Cannabinoid inhibits HIV-1 Tat-stimulated adhesion of human monocyte-like cells to extracellular matrix proteins

The Endocannabinoid System as a Potential Therapeutic Target for HIV-1-Associated Neurocognitive Disorder

Background: Despite the successful introduction of combined antiretroviral therapy, the prevalence of mild to moderate forms of HIV-associated neurocognitive disorders (HAND) remains high. It has been demonstrated that neuronal injury caused by HIV is excitotoxic and inflammatory, and it correlates with neurocognitive decline in HAND. Endocannabinoid system (ECS) protects the body from excitotoxicity and neuroinflammation on demand and presents a promising therapeutic target for treating HAND. Here, we firstly discuss the potential pathogenesis of HAND. We secondly discuss the structural and functional changes in the ECS that are currently known among HAND patients. We thirdly discuss current clinical and preclinical findings concerning the neuroprotective and anti-inflammatory properties of the ECS among HAND patients. Fourth, we will discuss the interactions between the ECS and neuroendocrine systems, including the hypothalamic-pituitary-adrenocortical (HPA) and hypothalamic-pituitary-gonadal (HPG) axes under the HAND conditions. Materials and Methods: We have carried out a review of the literature using PubMed to summarize the current state of knowledge on the association between ECS and HAND. Results: The ECS may be ideally suited for modulation of HAND pathophysiology. Direct activation of presynaptic cannabinoid receptor 1 or reduction of cannabinoid metabolism attenuates HAND excitotoxicity. Chronic neuroinflammation associated with HAND can be reduced by activating cannabinoid receptor 2 on immune cells. The sensitivity of the ECS to HIV may be enhanced by increased cannabinoid receptor expression in HAND. In addition, indirect regulation of the ECS through modulation of hormone-related receptors may be a potential strategy to influence the ECS and also alleviate the progression of HAND due to the reciprocal inhibition of the ECS by the HPA and HPG axes. Conclusions: Taken together, targeting the ECS may be a promising strategy to alleviate the inflammation and neurodegeneration caused by HIV-1 infection. Further studies are required to clarify the role of endocannabinoid signaling in HIV neurotoxicity. Strategies promoting endocannabinoid signaling may slow down cognitive decline of HAND are proposed.

Expression and Functions of the CB2 Receptor in Human Leukocytes

The cannabinoid CB₂ receptor was cloned from the promyeloid cell line HL-60 and is notably expressed in most, if not all leukocyte types. This relatively restricted localization, combined to the absence of psychotropic effects following its activation, make it an attractive drug target for inflammatory and autoimmune diseases. Therefore, there has been an increasing interest in the past decades to identify precisely which immune cells express the CB₂ receptor and what are the consequences of such activation. Herein, we provide new data on the expression of both CB₁ and CB₂ receptors by human blood leukocytes and discuss the impact of CB₂ receptor activation in human leukocytes. While the expression of the CB₂ mRNA can be detected in eosinophils, neutrophils, monocytes, B and T lymphocytes, this receptor is most abundant in human eosinophils and B lymphocytes. We also review the evidence obtained from primary human leukocytes and immortalized cell lines regarding the regulation of their functions by the CB₂ receptor, which underscore the urgent need to deepen our understanding of the CB₂ receptor as an immunoregulator in humans.

Cannabinoids Reduce Extracellular Vesicle Release from HIV-1 Infected Myeloid Cells and Inhibit Viral Transcription

Of the 37.9 million individuals infected with human immunodeficiency virus type 1 (HIV-1), approximately 50% exhibit HIV-associated neurocognitive disorders (HAND). We and others previously showed that HIV-1 viral RNAs, such as trans-activating response (TAR) RNA, are incorporated into extracellular vesicles (EVs) and elicit an inflammatory response in recipient naïve cells. Cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC), the primary cannabinoids present in cannabis, are effective in reducing inflammation. Studies show that cannabis use in people living with HIV-1 is associated with lower viral load, lower circulating CD16+ monocytes and high CD4+ T-cell counts, suggesting a potentially therapeutic application. Here, HIV-1 infected U1 monocytes and primary macrophages were used to assess the effects of CBD. Post-CBD treatment, EV concentrations were analyzed using nanoparticle tracking analysis. Changes in intracellular and EV-associated viral RNA were quantified using RT-qPCR, and changes in viral proteins, EV markers, and autophagy proteins were assessed by Western blot. Our data suggest that CBD significantly reduces the number of EVs released from infected cells and that this may be mediated by reducing viral transcription and autophagy activation. Therefore, CBD may exert a protective effect by alleviating the pathogenic effects of EVs in HIV-1 and CNS-related infections.

