Co-receptor signaling in the pathogenesis of neuroHIV

Neuroinflammation: An Oligodendrocentric View

Chronic neuroinflammation, driven by central nervous system (CNS)-resident astrocytes and microglia, as well as infiltration of the peripheral immune system, is an important pathologic mechanism across a range of neurologic diseases. For decades, research focused almost exclusively on how neuroinflammation impacted neuronal function; however, there is accumulating evidence that injury to the oligodendrocyte lineage is an important component for both pathologic and clinical outcomes. While oligodendrocytes are able to undergo an endogenous repair process known as remyelination, this process becomes inefficient and usually fails in the presence of sustained inflammation. The present review focuses on our current knowledge regarding activation of the innate and adaptive immune systems in the chronic demyelinating disease, multiple sclerosis, and provides evidence that sustained neuroinflammation in other neurologic conditions, such as perinatal white matter injury, traumatic brain injury, and viral infections, converges on oligodendrocyte injury. Lastly, the therapeutic potential of targeting the impact of inflammation on the oligodendrocyte lineage in these diseases is discussed.

Human Microglia Models for NeuroHIV

Microglia are the primary target and reservoir of HIV infection in the central nervous system (CNS), which contributes to HIV-associated neurocognitive disorder (HAND). However, studying HIV infection of microglia has been challenged by the limited availability of primary human microglial cells. To overcome this issue, investigators have developed various microglial models for HIV studies, including immortalized human microglial cell lines, HIV latently infected microglial clones, peripheral blood monocyte-derived microglia (MMG), induced pluripotent stem cell (iPSC)-derived microglia (iMg), and microglia-containing cerebral organoids (MCOs) from iPSCs. Though these models have been used in many laboratories, the published data about their expression of the specific human microglia markers and the HIV entry receptors are conflicting. In addition, there is limited information about their feasibility and applicability as a suitable model for acute and/or latent HIV infection. This review provides a concise summary of the currently used human microglial models, with a focus on their suitability for NeuroHIV research.

Osteopontin as a potential mediator of inflammation in HIV and comorbid conditions

INTRODUCTION

Approximately 39 million people live with HIV globally, with 1.3 million new infections annually. Despite improved treatment, noncommunicable diseases (NCDs) such as cardiovascular disease (CVD), neurological disorders, chronic kidney disease (CKD), and cancer are now the leading causes of death among people with HIV (PWH). Osteopontin (OPN) has emerged as a notable mediator in the inflammatory response to HIV and related NCDs. Our aim is to review the current understanding of OPN's role in HIV-related inflammatory pathways to highlight potential therapeutic avenues for improved treatment and mitigation of comorbidities.

METHODS

We conducted a systematic review by searching relevant literature using specific keywords related to HIV, osteopontin, cardiovascular disease, inflammation, neurological disorders, cancer, and chronic kidney disease. The collected studies were organized and categorized by key themes, followed by a comprehensive analysis to identify patterns and draw conclusions regarding OPN's role in HIV-associated comorbidities.

RESULTS

The intricate interactions between OPN, its isoforms, and HIV-related illnesses suggest that OPN can exhibit both pro-inflammatory and anti-inflammatory roles, depending on the stage of the disease and the specific cell type involved. Its functions are diverse throughout the progression of HIV and its associated comorbidities, including CVD, CKD, cancer, and neurological disorders.

CONCLUSION

OPN's effects on the disease progression of HIV and related NCDs are highly variable due to its diverse functions. Therefore, further research is essential to fully understand its complex roles before considering OPN as a therapeutic target for HIV and its comorbidities.

EphB2-mediated ephrin-B reverse signaling on microglia drives an anti-viral, but inflammatory and neurotoxic response associated with HIV

