Macrophage epoxygenase determines a profibrotic transcriptome signature.

Area of Science:

• Biochemistry
• Cell Biology
• Immunology

Background:

• Epoxygenases, part of the cytochrome P450 family, produce epoxyeicosatrienoic acids with known anti-inflammatory effects.
• The specific role of epoxyeicosanoic acids in macrophage function remains largely unexplored.
• Macrophage dysfunction is implicated in various inflammatory and fibrotic diseases.

Purpose of the Study:

• To investigate the role of epoxyeicosanoic acids in macrophage function.
• To determine the expression profile of epoxyeicosanoic acids in rodent and human macrophages.
• To elucidate the impact of targeting the major rat macrophage epoxygenase, Cyp2j4, on macrophage phenotype and fibrotic processes.

Main Methods:

• High-throughput RNA sequencing was employed to analyze gene expression in primary macrophages.
• Zinc-finger nuclease technology was used for targeted gene deletion of Cyp2j4 in rat macrophages.
• In vivo studies involved unilateral ureter obstruction and crescentic glomerulonephritis models in rats.
• Quantitative proteomics (liquid chromatography-tandem mass spectrometry) was utilized to assess protein abundance.

Main Results:

• Cyp2j4 deletion in macrophages led to reduced epoxyeicosanoic acid synthesis and increased peroxisome proliferator-activated receptor-γ levels.
• Cyp2j4-deficient macrophages exhibited a profibrotic transcriptome with overexpression of extracellular matrix genes, notably fibronectin.
• In vivo, Cyp2j4 knockout rats showed increased type I collagen and fibronectin in kidneys following injury models.

Conclusions:

• The rat epoxygenase Cyp2j4 is identified as a key regulator of a profibrotic macrophage transcriptome.
• Epoxygenase activity directly influences fibronectin expression in both rat and human macrophages.
• Targeting Cyp2j4 may offer therapeutic potential for inflammatory and fibrotic conditions involving macrophage activation.