Cannabinoid receptor-2 and HIV-associated neurocognitive disorders

Quantitative Proteomics Reveal That CB2R Agonist JWH-133 Downregulates NF-κB Activation, Oxidative Stress, and Lysosomal Exocytosis from HIV-Infected Macrophages

HIV-associated neurocognitive disorders (HAND) affect 15-55% of HIV-positive patients and effective therapies are unavailable. HIV-infected monocyte-derived macrophages (MDM) invade the brain of these individuals, promoting neurotoxicity. We demonstrated an increased expression of cathepsin B (CATB), a lysosomal protease, in monocytes and post-mortem brain tissues of women with HAND. Increased CATB release from HIV-infected MDM leads to neurotoxicity, and their secretion is associated with NF-κB activation, oxidative stress, and lysosomal exocytosis. Cannabinoid receptor 2 (CB2R) agonist, JWH-133, decreases HIV-1 replication, CATB secretion, and neurotoxicity from HIV-infected MDM, but the mechanisms are not entirely understood. We hypothesized that HIV-1 infection upregulates the expression of proteins associated with oxidative stress and that a CB2R agonist could reverse these effects. MDM were isolated from healthy women donors (n = 3), infected with HIV-1ADA, and treated with JWH-133. After 13 days post-infection, cell lysates were labeled by Tandem Mass Tag (TMT) and analyzed by LC/MS/MS quantitative proteomics bioinformatics. While HIV-1 infection upregulated CATB, NF-κB signaling, Nrf2-mediated oxidative stress response, and lysosomal exocytosis, JWH-133 treatment downregulated the expression of the proteins involved in these pathways. Our results suggest that JWH-133 is a potential alternative therapy against HIV-induced neurotoxicity and warrant in vivo studies to test its potential against HAND.

Effects of acute Δ9-tetrahydrocannabinol on behavior and the endocannabinoid system in HIV-1 Tat transgenic female and male mice

Cannabis use is highly prevalent especially among people living with HIV (PLWH). Activation of the anti-inflammatory and neuroprotective endocannabinoid system by phytocannabinoids, i.e. Δ9-tetrahydrocannabinol (THC), has been proposed to reduce HIV symptoms. However, THC's effects on HIV-related memory deficits are unclear. Using HIV-1 Tat transgenic mice, the current study investigates acute THC effects on various behavioral outcomes and the endocannabinoid system. For the rodent tetrad model, THC doses (1, 3, 10 mg/kg) induced known antinociceptive effects, with Tat induction increasing antinociceptive THC effects at 3 and 10 mg/kg doses. Only minor or no effects were noted for acute THC on body temperature, locomotor activity, and coordination. Increased anxiety-like behavior was found for females compared to males, but acute THC had no effect on anxiety. Object recognition memory was diminished by acute THC in Tat(-) females but not Tat(+) females, without affecting males. The endocannabinoid system and related lipids were not affected by acute THC, except for THC-induced decreases in CB1R protein expression levels in the spinal cord of Tat(-) mice. Female sex and Tat induction was associated with elevated 2-AG, AEA, AA, CB1R, CB2R, FAAH and/or MAGL expression in various brain regions. Further, AEA levels in the prefrontal cortex of Tat(+) females were negatively associated with object recognition memory. Overall, findings indicate that acute THC exerts differential effects on antinociception and memory, dependent on sex and HIV Tat expression, potentially in relation to an altered endocannabinoid system, which may be of relevance in view of potential cannabis-based treatment options for PLWH.

