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Hwang, S. Oxidative Stress in Alcoholic Liver Disease. Encyclopedia. Available online: https://encyclopedia.pub/entry/18486 (accessed on 28 July 2024).
Hwang S. Oxidative Stress in Alcoholic Liver Disease. Encyclopedia. Available at: https://encyclopedia.pub/entry/18486. Accessed July 28, 2024.
Hwang, Seonghwan. "Oxidative Stress in Alcoholic Liver Disease" Encyclopedia, https://encyclopedia.pub/entry/18486 (accessed July 28, 2024).
Hwang, S. (2022, January 19). Oxidative Stress in Alcoholic Liver Disease. In Encyclopedia. https://encyclopedia.pub/entry/18486
Hwang, Seonghwan. "Oxidative Stress in Alcoholic Liver Disease." Encyclopedia. Web. 19 January, 2022.
Oxidative Stress in Alcoholic Liver Disease
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This entry is adapted from the peer-reviewed paper 10.3390/ijms23020774

Alcoholic liver disease (ALD) is characterized by the injury, inflammation, and scarring in the liver owing to excessive alcohol consumption. Currently, ALD is a leading cause for liver transplantation. Therefore, extensive studies (in vitro, in experimental ALD models and in humans) are needed to elucidate pathological features and pathogenic mechanisms underlying ALD. Notably, oxidative changes in the liver have been recognized as a signature trait of ALD. Progression of ALD is linked to the generation of highly reactive free radicals by reactions involving ethanol and its metabolites. Furthermore, hepatic oxidative stress promotes tissue injury and, in turn, stimulates inflammatory responses in the liver, forming a pathological loop that promotes the progression of ALD. Accordingly, accumulating further knowledge on the relationship between oxidative stress and inflammation may help establish a viable therapeutic approach for treating ALD. 

alcoholic liver disease oxidative stress inflammatory liver injury fatty liver alcoholic steatohepatitis cirrhosis

1. Introduction

Excessive and chronic alcohol intake can cause numerous problems affecting various physiological systems, including the immune, nervous, cardiovascular, and digestive systems [1][2][3][4][5]. The hepatic manifestation of heavy alcohol consumption is referred to as alcoholic liver disease (ALD), which encompasses a wide spectrum of disorders including fatty liver, alcoholic steatohepatitis (ASH), alcoholic hepatitis (AH), cirrhosis, and hepatocellular carcinoma [6][7][8][9][10]. Fatty liver is relatively benign and represents the initial stage in the ALD spectrum, marked by triglyceride accumulation in the liver. In some individuals, alcoholic fatty liver progresses to ASH, which is characterized by the presence of hepatocyte injury, hepatocyte ballooning, and inflammation [11]. Chronic injury, inflammation, and activation of the liver regeneration machinery, which are features of ASH, may result in the replacement of the hepatic parenchyma with fibrotic tissues, eventually causing liver failure and cirrhosis [12]. Apart from the chronic, subclinical nature of ASH progression, acute and overt syndromes observed in patients with ALD are referred to as AH, known to present a poor prognosis [13].
ALD has become one of the leading causes of end-stage liver disease, and necessitates liver transplantation, while the contribution of viral infections has gradually waned [14][15]. In the United States, recent studies have reported that approximately 40% of cirrhosis-related deaths can be attributed to ALD, and the three-month mortality of severe AH is approximately 50%, indicating that ALD may be fatal without active therapeutic intervention [16][17]. However, therapeutic options for ALD remain limited.
Molecular mechanisms underlying the principal features of ALD progression, including liver injury, inflammation, and fibrosis, have been extensively investigated as potential therapeutic targets for ALD [18]. Numerous reports have demonstrated that the pathogenesis of ALD is often accompanied by oxidative stress and inflammatory injury [19][20]

2. Oxidative Stress-Related Pathogenic Mechanisms of ALD

ALD pathogenesis involves various processes, including fat accumulation, organelle stress and hepatocyte death, immune cell infiltration and activation, and fibrogenesis stimulated by hepatic stellate cells [19][21][22][23][24]. As stated above, these processes are reportedly stimulated by and/or enhance oxidative stress. Early studies have revealed that ethanol metabolism via alcohol dehydrogenase (ADH) and microsomal cytochrome P450 (CYP) enzymes produces acetaldehyde and reactive oxygen species (ROS) and depletes glutathione levels [25][26][27][28][29][30]. These findings and other reports have highlighted the importance of oxidative stress in the pathogenesis of ALD.
The oxidation of ethanol to acetaldehyde and acetate utilizes NAD+ as a cofactor and produces NADH, thereby reducing the ratio of NAD+ to NADH (NAD+/NADH) [31]. NAD+/NADH is a crucial factor determining metabolic homeostasis in hepatocytes, including fatty acid synthesis, fatty acid oxidation, gluconeogenesis, and glycolysis [32]. In particular, the decrease in NAD+/NADH ratio promotes fat accumulation in the liver by reducing fatty acid oxidation and enhancing fatty acid synthesis [21]. Alcohol intake promotes hepatic fat accumulation via various mechanisms, including elevated expression levels of lipogenic genes (e.g., sterol regulatory element-binding protein [SREBP]-1c and its target genes) [33][34][35] and inhibition of genes involved in fatty acid oxidation (e.g., peroxisome proliferator-activated receptor [PPAR]-α target genes) [30][35][36][37]. Notably, CYP2E1-dependent ROS production was shown to inhibit PPAR-α-mediated fatty acid oxidation genes, such as acyl CoA oxidase [30]. Alcohol-induced fat accumulation may, in turn, cause cellular stress and hepatocyte death, which can also be directly stimulated by ethanol and ethanol-derived metabolites [38]. Alcohol-induced hepatocyte injury and inflammation are closely associated with oxidative stress; thus, this section discusses the detailed involvement of oxidative stress in alcohol-induced hepatocyte injury, as well as the role of immune cells in mediating alcohol-induced inflammatory liver injury (Figure 1). In addition, we summarize the messengers linking oxidative stress and inflammation in ALD pathogenesis. Furthermore, we elaborate on experimental ALD models characterized by profound oxidative stress and inflammation and the consequences of modulating oxidative stress and/or inflammation in ALD models.
Ijms 23 00774 g001 550
Figure 1. Oxidative stress-related pathogenesis of ALD. ROS can be produced by the metabolism of ethanol to acetaldehyde and acetate as well as the related processes that involve the conversion between NAD+/NADP+ and NADH/NADPH. ROS produced via these processes stimulate hepatocyte injury directly or via enhanced fat accumulation. Injured hepatocytes release DAMPs, cytokines, and chemokines, which activate and recruit innate immune cells such as macrophages and neutrophils. Activated macrophages and neutrophils can also produce ROS via NADPH oxidase. Protein and DNA adducts formed by acetaldehyde and ROS may facilitate liver injury, inflammation, and carcinogenesis. ADH, alcohol dehydrogenase; ALD, alcoholic liver disease; ALDH, aldehyde dehydrogenase; DAMP, damage-associated molecular pattern; GSH, glutathione; ROS, reactive oxygen species; TNF-α, tumor necrosis factor-alpha. ↑, increased; ↓, decreased.

2.1. Alcohol-Induced Hepatocyte Injury

Ethanol is metabolized to acetaldehyde in hepatocytes, mainly via an enzymatic reaction catalyzed by ADHs [39]. There are six closely related ADHs: ADH1A, ADH1B, ADH1C, ADH4, ADH5, and ADH6 [40]. Among these, ADH1A, ADH1B, and ADH1C are responsible for the majority of ethanol oxidation in the liver [41]. Acetaldehyde generated by the enzymatic reaction reacts with DNA and proteins, thereby forming adducts that induce hepatocyte injury. The catalytic cycle of ADH is coupled with the conversion of NAD+ to NADH [42]. Aldehyde dehydrogenases (ALDHs) catalyze the conversion of acetaldehyde to acetate using NAD+ as a cofactor, which is also converted to NADH [32]. Re-oxidation of NADH to NAD+ in the mitochondria has been associated with electron leakage from the mitochondrial respiratory chain and subsequent ROS production [43][44][45]. In addition, ethanol inhibited the expression of antioxidant enzymes (e.g., superoxide dismutase 1) and depleted levels of non-enzyme antioxidants (e.g., glutathione), thereby reducing the cellular ability to modulate oxidative stress [25][26][46][47].
Alternatively, CYP2E1 can be induced by chronic alcohol consumption and can oxidize ethanol to acetaldehyde. CYP2E1 produces ROS, such as O2–, H2O2, and ·OH [48][49]. Several animal studies have proposed that CYP2E1 is central to ethanol-induced oxidative stress and hepatic injury. CYP2E1 is mainly located within ER, but also expressed in the mitochondria. The Cederbaum group investigated the role of mitochondrial targeted CYP2E1 in ethanol-induced oxidative stress and mitochondrial damage [50]. Mitochondrial CYP2E1 regulated buthionine sulfoximine-mediated GSH depletion, leading to cell death. Mitochondrial CYP2E1 also contributes to increased levels of ROS and mitochondrial 3-nitrotyrosine and 4-hydroxynonenal protein adducts as well as decreased mitochondrial aconitase activity and mitochondrial membrane potential [50]. Chronic alcohol consumption induced mitochondrial CYP2E1, which plays an important role in ALD. Pharmacological inhibition of CYP2E1 by chlormethiazole reduced liver injury induced by two months of ethanol feeding in rats [51]. Furthermore, chlormethiazole suppressed the development of hepatocellular carcinoma in rats induced by treatment with ethanol and diethylnitrosamine [52]. Lu et al. demonstrated that genetic ablation of the Cyp2e1 gene in mice reduced oxidative stress and prevented ethanol-induced liver injury [30]. In addition, chlormethiazole treatment reduced oxidative stress induced by two-week ethanol feeding in mice [30]. Diesinger et al. reported that novel chimeric inhibitors of CYP2E1 restored the redox balance and rescued liver injury in alcohol-exposed rats [53].
NADPH oxidase (NOX) is an important source of ROS generation which produces superoxide from oxygen using NAD(P)H [54]. NOX1 and NOX4 are abundantly expressed in the liver and hepatocytes [55]. Chronic alcohol consumption increased NOX4 expression in mitochondrial fraction. GKT137831, a NOX4 inhibitor, partially reversed alcohol-induced liver injury, the levels of mitochondrial ROS, mitochondrial DNA, respiratory chain complex IV, and hepatic ATP. Knockdown of NOX4 increased mitochondrial membrane potential and decreased mitochondrial superoxide levels, the number of apoptotic cells, and lipid accumulation [54].Diverse types of cell death, including apoptosis, necroptosis, pyroptosis, and ferroptosis mediate alcohol-induced hepatocyte death [56]. Mitochondria have been highlighted as important locations for ROS-associated cell death [57]. ROS production and oxidative stress caused by ethanol or acetaldehyde reportedly alter the mitochondrial membrane permeability and transition potential [58][59]. This promotes the release of cytochrome c and other pro-apoptotic factors, thereby stimulating the intrinsic pathway of apoptosis [60]. Apoptotic factors released into the cytosol interact with Apaf-1 and caspase-9 to form the apoptosome [61][62][63]. Mitochondrial permeability transition was found to activate caspase-3 in hepatocytes dependent on p38 mitogen-activated protein kinase (MAPK) [64].
Iron overload has been observed in approximately 50% of patients with ALD [65]. Alcohol consumption can decrease the expression of hepcidin through suppression of the transcriptional activity of CCAAT/enhancer binding protein alpha [66]. Hepcidin promotes the degradation of ferroportin, thereby reducing duodenal iron absorption [67]. Downregulation of hepcidin enhances the expression of ferroportin and divalent metal transporter 1 in the duodenum [68]. This is in line with the observation that alcohol intake elevates serum iron levels, serum ferritin levels, and transferrin-iron saturation [69]. In addition to the serum iron levels, hepatic iron is reportedly increased in ALD patients, which may contribute to ROS-associated alcohol toxicity, as iron induces oxidative stress through Fenton reactions [70][71]. Iron overload can also cause cellular damage and death through the process called ferroptosis, a type of iron-dependent programmed cell death [72][73]. There are several crucial regulators of ferroptosis, including lipid peroxidation and iron accumulation [74]. Iron accumulation in cells causes lipid peroxidation and subsequent damage and rupture of the cell membrane, thereby promoting the release of damage-associated molecular patterns (DAMPs) [75]. Iron is believed to play a role in ROS production through several mechanisms, such as iron-containing enzymes (e.g., lipoxygenase) and the Fenton reaction that requires iron [76][77]. In the liver, ferroptosis generates ROS and depletes glutathione levels [78][79]. Ferroptosis has gained momentum as a type of cell death that exacerbates ALD, as evidenced by iron overload observed in the liver of patients with alcohol-related cirrhosis [80]. Moreover, alcohol administration was shown to induce excessive iron accumulation and ferroptosis in animal models [81][82].
ROS are highly reactive and can react with various biological materials ranging from lipids to nucleic acids and proteins. Lipid species reacting with ROS undergo lipid peroxidation and produce 4-hydroxynonenal and malondialdehyde, which can induce several forms of cell death, including apoptosis and ferroptosis [83][84]. Lipid peroxidation products can also bind to DNA and enhance carcinogenesis by producing etheno-DNA adducts [85][86]. Proteins that react with ROS modify their structures and functions, possibly resulting in neoantigens that can induce an immune response [87].
Building on the concept that oxidative stress is involved in hepatocyte injury in ALD, several recent reports have investigated the therapeutic potential of suppressing oxidative stress-associated signaling pathways. For example, Ma et al. demonstrated that inhibition of ASK1 and p38MAPK, which relay oxidative stress to cell death signaling, afforded protection against hepatocyte death induced by ethanol feeding in mice [88]. In addition, recent studies have demonstrated that the Nrf2/ARE pathway might be a useful target for reducing ethanol-induced oxidative stress and liver injury [20][89][90][91][92][93][94].

