Alcohol-induced interactive phosphorylation of Src and toll-like receptor regulates the secretion of inflammatory mediators by human astrocytes

Oxidative Stress in People Living With HIV: Are Diverse Supplement Sources the Solution?

Background and Aim

Antiretroviral therapy (ART) has reduced human immunodeficiency virus (HIV)/AIDS to a manageable chronic condition even though no cure exists. Despite ART control, latent HIV infection results in failed memory CD4 T-cell responses, immune overactivation, inflammation, oxidative stress, genomic instability, deoxyribonucleic acid (DNA) damage, and premature CD4 T-cell ageing. Overproduction of reactive oxygen species during oxidative stress can cause mitochondrial DNA damage, cancer, neurodegenerative and cardiovascular diseases, and premature aging in people living with HIV (PLWH). This review outlines current knowledge in oxidative stress among PLWH.

Methods

Google Scholar, Scopus, PubMed, and Science Direct were searched for literature conforming with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines from studies published from January 2013 to December 2023. A total of 75 studies from 22 countries were identified, with 52 studies carried out in human participants, 17 studies in cell lines, and 6 studies in animal models to assess oxidative stress levels.

Results

An increased oxidative stress with no changes in antioxidant levels was reported in HIV-positive smokers, and those on substance abuse. Long-term ART usage showed high levels of oxidative protein products and low levels of antioxidants when compared to short-term ART usage. The use of supplements such as N-acetylcysteine, selenium, and silibinin in animal models and cell lines showed increased cell viability, reduced reactive oxygen species, and increased antioxidant levels, which are promising therapeutic interventions that should be studied in PLWH to further help improve their disease outcomes.

Conclusions

Identifying extracts from natural and synthetic products with antioxidant effects will improve the general well-being of PLWH.

Ethanol-induced cerebellar transcriptomic changes in a postnatal model of fetal alcohol spectrum disorders: Focus on disease onset

Fetal alcohol spectrum disorders (FASD) are a group of neurodevelopmental disorders caused by ethanol exposure in utero, which can result in neurocognitive and behavioral impairments, growth defects, and craniofacial anomalies. FASD affects up to 1-5% of school-aged children in the United States, and there is currently no cure. The underlying mechanisms involved in ethanol teratogenesis remain elusive and need greater understanding to develop and implement effective therapies. Using a third trimester human equivalent postnatal mouse model of FASD, we evaluate the transcriptomic changes induced by ethanol exposure in the cerebellum on P5 and P6, after only 1 or 2 days of ethanol exposure, with the goal of shedding light on the transcriptomic changes induced early during the onset and development of FASD. We have highlighted key pathways and cellular functions altered by ethanol exposure, which include pathways related to immune function and cytokine signaling as well as the cell cycle. Additionally, we found that ethanol exposure resulted in an increase in transcripts associated with a neurodegenerative microglia phenotype, and acute- and pan-injury reactive astrocyte phenotypes. Mixed effects on oligodendrocyte lineage cell associated transcripts and cell cycle associated transcripts were observed. These studies help to elucidate the underlying mechanisms that may be involved with the onset of FASD and provide further insights that may aid in identifying novel targets for interventions and therapeutics.

The neuroimmune system - Where aging and excess alcohol intersect

As the percentage of the global population over age 65 grows, and with it a subpopulation of individuals with alcohol use disorder (AUD), understanding the effect of alcohol on the aged brain is of utmost importance. Neuroinflammation is implicated in both natural aging as well as alcohol use, and its role in alterations to brain morphology and function may be exacerbated in aging individuals who drink alcohol to excess. The neuroimmune response to alcohol in aging is complex. The few studies investigating this issue have reported heightened basal activity and either hypo- or hyper-reactivity to an alcohol challenge. This review of preclinical research will first introduce key players of the immune system, then explore changes in neuroimmune function with aging or alcohol alone, with discussion of vulnerable brain regions, changes in cytokines, and varied reactions of microglia and astrocytes. We will then consider different levels of alcohol exposure, relevant animal models of AUD, and neuroimmune activation by alcohol across the lifespan. By identifying key findings, challenges, and targets for future research, we hope to bring more attention and resources to this underexplored area of inquiry.

Cerebellar Transcriptomic Analysis in a Chronic plus Binge Mouse Model of Alcohol Use Disorder Demonstrates Ethanol-Induced Neuroinflammation and Altered Glial Gene Expression

Alcohol use disorder (AUD) is one of the most common preventable mental health disorders and can result in pathology within the CNS, including the cerebellum. Cerebellar alcohol exposure during adulthood has been associated with disruptions in proper cerebellar function. However, the mechanisms regulating ethanol-induced cerebellar neuropathology are not well understood. High-throughput next generation sequencing was performed to compare control versus ethanol-treated adult C57BL/6J mice in a chronic plus binge model of AUD. Mice were euthanized, cerebella were microdissected, and RNA was isolated and submitted for RNA-sequencing. Down-stream transcriptomic analyses revealed significant changes in gene expression and global biological pathways in control versus ethanol-treated mice that included pathogen-influenced signaling pathways and cellular immune response pathways. Microglial-associated genes showed a decrease in homeostasis-associated transcripts and an increase in transcripts associated with chronic neurodegenerative diseases, while astrocyte-associated genes showed an increase in transcripts associated with acute injury. Oligodendrocyte lineage cell genes showed a decrease in transcripts associated with both immature progenitors as well as myelinating oligodendrocytes. These data provide new insight into the mechanisms by which ethanol induces cerebellar neuropathology and alterations to the immune response in AUD.

Innate immune activation: Parallels in alcohol use disorder and Alzheimer’s disease

Alcohol use disorder is associated with systemic inflammation and organ dysfunction especially in the liver and the brain. For more than a decade, studies have highlighted alcohol abuse-mediated impairment of brain function and acceleration of neurodegeneration through inflammatory mechanisms that directly involve innate immune cells. Furthermore, recent studies indicate overlapping genetic risk factors between alcohol use and neurodegenerative disorders, specifically regarding the role of innate immunity in the pathomechanisms of both areas. Considering the pressing need for a better understanding of the relevance of alcohol abuse in dementia progression, here we summarize the molecular mechanisms of neuroinflammation observed in alcohol abuse and Alzheimer’s disease, the most common cause of dementia. In addition, we highlight mechanisms that are already established in the field of Alzheimer’s disease that may be relevant to explore in alcoholism to better understand alcohol mediated neurodegeneration and dementia, including the relevance of the liver-brain axis.

Possible mechanisms of HIV neuro-infection in alcohol use: Interplay of oxidative stress, inflammation, and energy interruption

Alcohol use and HIV-1 infection have a pervasive impact on brain function, which extends to the requirement, distribution, and utilization of energy within the central nervous system. This effect on neuroenergetics may explain, in part, the exacerbation of HIV-1 disease under the influence of alcohol, particularly the persistence of HIV-associated neurological complications. The objective of this review article is to highlight the possible mechanisms of HIV/AIDS progression in alcohol users from the perspective of oxidative stress, neuroinflammation, and interruption of energy metabolism. These include the hallmark of sustained immune cell activation and high metabolic energy demand by HIV-1-infected cells in the central nervous system, with at-risk alcohol use. Here, we discussed the point that the increase in energy supply requirement by HIV-1-infected neuroimmune cells as well as the deterrence of nutrient uptake across the blood-brain barrier significantly depletes the energy source and neuro-environment homeostasis in the CNS. We also described the mechanistic idea that comorbidity of HIV-1 infection and alcohol use can cause a metabolic shift and redistribution of energy usage toward HIV-1-infected neuroimmune cells, as shown in neuropathological evidence. Under such an imbalanced neuro-environment, meaningless energy waste is expected in infected cells, along with unnecessary malnutrition in non-infected neuronal cells, which is likely to accelerate HIV neuro-infection progression in alcohol use. Thus, it will be important to consider the factor of nutrients/energy imbalance in formulating treatment strategies to help impede the progression of HIV-1 disease and associated neurological disorders in alcohol use.