Peripheral sensory neuron CB2 cannabinoid receptors are necessary for both CB2-mediated antinociceptive efficacy and sparing of morphine tolerance in a mouse model of anti-retroviral toxic neuropathy

Painful peripheral neuropathy is a common neurological complication associated with human immunodeficiency virus (HIV) infection and anti-retroviral therapy. We characterized the impact of two CB2 cannabinoid agonists (AM1710 and LY2828360 - ligands differing in signaling bias and CNS penetration) on neuropathic nociception induced by the antiretroviral agent Zalcitabine (2',3'-dideoxycytidine; ddC). We also used a conditional knockout approach to identify cell types mediating CB2 agonist-induced antinociceptive efficacy and sparing of morphine tolerance. AM1710 and LY2828360 alleviated ddC-induced neuropathic nociception in mice of both sexes. These benefits were absent in global CB2 knockout mice, which exhibited robust morphine antinociception. Like morphine, AM1710 blunted ddC-induced increases in proinflammatory cytokine (IL-1β, TNF-α) and chemokine (CCL2) mRNA expression levels. We generated advillinCre/+;CB2f/f conditional knockout mice to ascertain the role of CB2 localized to primary sensory neurons in CB2-mediated therapeutic effects. Antinociceptive efficacy of both AM1710 and LY2828360, but not reference analgesics, were absent in advillinCre/+;CB2f/f mice, which exhibited robust ddC-induced neuropathy. In ddC-treated CB2f/f mice, LY2828360 suppressed development of morphine tolerance and reversed established morphine tolerance, albeit with greater efficacy in male compared to female mice. LY2828360 failed to block or reverse morphine tolerance in advillinCre/+;CB2f/f mice. The present studies indicate that CB2 activation may alleviate HIV-associated antiretroviral neuropathy and identify a previously unreported mechanism through which CB2 activation produces antinociceptive efficacy. Our results also provide the first evidence that a CB2 agonist can reverse established morphine tolerance and demonstrate that CB2 localized to peripheral sensory neurons mediates the opioid tolerance sparing efficacy of CB2 agonists.

Regular cannabis use modulates the impact of HIV on the neural dynamics serving cognitive control

BACKGROUND

Cannabis use and HIV are independently associated with decrements in cognitive control. However, the combined effects of HIV and regular cannabis use on the brain circuitry serving higher-order cognition are unclear.

AIMS

Investigate the interaction between cannabis and HIV on neural interference effects during the flanker task and spontaneous activity in regions underlying higher-order cognition.

METHODS

The sample consisted of 100 participants, including people with HIV (PWH) who use cannabis, PWH who do not use cannabis, uninfected cannabis users, and uninfected nonusers. Participants underwent an interview regarding their substance use history and completed the Eriksen flanker task during magnetoencephalography (MEG). MEG data were imaged in the time-frequency domain and oscillatory maps depicting the neural flanker interference effect were probed for group differences. Voxel time series were then assessed for group-level differences in spontaneous activity.

RESULTS

Group differences in behavioral performance were identified along with group differences in theta and alpha neural interference responses in higher-order regions across the cortex, with nonusers with HIV generally exhibiting the most aberrant responses. Likewise, time series analyses indicated that nonusers with HIV also had significantly elevated spontaneous alpha activity in the left inferior frontal and dorsolateral prefrontal cortices (dlPFC). Finally, we found that spontaneous and oscillatory alpha activity were significantly coupled in the inferior frontal cortex and dlPFC among cannabis users, but not nonusers.

CONCLUSIONS

Regular cannabis use appears to suppress the impact of HIV on spontaneous and oscillatory alpha deficits in the left inferior frontal cortex and dlPFC.

Inhibitory Neurotransmission Is Sex-Dependently Affected by Tat Expression in Transgenic Mice and Suppressed by the Fatty Acid Amide Hydrolase Enzyme Inhibitor PF3845 via Cannabinoid Type-1 Receptor Mechanisms

