) in the first year and at two time points (t4 and t5) in the second year of natalizumab treatment, indicated the prevalence of JC viremia rather than JC viruria only in the second year of treatment (p = 0.04). Moreover, the analysis of JCV non-coding control region (NCCR) sequences in peripheral blood mononuclear cells of patients with JC-specific antibodies after 12 natalizumab infusions (t3) revealed the presence of rearranged sequences, whereas the prevalence of genotypes 1A, 1B, and 4 was detected in these patients by VP1 sequence analysis. In summary, JC viruria evaluation seems to be useful to identify early those patients who do not already develop a humoral immune response against JCV. It may also be interesting to study the JCV NCCR rearrangements since they could give us new insights on the onset of neuro-invasive viral variants.

Atypical progressive multifocal leukoencephalopathy in a patient with antisynthetase syndrome

Antisynthetase syndrome is a disorder belonging to the dermatomyositis/polymyositis group, with high rates of morbidity and mortality. We herein present the case of a 71-year-old man who was diagnosed with antisynthetase syndrome and treated with rituximab. Almost three years later, the patient showed right-sided hemiparesis that ultimately progressed to complete hemiplegia and advancing cognitive deterioration with a poor clinical outcome. The neuropathological diagnosis was progressive multifocal leukoencephalopathy. Treatment with rituximab for antisynthetase syndrome itself plays a fundamental role in the development of infectious complications.

Immunological biomarkers identifying natalizumab-treated multiple sclerosis patients at risk of progressive multifocal leukoencephalopathy

Natalizumab-induced progressive multifocal leukoencephalopathy appears to be unleashed by complex interactions between viral and immunological host factors leading the latent form of JC virus to become pathogenic. Positive anti-JC virus antibody status, prior use of immunosuppressants, and increasing duration of natalizumab treatment have been proposed as risk factors for progressive multifocal leukoencephalopathy in multiple sclerosis patients, but while they may help to identify the most appropriate patients for natalizumab, their use have some limitations. Therefore, a large body of studies is ongoing to identify alternative, reliable immunological markers capable to improve the safety and efficacy of therapy, and to guide tailored clinical decisions.

Human coronaviruses: viral and cellular factors involved in neuroinvasiveness and neuropathogenesis

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Human coronavirus (HCoV) are naturally neuroinvasive in both mice and humans.

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Both transneuronal and hematogenous route may allow virus invasion of the CNS.

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Infection of neurons leads to excitotoxicity, neurodegeneration and cell-death.

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HCoV are potentially associated with human neurological disorders.

Among the various respiratory viruses infecting human beings, coronaviruses are important pathogens, which usually infect the upper respiratory tract, where they are mainly associated with common colds. However, in more vulnerable populations, such as newborns, infants, the elderly and immune-compromised individuals, these opportunistic pathogens can also affect the lower respiratory tract, leading to pneumonia, exacerbations of asthma, and various types of respiratory distress syndrome. The respiratory involvement of human coronaviruses has been clearly established since the 1960s. Nevertheless, for almost three decades now, data reported in the scientific literature has also demonstrated that, like it was described for other human viruses, coronaviruses have neuroinvasive capacities since they can spread from the respiratory tract to the central nervous system (CNS). Once there, infection of CNS cells (neurotropism) could lead to human health problems, such as encephalitis and long-term neurological diseases. Neuroinvasive coronaviruses could damage the CNS as a result of misdirected host immune responses that could be associated with autoimmunity in susceptible individuals (virus-induced neuroimmunopathology) and/or viral replication, which directly induces damage to CNS cells (virus-induced neuropathology). Given all these properties, it has been suggested that these opportunistic human respiratory pathogens could be associated with the triggering or the exacerbation of neurologic diseases for which the etiology remains poorly understood. Herein, we present host and viral factors that participate in the regulation of the possible pathogenic processes associated with CNS infection by human coronaviruses and we try to decipher the intricate interplay between virus and host target cells in order to characterize their role in the virus life cycle as well as in the capacity of the cell to respond to viral invasion.

