title: The alpha 7 nicotinic receptor agonist PHA-543613 hydrochloride inhibits Porphyromonas gingivalis-induced expression of interleukin-8 by oral keratinocytes.
abstract: OBJECTIVE
  The alpha 7 nicotinic receptor (α7nAChR) is expressed by oral keratinocytes. α7nAChR activation mediates anti-inflammatory responses. The objective of this study was to determine if α7nAChR activation inhibited pathogen-induced interleukin-8 (IL-8) expression by oral keratinocytes.
  
  
  METHODS
  Periodontal tissue expression of α7nAChR was determined by real-time PCR. OKF6/TERT-2 oral keratinocytes were exposed to Porphyromonas gingivalis in the presence and absence of a α7nAChR agonist (PHA-543613 hydrochloride) alone or after pre-exposure to a specific α7nAChR antagonist (α-bungarotoxin). Interleukin-8 (IL-8) expression was measured by ELISA and real-time PCR. Phosphorylation of the NF-κB p65 subunit was determined using an NF-κB p65 profiler assay and STAT-3 activation by STAT-3 in-cell ELISA. The release of ACh from oral keratinocytes in response to P. gingivalis lipopolysaccharide was determined using a GeneBLAzer M3 CHO-K1-bla cell reporter assay.
  
  
  RESULTS
  Expression of α7nAChR mRNA was elevated in diseased periodontal tissue. PHA-543613 hydrochloride inhibited P. gingivalis-induced expression of IL-8 at the transcriptional level. This effect was abolished when cells were pre-exposed to a specific α7nAChR antagonist, α-bungarotoxin. PHA-543613 hydrochloride downregulated NF-κB signalling through reduced phosphorylation of the NF-κB p65-subunit. In addition, PHA-543613 hydrochloride promoted STAT-3 signalling by maintenance of phosphorylation. Furthermore, oral keratinocytes upregulated ACh release in response to P. gingivalis lipopolysaccharide.
  
  
  CONCLUSIONS
  These data suggest that α7nAChR plays a role in regulating the innate immune responses of oral keratinocytes.
authors.affiliation: Infection and Immunity Research Group, Glasgow Dental School, School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Level 9, 378 Sauchiehall Street, Glasgow, G2 3JZ, UK.
authors.forename: Alexandrea
authors.initials: A
authors.lastname: Macpherson
authors.forename: Noha
authors.initials: N
authors.lastname: Zoheir
authors.forename: Raja Azman
authors.initials: RA
authors.lastname: Awang
authors.forename: Shauna
authors.initials: S
authors.lastname: Culshaw
authors.forename: Gordon
authors.initials: G
authors.lastname: Ramage
authors.forename: David F
authors.initials: DF
authors.lastname: Lappin
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Nile
mesh_terms: D000109:Acetylcholine / Q000276:immunology; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002038:Bungarotoxins / Q000494:pharmacology; D016466:CHO Cells; D003412:Cricetulus; D006801:Humans; D016209:Interleukin-8 / Q000276:immunology*; D015603:Keratinocytes / Q000187:drug effects / Q000276:immunology*; D008070:Lipopolysaccharides; D009061:Mouth Mucosa / Q000166:cytology; D010510:Periodontal Diseases / Q000235:genetics / Q000276:immunology; D016966:Porphyromonas gingivalis; D011812:Quinuclidines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000276:immunology; D051996:Transcription Factor RelA / Q000276:immunology; D064569:alpha7 Nicotinic Acetylcholine Receptor / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology*
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D002038:Bungarotoxins; C508606:CXCL8 protein, human; D016209:Interleukin-8; D008070:Lipopolysaccharides; C513163:N-(1-azabicyclo(2.2.2)oct-3-yl)furo(2,3-c)pyridine-5-carboxamide; D011812:Quinuclidines; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D051996:Transcription Factor RelA; D064569:alpha7 Nicotinic Acetylcholine Receptor; D000109:Acetylcholine