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Modulation of metabolic, inflammatory and fibrotic pathways by semaglutide in metabolic dysfunction-associated steatohepatitis.

Metabolic dysfunction-associated steatohepatitis (MASH) is a chronic liver disease strongly associated with cardiometabolic risk factors. Semaglutide, a glucagon-like peptide-1 receptor agonist, improves liver histology in MASH, but the underlying signals and pathways driving semaglutide-induced MASH resolution are not well understood. Here we show that, in two preclinical MASH models, semaglutide improved histological markers of fibrosis and inflammation and reduced hepatic expression of fibrosis-related and inflammation-related gene pathways. Aptamer-based proteomic analyses of serum samples from patients with MASH in a clinical trial identified 72 proteins significantly associated with MASH resolution and semaglutide treatment, with most related to metabolism and several implicated in fibrosis and inflammation. An independent real-world cohort verified the pathophysiological relevance of this signature, showing that the same 72 proteins are differentially expressed in patients with MASH relative to healthy individuals. Taken together, these data suggest that semaglutide may revert the circulating proteome associated with MASH to the proteomic pattern observed in healthy individuals.

Humans↗

Acyloxyacyl Hydrolase-Mediated Lipopolysaccharide Inactivation Limits Macrophage Endotoxin Tolerance and Promotes Inflammation and Fibrosis in Metabolic Dysfunction-Associated Steatohepatitis.

BACKGROUND & AIMS: Metabolic dysfunction-associated steatohepatitis, a chronic liver disease, is characterized by persistent low-grade inflammation, partially driven by gut-derived lipopolysaccharide. Although repeated lipopolysaccharide exposure can induce endotoxin tolerance in innate immune cells, its role in chronic liver diseases remains unclear. Acyloxyacyl hydrolase is an endogenous enzyme that inactivates lipopolysaccharide, potentially modulating this process. We aimed to investigate how acyloxyacyl hydrolase regulates endotoxin tolerance in Kupffer cells and how this affects hepatic inflammation and fibrosis during metabolic dysfunction-associated steatohepatitis progression. METHODS: Acyloxyacyl hydrolase-deficient mice and wild-type controls were subjected to multiple dietary metabolic dysfunction-associated steatohepatitis models. Inflammatory responses, fibrosis, and transcriptomic changes in liver tissues and isolated Kupffer cells were analyzed. Endotoxin tolerance was modulated through β-glucan administration or lipopolysaccharide preconditioning. Lipopolysaccharide bioactivity was assessed using Toll-like receptor 4-reporter cell assays. RESULTS: Lipopolysaccharide-preconditioned Kupffer cells exhibited reduced proinflammatory cytokine production and transcriptional suppression of inflammatory pathways, indicating tolerance. Despite slight elevation of plasma lipopolysaccharide levels in metabolic dysfunction-associated steatohepatitis, upregulation of hepatic acyloxyacyl hydrolase positively correlated with disease severity, suggesting enhanced lipopolysaccharide inactivation but impaired establishment of tolerance. In contrast, acyloxyacyl hydrolase-deficient Kupffer cells displayed reinforced endotoxin tolerance, leading to diminished hepatic inflammation and fibrosis. Reversal of tolerance using β-glucan reactivated inflammatory and fibrogenic responses in acyloxyacyl hydrolase-deficient mice, whereas tolerance induction by low-dose lipopolysaccharide preconditioning mitigated metabolic dysfunction-associated steatohepatitis pathology, supporting the protective role of macrophage tolerance in chronic liver injury. CONCLUSIONS: Endotoxin tolerance in Kupffer cells represents a protective mechanism against chronic liver inflammation and fibrosis. Acyloxyacyl hydrolase regulates this state by limiting bioactive lipopolysaccharide, thereby modulating the establishment of endotoxin tolerance and downstream inflammatory and fibrotic responses. Enhancing macrophage tolerance by utilizing lipopolysaccharide may offer a novel therapeutic avenue to control the progression of metabolic dysfunction-associated steatohepatitis.

AOAH↗

Incidence of Cirrhosis in Fibrotic Metabolic Dysfunction-Associated Steatohepatitis: A Meta-Analysis of Placebo Arms from Randomized Clinical Trials.

