Severe aseptic leucoencephalopathy as immune reconstitution inflammatory syndrome in Caucasian and African patients

Cognitive impairment in people living with HIV: consensus recommendations for a new approach

Current approaches to classifying cognitive impairment in people living with HIV can overestimate disease burden and lead to ambiguity around disease mechanisms. The 2007 criteria for HIV-associated neurocognitive disorders (HAND), sometimes called the Frascati criteria, can falsely classify over 20% of cognitively healthy individuals as having cognitive impairment. Minimum criteria for HAND are met on the basis of performance on cognitive tests alone, which might not be appropriate for populations with diverse educational and socioeconomic backgrounds. Imprecise phenotyping of cognitive impairment can limit mechanistic research, biomarker discovery and treatment trials. Importantly, overestimation of cognitive impairment carries the risk of creating fear among people living with HIV and worsening stigma and discrimination towards these individuals. To address this issue, we established the International HIV-Cognition Working Group, which is globally representative and involves the community of people living with HIV. We reached consensus on six recommendations towards a new approach for diagnosis and classification of cognitive impairment in people living with HIV, intended to focus discussion and debate going forward. We propose the conceptual separation of HIV-associated brain injury - including active or pretreatment legacy damage - from other causes of brain injury occurring in people living with HIV. We suggest moving away from a quantitative neuropsychological approach towards an emphasis on clinical context. Our recommendations are intended to better represent the changing profile of cognitive impairment in people living with HIV in diverse global settings and to provide a clearer framework of classification for clinical management and research studies.

HIV-Associated CD8 Encephalitis: A UK Case Series and Review of Histopathologically Confirmed Cases

HIV-associated CD8-encephalitis (HIV-CD8E) is a severe inflammatory disorder dominated by infiltration of the brain by CD8+ T-lymphocytes. It occurs in people with HIV, typically when the virus is apparently well-controlled by antiretroviral treatment (ART). HIV-CD8E presents with symptoms and signs related to marked cerebral inflammation and swelling, and can lead to coma and death unless treated promptly with corticosteroids. Risk events such as intercurrent infection, antiretroviral therapy interruption, immune reconstitution inflammatory syndrome (IRIS) after starting ART, and concomitant associations such as cerebrospinal fluid (CSF) HIV viral escape have been identified, but the pathogenesis of the disorder is not known. We present the largest case series of HIV-CD8E to date (n = 23), representing histopathologically confirmed cases in the UK. We also summarize the global literature representing all previously published cases with histopathological confirmation (n = 30). A new variant of HIV-CD8E is described, occurring on a background of HIV encephalitis (HIVE).Together these series, totalling 53 patients, provide new insights. CSF HIV viral escape was a frequent finding in HIV-CD8E occurring in 68% of those with CSF available and tested; ART interruption and IRIS were important, both occurring in 27%. Black ethnicity appeared to be a key risk factor; all but two UK cases were African, as were the majority of the previously published cases in which ethnicity was stated. We discuss potential pathogenic mechanisms, but there is no unifying explanation over all the HIV-CD8E scenarios.

CD8+ T-cell encephalitis mimicking PRES in AIDS: a case report

Background

Diverse mechanisms including infections, autoimmune inflammatory reactions, neoplasms, and degeneration are involved in the central nervous system in cases of acquired immune deficiency syndrome. In such cases, it is difficult to determine the precise pathogenesis by radiological examination and laboratory testing.

Case presentation

We report a 37-year-old Japanese woman who had untreated hypertension and gender identity disorder and had been taking testosterone injections since she was 19 years old. She developed a headache and visual field deficits together with elevated blood pressure. According to radiological findings, she was initially suspected as having posterior reversible encephalopathy syndrome in the right parieto-occipital lobe with reversible cerebral vasoconstriction syndrome. Human immunodeficiency virus antibody was positive and the CD4⁺ T-lymphocyte count was 140 cells/μl. Therefore, antiretroviral therapy was started. Antiretroviral therapy suppressed the activity of acquired immune deficiency syndrome but worsened her visual symptoms and expanding radiological lesions. Brain biopsy led to the diagnosis of CD8⁺ encephalitis, and she also fulfilled the diagnosis of paradoxical immune reconstitution inflammatory syndrome. Corticosteroid therapy alleviated her symptoms.

