Inflammatory reactions in progressive multifocal leukoencephalopathy after highly active antiretroviral therapy

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.

Lymphocyte Counts and Multiple Sclerosis Therapeutics: Between Mechanisms of Action and Treatment-Limiting Side Effects

Although the detailed pathogenesis of multiple sclerosis (MS) is not completely understood, a broad range of disease-modifying therapies (DMTs) are available. A common side effect of nearly every MS therapeutic agent is lymphopenia, which can be both beneficial and, in some cases, treatment-limiting. A sound knowledge of the underlying mechanism of action of the selected agent is required in order to understand treatment-associated changes in white blood cell counts, as well as monitoring consequences. This review is a comprehensive summary of the currently available DMTs with regard to their effects on lymphocyte count. In the first part, we describe important general information about the role of lymphocytes in the course of MS and the essentials of lymphopenic states. In the second part, we introduce the different DMTs according to their underlying mechanism of action, summarizing recommendations for lymphocyte monitoring and definitions of lymphocyte thresholds for different therapeutic regimens.

JCPyV VP1 Mutations in Progressive MultifocalLeukoencephalopathy: Altering Tropismor Mediating Immune Evasion?

Polyomaviruses are ubiquitous human pathogens that cause lifelong, asymptomatic infections in healthy individuals. Although these viruses are restrained by an intact immune system, immunocompromised individuals are at risk for developing severe diseases driven by resurgent viral replication. In particular, loss of immune control over JC polyomavirus can lead to the development of the demyelinating brain disease progressive multifocal leukoencephalopathy (PML). Viral isolates from PML patients frequently carry point mutations in the major capsid protein, VP1, which mediates virion binding to cellular glycan receptors. Because polyomaviruses are non-enveloped, VP1 is also the target of the host's neutralizing antibody response. Thus, VP1 mutations could affect tropism and/or recognition by polyomavirus-specific antibodies. How these mutations predispose susceptible individuals to PML and other JCPyV-associated CNS diseases remains to be fully elucidated. Here, we review the current understanding of polyomavirus capsid mutations and their effects on viral tropism, immune evasion, and virulence.

[Immune reconstitution inflammatory syndrome and rebound syndrome in multiple sclerosis patients who stopped disease modification therapy: current understanding and a case report]

More and more multiple sclerosis patients have been receiving treatment with new immunomodulatory drugs. Its discontinuation because of side-effects, lack of efficacy or pregnancy has been increasing as well. This paper reviews such severe complications of natalizumab and fingolimod cessation as immune reconstitution inflammatory syndrome (IRIS) and rebound. The short history, immunopathogenesis and diagnostic criteria of IRIS in individuals with human immunodeficiency virus infection are covered. Clinical and radiological presentations as well as possible pathogenic mechanisms of IRIS in patients treated with natalizumab and fingolimod are discussed. The authors also report the case of a woman with multiple sclerosis treated with fingolimod, who experienced a severe relapse when she stopped treatment. Diagnostic criteria and prognostic factors for IRIS and rebound are needed in patients with multiple sclerosis who discontinue the new disease modification therapy.

Immune Reconstitution Inflammatory Syndrome Unmasking or Worsening AIDS-Related Progressive Multifocal Leukoencephalopathy: A Literature Review

Incidence of progressive multifocal leukoencephalopathy (PML) in HIV-infected patients has declined in the combined antiretroviral therapy (cART) era although a growing number of acquired immunodeficiency syndrome (AIDS)-related PML-immune reconstitution inflammatory syndromes (PML-IRIS) have been published during the same period. Therapeutic management of PML-IRIS is not consensual and mainly relies on corticosteroids. Our main aim was, in addition to provide a thoughtful analysis of published PML-IRIS cases, to assess the benefit of corticosteroids in the management of PML-IRIS, focusing on confirmed cases. We performed a literature review of the 46 confirmed cases of PML-IRIS cases occurring in HIV-infected patients from 1998 to September 2016 (21 unmasking and 25 paradoxical PML-IRIS). AIDS-related PML-IRIS patients were mostly men (sex ratio 4/1) with a median age of 40.5 years (range 12-66). Median CD4 T cell count before cART and at PML-IRIS onset was 45/μl (0-301) and 101/μl (20-610), respectively. After cART initiation, PML-IRIS occurred within a median timescale of 38 days (18-120). Clinical signs were motor deficits (69%), speech disorders (36%), cognitive disorders (33%), cerebellar ataxia (28%), and visual disturbances (23%). Brain MRI revealed hyperintense areas on T2-weighted sequences and FLAIR images (76%) and suggestive contrast enhancement (87%). PCR for John Cunningham virus (JCV) in cerebrospinal fluid (CSF) was positive in only 84% of cases; however, when performed, brain biopsy confirmed diagnosis of PML in 90% of cases and demonstrated histological signs of IRIS in 95% of cases. Clinical worsening related to PML-IRIS and leading to death was observed in 28% of cases. Corticosteroids were prescribed in 63% of cases and maraviroc in one case. Statistical analysis failed to demonstrate significant benefit from steroid treatment, despite spectacular improvement in certain cases. Diagnosis of PML-IRIS should be considered in HIV-infected patients with worsening neurological symptoms after initiation or resumption of effective cART, independently of CD4 cell count prior to cART. If PCR for JCV is negative in CSF, brain biopsy should be discussed. Only large multicentric randomized trials could potentially demonstrate the possible efficacy of corticosteroids and/or CCR5 antagonists in the management of PML-IRIS.

