title: Repeated lipopolysaccharide stimulation induces cellular senescence in BV2 cells.
abstract: OBJECTIVE
  The dual action of microglia in neurodegenerating diseases has been controversial for some time. Recent studies indicate that microglia senescence might be the key determinant. When microglia age, they function abnormally and fail to respond correctly to stimuli, which eventually promotes neurodegeneration. Accumulating evidence has shown a close relationship between inflammation and aging. Since neuroinflammation is characterized by microglia activation, we assessed if the repeated activation of microglia would lead to senescence.
  
  
  METHODS
  The microglia cell line BV2 was repeatedly stimulated every 48 h with lipopolysaccharide (LPS; 10 ng/ml) and senescence was evaluated by β-galactosidase staining and the presence of senescence-associated heterochromatic foci as well as by cell cycle arrest detection by flow cytometry. The senescence-associated protein p53 was also detected by Western blot.
  
  
  RESULTS
  β-galactosidase staining was barely detectable in control cells, while it tended to increase with repeated LPS stimulation and was positive in most cells after stimulation with LPS 6 times. Similarly, senescence-associated heterochromatic foci were most prominent in cells repeatedly stimulated with LPS, while almost undetectable in control cells or cells receiving a single stimulation. p53 expression was highest in the cells that received LPS stimulation 6 times, and the largest number of cells arrested in the G0/G1 phase was observed in this same group.
  
  
  CONCLUSIONS
  Microglial cells tend to undergo senescence after repeated activation, implying that microglia senescence may start after multiple inflammatory challenges.
authors.affiliation: Department of Laboratory Medicine, First Affiliated Hospital of China Medical University, Shenyang, China.
authors.forename: Hong-Mei
authors.initials: HM
authors.lastname: Yu
authors.forename: Yan-Min
authors.initials: YM
authors.lastname: Zhao
authors.forename: Xiao-Guang
authors.initials: XG
authors.lastname: Luo
authors.forename: Yu
authors.initials: Y
authors.lastname: Feng
authors.forename: Yan
authors.initials: Y
authors.lastname: Ren
authors.forename: Hong
authors.initials: H
authors.lastname: Shang
authors.forename: Zhi-Yi
authors.initials: ZY
authors.lastname: He
authors.forename: Xiao-Meng
authors.initials: XM
authors.lastname: Luo
authors.forename: Sheng-Di
authors.initials: SD
authors.lastname: Chen
authors.forename: Xi-Yin
authors.initials: XY
authors.lastname: Wang
mesh_terms: D000818:Animals; D002460:Cell Line; D016922:Cellular Senescence / Q000187:drug effects / Q000276:immunology*; D005434:Flow Cytometry / Q000379:methods; D007249:Inflammation / Q000139:chemically induced / Q000276:immunology / Q000473:pathology; D008070:Lipopolysaccharides / Q000633:toxicity*; D051379:Mice; D017628:Microglia / Q000166:cytology / Q000187:drug effects / Q000276:immunology*
chemical_list: D008070:Lipopolysaccharides