Role of anti-inflammatory compounds in human immunodeficiency virus-1 glycoprotein120-mediated brain inflammation

Chemokine Receptor Antagonists Prevent and Reverse Cofilin-Actin Rod Pathology and Protect Synapses in Cultured Rodent and Human iPSC-Derived Neurons

Synapse loss is the principal cause of cognitive decline in Alzheimer's disease (AD) and related disorders (ADRD). Synapse development depends on the intricate dynamics of the neuronal cytoskeleton. Cofilin, the major protein regulating actin dynamics, can be sequestered into cofilactin rods, intra-neurite bundles of cofilin-saturated actin filaments that can disrupt vesicular trafficking and cause synaptic loss. Rods are a brain pathology in human AD and mouse models of AD and ADRD. Eliminating rods is the focus of this paper. One pathway for rod formation is triggered in ~20% of rodent hippocampal neurons by disease-related factors (e.g., soluble oligomers of Amyloid-β (Aβ)) and requires cellular prion protein (PrPC), active NADPH oxidase (NOX), and cytokine/chemokine receptors (CCRs). FDA-approved antagonists of CXCR4 and CCR5 inhibit Aβ-induced rods in both rodent and human neurons with effective concentrations for 50% rod reduction (EC50) of 1-10 nM. Remarkably, two D-amino acid receptor-active peptides (RAP-103 and RAP-310) inhibit Aβ-induced rods with an EC50 of ~1 pM in mouse neurons and ~0.1 pM in human neurons. These peptides are analogs of D-Ala-Peptide T-Amide (DAPTA) and share a pentapeptide sequence (TTNYT) antagonistic to several CCR-dependent responses. RAP-103 does not inhibit neuritogenesis or outgrowth even at 1 µM, >106-fold above its EC50. N-terminal methylation, or D-Thr to D-Ser substitution, decreases the rod-inhibiting potency of RAP-103 by 103-fold, suggesting high target specificity. Neither RAP peptide inhibits neuronal rod formation induced by excitotoxic glutamate, but both inhibit rods induced in human neurons by several PrPC/NOX pathway activators (Aβ, HIV-gp120 protein, and IL-6). Significantly, RAP-103 completely protects against Aβ-induced loss of mature and developing synapses and, at 0.1 nM, reverses rods in both rodent and human neurons (T½ ~ 3 h) even in the continuous presence of Aβ. Thus, this orally available, brain-permeable peptide should be highly effective in reducing rod pathology in multifactorial neurological diseases with mixed proteinopathies acting through PrPC/NOX.

Characterization of a Human Neuronal Culture System for the Study of Cofilin-Actin Rod Pathology

Cofilactin rod pathology, which can initiate synapse loss, has been extensively studied in rodent neurons, hippocampal slices, and in vivo mouse models of human neurodegenerative diseases such as Alzheimer's disease (AD). In these systems, rod formation induced by disease-associated factors, such as soluble oligomers of Amyloid-β (Aβ) in AD, utilizes a pathway requiring cellular prion protein (PrPC), NADPH oxidase (NOX), and cytokine/chemokine receptors (CCR5 and/or CXCR4). However, rod pathways have not been systematically assessed in a human neuronal model. Here, we characterize glutamatergic neurons differentiated from human-induced pluripotent stem cells (iPSCs) for the formation of rods in response to activators of the PrPC-dependent pathway. Optimization of substratum, cell density, and use of glial-conditioned medium yielded a robust system for studying the development of Aβ-induced rods in the absence of glia, suggesting a cell-autonomous pathway. Rod induction in younger neurons requires ectopic expression of PrPC, but this dependency disappears by Day 55. The quantification of proteins within the rod-inducing pathway suggests that increased PrPC and CXCR4 expression may be factors in the doubling of the rod response to Aβ between Days 35 and 55. FDA-approved antagonists to CXCR4 and CCR5 inhibit the rod response. Rods were predominantly observed in dendrites, although severe cytoskeletal disruptions prevented the assignment of over 40% of the rods to either an axon or dendrite. In the absence of glia, a condition in which rods are more readily observed, neurons mature and fire action potentials but do not form functional synapses. However, PSD95-containing dendritic spines associate with axonal regions of pre-synaptic vesicles containing the glutamate transporter, VGLUT1. Thus, our results identified stem cell-derived neurons as a robust model for studying cofilactin rod formation in a human cellular environment and for developing effective therapeutic strategies for the treatment of dementias arising from multiple proteinopathies with different rod initiators.

Neuroprotective mechanism of salvianolic acid B against cerebral ischemia-reperfusion injury in mice through downregulation of TLR4, p-p38MAPK, p-JNK, NF-κB, and IL-1β

OBJECTIVE

Tissue injury and inflammation are two potential outcomes of cerebral ischemia-reperfusion (I/R) injury. Salvianolic acid B (Sal B), isolated from the roots of Salvia miltiorrhiza, is one of the major water-soluble compounds with a wide range of pharmacological effects including antioxidant, anti-inflammatory, antiproliferative, and neuroprotective effects. In the present study, we explored the neuroprotective effects and potential mechanisms of Sal B after I/R injury.

