Chemokine Signaling and the Management of Neuropathic Pain

Peripheral nerve demyelination induces CCR2. CCR2–mRNA is induced in both the site of the nerve injury and in the sensory neurons of the dorsal root ganglion (DRG), but not in the associated spinal cord. (A) Neither the MCP1 monomeric red fluorescent protein-1 (MCP1–mRFP1) nor the CCR2 extra green fluorescent protein CCR2–EGFP in transgenic mice subjected to LPC-induced demyelination of the sciatic nerve exhibited expression of MCP1 or CCR2 at a detectable level. Leukocytes outside the spinal cord were clearly visible (green arrow). (B–D) CCR2 expression was also examined at the mRNA level by in situ hybridization. The spinal cord does not contain significant CCR2-expressing cellular components (B), whereas many cells in the sciatic nerve (C) and DRG (D) express CCR2 receptors in the LPC group. DH, Dorsal horn; DC, dorsal column.