Predictors and characteristics of seizures in survivors of progressive multifocal leukoencephalopathy

This study aims to determine the risk factors for epileptogenesis and characteristics of seizures in patients with progressive multifocal leukoencephalopathy (PML) who survive more than 1 year from onset of neurological symptoms (PML survivors). We reviewed clinical data including seizure history and MR imaging studies from PML survivors evaluated at our institution between 1997 and 2014. PML progressors who passed away within 1 year and patients with a history of seizures prior to PML diagnosis were excluded from the analysis. Of 64 PML survivors, 28 (44 %) developed seizures. The median time from the onset of PML symptoms to the first seizure was 5.4 months (range 0-159) and 64 % of patients with seizures had them within the first year. The presence of juxtacortical PML lesions was associated with a relative risk of seizures of 3.5 (p < 0.02; 95 % confidence interval (CI) 1.3-9.4) in multivariate analyses. Of all seizure types, 86 % were focal and 60 % most likely originated from the frontal lobes. Among seizure patients, 89 % required treatment, including one (54 %), two (25 %), or three (10.5 %) antiepileptic drugs. Seizures are a frequent complication in PML and can develop throughout the entire course of the disease. However, late onset seizures did not signify PML relapse. Seizures may require treatment with multiple antiepileptic medications and are a significant co-morbidity in PML.

Development of primary central nervous system lymphoma associated with human immunodeficiency virus and JC virus infection

We report here a case of a 37-year-old man with human immunodeficiency virus (HIV) infection followed by JC virus (JCV) infection and primary central nervous system lymphoma (PCNSL). The patient had been infected with HIV type 1 due to blood products for hemophilia A during infancy. He had progression of nervous symptoms and was diagnosed with progressive multifocal leukoencephalopathy (PML) clinically at the age of 36, when his CD4-positive lymphocyte counts ranged between 350 and 450/μl. Oral mefloquine, intravenous methylprednisolone pulse therapy, and intravenous immunoglobulin were not effective for the PML, and the patient entered a vegetative state. Brain biopsy revealed JCV infection without pathological findings of PML. Eight months after the clinical diagnosis of PML, he developed respiratory failure and brain magnetic resonance imaging revealed a mass lesion in the brain stem. The patient died 19 months after the diagnosis of PML. Autopsy findings were compatible with PCNSL. EBV-encoded small RNA-1-positive cells were not detected. We present a case of JCV-positive PCNSL with HIV infection complicated with clinical PML.

PML diagnostic criteria: consensus statement from the AAN Neuroinfectious Disease Section

OBJECTIVE

To establish criteria for the diagnosis of progressive multifocal leukoencephalopathy (PML).

METHODS

We reviewed available literature to identify various diagnostic criteria employed. Several search strategies employing the terms "progressive multifocal leukoencephalopathy" with or without "JC virus" were performed with PubMed, SCOPUS, and EMBASE search engines. The articles were reviewed by a committee of individuals with expertise in the disorder in order to determine the most useful applicable criteria.

RESULTS

A consensus statement was developed employing clinical, imaging, pathologic, and virologic evidence in support of the diagnosis of PML. Two separate pathways, histopathologic and clinical, for PML diagnosis are proposed. Diagnostic classification includes certain, probable, possible, and not PML.

CONCLUSION

Definitive diagnosis of PML requires neuropathologic demonstration of the typical histopathologic triad (demyelination, bizarre astrocytes, and enlarged oligodendroglial nuclei) coupled with the techniques to show the presence of JC virus. The presence of clinical and imaging manifestations consistent with the diagnosis and not better explained by other disorders coupled with the demonstration of JC virus by PCR in CSF is also considered diagnostic. Algorithms for establishing the diagnosis have been recommended.

Progressive multifocal leukoencephalopathy presenting as IRIS in an AIDS patient. A case report and literature review

Progressive multifocal leukoencephalopathy causes an infection of the central nervous system by JC virus (JCV), a polyomavirus that destroys oligodendrocytes and their myelin processes. Here, we describe a patient with AIDS who developed a progressive multifocal leucoencephalopathy with the clinical and neuroimaging characteristics of the immune inflammatory reconstitution syndrome. Unlike other opportunistic infections, this disease can present when CD4 T cell counts are higher than those associated with AIDS and also when patients are receiving combined antiretroviral therapy. Clinical suspicion of this form of the disease is based on clinical examination that shows focal neurological deficits associated with magnetic resonance images findings. The histopathological examination of brain biopsy smears and the identification of JCV in cerebrospinal fluid or brain tissue are definitive for the diagnosis.

