A large number of different biologically active molecules can be produced from arachidonic acid. In resting cells, the levels of free arachidonic acid are kept low by rapid reacylation which sequesters them in the phospholipid pool. After activation of cPLA2α, the rate of liberation of arachidonic acid becomes faster than the rate of reacylation, and results in a large amount of free arachidonic acid. Some of the arachidonic acid is converted to eicosanoids, but the remainder is reacylated and returned to the phospholipid pool. Until recently it was not easy to investigate this highly dynamic phenomenon to answer questions such as, from which phospholipid pools is arachidonic acid liberated upon stimulation? Does the liberated arachidonic acid return to the same phospholipid pools it came from? Do other acceptors of arachidonic acid come into play when free arachidonic acid levels are high?
Current advances in HPLC ESI MS/MS now allow questions like these to be answered with relative ease. Balgoma, et al (1) investigated the arachidonic acid response of monocytes in response to stimuli like zymosan and platelet activating factor. This group demonstrates that, in response to different stimuli, cPLA¬2α hydrolyzes different pools of phospholipids that contain arachidonic acid. They also demonstrate increases in specific pools of phospholipids containing arachidonic acid after monocytes are activated, indicating that additional phospholipid acceptors have become available for esterification. Further, the authors describe how the increase in particular arachidonic acid-containing phospholipids can be used as markers for monocyte activation. Overall the manuscript illustrates the power of HPLC ESI MS/MS in the field of lipidomic analysis, and demonstrates that it is now possible to use this technology to answer complex biological questions.
Balgoma D, Astudillo AM, Pérez-Chacón G, Montero O, Balboa MA, Balsinde JMarkers of monocyte activation revealed by lipidomic profiling of arachidonic acid-containing phospholipids. J Immunol. 2010 Apr 1;184(7):3857-65. Epub 2010 Feb 24.
PMID: 20181887
Reviewed by: Dayanjan S. Wijesinghe, Nadia F. Lamour and Charles E. Chalfantm, Virginia Commonwealth University.
Posted on: 01 April 2010