BACKGROUNDS AND AIMS: Metabolic dysfunction-associated steatohepatitis (MASH) with stage F2-F3 fibrosis represents the main target population for emerging pharmacotherapies. However, data on short-term progression to cirrhosis (F4) in this group remain limited. We aimed to evaluate the incidence of cirrhosis in placebo-treated patients with fibrotic MASH in randomized controlled trials (RCTs). METHODS: In this single-arm meta-analysis, we systematically searched PubMed and Cochrane Library from inception to December 13, 2024, for pharmacological Phase ≥ 2 RCTs reporting cirrhosis events (detected in liver biopsy or clinical signs) among patients with fibrotic MASH receiving placebo. Incidence rates were pooled using generalized linear mixed models with Clopper-Pearson confidence intervals (CIs). RESULTS: We identified a total of 11 RCTs, including 586 patients with fibrotic MASH. Total follow-up was 657.23 person-years (PYs), with 83 cirrhosis events reported. The pooled incidence rate was 13.09 per 100 PYs (95% CI 7.81 to 21.12, I2 = 75.6%, τ2 = 0.682). In subgroup analysis, the incidence of cirrhosis was 3.40 per 100 PYs in MASH F2 (95% CI 1.10 to 10.02, I2 = 0%, τ2 = 0) and 17.90 per 100 PYs (95% CI 10.63 to 28.55, I2 = 70.2%, τ2 = 0.561) in MASH F3, with significant differences between stages (p = 0.006). Sensitivity analyses showed consistent estimates. Most RCTs were judged to have a low risk of bias. CONCLUSIONS: This study provides stage-specific data on cirrhosis incidence in fibrotic MASH, highlighting the high short-term risk associated with MASH F3 in trial settings. These data may inform benchmarks to guide event expectations, enrichment strategies, sample size assumptions, and the interpretation of future MASH clinical trials.

Humans↗

Targeting microbial bile salt hydrolase reprograms bile acid metabolism and ameliorates metabolic dysfunction-associated steatohepatitis in mice.

Microbial bile salt hydrolase (BSH) plays a central role in shaping bile acid composition and gut-liver metabolic signaling, yet its therapeutic potential in metabolic dysfunction-associated steatohepatitis (MASH) remains incompletely defined. Here, we evaluated the efficacy of the non-absorbable BSH inhibitor GR-7 in a diet-induced mouse model of steatohepatitis using early and late intervention strategies with different dosing regimens. GR-7 reduced food intake and exerted stage- and dose-dependent therapeutic effects, with early intervention robustly suppressing hepatic fibrosis even at a low dose, whereas late-stage administration of high-dose GR-7 markedly reduced hepatic steatosis and inflammation, as evidenced by decreased liver weight, hepatic triglyceride and cholesterol levels, and plasma ALT. Although late intervention did not result in statistically significant histological reversal of fibrosis, a trend toward improvement was observed, together with suppression of fibrogenic gene expression, suggesting that prolonged treatment may further enhance antifibrotic efficacy. Mechanistically, GR-7 effectively inhibited microbial BSH activity in vivo, leading to reduced cecal unconjugated primary and secondary bile acids-including deoxycholic acid and lithocholic acid, which was associated with improved gut barrier integrity and reduced hepatic inflammation. In parallel, BSH inhibition reprogrammed hepatic bile acid metabolism toward activation of the alternative CYP27A1-mediated synthesis pathway, accompanied by reduced food intake, thereby contributing to reduced hepatic lipid accumulation. Furthermore, late-stage high-dose treatment selectively remodeled the hepatic immune landscape rather than fully restoring homeostasis, highlighting immune recalibration as a key component of therapeutic response. Together, these findings identify microbial BSH inhibition as a promising microbiome-targeted therapeutic strategy for MASH.

Animals↗

Targeting Microbial Bile Salt Hydrolase Reprograms Bile Acid Metabolism and Ameliorates Metabolic Dysfunction-Associated Steatohepatitis in Mice.

