Improved Cognitive Performance and Reduced Monocyte Activation in Virally Suppressed Chronic HIV After Dual CCR2 and CCR5 Antagonism

Unravelling the triad of neuroinvasion, neurodissemination, and neuroinflammation of human immunodeficiency virus type 1 in the central nervous system

Since the identification of human immunodeficiency virus type 1 (HIV-1) in 1983, many improvements have been made to control viral replication in the peripheral blood and to treat opportunistic infections. This has increased life expectancy but also the incidence of age-related central nervous system (CNS) disorders and HIV-associated neurodegeneration/neurocognitive impairment and depression collectively referred to as HIV-associated neurocognitive disorders (HAND). HAND encompasses a spectrum of different clinical presentations ranging from milder forms such as asymptomatic neurocognitive impairment or mild neurocognitive disorder to a severe HIV-associated dementia (HAD). Although control of viral replication and suppression of plasma viral load with combination antiretroviral therapy has reduced the incidence of HAD, it has not reversed milder forms of HAND. The objective of this review, is to describe the mechanisms by which HIV-1 invades and disseminates in the CNS, a crucial event leading to HAND. The review will present the evidence that underlies the relationship between HIV infection and HAND. Additionally, recent findings explaining the role of neuroinflammation in the pathogenesis of HAND will be discussed, along with prospects for treatment and control.

HIV-Associated Neurocognitive Disorder: A Look into Cellular and Molecular Pathology

Despite combined antiretroviral therapy (cART) limiting HIV replication to undetectable levels in the blood, people living with HIV continue to experience HIV-associated neurocognitive disorder (HAND). HAND is associated with neurocognitive impairment, including motor impairment, and memory loss. HIV has been detected in the brain within 8 days of estimated exposure and the mechanisms for this early entry are being actively studied. Once having entered into the central nervous system (CNS), HIV degrades the blood-brain barrier through the production of its gp120 and Tat proteins. These proteins are directly toxic to endothelial cells and neurons, and propagate inflammatory cytokines by the activation of immune cells and dysregulation of tight junction proteins. The BBB breakdown is associated with the progression of neurocognitive disease. One of the main hurdles for treatment for HAND is the latent pool of cells, which are insensitive to cART and prolong inflammation by harboring the provirus in long-lived cells that can reactivate, causing damage. Multiple strategies are being studied to combat the latent pool and HAND; however, clinically, these approaches have been insufficient and require further revisions. The goal of this paper is to aggregate the known mechanisms and challenges associated with HAND.

Cenicriviroc prevents dysregulation of astrocyte/endothelial cross talk induced by ischemia and HIV-1 via inhibiting the NLRP3 inflammasome and pyroptosis

Blood-brain barrier (BBB) breakdown is one of the pathophysiological characteristics of ischemic stroke, which may contribute to the progression of brain tissue damage and subsequent neurological impairment. Human immunodeficiency virus (HIV)-infected individuals are at greater risk for ischemic stroke due to diminished immune function and HIV-associated vasculopathy. Studies have shown that astrocytes are involved in maintaining BBB integrity and facilitating HIV-1 infection in the brain. The present study investigated whether targeting astrocyte-endothelial cell signaling with cenicriviroc (CVC), a dual chemokine receptor (CCR)2 and CCR5 antagonist, may protect against dysregulation of cross talk between these cells after oxygen-glucose deprivation/reoxygenation (OGD/R) combined with HIV-1 infection. Permeability assay with 10 kDa fluorescein isothiocyanate (FITC)-dextran demonstrated that CVC alleviated endothelial barrier disruption in noncontact coculture of human brain microvascular endothelial cells (HBMECs) with HIV-1-infected human astrocytes, and reversed downregulation of tight junction protein claudin-5 induced by OGD/R- and HIV-1. Moreover, CVC attenuated OGD/R- and HIV-1-triggered upregulation of the NOD-like receptor protein-3 (NLRP3) inflammasome and IL-1β secretion. Treatment with CVC also suppressed astrocyte pyroptosis by attenuating cleaved caspase-1 levels and the formation of cleaved N-terminal GSDMD (N-GSDMD). Secretome profiling revealed that CVC ameliorated secretion levels of chemokine CC chemokine ligand 17 (CCL17), adhesion molecule intercellular adhesion molecule-1 (ICAM-1), and T cell activation modulator T cell immunoglobulin and mucin domain 3 (TIM-3) by astrocytes synergistically induced by OGD/R and HIV-1. Overall, these results suggest that CVC contributes to restoring astrocyte-endothelial cross interactions in an astrocyte-dependent manner via protection against NLRP3 activation and pyroptosis.NEW & NOTEWORTHY The present study reveals the role of astrocytic NOD-like receptor protein-3 (NLRP3) inflammasome in dysfunctional astrocyte-endothelial cross interactions triggered in response to oxygen/glucose deprivation injury associated with human immunodeficiency virus type 1 (HIV-1) infection. Our results suggest that blocking NLRP3 inflammasome activation and pyroptosis-mediated inflammation with cenicriviroc (CVC) may constitute a potentially effective therapeutic strategy for blood-brain barrier (BBB) protection during HIV-1-associated ischemic stroke.

CCR5 regulates Aβ1-42-induced learning and memory deficits in mice

C-C chemokine receptor 5 (CCR5) is a chemokine receptor involved in immune responses and a co-receptor for HIV infection. Recently, CCR5 has also been reported to play a role in synaptic plasticity, learning and memory, and cognitive deficits associated with normal aging, traumatic brain injury (TBI), and HIV-associated neurocognitive disorder (HAND). In contrast, the role of CCR5 in cognitive deficits associated with other disorders, including Alzheimer's disease (AD), is much less understood. Studies have reported an increase in expression of CCR5 or its ligands in both AD patients and AD rodent models, suggesting a correlation between AD and CCR5 expression. However, whether blocking CCR5 in specific brain regions, such as the hippocampus, could improve memory deficits in AD mouse models is unknown. To study the potential causal role of CCR5 in cognitive deficits in AD, we injected soluble Aβ1-42 or a control (Aβ42-1) oligomers in the dorsal CA1 region of the hippocampus and found that Aβ1-42 injection resulted in severe memory impairment in the object place recognition (OPR) and novel object recognition (NOR) tests. Aβ1-42 injection caused an increase in Ccr5, Ccl3, and Ccl4 in the dorsal hippocampus, and the expression levels of CCR5 and its ligands remained elevated at 2 weeks after Aβ1-42 injection. Knocking down Ccr5 in the CA1 region of dorsal hippocampus reversed the increase in microglia number and size in dorsal CA1 and rescued memory deficits. These results indicate that CCR5 plays an important role in modulating Aβ1-42-induced learning and memory deficits, and suggest that CCR5 antagonists may serve as a potential treatment to improve cognitive deficits associated with AD.

Chemokine receptor 5 signaling in PFC mediates stress susceptibility in female mice

Chronic stress induces changes in the periphery and the central nervous system (CNS) that contribute to neuropathology and behavioral abnormalities associated with psychiatric disorders. In this study, we examined the impact of peripheral and central inflammation during chronic social defeat stress (CSDS) in female mice. Compared to male mice, we found that female mice exhibited heightened peripheral inflammatory response and identified C-C motif chemokine ligand 5 (CCL5), as a stress-susceptibility marker in females. Blocking CCL5 signaling in the periphery promoted resilience to CSDS. In the brain, stress-susceptible mice displayed increased expression of C-C chemokine receptor 5 (CCR5), a receptor for CCL5, in microglia in the prefrontal cortex (PFC). This upregulation was associated with microglia morphological changes, their increased migration to the blood vessels, and enhanced phagocytosis of synaptic components and vascular material. These changes coincided with neurophysiological alterations and impaired blood-brain barrier (BBB) integrity. By blocking CCR5 signaling specifically in the PFC were able to prevent stress-induced physiological changes and rescue social avoidance behavior. Our findings are the first to demonstrate that stress-mediated dysregulation of the CCL5-CCR5 axis triggers excessive phagocytosis of synaptic materials and neurovascular components by microglia, resulting in disruptions in neurotransmission, reduced BBB integrity, and increased stress susceptibility. Our study provides new insights into the role of cortical microglia in female stress susceptibility and suggests that the CCL5-CCR5 axis may serve as a novel sex-specific therapeutic target for treating psychiatric disorders in females.

