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Many disorders of the central nervous system (CNS), including alcohol use disorder (AUD), are associated with induction of proinflammatory neuroimmune signalling and neurodegeneration. In previous studies, we found increased expression of Toll‐like receptors (TLRs), activated NF‐κB p65 (RELA), and other proinflammatory signalling molecules. Proinflammatory NADPH oxidases generate reactive oxygen species, which are linked to neurodegeneration. We tested the hypothesis that AUD increased RELA activation increases NADPH oxidase‐oxidative stress and endoplasmic reticulum (ER) stress cell death cascades in association with neuronal cell death in the human orbitofrontal cortex (OFC). In the AUD OFC, we report mRNA induction of several NADPH oxidases, the dual oxidase DUOX2, and the oxidative stress lipid peroxidation marker 4‐HNE and the DNA oxidation marker 8‐OHdG that correlate with RELA, a marker of proinflammatory NF‐κB activation. This was accompanied by increased expression of the ER stress‐associated regulator protein glucose‐regulated protein 78 (GRP78), transmembrane sensors activating transcription factor 6 (ATF6), protein kinase RNA‐like endoplasmic reticulum kinase (PERK), and inositol‐requiring kinase/endonuclease 1 (pIRE1), and the pro‐apoptotic transcription factor C/EBP homologous protein (CHOP). Expression of NADPH oxidase‐oxidative stress markers correlate with ER stress‐associated molecules. Induction of oxidative stress and ER stress signalling pathways correlate with expression of cell death‐associated caspases and neuronal cell loss. These data support the hypothesis that proinflammatory RELA‐mediated induction of NADPH oxidase‐oxidative stress and ER stress‐associated signalling cascades is associated with neuronal cell death in the post‐mortem human OFC of individuals with AUD. [ABSTRACT FROM AUTHOR]

Background: Many brain disorders, including alcohol use disorder (AUD), are associated with induction of multiple proinflammatory genes. One aspect of proinflammatory signaling is progressive increases in expression across cells and induction of other innate immune genes. High‐mobility group box 1 (HMGB1) heteromers contribute to amplification by potentiating multiple proinflammatory responses, including Toll‐like receptors (TLRs). TLR signaling recruits coupling proteins linked to nuclear transcription factors that induce proinflammatory cytokines and chemokines and their respective receptors. We tested the hypothesis that AUD induction of TLR expression increases levels of proinflammatory genes and cellular signaling cascades in association with neurodegeneration in the orbitofrontal cortex (OFC). Methods: Postmortem human OFC tissue samples (n = 10) from males diagnosed with AUD were compared to age‐matched moderate drinking controls (CON). Neuroimmune signaling molecules were assessed using immunohistochemistry for protein and reverse transcription polymerase chain reaction for messenger RNA (mRNA). Results: In the AUD OFC, we report induction of the endogenous TLR agonist HMGB1 as well as all TLRs assessed (i.e., TLR2‐TLR9) except TLR1. This was accompanied by increased expression of the TLR adaptor protein myeloid differentiation primary response 88 (MyD88), activation of the proinflammatory nuclear transcription factor nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NFκB), and downstream induction of proinflammatory cytokines, chemokines, and their corresponding receptors. Several of these proinflammatory signaling markers are expressed in glia and neurons. The induction of HMGB1‐TLR‐MyD88‐NFκB proinflammatory signaling pathways correlates with neurodegeneration (i.e., Fluoro‐Jade B), lifetime alcohol consumption, and age of drinking onset. Conclusion: These data implicate the induction of HMGB1‐TLR‐MyD88‐NFκB cascades through coordinated glial and neuronal signaling as contributors to the neurodegeneration seen in the postmortem human OFC of individuals with AUD. [ABSTRACT FROM AUTHOR]