Encephalitis with infiltration by CD8+ lymphocytes in HIV patients receiving combination antiretroviral treatment

We report the neuropathological findings in 10 HIV-infected patients treated by combination antiretroviral therapy who developed subacute encephalopathy of rapidly progressive onset. Brain biopsy showed encephalitic lesions variably associated with myelin loss and slight axonal damage. There was inconstant, weak expression of HIV protein p24; tests for other pathogens were negative. The most striking feature was diffuse, perivascular and intraparenchymal infiltration by CD8+ T-lymphocytes. Six patients improved after the treatment. Four had an unfavorable outcome and died within a year. Post-mortem in one case confirmed HIV leukoencephalitis with p24-positive multinucleated giant cells, associated with acute demyelinating encephalomyelitis (ADEM) in the cerebellum. There was diffuse infiltration by CD8+ lymphocytes; CD4+ cells were virtually absent. These cases may represent a specific clinicopathological entity, of which a few comparable cases have been already described. They can be included in the wide framework of immune reconstitution disease. Such syndromes have been described with opportunistic infections, but only seldom with HIV infection of the central nervous system (CNS). Our findings support the hypothesis that CD8+ cytotoxic lymphocytes can be harmful in immune reconstitution disease, particularly in the absence of CD4+ lymphocytes. CD8 cytotoxicity produces an acutization of a smoldering infection and/or an immunopathological reaction similar to ADEM.

Management of the immune reconstitution inflammatory syndrome

The immune reconstitution inflammatory syndrome (IRIS) is a frequent early complication of antiretroviral therapy (ART) in patients with advanced HIV. Because there is no confirmatory diagnostic test, the diagnosis is based on clinical presentation and exclusion of alternative causes for deterioration, such as antimicrobial drug resistance. Opportunistic infection treatment should be optimized. Mild cases may require symptomatic therapy alone or nonsteroidal anti-inflammatory drugs. Corticosteroids have been used to treat more severe cases of IRIS associated with mycobacterial and fungal infections. There is evidence from a randomized controlled trial that prednisone reduces morbidity and improves symptoms in paradoxical tuberculosis (TB)-IRIS. Neurological TB-IRIS is potentially life-threatening; high-dose corticosteroids are indicated and ART interruption should be considered if level of consciousness is depressed. When considering corticosteroid treatment clinicians should be aware of their side effects and only use them when the diagnosis of IRIS is certain. In viral forms of IRIS corticosteroids are generally avoided.

Progressive multifocal leukoencephalopathy: why gray and white matter

Since it was first described in 1958, progressive multifocal leukoencephalopathy (PML), a demyelinating disease of the brain caused by the polyomavirus JC (JCV), has evolved tremendously. It was once considered a noninflammatory disease that affected exclusively oligodendrocytes and astrocytes in the white matter of immunosuppressed individuals and was almost always fatal. Today, we understand that PML can present during the course of an immune reconstitution inflammatory syndrome and that it affects a broader range of individuals, including patients with minimal immunosuppression and those who are treated with novel immunomodulatory medications. Furthermore, JCV-infected glial cells are frequently located at the gray matter-white matter junction or within the gray matter, causing demyelinating lesions within cortical areas. Finally, JCV variants can also infect neurons, leading to the recognition of two distinct clinical entities: JCV granule cell neuronopathy and JCV encephalopathy.

Pathology of immune reconstitution inflammatory syndrome in multiple sclerosis with natalizumab-associated progressive multifocal leukoencephalopathy

Natalizumab is an approved medication for highly active multiple sclerosis (MS). Progressive multifocal leukoencephalopathy (PML) may occur as a severe side effect of this drug. Here, we describe pathological and radiological characteristics of immune reconstitution inflammatory syndrome (IRIS), which occurs in natalizumab-associated PML after the cessation of therapy, and we differentiate it from ongoing PML. Brain biopsy tissue and MRI scans from five MS patients with natalizumab-associated PML were analyzed and their histology compared with non-MS PML. Histology showed an extensive CD8-dominated T cell infiltrate and numerous macrophages within lesions, and in nondemyelinated white and grey matter, in four out of five cases. Few or no virally infected cells were found. This was indicative of IRIS as known from HIV patients with PML. Outstandingly high numbers of plasma cells were present as compared to non-MS PML and typical MS lesions. MRI was compatible with IRIS, revealing enlarging lesions with a band-like or speckled contrast enhancement either at the lesion edge or within lesions. Only the fifth patient showed typical PML pathology, with low inflammation and high numbers of virally infected cells. This patient showed a similar interval between drug withdrawal and biopsy (3.5 months) to the rest of the cohort (range 2.5-4 months). MRI could not differentiate between PML-associated IRIS and ongoing PML. We describe in detail the histopathology of IRIS in natalizumab-associated PML. PML-IRIS, ongoing PML infection, and MS exacerbation may be impossible to discern clinically alone. MRI may provide some clues for distinguishing different pathologies that can be differentiated histologically. In our individual cases, biopsy helped to clarify diagnoses in natalizumab-associated PML.

Selective expansion of polyfunctional pathogen-specific CD4(+) T cells in HIV-1-infected patients with immune reconstitution inflammatory syndrome

Since the introduction of highly active antiretroviral therapies (ART), the prognosis for HIV-1 patients has improved immensely. However, approximately 25% of patients can experience a variety of inflammatory symptoms that are collectively known as immune reconstitution inflammatory syndrome (IRIS). Studying the etiology and immunopathology of IRIS has been hampered by the fact that the symptoms and associated opportunistic infections are highly varied. We hypothesized that there is a common mechanism underlying IRIS pathogenesis and investigated a patient group with IRIS related to different pathogens. Functional and phenotypic characterization of PBMC samples was performed by polychromatic flow cytometry after in vitro stimulation with relevant antigenic preparations. In most patients, IRIS events were characterized by the robust increase of preexisting polyfunctional, highly differentiated effector CD4(+) T-cell responses that specifically targeted the antigens of the underlying co-infection. T-cell responses to HIV-1 or other underlying infections were not affected and did not differ between IRIS and non-IRIS patients. These data suggest that patients with IRIS do not have a generalized T-cell dysfunction; instead, IRIS represents a dysregulated CD4(+) T-cell response against residual opportunistic infection antigen. These studies were registered at www.clinical-trials.gov as NCT00557570 and NCT00286767.

