Targeting formyl peptide receptor 2 reduces leukocyte-endothelial interactions in a murine model of stroke

• Published in: The FASEB journal Vol. 29; no. 5; p. 2161
• Main Authors: Smith, Helen K, Gil, Cristiane Damas, Oliani, Sonia M, Gavins, Felicity N E
• Format: Journal Article
• Language: English
• Published: United States 01.05.2015
• Subjects: Adaptor Proteins, Signal Transducing - physiology; Animals; Annexin A1 - metabolism; Blotting, Western; Carotid Artery Diseases - pathology; Carotid Artery Diseases - prevention & control; Cell Adhesion; Cells, Cultured; Disease Models, Animal; Endothelium, Vascular - cytology; Endothelium, Vascular - metabolism; Fluorescent Antibody Technique; Humans; Immunoenzyme Techniques; Inflammation - pathology; Inflammation - prevention & control; Leukocytes - cytology; Leukocytes - metabolism; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Microscopy, Fluorescence; Microvessels - metabolism; Microvessels - pathology; Neutrophils - cytology; Neutrophils - metabolism; Peptide Fragments - pharmacology; Receptors, Formyl Peptide - physiology; Reperfusion Injury - pathology; Reperfusion Injury - prevention & control; Stroke - physiopathology; ischemia/reperfusion; FPR2/ALX; Annexin A1; inflammation
• ISSN: 1530-6860
• DOI: 10.1096/fj.14-263160

Ischemia/reperfusion (I/R) injury following stroke can worsen patient outcome through excess inflammation. This study investigated the pharmacologic potential of targeting an endogenous anti-inflammatory circuit via formyl peptide receptor (FPR) 2/lipoxin receptor (ALX) (Fpr2/3 in mouse) in global cerebral I/R. Mice (C57BL/6 and Fpr2/3(-/-)) were subjected to bilateral common carotid artery occlusion, followed by reperfusion and treatment with FPR agonists: AnxA1Ac2-26 [Annexin A1 mimetic peptide (Ac-AMVSEFLKQAWFIENEEQEYVQTVK), 2.5 μg/kg] and 15-epimer-lipoxin A4 (15-epi-LXA4; FPR2/ALX specific, 12.5 and 100 ng/kg). Leukocyte-endothelial (L-E) interactions in the cerebral microvasculature were then quantified in vivo using intravital fluorescence microscopy. 15-epi-LXA4 administration at the start of reperfusion reduced L-E interactions after 40 min (which was sustained at 2 h with high-dose 15-epi-LXA4) to levels seen in sham-operated animals. AnxA1Ac2-26 treatment decreased leukocyte adhesion at 40 min and all L-E interactions at 2 h (up to 95%). Combined treatment with AnxA1Ac2-26 plus FPR antagonists t-Boc-FLFLF (250 ng/kg) or WRW4 (FPR2/ALX selective, 1.4 μg/kg) abrogated the effects of AnxA1Ac2-26 fully at 40 min. Antagonists were less effective at 2 h, which we demonstrate is likely because of their impact on early L-E interactions. Our findings indicate that FPR2/ALX activity elicits considerable control over vascular inflammatory responses during cerebral I/R and, therefore, provide evidence that targeting FPR2/ALX may be beneficial for patients who suffered from stroke.