title: Mechanisms of anti-inflammatory property of Anacardium occidentale stem bark: inhibition of NF-κB and MAPK signalling in the microglia.
abstract: BACKGROUND
  Anacardium occidentale is used in traditional African medicine for the treatment of arthritis, fever, aches, pains, and inflammation of the extremities.
  
  
  OBJECTIVE
  In this study, we investigated the molecular mechanisms responsible for anti-inflammatory effects of a stem bark extract of A. occidentale (ANE) in LPS-stimulated microglia.
  
  
  METHODS
  Nitric oxide (NO), prostaglandin E(2) and cytokine (TNFα and IL-6) production were evaluated in supernatants from LPS-stimulated BV-2 cells. Cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) and microsomal prostaglandin E2 synthase (mPGES-1) protein expressions in rat primary microglia were measured using western blot. The effects of ANE on NF-κB activation and nuclear translocation were evaluated in the luciferase reporter gene assay and ELISA, while ability of ANE to influence IκB phosphorylation was determined using ELISA specific for phospho-IκB. The involvement of MAPK phosphorylation in the anti-inflammatory actions of ANE was evaluated using specific ELISA for phospho-p38, phospho-p42/44 and phospho-JNK. The MTT assay was used to determine the effect of ANE on BV-2 microglia viability.
  
  
  RESULTS
  ANE (25-100 μg/ml) produced significant (p<0.05) reduction in the production of NO, PGE(2), TNFα and IL-6 in BV-2 microglia stimulated with LPS for 24h. Pre-treatment with ANE caused a significant (p<0.05) inhibition of COX-2, iNOS and mPGES-1 protein expressions in the rat primary microglia. Further experiments showed that ANE inhibited COX-2 and iNOS protein expression via IκB-mediated nuclear translocation and transactivation of NF-κB. Our studies also revealed that ANE produced significant (p<0.05) and dose-dependent inhibition of p38, p42/44 and JNK MAPK phosphorylation in LPS-activated BV-2 microglia.
  
  
  CONCLUSIONS
  We conclude that ANE has an anti-inflammatory property related to inhibition of inflammation-associated cytokine production as well as iNOS and COX-2 gene expression by blocking NF-κB and MAPK pathways in the microglia. It is also suggested that mPGES-1 inhibition contributes to the effect of ANE on PGE(2) production in the microglia.
authors.affiliation: Division of Pharmacy and Pharmaceutical Science, School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, United Kingdom. o.a.olajide@hud.ac.uk
authors.forename: Olumayokun A
authors.initials: OA
authors.lastname: Olajide
authors.forename: Mutalib A
authors.initials: MA
authors.lastname: Aderogba
authors.forename: Bernd L
authors.initials: BL
authors.lastname: Fiebich
mesh_terms: D031021:Anacardium / Q000737:chemistry; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D051379:Mice; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000893:Anti-Inflammatory Agents; D016207:Cytokines; D016328:NF-kappa B; D010936:Plant Extracts; D009569:Nitric Oxide; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D020928:Mitogen-Activated Protein Kinases; D015232:Dinoprostone