Vinsamlegast notið þetta auðkenni þegar þið vitnið til verksins eða tengið í það: http://hdl.handle.net/1946/29860
Introduction: As neutrophils are a vital component of the innate immune system and
in inflammation, the effects that the n-3 PUFAs could have on neutrophils relating to
anti-inflammatory and pro-resolving effects is an interesting research field. During the inflammatory response, damage to the host can occur as neutrophils release oxidants, proteases and antimicrobial proteins that can cause tissue injury. They also secrete various cytokines that can amplify the inflammatory response. Therefore, if n-3 PUFAs would be shown to have anti-inflammatory or pro-resolving effects by affecting neutrophil survival and/or cellular function, especially during prolonged inflammation, it might prevent some of the tissue damage caused by neutrophils.
Aim: The aim of this study was to assess the effects of the n-3 PUFA, DHA, on
neutrophil apoptosis and their expression of various surface molecules.
Methods: Human neutrophils, isolated from peripheral blood from healthy volunteers,
and cultured in vitro with or without LPS, were harvested at different time-points. In
some experiments, neutrophils were cultured with DHA (50 μM) or control (DMSO) for
3 h and then cultured further with or without LPS for 2 or 9 h. The harvested cells were stained with annexin V and propidium iodide or with antibodies against CD11b, CD16a and CD62L and the percentage of positive cells determined using flow cytometry.
Results: A successful in vitro culture system was set up for human neutrophils. The
percentage of live neutrophils decreased with time in culture and the percentage of
apoptotic cells increased. The percentage of neutrophils expressing CD11b, CD16a
and CD62L also seemed to decrease with increased time in culture. LPS stimulation
seemed to increase neutrophil survival by delaying neutrophil apoptosis and also
delayed downregulation of CD11b expression and downregulated CD62L expression.
Adding DHA to cultured neutrophils did not affect neutrophil apoptosis or their surface molecule expression. Two distinct neutrophil populations that differed in size and granularity were observed upon analysis of freshly isolated neutrophils. The larger and less granular neutrophils (P2) seemed to be less apoptotic and to have more prolonged expression of CD11b and CD16a in culture than the smaller and more granular neutrophils (P1).
Conclusion: The results indicate that LPS increases neutrophil survival and function
but that DHA does not have an effect on neutrophil survival or their surface molecule
expression. The results further indicate that of the two distinct neutrophil populations
detected in freshly isolated human blood, the larger and less granular neutrophils may
have more prolonged survival and be more functional than the smaller and more
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