Eicosapentaenoic acid is more effective than docosahexaenoic acid in inhibiting proinflammatory mediator production and transcription from LPS-induced human asthmatic alveolar macrophage cells

Background & aims: The purpose of the study was to determine which of the active constituents of fish oil, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), is most effective in suppressing proinflammatory mediator generation and cytokine expression from LPS-stimulated human asthmatic alveolar macrophages (AMΦ). Methods: The AMΦ were obtained from twenty-one asthmatic adults using fiberoptic bronchoscopy. Cells were pretreated with DMEM, pure EPA, an EPA-rich media (45% EPA/10% DHA), pure DHA, a DHArich media (10% EPA/50% DHA) or Lipovenos® (n-6 PUFA), and then exposed to Dulbecco’s Modified Eagle’s Medium (DMEM) (-) or LPS (+). Supernatants were analyzed for leukotriene (LT)B4, prostaglandin (PG)D2, tumor necrosis factor (TNF)-α and interleukin (IL)-1β production. Detection of TNF-α and IL-1β mRNA expression levels was quantified by reverse transcriptase polymerase chain reaction. Results: 120 μM pure EPA and EPA-rich media significantly (p < 0.05) suppressed TNF-a and IL-1b mRNA expression and the production of LTB4, PGD2 and TNF-a and IL-1b in LPS-stimulated primary AMφ cells obtained from asthmatic patients to a much greater extent than 120 mM pure DHA and DHA-rich media respectively. Conclusions: This study has shown for the first time that EPA is a more potent inhibitor than DHA of inflammatory responses in human asthmatic AMΦ cells.