2.2. Immune Cells Mediating the Crosstalk between Oxidative Stress and Inflammation in ALD

Alcohol-exposed hepatocytes that undergo oxidative stress-induced cellular injury and death produce a variety of inflammatory mediators, such as cytokines, chemokines, and DAMPs (e.g., high-mobility group box 1 protein and mitochondrial DNA), which can, in turn, activate immune reactions and inflammation [95][96][97][98]. DAMPs are recognized by Toll-like receptors (TLRs) and NOD-like receptors, such as NLRPs, which are expressed in hepatocytes and immune cells [99][100]. DAMP-mediated activation of these receptors intensifies innate immunity-related inflammatory pathways in ALD, along with enhanced expression of cytokines, chemokines, and adhesion molecules that promote the infiltration and/or activation of innate immune cells, such as neutrophils, macrophages, and Kupffer cells [101][102][103]. In addition, alcohol consumption augments ROS levels and lipid peroxidation, facilitating the production of protein adducts with malondialdehyde and 4-hydroxynonenal, which may function as neoantigens and activate adaptive immunity mediated by T and B cells [104].
As stated above, hepatic inflammation during ALD progression is associated with the infiltration and activation of inflammatory cells, such as macrophages and neutrophils, whose actions are associated with ROS production [105][106]. Oxidative stress and inflammatory cell activation often mutually affect each other; ROS derived from damaged cells activate inflammatory cells, and the activation of these immune cells further enhances oxidative stress by producing ROS and reactive nitrogen species such as peroxynitrite and nitric oxide [107][108]. This section highlights the detailed roles of oxidative immune cells in the progression of ALD.

2.2.1. Neutrophils

Neutrophils are the most abundant subset of leukocytes in the circulation and participate in various processes of immune reactions and inflammation [109]. For example, in response to oxidative hepatic injury during ALD progression, neutrophils migrate from the circulation to the affected tissue, regulated by chemokines, cytokines, and adhesion molecules that attract and activate neutrophils in an orchestrated manner (Figure 2) [110][111][112].
Ijms 23 00774 g002 550
Figure 2. Role of neutrophils in the development of ALD. Injured hepatocytes with oxidative stress promote neutrophil infiltration and activation via the release of DAMPs, cytokines, and chemokines. In addition, endothelial cells upregulate adhesion molecules, such as SELE, to facilitate hepatic neutrophil infiltration. Neutrophils play both protective and detrimental roles during ALD progression. Generally, neutrophils are known to exacerbate ALD via oxidative burst, ROS production, cytokine release, and the release of granule proteins (e.g., myeloperoxidase). However, neutrophils also express antimicrobial factors, such as lipocalin 2, and play a crucial role in affording protection against infection in patients with ALD. Neutrophils are also involved in tissue repair by releasing HGF and inflammation resolution, delaying the progression of ALD. NETs not only augment hepatocyte injury but also mediate the antimicrobial function of neutrophils. HGF, hepatocyte growth factor; HMGB1, high-mobility group box 1 protein; NET, neutrophil extracellular trap; SELE, E-selectin.
Hepatic neutrophil infiltration is enhanced after chronic alcohol consumption and acute and heavy alcohol exposure [113][114][115][116]. In particular, binge ethanol intake can promote hepatic neutrophil infiltration and elevate circulating neutrophils in alcoholic individuals [117], which is postulated to contribute to the switching of chronic ASH with macrophage inflammation to AH with neutrophil infiltration [118]. Animal models that mimic the acute-on-chronic alcohol consumption pattern of alcoholics have also been reported to exhibit marked neutrophil infiltration in the liver. The National Institute on Alcohol Abuse and Alcoholism (NIAAA) model is characterized by a combination of 10 days of ad libitum feeding on the Lieber–DeCarli ethanol diet and a single binge ethanol feeding (chronic-plus-binge ethanol feeding), recapitulating the features of early-stage AH [119]. In the livers of mice subjected to the NIAAA model, neutrophil-recruiting chemokines, such as CXCL1 and interleukin (IL)-8, were upregulated, along with substantial neutrophil infiltration, similar to the liver of patients with ALD [115].
While oxidative stress-associated hepatocyte damage and death promote neutrophil activation and recruitment to the site of injury, activated neutrophils can also produce ROS through oxidative burst, which is one of the mechanisms underlying neutrophil functions [105][120]. Other mechanisms include phagocytosis, degranulation, the release of proteases (e.g., neutrophil elastase), and neutrophil extracellular trap formation [121]. Oxidative burst is mediated by NOX2 and its association with components of the NOX2 complex, such as p47phox, p67phox, p40phox, and p22phox [122][123]. Neutrophilic ROS production via oxidative bursts may further stimulate hepatocyte injury [117][124][125].
Li et al. investigated the critical role of the neutrophilic IL-6-p47phox-oxidative stress pathway in the development of ALD [117]. Mice deficient in the gene encoding microRNA-223 (miR-223) were more susceptible to hepatic neutrophil infiltration and neutrophil ROS production when subjected to the chronic-plus-binge ethanol feeding model of ALD [117]. Mechanistically, the authors showed that miR-223 inhibited the IL-6-p47phox-ROS pathway in neutrophils, thereby decreasing the severity of the alcohol-induced liver injury. In addition, the authors documented numerous circulating neutrophils and higher levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in alcoholics with recent excessive drinking than in healthy individuals. Roh et al. demonstrated that the upregulation of CXCL1 and subsequent neutrophil infiltration in mice subjected to chronic-plus-binge ethanol feeding depended on TLR2 and TLR9 signaling [126].
IL-17 is reportedly elevated in patients with AH and can affect the function of neutrophil-attracting chemokines [127]. Ma et al. reported that deletion of the gene encoding IL-17RA reduced the expression level of CXCL1 and delayed the development of alcohol-associated liver cancer, indicating that IL-17 signaling promotes hepatocellular carcinoma in ALD [128].
Typically, neutrophils have been recognized as a deleterious cell type that exacerbates alcohol-induced liver injury and inflammation; however, studies have also revealed the potential benefits of neutrophils. Neutrophil dysfunction predicts the poor prognosis of AH with cirrhosis, which has been attributed to uncontrolled infection [129]. Neutrophils may participate in tissue repair and inflammation resolution to maintain tissue homeostasis. For instance, neutrophil-mediated ROS production stimulates the conversion of proinflammatory macrophages (Ly6ChiCX3CR1lo) to pro-resolving macrophages (Ly6CloCX3CR1hi) during acute liver injury [130][131]. Further studies are warranted to elucidate the complex functions of neutrophils. The advent of single-cell analysis may accelerate the identification of a distinct subset of neutrophils that differentially participate in the pathogenesis of ALD.

2.2.2. Macrophages

During the course of ALD progression, the sustained inflammatory environment leads to hepatic monocyte infiltration. Monocytes infiltrating the liver differentiate into macrophages [132]. Several subpopulations of macrophages exist in the liver, including resident macrophages, Kupffer cells, and monocyte-derived macrophages [133]. The population of macrophages was shown to be elevated in the liver of patients with ALD, as well as in experimental ALD models [134][135]. In addition, a study conducted in rats reported that depletion of hepatic macrophages by gadolinium chloride treatment reduced alcohol-induced hepatic inflammation [136], indicating the importance of hepatic macrophages in the development of ALD.
Alcohol consumed is absorbed through the gastrointestinal tract; thus, the gut is one of the first organs whose integrity is altered by alcohol intake [137][138][139][140].
Ethanol and ethanol metabolites modulate the physiology of the intestine through several mechanisms. First, ethanol and ethanol metabolites may directly damage the intestine epithelial cells. In humans, ethanol consumption results in acute subepithelial bleb formation and hemorrhagic erosions [141]. Chronic alcohol consumption alters the histological properties of the duodenal mucosa (e.g., decreased surface area) [142]. In rats, hemorrhagic erosions of the proximal small intestine with epithelial cell loss were observed upon acute administration of ethanol [143]. In mice, submucosal blebbing and ulceration of villi in the ileal small intestine were observed upon acute ethanol exposure [144]. A study using Caco-2 monolayers demonstrated that ethanol treatment induced apoptosis, which was augmented by exposure to E. coli [145][146]. Oxidative stress-associated mitochondrial dysfunction has been suggested as a potential mechanism underlying the damage of intestinal epithelial cells by ethanol metabolites such as fatty acyl ethyl esters [147].
Secondly, ethanol and ethanol metabolites impair the integrity of tight junctions in epithelial barriers, and the interaction between zonula occludens-1 and occludin is a hallmark of tight junction formation [148]. Ethanol and acetaldehyde cause redistribution of occludin from the intestine epithelial tight junctions [149][150][151][152]. Oxidative stress has also been suggested as a crucial mediator of alcohol-associated alteration of tight junctions. A study using Caco-2 cells revealed that ethanol treatment disrupted barrier function and damaged microtubules through inducible nitric oxide synthase (iNOS)-dependent ROS production [153]. The iNOS-dependent ROS production was found to be the mechanism by which ethanol gavage stimulates the intestinal permeability in rats [154].
Lastly, alcohol consumption can change the composition and the number of microbiota in the intestine, which may lead to an increase in gut permeability [155]. For example, patients with ALD have a lower population of Faecalibacterium prausnitzii, which produce butyric acid [156][157]. Butyric acid contributes to the intestine epithelial barrier by maintaining the expression of the tight junction proteins and mucins [158][159]. Bacteroidetes are reportedly decreased in the individuals with excessive alcohol consumption, whereas Proteobacteria are increased in individuals with chronic drinking [160]. Bacterial overgrowth has been also observed in experimental ALD models and patients with ALD. For instance, three-week feeding of ethanol increased the population of bacteria in the small intestine of mice [161]. Bacterial growth is reportedly profound in humans with chronic alcohol abuse [162][163].
Alcohol-induced dysregulation of the intestinal barrier mediated by the mechanisms above is postulated to increase gut permeability to Gram-negative bacterial endotoxin, promoting the transfer of endotoxin to the circulation and eventually to the liver via the portal vein [164][165][166][167]. Pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS) associated with the incoming bacteria interact with TLR4 in macrophages, including Kupffer cells, stimulating the production and release of inflammatory cytokines and chemokines that further augment inflammation and recruit monocytes [111][168]. Apart from PAMPs, DAMPs may also activate Kupffer cells in the context of sterile inflammation during ALD development, which, in turn, stimulates the release of inflammatory mediators that promote the infiltration and activation of monocytes/macrophages [95][169][170]. One possible mechanism is dependent on the action of inflammasomes, known to activate caspase-1 and secrete inflammatory mediators, including IL-1β and IL-18 [171][172].
There are two distinct types of infiltrating monocytes depending on Ly6C expression levels. Ly6Chi monocytes are proinflammatory and tissue-damaging, whereas Ly6Clo monocytes mediate patrolling, anti-inflammatory, and tissue-reparative functions [173]. The number of Ly6Chi monocytes was found to be increased in experimental ALD [135]. Ly6Chi cells participate in the efferocytosis of apoptotic hepatocytes, which is the process through which dying cells are removed by phagocytic cells such as macrophages [174]. Accordingly, Ly6Chi cells may switch to Ly6Clo cells after efferocytosis of hepatocytes [135][175].
The production of oxidants in activated macrophages primarily occurs through the action of NOX [123][176]. Chronic ethanol feeding-induced ROS production in Kupffer cells is dependent on the action of NOX and p47phox [177]. NOX-derived ROS are key players mediating nuclear factor-kappa B (NF-κB) activation and subsequent production of tumor necrosis factor (TNF)-α in Kupffer cells upon ethanol administration [177], thus indicating that oxidative stress may enhance the inflammatory function of Kupffer cells and contribute to ALD pathogenesis. Furthermore, ROS can sensitize Kupffer cells to LPS. In animals subjected to chronic ethanol feeding, LPS-induced ROS production was enhanced in Kupffer cells, which was attenuated by inhibiting NADPH oxidase [178]. LPS sensitization in Kupffer cells by NADPH oxidase-derived ROS (e.g., LPS-stimulated TNF-α production) was in part attributed to the activation of extracellular signal-regulated kinase (ERK), a stress kinase activated by ROS [178].
Despite the abundance of the hepatic resident macrophages, as well as a marked increase in the population of hepatic macrophages upon alcohol consumption, there remains a gap in the knowledge regarding the role of macrophages in ALD pathogenesis. Identifying signaling molecules that link oxidative and inflammatory functions of macrophages, as well as those responsible for the interdependence between the polarization status of macrophages and their oxidative ability, will open new avenues for future research.