Cannabinoid receptor type 2 agonist JWH-133 decreases cathepsin B secretion and neurotoxicity from HIV-infected macrophages

HIV-associated neurocognitive disorders (HAND) are prevalent despite combined antiretroviral therapy (cART), affecting 52% of people living with HIV. Our laboratory has demonstrated increased expression of cathepsin B (CATB) in postmortem brain tissue with HAND. Increased secretion of CATB from in vitro HIV-infected monocyte-derived macrophages (MDM) induces neurotoxicity. Activation of cannabinoid receptor type 2 (CB2R) inhibits HIV-1 replication in macrophages and the neurotoxicity induced by viral proteins. However, it is unknown if CB2R agonists affect CATB secretion and neurotoxicity in HIV-infected MDM. We hypothesized that HIV-infected MDM exposed to CB2R agonists decrease CATB secretion and neurotoxicity. Primary MDM were inoculated with HIV-1_ADA and treated with selective CB2R agonists JWH-133 and HU-308. HIV-1 p24 and CATB levels were determined from supernatants using ELISA. MDM were pre-treated with a selective CB2R antagonist SR144528 before JWH-133 treatment to determine if CB2R activation is responsible for the effects. Neuronal apoptosis was assessed using a TUNEL assay. Results show that both agonists reduce HIV-1 replication and CATB secretion from MDM in a time and dose-dependent manner and that CB2R activation is responsible for these effects. Finally, JWH-133 decreased HIV/MDM-CATB induced neuronal apoptosis. Our results suggest that agonists of CB2R represent a potential therapeutic strategy against HIV/MDM-induced neurotoxicity.

Confound, Cause, or Cure: The Effect of Cannabinoids on HIV-Associated Neurological Sequelae

The persistence of human immunodeficiency virus-1 (HIV)-associated neurocognitive disorders (HAND) in the era of effective antiretroviral therapy suggests that modern HIV neuropathogenesis is driven, at least in part, by mechanisms distinct from the viral life cycle. Identifying more subtle mechanisms is complicated by frequent comorbidities in HIV⁺ populations. One of the common confounds is substance abuse, with cannabis being the most frequently used psychoactive substance among people living with HIV. The psychoactive effects of cannabis use can themselves mimic, and perhaps magnify, the cognitive deficits observed in HAND; however, the neuromodulatory and anti-inflammatory properties of cannabinoids may counter HIV-induced excitotoxicity and neuroinflammation. Here, we review our understanding of the cross talk between HIV and cannabinoids in the central nervous system by exploring both clinical observations and evidence from preclinical in vivo and in vitro models. Additionally, we comment on recent advances in human, multi-cell in vitro systems that allow for more translatable, mechanistic studies of the relationship between cannabinoid pharmacology and this uniquely human virus.

Mini-review: The therapeutic role of cannabinoids in neuroHIV

In the era of combined antiretroviral therapy (cART), human immunodeficiency virus type 1 (HIV-1) is considered a chronic disease with an inflammatory component that specifically targets the brain and causes a high prevalence of HIV-1-associated neurocognitive disorders (HAND). The endocannabinoid (eCB) system has attracted interest as a target for treatment of neurodegenerative disorders, due to the potential anti-inflammatory and neuroprotective properties of cannabinoids, including its potential therapeutic use in HIV-1 neuropathogenesis. In this review, we summarize what is currently known about the structural and functional changes of the eCB system under conditions of HAND. This will be followed by summarizing the current clinical and preclinical findings on the effects of cannabis use and cannabinoids in the context of HIV-1 infection, with specifically focusing on viral load, cognition, inflammation, and neuroprotection. Lastly, we present some potential future directions to better understand the involvement of the eCB system and the role that cannabis use and cannabinoids play in neuroHIV.

Long-Term Low-Dose Delta-9-Tetrahydrocannbinol (THC) Administration to Simian Immunodeficiency Virus (SIV) Infected Rhesus Macaques Stimulates the Release of Bioactive Blood Extracellular Vesicles (EVs) that Induce Divergent Structural Adaptations and Signaling Cues

