Can antiretroviral therapy prevent HIV-associated cognitive disorders?:

Cigarette smoking is associated with reduced neuroinflammation and better cognitive control in people living with HIV

People living with HIV (HIV+) are roughly twice as likely to smoke cigarettes (Smok+) as the general population. With the advent of effective antiretroviral therapies, it is increasingly important to understand the effects of chronic HIV infection and cigarette smoking on brain function and cognition since HIV+ individuals have heightened neuroinflammation and cognitive deficits even with such therapies. Based on prior studies demonstrating that smoking reduces a marker for neuroinflammation in HIV- individuals, we hypothesized that HIV+/Smok+ individuals would have less neuroinflammation and better cognitive control than HIV+/Smok- individuals. Fifty-nine participants (HIV-/Smok- [n = 16], HIV-/Smok+ [n=14], HIV+/Smok- [n = 18], and HIV+/Smok+ [n = 11]) underwent baseline eligibility tests, positron emission tomography (PET) scanning to determine levels of a marker for neuroinflammation, and assessment of cognitive control with the reverse-translated 5-choice continuous performance test (5C-CPT), with smokers having smoked to satiety prior to testing. For the PET data, a significant effect of smoking status on whole brain (WB) standardized uptake value (SUV) was found between HIV+/Smok+ and HIV+/Smok- participants (due to 18.8% lower WB SUV in the HIV+/Smok+ group). HIV+/Smok- participants exhibited a mean 13.5% higher WB SUV than HIV-/Smok- participants. For the 5C-CPT, HIV+/Smok+ participants performed significantly better than HIV+/Smok- participants (d prime), and HIV+/Smok- participants performed worse than HIV-/Smok- participants. Thus, HIV+/Smok+ individuals demonstrated lower levels of the neuroinflammation marker and better cognitive control than HIV+/Smok- individuals. Given that HIV+ individuals whose HIV is well-controlled can still have chronic neurocognitive complications, study results suggest possible paths for future research into nicotine-related treatments to prevent such complications.

Neuroinflammation: From Molecular Basis to Therapy

Neuroinflammatory conditions in the central nervous system (CNS) are implicated in the pathogenesis of several neuroimmune disorders such as acquired demyelinating syndromes, autoimmune encephalopathies, acute or chronic bacterial and viral CNS infections as well as multiple sclerosis (MS) [...].

Antiretroviral therapy improves neurocognitive impairment in people living with HIV? A meta-analysis

Objectives

Although effective antiretroviral therapy (ART) has been used for more than two decades, HIV-associated neurocognitive disorder remains prevalent. Thus, whether ART can improve neurocognitive impairment is controversial. This review aims to explore the effects of ART on cognitive impairment in people living with HIV (PLWH).

Methods

A systematic literature search was conducted in eight databases (PubMed, Embase, Web of Science, Cochrane Library, CNKI, VIP, China Biology Medicine disc, and WanFang) to identify studies that compare cognitive function between study groups who are administered and not administered ART. We searched for articles published up to April 2019. Article evaluation and data extraction were independently conducted by two reviewers.

Results

Sixteen articles (6,694 participants)—14 cross-sectional studies and 2 cohort studies—were included in this meta-analysis. The cross-sectional studies demonstrated that ART group did not perform better than the non-ART group (OR = 1.16; 95% CI, 1.03–1.30). However, the cohort studies reported a significant improvement in cognitive function at three months (OR = 4.01; 95% CI, 2.35–6.85) and six months (OR = 9.24; 95% CI, 1.71–49.96) after ART initiation compared with the baseline data. No significant cognitive improvement was found in participants younger than 55 years old, but the two cross-sectional studies showed that ART may improve cognitive function in PLWH under 65 years old with poor physical condition and immune status.

Conclusions

ART could improve cognitive function in PLWH with poor physical condition and immune status, but it does not considerably improve cognition in the entire PLWH population.

