In Vivo Bruton's Tyrosine Kinase Inhibition Attenuates Alcohol-Associated Liver Disease by Regulating CD84-Mediated Granulopoiesis

Infectious Diseases Hepatobiliary System Biochemistry Hematology Life Sciences Immunology Gastroenterology Medicine
Bruton's Tyrosine Kinase Alcohol-Associated Liver Disease Granulopoiesis Neutrophils Liver Damage Therapeutic Target

Research Background

Severe alcoholic hepatitis (ALD) is a fatal form of alcohol-associated liver disease (AALD). The course of ALD is usually accompanied by neutrophil infiltration in the liver, which significantly affects the severity of the condition. However, the specific effects of alcohol on neutrophil function remain unclear. Based on this, it is extremely important to identify therapeutic targets that can alleviate neutrophil-mediated liver injury. Bruton’s tyrosine kinase (BTK) plays a key role in the development and function of neutrophils, but its role in ALD has not been elucidated.

Paper Source

This paper was written by Prashanth Thevkar Nagesh, Yeonhee Cho, Yuan Zhuang, Mrigya Babuta, and others from Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA. The paper was published in the journal “Science Translational Medicine” on August 7, 2024.

Research Process

This study employed various experimental methods and techniques to clarify the role of BTK in ALD and evaluate the therapeutic potential of BTK inhibitors (BTKIs).

a) Detailed Research Process

  1. Preliminary experiments: RNA sequencing analysis of circulating neutrophil BTK expression in patients with ALD and healthy controls (P=0.05) found that BTK expression and phosphorylation levels were significantly increased in ALD patients.

  2. In vitro experiments: In vitro, physiologically relevant doses of alcohol rapidly induced TLR4-mediated BTK phosphorylation (PBTK) in neutrophils.

  3. Animal model experiments: In preclinical ALD models, the use of small molecule BTK inhibitors (Evobrutinib) or myeloid cell-specific BTK knockout resulted in reduced pro-inflammatory cytokines and neutrophil-mediated liver injury. Additionally, PBTK was found to be key to alcohol-induced bone marrow granulopoiesis and hepatic neutrophil infiltration.

  4. In vivo experiments: In vivo, BTK inhibition or myeloid cell-specific BTK knockout reduced granulopoiesis, circulating neutrophils, hepatic neutrophil infiltration, and liver injury.

  5. Further validation: Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), the kinase target CD84 of BTK was identified and found to be involved in granulopoiesis. In vitro experiments showed that CD84 promoted alcohol-induced interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in primary human neutrophils, while treatment with CD84 blocking antibodies inhibited the production of these inflammatory factors.

b) Main Results

Each experimental step supported the important role of BTK in the pathogenesis of ALD. Detailed analysis showed:

  1. Circulating and liver-infiltrating neutrophils: Hepatic neutrophil infiltration and bone marrow granulopoiesis were significantly increased in ALD patients and mouse models.
  2. BTK and PBTK levels: BTK and PBTK levels were significantly upregulated in ALD patients and models.
  3. Direct action mechanism: Acute alcohol exposure directly induced BTK phosphorylation in neutrophils and achieved this process through the TLR4 pathway.
  4. Therapeutic effect of BTKI: BTKI (Evobrutinib) significantly reduced neutrophil infiltration, inflammation, and liver injury in ALD mouse models, supporting the therapeutic potential of BTKI.
  5. Key mechanism of granulopoiesis: The central role of BTK in bone marrow granulopoiesis was confirmed, with inhibition of BTK phosphorylation significantly slowing alcohol-induced granulopoiesis.

Conclusions and Significance

Through these experiments, this paper revealed the key role of BTK in neutrophil-mediated inflammation and ALD-related liver injury, providing new directions for potential therapeutic interventions. The use of BTKIs may become an effective strategy for ALD treatment, with its mechanism of inhibiting BTK phosphorylation able to reduce neutrophil-mediated inflammation and liver injury.

Research Highlights

  1. Innovation: This study is the first to clearly define the key regulatory role of BTK in ALD.
  2. Potential therapeutic applications: The use of BTKI (Evobrutinib) effectively alleviated liver injury, providing a potential therapeutic strategy.
  3. In-depth mechanism research: By identifying CD84 as the kinase target of BTK, the mechanism of neutrophil generation was revealed.

Other Valuable Information

This study also provided extensive data support, including multiple repeat experiments in human and mouse models, further validating the effectiveness of BTKI in treating ALD and its potential clinical application value. At the same time, the use of liquid chromatography-tandem mass spectrometry technology increased the depth of the research, providing more detailed molecular mechanism analysis for subsequent studies.

This study not only revealed the mechanism of BTK in ALD but also provided a theoretical basis for the development of new therapeutic strategies, with important scientific and clinical application value.