AIDS-associated progressive multifocal leukoencephalopathy : current management strategies

Neuroinvasion, neurotropic, and neuroinflammatory events of SARS-CoV-2: understanding the neurological manifestations in COVID-19 patients

Respiratory viruses are opportunistic pathogens that infect the upper respiratory tract in humans and cause severe illnesses, especially in vulnerable populations. Some viruses have neuroinvasive properties and activate the immune response in the brain. These immune events may be neuroprotective or they may cause long-term damage similar to what is seen in some neurodegenerative diseases. The new “Severe Acute Respiratory Syndrome Coronavirus 2” (SARS-CoV-2) is one of the Respiratory viruses causing highly acute lethal pneumonia coronavirus disease 2019 (COVID-19) with clinical similarities to those reported in “Severe Acute Respiratory Syndrome Coronavirus”(SARS-CoV) and the “Middle East Respiratory Syndrome Coronavirus”(MERS-CoV) including neurological manifestation. To examine the possible neurological damage induced by SARS-CoV-2, it is necessary to understand the immune reactions to viral infection in the brain, and their short- and long-term consequences. Considering the similarities between SARS-CoV and SARS-CoV-2, which will be discussed, cooperative homological and phylogenetical studies lead us to question if SARS-CoV-2 can have similar neuroinvasive capacities and neuroinflammatiory events that may lead to the same short- and long-term neuropathologies that SARS-CoV had shown in human and animal models. To explain the neurological manifestation caused by SARS-CoV-2, we will present a literature review of 765 COVID-19 patients, in which 18% had neurological symptoms and complications, including encephalopathy, encephalitis and cerebrovascular pathologies, acute myelitis, and Guillain-Barré syndrome. Clinical studies describe anosmia or partial loss of the sense of smell as the most frequent symptom in COVID19 patients, suggesting that olfactory dysfunction and the initial ultrarapid immune responses could be a prognostic factor.

Neuropathology of wild-type and nef-attenuated T cell tropic simian immunodeficiency virus (SIVmac32H) and macrophage tropic neurovirulent SIVmac17E-Fr in cynomolgus macaques

The neuropathology of simian immunodeficiency (SIV) infection in cynomolgus macaques (Macaca fascicularis) was investigated following infection with either T cell tropic SIVmacJ5, SIVmacC8 or macrophage tropic SIVmac17E-Fr. Formalin fixed, paraffin embedded brain tissue sections were analysed using a combination of in situ techniques. Macaques infected with either wild-type SIVmacJ5 or neurovirulent SIVmac17E-Fr showed evidence of neuronal dephosphorylation, loss of oligodendrocyte and CCR5 staining, lack of microglial MHC II expression, infiltration by CD4⁺ and CD8⁺ T cells and mild astrocytosis. SIVmacJ5-infected animals exhibited activation of microglia whilst those infected with SIVmac17E-Fr demonstrated a loss of microglia staining. These results are suggestive of impaired central nervous system (CNS) physiology. Furthermore, infiltration by T cells into the brain parenchyma indicated disruption of the blood brain barrier (BBB). Animals infected with the Δnef-attenuated SIVmacC8 showed microglial activation and astrogliosis indicative of an inflammatory response, lack of MHC II and CCR5 staining and infiltration by CD8⁺ T cells. These results demonstrate that the SIV infection of cynomolgus macaque can be used as a model to replicate the range of CNS pathologies observed following HIV infection of humans and to investigate the pathogenesis of HIV associated neuropathology.

Human Polyomavirus-Associated Cerebral Disorders in the Post-HAART Era

Human polyomavirus JC is the causative agent of a deadly form of sudden onset dementia, progressive multifocal leukocoencephalopathy (PML). PML is highly prevalent in immunodeficient populations, specially those undergoing chemotherapy, immunosuppressive treatments for autoimmune conditions, and HIV-1/AIDS patients. In fact, before the highly active antiretroviral therapy (HAART) regimens became available, PML was a leading cause of death in HIV-1 seropositive individuals. However, patients under HAART show increased survival times with better prognoses. In this report we described the main differences between PML before and after the HAART era; highlighting the new patterns of presentation, the neurotropism of other human polyomaviruses, and the increased prevalence of immune reconstitution inflammatory syndrome (IRIS), as a complication of PML in patients under HAART. Lastly, we propose a revised classification of human poliomavirus-associated cerebral disorders that may reflect more accurately what clinicians encounter in their everyday practice.

