title: Inhibition of EGFR/MAPK signaling reduces microglial inflammatory response and the associated secondary damage in rats after spinal cord injury.
abstract: BACKGROUND
  Emerging evidence indicates that reactive microglia-initiated inflammatory responses are responsible for secondary damage after primary traumatic spinal cord injury (SCI); epidermal growth factor receptor (EGFR) signaling may be involved in cell activation. In this report, we investigate the influence of EGFR signaling inhibition on microglia activation, proinflammatory cytokine production, and the neuronal microenvironment after SCI.
  
  
  METHODS
  Lipopolysaccharide-treated primary microglia/BV2 line cells and SCI rats were used as model systems. Both C225 and AG1478 were used to inhibit EGFR signaling activation. Cell activation and EGFR phosphorylation were observed after fluorescent staining and western blot. Production of interleukin-1 beta (IL-1 β) and tumor necrosis factor alpha (TNF α) was tested by reverse transcription PCR and ELISA. Western blot was performed to semi-quantify the expression of EGFR/phospho-EGFR, and phosphorylation of Erk, JNK and p38 mitogen-activated protein kinases (MAPK). Wet-dry weight was compared to show tissue edema. Finally, axonal tracing and functional scoring were performed to show recovery of rats.
  
  
  RESULTS
  EGFR phosphorylation was found to parallel microglia activation, while EGFR blockade inhibited activation-associated cell morphological changes and production of IL-1 β and TNF α. EGFR blockade significantly downregulated the elevated MAPK activation after cell activation; selective MAPK inhibitors depressed production of cytokines to a certain degree, suggesting that MAPK mediates the depression of microglia activation brought about by EGFR inhibitors. Subsequently, seven-day continual infusion of C225 or AG1478 in rats: reduced the expression of phospho-EGFR, phosphorylation of Erk and p38 MAPK, and production of IL-1 β and TNF α; lessened neuroinflammation-associated secondary damage, like microglia/astrocyte activation, tissue edema and glial scar/cavity formation; and enhanced axonal outgrowth and functional recovery.
  
  
  CONCLUSIONS
  These findings indicate that inhibition of EGFR/MAPK suppresses microglia activation and associated cytokine production; reduces neuroinflammation-associated secondary damage, thus provides neuroprotection to SCI rats, suggesting that EGFR may be a therapeutic target, and C225 and AG1478 have potential for use in SCI treatment.
authors: Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China.
authors: Wen-Sheng
authors: WS
authors: Qu
authors: Dai-Shi
authors: DS
authors: Tian
authors: Zhi-Bao
authors: ZB
authors: Guo
authors: Jun
authors: J
authors: Fang
authors: Qiang
authors: Q
authors: Zhang
authors: Zhi-Yuan
authors: ZY
authors: Yu
authors: Min-Jie
authors: MJ
authors: Xie
authors: Hua-Qiu
authors: HQ
authors: Zhang
authors: Jia-Gao
authors: JG
authors: Lü
authors: Wei
authors: W
authors: Wang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000502:physiology*; D007249:Inflammation / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D008297:Male; D017628:Microglia / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D011799:Quinazolines / Q000494:pharmacology / Q000627:therapeutic use; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013119:Spinal Cord Injuries / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D020032:Tyrphostins / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D004791:Enzyme Inhibitors; D011799:Quinazolines; D020032:Tyrphostins; C101044:RTKI cpd; C483803:Egfr protein, rat; D066246:ErbB Receptors