The default mode network is affected in the early stage of simian immunodeficiency virus infection: a longitudinal study

Acquired immune deficiency syndrome infection can lead to cognitive dysfunction represented by changes in the default mode network. Most recent studies have been cross-sectional and thus have not revealed dynamic changes in the default mode network following acquired immune deficiency syndrome infection and antiretroviral therapy. Specifically, when brain imaging data at only one time point are analyzed, determining the duration at which the default mode network is the most effective following antiretroviral therapy after the occurrence of acquired immune deficiency syndrome. However, because infection times and other factors are often uncertain, longitudinal studies cannot be conducted directly in the clinic. Therefore, in this study, we performed a longitudinal study on the dynamic changes in the default mode network over time in a rhesus monkey model of simian immunodeficiency virus infection. We found marked changes in default mode network connectivity in 11 pairs of regions of interest at baseline and 10 days and 4 weeks after virus inoculation. Significant interactions between treatment and time were observed in the default mode network connectivity of regions of interest pairs area 31/V6.R and area 8/frontal eye field (FEF). L, area 8/FEF.L and caudal temporal parietal occipital area (TPOC).R, and area 31/V6.R and TPOC.L. ART administered 4 weeks after infection not only interrupted the progress of simian immunodeficiency virus infection but also preserved brain function to a large extent. These findings suggest that the default mode network is affected in the early stage of simian immunodeficiency virus infection and that it may serve as a potential biomarker for early changes in brain function and an objective indicator for making early clinical intervention decisions.

Chronic immune activation and gut barrier dysfunction is associated with neuroinflammation in ART-suppressed SIV+ rhesus macaques

HIV-associated neurocognitive disorders (HAND) affect ~40% of virally suppressed people with HIV (PWH), however, the precise viral dependent and independent changes to the brain are unclear. Here we characterized the CNS reservoir and immune environment of SIV-infected (SIV+) rhesus macaques during acute (n = 4), chronic (n = 12) or ART-suppressed SIV infection (n = 11). Multiplex immunofluorescence for markers of SIV infection (vRNA/vDNA) and immune activation was performed on frontal cortex and matched colon tissue. SIV+ animals contained detectable viral DNA+ cells that were not reduced in the frontal cortex or the gut by ART, supporting the presence of a stable viral reservoir in these compartments. SIV+ animals had impaired blood brain barrier (BBB) integrity and heightened levels of astrocytes or myeloid cells expressing antiviral, anti-inflammatory or oxidative stress markers which were not abrogated by ART. Neuroinflammation and BBB dysfunction correlated with measures of viremia and immune activation in the gut. Furthermore, SIV-uninfected animals with experimentally induced gut damage and colitis showed a similar immune activation profile in the frontal cortex to those of SIV-infected animals, supporting the role of chronic gut damage as an independent source of neuroinflammation. Together, these findings implicate gut-associated immune activation/damage as a significant contributor to neuroinflammation in ART-suppressed HIV/SIV infection which may drive HAND pathogenesis.

A Rationale and Approach to the Development of Specific Treatments for HIV Associated Neurocognitive Impairment

Neurocognitive impairment (NCI) associated with HIV infection of the brain impacts a large proportion of people with HIV (PWH) regardless of antiretroviral therapy (ART). While the number of PWH and severe NCI has dropped considerably with the introduction of ART, the sole use of ART is not sufficient to prevent or arrest NCI in many PWH. As the HIV field continues to investigate cure strategies, adjunctive therapies are greatly needed. HIV imaging, cerebrospinal fluid, and pathological studies point to the presence of continual inflammation, and the presence of HIV RNA, DNA, and proteins in the brain despite ART. Clinical trials exploring potential adjunctive therapeutics for the treatment of HIV NCI over the last few decades have had limited success. Ideally, future research and development of novel compounds need to address both the HIV replication and neuroinflammation associated with HIV infection in the brain. Brain mononuclear phagocytes (MPs) are the primary instigators of inflammation and HIV protein expression; therefore, adjunctive treatments that act on MPs, such as immunomodulating agents, look promising. In this review, we will highlight recent developments of innovative therapies and discuss future approaches for HIV NCI treatment.

Characterization of Circulating Fibrocytes in People Living with HIV on Stable Antiretroviral Therapy

Highly effective combination antiretroviral therapy has reduced HIV infection to a manageable chronic disease, shifting the clinical landscape toward management of noninfectious comorbidities in people living with HIV (PLWH). These comorbidities are diverse, generally associated with accelerated aging, and present within multiple organ systems. Mechanistically, immune dysregulation and chronic inflammation, both of which persist in PLWH with well-controlled virally suppressive HIV infection, are suggested to create and exacerbate noninfectious comorbidity development. Persistent inflammation often leads to fibrosis, which is the common end point pathologic feature associated with most comorbidities. Fibrocytes are bone marrow-derived fibroblast-like cells, which emerged as key effector cells in tissue repair and pathologic fibrotic diseases. Despite their relevance to fibrosis, the circulating fibrocyte concentration in PLWH remains poorly characterized, and an understanding of their functional role in chronic HIV is limited. In this study, utilizing PBMCs from a cross-sectional adult HIV cohort study with matched uninfected controls (HIV-), we aimed to identify and compare circulating fibrocytes in blood. Both the percentage and number of fibrocytes and α-smooth muscle actin+ fibrocytes in circulation did not differ between the HIV+ and HIV- groups. However, circulating fibrocyte levels were significantly associated with increasing age in both the HIV+ and HIV- groups (the percentage and number; r = 0.575, p ≤ 0.0001 and r = 0.558, p ≤ 0.0001, respectively). Our study demonstrates that circulating fibrocyte levels and their fibroblast-like phenotype defined as collagen I and α-smooth muscle actin+ expression are comparable between, and strongly associated with, age irrespective of HIV status.

The role of CCR5 in HIV-associated neurocognitive disorders

While combination antiretroviral therapy (cART) has successfully increased the lifespan of individuals infected with HIV, a significant portion of this population remains affected by HIV-associated neurocognitive disorder (HAND). C-C chemokine receptor 5 (CCR5) has been well studied in immune response and as a co-receptor for HIV infection. HIV-infected (HIV⁺) patients experienced mild to significant amelioration of cognitive function when treated with different CCR5 antagonists, including maraviroc and cenicriviroc. Consistent with clinical results, Ccr5 knockout or knockdown rescued cognitive deficits in HIV animal models, with mechanisms of reduced microgliosis and neuroinflammation. Pharmacologic inhibition of CCR5 directly improved cerebral and hippocampal neuronal plasticity and cognitive function. By summarizing the animal and human studies of CCR5 in HIV-associated cognitive deficits, this review aims to provide an overview of the mechanistic role of CCR5 in HAND pathophysiology. This review also discusses the addition of CCR5 antagonists, such as maraviroc, to cART for targeted prevention and treatment of cognitive impairments in patients infected with HIV.

Neuropathogenesis of HIV and emerging therapeutic targets

INTRODUCTION

HIV infection causes a wide range of neurological complications, many of which are among the most common complications of chronic HIV infection in the era of combined antiretroviral therapy. These neurological conditions arise due to complex interactions between HIV viral proteins and neuronal and glial cells that lead to the activation of various inflammatory and neurotoxic pathways across the nervous system.