Microbial bile salt hydrolase (BSH) plays a central role in shaping bile acid composition and gut-liver metabolic signaling, yet its therapeutic potential in metabolic dysfunction-associated steatohepatitis (MASH) remains incompletely defined. Here, we evaluated the efficacy of the non-absorbable BSH inhibitor GR-7 in a diet induced mouse model of steatohepatitis using early and late intervention strategies with different dosing regimens. GR-7 reduced food intake and exerted stage- and dose-dependent therapeutic effects, with early intervention robustly suppressing hepatic fibrosis even at low dose, whereas late-stage administration of high-dose GR-7 markedly reduced hepatic steatosis and inflammation, as evidenced by decreased liver weight, hepatic triglyceride and cholesterol levels, and plasma ALT. Although late intervention did not result in statistically significant histological reversal of fibrosis, a trend toward improvement was observed, together with suppression of fibrogenic gene expression, suggesting that prolonged treatment may further enhance antifibrotic efficacy. Mechanistically, GR-7 effectively inhibited microbial BSH activity in vivo, leading to reduced cecal unconjugated primary and secondary bile acids-including deoxycholic acid and lithocholic acid, which was associated with improved gut barrier integrity and reduced hepatic inflammation. In parallel, BSH inhibition reprogrammed hepatic bile acid metabolism toward activation of the alternative CYP27A1-mediated synthesis pathway, accompanied by reduced food intake, thereby contributing to improved hepatic lipid accumulation. Furthermore, late-stage high-dose treatment selectively remodeled the hepatic immune landscape rather than fully restoring homeostasis, highlighting immune recalibration as a key component of therapeutic response. Together, these findings identify microbial BSH inhibition as a promising microbiome-targeted therapeutic strategy for MASH.

Gut microbiome↗

Genome-wide DNA methylation profiling during metabolic dysfunction-associated steatohepatitis-related hepatocarcinogenesis in patients in Japan and the United States.

This study aimed to compare ethnicity-related differences in DNA methylation profiles during metabolic dysfunction-associated steatohepatitis (MASH)-related hepatocarcinogenesis in patients from Japan and the United States (US). Genome-wide DNA methylation analysis using the Infinium assay was performed in 36, 148 and 36 samples of normal liver tissue (NLT), non-cancerous liver tissue showing MASH, and MASH-related hepatocellular carcinoma (HCC), respectively (220 samples in total), from the Japan and US cohorts. Principal component analysis revealed that MASH had a distinct DNA methylation profile differing from that of NLT, and that the MASH profiles in the two cohorts differed from each other. DNA methylation alterations of cancer-related genes in MASH were inherited by or strengthened in MASH-related HCC itself, resulting in expression alterations. DNA methylation alterations of FGFR2, FUT4, B3GNT5 and MOSC1 in the precancerous MASH stage were shared by the two cohorts, suggesting that such genes are commonly associated with MASH-related hepatocarcinogenesis. On the other hand, it was suggested that DNA methylation alterations of ZNF611 and SAMD10, and those of SHC1, are involved specifically in MASH-related hepatocarcinogenesis in the Japan and the US cohorts, respectively. These findings suggest that DNA methylation alterations, which may reflect race and lifestyle, are associated with MASH-related hepatocarcinogenesis.

Humans↗

Discovery of a MET -driven monogenic cause of steatotic liver disease.

BACKGROUND AND AIMS: Metabolic dysfunction-associated steatotic liver disease affects about a third of adults worldwide and is projected soon to be the leading cause of liver cirrhosis. It occurs when fat accumulates in hepatocytes and can progress to metabolic dysfunction-associated steatohepatitis, liver cirrhosis, and HCC. Metabolic dysfunction-associated steatotic liver disease pathogenesis is believed to involve a combination of genetic and environmental risk factors. Single nucleotide polymorphisms have been implicated, but non-syndromic monogenic causes are lacking. APPROACH AND RESULTS: We identified a novel genetic variant in a familial case of metabolic dysfunction-associated steatohepatitis and performed deep variant functional analysis, including protein modeling, dynamics, and cell-based assays to assess molecular mechanisms of dysfunction and altered cellular signaling. We analyzed exome sequencing data of 3904 individuals with steatotic liver disease (SLD) to identify additional cases and establish the link between specific gene variants and SLD diagnosis. We discovered and functionally validated the NM_000245.4:c.3505A>T; p.(Ile1169Phe) variant in the MET (mesenchymal-epithelial transition) kinase domain as a monogenic cause of SLD. Subsequently, we detected additional ultra-rare, previously uninterpreted, and likely deleterious variants in MET from screening sequencing data. Among individuals with confirmed SLD based on electronic record review, 1.1% (45/3904) had rare predicted deleterious MET variants. Eight of 45 (17.7%) individuals had predicted deleterious variants in the MET kinase domain confirmed to be functionally like the familial case variant. CONCLUSIONS: We report the first germline nonmalignant rare MET -driven disease, a monogenic form of SLD.

