Metabolic dysfunction associated steatohepatitis
Metabolic dysfunction associated steatohepatitis
Overview
Metabolic dysfunction-associated steatohepatitis (MASH) is a progressive inflammatory liver disease and the advanced form of metabolic dysfunction-associated steatotic liver disease (MASLD), which itself affects approximately one-third of the global population. MASH is histologically defined by the coexistence of hepatic steatosis, persistent lobular inflammation, hepatocyte ballooning degeneration, and varying degrees of fibrotic remodeling. It represents a critical transition point in the natural history of fatty liver disease: while steatosis alone is largely reversible, the inflammatory and fibrogenic cascade in MASH substantially elevates the risk of progression to cirrhosis, hepatocellular carcinoma (HCC), and liver-related mortality. Approximately 20% of individuals with MASLD progress to MASH, and among those with obesity, 12–40% may advance to MASH within 8–13 years.
The pathogenesis of MASH is multifactorial, driven by a complex interplay of metabolic disturbances, lipotoxicity, oxidative stress, immune cell dysregulation, and gut-liver axis dysfunction. Key molecular mechanisms involve proinflammatory cytokine signaling, activation of hepatic stellate cells (HSCs), macrophage polarization, ferroptosis, mitochondrial dysfunction, and cGAS-STING pathway activation. The disease is strongly associated with components of the metabolic syndrome—including obesity, type 2 diabetes, and hyperinsulinemia—and shares bidirectional relationships with cardiovascular disease and sarcopenia. Formerly designated non-alcoholic steatohepatitis (NASH), the renaming to MASH reflects a consensus shift toward emphasizing its metabolic etiology and distinguishing it from alcohol-related liver injury.
Focus of Latest Publications
MASH has emerged as one of the most intensely investigated areas in hepatology, with recent publications spanning disease mechanisms, biomarker development, therapeutic targets, and clinical trial design.
Fibrosis and Disease Progression
A central focus of recent research is the fibroinflammatory cascade that drives MASH toward end-stage liver disease. Studies have identified thrombospondin-1 (THBS1), derived from both fibroblasts and macrophages, as an orchestrator of the fibroinflammatory niche in MASH-induced fibrosis (PMID: 42266095). The Selplg-Sell-YAP axis has been implicated in macrophage-neutrophil crosstalk that drives NETosis and MASH-associated liver fibrosis (PMID: 42274998). Palmitoylation-mediated exosomal trafficking of the nuclear protein NAT10 has been shown to potentiate liver fibrosis in MASH, while a separate study demonstrated that depletion of NAT10 specifically in T cells attenuates MASH in mice (PMIDs: 42103688, 42275589). Liver fibrosis is consistently highlighted as the principal histological determinant of mortality in MASH, underscoring the urgency of identifying anti-fibrotic targets.
Immune and Inflammatory Mechanisms
macrophage biology features prominently across multiple studies. macrophage-driven inflammation is recognized as a key pathogenic factor, and integrated multi-omics analyses have characterized dynamic changes in macrophage composition during progression from steatosis to steatohepatitis (PMID: 42151416). Soft fibrin matrix has been shown to instruct macrophage M2 polarization via FABP4-mediated enhancement of fatty acid β-oxidation, thereby alleviating MASH (PMID: 42240847). The IGFBP7 pathway in liver macrophages has been implicated as a mechanism by which prior obesity history exacerbates fibrosis (PMID: 42263885). Death receptor 5 (DR5), a mediator of hepatocyte apoptosis involving CASP8, also plays a pivotal role in MASH inflammation (PMID: 42087709). anti-inflammatory cytokines and proinflammatory cytokine networks—including growth factors TGF-β1—are repeatedly referenced as central mediators of the hepatic injury response.
Gut Microbiota and Metabolic Axes
The gut-liver axis is emerging as a critical determinant of MASH pathogenesis. Dysbiosis has been identified as an important exacerbating factor via the gut-liver axis (PMID: 42236578), and Turicibacter sanguinis has been proposed as a candidate gut microbial pathobiont promoting MASH (PMID: 42148776). Gut microbes have been shown to mediate the synergistic effects of dietary cholesterol and saturated fat in driving fibrosing MASH (PMID: 42108649). Clostridium perfringens-derived ammonia has been found to exacerbate MASH, an effect attenuated by the tripeptide DT-109 (PMID: 42118590). Several traditional Chinese medicine formulas—including Xiayuxue decoction, Yanxiao Di'naer decoction, and Banxia Baizhu Tianma Decoction—have been studied in MASH models, with observed effects on gut microbiota regulation, bile acid metabolism, and m6A modification (PMIDs: 41797191, 41796617, 41831735). Bile acid profiling has been instrumental in characterizing these microbiome-hepatic interactions.
