PT - JOURNAL ARTICLE AU - Norikazu Kiguchi AU - Yuka Kobayashi AU - Takehiko Maeda AU - Yohji Fukazawa AU - Kazuo Tohya AU - Michio Kimura AU - Shiroh Kishioka TI - Epigenetic Augmentation of the Macrophage Inflammatory Protein 2/C-X-C Chemokine Receptor Type 2 Axis through Histone H3 Acetylation in Injured Peripheral Nerves Elicits Neuropathic Pain AID - 10.1124/jpet.111.187724 DP - 2012 Mar 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 577--587 VI - 340 IP - 3 4099 - http://jpet.aspetjournals.org/content/340/3/577.short 4100 - http://jpet.aspetjournals.org/content/340/3/577.full SO - J Pharmacol Exp Ther2012 Mar 01; 340 AB - Although there is growing evidence showing that the involvement of chemokines in the pathogenesis of neuropathic pain is associated with neuroinflammation, the details are unclear. We investigated the C-X-C chemokine ligand type 2 [macrophage inflammatory protein 2 (MIP-2)]/C-X-C chemokine receptor type 2 (CXCR2) axis and epigenetic regulation of these molecules in neuropathic pain after peripheral nerve injury. Expression of MIP-2 and CXCR2 were up-regulated and localized on accumulated neutrophils and macrophages in the injured sciatic nerve (SCN) after partial sciatic nerve ligation (PSL). Perineural injection of MIP-2-neutralizing antibody (anti-MIP-2) or the CXCR2 antagonist N-(2-bromophenyl)-N′-(2-hydroxy-4-nitrophenyl)urea (SB225002) prevented PSL-induced tactile allodynia and thermal hyperalgesia. Perineural injection of recombinant MIP-2 elicited neuropathic pain-like behaviors. Anti-MIP-2 suppressed neutrophil accumulation in the SCN after PSL. Neutrophil depletion by intraperitoneal injection of Ly6G antibody attenuated PSL-induced neuropathic pain. Both anti-MIP-2 and SB225002 suppressed up-regulation of inflammatory cytokines and chemokines in the injured SCN. In addition, acetylation of histone H3 [lysine (Lys9)-acetylated histone H3 (AcK9-H3)] on the promoter region of MIP-2 and CXCR2 was increased in the injured SCN after PSL. Expression of AcK9-H3 was observed in the nuclei of neutrophils and macrophages surrounding the epineurium. Administration of the histone acetyltransferase inhibitor anacardic acid suppressed the up-regulation of MIP-2 and CXCR2 in the SCN after PSL and resulted in the prevention of PSL-induced neuropathic pain. Taken together, these results show that augmentation of the MIP-2/CXCR2 axis by hyperacetylation of histone H3 on the promoter region of MIP-2 and CXCR2 located in the injured peripheral nerve elicits chronic neuroinflammation through neutrophil accumulation, leading to neuropathic pain.