Adult↗

Clinical Trial: Phase 3 Trial of Resmetirom Versus Placebo in Metabolic Dysfunction-Associated Steatohepatitis-Reanalysis of Fibrosis Stage 2-3 Subset.

BACKGROUND: Resmetirom is an oral thyroid hormone receptor beta agonist clinically used to treat metabolic dysfunction-associated steatohepatitis (MASH) among adults with stage F2 or F3 fibrosis. AIMS: Because the pivotal, 52-week, randomized, controlled, phase 3 MAESTRO-NASH trial (once-daily oral resmetirom 80 or 100&#x2009;mg or placebo) included patients with F1, F2, or F3 fibrosis, we conducted a post hoc analysis aimed at assessing treatment response in the subset of patients with stages F2 and F3 fibrosis, consistent with the approved label population. METHODS: Co-primary end points were MASH resolution (hepatocellular ballooning score 0, lobular inflammation score &#x2264;&#x2009;1, and &#x2265;&#x2009;2-point nonalcoholic fatty liver disease activity score [NAS] reduction from baseline) with no fibrosis worsening, and &#x2265;&#x2009;1-stage fibrosis improvement with no NAS worsening at Week 52. RESULTS: Among 917 patients with F2 or F3 fibrosis, metabolic risk factor prevalence was high (hypertension, 78.0%; dyslipidemia, 71.1%; type 2 diabetes, 67.0%). MASH resolution was achieved by 25.7% in the 80-mg group, 29.9% in the 100-mg group, and 9.5% in the placebo group (p&#x2009;<&#x2009;0.0001 for both comparisons with placebo). Respective percentages with fibrosis improvement were 26.5%, 28.9%, and 17.3% (p&#x2009;<&#x2009;0.01 for both comparisons). From baseline to Week 24, low-density lipoprotein cholesterol decreased by 11.7% and 13.7% in the 80- and 100-mg resmetirom groups, respectively, and increased by 2.3% with placebo (p&#x2009;<&#x2009;0.0001 for both comparisons). No new safety signals emerged. CONCLUSION: Results among patients with F2 and F3 fibrosis were consistent with the primary MAESTRO-NASH analysis population, demonstrating efficacy and safety of resmetirom after 52&#x2009;weeks.

Humans↗

GLP-1 Receptor Agonist and GIP/GLP-1 Receptor Dual Agonist Therapeutics at the Intersection of Alcohol Use Disorder, Obesity, and Cardiometabolic Dysfunction.

The co-occurrence of metabolic dysfunction and heavy alcohol consumption contributes substantially to global morbidity, particularly through its impact on liver disease progression. Glucagon-like peptide-1 receptor (GLP1R) agonists and glucose-dependent insulinotropic polypeptide receptor (GIPR)/GLP1R dual agonists, currently approved for the treatment of diabetes and obesity and under investigation for metabolic dysfunction-associated steatohepatitis, are considered for repurposing to reduce alcohol consumption and stabilize metabolic health in heavy-drinking populations. This review summarizes existing evidence, highlights ongoing research, and outlines key unanswered questions regarding this therapeutic potential and the paradigm shift toward metabolic circuit-based interventions in addiction treatment. The dual-target GIPR/GLP1R approach could fill a critical gap for individuals struggling with both heavy alcohol consumption and metabolic dysfunction.

Alcohol use disorder↗

A refined MASH-HCC model identifies macrophage Gadd45b as a key orchestrator of inflammation-driven neoplastic progression.

