Targeting AnxA1/Formyl Peptide Receptor 2 Pathway Affords Protection against Pathological Thrombo-Inflammation

Abstract

Stroke is a leading cause of death and disability globally and is associated with a number of co-morbidities including sepsis and sickle cell disease (SCD). Despite thrombo-inflammation underlying these co-morbidities, its pathogenesis remains complicated and drug discovery programs aimed at reducing and resolving the detrimental effects remain a major therapeutic challenge. The objective of this study was to assess whether the anti-inflammatory pro-resolving protein Annexin A1 (AnxA1) was able to reduce inflammation-induced thrombosis and suppress platelet activation and thrombus formation in the cerebral microvasculature. Using two distinct models of pathological thrombo-inflammation (lipopolysaccharide (LPS) and sickle transgenic mice (STM)), thrombosis was induced in the murine brain using photoactivation (light/dye) coupled with intravital microscopy. The heightened inflammation-induced microvascular thrombosis present in these two distinct thrombo-inflammatory models was inhibited significantly by the administration of AnxA1 mimetic peptide AnxA1Ac2-26 (an effect more pronounced in the SCD model vs. the endotoxin model) and mediated by the key resolution receptor, Fpr2/ALX. Furthermore, AnxA1Ac2-26 treatment was able to hamper platelet aggregation by reducing platelet stimulation and aggregation (by moderating αIIbβ3 and P-selectin). These findings suggest that targeting the AnxA1/Fpr2/ALX pathway represents an attractive novel treatment strategy for resolving thrombo-inflammation, counteracting e.g., stroke in high-risk patient cohorts.

The impact of thrombo‐inflammation on the cerebral microcirculation

“…These mediators act on different stages of the inflammatory cascade, restoring physiological responses by, for example, reducing neutrophil recruitment, inhibiting cytokine release, promoting apoptosis and phagocytosis, decreasing vascular permeability, regulating neutrophil‐platelet complexes, and delaying the overall cerebral thrombotic responses 7,8,57,107,108 . More specifically, in our study models, we have shown that Annexin A1 (and its N‐terminal–derived peptide) modifies neutrophil‐platelet interaction by activating the Annexin A1/FPR‐2 pathway in both neutrophils and platelets, with AnxA1 administration leading to reduced platelet activation and aggregate formation, delayed thrombosis, and enhanced platelet phagocytosis by neutrophils 7,106 . Some of these mechanisms were dependent upon AKT, intracellular Ca 2+ , and Rap1 and suggested a role for Annexin A1 to affect integrin ( α IIb β 3 ) activation 7 .…”

“…(and its N-terminal-derived peptide) modifies neutrophil-platelet interaction by activating the Annexin A1/FPR-2 pathway in both neutrophils and platelets, with AnxA1 administration leading to reduced platelet activation and aggregate formation, delayed thrombosis, and enhanced platelet phagocytosis by neutrophils. 7,106 Some of these mechanisms were dependent upon AKT, intracellular Ca 2+ , and Rap1 and suggested a role for Annexin A1 to affect integrin (α IIb β 3 ) activation. 7 In addition, we also showed that aspirin-triggered lipoxin, a specific FPR-2, markedly attenuated inflammatory responses, including neutrophil-platelet aggregates in a murine model of ischemic stroke.…”

“…Endogenous‐specialized pro‐resolving mediators which enhance the ability of vascular milieu to clear inflammatory phase and enable homeostasis have shown to be of benefit in many pre‐clinical models of vascular inflammation 54,105,106 . These mediators act on different stages of the inflammatory cascade, restoring physiological responses by, for example, reducing neutrophil recruitment, inhibiting cytokine release, promoting apoptosis and phagocytosis, decreasing vascular permeability, regulating neutrophil‐platelet complexes, and delaying the overall cerebral thrombotic responses 7,8,57,107,108 .…”

Special Issue “Recent Developments in Annexin Biology”

“…They identify the importance of this process and demonstrate the role of this process in facilitating embryo implantation in the uterus at the blastocyst stage. Vital et al [11] examined another aspect of FPR-AnxA1-its involvement in thrombus-induced inflammation during sepsis and sickle cell disease. Using intravital imaging together with an AnxA1 mimetic peptide, they observe that targeting this signaling through the Fpr2/ALX receptor helps reduce the severity of the inflammatory response.…”

Regulation of Inflammation and Oxidative Stress by Formyl Peptide Receptors in Cardiovascular Disease Progression

“…In fact, ANXA1 and its N-terminal peptides (Ac 2-26 and Ac 9-25 ) are endogenous anti-inflammatory and proresolving mediators, known to have significant effects in resolving inflammation in a variety of disease models and showing therapeutic potential in IRI [ 33 ]. ANXA1 has also protective role in myocardial infarction (MI) and stroke [ 34 ]. SAA is a sensitive marker of an acute inflammatory state [ 35 ] and although it is mainly associated with amyloidosis, it is involved in early atherogenic processes [ 36 ] and represents a marker of cardiovascular events [ 37 , 38 ].…”