Blood levels of serotonin are specifically correlated with plasma lysophosphatidylserine among the glycero-lysophospholipids

Backgrounds: Glycero-lysophospholipids (glycero-LPLs), which are known to exert potent biological activities, have been demonstrated to be secreted from activated platelets in vitro; however, their association with platelet activation in vivo has not been yet elucidated. In this study, we investigated the correlations between the blood levels of each glycero-LPL and serotonin, a biomarker of platelet activation, in human subjects to elucidate the involvement of platelet activation in glycero-LPLs in vivo. Methods and Results: We measured the plasma serotonin levels in 141 consecutive patients undergoing coronary angiography (acute coronary syndrome, n= 38; stable angina pectoris, n= 71; angiographically normal coronary arteries, n= 32) and investigated the correlations between the plasma levels of serotonin and glycero-LPLs. The results revealed the existence of a specific and significant association between the plasma serotonin and plasma lysophosphatidylserine (LysoPS) levels. On the contrary, regular aspirin intake failed to affect the plasma LysoPS levels despite the fact that the plasma lysophosphatidic acid, lysophosphatidylethanolamine, lysophosphatidylglycerol, and lysophosphatidylinositol levels were lower in those who had taken aspirin regularly. Conclusion: We found a specific positive correlation between the blood levels of serotonin and LysoPS, a new lipid mediator. Thus, LysoPS might be specifically involved in strong platelet activation, which is associated with the release of serotonin. General Significance: Our present results suggest the possible involvement of LysoPS in the pathogenesis of atherosclerotic diseases.