Background: Toll‐like receptor 7 (TLR7) is an endosomal TLR that is activated by single‐stranded RNA, including endogenous microRNAs (e.g., let‐7b). Increased hepatic expression of TLRs, microRNAs, and inflammatory mediators is linked to ethanol (EtOH) exposure and to alcoholic liver disease (ALD). ALD invovles chronic hepatic inflammation that can progress to alcoholic hepatitis (AH), a particularly severe form of ALD. This study aimed to investigate TLR7 expression in patients with different liver disease phenotypes and in mouse liver following alcohol exposure. Methods: Hepatic mRNA expression was determined by RNA sequencing of liver tissue from patients with liver disease or normal liver tissue. Mice were exposed to subchronic EtOH followed by administration of the TLR7 agonist imiquimod. Primary human hepatocytes were exposed to EtOH or imiquimod in vitro. Results: RNAseq analysis revealed that hepatic expression of TLR7 and let‐7b microRNA, an endogenous TLR7 ligand, was significantly increased in AH patients. Hepatic expression of TLR7 and let‐7b positively correlated with hepatic IL‐8 mRNA expression. In mice, EtOH increased hepatic TLR7 mRNA expression and enhanced imiquimod‐induced expression of the pro‐inflammatory mediators TNFα, MCP‐1, and iNOS. In vitro, EtOH significantly increased hepatocyte TLR7 mRNA and the TLR7 agonist, imiquimod, induced hepatocyte expression of TNFα and IL‐8 mRNA. EtOH also increased the release of let‐7b in microvesicles from hepatocytes, suggesting that EtOH can increase the expression of both the receptor and its endogenous ligand. Conclusions: These studies suggest that increased TLR7 signaling caused by increased expression of TLR7 and its endogenous ligand let‐7b may contribute to the enhanced inflammatory response associated with AH. Activation of the RNA receptor, Toll‐like Receptor 7, by endogenous microRNA let‐7 contributes to alcoholic hepatitis (AH). Steatohepatitis (fatty liver) involves chronic mild proinflammatory signaling through Toll‐like receptor 4 by LPS‐endotoxin. Some patients spontaneously progress to acute alcoholic hepatitis, a sometimes fatal, serious systemic immune response syndrome. This study finds Toll‐like receptor 7, an RNA receptor, responds to endogenous let‐7 microRNAs, uniquely amplify key proinflammatory genes in patients with AH. [ABSTRACT FROM AUTHOR]

Background Wernicke's encephalopathy- Korsakoff syndrome ( WE- KS) is common in alcoholics, caused by thiamine deficiency ( TD; vitamin B1) and associated with lesions to the thalamus ( THAL). Although TD alone can cause WE, the high incidence in alcoholism suggests that TD and ethanol (EtOH) interact. Methods Mice in control, TD, or EtOH groups alone or combined were studied after 5 or 10 days of treatment. THAL and entorhinal cortex ( ENT) histochemistry and mRNA were assessed. Results Combined EtOH- TD treatment for 5 days (Et OH- TD5) showed activated microglia, proinflammatory gene induction and THAL neurodegeneration that was greater than that found with TD alone ( TD5), whereas 10 days resulted in marked THAL degeneration and microglial-neuroimmune activation in both groups. In contrast, 10 days of TD did not cause ENT degeneration. Interestingly, in ENT, TD10 activated microglia and astrocytes more than Et OH- TD10. In THAL, multiple astrocytic markers were lost consistent with glial cell loss. TD blocks glucose metabolism more than acetate. Acetate derived from hepatic EtOH metabolism is transported by monocarboxylic acid transporters ( MCT) into both neurons and astrocytes that use acetyl-CoA synthetase (AcCo AS) to generate cellular energy from acetate. MCT and AcCo AS expression in THAL is lower than ENT prompting the hypothesis that focal THAL degeneration is related to insufficient MCT and AcCo AS in THAL. To test this hypothesis, we administered glycerin triacetate ( GTA) to increase blood acetate and found it protected the THAL from TD-induced degeneration. Conclusions Our findings suggest that Et OH potentiates TD-induced THAL degeneration through neuroimmune gene induction. The findings support the hypothesis that TD deficiency inhibits global glucose metabolism and that a reduced ability to process acetate for cellular energy results in THAL focal degeneration in alcoholics contributing to the high incidence of Wernicke-Korsakoff syndrome in alcoholism. [ABSTRACT FROM AUTHOR]

