title: S1PR5 is pivotal for the homeostasis of patrolling monocytes.
abstract: Patrolling Ly6C(-) monocytes are blood-circulating cells that play a role in inflammation and in the defense against pathogens. Here, we show that similar to natural killer (NK) cells, patrolling monocytes express high levels of S1PR5, a G-coupled receptor for sphingosine-1 phosphate. We found that S1pr5(-/-) mice lack peripheral Ly6C(-) monocytes but have a normal number of these cells in the bone marrow (BM). Various lines of evidence exclude a direct contribution of S1PR5 in the survival of Ly6C(-) monocytes at the periphery. Rather, our data support a role for S1PR5 in the egress of Ly6C(-) monocytes from the BM. In particular, we observed a reduced frequency of patrolling monocytes in BM sinusoids of S1PR5 KO mice. Unexpectedly, S1P was not a chemoattractant for patrolling monocytes and had no significant effect on their viability in vitro. Moreover, the disruption of S1P gradients in vivo did not alter Ly6C(-) monocyte trafficking and viability. These data suggest that S1PR5 regulates the trafficking of monocytes via a mechanism independent of S1P gradients.
authors.affiliation: Université de Lyon, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Debien
authors.forename: Katia
authors.initials: K
authors.lastname: Mayol
authors.forename: Vincent
authors.initials: V
authors.lastname: Biajoux
authors.forename: Cécile
authors.initials: C
authors.lastname: Daussy
authors.forename: Mercedes Gomez
authors.initials: MG
authors.lastname: De Aguero
authors.forename: Morgan
authors.initials: M
authors.lastname: Taillardet
authors.forename: Nicolas
authors.initials: N
authors.lastname: Dagany
authors.forename: Lilia
authors.initials: L
authors.lastname: Brinza
authors.forename: Thomas
authors.initials: T
authors.lastname: Henry
authors.forename: Bertrand
authors.initials: B
authors.lastname: Dubois
authors.forename: Dominique
authors.initials: D
authors.lastname: Kaiserlian
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Marvel
authors.forename: Karl
authors.initials: K
authors.lastname: Balabanian
authors.forename: Thierry
authors.initials: T
authors.lastname: Walzer
mesh_terms: D000818:Animals; D000950:Antigens, Ly / Q000378:metabolism*; D001775:Blood Circulation; D001853:Bone Marrow / Q000276:immunology*; D002465:Cell Movement / Q000276:immunology; D002470:Cell Survival; D002478:Cells, Cultured; D005260:Female; D006706:Homeostasis; D007157:Immunologic Surveillance; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009000:Monocytes / Q000276:immunology*; D049349:Receptors, Lysosphingolipid / Q000235:genetics / Q000378:metabolism*
chemical_list: D000950:Antigens, Ly; C494192:Ly-6C antigen, mouse; D049349:Receptors, Lysosphingolipid