Antibodies reacting with JCPyV_VP2 _167-15mer as a novel serological marker for JC polyomavirus infection

Background

JC polyomavirus (JCPyV) is a widespread human polyomavirus that usually resides latently in its host, but can be reactivated under immune-compromised conditions potentially causing Progressive Multifocal Leukoencephalopathy (PML). Detection of antibodies against the major capsid protein VP1 currently is the main marker for assessment of infection with JCPyV.

Methods

Based on a peptide microarray, peptide JCPyV_VP2_167-15mer was selected and a peptide ELISA was developed for detection of antibodies directed against this peptide. Epitope mapping and computational modelling was performed to further characterize this peptide. In a cohort of 204 healthy subjects it was investigated whether antibodies against JCPyV_VP2_167-15mer were correlated with VP1 serology or urinary viral load.

Results

Epitope mapping of peptide JCPyV_VP2_167-15mer showed that the minimal epitope consisted of L₁₇₃PALTSQEI₁₈₁ with amino acids P₁₇₄, L₁₇₆ and E₁₈₀ being essential for antibody recognition. Computational analysis was used to predict that this epitope is located at an exposed domain of the VP2 capsid protein, readily accessible for immune recognition upon infection. No correlation could be observed with JCPyV VP1 antibody levels, or urinary viral load.

Conclusion

This work indicates that specific antibodies against JCPyV_VP2_167-15mer might be considered as a novel serological marker for infection with JCPyV.

Electronic supplementary material

The online version of this article (doi:10.1186/1743-422X-11-174) contains supplementary material, which is available to authorized users.

Neuroinvasive and neurotropic human respiratory coronaviruses: potential neurovirulent agents in humans

In humans, viral infections of the respiratory tract are a leading cause of morbidity and mortality worldwide. Several recognized respiratory viral agents have a neuroinvasive capacity since they can spread from the respiratory tract to the central nervous system (CNS). Once there, infection of CNS cells (neurotropism) could lead to human health problems, such as encephalitis and long-term neurological diseases. Among the various respiratory viruses, coronaviruses are important pathogens of humans and animals. Human Coronaviruses (HCoV) usually infect the upper respiratory tract, where they are mainly associated with common colds. However, in more vulnerable populations, such as newborns, infants, the elderly, and immune-compromised individuals, they can also affect the lower respiratory tract, leading to pneumonia, exacerbations of asthma, respiratory distress syndrome, or even severe acute respiratory syndrome (SARS). The respiratory involvement of HCoV has been clearly established since the 1960s. In addition, for almost three decades now, the scientific literature has also demonstrated that HCoV are neuroinvasive and neurotropic and could induce an overactivation of the immune system, in part by participating in the activation of autoreactive immune cells that could be associated with autoimmunity in susceptible individuals. Furthermore, it was shown that in the murine CNS, neurons are the main target of infection, which causes these essential cells to undergo degeneration and eventually die by some form of programmed cell death after virus infection. Moreover, it appears that the viral surface glycoprotein (S) represents an important factor in the neurodegenerative process. Given all these properties, it has been suggested that these recognized human respiratory pathogens could be associated with the triggering or the exacerbation of neurological diseases for which the etiology remains unknown or poorly understood.

Progressive multifocal leukoencephalopathy: a rare cause of cerebellar edema and atypical mass effect. A case report

Progressive multifocal leukoencephalopathy (PML) is an opportunistic demyelinating disease of the CNS caused by the JC papovavirus (JCV). Demyelination due to oligodendrocyte death leads to multifocal, asymmetric lesions. MRI is a valuable tool for detecting and differentiating PML from other neuropathies. Radiographically, PML classically presents as bilateral, subcortical white matter lesions with a lack of brain atrophy. As the disease progresses, lesions become larger and coalesce to become confluent. Minor edema and mass effect are infrequently described and the presence of significant mass effect suggests an alternative diagnosis. In our case, a patient demonstrated atypical marked infratentorial mass effect. Bilaterally, cerebellar lesions with associated mass effect were observed, as well as effacement of cerebellar folia and partial effacement of the fourth ventricle. The diagnosis of PML was confirmed with a biopsy of the right cerebellar lesion showing classic PML histology, with JCV DNA detection by polymerase chain reaction in the biopsy material.