Immunological and clinical consequences of treating a patient with natalizumab

BACKGROUND

Long-term therapy with natalizumab increases the risk of progressive multifocal leukoencephalopathy (PML).

OBJECTIVES

We present a patient study through therapy, the diagnosis of PML (after 29 infusions), plasma exchange (PE) and development of immune reconstitution inflammatory syndrome (IRIS).

METHODS

Routine diagnostics, magnetic resonance imaging (MRI), immunological status (flow cytometry, T-cell migration assays and T-cell repertoire analysis), and brain biopsy with immunohistological analysis.

RESULTS

CD49d decreased after 12 months of treatment. At PML diagnosis, CD49d expression and migratory capacity of T cells was low and peripheral T-cell receptor (TCR) complexity showed severe perturbations. The distribution of peripheral monocytes changed from CCR5+ to CCR7+. After PE some changes reverted: CD49d increased and overshot earliest levels, migratory capacities of T cells recovered and peripheral TCR complexity increased. With no clinical, routine laboratory or cerebrospinal fluid (CSF) changes, MRI 2 months after PE demonstrated progressive lesion development. Brain histopathology confirmed the presence of infiltrates indicative of IRIS without clinical signs, immunologically accompanied by CCR7/CCR5 recovery of peripheral monocytes.

CONCLUSION

Natalizumab-associated immunological changes accompanying PML were reversible after PE; IRIS can occur very late, remain asymptomatic and be elusive to CSF analysis. Our study may provide insights into the changes under treatment with natalizumab associated with JC virus control.

Immune reconstitution after a decade of combined antiretroviral therapies for human immunodeficiency virus

The introduction of combined antiretroviral therapies (HAART) has reversed the fatal course of human immunodeficiency virus (HIV) infection. HAART controls virus production and, in most cases, allows the quantitative and functional immune defects caused by HIV to be reversed. Here, we review T cell homeostatic mechanisms that drive immune recovery. These homeostatic mechanisms, as well as differences in T cell antigen exposure, explain the distinct patterns of recovery for HIV-specific T cells versus T cells specific for other pathogens. Immune restoration during HAART can, however, have adverse effects. Immune restoration syndrome occurs in some patients as a result of successful but unbalanced immunity.

JC virus infection of the brain

Since its initial description, there have been significant changes in the epidemiology, pathogenesis, and clinical and imaging manifestations of JCV infection of brain. The most common clinical manifestation is PML. Other recently described CNS manifestations are JCE, JCVGCN, and JCM. Although AIDS is the most common predisposing factor for JCV reactivation, there is increasing incidence of brain manifestations of JCV reactivation in non-HIV settings, including different rheumatologic, hematologic, and oncologic conditions; monoclonal antibody therapy; transplant recipients; primary immunodeficiency syndromes; and even in patients without any recognizable immune deficiency. IRIS may develop secondary to restoration of immunity in HIV-positive patients with PML receiving antiretroviral therapy. This is of profound clinical significance and needs to be diagnosed promptly. Imaging plays a crucial role in the diagnosis of the disease, monitoring of treatment response, identifying disease progression, and predicting prognosis. In this article, current understanding of the epidemiology, pathogenesis, clinical presentations, and all aspects of imaging of JCV infection of the brain have been comprehensively reviewed.

Progressive multifocal leukoencephalopathy and promyelocytic leukemia nuclear bodies: a review of clinical, neuropathological, and virological aspects of JC virus-induced demyelinating disease

Progressive multifocal leukoencephalopathy is a fatal viral-induced demyelinating disease that was once rare but has become more prevalent today. Over the past decades, much has been learned about the disease from molecular study of the etiological agent of the disease, JC virus. Recently, promyelocytic leukemia nuclear bodies (PML-NBs), punctuate structures for important nuclear functions in eukaryotic cells, were identified as an intranuclear target of JC virus infection. Neuropathologically, JC virus-infected glial cells display diffuse amphophilic viral inclusions by hematoxylin–eosin staining (full inclusions), a diagnostic hallmark of this disease. Recent results using immunohistochemistry, however, revealed the presence of punctate viral inclusions preferentially located along the inner nuclear periphery (dot-shaped inclusions). Dot-shaped inclusions reflect the accumulation of viral progeny at PML-NBs, which may be disrupted after viral replication. Structural changes to PML-NBs have been reported for a variety of human diseases, including cancers and neurodegenerative disorders. Thus, PML-NBs may provide clues to the further pathogenesis of JC virus-induced demyelinating disease. Here, we review what we have learned since the disease entity establishment, including a look at recent progress in understanding the relationship between JC virus, etiology and PML-NBs.