AREAS COVERED

This review summarizes the current literature on the pathogenesis and clinical manifestations of neurological injuries associated with HIV in the brain, spinal cord, and peripheral nervous system. Molecular pathways relevant for possible therapeutic targets or advancements are emphasized. Gaps in knowledge and current challenges in therapeutic design are also discussed.

EXPERT OPINION

Several challenges exist in the development of therapeutic targets for HIV-associated cognitive impairments. However, recent developments in drug delivery systems and treatment strategies are encouraging. Treatments for HIV-associated pain and peripheral sensory neuropathies currently consist of symptomatic management, but a greater understanding of their pathogenesis can lead to the development of targeted molecular therapies and disease-modifying therapies. HIV-associated autonomic dysfunction may affect the course of systemic disease via disrupted neuro-immune interactions; however, more research is needed to facilitate our understanding of how these processes present clinically.

Targeting the CCL2-CCR2 axis for atheroprotection

Decades of research have established atherosclerosis as an inflammatory disease. Only recently though, clinical trials provided proof-of-concept evidence for the efficacy of anti-inflammatory strategies with respect to cardiovascular events, thus offering a new paradigm for lowering residual vascular risk. Efforts to target the inflammasome-interleukin-1β-interleukin-6 pathway have been highly successful, but inter-individual variations in drug response, a lack of reduction in all-cause mortality, and a higher rate of infections also highlight the need for a second generation of anti-inflammatory agents targeting atherosclerosis-specific immune mechanisms while minimizing systemic side effects. CC-motif chemokine ligand 2/monocyte-chemoattractant protein-1 (CCL2/MCP-1) orchestrates inflammatory monocyte trafficking between the bone marrow, circulation, and atherosclerotic plaques by binding to its cognate receptor CCR2. Adding to a strong body of data from experimental atherosclerosis models, a coherent series of recent large-scale genetic and observational epidemiological studies along with data from human atherosclerotic plaques highlight the relevance and therapeutic potential of the CCL2-CCR2 axis in human atherosclerosis. Here, we summarize experimental and human data pinpointing the CCL2-CCR2 pathway as an emerging drug target in cardiovascular disease. Furthermore, we contextualize previous efforts to interfere with this pathway, scrutinize approaches of ligand targeting vs. receptor targeting, and discuss possible pathway-intrinsic opportunities and challenges related to pharmacological targeting of the CCL2-CCR2 axis in human atherosclerotic disease.

Targeting C–C Chemokine Receptor 5: Key to Opening the Neurorehabilitation Window After Ischemic Stroke

Stroke is the world’s second major cause of adult death and disability, resulting in the destruction of brain tissue and long-term neurological impairment; induction of neuronal plasticity can promote recovery after stroke. C–C chemokine receptor 5 (CCR5) can direct leukocyte migration and localization and is a co-receptor that can mediate human immunodeficiency virus (HIV) entry into cells. Its role in HIV infection and immune response has been extensively studied. Furthermore, CCR5 is widely expressed in the central nervous system (CNS), is engaged in various physiological activities such as brain development, neuronal differentiation, communication, survival, and learning and memory capabilities, and is also involved in the development of numerous neurological diseases. CCR5 is differentially upregulated in neurons after stroke, and the inhibition of CCR5 in specific regions of the brain promotes motor and cognitive recovery. The mechanism by which CCR5 acts as a therapeutic target to promote neurorehabilitation after stroke has rarely been systematically reported yet. Thus, this review aims to discuss the function of CCR5 in the CNS and the mechanism of its effect on post-stroke recovery by regulating neuroplasticity and the inflammatory response to provide an effective basis for clinical rehabilitation after stroke.

Developments in Neuroprotection for HIV-Associated Neurocognitive Disorders (HAND)

PURPOSE OF REVIEW

Reducing the risk of HIV-associated neurocognitive disorders (HAND) is an elusive treatment goal for people living with HIV. Combination antiretroviral therapy (cART) has reduced the prevalence of HIV-associated dementia, but milder, disabling HAND is an unmet challenge. As newer cART regimens that more consistently suppress central nervous system (CNS) HIV replication are developed, the testing of adjunctive neuroprotective therapies must accelerate.

RECENT FINDINGS

Successes in modifying cART regimens for CNS efficacy (penetrance, chemokine receptor targeting) and delivery (nanoformulations) in pilot studies suggest that improving cART neuroprotection and reducing HAND risk is achievable. Additionally, drugs currently used in neuroinflammatory, neuropsychiatric, and metabolic disorders show promise as adjuncts to cART, likely by broadly targeting neuroinflammation, oxidative stress, aerobic metabolism, and/or neurotransmitter metabolism. Adjunctive cognitive brain therapy and aerobic exercise may provide additional efficacy. Adjunctive neuroprotective therapies, including available FDA-approved drugs, cognitive therapy, and aerobic exercise combined with improved cART offer plausible strategies for optimizing the prevention and treatment of HAND.

Plasma biomarker factors associated with neurodevelopmental outcomes in children with perinatal HIV infection and controlled viremia

OBJECTIVE

We examined relationships between plasma biomarkers and neurodevelopment in children from sub-Saharan Africa with perinatal HIV (PHIV) with controlled viremia on antiretroviral therapy (ART).

DESIGN

Longitudinal retrospective cohort study of children with controlled blood HIV replication.

METHODS

Children (N = 213; 57% girls) started ART at less than 3 years of age, had neurodevelopmental assessments (cognition, attention/impulsivity, motor proficiency, global executive functions) at 5-11 years, and achieved controlled viremia (HIV-1 RNA <400 copies/ml for ≥9 months before initial assessment). Twenty-three plasma biomarkers were measured at onset of controlled viremia, week 0 (first neurodevelopmental assessment), and week 48 (second neurodevelopmental assessment). Factor analysis was conducted at each time point. Multivariable linear regressions assessed associations between factors and neurodevelopmental scores.

RESULTS

Median age at week 0 was 7.0 years. Eighteen biomarkers loaded on six factors: a (L-10, IFNγ, IFNα2, IL-1β, IL-6, IP-10, TNFα); B (sCD163, sICAM-1, sVCAM-1, CRP); C (sE-selectin, sP-selectin); D [MIP-1β, vascular endothelial growth factor (VEGF)-A]; E (sCD14, CRP); and F (CX3CL1, MCP-1). Higher factor B scores were consistently associated with worse cognition and attention/impulsivity, and higher factor D scores with better attention/impulsivity.

CONCLUSION

These results suggest a detrimental effect of increased endothelial cell activation (sICAM-1, sVCAM-1) and monocyte/macrophage scavenger function (sCD163) and a beneficial effect of increased CCR5 ligand and HIV entry blocker MIP-1β and angiogenesis stimulant-VEGF concentrations on the neurodevelopment of children with PHIV. The model that emerges is of vascular inflammation leading to neurodevelopmental deficits. The role of persistent HIV replication in the central nervous system also needs to be further explored.

