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CXCL4/CXCR3 axis regulates cardiac fibrosis by activating TGF-β1/Smad2/3 signaling in mouse viral myocarditis
Jing Wei1, Dan-Feng Wang2, Cong-Cong Cui2
1Department of Laboratory Medicine, Nanjing First Hospital, Nanjing Medical University, Nanjing, China.
Background:
Severe myocarditis is often accompanied by cardiac fibrosis, but the underlying mechanism has not been fully elucidated. CXCL4 is a chemokine that has been reported to have pro-inflammatory and profibrotic functions. The exact role of CXCL4 in cardiac fibrosis remains unclear.
Methods:
Viral myocarditis (VMC) models were induced by intraperitoneal injection of Coxsackie B Type 3 (CVB3). In vivo, CVB3 (100 TCID50) and CVB3-AMG487 (CVB3: 100 TCID50; AMG487: 5 mg/kg) combination were administered in the VMC and VMC+AMG487 groups, respectively. Hematoxylin and eosin staining, severity score, Masson staining, and immunofluorescence staining were performed to measure myocardial morphology in VMC. Enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) were performed to quantify inflammatory factors (IL-1β, IL-6, TNF-α, and CXCL4). Aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and creatine kinase-myocardial band (CK-MB) levels were analyzed by commercial kits. CXCL4, CXCR3B, α-SMA, TGF-β1, Collagen I, and Collagen III were determined by Western blot and immunofluorescence staining.
Results:
In vivo, CVB3-AMG487 reduced cardiac injury, α-SMA, Collagen I and Collagen III levels, and collagen deposition in VMC+AMG487 group. Additionally, compared with VMC group, VMC+AMG group decreased the levels of inflammatory factors (IL-1β, IL-6, and TNF-α). In vitro, CXCL4/CXCR3B axis activation TGF-β1/Smad2/3 pathway promote mice cardiac fibroblasts differentiation.
Conclusion:
CXCL4 acts as a profibrotic factor in TGF-β1/Smad2/3 pathway-induced cardiac fibroblast activation and ECM synthesis, and eventually progresses to cardiac fibrosis. Therefore, our findings revealed the role of CXCL4 in VMC and unveiled its underlying mechanism. CXCL4 appears to be a potential target for the treatment of VMC.
Insights
CXCL4 promotes cardiac fibrosis by activating the TGF-β1/Smad2/3 pathway in viral myocarditis. Targeting CXCL4 may offer a new therapeutic strategy for treating cardiac fibrosis in viral myocarditis.
Area of Science:
- Cardiology
- Immunology
- Pathology
Background:
- Severe myocarditis often leads to cardiac fibrosis, but the precise mechanisms remain incompletely understood.
- CXCL4, a chemokine with known pro-inflammatory and profibrotic properties, has an unclear role in cardiac fibrosis development.
Purpose of the Study:
- To elucidate the role and underlying mechanism of CXCL4 in viral myocarditis (VMC)-induced cardiac fibrosis.
- To investigate CXCL4 as a potential therapeutic target for VMC.
Main Methods:
- Viral myocarditis (VMC) was induced in mice using Coxsackie B Type 3 (CVB3).
- CXCL4 inhibition was achieved using AMG487 in the VMC+AMG487 group.
- Cardiac morphology, inflammatory markers (IL-1β, IL-6, TNF-α, CXCL4), cardiac injury markers (AST, LDH, CK-MB), and fibrosis-related proteins (α-SMA, Collagen I, Collagen III, TGF-β1) were assessed using histological staining, ELISA, qRT-PCR, and Western blotting.
Main Results:
- CXCL4 inhibition with AMG487 significantly reduced cardiac injury, fibrosis markers (α-SMA, Collagen I, Collagen III), and collagen deposition in VMC mice.
- CXCL4 inhibition also decreased levels of key inflammatory factors (IL-1β, IL-6, TNF-α).
- In vitro studies demonstrated that the CXCL4/CXCR3B axis activates the TGF-β1/Smad2/3 pathway, promoting cardiac fibroblast differentiation and extracellular matrix synthesis.
Conclusions:
- CXCL4 functions as a profibrotic factor in VMC by driving cardiac fibroblast activation and extracellular matrix synthesis via the TGF-β1/Smad2/3 pathway.
- These findings highlight the critical role of CXCL4 in the pathogenesis of VMC and cardiac fibrosis.
- CXCL4 emerges as a promising therapeutic target for managing VMC and associated cardiac fibrosis.
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