HIV-related acute inflammatory leukoencephalopathy of undetermined origin: review of the literature

HIV-related acute inflammatory leukoencephalopathy of undetermined origin (AIL) has been anecdotally described in literature as being responsible for cognitive and motor deficits. We carried out a review of all the cases of AIL published in literature. Articles were selected according to 2 criteria: acute onset of symptoms; undetermined aetiology and non-fulfilment of multiple sclerosis diagnostic criteria. They were then analyzed in terms of clinical, biological and instrumental features, therapy, diagnostic classification and prognosis. Although rare (21 patients out of about 4,000 publications), AIL is of particular interest, as the comprehension of its mechanisms could give some insight into the direct and immune-mediated actions of HIV within the brain. All the reported patients share several clinical, histopathological, radiological and CSF features, leading to hypothesize a similar aetiopathogenetic mechanism. Conversely, we observed a high heterogeneity of treatment and diagnostic classification, which could have conditioned the broad prognostic variability. The absence of a defined aetiology leads to consider these forms as a particular subgroup of not determined leucoencephalopathies (NDLE), with both MRI and histological pattern dominated by inflammation as distinctive feature.

Incidence, clinical presentation, and outcome of progressive multifocal leukoencephalopathy in HIV-infected patients during the highly active antiretroviral therapy era: a nationwide cohort study

BACKGROUND

Human immunodeficiency virus (HIV) infection predisposes to progressive multifocal leukoencephalopathy (PML). Here, we describe the incidence, presentation, and prognosis of PML in HIV-1-infected patients during the period before highly active antiretroviral therapy (HAART) (1995-1996) and during the early HAART (1997-1999) and late HAART (2000-2006) periods.

METHODS

Patients from a nationwide population-based cohort of adult HIV-1-infected individuals were included. We calculated incidence rates of PML and median survival times after diagnosis. We also described neurological symptoms at presentation and follow-up.

RESULTS

Among 4,649 patients, we identified 47 patients with PML. The incidence rates were 3.3, 1.8, and 1.3 cases per 1000 person-years at risk in 1995-1996, 1997-1999, and 2000-2006, respectively. The risk of PML was significantly associated with low CD4(+) cell count, and 47% of cases were diagnosed by means of brain biopsy or polymerase chain reaction analysis for JC virus. The predominant neurological symptoms at presentation were coordination disturbance, cognitive defects, and limb paresis. Thirty-five patients died; the median survival time was 0.4 years (95% confidence interval [CI], 0.0-0.7) in 1995-1996 and 1.8 years (95% CI, 0.6-3.0) in both 1997-1999 and 2000-2006. CD4(+) cell count >50 cells/microL at diagnosis of PML was significantly associated with reduced mortality.

CONCLUSIONS

The incidence of PML in HIV-infected patients decreased after the introduction of HAART. Survival after PML remains poor. In the management of PML, the main focus should be on prophylactic measures to avoid immunodeficiency.

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.

Aids-related progressive multifocal leukoencephalopathy: a retrospective study in a referral center in São Paulo, Brazil

Few data are available about progressive multifocal leukoencephalopathy (PML) in patients with acquired immunodeficiency syndrome (AIDS) from Brazil. The objectives of this study were to describe the main features of patients with PML and estimate its frequency among AIDS patients with central nervous system (CNS) opportunistic diseases admitted to the Instituto de Infectologia Emílio Ribas, São Paulo, Brazil, from April 2003 to April 2004. A retrospective and descriptive study was performed. Twelve (6%) cases of PML were identified among 219 patients with neurological diseases. The median age of patients with PML was 36 years and nine (75%) were men. Nine (75%) patients were not on antiretroviral therapy at admission. The most common clinical manifestations were: focal weakness (75%), speech disturbances (58%), visual disturbances (42%), cognitive dysfunction (42%), and impaired coordination (42%). The median CD4+ T-cell count was 45 cells/µL. Eight (67%) of 12 patients were laboratory-confirmed with PML and four (33%) were possible cases. Eleven (92%) presented classic PML and only one case had immune reconstitution inflammatory syndrome (IRIS)-related PML. In four (33%) patients, PML was the first AIDS-defining illness. During hospitalization, three patients (25%) died as a result of nosocomial pneumonia and nine (75%) were discharged to home. Cases of PML were only exceeded by cases of cerebral toxoplasmosis, cryptococcal meningoencephalitis, and CNS tuberculosis, the three more frequent neurologic opportunistic infections in Brazil. The results of this study suggest that PML is not an uncommon HIV-related neurologic disorder in a referral center in Brazil.