Metabolic dysfunction-associated steatohepatitis (MASH) is emerging as a leading driver of hepatocellular carcinoma (HCC), yet the molecular mechanisms linking metabolic stress, chronic inflammation and tumorigenesis remain poorly understood. Here we established a metabolically relevant, time-efficient MASH-to-HCC model in C57BL/6N mice by combining a MASH diet with controlled CCl4 administration, enabling stepwise recapitulation of MASH-associated neoplastic progression. Using this model, we identified growth arrest and DNA damage 45b (Gadd45b) as a novel MASH-derived protumorigenic regulator selectively activated under metabolic stress. Integrated analyses of human bulk and single-cell transcriptomic datasets and mouse transcriptomic deconvolution revealed concordant macrophage remodeling and GADD45B/Gadd45b expression dynamics during MASH-to-HCC progression. Mechanistically, fatty acids and TNF&#x3b1; preferentially induced Gadd45b in macrophages, where it amplified TNF&#x3b1;-NF-&#x3ba;B signaling. Macrophage-derived inflammatory signals subsequently induced Gadd45b and NF-&#x3ba;B activation in hepatocytes, establishing a feed-forward inflammatory loop that promoted fibrogenic and partial EMT-like programs and tumor spheroid formation. Importantly, temporal profiling during spheroid formation and progression revealed transient induction of Gadd45b during early spheroid establishment, but not during later progression, indicating that Gadd45b-mediated inflammatory signaling primarily promotes tumor initiation rather than subsequent growth. Consistent with human data, Gadd45b expression increased with disease severity and positively correlated with inflammatory factors in the MASH-HCC model, whereas pharmacological inhibition attenuated the Gadd45b-inflammation signaling axis. Collectively, our findings establish macrophage Gadd45b as a key orchestrator linking metabolic stress, chronic inflammation, and neoplastic transformation during MASH-to-HCC progression. Our refined MASH-HCC model provides a robust platform for mechanistic studies and preclinical evaluation of inflammation-targeted therapies.

Journal Article↗

Immunopathogenic mechanisms and immunoregulatory therapies in MASLD.

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as nonalcoholic fatty liver disease (NAFLD), is the most prevalent chronic liver disease worldwide, with an estimated global prevalence of approximately 30%; however, effective pharmacotherapies are still limited due to its complex pathogenesis and etiology. Therefore, a more thorough understanding of disease pathogenesis is urgently needed. An increasing number of studies suggest that MASLD and its progressive form, metabolic dysfunction-associated steatohepatitis (MASH), are driven by chronic overnutrition, multiple genetic susceptibility factors, and pathogenic consequences, including hepatocyte damage and liver inflammation. Hepatic inflammation is the key event fueling the conversion from simple steatosis to steatohepatitis and fibrosis. Current therapies for MASH, including the recently approved thyroid hormone receptor-beta agonist resmetirom or the available incretin mimetics, mainly target metabolic injury to the liver but not inflammation directly. In this review, we provide an in-depth discussion of current data related to the immunological mechanisms of MASLD and summarize the effects of current and experimental therapies on immunoregulation in MASLD.

Humans↗

Immune microenvironment in hepatocellular carcinoma: from pathogenesis to immunotherapy.

Hepatocellular carcinoma (HCC) is an increasingly prevalent and deadly disease that is initiated by different etiological factors, such as alcohol-associated liver disease (ALD), metabolic dysfunction-associated steatohepatitis (MASH), viral hepatitis, and other hepatotoxic and hepatocarcinogenic agents. The tumor microenvironment (TME) of HCC is characterized by several different fibroblastic and immune cell types, all of which affect the initiation, progression and metastasis of this malignant cancer. This complex immune TME can be divided into an innate component that includes macrophages, neutrophils, dendritic cells, myeloid-derived suppressor cells, mucosal-associated invariant T cells, natural killer cells, natural killer T cells, and innate lymphoid cells, as well as an adaptive component that includes CD4+ T cells, CD8+ T cells, regulatory T cells, and B cells. In this review, we discuss the latest findings shedding light on the direct or indirect roles of these immune cells (and fibroblastic-like cells such as hepatic stellate cells) in the pathogenesis of HCC. Henceforth, further characterization of this heterogeneous TME is highly important for studying the progression of HCC and developing novel immunotherapeutic treatment options. In line with this, we also review novel groundbreaking experimental techniques and animal models aimed at specifically elucidating this complex TME and discuss emerging immune-based therapeutic strategies intended to treat HCC and predict the efficacy of these immunotherapies.

Humans↗

Loss of Mtarc1 Protects Against Steatotic Liver Disease in Mice.