Blood extracellular vesicles (BEVs) carry bioactive cargo (proteins, genetic materials, lipids, licit, and illicit drugs) that regulate diverse functions in target cells. The cannabinoid drug delta-9-tetrahydrocannabinol (THC) is FDA approved for the treatment of anorexia and weight loss in people living with HIV. However, the effect of THC on BEV characteristics in the setting of HIV/SIV infection needs to be determined. Here, we used the SIV-infected rhesus macaque model of AIDS to evaluate the longitudinal effects of THC (THC/SIV) or vehicle (VEH/SIV) treatment in HIV/SIV infection on the properties of BEVs. While BEV concentrations increased longitudinally (pre-SIV (0), 30, and 150 days post-SIV infection (DPI)) in VEH/SIV macaques, the opposite trend was observed with THC/SIV macaques. SIV infection altered BEV membrane properties and cargo composition late in infection, since i) the electrostatic surface properties (zeta potential, ζ potential) showed that RM BEVs carried negative surface charge, but at 150 DPI, SIV infection significantly changed BEV ζ potential; ii) BEVs from the VEH/SIV group altered tetraspanin CD9 and CD81 levels compared to the THC/SIV group. Furthermore, VEH/SIV and THC/SIV BEVs mediated divergent changes in monocyte gene expression, morphometrics, signaling, and function. These include altered tetraspanin and integrin β1 expression; altered levels and distribution of polymerized actin, FAK/pY397 FAK, pERK1/2, cleaved caspase 3, proapoptotic Bid and truncated tBid; and altered adhesion of monocytes to collagen I. These data indicate that HIV/SIV infection and THC treatment result in the release of bioactive BEVs with potential to induce distinct structural adaptations and signaling cues to instruct divergent cellular responses to infection.

Novel association of genetic variants in non-coding regulatory regions with HIV-1 infection

Host genetic variability interplays with the environment and variegating viral factors to determine the outcome in HIV-1/AIDS. Several GWAS studies have reported that genetic heterogeneity of individuals leads to differential HIV susceptibility. Proxy SNPs that are in Linkage Disequilibrium to the GWAS SNPs could be important targets in HIV pathogenesis and need to be analyzed further for their potential regulatory role. Current study thus aimed to identify novel proxy SNPs that may play a critical role in HIV susceptibility and disease progression. 372 SNPs, associated with HIV-1/AIDS pathogenesis, were retrieved via GWAS catalogue. 1854 proxy SNPs, in Linkage Disequilibrium (r² = 0.8) to the GWAS reported SNPs, were identified using the SNAP web tool. Regulatory functions of aforementioned 1854 polymorphic sites (GWAS SNPs and their proxy SNPs) were acquired from RegulomeDB. 178 of the proxy SNPs showed evidence of strong regulatory potential returning a score of ≤3. Among these regulatory SNPs, 22 had already been reported for their association with HIV/AIDS while 156 SNPs showed novel association. Three of these novel SNPs (g.rs6457282T>C, g.rs17064977C>T and g.rs3130350G>T) were validated using sequence specific PCR (SSP-PCR) on HIV-infected patients. For g.rs6457282T>C and rs17064977C>T, CT genotype was determined to be significantly associated with increased risk of HIV-1 infection (rs6457282T>C: OR = 9.5, 95% CI = 3.0792-29.3099, p = 0.0001; rs17064977C>T: OR = 8.1077, 95% CI = 3.1125-21.119, p = 0.0001). Moreover, the association of interacting protein partners of affected genes with HIV-1 elucidates the significance of corresponding SNPs in HIV disease outcome that further needs to be functionally deciphered.

Cannabinoid-Induced Immunomodulation during Viral Infections: A Focus on Mitochondria

This review examines the impact of cannabinoids on viral infections, as well as its effects on the mitochondria of the nervous and immune system. The paper conveys information about the beneficial and negative impacts of cannabinoids on viral infections, especially HIV-1. These include effects on the inflammatory response as well as neuroprotective effects. We also explore non-apoptotic mitochondrial pathways modulated by the activity of cannabinoids, resulting in modifications to cellular functions. As a large part of the literature derives from studies of the nervous system, we first compile the information related to mitochondrial functions in this system, particularly through the CB1 receptor. Finally, we reflect on how this knowledge could complement what has been demonstrated in the immune system, especially in the context of the CB2 receptor and Ca²⁺ uptake. The overall conclusion of the review is that cannabinoids have the potential to affect a broad range of cell types through mitochondrial modulation, be it through receptor-specific action or not, and that this pathway has a potential implication in cases of viral infection.

Druggable targets of the endocannabinoid system: Implications for the treatment of HIV-associated neurocognitive disorder

HIV-associated neurocognitive disorder (HAND) affects nearly half of all HIV-infected individuals. Synaptodendritic damage correlates with neurocognitive decline in HAND, and many studies have demonstrated that HIV-induced neuronal injury results from excitotoxic and inflammatory mechanisms. The endocannabinoid (eCB) system provides on-demand protection against excitotoxicity and neuroinflammation. Here, we discuss evidence of the neuroprotective and anti-inflammatory properties of the eCB system from in vitro and in vivo studies. We examine the pharmacology of the eCB system and evaluate the therapeutic potential of drugs that modulate eCB signaling to treat HAND. Finally, we provide perspective on the need for additional studies to clarify the role of the eCB system in HIV neurotoxicity and speculate that strategies that enhance eCB signaling might slow cognitive decline in HAND.