Chronic ethanol exposure induces neuroinflammation in H4 cells through TLR3 / NF-κB pathway and anxiety-like behavior in male C57BL/6 mice

Chronic alcoholism has become a major public health problem. Long-term and excessive drinking can lead to a variety of diseases. Chronic ethanol exposure can induce neuroinflammation and anxiety-like behavior, and this may be induced through the Toll-like receptor 3/nuclear factor-κB (TLR3/NF-κB) pathway. Animal experiments were performed using healthy adult male C57BL/6 N mice given 10 % (m/V) or 20 % ethanol solution as the only choice of drinkable fluid for 60, 90 or 180 d. In cell culture experiments, H4 human glioma cells were treated with 100 mM ethanol for 2 d, with the TLR3 gene silenced by RNAi and NF-κB inhibited by ammonium pyrrolidine dithiocarbamate (PDTC, 10 μM). After treatment with ethanol solution for a specific time, the anxiety-like behavior of the mice was tested using the open field test and the elevated plus maze test. Western blotting was used to detect the expression of TLR3, TLR4, NF-κB, IL-1β, IL-6, and TNF-α in the mouse hippocampus and H4 cells. The expression of IL-1β, IL-6 and TNF-α in the supernatant of cell culture medium was detected by ELISA. The open field test showed a decrease in time spent in the central area, and the elevated plus maze test showed a decrease in activity time in the open arm region. These behavioral tests indicated that ethanol caused anxiety-like behavior in mice. The expression levels of TLR3, TLR4, NF-κB, IL-1β, IL-6, and TNF-α increased after ethanol exposure in both the hippocampus of mice and H4 cells. Silencing of the TLR3 gene by RNAi or inhibition of NF-κB by PDTC attenuated the ethanol-induced increase in the expression of inflammatory factors in H4 cells. These findings indicated that chronic ethanol exposure increases the expression of TLR3 and NF-κB and produces neuroinflammation and anxiety-like behavior in male C57BL/6 mice and that ethanol-induced neuroinflammation can be caused through the TLR3/NF-κB pathway.

Downregulation of ROCK2 attenuates alcohol-induced inflammation and oxidative stress in astrocytes

OBJECTIVE

Alcohol abuse can cause severe injury to human brain. Astrocytes are the most abundant nonneuronal cells that function to maintain the brain homeostasis. In present study, we aimed to investigate the role of ROCK2 in astrocytes exposed to alcohol.

METHODS

Astrocytes were transfected with lentivirus (LV)-anti-ROCK2 vector to downregulate the expression of ROCK2. The ROCK2 expression in mRNA and protein level was analyzed by real-time PCR and Western blotting, respectively. Cytokines or indicators involved in inflammation and oxidative stress were determined by assay kits. Proteins involved in nuclear factor kappa B (NF-κB) signaling pathway and NOD-like receptor protein 3 (NLRP3) inflammasome were analyzed by Western blotting.

RESULTS

Alcohol exposure dramatically upregulated ROCK2 expression and lactate dehydrogenase (LDH) activity in astrocytes. On the contrary, transfecting with LV-anti-ROCK2 vector downregulated ROCK2 expression and LDH activity in astrocytes, demonstrating that downregulation of ROCK2 alleviated alcohol-induced astrocytic injury. Furthermore, downregulation of ROCK2 attenuated alcohol-induced inflammation by reducing the levels of pro-inflammatory cytokines (tumor necrosis factor (TNF)-α and interleukin (IL)-6) and enhanced the level of anti-inflammatory IL-10. Downregulation of ROCK2 also attenuated alcohol-induced oxidative stress by reducing the reactive oxygen species (ROS) production, as well as enhancing the activity of anti-oxidative superoxide dismutase (SOD) and glutathione (GSH). More importantly, downregulation of ROCK2 inhibited the activation of NF-κB signaling pathway and NLRP3 inflammasome.

CONCLUSION

Therefore, ROCK2 could be a potential target to treat alcohol-induced astrocytic injury and the downregulation of ROCK2 might be a promising approach to protect against alcohol-induced astrocytic injury.

Alcohol induces programmed death receptor-1 and programmed death-ligand-1 differentially in neuroimmune cells

Engagement of programmed death-1 (PD-1) receptor by its ligands (PD-L1/PD-L2) in activated immune cells is known to be involved in inflammatory neurological disease via a co-inhibitory signal pathway. Interaction of PD-1/PD-L1 is believed to occur only in activated neuroimmune cells because there are undetectable levels of PD-1/PD-L1 in normal physiological conditions. Here, we evaluated whether activation of neuroimmune cells such as human macrophage, brain endothelial cells (hBECs), astrocytes, microglia, and neurons by non-toxic concentrations of ethanol (EtOH) exposure can alter PD-1/PD-L1 expression. Thus, the present study is limited to the screening of PD-1/PD-L1 alterations in neuroimmune cells following ethanol exposure. We found that exposure of human macrophage or microglia to EtOH in primary culture immediately increased the levels of PD-L1 and gradually up-regulated PD-1 levels (beginning at 1-2 h). Similarly, ethanol exposure was able to induce PD-1/PD-L1 levels in hBECs and neuronal culture in a delayed process (occurring at 24 h). Astrocyte culture was the only cell type that showed endogenous levels of PD-1/PD-L1 that was decreased by EtOH exposure time-dependently. We concluded that ethanol (alcohol) mediated the induction of PD-1/PD-L1 differentially in neuroimmune cells. Taken together, our findings suggest that up-regulation of PD-1/PD-L1 by chronic alcohol use may dampen the innate immune response of neuroimmune cells, thereby contributing to neuroinflammation and neurodegeneration.

Antiretroviral drug-S for a possible HIV elimination

Although the combination of highly active antiretroviral therapy (cART) can remarkably control human immunodeficiency virus type-1 (HIV-1) replication, it fails to cure HIV/AIDS disease. It is attributed to the incapability of cART to eliminate persistent HIV-1 contained in latent reservoirs in the central nervous system (CNS) and other tissue organs. Thus, withdrawal of cART causes rebound viral replication and resurgent of HIV/AIDS. The lack of success on non-ART approaches for elimination of HIV-1 include the targeted molecules not reaching the CNS, not adjusting well with drug-resistant mutants, or unable to eliminate all components of viral life cycle. Here, we show that our newly discovered Drug-S can effectively inhibit HIV-1 infection and persistence at the low concentration without causing any toxicity to neuroimmune cells. Our results suggest that Drug-S may have a direct effect on viral structure, prevent rebounding of HIV-1 infection, and arrest progression into acquired immunodeficiency syndrome. We also observed that Drug-S is capable of crossing the blood-brain barrier, suggesting a potential antiretroviral drug for elimination of CNS viral reservoirs and self-renewal of residual HIV-1. These results outlined the possible mechanism(s) of action of Drug-S as a novel antiretroviral drug for elimination of HIV-1 replication by interfering the virion structure.

Umbelliferone alleviates hepatic injury in diabetic db/db mice via inhibiting inflammatory response and activating Nrf2-mediated antioxidant

The current study was designed to investigate the protective effect and possible mechanisms of umbelliferone (Umb) on liver injury in diabetic C57BL/KsJ-db/db (dbdb) mice. Mice were divided into five groups: wild-type mice group (WY), dbdb mice group, dbdb mice + Metformin (100 mg/kg) group, dbdb mice + Umb (20, 40 mg/kg) group. Blood glucose regulation was assessed by an oral glucose tolerance test (OGTT). At 28 days after drug administration, blood samples were obtained for the analysis of lipids and enzymes related to hepatic function, including alanine aminotransferase (ALT), aspartate aminotransaminase (AST) and total cholesterol (TC) and triglyceride (TG). Expression levels of inflammatory cytokines (TNF-α, IL-1β, and IL-6) and oxidative stress indicators (SOD and MDA) were measured with ELISA kit. The expressions of high-mobility group box 1 (HMGB1), Toll-like receptor (TLR) 4 (TLR4), Myd88, NF-κB, IκB, Nrf2, and HO-1 proteins were also evaluated by Western blotting analysis. The results showed that Umb significantly restored the blood glucose in OGTT, and inhibited the levels of insulin, TG, TC, as well as activities of ALT and AST. Moreover, Umb inhibited diabetic inflammation through down-regulating the expression of HMGB1, TLR4, NF-κB, and IκB. In addition, Umb alleviated oxidative damage in the liver by activating Nrf2-mediated signal pathway. These findings demonstrated that Umb exhibited protective effect against diabetic live injury, which may be through inhibiting HMGB1-induced inflammatory response and activating Nrf2-mediated antioxidant.

