A Novel Role for the AnxA1-Fpr2/ALX Signaling Axis as a Key Regulator of Platelet Function to Promote Resolution of Inflammation

ANSARI, JUNAID; AL-YAFEAI, ZAKI; STOKES, KAREN Y.; QIN, CHENG XUE; CUELLAR-SAENZ, HUGO H.; ORR, A. WAYNE; GAVINS, FELICITY N.E.; SENCHENKOVA, ELENA Y.; VITAL, SHANTEL A.; PAWLINSKI, RAFAL; DRAGOI, ANA-MARIA; SUN, HAI; HAN, YIPING W.; GRANGER, D. NEIL; BECKER, FELIX; SPARKENBAUGH, ERICA M.; CARROLL, JENNIFER L.; RITCHIE, REBECCA H.; RUBINSTEIN, MARA R.; PERRETTI, MAURO

CIRCULATION

LIPPINCOTT WILLIAMS & WILKINS

Lugar: Philadelphia; Año: 2019

0009-7322

BACKGROUND:Ischemia reperfusion injury (I/RI) is a common complication of cardiovascular diseases. Resolution of detrimental I/RI-generated pro-thrombotic and pro-inflammatory responses is essential to restore homeostasis. Platelets play a crucial part in the integration of thrombosis and inflammation. Their role as participants in the resolution of thrombo-inflammation is underappreciated, therefore we used pharmacological and genetic approaches, coupled with murine and clinical samples to uncover key concepts underlying this role.METHODS:Middle cerebral artery occlusion with reperfusion was performed in wild-type or AnxA1-knockout (AnxA1-/-) mice. Fluorescence intravital microscopy (IVM) was employed to a) visualize cellular trafficking and b) to monitor light/dye-induced thrombosis. Mice were treated with vehicle, AnxA1 (3.3 mg/kg) and/or WRW4 (1.8 mg/kg) and the effect of AnxA1 was determined in-vivo and in-vitro.RESULTS:IVM revealed heightened platelet adherence and aggregate formation post I/RI, which were further exacerbated in AnxA1-/- mice. AnxA1 administration regulated platelet function directly (e.g. via reducing thromboxane B2 and modulating phosphatidylserine [PS] expression) to promote cerebral protection post-I/RI and act as an effective preventative strategy for stroke by reducing platelet activation, aggregate formation, and cerebral thrombosis, a pre-requisite for ischemic stroke. To translate these findings into a clinical setting, we show AnxA1 plasma levels are reduced in human and murine stroke and that AnxA1 is able to act on human platelets, suppressing classic thrombin-induced inside-out signaling events (e.g. Akt activation, intracellular calcium release and Ras-associated protein 1 [Rap1] expression) to decrease αIIbβ3 activation without altering its surface expression. AnxA1 also selectively modifies cell surface determinants (e.g. PS) to promote platelet phagocytosis by neutrophils, thereby driving active resolution. (n=5-13 mice/group or 7-10 humans/group.) Conclusions: AnxA1 affords protection by altering the platelet phenotype in cerebral I/RI from pro-pathogenic to regulatory, and reducing the propensity for platelets to aggregate and cause thrombosis by affecting integrin (αIIbβ3) activation, a previously unknown phenomenon. Thus, our data reveal a novel multi-faceted role for AnxA1 to act both as a therapeutic and a prophylactic drug via its ability to promote endogenous pro-resolving, anti-thrombo-inflammatory circuits in cerebral I/RI. Collectively, these results further advance our knowledge and understanding in the field of platelet and Resolution Biology.