2.2.3. Other Types of Immune Cells

Neoantigens generated by ROS-induced alteration of protein structures can result in T cell activation [179]. Activated T cells promote the progression of ALD by releasing proinflammatory cytokines such as TNF-α, IL-1, and IL-17 [180]. In addition, the cytotoxic property exerted by CD8+ T cells contributes to the progression of ALD [181]. In addition to CD8+ T cells, CD4+ T cells also contribute to ALD development by releasing multiple types of cytokines. For example, Th1 cells help activate macrophages and exacerbate liver injury and inflammation by releasing cytokines such as interferon (IFN)-γ, IL-2, and TNF-α [182][183]. Th17 cells produce IL-17, which enhances liver injury and inflammation; however, Th17 cells can produce IL-22, which possesses anti-apoptotic and antioxidant properties through STAT3 activation [127][184][185][186].
Natural killer T (NKT) cells are a subset of T cells that express T cell receptors; however, they also express unique marker proteins such as NK1.1, CD161, and CD56 in humans [187]. Although NKT cells are presumed to be involved in accelerating ALD progression by activating hepatic macrophages in rodent models, limited data are available to determine whether NKT cells contribute to ALD progression in humans [180]. Mathews et al. demonstrated that chronic-plus-binge ethanol feeding in mice activated invariant NKT cells, also known as type 1 NKT cells, which release mediators that recruit neutrophils to the liver and promote the development of ALD [114]. In contrast, type 2 NKT cells may inhibit the progression of ALD by suppressing the action of type 1 NKT cells [188].
Mucosa-associated invariant T (MAIT) cells are a subset of innate-like T cells that possess a conserved invariant T cell antigen receptor (TCR) α-chain [189]. The composition of the chain is different between species. For example, humans possess Vα7.2-Jα33, whereas mice possess Vα19-Jα33 [190].
MAIT cells are abundantly observed in the liver of humans [191]. Approximately 30% of intrahepatic T cells are considered MAIT cells in humans; however, mice have markedly lower population of MAIT cells, which makes it difficult to precisely understand the function of MAIT cells [192]. MAIT cells have been demonstrated to inhibit bacterial infection [193]. Mechanistically, invariant TCRs in MAIT cells interact with riboflavin (vitamin B2) derivatives that are presented by the major histocompatibility complex class I-related protein 1 [194]. Mechanisms that are independent of TCRs are also known to mediate the antibacterial function of MAIT cells. For instance, IL-12 and IL-18 may activate MAIT cells, thereby producing numerous types of cytokines, including TNF-α, IFN-γ, and IL-22, and regulating immune responses [194].
Riva et al. reported that patients with alcoholic cirrhosis and severe alcoholic hepatitis have lower levels of MAIT cells in the circulation and weakened antibacterial potency [195]. They also reported that intestinal bacterial antigens and metabolites reduced the production of antibacterial cytokines by MAIT cells in vitro [195]. Alcohol consumption-associated dysfunction of the intestinal epithelial barrier leads to an increased gut permeability which induces the migration of bacterial antigens and metabolites to the portal circulation. These may reduce the number of MAIT cells in the circulation as well as in the liver, which may in part explain the reduced antibacterial capability observed in individuals with chronic alcohol consumption.

2.3. The Role of MicroRNAs in the Crosstalk between Oxidative Stress and Inflammation in ALD

MicroRNAs (miRNAs) are key players in ALD. The landscape of miRNA expression is reportedly altered under pathological conditions [196][197][198]. Dysregulated miRNAs contribute to the regulation of pathophysiological pathways in ALD via several different mechanisms (Table 1). miRNAs can directly bind to the 3′UTR of target genes, leading to degradation or translational repression of target mRNAs. In contrast, miRNAs sometimes enhance translational activation [199]. Furthermore, miRNAs not only mediate gene regulation, but several miRNAs possessing a GC-rich motif (e.g., let-7b, miR-21, and miR-29a) can serve as ligands for TLRs [200]. Herein, we discuss the role of miRNAs in inflammation, cell death, and oxidative stress during ALD and their regulatory mechanisms.
Table 1. Aberrant microRNA expression in ALD and the associated pathological effects.
microRNA Status in ALD Targets Effects References
Let-7b Up TLR7 activation ↑hepatic inflammatory response [201]
miR-150-5p Up CISH ↑FADD-mediated programmed cell death [202]
miR-155 Up Cebpb ↑M1 macrophage polarization
↑fatty liver		 [203][204][205][206]
miR-181b Up PIAS1 oxidative stress and inflammation [197][207]
miR-182 Up SLC1A1
CFL1		 ↑liver injury and inflammation [197]
miR-214 Up GSR
POR		 ↑oxidative stress [208]
miR-223 Up IL-6 ↓oxidative stress [117]
miR-540 Up PPARα, PMP70, ACOX1, CPT1a ↑hepatic steatosis [209]
miR-148a Down TXNIP ↑TXNIP-dependent inflammasome activation
↑ADH4 and CYP2B6		 [10][210][211]
miR-219a-5p Down P66shc ↑oxidative stress [212]
The most overexpressed miRNA in the liver tissue of patients with AH when compared with normal livers is miR-182 [197]. Increased miR-182 levels are associated with disease severity. miR-182 is mainly found in the ductular reaction cells. In cholangiocytes, miR-182 reportedly targets SLC1A1 and CFL1, whereas miR-182 increases the levels of proinflammatory genes such as CCL20, CXCL1, and IL-8. In addition, miR-182 enhanced IL-6 mRNA levels in hepatocytes and macrophages. Blocking miR-182 using a decoy inhibited liver injury, bile acid accumulation, and proinflammatory genes [197]. Circulating miR-155 and miR-155 levels in hepatocytes and macrophages were elevated in ALD [203][204]. miR-155 induced M1 macrophage polarization by targeting Cebpb and promoted TNF-α production in macrophages [205]. miR-155 knockout mice were found to be resistant to alcohol-induced fatty liver and inflammation [206]. Let-7, a TLR7 ligand, contributes to the hepatic inflammatory response in AH [201]. Ethanol was shown to stimulate the release of let-7b in microvesicles originating from hepatocytes. Hepatic expression levels of let-7b positively correlated with IL-8 and nuclear enriched abundant transcript 1 (NEAT1) expression levels in patients with AH. Activation of TLR7 may contribute to the induction of a subset of inflammatory genes, such as IL-8 and TNF-α [201]. Therefore, miRNAs appear to play a role in the regulation of the inflammatory response associated with ALD.
In addition, miRNAs mediate hepatocyte death in alcohol-associated hepatitis. Elevated IL-1 levels were detected in patients with AH [213]. NLRP3 inflammasome activation and caspase-1-mediated pyroptosis in hepatocytes are reportedly enhanced during ALD [10]. Pyroptosis is regulated by miR-148a, a miRNA abundant in the liver. The miR-148a expression level was greatly decreased in patients with AH and in ALD animal models. Decreased miR-148a expression level by ethanol was found to be responsible for thioredoxin-interacting protein (TXNIP) overexpression. TXNIP-dependent inflammasome activation contributes to hepatocyte pyroptosis. Moreover, miR-148a non-canonically increased the mRNA stability of ADH4 and CYP2B6 by directly binding to the coding sequence and 3′UTR sequence, respectively [210][211]. Caspase-3-mediated apoptosis was shown to be regulated by miRNA(s) in alcohol-associated hepatitis. Fan et al. identified a miRNA-E3 ubiquitin ligase regulatory network for hepatocyte death pathways [202]. miR-150-5p negatively regulated the E3 ligase cytokine-inducible SH2 containing protein (CISH). As Fas-associated protein with death domain, (FADD) is a CISH substrate, ubiquitination of FADD was reduced in the NIAAA model of ethanol-induced liver injury, thus resulting in an increased extent of caspase-3 activation and programmed cell death [202]. These results suggest that miRNAs play an important role in diverse types of hepatocyte death, including pyroptosis and apoptosis.
Additional evidence suggests that oxidative stress-induced miRNA may contribute to the pathology of ALD. Ethanol feeding reduced levels of augmenter of liver regeneration (ALR). ALR deficiency-mediated oxidative stress increased miR-540, which disturbed peroxisomal and mitochondrial lipid homeostasis [209].
miRNAs also play an important role in alcohol-associated oxidative stress. Ethanol can induce miR-214 expression in liver cells [208]. miR-214 was found to directly bind to the 3′UTR of glutathione reductase (GSR) and cytochrome P450 oxidoreductase (POR) genes. Reduced GSR and POR levels induced by miR-214 promoted ethanol-induced oxidative stress. In a rat model of alcoholic fatty liver diseases, miR-181b-5p levels were elevated [207]. Inhibition of miR-181b-5p attenuated oxidative stress. Silencing miR-181b-5p increased protein inhibitors of activated STAT1 to suppress oxidative stress and inflammatory response [207]. miR-241 and miR-181b-5p increased by ethanol may induce oxidative stress.
In contrast, the miR-223 level increases in serum and neutrophils in chronic-plus-binge ethanol feeding, and miR-223 attenuates the IL-6-p47phox-oxidative stress pathway in neutrophils [117]. Therefore, miR-223 inhibits neutrophil infiltration and protects against alcohol-induced liver injury. Interestingly, the neutrophilic miR-223 expression level was lower in aged mice than in young mice [214]. Aging stimulates the susceptibility to acute and chronic alcohol-induced liver injury by inhibiting the neutrophilic SIRT1-C/EBPα-miR-223 axis. miR-219a-5p attenuated p66shc-mediated ROS in ALD [212]. Protocatechuic acid, a component of green tea, can induce miR-219a-5p expression, thereby ameliorating ALD by reducing ROS formation. These findings suggest that miRNA modulators could play a protective role in ALD by controlling the oxidation pathway. Collectively, miRNAs are major contributors to oxidative stress and inflammatory liver injury in ALD.

