title: [Toll-like receptor 4 expression and cytokine secretion in microglial cells induced by IgG stimulation].
abstract: OBJECTIVE
  To investigate the effects of immunoglobulin G (IgG) on the expression of toll-like receptor 4 (TLR4) and secretion of cytokines in microglial cells in vitro.
  
  
  METHODS
  Cultured primary rat microglial cells were stimulated with different concentrations of rat IgG (2 mg/L, 20 mg/L, 200 mg/L) and lipopolysaccharide (LPS) 10 mg/L for 24 h, respectively. The TLR4 expression in the microglial cells was examined by immunofluorescence staining and tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) levels in the culture medium were assayed by ELISA.
  
  
  RESULTS
  IgG stimulation induced a significant TLR4 expression and TNF-alpha secretion in cultured microglial cells in a dose-dependent manner, while IFN-gamma was not detected in the same medium samples. As a positive control, LPS caused increases of TLR4 expression and both IFN-gamma and TNF-alpha production in the microglial cells.
  
  
  CONCLUSIONS
  TLR4 expression could be induced in microglia in vitro by non-pathogenic protein, IgG from the same species. Therefore, congeneric IgG stimulation might lead to proinflammmatory cytokine production, probably via MyD88-dependent pathway. This finding suggests that TLR4 may play more roles than pathogen recognition of innate immune reactivity, at least in the central nervous system.
authors.affiliation: College of Veterinary Medicine, Northwest A&F University, Yangling, China. wur2003@163.com
authors.forename: Rui
authors.initials: R
authors.lastname: Wu
authors.forename: Ling
authors.initials: L
authors.lastname: Liu
authors.forename: Zheng-wu
authors.initials: ZW
authors.lastname: Peng
authors.forename: Xiao-li
authors.initials: XL
authors.lastname: Duan
authors.forename: Bai-ren
authors.initials: BR
authors.lastname: Wang
authors.forename: Ya-ping
authors.initials: YP
authors.lastname: Jin
authors.forename: Fang
authors.initials: F
authors.lastname: Kuang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D007074:Immunoglobulin G / Q000494:pharmacology*; D007371:Interferon-gamma / Q000378:metabolism; D017628:Microglia / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D016207:Cytokines; D007074:Immunoglobulin G; C495347:Tlr4 protein, rat; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma