HIV Associated Risk Factors for Ischemic Stroke and Future Perspectives

Systematic review on cumulative HIV viraemia among people living with HIV receiving antiretroviral treatment and its association with mortality and morbidity

BACKGROUND

We performed a systematic review to generate evidence on the association between cumulative human immunodeficiency virus (HIV) viraemia and health outcomes.

METHODS

Quantitative studies reporting on HIV cumulative viraemia (CV) and its association with health outcomes among people living with HIV (PLHIV) on antiretroviral treatment (ART) were included. We searched MEDLINE via PubMed, Embase, Scopus and Web of Science and conference abstracts from 1 January 2008 to 1 August 2022.

RESULTS

The systematic review included 26 studies. The association between CV and mortality depended on the study population, methods used to calculate CV and its level. Higher CV was not consistently associated with greater risk of acquire immunodeficiency syndrome-defining clinical conditions. However, four studies present a strong relationship between CV and cardiovascular disease. The risk was not confirmed in relation of increased hazards of stroke. Studies that assessed the effect of CV on the risk of cancer reported a positive association between CV and malignancy, although the effect may differ for different types of cancer.

CONCLUSIONS

CV is associated with adverse health outcomes in PLHIV on ART, especially at higher levels. However, its role in clinical and programmatic monitoring and management of PLHIV on ART is yet to be established.

Risk of Stroke Among HIV Patients: A Systematic Review and Meta-analysis of Global Studies and Associated Comorbidities

BACKGROUND

Despite advancements in the management of HIV infection, the factors contributing to stroke development among HIV-positive individuals remain unclear. This systematic review and meta-analysis aim to identify and evaluate the relative risk factors associated with stroke susceptibility in the HIV population.

METHODS

A comprehensive search was conducted in PubMed, Scopus, and Web of Science databases to identify studies investigating the risk of stroke development in HIV patients and assessing the role of different risk factors, including hypertension, diabetes, dyslipidemia, smoking, sex, and race. The quality assessment of case-control studies was conducted using the Newcastle-Ottawa Scale, whereas cohort studies were assessed using the National Institute of Health tool. Meta-analyses were performed using a random-effects model to determine pooled hazard ratios (HRs) or odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

A total of 18 observational studies involving 116,184 HIV-positive and 3,184,245 HIV-negative patients were included. HIV-positive patients exhibited a significantly higher risk of stroke compared with HIV-negative patients [OR (95% CI): 1.31 (1.20 to 1.44)]. Subgroup analyses revealed increased risks for both ischemic stroke [OR (95% CI): 1.32 (1.19 to 1.46)] and hemorrhagic stroke [OR (95% CI): 1.31 (1.09 to 1.56)]. Pooled adjusted HRs showed a significant association between stroke and HIV positivity (HR: 1.37, 95% CI: 1.22 to 1.54). Among HIV-positive patients with stroke, hypertension [OR (95% CI): 3.5 (1.42 to 8.65)], diabetes [OR (95% CI): 5 (2.12 to 11.95)], hyperlipidemia, smoking, male gender, and black race were associated with an increased risk.

DISCUSSION

Our study revealed a significant increased risk of stroke development among people with HIV. A multitude of factors, encompassing sociodemographic characteristics, racial background, underlying health conditions, and personal behaviors, significantly elevate the risk of stroke in individuals living with HIV. The use of observational studies introduces inherent limitations, and further investigations are necessary to explore the underlying mechanisms of stroke in people with HIV for potential treatment strategies.

CONCLUSION

HIV patients face a higher risk of stroke development, either ischemic and hemorrhagic strokes. Hypertension, diabetes, hyperlipidemia, smoking, male gender, and black race were identified as significant risk factors. Early identification and management of these risk factors are crucial in reducing stroke incidence among patients living with HIV.

Characterizing blood pressure trajectories in people living with HIV following antiretroviral therapy: A systematic review

OBJECTIVES

The advent of antiretroviral therapy (ART) has reduced AIDS-related morbidity and mortality among people living with HIV (PLWH). Due to increased survival, PLWH have now been found to be at risk of chronic conditions related to ageing, such as cardiovascular disease (CVD). Hypertension is common in PLWH and is a major risk factor for the development of CVD. We conducted a systematic literature review to evaluate the research evidence on longitudinal blood pressure (BP) trajectories following ART initiation in PLWH.