Objective memory as an indicator of functional impairment in native Spanish-speaking patients with HIV infection

Objective memory is one of the most affected cognitive areas in patients with HIV and perhaps one of the best predictors of daily functioning problems. Its relationship with biological markers, mood symptoms, and cognitive complaint is unclear and has received little attention in native Spanish-speakers. The goal of this study is to explore the relationships between the above-mentioned variables and their prediction of objective memory performance in native Spanish-speakers. HIV-related biological markers, mood symptoms, cognitive complaint, and objective memory were assessed in a sample native Spanish-speaking HIV patient with possible cognitive impairment. The results revealed deficit in short- and long-term memory while recognition was retained. Hierarchical regression analysis showed that the combination of independent variables significantly predicted performance in recognition, indicating that the pattern of impairment in short- and long-term memory is related to a difficulty to learn new information discriminately. The non-prediction of short- and long-term memory performance may be related to the inability to estimate the deficit in objective memory. These results show the need to perform specific interventions in mnesic processes, in view of the relation between this cognitive process and patients' daily functioning.

Cognitive Impairment in people living with HIV in the ART era: A Review

BACKGROUND

Cognitive disorders are a common issue impacting those living with human immunodeficiency virus (HIV). Effective antiretroviral treatment has lessened the severity but not the frequency of these impairments. Such deficits reduce quality of life and present a significant challenge to clinicians in the context of an ageing HIV population with a growing number of comorbidities.

SOURCES OF DATA

This review is based on recent published literature in the field of HIV-associated cognitive impairment (HAND).

AREAS OF AGREEMENT

The pathogenesis of HAND is multifactorial and can be categorized into HIV viral factors, antiretroviral factors and individual factors. The risk factors associated with HAND are well documented.

AREAS OF CONTROVERSY

The prevalence of HAND in HIV populations varies and is dependent on populations studied and assessment batteries used. Disease progression is poorly understood and has important implication for screening programmes. The relative contribution of pathogenic mechanisms causing HAND is unclear, but recent papers point to inflammation as a significant contributor.

GROWING AREAS

The role of psychiatric diseases, such as depression, in the development and maintenance of HAND has recently been examined and requires clinical consideration. Furthermore, as the HIV population ages, its clinical management faces new challenges.

AREAS TIMELY FOR DEVELOPING RESEARCH

Identifying biomarkers for HAND which are practical in a clinical setting and utilizing new imaging technologies to better monitor diagnosis and disease progression. Furthermore, the development of therapeutics targeting inflammation appears of increasing importance.

Aged Chinese-origin rhesus macaques infected with SIV develop marked viremia in absence of clinical disease, inflammation or cognitive impairment

BACKGROUND

Damage to the central nervous system during HIV infection can lead to variable neurobehavioral dysfunction termed HIV-associated neurocognitive disorders (HAND). There is no clear consensus regarding the neuropathological or cellular basis of HAND. We sought to study the potential contribution of aging to the pathogenesis of HAND. Aged (range = 14.7-24.8 year) rhesus macaques of Chinese origin (RM-Ch) (n = 23) were trained to perform cognitive tasks. Macaques were then divided into four groups to assess the impact of SIVmac251 infection (n = 12) and combined antiretroviral therapy (CART) (5 infected; 5 mock-infected) on the execution of these tasks.

RESULTS

Aged SIV-infected RM-Ch demonstrated significant plasma viremia and modest CSF viral loads but showed few clinical signs, no elevations of systemic temperature, and no changes in activity levels, platelet counts or weight. Concentrations of biomarkers of acute and chronic inflammation such as soluble CD14, CXCL10, IL-6 and TNF-α are known to be elevated following SIV infection of young adult macaques of several species, but concentrations of these biomarkers did not shift after SIV infection in aged RM-Ch and remained similar to mock-infected macaques. Neither acute nor chronic SIV infection or CART had a significant impact on accuracy, speed or percent completion in a sensorimotor test.

CONCLUSIONS

Viremia in the absence of a chronic elevated inflammatory response seen in some aged RM-Ch is reminiscent of SIV infection in natural disease resistant hosts. The absence of cognitive impairment during SIV infection in aged RM-Ch might be in part attributed to diminishment of some facets of the immunological response. Additional study encompassing species and age differences is necessary to substantiate this hypothesis.

