Deregulation of microRNAs by HIV-1 Vpr protein leads to the development of neurocognitive disorders

Studies have shown that HIV-infected patients develop neurocognitive disorders characterized by neuronal dysfunction. The lack of productive infection of neurons by HIV suggests that viral and cellular proteins, with neurotoxic activities, released from HIV-1-infected target cells can cause this neuronal deregulation. The viral protein R (Vpr), a protein encoded by HIV-1, has been shown to alter the expression of various important cytokines and inflammatory proteins in infected and uninfected cells; however the mechanisms involved remain unclear. Using a human neuronal cell line, we found that Vpr can be taken up by neurons causing: (i) deregulation of calcium homeostasis, (ii) endoplasmic reticulum-calcium release, (iii) activation of the oxidative stress pathway, (iv) mitochondrial dysfunction and v- synaptic retraction. In search for the cellular factors involved, we performed microRNAs and gene array assays using human neurons (primary cultures or cell line, SH-SY5Y) that we treated with recombinant Vpr proteins. Interestingly, Vpr deregulates the levels of several microRNAs (e.g. miR-34a) and their target genes (e.g. CREB), which could lead to neuronal dysfunctions. Therefore, we conclude that Vpr plays a major role in neuronal dysfunction through deregulating microRNAs and their target genes, a phenomenon that could lead to the development of neurocognitive disorders.

HIV-1 reduces Abeta-degrading enzymatic activities in primary human mononuclear phagocytes

The advent and wide introduction of antiretroviral therapy has greatly improved the survival and longevity of HIV-infected patients. Unfortunately, despite antiretroviral therapy treatment, these patients are still afflicted with many complications including cognitive dysfunction. There is a growing body of reports indicating accelerated deposition of amyloid plaques, which are composed of amyloid-β peptide (Aβ), in HIV-infected brains, though how HIV viral infection precipitates Aβ accumulation is poorly understood. It is suggested that viral infection leads to increased production and impaired degradation of Aβ. Mononuclear phagocytes (macrophages and microglia) that are productively infected by HIV in brains play a pivotal role in Aβ degradation through the expression and execution of two endopeptidases, neprilysin (NEP) and insulin-degrading enzyme. In this study, we report that NEP has the dominant endopeptidase activity toward Aβ in macrophages. Further, we demonstrate that monomeric Aβ degradation by primary cultured macrophages and microglia was significantly impaired by HIV infection. This was accompanied with great reduction of NEP endopeptidase activity, which might be due to the diminished transport of NEP to the cell surface and intracellular accumulation at the endoplasmic reticulum and lysosomes. Therefore, these data suggest that malfunction of NEP in infected macrophages may contribute to acceleration of β amyloidosis in HIV-inflicted brains, and modulation of macrophages may be a potential preventative target of Aβ-related cognitive disorders in HIV-affected patients.

Protein changes in CSF of HIV-infected patients: evidence for loss of neuroprotection

To begin to unravel the complexity of HIV-associated changes in the brain, broader, multifaceted analyses of cerebrospinal fluid (CSF) are needed that examine a wide range of proteins reflecting different functions. To provide the first broad profiles of protein changes in the CSF of HIV-infected patients, we used antibody arrays to measure 120 cytokines, chemokines, growth factors, and other proteins. CSF from HIV-infected patients with a range of cognitive deficits was compared to CSF from uninfected, cognitively normal patients to begin to identify protein changes associated with HIV infection and neurological disease progression. Uninfected patients showed relatively consistent patterns of protein expression. Highly expressed proteins in CSF included monocyte chemotactic protein-1, tissue inhibitors of metalloproteases, granulocyte colony-stimulating factor, adiponectin, soluble tumor necrosis factor receptor-1, urokinase-type plasminogen activator receptor, and insulin-like growth factor binding protein-2. Inflammatory and anti-inflammatory cytokines were expressed at low levels. HIV-infected patients showed increases in inflammatory proteins (interferon-gamma, tumor necrosis factor-alpha), anti-inflammatory proteins (IL-13), and chemokines but these correlated poorly with neurological status. The strongest correlation with increasing severity of neurological disease was a decline in growth factors, particularly, brain-derived neurotrophic factor and NT-3. These studies illustrate that HIV infection is associated with parallel changes in both inflammatory and neuroprotective proteins in the CSF. The inverse relationship between growth factors and neurological disease severity suggests that a loss of growth factor neuroprotection may contribute to the development of neural damage and may provide useful markers of disease progression.