Conclusions

This is a rare case of CD8⁺ encephalitis, with an exacerbation owing to paradoxical immune reconstitution inflammatory syndrome after antiretroviral therapy, which radiologically mimicked posterior reversible encephalopathy syndrome. Corticosteroid therapy was effective; thus, it is important to provide a pathological diagnosis in such cases.

HIV neuropathology

Primary human immunodeficiency virus (HIV) neuropathologies can affect all levels of the neuraxis and occur in all stages of natural history disease. Some, like HIV encephalitis, HIV myelitis, and diffuse infiltrative lymphocytosis of peripheral nerve, reflect productive infection of the nervous system; others, like vacuolar myelopathy, distal symmetric polyneuropathy, and central and peripheral nervous system demyelination, are not clearly related to regional viral replication, and reflect more complex cascades of dysregulated host immunity and metabolic dysfunction. In pediatric patients, the spectrum of neuropathology is altered by the impacts of HIV on a developing nervous system, with microcephaly, abundant brain mineralization, and corticospinal tract degeneration as examples of this unique interaction. With efficacious therapies, CD8 T-cell encephalitis is emerging as a significant entity; often this is clinically recognized as immune reconstitution inflammatory syndrome, but has also been described in the context of viral escape and treatment interruption. The relationship of HIV neuropathology to clinical symptoms is sometimes straightforward, and sometimes mysterious, as individuals can manifest significant deficits in the absence of discrete lesions. However, at all stages of the natural history disease, neuroinflammation is abundant, and critical to the generation of clinical abnormality. Neuropathologic and neurobiologic investigations will be central to understanding HIV nervous system disorders in the era of efficacious therapies.

Lymphocyte-Dominant Encephalitis and Meningitis in Simian Immunodeficiency Virus-Infected Macaques Receiving Antiretroviral Therapy

A retrospective neuropathologic review of 30 SIV-infected pigtailed macaques receiving combination antiretroviral therapy (cART) was conducted. Seventeen animals with lymphocyte-dominant inflammation in the brain and/or meninges that clearly was morphologically distinct from prototypic SIV encephalitis and human immunodeficiency virus encephalitis were identified. Central nervous system (CNS) infiltrates in cART-treated macaques primarily comprised CD20⁺ B cells and CD3⁺ T cells with fewer CD68⁺ macrophages. Inflammation was associated with low levels of SIV RNA in the brain as shown by in situ hybridization, and generally was observed in animals with episodes of cerebrospinal fluid (CSF) viral rebound or sustained plasma and CSF viremia during treatment. Although the lymphocytic CNS inflammation in these macaques shared morphologic characteristics with uncommon immune-mediated neurologic disorders reported in treated HIV patients, including CNS immune reconstitution inflammatory syndrome and neurosymptomatic CSF escape, the high prevalence of CNS lesions in macaques suggests that persistent adaptive immune responses in the CNS also may develop in neuroasymptomatic or mildly impaired HIV patients yet remain unrecognized given the lack of access to CNS tissue for histopathologic evaluation. Continued investigation into the mechanisms and outcomes of CNS inflammation in cART-treated, SIV-infected macaques will advance our understanding of the consequences of residual CNS HIV replication in patients on cART, including the possible contribution of adaptive immune responses to HIV-associated neurocognitive disorders.

Immune reconstitution inflammatory syndrome in HIV-infected patients

Access to antiretroviral therapy (ART) is improving worldwide. Immune reconstitution inflammatory syndrome (IRIS) is a common complication of ART initiation. In this review, we provide an overview of clinical and epidemiological features of HIV-associated IRIS, current understanding of pathophysiological mechanisms, available therapy, and preventive strategies. The spectrum of HIV-associated IRIS is described, with a particular focus on three important pathogen-associated forms: tuberculosis-associated IRIS, cryptococcal IRIS, and Kaposi's sarcoma IRIS. While the clinical features and epidemiology are well described, there are major gaps in our understanding of pathophysiology and as a result therapeutic and preventative strategies are suboptimal. Timing of ART initiation is critical to reduce IRIS-associated morbidity. Improved understanding of the pathophysiology of IRIS will hopefully enable improved diagnostic modalities and better targeted treatments to be developed.