METHODS

We induced cerebral ischemia in male CD-1 mice through transient (60 min) middle cerebral artery occlusion (tMCAO), and then injected Sal B (30 mg/kg) intraperitoneally. Neurological deficits, infarct volumes, and brain edema were assessed at 24 and 72 h after tMCAO. We detected the expression of Toll-like receptor 4 (TLR4), phosphorylated-p38 mitogen-activated protein kinase (P-p38 MAPK), phosphorylated c-Jun amino (N)-terminal kinases (p-JNK), nuclear factor-κB (NF-κB), and interleukin-1β (IL-1β) in the brain tissue.

RESULTS

Compared with the tMCAO group, Sal B significantly improved neurological deficits, reduced infarct size, attenuated cerebral edema, and downregulated the expression of pro-inflammatory mediators TLR4, p-p38MAPK, p-JNK, nuclear NF-κB, and IL-1β in brain tissue after I/R injury.

CONCLUSION

We found that Sal B protects brain tissues from I/R injury by activating its anti-inflammatory properties.

Genomic Factors and Therapeutic Approaches in HIV-Associated Neurocognitive Disorders: A Comprehensive Review

HIV-associated neurocognitive disorders (HANDs) still persist despite improved life expectancy, reduced viral loads, and decreased infection severity. The number of patients affected by HANDs ranges from (30 to 50) % of HIV-infected individuals. The pathological mechanisms contributing to HANDs and the most serious manifestation of the disease, HIV-associated dementia (HAD), are not yet well understood. Evidence suggests that these mechanisms are likely multifactorial, producing neurocognitive complications involving disorders such as neurogenesis, autophagy, neuroinflammation, and mitochondrial dysfunction. Over the years, multiple pharmacological approaches with specific mechanisms of action acting upon distinct targets have been approved. Although these therapies are effective in reducing viral loading to undetectable levels, they also present some disadvantages such as common side effects, the need for administration with a very high frequency, and the possibility of drug resistance. Genetic studies on HANDs provide insights into the biological pathways and mechanisms that contribute to cognitive impairment in people living with HIV-1. Furthermore, they also help identify genetic variants that increase susceptibility to HANDs and can be used to tailor treatment approaches for HIV-1 patients. Identification of the genetic markers associated with disease progression can help clinicians predict which individuals require more aggressive management and by understanding the genetic basis of the disorder, it will be possible to develop targeted therapies to mitigate cognitive impairment. The main goal of this review is to provide details on the epidemiological data currently available and to summarise the genetic (specifically, the genetic makeup of the immune system), transcriptomic, and epigenetic studies available on HANDs to date. In addition, we address the potential pharmacological therapeutic strategies currently being investigated. This will provide valuable information that can guide clinical care, drug development, and our overall understanding of these diseases.

HIV gp120 impairs nucleus accumbens neuroimmune function and dopamine D3 receptor-mediated inhibition of cocaine seeking in male rats

Cocaine Use Disorders (CUDs) are associated with an increased risk of human immunodeficiency virus (HIV) infection. Cocaine and the HIV envelope protein gp120 each induce distinct deficits to mesocorticolimbic circuit function and motivated behavior; however, little is known regarding how they interact to dysregulate these functions or how such interactions impact pharmacotherapeutic efficacy. We have previously shown that the selective, weak partial agonist of the dopamine D3 receptor (D3R), MC-25-41, attenuates cocaine-seeking behavior in male rats. Here, we sought to characterize changes in striatal neuroimmune function in gp120-exposed rats across abstinence from operant access to cocaine (0.75 mg/kg, i.v.) or sucrose (45 mg/pellet), and to examine the impact of gp120 exposure on MC-25-41-reduced cocaine seeking. After establishing a history of cocaine or sucrose self-administration, rats received intracerebroventricular gp120 infusions daily the first 5 days of abstinence and were sacrificed either on day 6 or after 21 days of forced abstinence and a cue-induced cocaine seeking test. We demonstrated that MC-25-41 treatment attenuated cue-induced cocaine seeking among control rats but not gp120-exposed rats. Moreover, postmortem analysis of nucleus accumbens (NAc) core neuroimmune function indicated cocaine abstinence- and gp120-induced impairments, and the expression of several immune factors within the NAc core significantly correlated with cocaine-seeking behavior. We conclude that cocaine abstinence dysregulates striatal neuroimmune function and interacts with gp120 to inhibit the effectiveness of a D3R partial agonist in reducing cocaine seeking. These findings highlight the need to consider comorbidities, such as immune status, when evaluating the efficacy of novel pharmacotherapeutics.

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.

Transporter Regulation in Critical Protective Barriers: Focus on Brain and Placenta

Drug transporters play an important role in the maintenance of chemical balance and homeostasis in different tissues. In addition to their physiological functions, they are crucial for the absorption, distribution, and elimination of many clinically important drugs, thereby impacting therapeutic efficacy and toxicity. Increasing evidence has demonstrated that infectious, metabolic, inflammatory, and neurodegenerative diseases alter the expression and function of drug transporters. However, the current knowledge on transporter regulation in critical protective barriers, such as the brain and placenta, is still limited and requires more research. For instance, while many studies have examined P-glycoprotein, it is evident that research on the regulation of highly expressed transporters in the blood–brain barrier and blood–placental barrier are lacking. The aim of this review is to summarize the currently available literature in order to better understand transporter regulation in these critical barriers.