Prenatal Alcohol Exposure Is Associated With Adverse Cognitive Effects and Distinct Whole-Genome DNA Methylation Patterns in Primary School Children

Prenatal alcohol exposure (PAE) is known to elicit a broad range of systemic effects, including neurophysiological alterations that result in adverse behavioral and cognitive outcomes. However, molecular pathways underlying these long-term intrauterine effects remain to be investigated. Here, we tested a hypothesis that PAE may lead to epigenetic alterations to the DNA resulting in attentional and cognitive alterations of the children. We report the results of the study that included 156 primary school children of the Franconian Cognition and Emotion Studies (FRANCES) cohort which were tested for an objective marker of PAE, ethyl glucuronide (EtG) in meconium at birth. Thirty-two newborns were found to be exposed to alcohol with EtG values above 30 ng/g (EtG+). Previously we described PAE being associated with lower IQ and smaller amplitude of the event-related potential component P3 in go trials (Go-P3), which indicates a reduced capacity of attentional resources. Whole-genome methylation analysis of the buccal cell DNA revealed 193 differentially methylated genes in children with positive meconium EtG, that were clustered into groups involved in epigenetic modifications, neurodegeneration, neurodevelopment, axon guidance and neuronal excitability. Furthermore, we detected mediation effects of the methylation changes in DPP10 and SLC16A9 genes on the EtG related cognitive and attention-related deficits. Our results suggest that system-wide epigenetic changes are involved in long-term effects of PAE. In particular, we show an epigenetic mediation of PAE effects on cognition and attention-related processes.

Phosphodiesterase 4b expression plays a major role in alcohol-induced neuro-inflammation

It is increasingly evident that alcohol-induced, gut-mediated peripheral endotoxemia plays a significant role in glial cell activation and neuro-inflammation. Using a mouse model of chronic alcohol feeding, we examined the causal role of endotoxin- and cytokine-responsive Pde4 subfamily b (Pde4b) expression in alcohol-induced neuro-inflammation. Both pharmacologic and genetic approaches were used to determine the regulatory role of Pde4b. In C57Bl/6 wild type (WT) alcohol fed (WT-AF) animals, alcohol significantly induced peripheral endotoxemia and Pde4b expression in brain tissue, accompanied by a decrease in cAMP levels. Further, along with Pde4b, there was a robust activation of astrocytes and microglia accompanied by significant increases in the inflammatory cytokines (Tnfα, Il-1β, Mcp-1 and Il-17) and the generalized inflammatory marker Cox-2. At the cellular level, alcohol and inflammatory mediators, particularly LPS, Tnfα and Hmgb1 significantly activated microglial cells (Iba-1 expression) and selectively induced Pde4b expression with a minimal to no change in Pde4a and d isoforms. In comparison, the alcohol-induced decrease in brain cAMP levels was completely inhibited in WT mice treated with the Pde4 specific pharmacologic inhibitor rolipram and in Pde4b-/- mice. Moreover, all the observed markers of alcohol-induced brain inflammation were markedly attenuated. Importantly, glial cell activation induced by systemic endotoxemia (LPS administration) was also markedly decreased in Pde4b-/- mice. Taken together, these findings strongly support the notion that Pde4b plays a critical role in coordinating alcohol-induced, peripheral endotoxemia mediated neuro-inflammation and could serve as a significant therapeutic target.

Activation of NLRP3 inflammasome by cholesterol crystals in alcohol consumption induces atherosclerotic lesions

Epidemiological studies showed a strong association between alcoholism and incidence of stroke, for which the underlying causative mechanisms remain to be understood. Here we found that infiltration of immune cells and deposition of cholesterol at the site of brain artery/capillary injury induced atherosclerosis in chronic alcohol (ethanol) consumption in the presence or absence of high-fat diet. Conversion of cholesterol into sharp edges of cholesterol crystals (CCs) in alcohol intake was key to activation of NLRP3 inflammasome, induction of cerebral atherosclerosis, and development of neuropathy around the atherosclerotic lesions. The presence of alcohol was critical for the formation of CCs and development of the neuropathology. Thus, we observed that alcohol consumption elevated the level of plasma cholesterol, deposition and crystallization of cholesterol, as well as activation of NLRP3 inflammasome. This led to arteriole or capillary walls thickening and increase intracranial blood pressure. Distinct neuropathy around the atherosclerotic lesions indicated vascular inflammation as an initial cause of neuronal degeneration. We demonstrated the molecular mechanisms of NLRP3 activation and downstream signaling cascade event in primary culture of human brain arterial/capillary endothelial cells in the setting of dose-/time-dependent effects of alcohol/CCs using NLRP3 gene silencing technique. We also detected CCs in blood samples from alcohol users, which validated the clinical importance of the findings. Finally, combined therapy of acetyl-l-carnitine and Lipitor® prevented deposition of cholesterol, formation of CCs, activation of NLRP3, thickening of vessel walls, and elevation of intracranial blood pressure. We conclude that alcohol-induced accumulation and crystallization of cholesterol activates NLRP3/caspase-1 in the cerebral vessel that leads to early development of atherosclerosis.

Involvement of delta opioid receptors in alcohol withdrawal-induced mechanical allodynia in male C57BL/6 mice

BACKGROUND

As a legal drug, alcohol is commonly abused and it is estimated that 17 million adults in the United States suffer from alcohol use disorder. Heavy alcoholics can experience withdrawal symptoms including anxiety and mechanical allodynia that can facilitate relapse. The molecular mechanisms underlying this phenomenon are not well understood, which stifles development of new therapeutics. Here we investigate whether delta opioid receptors (DORs) play an active role in alcohol withdrawal-induced mechanical allodynia (AWiMA) and if DOR agonists may provide analgesic relief from AWiMA.

METHODS

To study AWiMA, adult male wild-type and DOR knockout C57BL/6 mice were exposed to alcohol by a voluntary drinking model or oral gavage exposure model, which we developed and validated here. We also used the DOR-selective agonist TAN-67 and antagonist naltrindole to examine the involvement of DORs in AWiMA, which was measured using a von Frey model of mechanical allodynia.

RESULTS

We created a robust model of alcohol withdrawal-induced anxiety and mechanical allodynia by orally gavaging mice with 3g/kg alcohol for three weeks. AWiMA was exacerbated and prolonged in DOR knockout mice as well as by pharmacological blockade of DORs compared to control mice. However, analgesia induced by TAN-67 was attenuated during withdrawal in alcohol-gavaged mice.

CONCLUSIONS

DORs appear to play a protective role in the establishment of AWiMA. Our current results indicate that DORs could be targeted to prevent or reduce the development of AWiMA during alcohol use; however, DORs may be a less suitable target to treat AWiMA during active withdrawal.

Disentangling the Role of Astrocytes in Alcohol Use Disorder

Several laboratories recently identified that astrocytes are critical regulators of addiction machinery. It is now known that astrocyte pathology is a common feature of ethanol (EtOH) exposure in both humans and animal models, as even brief EtOH exposure is sufficient to elicit long-lasting perturbations in astrocyte gene expression, activity, and proliferation. Astrocytes were also recently shown to modulate the motivational properties of EtOH and other strongly reinforcing stimuli. Given the role of astrocytes in regulating glutamate homeostasis, a crucial component of alcohol use disorder (AUD), astrocytes might be an important target for the development of next-generation alcoholism treatments. This review will outline some of the more prominent features displayed by astrocytes, how these properties are influenced by acute and long-term EtOH exposure, and future directions that may help to disentangle astrocytic from neuronal functions in the etiology of AUD.