Non-human Primate Models to Investigate Mechanisms of Infection-Associated Fetal and Pediatric Injury, Teratogenesis and Stillbirth

A wide array of pathogens has the potential to injure the fetus and induce teratogenesis, the process by which mutations in fetal somatic cells lead to congenital malformations. Rubella virus was the first infectious disease to be linked to congenital malformations due to an infection in pregnancy, which can include congenital cataracts, microcephaly, hearing impairment and congenital heart disease. Currently, human cytomegalovirus (HCMV) is the leading infectious cause of congenital malformations globally, affecting 1 in every 200 infants. However, our knowledge of teratogenic viruses and pathogens is far from complete. New emerging infectious diseases may induce teratogenesis, similar to Zika virus (ZIKV) that caused a global pandemic in 2016-2017; thousands of neonates were born with congenital microcephaly due to ZIKV exposure in utero, which also included a spectrum of injuries to the brain, eyes and spinal cord. In addition to congenital anomalies, permanent injury to fetal and neonatal organs, preterm birth, stillbirth and spontaneous abortion are known consequences of a broader group of infectious diseases including group B streptococcus (GBS), Listeria monocytogenes, Influenza A virus (IAV), and Human Immunodeficiency Virus (HIV). Animal models are crucial for determining the mechanism of how these various infectious diseases induce teratogenesis or organ injury, as well as testing novel therapeutics for fetal or neonatal protection. Other mammalian models differ in many respects from human pregnancy including placentation, labor physiology, reproductive tract anatomy, timeline of fetal development and reproductive toxicology. In contrast, non-human primates (NHP) most closely resemble human pregnancy and exhibit key similarities that make them ideal for research to discover the mechanisms of injury and for testing vaccines and therapeutics to prevent teratogenesis, fetal and neonatal injury and adverse pregnancy outcomes (e.g., stillbirth or spontaneous abortion). In this review, we emphasize key contributions of the NHP model pre-clinical research for ZIKV, HCMV, HIV, IAV, L. monocytogenes, Ureaplasma species, and GBS. This work represents the foundation for development and testing of preventative and therapeutic strategies to inhibit infectious injury of human fetuses and neonates.

Cytokine-like protein 1-induced survival of monocytes suggests a combined strategy targeting MCL1 and MAPK in CMML

Mouse models of chronic myeloid malignancies suggest that targeting mature cells of the malignant clone disrupts feedback loops that promote disease expansion. Here, we show that in chronic myelomonocytic leukemia (CMML), monocytes that accumulate in the peripheral blood show a decreased propensity to die by apoptosis. BH3 profiling demonstrates their addiction to myeloid cell leukemia-1 (MCL1), which can be targeted with the small molecule inhibitor S63845. RNA sequencing and DNA methylation pattern analysis both point to the implication of the mitogen-activated protein kinase (MAPK) pathway in the resistance of CMML monocytes to death and reveal an autocrine pathway in which the secreted cytokine-like protein 1 (CYTL1) promotes extracellular signal-regulated kinase (ERK) activation through C-C chemokine receptor type 2 (CCR2). Combined MAPK and MCL1 inhibition restores apoptosis of monocytes from patients with CMML and reduces the expansion of patient-derived xenografts in mice. These results show that the combined inhibition of MCL1 and MAPK is a promising approach to slow down CMML progression by inducing leukemic monocyte apoptosis.

Higher circulating intermediate monocytes are associated with cognitive function in women with HIV

BACKGROUND

Identifying a quantitative biomarker of neuropsychiatric dysfunction in people with HIV (PWH) remains a significant challenge in the neuroHIV field. The strongest evidence to date implicates the role of monocytes in central nervous system (CNS) dysfunction in HIV, yet no study has examined monocyte subsets in blood as a correlate and/or predictor of neuropsychiatric function in virally suppressed PWH.

METHODS

In 2 independent cohorts of virologically suppressed women with HIV (vsWWH; n = 25 and n = 18), whole blood samples were obtained either in conjunction with neuropsychiatric assessments (neuropsychological [NP] test battery, self-report depression and stress-related symptom questionnaires) or 1 year prior to assessments. Immune cell subsets were assessed by flow cytometry.

RESULTS

A higher proportion of intermediate monocytes (CD14⁺CD16⁺) was associated with lower global NP function when assessing monocytes concurrently and approximately 1 year before (predictive) NP testing. The same pattern was seen for executive function (mental flexibility) and processing speed. Conversely, there were no associations with monocyte subsets and depression or stress-related symptoms. Additionally, we found that a higher proportion of classical monocytes was associated with better cognition.

CONCLUSION

Although it is widely accepted that lentiviral infection of the CNS targets cells of monocyte-macrophage-microglial lineage and is associated with an increase in intermediate monocytes in the blood and monocyte migration into the brain, the percentage of intermediate monocytes in blood of vsWWH has not been associated with neuropsychiatric outcomes. Our findings provide evidence for a new, easily measured, blood-based cognitive biomarker in vsWWH.

FUNDING

R01-MH113512, R01-MH113512-S, P30-AI094189, R01-MH112391, R01-AI127142, R00-DA044838, U01-AI35004, and P30-MH075673

Central Nervous System (CNS) Viral Seeding by Mature Monocytes and Potential Therapies To Reduce CNS Viral Reservoirs in the cART Era

We characterized mechanisms of CNS viral reservoir establishment/replenishment using peripheral blood mononuclear cells (PBMC) of PLWH on cART and propose therapeutic targets to reduce/block selective entry of cells harboring HIV (HIV⁺) into the CNS. Using DNA/RNAscope, we show that CD14⁺ CD16⁺ monocytes with integrated HIV, transcriptionally active, and/or with active viral replication from PBMC of PLWH prescribed cART and virally suppressed, selectively transmigrate across a human BBB model.

The human immunodeficiency virus (HIV) enters the central nervous system (CNS) within a few days after primary infection, establishing viral reservoirs that persist even with combined antiretroviral therapy (cART). We show that monocytes from people living with HIV (PLWH) on suppressive cART harboring integrated HIV, viral mRNA, and/or viral proteins preferentially transmigrate across the blood-brain barrier (BBB) to CCL2 and are significantly enriched post-transmigration, and even more highly enriched posttransmigration than T cells with similar properties. Using HIV-infected ART-treated mature monocytes cultured in vitro, we recapitulate these findings and demonstrate that HIV⁺ CD14⁺ CD16⁺ ART-treated monocytes also preferentially transmigrate. Cenicriviroc and anti-JAM-A and anti-ALCAM antibodies significantly and preferentially reduce/block transmigration of HIV⁺ CD14⁺ CD16⁺ ART-treated monocytes. These findings highlight the importance of monocytes in CNS HIV reservoirs and suggest targets to eliminate their formation and reseeding.

CNS Neurotoxicity of Antiretrovirals

The development of novel antiretroviral treatments has led to a significant turning point in the fight against HIV. Although therapy leads to virologic suppression and prolonged life expectancies, HIV-associated neurocognitive disorder (HAND) remains prevalent. While various hypotheses have been proposed to explain this phenomenon, a growing body of literature explores the neurotoxic effects of antiretroviral therapy. Research to date brings into question the potential role of such medications in neurocognitive and neuropsychiatric impairment seen in HIV-positive patients. This review highlights recent findings and controversies in cellular, molecular, and clinical neurotoxicity of antiretrovirals. It explores the pathogenesis of such toxicity and relates it to clinical manifestations in each medication class. The concept of accelerated aging in persons living with HIV (PLWH) as well as potential treatments for HAND are also discussed. Ultimately, this article hopes to educate clinicians and basic scientists about the neurotoxic effects of antiretrovirals and spur future scientific investigation into this important topic. Graphical Abstract.

Hepatitis C Virus Cure in Human Immunodeficiency Virus Coinfection Dampens Inflammation and Improves Cognition Through Multiple Mechanisms

BACKGROUND

Chronic inflammation in human immunodeficiency virus (HIV)/hepatitis C virus (HCV) coinfection increases cognitive impairment. With newer, direct-acting antiviral therapies for HCV, our objective was to determine whether chronic inflammation would be decreased and cognition improved with HCV sustained viral response (SVR) in coinfection.

METHODS

We studied 4 groups longitudinally: 7 HCV-monoinfected and 12 HIV/HCV-coinfected persons before and after treatment for HCV, 12 HIV-monoinfected persons, and 9 healthy controls. We measured monocyte activation and gene expression, monocyte-derived exosome micro-ribonucleic acid (miRNA) expression, plasma inflammation, and cognitive impairment before and after therapy.

