Unraveling neuroHIV in the Presence of Substance Use Disorders

This special issue contains 10 invited review papers that highlighted and extended the presentations at the NIDA-sponsored workshop "Unraveling NeuroAIDS in the Presence of Substance Use Disorders" at the 25th Society on NeuroImmune Pharmacology conference in 2019. The topics covered by these papers focused on the interactive, additive or synergistic effects of substance use disorders (SUD) with HIV infection on the immune system and on neuropathogenesis. These papers reviewed four categories of substances of abuse (opioids, tobacco, stimulants, and cannabis) and how comorbid HIV infection (including models with HIV proteins, HIV transgenic rodent models and SIV) might further impact the dysregulated dopaminergic and immune systems, and the subsequent neuropathogenesis and behavioral disorders known as HIV-associated neurological disorders (HAND). These reviews provided detailed background knowledge regarding how each of these addictive substances and HIV individually or collectively affected the immune system at the cellular, molecular and system levels, and the subsequent clinical and behavioral outcomes. The authors also identified gaps, confounds or constraints in the current disease models and approaches, and proposed future research directions.

NeuroAIDS in children

The human immunodeficiency virus-1 (HIV-1) enters the central nervous system compartment within the first few weeks of systemic HIV infection and may cause a spectrum of neurologic complications. Without combination antiretroviral therapy (cART), 50-90% of all HIV-infected infants and children develop some form of neuroAIDS. Of the estimated 2.3 million children less than 15 years of age who were living in sub-Saharan Africa at the end of 2014, only 30% were receiving cART, suggesting that there is a large burden of neuroAIDS among HIV-infected children in sub-Saharan Africa. There is complex interplay between the disease process itself, the child's immune reaction to the disease, the secondary complications, the side-effects of antiretroviral drugs, and inadequate antiretroviral drug uptake into the central nervous system. In addition there is the layering effect from the multiple socioeconomic challenges for children living in low- and middle-income countries. Adolescents may manifest with a range of neurocognitive sequelae from mild neurocognitive disorder through to severe neurocognitive impairment. Neuroimaging studies on white-matter tracts have identified dysfunction, especially in the frontostriatal networks needed for executive function. Psychiatric symptoms of depression, attention deficit hyperactivity disorder, and behavioral problems are also commonly reported in this age group. Antiretroviral drugs may cause treatment-limiting neurologic and neuropsychiatric adverse reactions. The following chapter addresses the neurologic complications known to be, and suspected of being, associated with HIV infection in children and adolescents.

HIV-1-associated neurocognitive disorder: epidemiology, pathogenesis, diagnosis, and treatment

The modern antiretroviral treatment of human immunodeficiency virus (HIV-1) infection has considerably lowered the incidence of opportunistic infections. With the exception of the most severe dementia manifestations, the incidence and prevalence of HIV-associated neurocognitive disorders (HAND) have not decreased, and HAND continues to be relevant in daily clinical practice. Now, HAND occurs in earlier stages of HIV infection, and the clinical course differs from that before the widespread use of combination antiretroviral treatment (cART). The predominant clinical feature is a subcortical dementia with deficits in the domains concentration, attention, and memory. Motor signs such as gait disturbance and impaired manual dexterity have become less prominent. Prior to the advent of cART, the cerebral dysfunction could at least partially be explained by the viral load and by virus-associated histopathological findings. In subjects where cART has led to undetectable or at least very low viral load, the pathogenic virus-brain interaction is less direct, and an array of poorly understood immunological and probably toxic phenomena are discussed. This paper gives an overview of the current concepts in the field of HAND and provides suggestions for the diagnostic and therapeutic management.

[Evaluation of an outpatient multidisciplinary Neuro-HIV clinic by the patients and referring doctors]

The neurocognitive complaints among HIV infected patients remain frequent, and to establish their etiology can be challenging. We created in 2011 an outpatient Neuro-HIV clinical platform that takes advantage of a multidisciplinary approach with 5 specialists (neuropsychologist, neurologist, psychiatrist, infectiologist and neuroradiologist). In order to estimate its utility, we conducted two questionnaire-based interviews by phone calls with the patients and their referring physicians. Three quarters of both the patients and the physicians interviewed consider the platform useful or essential. Even though there is often no immediate treatment for cognitive disorders, the patients receive from this multidisciplinary approach a better understanding of their disease, which may help them to better cope with their anxieties in daily life.

[HIV- DEMENTIA. A REVIEW THIRTY FIVE YEARS AFTER (1981-2015)]

In this review, the intention is to present the four clinical models of HIV-1-brain damage, named with the diffuse category of HIV-encephalopathy. It contains the past three decades, since the first static-infectological model of Snider WD, developed in 1983, based in a great neuropathological trial with AIDS patients. The second one, maybe the most compact of them, was the AIDS-dementia complex, published by the Navia BA group, in two notable papers published in 1986. This resulted in a consistent HIV-neuropsychiatric condition, till 1996, when HAART era begun. In a third early-HAART evolving model, we can find good correlations between the different levels: clinical (mild-moderate/severe forms), neuropsychological (subcortical pattern), neuroimaging, and LCR-markers. In the last-current paradigm, coincident with the advanced HAART treatments, the original HIV-encephalopathy became in a hybrid-complex compartimentalized condition, in contact with other neurodegenerative entities, like Alzheimer disease, Parkinson disease or the CNS-immune reconstitution inflammatory syndrome, with a high prevalence, atypical clinical forms, and with the demand of a specific management, in parallel to the systemic HIV disease.