1-Deoxynojirimycin Alleviates Liver Injury and Improves Hepatic Glucose Metabolism in db/db Mice

The present study investigated the effect of 1-Deoxynojirimycin (DNJ) on liver injury and hepatic glucose metabolism in db/db mice. Mice were divided into five groups: normal control, db/db control, DNJ-20 (DNJ 20 mg·kg⁻¹·day⁻¹), DNJ-40 (DNJ 40 mg·kg⁻¹·day⁻¹) and DNJ-80 (DNJ 80 mg·kg⁻¹·day⁻¹). All doses were treated intravenously by tail vein for four weeks. DNJ was observed to significantly reduce the levels of serum triglyceride (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and liver TG, as well as activities of serum alanine aminotransferase (ALT), and aspartate transaminase (AST); DNJ also alleviated macrovesicular steatosis and decreased tumor necrosis factor α (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6) levels in liver tissue. Furthermore, DNJ treatment significantly increased hepatic glycogen content, the activities of hexokinase (HK), pyruvate kinase (PK) in liver tissue, and decreased the activities of glucose-6-phosphatase (G6Pase), glycogen phosphorylase (GP), and phosphoenolpyruvate carboxykinase (PEPCK). Moreover, DNJ increased the phosphorylation of phosphatidylinositol 3 kinase (PI3K) on p85, protein kinase B (PKB) on Ser473, glycogen synthase kinase 3β (GSK-3β) on Ser9, and inhibited phosphorylation of glycogen synthase (GS) on Ser645 in liver tissue of db/db mice. These results demonstrate that DNJ can increase hepatic insulin sensitivity via strengthening of the insulin-stimulated PKB/GSK-3β signal pathway and by modulating glucose metabolic enzymes in db/db mice. Moreover, DNJ also can improve lipid homeostasis and attenuate hepatic steatosis in db/db mice.

Cytosolic phospholipase A2 regulates alcohol-mediated astrocyte inflammatory responses in HIV-associated neurocognitive disorders

Alcohol (EtOH) abuse and HIV-1 infection remain leading public health problems not only in the United States but also across the world. Alcohol abusers have a significantly greater risk of HIV-1 infection than non-drinkers globally. In the United States, prevalence of EtOH abuse is over two-fold higher in HIV-1-positive individuals than that of the general population. Although alcohol abusers show neurodegeneration, exacerbated neuroinflammation and oxidative damage, the mechanism(s) by which EtOH regulates astrocyte inflammatory responses in HIV-associated neurocognitive disorders is unknown. Thus, we explored signaling pathway(s) involved in EtOH-mediated activation of human astrocytes with HIV-1 and subsequent alterations in their inflammatory functions. Alcohol exposure altered the morphology of astrocytes, proinflammatory responses and induced cytotoxicity in a dose-dependent manner. Time-dependent changes were also evaluated. EtOH and HIV-1 cotreatment decreased cell viability and proliferation, while increasing apoptosis and mitochondrial depolarization. EtOH and HIV-1 together increased the levels of proinflammatory molecules, interleukin-1β, tumor necrosis factor-α, CXCL8, tissue inhibitor of metalloproteinases-1 and more importantly, arachidonic acid, a known downstream target of cytosolic phospholipase A₂ (cPLA₂). Consistent with this observation, phospho-cPLA₂ levels were augmented in HIV-1 and EtOH cotreatment as compared with HIV-1 or EtOH alone. Cyclooxygenase 2 was upregulated as measured by real-time PCR and western blot, whereas cotreatment of HIV-1 and EtOH decreased cytochrome P450-2E1 levels as compared with EtOH alone. Furthermore, we confirmed that blocking cPLA₂ with arachidonyl tri floro methyl ketone, a cPLA₂-specific inhibitor, effectively prevented cPLA₂ phosphorylation and downstream outcomes. Thus, the present findings suggest that cPLA₂ has a critical role in alcohol and HIV-induced astrocyte inflammation. In the future, cPLA₂ inhibitors may present novel therapeutic tools to treat alcohol abuse and HIV-associated neurocognitive disorder comorbidity.

Differential induction of PD-1/PD-L1 in Neuroimmune cells by drug of abuse

Interaction of programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1) plays a critical role in regulating the delicate balance between protective immunity and tolerance. Human neuroimmune cells express very low or undetectable levels of PD-1/PD-L1 in normal physiological condition.We seek to examine if exposure of these cells to drug of abuse such as methamphetamine (METH) alters the profile of PD-1/PD-L1 levels, thereby dampens the innate immune response of the host cells. Thus, we assessed the changes in the levels of PD-1/PD-L1 in primary human macrophages, brain endothelial cells (hBECs), astrocytes, microglia, and neurons after exposure to METH. We observed that stimulation of these neuroimmune cells by METH responded differentially to PD-1/PD-L1 expression. Stimulation of macrophage culture with 50 μM of METH exhibited immediate gradual upregulation of PD-L1, while increase in PD-1 took 2-4 hours later than PD-L1. The response of hBECs to PD-1/PD-L1 induction occurred at 24 hours, while increase of PD-1/PD-L1 levels in neurons and microglia was immediate following METH exposure. We found that astrocytes expressed moderate levels of endogenous PD-1/PD-L1, which was diminished by METH exposure. Our findings show a differential expression of PD-1/PD-L1 in neuroimmune cells in response to METH stimulation, suggesting that PD-1/PD-L1 interplay in these cell types could orchestrate the intercellular interactive communication for neuronal death or protection in the brain environment.

Drug abuse and the neurovascular unit

Drug abuse continues to create a major international epidemic affecting society. A great majority of past drug abuse research has focused mostly on the mechanisms of addiction and the specific effects of substance use disorders on brain circuits and pathways that modulate reward, motivation, craving, and decision making. Few studies have focused on the neurobiology of acute and chronic substance abuse as it relates to the neurovascular unit (brain endothelial cell, neuron, astrocyte, microglia, and pericyte). Increasing research indicates that all cellular components of the neurovascular unit play a pivotal role in both the process of addiction and how drug abuse affects the brain response to diseases. This review will focus on the specific effects of opioids, amphetamines, alcohol, and nicotine on the neurovascular unit and its role in addiction and adaption to brain diseases. Elucidation of the role of the neurovascular unit on the neurobiology associated with drug addiction will help to facilitate the development of better therapeutic approaches for drug-dependent individuals.

Role of cytosolic phospholipase A2 in oxidative and inflammatory signaling pathways in different cell types in the central nervous system

Phospholipases A(2) (PLA(2)s) are important enzymes for the metabolism of fatty acids in membrane phospholipids. Among the three major classes of PLA(2)s in the mammalian system, the group IV calcium-dependent cytosolic PLA(2) alpha (cPLA(2)α) has received the most attention because it is widely expressed in nearly all mammalian cells and its active participation in cell metabolism. Besides Ca(2+) binding to its C2 domain, this enzyme can undergo a number of cell-specific post-translational modifications, including phosphorylation by protein kinases, S-nitrosylation through interaction with nitric oxide (NO), as well as interaction with other proteins and lipid molecules. Hydrolysis of phospholipids by cPLA(2) yields two important lipid mediators, arachidonic acid (AA) and lysophospholipids. While AA is known to serve as a substrate for cyclooxygenases and lipoxygenases, which are enzymes for the synthesis of eicosanoids and leukotrienes, lysophospholipids are known to possess detergent-like properties capable of altering microdomains of cell membranes. An important feature of cPLA(2) is its link to cell surface receptors that stimulate signaling pathways associated with activation of protein kinases and production of reactive oxygen species (ROS). In the central nervous system (CNS), cPLA(2) activation has been implicated in neuronal excitation, synaptic secretion, apoptosis, cell-cell interaction, cognitive and behavioral function, oxidative-nitrosative stress, and inflammatory responses that underline the pathogenesis of a number of neurodegenerative diseases. However, the types of extracellular agonists that target intracellular signaling pathways leading to cPLA(2) activation among different cell types and under different physiological and pathological conditions have not been investigated in detail. In this review, special emphasis is given to metabolic events linking cPLA(2) to activation in neurons, astrocytes, microglial cells, and cerebrovascular cells. Understanding the molecular mechanism(s) for regulation of this enzyme is deemed important in the development of new therapeutic targets for the treatment and prevention of neurodegenerative diseases.