BACKGROUND & AIMS: Metabolic dysfunction-associated steatotic liver disease (MASLD) spans from simple steatosis to metabolic dysfunction-associated steatohepatitis (MASH) and can progress to cirrhosis or hepatocellular carcinoma. Despite its prevalence, effective therapies are lacking. Recent genome-wide association studies identified a common missense variant (rs2642438) in the Mitochondrial Amidoxime Reducing Component 1 (MTARC1) gene that protects against liver cirrhosis without increasing cardiovascular disease risk. Biochemical and disease risk signatures associated with carriers of this missense variant also aligned with those of a known loss-of-function MTARC1 variant, suggesting mARC1 inhibition as a potential MASLD treatment. METHODS: To validate mARC1 loss-of-function as protective against MASLD, we generated Mtarc1 knockout (KO) mice and placed them on a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD). Effects of Mtarc1 KO on obesity and type 2 diabetes were explored using a high-fat diet. Hepatocytes from Mtarc1 KO mice were isolated to explore the molecular mechanisms by which Mtarc1 KO impacts lipid metabolism. RESULTS: Mtarc1 KO mice exhibited no vital growth or development defects. With a high-fat diet-induced obesity model, obese Mtarc1 KO mice exhibited reduced liver mass and lower cholesterol levels, with no effect on glucose homeostasis. In a CDAHFD-induced MASLD model, mARC1 deficiency significantly reduced liver steatosis, profibrosis, and inflammation. Untargeted metabolomics profiling further showed hepatic enrichment of phospholipids in Mtarc1 KO mice. Primary hepatocytes isolated from Mtarc1 KO mice exhibited reduced lipid droplet accumulation, decreased fatty acid uptake, and increased lipid secretion. CONCLUSIONS: These findings support mARC1 inhibition as a promising therapeutic strategy for MASLD/MASH.

Animals↗

AI-driven diagnostic and prognostic models for metabolic dysfunction-associated steatotic liver disease: insights from clinical, imaging, and multi-omics studies-a scoping review.

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD), is the most common chronic liver disease around the world, affecting 33.6% of the adult population (95% CI: 28.1%-39.5%; I 2&#x2009;=&#x2009;99.9%), or roughly one in three. The extent of the liver damage is variable, from simple steatosis to metabolic dysfunction-associated steatohepatitis (MASH, formerly NASH), cirrhosis and hepatocellular carcinoma (HCC). Early diagnosis is essential to prevent serious liver damage. Traditional diagnostic techniques such as liver biopsy, imaging, and biomarker testing are all invasive, costly, reduced sensitive to early-stage disease, and they also have variability among observers. Modern diagnostic and prognostic approaches based on the principles of Artificial Intelligence (AI) and specifically on machine learning (ML) and deep learning (DL) have enabled multimodal approaches integrating clinical, imaging and molecular data. This scoping review conducted per PRISMA-ScR guidelines, synthesizes findings from 73 studies (search window 2020-2026) across three dimensions: clinical data driven models, imaging-based classifiers (ultrasound, CT and MRI), and multi-omics (genomics, transcriptomics and proteomics) techniques. Moreover, emergence of models such as U-Net and LiverNet 2.x, classification models like DeepLiverNet and BiLSTM models, as well as transformer frameworks and the identification of biomarkers models are also described. This study also investigates challenges such as data heterogeneity, data interpretability, fairness and real-world clinical application. Finally, important areas of research opportunities and future directions are highlighted to present a developing clinically applicable, explainable and ethical AI solutions to manage MASLD.

MASLD↗

Hepatocyte-Specific Deficiency of Endoplasmic Reticulum-Associated Degradation Induces Coordinated Innate-Adaptive Immune Responses.

Hepatic inflammation is a defining feature of Metabolic Dysfunction-Associated Steatohepatitis (MASH), yet the specific contributions of individual immune cell populations and their reciprocal interactions remain incompletely understood. In this study, we combined flow cytometry with single-cell transcriptomic profiling to characterize the hepatic immune landscape in a novel model of spontaneous MASH caused by hepatocyte-specific deficiency of endoplasmic reticulum-associated degradation (ERAD). Hepatic ERAD deficiency led to the expansion of multiple immune cell populations in the liver, including CD8+ T cells, macrophages, monocytes, and dendritic cells, accompanied by extensive functional reprogramming of both innate and adaptive immune compartments. Myeloid cells exhibited enhanced phagocytic activity and increased antigen processing and presentation, whereas CD8+ T cells displayed elevated proliferation capacity, DNA repair activity and cytotoxicity. Notably, two functionally distinct triggering receptor expressed on myeloid cells 2 (TREM2)-expressing macrophage subsets emerged during the progression of ERAD deficiency-induced MASH. Depletion of CD8+ T cells increased monocyte infiltration and aggravated liver injury, suggesting that CD8+ T cells exert a previously unrecognized protective role by restraining monocyte recruitment. Collectively, these findings reveal highly coordinated interactions between innate and adaptive cells during MASH progression and identify CD8+ T cells as potential regulators of monocyte infiltration and hepatic injury.