METHODS

We searched the following databases: PubMed, CINHAL, Scopus, and Web of Science (up to 15 March 2021) for peer-reviewed published studies that reported BP trajectories following ART initiation in PLWH. Three reviewers independently screened all studies by title and abstract. We included articles in English, published up to March 2021, that report office BP trajectories in PLWH initiating ART. A total of 10 publications met our inclusion criteria. Eight studies were prospective cohorts and two were retrospective.

RESULTS

Nine out of 10 studies in the literature reported an increase in systolic BP (4.7-10.0 mmHg in studies with a follow-up range of 6 months to 8 years, and 3.0-4.7 mmHg/year in time-averaged studies). In addition, four out of 10 studies reported increases in diastolic BP (2.3-8.0 mmHg for a 6 month to 6.8-year follow-up range and 2.3 mmHg/year).

CONCLUSION

Systolic BP consistently increases while diastolic BP changes are more heterogeneous following ART initiation in PLWH. However, the studies were highly variable with respect to population demographics, ART regimen and duration, and follow-up time. Nevertheless, given the risks of CVD complications, such as stroke, heart failure and myocardial infarction, associated with elevated BP, results highlight the importance of future research in this area. It will be important to better characterize BP trajectories over time, identify the most critical times for interventions to reduce BP, determine the long-term CVD consequences in PLWH with elevated BP, and understand how different ART regimens may or may not influence BP and CVD disease.

Extracellular Vesicle-Serpine-1 Affects Neural Progenitor Cell Mitochondrial Networks and Synaptic Density: Modulation by Amyloid Beta and HIV-1

Brain endothelial extracellular vesicles carrying amyloid beta (EV-Aβ) can be transferred to neural progenitor cells (NPCs) leading to NPC dysfunction. However, the events involved in this EV-mediated Aβ pathology are unclear. EV-proteomics studies identified Serpine-1 (plasminogen activator inhibitor 1, PAI-1) as a major connecting "hub" on several protein-protein interaction maps. Serpine-1 was described as a key player in Aβ pathology and was linked to HIV-1 infection as well. Therefore, the aim of this work was to address the hypothesis that Serpine-1 can be transferred via EVs from brain endothelial cells (HBMEC) to NPCs and contribute to NPC dysfunction. HBMEC concentrated and released Serpine-1 via EVs, the effect that was potentiated by HIV-1 and Aβ. EVs loaded with Serpine-1 were readily taken up by NPCs, and HIV-1 enhanced this event. Interestingly, a highly specific Serpine-1 inhibitor PAI039 increased EV-Aβ transfer to NPCs in the presence of HIV-1. PAI039 also partially blocked mitochondrial network morphology alterations in the recipient NPCs, which developed mainly after HIV + Aβ-EV transfer. PAI039 partly attenuated HIV-EV-mediated decreased synaptic protein levels in NPCs, while increased synaptic protein levels in NPC projections. These findings contribute to a better understanding of the complex mechanisms underlying EV-Serpine-1 related Aβ pathology in the context of HIV infection. They are relevant to HIV-1 associated neurocognitive disorders (HAND) in an effort to elucidate the mechanisms of neuropathology in HIV infection.

Occludin: a gatekeeper of brain Infection by HIV-1

Compromised structure and function of the blood-brain barrier (BBB) is one of the pathological hallmarks of brain infection by HIV-1. BBB damage during HIV-1 infection has been associated with modified expression of tight junction (TJ) proteins, including occludin. Recent evidence indicated occludin as a redox-sensitive, multifunctional protein that can act as both an NADH oxidase and influence cellular metabolism through AMPK kinase. One of the newly identified functions of occludin is its involvement in regulating HIV-1 infection. Studies suggest that occludin expression levels and the rate of HIV-1 infection share a reverse, bidirectional relationship; however, the mechanisms of this relationship are unclear. In this review, we describe the pathways involved in the regulation of HIV-1 infection by occludin. We propose that occludin may serve as a potential therapeutic target to control HIV-1 infection and to improve the lives of people living with HIV-1.