Plasma cytokine concentrations associated with HIV/hepatitis C coinfection are related to attention, executive and psychomotor functioning

Cytokine disturbances have been linked to brain dysfunction among HIV-infected people. Past studies have not simultaneously examined a large set of cytokine measures and their relationships to HIV-associated neurocognitive deficits. We hypothesized that performance on measures of attention and executive and psychomotor functions would be associated with plasma cytokine concentrations in HIV-infected individuals. Plasma samples drawn from 30 HIV-infected and 37 HIV seronegative individuals were analyzed via xMAP multiplexed bead array immunoassay to determine concentrations of 13 cytokines. Performance on Trail Making A/B, Stroop Test, Letter-Number Sequencing, Digit Symbol Coding, Symbol Search, and Grooved Pegboard tests was assessed. Statistical analyses were performed to examine group differences in cytokine concentrations, and associations between cytokine and HIV clinical variables and neurocognitive performance. Significant HIV effects were found on 7 of the 13 cytokines, primarily with respect to interleukins. HIV clinical factors (CD4 and HIV RNA levels, duration of illness, antiretroviral treatment) and hepatitis C status were associated with specific plasma cytokine concentrations. Neurocognitive measures were associated with cytokine concentrations, most consistently among the interleukins and IP-10. Generally, cytokine concentrations were among the strongest predictors of neurocognitive function relative to other clinical factors, which reinforces their potential importance in examining the neuropathological processes of HIV. The findings also point to the potential value of simultaneously examining a panel of biomarkers. The current results suggest that a complex relationship likely exists among cytokines [how?] and that these relationships are mediated not only by HIV infection but also by antiretroviral treatment and other comorbid conditions.

Human immunodeficiency virus infection in the CNS and decreased dopamine availability: relationship with neuropsychological performance

Human immunodeficiency virus (HIV-1) infection in the central nervous system (CNS) is associated with a wide range of neurological, cognitive, and behavioral problems. HIV-1 enters the brain soon after the initial infection and is distributed in varying concentrations in different regions with specific affinity to the subcortical regions, particularly the basal ganglia, causing neurodegeneration of dopaminergic regions and resulting in the decreased availability of dopamine (DA) in the CNS. Although there are numerous reports on HIV-1-associated neuropsychological (NP) impairment, there is a paucity of studies showing a direct relationship between the decreased availability of dopamine in different regions of postmortem brains of HIV-1-infected individuals and the level of performance in different NP functions during life. Dopamine is the key neurotransmitter in the brain and plays a regulatory role for motor and limbic functions. The purpose of the present study was to investigate the relationship between the decreased availability of dopamine found in the postmortem brain regions (fronto-cortical regions, basal ganglia, caudate, putamen, globus pallidus, and substantia nigra) of individuals with HIV/AIDS and the antemortem level of performance (assessed as T scores) in different NP functions. The relationship between HIV-1 RNA levels in different brain regions and the level of performance in different NP domains was also investigated. We found that although DA concentrations were 2-53% lower in the brain regions of HIV-1-infected, HAART-treated individuals, compared with HIV-negative controls, a 45% decrease in DA levels in the substantia nigra (SN) of HIV-1-infected individuals was significantly correlated with the low level of performance (T scores) in the speed of information processing, learning, memory, verbal fluency, and average T scores across domains. In case of homovanillic acid (HVA), the variable changes in different regions, including the substantia nigra, basal ganglia, caudate, and putamen (compared to that in the HIV-negative individuals), were significantly correlated with the level of performance (T scores) in motor functions, speed of information processing, and attention/working memory. HIVRNA levels in the frontal cortex, caudate, and GP were significantly inversely correlated with abstract/executive function, motor, learning, verbal fluency, and attention/working memory. No significant correlations were found between HIVRNA in other brain regions and NP performance. These findings suggest that the decreased availability of dopamine in the SN (the main site of DA synthesis in the CNS), and changes in the levels of HVA in different brain regions are, in part, related with the lower level of performance in some of the NP functions in individuals with HIV/AIDS.