References

  1. Piano, M.R. Alcohol’s Effects on the Cardiovascular System. Alcohol Res. 2017, 38, 219–241.
  2. Obad, A.; Peeran, A.; Little, J.I.; Haddad, G.E.; Tarzami, S.T. Alcohol-Mediated Organ Damages: Heart and Brain. Front. Pharmacol. 2018, 9, 81.
  3. Pasala, S.; Barr, T.; Messaoudi, I. Impact of Alcohol Abuse on the Adaptive Immune System. Alcohol Res. 2015, 37, 185–197.
  4. Barr, T.; Helms, C.; Grant, K.; Messaoudi, I. Opposing effects of alcohol on the immune system. Prog. Neuropsychopharmacol. Biol. Psychiatry 2016, 65, 242–251.
  5. Szabo, G.; Saha, B. Alcohol’s Effect on Host Defense. Alcohol Res. 2015, 37, 159–170.
  6. Gao, B.; Bataller, R. Alcoholic liver disease: Pathogenesis and new therapeutic targets. Gastroenterology 2011, 141, 1572–1585.
  7. Mandrekar, P.; Bataller, R.; Tsukamoto, H.; Gao, B. Alcoholic hepatitis: Translational approaches to develop targeted therapies. Hepatology 2016, 64, 1343–1355.
  8. Chacko, K.R.; Reinus, J. Spectrum of Alcoholic Liver Disease. Clin. Liver Dis. 2016, 20, 419–427.
  9. Osna, N.A.; Donohue, T.M., Jr.; Kharbanda, K.K. Alcoholic Liver Disease: Pathogenesis and Current Management. Alcohol Res. 2017, 38, 147–161.
  10. Heo, M.J.; Kim, T.H.; You, J.S.; Blaya, D.; Sancho-Bru, P.; Kim, S.G. Alcohol dysregulates miR-148a in hepatocytes through FoxO1, facilitating pyroptosis via TXNIP overexpression. Gut 2019, 68, 708–720.
  11. Sakhuja, P. Pathology of alcoholic liver disease, can it be differentiated from nonalcoholic steatohepatitis? World J. Gastroenterol. 2014, 20, 16474–16479.
  12. Lackner, C.; Tiniakos, D. Fibrosis and alcohol-related liver disease. J. Hepatol. 2019, 70, 294–304.
  13. Chayanupatkul, M.; Liangpunsakul, S. Alcoholic hepatitis: A comprehensive review of pathogenesis and treatment. World J. Gastroenterol. 2014, 20, 6279–6286.
  14. Marroni, C.A.; Fleck, A.M., Jr.; Fernandes, S.A.; Galant, L.H.; Mucenic, M.; de Mattos Meine, M.H.; Mariante-Neto, G.; Brandão, A.B.M. Liver transplantation and alcoholic liver disease: History, controversies, and considerations. World J. Gastroenterol. 2018, 24, 2785–2805.
  15. Chuncharunee, L.; Yamashiki, N.; Thakkinstian, A.; Sobhonslidsuk, A. Alcohol relapse and its predictors after liver transplantation for alcoholic liver disease: A systematic review and meta-analysis. BMC Gastroenterol. 2019, 19, 150.
  16. Lucey, M.R.; Mathurin, P.; Morgan, T.R. Alcoholic hepatitis. N. Engl. J. Med. 2009, 360, 2758–2769.
  17. Amini, M.; Runyon, B.A. Alcoholic hepatitis 2010: A clinician’s guide to diagnosis and therapy. World J. Gastroenterol. 2010, 16, 4905–4912.
  18. Wang, H.; Mehal, W.; Nagy, L.E.; Rotman, Y. Immunological mechanisms and therapeutic targets of fatty liver diseases. Cell. Mol. Immunol. 2021, 18, 73–91.
  19. Louvet, A.; Mathurin, P. Alcoholic liver disease: Mechanisms of injury and targeted treatment. Nat. Rev. Gastroenterol. Hepatol. 2015, 12, 231–242.
  20. Sun, J.; Fu, J.; Li, L.; Chen, C.; Wang, H.; Hou, Y.; Xu, Y.; Pi, J. Nrf2 in alcoholic liver disease. Toxicol. Appl. Pharmacol. 2018, 357, 62–69.
  21. Donohue, T.M., Jr. Alcohol-induced steatosis in liver cells. World J. Gastroenterol. 2007, 13, 4974–4978.
  22. Ji, C. Advances and New Concepts in Alcohol-Induced Organelle Stress, Unfolded Protein Responses and Organ Damage. Biomolecules 2015, 5, 1099–1121.
  23. Cao, S.; Liu, M.; Sehrawat, T.S.; Shah, V.H. Regulation and functional roles of chemokines in liver diseases. Nat. Rev. Gastroenterol. Hepatol. 2021, 18, 630–647.
  24. Fujii, H.; Kawada, N. Fibrogenesis in alcoholic liver disease. World J. Gastroenterol. 2014, 20, 8048–8054.
  25. Mantena, S.K.; King, A.L.; Andringa, K.K.; Landar, A.; Darley-Usmar, V.; Bailey, S.M. Novel interactions of mitochondria and reactive oxygen/nitrogen species in alcohol mediated liver disease. World J. Gastroenterol. 2007, 13, 4967–4973.
  26. Speisky, H.; Kera, Y.; Penttilä, K.E.; Israel, Y.; Lindros, K.O. Depletion of hepatic glutathione by ethanol occurs independently of ethanol metabolism. Alcohol. Clin. Exp. Res. 1988, 12, 224–228.
  27. Jewell, S.A.; Di Monte, D.; Gentile, A.; Guglielmi, A.; Altomare, E.; Albano, O. Decreased hepatic glutathione in chronic alcoholic patients. J. Hepatol. 1986, 3, 1–6.
  28. Wu, D.; Cederbaum, A.I. Oxidative stress and alcoholic liver disease. Semin. Liver Dis. 2009, 29, 141–154.
  29. Zhu, H.; Jia, Z.; Misra, H.; Li, Y.R. Oxidative stress and redox signaling mechanisms of alcoholic liver disease: Updated experimental and clinical evidence. J. Dig. Dis. 2012, 13, 133–142.
  30. Lu, Y.; Zhuge, J.; Wang, X.; Bai, J.; Cederbaum, A.I. Cytochrome P450 2E1 contributes to ethanol-induced fatty liver in mice. Hepatology 2008, 47, 1483–1494.
  31. Cederbaum, A.I. Alcohol metabolism. Clin. Liver Dis. 2012, 16, 667–685.
  32. Xie, N.; Zhang, L.; Gao, W.; Huang, C.; Huber, P.E.; Zhou, X.; Li, C.; Shen, G.; Zou, B. NAD+ metabolism: Pathophysiologic mechanisms and therapeutic potential. Signal Transduct. Target. Ther. 2020, 5, 227.
  33. You, M.; Fischer, M.; Deeg, M.A.; Crabb, D.W. Ethanol induces fatty acid synthesis pathways by activation of sterol regulatory element-binding protein (SREBP). J. Biol. Chem. 2002, 277, 29342–29347.
  34. Esfandiari, F.; Medici, V.; Wong, D.H.; Jose, S.; Dolatshahi, M.; Quinlivan, E.; Dayal, S.; Lentz, S.R.; Tsukamoto, H.; Zhang, Y.H.; et al. Epigenetic regulation of hepatic endoplasmic reticulum stress pathways in the ethanol-fed cystathionine beta synthase-deficient mouse. Hepatology 2010, 51, 932–941.
  35. Ji, C.; Deng, Q.; Kaplowitz, N. Role of TNF-alpha in ethanol-induced hyperhomocysteinemia and murine alcoholic liver injury. Hepatology 2004, 40, 442–451.
  36. Galli, A.; Pinaire, J.; Fischer, M.; Dorris, R.; Crabb, D.W. The transcriptional and DNA binding activity of peroxisome proliferator-activated receptor alpha is inhibited by ethanol metabolism. A novel mechanism for the development of ethanol-induced fatty liver. J. Biol. Chem. 2001, 276, 68–75.
  37. Wagner, M.; Zollner, G.; Trauner, M. Nuclear receptors in liver disease. Hepatology 2011, 53, 1023–1034.
  38. Seitz, H.K.; Bataller, R.; Cortez-Pinto, H.; Gao, B.; Gual, A.; Lackner, C.; Mathurin, P.; Mueller, S.; Szabo, G.; Tsukamoto, H. Alcoholic liver disease. Nat. Rev. Dis. Primers 2018, 4, 16.
  39. Lieber, C.S. Ethanol metabolism, cirrhosis and alcoholism. Clin. Chim. Acta 1997, 257, 59–84.
  40. Edenberg, H.J. The genetics of alcohol metabolism: Role of alcohol dehydrogenase and aldehyde dehydrogenase variants. Alcohol Res. Health 2007, 30, 5–13.
  41. Edenberg, H.J.; McClintick, J.N. Alcohol Dehydrogenases, Aldehyde Dehydrogenases, and Alcohol Use Disorders: A Critical Review. Alcohol. Clin. Exp. Res. 2018, 42, 2281–2297.
  42. Jiang, Y.; Zhang, T.; Kusumanchi, P.; Han, S.; Yang, Z.; Liangpunsakul, S. Alcohol Metabolizing Enzymes, Microsomal Ethanol Oxidizing System, Cytochrome P450 2E1, Catalase, and Aldehyde Dehydrogenase in Alcohol-Associated Liver Disease. Biomedicines 2020, 8, 50.
  43. Zhao, R.Z.; Jiang, S.; Zhang, L.; Yu, Z.B. Mitochondrial electron transport chain, ROS generation and uncoupling (Review). Int. J. Mol. Med. 2019, 44, 3–15.
  44. Zakhari, S. Overview: How is alcohol metabolized by the body? Alcohol Res. Health 2006, 29, 245–254.
  45. Mailloux, R.J. Teaching the fundamentals of electron transfer reactions in mitochondria and the production and detection of reactive oxygen species. Redox. Biol. 2015, 4, 381–398.
  46. Zhao, M.; Matter, K.; Laissue, J.A.; Zimmermann, A. Copper/zinc and manganese superoxide dismutases in alcoholic liver disease: Immunohistochemical quantitation. Histol. Histopathol. 1996, 11, 899–907.
  47. Choi, D.W.; Kim, S.Y.; Kim, S.K.; Kim, Y.C. Factors involved in hepatic glutathione depletion induced by acute ethanol administration. J. Toxicol. Environ. Health A 2000, 60, 459–469.
  48. Lu, Y.; Cederbaum, A.I. CYP2E1 and oxidative liver injury by alcohol. Free Radic. Biol. Med. 2008, 44, 723–738.
  49. Leung, T.M.; Nieto, N. CYP2E1 and oxidant stress in alcoholic and non-alcoholic fatty liver disease. J. Hepatol. 2013, 58, 395–398.
  50. Bai, J.; Cederbaum, A.I. Overexpression of CYP2E1 in mitochondria sensitizes HepG2 cells to the toxicity caused by depletion of glutathione. J. Biol. Chem. 2006, 281, 5128–5136.
  51. Gouillon, Z.; Lucas, D.; Li, J.; Hagbjork, A.L.; French, B.A.; Fu, P.; Fang, C.; Ingelman-Sundberg, M.; Donohue, T.M., Jr.; French, S.W. Inhibition of ethanol-induced liver disease in the intragastric feeding rat model by chlormethiazole. Proc. Soc. Exp. Biol. Med. 2000, 224, 302–308.
  52. Ye, Q.; Lian, F.; Chavez, P.R.; Chung, J.; Ling, W.; Qin, H.; Seitz, H.K.; Wang, X.D. Cytochrome P450 2E1 inhibition prevents hepatic carcinogenesis induced by diethylnitrosamine in alcohol-fed rats. Hepatobiliary Surg. Nutr. 2012, 1, 5–18.