CROI 2014: Neurologic complications of HIV infection

A shift in focus in the field of neuroHIV was clearly manifest at the 2014 Conference on Retroviruses and Opportunistic Infections (CROI), where a major emphasis was on the milder forms of neurologic morbidity, including cognitive impairment, seen in well-treated patients. Mechanisms of this persistent abnormality were investigated, including extensive analysis of the prevalence and associations of persistent HIV detection in cerebrospinal fluid (CSF) and characterization of persistent CNS immune activation. Another key emphasis was the early establishment of HIV replication and inflammation within the central nervous system (CNS) and the potentially salutary effect of very early HIV diagnosis and treatment in protecting the CNS from HIV-related injury. Mitochondrial function was identified as a potential mediator of a number of aspects of HIV-associated CNS dysfunction, including neurotoxicity associated with efavirenz, host genetic determinants of HIV-associated neurocognitive disorders (HAND), associations with direct measures of mitochondria in CSF, and metabolomic screening of CSF in HIV-infected subjects and those with HAND. Many studies employed laboratory rather than neuropsychologic end points, with a major focus on CSF biomarkers. Overall, neuroHIV presentations at CROI 2014 provided new insights into pathogenesis and treatment of the CNS, raising new challenges for researchers and practitioners aiming to optimize the status of the brain in people living with HIV infection.

Monocytes-derived macrophages mediated stable expression of human brain-derived neurotrophic factor, a novel therapeutic strategy for neuroAIDS

HIV-1 associated dementia remains a significant public health burden. Clinical and experimental research has shown that reduced levels of brain-derived neurotrophic factor (BDNF) may be a risk factor for neurological complications associated with HIV-1 infection. We are actively testing genetically modified macrophages for their possible use as the cell-based gene delivery vehicle for the central nervous system (CNS). It can be an advantage to use the natural homing/migratory properties of monocyte-derived macrophages to deliver potentially neuroprotective BDNF into the CNS, as a non-invasive manner. Lentiviral-mediated gene transfer of human (h)BDNF plasmid was constructed and characterized. Defective lentiviral stocks were generated by transient transfection of 293T cells with lentiviral transfer plasmid together with packaging and envelope plasmids. High titer lentiviral vector stocks were harvested and used to transduce human neuronal cell lines, primary cultures of human peripheral mononocyte-derived macrophages (hMDM) and murine myeloid monocyte-derived macrophages (mMDM). These transduced cells were tested for hBDNF expression, stability, and neuroprotective activity. The GenomeLab GeXP Genetic Analysis System was used to evaluate transduced cells for any adverse effects by assessing gene profiles of 24 reference genes. High titer vectors were prepared for efficient transduction of neuronal cell lines, hMDM, and mMDM. Stable secretion of high levels of hBDNF was detected in supernatants of transduced cells using western blot and ELISA. The conditioned media containing hBDNF were shown to be protective to neuronal and monocytic cell lines from TNF-α and HIV-1 Tat mediated cytotoxicity. Lentiviral vector-mediated gene transduction of hMDM and mMDM resulted in high-level, stable expression of the neuroprotective factorBDNF in vitro. These findings form the basis for future research on the potential use of BDNF as a novel therapy for neuroAIDS.

Mind Exchange Working Group. Assessment, diagnosis, and treatment of HIV-associated neurocognitive disorder: a consensus report of the mind exchange program

Many practical clinical questions regarding the management of human immunodeficiency virus (HIV)-associated neurocognitive disorder (HAND) remain unanswered. We sought to identify and develop practical answers to key clinical questions in HAND management. Sixty-six specialists from 30 countries provided input into the program, which was overseen by a steering committee. Fourteen questions were rated as being of greatest clinical importance. Answers were drafted by an expert group based on a comprehensive literature review. Sixty-three experts convened to determine consensus and level of evidence for the answers. Consensus was reached on all answers. For instance, good practice suggests that all HIV patients should be screened for HAND early in disease using standardized tools. Follow-up frequency depends on whether HAND is already present or whether clinical data suggest risk for developing HAND. Worsening neurocognitive impairment may trigger consideration of antiretroviral modification when other causes have been excluded. The Mind Exchange program provides practical guidance in the diagnosis, monitoring, and treatment of HAND.