RESULTS

Plasma soluble CD163 and neopterin were decreased in HCV mono- and coinfected persons. Blood CD16+ monocytes were decreased in coinfection after HCV treatment. Global deficit score improved 25% in coinfection with the visual learning/memory domain the most improved. Hepatitis C virus SVR decreased monocyte interferon genes MX1, IFI27, and CD169 in coinfection and MX1, LGALS3BP, and TNFAIP6 in HCV monoinfection. Monocyte exosomes from coinfected persons increased in microRNA (miR)-19a, miR-221, and miR-223, all of which were associated with decreasing inflammation and nuclear factor-κB activation.

CONCLUSIONS

Hepatitis C virus cure in coinfection brings monocyte activation to levels of HIV alone. Cognitive impairment is significantly improved with cure but not better than HIV infection alone, which strong suggests that cognitive impairment was driven by both HIV and HCV.SummaryHCV cure in HIV coinfection improves monocyte and plasma activation markers and increases cognitive function in the visual learning/memory domain.

Insight into the roles of CCR5 in learning and memory in normal and disordered states

As cognitive impairments continue to rise in prevalence, there is an urgent need to understand the mechanisms of learning and memory in normal and disordered states. C-C chemokine receptor 5 (CCR5) has been implicated in the regulation of multiple forms of learning and memory via its regulation on learning-related cell signaling and neuronal plasticity. As a chemokine receptor and a co-receptor for HIV, CCR5's role in immune response and HIV-associated neurocognitive disorder (HAND) has been widely studied. In contrast, CCR5 is less understood in cognitive deficits associated with other disorders, including Alzheimer's disease (AD), stroke and certain psychiatric disorders. A broad overview of the present literature shows that CCR5 acts as a potent suppressor of synaptic plasticity and learning and memory, although a few studies have reported the opposite effect of CCR5 in stroke or AD animal models. By summarizing the current literature of CCR5 in animal and human studies of cognition, this review aims to provide a comprehensive overview of the role of CCR5 in learning and memory in both normal and disordered states and to discuss the possibility of CCR5 suppression as an effective therapeutic to alleviate cognitive deficits in HAND, AD, and stroke.

Pathomechanisms of HIV-Associated Cerebral Small Vessel Disease: A Comprehensive Clinical and Neuroimaging Protocol and Analysis Pipeline

Rationale: We provide an in-depth description of a comprehensive clinical, immunological, and neuroimaging study that includes a full image processing pipeline. This approach, although implemented in HIV infected individuals, can be used in the general population to assess cerebrovascular health.

Aims: In this longitudinal study, we seek to determine the effects of neuroinflammation due to HIV-1 infection on the pathomechanisms of cerebral small vessel disease (CSVD). The study focuses on the interaction of activated platelets, pro-inflammatory monocytes and endothelial cells and their impact on the neurovascular unit. The effects on the neurovascular unit are evaluated by a novel combination of imaging biomarkers.

Sample Size: We will enroll 110 HIV-infected individuals on stable combination anti-retroviral therapy for at least three months and an equal number of age-matched controls. We anticipate a drop-out rate of 20%.

Methods and Design: Subjects are followed for three years and evaluated by flow cytometric analysis of whole blood (to measure platelet activation, platelet monocyte complexes, and markers of monocyte activation), neuropsychological testing, and brain MRI at the baseline, 18- and 36-month time points. MRI imaging follows the recommended clinical small vessel imaging standards and adds several advanced sequences to obtain quantitative assessments of brain tissues including white matter microstructure, tissue susceptibility, and blood perfusion.

Discussion: The study provides further understanding of the underlying mechanisms of CSVD in chronic inflammatory disorders such as HIV infection. The longitudinal study design and comprehensive approach allows the investigation of quantitative changes in imaging metrics and their impact on cognitive performance.

Peripheral immune dysregulation in the ART era of HIV-associated neurocognitive impairments: A systematic review

Human immunodeficiency virus-associated neurocognitive impairment (HANI) remains problematic despite the effective use of antiretroviral therapy (ART) and viral suppression. A dysregulated immune response contributes to the development of HANI but findings on the association between peripheral blood immune markers and HANI have been inconsistent. We therefore conducted a systematic review of studies of the association of peripheral blood immune markers with neurocognitive performance in ART experienced HIV-positive participants. Thirty-seven studies were eligible, including 12 longitudinal studies and 25 cross-sectional studies. Findings consistently show that HIV-positive participants have altered immune marker levels, including elevated markers of monocyte activation (neopterin, sCD14, sCD163) and inflammation (CCL2, IL-8, IL-18, IP-10, IFN-α, sTNFR-II and TNF-α). These elevated levels persist in HIV-positive participants despite ART. The majority of studies found associations of HANI with immune markers, including those linked to monocyte activation (sCD14 and sCD163) and inflammation (IL-18 and IP-10). Despite the heterogeneity of studies reviewed, due to the presence of raised peripheral markers, our narrative review provides evidence of chronic inflammation despite ART. The raised levels of these markers may suggest certain mechanisms are active, potentially those involved in the neuropathophysiology of HANI.

Effects of Internet Cognitive-Behavioral Therapy on Depressive Symptoms and Surrogates of Cardiovascular Risk in Human Immunodeficiency Virus: A Pilot, Randomized, Controlled Trial

Background

Depression is associated with an increased risk of cardiovascular disease in human immunodeficiency virus (HIV). We hypothesized that reducing depressive symptoms would improve HIV-related cardiovascular risk.

Methods

We conducted a single-center, randomized (1:1), controlled, parallel-group, assessor-blinded, pilot trial comparing Beating the Blues US (BtB)—an evidence-based, 8-session, internet cognitive-behavioral therapy for depression—with usual care (UC) in HIV-positive participants receiving virologically suppressive antiretroviral therapy and with Patient Health Questionnaire (PHQ)-9 scores ≥10. The primary endpoint was change in brachial artery flow-mediated dilation (FMD) at 12 weeks. Secondary endpoints were FMD change at 24 weeks and inflammation, coagulation, and metabolic biomarker changes at 12 and 24 weeks.

Results

Fifty-four participants were randomized (27 in each arm). Mean reductions in PHQ-9 scores were significantly greater with BtB versus UC at 12 weeks (−5.60 vs −1.52; P = .007) and 24 weeks (−6.00 vs −1.38; P = .008); reductions in the Hopkins Symptom Checklist Depression Scale-20 scores were also significantly greater with BtB versus UC at 24 weeks (−0.72 vs −0.35; P = .029). Changes in FMD between arms were not significantly different at 12 or 24 weeks. Significantly larger reductions in soluble (s)CD14 and sCD163 with BtB versus UC were found at 12 and 24 weeks, respectively.

Conclusions

Compared with UC, internet cognitive-behavioral therapy using BtB resulted in greater improvements in depressive symptoms and monocyte activation markers but did not improve FMD in this pilot trial. These data support performing larger studies to determine the potential salutatory effects of behavioral therapies for depression on HIV-related inflammation.

Pathogenesis of Aging and Age-related Comorbidities in People with HIV: Highlights from the HIV ACTION Workshop

People with HIV (PWH) experience accentuated biological aging, as defined by markers of inflammation, immune dysfunction, and the epigenetic clock. They also have an elevated risk of multiple age-associated comorbidities. To discuss current knowledge, research gaps, and priorities in aging and age-related comorbidities in treated HIV infection, the NIH program staff organized a workshop held in Bethesda, Maryland in September 2019. This review article describes highlights of discussions led by the Pathogenesis/Basic Science Research working group that focused on three high priority topics: immunopathogenesis; the microbiome/virome; and aging and senescence. We summarize knowledge in these fields and describe key questions for research on the pathogenesis of aging and age-related comorbidities in PWH. Understanding the drivers and mechanisms underlying accentuated biological aging is a high priority that will help identify potential therapeutic targets to improve healthspan in older PWH.

Role of T Lymphocytes in HIV Neuropathogenesis

PURPOSE OF REVIEW

The purpose of this review is to summarize the current knowledge on the role of CD4⁺ T lymphocytes leading to HIV assault and persistence in the central nervous system (CNS) and the elimination of HIV-infected CNS resident cells by CD8⁺ T lymphocytes.