Regulation of ABC Drug Efflux Transporters in Human T-Cells Exposed to an HIV Pseudotype

ATP-binding cassette (ABC) drug efflux transporters could contribute to low intracellular concentrations of antiretroviral drugs in HIV-1 cell reservoirs and sanctuary sites. Furthermore, the functional expression of these transporters could be induced in activated T-cells. Therefore, we investigated the expression of ABC drug efflux transporters in human T-cells exposed to an HIV pseudotype virus (pHIV_NL4-3), and further examined the potential involvement of the mammalian target of rapamycin (mTOR) signaling pathway in regulating their expression following exposure to pHIV_NL4-3. Additionally, we investigated the contribution of the drug efflux transporters to the inflammatory response following pHIV_NL4-3-induced T-cell activation. Human peripheral blood mononuclear cells (PBMCs) were exposed to HIV-1 envelope glycoprotein gp120_IIIB, pHIV_NL4-3 and/or mTOR inhibitors. The expression of ABC transporters, T-cell activation marker CD69, mTOR and pHIV_NL4-3 was assessed in CD4⁺ T-cells by Flow cytometry. mRNA and protein levels of proinflammatory cytokines (IL6, TNFα and INFγ) were examined in PBMCs by qPCR and ELISA analyses, respectively, following exposure to pHIV_NL4-3 with or without inhibitors of mTOR or ABC transporters. The expression of ABC transporters (P-glycoprotein, breast cancer resistance protein and multi-drug resistance associated protein-1) was significantly increased in CD4⁺ T-cells exposed to pHIV_NL4-3. Treatment with mTOR inhibitors attenuated pHIV_NL4-3-induced transporter expression, as well as mRNA and protein levels of IL6, TNFα and INFγ. Additionally, inhibition of P-gp or MRP1 activity resulted in lower concentrations of proinflammatory cytokines in supernatants of PBMC exposed to pHIV_NL4-3. Herein we present novel data demonstrating that upregulation of ABC drug efflux transporters could involve the mTOR signaling pathway in CD4⁺ T-cells exposed to an HIV pseudotype. These transporters could limit antiretroviral drug penetration in HIV target T-cells. Furthermore, ABC transporters could potentially contribute to HIV-associated proinflammatory cytokine secretion.

HIV-1 Sanctuary Sites-the Role of Membrane-Associated Drug Transporters and Drug Metabolic Enzymes

Despite significant advances in the treatment of human immunodeficiency virus-1 (HIV) infection with highly active antiretroviral drug therapy, the persistence of the virus in cellular and anatomic reservoirs is a major obstacle preventing total HIV eradication. Viral persistence could result from a variety of contributing factors including, but not limited to, non-adherence to treatment and adverse drug reactions, latently infected cells carrying replication-competent virus, drug-drug interactions, and inadequate antiretroviral drug (ARV) concentrations reached in several anatomic sites such as the brain, testis, and gut-associated lymphoid tissues. The distribution of ARVs at specific sites of infection is primarily dependent on drug physicochemical properties and drug plasma protein binding, as well as drug efflux, influx, and metabolic processes. A thorough understanding of the functional roles of drug transporters and metabolic enzymes in the disposition of ARVs in immune cell types and tissues that are characterized as HIV reservoirs and sanctuaries is critical to overcome the challenge of suboptimal drug distribution at sites of persistent HIV infection. This review summarizes the current knowledge related to the expression and function of drug transporters and metabolic enzymes in HIV cellular and anatomic reservoirs, and their potential contribution to drug-drug interactions and insufficient drug concentration at these sites.

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.

Chloroquine pretreatment attenuates ischemia-reperfusion injury in the brain of ob/ob diabetic mice as well as wildtype mice

Chloroquine, a prototype anti-malaria drug, has been reported to possess anti-inflammatory effects. Moreover, chloroquine pretreatment could improve DNA damage repair. It is therefore reasonable to hypothesize that chloroquine pretreatment could attenuate ischemia/reperfusion injury in the brain. Considering the fact that chloroquine could also improve glucose metabolism, we speculated that the potential effects of chloroquine on ischemia/reperfusion injury might be particularly pronounced in diabetic mice. In this study, chloroquine pretreatment protected neurons from Oxygen Glucose Deprivation (OGD) induced cytotoxicity and apoptosis. In vivo, Ob/ob mice and wildtype (WT) mice were pretreated with chloroquine for 3 weeks. Then, ischemic stroke was induced by 60 min Middle Cerebral Artery Occlusion (MCAO). We found that chloroquine pretreatment normalized blood glucose in diabetic ob/ob mice, and reduced cerebral damage after ischemic stroke especially for diabetic mice. In addition, chloroquine pretreatment reduced High-mobility group box 1 (HMGB1) content in the cerebrospinal fluid (CSF) and serum and lowered myeloperoxidase (MPO) activity and inflammatory cytokines gene expression both in the ob/ob diabetic mice and WT mice. Moreover, harmful DNA damage-signaling responses, including PARP activation and p53 activation, were also attenuated by chloroquine pretreatment in these two kinds of mice. In conclusion, chloroquine pretreatment could reduce cerebral damage after ischemic stroke especially in diabetic mice through multiple mechanisms, which include reducing neural cell DNA injury, restoring euglycemia and anti-inflammatory effects. The findings may provide potential for the development of chloroquine in the prevention and treatment of stroke in diabetic high-risk patients.