Central nervous system complications of HIV infection

Issues relevant to the nervous system garnered substantial attention at the 18th Conference on Retroviruses and Opportunistic Infections. Several topics emerged as areas of importance both for informing current understanding of HIV-related neurologic disorders and their treatment, and for spurring future investigations. Measurable biomarkers of HIV-associated neurocognitive disorder (HAND) were a major theme, with studies ranging from new investigations of known laboratory and imaging markers to identification of novel molecules that might be investigated as potential means to follow disease activity as well as to better understand etiology of disease. Studies of pathogenesis of HAND and simian immunodeficiency virus-mediated neurologic injury added to prior understanding of lentivirus neuropathogenesis. Another broad area of investigation was the interplay between treatment with antiretroviral or adjunctive therapies and biomarkers of HAND. New data were presented on the potential importance of acute and early infection on the integrity of the central nervous system, complemented by studies of the effects of early treatment interventions.

Adjunctive therapies for AIDS dementia complex

BACKGROUND

AIDS dementia complex is a common complication of human immunodeficiency virus type 1 (HIV-1) that continues to exist despite the current use of potent antiretroviral therapy. It is a source of great morbidity and, when severe, is associated with limited survival.

OBJECTIVES

To determine efficacy and safety of adjunctive therapies for AIDS dementia complex

SEARCH STRATEGY

We searched the Cochrane HIV/AIDS group trials Specialized Register (December 2006), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2007), MEDLINE (January 1980 to February 2007), EMBASE (January 1980 to February 2007), AIDSearch (January 1980 to February 2007), PsycINFO (January 1980 to February 2007), PSYCHLIT (January 1980 to February 2007), LILACS (January 1980 to February 2007), conference proceedings, trial registers, theses databases, and reference lists of the articles. We also contacted manufacturers and researchers in the field.

SELECTION CRITERIA

Randomized controlled trials, either published or published, that compared one type of adjunctive therapy to no therapy or placebo in adults with AIDS dementia complex

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trials quality, extracted data and entered data into RevMan 4.2 software. Where possible intention-to-treat data were used and we contacted study authors for additional information. We collected neurocognitive performance, adverse effects, tolerability and all-cause mortality information from the trials.

MAIN RESULTS

Ten trials involving 711 people were included. All the studies were phase 2 trials. Six studies used adequate methods for allocation of sequence generation and unclear in the remaining four trials. Allocation concealment was adequate in five trials and unclear in the remaining trials. The trials were heterogeneous in terms of types, dosages, routes and frequencies of administration of the adjunctive therapies. There were no significant differences between the treated and placebo groups on neuropsychological test scores, number of those that complete the assign dosage of experimental medication, adverse effects, and all-cause mortality.

AUTHORS' CONCLUSIONS

This review confirms the absence of evidence that any of the adjunctive therapies improves cognitive performance or quality of life, or both for patients with ADC, though they were well tolerated and safe.

Communication impairment in the AIDS dementia complex (ADC): a case report

This article details three examinations of communication impairment over 13 months in a man with AIDS dementia complex (ADC) and compares his performance on standardised language testing with that of two control participants. He had mild language impairments as measured on standardised tests but was severely impaired in pragmatic language skills. When compared with control participants, he was particularly impaired in the skills of topic maintenance and informational redundancy and equally impaired as matched controls with AIDS on the items of non-specific vocabulary and excessive revisions. This man's communication impairment as a result of ADC, which was characterised by poor conversation skills in the absence of frank aphasia or dysarthria, may be related to non-linguistic cognitive impairment.

LEARNING OUTCOMES

Readers will be able to: (i) identify and recognise a general process of central nervous system changes and symptoms in ADC; (ii) recognise and describe changes in the language and communication skills in people with dementias resulting from diffuse neuropathology including in those with ADC; (iii) consider any changes in the communicative pragmatic style of people with ADC, in the light of hypothesising their possible links with cognitive changes in the executive functions of the brain e.g. attention and short term memory.

Updated research nosology for HIV-associated neurocognitive disorders

In 1991, the AIDS Task Force of the American Academy of Neurology published nomenclature and research case definitions to guide the diagnosis of neurologic manifestations of HIV-1 infection. Now, 16 years later, the National Institute of Mental Health and the National Institute of Neurological Diseases and Stroke have charged a working group to critically review the adequacy and utility of these definitional criteria and to identify aspects that require updating. This report represents a majority view, and unanimity was not reached on all points. It reviews our collective experience with HIV-associated neurocognitive disorders (HAND), particularly since the advent of highly active antiretroviral treatment, and their definitional criteria; discusses the impact of comorbidities; and suggests inclusion of the term asymptomatic neurocognitive impairment to categorize individuals with subclinical impairment. An algorithm is proposed to assist in standardized diagnostic classification of HAND.

CSF neurofilament protein (NFL) — a marker of active HIV-related neurodegeneration

BACKGROUND AND METHODS

The light subunit of the neurofilament protein (NFL), a major structural component of myelinated axons, is a sensitive indicator of axonal injury in the central nervous system (CNS) in a variety of neurodegenerative disorders. Cerebrospinal fluid (CSF) NFL concentrations were measured by ELISA (normal < 250 ng/l) in archived samples from 210 HIV-infected patients not taking antiretroviral treatment: 55 with AIDS dementia complex (ADC), 44 with various CNS opportunistic infections/tumours (CNS OIs), 95 without neurological symptoms or signs, and 16 with primary HIV infection (PHI). The effect of highly active antiretroviral treatment (HAART) was studied by repeated CSF sampling in four of the ADC patients initiating treatment.

