Alterations in brain metabolism during the first year of HIV infection

Central Nervous System Effects of Early HIV Infection and Consequences of Antiretroviral Therapy Initiation during Acute HIV

HIV infection is a multi-organ disease that involves the central nervous system (CNS). While devastating CNS complications such as HIV-associated dementia and CNS opportunistic infection typically manifest years after HIV acquisition, HIV RNA is readily detected in the cerebrospinal fluid in untreated neuroasymptomatic people with HIV, highlighting that HIV neuroinvasion predates overt clinical manifestations. Over the past two decades, increased awareness of HIV infection within the at-risk population, coupled with the accessibility of nucleic acid testing and modern HIV immunoassays, has made the detection of acute and early HIV infection readily achievable. This review aims to summarize research findings on CNS involvement during acute and early HIV infection, as well as the outcomes following the immediate initiation of antiretroviral therapy during this early stage of infection. The knowledge gap in long-term neuroprotection through early ART within the first year of infection will be discussed.

HIV viremia contributes to neurocognitive impairments in persons who use cocaine

Persons with HIV (PWH) who use illicit drugs are at elevated risk for neurocognitive impairment (NCI). This study investigated the effects of HIV disease and HIV viremia on NCI among adults who use cocaine. PWH who were not virologically suppressed showed greater global deficits compared to participants with HIV viral suppression and HIV-negative participants, but no differences emerged between the latter two groups. These findings highlight the adverse effects of poorly controlled HIV disease on NCI, beyond the independent effects of cocaine on cognition, and underscore the importance of strengthening the HIV care continuum for persons who use cocaine.

Evaluation of Two Post-Processing Analysis Methods of Proton Magnetic Resonance Spectroscopy in Glioma Tumors

BACKGROUND

Magnetic resonance spectroscopy (MRS) is a non-invasive diagnostic and the neuroimaging method of choice for the noninvasive monitoring of brain metabolism in patients with glioma tumors. ¹H-MRS is a reliable and non-invasive tool used to study glioma. However, the metabolite spectra obtained by ¹H-MRS requires a specific quantification procedure for post-processing. According to our knowledge, no comparisons have yet been made between spectrum analysis software for quantification of gliomas metabolites.

OBJECTIVE

Current study aims to evaluate the difference between this two common software in quantifying cerebral metabolites.

MATERIAL AND METHODS

In this analytical study, we evaluate two post-processing software packages, java-based graphical for MR user interface packages (jMRUI) and totally automatic robust quantitation in NMR (TARQUIN) software. ¹H-MRS spectrum from the brain of patients with gliomas tumors was collected for post-processing. AMARES algorithms were conducted to metabolite qualification on jMRUI software, and TARQUIN software were implemented with automated quantification algorithms. The study included a total of 30 subjects. For quantification, subjects were divided into a normal group (n=15) and group of gliomas (n=15).

RESULTS

When calculated by TARQUIN, the mean metabolites ratio was typically lower than by jMRUI. While, the mean ratio of metabolites varied when quantified by jMRUI vs. TARQUIN, both methods apparent clinical associations.

CONCLUSION

TARQUIN and jMRUI are feasible choices for the post-processing of cerebral MRS data obtained from glioma tumors.

Brain temperature as an indicator of neuroinflammation induced by typhoid vaccine: Assessment using whole-brain magnetic resonance spectroscopy in a randomised crossover study

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MRSI-derived whole-brain temperature did not detect low-level neuroinflammation.

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Regional brain temperature was a more sensitive measure of neuroinflammation.

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MRSI/EPSI might be a useful measure of neuroinflammation in psychiatric disorders.

Prior studies indicate a pathogenic role of neuroinflammation in psychiatric disorders; however, there are no accepted methods that can reliably measure low-level neuroinflammation non-invasively in these individuals. Magnetic resonance spectroscopic imaging (MRSI) is a versatile, non-invasive neuroimaging technique that demonstrates sensitivity to brain inflammation. MRSI in conjunction with echo-planar spectroscopic imaging (EPSI) measures brain metabolites to derive whole-brain and regional brain temperatures, which may increase in neuroinflammation. The validity of MRSI/EPSI for measurement of low level neuroinflammation was tested using a safe experimental model of human brain inflammation – intramuscular administration of typhoid vaccine. Twenty healthy volunteers participated in a double-blind, placebo-controlled crossover study including MRSI/EPSI scans before and 3 h after vaccine/placebo administration. Body temperature and mood, assessed using the Profile of Mood States, were measured every hour up to four hours post-treatment administration. A mixed model analysis of variance was used to test for treatment effects. A significant proportion of brain regions (44/47) increased in temperature post-vaccine compared to post-placebo (p < 0.0001). For temperature change in the brain as a whole, there was no significant treatment effect. Significant associations were seen between mood scores assessed at 4 h and whole brain and regional temperatures post-treatment. Findings indicate that regional brain temperature may be a more sensitive measure of low-level neuroinflammation than whole-brain temperature. Future work where these measurement techniques are applied to populations with psychiatric disorders would be of clinical interest.

Cognitive Effects of a Ketogenic Diet on Neurocognitive Impairment in Adults Aging With HIV: A Pilot Study

We assessed a ketogenic diet (KD) intervention protocol and the cognitive effects of KD in older adults with HIV-associated neurocognitive impairment. Adults older than 50 years and living with HIV and mild-to-moderate neurocognitive impairment were randomized to either a KD or a patient-choice diet for 12 weeks followed by a 6-week washout period. A neurocognitive battery was administered at baseline, Week 12, and Week 18. Paired t tests compared groups at baseline, and multivariate analyses of covariance were used to assess between-group differences on primary outcome variables at Weeks 12 and 18. We enrolled 17 participants, and 14 completed the study. No between-group baseline differences were noted. The KD group demonstrated improved executive function and speed of processing at Week 12, which were negated after participants resumed their usual diets. Our study supports the potential efficacy of a KD for the treatment of HIV-associated neurocognitive impairment.

A longitudinal study of brain volume changes in rhesus macaque model infected with SIV

Given the current lack of understanding of brain volume changes caused by HIV infection, this study aimed to longitudinally assess the changes in regional brain tissue volume following HIV infection and to explore its relationship with peripheral blood absolute CD4+ lymphocyte count (CD4+), the percentage of monocytes in plasma(MON%) and cerebrospinal fluid viral load (CFVL).Four adult male rhesus monkeys were examined in healthy status and following infection with simian immunodeficiency virus using high-resolution 3D T1-weighted sagittal whole brain magnetic resonance imaging. DPABI and SPM were used to process and record changes in brain tissue volume. Correlation analyses were then used to explore the above relationships. Compared with brain tissue volume during the healthy stage, there was no change at 12 and 24 weeks postinoculation (12 wpi, 24 wpi). At 36 wpi, 48 wpi, and 60 wpi, basal ganglia, left inferior temporal gyrus, left occipital gyrus, and left superior frontal gyrus exhibited varying degrees of atrophy. There was no association found between CD4+, MON%, CFVL, and brain volume loss in any brain region. Our research demonstrated that in the early stage of HIV infection, local brain tissue atrophy can be demonstrated by MRI technique; furthermore, MRI can identify the earliest site of atrophy as well as the most severely affected site. Although there was no significant correlation between brain tissue volume loss and CD4+, MON%, and CFVL, our findings provided some evidence in the application of volumetric MR imaging in the early diagnosis and treatment follow-up of patients with HIV infection.

Bioenergetic adaptations to HIV infection. Could modulation of energy substrate utilization improve brain health in people living with HIV-1?

The human brain consumes more energy than any other organ in the body and it relies on an uninterrupted supply of energy in the form of adenosine triphosphate (ATP) to maintain normal cognitive function. This constant supply of energy is made available through an interdependent system of metabolic pathways in neurons, glia and endothelial cells that each have specialized roles in the delivery and metabolism of multiple energetic substrates. Perturbations in brain energy metabolism is associated with a number of different neurodegenerative conditions including impairments in cognition associated with infection by the Human Immunodeficiency Type 1 Virus (HIV-1). Adaptive changes in brain energy metabolism are apparent early following infection, do not fully normalize with the initiation of antiretroviral therapy (ART), and often worsen with length of infection and duration of anti-retroviral therapeutic use. There is now a considerable amount of cumulative evidence that suggests mild forms of cognitive impairments in people living with HIV-1 (PLWH) may be reversible and are associated with specific modifications in brain energy metabolism. In this review we discuss brain energy metabolism with an emphasis on adaptations that occur in response to HIV-1 infection. The potential for interventions that target brain energy metabolism to preserve or restore cognition in PLWH are also discussed.