Molecular Targets and Therapeutic Development
The therapeutic landscape for MASH is rapidly evolving. Resmetirom and semaglutide are currently the only clinically approved treatments, with GLP-1 receptor agonists emerging as particularly promising therapeutic candidates (PMID: 41973550, 42048716). Ongoing investigations target a wide range of molecular pathways: PPAR α/δ/γ agonists (pemafibrate, seladelpar, pioglitazone), FXR agonists, ATP-citrate lyase (ACLY) inhibitors, and mTOR inhibition with vistusertib (PMIDs: 41922122, 42048716, 42189199). The PPAR δ agonist DN203316 has been shown to suppress ferroptotic signaling and fibrogenesis in MASH (PMID: 42249087), and ferroptosis—linked to Prostaglandin-endoperoxide synthase 2 and B-cell lymphoma 2 signaling—is increasingly recognized as a pathogenic mechanism. Lactylation of TNFRSF25 by lysine acetyltransferase 6B has been identified as aggravating ferroptosis in MASH (PMID: 42225083). The SIRT3-DsbA-L-TFAM axis has been shown to restrain cGAS-driven MASH via mitochondrial protection in male mice (PMID: 42082480), while blocking MOXD1-derived ACOX1 peroxisome trafficking has been demonstrated to suppress MASH (PMID: 42167911). Inhibition of non-canonical mTORC1 signaling by byakangelicin and disruption of ox-LDL/HSP90-mediated NLRP3 stability represent additional mechanistic avenues (PMIDs: 42152469, 42183856). Alpha 2A adrenergic receptor (ADRA2a) antagonism has been shown to reduce fibrosis, inflammation, and portal hypertension in experimental MASH and cirrhotic-rat models (PMID: 42264035). matrix metalloproteinase-9, MMP2, and Galectin 3 are among the extracellular matrix remodeling proteins noted in related mechanistic contexts.
Biomarkers and Diagnostics
Non-invasive diagnostics represent a major unmet need. Thrombospondin-2 (THBS2) has been validated as a performant biomarker for at-risk MASH and advanced fibrosis in a large multicenter European cohort (PMID: 40738743). Liver CT-based composite biomarkers have demonstrated ability to identify MASH and steatosis grade in patients with obesity prior to bariatric surgery (PMID: 42135651). Profiling of extracellular vesicles from primary hepatocytes, organoids, and MASH patient samples has identified cell injury-specific signatures as non-invasive diagnostic alternatives to biopsy (PMID: 42236744). The ELF (Enhanced Liver Fibrosis) test has been evaluated with multi-threshold analysis for prognostication of disease progression and regression (PMID: 42043861), and hepatokines Lipocalin 2 and osteopontin have been identified as drivers of muscle atrophy in MASH, highlighting the sarcope-MASH bidirectional relationship (PMID: 42270040). Lower prolactin levels have been associated with histological severity of MASLD, including MASH (PMID: 42265657). The receptor for advanced glycation end products (RAGE) has been studied in relation to genetic polymorphisms and MASLD/MASH susceptibility (PMID: 41908674).
Clinical Practice and Epidemiology
Evidence-based clinical practice guidelines for MASLD/MASH published in 2026 (jointly by the Japan Society of Hepatology) affirm that liver biopsy remains essential for definitive diagnosis of at-risk MASH, assessment of inflammatory activity, and differentiation from other chronic liver diseases (PMIDs: 42118685, 42120590). High prevalence of MASH with significant fibrosis has been documented in primary care and endocrinology clinics, reinforcing the need for systematic screening in metabolic risk populations (PMID: 42056678). A prospective, multicenter, randomized, double-blind, placebo-controlled trial (the chiglitazar combination therapy study) is underway targeting MASH associated with type 2 diabetes (PMID: 42150836). Breastfeeding in infancy has been identified as conferring sex-specific, long-term protection against MASH and adverse liver outcomes in adulthood (PMID: 42116208). The mitiperstat study expands MASH's therapeutic connections to the myeloperoxidase inhibitor class, also investigated for heart failure and COPD (PMID: 42101107).