Disturbance in cerebral spinal fluid sphingolipid content is associated with memory impairment in subjects infected with the human immunodeficiency virus

Despite widespread use of antiretroviral therapies to control replication of the human immunodeficiency virus (HIV), dysfunctions of cognition that are collectively termed HIV-associated neurocognitive disorders (HAND) still occur in approximately 50% of those infected by the virus. Currently there is not a biomarker that can identify HIV-infected people who are at risk for the development of HAND. Previous studies have identified particular sphingolipid species that are dysregulated in HAND, but the neurocognitive correlates of these biochemical findings are not currently understood. To address this question, we compared cerebrospinal fluid (CSF) levels of sphingomyelin, ceramide, and sterol species with performance on standard neurological tests designed to assess the function of multiple cognitive and motor domains in HIV-infected subjects. We found that sphingomyelin:ceramide ratios for acyl chain lengths of C16:0, C18:0, C22:0, and C24:0 were associated with worse performance on several indices of memory. The most striking finding was for the acyl chain of C18:0 that consistently associated with performance on multiple tests of memory. These findings suggest that the sphingomyelin:ceramide ratio for C18:0 may be a reasonable surrogate marker for memory dysfunction in HIV-infected subjects.

Rebuilding synaptic architecture in HIV-1 associated neurocognitive disease: a therapeutic strategy based on modulation of mixed lineage kinase

Work from our laboratories has validated mixed lineage kinase type 3 (MLK3) as an enzyme pathologically activated in the CNS by human immunodeficiency virus 1 (HIV-1) neurotoxins. In this review, we discuss MLK3 activation in the context of the neuropathogenesis of HIV-1 associated neurocognitive deficits (HAND). We use findings from the literature to substantiate the neuropathologic relevance of MLK3 to neurodegenerative disease, with an emphasis on Parkinson's disease that shares a number of important phenotypic and neuropathologic characteristics with HAND. We discuss signal transduction pathways downstream from MLK3 activation, with an emphasis on their involvement in microglia and neurons in preclinical models of HAND. Finally, we make a case for pharmacologic intervention targeted at inhibition of MLK3 as a strategy to reverse HAND, in light of the fact that combination antiretroviral therapy, despite successfully managing systemic infection of HIV-1, has been largely unsuccessful in eradicating HAND.

Implications of positive and negative neuroplasticity on cognition in HIV

HIV cognitive impairments are a common occurrence. Although some of the etiologies of such cognitive impairments are understood, some of the causes are not always straightforward because adults with HIV represent a very heterogenous population. Unfortunately, many of the studies that investigate cognition in this population rely on convenience samples of HIV-positive adults who may lack cognitive stimulation due to poor education or unemployment, both of which can promote negative neuroplasticity. By the same token, other adults with HIV may be cognitively stimulated by their work, educational pursuits, and intellectual interests which may promote positive neuroplasticity which may be protective against cognitive impairments. Implications for how this impacts research as well as prevention and intervention of cognitive impairments are posited.

[Impaired cognitive function in hepatitis C virus infection]

Impaired cognitive function is commonly seen in patients with hepatitis C-virus (HCV). This might be due to a toxic effect of the virus itself or to neuroinflammatory processes with a direct damaging cerebral effect. The symptoms appear in the pre-cirrhotic stage and impair the patient's level of functioning. Therefore, doctors in contact with HCV patients should be up to date on the existing knowledge in the field to be able to inform patients about their cognitive deficits and take them into consideration. It is unknown if the cognitive deficits decline when the virus is eradicated.