Use of Neuroimaging to Inform Optimal Neurocognitive Criteria for Detecting HIV-Associated Brain Abnormalities

OBJECTIVE

Frascati international research criteria for HIV-associated neurocognitive disorders (HAND) are controversial; some investigators have argued that Frascati criteria are too liberal, resulting in a high false positive rate. Meyer et al. recommended more conservative revisions to HAND criteria, including exploring other commonly used methodologies for neurocognitive impairment (NCI) in HIV including the global deficit score (GDS). This study compares NCI classifications by Frascati, Meyer, and GDS methods, in relation to neuroimaging markers of brain integrity in HIV.

METHOD

Two hundred forty-one people living with HIV (PLWH) without current substance use disorder or severe (confounding) comorbid conditions underwent comprehensive neurocognitive testing and brain structural magnetic resonance imaging and magnetic resonance spectroscopy. Participants were classified using Frascati criteria versus Meyer criteria: concordant unimpaired [Frascati(Un)/Meyer(Un)], concordant impaired [Frascati(Imp)/Meyer(Imp)], or discordant [Frascati(Imp)/Meyer(Un)] which were impaired via Frascati criteria but unimpaired via Meyer criteria. To investigate the GDS versus Meyer criteria, the same groupings were utilized using GDS criteria instead of Frascati criteria.

RESULTS

When examining Frascati versus Meyer criteria, discordant Frascati(Imp)/Meyer(Un) individuals had less cortical gray matter, greater sulcal cerebrospinal fluid volume, and greater evidence of neuroinflammation (i.e., choline) than concordant Frascati(Un)/Meyer(Un) individuals. GDS versus Meyer comparisons indicated that discordant GDS(Imp)/Meyer(Un) individuals had less cortical gray matter and lower levels of energy metabolism (i.e., creatine) than concordant GDS(Un)/Meyer(Un) individuals. In both sets of analyses, the discordant group did not differ from the concordant impaired group on any neuroimaging measure.

CONCLUSIONS

The Meyer criteria failed to capture a substantial portion of PLWH with brain abnormalities. These findings support continued use of Frascati or GDS criteria to detect HIV-associated CNS dysfunction.

Normalization of Soluble CD163 Levels After Institution of Antiretroviral Therapy During Acute HIV Infection Tracks with Fewer Neurological Abnormalities

Background

Myeloid activation contributes to cognitive impairment in chronic human immunodeficiency virus (HIV) infection. We explored whether combination antiretroviral therapy (cART) initiation during acute HIV infection impacts CD163 shedding, a myeloid activation marker, and in turn, implications on the central nervous system (CNS).

Methods

We measured soluble CD163 (sCD163) levels in plasma and cerebrospinal fluid (CSF) by enzyme-linked immunosorbent assay in Thais who initiated cART during acute HIV infection (Fiebig stages I-IV). Examination of CNS involvement included neuropsychological testing and analysis of brain metabolites by magnetic resonance spectroscopy. Chronic HIV-infected or uninfected Thais served as controls.

Results

We examined 51 adults with acute HIV infection (Fiebig stages I-III; male sex, >90%; age, 31 years). sCD163 levels before and after cART in Fiebig stage I/II were comparable to those in uninfected controls (plasma levels, 97.9 and 93.6 ng/mL, respectively, vs 99.5 ng/mL; CSF levels, 6.7 and 6.4 ng/mL, respectively, vs 7.1 ng/mL). In Fiebig stage III, sCD163 levels were elevated before cART as compared to those in uninfected controls (plasma levels, 135 ng/mL; CSF levels, 10 ng/mL; P < .01 for both comparisons) before normalization after cART (plasma levels, 90.1 ng/mL; CSF levels, 6.5 ng/mL). Before cART, higher sCD163 levels during Fiebig stage III correlated with poor CNS measures (eg, decreased N-acetylaspartate levels), but paradoxically, during Fiebig stage I/II, this association was linked with favorable CNS outcomes (eg, higher neuropsychological test scores). After cART initiation, higher sCD163 levels during Fiebig stage III were associated with negative CNS indices (eg, worse neuropsychological test scores).

Conclusion

Initiation of cART early during acute HIV infection (ie, during Fiebig stage I/II) may decrease inflammation, preventing shedding of CD163, which in turn might lower the risk of brain injury.

HIV-1 persistence in the central nervous system: viral and host determinants during antiretroviral therapy

Despite remarkable therapeutic advances in the past two decades, the elimination of human immunodeficiency virus type 1 (HIV-1) from latent reservoirs constitutes a major barrier to eradication and preventing neurological disease associated with HIV/AIDS. Invasion of the central nervous system (CNS) by HIV-1 occurs early in infection, leading to viral infection and productive persistence in brain macrophage-like cells (BMCs) including resident microglia and infiltrating macrophages. HIV-1 persistence in the brain and chronic neuroinflammation occur despite effective treatment with antiretroviral therapy (ART). This review examines the evidence from clinical studies, in vivo and in vitro models for HIV-1 CNS persistence, as well as therapeutic considerations in targeting latent CNS reservoirs.

HIV brain latency as measured by CSF BcL11b relates to disrupted brain cellular energy in virally suppressed HIV infection

OBJECTIVE

We investigated whether HIV brain latency was associated with brain injury in virally suppressed HIV infection.

DESIGN

Observational cross-sectional and longitudinal study.

METHODS

The study included 26 virally suppressed HIV-infected men (61.5% with HIV-associated neurocognitive disorder) who undertook cerebrospinal fluid (CSF) analyses at baseline. They also completed a proton magnetic resonance spectroscopy (1H MRS) and neuropsychological assessments at baseline and 18 months. To quantify whether there was residual brain HIV transcription, we measured CSF HIV-tat. As an HIV brain latency biomarker, we used concentrations of CSF BcL11b - a microglia transcription factor that inhibits HIV transcription. Concurrently, we assessed neuroinflammation with CSF neopterin, neuronal injury with CSF neurofilament light-chain (NFL), and in-vivo neurochemistry with 1H MRS of N-acetyl aspartate (NAA), choline (Cho), creatine, myo-inositol (MI), glutamine/glutamate (Glx) in the frontal white matter (FWM), posterior cingulate cortex (PCC), and caudate nucleus area.

RESULTS

Baseline adjusted regression models for neopterin, NFL, and tat showed that a higher CSF BcL11b was consistently associated with lower FWM creatine (when adjusted for neopterin: β = -0.30, P = 0.15; when adjusted for NFL: β = -0.47, P = 0.04; and when adjusted for tat: β = -0.47, P = 0.02). In longitudinal analyses, we found no time effect, but a consistent BcL11b altering effect on FWM creatine. The effect reached a significant moderate effect size range when corrected for CSF NFL (β = -0.36, P = 0.02) and CSF tat (β = -0.34, P = 0.02).

CONCLUSIONS

Reduced frontal white matter total creatine may indicate subclinical HIV brain latency-related injury. H MRS may offer a noninvasive option to measure HIV brain latency.

Simian immunodeficiency virus transiently increases brain temperature in rhesus monkeys: detection with magnetic resonance spectroscopy thermometry

PURPOSE

To evaluate brain temperature effects of early simian immunodeficiency virus (SIV) infection in rhesus macaques using proton magnetic resonance spectroscopy (MRS) thermometry (MRSt) and to determine whether temperature correlates with brain choline or myo-inositol levels.

METHODS

Brain temperature was retrospectively determined in serial MRS scans that had been acquired at baseline and at 2 and 4 weeks post-SIV infection (wpi) in 16 monkeys by calculating the chemical shift difference between N-acetylaspartate (NAA) and water peaks in sequentially acquired water-suppressed and unsuppressed point-resolved spectroscopy (PRESS) spectra. Frontal and parietal cortex, basal ganglia, and white matter spectra were analyzed.

RESULTS

At 2 wpi, brain and rectal temperatures increased relative to baseline and normalized at 4 wpi. Brain temperatures correlated with choline levels in several brain areas, but not with myo-inositol levels.

