Phospholipase D activation by sphingosine 1-phosphate regulates interleukin-8 secretion in human bronchial epithelial cells.
Sphingosine 1-phosphate (S1P), a potent bioactive sphingolipid, has been implicated in many critical cellular events, including a regulatory role in the pathogenesis of airway inflammation. We investigated the participation of S1P as an inflammatory mediator by assessing interleukin-8 (IL-8) secretion and phospholipase D (PLD) activation in human bronchial epithelial cells (Beas-2B). S1P(1), S1P(3), S1P(4), S1P(5), and weak S1P(2) receptors were detected in Beas-2B and primary human bronchial epithelial cells. S1P stimulated a rapid activation of PLD, which was nearly abolished by pertussis toxin (PTX) treatment, consistent with S1P receptor/G(i) protein coupling. S1P also markedly induced Beas-2B secretion of IL-8, a powerful neutrophil chemoattractant and activator, in a PTX-sensitive manner. This S1P-mediated response was dependent on transcription as indicated by a strong induction of IL-8 promoter-mediated luciferase activity in transfected Beas-2B cells and a complete inhibition by actinomycin D. Beas-2B exposure to 1-butanol, which converts the PLD-generated phosphatidic acid (PA) to phosphatidylbutanol by a transphosphatidylation reaction, significantly attenuated the S1P-induced IL-8 secretion, indicating the involvement of PLD-derived PA in the signaling pathway. Inhibition of 12-O-tetradecanoyl-phorbol-13-acetate-stimulated IL-8 production by 1-butanol further strengthened this observation. Blocking protein kinase C and Rho kinase also attenuated S1P-induced IL-8 secretion. Our data suggest that PLD-derived PA, protein kinase C, and Rho are important signaling components in S1P-mediated IL-8 secretion by human bronchial epithelial cells.
Cummings
Rhett J
RJ
Department of Medicine, Division of Pulmonary and Critical Care Medicine, The Johns Hopkins University, Baltimore, Maryland 21224, USA.
Parinandi
Narasimham L
NL
Zaiman
Ari
A
Wang
Lixin
L
Usatyuk
Peter V
PV
Garcia
Joe G N
JG
Natarajan
Viswanathan
V
D001980:Bronchi / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism*; D008246:Lysophospholipids; D037342:Pertussis Toxin; D010739:Phospholipase D / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D016209:Interleukin-8; D008246:Lysophospholipids; D010566:Virulence Factors, Bordetella; C060506:sphingosine 1-phosphate; D037342:Pertussis Toxin; D011493:Protein Kinase C; D010739:Phospholipase D; D013110:Sphingosine