title: Inhibition of STAT3- and MAPK-dependent PGE2synthesis ameliorates phagocytosis of fibrillar β-amyloid peptide (1-42) via EP2 receptor in EMF-stimulated N9 microglial cells.
abstract: Prostaglandin E2(PGE2)-involved neuroinflammatory processes are prevalent in several neurological conditions and diseases. Amyloid burden is correlated with the activation of E-prostanoid (EP) 2 receptors by PGE2in Alzheimer's disease. We previously demonstrated that electromagnetic field (EMF) exposure can induce pro-inflammatory responses and the depression of phagocytosis in microglial cells, but the signaling pathways involved in phagocytosis of fibrillar β-amyloid (fAβ) in microglial cells exposed to EMF are poorly understood. Given the important role of PGE2in neural physiopathological processes, we investigated the PGE2-related signaling mechanism in the immunomodulatory phagocytosis of EMF-stimulated N9 microglial cells (N9 cells).
  
  
  
  N9 cells were exposed to EMF with or without pretreatment with the selective inhibitors of cyclooxygenase-2 (COX-2), Janus kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3), and mitogen-activated protein kinases (MAPKs) and antagonists of PG receptors EP1-4. The production of endogenous PGE2was quantified by enzyme immunoassays. The phagocytic ability of N9 cells was evaluated based on the fluorescence intensity of the engulfed fluorescent-labeled fibrillar β-amyloid peptide (1-42) (fAβ42) measured using a flow cytometer and a fluorescence microscope. The effects of pharmacological agents on EMF-activated microglia were investigated based on the expressions of JAK2, STAT3, p38/ERK/JNK MAPKs, COX-2, microsomal prostaglandin E synthase-1 (mPGES-1), and EP2 using real-time PCR and/or western blotting.
  
  
  
  EMF exposure significantly increased the production of PGE2and decreased the phagocytosis of fluorescent-labeled fAβ42by N9 cells. The selective inhibitors of COX-2, JAK2, STAT3, and MAPKs clearly depressed PGE2release and ameliorated microglial phagocytosis after EMF exposure. Pharmacological agents suppressed the phosphorylation of JAK2-STAT3 and MAPKs, leading to the amelioration of the phagocytic ability of EMF-stimulated N9 cells. Antagonist studies of EP1-4 receptors showed that EMF depressed the phagocytosis of fAβ42through the PGE2system, which is linked to EP2 receptors.
  
  
  
  This study indicates that EMF exposure could induce phagocytic depression via JAK2-STAT3- and MAPK-dependent PGE2-EP2 receptor signaling pathways in microglia. Therefore, pharmacological inhibition of PGE2synthesis and EP2 receptors may be a potential therapeutic strategy to combat the neurobiological deterioration that follows EMF exposure.
authors.affiliation: Department of Tropic Hygiene, Institute of Tropical Medicine, Third Military Medical University, 30 Gaotanyan Street, Chongqing, 400038, People's Republic of China.
authors.forename: Gen-Lin
authors.initials: GL
authors.lastname: He
authors.affiliation: Department of Tropic Hygiene, Institute of Tropical Medicine, Third Military Medical University, 30 Gaotanyan Street, Chongqing, 400038, People's Republic of China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Luo
authors.affiliation: Department of Tropic Hygiene, Institute of Tropical Medicine, Third Military Medical University, 30 Gaotanyan Street, Chongqing, 400038, People's Republic of China.
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Shen
authors.affiliation: Department of Tropic Hygiene, Institute of Tropical Medicine, Third Military Medical University, 30 Gaotanyan Street, Chongqing, 400038, People's Republic of China.
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.affiliation: Department of Tropic Hygiene, Institute of Tropical Medicine, Third Military Medical University, 30 Gaotanyan Street, Chongqing, 400038, People's Republic of China.
authors.forename: Ju
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Tropic Hygiene, Institute of Tropical Medicine, Third Military Medical University, 30 Gaotanyan Street, Chongqing, 400038, People's Republic of China.
authors.forename: Xue
authors.initials: X
authors.lastname: Luo
authors.affiliation: Key Laboratory of Medical Protection for Electromagnetic Radiation Ministry of Education, Third Military Medical University, Chongqing, 400038, People's Republic of China.
authors.forename: Chun-Hai
authors.initials: CH
authors.lastname: Chen
authors.affiliation: Key Laboratory of Medical Protection for Electromagnetic Radiation Ministry of Education, Third Military Medical University, Chongqing, 400038, People's Republic of China.
authors.forename: Peng
authors.initials: P
authors.lastname: Gao
authors.affiliation: Department of Tropic Hygiene, Institute of Tropical Medicine, Third Military Medical University, 30 Gaotanyan Street, Chongqing, 400038, People's Republic of China. xuesenyyy@aliyun.com.
authors.forename: Xue-Sen
authors.initials: XS
authors.lastname: Yang
mesh_terms: D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D000818:Animals; D002461:Cell Line, Transformed; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004574:Electromagnetic Fields; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000187:drug effects / Q000528:radiation effects; D051379:Mice; D017628:Microglia / Q000187:drug effects* / Q000528:radiation effects; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology*; D010587:Phagocytosis / Q000187:drug effects* / Q000528:radiation effects; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects; D013997:Time Factors
chemical_list: D016229:Amyloid beta-Peptides; D016207:Cytokines; D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D050796:STAT3 Transcription Factor; C075222:amyloid beta-protein (1-42); D009569:Nitric Oxide; D051546:Cyclooxygenase 2; D020929:Mitogen-Activated Protein Kinase Kinases; D015232:Dinoprostone
keywords: EMF; Microglia; PGE2; Phagocytosis; Synthesis