RESULTS

CSF NFL concentrations were significantly higher in patients with ADC (median 2590 ng/l, IQR 780-7360) and CNS OIs (2315 ng/l, 985-7390 ng/l) than in neuroasymptomatic patients (<250 ng/l, <250-300) or PHI (<250 ng/l, <250-280), p < 0.001. Among patients with ADC, those with more severe disease (stage 2-4) had higher levels than those with milder disease (stage 0.5-1), p < 0.01. CSF NFL declined during HAART to the limit of detection in parallel with virological response and neurological improvement in ADC.CSF NFL concentrations were higher in neuroasymptomatic patients with lower CD4-cell strata than higher, p < 0.001. This increase was less marked than in the ADC patients and noted in 26/58 neuroasymptomatic patients with CD4 counts <200/microl compared to 1/37 with CD4-cells > or =200/microl.

CONCLUSIONS

The findings of this study support the value of CSF NFL as a useful marker of ongoing CNS damage in HIV infection. Markedly elevated CSF NFL concentrations in patients without CNS OIs are associated with ADC, follow the grade of severity, and decrease after initiation of effective antiretroviral treatment. Nearly all previously suggested CSF markers of ADC relate to immune activation or HIV viral load that do not directly indicate brain injury. By contrast NFL is a sensitive marker of such injury, and should prove useful in evaluating the presence and activity of ongoing CNS injury in HIV infection.

Challenges to the diagnosis and management of HIV dementia

Although it has been evident since the early days of the HIV epidemic that a dementing illness often accompanies HIV infection and that the virus invades the nervous system soon after systemic infection, the clinical syndrome has evolved with the introduction of antiretroviral therapy. Milder forms of cognitive impairment with a variable course, evident at higher CD4+ cell counts, are now more frequently seen. Furthermore, these patients often have other comorbidities such as drug abuse, hepatitis C virus infection, depression, and those associated with aging as confounding factors. The antiretroviral drugs may themselves be toxic or cause an immune reconstitution syndrome that needs to be distinguished from HIV dementia. The treating physician thus faces several new challenges in the diagnosis and treatment of a patient with HIV infection who presents with cognitive impairment. In this article, we provide a systematic approach to addressing each of these issues and guidelines for management of these patients. We also discuss the latest experimental approaches and the clinical trials being conducted for the better management of this population.

Mononuclear phagocytes in the pathogenesis of neurodegenerative diseases

Brain mononuclear phagocytes (MP, bone marrow monocyte-derived macrophages, perivascular macrophages, and microglia) function to protect the nervous system by acting as debris scavengers, killers of microbial pathogens, and regulators of immune responses. MP are activated by a variety of environmental cues and such inflammatory responses elicit cell injury and death in the nervous system. MP immunoregulatory responses include secretion of neurotoxic factors, mobilization of adaptive immunity, and cell chemotaxis. This incites tissue remodelling and blood-brain barrier dysfunction. As disease progresses, MP secretions engage neighboring cells in a vicious cycle of autocrine and paracrine amplification of inflammation leading to tissue injury and ultimately destruction. Such pathogenic processes tilt the balance between the relative production of neurotrophic and neurotoxic factors and to disease progression. The ultimate effects that brain MP play in disease revolves "principally" around their roles in neurodegeneration. Importantly, common functions of brain MP in neuroimmunity link highly divergent diseases (for example, human immunodeficiency virus type-one associated dementia, Alzheimer's disease and Parkinson's disease). Research into this process from our own laboratories and those of others seek to harness MP inflammatory processes with the intent of developing therapeutic interventions that block neurodegenerative processes and improve the quality of life in affected people.

Atteintes du système nerveux central et infection par le VIH-1

Central nervous system complications are common in HIV-1 infected patients and occur either as a result of concomitant immunosuppression (opportunistic infections, lymphoma and tumors), as a primary manifestation of HIV infection, or as an adverse effect of therapy (immune restoration and toxicity). These complications contribute largely to patient morbidity and mortality. In the era of highly active antiretroviral therapy (HAART) these disease states have changed in presentation, outcome and incidence. We review in detail the epidemiology, pathogenesis, clinical features, diagnosis, and management of these disorders.