Fetal alcohol spectrum disorders and neuroimmune changes

The behavioral consequences of fetal alcohol spectrum disorders (FASD) are serious and persist throughout life. The causative mechanisms underlying FASD are poorly understood. However, much has been learned about FASD from human structural and functional studies as well as from animal models, which have provided a greater understanding of the mechanisms underlying FASD. Using animal models of FASD, it has been recently discovered that ethanol induces neuroimmune activation in the developing brain. The resulting microglial activation, production of proinflammatory molecules, and alteration in expression of developmental genes are postulated to alter neuron survival and function and lead to long-term neuropathological and cognitive defects. It has also been discovered that microglial loss occurs, reducing microglia's ability to protect neurons and contribute to neuronal development. This is important, because emerging evidence demonstrates that microglial depletion during brain development leads to long-term neuropathological and cognitive defects. Interestingly, the behavioral consequences of microglial depletion and neuroimmune activation in the fetal brain are particularly relevant to FASD. This chapter reviews the neuropathological and behavioral abnormalities of FASD and delineates correlates in animal models. This serves as a foundation to discuss the role of the neuroimmune system in normal brain development, the consequences of microglial depletion and neuroinflammation, the evidence of ethanol induction of neuroinflammatory processes in animal models of FASD, and the development of anti-inflammatory therapies as a new strategy for prevention or treatment of FASD. Together, this knowledge provides a framework for discussion and further investigation of the role of neuroimmune processes in FASD.

HIV-1 and alcohol: interactions in the central nervous system

The use of alcohol has been associated with both an increased risk of acquisition of HIV-1 infection and an increased rate of disease progression among those already infected by the virus. The potential for alcohol to exacerbate the effects of HIV infection is especially important in the central nervous system (CNS) because this area is vulnerable to the combined effects of alcohol and HIV infection. The effects of alcohol on glial cells are mediated through receptors such as Toll-like receptor 4 and N-methyl-d-aspartate receptor. This causes the activation of signaling molecules such as interleukin-1 receptor-associated kinase and various members of the P38 mitogen-activated protein kinase family and subsequent activation of transcription factors such as nuclear factor-kappa beta and activator protein 1. The eventual outcome is an increase in pro-inflammatory cytokine production by glial cells. Alcohol also induces higher levels of NADPH oxidase in glial cells, which leads to an increased production of reactive oxygen species (ROS). Viral invasion of the CNS occurs early after infection, and HIV proteins have also been demonstrated to increase levels of pro-inflammatory cytokines and ROS in glial cells through activation of some of the same pathways activated by alcohol. Both cell culture systems and animal models have demonstrated that concomitant exposure to alcohol and HIV/HIV proteins results in increased levels of expression of pro-inflammatory cytokines such as interleukin-1 beta and tumor necrosis factor-alpha, along with increased levels of oxidative stress. Clinical studies also suggest that alcohol exacerbates the CNS effects of HIV-1 infection. This review focuses on the mechanisms by which alcohol causes increased CNS damage in HIV-1 infection.

Reduction of brain mitochondrial β-oxidation impairs complex I and V in chronic alcohol intake: the underlying mechanism for neurodegeneration

Neuropathy and neurocognitive deficits are common among chronic alcohol users, which are believed to be associated with mitochondrial dysfunction in the brain. The specific type of brain mitochondrial respiratory chain complexes (mRCC) that are adversely affected by alcohol abuse has not been studied. Thus, we examined the alterations of mRCC in freshly isolated mitochondria from mice brain that were pair-fed the ethanol (4% v/v) and control liquid diets for 7–8 weeks. We observed that alcohol intake severely reduced the levels of complex I and V. A reduction in complex I was associated with a decrease in carnitine palmitoyltransferase 1 (cPT1) and cPT2 levels. The mitochondrial outer (cPT1) and inner (cPT2) membrane transporter enzymes are specialized in acylation of fatty acid from outer to inner membrane of mitochondria for ATP production. Thus, our results showed that alterations of cPT1 and cPT2 paralleled a decrease β-oxidation of palmitate and ATP production, suggesting that impairment of substrate entry step (complex I function) can cause a negative impact on ATP production (complex V function). Disruption of cPT1/cPT2 was accompanied by an increase in cytochrome C leakage, while reduction of complex I and V paralleled a decrease in depolarization of mitochondrial membrane potential (ΔΨ, monitored by JC-1 fluorescence) and ATP production in alcohol intake. We noted that acetyl-L-carnitine (ALC, a cofactor of cPT1 and cPT2) prevented the adverse effects of alcohol while coenzyme Q10 (CoQ10) was not very effective against alcohol insults. These results suggest that understanding the molecular, biochemical, and signaling mechanisms of the CNS mitochondrial β-oxidation such as ALC can mitigate alcohol related neurological disorders.

Phospholipase A2, oxidative stress, and neurodegeneration in binge ethanol-treated organotypic slice cultures of developing rat brain

BACKGROUND

Brain neurodamage from chronic binge ethanol (EtOH) exposure is linked to neuroinflammation and associated oxidative stress. Using rat organotypic hippocampal-entorhinal cortical (HEC) slice cultures of developing brain age, we reported that binge EtOH promotes release of a neuroinflammatory instigator, arachidonic acid (AA), concomitant with neurodegeneration, and that mepacrine, a global inhibitor of phospholipase A2 (PLA2) enzymes mobilizing AA from phospholipids, is neuroprotective. Here, we sought with binge EtOH-treated HEC cultures to establish that PLA2 activity is responsible in part for significant oxidative stress and to ascertain the PLA2 families responsible for AA release and neurodegeneration.

METHODS

HEC slices, prepared from 1-week-old rats and cultured 2 to 2.5 weeks, were exposed to 100 mM EtOH over 6 successive days, with 4 daytime "withdrawals" (no EtOH). Brain 3-nitrotyrosinated (3-NT)- and 4-hydroxy-2-nonenal (4-HNE)-adducted proteins, oxidative stress footprints, were immunoassayed on days 3 through 6, and mepacrine's effect was determined on day 6. The effects of specific PLA2 inhibitors on neurodegeneration (propidium iodide staining) and AA release (ELISA levels in media) in the cultures were then determined. Also, the effect of JZL184, an inhibitor of monoacylglycerol lipase (MAGL) which is reported to mobilize AA from endocannabinoids during neuroinflammatory insults, was examined.

RESULTS

3-NT- and 4-HNE-adducted proteins were significantly increased by the binge EtOH exposure, consistent with oxidative stress, and mepacrine prevented the increases. The PLA2 inhibitor results implicated secretory PLA2 (group II sPLA2) and to some extent Ca(2+) -independent cytosolic PLA2 (group VI iPLA2) in binge EtOH-induced neurotoxicity and in AA release, but surprisingly, Ca(2+) -dependent cytosolic PLA2 (group IV cPLA2) did not appear important. Furthermore, unlike PLA2 inhibition, MAGL inhibition failed to prevent the neurodegeneration.

CONCLUSIONS

In these developing HEC slice cultures, pro-oxidative signaling via sPLA2 and iPLA2, but not necessarily cPLA2 or MAGL, is involved in EtOH neurotoxicity. This study provides further insights into neuroinflammatory phospholipase signaling and oxidative stress underlying binge EtOH-induced neurodegeneration in developing (adolescent age) brain in vitro.

Protective reactivity and alteration of the brain tissue in alcoholics evidenced by SOD1, MMP9 immunohistochemistry, and electron microscopy

Alcohol and its associated oxidative stress is one of the widespread contributors to the brain damage. Matrix metalloproteinases, which are extensively analyzed in brain pathology studies, are not sufficiently investigated in chronic alcohol consumption. This study evaluated regional brain damage caused by oxidative stress. Contribution of metalloproteinase-9 to this affection was evidenced in alcoholic subjects and correlated with ultrastructural changes. The authors found correlation between neuronal expression patterns of superoxide dismutase-1 and metalloproteinase-9 in nigral (r = 0.532, p < 0.001), striatal (r = 0.327, p < 0.001), and cortical (r = 0.306, p < 0.001) regions, and a significant decrease of nigral superoxide dismutase-1 median values accompanied by severe myelin damage.