Update on immune reconstitution inflammatory syndrome: progress and unanswered questions

The immune reconstitution inflammatory syndrome (IRIS) is characterized by clinical deterioration occurring after the initiation of effective antiretroviral therapy (ART) and results from a disordered and exuberant immune response. The syndrome may present as paradoxical IRIS or unmasking IRIS, depending on whether an opportunistic infection was recognized and treated before ART initiation. Numerous descriptions of IRIS caused by many pathogens were published in the years after the introduction of effective ART. In recent years, with enhanced rollout of ART in resource-limited settings, attention has again focused on IRIS because of the enormous burden of opportunistic infections. This review highlights recent findings elucidating risk factors for and the pathogenesis and treatment of IRIS.

Use of diffusion-weighted imaging to evaluate the initial response of progressive multifocal leukoencephalopathy to highly active antiretroviral therapy: early experience

BACKGROUND AND PURPOSE

IRIS occurs in a small percentage of patients with AIDS following the initiation of HAART. Because PML lesions have a characteristic DWI/ADC appearance, our purpose was to determine if DWI/ADC measurements of PML lesions can be used to follow HAART treatment response and/or identify patients at risk for IRIS.

MATERIALS AND METHODS

Six patients with AIDS and PML who had recently started HAART were retrospectively identified. On the basis of clinical history, patients were classified as having slow (non-IRIS) or rapid (IRIS) progression. Images were obtained at pre-HAART (time point 1) and post-HAART (time point 2). ADC parameters were measured and compared by using the 2-tailed t test.

RESULTS

Seven lesions (4 rapidly progressing, 3 slowly progressing) were identified. Lesions from patients with rapid clinical progression had higher maximal ADC ratios at time point 1. There were also significant correlations between ADC parameters, time to clinical deterioration, and JCV titers.

CONCLUSIONS

The ADC parameters of PML lesions were different for patients with rapid-versus-slow clinical progression. In our preliminary experience, ADC was helpful in diagnosing rapid clinical progression and IRIS. ADC values may correlate with the pathologic changes in PML lesions following HAART therapy.

Immune restoration diseases reflect diverse immunopathological mechanisms

Up to one in four patients infected with human immunodeficiency virus type 1 and given antiretroviral therapy (ART) experiences inflammatory or cellular proliferative disease associated with a preexisting opportunistic infection, which may be subclinical. These immune restoration diseases (IRD) appear to result from the restoration of immunocompetence. IRD associated with intracellular pathogens are characterized by cellular immune responses and/or granulomatous inflammation. Mycobacterial and cryptococcal IRD are attributed to a pathological overproduction of Th1 cytokines. Clinicopathological characteristics of IRD associated with viral infections suggest different pathogenic mechanisms. For example, IRD associated with varicella-zoster virus or JC polyomavirus infection correlate with a CD8 T-cell response in the central nervous system. Exacerbations or de novo presentations of hepatitis associated with hepatitis C virus (HCV) infection following ART may also reflect restoration of pathogen-specific immune responses as titers of HCV-reactive antibodies rise in parallel with liver enzymes and plasma markers of T-cell activation. Correlations between immunological parameters assessed in longitudinal sample sets and clinical presentations are required to illuminate the diverse immunological scenarios described collectively as IRD. Here we present salient clinical features and review progress toward understanding their pathogeneses.

Human polyoma viruses and disease with emphasis on clinical BK and JC

Polyoma viruses are ubiquitous infecting many different mammalian species including humans. There are five known human polyoma viruses. JC virus and BK virus are two polyoma viruses identified nearly three decades ago. Recently WU, KI and Merkel cell polyoma viruses have been isolated from humans. The exact role of these three newly discovered viruses in human disease is not known. Most human polyoma disease is caused by BK and JC viruses which are usually acquired in childhood. Approximately 50-80% of humans have seropositivity to these viruses. Clinically apparent diseases in immunocompetent hosts are extremely rare. These viruses remain latent possibly in the lymphoid organs, neuronal tissue, and kidney and under the circumstances of severe immunosuppression both these viruses reactivate. Neurotropic JC virus reaches the brain and causes progressive multifocal leukoencephalopathy, a demyelinating disease of the central nervous system with a high mortality rate. BK virus is urotheliotropic and its reactivation causes a form of interstitial nephritis, known as BK or polyoma virus associated nephropathy which is associated with high graft loss if not recognized early. There are no known effective antiviral agents for any of the polyoma viruses.

Unmasking of PML by HAART: unusual clinical features and the role of IRIS

For patients with HIV/AIDS, highly active antiretroviral therapy (HAART) is currently the only effective therapy for progressive multifocal leukoencephalopathy (PML), a viral-induced demyelinating disease caused by polyomavirus JC. Immune reconstitution inflammatory syndrome (IRIS) following initiation of HAART can cause paradoxical clinical deterioration in patients with established PML. Because the onset of PML follows soon after initiation of HAART in some cases (unmasking), we investigated the role IRIS plays in unmasked PML. We reviewed records of 20 PML cases seen from 1997-2006 at the UCSD HIV primary care clinic. Eight cases presented with PML symptoms within 6months of initiating HAART (referred to hereafter as unmasked PML), six patients were diagnosed with PML before initiating HAART, and six were diagnosed more than 6months after starting HAART. Patients with unmasked PML constituted 40% of our series, had relatively long survival, and commonly (50%) had lesions exclusively in the posterior fossa, a localization not previously reported with such a high prevalence. Only 3 of the 8 patients with unmasked PML had IRIS reactions as evidenced by contrast enhancement around lesions on MRI, suggesting that IRIS is not necessary for the pathogenesis of this syndrome.