Immune dysfunction, inflammation, and accelerated aging in patients on antiretroviral therapy

Patients receiving long-term antiretroviral therapy are at increased risk of age-associated non-AIDS-related morbidity and mortality compared with HIV-seronegative persons. Despite suppressive antiretroviral treatment, inflammation remains elevated and CD4+ count often remains low, with both measures predicting age-associated events. Several factors likely contribute to persistent inflammation and suboptimal gains during therapy. These include residual HIV replication, persistent virus expression, loss of immunoregulatory cells, collagen deposition, microbial translocation, chronic coinfections, and thymic dysfunction. How these factors influence disease outcomes and how chronic inflammation should be managed during therapy are the focus of intense ongoing investigation. Currently, the most practical advice is to start antiretroviral therapy early and to manage traditional risk factors for non-AIDS-related conditions aggressively. This article summarizes a presentation made by Steven G. Deeks, MD, at the International AIDS Society-USA continuing medical education program in Chicago in May 2009.

[Acute disseminated encephalomyelitis in childhood]

BACKGROUND AND PURPOSE

Acute disseminated encephalomyelitis is a rare inflammatory demyelinating disorder often preceded by infection or vaccination. The purpose of the study was the systematic analysis of clinical, radiological and microbiological profiles of children treated at Szent László Hospital, and the comparison of findings with literature data.

METHODS

Demographic, infectological, clinical, radiological, laboratory and virological data of patients treated and followed-up between 1-Jan-1998 and 30-June-2008 were reviewed and analysed.

RESULTS

19 children met diagnostic criteria. Their mean age was 6.8 years. A prodromal illness--mostly febrile viral infection, upper respiratory infection or chickenpox--preceded neurological symptoms in 17 patients. All had polysymptomatic encephalopathy, 2 children had spinal symptoms. The cerebrospinal fluid was abnormal in all but one. A viral etiology was definite in 7 and probable in 8 cases. MRI disclosed white matter changes in 18, cortical and deep gray matter in 16, cerebellar in 6, brain stem in 14 and spinal cord changes in 2 cases. Repeat MRI performed mean 4 months later showed complete resolution in 6 and partial resolution in 11 patients. 13 patients received high-dose methylprednisolone, 2 of whom were also treated with plasma exchange and 1 with immunoglobulin. 9 children required mechanical ventilation. 2 patients died, 10 recovered without and 7 with sequelae. 2 patients developed further demyelinating events: multiple sclerosis and multiphasic disseminated encephalomyelitis, respectively.

CONCLUSION

Clinical, radiological and follow-up results were similar to those published in literature however, triggering viruses were identified in a larger proportion of cases.

Neurologic complications associated with novel influenza A (H1N1) virus infection in children - Dallas, Texas, May 2009

Neurologic complications, including seizures, encephalitis, encephalopathy, Reye syndrome, and other neurologic disorders, have been described previously in association with respiratory tract infection with seasonal influenza A or B viruses, but not with novel influenza A (H1N1) virus. On May 28, 2009, the Dallas County Department of Health and Human Services (DCHHS) notified CDC of four children with neurologic complications associated with novel influenza A (H1N1) virus infection admitted to hospitals in Dallas County, Texas, during May 18-28. This report summarizes the clinical characteristics of those four cases. Patients were aged 7-17 years and were admitted with signs of influenza-like illness (ILI) and seizures or altered mental status. Three of the four patients had abnormal electroencephalograms (EEGs). In all four patients, novel influenza A (H1N1) viral RNA was detected in nasopharyngeal specimens but not in cerebrospinal fluid (CSF). Antiviral therapy included oseltamivir (four patients) and rimantadine (three patients). All four patients recovered fully and had no neurologic sequelae at discharge. These findings indicate that, as with seasonal influenza, neurologic complications can occur after respiratory tract infection with novel influenza A (H1N1) virus. For children who have ILI accompanied by unexplained seizures or mental status changes, clinicians should consider acute seasonal influenza or novel influenza A (H1N1) virus infection in the differential diagnosis, send respiratory specimens for appropriate diagnostic testing, and promptly initiate empirical antiviral treatment, especially in hospitalized patients.