Animals↗

Targeting hepatocyte-specific SLC2A8 blocks hepatic steatosis and dissociates TCA cycle flux inhibition from glutamine anaplerosis.

BACKGROUND: Excess TCA cycle and glutamine anaplerosis are hallmarks of metabolic dysfunction-associated steatotic liver disease and steatohepatitis. Blocking glutamine metabolism attenuates metabolic dysfunction-associated steatohepatitis. However, inhibiting TCA cycle flux by blocking plasma membrane carbohydrate transport is limited by the ubiquitous tissue distribution, function, and homology among the SLC2A family of facilitative carbohydrate transporters, and the potential for carbohydrate blockade to invoke or exacerbate glutamine anaplerosis. Here, we quantify alterations in hepatocyte carbon flux, define the broader metabolic consequences of hepatocyte-specific GLUT8/SLC2A8 inhibition, and delineate the antisteatotic efficacy of a novel small-molecule GLUT8-selective inhibitor. METHODS: We generated mice with floxed SLC2A8 alleles and expressed hepatocyte-specific Cre by breeding these mice with albumin-Cre transgenic mice, or by administering AAV8 encoding hepatocyte-specific iCre. We performed stable-isotope glucose, fructose, and glutamine metabolic labeling in isolated GLUT8WT and GLUT8LKO hepatocytes and performed metabolic phenotyping in lean and diet-induced obese GLUT8WT and GLUT8LKO mice. Finally, we performed high-throughput screening to identify a GLUT8-selective inhibitor, which we characterized using in vitro models of triglyceride accumulation. RESULTS: Hepatocyte-specific SLC2A8 deletion reduced diet-induced hepatic and peripheral fat accumulation and increased thermogenesis during ZT12-24 (eg, the dark phase). It also disrupted TCA cycle flux without inducing compensatory glutamine utilization. High-throughput screening identified a small-molecule, GLUT8-selective inhibitor, P20, which blocked hepatocyte TG accumulation and inflammation in in vitro steatotic and inflammatory models. CONCLUSIONS: Deleting the hepatocyte carbohydrate transporter GLUT8 suppresses TCA cycle flux without inducing compensatory glutamine anaplerosis. The net effect of this is liver protection against multiple forms of dietary insult. Given that selective pharmacological GLUT8 inhibition is feasible, GLUT8 may be a viable target to abate metabolic dysfunction-associated steatohepatitis and other complications of obesity.

Animals↗

The glucagon and GLP-1 receptor dual agonist DD01 for metabolic dysfunction-associated steatotic liver disease and steatohepatitis (DD01-DN-02): 12-week results from a randomised, double-blind, multicentre, placebo-controlled, phase 2 trial.

