Phospholipid membranes drive abdominal aortic aneurysm development through stimulating coagulation factor activity
Allen-Redpath K., Aldrovandi M., Lauder SN., Gketsopoulou A., Tyrrell VJ., Slatter DA., Andrews R., Watkins WJ., Atkinson G., McNeill E., Gilfedder A., Protty M., Burston J., Johnson SRC., Rodrigues PRS., Jones DO., Lee R., Handa A., Channon K., Obaji S., Alvarez-Jarreta J., Krönke G., Ackermann J., Jenkins PV., Collins PW., O’Donnell VB.
<jats:p>Abdominal aortic aneurysm (AAA) is an inflammatory vascular disease with high mortality and limited treatment options. How blood lipids regulate AAA development is unknown. Here lipidomics and genetic models demonstrate a central role for procoagulant enzymatically oxidized phospholipids (eoxPL) in regulating AAA. Specifically, through activating coagulation, eoxPL either promoted or inhibited AAA depending on tissue localization. Ang II administration to <jats:italic>ApoE</jats:italic><jats:sup><jats:italic>−/−</jats:italic></jats:sup> mice increased intravascular coagulation during AAA development. Lipidomics revealed large numbers of eoxPL formed within mouse and human AAA lesions. Deletion of eoxPL-generating enzymes (<jats:italic>Alox12</jats:italic> or <jats:italic>Alox15</jats:italic>) or administration of the factor Xa inhibitor rivaroxaban significantly reduced AAA. <jats:italic>Alox</jats:italic>-deficient mice displayed constitutively dysregulated hemostasis, including a consumptive coagulopathy, characterized by compensatory increase in prothrombotic aminophospholipids (aPL) in circulating cell membranes. Intravenously administered procoagulant PL caused clotting factor activation and depletion, induced a bleeding defect, and significantly reduced AAA development. These data suggest that <jats:italic>Alox</jats:italic> deletion reduces AAA through diverting coagulation away from the vessel wall due to eoxPL deficiency, instead activating clotting factor consumption and depletion in the circulation. In mouse whole blood, ∼44 eoxPL molecular species formed within minutes of clot initiation. These were significantly elevated with <jats:italic>ApoE</jats:italic><jats:sup><jats:italic>−/−</jats:italic></jats:sup> deletion, and many were absent in <jats:italic>Alox</jats:italic><jats:sup><jats:italic>−/−</jats:italic></jats:sup> mice, identifying specific eoxPL that modulate AAA. Correlation networks demonstrated eoxPL belonged to subfamilies defined by oxylipin composition. Thus, procoagulant PL regulate AAA development through complex interactions with clotting factors. Modulation of the delicate balance between bleeding and thrombosis within either the vessel wall or circulation was revealed that can either drive or prevent disease development.</jats:p>