[Neurological manifestations of HIV-infection in the era of highly active antiretroviral therapy (HAART)]

After the introduction of highly active antiretroviral therapy (HAART) in 1996 the neurological manifestations of human immunodeficiency virus (HIV-1)-infection did not decline in incidence and prevalence like the other complications of immunodeficiency; in contrast, due to the longer survival times of HAART treated HIV-1-positive individuals, prevalence of virus associated neurological disease increased during the last years, as international studies underline. Therefore, clinicians and HIV-therapists should be able to diagnose HIV-1-associated neurological disease even in early stages. This article describes symptoms and signs, neuro-imaging and cerebrospinal fluid findings as well as therapy options in primary HIV-1-associated neurological disease like encephalo- and myelopathy and polyneuropathy. Furthermore, those opportunistic infections, caused by bacteria, viruses other than HIV and parasites emerging with manifest immunodeficiency and remaining to be relevant in the HAART era are presented from diagnostic, differential-diagnostic and therapeutic points of view. An extra paragraph describes the interaction of HAART with neurological/psychiatric standard therapies.

Experimental and potential future therapeutic approaches for HIV-1 associated dementia targeting receptors for chemokines, glutamate and erythropoietin

Severe and debilitating neurological problems that include behavioral abnormalities, motor dysfunction and frank dementia can occur after infection with the human immunodeficiency virus-1 (HIV-1). Infected peripheral immune-competent cells, in particular macrophages, infiltrate the central nervous system (CNS) and provoke a neuropathological response involving all cell types in the brain. HIV-1 infection results in activation of chemokine receptors, inflammatory mediators, extracellular matrix-degrading enzymes and glutamate receptor-mediated excitotoxicity, all of which can trigger numerous downstream signaling pathways that result in disruption of neuronal and glial function. Despite many major improvements in the control of viral infection in the periphery, a truly effective therapy for HIV-1 associated dementia is currently not available. This review will discuss experimental and potentially future therapeutic strategies based on recently uncovered pathologic mechanisms contributing to neuronal damage induced by HIV-1.

The AIDS dementia complex: clinical and basic neuroscience with implications for novel molecular therapies

The AIDS dementia complex (ADC, also referred to as HIV-associated cognitive impairment) is a common disorder among HIV-infected patients associated with both inflammatory and neurodegenerative processes. This review describes recent advances in the clinical and basic neurosciences of HIV infection and discusses the multivariable nature of what has become a chronic disorder in the context of highly active antiretroviral therapies (HAART). Since its initial description twenty years ago, advances in cell and molecular biology along with those in neuroimaging have furthered our understanding of the underlying pathogenic mechanisms. The clinical and neuropsychological profile of ADC is generally consistent with a "frontal-subcortical" pattern of injury. Neuropathogenesis is largely driven by indirect mechanisms mediated by infected, or more commonly, immune activated macrophages, which secrete viral and host-derived factors. Magnetic resonance spectroscopy (MRS) provides a robust in vivo method to measure the inflammatory and neurotoxic events triggered by these factors and their associated signals. Although the use of combined or highly active antiretroviral therapies (HAART) has significantly improved survival rates, cerebral injury and cognitive impairment remain common events. Factors such as aging and chronic infection will likely impact the course of this disease, its pathogenesis, and treatment. The combined observations presented in this review suggest a number of critical areas for future inquiry.

Efficacy of proton magnetic resonance spectroscopy in neurological diagnosis and neurotherapeutic decision making

Anatomic and functional neuroimaging with magnetic resonance imaging (MRI) includes the technology more widely known as magnetic resonance spectroscopy (MRS). Now a routine automated "add-on" to all clinical magnetic resonance scanners, MRS, which assays regional neurochemical health and disease, is therefore the most accessible diagnostic tool for clinical management of neurometabolic disorders. Furthermore, the noninvasive nature of this technique makes it an ideal tool for therapeutic monitoring of disease and neurotherapeutic decision making. Among the more than 100 brain disorders that fall within this broad category, MRS contributes decisively to clinical decision making in a smaller but growing number. In this review, we will cover how MRS provides therapeutic impact in brain tumors, metabolic disorders such as adrenoleukodystrophy and Canavan's disease, Alzheimer's disease, hypoxia, secondary to trauma or ischemia, human immunodeficiency virus dementia and lesions, as well as systemic disease such as hepatic and renal failure. Together, these eight indications for MRS apply to a majority of all cases seen. This review, which examines the role of MRS in enhancing routine neurological practice and treatment concludes: 1) there is added value from MRS where MRI is positive; 2) there is unique decision-making information in MRS when MRI is negative; and 3) MRS usefully informs decision making in neurotherapeutics. Additional efficacy studies could extend the range of this capability.

