TLR2 recognizes gram‐positive organisms and yeast, and promotes leukocyte recruitment. TGF β stimulates macrophage chemotaxis. Hyaluronan (HA), a glycosaminoglycan, also stimulates cell migration using Receptor for HA‐Mediated Motility (RHAMM). We hypothesized that TLR2 ligation leads to increased production of TGF β, which in turn stimulates macrophage chemotaxis in a RHAMM‐HA dependent manner.
... [Show full abstract] RAW 264.7 murine macrophages were stimulated with Pam3Cys, a specific TLR2 agonist. TGF β was measured using an ELISA. Chemotaxis was determined using a Boyden chamber, and cytoskeletal changes by phalliodin staining. Immunoblots with phospho‐specific antibodies examined signaling pathways. Antibodies to TGF β, RHAMM (R36), and HA‐binding peptide were used as blockers. Pam3Cys stimulation increased macrophage chemotaxis (optimal 5µM), a response that was blocked by anti‐TGFß and anti‐RHAMM antibodies, as well as HA‐binding peptide, but not by normal IgG or scrambled peptide. Pam3Cys also stimulated TGFß production and lamellaepodia. TGFß‐stimulated chemotaxis was also blocked by anti‐RHAMM Ab and HA‐binding peptide, but not by anti‐TLR2 Ab. TLR2 activation resulted in rapid phosphorylation of p38. We conclude that TLR2 signaling results in TGFß production and macrophage chemotaxis that is dependent on RHAMM:HA interactions. We speculate that RHAMM and HA play important roles in innate immune responses to bacterial challenge. Funded by NIH HL073986