Selective peroxisome proliferator-activated receptor-gamma modulator, INT131 exhibits anti-inflammatory effects in an EcoHIV mouse model

Despite the use of antiretroviral therapy for the treatment of HIV-1 infection, cognitive impairments, that is, HIV-1-associated neurocognitive disorders remain prevalent potentially due to persistent viral replication, production of viral proteins, associated brain inflammation or in certain instances, antiretroviral neurotoxicity. Cellular targets in the brain include microglia which in response to infection release inflammatory markers and viral proteins. Evidence suggests that PPARγ agonists exert anti-inflammatory properties in neurological disorders. However, these agonists namely, thiazolidinediones have limited use in the clinic due to reported adverse side effects. INT131 is a novel non-thiazolidinedione compound that belongs to a new class of drugs known as selective PPARγ modulators. INT131 is considered to have a safer profile; however, its neuroprotective role in vivo is not known.The goal of this study was to examine the effect of INT131 in the context of EcoHIV-induced inflammation in vitro, in primary cultures of mouse glial cells and in vivo, in a mouse model of EcoHIV-associated brain inflammation, as well as characterize its pharmacokinetic properties and brain penetration. In primary cultures of glial cells and in the in vivo mouse model, EcoHIV exposure resulted in a significant elevation of inflammatory markers such as TNFα, IL-1β, CCL3, and C3 which were attenuated with INT131 treatment. Pharmacokinetic analyses revealed that INT131 penetrates into the brain with a brain to blood partition ratio Kp value of 8.5%. Overall, this is the first report to demonstrate that INT131 could be a potential candidate for the treatment of HIV-1-associated brain inflammation.

URB597 protects against NLRP3 inflammasome activation by inhibiting autophagy dysfunction in a rat model of chronic cerebral hypoperfusion

Background

Previous studies reported that URB597 (URB) had therapeutic potential for treating chronic cerebral hypoperfusion (CCH)-induced neuroinflammation and autophagy dysfunction. However, the interaction mechanisms underlying the CCH-induced abnormal excessive autophagy and neuroinflammation remain unknown. In this study, we investigated the roles of impaired autophagy in nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing (NLRP) 3 inflammasome activation in the rat hippocampus and the underlying mechanisms under the condition of induced CCH as well as the effect of URB treatment.

Methods

The CCH rat model was established by bilateral common carotid artery occlusion (BCCAo), and rats were randomly divided into 11 groups as follows: (1) sham-operated, (2) BCCAo; (3) BCCAo+autophagy inhibitor 3-methyladenine (3-MA), (4) BCCAo+lysosome inhibitor chloroquine (CQ), (5) BCCAo+microglial activation inhibitor minocycline, (6) BCCAo+ROS scavenger N-acetylcysteine (NAC), (7) BCCAo+URB, (8) BCCAo+URB+3-MA, (9) BCCAo+URB+CQ, (10) BCCAo+URB+minocycline, (11) BCCAo+URB+NAC. The cell localizations of LC3, p62, LAMP1, TOM20 and NLRP3 were assessed by immunofluorescence staining. The levels of autophagy-related proteins (LC3, p62, LAMP1, BNIP3 and parkin), NLRP3 inflammasome-related proteins (NLRP3, CASP1 and IL-1β), microglial marker (OX-42) and proinflammatory cytokines (iNOS and COX-2) were evaluated by western blotting, and proinflammatory cytokines (IL-1β and TNF-a) were determined by ELISA. Reactive oxygen species (ROS) were assessed by dihydroethidium staining. The mitochondrial ultrastructural changes were examined by electron microscopy.

Results

CCH induced microglial overactivation and ROS accumulation, promoting the activation of the NLRP3 inflammasome and the release of IL-1β. Blocked autophagy and mitophagy flux enhanced the activation of the NLRP3-CASP1 inflammasome pathway. However, URB alleviated impaired autophagy and mitophagy by decreasing mitochondrial ROS and microglial overactivation as well as restoring lysosomal function, which would further inhibit the activation of the NLRP3-CASP1 inflammasome pathway.

Conclusion

These findings extended previous studies indicating the function of URB in the mitigation of chronic ischemic injury of the brain.