HIV dementia: an evolving disease

Several advances have led to improvements in the care and prognosis of HIV+ individuals. The first is an understanding of the direct relationship between HIV replication and subsequent immunological and clinical progression, reinforcing the need to completely suppress HIV replication to control disease progression. The second is the wider availability of HAART which can provide effective suppression of HIV. The third major change is the ability to monitor HAART through the reliable and widespread measurement of plasma HIV RNA levels, which has become a routine part of clinical care. Since the introduction of highly active antiretroviral therapy (HAART) in the 1990s, there have been significant declines in the incidence rates of opportunistic infections in developed countries. HAART has clearly improved survival for individuals with HIV/AIDS, and has reduced the incidence of HIV-associated dementia (HIV-D) by 40-50% (Brodt et al., 2002). The prevalence of sensory neuropathies in advanced HIV/AIDS now exceeds 20% (Schifitto et al., 2002), and may rise further with prolonged exposure to neurotoxic HAART. HIV-D and HIV-related sensory neuropathies (HIV-SN) have a combined prevalence of about 30-50% in advanced HIV disease, suggesting that HAART does not provide complete protection against neurological damage (Bouwman et al., 1998). HIV-associated dementia (HIV-D) remains a common cause of dementia worldwide, and with HIV-related sensory neuropathies (HIV-SN) represents the commonest neurological disorders associated with AIDS. Furthermore, the temporal progression of HIV-D appears to have been altered by HAART, with most patients now showing an attenuated form of dementia, which with treatment is slowly progressive or static (Dougherty et al., 2002). This overview will review some of the outstanding questions relating to HIV-dementia, including: (a) are there differing phenotypes or temporal patterns of progression in HIV-dementia? (b) what determines these temporal patterns? and (c), what has been the impact of therapy on HIV dementia?

Age, apolipoprotein E4, and the risk of HIV dementia: the Hawaii Aging with HIV Cohort

There are discrepant findings regarding the risk of HIV-associated dementia (HAD) relating to apolipoprotein E4, suggesting other factors may modulate risk. Furthermore, evidence suggests a changing phenotype of HAD in the era of highly active antiretroviral therapy (HAART), prompting a need to determine if new disease markers have emerged. In this analysis, APOE genotype was determined for 182 participants enrolled in the Hawaii Aging with HIV Cohort. After controlling for age and diabetes status, an independent risk of HAD relating to E4 was seen in older participants [OR=2.898 (1.031-8.244)] but not in younger participants [OR=0.373 (0.054-1.581)]. Several proposed mechanisms may underlie this association. Consideration of non-traditional risk factors for HAD in older HIV patients may yield new markers of disease in the era of HAART.

RNA interference:a potential novel therapeutic combating HIV-1 in the central nervous system

RNA interference (RNAi)is a conserved process by which eukaryotic cells protect their genomes utilizing small, double-stranded RNAs to degrade target RNAs. This occurs in a sequence-specific manner and is different from the interferon effect of larger double stranded RNAs. Post-transcriptional gene silencing by these nucleic acids can lead to degradation of either cellular or viral RNAs. It has been recently shown that double stranded, small interfering RNAs (siRNAs)of 21 to 25 nucleotides can be transfected into relevant cells to target specific RNAs. In addition, utilizing hairpin motifs, siRNAs can be expressed intracellularly using molecular therapeutic vectors. This potent approach has been utilized to both inhibit pathogens, including viruses, as well as to dissect cellular molecular mechanisms via a potent knockout effect. At this time in the HIV-1-pandemic,one of the remaining, most enigmatic, and still vitally important areas of HIV-1 pathogenesis occurs in the central nervous system (CNS).HIV-1-induced encephalopathy remains difficult to treat in the developing world and in parts of the developed world, even in the era of highly active anti-retroviral therapy. As such, novel approaches which could lead to intracellular immunization, and life-long resistance against HIV-1 encephalopathy would be of important impact worldwide. Thus, we now seek to combine our background in molecular therapeutics and RNAi with our long-standing interest in HIV-1 neuropathogenesis to target the CNS using siRNAs.

Murine models for human immunodeficiency virus type 1-associated dementia: the development of new treatment testing paradigms

The neuroimmune events leading to human immunodeficiency virus (HIV)-1-associated dementia (HAD) are linked to macrophage secretory neurotoxins (cellular and viral toxins). To study such events, we developed a murine model of HIV-1 encephalitis (HIVE), the pathological equivalent of HAD. Severe combined immunodeficient (SCID) mice injected with HIV-1-infected monocyte-derived macrophages (MDMs) into basal ganglia exhibited many of the pathological features of human HIVE. Moreover, behavioral and cognitive abnormalities in the HIVE mice were associated with neuronal dysfunction and decreased synaptic density. Thus, the rationale for testing novel therapeutic approaches (anti-inflammatory, antiretroviral, or neuroprotective) in the HIVE SCID mice is clear. Animals treated with anti-inflammatory compounds (platelet-activating factor [PAF] antagonist and tumor necrosis factor [TNF]-alpha release inhibitor) showed a marked reduction in brain inflammation and a reduction in neuronal injury. Comparative analyses of highly active antiretroviral therapy (HAART) regimens provided direction for which one might be most efficient for reduction of viral load in infected brain tissue. Moreover, modifications of the HIVE model might serve as a vehicle for testing vaccine approaches. Reconstitution of immunodeficient animals with syngeneic T lymphocytes followed by injection of HIV-1-infected MDMs in the brain resulted in cytotoxic antivirus T lymphocyte (CTL) response. CD8-positive T cells migrated to the sites of human MDMs, leading to the cell-mediated destruction of HIV-1 infected MDMs. These results, taken together, strongly support the use of HIVE SCID mouse model as a novel system for studies of the neuropathogenesis of HIV-1 infection, as well as for testing novel therapeutic and vaccine interventions for human disease.

