title: Toll-like receptor 2 contributes to chemokine gene expression and macrophage infiltration in the dorsal root ganglia after peripheral nerve injury.
abstract: BACKGROUND
  We have previously reported that nerve injury-induced neuropathic pain is attenuated in toll-like receptor 2 (TLR2) knock-out mice. In these mice, inflammatory gene expression and spinal cord microglia actvation is compromised, whereas the effects in the dorsal root ganglia (DRG) have not been tested. In this study, we investigated the role of TLR2 in inflammatory responses in the DRG after peripheral nerve injury.
  
  
  RESULTS
  L5 spinal nerve transection injury induced the expression of macrophage-attracting chemokines such as CCL2/MCP-1 and CCL3/MIP-1 and subsequent macrophage infiltration in the DRG of wild-type mice. In TLR2 knock-out mice, however, the induction of chemokine expression and macrophage infiltration following nerve injury were markedly reduced. Similarly, the induction of IL-1β and TNF-α expression in the DRG by spinal nerve injury was ameliorated in TLR2 knock-out mice. The reduced inflammatory response in the DRG was accompanied by attenuation of nerve injury-induced spontaneous pain hypersensitivity in TLR2 knock-out mice.
  
  
  CONCLUSIONS
  Our data show that TLR2 contributes to nerve injury-induced proinflammatory chemokine/cytokine gene expression and macrophage infiltration in the DRG, which may have relevance in the reduced pain hypersensitivity in TLR2 knock-out mice after spinal nerve injury.
authors.affiliation: Department of Neuroscience and Oral Physiology, and Dental Research Institute, School of Dentistry, Seoul National University, 28 Yeongun-dong Jongno-gu, Seoul, 110-749, Republic of Korea.
authors.forename: Donghoon
authors.initials: D
authors.lastname: Kim
authors.forename: Byunghyun
authors.initials: B
authors.lastname: You
authors.forename: Hyoungsub
authors.initials: H
authors.lastname: Lim
authors.forename: Sung Joong
authors.initials: SJ
authors.lastname: Lee
mesh_terms: D000818:Animals; D018932:Chemokine CCL2 / Q000378:metabolism; D054405:Chemokine CCL3 / Q000378:metabolism; D018925:Chemokines / Q000235:genetics / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005727:Ganglia, Spinal / Q000166:cytology* / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism*; D008297:Male; D051379:Mice; D059348:Peripheral Nerve Injuries / Q000276:immunology* / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D018932:Chemokine CCL2; D054405:Chemokine CCL3; D018925:Chemokines; D053583:Interleukin-1beta; D051195:Toll-Like Receptor 2; D014409:Tumor Necrosis Factor-alpha