Background: Pathological inflammation with a loss of synaptic integrity and function has been implicated in HIV Associated Neurocognitive Disorders (HAND). Although therapeutics exist to increase the lifespan of people living with HIV (PLWH), they are not effective at preventing neuroinflammation and HIV induced neuronal damage persists. In this study, we investigate the ephrin-B/EphB axis, which regulates inflammation, in post-mortem brain specimen of PLWH and experimental models in order to assess its potential role in HIV induced neuroinflammation. Methods: We analyze mRNA samples of post-mortem brain specimen of PLWH and uninfected controls obtained from the National NeuroAIDS Tissue Consortium (NNTC) and, for comparison, of a transgenic mouse model of neuroHIV using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Follow-up experiments employ mouse brain tissue and in vitro models, including immortalized human microglia, human induced pluripotent stem cell (iPSC)-derived mixed neuroglial cell cultures, cellular and molecular interference, functional and multiplex assays, immunofluorescence and mRNA sequencing to examine the role of the ephrin-B/EphB axis in neuroinflammation and the associated neurotoxicity. Results: Using qRT-PCR we find increased expression of EphB2 in post-mortem brain of PLWH, and detect a correlation with pro-viral DNA, viral RNA and an inverse correlation with abstract executive function and verbal fluency. Increased expression of ephrin-B/EphB at mRNA and protein level is also observed in brains of a transgenic mouse model of neuroHIV suggesting the upregulation can be driven, at least in part, by expression of viral gp120 envelope protein and a type I interferon, IFNβ. Additionally, we find induction of ephrin-B1 expression in microglia following activation by IFNβ. Given the previously reported impact of EphB2 on inflammation in the periphery, the functional role of EphB2-mediated ephrin-B reverse signaling on microglia is assessed for a pro-inflammatory and anti-viral signature. We find that EphB2 treated microglia secrete inflammatory and anti-viral factors but also exert contact-independent neurotoxicity. Finally, knockdown of microglial ephrin-B1, an EphB2 binding partner, shows a partial alleviation of the microglial pro-inflammatory signature and neurotoxicity. Conclusion: Our study suggests that elevated EphB2, and its reverse signaling through ephrin-B1 in microglia contribute to neuroinflammation and neurotoxicity in neuroHIV.

HIV Cerebrospinal Fluid Escape: Interventions for the Management, Current Evidence and Future Perspectives

Neurocognitive impairment is an important cause of HIV-associated morbidity. The advent of antiretroviral therapy (ART) has shifted the spectrum of HIV-associated cognitive impairment from HIV-associated dementia to milder forms of cognitive impairment. Independent replication of HIV within the central nervous system in those on effective ART with peripheral suppression is a recognised phenomenon known as cerebrospinal fluid (CSF) HIV RNA escape. CSF HIV RNA escape is independently associated with neurocognitive impairment but has also been detected in asymptomatic persons with HIV. The current consensus for management of CSF HIV RNA escape is based on expert opinion rather than empirical evidence. The current evidence suggests having a low threshold to investigate for CSF HIV RNA escape and optimising ART based on resistance profiles. The use of central nervous system (CNS) penetration effectiveness scores is no longer recommended. The evidence for statins, SSRIs, minocycline, lithium and valproate is limited to small-scale studies. There are potential new developments in the form of nanoparticles, Janus Kinase inhibitors and latency reversal agents.

Development and therapeutic perspectives of CXCR4 antagonists for disease therapy

Chemokine receptor 4 (CXCR4) is a subtype receptor protein of the GPCR family with a seven-transmembrane structure widely distributed in human tissues. CXCR4 is involved in diseases (e.g., HIV-1 infection), cancer proliferation and metastasis, inflammation signaling pathways, and leukemia, making it a promising drug target. Clinical trials on CXCR4 antagonists mainly focused on peptides and antibodies, with a few small molecule compounds, such as AMD11070 (2) and MSX-122 (3), showing promise in cancer treatment. This perspective discusses the structure-activity relationship (SAR) of CXCR4 and its role in diseases, mainly focusing on the SAR of CXCR4 antagonists. It also explores the standard structural features and target interactions of CXCR4 binding in different disease categories. Furthermore, it investigates various modification strategies to propose potential improvements in the effectiveness of CXCR4 drugs.