BACKGROUND: Metabolic dysfunction-associated steatohepatitis (MASH) is a major public health problem arising in the context of metabolic syndrome and obesity. DD01 is a liver-targeted GLP-1 receptor and glucagon dual agonist being investigated for the treatment of metabolic dysfunction-associated steatotic liver disease (MASLD) and MASH. The DD01-DN-02 trial aimed to evaluate the efficacy and safety of DD01 in adults with MASLD or MASH; this initial analysis reports prespecified 12-week outcomes to assess early hepatic effects. METHODS: DD01-DN-02 is an ongoing, randomised, double-blind, multicentre, placebo-controlled, phase 2 trial conducted at 12 outpatient clinical sites in the USA. Adults aged 18-70 years with obesity or who were overweight (BMI &#x2265;25 kg/m2) were included in the study. Patients with MASLD or MASH underwent liver biopsy and MRI-proton density fat fraction (PDFF) and were eligible if liver fat content was 10% or higher with metabolic risk factors, or if the biopsy confirmed MASH with a non-alcoholic fatty liver disease activity score of at least 4. Participants were randomly assigned (1:1) to receive once-weekly subcutaneous DD01 40 mg or matched placebo over 48 weeks, dose-escalated over 2 weeks, using a centrally administered interactive response technology system. The randomisation sequence was computer-generated by an independent statistician. Participants, investigators, study staff, outcome assessors, and the sponsor were masked to treatment assignment. The primary endpoint was the proportion of participants having at least a 30% relative reduction in liver fat by MRI-PDFF at week 12, which was analysed in all randomly assigned participants receiving at least one dose of study drug or placebo. Safety analyses included all participants who received at least one dose of study drug. Missing primary endpoint data were handled using multiple imputation under a missing-at-random assumption. This trial is registered with ClinicalTrials.gov (NCT06410924) and is ongoing but closed to new participants. FINDINGS: Between June 13, 2024, and Jan 30, 2025, 67 eligible participants were enrolled, of whom 33 were randomly assigned to DD01 and 34 to placebo. The mean age of participants was 48&#xb7;4 years (SD 10&#xb7;6), 42 (63%) were female, 25 (37%) were male, 57 (85%) were White, and 52 (78%) participants had biopsy-confirmed MASH. At week 12, 25 (76%) of 33 participants receiving DD01 had a 30% or higher reduction in liver fat versus four (12%) of 34 participants receiving placebo (adjusted common odds ratio 28&#xb7;8 [95% CI 7&#xb7;2-115&#xb7;2]; adjusted relative risk 6&#xb7;3 [95% CI 2&#xb7;5-15&#xb7;9]; p<0&#xb7;0001). Treatment-emergent adverse events occurred in 28 (85%) of 33 participants receiving DD01 and 23 (68%) of 34 participants receiving placebo. The most common adverse events were nausea (18 [55%] of 33 participants assigned DD01; six [18%] of 34 participants assigned placebo), diarrhoea (nine [27%] of 33; six [18%] of 34), and vomiting (ten [30%] of 33; four [12%] of 34). Treatment-emergent adverse events led to treatment discontinuation in four (12%) of 33 participants in the DD01 group and one (3%) of 34 participants in the placebo group. Two (6%) treatment-emergent serious adverse events occurred in the DD01 group (abdominal pain and acute cholecystitis) and zero in the placebo group. No deaths occurred. INTERPRETATION: In this prespecified 12-week primary analysis, DD01 produced rapid reductions in liver fat compared with placebo, supporting further evaluation in long-term studies. FUNDING: D&D Pharmatech, Neuraly.

Humans↗

Hepatocyte-specific CLSTN3B ablation impairs lipid droplet maturation and alleviates diet-induced steatohepatitis in mice.

Excessive lipid accumulation in hepatocytes, a hallmark of metabolic dysfunction-associated steatotic liver disease (MASLD), can lead to progressive liver damage. Understanding the molecular mechanisms governing lipid storage in hepatocytes is essential for identifying therapeutic targets to halt MASLD progression. Here, we show a pivotal role for the protein calsyntenin 3&#x3b2; (CLSTN3B) in promoting lipid droplet (LD) maturation and lipid storage in hepatocytes. Previously characterized as an endoplasmic reticulum (ER)-LD contact protein that facilitates LD maturation in adipocytes, we now show that CLSTN3B expression is strongly induced in mouse hepatocytes by peroxisome proliferator-activated receptor gamma (PPAR&#x3b3;) in response to dietary caloric excess. Hepatocyte-specific deletion of CLSTN3B in mice significantly increases energy expenditure, reduces metabolic efficiency, and protects against diet-induced hepatic steatosis and fibrosis. Mechanistically, CLSTN3B deficiency causes reduced LD phospholipid coverage and increased lipase recruitment. This results in enhanced fatty acid oxidation driven by a futile cycle of lipolysis and re-esterification. Notably, human clinical data reveal a positive correlation between hepatic CLSTN3B expression and MASLD severity and progression, emphasizing its relevance to human disease. Together, our findings establish CLSTN3B as a key regulator of hepatocyte lipid storage and metabolic efficiency and highlight its potential as a therapeutic target in MASLD.

Journal Article↗