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Induction of an Inflammatory Response in Primary Hepatocyte Cultures from Mice
Published on: March 10, 2017
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TLR4 promotes liver inflammation by activating the JNK pathway
1Department of Hepatology, Third People's Hospital of Shenzhen City, Shenzhen, China. gl.yang@163.com.
European Review for Medical and Pharmacological Sciences
|September 21, 2019
Summary
Toll-like receptor 4 (TLR4) exacerbates acetaminophen-induced liver injury by activating the JNK pathway, leading to inflammation and immune cell infiltration. Inhibiting TLR4 in mice reduced liver damage, suggesting it as a therapeutic target for drug-induced hepatitis.
Area of Science:
- Hepatology and Immunology
- Molecular and Cellular Biology
- Pharmacology and Toxicology
Background:
- Drug-induced liver injury (DILI) is a significant public health concern.
- Acetaminophen (APAP) overdose is a leading cause of DILI, yet its precise mechanisms remain incompletely understood.
- Identifying novel molecular pathways involved in APAP-DILI is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the role of toll-like receptor 4 (TLR4) in acetaminophen-induced liver injury (APAP-DILI).
- To elucidate the molecular mechanisms by which TLR4 influences APAP-DILI, focusing on inflammatory signaling pathways.
- To explore the potential of targeting TLR4 for the prevention and treatment of APAP-DILI.
Main Methods:
- Wild-type (WT) and TLR4 knockout (TLR4-/-) mice were administered acetaminophen (APAP) or vehicle.
- Liver injury was assessed by measuring serum alanine aminotransferase (ALT) and glutathione (GSH) levels, and histological examination (H&E staining).
- Inflammatory cytokine expression (TNF-α, IL-1β, MCP-1, IL-6), immune cell infiltration (macrophages, neutrophils via flow cytometry), and JNK/p38 signaling pathway activation (Western blotting) were analyzed.
Main Results:
- TLR4-/- mice exhibited significantly reduced APAP-induced liver injury, characterized by lower ALT levels, higher GSH levels, and less hepatocellular necrosis/apoptosis compared to WT mice.
- TLR4 deficiency led to decreased expression of pro-inflammatory cytokines (MCP-1, IL-6) and reduced infiltration of macrophages and neutrophils into the liver.
- APAP treatment strongly activated the JNK signaling pathway in WT mice, whereas this activation was significantly blunted in TLR4-/- mice and in RAW264.7 cells with TLR4 knockdown.
Conclusions:
- Toll-like receptor 4 (TLR4) plays a critical role in promoting acetaminophen-induced liver injury.
- TLR4 mediates APAP-DILI by activating the JNK signaling pathway, which drives the secretion of inflammatory factors and immune cell infiltration.
- Targeting TLR4 presents a promising therapeutic strategy for managing clinical drug-induced hepatitis caused by acetaminophen.
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