Adult Human Brain Tissue Cultures to Study NeuroHIV

HIV-associated neurocognitive disorders (HAND) persist under antiretroviral therapy as a complex pathology that has been difficult to study in cellular and animal models. Therefore, we generated an ex vivo human brain slice model of HIV-1 infection from surgically resected adult brain tissue. Brain slice cultures processed for flow cytometry showed >90% viability of dissociated cells within the first three weeks in vitro, with parallel detection of astrocyte, myeloid, and neuronal populations. Neurons within brain slices showed stable dendritic spine density and mature spine morphologies in the first weeks in culture, and they generated detectable activity in multi-electrode arrays. We infected cultured brain slices using patient-matched CD4+ T-cells or monocyte-derived macrophages (MDMs) that were exposed to a GFP-expressing R5-tropic HIV-1 in vitro. Infected slice cultures expressed viral RNA and developed a spreading infection up to 9 days post-infection, which were significantly decreased by antiretrovirals. We also detected infected myeloid cells and astrocytes within slices and observed minimal effect on cellular viability over time. Overall, this human-centered model offers a promising resource to study the cellular mechanisms contributing to HAND (including antiretroviral toxicity, substance use, and aging), infection of resident brain cells, and new neuroprotective therapeutics.

Non-Coding RNAs in HIV Infection, NeuroHIV, and Related Comorbidities

NeuroHIV affects approximately 30-60% of people living with HIV-1 (PLWH) and is characterized by varying degrees of cognitive impairments, presenting a multifaceted challenge, the underlying cause of which is chronic, low-level neuroinflammation. Such smoldering neuroinflammation is likely an outcome of lifelong reliance on antiretrovirals coupled with residual virus replication in the brains of PLWH. Despite advancements in antiretroviral therapeutics, our understanding of the molecular mechanism(s) driving inflammatory processes in the brain remains limited. Recent times have seen the emergence of non-coding RNAs (ncRNAs) as critical regulators of gene expression, underlying the neuroinflammatory processes in HIV infection, NeuroHIV, and their associated comorbidities. This review explores the role of various classes of ncRNAs and their regulatory functions implicated in HIV infection, neuropathogenesis, and related conditions. The dysregulated expression of ncRNAs is known to exacerbate the neuroinflammatory responses, thus contributing to neurocognitive impairments in PLWH. This review also discusses the diagnostic and therapeutic potential of ncRNAs in HIV infection and its comorbidities, suggesting their utility as non-invasive biomarkers and targets for modulating neuroinflammatory pathways. Understanding these regulatory roles could pave the way for novel diagnostic strategies and therapeutic interventions in the context of HIV and its comorbidities.

Molecular Role of HIV-1 Human Receptors (CCL5-CCR5 Axis) in neuroAIDS: A Systematic Review

Chronic HIV-1 infection can cause neurological illness, also known as HIV-associated neurocognitive disorders (HAND). The elevated level of pro-inflammatory cytokines and chemokines, such as C-C Chemokine Ligand 5 (CCL5/RANTES), is one of the ways of causing HIV-1-mediated neuroinflammation. C-C Chemokine Receptor 5 (CCR5) is the main coreceptor for viral entry into host cells and for mediating induction of CCL5/RANTES. CCR5 and CCL5 are part of a correlated axis of immune pathways used for effective protection against the HIV-1 virus. The purpose of this paper was to review the literary knowledge about the immunopathological relationship between this immune complex and neuroAIDS. A systematic review of the literature was conducted based on the selection and search of articles, available in English, Spanish, or Portuguese in the time frame of 1990-2022, of primary and secondary types in the PUBMED, Science Direct, SciELO, and LILACS databases through descriptors (MeSH) together with "AND": "CCR5"; "CCL5"; "neurological manifestations"; or "HIV". The methodological quality of the articles was assessed using the JBI Checklists and the PRISMA 2020 writing guidelines were followed. A total of 36 articles were included in the final composition of the review. The main cells of the CNS affected by neuroAIDS are: neurons; microglia; astrocytes; and oligodendrocytes. Molecular devices and their associations with cellular injuries have been described from the entry of the virus into the host's CNS cell to the generation of mental disorders. Furthermore, divergent results were found about the levels of CCL5/RANTES secretion and the generation of immunopathogenesis, while all condensed research for CCR5 indicated that elevation of this receptor causes more neurodegenerative manifestations. Therefore, new therapeutic and interventional strategies can be conditioned on the immunological direction proposed in this review for the disease.

