A Microbial Metabolite Mediates the Beneficial Effects of Time-Restricted Feeding on MASH by Inhibiting the HIF-2A-Ceramide Pathway

Introduction

Background:

Metabolic Dysfunction-Associated Steatotic Liver Disease/Metabolic Dysfunction-Associated Steatohepatitis (MASLD/MASH) is a major health problem affecting a quarter of the global population. MASLD ranges from liver steatosis to the more aggressive MASH, characterized by necroinflammation and fibrosis, which may progress to cirrhosis and hepatocellular carcinoma. Current clinical treatments primarily focus on halting the progression of MASLD and reversing existing MASH. However, due to its complex pathology and lack of effective medical interventions, dietary and lifestyle adjustments remain the main management options, yet patients find it difficult to adhere to these methods.

Research Question:

Time-Restricted Feeding (TRF) is an effective dietary intervention that has been shown to reduce body weight, improve insulin resistance, and suppress liver fat accumulation. However, the specific molecular mechanisms of this approach are not fully elucidated. This study aims to explore the potential mechanisms by which TRF improves MASLD/MASH, with a focus on the role of changes in gut microbiota and their metabolites in this process.

Relevant Background Knowledge:

TRF refers to restricting daily food intake to a 4 to 12-hour window, which, while not limiting caloric intake, has been shown to have significant effects on improving metabolic diseases. Since gut microbiota play a crucial role in host metabolic regulation, studies have shown that TRF can partially restore the periodic fluctuations in gut microbiota induced by a high-fat diet, thereby affecting the host’s metabolic function. However, the role of gut microbiota and their metabolites in the improvement of MASLD/MASH by TRF requires further exploration.

Research Source

Authors and Institutions:

The authors of this paper, Yi Zhang, Xuemei Wang, Jun Lin, and others, are from organizations such as Peking University Third Hospital, China-Japan Friendship Hospital, and the Peking University Health Science Center. Their research is also supported by the Tencent Foundation. This study was published on August 6, 2024, in the journal “Cell Metabolism.”

Corresponding Authors: Wang Guang, Zhang Zhipeng, Wei Fu, Changtao Jiang, Yanli Pang

Publication Date: August 6, 2024

Paper Title: A microbial metabolite inhibits the HIF-2A-ceramide pathway to mediate the beneficial effects of time-restricted feeding on MASH.

Research Details

a) Research Workflow

Experimental Design:

1. Clinical Trial: A four-week clinical intervention study was initially conducted by recruiting 19 MASLD patients. They were required to eat freely from 7 AM to 5 PM (a 10-hour feeding window) and fast during other times. Stool and plasma samples were collected during the study to detect representative indicators of liver function and blood lipid levels.

2. Mouse Experiment: Eight-week-old male C57BL/6J mice were fed a high-fat diet (HFD) and restricted to a 10-hour feeding window (ZT13 to ZT23) to simulate the TRF method, with or without antibiotic treatment to study the role of gut microbiota in the TRF intervention. Furthermore, the changes in gut microbiota of TRF mice and control group were analyzed using whole-genome shotgun sequencing.

3. Functional Validation Experiment: By using top ten “post-TRF microbiota” microbial model (ATM) and ATM model without R. torques, the role of R. torques in MASLD progression was validated upon feeding mice. The authors also explored the mechanism by which R. torques improves MASLD through RNA sequencing.

4. Metabolite Analysis: Various experimental methods, including co-immunoprecipitation and liquid chromatography-mass spectrometry (LC-MS), were used to analyze the inhibition of the gut HIF-2A-ceramide axis by the R. torques product HMP, and further verify the roles of R. torques and HMP in the MASH process.

Novel Methods and Equipment:

The authors uniquely identified the enzyme RTMOR in R. torques that can synthesize HMP, and performed corresponding gene expression and functional validations. These novel approaches provide an important foundation for studying the mechanism by which microbial metabolites improve MASLD/MASH through TRF.

b) Main Results

Clinical Trial Results:

1. After TRF intervention, the plasma levels of ALT, AST, and GGT in subjects significantly decreased, the hepatic steatosis index (HSI) was significantly reduced, serum triglyceride (TG) levels also significantly decreased, and BMI decreased.

2. Whole-genome shotgun sequencing of stool samples showed that TRF intervention significantly increased the abundance of R. torques in the Clostridiales order.

Mouse Experiment Results:

1. The ALT and AST levels in the TRF mouse group were lower than those in the control group, and BMI, liver weight, and liver/body weight ratio also significantly decreased.

2. H&E staining and Oil Red O staining revealed that TRF improved MASLD caused by HFD, with significantly increased diversity of gut microbiota in mice and significantly increased abundance of R. torques.

3. Gavage proved that R. torques supplementation significantly alleviated MASLD symptoms in mice, reducing liver and plasma TG and TC levels.

Mechanism Study Results:

1. Co-immunoprecipitation tests confirmed that HMP inhibits gut HIF-2A function by disrupting HIF-2A-ARNT interaction.

2. Mouse experiments showed that R. torques and HMP significantly reduced the expression of HIF-2A related downstream genes (such as NEU3, DMT1, FPN), suppressed the ceramide synthesis pathway, thus improving MASLD.

3. HMP alleviated MASLD symptoms by reducing intestinal ceramide levels through inhibiting the intestinal HIF-2A-ceramide signaling axis.

c) Conclusion and Value of Research

Scientific Value:

This study is the first to reveal the critical role of gut microbiota and their metabolites in improving MASLD/MASH through TRF, clarifying the role of R. torques and its metabolite HMP in inhibiting the intestinal HIF-2A-ceramide pathway. The research provides a new perspective for understanding how gut symbiotic bacteria regulate the development of host metabolic diseases and proposes the possibility of R. torques and HMP as potential probiotic interventions or pharmaceutical treatments for MASLD/MASH.

Application Value:

The study results offer new strategies for treating MASLD/MASH; the supplementation of microbial metabolites (such as HMP) can mimic the fasting dietary schemes that are difficult to adhere to persistently, thereby reducing liver steatosis and its progression. This opens up new avenues for developing microbiome-based therapeutic strategies with promising clinical applications.

d) Research Highlights

1. Important Discovery: For the first time, the critical role of R. torques in TRF improving MASLD/MASH is identified, and its metabolite HMP is found to function by inhibiting the intestinal HIF-2A-ceramide pathway.

2. Novel Approaches: For the first time, the enzyme RTMOR in R. torques that can synthesize HMP was identified, and its gene expression and functional validations were performed.

3. Application Potential: The proposal of R. torques and HMP as probiotic interventions or pharmaceutical treatments for MASLD/MASH opens up new avenues for developing microbiome-based therapeutic strategies.