Progressive multifocal leukoencephalopathy in HIV-1 infection

Progressive multifocal leukoencephalopathy is caused by the JC polyomavirus (JCV) and is one of the most feared complications of HIV-1 infection. Unlike other opportunistic infections, this disease can present when CD4 counts are higher than those associated with AIDS and when patients are receiving combined antiretroviral therapy, either shortly after starting or, more rarely, during long term successful treatment. Clinical suspicion of the disease is typically when MRI shows focal neurological deficits and associated demyelinating lesions; however, the identification of JCV in cerebrospinal fluid or brain tissue is needed for a definitive diagnosis. Although no specific treatment exists, the reversal of immunosuppression by combined antiretroviral therapy leads to clinical and MRI stabilisation in 50-60% of patients with the disease, and JCV clearance from cerebrospinal fluid. A substantial proportion of patients treated with combined antiretroviral therapy develop inflammatory lesions, which can be associated with either a favourable outcome or clinical worsening. The reasons for variability in the natural history of progressive multifocal leukoencephalopathy and treatment responses are largely undefined, and more specific and rational approaches to management are needed.

Immune reconstitution inflammatory syndrome

Antiretroviral therapy (ART) inhibits HIV replication, allowing recovery of CD4+ T cell numbers and the restoration of immune function; its introduction has led to improved outcomes for individuals with HIV infection. However, it has been observed that some individuals responding to ART experience a clinical deterioration with symptoms and signs of an inflammatory illness. Immune reconstitution inflammatory syndrome (IRIS) results from pathological immune responses occurring during immune reconstitution. IRIS is best considered a group of disorders with a wide range of clinical manifestations, incorporating disease resulting from pathological inflammation to pathogens, immune-mediated inflammatory disease and autoimmune disease. Clinical effects range from a mild, self-limiting illness to severe morbidity and mortality. Clinicians working in the field of HIV medicine can expect to encounter individuals with IRIS. In this review, we discuss definitions, describe clinical presentations, summarize research relating to pathogenesis and identify risk factors, preventive and management strategies.

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.

PML-IRIS in patients with HIV infection: clinical manifestations and treatment with steroids

BACKGROUND

Progressive multifocal leukoencephalopathy (PML) is an opportunistic infection that develops in immunosuppressed patients with HIV infection. Paradoxically, some of these patients may develop PML during combined antiretroviral therapy in the setting of immune reconstitution. We describe the types of PML in relation to immune reconstitution inflammatory syndrome (IRIS) and the effects of steroid use in these patients.

METHODS

We performed a retrospective review of the literature (1998 to 2007) and of all HIV-infected patients diagnosed with PML-IRIS at Johns Hopkins Hospital (2004 to 2007). We recorded information on clinical features, microbiologic and virological analysis, neuroimaging, pathology, treatment, and outcome.

RESULTS

Of 54 patients with PML-IRIS, 36 developed PML and IRIS simultaneously (PML-s-IRIS) and 18 had worsening of preexisting PML (PML-d-IRIS) after the initiation of combined antiretroviral therapy. PML-IRIS developed between 1 week and 26 months after initiation of antiretroviral therapy. PML-d-IRIS patients developed IRIS earlier, had higher lesion loads on MRI of the brain, had shorter durations of survival, and had higher mortality rate compared to PML-s-IRIS patients. Twelve patients received treatment with steroids, of which five died and seven showed good neurologic recovery. Patients who survived had received steroids early after IRIS diagnosis for longer durations and had contrast enhancement on IRIS neuroimaging.

CONCLUSIONS

Immune reconstitution following initiation of combined antiretroviral therapy may lead to activation of an inflammatory response to detectable or latent JC virus infection. Early and prolonged treatment with steroids may be useful in these patients but requires further investigation.

Progressive multifocal leukoencephalopathy showing extensive spinal cord involvement in a patient with lymphocytopenia

A 64-year-old Japanese man who was diagnosed as having cerebral infarcts at an early clinical stage was found to have progressive multifocal leukoencephalopathy (PML). A decrease of leukocytes and lymphocytes had been detected in the previous year. During a total clinical course of 11 months, he showed marked depletion of lymphocytes ranging from 264/microL to 459/microL. Autopsy disclosed no underlying diseases such as malignancies or tuberculosis. Extensive PML lesions were seen in the cerebral white matter. Small perivascular cuffs comprising many CD8+ T lymphocytes and a few CD4+ T cells were scattered in the PML lesions. CD20+ B cells were rarely evident. The subsets of the infiltrating lymphocytes differed from those of primary or spontaneous PML. Similar extensive PML lesions were observed not only in the cerebellum and brainstem but also in the spinal cord. All 26 segments of the spinal cord, especially the cervical, lumbar and sacral cord, showed extensive lesions involving the lateral and anterior columns. To our knowledge, only three cases of PML with such extensive spinal cord lesions have been reported previously. These three cases, and the present one, may represent a group of PML that shows extensive lesions in the spinal cord as well as the cerebrum, cerebellum and brainstem. The underlying disease in the present case was unclear. Because lymphocytopenia is not observed in primary or spontaneous PML, and the immunohistochemical findings of the infiltrating lymphocytes in the present case are different from primary or spontaneous PML, the decrease in his total blood lymphocytes may have played a significant role in his immunosuppressed condition as the underlying disease.