(1) Background. The endocannabinoid (eCB) system, which regulates physiological and cognitive processes, presents a promising therapeutic target for treating HIV-associated neurocognitive disorders (HAND). Here we examine whether upregulating eCB tone has potential protective effects against HIV-1 Tat (a key HIV transactivator of transcription) protein-induced alterations in synaptic activity. (2) Methods. Whole-cell patch-clamp recordings were performed to assess inhibitory GABAergic neurotransmission in prefrontal cortex slices of Tat transgenic male and female mice, in the presence and absence of the fatty acid amide hydrolase (FAAH) enzyme inhibitor PF3845. Western blot and mass spectrometry analyses assessed alterations of cannabinoid receptor and enzyme protein expression as well as endogenous ligands, respectively, to determine the impact of Tat exposure on the eCB system. (3) Results. GABAergic activity was significantly altered upon Tat exposure based on sex, whereas the effectiveness of PF3845 to suppress GABAergic activity in Tat transgenic mice was not altered by Tat or sex and involved CB1R-related mechanisms that depended on calcium signaling. Additionally, our data indicated sex-dependent changes for AEA and related non-eCB lipids based on Tat induction. (4) Conclusion. Results highlight sex- and/or Tat-dependent alterations of GABAergic activity and eCB signaling in the prefrontal cortex of Tat transgenic mice and further increase our understanding about the role of FAAH inhibition in neuroHIV.

Considerations for Cannabinoids in Perioperative Care by Anesthesiologists

Increased usage of recreational and medically indicated cannabinoid compounds has been an undeniable reality for anesthesiologists in recent years. These compounds’ complicated pharmacology, composition, and biological effects result in challenging issues for anesthesiologists during different phases of perioperative care. Here, we review the existing formulation of cannabinoids and their biological activity to put them into the context of the anesthesia plan execution. Perioperative considerations should include a way to gauge the patient’s intake of cannabinoids, the ability to gain consent properly, and vigilance to the increased risk of pulmonary and airway problems. Intraoperative management in individuals with cannabinoid use is complicated by the effects cannabinoids have on general anesthetics and depth of anesthesia monitoring while simultaneously increasing the potential occurrence of intraoperative hemodynamic instability. Postoperative planning should involve higher vigilance to the risk of postoperative strokes and acute coronary syndromes. However, most of the data are not up to date, rending definite conclusions on the importance of perioperative cannabinoid intake on anesthesia management difficult.

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.

Role of cannabinoids in various diseases: A review

BACKGROUND

The plant, Cannabis sativa is heavily explored and researched with many industrial and pharmaceutical applications. The medicinal and therapeutic role of cannabis Sativa has been summarized in the paper, citing its mechanism of action and influence on the human body. Diseases like metabolic disorders, infectious diseases, and psychological disorders pose negative and long-term drastic effects on the body like neurodegeneration and other chronic system failures. Several existing literature has proved its effectiveness against such diseases.

OBJECTIVES

This review aims to provide an overview of the role of cannabinoids in various diseases like metabolic disorders, infectious diseases, and psychological disorders.

METHOD

Various e-resources like Pubmed, Science Direct, and Google Scholar were thoroughly searched and read to form a well-informed and information-heavy manuscript. Here we tried to summaries the therapeutic aspect of Cannabis sativa and its bioactive compound cannabinoids in various diseases.

RESULT

This review highlights the various constituents which are present in Cannabis sativa, the Endocannabinoid system, and the role of cannabinoids in various diseases Conclusion: Recent research on Cannabis has suggested its role in neurodegenerative diseases, inflammation, sleep disorders, pediatric diseases, and their analgesic nature. Therefore, the authors majorly focus on the therapeutic aspect of Cannabis sativa in various diseases. The focus is also on the endocannabinoid system (ECS) and its role in fighting or preventing bacterial, parasitic, fungal, and viral infections.

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.

Adjuvant Cannabinoid Receptor Type 2 Agonist Modulates the Polarization of Microglia Towards a Non-Inflammatory Phenotype in Experimental Pneumococcal Meningitis

Background

Microglia initiates and sustains the inflammatory reaction that drives the pathogenesis of pneumococcal meningitis. The expression of the G-protein cannabinoid receptor type 2 (CB2) in the brain is low, but is upregulated in glial cells during infection. Its activation down-regulates pro-inflammatory processes, driving microglia towards an anti-inflammatory phenotype. CB2 agonists are therefore therapeutic candidates in inflammatory conditions like pneumococcal meningitis. We evaluated the effects of JWH-133, a specific CB2 agonist on microglial cells, inflammation, and damage driven by S. pneumoniae in vitro and in experimental pneumococcal meningitis.