CONCLUSION

These data indicate that SIV transiently increases brain temperature soon after infection and that temperature is correlated with transient changes in choline levels. Given that choline levels are associated with brain inflammation in SIV-infected monkeys, our findings suggest that the SIV-induced temperature increase reflects brain inflammation. We conclude that MRSt may be informative in human immunodeficiency virus models and may be useful for assessing effects of treatments that reduce inflammation. This study also illustrates that existing MRS data sets containing unsuppressed water spectra can be used to measure tissue temperature, an important physiological parameter.

CCR2 on Peripheral Blood CD14+CD16+ Monocytes Correlates with Neuronal Damage, HIV-Associated Neurocognitive Disorders, and Peripheral HIV DNA: reseeding of CNS reservoirs?

HIV-associated neurocognitive disorders (HAND) occur in ~50% of HIV infected individuals despite combined antiretroviral therapy. Transmigration into the CNS of CD14⁺CD16⁺ monocytes, particularly those that are HIV infected and express increased surface chemokine receptor CCR2, contributes to neuroinflammation and HAND. To examine whether in HIV infected individuals CCR2 on CD14⁺CD16⁺ monocytes serves as a potential peripheral blood biomarker of HAND, we examined a cohort of 45 HIV infected people. We correlated CCR2 on CD14⁺CD16⁺ monocytes with cognitive status, proton magnetic resonance spectroscopy (¹H-MRS) measured neurometabolite levels, and peripheral blood mononuclear cell (PBMC) HIV DNA copies. We determined that CCR2 was increased specifically on CD14⁺CD16⁺ monocytes from people with HAND (median [interquartile range (IQR)]) (63.3 [51.6, 79.0]), compared to those who were not cognitively impaired (38.8 [26.7, 56.4]) or those with neuropsychological impairment due to causes other than HIV (39.8 [30.2, 46.5]). CCR2 was associated with neuronal damage, based on the inverse correlation of CCR2 on CD14⁺CD16⁺ monocytes with total N-Acetyl Aspartate (tNAA)/total Creatine (tCr) (r² = 0.348, p = 0.01) and Glutamine-Glutamate (Glx)/tCr (r² = 0.356, p = 0.01) in the right and left caudate nucleus, respectively. CCR2 on CD14⁺CD16⁺ monocytes also correlated with PBMC HIV DNA copies (ρ = 0.618, p = 0.02) that has previously been associated with HAND. These findings suggest that CCR2 on CD14⁺CD16⁺ monocytes may be a peripheral blood biomarker of HAND, indicative of increased HIV infected CD14⁺CD16⁺ monocyte entry into the CNS that possibly increases the macrophage viral reservoir and contributes to HAND.

Altered White Matter Integrity in Human Immunodeficiency Virus-Associated Neurocognitive Disorder: A Tract-Based Spatial Statistics Study

Objective

Human immunodeficiency virus (HIV) infection has been known to damage the microstructural integrity of white matter (WM). However, only a few studies have assessed the brain regions in HIV-associated neurocognitive disorders (HAND) with diffusion tensor imaging (DTI). Therefore, we sought to compare the DTI data between HIV patients with and without HAND using tract-based spatial statistics (TBSS).

Materials and Methods

Twenty-two HIV-infected patients (10 with HAND and 12 without HAND) and 11 healthy controls (HC) were enrolled in this study. A whole-brain analysis of fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity was performed with TBSS and a subsequent 20 tract-specific region-of-interest (ROI)-based analysis to localize and compare altered WM integrity in all group contrasts.

Results

Compared with HC, patients with HAND showed decreased FA in the right frontoparietal WM including the upper corticospinal tract (CST) and increased MD and RD in the bilateral frontoparietal WM, corpus callosum, bilateral CSTs and bilateral cerebellar peduncles. The DTI values did not significantly differ between HIV patients with and without HAND or between HIV patients without HAND and HC. In the ROI-based analysis, decreased FA was observed in the right superior longitudinal fasciculus and was significantly correlated with decreased information processing speed, memory, executive function, and fine motor function in HIV patients.

Conclusion

These results suggest that altered integrity of the frontoparietal WM contributes to cognitive dysfunction in HIV patients.

The Aging Brain With HIV Infection: Effects of Alcoholism or Hepatitis C Comorbidity

As successfully treated individuals with Human Immunodeficiency Virus (HIV)-infected age, cognitive and health challenges of normal aging ensue, burdened by HIV, treatment side effects, and high prevalence comorbidities, notably, Alcohol Use Disorders (AUD) and Hepatitis C virus (HCV) infection. In 2013, people over 55 years old accounted for 26% of the estimated number of people living with HIV (~1.2 million). The aging brain is increasingly vulnerable to endogenous and exogenous insult which, coupled with HIV infection and comorbid risk factors, can lead to additive or synergistic effects on cognitive and motor function. This paper reviews the literature on neuropsychological and in vivo Magnetic Resonance Imaging (MRI) evaluation of the aging HIV brain, while also considering the effects of comorbidity for AUD and HCV.

7T Brain MRS in HIV Infection: Correlation with Cognitive Impairment and Performance on Neuropsychological Tests

BACKGROUND AND PURPOSE

Validated neuroimaging markers of HIV-associated neurocognitive disorder in patients on antiretroviral therapy are urgently needed for clinical trials. The purpose of this study was to explore the relationship between cognitive impairment and brain metabolism in older subjects with HIV infection. It was hypothesized that MR spectroscopy measurements related to neuronal health and function (particularly N-acetylaspartate and glutamate) would be lower in HIV-positive subjects with worse cognitive performance.

MATERIALS AND METHODS

Forty-five HIV-positive patients (mean age, 58.9 ± 5.3 years; 33 men) underwent detailed neuropsychological testing and brain MR spectroscopy at 7T. Twenty-four subjects were classified as having asymptomatic cognitive impairment, and 21 were classified as having symptomatic cognitive impairment. Single-voxel proton MR spectra were acquired from 5 brain regions and quantified using LCModel software. Brain metabolites and neuropsychological test results were compared using nonparametric statistics and Pearson correlation coefficients.

RESULTS

Differences in brain metabolites were found between symptomatic and asymptomatic subjects, with the main findings being lower measures of N-acetylaspartate in the frontal white matter, posterior cingulate cortex, and precuneus. In the precuneus, glutamate was also lower in the symptomatic group. In the frontal white matter, precuneus, and posterior cingulate cortex, NAA and glutamate measurements showed significant positive correlation with better performance on neuropsychological tests.

CONCLUSIONS

Compared with asymptomatic subjects, symptomatic HIV-positive subjects had lower levels of NAA and glutamate, most notably in the frontal white matter, which also correlated with performance on neuropsychological tests. High-field MR spectroscopy offers insight into the pathophysiology associated with cognitive impairment in HIV and may be useful as a quantitative outcome measure in future treatment trials.

Sonic Hedgehog mimetic prevents leukocyte infiltration into the CNS during acute HIV infection

Infiltration of infected leukocytes culminates in establishment of a brain niche for Human Immunodeficiency Virus (HIV) during acute phase of infection, initiating an ongoing cascade of persistent viral replication and inflammation, that causes irreversible neuronal injury and HIV associated neurocognitive disease (HAND). In this study, humanized mice were treated with Smoothened Agonist (SAG), a Sonic Hedgehog (Shh) mimetic in order to fortify blood brain barrier (BBB) and dampen leukocyte extravasation into CNS during AHI. Results indicate that SAG treatment reduced viral burden in the CNS immediately after HIV transmission, but also conferred extended neuroprotection via increased BBB integrity (elevated levels of tight-junction protein, Claudin 5, and reduced S100B levels in periphery). These mice also showed healthier neurons with thick, uniform dendrites and reduced numbers of activated astrocytes. Additional in vitro experiments suggested SAG treatment was not associated with the establishment or reversal of latency in the target cells. Altogether, these findings validate neuroprotective role of Shh signaling and highlight the therapeutic potential of Shh mimetics against CNS complications associated with HIV infection. Further our results strongly demonstrate that pharmacological interventions to reduce leukocyte mobilization during early HIV infection, can provide prolonged neuroprotection, which might significantly delay the onset of HAND.