The NLRP3 inflammasome and gut dysbiosis as a putative link between HIV-1 infection and ischemic stroke

HIV-associated comorbidities, such as ischemic stroke, are prevalent in people with HIV (PWH). Several studies both in animal models and humans have revealed an association between activation of the inflammasome in HIV-1 infection and stroke. The gut microbiota is an important component in controlling neuroinflammation in the CNS. It has also been proposed to be involved in the pathobiology of HIV-1 infection, and has been associated with an increase in activation of the inflammasome. In this review, we provide an overview of the microbiota-gut-inflammasome-brain axis, focusing on the NLRP3 inflammasome and dysregulation of the microbiome as risk factors that may contribute to the outcome of ischemic stroke and recovery in PWH. We also focus on the potential of targeting the NLRP3 inflammasome as a novel therapeutic approach for PWH who are at risk of developing cerebrovascular diseases.

Stroke in Young Adults

Stroke in young adults is associated with significant morbidity, and its prevalence is rising in the United States. This is partly attributed to a rise in the prevalence of traditional risk factors including hypertension, hypercholesterolemia, obesity, diabetes mellitus, smoking and heart disease. In addition, there are non-modifiable risk factors comprising migraine, pregnancy and postpartum state, illicit drug use, oral contraceptives and hypercoagulable state. The mechanisms causing stroke in young adults are unique and include cervical dissection, cardioembolic phenomenon, vasculitis and vasculopathy, connective tissue disease, patent foramen ovale and cerebral venous thrombosis. The diagnosis of stroke in the young population can be challenging given its myriad clinical presentations. In this document, we provide an overview of the epidemiology of stroke in young adults, explore mechanisms that may explain increasing rates of stroke in this population, and provide a critical updated overview of the existing literature on the management and prevention of stroke in young adults.

The epidemiology, mechanisms, diagnosis and treatment of cardiovascular disease in adult patients with HIV

More than 1.2 million people in the United States have Human Immunodeficiency Virus (HIV) infections but 13% of these people are unaware of their HIV infection. Current combination antiretroviral therapy (ART) does not cure HIV infection but rather suppresses the infection with the virus persisting indefinitely in latent reservoirs in the body. As a consequence of ART, HIV infection has changed from a fatal disease in the past to a chronic disease today. Currently in the United States, more than 45% of HIV+ individuals are greater than 50 years of age and 25% will be greater than 65 years of age by 2030. Atherosclerotic cardiovascular disease (CVD), including myocardial infarction, stroke, and cardiomyopathy, is now the major cause of death in HIV+ individuals. Novel risk factors, including chronic immune activation and inflammation in the body, antiretroviral therapy, and traditional CVD risk factors, such as tobacco and illicit drug use, hyperlipidemia, the metabolic syndrome, diabetes mellitus, hypertension, and chronic renal disease, contribute to cardiovascular atherosclerosis. This article discusses the complex interactions involving HIV infection, the novel and traditional risk factors for CVD, and the antiretroviral HIV therapies which can contribute to CVD in HIV-infected people. In addition, the treatment of HIV+ patients with acute myocardial infarction, stroke, and cardiomyopathy/heart failure are discussed. Current recommended ART and their major side effects are summarized in table format. All medical personnel must be aware of the increasing incidence of CVD on the morbidity and mortality in HIV infected patients and must be watchful for the presence of CVD in their patients with HIV.

Extracellular vesicles released from macrophages modulates interleukin-1β in astrocytic and neuronal cells

We have recently demonstrated that long-term exposure of cigarette smoke condensate (CSC) to HIV-uninfected (U937) and -infected (U1) macrophages induce packaging of pro-inflammatory molecules, particularly IL-1β, in extracellular vesicles (EVs). Therefore, we hypothesize that exposure of EVs derived from CSC-treated macrophages to CNS cells can increase their IL-1β levels contributing to neuroinflammation. To test this hypothesis, we treated the U937 and U1 differentiated macrophages once daily with CSC (10 µg/ml) for 7 days. Then, we isolated EVs from these macrophages and treated these EVs with human astrocytic (SVGA) and neuronal (SH-SY5Y) cells in the absence and presence of CSC. We then examined the protein expression of IL-1β and oxidative stress related proteins, cytochrome P450 2A6 (CYP2A6), superoxide dismutase-1 (SOD1), catalase (CAT). We observed that the U937 cells have lower expression of IL-1β compared to their respective EVs, confirming that most of the produced IL-1β are packaged into EVs. Further, EVs isolated from HIV-infected and uninfected cells, both in the absence and presence of CSC, were treated to SVGA and SH-SY5Y cells. These treatments showed a significant increase in the levels of IL-1β in both SVGA and SH-SY5Y cells. However, under the same conditions, the levels of CYP2A6, SOD1, and catalase were only markedly altered. These findings suggest that the macrophages communicate with astrocytes and neuronal cells via EVs-containing IL-1β in both HIV and non-HIV setting and could contribute to neuroinflammation.