Inhibition of glycogen synthase kinase-3β by lithium chloride suppresses 6-hydroxydopamine-induced inflammatory response in primary cultured astrocytes

An increasing amount of evidence has emerged to suggest that neuroinflammatory process is involved in the pathogenesis of Parkinson's disease (PD). Activated microglia and astrocytes are found in the substantia nigra (SN) of Parkinson's disease brains as well as in animal models of Parkinson's disease. Although reactive astrocytes are involved in the progression of PD, the role of reactive astrocytes in neuroinflammation of PD has received limited attention to date. Recently, Glycogen synthase kinase-3β (GSK-3β) was identified as a crucial regulator of the inflammatory response. The purpose of this study was to explore the mechanism by which 6-hydroxydopamine (6-OHDA) induces inflammatory response in astrocytes and observe the anti-inflammatory effect of lithium chloride (LiCl) on 6-OHDA-treated astrocytes. In the present study, we found that glial fibrillary acidic protein (GFAP) was markedly upregulated in the presence of 6-OHDA. Moreover, our results revealed that proinflammatory molecules including inducible nitric oxide synthase (iNOS), nitric oxide (NO), cyclooxygenase-2(COX-2), prostaglandins E2 (PGE2), and tumor necrosis factor-α (TNF-α) were obviously increased in astrocytes exposed to 6-OHDA. Western blot analysis revealed that 6-OHDA significantly increased dephosphorylation/activation of GSK-3β as well as the nuclear translocation of nuclear factor-κB (NF-κB) p65. Besides, GSK-3β inhibitor LiCl and SB415286 inhibited the GSK-3β/NF-κB signaling pathway, leading to the reduction of proinflammatory molecules in 6-OHDA-activated astrocytes. These results confirmed that GSK-3β inhibitor LiCl and SB415286 provide protection against neuroinflammation in 6-OHDA-treated astrocytes. Therefore, GSK-3β may be a potential therapeutic target for the treatment of PD.

At low doses ethanol maintains blood-brain barrier (BBB) integrity after hypoxia and reoxygenation: a brain slice study

Post-ischemia ethanol (EtOH) treatments have been shown to exhibit neuroprotective effects in stroke. However, the mechanisms underlying these effects and those on blood-brain barrier (BBB) integrity have yet to be elucidated. In the present study, we determined whether administering differing concentrations of EtOH alter the expressions of BBB integral proteins, including aquaporins-4 and -9 (AQP-4, AQP-9), matrix metallopeptidases-2 and -9 (MMP-2, MMP-9), zonula occludens-1 (ZO-1), and basal lamina (laminin). We employed an organotypic brain slice culture model that utilizes oxygen-glucose deprivation followed by reoxygenation (OGD/R). Brain slices were obtained from 10-day-old Sprague-Dawley rats and divided into the following five groups (n = 8 subjects per group): (1) control, (2) hypoxia (OGD/R), no EtOH, (3) OGD/R and 10 mM EtOH, (4) OGD/R and 30 mM EtOH, and (5) OGD/R and 90 mM EtOH. To assess BBB integrity, levels of AQPs, MMPs, ZO-1, and laminin were determined by Western blot. Compared to control, OGD/R without EtOH significantly increased AQP-4, AQP-9, MMP-2, and MMP-9 levels, while decreasing ZO-1 and laminin levels. All EtOH concentration treatments (groups 3 through 5) significantly reduced the expressions of AQP-4, AQP-9, MMP-2, and MMP-9, compared to the OGD/R, non-alcohol treated slices. Furthermore, compared to the OGD/R without EtOH group, the 30 mM EtOH treatment significantly increased ZO-1 and laminin levels. In contrast, the 90 mM EtOH level neither enhanced the reduction in AQP and MMP levels nor increased ZO-1 or basal lamina expressions observed in the 30 mM treatment. In conclusion, at an optimal dose of 30 mM, EtOH improves the expressions of MMP-2, MMP-9, AQP-4, AQP-9, ZO-1, and basal laminin, previously altered by OGD/R. These effects may indicate a beneficial effect of EtOH on BBB integrity after stroke.

Effect of repetitive daily ethanol intoxication on adult rat brain: significant changes in phospholipase A2 enzyme levels in association with increased PARP-1 indicate neuroinflammatory pathway activation

Collaborating on studies of subchronic daily intoxication in juvenile and adult rats, we examined whether the repetitive ethanol treatments at these two life stages altered levels of key neuroinflammation-associated proteins-aquaporin-4 (AQP4), certain phospholipase A2 (PLA2) enzymes, PARP-1 and caspase-3-in hippocampus (HC) and entorhinal cortex (EC). Significant changes in the proteins could implicate activation of specific neuroinflammatory signaling pathways in these rats as well as in severely binge-intoxicated adult animals that are reported to incur degeneration of vulnerable neurons in HC and EC. Male Wistar rats, ethanol-intoxicated (3 g/kg i.p.) once daily for 6 days over an 8-day interval beginning at 37 days old and repeated at age 68-75 days, were sacrificed 1 h after the day 75 dose (blood ethanol, 200- 230 mg/dl). Analysis of HC with an immunoblot technique showed that AQP4, Ca(+2)-dependent PLA2 (cPLA2 IVA), phosphorylated (activated) p-cPLA2, cleaved (89 kD) PARP (c-PARP), and caspase-3 levels were significantly elevated over controls, whereas Ca(+2)-independent PLA2 (iPLA2 VIA) was reduced ∼70%; however, cleaved caspase-3 was undetectable. In the EC, AQP4 was unchanged, but cPLA2 and p-cPLA2 were significantly increased while iPLA2 levels were diminished (∼40%) similar to HC, although just outside statistical significance (p = 0.06). In addition, EC levels of PARP-1 and c-PARP were significantly increased. The ethanol-induced activation of cPLA2 in association with reduced iPLA2 mirrors PLA2 changes in reports of neurotrauma and also of dietary omega-3 fatty acid depletion. Furthermore, the robust PARP-1 elevations accompanied by negligible caspase-3 activation indicate that repetitive ethanol intoxication may be potentiating non-apoptotic neurodegenerative processes such as parthanatos. Overall, the repetitive ethanol treatments appeared to instigate previously unappreciated neuroinflammatory pathways in vivo. The data provide insights into mechanisms of binge ethanol abuse that might suggest new therapeutic approaches to counter neurodegeneration and dementia.

Small RNA interference-mediated gene silencing of TREK-1 potassium channel in cultured astrocytes

This study was aimed to examine the effect of TREK-1 silencing on the function of astrocytes. Three 21-nucleotide small interfering RNA (siRNA) duplexes (siT1, siT2, siT3) targeting TREK-1 were constructed. Cy3-labeled dsRNA oligmers were used to determine the transfection efficiency in cultured astrocytes. TREK-1-specific siRNA duplexes (siT1, siT2, siT3) at the optimal concentration were transfected into cultured astrocytes, and the most efficient siRNA was identified by the method of immunocytochemical staining and Western blotting. The proliferation of astrocytes tranfected with TREK-1-targeting siRNA under hypoxia condition was measured by fluorescence-activated cell sorting (FACS). The results showed that TREK-1 was expressed in cultured astrocytes. The dsRNA oligmers targeting TREK-1 could be transfected efficiently in cultured astrocytes and down-regulate the expression of TREK-1 in astrocytes. Moreover, the down-regulation of TREK-1 in astrocytes contributed to the proliferation of astrocytes under hypoxia condition as determined by cell cycle analysis. It was concluded that siRNA is a powerful technique that can be used to knockdown the expression of TREK-1 in astrocytes, which helps further investigate the function of TREK-1 channel in astrocytes under physicological and pathological condition.

Neuroimmune mechanisms in fetal alcohol spectrum disorder

Fetal alcohol spectrum disorder (FASD) is a major health concern worldwide and results from maternal consumption of alcohol during pregnancy. It produces tremendous individual, social, and economic losses. This review will first summarize the structural, functional, and behavior changes seen in FASD. The development of the neuroimmune system will be then be described with particular emphasis on the role of microglial cells in the normal regulation of homeostatic function in the central nervous system (CNS) including synaptic transmission. The impact of alcohol on the neuroimmune system in the developing CNS will be discussed in the context of several key immune molecules and signaling pathways involved in neuroimmune mechanisms that contribute to FASD. This review concludes with a summary of the development of early therapeutic approaches utilizing immunosuppressive drugs to target alcohol-induced pathologies. The significant role played by neuroimmune mechanisms in alcohol addiction and pathology provides a focus for future research aimed at understanding and treating the consequences of FASD.