Human Polyomavirus JC monitoring and noncoding control region analysis in dynamic cohorts of individuals affected by immune-mediated diseases under treatment with biologics: an observational study

BACKGROUND

Progressive multifocal leukoencephalopathy (PML) onset, caused by Polyomavirus JC (JCPyV) in patients affected by immune-mediated diseases during biological treatment, raised concerns about the safety profile of these agents. Therefore, the aims of this study were the JCPyV reactivation monitoring and the noncoding control region (NCCR) and viral protein 1 (VP1) analysis in patients affected by different immune-mediated diseases and treated with biologics.

METHODS

We performed JCPyV-specific quantitative PCR of biological samples collected at moment of recruitment (t0) and every 4 months (t1, t2, t3, t4). Subsequently, rearrangements' analysis of NCCR and VP1 was carried out. Data were analyzed using χ2 test.

RESULTS

Results showed that at t0 patients with chronic inflammatory rheumatic diseases presented a JCPyV load in the urine significantly higher (p≤0.05) than in patients with multiple sclerosis (MS) and Crohn's disease (CD). It can also be observed a significant association between JC viruria and JCPyV antibodies after 1 year of natalizumab (p=0.04) in MS patients. Finally, NCCR analysis showed the presence of an archetype-like sequence in all urine samples, whereas a rearranged NCCR Type IR was found in colon-rectal biopsies collected from 2 CD patients after 16 months of infliximab. Furthermore, sequences isolated from peripheral blood mononuclear cells (PBMCs) of 2 MS patients with JCPyV antibody at t0 and t3, showed a NCCR Type IIR with a duplication of a 98 bp unit and a 66 bp insert, resulting in a boxB deletion and 37 T to G transversion into the Spi-B binding site. In all patients, a prevalence of genotypes 1A and 1B, the predominant JCPyV genotypes in Europe, was observed.

CONCLUSIONS

It has been important to understand whether the specific inflammatory scenario in different immune-mediated diseases could affect JCPyV reactivation from latency, in particular from kidneys. Moreover, for a more accurate PML risk stratification, testing JC viruria seems to be useful to identify patients who harbor JCPyV but with an undetectable JCPyV-specific humoral immune response. In these patients, it may also be important to study the JCPyV NCCR rearrangement: in particular, Spi-B expression in PBMCs could play a crucial role in JCPyV replication and NCCR rearrangement.

