TY - JOUR
T1 - Lysophosphatidic acid induces thrombogenic activity through phosphatidylserine exposure and procoagulant microvesicle generation in human erythrocytes
AU - Chung, Seung Min
AU - Bae, Ok Nam
AU - Lim, Kyung Min
AU - Noh, Ji Yoon
AU - Lee, Moo Yeol
AU - Jung, Yi Sook
AU - Chung, Jin Ho
PY - 2007/2
Y1 - 2007/2
N2 - OBJECTIVE - Although erythrocytes have been suggested to play a role in blood clotting, mediated through phosphatidylserine (PS) exposure and/or PS-bearing microvesicle generation, an endogenous substance that triggers the membrane alterations leading to a procoagulant activity in erythrocytes has not been reported. We now demonstrated that lysophosphatidic acid (LPA), an important lipid mediator in various pathophysiological processes, induces PS exposure and procoagulant microvesicle generation in erythrocytes, which represent a biological significance resulting in induction of thrombogenic activity. METHODS AND RESULTS - In human erythrocytes, LPA treatment resulted in PS exposure on remnant cells and PS-bearing microvesicle generation in a concentration-dependent manner. Consistent with the microvesicle generation, scanning electron microscopic study revealed that LPA treatment induced surface changes, alteration of normal discocytic shape into echinocytes followed by spherocytes. Surprisingly, chelation of intracellular calcium did not affect LPA-induced PS exposure and microvesicle generation. On the other hand, protein kinase C (PKC) inhibitors significantly reduced PS exposure and microvesicle generation induced by LPA, reflecting the role of calcium-independent PKC. Activation of PKC was confirmed by Western blot analysis showing translocation of calcium-independent isoform, PKCζ, to erythrocyte membrane. The activity of flippase, which is important in the maintenance of membrane asymmetry, was also inhibited by LPA. Furthermore, LPA-exposed erythrocytes actually potentiated the thrombin generation as determined by prothrombinase assay and accelerated the coagulation process initiated by recombinant human tissue factor in plasma. The adherence of erythrocytes to endothelial cells, another important feature of thrombogenic process, was also stimulated by LPA treatment. CONCLUSION - These results suggested that LPA-exposed erythrocytes could make an important contribution to thrombosis mediated through PS exposure and procoagulant microvesicle generation.
AB - OBJECTIVE - Although erythrocytes have been suggested to play a role in blood clotting, mediated through phosphatidylserine (PS) exposure and/or PS-bearing microvesicle generation, an endogenous substance that triggers the membrane alterations leading to a procoagulant activity in erythrocytes has not been reported. We now demonstrated that lysophosphatidic acid (LPA), an important lipid mediator in various pathophysiological processes, induces PS exposure and procoagulant microvesicle generation in erythrocytes, which represent a biological significance resulting in induction of thrombogenic activity. METHODS AND RESULTS - In human erythrocytes, LPA treatment resulted in PS exposure on remnant cells and PS-bearing microvesicle generation in a concentration-dependent manner. Consistent with the microvesicle generation, scanning electron microscopic study revealed that LPA treatment induced surface changes, alteration of normal discocytic shape into echinocytes followed by spherocytes. Surprisingly, chelation of intracellular calcium did not affect LPA-induced PS exposure and microvesicle generation. On the other hand, protein kinase C (PKC) inhibitors significantly reduced PS exposure and microvesicle generation induced by LPA, reflecting the role of calcium-independent PKC. Activation of PKC was confirmed by Western blot analysis showing translocation of calcium-independent isoform, PKCζ, to erythrocyte membrane. The activity of flippase, which is important in the maintenance of membrane asymmetry, was also inhibited by LPA. Furthermore, LPA-exposed erythrocytes actually potentiated the thrombin generation as determined by prothrombinase assay and accelerated the coagulation process initiated by recombinant human tissue factor in plasma. The adherence of erythrocytes to endothelial cells, another important feature of thrombogenic process, was also stimulated by LPA treatment. CONCLUSION - These results suggested that LPA-exposed erythrocytes could make an important contribution to thrombosis mediated through PS exposure and procoagulant microvesicle generation.
KW - Erythrocyte
KW - Lysophosphatidic acid
KW - Microvesicle
KW - Phosphatidylserine
KW - Thrombogenic activity
UR - http://www.scopus.com/inward/record.url?scp=33846444733&partnerID=8YFLogxK
U2 - 10.1161/01.ATV.0000252898.48084.6a
DO - 10.1161/01.ATV.0000252898.48084.6a
M3 - Article
C2 - 17110600
AN - SCOPUS:33846444733
SN - 1079-5642
VL - 27
SP - 414
EP - 421
JO - Arteriosclerosis, Thrombosis, and Vascular Biology
JF - Arteriosclerosis, Thrombosis, and Vascular Biology
IS - 2
ER -