An exploratory study of long-term neurocognitive outcomes following recovery from opportunistic brain infections in HIV+ adults

Central nervous system opportunistic infections (CNS-OI) are a significant cause of morbidity and mortality in AIDS. While current interventions are increasingly successful in treating CNS-OI, little information exists regarding long-term behavioral outcomes among survivors. In this exploratory study we examined neurocognitive data among three groups of adults with different AIDS-related CNS-OI: 15 with past cryptococcal meningitis (CM), 8 with toxoplasmosis encephalitis (TE), and 8 with progressive multifocal leukoencephalopathy (PML). A group of 61 individuals with AIDS, but without CNS-OI, was used as a comparison group. A battery of standardized neuropsychological tests assessing a variety of cognitive domains was administered upon entry. Results indicate that individuals with a history of CNS-OI were most impaired on measures of cognitive and psychomotor speed relative to the HIV+ comparison group. Among the CNS-OI groups, individuals with history of TE had the most severe and varied deficits. The results are discussed in relation to what is known about the neuropathological consequences of the various CNS-OIs. While this is the first systematic group study of residual CNS-OI effects on neurocognitive function, future studies employing more participants, perhaps focusing on specific CNS-OIs, will further characterize the long-term outcomes in AIDS-related CNS-OI.

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

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

Progressive multifocal leukoencephalopathy in an AIDS patient

Progressive multifocal leukoencephalopathy (PML) is a demyelinating brain disease caused by Jamestown Canyon virus (JCV). This disease is an important cause of morbidity and mortality in acquired immunodeficiency syndrome (AIDS) patients. We report a 34-year-old man infected with HIV-1 who presented with frequent general tonic clonic seizure and left side weakness for 2 months. Clinical features and magnetic resonance imaging (MRI) findings with hyperintensity on T2-weighted imaging and low density on T2 fluid attenuated inversion recovery involving multiple white matter were compatible with PML. He died of sepsis 2 months after diagnosis. Autopsy demonstrated progressive multifocal leukoencephalopathy according to characteristic histopathologic picture with multifocal demyelination, bizarre astrocytes formation and basophilic intranuclear inclusion bodies in the oligodendrocytes. JCV genome was demonstrated in the nucleus of oligodendrocytes using in situ hybridization. In conclusion, in AIDS patients with neurologic signs and typical MRI findings who present with multifocal demyelination lesions, PML should be diagnosed clinically.

Multiple sclerosis, natalizumab therapy, and progressive multifocal leukoencephalopathy

PURPOSE OF REVIEW

Multiple sclerosis affects many people, often in early adulthood, and causes significant disability. Natalizumab is a novel agent to be evaluated for multiple sclerosis and Crohn's disease that has demonstrated unique efficacy but has unfortunately been implicated in three cases of progressive multifocal leukoencephalopathy. This review covers the mechanism of action of natalizumab and efficacy for multiple sclerosis, the three cases of natalizumab-associated progressive multifocal leukoencephalopathy, our understanding of progressive multifocal leukoencephalopathy, and the mechanisms that may account for these events.

RECENT FINDINGS

Natalizumab, an anti-alpha4-integrin antibody, binds to T-cell surface receptors to prevent migration from the circulation into the brain tissue. Phase II and III trials have been completed and demonstrate previously unseen efficacy in preventing relapses and disease progression. The cases of progressive multifocal leukoencephalopathy, two fatal and one disabling, resulted in the voluntary suspension of natalizumab and bring this entire class of agents into doubt. It is important to determine what led to the development of progressive multifocal leukoencephalopathy in the natalizumab-associated cases and to advance understanding and continue to develop therapies for the treatment of multiple sclerosis.

SUMMARY

With ongoing safety evaluations, natalizumab is being reevaluated by the US Food and Drug Administration for possible reapproval and return to the market. If natalizumab is reapproved, challenging questions and issues will remain in treating patients with multiple sclerosis.

Irisolidone, an isoflavone metabolite, represses JC virus gene expression via inhibition of Sp1 binding in human glial cells

Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease that results from an oligodendrocyte infection caused by the JC virus. Therefore, inhibiting the expression of JC virus is important for preventing and/or treating PML. This study found that irisolidone, an isoflavone metabolite, significantly inhibited the JC virus expression in primary cultured human astrocytes and glial cell lines. Studies examining the underlying mechanism revealed that a mutation of the Sp1 binding site downstream of the TATA box (Sp1-II) dramatically diminished the inhibitory activity of irisolidone. In addition, an irisolidone treatment repressed Sp1 binding to Sp1-II site, which is important for the basal JC virus promoter activity. The results suggest that the inhibitory effect of irisolidone against the JC virus may be attributed at least in part to the suppression of Sp1 binding to the JC virus promoter region. Therefore, the inhibition of the JC virus expression by irisolidone might provide therapeutic potential for PML caused by the JC virus.