The comorbidity of HIV-associated neurocognitive disorders and Alzheimer's disease: a foreseeable medical challenge in post-HAART era

Although the introduction of highly active antiretroviral therapy (HAART) has led to a strong reduction of HIV-associated dementia (HAD) incidence, the prevalence of minor HIV-1-associated neurocognitive disorder (HAND) is rising among AIDS patients. HAART medication has shifted neuropathology from a subacute encephalitic condition to a subtle neurodegenerative process involving synaptic and dendritic degeneration, particularly of hippocampal neurons that are spared prior to HAART medication. Considerable neuroinflammation coupled with mononuclear phagocyte activation is present in HAART-medicated brains, particularly in the hippocampus. Accumulating evidence suggests that the resultant elevated secretion of pro-inflammatory cytokines such as interferon-gamma, tumor necrosis factor-alpha, and interleukin-1beta can increase amyloid-beta peptide (Abeta) generation and reduce Abeta clearance. Recent advancements in Alzheimer's disease (AD) research identified Abeta biogenesis and clearance venues that are potentially influenced by HIV viral infection, providing new insights into beta-amyloidosis segregation in HIV patients. Our study suggests enhanced beta-amyloidosis in ART-treated HAD and HIV-associated encephalitis brains and suppression of Abeta clearance by viral infection of human primary macrophages. A growing awareness of potential convergent mechanisms leading to neurodegeneration shared by HIV and Abeta points to a significant chance of comorbidity of AD and HAND in senile HIV patients, which calls for a need of basic studies.

Drug abuse and hepatitis C infection as comorbid features of HIV associated neurocognitive disorder: neurocognitive and neuroimaging features

Substance abuse and co-infection with hepatitis C (HCV) are two highly relevant determinants of neurocognitive and neuroimaging abnormalities associated with HIV. Substance abuse and HCV are common in the HIV population and there is increasing evidence that the CNS is directly compromised by these comorbid conditions via additive or synergistic processes. In this article we review the current literature regarding mechanisms of neuronal injury as well as the neuropsychological and neuroimaging signatures associated with substance abuse and HCV status among HIV patients. We discuss specific methodological challenges and threats to validity associated with studies of HIV and comorbid substance use disorders or HCV and review potential strategies for minimizing their confounding effects. Efforts to understand the interactions between HIV, substance abuse and HCV co-infection will lead to more complete models of neuropathogenesis of HIV and a greater understanding of the variability in neuropsychological expression of HIV Associated Neurocognitive Disorder.

Neuropsychological functioning and antiretroviral treatment in HIV/AIDS: a review

This article presents a review of studies that have investigated the neuropsychological effects of antiretroviral treatment (ART) for HIV-1 infection. It provides a brief overview of the era of monotherapy, dual-therapy, and an extended overview of the current era of combination antiretroviral therapy (CART). This review highlights that while CART has had a dramatic effect on the incidence and the severity of HIV-associated neurocognitive disorders (HAND), HAND, in its mild form, still remains prevalent. New causes of this sustained prevalence are poor CNS penetration of some antiretroviral agents, drug resistance, poor adherence, potential neurotoxicity, co-morbidities such as the long-term CART side effects in relation to cardio-vascular disease, and chronic HIV brain infection that may facilitate the expression of new forms of neurodegenerative processes. The review emphasizes the need to address methodological limitations of published studies and the need for large and representative cross-disciplinary longitudinal investigations across the HIV illness span.

Host and viral factors influencing the pathogenesis of HIV-associated neurocognitive disorders

The human immunodeficiency virus (HIV) invades the central nervous system early in the course of infection and establishes a protected viral reservoir. However, neurocognitive consequences of HIV infection, known collectively as HIV-associated neurocognitive disorders (HAND), develop in only a small portion of infected patients. The precise mechanisms of pathogenesis involved in HIV-induced central nervous system injury are still not completely understood. In particular, most theories of HAND pathogenesis cannot account for either the selective vulnerability of specific neuronal populations to HIV-induced neurodegeneration or why only a subset of patients develop clinically detectable nervous system disease. Epidemiological and virological studies have identified a variety of host and viral factors that are associated with increased risk of developing HAND. Some host factors that predispose HIV-infected patients to HAND overlap with those associated with Alzheimer's disease (AD), suggesting the possibility that common pathogenic mechanisms may participate in both diseases. Here, we will review reports of host and viral factors associated with HAND and place these studies in the context of the data employed to support current theories regarding the molecular and cellular mechanisms that lead to HIV-induced neurodegeneration with additional focus on mechanisms common to AD pathogenesis.