Topological Organization of Whole-Brain White Matter in HIV Infection

Infection with human immunodeficiency virus (HIV) is associated with neuroimaging alterations. However, little is known about the topological organization of whole-brain networks and the corresponding association with cognition. As such, we examined structural whole-brain white matter connectivity patterns and cognitive performance in 29 HIV+ young adults (mean age = 25.9) with limited or no HIV treatment history. HIV+ participants and demographically similar HIV- controls (n = 16) residing in South Africa underwent magnetic resonance imaging (MRI) and neuropsychological testing. Structural network models were constructed using diffusion MRI-based multifiber tractography and T₁-weighted MRI-based regional gray matter segmentation. Global network measures included whole-brain structural integration, connection strength, and structural segregation. Cognition was measured using a neuropsychological global deficit score (GDS) as well as individual cognitive domains. Results revealed that HIV+ participants exhibited significant disruptions to whole-brain networks, characterized by weaker structural integration (characteristic path length and efficiency), connection strength, and structural segregation (clustering coefficient) than HIV- controls (p < 0.05). GDSs and performance on learning/recall tasks were negatively correlated with the clustering coefficient (p < 0.05) in HIV+ participants. Results from this study indicate disruption to brain network integrity in treatment-limited HIV+ young adults with corresponding abnormalities in cognitive performance.

Cognitive function in early HIV infection

This study aimed to examine cognitive function in acute/early HIV infection over the subsequent 2 years. Fifty-six HIV+ subjects and 21 seronegative participants of the Chicago Early HIV Infection Study were evaluated using a comprehensive neuropsychological assessment at study enrollment and at 2-year follow-up. Cognitive performance measures were compared in the groups using t tests and mixed-effect models. Patterns of relationship with clinical measures were determined between cognitive function and clinical status markers using Spearman's correlations. At the initial timepoint, the HIV group demonstrated significantly weaker performance on measures of verbal memory, visual memory, psychomotor speed, motor speed, and executive function. A similar pattern was found when cognitive function was examined at follow-up and across both timepoints. The HIV subjects had generally weaker performance on psychomotor speed, executive function, motor speed, visual memory, and verbal memory. The rate of decline in cognitive function across the 2-year follow-up period did not differ between groups. Correlations between clinical status markers and cognitive function at both timepoints showed weaker performance associated with increased disease burden. Neurocognitive difficulty in chronic HIV infection may have very early onset and reflect consequences of initial brain viral invasion and neuroinflammation during the intense, uncontrolled viremia of acute HIV infection. Further characterization of the changes occurring in initial stages of infection and the risk and protective factors for cognitive function could inform new strategies for neuroprotection.

Neurobehavioral Disturbances During Acute and Early HIV Infection

BACKGROUND AND OBJECTIVE

Acute and early human immunodeficiency virus infection (AEH) is accompanied by neuroinflammatory processes as well as impairment in neurocognitive and everyday functions, but little is known about the frequency and clinical correlates of the neurobehavioral disturbances during this period. We compared pre-seroconversion with current levels of apathy, disinhibition, and executive dysfunction; we also examined everyday function and HIV disease correlates of neuropsychiatric impairment in individuals with AEH.

METHODS

In this study, 34 individuals with AEH and 39 HIV-seronegative participants completed neuromedical and neuropsychological assessments, a structured psychiatric interview, and the apathy, disinhibition, and executive dysfunction subscales of the Frontal Systems Behavioral Scale.

RESULTS

Independent of any substance use and mood disorders, the AEH group had significantly higher levels of current apathy and executive dysfunction than the controls, but not greater disinhibition. Retrospective ratings of pre-seroconversion levels of apathy, disinhibition, and executive dysfunction were all higher in the AEH group than the controls. After seroconversion, the AEH cohort had increases in current apathy and executive dysfunction, but not disinhibition. In the AEH cohort, higher current global neurobehavioral dysfunction was significantly associated with lower nadir CD4 counts, slowed information processing speed, and more everyday function problems.

CONCLUSIONS

These data suggest that individuals who have recently acquired HIV experienced higher-than-normal premorbid levels of neurobehavioral disturbance. Apathy and executive dysfunction are exacerbated during AEH, particularly in association with lower CD4 counts.

HIV and Cocaine Impact Glial Metabolism: Energy Sensor AMP-activated protein kinase Role in Mitochondrial Biogenesis and Epigenetic Remodeling

HIV infection and cocaine use have been identified as risk factors for triggering neuronal dysfunction. In the central nervous system (CNS), energy resource and metabolic function are regulated by astroglia. Glia is the major reservoir of HIV infection and disease progression in CNS. However, the role of cocaine in accelerating HIV associated energy deficit and its impact on neuronal dysfunction has not been elucidated yet. The aim of this study is to elucidate the molecular mechanism of HIV associated neuropathogenesis in cocaine abuse and how it accelerates the energy sensor AMPKs and its subsequent effect on mitochondrial oxidative phosphorylation (OXPHOS), BRSKs, CDC25B/C, MAP/Tau, Wee1 and epigenetics remodeling complex SWI/SNF. Results showed that cocaine exposure during HIV infection significantly increased the level of p24, reactive oxygen species (ROS), ATP-utilization and upregulated energy sensor AMPKs, CDC25B/C, MAP/Tau and Wee1 protein expression. Increased ROS production subsequently inhibits OCR/ECAR ratio and OXPHOS, and eventually upregulate epigenetics remodeling complex SWI/SNF in CHME-5 cells. These results suggest that HIV infection induced energy deficit and metabolic dysfunction is accelerated by cocaine inducing energy sensor AMPKs, mitochondrial biogenesis and chromatin remodeling complex SWI/SNF activation, which may lead to neuroAIDS disease progression.

A comparison of two post-processing analysis methods to quantify cerebral metabolites measured via proton magnetic resonance spectroscopy in HIV disease

OBJECTIVE

Non-invasive biomarkers to monitor cerebral function in treated human immunodeficiency virus (HIV) disease are required. Cerebral metabolite ratios (CMRs) measured by proton-MR spectroscopy ((1)H-MRS) are a potential biomarker. Here, we compare two post-processing software packages to quantify CMRs.

METHODS

Cerebral (1)H-MRS data from 11 HIV-positive subjects before and after antiretroviral therapy intensification with maraviroc were quantified using a java-based version of the MR user interface package (jMRUI) and the totally automatic robust quantitation in nuclear MR (TARQUIN). (1)H-MRS data included N-acetylaspartate (NAA), creatine (Cr), choline (Cho) and myo-inositol (mI) from three cerebral locations. Differences in quantification and clinical associations of CMRs measured by the two packages were evaluated.

RESULTS

Mean CMRs were generally lower when measured by TARQUIN than by jMRUI (NAA/Cr, Cho/Cr, mI/Cr ratios of 1.78, 0.83, 0.81 for jMRUI, and 1.27, 0.25, 0.81 for TARQUIN). Longitudinal changes were observed in CMRs in the basal ganglia voxel although these changes were not statistically significant [+7.1% (p = 0.18), +0.0% (p = 0.91) and -6.6% (p = 0.61) and +14.8% (p = 0.18), +17.9% (p = 0.07) and +34.8% (p = 0.17) for NAA/Cr, Cho/Cr and mI/Cr ratios measured by TARQUIN and jMRUI, respectively]. Plasma maraviroc concentration was associated with a decrease in mI/Cr ratio measured via TARQUIN (p = 0.049).

CONCLUSION

Although CMRs differed when quantified by jMRUI vs TARQUIN, these differences were consistently observed across three cerebral locations, and clinical associations were evident by both methods.

ADVANCES IN KNOWLEDGE

TARQUIN and jMRUI are viable options to use in the post-processing of cerebral MRS data acquired in HIV disease.

Case control study: magnetic resonance spectroscopy of brain in HIV infected patients

BACKGROUND

In vivo proton magnetic resonance spectroscopy ((1)H-MRS) studies on brain in HIV infected patients have shown significant alteration in neuro-biochemicals.

METHODS

In this study, we measured the neuro-biochemical metabolites from the left frontal white matter (FWM) and left basal ganglia (BG) caudate head nucleus in 71 subjects that include 30 healthy controls, 20 asymptomatic HIV and 21 HIV patients with CNS lesion. Proton MR spectra were acquired at 3 T MRI system and the concentration (institutional units) of tNAA (N-acetylaspartate, NAA + N-acetylaspartylglutamate, NAAG), tCr (Creatine, Cr + phosphocreatine, PCr), choline containing compounds (tCho), glutamate + glutamine (Glx) and lipid and macromolecules at 0.9 ppm were determined using LC Model.