Microglial- neuronal crosstalk in chronic viral infection through mTOR, SPP1/OPN and inflammasome pathway signaling

HIV-infection of microglia and macrophages (MMs) induces neuronal injury and chronic release of inflammatory stimuli through direct and indirect molecular pathways. A large percentage of people with HIV-associated neurologic and psychiatric co-morbidities have high levels of circulating inflammatory molecules. Microglia, given their susceptibility to HIV infection and long-lived nature, are reservoirs for persistent infection. MMs and neurons possess the molecular machinery to detect pathogen nucleic acids and proteins to activate innate immune signals. Full activation of inflammasome assembly and expression of IL-1β requires a priming event and a second signal. Many studies have demonstrated that HIV infection alone can activate inflammasome activity. Interestingly, secreted phosphoprotein-1 (SPP1/OPN) expression is highly upregulated in the CNS of people infected with HIV and neurologic dysfunction. Interestingly, all evidence thus far suggests a protective function of SPP1 signaling through mammalian target of rapamycin (mTORC1/2) pathway function to counter HIV-neuronal injury. Moreover, HIV-infected mice knocked down for SPP1 show by neuroimaging, increased neuroinflammation compared to controls. This suggests that SPP1 uses unique regulatory mechanisms to control the level of inflammatory signaling. In this mini review, we discuss the known and yet-to-be discovered biological links between SPP1-mediated stimulation of mTOR and inflammasome activity. Additional new mechanistic insights from studies in relevant experimental models will provide a greater understanding of crosstalk between microglia and neurons in the regulation of CNS homeostasis.

Mannose-specific plant and microbial lectins as antiviral agents: A review

Lectins are non-immunological carbohydrate-binding proteins classified on the basis of their structure, origin, and sugar specificity. The binding specificity of such proteins with the surface glycan moiety determines their activity and clinical applications. Thus, lectins hold great potential as diagnostic and drug discovery agents and as novel biopharmaceutical products. In recent years, significant advancements have been made in understanding plant and microbial lectins as therapeutic agents against various viral diseases. Among them, mannose-specific lectins have being proven as promising antiviral agents against a variety of viruses, such as HIV, Influenza, Herpes, Ebola, Hepatitis, Severe Acute Respiratory Syndrome Coronavirus-1 (SARS-CoV-1), Middle Eastern Respiratory Syndrome Coronavirus (MERS-CoV) and most recent Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). The binding of mannose-binding lectins (MBLs) from plants and microbes to high-mannose containing N-glycans (which may be simple or complex) of glycoproteins found on the surface of viruses has been found to be highly specific and mainly responsible for their antiviral activity. MBLs target various steps in the viral life cycle, including viral attachment, entry and replication. The present review discusses the brief classification and structure of lectins along with antiviral activity of various mannose-specific lectins from plants and microbial sources and their diagnostic and therapeutic applications against viral diseases.

The chemokine receptor CCR5: multi-faceted hook for HIV-1

Chemokines are cytokines whose primary role is cellular activation and stimulation of leukocyte migration. They perform their various functions by interacting with G protein-coupled cell surface receptors (GPCRs) and are involved in the regulation of many biological processes such as apoptosis, proliferation, angiogenesis, hematopoiesis or organogenesis. They contribute to the maintenance of the homeostasis of lymphocytes and coordinate the function of the immune system. However, chemokines and their receptors are sometimes hijacked by some pathogens to infect the host organism. For a given chemokine receptor, there is a wide structural, organizational and conformational diversity. In this review, we describe the evidence for structural variety reported for the chemokine receptor CCR5, how this variability can be exploited by HIV-1 to infect its target cells and what therapeutic solutions are currently being developed to overcome this problem.

Ongoing Healthcare Disparities in neuroHIV: Addressing Gaps in the Care Continuum

PURPOSE OF REVIEW

We aim to review the neurological complications of HIV and the social, cultural, and economic inequalities that contribute to disparities in neuroHIV care.

RECENT FINDINGS

Disparities in diagnostics and care of patients with neurological infections and non-infectious conditions associated with HIV in both high-income and low-to-middle-income countries (LMIC) are common. The COVID-19 pandemic has exacerbated these disparities. Factors, such as HIV-related stigma, may deter people from accessing HIV treatment. First-line recommended treatments for neurological infections are not available in many LMICs, leading to inadequate treatment and exposure to agents with more harmful side effect profiles. Access-related factors, such as lack of transportation, lack of health insurance, and inadequate telehealth access, may increase the risk of HIV-related neurological complications. Further research is needed to increase awareness of neurological complications among providers and PWH, and regional guidelines should be considered to better address these complications.