Temporal changes in innate immune signals in a rat model of alcohol withdrawal in emotional and cardiorespiratory homeostatic nuclei

Background

Chronic alcohol use changes the brain’s inflammatory state. However, there is little work examining the progression of the cytokine response during alcohol withdrawal, a period of profound autonomic and emotional upset. This study examines the inflammatory response in the central nucleus of the amygdala (CeA) and dorsal vagal complex (DVC), brain regions neuroanatomically associated with affective and cardiorespiratory regulation in an in vivo rat model of withdrawal following a single chronic exposure.

Methods

For qRT-PCR studies, we measured the expression of TNF-α, NOS-2, Ccl2 (MCP-1), MHC II invariant chain CD74, and the TNF receptor Tnfrsf1a in CeA and DVC samples from adult male rats exposed to a liquid alcohol diet for thirty-five days and in similarly treated animals at four hours and forty-eight hours following alcohol withdrawal. ANOVA was used to identify statistically significant treatment effects. Immunohistochemistry (IHC) and confocal microscopy were performed in a second set of animals during chronic alcohol exposure and subsequent 48-hour withdrawal.

Results

Following a chronic alcohol exposure, withdrawal resulted in a statistically significant increase in the expression of mRNAs specific for innate immune markers Ccl2, TNF-α, NOS-2, Tnfrsf1a, and CD74. This response was present in both the CeA and DVC and most prominent at 48 hours. Confocal IHC of samples taken 48 hours into withdrawal demonstrate the presence of TNF-α staining surrounding cells expressing the neural marker NeuN and endothelial cells colabeled with ICAM-1 (CD54) and RECA-1, markers associated with an inflammatory response. Again, findings were consistent in both brain regions.

Conclusions

This study demonstrates the rapid induction of Ccl2, TNF-α, NOS-2, Tnfrsf1a and CD74 expression during alcohol withdrawal in both the CeA and DVC. IHC dual labeling showed an increase in TNF-α surrounding neurons and ICAM-1 on vascular endothelial cells 48 hours into withdrawal, confirming the inflammatory response at the protein level. These findings suggest that an abrupt cessation of alcohol intake leads to an acute central nervous system (CNS) inflammatory response in these regions that regulate autonomic and emotional state.

Implications of central immune signaling caused by drugs of abuse: mechanisms, mediators and new therapeutic approaches for prediction and treatment of drug dependence

In the past two decades a trickle of manuscripts examining the non-neuronal central nervous system immune consequences of the drugs of abuse has now swollen to a significant body of work. Initially, these studies reported associative evidence of central nervous system proinflammation resulting from exposure to the drugs of abuse demonstrating key implications for neurotoxicity and disease progression associated with, for example, HIV infection. However, more recently this drug-induced activation of central immune signaling is now understood to contribute substantially to the pharmacodynamic actions of the drugs of abuse, by enhancing the engagement of classical mesolimbic dopamine reward pathways and withdrawal centers. This review will highlight the key in vivo animal, human, biological and molecular evidence of these central immune signaling actions of opioids, alcohol, cocaine, methamphetamine, and 3,4-methylenedioxymethamphetamine (MDMA). Excitingly, this new appreciation of central immune signaling activity of drugs of abuse provides novel therapeutic interventions and opportunities to identify 'at risk' individuals through the use of immunogenetics. Discussion will also cover the evidence of modulation of this signaling by existing clinical and pre-clinical drug candidates, and novel pharmacological targets. Finally, following examination of the breadth of central immune signaling actions of the drugs of abuse highlighted here, the current known common immune signaling components will be outlined and their impact on established addiction neurocircuitry discussed, thereby synthesizing a common neuroimmune hypothesis of addiction.

Stabilization of superoxide dismutase by acetyl-l-carnitine in human brain endothelium during alcohol exposure: novel protective approach

Oxidative damage of the endothelium disrupts the integrity of the blood-brain barrier (BBB). We have shown before that alcohol exposure increases the levels of reactive oxygen species (ROS; superoxide and hydroxyl radical) and nitric oxide (NO) in brain endothelial cells by activating NADPH oxidase and inducible nitric oxide synthase. We hypothesize that impairment of antioxidant systems, such as a reduction in catalase and superoxide dismutase (SOD) activity, by ethanol exposure may elevate the levels of ROS/NO in endothelium, resulting in BBB damage. This study examines whether stabilization of antioxidant enzyme activity results in suppression of ROS levels by anti-inflammatory agents. To address this idea, we determined the effects of ethanol on the kinetic profile of SOD and catalase activity and ROS/NO generation in primary human brain endothelial cells (hBECs). We observed an enhanced production of ROS and NO levels due to the metabolism of ethanol in hBECs. Similar increases were found after exposure of hBECs to acetaldehyde, the major metabolite of ethanol. Ethanol simultaneously augmented ROS generation and the activity of antioxidative enzymes. SOD activity was increased for a much longer period of time than catalase activity. A decline in SOD activity and protein levels preceded elevation of oxidant levels. SOD stabilization by the antioxidant and mitochondria-protecting agent acetyl-L-carnitine (ALC) and the anti-inflammatory agent rosiglitazone suppressed ROS levels, with a marginal increase in NO levels. Mitochondrial membrane protein damage and decreased membrane potential after ethanol exposure indicated mitochondrial injury. These changes were prevented by ALC. Our findings suggest the counteracting mechanisms of oxidants and antioxidants during alcohol-induced oxidative stress at the BBB. The presence of enzymatic stabilizers favors the ROS-neutralizing antioxidant redox of the BBB, suggesting an underlying protective mechanism of NO for brain vascular tone and vasodilation.

Molecular and behavioral aspects of the actions of alcohol on the adult and developing brain

The brain is one of the major target organs of alcohol actions. Alcohol abuse can lead to alterations in brain structure and functions and, in some cases, to neurodegeneration. Cognitive deficits and alcohol dependence are highly damaging consequences of alcohol abuse. Clinical and experimental studies have demonstrated that the developing brain is particularly vulnerable to alcohol, and that drinking during gestation can lead to a range of physical, learning and behavioral defects (fetal alcohol spectrum disorders), with the most dramatic presentation corresponding to fetal alcohol syndrome. Recent findings also indicate that adolescence is a stage of brain maturation and that heavy drinking at this stage can have a negative impact on brain structure and functions causing important short- and long-term cognitive and behavioral consequences. The effects of alcohol on the brain are not uniform; some brain areas or cell populations are more vulnerable than others. The prefrontal cortex, the hippocampus, the cerebellum, the white matter and glial cells are particularly susceptible to the effects of ethanol. The molecular actions of alcohol on the brain are complex and involve numerous mechanisms and signaling pathways. Some of the mechanisms involved are common for the adult brain and for the developing brain, while others depend on the developmental stage. During brain ontogeny, alcohol causes irreversible alterations to the brain structure. It also impairs several molecular, neurochemical and cellular events taking place during normal brain development, including alterations in both gene expression regulation and the molecules involved in cell-cell interactions, interference with the mitogenic and growth factor response, enhancement of free radical formation and derangements of glial cell functions. However, in both adult and adolescent brains, alcohol damages specific brain areas through mechanisms involving excitotoxicity, free radical formation and neuroinflammatory damage resulting from activation of the innate immune system mediated by TLR4 receptors. Alcohol also acts on specific membrane proteins, such as neurotransmitter receptors (e.g. NMDA, GABA-A), ion channels (e.g. L-type Ca²⁺ channels, GIRKs), and signaling pathways (e.g. PKA and PKC signaling). These effects might underlie the wide variety of behavioral effects induced by ethanol drinking. The neuroadaptive changes affecting neurotransmission systems which are more sensitive to the acute effects of alcohol occur after long-term alcohol consumption. Alcohol-induced maladaptations in the dopaminergic mesolimbic system, abnormal plastic changes in the reward-related brain areas and genetic and epigenetic factors may all contribute to alcohol reinforcement and alcohol addiction. This manuscript reviews the mechanisms by which ethanol impacts the adult and the developing brain, and causes both neural impairments and cognitive and behavioral dysfunctions. The identification and the understanding of the cellular and molecular mechanisms involved in ethanol toxicity might contribute to the development of treatments and/or therapeutic agents that could reduce or eliminate the deleterious effects of alcohol on the brain.