RECENT FINDINGS

HIV targets the CNS early in infection, and HIV-infected individuals suffer from mild forms of neurological impairments even under antiretroviral therapy (ART). CD4⁺ T cells and monocytes mediate HIV entry into the brain and constitute a source for HIV persistence and neuronal damage. HIV-specific CD8⁺ T cells are also massively recruited in the CNS in acute infection to control viral replication but cannot eliminate HIV-infected cells within the CNS. This review summarizes the involvement of CD4⁺ T cells in seeding and maintaining HIV infection in the brain and describes the involvement of CD8⁺ T cells in HIV neuropathogenesis, playing a role still to be deciphered, either beneficial in eliminating HIV-infected cells or deleterious in releasing inflammatory cytokines.

Cenicriviroc, a dual CCR2 and CCR5 antagonist leads to a reduction in plasma fibrotic biomarkers in persons living with HIV on antiretroviral therapy

Background: Chronic HIV is associated with increased inflammation and tissue fibrosis despite suppressive antiretroviral therapy (ART). Monocytes and macrophages have been implicated in the pathogenesis of fibrosis, facilitated by chemokine receptor interactions.Methods: We assessed systemic fibrotic biomarkers (transforming growth factor beta-1 [TGF-β1], thrombospondin-1 [TSP-1], C-terminal pro-peptide of collagen type I [CICP], and IL-11) in banked plasma from a previously published 24-week open-label trial of cenicriviroc (CVC), a dual CCR2/CCR5 antagonist, among persons living with HIV (PLWH) on stable ART with undetectable plasma HIV RNA (<50 copies/mL). Fibrotic markers were assessed by ELISA and Luminex. Untreated HIV-seronegative individuals (n = 6) of similar age and demographics served as a comparator group.Results: Median age of PLWH was 55 years. At baseline, PLWH had higher median TGF-β1 (2.11 vs 1.62 ng/mL, p = 0.01), TSP-1 (236.74 vs 83.29 ng/mL, p < 0.0001), and CICP (200.46 vs 111.28 ng/mL, p = 0.01), but lower IL-11 (36.00 vs 53.74 pg/mL, p = 0.01) compared to HIV-uninfected individuals. Over 24 weeks, median TGF-β1 (-0.74 ng/mL, p = 0.006), TSP-1 (-52.12 ng/mL, p < 0.0001), and CICP (-28.12 ng/mL, p < 0.0001) decreased and IL-11 (28.98 pg/mL, p < 0.0001) increased in PLWH. At week 24, TGF-β1, CICP, and IL-11 were similar between the two groups (p > 0.05), while TSP-1 remained elevated in PLWH (p = 0.009) compared to controls.Conclusions: PLWH had higher levels of the plasma fibrotic markers TGF-β1, TSP-1, and CICP. After 24 weeks of CVC, fibrotic markers generally returned to levels comparable to HIV-uninfected controls. Dual CCR2 and CCR5 blockade may ameliorate the detrimental fibrotic events that persist in treated HIV.

Hippocampal CCR5/RANTES Elevations in a Rodent Model of Post-Traumatic Stress Disorder: Maraviroc (a CCR5 Antagonist) Increases Corticosterone Levels and Enhances Fear Memory Consolidation

BACKGROUND

Contextual fear conditioning (CFC) is a rodent model that induces a high and long-lasting level of conditioning associated with traumatic memory formation; this behavioral paradigm resembles many characteristics of posttraumatic stress disorder (PSTD). Chemokines (chemotactic cytokines) play a known role in neuronal migration and neurodegeneration but their role in cognition is not totally elucidated.

AIM

We ascertain whether CCR5/RANTES beta chemokines (hippocampus/prefrontal cortex) could play a role in fear memory consolidation (CFC paradigm). We also evaluated whether chronic stress restraint (21 days of restraint, 6-h/day) could regulate levels of these beta chemokines in CFC-trained rats; fear memory retention was determined taking the level of freezing (context and tone) by the animals as an index of fear memory consolidation 24 h after CFC training session; these chemokines (CCR5/RANTES) and IL-6 levels were measured in the hippocampus and prefrontal cortex of chronically stressed rats, 24 h after CFC post-training, and compared with undisturbed CFC-trained rats (Experiment 1). In Experiment 2, rats received 1 mA of footshock during the CFC training session and fear memory consolidation was evaluated at 12 and 24 h after CFC training sessions. We evaluated whether RANTES levels could be differentially regulated at 12 and 24 h after CFC training; in Experiment 3, maraviroc was administered to rats (i.m: 100 mg/Kg, a CCR5 antagonist) before CFC training. These rats were not subjected to chronic stress restraint. We evaluated whether CCR5 blockade before CFC training could increase corticosterone, RANTES, or IL-6 levels and affects fear memory consolidation in the rats 24-h post-testing compared with vehicle CFC-trained rats.

RESULTS

Elevations of CCR5/RANTES chemokine levels in the hippocampus could have contributed to fear memory consolidation (24 h post-training) and chronic stress restraint did not affect these chemokines in the hippocampus; there were no significant differences in CCR5/RANTES levels between stressed and control rats in the prefrontal cortex (Experiment 1). In Experiment 2, hippocampal CCR5/RANTES levels increased and enhanced fear memory consolidation was observed 12 and 24 h after CFC training sessions with 1 mA of footshock. Increased corticosterone and CCR5/RANTES levels, as well as a higher freezing percentage to the context, were found at 24 h CFC post-testing in maraviroc-treated rats as compared to vehicle-treated animals (experiment-3). Conversely, IL-6 is not affected by maraviroc treatment in CFC training.

CONCLUSION

Our findings suggest a role for a hippocampal CCR5/RANTES axis in contextual fear memory consolidation; in fact, RANTES levels increased at 12 and 24 h after CFC training. When CCR5 was blocked by maraviroc before CFC training, RANTES (hippocampus), corticosterone levels, and fear memory consolidation were greater than in vehicle CFC-trained rats 24 h after the CFC session.

Altered monocyte phenotype and dysregulated innate cytokine responses among people living with HIV and opioid-use disorder

Supplemental Digital Content is available in the text

Background:

Opioid-use disorders (OUD) and hepatitis C or B co-infection (HEP) are common among people living with HIV (PLHIV). The impact of OUD on innate and adaptive immunity among PLHIV with and without HEP is unknown.

Objectives:

To investigate the impact of OUD on monocyte and T-cell phenotypes, cytokine responses to lipopolysaccharide (LPS) and phytohemagglutinin (PHA), and plasma inflammatory markers, among PLHIV with and without HEP.

Methods:

Cross-sectional study enrolling PLHIV receiving ART, with and without OUD. Flow cytometry determined monocyte and T-cell phenotypes; LPS and PHA-induced cytokine production was assessed following LPS and PHA stimulation by multiplex cytokine array; plasma IL-6, soluble CD163, and soluble CD14 were measured by ELISA.

Results:

Twenty-two PLHIV with OUD and 37 PLHIV without OUD were included. PLHIV with OUD exhibited higher frequencies of intermediate (CD14⁺⁺CD16⁺) and nonclassical (CD14^dimCD16⁺) monocytes when compared with PLHIV without OUD (P = 0.0025; P = 0.0001, respectively), regardless of HEP co-infection. Soluble CD163 and monocyte cell surface CD163 expression was increased among PLHIV with OUD and HEP, specifically. Regardless of HEP co-infection, PLHIV with OUD exhibited reduced production of IL-10, IL-8, IL-6, IL-1alpha, and TNF-alpha in response to LPS when compared with PLHIV without OUD; PHA-induced production of IL-10, IL-1alpha, IL-1beta, IL-6, and TNF-alpha were also reduced among individuals with OUD.