NLRP3-dependent pyroptosis is required for HIV-1 gp120-induced neuropathology

The human immunodeficiency virus-1 (HIV-1) envelope protein gp120 is the major contributor to the pathogenesis of HIV-associated neurocognitive disorder (HAND). Neuroinflammation plays a pivotal role in gp120-induced neuropathology, but how gp120 triggers neuroinflammatory processes and subsequent neuronal death remains unknown. Here, we provide evidence that NLRP3 is required for gp120-induced neuroinflammation and neuropathy. Our results showed that gp120-induced NLRP3-dependent pyroptosis and IL-1β production in microglia. Inhibition of microglial NLRP3 inflammasome activation alleviated gp120-mediated neuroinflammatory factor release and neuronal injury. Importantly, we showed that chronic administration of MCC950, a novel selective NLRP3 inhibitor, to gp120 transgenic mice not only attenuated neuroinflammation and neuronal death but also promoted neuronal regeneration and restored the impaired neurocognitive function. In conclusion, our data revealed that the NLRP3 inflammasome is important for gp120-induced neuroinflammation and neuropathology and suggest that NLRP3 is a potential novel target for the treatment of HAND.

Peroxisome Proliferator-Activated Receptor-gamma agonists exhibit anti-inflammatory and antiviral effects in an EcoHIV mouse model

The widespread use of combination antiretroviral therapy (cART) has resulted in significantly reduced deaths from HIV-1 associated complications and opportunistic infections. However, it is estimated that up to 50% of HIV-1 infected individuals still develop HIV-1 associated neurocognitive disorders (HAND). With no treatment currently available for patients, there is a critical need to identify therapeutic approaches that can treat this disorder. Evidence suggests that targeting Peroxisome Proliferator-Activated Receptor-gamma (PPARγ) can be anti-inflammatory in neurological disorders. Here we show that treatment with PPARγ agonists (rosiglitazone or pioglitazone) in primary cultures of mouse glial cells reversed EcoHIV-induced inflammatory genes (TNFα, IL-1β, CCL2, CCL3, CXCL10) and indicator of oxidative stress (iNOS). Furthermore, in vivo, mice administered with EcoHIV through intracranial injection resulted in upregulation of inflammatory genes (TNFα, IL-1β, IFNγ, CCL2, CCL3, CXCL10) and oxidative stress marker (iNOS) in the brain which was reversed through intraperitoneal administration of PPARγ agonists (rosiglitazone or pioglitazone). Finally, we demonstrated that treatment with these compounds in vivo reduced EcoHIV p24 protein burden in the brain. Our results suggest that treatment with PPARγ agonists are anti-inflammatory and antiviral in an in vivo model of EcoHIV infection. These drugs hold promise as potential candidates for HAND treatment in the future.

HIV gp120 upregulates tonic inhibition through α5-containing GABAARs

HIV-Associated Neurocognitive disorder (HAND) affects nearly half of infected patients. The HIV envelope protein gp120 is shed by infected cells and is a potent neurotoxin in vitro that reproduces many aspects of HAND when expressed in vivo. Here, we show that HIV gp120 increases the amplitude of a tonic current mediated by γ-aminobutyric acid type-A receptors (GABA_ARs). Treating rat hippocampal cultures with 600 pM gp120_IIIB for 4 h increased a tonic bicuculline-sensitive current, which remained elevated for 24 h. The increased current resulted from upregulation of extrasynaptic α5-containing GABA_ARs, as indicated by inhibition with the selective inverse agonist basmisanil. Treatment with gp120 increased α5-GABA_AR immunoreactivity on the cell surface without new protein synthesis. The increase in tonic inhibition was prevented by a C-X-C chemokine receptor type 4 (CXCR4) antagonist or elimination of microglia from the culture. Treatment with interleukin-1β (IL-1β) increased the tonic current and an IL-1 receptor antagonist blocked the gp120-evoked response. Pharmacological or genetic inhibition of p38 mitogen-activated protein kinase (MAPK) prevented the gp120-evoked increase in tonic current and direct activation of a mutant form of p38 MAPK expressed in neurons increased the current. Collectively, these data show that gp120 activates CXCR4 to stimulate microglia to release IL-1β. Subsequent stimulation of IL-1 receptors activates p38 MAPK in neurons leading to the upregulation of α5-containing GABA_ARs. Increased tonic inhibition impairs neuroplasticity and inhibition of α5-containing GABA_ARs improves cognitive function in disease models. Thus, gp120-induced upregulation of α5-containing GABA_ARs presents a novel therapeutic target for HAND.

HIV gp120-induced neuroinflammation potentiates NMDA receptors to overcome basal suppression of inhibitory synapses by p38 MAPK

HIV-associated neurocognitive disorder affects about half of HIV-infected patients. HIV impairs neuronal function through indirect mechanisms mainly mediated by inflammatory cytokines and neurotoxic viral proteins, such as the envelope protein gp120. HIV gp120 elicits a neuroinflammatory response that potentiates NMDA receptor function and induces the loss of excitatory synapses. How gp120 influences neuronal inhibition remains unknown. In this study, we expressed a green fluorescent protein (GFP)-tagged recombinant antibody-like protein that binds to the post-synaptic scaffolding protein gephyrin to label inhibitory synapses in living neurons. Treatment with 600 pM gp120 for 24 h increased the number of labeled inhibitory synapses. HIV gp120 evoked the release of interleukin-1β (IL-1β) from microglia to activate IL-1 receptors on neurons. Subsequent activation of the tyrosine kinase Src and GluN2A-containing NMDA receptors increased the number of inhibitory synapses via a process that required protein synthesis. In naïve cultures, inhibition of neuronal p38 mitogen-activated protein kinase (p38 MAPK) increased the number of inhibitory synapses suggesting that p38 MAPK produces a basal suppression of inhibitory synapses that is overcome in the presence of gp120. Direct activation of a mutant form of p38 MAPK expressed in neurons mimicked basal suppression of inhibitory synapses. This study shows for the first time that gp120-induced neuroinflammation increases the number of inhibitory synapses and that this increase overcomes a basal suppression of synaptic inhibition. Increased inhibition may be an adaptive mechanism enabling neurons to counteract excess excitatory input in order to maintain network homeostasis. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.