Cannabinoid receptor 2 deficiency exacerbates inflammation and neutrophil recruitment

Cannabinoid receptor (CB)₂ is an immune cell–localized GPCR that has been hypothesized to regulate the magnitude of inflammatory responses. However, there is currently no consensus as to the mechanism by which CB₂ mediates its anti-inflammatory effects in vivo. To address this question, we employed a murine dorsal air pouch model with wild-type and CB₂^−/− 8–12-wk-old female and male C57BL/6 mice and found that acute neutrophil and lymphocyte antigen 6 complex, locus C^hi monocyte recruitment in response to Zymosan was significantly enhanced in CB₂^−/− mice. Additionally, levels of matrix metalloproteinase 9 and the chemokines C-C motif chemokine ligand (CCL)2, CCL4, and C-X-C motif chemokine ligand 10 in CB₂^−/− pouch exudates were elevated at earlier time points. Importantly, using mixed bone marrow chimeras, we revealed that the proinflammatory phenotype in CB₂^−/− mice is neutrophil-intrinsic rather than stromal cell–dependent. Indeed, neutrophils isolated from CB₂^−/− mice exhibited an enhanced migration-related transcriptional profile and increased adhesive phenotype, and treatment of human neutrophils with a CB₂ agonist blocked their endothelial transmigration. Overall, we have demonstrated that CB₂ plays a nonredundant role during acute neutrophil mobilization to sites of inflammation and, as such, it could represent a therapeutic target for the development of novel anti-inflammatory compounds to treat inflammatory human diseases.—Kapellos, T. S., Taylor, L., Feuerborn, A., Valaris, S., Hussain, M. T., Rainger, G. E., Greaves, D. R., Iqbal, A. J. Cannabinoid receptor 2 deficiency exacerbates inflammation and neutrophil recruitment.

In vivo evidence that the cannabinoid receptor 2-63 RR variant is associated with the acquisition and/or expansion of HIV infection

OBJECTIVES

The aim of the study was to investigate whether the rs35761398 variants of the cannabinoid receptor 2 (CB2) gene may influence the acquisition of HIV infection and the clinical presentation of HIV/hepatitis C virus (HCV) coinfection.

METHODS

We compared 166 HIV/HCV-coinfected patients with 186 HCV-monoinfected patients, all with biopsy-proven chronic hepatitis (using the Ishak scoring system), naïve for anti-HCV treatment and tested for the CB2 rs35761398 polymorphism (using the TaqMan assay).

RESULTS

The HIV/HCV-coinfected patients were more frequently male (P < 0.002), were younger (P < 0.001), and had lower median BMI (P < 0.001) and HCV RNA (P < 0.05) and higher median aspartate aminotransferase (AST; P < 0.001), alanine aminotransferase (ALT; P < 0.001) and gamma glutamyl transferase (GGT; P < 0.001) levels than the HCV-monoinfected patients. The CB2 RR variant predominated in HIV/HCV-coinfected patients (45.8% vs. 31.2% in HCV-monoinfected patients; P < 0.001) and the CB2 QR variant in HCV-monoinfected patients (57.5% vs. 38.6% in HIV/HCV-coinfected patients; P < 0.00001), and the CB2 QQ variant was equally distributed. Focusing on patients with the CB2 QQ variant, the 26 HIV/HCV-coinfected patients, compared with the 21 HCV-monoinfected patients, showed less severe liver necroinflammation [lower histological activity index (HAI)] (P < 0.05). Of the patients with the CB2 RR variant, the 76 HIV/HCV-coinfected patients, compared with the 58 HCV-monoinfected patients, were more frequently male (P < 0.05), were younger (P < 0.001), and had a lower median body mass index (BMI; P < 0.001), a higher median AST level (P < 0.001), a higher mean HAI score (P < 0.05) and a higher rate of cases with severe steatosis (P = 0.05). In an analysis of variance (anova) of HCV/HIV-coinfected and HCV-monoinfected patient data, those with the CB2 RR variant (P = 0.003) and of male sex (P = 0.002) were more prevalent in the HCV/HIV-coinfected group.

CONCLUSIONS

There is the suggestion of a positive effect of the CB2 RR variant on HIV acquisition and/or spread, which is in accordance with previous in vitro observations.