RESULTS

In BG, the concentration of tNAA (6.71 ± 0.64) was decreased and in FWM, the concentration of Glx (20.4 ± 7.8), tCr (9.14 ± 3.04) and lipid and macromolecules at 0.9 ppm (8.69 ± 2.96) were increased in HIV patients with CNS lesion. In healthy controls, the concentration of tNAA in BG was 7.31 ± 0.47 and concentration of Glx, tCr and lipid and macromolecules in FWM were 15.0 ± 6.06, 6.95 ± 2.56, 5.59 ± 1.56, respectively.

CONCLUSION

Reduced tNAA in BG suggests neuronal loss in HIV patients with CNS lesion while increased Glx in FWM may suggest excito-toxicity. In addition, increased levels of tCr in FWM of HIV patients were observed. The study indicates region specific metabolic changes in tNAA, tCr and Glx in brain of HIV infected patients.

Neuronal-Glia Markers by Magnetic Resonance Spectroscopy in HIV Before and After Combination Antiretroviral Therapy

OBJECTIVE

Combination antiretroviral therapy (cART) can suppress plasma HIV RNA to undetectable levels; yet reports indicate persistent HIV-associated neurocognitive disorders (HAND) among treated individuals. We sought to investigate imaging correlates of incomplete cognitive recovery among individuals with chronic HIV.

METHODS

We used single voxel proton magnetic resonance spectroscopy in 4 regions of the brain to measure changes in neuronal and glia biomarkers in cART-naive subjects before (n = 59, 27 with HAND) and after 12 months of cART.

RESULTS

At baseline, we observed elevated total choline (CHO) in the basal ganglia (BG, P = 0.002) and in the posterior cingulate gyrus (PCG, P = 0.022) associated with HIV infection. Myo-inositol (MI) was elevated in the frontal white matter (FWM, P = 0.040). N-acetylaspartate was elevated in the BG (P = 0.047). Using a mixed model approach among all HIV-infected individuals, at 6 months, we observed decreased n- acetylaspartate in FWM (P = 0.031), decreased creatine in PCG (P = 0.026) and increased MI in frontal gray matter (FGM, P = 0.023). At 12 months, we observed an increase in BG MI (P = 0.038) and in FGM (P = 0.021). Compared to those with normal cognition, HAND cases had higher FGM MI (P = 0.014) at baseline. At 12 months, individuals that remained cognitively impaired compared with those without HAND exhibited elevated CHO in the PCG (P = 0.018) and decreased glutamate in both FWM (P = 0.027) and BG (P = 0.013).

CONCLUSIONS

cART started during chronic HIV is associated with reduced neuronal-glia and inflammatory markers. Alterations in CHO are noted among individuals who remain impaired after 12 months of cART.

Basic Principles and Clinical Applications of Magnetic Resonance Spectroscopy in Neuroradiology

Magnetic resonance spectroscopy is a powerful tool to assist daily clinical diagnostics. This review is intended to give an overview on basic principles of the technology, discuss some of its technical aspects, and present typical applications in daily clinical routine in neuroradiology.

Determinants of HIV-induced brain changes in three different periods of the early clinical course: A data mining analysis

To inform an understanding of brain status in HIV infection, quantitative imaging measurements were derived at structural, microstructural and macromolecular levels in three different periods of early infection and then analyzed simultaneously at each stage using data mining. Support vector machine recursive feature elimination was then used for simultaneous analysis of subject characteristics, clinical and behavioral variables, and immunologic measures in plasma and CSF to rank features associated with the most discriminating brain alterations in each period. The results indicate alterations beginning in initial infection and in all periods studied. The severity of immunosuppression in the initial virus host interaction was the most highly ranked determinant of earliest brain alterations. These results shed light on the initial brain changes induced by a neurotropic virus and their subsequent evolution. The pattern of ongoing alterations occurring during and beyond the period in which virus is suppressed in the systemic circulation supports the brain as a viral reservoir that may preclude eradication in the host. Data mining capabilities that can address high dimensionality and simultaneous analysis of disparate information sources have considerable utility for identifying mechanisms underlying onset of neurological injury and for informing new therapeutic targets.

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The brain was examined in initial stages of HIV using imaging and data mining.

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Brain alterations were identified in all studied periods of the early course.

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Severity of immunosuppression was the highest ranked determinant of onset.

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MMP-1 and CD33+CD36+ monocytes were identified as determinants in every period.

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The brain may represent an early reservoir that precludes viral eradication.

Neuroimaging of HIV-associated neurocognitive disorders (HAND)

PURPOSE OF REVIEW

HIV enters the brain after initial infection, and with time can lead to HIV-associated neurocognitive disorders (HAND). Although the introduction of combination antiretroviral therapy has reduced the more severe forms of HAND, milder forms are still highly prevalent. The 'gold standard' for HAND diagnosis remains detailed neuropsychological performance testing but additional biomarkers (including neuroimaging) may assist in early detection of HAND.

RECENT FINDINGS

We review the application of recently developed noninvasive MRI and PET techniques in HIV+ individuals. In particular, magnetic resonance spectroscopy may be more sensitive than conventional MRI alone in detecting HIV associated changes. Diffusion tensor imaging has become increasingly popular for assessing changes in white matter structural integrity due to HIV. Both functional MRI and PET have been limitedly performed but could provide keys for characterizing neuropathophysiologic changes due to HIV.

SUMMARY

It is hoped that continued progress will allow novel neuroimaging methods to be included in future HAND management guidelines.

Neuropathogenesis of HIV: from initial neuroinvasion to HIV-associated neurocognitive disorder (HAND)

Early in the HIV epidemic, the central nervous system (CNS) was recognized as a target of infection and injury in the advanced stages of disease. Though the most severe forms of HIV-associated neurocognitive disorder (HAND) related to severe immunosuppression are rare in the current era of widespread combination antiretroviral therapy (cART), evidence now supports pathological involvement of the CNS throughout the course of infection. Recent work suggests that the stage for HIV neuropathogenesis may be set with initial viral entry into the CNS, followed by initiation of pathogenetic processes including neuroinflammation and neurotoxicity, and establishment of local, compartmentalized HIV replication that may reflect a tissue reservoir for HIV. Key questions still exist as to when HIV establishes local infection in the CNS, which CNS cells are the primary targets of HIV, and what mechanistic processes underlie the injury to neurons that produce clinical symptoms of HAND. Advances in these areas will provide opportunities for improved treatment of patients with established HAND, prevention of neurological disease in those with early stage infection, and understanding of HIV tissue reservoirs that will aid efforts at HIV eradication.

Cerebral white matter integrity during primary HIV infection

OBJECTIVE

Inflammation and infection within the central nervous system is initiated during primary HIV infection (PHI), but the association of these processes with the integrity of brain white matter during PHI is unknown.

DESIGN

We used diffusion tensor imaging (DTI) in this prospective cross-sectional neuroimaging study to determine the extent of white matter involvement in early HIV infection.

METHODS

Antiretroviral-naive PHI (defined as <1 year after infection, n = 62), chronic HIV infection (CHI, n = 16), and HIV-uninfected (n = 19) participants had DTI, laboratory, and neuropsychometric performance assessments. DTI metrics were examined using region of interest and whole brain voxelwise analyses. Linear mixed-effects models assessed correlations between DTI measures and laboratory and neuropsychometric performance values.

RESULTS

PHI participants were assessed at a median 4.1 months after estimated infection, and had median CD4 cell count of 573 cells/μl, and HIV-1 RNA viral load of 4.5 log10 copies/ml in plasma and 2.6 log10 copies/ml in cerebrospinal fluid (CSF). DTI metrics in PHI individuals were similar to HIV- participants and correlated with disruptions in the blood-brain barrier (indicated by CSF/plasma albumin ratio and CSF protein). CHI participants had significant loss of white matter integrity that correlated with biomarkers of infection and inflammation (blood viral load, CD4 T-cell count, and neopterin, and CSF white blood cell). Within the PHI group, DTI metrics inversely correlated with increasing days since infection.

CONCLUSION

In individuals assessed during PHI, group DTI measures suggested relative preservation of white matter microstructural integrity, but were associated with disruption of the blood-brain barrier and estimated duration of infection.