[Treatment of opportunistic infections in adolescent and adult patients infected with the human immunodeficiency virus during the era of highly active antiretroviral therapy. AIDS Study Group (GESIDA) and National AIDS Plan Expert Committee]

Despite the huge advance that highly active antiretroviral therapy has represented for the prognosis of infection by human immunodeficiency virus (HIV), opportunistic infections continue to be a cause of morbidity and mortality in HIV-infected patients. This is often the case because of severe immunodepression, poor adherence to antiretroviral therapy, failure of therapy, or the fact that patients are unaware of their HIV-positive status and debut with an opportunistic infection. This article updates the guidelines on treatment of acute episodes of various opportunistic infections in HIV-infected patients, including infections due to parasites, fungi, viruses, mycobacteria, and bacteria. This edition has a new chapter on imported parasite infections as well as additional information on endemic mycoses in the chapter on fungal infections, taking into account the growing number of immigrants in our setting. Lastly, the chapter on the immune reconstitution syndrome has also been updated, providing relevant data on a phenomenon that has clinical and diagnostic repercussions in patients who start antiretroviral therapy while they are severely immunodepressed (English version available at http://www.gesida.seimc.org).

Influence of HAART on the clinical course of HIV-1-infected patients with progressive multifocal leukoencephalopathy: results of an observational multicenter study

BACKGROUND

The aim of this study was to analyze the incidence of new cases, survival of HIV-1-infected patients with progressive multifocal leukoencephalopathy (PML), and the characteristics of PML-associated immune reconstitution inflammatory syndrome (IRIS).

METHODS

Multicenter observational cohort study of all HIV-1-infected patients newly diagnosed of PML in 7 hospitals in Barcelona (Spain) from 2002 to 2006. The annual incidence of PML was calculated. Survival was estimated using the Kaplan-Meier method. IRIS was defined as new onset or rapid worsening of PML shortly after initiation of highly active antiretroviral therapy together with a decline in HIV-1 viral load and rising of CD4 lymphocytes.

RESULTS

Sixty-one new cases of PML were diagnosed. The mean survival time was 15 months [95% confidence interval (CI), 11 to 19]. The Kaplan-Meier estimates of the probability of survival were 47.7% (95% CI, 35 to 59) at 6 months, 38.6% (95% CI, 25 to 51) at 12 months, 35.1% (95% CI, 22 to 48) at 24 months, and 25.1% (95% CI, 10 to 40) at 36 months. IRIS was diagnosed in 14 (23%) cases. Mortality was similar in patients with and without IRIS.

CONCLUSIONS

PML continues to be one of the deadliest opportunistic infections in acquired immunodeficiency syndrome patients. The development of PML-associated IRIS has no influence on prognosis.

Immune reconstitution inflammatory syndrome associated with progressive multifocal leukoencephalopathy in a perinatally acquired human immunodeficiency virus-infected young adult

Perinatally infected children represent a large proportion of the youth living with human immunodeficiency virusinfection/acquired immunodeficiency syndrome (HIV/AIDS). Because of nonadherence to treatment, an increasing number of perinatally acquired HIV-infected adolescents and young adults are showing virologic failure and immune suppression. We report a case of progressive multifocal leukoencephalopathy secondary to immune reconstitution inflammatory syndrome in a perinatally HIV-infected young adult, occurred shortly after the revision of an antiretroviral regimen. The patient showed marked improvement with the combination of corticosteroid and antiretroviral treatment.

Neuropathologic contributions to understanding AIDS and the central nervous system

This historical review describes the evolution of the pathogenetic concepts associated with infection by the Human Immunodeficiency Virus (HIV), with emphasis on the pathology of the nervous system. Although the first descriptions of damage to the nervous system in the acquired immunodeficiency syndrome (AIDS) only appeared in 1982, the dramatic diffusion of the epidemic worldwide and the invariably rapidly fatal outcome of the disease, before the introduction of efficient treatment, generated from the beginning an enormous amount of research with rethinking on a number of pathogenetic concepts. Less than 25 years after the first autopsy series of AIDS patients were published and the virus responsible for AIDS was identified, satisfactory definition and classification of a number of neuropathological complications of HIV infection have been established, leading to accurate clinical radiological and biological diagnosis of the main neurological complications of the disease, which remain a major cause of disability and death in AIDS patients. Clinical and experimental studies have provided essential insight into the pathogenesis of CNS lesions and natural history of the disease. The relatively recent introduction of highly active antiretroviral therapy (HAART) in 1995-1996 has dramatically improved the course and prognosis of HIV disease. However, there remain a number of unsolved pathogenetic issues, the most puzzling of which remains the precise mechanism of neuronal damage underlying the specific HIV-related cognitive disorders (HIV dementia). In addition, although HAART has changed the course of neurological complications of HIV infection, new issues have emerged such as the lack of improvement or even paradoxical deterioration of the neurological status in treated patients. Interpretation of these latter data remains largely speculative partly because of the small number of neuropathological studies related to the beneficial consequence of this treatment.