Central Nervous System Infections

Central nervous system (CNS) infections—i.e., infections involving the brain (cerebrum and cerebellum), spinal cord, optic nerves, and their covering membranes—are medical emergencies that are associated with substantial morbidity, mortality, or long-term sequelae that may have catastrophic implications for the quality of life of affected individuals. Acute CNS infections that warrant neurointensive care (ICU) admission fall broadly into three categories—meningitis, encephalitis, and abscesses—and generally result from blood-borne spread of the respective microorganisms. Other causes of CNS infections include head trauma resulting in fractures at the base of the skull or the cribriform plate that can lead to an opening between the CNS and the sinuses, mastoid, the middle ear, or the nasopharynx. Extrinsic contamination of the CNS can occur intraoperatively during neurosurgical procedures. Also, implanted medical devices or adjunct hardware (e.g., shunts, ventriculostomies, or external drainage tubes) and congenital malformations (e.g., spina bifida or sinus tracts) can become colonized and serve as sources or foci of infection. Viruses, such as rabies, herpes simplex virus, or polioviruses, can spread to the CNS via intraneural pathways resulting in encephalitis. If infection occurs at sites (e.g., middle ear or mastoid) contiguous with the CNS, infection may spread directly into the CNS causing brain abscesses; alternatively, the organism may reach the CNS indirectly via venous drainage or the sheaths of cranial and spinal nerves. Abscesses also may become localized in the subdural or epidural spaces. Meningitis results if bacteria spread directly from an abscess to the subarachnoid space. CNS abscesses may be a result of pyogenic meningitis or from septic emboli associated with endocarditis, lung abscess, or other serious purulent infections. Breaches of the blood–brain barrier (BBB) can result in CNS infections. Causes of such breaches include damage (e.g., microhemorrhage or necrosis of surrounding tissue) to the BBB; mechanical obstruction of microvessels by parasitized red blood cells, leukocytes, or platelets; overproduction of cytokines that degrade tight junction proteins; or microbe-specific interactions with the BBB that facilitate transcellular passage of the microorganism. The microorganisms that cause CNS infections include a wide range of bacteria, mycobacteria, yeasts, fungi, viruses, spirochaetes (e.g., neurosyphilis), and parasites (e.g., cerebral malaria and strongyloidiasis). The clinical picture of the various infections can be nonspecific or characterized by distinct, recognizable clinical syndromes. At some juncture, individuals with severe acute CNS infections require critical care management that warrants neuro-ICU admission. The implications for CNS infections are serious and complex and include the increased human and material resources necessary to manage very sick patients, the difficulties in triaging patients with vague or mild symptoms, and ascertaining the precise cause and degree of CNS involvement at the time of admission to the neuro-ICU. This chapter addresses a wide range of severe CNS infections that are better managed in the neuro-ICU. Topics covered include the medical epidemiology of the respective CNS infection; discussions of the relevant neuroanatomy and blood supply (essential for understanding the pathogenesis of CNS infections) and pathophysiology; symptoms and signs; diagnostic procedures, including essential neuroimaging studies; therapeutic options, including empirical therapy where indicated; and the perennial issue of the utility and effectiveness of steroid therapy for certain CNS infections. Finally, therapeutic options and alternatives are discussed, including the choices of antimicrobial agents best able to cross the BBB, supportive therapy, and prognosis.

New insights on human polyomavirus JC and pathogenesis of progressive multifocal leukoencephalopathy

John Cunningham virus (JCV) is a member of the Polyomaviridae family. It was first isolated from the brain of a patient with Hodgkin disease in 1971, and since then the etiological agent of the progressive multifocal leukoencephalopathy (PML) was considered. Until the human immunodeficiency virus (HIV) pandemic, PML was rare: in fact HIV-induced immunodeficiency is the most common predisposing factor accounting for 85% of all instances of PML. This data led to intense research on JCV infection and resulted in better understanding of epidemiology and clinic-pathologic spectrum. Recently, cases of PML have been observed after the introduction of monoclonal antibodies, such as natalizumab, rituximab, efalizumab, and infliximab, in the treatment of autoimmune disease, underlining the important role of host immunity in PML pathogenesis. In this review current understanding of the JCV infection and the new findings relating to the pathogenesis of PML has been comprehensively revised, focusing our attention on the interaction between the cellular and viral molecular pathways implicated in the JCV infection and the modulating role of host immune surveillance in the viral reactivation from a latent state.

Progressive multifocal leukoencephalopathy and palliative care: a report of three cases and review of the literature

Progressive multifocal leukoencephalopathy (PML) is a rare but usually fatal demyelinating disease of the central nervous system in patients who are immunocompromised. It is characterized by rapid neurological deterioration associated with progressive white matter changes on imaging and is confirmed by isolation of the causative virus in the cerebrospinal fluid or brain tissue. Currently there are no effective treatments for PML and outcomes remain poor even after reversal of the immunocompromised state. This case series describes three patients with different underlying pathologies and varying presentations who were all diagnosed with PML and referred to a palliative care service.