Conclusion:

OUD among PLHIV are associated with altered monocyte phenotypes and a dysregulated innate cytokine response. Defining underlying mechanisms of opioid-associated innate immune dysregulation among PLHIV should be prioritized to identify optimal OUD treatment strategies.

Clinical significance of chemokine receptor antagonists

Introduction: Chemokine receptors are important therapeutic targets for the treatment of many human diseases. This study will provide an overview of approved chemokine receptor antagonists and promising candidates in advanced clinical trials.Areas covered: We will describe clinical aspects of chemokine receptor antagonists regarding their clinical efficacy, mechanisms of action, and re-purposed applications.Expert opinion: Three chemokine antagonists have been approved: (i) plerixafor is a small-molecule CXCR4 antagonist that mobilizes hematopoietic stem cells; (ii) maraviroc is a small-molecule CCR5 antagonist for anti-HIV treatment; and (iii) mogamulizumab is a monoclonal-antibody CCR4 antagonist for the treatment of mycosis fungoides or Sézary syndrome. Moreover, phase 3 trials are ongoing to evaluate many potent candidates, including CCR5 antagonists (e.g. leronlimab), dual CCR2/CCR5 antagonists (e.g. cenicriviroc), and CXCR4 antagonists (e.g. balixafortide, mavorixafor, motixafortide). The success of chemokine receptor antagonists depends on the selective blockage of disease-relevant chemokine receptors which are indispensable for disease progression. Although clinical translation has been slow, antagonists targeting chemokine receptors with multifaced functions offer the potential to treat a broad spectrum of human diseases.

New Potential Axes of HIV Neuropathogenesis with Relevance to Biomarkers and Treatment

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) affect approximately half of people living with HIV despite viral suppression with antiretroviral therapies and represent a major cause of morbidity. HAND affects activities of daily living including driving, using the Internet and, importantly, maintaining drug adherence. Whilst viral suppression with antiretroviral therapies (ART) has reduced the incidence of severe dementia, mild neurocognitive impairments continue to remain prevalent. The neuropathogenesis of HAND in the context of viral suppression remains ill-defined, but underlying neuroinflammation is likely central and driven by a combination of chronic intermittent low-level replication of whole virus or viral components, latent HIV infection, peripheral inflammation possibly from a disturbed gut microbiome or chronic cellular dysfunction in the central nervous system. HAND is optimally diagnosed by clinical assessment with imaging and neuropsychological testing, which can be difficult to perform in resource-limited settings. Thus, the identification of biomarkers of disease is a key focus of the field. In this chapter, recent advances in the pathogenesis of HAND and biomarkers that may aid its diagnosis and treatment will be discussed.

Clinical Treatment Options and Randomized Clinical Trials for Neurocognitive Complications of HIV Infection: Combination Antiretroviral Therapy, Central Nervous System Penetration Effectiveness, and Adjuvants

The etiology and pathogenesis of human immunodeficiency virus type-I (HIV)-associated neurocognitive disorders (HAND) remain undetermined and are likely the produce of multiple mechanisms. This can mainly include neuronal injury from HIV, inflammatory processes, and mental health issues. As a result, a variety of treatment options have been tested including NeuroHIV-targeted regimens based on the central nervous system (CNS) penetration effectiveness (CPE) of antiretroviral therapy (ART) and adjuvant therapies for HAND. NeuroHIV-targeted ART regimens have produced consistent and statistically significant HIV suppression in the CNS, but this is not the case for cognitive and functional domains. Most adjuvant therapies such as minocycline, memantine, and selegiline have negligible benefit in the improvement of cognitive function of people living with HIV (PLWH) with mild to moderate neurocognitive impairment. Newer experimental treatments have been proposed to target cognitive and functional symptoms of HAND as well as potential underlying pathogenesis. This review aims to provide an analytical overview of the clinical treatment options and clinical trials for HAND by focusing on NeuroHIV-targeted ART regimen development, CPE, and adjuvant therapies.

Dual CCR5/CCR2 targeting: opportunities for the cure of complex disorders

The chemokine system mediates acute inflammation by driving leukocyte migration to damaged or infected tissues. However, elevated expression of chemokines and their receptors can contribute to chronic inflammation and malignancy. Thus, great effort has been taken to target these molecules. The first hint of the druggability of the chemokine system was derived from the role of chemokine receptors in HIV infection. CCR5 and CXCR4 function as essential co-receptors for HIV entry, with the former accounting for most new HIV infections worldwide. Not by chance, an anti-CCR5 compound, maraviroc, was the first FDA-approved chemokine receptor-targeting drug. CCR5, by directing leukocytes to sites of inflammation and regulating their activation, also represents an important player in the inflammatory response. This function is shared with CCR2 and its selective ligand CCL2, which constitute the primary chemokine axis driving the recruitment of monocytes/macrophages to inflammatory sites. Both receptors are indeed involved in the pathogenesis of several immune-mediated diseases, and dual CCR5/CCR2 targeting is emerging as a more efficacious strategy than targeting either receptor alone in the treatment of complex human disorders. In this review, we focus on the distinctive and complementary contributions of CCR5 and CCR2/CCL2 in HIV infection, multiple sclerosis, liver fibrosis and associated hepatocellular carcinoma. The emerging therapeutic approaches based on the inhibition of these chemokine axes are highlighted.

The impact of substance abuse on HIV-mediated neuropathogenesis in the current ART era

Approximately 37 million people worldwide are infected with human immunodeficiency virus (HIV). One highly significant complication of HIV infection is the development of HIV-associated neurocognitive disorders (HAND) in 15-55% of people living with HIV (PLWH), that persists even in the antiretroviral therapy (ART) era. The entry of HIV into the central nervous system (CNS) occurs within 4-8 days after peripheral infection. This establishes viral reservoirs that may persist even in the presence of ART. Once in the CNS, HIV infects resident macrophages, microglia, and at low levels, astrocytes. In response to chronic infection and cell activation within the CNS, viral proteins, inflammatory mediators, and host and viral neurotoxic factors produced over extended periods of time result in neuronal injury and loss, cognitive deficits and HAND. Substance abuse is a common comorbidity in PLWH and has been shown to increase neuroinflammation and cognitive disorders. Additionally, it has been associated with poor ART adherence, and increased viral load in the cerebrospinal fluid (CSF), that may also contribute to increased neuroinflammation and neuronal injury. Studies have examined mechanisms that contribute to neuroinflammation and neuronal damage in PLWH, and how substances of abuse exacerbate these effects. This review will focus on how substances of abuse, with an emphasis on methamphetamine (meth), cocaine, and opioids, impact blood brain barrier (BBB) integrity and transmigration of HIV-infected and uninfected monocytes across the BBB, as well as their effects on monocytes/macrophages, microglia, and astrocytes within the CNS. We will also address how these substances of abuse may contribute to HIV-mediated neuropathogenesis in the context of suppressive ART. Additionally, we will review the effects of extracellular dopamine, a neurotransmitter that is increased in the CNS by substances of abuse, on HIV neuropathogenesis and how this may contribute to neuroinflammation, neuronal insult, and HAND in PLWH with active substance use. Lastly, we will discuss some potential therapies to limit CNS inflammation and damage in HIV-infected substance abusers.

Emerging medical therapies for non-alcoholic fatty liver disease and for alcoholic hepatitis

Non-alcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD) are currently the two most common liver diseases in the world. Alcoholic hepatitis (AH), a unique clinical syndrome among ALD patients has high short-term mortality. Apart from controlling the risk factor for individual respective disease, there are no Food and Drug Administration (FDA) approved medical therapies for these diseases. Over the last 5-10 years, the field has extensively grown with many new targets being studied in randomized clinical trials for these diseases, with many of these drugs being tested in both the conditions. In this chapter, we will describe the novel therapeutic agents and current status of ongoing clinical trials with these agents for the treatment of NAFLD and/or AH.