  53. Diesinger, T.; Buko, V.; Lautwein, A.; Dvorsky, R.; Belonovskaya, E.; Lukivskaya, O.; Naruta, E.; Kirko, S.; Andreev, V.; Buckert, D.; et al. Drug targeting CYP2E1 for the treatment of early-stage alcoholic steatohepatitis. PLoS ONE 2020, 15, e0235990.
  54. Sun, Q.; Zhang, W.; Zhong, W.; Sun, X.; Zhou, Z. Pharmacological inhibition of NOX4 ameliorates alcohol-induced liver injury in mice through improving oxidative stress and mitochondrial function. Biochim. Biophys. Acta Gen. Subj. 2017, 1861, 2912–2921.
  55. Yang, C.F.; Zhong, Y.J.; Ma, Z.; Li, L.; Shi, L.; Chen, L.; Li, C.; Wu, D.; Chen, Q.; Li, Y.W. NOX4/ROS mediate ethanolinduced apoptosis via MAPK signal pathway in L02 cells. Int. J. Mol. Med. 2018, 41, 2306–2316.
  56. Miyata, T.; Nagy, L.E. Programmed cell death in alcohol-associated liver disease. Clin. Mol. Hepatol. 2020, 26, 618–625.
  57. Hoek, J.B.; Cahill, A.; Pastorino, J.G. Alcohol and mitochondria: A dysfunctional relationship. Gastroenterology 2002, 122, 2049–2063.
  58. Sastre, J.; Serviddio, G.; Pereda, J.; Minana, J.B.; Arduini, A.; Vendemiale, G.; Poli, G.; Pallardo, F.V.; Vina, J. Mitochondrial function in liver disease. Front. Biosci. 2007, 12, 1200–1209.
  59. Shalbueva, N.; Mareninova, O.A.; Gerloff, A.; Yuan, J.; Waldron, R.T.; Pandol, S.J.; Gukovskaya, A.S. Effects of oxidative alcohol metabolism on the mitochondrial permeability transition pore and necrosis in a mouse model of alcoholic pancreatitis. Gastroenterology 2013, 144, 437–446.
  60. Zelickson, B.R.; Benavides, G.A.; Johnson, M.S.; Chacko, B.K.; Venkatraman, A.; Landar, A.; Betancourt, A.M.; Bailey, S.M.; Darley-Usmar, V.M. Nitric oxide and hypoxia exacerbate alcohol-induced mitochondrial dysfunction in hepatocytes. Biochim. Biophys. Acta 2011, 1807, 1573–1582.
  61. Zou, H.; Li, Y.; Liu, X.; Wang, X. An APAF-1.cytochrome c multimeric complex is a functional apoptosome that activates procaspase-9. J. Biol. Chem. 1999, 274, 11549–11556.
  62. Zou, H.; Yang, R.; Hao, J.; Wang, J.; Sun, C.; Fesik, S.W.; Wu, J.C.; Tomaselli, K.J.; Armstrong, R.C. Regulation of the Apaf-1/caspase-9 apoptosome by caspase-3 and XIAP. J. Biol. Chem. 2003, 278, 8091–8098.
  63. Bratton, S.B.; Salvesen, G.S. Regulation of the Apaf-1-caspase-9 apoptosome. J. Cell Sci. 2010, 123, 3209–3214.
  64. Pastorino, J.G.; Shulga, N.; Hoek, J.B. TNF-alpha-induced cell death in ethanol-exposed cells depends on p38 MAPK signaling but is independent of Bid and caspase-8. Am. J. Physiol. Gastrointest. Liver Physiol. 2003, 285, G503–G516.
  65. Milic, S.; Mikolasevic, I.; Orlic, L.; Devcic, E.; Starcevic-Cizmarevic, N.; Stimac, D.; Kapovic, M.; Ristic, S. The Role of Iron and Iron Overload in Chronic Liver Disease. Med. Sci. Monit. 2016, 22, 2144–2151.
  66. Anderson, E.R.; Taylor, M.; Xue, X.; Martin, A.; Moons, D.S.; Omary, M.B.; Shah, Y.M. The hypoxia-inducible factor-C/EBPα axis controls ethanol-mediated hepcidin repression. Mol. Cell. Biol. 2012, 32, 4068–4077.
  67. Nemeth, E.; Tuttle, M.S.; Powelson, J.; Vaughn, M.B.; Donovan, A.; Ward, D.M.; Ganz, T.; Kaplan, J. Hepcidin regulates cellular iron efflux by binding to ferroportin and inducing its internalization. Science 2004, 306, 2090–2093.
  68. Harrison-Findik, D.D.; Schafer, D.; Klein, E.; Timchenko, N.A.; Kulaksiz, H.; Clemens, D.; Fein, E.; Andriopoulos, B.; Pantopoulos, K.; Gollan, J. Alcohol metabolism-mediated oxidative stress down-regulates hepcidin transcription and leads to increased duodenal iron transporter expression. J. Biol. Chem. 2006, 281, 22974–22982.
  69. Ioannou, G.N.; Dominitz, J.A.; Weiss, N.S.; Heagerty, P.J.; Kowdley, K.V. The effect of alcohol consumption on the prevalence of iron overload, iron deficiency, and iron deficiency anemia. Gastroenterology 2004, 126, 1293–1301.
  70. Purohit, V.; Russo, D.; Salin, M. Role of iron in alcoholic liver disease: Introduction and summary of the symposium. Alcohol 2003, 30, 93–97.
  71. Kohgo, Y.; Ohtake, T.; Ikuta, K.; Suzuki, Y.; Hosoki, Y.; Saito, H.; Kato, J. Iron accumulation in alcoholic liver diseases. Alcohol. Clin. Exp. Res. 2005, 29, 189s–193s.
  72. Jiang, X.; Stockwell, B.R.; Conrad, M. Ferroptosis: Mechanisms, biology and role in disease. Nat. Rev. Mol. Cell. Biol. 2021, 22, 266–282.
  73. Li, J.; Cao, F.; Yin, H.L.; Huang, Z.J.; Lin, Z.T.; Mao, N.; Sun, B.; Wang, G. Ferroptosis: Past, present and future. Cell Death Dis. 2020, 11, 88.
  74. Conrad, M.; Kagan, V.E.; Bayir, H.; Pagnussat, G.C.; Head, B.; Traber, M.G.; Stockwell, B.R. Regulation of lipid peroxidation and ferroptosis in diverse species. Genes Dev. 2018, 32, 602–619.
  75. Wen, Q.; Liu, J.; Kang, R.; Zhou, B.; Tang, D. The release and activity of HMGB1 in ferroptosis. Biochem. Biophys. Res. Commun. 2019, 510, 278–283.
  76. Latunde-Dada, G.O. Ferroptosis: Role of lipid peroxidation, iron and ferritinophagy. Biochim. Biophys. Acta Gen. Subj. 2017, 1861, 1893–1900.
  77. Su, L.J.; Zhang, J.H.; Gomez, H.; Murugan, R.; Hong, X.; Xu, D.; Jiang, F.; Peng, Z.Y. Reactive Oxygen Species-Induced Lipid Peroxidation in Apoptosis, Autophagy, and Ferroptosis. Oxid. Med. Cell. Longev. 2019, 2019, 5080843.
  78. Gautheron, J.; Gores, G.J.; Rodrigues, C.M.P. Lytic cell death in metabolic liver disease. J. Hepatol. 2020, 73, 394–408.
  79. Mao, L.; Zhao, T.; Song, Y.; Lin, L.; Fan, X.; Cui, B.; Feng, H.; Wang, X.; Yu, Q.; Zhang, J.; et al. The emerging role of ferroptosis in non-cancer liver diseases: Hype or increasing hope? Cell Death Dis. 2020, 11, 518.
  80. Macías-Rodríguez, R.U.; Inzaugarat, M.E.; Ruiz-Margáin, A.; Nelson, L.J.; Trautwein, C.; Cubero, F.J. Reclassifying Hepatic Cell Death during Liver Damage: Ferroptosis-A Novel Form of Non-Apoptotic Cell Death? Int. J. Mol. Sci. 2020, 21, 1651.
  81. Zhou, Z.; Ye, T.J.; DeCaro, E.; Buehler, B.; Stahl, Z.; Bonavita, G.; Daniels, M.; You, M. Intestinal SIRT1 Deficiency Protects Mice from Ethanol-Induced Liver Injury by Mitigating Ferroptosis. Am. J. Pathol. 2020, 190, 82–92.
  82. Zhou, Z.; Ye, T.J.; Bonavita, G.; Daniels, M.; Kainrad, N.; Jogasuria, A.; You, M. Adipose-Specific Lipin-1 Overexpression Renders Hepatic Ferroptosis and Exacerbates Alcoholic Steatohepatitis in Mice. Hepatol. Commun. 2019, 3, 656–669.
  83. Dalleau, S.; Baradat, M.; Guéraud, F.; Huc, L. Cell death and diseases related to oxidative stress: 4-hydroxynonenal (HNE) in the balance. Cell Death Differ. 2013, 20, 1615–1630.
  84. Yang, W.S.; Stockwell, B.R. Ferroptosis: Death by Lipid Peroxidation. Trends Cell Biol. 2016, 26, 165–176.
  85. Linhart, K.; Bartsch, H.; Seitz, H.K. The role of reactive oxygen species (ROS) and cytochrome P-450 2E1 in the generation of carcinogenic etheno-DNA adducts. Redox Biol. 2014, 3, 56–62.
  86. Mueller, S.; Peccerella, T.; Qin, H.; Glassen, K.; Waldherr, R.; Flechtenmacher, C.; Straub, B.K.; Millonig, G.; Stickel, F.; Bruckner, T.; et al. Carcinogenic Etheno DNA Adducts in Alcoholic Liver Disease: Correlation with Cytochrome P-4502E1 and Fibrosis. Alcohol. Clin. Exp. Res. 2018, 42, 252–259.
  87. Lu, L.; Jiang, J.; Zhan, M.; Zhang, H.; Wang, Q.T.; Sun, S.N.; Guo, X.K.; Yin, H.; Wei, Y.; Liu, J.O.; et al. Targeting Neoantigens in Hepatocellular Carcinoma for Immunotherapy: A Futile Strategy? Hepatology 2021, 73, 414–421.
  88. Ma, J.; Cao, H.; Rodrigues, R.M.; Xu, M.; Ren, T.; He, Y.; Hwang, S.; Feng, D.; Ren, R.; Yang, P.; et al. Chronic-plus-binge alcohol intake induces production of proinflammatory mtDNA-enriched extracellular vesicles and steatohepatitis via ASK1/p38MAPKα-dependent mechanisms. JCI Insight 2020, 5, e136496.
  89. Wang, G.; Fu, Y.; Li, J.; Li, Y.; Zhao, Q.; Hu, A.; Xu, C.; Shao, D.; Chen, W. Aqueous extract of Polygonatum sibiricum ameliorates ethanol-induced mice liver injury via regulation of the Nrf2/ARE pathway. J. Food. Biochem. 2021, 45, e13537.
  90. Jiang, W.; Zhu, H.; Xu, W.; Liu, C.; Hu, B.; Guo, Y.; Cheng, Y.; Qian, H. Echinacea purpurea polysaccharide prepared by fractional precipitation prevents alcoholic liver injury in mice by protecting the intestinal barrier and regulating liver-related pathways. Int. J. Biol. Macromol. 2021, 187, 143–156.
  91. Sun, J.; Hong, Z.; Shao, S.; Li, L.; Yang, B.; Hou, Y.; Wang, H.; Xu, Y.; Zhang, Q.; Pi, J.; et al. Liver-specific Nrf2 deficiency accelerates ethanol-induced lethality and hepatic injury in vivo. Toxicol. Appl. Pharmacol. 2021, 426, 115617.
  92. Zhao, X.; Gong, L.; Wang, C.; Liu, M.; Hu, N.; Dai, X.; Peng, C.; Li, Y. Quercetin mitigates ethanol-induced hepatic steatosis in zebrafish via P2X7R-mediated PI3K/ Keap1/Nrf2 signaling pathway. J. Ethnopharmacol. 2021, 268, 113569.
  93. Wang, X.; Chang, X.; Zhan, H.; Zhang, Q.; Li, C.; Gao, Q.; Yang, M.; Luo, Z.; Li, S.; Sun, Y. Curcumin and Baicalin ameliorate ethanol-induced liver oxidative damage via the Nrf2/HO-1 pathway. J. Food Biochem. 2020, 44, e13425.
