CCL2 and peripheral nerve injury: Nerve injury-induced axonal degeneration and subsequent axonal debris clearance were reduced in Tlr3−/− mice compared with wild-type mice. Nerve injury-induced macrophage infiltration into injury sites was also attenuated in Tlr3−/− mice, accompanied by reduced expression of the macrophage-recruiting chemokines, CCL2/MCP-1, CCL4/MIP-1β, and CCL5/RANTES. These data show that TLR3 signaling contributes to Wallerian degeneration after peripheral nerve injury by impacting Schwann cell activation and macrophage recruitment to injured nerves.