All-Round Manipulation of the Actin Cytoskeleton by HIV

While significant progress has been made in terms of human immunodeficiency virus (HIV) therapy, treatment does not represent a cure and remains inaccessible to many people living with HIV. Continued mechanistic research into the viral life cycle and its intersection with many aspects of cellular biology are not only fundamental in the continued fight against HIV, but also provide many key observations of the workings of our immune system. Decades of HIV research have testified to the integral role of the actin cytoskeleton in both establishing and spreading the infection. Here, we review how the virus uses different strategies to manipulate cellular actin networks and increase the efficiency of various stages of its life cycle. While some HIV proteins seem able to bind to actin filaments directly, subversion of the cytoskeleton occurs indirectly by exploiting the power of actin regulatory proteins, which are corrupted at multiple levels. Furthermore, this manipulation is not restricted to a discrete class of proteins, but rather extends throughout all layers of the cytoskeleton. We discuss prominent examples of actin regulators that are exploited, neutralized or hijacked by the virus, and address how their coordinated deregulation can lead to changes in cellular behavior that promote viral spreading.

Cannabinoid receptor 2-63 RR variant is independently associated with severe necroinflammation in HIV/HCV coinfected patients

Objective

This is the first study to analyze the impact of the rs35761398 variant of the CNR2 gene leading to the substitution of GLN (Q) of codon 63 of the cannabinoid receptor 2 (CB2) with ARG (R) on the clinical presentation of chronic hepatitis in HIV/HCV coinfected patients.

Methods

Enrolled in this study were 166 consecutive HIV/HCV coinfected patients, naïve for HCV treatment. A pathologist unaware of the patients’ condition graded liver fibrosis, necroinflammation (Ishak) and steatosis. All patients were screened for the CB2 rs35761398 polymorphism.

Results

Of the 166 HIV/HCV coinfected patients, 72.9% were males, 42.5% were infected with HCV-genotype-3 and 60.2% had been intravenous drug users. The median age was 40.6 years and the immunological condition good (median CD4⁺ cells/mm³ = 507, IQR: 398.0–669.5). Thirty-five (21.1%) patients were naive for ART and 131(78.9%) were on ART. The CB2-RR variant was detected in 45.8% of patients, QR in 38.6% and QQ in 15.7%. Patients with CB2-RR showed a necroinflammation score (HAI) ≥9 more frequently than those with CB2-QQ or CB2-QR (32.9% vs. 11.5% and 14.1%, respectively, p≤0.001). In the multivariate analysis, the CB2-RR variant (p = 0.03) and liver fibrosis were both identified as independent predictors of the entity of liver necroinflammation (p = 0.0001).

Conclusion

This study shows interesting interplay between the CB2-RR variant and liver necroinflammation in chronic hepatitis patients with HIV/HCV coinfection, an observation of clinical value that coincides with the interest in the use of the CB2 agonists and antagonists in clinical practice emerging from the literature.

Interaction between Tat and Drugs of Abuse during HIV-1 Infection and Central Nervous System Disease

In many individuals, drug abuse is intimately linked with HIV-1 infection. In addition to being associated with one-third of all HIV-1 infections in the United States, drug abuse also plays a role in disease progression and severity in HIV-1-infected patients, including adverse effects on the central nervous system (CNS). Specific systems within the brain are known to be damaged in HIV-1-infected individuals and this damage is similar to that observed in drug abuse. Even in the era of anti-retroviral therapy (ART), CNS pathogenesis occurs with HIV-1 infection, with a broad range of cognitive impairment observed, collectively referred to as HIV-1-associated neurocognitive disorders (HAND). A number of HIV-1 proteins (Tat, gp120, Nef, Vpr) have been implicated in the etiology of pathogenesis and disease as a result of the biologic activity of the extracellular form of each of the proteins in a number of tissues, including the CNS, even in ART-suppressed patients. In this review, we have made Tat the center of attention for a number of reasons. First, it has been shown to be synthesized and secreted by HIV-1-infected cells in the CNS, despite the most effective suppression therapies available to date. Second, Tat has been shown to alter the functions of several host factors, disrupting the molecular and biochemical balance of numerous pathways contributing to cellular toxicity, dysfunction, and death. In addition, the advantages and disadvantages of ART suppression with regard to controlling the genesis and progression of neurocognitive impairment are currently under debate in the field and are yet to be fully determined. In this review, we discuss the individual and concerted contributions of HIV-1 Tat, drug abuse, and ART with respect to damage in the CNS, and how these factors contribute to the development of HAND in HIV-1-infected patients.