[HTML][HTML] Definition of a novel pathway centered on lysophosphatidic acid to recruit monocytes during the resolution phase of tissue inflammation

S McArthur, T Gobbetti, DHM Kusters… - The Journal of …, 2015 - journals.aai.org
S McArthur, T Gobbetti, DHM Kusters, CP Reutelingsperger, RJ Flower, M Perretti
The Journal of Immunology, 2015journals.aai.org
Blood-derived monocytes remove apoptotic cells and terminate inflammation in settings as
diverse as atherosclerosis and Alzheimer's disease. They express high levels of the
proresolving receptor ALX/FPR2, which is activated by the protein annexin A1 (ANXA1),
found in high abundance in inflammatory exudates. Using primary human blood monocytes
from healthy donors, we identified ANXA1 as a potent CD14+ CD16− monocyte
chemoattractant, acting via ALX/FPR2. Downstream signaling pathway analysis revealed …
Abstract
Blood-derived monocytes remove apoptotic cells and terminate inflammation in settings as diverse as atherosclerosis and Alzheimer’s disease. They express high levels of the proresolving receptor ALX/FPR2, which is activated by the protein annexin A1 (ANXA1), found in high abundance in inflammatory exudates. Using primary human blood monocytes from healthy donors, we identified ANXA1 as a potent CD14+ CD16− monocyte chemoattractant, acting via ALX/FPR2. Downstream signaling pathway analysis revealed the p38 MAPK-mediated activation of a calcium independent phospholipase A 2 with resultant synthesis of lysophosphatidic acid (LPA) driving chemotaxis through LPA receptor 2 and actin cytoskeletal mobilization. In vivo experiments confirmed ANXA1 as an independent phospholipase A 2–dependent monocyte recruiter; congruently, monocyte recruitment was significantly impaired during ongoing zymosan-induced inflammation in AnxA1−/− or alx/fpr2/3−/− mice. Using a dorsal air-pouch model, passive transfer of apoptotic neutrophils between AnxA1−/− and wild-type mice identified effete neutrophils as the primary source of soluble ANXA1 in inflammatory resolution. Together, these data elucidate a novel proresolving network centered on ANXA1 and LPA generation and identify previously unappreciated determinants of ANXA1 and ALX/FPR2 signaling in monocytes.
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