HIV-infected prisoners: what mental health services are constitutionally mandated?

State and federal correctional facilities currently have approximately 23,000 inmates who are infected with human immunodeficiency virus (HIV). These inmates suffer from the same mental health disorders as uninfected inmates but are additionally subject to mental health problems uniquely related to their HIV infection. Many prison systems are struggling to provide minimal mental health care to uninfected inmates. How will prisoners address the additional mental health needs of the staggering number of inmates being diagnosed with AIDS and HIV? This article describes the type of mental health services that are constitutionally mandated and discusses whether and how prisons will have to respond to the distinct mental health issues related to HIV infection.

Understanding pathogenesis and treatment of HIV dementia: a role for magnetic resonance?

HIV dementia (HIVD) is among the most common and most feared neurological complications of AIDS. In vitro studies have identified a constellation of potentially neurotoxic inflammatory and non-inflammatory pathways, one or more of which could underlie HIVD. Magnetic resonance spectroscopy (MRS) and magnetic resonance imaging (MRI) studies can distinguish between inflammatory and non-inflammatory pathways in vivo and suggest that either or both might be active in different patients or at different times in the same patient. This could perhaps explain the variability in HIVD development, progression and response to therapy. These findings also suggest that MRI and MRS can identify patients at risk for HIVD and predict response to therapy.

HIV-1 associated encephalopathy and myelopathy

HIV-1-associated encephalopathy (HIVE) remains an important manifestation of advanced HIV infection despite recent advances in antiretroviral therapy. Special pharmacological and virological conditions predominate in the central nervous system (CNS). HIVE is characterized by "subcortical" dementia which becomes manifest as psychomotors lowing as well as memory and concentration deficits. Deficits of central motor function are an invariable finding. Enhanced viral replication in immunocompetent CNS cells is believed to be the pathogenic basis of CNS disease. This process leads to neurotoxic effects elicited directly by viral products as well as indirectly by the immune response to the virus. HIV-1 associated myelopathy (HIVM) is the other CNS manifestion of advanced HIV-1 infection. The present consensus paper recommends diagnostic and therapeutic procedures in HIVE and HIVM and outlines the state of current research.

HIV-1-associated dementia: a basic science and clinical perspective

HIV-1 associated dementia (HAD) is a metabolic encephalopathy induced by viral infection and fueled by immune activation of brain mononuclear phagocytes (perivascular and parenchymal macrophages and microglia). These same cells serve as reservoirs for persistent infection and sources for soluble neurotoxins. Neurologic impairments are manifested by cognitive, behavioral, and motor abnormalities that occur years after viral exposure and are associated with depletion of CD4+ T lymphocytes and high viral loads. Improvements in antiretroviral and adjunctive therapies have decreased HAD incidence, but cognitive dysfunction remains a cause of morbidity in many infected persons.

Analyses of nursing home residents with HIV and dementia using the minimum data set

OBJECTIVE

The objective of this paper is to profile nursing home residents with HIV who also have dementia at the time of admission, using the Minimum Data Set (MDS). In addition, this paper compares HIV residents with dementia with other residents with HIV. These resident profiles contain sociodemographic characteristics, health status measures, treatments, and procedures.

STUDY SUBJECTS

There are 1,074 admission assessments for HIV residents with dementia and 4,040 admission assessments for other residents with HIV in the MDS between June 22, 1998 and January 17, 2000; these were analyzed for this study.

RESULTS

Other residents with HIV were twice as likely to be physically independent as HIV residents with dementia. Only 1 of 5 HIV residents with dementia was independent in cognitive skills for daily decision making compared with 3 of 5 other residents with HIV who were independent in these skills. Significantly greater percentages of HIV residents with dementia also had anemia, depression, schizophrenia, cognitive and memory problems, hepatitis, renal failure, and cancer than other residents with HIV.

CONCLUSIONS

These analyses demonstrate that HIV residents with dementia were significantly more likely to have other diseases, infections, and health care conditions than other residents with HIV.

"Mental" issue threatens medical care

Restrictions on "psychiatric" care mean that many patients with organic brain disease cannot be treated in the hospital wards equipped to manage the behavioral problems which may result from the illness.

[Acute psychiatric symptoms as the initial manifestation of HIV-infection: differential diagnosis, therapy and medico-legal issues]

The prevalence of psychiatric symptoms and disorders in HIV-infected patients is high. The differential diagnosis includes psychoreactive disorders, acute psychiatric symptoms of an HIV-associated encephalopathy, and symptomatic psychotic illnesses due to secondary neurologic manifestations such as opportunistic central nervous infections and intracerebral lymphoma. Clinical aspects and psychopathological findings are not sufficient for differential diagnosis and identification of primarily psychiatric disorders. Secondary neurologic manifestations causing a symptomatic psychosis must be excluded as soon as possible by brain imaging (CT, MRI) and analysis of the cerebrospinal fluid. In emergency situations, however, German law imposes strict regulations, especially in the case of sectioned patients. These medical and medicolegal questions are illustrated by case reports and propositions for an effective strategy are made.