Treatment of HIV in the CNS: effects of antiretroviral therapy and the promise of non-antiretroviral therapeutics

The growing recognition of the burden of neurologic disease associated with HIV infection in the last decade has led to renewed efforts to characterize the pathophysiology of the virus within the central nervous system (CNS). The concept of the AIDS-dementia complex is now better understood as a spectrum of HIV-associated neurocognitive disorders (HAND), which range from asymptomatic disease to severe impairment. Recent work has shown that even optimally treated patients can experience not only persistent HAND, but also the development of new neurologic abnormalities despite viral suppression. This has thrown into question what the impact of antiretroviral therapy has been on the incidence and prevalence of neurocognitive dysfunction. In this context, the last few years have seen a concentrated effort to identify the effects that antiretroviral therapy has on the neurologic manifestations of HIV and to develop therapeutic modalities that might specifically alter the trajectory of HIV within the CNS.

Longitudinal cerebral metabolic changes in pig-tailed macaques infected with the neurovirulent virus SIVsmmFGb

Longitudinal cerebral metabolite changes in pig-tailed macaques inoculated with the simian immunodeficiency virus SIVsmmFGb were evaluated with in vivo proton MRS at 3 T. Blood sample collection, and MRS were carried out before and 2, 4, 8, 12, 16, 20, and 24 weeks after SIV inoculation. Significant reduction of N-acetylaspartate (NAA)/creatine (Cr) and choline (Cho)/Cr ratios in prefrontal gray matter (PGM) and glutamate/glutamine(Glx)/Cr ratio in striatum, and increase of myo-inositol (mI)/Cr in striatum were observed during acute SIV infection. The metabolite alterations during the SIVsmmFGb infection are largely in agreement with previous findings in other non-human primate models and HIV patients. Also, NAA/Cr in PGM and striatum and Glx/Cr in striatum are negatively correlated with the percentage of CD8+ T cells after the SIV infection, suggesting the interaction between brain metabolite and immune dysfunction. The present study complements previous studies by describing the time course of alterations of brain metabolites during SIVsmmFGb infection. The findings further demonstrate the efficacy of the SIVsmmFGb-infected macaque as a model to characterize central nervous system infection using novel neuroimaging approaches and also as a tool for exploration of novel and advanced neuroimaging techniques in HIV/AIDS studies.

Cerebral metabolite changes prior to and after antiretroviral therapy in primary HIV infection

OBJECTIVE

We examined the longitudinal effects of primary HIV infection (PHI) and responses to early antiretroviral therapy (ART) on the brain using high-field magnetic resonance spectroscopy (MRS).

METHODS

Cerebral metabolites were measured longitudinally with 4T proton MRS and assessed for ART effects in participants with PHI. Levels of glutamate (Glu), N-acetylaspartate (NAA), myo-inositol (MI), and choline-containing metabolites (Cho) were measured relative to creatine + phosphocreatine (Cr) in anterior cingulate, basal ganglia, frontal white matter, and parietal gray matter.

RESULTS

Fifty-three participants recruited at median 3.7 months post HIV transmission were followed a median 6.0 months. A total of 23 participants initiated ART during follow-up. Prior to ART, increases per month were observed in Cho/Cr (slope = 0.0012, p = 0.005) and MI/Cr (slope = 0.0041, p = 0.005) in frontal white matter as well as increases in MI/Cr (slope = 0.0041, p < 0.001) and NAA/Cr (slope = 0.0024, p = 0.030) in parietal gray matter. After initiation of ART, prior positive slopes were no longer significantly different from zero, while Glu/Cr in basal ganglia decreased (slope = -0.0038, p = 0.031).

CONCLUSIONS

Early in HIV infection, increases of Cho/Cr and MI/Cr in treatment-naive participants suggest progressive inflammation and gliosis in the frontal white matter and parietal gray matter, which is attenuated after initiation of ART. Elevated baseline Glu/Cr in basal ganglia may signal excitotoxicity; its subsequent stabilization and downward trajectory with ART may lend further support for early ART initiation.

Can Speed of Processing Training Ameliorate Depressive Symptomatology in Adults with HIV?

Despite advances in combination Antiretroviral Therapy (cART), adults with HIV continue to experience cognitive impairments. In addition to these cognitive impairments, research suggests as many as 40% and 20% of adults with HIV are diagnosed with depression and anxiety, respectively. The impact of these cognitive and emotional deficits increases caregiver burden, impairs occupational and driving performance, contributes to poor emotional processing, increases cognitive complaints, and reduces quality of life. Fortunately, cognitive remediation therapy improves targeted cognitive abilities along with general cognitive processes. Speed of processing training, a type of cognitive remediation therapy, has been shown to improve cognitive performance on measures of visual attention, speed of processing, and timed-task performances. Furthermore, studies suggest that speed of processing training could also enhance neuromodulatory systems which have direct implications for improving mood functions (depression and anxiety). The benefits of the improvement in these cognitive and emotional systems are a decrease or slowing in cognitive decline along with the potential to protect against clinically significant depressive symptoms. Studies support the need for deeper investigation into the short-term and long-term benefits of speed of processing training as a behavioral adjunct for the pharmacologically-burdened HIV population.

Early suppressive antiretroviral therapy in HIV infection is associated with measurable changes in the corpus callosum

The purpose of this study was to examine the impact of early suppressive antiretroviral therapy (ART) on brain structure and neurocognitive outcomes. We conducted an observational study of subjects within 1 year of HIV infection. Ten ART-naïve and 10 ART-suppressed individuals were matched for age and infection duration and age-matched to 10 HIV-seronegative controls. Quantitative brain imaging and neurocognitive data were analyzed. Subjects on suppressive ART had diminished corpus callosum structural integrity on macromolecular and microstructural imaging, higher cerebrospinal fluid percent, higher depression scores, and lower functional performance. Early suppressive ART may alter the trajectory of neurological progression of HIV infection, particularly in the corpus callosum.

Dual-mixed HIV-1 coreceptor tropism and HIV-associated neurocognitive deficits

HIV coreceptor usage of CXCR4 (X4) is associated with decreased CD4+ T-cell counts and accelerated disease progression, but the role of X4 tropism in HIV-associated neurocognitive disorders (HAND) has not previously been described. This longitudinal study evaluated data on 197 visits from 72 recently HIV-infected persons who had undergone up to four sequential neurocognitive assessments over a median of 160 days (IQR, 138–192). Phenotypic tropism testing (Trofile ES, Monogram, Biosciences) was performed on stored blood samples. Multivariable mixed model repeated measures regression was used to determine the association between HAND and dual-mixed (DM) viral tropism, estimated duration of infection (EDI), HIV RNA, CD4 count, and problematic methamphetamine use. Six subjects (8.3 %) had DM at their first neurocognitive assessment and four converted to DM in subsequent sampling (for total of 10 DM) at a median EDI of 10.1 months (IQR, 7.2–12.2). There were 44 (61.1 %) subjects who demonstrated HAND on at least one study visit. HAND was associated with DM tropism (odds ratio, 4.4; 95 % CI, 0.9–20.5) and shorter EDI (odds ratio 1.1 per month earlier; 95 % CI, 1.0–1.2). This study found that recency of HIV-1 infection and the development of DM tropism may be associated with HAND in the relatively early stage of infection. Together, these data suggest that viral interaction with cellular receptors may play an important role in the early manifestation of HAND.

The role of neuroplasticity and cognitive reserve in aging with HIV: recommendations for cognitive protection and rehabilitation

By and large, the immune systems of people infected with HIV are being protected and maintained by advances in highly active antiretroviral therapy; as such, this is extending the lives of people into old age. Unfortunately, for many living with this disease, HIV is associated with neuroinflammation, co-morbidities, and accelerated aging which can compromise brain function, resulting in cognitive deficits. The purpose of this article is to highlight how to interpret these deficits within the framework of neuroplasticity and cognitive reserve for this clinical population. We suggest several recommendations for cognitive rehabilitation and mitigation such as addressing lifestyle factors, psychostimulants, cognitive remediation therapy, and treatment of depression and anxiety. Implications for nursing research and practice are posited.

Role of neuroimaging in HIV-associated neurocognitive disorders

Human immunodeficiency virus (HIV) enters the brain soon after seroconversion and can cause HIV-associated neurocognitive disorders (HAND). Although the more severe and progressive forms of HAND are less prevalent due to combination antiretroviral therapy (cART), ∼ 40% of HIV-infected (HIV+) patients continue to have cognitive impairment. Some HIV+ individuals who have effective plasma HIV-1 RNA suppression with cART still develop HAND. It is often difficult to diagnose HAND in the outpatient setting as detailed neuropsychological performance testing is required. Additional biomarkers that are relatively easy to obtain and clinically relevant are needed for assessing HIV-associated neuropathologic changes. Recently developed noninvasive magnetic resonance imaging (MRI) techniques have great potential to serve as biomarkers. The authors review the application of some of these neuroimaging techniques, magnetic resonance spectroscopy (MRS), volumetric MRI, diffusion tensor imaging (DTI), functional MRI (fMRI), in HIV+ individuals. Each of the neuroimaging methods offers unique insight into mechanisms underlying neuroHIV, could monitor disease progression, and may assist in evaluating the efficacy of particular cART regimens. It is hoped that considerable progress will continue to occur such that some of these neuroimaging methods will be incorporated across multiple sites and included in future HAND guidelines.