Accelerated brain aging with opioid misuse and HIV: New insights on the role of glially derived pro-inflammation mediators and neuronal chloride homeostasis

Opioid use disorder (OUD) has become a national crisis and contributes to the spread of human immunodeficiency virus (HIV) infection. Emerging evidence and advances in experimental models, methodology, and our understanding of disease processes at the molecular and cellular levels reveal that opioids per se can directly exacerbate the pathophysiology of neuroHIV. Despite substantial inroads, the impact of OUD on the severity, development, and prognosis of neuroHIV and HIV-associated neurocognitive disorders is not fully understood. In this review, we explore current evidence that OUD and neuroHIV interact to accelerate cognitive deficits and enhance the neurodegenerative changes typically seen with aging, through their effects on neuroinflammation. We suggest new thoughts on the processes that may underlie accelerated brain aging, including dysregulation of neuronal inhibition, and highlight findings suggesting that opioids, through actions at the μ-opioid receptor, interact with HIV in the central nervous system to promote unique structural and functional comorbid deficits not seen in either OUD or neuroHIV alone.

Identification of human immunodeficiency virus -1 E protein-targeting lead compounds by pharmacophore based screening

OBJECTIVES

To identify potential compounds by seeking the knowledge of molecular interactions between human immunodeficiency virus (HIV) glycoprotein (gp) 120 protein and anti-HIV drug (BMS-488043).

METHODS

This study is a computational structure-based drug design study, carried out at University of Taif, Saudi Arabia and African Genome Centre (AGC), Mohammed VI Polytechnic University, Benguerir, Morocco from January 2021 to March 2022. Initially, using the docked structure of gp120 with BMS-488043, a structure-based pharmacophore model was created. The generated model was utilized for virtual screening of the ZINC and ChemBridge database in order to identify hit compounds. To further assess the time-dependent stability of the selected complexes, computer simulation was performed.

RESULTS

From pharmacophore-based screening, 356 hits were obtained from both the database. The docking studies of the retrieved hit compounds reveal that all the compounds fit into the binding site of gp120. However, based on the significant interactions with the crucial residues and docking scores four compounds were suggested as potential hits. MD simulation of ChemBridge14695864 and ZINC06893293 in complex with gp120 suggested that both compounds significantly stabilized the receptor.

CONCLUSION

These findings could aid in the design of effective drugs against HIV by inhibiting the interaction between gp120 and CD4.

Frequency and functional profile of circulating TCRαβ+ double negative T cells in HIV/TB co-infection

BACKGROUND

Increased frequency of circulating double negative T (DNT, CD4^-CD8^-CD3⁺) cells with protective immune function has been observed in human immunodeficiency virus (HIV) infection and tuberculosis (TB). Here the role of circulating TCRαβ⁺ DNT cells was further investigated in HIV/TB co-infection.

METHODS

A cross-sectional study was conducted to investigate the frequency and functional profiles of peripheral TCRαβ⁺ DNT cells including apoptosis, chemokine and cytokine expression among healthy individuals and patients with TB, HIV infection and HIV/TB co-infection by cell surface staining and intracellular cytokine staining combined with flow cytometry.

RESULTS

Significantly increased frequency of TCRαβ⁺ DNT cells was observed in HIV/TB co-infection than that in TB (p < 0.001), HIV infection (p = 0.039) and healthy controls (p < 0.001). Compared with TB, HIV/TB co-infection had higher frequency of Fas expression (p = 0.007) and lower frequency of Annexin V expression on TCRαβ⁺ DNT cells (p = 0.049), and the frequency of Annexin V expression on Fas⁺TCRαβ⁺ DNT cells had no significant difference. TCRαβ⁺ DNT cells expressed less CCR5 in HIV/TB co-infection than that in TB (p = 0.014), and more CXCR4 in HIV/TB co-infection than that in HIV infection (p = 0.043). Compared with healthy controls, TB and HIV/TB co-infection had higher frequency of TCRαβ⁺ DNT cells secreting Granzyme A (p = 0.046; p = 0.005). In TB and HIV/TB co-infection, TCRαβ⁺ DNT cells secreted more granzyme A (p = 0.002; p = 0.002) and perforin (p < 0.001; p = 0.017) than CD4⁺ T cells but similar to CD8⁺ T cells.