Materials/methods

Primary mixed glial cultures were stimulated with live or heat-inactivated S. pneumoniae, or lipopolysaccharide and treated with JWH-133 or vehicle. Nitric oxide and cytokines levels were measured in the supernatant. In vivo, pneumococcal meningitis was induced by intracisternal injection of live S. pneumoniae in 11 days old Wistar rats. Animals were treated with antibiotics (Ceftriaxone, 100 mg/kg, s.c. bid) and JWH-133 (1 mg/kg, i.p. daily) or vehicle (10% Ethanol in saline, 100 µl/25g body weight) at 18 h after infection. Brains were harvested at 24 and 42 h post infection (hpi) for histological assessment of hippocampal apoptosis and cortical damage and determination of cyto/chemokines in tissue homogenates. Microglia were characterized using Iba-1 immunostaining. Inflammation in brain homogenates was determined using membrane-based antibody arrays.

Results

In vitro, nitric oxide and cytokines levels were significantly lowered by JWH-133 treatment. In vivo, clinical parameters were not affected by the treatment. JWH-133 significantly lowered microglia activation assessed by quantification of cell process length and endpoints per microglia. Animals treated with JWH-133 demonstrated significantly lower parenchymal levels of chemokines (CINC-1, CINC-2α/β, and MIP-3α), TIMP-1, and IL-6 at 24 hpi, and CINC-1, MIP-1α, and IL-1α at 42 hpi. Quantitative analysis of brain damage did not reveal an effect of JWH-133.

Conclusions

JWH-133 attenuates microglial activation and downregulates the concentrations of pro-inflammatory mediators in pneumococcal infection in vitro and in vivo. However, we didn't observe a reduction in cortical or hippocampal injury. This data provides evidence that inhibition of microglia by adjuvant CB2 agonists therapy effectively downmodulates neuroinflammation but does not reduce brain damage in experimental pneumococcal meningitis.

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.

Potential pharmacological approaches for the treatment of HIV-1 associated neurocognitive disorders

HIV associated neurocognitive disorders (HAND) are the spectrum of cognitive impairments present in patients infected with human immunodeficiency virus type 1 (HIV-1). The number of patients affected with HAND ranges from 30 to 50% of HIV infected individuals and although the development of combinational antiretroviral therapy (cART) has improved longevity, HAND continues to pose a significant clinical problem as the current standard of care does not alleviate or prevent HAND symptoms. At present, the pathological mechanisms contributing to HAND remain unclear, but evidence suggests that it stems from neuronal injury due to chronic release of neurotoxins, chemokines, viral proteins, and proinflammatory cytokines secreted by HIV-1 activated microglia, macrophages and astrocytes in the central nervous system (CNS). Furthermore, the blood-brain barrier (BBB) not only serves as a route for HIV-1 entry into the brain but also prevents cART therapy from reaching HIV-1 brain reservoirs, and therefore could play an important role in HAND. The goal of this review is to discuss the current data on the epidemiology, pathology and research models of HAND as well as address the potential pharmacological treatment approaches that are being investigated.

Identification of novel phytocannabinoids from Ganoderma by label-free dynamic mass redistribution assay

