Effects of epoxyeicosatrienoic acids on polymorphonuclear leukocyte function

Area of Science:

• Cardiovascular Biology
• Inflammation Research
• Endothelial Cell Function

Background:

• Ischemia and vascular injury trigger the release of factors that recruit monocytes and polymorphonuclear leukocytes (PMNs) to injury sites.
• Endothelium-derived epoxyeicosatrienoic acids (EETs), cytochrome P450 metabolites of arachidonic acid, are elevated during coronary artery stenosis.
• The role of EETs in modulating PMN recruitment to the endothelium requires further investigation.

Purpose of the Study:

• To investigate whether epoxyeicosatrienoic acids (EETs) stimulate PMN adherence to cultured endothelial cells (ECs).
• To explore the impact of EETs on PMN aggregation and intracellular calcium levels.
• To elucidate the biological significance of EETs in myocardial ischemia and vascular injury.

Main Methods:

• Cultured endothelial cells (ECs) were pretreated with EETs, followed by incubation with 51Cr-labelled PMNs to assess adherence.
• PMN adherence was also evaluated during coincubation of ECs and PMNs with EETs and/or phorbol myristate acetate (PMA).
• PMN aggregation and intracellular calcium levels were measured in response to various EETs, and superoxide production was assessed.

Main Results:

• EET pretreatment of ECs did not alter PMN adherence, while PMA significantly increased it.
• During coincubation, EETs caused a concentration-dependent decrease in PMN adherence, associated with PMN aggregation.
• Specific EETs, including 8,9-EET, significantly increased PMN aggregation and intracellular calcium, but not superoxide production.

Conclusions:

• EETs do not promote PMN adherence to endothelial cells but rather induce PMN aggregation.
• The observed decrease in PMN adherence in coincubation assays is attributed to EET-induced PMN aggregation.
• Elevated EET levels during coronary artery stenosis may contribute to myocardial ischemia and vascular injury through PMN aggregation.