An Experimental DUAL Model of Advanced Liver Damage

Individuals exhibiting an intermediate alcohol drinking pattern in conjunction with signs of metabolic risk present clinical features of both alcohol-associated and metabolic-associated fatty liver diseases. However, such combination remains an unexplored area of great interest, given the increasing number of patients affected. In the present study, we aimed to develop a preclinical DUAL (alcohol-associated liver disease plus metabolic-associated fatty liver disease) model in mice. C57BL/6 mice received 10% vol/vol alcohol in sweetened drinking water in combination with a Western diet for 10, 23, and 52 weeks (DUAL model). Animals fed with DUAL diet elicited a significant increase in body mass index accompanied by a pronounced hypertrophy of adipocytes, hypercholesterolemia, and hyperglycemia. Significant liver damage was characterized by elevated plasma alanine aminotransferase and lactate dehydrogenase levels, extensive hepatomegaly, hepatocyte enlargement, ballooning, steatosis, hepatic cell death, and compensatory proliferation. Notably, DUAL animals developed lobular inflammation and advanced hepatic fibrosis. Sequentially, bridging cirrhotic changes were frequently observed after 12 months. Bulk RNA-sequencing analysis indicated that dysregulated molecular pathways in DUAL mice were similar to those of patients with steatohepatitis. Conclusion: Our DUAL model is characterized by obesity, glucose intolerance, liver damage, prominent steatohepatitis and fibrosis, as well as inflammation and fibrosis in white adipose tissue. Altogether, the DUAL model mimics all histological, metabolic, and transcriptomic gene signatures of human advanced steatohepatitis, and therefore serves as a preclinical tool for the development of therapeutic targets.

Oxidative Stress in Drug-Induced Liver Injury (DILI): From Mechanisms to Biomarkers for Use in Clinical Practice

Idiosyncratic drug-induced liver injury (DILI) is a type of hepatic injury caused by an uncommon drug adverse reaction that can develop to conditions spanning from asymptomatic liver laboratory abnormalities to acute liver failure (ALF) and death. The cellular and molecular mechanisms involved in DILI are poorly understood. Hepatocyte damage can be caused by the metabolic activation of chemically active intermediate metabolites that covalently bind to macromolecules (e.g., proteins, DNA), forming protein adducts-neoantigens-that lead to the generation of oxidative stress, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress, which can eventually lead to cell death. In parallel, damage-associated molecular patterns (DAMPs) stimulate the immune response, whereby inflammasomes play a pivotal role, and neoantigen presentation on specific human leukocyte antigen (HLA) molecules trigger the adaptive immune response. A wide array of antioxidant mechanisms exists to counterbalance the effect of oxidants, including glutathione (GSH), superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX), which are pivotal in detoxification. These get compromised during DILI, triggering an imbalance between oxidants and antioxidants defense systems, generating oxidative stress. As a result of exacerbated oxidative stress, several danger signals, including mitochondrial damage, cell death, and inflammatory markers, and microRNAs (miRNAs) related to extracellular vesicles (EVs) have already been reported as mechanistic biomarkers. Here, the status quo and the future directions in DILI are thoroughly discussed, with a special focus on the role of oxidative stress and the development of new biomarkers.

Intestinal Epithelial Cell-Derived Extracellular Vesicles Modulate Hepatic Injury via the Gut-Liver Axis During Acute Alcohol Injury

Binge drinking, i.e., heavy episodic drinking in a short time, has recently become an alarming societal problem with negative health impact. However, the harmful effects of acute alcohol injury in the gut-liver axis remain elusive. Hence, we focused on the physiological and pathological changes and the underlying mechanisms of experimental binge drinking in the context of the gut-liver axis. Eight-week-old mice with a C57BL/6 background received a single dose (p.o.) of ethanol (EtOH) [6 g/kg b.w.] as a preclinical model of acute alcohol injury. Controls received a single dose of PBS. Mice were sacrificed 8 h later. In parallel, HepaRGs and Caco-2 cells, human cell lines of differentiated hepatocytes and intestinal epithelial cells intestinal epithelial cells (IECs), respectively, were challenged in the presence or absence of EtOH [0–100 mM]. Extracellular vesicles (EVs) isolated by ultracentrifugation from culture media of IECs were added to hepatocyte cell cultures. Increased intestinal permeability, loss of zonula occludens-1 (ZO-1) and MUCIN-2 expression, and alterations in microbiota—increased Lactobacillus and decreased Lachnospiraceae species—were found in the large intestine of mice exposed to EtOH. Increased TUNEL-positive cells, infiltration of CD11b-positive immune cells, pro-inflammatory cytokines (e.g., tlr4, tnf, il1β), and markers of lipid accumulation (Oil Red O, srbep1) were evident in livers of mice exposed to EtOH, particularly in females. In vitro experiments indicated that EVs released by IECs in response to ethanol exerted a deleterious effect on hepatocyte viability and lipid accumulation. Overall, our data identified a novel mechanism responsible for driving hepatic injury in the gut-liver axis, opening novel avenues for therapy.