HIV-1 Tat promotes astrocytic release of CCL2 through MMP/PAR-1 signaling

The HIV-1 protein Tat is continually released by HIV-infected cells despite effective combination antiretroviral therapies (cART). Tat promotes neurotoxicity through enhanced expression of proinflammatory molecules from resident and infiltrating immune cells. These molecules include matrix metalloproteinases (MMPs), which are pathologically elevated in HIV, and are known to drive central nervous system (CNS) injury in varied disease settings. A subset of MMPs can activate G-protein coupled protease-activated receptor 1 (PAR-1), a receptor that is highly expressed on astrocytes. Although PAR-1 expression is increased in HIV-associated neurocognitive disorder (HAND), its role in HAND pathogenesis remains understudied. Herein, we explored Tat's ability to induce expression of the PAR-1 agonists MMP-3 and MMP-13. We also investigated MMP/PAR-1-mediated release of CCL2, a chemokine that drives CNS entry of HIV infected monocytes and remains a significant correlate of cognitive dysfunction in the era of cART. Tat exposure significantly increased the expression of MMP-3 and MMP-13. These PAR-1 agonists both stimulated the release of astrocytic CCL2, and both genetic knock-out and pharmacological inhibition of PAR-1 reduced CCL2 release. Moreover, in HIV-infected post-mortem brain tissue, within-sample analyses revealed a correlation between levels of PAR-1-activating MMPs, PAR-1, and CCL2. Collectively, these findings identify MMP/PAR-1 signaling to be involved in the release of CCL2, which may underlie Tat-induced neuroinflammation.

Nucleic acid testing and molecular characterization of HIV infections

Significant advances have been made in the molecular assays used for the detection of human immunodeficiency virus (HIV), which are crucial in preventing HIV transmission and monitoring disease progression. Molecular assays for HIV diagnosis have now reached a high degree of specificity, sensitivity and reproducibility, and have less operator involvement to minimize risk of contamination. Furthermore, analyses have been developed for the characterization of host gene polymorphisms and host responses to better identify and monitor HIV-1 infections in the clinic. Currently, molecular technologies including HIV quantitative and qualitative assays are mainly based on the polymerase chain reaction (PCR), transcription-mediated amplification (TMA), nucleic acid sequence-based amplification (NASBA), and branched chain (b) DNA methods and widely used for HIV detection and characterization, such as blood screening, point-of-care testing (POCT), pediatric diagnosis, acute HIV infection (AHI), HIV drug resistance testing, antiretroviral (AR) susceptibility testing, host genome polymorphism testing, and host response analysis. This review summarizes the development and the potential utility of molecular assays used to detect and characterize HIV infections.

Elevated cerebrospinal fluid Galectin-9 is associated with central nervous system immune activation and poor cognitive performance in older HIV-infected individuals

We previously reported that galectin-9 (Gal-9), a soluble lectin with immunomodulatory properties, is elevated in plasma during HIV infection and induces HIV transcription. The link between Gal-9 and compromised neuronal function is becoming increasingly evident; however, the association with neuroHIV remains unknown. We measured Gal-9 levels by ELISA in cerebrospinal fluid (CSF) and plasma of 70 HIV-infected (HIV+) adults stratified by age (older > 40 years and younger < 40 years) either ART suppressed or with detectable CSF HIV RNA, including a subgroup with cognitive assessments, and 18 HIV uninfected (HIV-) controls. Gal-9 tissue expression was compared in necropsy brain specimens from HIV- and HIV+ donors using gene datasets and immunohistochemistry. Among older HIV+ adults, CSF Gal-9 was elevated in the ART suppressed and CSF viremic groups compared to controls, whereas in the younger group, Gal-9 levels were elevated only in the CSF viremic group (p < 0.05). CSF Gal-9 positively correlated with age in all groups (p < 0.05). CSF Gal-9 tracked with CSF HIV RNA irrespective of age (β = 0.33; p < 0.05). Higher CSF Gal-9 in the older viremic HIV+ group correlated with worse neuropsychological test performance scores independently of age and CSF HIV RNA (p < 0.05). Furthermore, CSF Gal-9 directly correlated with myeloid activation (CSF-soluble CD163 and neopterin) in both HIV+ older groups (p < 0.05). Among HIV+ necropsy specimens, Gal-9 expression was increased in select brain regions compared to controls (p < 0.05). Gal-9 may serve as a novel neuroimmuno-modulatory protein that is involved in driving cognitive deficits in those aging with HIV and may be valuable in tracking cognitive abnormalities.

Cenicriviroc inhibits trans-endothelial passage of monocytes and is associated with impaired E-selectin expression

Incidences of cardiovascular diseases (CVD) are high among virologically suppressed HIV-infected individuals. Monocyte activation and trafficking are key mechanisms in the evolution of CVD. We studied the ability of cenicriviroc (CVC), a dual C-C chemokine receptor type 2 (CCR2) and CCR5 antagonist, to influence the migration of monocytes from HIV-infected individuals on antiretroviral therapy (ART). Monocytes were derived from 23 ART-suppressed HIV-infected and 16 HIV-uninfected donors. In a trans-endothelial migration model, monocytes, and human aortic endothelial cells (HAoECs) were exposed to cenicriviroc and migrated monocytes, quantified. Expression of CCR2 and CCR5 on monocytes and adhesion molecules (E-selectin, ICAM-1, VCAM-1, PECAM-1, and CD99) on HAoECs were measured. The single antagonists, BMS-22 (CCR2), and maraviroc (CCR5), served as controls. When both HAoECs and monocytes together were exposed to the antagonists, cenicriviroc led to a greater decrease in monocyte migration compared to BMS-22 or vehicle in both HIV-infected and HIV-uninfected groups (P < 0.05), with maraviroc having no inhibitory effect. Cenicriviroc treatment of HAoECs alone decreased monocyte migration in the HIV-infected group when compared to vehicle (P < 0.01). Inhibition of migration was not evident when monocytes alone were exposed to cenicriviroc, BMS-22 or maraviroc. Incubation of HAoECs with cenicriviroc decreased E-selectin expression (P = 0.045) but had limited effects on the other adhesion molecules. Cenicriviroc inhibits monocyte trans-endothelial migration more effectively than single chemokine receptor blockade, which may be mediated via disruption of monocyte-endothelial tethering through reduced E-selectin expression. Cenicriviroc should be considered as a therapeutic intervention to reduce detrimental monocyte trafficking.

APOBEC3G/3A Expression in Human Immunodeficiency Virus Type 1-Infected Individuals Following Initiation of Antiretroviral Therapy Containing Cenicriviroc or Efavirenz

Apolipoprotein B mRNA editing enzyme catalytic polypeptide-like 3 (APOBEC3) family members are cytidine deaminases that play crucial roles in innate responses to retrovirus infection. The mechanisms by which some of these enzymes restrict human immunodeficiency virus type 1 (HIV-1) replication have been extensively investigated in vitro. However, little is known regarding how APOBEC3 proteins affect the pathogenesis of HIV-1 infection in vivo and how antiretroviral therapy influences their expression. In this work, a longitudinal analysis was performed to evaluate APOBEC3G/3A expression in peripheral blood mononuclear cells of antiretroviral-naive HIV-1-infected individuals treated with cenicriviroc (CVC) or efavirenz (EFV) at baseline and 4, 12, 24, and 48 weeks post-treatment follow-up. While APOBEC3G expression was unaffected by therapy, APOBEC3A levels increased in CVC but not EFV arm at week 48 of treatment. APOBEC3G expression correlated directly with CD4⁺ cell count and CD4⁺/CD8⁺ cell ratio, whereas APOBEC3A levels inversely correlated with plasma soluble CD14. These findings suggest that higher APOBEC3G/3A levels may be associated with protective effects against HIV-1 disease progression and chronic inflammation and warrant further studies.