title: Pro-inflammatory cytokines and lipopolysaccharide induce changes in cell morphology, and upregulation of ERK1/2, iNOS and sPLA₂-IIA expression in astrocytes and microglia.
abstract: BACKGROUND
  Activation of glial cells, including astrocytes and microglia, has been implicated in the inflammatory responses underlying brain injury and neurodegenerative diseases including Alzheimer's and Parkinson's diseases. Although cultured astrocytes and microglia are capable of responding to pro-inflammatory cytokines and lipopolysaccharide (LPS) in the induction and release of inflammatory factors, no detailed analysis has been carried out to compare the induction of iNOS and sPLA2-IIA. In this study, we investigated the effects of cytokines (TNF-alpha, IL-1beta, and IFN-gamma) and LPS + IFN-gamma to induce temporal changes in cell morphology and induction of p-ERK1/2, iNOS and sPLA₂-IIA expression in immortalized rat (HAPI) and mouse (BV-2) microglial cells, immortalized rat astrocytes (DITNC), and primary microglia and astrocytes.
  
  
  RESULTS
  Cytokines (TNF-alpha, IL-1beta, and IFN-gamma) and LPS + IFN-gamma induced a time-dependent increase in fine processes (filopodia) in microglial cells but not in astrocytes. Filopodia production was attributed to IFN-gamma and was dependent on ERK1/2 activation. Cytokines induced an early (15 min) and a delayed phase (1 ~ 4 h) increase in p-ERK1/2 expression in microglial cells, and the delayed phase increase corresponded to the increase in filopodia production. In general, microglial cells are more active in responding to cytokines and LPS than astrocytes in the induction of NO. Although IFN-gamma and LPS could individually induce NO, additive production was observed when IFN-gamma was added together with LPS. On the other hand, while TNF-alpha, IL-1beta, and LPS could individually induce sPLA₂-IIA mRNA and protein expression, this induction process does not require IFN-gamma. Interestingly, neither rat immortalized nor primary microglial cells were capable of responding to cytokines and LPS in the induction of sPLA2-IIA expression.
  
  
  CONCLUSIONS
  These results demonstrated the utility of BV-2 and HAPI cells as models for investigation on cytokine and LPS induction of iNOS, and DITNC astrocytes for induction of sPLA2-IIA. In addition, results further demonstrated that cytokine-induced sPLA2-IIA is attributed mainly to astrocytes and not microglial cells.
authors.affiliation: Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, USA.
authors.forename: Wenwen
authors.initials: W
authors.lastname: Sheng
authors.forename: Yijia
authors.initials: Y
authors.lastname: Zong
authors.forename: Arwa
authors.initials: A
authors.lastname: Mohammad
authors.forename: Deepa
authors.initials: D
authors.lastname: Ajit
authors.forename: Jiankun
authors.initials: J
authors.lastname: Cui
authors.forename: Dongdong
authors.initials: D
authors.lastname: Han
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Hamilton
authors.forename: Agnes
authors.initials: A
authors.lastname: Simonyi
authors.forename: Albert Y
authors.initials: AY
authors.lastname: Sun
authors.forename: Zezong
authors.initials: Z
authors.lastname: Gu
authors.forename: Jau-Shyong
authors.initials: JS
authors.lastname: Hong
authors.forename: Gary A
authors.initials: GA
authors.lastname: Weisman
authors.forename: Grace Y
authors.initials: GY
authors.lastname: Sun
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D048430:Cell Shape / Q000187:drug effects; D002478:Cells, Cultured; D016207:Cytokines / Q000276:immunology / Q000494:pharmacology*; D005260:Female; D054501:Group II Phospholipases A2 / Q000235:genetics / Q000378:metabolism*; D007249:Inflammation / Q000276:immunology; D007371:Interferon-gamma / Q000276:immunology / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism*; D011247:Pregnancy; D011554:Pseudopodia / Q000187:drug effects / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D016207:Cytokines; D008070:Lipopolysaccharides; D009569:Nitric Oxide; D007371:Interferon-gamma; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D054501:Group II Phospholipases A2