Neurocognitive profile of HIV-positive adults on combined antiretroviral therapy: A single-centre study in Serbia

The advent of combined antiretroviral therapy (cART) has prolonged the life expectancy of HIV + individuals and decreased the incidence of HIV-associated dementia. However, milder forms of neurocognitive impairment remain common and are often associated with poor daily functioning and lower medication adherence. This paper presents a research aimed at exploring the cognitive status differences between HIV + subjects (N = 39) on cART therapy and a group of demographically comparable healthy subjects (N = 39) in Serbia. The significance of differences between the HIV + group and the healthy control group in performance in six cognitive domains was tested using the multivariate analysis of variance. Results showed a lower performance of the HIV + group in the domains of attention/working memory, and learning. HIV-related clinical variables were not significantly associated with cognitive performance. An older age in HIV + patients was significantly related to a lower performance in all six cognitive domains, as opposed to healthy subjects, implying a synergistic interaction between HIV and aging, resulting in accentuated cognitive difficulties. Our findings suggest that even with the absence of a subjective experience of cognitive deficits and with a good basic control of the illness, a certain degree of cognitive deficit can be observed in the tested group.

Using the pathogenic and nonpathogenic nonhuman primate model for studying non-AIDS comorbidities

With the advent of antiretroviral therapy that can control virus replication below the detection levels of conventional assays, a new clinical landscape of AIDS emerged, in which non-AIDS complications prevail over AIDS-defining conditions. These comorbidities are diverse and affect multiple organs, thus resulting in cardiovascular, kidney, neurocognitive and liver disease, osteopenia/osteoporosis, and cancers. A common feature of these conditions is that they are generally associated with accelerated aging. The mechanism behind these comorbidities is chronic excessive inflammation induced by HIV infection, which persists under antiretroviral therapy. Progressive simian immunodeficiency virus (SIV) infection of nonhuman primates (NHPs) closely reproduces these comorbidities and offers a simplified system in which most of the traditional human risk factors for comorbidities (i.e., smoking, hyperlipidemia) are absent. Additionally, experimental conditions can be properly controlled during a shorter course of disease for SIV infection. As such, NHPs can be employed to characterize new paradigms of AIDS pathogenesis and to test the efficacy of interventions aimed at alleviating non-AIDS-related comorbidities.

CCR2 on CD14(+)CD16(+) monocytes is a biomarker of HIV-associated neurocognitive disorders

Objective:

To evaluate C-C chemokine receptor type 2 (CCR2) on monocyte subsets as a prognostic peripheral blood biomarker of HIV-associated neurocognitive disorders (HAND).

Methods:

We characterized monocyte populations in HIV-infected individuals with and without HAND from 2 cohorts and assessed their transmigration across an in vitro model of the human blood-brain barrier (BBB). We examined CCR2 expression among the monocyte populations as a prognostic/predictive biomarker of HAND and its functional consequences in facilitating monocyte diapedesis.

Results:

We determined that CCR2 was significantly increased on CD14⁺CD16⁺ monocytes in individuals with HAND compared to infected people with normal cognition. CCR2 remained elevated irrespective of the severity of cognitive impairment, combined antiretroviral therapy status, viral load, and current or nadir CD4 T-cell count. There was no association between CCR2 on other monocyte populations and HAND. There was a functional consequence to the increase in CCR2, as CD14⁺CD16⁺ monocytes from individuals with HAND transmigrated across our model of the human BBB in significantly higher numbers in response to its ligand chemokine (C-C) motif ligand 2 (CCL2) compared to the cell migration that occurred in people with no cognitive deficits. It should be noted that our study had the limitation of a smaller sample size of unimpaired individuals. In contrast, there was no difference in the transmigration of other monocyte subsets across the BBB in response to CCL2 in seropositive individuals with or without HAND.

Conclusions:

Our findings indicate CCR2 on CD14⁺CD16⁺ monocytes is a novel peripheral blood biomarker of HAND.