The effects of repetitive stress on tat protein-induced pro-inflammatory cytokine release and steroid receptor expression in the hippocampus of rats

Human immunodeficiency virus type 1 (HIV-1) affects the central nervous system (CNS) that may lead to the development of HIV-associated neuropathologies. Tat protein is one of the viral proteins that have been linked to the neurotoxic effects of HIV. Since many individuals living with HIV often experience significant adverse circumstances, the present study investigated whether exposure to stressful conditions would exacerbate harmful effects of tat protein on brain function. Tat protein (10 μg/10 μl) was injected bilaterally into the dorsal hippocampus of the animal using stereotaxic techniques. The control group received an injection of saline (10 μl). Some control and tat protein-treated animals were subjected to restrain stress for 6 h per day for 28 days and compared to a non-stress group. All animals underwent two behavioural tests, the open field test (OFT) and the novel object recognition test (NORT) to assess their mood state and cognitive function respectively. The release of pro-inflammatory cytokines (TNF-α and IL-1β) and the expression of mineralocorticoid (MR) and glucocorticoid (GR) receptors were also measured to see whether the impact of the repetitive stress on Tat protein-induced behavioural effects was mediated by elements of the immune system and the HPA axis. Rats treated with tat protein showed the following behavioural changes when compared to control animals: there was a significant decrease in time spent in the center of the open field during the OFT, a significant reduction in time spent with the novel object during the NORT, but no change in locomotor activity. Real-time PCR data showed that the expression levels of GR and MR mRNA were significantly reduced, while Western blot analysis showed that the protein expression levels of TNF-α and IL-1β were significantly increased. The present findings indicated that injection of tat protein into the hippocampus of rats not subjected to stress may lead to anxiety-like behaviour and deficits in learning and memory. Tat-treated animals subjected to stress evoked only a modest effect on their behaviour and neurochemistry, while stress alone led to behavioural and neurochemical changes similar to tat protein.

Peroxisome proliferator-activated receptor-gamma: potential molecular therapeutic target for HIV-1-associated brain inflammation

Background

Despite the use of combination antiretroviral therapy for the treatment of HIV-1 infection, cognitive impairments remain prevalent due to persistent viral replication and associated brain inflammation. Primary cellular targets of HIV-1 in the brain are macrophages, microglia, and to a certain extent astrocytes which in response to infection release inflammatory markers, viral proteins [i.e., glycoprotein 120 (gp120)] and exhibit impaired glutamate uptake. Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor superfamily of ligand-activated transcription factors. Compelling evidence suggests that PPARγ exerts anti-inflammatory properties in neurological disorders. The goal of this study was to examine the role of PPARγ in the context of HIV-1_ADA gp120-induced inflammation in vitro, in primary cultures of rat astrocytes and microglia, and in vivo, in a rodent model of HIV-1_ADA gp120-associated brain inflammation.

Methods

Primary mixed cultures of rat astrocytes and microglia were treated with PPARγ agonists (rosiglitazone or pioglitazone) and exposed to HIV-1_ADA gp120. Inflammatory cytokines and indicator of oxidative stress response (TNFα, IL-1β, iNOS) were measured using qPCR, and glutamate transporter (GLT-1) was quantified by immunoblotting. In vivo, rats were administered an intracerebroventricular injection of HIV-1_ADA gp120 and an intraperitoneal injection of PPARγ agonist (rosiglitazone) or co-administration with PPARγ antagonist (GW9662). qPCR and immunoblotting analyses were applied to measure inflammatory markers, GLT-1 and PPARγ.

Results

In primary mixed cultures of rat astrocytes and microglia, HIV-1_ADA gp120 exposure resulted in a significant elevation of inflammatory markers and a decrease in GLT-1 expression which were significantly attenuated with rosiglitazone or pioglitazone treatment. Similarly, in vivo, treatment with rosiglitazone reversed the gp120-mediated inflammatory response and downregulation of GLT-1. Furthermore, we demonstrated that the anti-inflammatory effects of PPARγ agonist rosiglitazone were mediated through inhibition of NF-κB.

Conclusion

Our data demonstrate that gp120 can induce an inflammatory response and decrease expression of GLT-1 in the brain in vitro and in vivo. We have also successfully shown that these effects can be reversed by treatment with PPARγ agonists, rosiglitazone or pioglitazone. Together our data suggest that targeting PPARγ signaling may provide an option for preventing/treating HIV-associated brain inflammation.

Electronic supplementary material

The online version of this article (10.1186/s12974-017-0957-8) contains supplementary material, which is available to authorized users.