Treatment of immigrants and residents suffering from neuro-AIDS on a neurological intensive care unit: epidemiology and predictors of outcome

This study aimed at determining the clinical features and predictors for the outcome of patients with Neuro-Aids treated on a neurological intensive care unit (NICU) using retrospective analysis of all patients treated for Neuro-Aids in a tertiary Department of Neurology between 1996 and 2011. Chart review of the patients including the characteristics of intensive care was performed. As negative outcome, "death on the NICU or within 2 months following completion of NICU treatment" was defined. In total, 462 patients were identified of whom 87 were immigrants. 67 of all patients required NICU treatment (mean age 40.2 ± 0.8 years; 64% male). The median of the duration between diagnosis of HIV infection and the onset of treatment on NICU was 8 days for immigrants and 10 years for residents (p < 0.001). 34 of the patients on the NICU died due to severe neuromanifestations. Negative predictors for death were: (1) artificial ventilation; (2) antiretroviral-naïve immigrant; (3) primary cerebral lymphoma; (4) missing antiretroviral therapy upon admission to the NICU. Gender, age, ethnicity, CD4+ cell count, and viral load were no predictors of a negative outcome. The results indicated that the rate of death during treatment on a NICU is much higher as compared with treatment on an internal medicine ICU. A lot of research and effort will be necessary to improve this outcome especially for immigrants with Neuro-Aids.

CD8 encephalitis in HIV-infected patients receiving cART: a treatable entity

BACKGROUND

Despite its overall efficacy, combined antiretroviral therapy (cART) has failed to control human immunodeficiency virus (HIV) infection of the central nervous system (CNS). New acute and chronic neurological complications continue to be reported.

METHODS

We conducted a retrospective study of 14 HIV-infected patients with documented encephalitis, which was initially attributed to an undetermined origin. Brain magnetic resonance imaging (MRI) uniformly revealed unusual, multiple linear gadolinium-enhanced perivascular lesions.

RESULTS

All patients had manifested acute or subacute neurological symptoms; the brain MRIs indicating diffuse brain damage. The mean duration of HIV infection was approximately 10 years, and 8 patients were immunovirologically stable. Cerebrospinal fluid abnormalities with mildly elevated protein and pleocytosis with >90% lymphocytes, predominantly CD8, were found in all but 1 patient. The mean cerebral spinal fluid HIV load was 5949 copies/mL. Six patients reported a minor infection a few days prior to neurological symptoms, 2 patients presented criteria for the immune reconstitution inflammatory syndrome of the CNS, 2 were in virological escape, and 1 developed encephalitis after interruption of cART. Brain biopsies revealed inflammatory encephalitis associated with astrocytic and microglial activation as well as massive perivascular infiltration by polyclonal CD8(+) lymphocytes. All patients had been treated with glucocorticosteroids. The long-term therapeutic response varied from excellent, with no sequalae (n = 5), to moderate, with cognitive disorders (n = 4). The mean survival time was 8 years; however, 5 patients died within 13 months of initiation of treatment.

CONCLUSIONS

CD8 encephalitis in HIV-infected patients receiving cART is a clinical entity that should be added to the list of HIV complications.

Pathogenesis of the immune reconstitution inflammatory syndrome in HIV-infected patients

PURPOSE OF REVIEW

The immune reconstitution inflammatory syndrome (IRIS) is an important clinical complication in HIV-infected patients initiating antiretroviral therapy. This review focuses on the latest literature pertaining to the pathogenesis of IRIS.

RECENT FINDINGS

The clinical manifestations of IRIS are heterogeneous due to the variety of opportunistic infections that are associated with this inflammatory syndrome. However, the disproportionate inflammation is a defining hallmark for which common mechanisms are suspected. Lymphopenia-induced proliferation in the context of systemic immune activation, presence of high antigenic exposure and a wider availability of interleukin-7 contribute to the exacerbated immune response underlying IRIS. Defect in pathogen clearance by phagocytes might favor high pathogen burden, which in turn is thought to activate both innate immune cells and pathogen-specific T cells upon correction of the CD4 T-cell lymphopenia, predisposing to IRIS. This common scenario might be further invigorated by functional impairments among regulatory T cells.

SUMMARY

Further insight into the cellular mechanisms driving IRIS is urgently needed. Understanding the relative contribution of distinct effector and regulatory T-cell subsets, and innate immune components to IRIS is required to inspire future therapeutic approaches.