The inflammatory footprints of alcohol-induced oxidative damage in neurovascular components

Microvessels, the main components of the blood-brain barrier (BBB) are vulnerable to oxidative damage during alcohol-induced stress. Alcohol produces oxidative damage within the vessels and in the brain. Using our animal model of catheter implant into the common carotid artery (CCA), we trace the footprints of alcohol-induced oxidative damage and inflammatory process at the BBB and into the brain. The uniqueness of the finding is that ethanol causes oxidative damage in all neurovascular components by activating NADPH oxidase and inducible nitric oxide synthase in the brain. It is not the oxidants but the ethanol that traverses through the BBB because we found that the highly reactive peroxynitrite does not cross the BBB. Thus, oxidative damage is caused at the site of oxidant production in the microvessels and in the brain. Our data indicate that acetaldehyde (the primary metabolite of ethanol) is the inducer/activator of these enzymes that generate oxidants in brain neurovascular cells. Evidence for alcohol-induced BBB damage is indicated by the alterations of the tight junction protein occludin in intact microvessels. Importantly, we demonstrate that the site of BBB oxidative damage is also the site of immune cells aggregation in the microvessels, which paves the path for inflammatory footprints. These findings reveal the underlying mechanisms that ethanol-elicited BBB oxidative damage initiates the brain vascular inflammatory process, which ultimately leads to neuroinflammation.

HIV-1 infection and alcohol abuse: neurocognitive impairment, mechanisms of neurodegeneration and therapeutic interventions

Clinical studies indicate that alcohol dependence has an additive effect on cognitive deficits associated with HIV-1 infection. Findings in humans and animal models suggest that alcohol, similar to HIV-1, induces inflammatory processes in the brain leading to neurodegeneration. The causes of HIV-1-associated neurotoxicity are comparable to those mediating alcohol-induced neuronal injury. This review aims to present the mechanisms of the combined effects of HIV-1 and alcohol abuse in the brain and to discuss neuroprotective therapies. Oxidative stress, overproduction of pro-inflammatory factors, impairment of blood-brain barrier and glutamate associated neurotoxicity appear to play important roles in alcohol driven neurodegeneration. Diminution of neuroinflammation constitutes a logical approach for prevention of HIV-1 and alcohol mediated neurodegeneration. Agonists of cannabinoid receptor 2 (CB₂) possess potent anti-inflammatory and neuroprotective properties. We address multifaceted beneficial effects of CB₂ activation in the setting of HIV-1 brain infection and alcohol abuse.

Methamphetamine inhibits the glucose uptake by human neurons and astrocytes: stabilization by acetyl-L-carnitine

Methamphetamine (METH), an addictive psycho-stimulant drug exerts euphoric effects on users and abusers. It is also known to cause cognitive impairment and neurotoxicity. Here, we hypothesized that METH exposure impairs the glucose uptake and metabolism in human neurons and astrocytes. Deprivation of glucose is expected to cause neurotoxicity and neuronal degeneration due to depletion of energy. We found that METH exposure inhibited the glucose uptake by neurons and astrocytes, in which neurons were more sensitive to METH than astrocytes in primary culture. Adaptability of these cells to fatty acid oxidation as an alternative source of energy during glucose limitation appeared to regulate this differential sensitivity. Decrease in neuronal glucose uptake by METH was associated with reduction of glucose transporter protein-3 (GLUT3). Surprisingly, METH exposure showed biphasic effects on astrocytic glucose uptake, in which 20 µM increased the uptake while 200 µM inhibited glucose uptake. Dual effects of METH on glucose uptake were paralleled to changes in the expression of astrocytic glucose transporter protein-1 (GLUT1). The adaptive nature of astrocyte to mitochondrial β-oxidation of fatty acid appeared to contribute the survival of astrocytes during METH-induced glucose deprivation. This differential adaptive nature of neurons and astrocytes also governed the differential sensitivity to the toxicity of METH in these brain cells. The effect of acetyl-L-carnitine for enhanced production of ATP from fatty oxidation in glucose-free culture condition validated the adaptive nature of neurons and astrocytes. These findings suggest that deprivation of glucose-derived energy may contribute to neurotoxicity of METH abusers.

Effect of alcohol on drug efflux protein and drug metabolic enzymes in U937 macrophages

BACKGROUND

ATP-binding cassette (ABC) proteins and cytochrome P450 (CYP) enzymes regulate the bioavailability of HIV-1 antiretroviral therapeutic drugs, non-nucleoside reverse transcriptase inhibitors (NNRTIs), and protease inhibitors (PIs). They are also involved in regulating, and responding to, oxidative stress in various tissues and organs including liver. This study is designed to assess the effect of alcohol on the ABCC1 and CYP enzymes involved in the metabolism of NNRTIs and PIs (CYP2B6, CYP2D6, and CYP3A4) and oxidative stress (CYP1A1, CYP2A6, and CYP2E1) in U937 macrophages. The U937 cell line has been utilized as an in vitro model of human macrophages.

METHODS

The expression levels of the ABCC1 and CYP enzymes in U937 macrophages were characterized in terms of mRNA quantification, protein analysis, and assays for functional activity. In addition, oxidative stress was monitored by measuring the activities of oxidative stress marker enzymes and production of reactive oxygen species (ROS).

RESULTS

The order of mRNA expression in U937 macrophages was ABCC1 ∼ CYP2A6 > CYP3A4 ∼ CYP2E1 ∼ CYP1A1 > CYP2D6 > CYP2B6. Alcohol (100 mM) increased the mRNA levels of ABCC1 and CYP2A6 (200%), CYP2B6 and CYP3A4 (150%), and CYP2E1 (400%) compared with the control. Alcohol caused significant upregulation of ABCC1, CYP2A6, CYP2E1, and CYP3A4 proteins (50 to 85%) and showed >50% increase in the specific activity of CYP2A6 and CYP3A4 in U937 macrophages. Furthermore, alcohol increased the production of ROS and significantly enhanced the activity of oxidative stress marker enzymes, superoxide dismutase, and catalase in U937 macrophages.

CONCLUSIONS

Our study showed that alcohol causes increases in the genetic and functional expressions of ABCC1 and CYP enzymes in U937 macrophages. This study has clinical implications in alcoholic HIV-1 individuals, because alcohol consumption is reported to reduce the therapeutic efficacy of NNRTIs and PIs and increases oxidative stress.

Ethanol impairs glucose uptake by human astrocytes and neurons: protective effects of acetyl-L-carnitine

Alcohol consumption causes neurocognitive deficits, neuronal injury, and neurodegeneration. At the cellular level, alcohol abuse causes oxidative damage to mitochondria and cellular proteins and interlink with the progression of neuroinflammation and neurological disorders. We previously reported that alcohol inhibits glucose transport across the blood-brain barrier (BBB), leading to BBB dysfunction and neurodegeneration. In this study, we hypothesized that ethanol (EtOH)-mediated disruption in glucose uptake would deprive energy for human astrocytes and neurons inducing neurotoxicity and neuronal degeneration. EtOH may also have a direct effect on glucose uptake in neurons and astrocytes, which has not been previously described. Our results indicate that ethanol exposure decreases the uptake of D-(2-3H)-glucose by human astrocytes and neurons. Inhibition of glucose uptake correlates with a reduction in glucose transporter protein expression (GLUT1 in astrocytes and GLUT3 in neurons). Acetyl-L-carnitine (ALC), a neuroprotective agent, suppresses the effects of alcohol on glucose uptake and GLUT levels, thus reducing neurotoxicity and neuronal degeneration. These findings suggest that deprivation of glucose in brain cells contributes to neurotoxicity in alcohol abusers, and highlights ALC as a potential therapeutic agent to prevent the deleterious health conditions caused by alcohol abuse.