The effects of the omega-3 fatty acid, DHA, on neutrophil secretion of chemokines and cytokines in vitro

Abstract

Introduction: Neutrophils are a big part of the innate immune response. They influence the inflammatory and immune responses by performing various effector functions like secretion of cytokines and chemokines. Neutrophil influx into tissue must be tightly regulated as their prolonged influences can lead to tissue damage. Omega-3 fatty acids can influence inflammation in various ways. Therefore, it was of interestto see if they affected neutrophil function.Aim: The aim of the study was to determine the effects of the omega-3 fatty acid, DHA, on neutrophil secretion of cytokines and chemokines.Methods: Human neutrophils were isolated from peripheral blood from healthy donors, and cultured in the absence or presence of LPS at 50, 100 or 200 ng/ml. Culture supernatants were collected at various time-points. In some experiments, neutrophils were cultured with 50 μM of DHA or solvent, for up to 12 h. After 3 h the neutrophils were stimulated with 100 ng/ml LPS or left unstimulated. Supernatants were collectedat four time-points (0, 3, 5 and 12 h). The concentrations of the hemokines CXCL8, CCL20 and the cytokines IL-6 and IL-1β were measured in the culture supernatants by enzyme-linked immunosorbent assay (ELISA).Results: A successful in vitro culture system was set up for human neutrophils. The neutrophils secreted increased levels of CXCL8 by increased time in culture, whereas CCL20, IL-6 and IL-1β were hardly detectable. Stimulating the neutrophils with LPS induced secretion of CXCL8, CCL20, IL-6 and IL-1β. However, culturing neutrophils with 50 μM of DHA did not affect the chemokine or cytokine secretion by human neutrophils, regardless of whether they were stimulated with LPS or not.Conclusion: These results indicate that DHA, under the culture conditions used in this study, has no effect on the chemokine and cytokine secretion of neutrophils.