[Neurological complications of HIV infection. Review: new diagnostic, therapeutic and prognostic aspects]

About one third of patients with HIV infection show neurological complications with considerable morbidity and high mortality. This is an actualized review of the most important neurological manifestations resulting from primary HIV infection, from secondary opportunistic infections, or as complications of antiretroviral therapy. The primary neurological manifestations, including HIV-associated dementia complex, myelopathies, peripheral neuropathies and myopathies, the more common opportunistic infections, primary central nervous system lymphoma and cerebrovascular diseases, are discussed in the light of new evidence in diagnosis, therapy and prognosis. Cognitive and psychiatric symptoms, visual changes, headache, seizures, dizziness, involuntary movements, gait disturbances, cranial neuropathies and focal deficits are the common neurological symptoms in HIV infection which are described under the aspect of differential diagnosis. It is important to bear in mind that nearly all information available to date on this subject concerns HIV patients in the period before combination therapies (including protease inhibitors). The introduction of highly active antiretroviral therapy (HAART) with protease inhibitors in 1995, and non-nucleoside reverse transcriptase inhibitors, have opened up new therapeutic modalities with a new emphasis on earlier detection and treatment of neurological complications. The prognosis of different HIV-associated neurological diseases has considerably improved, as recently shown in the case, for example, of progressive multifocal leucoencephalopathy.

Frontiers in care: a case of compulsory treatment in AIDS dementia. Case study and commentaries

A patient with AIDS dementia was confronted and compulsorily prevented from flying out of the country before being admitted against his will to hospital. While finding this on balance justified in the circumstances the commentators raise moral questions about the levels of care in general practice and within the couple's own relationships.

Anti-human immunodeficiency virus type 1 gene therapy in human central nervous system-based cells: an initial approach against a potential viral reservoir

Studies have demonstrated that human immunodeficiency virus type 1 (HIV-1) infection of central nervous system (CNS)-based cells in vivo results in a series of devastating clinical conditions collectively termed acquired immune deficiency syndrome (AIDS) dementia complex (ADC). Gene therapy for these neurovirological disorders necessitates utilization of a vector system that can mediate in vivo delivery and long-term expression of an antiretroviral transgene in nondividing/postmitotic CNS cellular elements. The present studies focus on the transfer of an anti-HIV-1 gene to primary isolated CNS microvascular endothelial cells (MVECs) and neuronal-based cells, for its effects in protecting these cells from HIV-1 infection. By using an HIV-1-based vector system, it was possible to efficiently transduce and maintain expression of a marker transgene, beta-galactosidase (beta-Gal), in human CNS MVECs, human fetal astrocytes, plus immature and mature (differentiated) NT2 cells. Significant transduction of the marker gene, beta-Gal, in CNS-based cells prompted the utilization of this system with an anti-HIV-1 gene therapeutic construct, RevM10, a trans-dominant negative mutant Rev protein. Initially, it was not possible to generate any HIV-1 vector particles with the RevM10 gene in the transducing construct, because of inhibitory effects on the HIV-1 vector by this gene product. However, the vector could be partially rescued by adding an additional construct that supplied wild-type rev, in trans, during a multiple construct transfection in the packaging 293T cells. Thus, it was possible to significantly improve the titer of RevM10-expressing viral particles generated from these cells. Moreover, this RevM10 vector transduced the neuronal precursor cell line NT2, retinoic acid-differentiated human neurons (hNT) from the precursor cells, and primary isolated human brain MVECs with high efficiency. RevM10 generated from the HIV-1-based vector system potently inhibited replication of diverse HIV-1 strains in human CNS MVECs and neuronal cells. The data generated from these studies represent an initial approach for future development of anti-HIV-1 gene therapy in the CNS.

Neurocognitive disorders seen in HIV disease

Despite dramatic improvements in the therapeutic management of clients with human immunodeficiency virus (HIV) disease, cognitive disorders still appear as clinical manifestations of the illness trajectory. The development of neuro-cognitive impairment is associated with high levels of HIV activity and the resultant severe degree of immunosuppression. Although many clinicians almost exclusively associate HIV-related cognitive dysfunction with HIV encephalopathy and dementia, the etiologic conditions are numerous and include not only HIV infection affecting the brain, but also infections and neoplasms, as well as adverse effects of prescribed therapies. Treatment strategies include pharmacologic interventions, alternative and complementary therapies, and milieu management.

[Inflammatory and infectious manifestations of the nervous system]

The Central Nervous System is the site of a wide variety of inflammatory and infectious diseases. Some disease entities have been in the focus of interest in recent years and progress has been achieved in our understanding of some chosen domains. We will review recent progress in our knowledge about transmissible spongiformes encephalopathies and AIDS-associated lesions, and briefly discuss cerebral vasculitis, granulomatous diseases and the most frequent infections by parasites.