Background: Binge ethanol administration causes corticolimbic brain damage that models alcoholic neurodegeneration. The mechanism of binge ethanol-induced degeneration is unknown, but is not simple glutamate– N-methyl-d-aspartate (NMDA) excitotoxicity. To test the hypothesis that oxidative stress and inflammation are mechanisms of binge ethanol-induced brain damage, we administered 4 antioxidants, e.g., butylated hydroxytoluene (BHT), ebselen (Eb), vitamin E (VE), and blueberry (BB) extract, during binge ethanol treatment and assessed various measures of neurodegeneration. Methods: Adult Sprague–Dawley rats were treated with intragastric ethanol 3 times per day (8–12 g/kg/d) alone or in combination with antioxidants or isocaloric diet for 4 days. Animals were killed, and brains were perfused and extracted for histochemical silver stain determination of brain damage, markers of neurogenesis, or other immunohistochemistry. Some animals were used for determination of nuclear factor κ B (NF- κB)–DNA binding by electrophoretic mobility shift assay (EMSA) or for reverse transcription–polymerase chain reaction (RT-PCR) of cyclooxygenase 2 (COX2). Results: Binge ethanol induced corticolimbic brain damage and reduced neurogenesis. Treatment with BHT reversed binge induced brain damage and blocked ethanol inhibition of neurogenesis in all regions studied. Interestingly, the other antioxidants studied, e.g., Eb, VE, and BB, did not protect against binge-induced brain damage. Binge ethanol treatment also caused microglia activation, increased NF- κB–DNA binding and COX2 expression. Butylated hydroxytoluene reduced binge-induced NF- κB–DNA binding and COX2 expression. Conclusions: Binge-induced brain damage and activation of NF- κB–DNA binding are blocked by BHT. These studies support a neuroinflammatory mechanism of binge ethanol-induced brain damage. [ABSTRACT FROM AUTHOR]

Here, we report that leucine enkephalin (LE) is neuroprotective to dopaminergic (DA) neurons at femtomolar concentrations through anti inflammatory properties. Mesencephalic neuron-glia cultures pretreated with femtomolar concentrations of LE (10-15-10-13M) protected DA neurons from lipopolysaccharide (LPS)-induced DA neurotoxicity, as determined by DA uptake assay and tyrosine hydroxy lase (TH) immunocytochemistry (ICC). However, des-tyrosine leucine enkephalin (DTLE), an LE analogue that is missing the tyrosine residue required for binding to the kappa opioid receptor, was also neuroprotective (10-15-10-13M), as determined by DA uptake assay and TH ICC. Both LE and DTLE (10-15-10-13M) reduced LPS-induced super- oxide production from microglia-enriched cultures. Further, both LE and DTLE (10-14-10-13M) reduced the LPS-induced tumor necrosis factor-alpha (TNFa) mRNA and TNFa protein from PHOX!1! microglia, as determined by quanti- tative real-time RT-PCR and ELISA analysis in mesencephalic neuron-glia cultures, respectively. However, both peptides failed to inhibit TNFα expression in PHOX! cultures, which are unable to produce extracellular superoxide in response to LPS. Additionally, LE and DTLE (10-14, 10-13 M) failed to show any neuroprotection against LPS in PHOX! cultures. Together, these data indicate that LE and DTLE are neuroprotective at femtomolar concentrations through the inhibition of oxidative insult associated with microglial NADPH oxidase and the attenuation of the ROS-mediated amplification of TNFa gene expression in microglia. [ABSTRACT FROM AUTHOR]

Background: Binge ethanol administration causes corticolimbic brain damage that models alcoholic neurodegeneration. The mechanism of binge ethanol-induced degeneration is unknown, but is not simple glutamate-N-methyl-D-aspartate (NMDA) excitotoxicity. To test the hypothesis that oxidative stress and inflammation are mechanisms of binge ethanol-induced brain damage, we administered 4 antioxidants, e.g., butylated hydroxytoluene (BHT), ebselen (Eb), vitamin E (VE), and blueberry (BB) extract, during binge ethanol treatment and assessed various measures of neurodegeneration., Methods: Adult Sprague-Dawley rats were treated with intragastric ethanol 3 times per day (8-12 g/kg/d) alone or in combination with antioxidants or isocaloric diet for 4 days. Animals were killed, and brains were perfused and extracted for histochemical silver stain determination of brain damage, markers of neurogenesis, or other immunohistochemistry. Some animals were used for determination of nuclear factor kappa B (NF-kappaB)-DNA binding by electrophoretic mobility shift assay (EMSA) or for reverse transcription-polymerase chain reaction (RT-PCR) of cyclooxygenase 2 (COX2)., Results: Binge ethanol induced corticolimbic brain damage and reduced neurogenesis. Treatment with BHT reversed binge induced brain damage and blocked ethanol inhibition of neurogenesis in all regions studied. Interestingly, the other antioxidants studied, e.g., Eb, VE, and BB, did not protect against binge-induced brain damage. Binge ethanol treatment also caused microglia activation, increased NF-kappaB-DNA binding and COX2 expression. Butylated hydroxytoluene reduced binge-induced NF-kappaB-DNA binding and COX2 expression., Conclusions: Binge-induced brain damage and activation of NF-kappaB-DNA binding are blocked by BHT. These studies support a neuroinflammatory mechanism of binge ethanol-induced brain damage.