title: Toll-like receptor 2 (TLR2), transforming growth factor-β, hyaluronan (HA), and receptor for HA-mediated motility (RHAMM) are required for surfactant protein A-stimulated macrophage chemotaxis.
abstract: The innate immune system protects the host from bacterial and viral invasion. Surfactant protein A (SPA), a lung-specific collectin, stimulates macrophage chemotaxis. However, the mechanisms regulating this function are unknown. Hyaluronan (HA) and its receptors RHAMM (receptor for HA-mediated motility, CD168) and CD44 also regulate cell migration and inflammation. We therefore examined the role of HA, RHAMM, and CD44 in SPA-stimulated macrophage chemotaxis. Using antibody blockade and murine macrophages, SPA-stimulated macrophage chemotaxis was dependent on TLR2 but not the other SPA receptors examined. Anti-TLR2 blocked SPA-induced production of TGFβ. In turn, TGFβ1-stimulated chemotaxis was inhibited by HA-binding peptide and anti-RHAMM antibody but not anti-TLR2 antibody. Macrophages from TLR2(-/-) mice failed to migrate in response to SPA but responded normally to TGFβ1 and HA, effects that were blocked by anti-RHAMM antibody. Macrophages from WT and CD44(-/-) mice had similar responses to SPA, whereas those from RHAMM(-/-) mice had decreased chemotaxis to SPA, TGFβ1, and HA. In primary macrophages, SPA-stimulated TGFβ production was dependent on TLR2, JNK, and ERK but not p38. Pam3Cys, a specific TLR2 agonist, stimulated phosphorylation of JNK, ERK, and p38, but only JNK and ERK inhibition blocked Pam3Cys-stimulated chemotaxis. We have uncovered a novel pathway for SPA-stimulated macrophage chemotaxis where SPA stimulation via TLR2 drives JNK- and ERK-dependent TGFβ production. TGFβ1, in turn, stimulates macrophage chemotaxis in a RHAMM and HA-dependent manner. These findings are highly relevant to the regulation of innate immune responses by SPA with key roles for specific components of the extracellular matrix.
authors.affiliation: Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of the Sciences in Philadelphia, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Foley
authors.forename: David
authors.initials: D
authors.lastname: Lam
authors.forename: Hongmei
authors.initials: H
authors.lastname: Jiang
authors.forename: Jie
authors.initials: J
authors.lastname: Liao
authors.forename: Naeun
authors.initials: N
authors.lastname: Cheong
authors.forename: Theresa M
authors.initials: TM
authors.lastname: McDevitt
authors.forename: Aisha
authors.initials: A
authors.lastname: Zaman
authors.forename: Jo Rae
authors.initials: JR
authors.lastname: Wright
authors.forename: Rashmin C
authors.initials: RC
authors.lastname: Savani
mesh_terms: D000818:Animals; D002460:Cell Line; D002633:Chemotaxis; D003599:Cytoskeleton / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D055786:Gene Knockout Techniques; D018960:Hyaluronan Receptors / Q000235:genetics / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000378:metabolism / Q000502:physiology*; D008074:Lipoproteins / Q000494:pharmacology; D020935:MAP Kinase Signaling System; D008264:Macrophages / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008907:Mink; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011554:Pseudopodia / Q000378:metabolism / Q000502:physiology; D037662:Pulmonary Surfactant-Associated Protein A / Q000502:physiology*; D051195:Toll-Like Receptor 2 / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism / Q000502:physiology*
chemical_list: C476399:Cd44 protein, mouse; D016326:Extracellular Matrix Proteins; D018960:Hyaluronan Receptors; D008074:Lipoproteins; D037662:Pulmonary Surfactant-Associated Protein A; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D053773:Transforming Growth Factor beta1; C098946:hyaluronan-mediated motility receptor; C061108:N-palmitoyl-S-(2,3-bis(palmitoyloxy)propyl)cysteinyl-seryl-lysyl-lysyl-lysyl-lysine; D006820:Hyaluronic Acid; D020928:Mitogen-Activated Protein Kinases