An overview of the biological and psychosocial context surrounding neurocognition in HIV

The presence of a psychiatric illness increases the risk of exposure to HIV and disease complications; however, effective treatments have substantially reduced mortality in adults with HIV. Despite such effective treatments, nearly half of adults with HIV experience neurocognitive deficits that can affect job-related and everyday tasks, thus reducing their quality of life. This article provides an overview of the context in which neurocognitive deficits occur in adults with HIV; it also includes implications for treatment and mitigation of such neurocognitive deficits. Understanding the underlying neurocognitive changes related to HIV can help psychiatric nurses provide better care to patients that may improve medication compliance and everyday functioning.

Δ(9)-Tetrahydrocannabinol treatment during human monocyte differentiation reduces macrophage susceptibility to HIV-1 infection

The major psychoactive component of marijuana, Δ(9)-tetrahydrocannabinol (THC), also acts to suppress inflammatory responses. Receptors for THC, CB1, CB2, and GPR55, are differentially expressed on multiple cell types including monocytes and macrophages, which are important modulators of inflammation in vivo and target cells for HIV-1 infection. Use of recreational and medicinal marijuana is increasing, but the consequences of marijuana exposure on HIV-1 infection are unclear. Ex vivo studies were designed to investigate effects on HIV-1 infection in macrophages exposed to THC during or following differentiation. THC treatment of primary human monocytes during differentiation reduced HIV-1 infection of subsequent macrophages by replication competent or single cycle CCR5 using viruses. In contrast, treatment of macrophages with THC immediately prior to or continuously following HIV-1 exposure failed to alter infection. Specific receptor agonists indicated that the THC effect during monocyte differentiation was mediated primarily through CB2. THC reduced the number of p24 positive cells with little to no effect on virus production per infected cell, while quantitation of intracellular viral gag pinpointed the THC effect to an early event in the viral life cycle. Cells treated during differentiation with THC displayed reduced expression of CD14, CD16, and CD163 and donor dependent increases in mRNA expression of selected viral restriction factors, suggesting a fundamental alteration in phenotype. Ultimately, the mechanism of THC suppression of HIV-1 infection was traced to a reduction in cell surface HIV receptor (CD4, CCR5 and CXCR4) expression that diminished entry efficiency.

HIV-associated neurocognitive disorder

Neurological involvement in HIV is often associated with cognitive impairment. Although severe and progressive neurocognitive impairment has become rare in HIV clinics in the era of potent antiretroviral therapy, most patients with HIV worldwide have poor outcomes on formal neurocognitive tests. In this Review, we describe the manifestations of HIV-associated neurocognitive disorder in the era of effective HIV therapy, outline diagnosis and treatment recommendations, and explore the research questions that remain. Although comorbid disorders, such as hepatitis C infection or epilepsy, might cause some impairment, their prevalence is insufficient to explain the frequency with which it is encountered. HIV disease markers, such as viral load and CD4 cell counts, are not strongly associated with ongoing impairment on treatment, whereas cardiovascular disease markers and inflammatory markers are. New cerebrospinal fluid and neuroimaging biomarkers are needed to detect and follow impairment. Ongoing research efforts to optimise HIV therapy within the CNS, and potentially to intervene in downstream mechanisms of neurotoxicity, remain important avenues for future investigation. Ultimately, the full control of virus in the brain is a necessary step in the goal of HIV eradication.

Cognitive Consequences of Aging with HIV: Implications for Neuroplasticity and Rehabilitation

Combination active antiretroviral therapy prevents HIV from replicating and ravaging the immune system, thus allowing people to age with this disease. Unfortunately, the synergistic effects of HIV and aging can predispose many to become more at-risk of developing cognitive deficits which can interfere with medical management, everyday functioning, and quality of life. The purpose of this article is to describe the role of cognitive reserve and neuroplasticity on cognitive functioning in those aging with this disease. Specifically, the role of environment and the health of these individuals can compromise cognitive functioning. Fortunately, some cognitive interventions such as prevention and management of co-morbidities, cognitive remediation therapy, and neurotropic medications may be of value in preventing and rehabilitating the cognitive consequences of aging with HIV. Novel approaches such as cognitive prescriptions, transcranial direct stimulation, and binaural beat therapy may also be considered as possible techniques for cognitive rehabilitation.

Real-world impact of neurocognitive deficits in acute and early HIV infection

The acute and early period of HIV-1 infection (AEH) is characterized by neuroinflammatory and immunopathogenic processes that can alter the integrity of neural systems and neurocognitive functions. However, the extent to which central nervous system changes in AEH confer increased risk of real-world functioning (RWF) problems is not known. In the present study, 34 individuals with AEH and 39 seronegative comparison participants completed standardized neuromedical, psychiatric, and neurocognitive research evaluations, alongside a comprehensive assessment of RWF that included cognitive symptoms in daily life, basic and instrumental activities of daily living, clinician-rated global functioning, and employment. Results showed that AEH was associated with a significantly increased risk of dependence in RWF, which was particularly elevated among AEH persons with global neurocognitive impairment (NCI). Among those with AEH, NCI (i.e., deficits in learning and information processing speed), mood disorders (i.e., Bipolar Disorder), and substance dependence (e.g., methamphetamine dependence) were all independently predictive of RWF dependence. Findings suggest that neurocognitively impaired individuals with AEH are at notably elevated risk of clinically significant challenges in normal daily functioning. Screening for neurocognitive, mood, and substance use disorders in AEH may facilitate identification of individuals at high risk of functional dependence who may benefit from psychological and medical strategies to manage their neuropsychiatric conditions.

HIV and neurocognitive dysfunction

The spectrum of HIV-associated neurocognitive disorder (HAND) has been dramatically altered in the setting of widely available effective antiretroviral therapy (ART). Once culminating in dementia in many individuals infected with HIV, HAND now typically manifests as more subtle, though still morbid, forms of cognitive impairment in persons surviving long-term with treated HIV infection. Despite the substantial improvement in severity of this disorder, the fact that neurologic injury persists despite ART remains a challenge to the community of patients, providers and investigators aiming to optimize quality of life for those living with HIV. Cognitive dysfunction in treated HIV may reflect early irreversible CNS injury accrued before ART is typically initiated, ongoing low-level CNS infection and progressive injury in the setting of ART, or comborbidities including effects of treatment which may confound the beneficial reduction in viral replication and immune activation effected by ART.

Early detection of simian immunodeficiency virus in the central nervous system following oral administration to rhesus macaques

The timing of HIV dissemination to the central nervous system (CNS) has the potential to have important implications regarding HIV disease progression and treatment. The earlier HIV enters the CNS the more difficult it might be to remove with antiretroviral therapy. Alternatively, HIV may only enter the CNS later in the course of disease as a result of disruption of the blood-brain-barrier. We utilized the simian immunodeficiency virus (SIV) infection of rhesus macaques to evaluate the oral route of infection and the subsequent spread of SIV to the CNS during the acute infection phase. A high dose oral SIV challenge was utilized to ensure a successful infection and permit the evaluation of CNS spread during the first 1–14 days post-infection. Ultrasensitive nested PCR was used to detect SIV gag DNA in the brains of macaques at 1–2 days post-infection and identified SIV gag DNA in the brain tissues from three of four macaques. This SIV DNA was also present following perfusion of the macaque brains, providing evidence that it was not residing in the circulating blood but in the brain tissue itself. The diversity of the viral envelope V1–V2 region at early times post-infection indicated that the brain viral variants were similar to variants obtained from lymph nodes. This genetic similarity between SIV obtained from lymphoid and brain tissues suggests that the founder population of viral species entered and subsequently spread without any evidence of brain-specific SIV selection. The relatively rapid appearance of SIV within the CNS tissue following oral transmission may also occur during HIV transmission where it may impact disease course as well as representing a challenge for long-term therapies and future viral eradication modalities.

