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).

Key Publications

• NEWJun Asia-Pacific perspectives on the steatotic liver disease (SLD) reclassification: balancing terminology, diagnostic criteria, and implementation. (Annals of hepatology, 2026, PMID 42315088): "The global transition from non-alcoholic fatty liver disease (NAFLD) to steatotic liver disease (SLD), encompassing metabolic dysfunction-associated steatotic liver disease (MASLD), metabolic dysfunction-associated steatohepatitis (MASH), and metabolic dysfunction-associated alcohol-related liver disease (Met-ALD), aims to improve pathophysiologic accuracy and reduce stigma."
• NEWJun A ROS-Responsive DNA Nanodevice for Targeted Cytosolic siRNA Delivery in Metabolic Dysfunction-Associated Steatohepatitis. (Journal of the American Chemical Society, 2026, PMID 42319126): "Metabolic dysfunction-associated steatohepatitis (MASH) arises from an intricate interplay of dysregulated metabolic, inflammatory, and fibrogenic pathways, necessitating coordinated therapeutic intervention that remains inadequately achieved by current treatments."
• NEWJun Incidence of Cirrhosis in Fibrotic Metabolic Dysfunction-Associated Steatohepatitis: A Meta-Analysis of Placebo Arms from Randomized Clinical Trials. (Digestive diseases and sciences, 2026, PMID 42315723): "Metabolic dysfunction-associated steatohepatitis (MASH) with stage F2-F3 fibrosis represents the main target population for emerging pharmacotherapies."
• Jun Refined liver MRI-derived cT1 thresholds capturing hepatic fat fraction enhance mortality risk prediction. (JHEP reports : innovation in hepatology, 2026, PMID 42309239): "Although a threshold of ≥800 ms has been proposed to identify individuals at risk of MASH with poor outcomes, it captures only a small proportion (∼5%) and may fail to account for risk below this level."
• Jun Labile iron starvation in embryonic Kupffer cells aggravates MASH via mitochondrial failure and macrophage dysfunction. (Cell death & disease, 2026, PMID 42310295): "Targeting emKC iron homeostasis could offer novel therapeutic strategies for MASLD/MASH."
• Jun Spatial transcriptome mapping identifies Ppara-Anxa2 cross-talk in microplastic-induced hepatotoxicity. (Science advances, 2026, PMID 42308314): "By performing combined bulk and spatial transcriptomic analyses, we observed that PE resulted in hepatic dysfunction in mice fed on standard or metabolic dysfunction-associated steatohepatitis (MASH)-inducing diets, driving both globally and spatially distinct transcriptional alterations, including a nuclear receptor (NR), Ppara."
• Jun Development of a short-term mouse model of early MASLD for non-invasive pathophysiological tracking via urinary metabolomics and micro-CT. (Life sciences, 2026, PMID 42302927): "Metabolic dysfunction-associated steatotic liver disease (MASLD) and its progressive form, metabolic dysfunction-associated steatohepatitis (MASH), are common chronic liver disorders linked to hepatocellular carcinoma."
• Jun Analysis of PNPLA3, TM6SF2 and GCKR gene polymorphisms in patients with metabolic dysfunction-associated steatohepatitis treated with probiotics ‒ An exploratory study. (Nutricion hospitalaria, 2026, PMID 42023869): "genetics significantly influences the development and progression of metabolic dysfunction-associated steatohepatitis (MASH)."
• Jun Discovery of a pyrimidine-based steroidal FXR agonist for the treatment of metabolic dysfunction-associated steatotic liver disease. (Bioorganic chemistry, 2026, PMID 41812427): "Farnesoid X receptor (FXR) plays a crucial role in regulating bile acid homeostasis and is implicated in the pathogenesis of metabolic dysfunction-associated steatohepatitis (MASH)."
• Jun Huanglian Wendan Decoction attenuates hepatic inflammation and lipogenesis via inhibition of the NF-κB/HDAC1/SREBP-1c axis. (Journal of ethnopharmacology, 2026, PMID 42276391): "Metabolic dysfunction-associated steatohepatitis (MASH) is characterized by hepatic steatosis accompanied by persistent inflammation and early fibrotic remodeling."