  94. Sabitha, R.; Nishi, K.; Gunasekaran, V.P.; Agilan, B.; David, E.; Annamalai, G.; Vinothkumar, R.; Perumal, M.; Subbiah, L.; Ganeshan, M. p-Coumaric acid attenuates alcohol exposed hepatic injury through MAPKs, apoptosis and Nrf2 signaling in experimental models. Chem. Biol. Interact. 2020, 321, 109044.
  95. Ge, X.; Antoine, D.J.; Lu, Y.; Arriazu, E.; Leung, T.M.; Klepper, A.L.; Branch, A.D.; Fiel, M.I.; Nieto, N. High mobility group box-1 (HMGB1) participates in the pathogenesis of alcoholic liver disease (ALD). J. Biol. Chem. 2014, 289, 22672–22691.
  96. Cai, Y.; Xu, M.J.; Koritzinsky, E.H.; Zhou, Z.; Wang, W.; Cao, H.; Yuen, P.S.; Ross, R.A.; Star, R.A.; Liangpunsakul, S.; et al. Mitochondrial DNA-enriched microparticles promote acute-on-chronic alcoholic neutrophilia and hepatotoxicity. JCI Insight 2017, 2, e92634.
  97. Mihm, S. Danger-Associated Molecular Patterns (DAMPs): Molecular Triggers for Sterile Inflammation in the Liver. Int. J. Mol. Sci. 2018, 19, 3104.
  98. Hoyt, L.R.; Randall, M.J.; Ather, J.L.; DePuccio, D.P.; Landry, C.C.; Qian, X.; Janssen-Heininger, Y.M.; van der Vliet, A.; Dixon, A.E.; Amiel, E.; et al. Mitochondrial ROS induced by chronic ethanol exposure promote hyper-activation of the NLRP3 inflammasome. Redox Biol. 2017, 12, 883–896.
  99. Jo, E.K.; Kim, J.K.; Shin, D.M.; Sasakawa, C. Molecular mechanisms regulating NLRP3 inflammasome activation. Cell. Mol. Immunol. 2016, 13, 148–159.
  100. Kelley, N.; Jeltema, D.; Duan, Y.; He, Y. The NLRP3 Inflammasome: An Overview of Mechanisms of Activation and Regulation. Int. J. Mol. Sci. 2019, 20, 3328.
  101. Kany, S.; Janicova, A.; Relja, B. Innate Immunity and Alcohol. J. Clin. Med. 2019, 8, 1981.
  102. Kim, A.; Bellar, A.; McMullen, M.R.; Li, X.; Nagy, L.E. Functionally Diverse Inflammatory Responses in Peripheral and Liver Monocytes in Alcohol-Associated Hepatitis. Hepatol. Commun. 2020, 4, 1459–1476.
  103. Xu, M.J.; Zhou, Z.; Parker, R.; Gao, B. Targeting inflammation for the treatment of alcoholic liver disease. Pharmacol. Ther. 2017, 180, 77–89.
  104. Mottaran, E.; Stewart, S.F.; Rolla, R.; Vay, D.; Cipriani, V.; Moretti, M.; Vidali, M.; Sartori, M.; Rigamonti, C.; Day, C.P.; et al. Lipid peroxidation contributes to immune reactions associated with alcoholic liver disease. Free Radic. Biol. Med. 2002, 32, 38–45.
  105. Nguyen, G.T.; Green, E.R.; Mecsas, J. Neutrophils to the ROScue: Mechanisms of NADPH Oxidase Activation and Bacterial Resistance. Front. Cell. Infect. Microbiol. 2017, 7, 373.
  106. Tan, H.Y.; Wang, N.; Li, S.; Hong, M.; Wang, X.; Feng, Y. The Reactive Oxygen Species in Macrophage Polarization: Reflecting Its Dual Role in Progression and Treatment of Human Diseases. Oxid. Med. Cell. Longev. 2016, 2016, 2795090.
  107. Fialkow, L.; Wang, Y.; Downey, G.P. Reactive oxygen and nitrogen species as signaling molecules regulating neutrophil function. Free Radic. Biol. Med. 2007, 42, 153–164.
  108. Murphy, M.P.; Holmgren, A.; Larsson, N.G.; Halliwell, B.; Chang, C.J.; Kalyanaraman, B.; Rhee, S.G.; Thornalley, P.J.; Partridge, L.; Gems, D.; et al. Unraveling the biological roles of reactive oxygen species. Cell Metab. 2011, 13, 361–366.
  109. Rosales, C. Neutrophil: A Cell with Many Roles in Inflammation or Several Cell Types? Front. Physiol. 2018, 9, 113.
  110. Luk, G.D.; Silverman, A.L.; Giardiello, F.M. Biochemical markers in patients with familial colonic neoplasia. Semin. Surg. Oncol. 1987, 3, 126–132.
  111. Marra, F.; Tacke, F. Roles for chemokines in liver disease. Gastroenterology 2014, 147, 577–594.
  112. Kolaczkowska, E.; Kubes, P. Neutrophil recruitment and function in health and inflammation. Nat. Rev. Immunol. 2013, 13, 159–175.
  113. Liu, K.; Wang, F.S.; Xu, R. Neutrophils in liver diseases: Pathogenesis and therapeutic targets. Cell. Mol. Immunol. 2021, 18, 38–44.
  114. Mathews, S.; Feng, D.; Maricic, I.; Ju, C.; Kumar, V.; Gao, B. Invariant natural killer T cells contribute to chronic-plus-binge ethanol-mediated liver injury by promoting hepatic neutrophil infiltration. Cell. Mol. Immunol. 2016, 13, 206–216.
  115. Bertola, A.; Park, O.; Gao, B. Chronic plus binge ethanol feeding synergistically induces neutrophil infiltration and liver injury in mice: A critical role for E-selectin. Hepatology 2013, 58, 1814–1823.
  116. Hwang, S.; Ren, T.; Gao, B. Obesity and binge alcohol intake are deadly combination to induce steatohepatitis: A model of high-fat diet and binge ethanol intake. Clin. Mol. Hepatol. 2020, 26, 586–594.e1.
  117. Li, M.; He, Y.; Zhou, Z.; Ramirez, T.; Gao, Y.; Gao, Y.; Ross, R.A.; Cao, H.; Cai, Y.; Xu, M.; et al. MicroRNA-223 ameliorates alcoholic liver injury by inhibiting the IL-6-p47(phox)-oxidative stress pathway in neutrophils. Gut 2017, 66, 705–715.
  118. Lazaro, R.; Wu, R.; Lee, S.; Zhu, N.L.; Chen, C.L.; French, S.W.; Xu, J.; Machida, K.; Tsukamoto, H. Osteopontin deficiency does not prevent but promotes alcoholic neutrophilic hepatitis in mice. Hepatology 2015, 61, 129–140.
  119. Bertola, A.; Mathews, S.; Ki, S.H.; Wang, H.; Gao, B. Mouse model of chronic and binge ethanol feeding (the NIAAA model). Nat. Protoc. 2013, 8, 627–637.
  120. Blüml, S.; Rosc, B.; Lorincz, A.; Seyerl, M.; Kirchberger, S.; Oskolkova, O.; Bochkov, V.N.; Majdic, O.; Ligeti, E.; Stöckl, J. The oxidation state of phospholipids controls the oxidative burst in neutrophil granulocytes. J. Immunol. 2008, 181, 4347–4353.
  121. Németh, T.; Sperandio, M.; Mócsai, A. Neutrophils as emerging therapeutic targets. Nat. Rev. Drug. Discov. 2020, 19, 253–275.
  122. Bedard, K.; Krause, K.H. The NOX family of ROS-generating NADPH oxidases: Physiology and pathophysiology. Physiol. Rev. 2007, 87, 245–313.
  123. Panday, A.; Sahoo, M.K.; Osorio, D.; Batra, S. NADPH oxidases: An overview from structure to innate immunity-associated pathologies. Cell. Mol. Immunol. 2015, 12, 5–23.
  124. Khanam, A.; Trehanpati, N.; Riese, P.; Rastogi, A.; Guzman, C.A.; Sarin, S.K. Blockade of Neutrophil’s Chemokine Receptors CXCR1/2 Abrogate Liver Damage in Acute-on-Chronic Liver Failure. Front. Immunol. 2017, 8, 464.
  125. Hwang, S.; He, Y.; Xiang, X.; Seo, W.; Kim, S.J.; Ma, J.; Ren, T.; Park, S.H.; Zhou, Z.; Feng, D.; et al. Interleukin-22 Ameliorates Neutrophil-Driven Nonalcoholic Steatohepatitis Through Multiple Targets. Hepatology 2020, 72, 412–429.
  126. Roh, Y.S.; Zhang, B.; Loomba, R.; Seki, E. TLR2 and TLR9 contribute to alcohol-mediated liver injury through induction of CXCL1 and neutrophil infiltration. Am. J. Physiol. Gastrointest. Liver Physiol. 2015, 309, G30–G41.
  127. Lemmers, A.; Moreno, C.; Gustot, T.; Maréchal, R.; Degré, D.; Demetter, P.; de Nadai, P.; Geerts, A.; Quertinmont, E.; Vercruysse, V.; et al. The interleukin-17 pathway is involved in human alcoholic liver disease. Hepatology 2009, 49, 646–657.
  128. Ma, H.Y.; Yamamoto, G.; Xu, J.; Liu, X.; Karin, D.; Kim, J.Y.; Alexandrov, L.B.; Koyama, Y.; Nishio, T.; Benner, C.; et al. IL-17 signaling in steatotic hepatocytes and macrophages promotes hepatocellular carcinoma in alcohol-related liver disease. J. Hepatol. 2020, 72, 946–959.
  129. Mookerjee, R.P.; Stadlbauer, V.; Lidder, S.; Wright, G.A.; Hodges, S.J.; Davies, N.A.; Jalan, R. Neutrophil dysfunction in alcoholic hepatitis superimposed on cirrhosis is reversible and predicts the outcome. Hepatology 2007, 46, 831–840.
  130. Yang, W.; Tao, Y.; Wu, Y.; Zhao, X.; Ye, W.; Zhao, D.; Fu, L.; Tian, C.; Yang, J.; He, F.; et al. Neutrophils promote the development of reparative macrophages mediated by ROS to orchestrate liver repair. Nat. Commun. 2019, 10, 1076.
  131. Tecchio, C.; Micheletti, A.; Cassatella, M.A. Neutrophil-derived cytokines: Facts beyond expression. Front. Immunol. 2014, 5, 508.
  132. Italiani, P.; Boraschi, D. From Monocytes to M1/M2 Macrophages: Phenotypical vs. Functional Differentiation. Front. Immunol. 2014, 5, 514.
  133. Wen, Y.; Lambrecht, J.; Ju, C.; Tacke, F. Hepatic macrophages in liver homeostasis and diseases-diversity, plasticity and therapeutic opportunities. Cell. Mol. Immunol. 2021, 18, 45–56.
  134. Karakucuk, I.; Dilly, S.A.; Maxwell, J.D. Portal tract macrophages are increased in alcoholic liver disease. Histopathology 1989, 14, 245–253.
  135. Wang, M.; You, Q.; Lor, K.; Chen, F.; Gao, B.; Ju, C. Chronic alcohol ingestion modulates hepatic macrophage populations and functions in mice. J. Leukoc. Biol. 2014, 96, 657–665.
  136. Koop, D.R.; Klopfenstein, B.; Iimuro, Y.; Thurman, R.G. Gadolinium chloride blocks alcohol-dependent liver toxicity in rats treated chronically with intragastric alcohol despite the induction of CYP2E1. Mol. Pharmacol. 1997, 51, 944–950.
  137. Rao, R. Endotoxemia and gut barrier dysfunction in alcoholic liver disease. Hepatology 2009, 50, 638–644.