Acute effects of focused ultrasound-induced increases in blood-brain barrier permeability on rat microvascular transcriptome

Therapeutic treatment options for central nervous system diseases are greatly limited by the blood-brain barrier (BBB). Focused ultrasound (FUS), in conjunction with circulating microbubbles, can be used to induce a targeted and transient increase in BBB permeability, providing a unique approach for the delivery of drugs from the systemic circulation into the brain. While preclinical research has demonstrated the utility of FUS, there remains a large gap in our knowledge regarding the impact of sonication on BBB gene expression. This work is focused on investigating the transcriptional changes in dorsal hippocampal rat microvessels in the acute stages following sonication. Microarray analysis of microvessels was performed at 6 and 24 hrs post-FUS. Expression changes in individual genes and bioinformatic analysis suggests that FUS may induce a transient inflammatory response in microvessels. Increased transcription of proinflammatory cytokine genes appears to be short-lived, largely returning to baseline by 24 hrs. This observation may help to explain some previously observed bioeffects of FUS and may also be a driving force for the angiogenic processes and reduced drug efflux suggested by this work. While further studies are necessary, these results open up intriguing possibilities for novel FUS applications and suggest possible routes for pharmacologically modifying the technique.

Limonene reduces hyperalgesia induced by gp120 and cytokines by modulation of IL-1 β and protein expression in spinal cord of mice

AIMS

We have investigated the antihyperalgesic effects of limonene in mice that received intrathecal injection of gp120.

MAIN METHODS

Male Swiss mice received gp120, IL-1β or TNF-α intrathecally or sterile saline as a control. A mechanical sensitivity test was performed at 2 and 3h after the injection. Spinal cord and blood samples were isolated for protein quantification.

KEY FINDINGS

Intrathecal administration of gp120 increased mechanical sensitivity measured with an electronic Von Frey apparatus, at 2 and 3h after the injections. Limonene administered orally prior to gp120 administration significantly decreased this mechanical sensitivity at 3h after the gp120 injection. In addition, intrathecal injection of gp120 increased IL-1β and IL-10 in serum, and limonene prevented the ability of gp120 to increase these cytokines. Limonene also inhibited TNF-α and IL-1β-induced mechanical hyperalgesia. Western blot assay demonstrated limonene was capable of increasing SOD expression in the cytoplasm of cells from spinal cord at 4h after intrathecal IL-1β injection.

SIGNIFICANCE

These results demonstrate that gp120 causes mechanical hyperalgesia and a peripheral increase in IL-1β and IL-10, and that prior administration of limonene inhibits these changes. Also limonene modulates the activation of SOD expression in the spinal cord after spinal IL-1β application. The ability of limonene to inhibit the mechanical hyperalgesia induced by gp120, TNF-α and IL-1β emphasizes the anti-inflammatory action of limonene, specifically its ability to inhibit cytokine production and its consequences.

Role and modulation of drug transporters in HIV-1 therapy

Current treatment of human immunodeficiency virus type-1 (HIV-1) infection involves a combination of antiretroviral drugs (ARVs) that target different stages of the HIV-1 life cycle. This strategy is commonly referred to as highly active antiretroviral therapy (HAART) or combined antiretroviral therapy (cART). Membrane-associated drug transporters expressed ubiquitously in mammalian systems play a crucial role in modulating ARV disposition during HIV-1 infection. Members of the ATP-binding cassette (ABC) and solute carrier (SLC) transporter superfamilies have been shown to interact with ARVs, including those that are used as part of first-line treatment regimens. As a result, the functional expression of drug transporters can influence the distribution of ARVs at specific sites of infection. In addition, pathological factors related to HIV-1 infection and/or ARV therapy itself can alter transporter expression and activity, thus further contributing to changes in ARV disposition and the effectiveness of HAART. This review summarizes current knowledge on the role of drug transporters in regulating ARV transport in the context of HIV-1 infection.

HIV-1 Alters Intestinal Expression of Drug Transporters and Metabolic Enzymes: Implications for Antiretroviral Drug Disposition

This study investigated the effects of HIV-1 infection and antiretroviral therapy (ART) on the expression of intestinal drug efflux transporters, i.e., P-glycoprotein (Pgp), multidrug resistance-associated proteins (MRPs), and breast cancer resistance protein (BCRP), and metabolic enzymes, such as cytochrome P450s (CYPs), in the human upper intestinal tract. Intestinal biopsy specimens were obtained from HIV-negative healthy volunteers, ART-naive HIV-positive (HIV(+)) subjects, and HIV(+) subjects receiving ART (10 in each group). Intestinal tissue expression of drug transporters and metabolic enzymes was examined by microarray, real-time quantitative reverse transcription-PCR (qPCR), and immunohistochemistry analyses. Microarray analysis demonstrated significantly lower expression of CYP3A4 and ABCC2/MRP2 in the HIV(+) ART-naive group than in uninfected subjects. qPCR analysis confirmed significantly lower expression of ABCC2/MRP2 in ART-naive subjects than in the control group, while CYP3A4 and ABCG2/BCRP showed a trend toward decreased expression. Protein expression of MRP2 and BCRP was also significantly lower in the HIV(+) naive group than in the control group and was partially restored to baseline levels in HIV(+) subjects receiving ART. In contrast, gene and protein expression of ABCB1/Pgp was significantly increased in HIV(+) subjects on ART relative to HIV(+) ART-naive subjects. These data demonstrate that the expression of drug-metabolizing enzymes and efflux transporters is significantly altered in therapy-naive HIV(+) subjects and in those receiving ART. Since CYP3A4, Pgp, MRPs, and BCRP metabolize or transport many antiretroviral drugs, their altered expression with HIV infection may negatively impact drug pharmacokinetics in HIV(+) subjects. This has clinical implications when using data from healthy volunteers to guide ART.