Race-norming of neuropsychological tests

Recent studies in the United States indicate that some neurologically intact minority groupings perform well below White Americans on neuropsychological tests. This has sparked the production of race-norms, especially for African Americans, that seek to reduce false positive rates (i.e., neurologically intact individuals misdiagnosed with cognitive impairment) in neuropsychological assessments. There are problems with this enterprise including: possible justification for inferior/superior treatment of different racial groupings; unknown effects on false negative rates (i.e., cognitive deficit misdiagnosed as normal); the overlooking of factors possibly responsible for group racial differences (e.g., acculturation); non-scientific and non-operational definitions of race/ethnic groupings; and an impossibly large number of potential race/ethnic groupings for which to generate race-norms. An alternative approach is to use a single set of combined race/ethnic norms and estimate preexisting neuropsychological skill levels by using individual comparison standards. This alternative has been poorly researched, a situation that needs correcting.

Benefits and risks of stavudine therapy for HIV-associated neurologic complications in Uganda

BACKGROUND

The frequency of HIV dementia in a recent study of HIV+ individuals at the Infectious Disease Institute in Kampala, Uganda, was 31%. Coformulated generic drugs, which include stavudine, are the most common regimens to treat HIV infection in Uganda and many other parts of Africa.

OBJECTIVE

To evaluate the benefits and risks of stavudine-based highly active antiretroviral therapy (HAART) for HIV-associated cognitive impairment and distal sensory neuropathy. The study compared neuropsychological performance changes in HIV+ individuals initiating HAART for 6 months and HIV- individuals receiving no treatment for 6 months. The risk of antiretroviral toxic neuropathy as a result of the initiation of stavudine-based HAART was also examined.

METHODS

At baseline, 102 HIV+ individuals in Uganda received neurologic, neuropsychological, and functional assessments; began HAART; and were followed up for 6 months. Twenty-five HIV- individuals received identical clinical assessments and were followed up for 6 months.

RESULTS

In HIV+ individuals, there was improvement in verbal memory, motor and psychomotor speed, executive thinking, and verbal fluency. After adjusting for differences in sex, HIV+ individuals demonstrated significant improvement in the Color Trails 2 test (p = 0.025) compared with HIV- individuals. Symptoms of neuropathy developed in 38% of previously asymptomatic HIV+ patients after initiation of the stavudine-based HAART.

CONCLUSIONS

After the initiation of highly active antiretroviral therapy (HAART) including stavudine, HIV+ individuals with cognitive impairment improve significantly as demonstrated by improved performance on a test of executive function. However, peripheral neurotoxicity occurred in 30 patients, presumably because of stavudine-based HAART, suggesting the need for less toxic therapy.

[HIV infection associated cognitive disorders]

The most frequent neuropsychiatric complication of the human immunodefienciency virus infection is cognitive impairment, wich may range in severity from a mild cognitive disorder to a severe dementing illness. HIV-associated dementia is known to be a poor indicator in patients with HIV. Caring for a person who develops cognitive impairment or even stable dementia is exhausting emotionally, psysically and financially. The most important difference between HIV-associated dementia and HIV associated minor cognitive disorder is the severity of impairment in activities of daily living. The purpose of this articol is to distinguish the most common symptomatology of this complication of HIV infection in order to prevent and treat cognitive deficits from the early stages if is possible.

Neurocognitive impairment in early HIV-positive individuals

The study was carried out to find out the cognitive impairment if any, in early stages of human immunodeficiency virus-positive patients and if there is any cognitive impairment, then its association with duration of illness detection. Fifty patients with early stages of HIV and 50 matched controls were compared in various neuropsychological tests along with demographic profiles. Seropositive patients had poorly performed in digit symbol substitution test, trail making test and controlled word association test. This impairment had no association with duration of detection of illness. It is not known whether mild neurocognitive disorder predisposes patients to the development of frank dementia. Cognitive impairment should be identified early in order to maximise functional status, enhance quality of life and survival time.