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Updated: Jan 18, 2026
Mouse Model of Metabolic Dysfunction-Associated Steatotic Liver Disease with Fibrosis
Published on: July 18, 2025
Impaired TIM4-mediated efferocytosis by liver macrophages contributes to fibrosis in metabolic dysfunction-associated
Hongxue Shi1, Xiaobo Wang1, Christopher Sloas2
1Department of Medicine, Columbia University Irving Medical Center, New York, NY 10032, USA.
Abstract:
Hepatocyte apoptosis is a key feature of metabolic dysfunction-associated steatohepatitis (MASH), but the fate of apoptotic hepatocytes in MASH is poorly understood. Here, we explore the hypotheses that clearance of dead hepatocytes by liver macrophages (efferocytosis) is impaired in MASH because of low expression of the efferocytosis receptor T cell immunoglobulin and mucin domain containing 4 (TIM4; gene Timd4) by MASH liver macrophages, which then drives liver fibrosis in MASH. We show that apoptotic hepatocytes accumulate in human and experimental MASH, using mice fed the fructose-palmitate-cholesterol (FPC) diet or the high-fat, choline-deficient amino acid-defined (HF-CDAA) diet. Apoptotic hepatocyte accumulation is associated with impaired efferocytosis and loss of TIM4. Administration of neutralizing anti-TIM4 antibodies or genetic deletion of Timd4 in Kupffer cells of FPC and HF-CDAA diet-fed mice decreased efferocytosis by liver macrophages, increased profibrotic activation of collagen-producing hepatic stellate cells (HSCs), and accelerated the progression to fibrotic MASH. Genetic restoration of macrophage Timd4 in FPC and HF-CDAA diet-fed MASH mice or cell therapy with TIM4+ macrophages enhanced apoptotic hepatocyte clearance and decreased HSC activation and liver fibrosis. Studies using an ex vivo macrophage HSC cross-talk model and the HF-CDAA MASH model revealed that inactivation of HSCs by efferocytosing macrophages involved macrophage reprogramming to secrete interleukin-10 (IL-10), which activated the IL-10 receptor on HSCs to dampen their profibrotic activation. These findings reveal a key process in the progression from hepatic steatosis to early MASH fibrosis and identify a mechanism-based therapeutic strategy to prevent fibrotic MASH progression.
Insights
Impaired clearance of dead liver cells (apoptotic hepatocytes) in metabolic dysfunction-associated steatohepatitis (MASH) is linked to reduced TIM4 expression on macrophages. Restoring TIM4 improves clearance, reduces liver fibrosis, and offers a therapeutic strategy for MASH.
Area of Science:
- Hepatology
- Immunology
- Fibrosis Research
Background:
- Hepatocyte apoptosis is central to metabolic dysfunction-associated steatohepatitis (MASH).
- The clearance mechanisms for apoptotic hepatocytes and their role in MASH progression, particularly fibrosis, remain unclear.
- T cell immunoglobulin and mucin domain containing 4 (TIM4) is an efferocytosis receptor expressed by macrophages.
Purpose of the Study:
- To investigate the role of TIM4-mediated efferocytosis in MASH pathogenesis.
- To determine if impaired efferocytosis contributes to liver fibrosis in MASH.
- To explore therapeutic strategies targeting TIM4 for MASH treatment.
Main Methods:
- Utilized mouse models of MASH (fructose-palmitate-cholesterol and high-fat, choline-deficient amino acid-defined diets).
- Assessed apoptotic hepatocyte accumulation, efferocytosis, TIM4 expression, and hepatic stellate cell (HSC) activation.
- Employed genetic manipulation (Timd4 deletion/restoration in Kupffer cells) and antibody treatments.
- Investigated macrophage-HSC crosstalk using ex vivo models and analyzed IL-10 signaling pathways.
Main Results:
- Apoptotic hepatocytes accumulate in MASH livers, correlating with impaired efferocytosis and reduced TIM4 expression on Kupffer cells.
- Loss of TIM4 exacerbates liver fibrosis by increasing HSC profibrotic activation.
- Restoring TIM4 expression or using TIM4-expressing macrophages enhances efferocytosis, suppresses HSC activation, and reduces liver fibrosis.
- Macrophage efferocytosis of apoptotic hepatocytes reprograms macrophages to secrete IL-10, which dampens HSC profibrotic activity.
Conclusions:
- Impaired TIM4-mediated efferocytosis by Kupffer cells is a critical mechanism driving liver fibrosis in MASH.
- TIM4 acts as a crucial regulator of liver macrophage function in MASH.
- Targeting TIM4-mediated efferocytosis presents a promising therapeutic avenue for preventing MASH progression to fibrosis.
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