title: Anti-neuroinflammatory properties of synthetic cryptolepine in human neuroblastoma cells: possible involvement of NF-κB and p38 MAPK inhibition.
abstract: Cryptolepis sanguinolenta and its bioactive alkaloid, cryptolepine have shown anti-inflammatory activity. However, the underlying mechanism of anti-inflammatory action in neuronal cells has not been investigated. In the present study we evaluated an extract of C. sanguinolenta (CSE) and cryptolepine (CAS) on neuroinflammation induced with IL-1β in SK-N-SH neuroblastoma cells. We then attempted to elucidate the mechanisms underlying the anti-neuroinflammatory effects of CAS in SK-N-SH cells. Cells were stimulated with 10 U/ml of IL-1β in the presence or absence of different concentrations of CSE (25-200 μg/ml) and CAS (2.5-20 μM). After 24 h incubation, culture media were collected to measure the production of PGE2 and the pro-inflammatory cytokines (TNFα and IL-6). Protein and gene expressions of cyclooxygenase (COX-2) and microsomal prostaglandin synthase-1 (mPGES-1) were studied by immunoblotting and qPCR, respectively. CSE produced significant (p < 0.05) inhibition of TNFα, IL-6 and PGE2 production in SK-N-SH cells. Studies on CAS showed significant and dose-dependent inhibition of TNFα, IL-6 and PGE2 production in IL-1β-stimulated cells without affecting viability. Pre-treatment with CAS (10 and 20 μM) was also found to inhibit IL-1β-induced protein and gene expressions of COX-2 and mPGES-1. Further studies to determine the mechanism of action of CAS showed inhibition of NF-κBp65 nuclear translocation, but not IκB phosphorylation. At 10 and 20 μM, CAS inhibited IL-1β-induced phosphorylation of p38 MAPK. Studies on the downstream substrate of p38, MAPK-activated protein kinase 2 (MAPKAPK2) showed that CAS produced significant (p < 0.05) and dose dependent inhibition of MAPKAPK2 phosphorylation in IL-1β-stimulated SK-N-SH cells. This study clearly shows that cryptolepine (CAS) inhibits neuroinflammation through mechanisms involving inhibition of COX-2 and mPGES-1. It is suggested that these actions are probably mediated through NF-κB and p38 signalling.
authors.affiliation: Pharmacy and Pharmaceutical Sciences, School of Applied Sciences, University of Huddersfield, Huddersfield, West Yorkshire HD1 3DH, United Kingdom. o.a.olajide@hud.ac.uk
authors.forename: Olumayokun A
authors.initials: OA
authors.lastname: Olajide
authors.forename: Harsharan S
authors.initials: HS
authors.lastname: Bhatia
authors.forename: Antonio C P
authors.initials: AC
authors.lastname: de Oliveira
authors.forename: Colin W
authors.initials: CW
authors.lastname: Wright
authors.forename: Bernd L
authors.initials: BL
authors.lastname: Fiebich
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000893:Anti-Inflammatory Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D045744:Cell Line, Tumor; D031106:Cryptolepis / Q000737:chemistry; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D015151:Immunoblotting; D026121:Indole Alkaloids / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D053583:Interleukin-1beta / Q000494:pharmacology; D019746:Intramolecular Oxidoreductases / Q000235:genetics / Q000378:metabolism; D015394:Molecular Structure; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D000071876:Prostaglandin-E Synthases; D011804:Quinolines / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D051996:Transcription Factor RelA / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D000893:Anti-Inflammatory Agents; D016207:Cytokines; D026121:Indole Alkaloids; D053583:Interleukin-1beta; D010936:Plant Extracts; D011804:Quinolines; D051996:Transcription Factor RelA; C024015:cryptolepine; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D048051:p38 Mitogen-Activated Protein Kinases; D019746:Intramolecular Oxidoreductases; C000605862:PTGES protein, human; D000071876:Prostaglandin-E Synthases; D015232:Dinoprostone