  138. Zhou, Z.; Zhong, W. Targeting the gut barrier for the treatment of alcoholic liver disease. Liver Res. 2017, 1, 197–207.
  139. Keshavarzian, A.; Farhadi, A.; Forsyth, C.B.; Rangan, J.; Jakate, S.; Shaikh, M.; Banan, A.; Fields, J.Z. Evidence that chronic alcohol exposure promotes intestinal oxidative stress, intestinal hyperpermeability and endotoxemia prior to development of alcoholic steatohepatitis in rats. J. Hepatol. 2009, 50, 538–547.
  140. Singal, A.K.; Shah, V.H. Current trials and novel therapeutic targets for alcoholic hepatitis. J. Hepatol. 2019, 70, 305–313.
  141. Gottfried, E.B.; Korsten, M.A.; Lieber, C.S. Alcohol-induced gastric and duodenal lesions in man. Am. J. Gastroenterol. 1978, 70, 587–592.
  142. Bode, J.C.; Knüppel, H.; Schwerk, W.; Lorenz-Meyer, H.; Dürr, H.K. Quantitative histomorphometric study of the jejunal mucosa in chronic alcoholics. Digestion 1982, 23, 265–270.
  143. Tamai, H.; Kato, S.; Horie, Y.; Ohki, E.; Yokoyama, H.; Ishii, H. Effect of acute ethanol administration on the intestinal absorption of endotoxin in rats. Alcohol. Clin. Exp. Res. 2000, 24, 390–394.
  144. Lambert, J.C.; Zhou, Z.; Wang, L.; Song, Z.; McClain, C.J.; Kang, Y.J. Prevention of alterations in intestinal permeability is involved in zinc inhibition of acute ethanol-induced liver damage in mice. J. Pharmacol. Exp. Ther. 2003, 305, 880–886.
  145. Asai, K.; Buurman, W.A.; Reutelingsperger, C.P.; Schutte, B.; Kaminishi, M. Low concentrations of ethanol induce apoptosis in human intestinal cells. Scand. J. Gastroenterol. 2003, 38, 1154–1161.
  146. Amin, P.B.; Diebel, L.N.; Liberati, D.M. Dose-dependent effects of ethanol and E. coli on gut permeability and cytokine production. J. Surg. Res. 2009, 157, 187–192.
  147. Elamin, E.; Masclee, A.; Juuti-Uusitalo, K.; van Ijzendoorn, S.; Troost, F.; Pieters, H.J.; Dekker, J.; Jonkers, D. Fatty acid ethyl esters induce intestinal epithelial barrier dysfunction via a reactive oxygen species-dependent mechanism in a three-dimensional cell culture model. PLoS ONE 2013, 8, e58561.
  148. Elamin, E.; Jonkers, D.; Juuti-Uusitalo, K.; van Ijzendoorn, S.; Troost, F.; Duimel, H.; Broers, J.; Verheyen, F.; Dekker, J.; Masclee, A. Effects of ethanol and acetaldehyde on tight junction integrity: In vitro study in a three dimensional intestinal epithelial cell culture model. PLoS ONE 2012, 7, e35008.
  149. Atkinson, K.J.; Rao, R.K. Role of protein tyrosine phosphorylation in acetaldehyde-induced disruption of epithelial tight junctions. Am. J. Physiol. Gastrointest. Liver Physiol. 2001, 280, G1280–G1288.
  150. Rao, R.K.; Baker, R.D.; Baker, S.S.; Gupta, A.; Holycross, M. Oxidant-induced disruption of intestinal epithelial barrier function: Role of protein tyrosine phosphorylation. Am. J. Physiol. 1997, 273, G812–G823.
  151. Rao, R.K.; Basuroy, S.; Rao, V.U.; Karnaky, K.J., Jr.; Gupta, A. Tyrosine phosphorylation and dissociation of occludin-ZO-1 and E-cadherin-beta-catenin complexes from the cytoskeleton by oxidative stress. Biochem. J. 2002, 368, 471–481.
  152. Sheth, P.; Seth, A.; Atkinson, K.J.; Gheyi, T.; Kale, G.; Giorgianni, F.; Desiderio, D.M.; Li, C.; Naren, A.; Rao, R. Acetaldehyde dissociates the PTP1B-E-cadherin-beta-catenin complex in Caco-2 cell monolayers by a phosphorylation-dependent mechanism. Biochem. J. 2007, 402, 291–300.
  153. Banan, A.; Choudhary, S.; Zhang, Y.; Fields, J.Z.; Keshavarzian, A. Ethanol-induced barrier dysfunction and its prevention by growth factors in human intestinal monolayers: Evidence for oxidative and cytoskeletal mechanisms. J. Pharmacol. Exp. Ther. 1999, 291, 1075–1085.
  154. Tang, Y.; Forsyth, C.B.; Farhadi, A.; Rangan, J.; Jakate, S.; Shaikh, M.; Banan, A.; Fields, J.Z.; Keshavarzian, A. Nitric oxide-mediated intestinal injury is required for alcohol-induced gut leakiness and liver damage. Alcohol. Clin. Exp. Res. 2009, 33, 1220–1230.
  155. Fukui, H. Role of Gut Dysbiosis in Liver Diseases: What Have We Learned So Far? Diseases 2019, 7, 58.
  156. Geirnaert, A.; Calatayud, M.; Grootaert, C.; Laukens, D.; Devriese, S.; Smagghe, G.; De Vos, M.; Boon, N.; Van de Wiele, T. Butyrate-producing bacteria supplemented in vitro to Crohn’s disease patient microbiota increased butyrate production and enhanced intestinal epithelial barrier integrity. Sci. Rep. 2017, 7, 11450.
  157. Bjørkhaug, S.T.; Aanes, H.; Neupane, S.P.; Bramness, J.G.; Malvik, S.; Henriksen, C.; Skar, V.; Medhus, A.W.; Valeur, J. Characterization of gut microbiota composition and functions in patients with chronic alcohol overconsumption. Gut Microbes 2019, 10, 663–675.
  158. Cresci, G.A.; Bush, K.; Nagy, L.E. Tributyrin supplementation protects mice from acute ethanol-induced gut injury. Alcohol. Clin. Exp. Res. 2014, 38, 1489–1501.
  159. Cresci, G.A.; Glueck, B.; McMullen, M.R.; Xin, W.; Allende, D.; Nagy, L.E. Prophylactic tributyrin treatment mitigates chronic-binge ethanol-induced intestinal barrier and liver injury. J. Gastroenterol. Hepatol. 2017, 32, 1587–1597.
  160. Mutlu, E.A.; Gillevet, P.M.; Rangwala, H.; Sikaroodi, M.; Naqvi, A.; Engen, P.A.; Kwasny, M.; Lau, C.K.; Keshavarzian, A. Colonic microbiome is altered in alcoholism. Am. J. Physiol. Gastrointest. Liver Physiol. 2012, 302, G966–G978.
  161. Yan, A.W.; Fouts, D.E.; Brandl, J.; Stärkel, P.; Torralba, M.; Schott, E.; Tsukamoto, H.; Nelson, K.E.; Brenner, D.A.; Schnabl, B. Enteric dysbiosis associated with a mouse model of alcoholic liver disease. Hepatology 2011, 53, 96–105.
  162. Bode, J.C.; Bode, C.; Heidelbach, R.; Dürr, H.K.; Martini, G.A. Jejunal microflora in patients with chronic alcohol abuse. Hepatogastroenterology 1984, 31, 30–34.
  163. Casafont Morencos, F.; de las Heras Castaño, G.; Martín Ramos, L.; López Arias, M.J.; Ledesma, F.; Pons Romero, F. Small bowel bacterial overgrowth in patients with alcoholic cirrhosis. Dig. Dis. Sci. 1996, 41, 552–556.
  164. Nanji, A.A.; Jokelainen, K.; Fotouhinia, M.; Rahemtulla, A.; Thomas, P.; Tipoe, G.L.; Su, G.L.; Dannenberg, A.J. Increased severity of alcoholic liver injury in female rats: Role of oxidative stress, endotoxin, and chemokines. Am. J. Physiol. Gastrointest. Liver Physiol. 2001, 281, G1348–G1356.
  165. Mathurin, P.; Deng, Q.G.; Keshavarzian, A.; Choudhary, S.; Holmes, E.W.; Tsukamoto, H. Exacerbation of alcoholic liver injury by enteral endotoxin in rats. Hepatology 2000, 32, 1008–1017.
  166. Purohit, V.; Bode, J.C.; Bode, C.; Brenner, D.A.; Choudhry, M.A.; Hamilton, F.; Kang, Y.J.; Keshavarzian, A.; Rao, R.; Sartor, R.B.; et al. Alcohol, intestinal bacterial growth, intestinal permeability to endotoxin, and medical consequences: Summary of a symposium. Alcohol 2008, 42, 349–361.
  167. Albillos, A.; de Gottardi, A.; Rescigno, M. The gut-liver axis in liver disease: Pathophysiological basis for therapy. J. Hepatol. 2020, 72, 558–577.
  168. Ju, C.; Mandrekar, P. Macrophages and Alcohol-Related Liver Inflammation. Alcohol Res. 2015, 37, 251–262.
  169. Petrasek, J.; Iracheta-Vellve, A.; Saha, B.; Satishchandran, A.; Kodys, K.; Fitzgerald, K.A.; Kurt-Jones, E.A.; Szabo, G. Metabolic danger signals, uric acid and ATP, mediate inflammatory cross-talk between hepatocytes and immune cells in alcoholic liver disease. J. Leukoc. Biol. 2015, 98, 249–256.
  170. Iracheta-Vellve, A.; Petrasek, J.; Satishchandran, A.; Gyongyosi, B.; Saha, B.; Kodys, K.; Fitzgerald, K.A.; Kurt-Jones, E.A.; Szabo, G. Inhibition of sterile danger signals, uric acid and ATP, prevents inflammasome activation and protects from alcoholic steatohepatitis in mice. J. Hepatol. 2015, 63, 1147–1155.
  171. Schroder, K.; Tschopp, J. The inflammasomes. Cell 2010, 140, 821–832.
  172. Petrasek, J.; Bala, S.; Csak, T.; Lippai, D.; Kodys, K.; Menashy, V.; Barrieau, M.; Min, S.Y.; Kurt-Jones, E.A.; Szabo, G. IL-1 receptor antagonist ameliorates inflammasome-dependent alcoholic steatohepatitis in mice. J. Clin. Investig. 2012, 122, 3476–3489.
  173. Ginhoux, F.; Jung, S. Monocytes and macrophages: Developmental pathways and tissue homeostasis. Nat. Rev. Immunol. 2014, 14, 392–404.
  174. Larson, S.R.; Atif, S.M.; Gibbings, S.L.; Thomas, S.M.; Prabagar, M.G.; Danhorn, T.; Leach, S.M.; Henson, P.M.; Jakubzick, C.V. Ly6C+ monocyte efferocytosis and cross-presentation of cell-associated antigens. Cell Death Differ. 2016, 23, 997–1003.
  175. Dou, L.; Shi, X.; He, X.; Gao, Y. Macrophage Phenotype and Function in Liver Disorder. Front. Immunol. 2019, 10, 3112.
  176. Badwey, J.A.; Karnovsky, M.L. Active oxygen species and the functions of phagocytic leukocytes. Annu. Rev. Biochem. 1980, 49, 695–726.
  177. Kono, H.; Rusyn, I.; Yin, M.; Gäbele, E.; Yamashina, S.; Dikalova, A.; Kadiiska, M.B.; Connor, H.D.; Mason, R.P.; Segal, B.H.; et al. NADPH oxidase-derived free radicals are key oxidants in alcohol-induced liver disease. J. Clin. Investig. 2000, 106, 867–872.