Therapy and pharmacological properties of hydroxychloroquine and chloroquine in treatment of systemic lupus erythematosus, rheumatoid arthritis and related diseases

OBJECTIVES

This review examines the pharmacokinetics, modes of action and therapeutic properties of the anti-malarial drugs, hydroxychloroquine (HCQ) and chloroquine (CQ), in the treatment of systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and related conditions, as well as osteoarthritis (OA).

KEY FINDINGS

Both HCQ and CQ have historically been employed successfully for the treatment of SLE and RA for over 70 years. HCQ has been used extensively for SLE where it has a good reputation for controlling the dermatological complications in SLE. It has also been reported to effectively control the symptoms of Sjøgren's syndrome, as well as preventing thrombosis in phospholipid antibody (aPL) syndrome. In RA and SLE, HCQ is preferred because of the lower incidence of gastrointestinal adverse reactions compared with CQ and it might have a lower risk of ocular adverse reactions. There is increasing evidence that HCQ may reduce atherosclerosis and risks of cardiovascular disease in rheumatic patients. Both HCQ and CQ have been shown to improve glycaemia and reduce the risks of type II diabetes mellitus. Although both HCQ and CQ are effective in low-moderate RA, HCQ is now preferred as part of combination therapy for more severe disease. The advantages of combination therapy are that the doses of the individual drugs may be lowered so reducing adverse reactions. Both HCQ and CQ are diastereoisomers, have basic properties and are given as the sulphate and phosphate salts. While being relatively well absorbed orally and with good bioavailability, they have long and variable plasma terminal elimination half-lives (approximately 40-60 days). This reflects their high volume of distribution, V D (HCQ 44,000L; CQ 65,000L) which extends into aqueous compartments, long mean residence time (HCQ 1300 h; CQ 900 h) and with about half the drugs (metabolites) undergoing renal clearance. The strong binding to melanin reflects the ocular injury and dermatological properties of these drugs. The consensus is that the occurrence of ocular adverse reactions can be minimised by close attention to the dose (which should be set on a body weight basis) with regular (e.g. quarterly) retinal examination. Although HCQ and CQ can pass through the placenta, the use of these drugs during pregnancy does not appear to risk harm to the baby and might be beneficial to the mother with SLE and her child by controlling the SLE disease activity, which is known to be an important factor affecting pregnancy outcome. The modes of action of HCQ and CQ in these arthritides represent somewhat of an enigma. Undoubtedly, these drugs have multiple actions related, in part, their ability to accumulate in lysosomes and autophagosomes of phagocytic cells as well as affecting MHC Class II expression and antigen presentation; actions of the production of pro-inflammatory cytokines [e.g. interleukin-1 (IL-1) tumour necrosis factor-α (TNFα)]; control of toll-like receptor-9 activation; and leucocyte generation of reactive oxygen species (ROS); i.e. antioxidant activity. The actions of these drugs on T and B cells are less clear but may depend on these leucocyte-mediated actions. Anti-malarials also protect against cytokine-mediated cartilage resorption. This and other actions may underlie the potential benefits in treating OA. The exact relationships of these various actions, mostly determined in vitro, have not been specifically defined in vivo or ex vivo in relation to clinical efficacy.

OUTCOMES

HCQ and CQ have a good reputation for being effective and relatively safe treatments in SLE, mild-moderate RA and Sjøgren's syndrome. There is need for (a) more information on their mode of action in relation to the control of these diseases, (b) scope for developing formulations that have improved pharmacokinetic and therapeutic properties and safety, and (c) further exploring their use in drug combinations not only with other disease modifying agents but also with biologics.

Effect of human immunodeficiency virus on blood-brain barrier integrity and function: an update

The blood-brain barrier (BBB) is a diffusion barrier that has an important role in maintaining a precisely regulated microenvironment protecting the neural tissue from infectious agents and toxins in the circulating system. Compromised BBB integrity plays a major role in the pathogenesis of retroviral associated neurological diseases. Human Immunodeficiency Virus (HIV) infection in the Central Nervous System (CNS) is an early event even before the serodiagnosis for HIV positivity or the initiation of antiretroviral therapy (ART), resulting in neurological complications in many of the infected patients. Macrophages, microglia and astrocytes (in low levels) are the most productively/latently infected cell types within the CNS. In this brief review, we have discussed about the effect of HIV infection and viral proteins on the integrity and function of BBB, which may contribute to the progression of HIV associated neurocognitive disorders.