CONCLUSIONS

Reduced apoptosis may take part in the mechanism of increased frequency of peripheral TCRαβ⁺ DNT cells in HIV/TB co-infection. TCRαβ⁺ DNT cells may play a cytotoxic T cells-like function in HIV/TB co-infection.

Co-Infection and Cancer: Host–Pathogen Interaction between Dendritic Cells and HIV-1, HTLV-1, and Other Oncogenic Viruses

Dendritic cells (DCs) function as a link between innate and adaptive immune responses. Retroviruses HIV-1 and HTLV-1 modulate DCs to their advantage and utilize them to propagate infection. Coinfection of HTLV-1 and HIV-1 has implications for cancer malignancies. Both viruses initially infect DCs and propagate the infection to CD4+ T cells through cell-to-cell transmission using mechanisms including the formation of virologic synapses, viral biofilms, and conduits. These retroviruses are both neurotrophic with neurovirulence determinants. The neuropathogenesis of HIV-1 and HTLV-1 results in neurodegenerative diseases such as HIV-associated neurocognitive disorders (HAND) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Infected DCs are known to traffic to the brain (CNS) and periphery (PNS, lymphatics) to induce neurodegeneration in HAND and HAM/TSP patients. Elevated levels of neuroinflammation have been correlated with cognitive decline and impairment of motor control performance. Current vaccinations and therapeutics for HIV-1 and HTLV-1 are assessed and can be applied to patients with HIV-1-associated cancers and adult T cell leukemia/lymphoma (ATL). These diseases caused by co-infections can result in both neurodegeneration and cancer. There are associations with cancer malignancies and HIV-1 and HTLV-1 as well as other human oncogenic viruses (EBV, HBV, HCV, HDV, and HPV). This review contains current knowledge on DC sensing of HIV-1 and HTLV-1 including DC-SIGN, Tat, Tax, and current viral therapies. An overview of DC interaction with oncogenic viruses including EBV, Hepatitis viruses, and HPV is also provided. Vaccines and therapeutics targeting host–pathogen interactions can provide a solution to co-infections, neurodegeneration, and cancer.

Recent Advances in the Molecular and Cellular Mechanisms of gp120-Mediated Neurotoxicity

Axonal degeneration and loss of synapses are often seen in different brain areas of people living with human immunodeficiency virus (HIV). Nevertheless, the underlying causes of the pathological alterations observed in these individuals are poorly comprehended, considering that HIV does not infect neurons. Experimental data have shown that viral proteins, including the envelope protein gp120, cause synaptic pathology followed by neuronal cell death. These neurotoxic effects on synapses could be the result of a variety of mechanisms that decrease synaptic plasticity. In this paper, we will briefly present new emerging concepts connected with the ability of gp120 to promote the degeneration of synapses by either directly damaging the axonal cytoskeleton and/or the indirect activation of the p75 neurotrophin receptor death domain in dendrites.

Recent Advances in Influenza, HIV and SARS-CoV-2 Infection Prevention and Drug Treatment—The Need for Precision Medicine

Viruses, and in particular, RNA viruses, dominate the WHO’s current list of ten global health threats. Of these, we review the widespread and most common HIV, influenza virus, and SARS-CoV-2 infections, as well as their possible prevention by vaccination and treatments by pharmacotherapeutic approaches. Beyond the vaccination, we discuss the virus-targeting and host-targeting drugs approved in the last five years, in the case of SARS-CoV-2 in the last one year, as well as new drug candidates and lead molecules that have been published in the same periods. We share our views on vaccination and pharmacotherapy, their mutually reinforcing strategic significance in combating pandemics, and the pros and cons of host and virus-targeted drug therapy. The COVID-19 pandemic has provided evidence of our limited armamentarium to fight emerging viral diseases. Novel broad-spectrum vaccines as well as drugs that could even be applied as prophylactic treatments or in early phases of the viremia, possibly through oral administration, are needed in all three areas. To meet these needs, the use of multi-data-based precision medicine in the practice and innovation of vaccination and drug therapy is inevitable.