  178. Thakur, V.; Pritchard, M.T.; McMullen, M.R.; Wang, Q.; Nagy, L.E. Chronic ethanol feeding increases activation of NADPH oxidase by lipopolysaccharide in rat Kupffer cells: Role of increased reactive oxygen in LPS-stimulated ERK1/2 activation and TNF-alpha production. J. Leukoc. Biol. 2006, 79, 1348–1356.
  179. Liaskou, E.; Klemsdal Henriksen, E.K.; Holm, K.; Kaveh, F.; Hamm, D.; Fear, J.; Viken, M.K.; Hov, J.R.; Melum, E.; Robins, H.; et al. High-throughput T-cell receptor sequencing across chronic liver diseases reveals distinct disease-associated repertoires. Hepatology 2016, 63, 1608–1619.
  180. Gao, B.; Ahmad, M.F.; Nagy, L.E.; Tsukamoto, H. Inflammatory pathways in alcoholic steatohepatitis. J. Hepatol. 2019, 70, 249–259.
  181. Chedid, A.; Mendenhall, C.L.; Moritz, T.E.; French, S.W.; Chen, T.S.; Morgan, T.R.; Roselle, G.A.; Nemchausky, B.A.; Tamburro, C.H.; Schiff, E.R.; et al. Cell-mediated hepatic injury in alcoholic liver disease. Veterans Affairs Cooperative Study Group 275. Gastroenterology 1993, 105, 254–266.
  182. Lin, F.; Taylor, N.J.; Su, H.; Huang, X.; Hussain, M.J.; Abeles, R.D.; Blackmore, L.; Zhou, Y.; Ikbal, M.M.; Heaton, N.; et al. Alcohol dehydrogenase-specific T-cell responses are associated with alcohol consumption in patients with alcohol-related cirrhosis. Hepatology 2013, 58, 314–324.
  183. Markwick, L.J.; Riva, A.; Ryan, J.M.; Cooksley, H.; Palma, E.; Tranah, T.H.; Manakkat Vijay, G.K.; Vergis, N.; Thursz, M.; Evans, A.; et al. Blockade of PD1 and TIM3 restores innate and adaptive immunity in patients with acute alcoholic hepatitis. Gastroenterology 2015, 148, 590–602.
  184. Støy, S.; Sandahl, T.D.; Dige, A.K.; Agnholt, J.; Rasmussen, T.K.; Grønbæk, H.; Deleuran, B.; Vilstrup, H. Highest frequencies of interleukin-22-producing T helper cells in alcoholic hepatitis patients with a favourable short-term course. PLoS ONE 2013, 8, e55101.
  185. Dudakov, J.A.; Hanash, A.M.; van den Brink, M.R. Interleukin-22: Immunobiology and pathology. Annu. Rev. Immunol. 2015, 33, 747–785.
  186. Rutz, S.; Eidenschenk, C.; Ouyang, W. IL-22, not simply a Th17 cytokine. Immunol. Rev. 2013, 252, 116–132.
  187. Kumar, V. NKT-cell subsets: Promoters and protectors in inflammatory liver disease. J. Hepatol. 2013, 59, 618–620.
  188. Maricic, I.; Sheng, H.; Marrero, I.; Seki, E.; Kisseleva, T.; Chaturvedi, S.; Molle, N.; Mathews, S.A.; Gao, B.; Kumar, V. Inhibition of type I natural killer T cells by retinoids or following sulfatide-mediated activation of type II natural killer T cells attenuates alcoholic liver disease in mice. Hepatology 2015, 61, 1357–1369.
  189. Xiao, X.; Cai, J. Mucosal-Associated Invariant T Cells: New Insights into Antigen Recognition and Activation. Front. Immunol. 2017, 8, 1540.
  190. Kurioka, A.; Jahun, A.S.; Hannaway, R.F.; Walker, L.J.; Fergusson, J.R.; Sverremark-Ekström, E.; Corbett, A.J.; Ussher, J.E.; Willberg, C.B.; Klenerman, P. Shared and Distinct Phenotypes and Functions of Human CD161++ Vα7.2+ T Cell Subsets. Front. Immunol. 2017, 8, 1031.
  191. Kurioka, A.; Walker, L.J.; Klenerman, P.; Willberg, C.B. MAIT cells: New guardians of the liver. Clin. Transl. Immunol. 2016, 5, e98.
  192. Li, Y.; Huang, B.; Jiang, X.; Chen, W.; Zhang, J.; Wei, Y.; Chen, Y.; Lian, M.; Bian, Z.; Miao, Q.; et al. Mucosal-Associated Invariant T Cells Improve Nonalcoholic Fatty Liver Disease Through Regulating Macrophage Polarization. Front. Immunol. 2018, 9, 1994.
  193. Klenerman, P.; Hinks, T.S.C.; Ussher, J.E. Biological functions of MAIT cells in tissues. Mol. Immunol. 2021, 130, 154–158.
  194. Franciszkiewicz, K.; Salou, M.; Legoux, F.; Zhou, Q.; Cui, Y.; Bessoles, S.; Lantz, O. MHC class I-related molecule, MR1, and mucosal-associated invariant T cells. Immunol. Rev. 2016, 272, 120–138.
  195. Riva, A.; Patel, V.; Kurioka, A.; Jeffery, H.C.; Wright, G.; Tarff, S.; Shawcross, D.; Ryan, J.M.; Evans, A.; Azarian, S.; et al. Mucosa-associated invariant T cells link intestinal immunity with antibacterial immune defects in alcoholic liver disease. Gut 2018, 67, 918–930.
  196. Dolganiuc, A.; Petrasek, J.; Kodys, K.; Catalano, D.; Mandrekar, P.; Velayudham, A.; Szabo, G. MicroRNA expression profile in Lieber-DeCarli diet-induced alcoholic and methionine choline deficient diet-induced nonalcoholic steatohepatitis models in mice. Alcohol. Clin. Exp. Res. 2009, 33, 1704–1710.
  197. Blaya, D.; Coll, M.; Rodrigo-Torres, D.; Vila-Casadesus, M.; Altamirano, J.; Llopis, M.; Graupera, I.; Perea, L.; Aguilar-Bravo, B.; Diaz, A.; et al. Integrative microRNA profiling in alcoholic hepatitis reveals a role for microRNA-182 in liver injury and inflammation. Gut 2016, 65, 1535–1545.
  198. Hwang, S.; Yang, Y.M. Exosomal microRNAs as diagnostic and therapeutic biomarkers in non-malignant liver diseases. Arch. Pharm. Res. 2021, 44, 574–587.
  199. O’Brien, J.; Hayder, H.; Zayed, Y.; Peng, C. Overview of MicroRNA Biogenesis, Mechanisms of Actions, and Circulation. Front. Endocrinol. 2018, 9, 402.
  200. Chen, X.; Liang, H.; Zhang, J.; Zen, K.; Zhang, C.Y. microRNAs are ligands of Toll-like receptors. RNA 2013, 19, 737–739.
  201. Massey, V.L.; Qin, L.; Cabezas, J.; Caballeria, J.; Sancho-Bru, P.; Bataller, R.; Crews, F.T. TLR7-let-7 Signaling Contributes to Ethanol-Induced Hepatic Inflammatory Response in Mice and in Alcoholic Hepatitis. Alcohol. Clin. Exp. Res. 2018, 42, 2107–2122.
  202. Fan, X.; Wu, J.; Poulsen, K.L.; Kim, A.; Wu, X.; Huang, E.; Miyata, T.; Sanz-Garcia, C.; Nagy, L.E. Identification of a MicroRNA-E3 Ubiquitin Ligase Regulatory Network for Hepatocyte Death in Alcohol-Associated Hepatitis. Hepatol. Commun. 2021, 5, 830–845.
  203. Bala, S.; Petrasek, J.; Mundkur, S.; Catalano, D.; Levin, I.; Ward, J.; Alao, H.; Kodys, K.; Szabo, G. Circulating microRNAs in exosomes indicate hepatocyte injury and inflammation in alcoholic, drug-induced, and inflammatory liver diseases. Hepatology 2012, 56, 1946–1957.
  204. Babuta, M.; Furi, I.; Bala, S.; Bukong, T.N.; Lowe, P.; Catalano, D.; Calenda, C.; Kodys, K.; Szabo, G. Dysregulated Autophagy and Lysosome Function Are Linked to Exosome Production by Micro-RNA 155 in Alcoholic Liver Disease. Hepatology 2019, 70, 2123–2141.
  205. Wang, X.; He, Y.; Mackowiak, B.; Gao, B. MicroRNAs as regulators, biomarkers and therapeutic targets in liver diseases. Gut 2021, 70, 784–795.
  206. Bala, S.; Csak, T.; Saha, B.; Zatsiorsky, J.; Kodys, K.; Catalano, D.; Satishchandran, A.; Szabo, G. The pro-inflammatory effects of miR-155 promote liver fibrosis and alcohol-induced steatohepatitis. J. Hepatol. 2016, 64, 1378–1387.
  207. Wang, W.; Zhong, G.Z.; Long, K.B.; Liu, Y.; Liu, Y.Q.; Xu, A.L. Silencing miR-181b-5p upregulates PIAS1 to repress oxidative stress and inflammatory response in rats with alcoholic fatty liver disease through inhibiting PRMT1. Int. Immunopharmacol. 2021, 101, 108151.
  208. Dong, X.; Liu, H.; Chen, F.; Li, D.; Zhao, Y. MiR-214 promotes the alcohol-induced oxidative stress via down-regulation of glutathione reductase and cytochrome P450 oxidoreductase in liver cells. Alcohol. Clin. Exp. Res. 2014, 38, 68–77.
  209. Kumar, S.; Rani, R.; Karns, R.; Gandhi, C.R. Augmenter of liver regeneration protein deficiency promotes hepatic steatosis by inducing oxidative stress and microRNA-540 expression. FASEB J. 2019, 33, 3825–3840.
  210. Luo, J.; Hou, Y.; Ma, W.; Xie, M.; Jin, Y.; Xu, L.; Li, C.; Wang, Y.; Chen, J.; Chen, W.; et al. A novel mechanism underlying alcohol dehydrogenase expression: Hsa-miR-148a-3p promotes ADH4 expression via an AGO1-dependent manner in control and ethanol-exposed hepatic cells. Biochem. Pharmacol. 2021, 189, 114458.
  211. Luo, J.; Xie, M.; Hou, Y.; Ma, W.; Jin, Y.; Chen, J.; Li, C.; Zhao, K.; Chen, N.; Xu, L.; et al. A novel epigenetic mechanism unravels hsa-miR-148a-3p-mediated CYP2B6 downregulation in alcoholic hepatitis disease. Biochem. Pharmacol. 2021, 188, 114582.
  212. Fu, R.; Zhou, J.; Wang, R.; Sun, R.; Feng, D.; Wang, Z.; Zhao, Y.; Lv, L.; Tian, X.; Yao, J. Protocatechuic Acid-Mediated miR-219a-5p Activation Inhibits the p66shc Oxidant Pathway to Alleviate Alcoholic Liver Injury. Oxid. Med. Cell. Longev. 2019, 2019, 3527809.
  213. Khoruts, A.; Stahnke, L.; McClain, C.J.; Logan, G.; Allen, J.I. Circulating tumor necrosis factor, interleukin-1 and interleukin-6 concentrations in chronic alcoholic patients. Hepatology 1991, 13, 267–276.
  214. Ren, R.; He, Y.; Ding, D.; Cui, A.; Bao, H.; Ma, J.; Hou, X.; Li, Y.; Feng, D.; Li, X.; et al. Aging exaggerates acute-on-chronic alcohol-induced liver injury in mice and humans by inhibiting neutrophilic sirtuin 1-C/EBPalpha-miRNA-223 axis. Hepatology 2021.
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