Transcriptomic Profiling Reveals Inflammatory, Fibrotic, and Apoptotic Signatures in a Methionine-Choline-Deficient...

Metabolic dysfunction-associated steatohepatitis (MASH; formerly non-alcoholic steatohepatitis, NASH) is characterized by oxidative stress, inflammatory activation, hepatocellular injury, and progressive liver dysfunction. However, the global transcriptomic landscape underlying stress-induced hepatic injury remains incompletely understood. In this study, we employed a methionine-choline-deficient (MCD) diet-induced murine model to characterize the phenotypic and transcriptomic alterations associated with liver injury. Male C57BL/6J mice were fed either a control or MCD diet, and hepatotoxicity was assessed by survival analysis, body and liver weight measurements, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, histopathological examination, RNA sequencing, quantitative real-time PCR (qRT-PCR), and tumor necrosis factor-alpha (TNF-α) enzyme-linked immunosorbent assay (ELISA). MCD feeding markedly reduced survival and body weight while inducing hepatomegaly and significant elevations in serum ALT and AST, indicating severe hepatocellular injury. Histopathological analysis demonstrated hepatic steatosis, hepatocellular ballooning, and lobular inflammation without histological evidence of fibrosis. Transcriptomic profiling revealed extensive gene expression remodeling, characterized by activation of inflammatory pathways, enrichment of MAPK-related signaling, dysregulation of lipid metabolism, suppression of antioxidant defense systems, impairment of cytochrome P450-mediated detoxification, and upregulation of apoptosis-associated genes. qRT-PCR further validated the differential expression of representative genes involved in inflammatory signaling (Tlr4, Nfkb1, Nlrp3, and Casp1), MAPK signaling (Fos), xenobiotic metabolism (Cyp4f18), lipid metabolism (Apoa4 and Lpl), extracellular matrix remodeling (Mmp12), and oxidative stress responses (Sod1 and Gstp1). In addition, elevated serum TNF-α levels provided protein-level evidence supporting activation of the TLR4/NF-κB/TNF-α/NLRP3 inflammatory axis. Although fibrosis-associated transcriptional responses were detected, the absence of histological fibrosis suggests transcriptional priming of fibrogenic pathways rather than established fibrogenesis. Collectively, these findings provide a transcriptomic framework linking oxidative stress, impaired detoxification, inflammatory activation, and stress-responsive signaling to MCD-induced hepatic injury. The MCD model provides a valuable experimental platform for characterizing hepatic stress-response transcriptomes and for generating hypotheses that can subsequently be evaluated in environmentally relevant toxicological models. Nevertheless, caution should be exercised when extrapolating these findings to obesity-associated human MASLD, as the MCD model lacks key metabolic features of the human disease, including obesity and insulin resistance. Therefore, the present findings should be interpreted primarily as transcriptomic signatures of stress-induced hepatic injury rather than as a direct representation of the pathophysiological processes underlying human obesity-associated MASLD.