ETHNOPHARMACOLOGICAL RELEVANCE

Located throughout the body, cannabinoid receptors (CB1 and CB2) are therapeutic targets for obesity/metabolic diseases, neurological/mental disorders, and immune modulation. Phytocannabinoids are greatly important for the development of new medicines with high efficacy and/or minor side effects. Plants and fungi are used in traditional medicine for beneficial effects to mental and immune system. The current research studied five fungi from the genus Ganoderma and five plants: Ganoderma hainanense J.D. Zhao, L.W. Hsu & X.Q. Zhang; Ganoderma capense (Lloyd) Teng, Zhong Guo De Zhen Jun; Ganoderma cochlear (Blume & T. Nees) Bres., Hedwigia; Ganoderma resinaceum Boud.; Ganoderma applanatum (Pers.) Pat.; Carthamus tinctorius L. (Compositae); Cynanchum otophyllum C. K. Schneid. (Asclepiadaceae); Coffea arabica L. (Rubiaceae); Prinsepia utilis Royle (Rosaceae); Lepidium meyenii Walp. (Brassicaceae). They show immunoregulation, promotion of longevity and maintenance of vitality, stimulant effects on the central nervous system, hormone balance and other beneficial effects. However, it remains unclear whether cannabinoid receptors are involved in these effects.

AIM OF THE STUDY

This work aimed to identify components working on CB1 and CB2 from the above plants and fungi, as novel phytocannabinoids, and to investigate mechanisms of how these compounds affected the cells. By analyzing the structure-activity relationship, we could identify the core structure for future development.

MATERIALS AND METHODS

Eighty-two natural compounds were screened on stably transfected Chinese hamster ovary (CHO) cell lines, CHO-CB1 and CHO-CB2, with application of a label-free dynamic mass redistribution (DMR) technology that measured cellular responses to compounds. CP55,940 and WIN55,212-2 were agonist probe molecules, and SR141716A and SR144528 were antagonist probes. Pertussis toxin, cholera toxin, LY294002 and U73122 were signaling pathway inhibitors. The DMR data were acquired by Epic Imager software (Corning, NY), processed by Imager Beta 3.7 (Corning), and analyzed by GraphPad Prism 6 (GraphPad Software, San Diego, CA).

RESULTS

Transfected CHO-CB1 and CHO-CB2 cell lines were established and characterized. Seven compounds induced responses/activities in the cells. Among the seven compounds, four were purified from two Ganoderma species with potencies between 20 and 35 μM. Three antagonists: Kfb68 antagonized both receptors with a better desensitizing effect on CB2 to WIN55,212-2 over CP55,940. Kga1 and Kfb28 were antagonists selective to CB1 and CB2, respectively. Kfb77 was a special agonist and it stimulated CB1 in a mechanism different from that of CP55,940. Another three active compounds, derived from the Lepidium meyenii Walp. (Brassicaceae), were also identified but their effects were mediated through mechanisms much related to the signaling transduction pathways, especially through the stimulatory G_s protein.

CONCLUSIONS

We identified four natural cannabinoids that exhibited structural and functional diversities. Our work confirms the presence of active ingredients in the Ganoderma species to CB1 and CB2, and this finding establishes connections between the fungi and the cannabinoid receptors, which will serve as a starting point to connect their beneficial effects to the endocannabinoid system. This research will also enrich the inventory of cannabinoids and phytocannabinoids from fungi. Yet due to some limitations, further structure-activity relationship studies and mechanism investigation are warranted in future.

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.

Confirmed marijuana use and lymphocyte count in black people living with HIV

BACKGROUND

Marijuana is a commonly used recreational substance with purported analgesic and mood enhancing properties. Many people living with HIV identify marijuana as a palliative substance. However, through its main psychoactive component, tetrahydrocannabinol (THC), is known to influence the immune system. The effects of marijuana use in people with HIV are still controversial, with very scant literature in Black adults.

METHODS

The current study determined the differences in the lymphocyte count, specifically the number cluster differentiation 4 and 8 (CD4+ and CD8+), among patients who urine drug tested negative for THC (n = 70) and those who tested positive for THC (n = 25). The sample included 95 Black people living with HIV, 51% female, with a mean age of 46 ± 11 years. Participants provided a urine sample for substance use testing and a trained researcher extracted clinical data from clinical charts on the day of appointment.

RESULTS

After adjusting for demographic and HIV-related covariates, THC-positive patients had significantly higher CD4+ and CD8+ counts than their THC-negative counterparts.