Combinatorial assessments of brain tissue metabolomics and histopathology in rodent models of human immunodeficiency virus infection

Metabolites are biomarkers for a broad range of central nervous system disorders serving as molecular drivers and byproducts of disease pathobiology. However, despite their importance, routine measures of brain tissue metabolomics are not readily available based on the requirements of rapid tissue preservation. They require preservation by microwave irradiation, rapid freezing or other methods designed to reduce post mortem metabolism. Our research on human immunodeficiency virus type one (HIV-1) infection has highlighted immediate needs to better link histology to neural metabolites. To this end, we investigated such needs in well-studied rodent models. First, the dynamics of brain metabolism during ex vivo tissue preparation was shown by proton magnetic resonance spectroscopy in normal mice. Second, tissue preservation methodologies were assessed using liquid chromatography tandem mass spectrometry and immunohistology to measure metabolites and neural antigens. Third, these methods were applied to two animal models. In the first, immunodeficient mice reconstituted with human peripheral blood lymphocytes then acutely infected with HIV-1. In the second, NOD scid IL2 receptor gamma chain knockout mice were humanized with CD34+ human hematopoietic stem cells and chronically infected with HIV-1. Replicate infected animals were treated with nanoformulated antiretroviral therapy (nanoART). Results from chronic infection showed that microgliosis was associated with increased myoinostitol, choline, phosphocholine concentrations and with decreased creatine concentrations. These changes were partially reversed with nanoART. Metabolite responses were contingent on the animal model. Taken together, these studies integrate brain metabolomics with histopathology towards uncovering putative biomarkers for neuroAIDS.

Magnetic resonance spectroscopy to assess neuroinflammation and neuropathic pain

Proton magnetic resonance spectroscopy ((1)H MRS) has been applied to numerous clinical studies, especially for neurological disorders. This technique can non-invasively evaluate brain metabolites and neurochemicals in selected brain regions and is particularly useful for assessing neuroinflammatory disorders. Neurometabolites assessed with MRS include the neuronal markers N-acetylaspartate (NAA) and glutamate (Glu), as well as the glial marker myo-inositol (MI). Therefore, the concentrations of these metabolites typically correspond to disease severity and often correlate well with clinical variables in the various brain disorders. Neuroinflammation with activated astrocytes and microglia in brain disorders are often associated with elevated MI, and to a lesser extent elevated total creatine (tCr) and choline containing compounds (Cho), which are found in higher concentrations in glia than neurons, while neuronal injury is indicated by lower than normal levels of NAA and Glu. This review summarizes the neurometabolite abnormalities found in MRS studies performed in patients with neuroinflammatory disorders or neuropathic pain, which also may be associated with neuroinflammation. These brain disorders include multiple sclerosis, neuroviral infections (including Human Immunodeficiency virus and Hepatitis C), degenerative brain disorders (including Alzheimer's disease and Parkinson's disease), stimulant abuse (including methamphetamine and cocaine) as well as several chronic pain syndromes.

Activation of CCR2+ human proinflammatory monocytes by human herpesvirus-6B chemokine N-terminal peptide

Human monocytes expressing CCR2 with CD14 and CD16 can mediate antigen presentation, and promote inflammation, brain infiltration and immunosenescence. Recently identified roles are in human immunodeficiency virus infection, tuberculosis and parasitic disease. Human herpesvirus 6B (HHV-6B) encodes a chemokine, U83B, which is monospecific for CCR2, and is distinct from the related HHV-6A U83A, which activates CCR1, CCR4, CCR5, CCR6 and CCR8 on immune effector cells and dendritic cells. These differences could alter leukocyte-subset recruitment for latent/lytic replication and associated neuroinflammatory pathology. Therefore, cellular interactions between U83A and U83B could help dictate potential tropism differences between these viruses. U83A specificity is maintained in the 38-residue N-terminal spliced-truncated form. Here, we sought to determine the basis for the chemokine receptor specificity differences and identify possible applications. To do this we first analysed variation in a natural host population in sub-Saharan Africa where both viruses are equally prevalent and compared these to global strains. Analyses of U83 N-terminal variation in 112 HHV-6A and HHV-6B infections identified 6/38 U83A or U83B-specific residues. We also identified a unique single U83A-specific substitution in one U83B sequence, 'U83BA'. Next, the variation effects were tested by deriving N-terminal (NT) 17-mer peptides and assaying activation of ex vivo human leukocytes, the natural host and cellular target. Chemotaxis of CCR2+ leukocytes was potently induced by U83B-NT, but not U83BA-NT or U83A-NT. Analyses of the U83B-NT activated population identified migrated CCR2+, but not CCR5+, leukocytes. The U83BA-NT asparagine-lysine14 substitution disrupted activity, thus defining CCR2 specificity and acting as a main determinant for HHV-6A/B differences in cellular interactions. A flow-cytometry-based shape-change assay was designed, and used to provide further evidence that U83B-NT could activate CCR2+CD14+CD16+ monocytes. This defines a potential antiviral target for HHV-6A/B disease and novel peptide immunomodulator for proinflammatory monocytes.

Prevention, Rehabilitation, and Mitigation Strategies of Cognitive Deficits in Aging with HIV: Implications for Practice and Research

Highly active antiretroviral therapy has given the chance to those living with HIV to keep on living, allowing them the opportunity to age and perhaps age successfully. Yet, there are severe challenges to successful aging with HIV, one of which is cognitive deficits. Nearly half of those with HIV experience cognitive deficits that can interfere with everyday functioning, medical decision making, and quality of life. Given that cognitive deficits develop with more frequency and intensity with increasing age, concerns mount that as people age with HIV, they may experience more severe cognitive deficits. These concerns become especially germane given that by 2015, 50% of those with HIV will be 50 and older, and this older cohort of adults is expected to grow. As such, this paper focuses on the etiologies of such cognitive deficits within the context of cognitive reserve and neuroplasticity. From this, evidence-based and hypothetical prevention (i.e., cognitive prescriptions), rehabilitation (i.e., speed of processing training), and mitigation (i.e., spaced retrieval method) strategies are reviewed. Implications for nursing practice and research are posited.

Assessing and treating forgetfulness and cognitive problems in adults with HIV

In addition to the immune system, HIV affects the nervous system and the brain, producing neurological sequelae, often resulting in forgetfulness and cognitive problems. These problems can compromise medication adherence, interfere with instrumental activities of daily living such as driving and managing finances, increase dependency, and decrease quality of life. Cognitive problems emerge due to a variety of reasons; likewise, several evidence-based methods to mitigate causes and compensate for cognitive problems can be used alone or in combination. This article focuses on nonpathological, nondementia forgetfulness and cognitive problems. However, dementia must be considered and assessed as measured by marked cognitive decline over time. Methods for assessing and measuring forgetfulness and cognitive problems are provided. In addition, methods of treating nonpathological cognitive problems are provided, ranging from Recommended for Practice to Not Recommended for Practice. A case study is presented to demonstrate how to implement recommended treatment options.

Quantitative MRI Measures in SIV-Infected Macaque Brains

Multiple MRI modalities including Diffusion Tensor Imaging (DTI), perfusion MRI, in vivo MR Spectroscopy (MRS), volumetric MRI, contrast-enhanced MRI, and functional MRI have demonstrated abnormalities of the structural and functional integrity as well as neurochemical alterations of the HIV-infected central nervous system (CNS). MRI has been proposed as a robust imaging approach for the characterization of the stage of progression in HIV infection. However, the interpretation of the MRI findings of HIV patients is complicated by the fact that these clinical studies cannot readily be controlled. Simian immunodeficiency virus (SIV) infected macaques exhibit neuropathological symptoms similar to those of HIV patients, and are an important model for studying the course of CNS infection, cognitive impairment, and neuropathology of HIV disease as well as treatment efficacy. MRI of non-human primates (NHPs) is of limited benefit on most clinical scanners operating at or below 1.5 Tesla because this low field strength does not produce high-quality images of the relatively small NHP brain. Contemporary high field MRI (3T or more) for clinical use provides impressive sensitivity for magnetic resonance signal detection and is now accessible in many imaging centers and hospitals, facilitating the use of various MRI techniques in NHP studies. In this article, several high field MRI techniques and applications in macaque models of neuroAIDS are reviewed and the relation between quantitative MRI measures and blood T-cell alterations is discussed.