Cardiovascular Disease and Thrombosis in HIV Infection

HIV infection has transitioned from an acute, fatal disease to a chronic one managed by antiretroviral therapy. Thus, the aging population of people living with HIV (PLWH) continues to expand. HIV infection results in a dysregulated immune system, wherein CD4+ T cells are depleted, particularly in the gastrointestinal tract, disrupting the gut epithelial barrier. Long-term HIV infection is associated with chronic inflammation through potentially direct mechanisms caused by viral replication or exposure to viral proteins and indirect mechanisms resulting from increased translocation of microbial products from the intestine or exposure to antiretroviral therapy. Chronic inflammation (as marked by IL [interleukin]-6 and CRP [C-reactive protein]) in PLWH promotes endothelial cell dysfunction and atherosclerosis. PLWH show significantly increased rates of cardiovascular disease, such as myocardial infarction (risk ratio, 1.79 [95% CI, 1.54-2.08]) and stroke (risk ratio, 2.56 [95% CI, 1.43-4.61]). In addition, PLWH have increased levels of the coagulation biomarker D-dimer and have a two to ten-fold increased risk of venous thromboembolism compared with the general population. Several small clinical trials analyzed the effect of different antithrombotic agents on platelet activation, coagulation, inflammation, and immune cell activation. Although some markers for coagulation were reduced, most agents failed to reduce inflammatory markers in PLWH. More studies are needed to understand the underlying mechanisms driving inflammation in PLWH to create better therapies for lowering chronic inflammation in PLWH. Such therapies can potentially reduce atherosclerosis, cardiovascular disease, and thrombosis rates in PLWH and thus overall mortality in this population.

Management of Pediatric Stroke - Challenges and Perspectives from Resource-limited Settings

Childhood stroke is not as common as adult stroke, but it is underrecognized the world over. Diagnosis is often delayed due to lack of awareness not only by the lay public but also by emergency and front-line health care workers. Despite the relative rarity of childhood stroke, the impact on morbidity, mortality and the economic burden for families and society is high, especially in poorly resourced settings. The risk factors for stroke in children differ from the adult population where lifestyle factors play a more important role. The developmental aspects of the pediatric cerebral vasculature and hematological maturational biology affects the clinical presentation, investigation, management and outcomes of childhood stroke in a different way compared to adults. The management of childhood stroke is currently based on expert guidelines and evidence extrapolated from adult studies. Hyperacute therapies that have revolutionized the treatment of stroke in adults cannot be easily applied to children at this stage due to the diagnostic delays, diverse risk factors and developmental considerations mentioned above. Much has been achieved in the understanding of genetic, acquired, preventable and recurrent stroke risk factors in the past decade through international collaborative efforts like the International Pediatric Stroke Study. Evidence for the prevention and treatment of childhood stroke remains elusive. Even more elusive are relevant and achievable management guidelines for pediatric stroke in resource-limited settings. This narrative review focusses on the current management practices globally, emphasizing the challenges, and gaps in knowledge of pediatric stroke in low- and middle-income countries and other areas with limited resources. Priorities and some potential solutions at national and local level are suggested for these settings.

Review of the neurological aspects of HIV infection

There are almost 40 million people in the world who live with the human immunodeficiency virus (HIV). The neurological manifestations associated with HIV contribute to significant morbidity and mortality despite the advances made with anti-retroviral therapy (ART). This review presents an approach to classification of neurological disorders in HIV, differentiating diseases due to the virus itself and those due to opportunistic infection. The effects of antiretroviral therapy are also discussed. The emphasis is on the developing world where advanced complications of HIV itself and infections such as tuberculosis (TB), toxoplasmosis and cryptococcal meningitis remain prevalent.