CONCLUSION

These results extend previous HIV-related immunity findings in an underrepresented group, and suggest that THC use does not reduce immune function as measured by CD count. Further research is warranted on the overall effects of THC on immune function in HIV positive patients.

Scaling Synapses in the Presence of HIV

A defining feature of HIV-associated neurocognitive disorder (HAND) is the loss of excitatory synaptic connections. Synaptic changes that occur during exposure to HIV appear to result, in part, from a homeostatic scaling response. Here we discuss the mechanisms of these changes from the perspective that they might be part of a coping mechanism that reduces synapses to prevent excitotoxicity. In transgenic animals expressing the HIV proteins Tat or gp120, the loss of synaptic markers precedes changes in neuronal number. In vitro studies have shown that HIV-induced synapse loss and cell death are mediated by distinct mechanisms. Both in vitro and animal studies suggest that HIV-induced synaptic scaling engages new mechanisms that suppress network connectivity and that these processes might be amenable to therapeutic intervention. Indeed, pharmacological reversal of synapse loss induced by HIV Tat restores cognitive function. In summary, studies indicate that there are temporal, mechanistic and pharmacological features of HIV-induced synapse loss that are consistent with homeostatic plasticity. The increasingly well delineated signaling mechanisms that regulate synaptic scaling may reveal pharmacological targets suitable for normalizing synaptic function in chronic neuroinflammatory states such as HAND.

Monoacylglycerol lipase inhibitor JZL184 prevents HIV-1 gp120-induced synapse loss by altering endocannabinoid signaling

Monoacylglycerol lipase (MGL) hydrolyzes 2-arachidonoylglycerol to arachidonic acid and glycerol. Inhibition of MGL may attenuate neuroinflammation by enhancing endocannabinoid signaling and decreasing prostaglandin (PG) production. Almost half of HIV infected individuals are afflicted with HIV-associated neurocognitive disorder (HAND), a neuroinflammatory disease in which cognitive decline correlates with synapse loss. HIV infected cells shed the envelope protein gp120 which is a potent neurotoxin that induces synapse loss. Here, we tested whether inhibition of MGL, using the selective inhibitor JZL184, would prevent synapse loss induced by gp120. The number of synapses between rat hippocampal neurons in culture was quantified by imaging clusters of a GFP-tagged antibody-like protein that selectively binds to the postsynaptic scaffolding protein, PSD95. JZL184 completely blocked gp120-induced synapse loss. Inhibition of MGL decreased gp120-induced interleukin-1β (IL-1β) production and subsequent potentiation of NMDA receptor-mediated calcium influx. JZL184-mediated protection of synapses was reversed by a selective cannabinoid type 2 receptor (CB2R) inverse agonist/antagonist. JZL184 also reduced gp120-induced prostaglandin E2 (PGE2) production; PG signaling was required for gp120-induced IL-1β expression and synapse loss. Inhibition of MGL prevented gp120-induced synapse loss by activating CB2R resulting in decreased production of the inflammatory cytokine IL-1β. Because PG signaling was required for gp120-induced synapse loss, JZL184-induced decreases in PGE2 levels may also protect synapses. MGL presents a promising target for preventing synapse loss in neuroinflammatory conditions such as HAND.

Confirmed marijuana use and lymphocyte count in black people living with HIV

BACKGROUND

Marijuana is a commonly used recreational substance with purported analgesic and mood enhancing properties. Many people living with HIV identify marijuana as a palliative substance. However, through its main psychoactive component, tetrahydrocannabinol (THC), is known to influence the immune system. The effects of marijuana use in people with HIV are still controversial, with very scant literature in Black adults.

METHODS

The current study determined the differences in the lymphocyte count, specifically the number cluster differentiation 4 and 8 (CD4+ and CD8+), among patients who urine drug tested negative for THC (n=70) and those who tested positive for THC (n=25). The sample included 95 Black people living with HIV, 51% female, with a mean age of 46±11years. Participants provided a urine sample for substance use testing and a trained researcher extracted clinical data from clinical charts on the day of appointment.

