ABSTRACT
BACKGROUND: Chronic alcohol exposure induces cognitive impairment and NLRP3 inflammasome activation in the mPFC (medial prefrontal cortex). Mitophagy plays a crucial role in neuroinflammation, and dysregulated mitophagy is associated with behavioral deficits. However, the potential relationships among mitophagy, inflammation, and cognitive impairment in the context of alcohol exposure have not yet been studied. NRF2 promotes the process of mitophagy, while alcohol inhibits NRF2 expression. Whether NRF2 activation can ameliorate defective mitophagy and neuroinflammation in the presence of alcohol remains unknown. METHODS: BV2 cells and primary microglia were treated with alcohol. C57BL/6J mice were repeatedly administered alcohol intragastrically. BNIP3-siRNA, PINK1-siRNA, CCCP and bafilomycin A1 were used to regulate mitophagy in BV2 cells. RTA-408 acted as an NRF2 activator. Mitochondrial dysfunction, mitophagy and NLRP3 inflammasome activation were assayed. Behavioral tests were used to assess cognition. RESULTS: Chronic alcohol exposure impaired the initiation of both receptor-mediated mitophagy and PINK1-mediated mitophagy in the mPFC and in vitro microglial cells. Silencing BNIP3 or PINK1 induced mitochondrial dysfunction and aggravated alcohol-induced NLRP3 inflammasome activation in BV2 cells. In addition, alcohol exposure inhibited the NRF2 expression both in vivo and in vitro. NRF2 activation by RTA-408 ameliorated NLRP3 inflammasome activation and mitophagy downregulation in microglia, ultimately improving cognitive impairment in the presence of alcohol. CONCLUSION: Chronic alcohol exposure-induced impaired mitophagy initiation contributed to NLRP3 inflammasome activation and cognitive deficits, which could be alleviated by NRF2 activation via RTA-408.
Subject(s)
Cognitive Dysfunction , Inflammasomes , Membrane Proteins , Microglia , Mitophagy , NF-E2-Related Factor 2 , NLR Family, Pyrin Domain-Containing 3 Protein , Animals , Mitophagy/drug effects , NLR Family, Pyrin Domain-Containing 3 Protein/metabolism , NLR Family, Pyrin Domain-Containing 3 Protein/genetics , Mice , NF-E2-Related Factor 2/metabolism , NF-E2-Related Factor 2/genetics , Inflammasomes/metabolism , Inflammasomes/genetics , Cognitive Dysfunction/drug therapy , Cognitive Dysfunction/metabolism , Cognitive Dysfunction/genetics , Cognitive Dysfunction/chemically induced , Cognitive Dysfunction/pathology , Microglia/metabolism , Microglia/drug effects , Microglia/pathology , Membrane Proteins/genetics , Membrane Proteins/metabolism , Male , Mice, Inbred C57BL , Mitochondria/metabolism , Mitochondria/drug effects , Mitochondria/pathology , Protein Kinases/metabolism , Protein Kinases/genetics , Prefrontal Cortex/metabolism , Prefrontal Cortex/pathology , Prefrontal Cortex/drug effects , Mitochondrial Proteins/genetics , Mitochondrial Proteins/metabolism , Ethanol/toxicity , Ethanol/adverse effectsABSTRACT
AIMS: Chronic alcohol exposure leads to persistent neurological disorders, which are mainly attributed to neuroinflammation and apoptosis. Stimulator of IFN genes (STING) is essential in the cytosolic DNA sensing pathway and is involved in inflammation and cellular death processes. This study was to examine the expression pattern and biological functions of STING signaling in alcohol use disorder (AUD). METHODS: Cell-free DNA was extracted from human and mouse plasma. C57BL/6J mice were given alcohol by gavage for 28 days, and behavior tests were used to determine their mood and cognition. Cultured cells were treated with ethanol for 24 hours. The STING agonist DMXAA, STING inhibitor C-176, and STING-siRNA were used to intervene the STING. qPCR, western blot, and immunofluorescence staining were used to assess STING signaling, inflammation, and apoptosis. RESULTS: Circulating cell-free mitochondrial DNA (mtDNA) was increased in individuals with AUD and mice chronically exposed to alcohol. Upregulation of STING signaling under alcohol exposure led to inflammatory responses in BV2 cells and mitochondrial apoptosis in PC12 cells. DMXAA exacerbated alcohol-induced cognitive impairment and increased the activation of microglia, neuroinflammation, and apoptosis in the medial prefrontal cortex (mPFC), while C-176 exerted neuroprotection. CONCLUSION: Activation of STING signaling played an essential role in alcohol-induced inflammation and mitochondrial apoptosis in the mPFC. This study identifies STING as a promising therapeutic target for AUD.