Immune responses to BK and JC viruses in immunocompromised patients

BK virus (BKV) and JC virus (JCV) are ubiquitous human polyomaviruses that establish persistent asymptomatic infections in immunocompetent individuals, but in a minority of immunocompromised patients, reactivate and cause clinical disease. BKV is associated with BKV nephropathy (BKVN) in kidney transplant recipients and JCV is the etiologic agent of progressive multifocal leukoencephalopathy (PML) in AIDS patients. Humoral responses do not appear adequate to protect against reactivation or disease, and both BKVN and PML appear to be due to a failure of cellular immune responses to control the virus. Among the goals of current research is the identification of the functional correlates of cellular immune protection against these viruses in immunocompetent individuals. Such insights may help identify the small subset of patients at risk of BKV and JCV reactivation, aid clinical management and permit the development of immunotherapeutic approaches.

Disorders of immune reconstitution in patients with HIV infection responding to antiretroviral therapy

Patients with HIV infection who were very immunodeficient before achieving a virologic response to antiretroviral therapy (ART) may experience various disorders of immune reconstitution. Immune restoration disease occurs in approximately 10% to 50% of patients and results from the restoration of a pathogen-specific immune response that causes immunopathology and presents as tissue inflammation or cellular proliferative disease. Opportunistic infections occur in no more than 5% of patients, but approximately one half of these patients have higher than expected CD4 T-cell counts and appear to have residual immune dysfunction. Autoimmune disease may arise because the reconstituted immune system confers an increased susceptibility to immune dysregulation but there may be different mechanisms because Graves' disease presents after a median time of about 2 years of ART whereas systemic lupus erythematosus presents earlier. Persistent CD4 T-cell deficiency (< 500/microL) affects up to 60% of patients and appears to reflect depletion of the naïve T-cell pool that results from low production and/or increased turnover of cells.

Visual loss secondary to acquired immunodeficiency virus–related progressive multifocal leukoencephalopathy demonstrating clinical improvement with highly active antiretroviral therapy

BACKGROUND

Progressive multifocal leukoencephalopathy (PML) is a demyelinating brain disease caused by the JC papovavirus. This disease afflicts the immunocompromised, particularly those infected with the human immunodeficiency virus (HIV). PML progresses rapidly, causing a variety of visual and neurologic complications.

CASE REPORT

A 49-year-old HIV-positive man presented with reduced vision, a bilateral left hemianopsia, left-sided motor dysfunction, and mild dementia. Confirmation of the presence of the JC virus in the cerebrospinal fluid and characteristic computed tomography and magnetic resonance imaging changes led to the diagnosis of PML. No treatment was initiated other than continuation of highly active antiretroviral therapy (HAART). The patient was re-examined 8 months later and found to have significant resolution of his visual and neurological symptoms.

CONCLUSION

PML often results in devastating and deadly neurologic deterioration in HIV-positive patients. Although treatment options are limited, HAART can lead to clinical improvement of symptoms and prolong survival time.

Management of infections by the human polyomavirus JC: past, present and future

Progressive multifocal leukoencephalopathy is a fatal demyelinating disease caused by infection of oligodendrocytes by the human polyomavirus known as JC virus. Over the past 10 years, the disease has been documented almost exclusively in AIDS patients, who constitute a rapidly growing population of immunosuppressed individuals. More recently, progressive multifocal leukoencephalopathy has also been described in patients undergoing solid organ or cell transplant, as a result of immunosuppressive therapy to avoid graft rejection. Although there are several reports of successful treatment of progressive multifocal leukoencephalopathy, large-scale prospective trials have been few, and with mixed results. As more is discovered about the biology of JC virus infection and advances are made in targeted parenchymal delivery of therapeutic agents, there is hope for the development of an effective therapy for progressive multifocal leukoencephalopathy.

Immune reconstitution disease associated with parasitic infections following antiretroviral treatment

HIV-associated immune reconstitution disease (IRD) is the clinical presentation or deterioration of opportunistic infections that results from enhancement of pathogen-specific immune responses among patients responding to antiretroviral treatment (ART). The vast majority of reported cases of IRD have been associated with mycobacterial, chronic viral and invasive fungal infections; such cases result from dysregulated augmentation of cell-mediated type 1 cytokine-secreting host immune responses. However, the spectrum of infections now recognized as associated with IRD is expanding and includes a number of parasitic infections, which may be mediated by different immunopathological mechanisms. These include leishmaniasis (visceral, cutaneous, mucosal and post kala azar dermal leishmaniasis), schistosomiasis and strongyloidiasis. Since the major burden of HIV lies in resource-limited countries where access to ART is now rapidly expanding, increased awareness and knowledge of these phenomena is important. Here we review the clinical spectrum and pathogenesis of IRD associated with parasitic infections.

Demyelinating diseases

A diagnosis of demyelination carries important therapeutic and prognostic implications. In most cases the diagnosis is made clinically, and involvement of the histopathologist is largely confined to postmortem confirmation and clinicopathological correlation. However, every now and then, accurate diagnosis of the presence or cause of demyelination before death hinges on the histopathological assessment. Recognition of demyelination depends on an awareness of this as a diagnostic possibility, and on the use of appropriate tinctorial and immunohistochemical stains to identify myelin, axons and inflammatory cells. In biopsy specimens, the critical distinction is usually from ischaemic or neoplastic disease, and the types of demyelinating disease most likely to be encountered are multiple sclerosis, acute-disseminated encephalomyelitis, progressive multifocal leucoencephalopathy and extrapontine myelinolysis. Interpretation of the pathology has to be made in the context of the clinical, radiological and biochemical findings. Freezing of a small amount of fresh tissue allows for later virological studies, and electron microscopy is occasionally helpful for demonstration of viral particles.