RESULTS

After adjusting for demographic and HIV-related covariates, THC-positive patients had significantly higher CD4+ and CD8+ counts than their THC-negative counterparts.

CONCLUSION

These results extend previous HIV-related immunity findings in an underrepresented group, and suggest that THC use does not reduce immune function as measured by CD count. Further research is warranted on the overall effects of THC on immune function in HIV positive patients.

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.

Curcumin improves synaptic plasticity impairment induced by HIV-1gp120 V3 loop

Curcumin has been shown to significantly improve spatial memory impairment induced by HIV-1 gp120 V3 in rats, but the electrophysiological mechanism remains unknown. Using extracellular microelectrode recording techniques, this study confirmed that the gp120 V3 loop could suppress long-term potentiation in the rat hippocampal CA1 region and synaptic plasticity, and that curcumin could antagonize these inhibitory effects. Using a Fura-2/AM calcium ion probe, we found that curcumin resisted the effects of the gp120 V3 loop on hippocampal synaptosomes and decreased Ca²⁺ concentration in synaptosomes. This effect of curcumin was identical to nimodipine, suggesting that curcumin improved the inhibitory effects of gp120 on synaptic plasticity, ameliorated damage caused to the central nervous system, and might be a potential neuroprotective drug.

Activation of Cannabinoid Type Two Receptors (CB2) Diminish Inflammatory Responses in Macrophages and Brain Endothelium

Chronic neuroinflammatory disorders (such as HIV associated neurodegeneration) require treatment that decreases production of inflammatory factors by activated microglia and macrophages and protection of blood brain barrier (BBB) injury secondary to activation of brain endothelium. Cannabioid type 2 receptor (CB2) is highly expressed on macrophages and brain microvasular enndothelial cells (BMVEC) and is upregulated in inflammation and HIV infection. It has been shown that CB2 activation dampened inflammatory responses in macrophages and BMVEC. In this study, we assessed by PCR array the expression of a wide range of genes increased in macrophages and BMVEC in inflammation. TNFα treatment upregulated 33 genes in primary human BMVEC, and two highly selective CB2 agonists diminished expression of 31 and 32 genes. These results were confirmed by functional assays (BBB protection after inflammatory insult and decreased migration of monocytes across BMVEC monolayers after CB2 stimulation). Similarly, CB2 stimulation in primary human macrophages led to the suppression of 35 genes out of the 50 genes upregulated by LPS. Such changes in gene expression paralleled diminished secretion of proinflammatory factors. These results indicate the potential utility of CB2 agonists for the treatment of neuroinflammation.

Effects of Cannabinoids on T-cell Function and Resistance to Infection

This review examines the effects of cannabinoids on immune function, with a focus on effects on T-cells, as well as on resistance to infection. The paper considers the immune modulating capacity of marijuana, of ∆(9)-THC extracted from the marijuana plant, and synthetic cannabinoids. Of particular interest are synthetic compounds that are CB2 receptor (CB2R) selective agonists. As the CB2R is principally expressed on cells of the immune system, agonists that target this receptor, and not CB1 (which is mainly expressed on neurons), have the possibility of altering immune function without psychoactive effects. The overall conclusion of the studies discussed in this review is that cannabinoids that bind to the CB2 receptor, including ∆(9)-THC and CB2 selective agonists are immunosuppressive. The studies provide objective evidence for potentially beneficial effects of marijuana and ∆(9)-THC on the immune system in conditions where it is desirable to dampen immune responses. Evidence is also reviewed supporting the conclusion that these same compounds can sensitize to some infections through their immunosuppressive activities, but not to others. An emerging area of investigation that is reviewed is evidence to support the conclusion that CB2 selective agonists are a new class of immunosuppressive and anti-inflammatory compounds that may have exceptional beneficial effects in a variety of conditions, such as autoimmune diseases and graft rejection, where it is desirable to dampen the immune response without psychoactive effects.