Inflammation Research

, Volume 60, Issue 8, pp 735–744 | Cite as

Lipopolysaccharide and platelet-activating factor stimulate expression of platelet-activating factor acetylhydrolase via distinct signaling pathways

  • Katherine M. Howard
  • Mohammed Abdel-al
  • Marcia Ditmyer
  • Nipa Patel
Original Research Paper



This study was designed to investigate and characterize the ability of platelet-activating factor (PAF) to induce the expression of platelet-activating factor acetylhydrolase (PAF-AH).


Ribonuclease protection assays and quantitative real-time PCR were used to investigate the ability of lipopolysaccharide (LPS) and PAF to regulate PAF-AH mRNA expression in human monocyte–macrophage 6 (MM6) cells. Pharmacological inhibitors of mitogen activated protein kinases (MAPK) and PAF receptor antagonists were used to investigate the mechanism of regulation of PAF-AH.


PAF-AH mRNA levels were increased upon exposure to LPS or PAF in a dose-dependent manner. LPS elicited a more potent and rapid increase in PAF-AH expression than the PAF-stimulated response. However, when administered concomitantly, PAF augmented the LPS-stimulated response. LPS-stimulated PAF-AH expression was susceptible to partial inhibition by a p38 MAPK inhibitor and PAF receptor antagonists. PAF-induced up-regulation of PAF-AH levels was solely mediated via the PAF receptor and was p38 MAPK-independent.


The proinflammatory mediators, LPS and PAF, increased levels of PAF-AH mRNA via distinct signaling pathways.


PAF acetylhydrolase Regulation Lipopolysaccharide Mitogen activated protein kinase PAF receptor 



We would like to express our sincere gratitude to Merle S. Olson, University of Texas Health Science Center, who donated much of the equipment to our laboratory to conduct this research. We would like to thank Ziming Cheng for technical help with the RPA assays and Drs. Gillian Galbraith and Barbara St Pierre Schneider for critically reading the manuscript. This work was supported by grants from the National Institutes of Health (HL66130) and the American Heart Association (0465061) to KMH.

Conflict of interest

The authors declare that they have no competing interests.


  1. 1.
    McManus LM, Pinckard RN. PAF, a putative mediator of oral inflammation. Crit Rev Oral Biol Med. 2000;11:240–58.PubMedCrossRefGoogle Scholar
  2. 2.
    Hargreaves DC, Medzhitov R. Innate sensors of microbial infection. J Clin Immunol. 2005;25:503–10.PubMedCrossRefGoogle Scholar
  3. 3.
    Castro Faria Neto HC, Stafforini DM, Prescott SM, Zimmerman GA. Regulating inflammation through the anti-inflammatory enzyme platelet-activating factor-acetylhydrolase. Mem Inst Oswaldo Cruz. 2005;100(Suppl 1):83–91.PubMedGoogle Scholar
  4. 4.
    Snyder F, Blank M, Lee TC, Robinson M, Woodard D. Measurement of key enzyme activities involved in the metabolism of platelet activating factor. Methods Enzymol. 1987;141:379–96.PubMedCrossRefGoogle Scholar
  5. 5.
    Stafforini DM, Prescott SM, Zimmerman GA, McIntyre TM. Mammalian platelet-activating factor acetylhydrolases. Biochim Biophys Acta. 1996;1301:161–73.PubMedGoogle Scholar
  6. 6.
    Farr RS, Cox CP, Wardlow ML, Jorgensen R. Preliminary studies of an acid-labile factor (ALF) in human sera that inactivates platelet-activating factor (PAF). Clin Immunol Immunopathol. 1980;15:318–30.PubMedCrossRefGoogle Scholar
  7. 7.
    Tjoelker LW, Wilder C, Eberhardt C, Stafforini DM, Dietsch G, Schimpf B, et al. Anti-inflammatory properties of a platelet-activating factor acetylhydrolase (see comments). Nature. 1995;374:549–53.PubMedCrossRefGoogle Scholar
  8. 8.
    Asano K, Okamoto S, Fukunaga K, Shiomi T, Mori T, Iwata M, et al. Cellular source(s) of platelet-activating-factor acetylhydrolase activity in plasma. Biochem Biophys Res Commun. 1999;261:511–4.PubMedCrossRefGoogle Scholar
  9. 9.
    Stafforini DM, McIntyre TM, Zimmerman GA, Prescott SM. Platelet-activating factor acetylhydrolases. J Biol Chem. 1997;272:17895–8.PubMedCrossRefGoogle Scholar
  10. 10.
    Imaizumi TA, Stafforini DM, Yamada Y, McIntyre TM, Prescott SM, Zimmerman GA. Platelet-activating factor: a mediator for clinicians. J Intern Med. 1995;238:5–20.PubMedCrossRefGoogle Scholar
  11. 11.
    Howard KM, Miller JE, Miwa M, Olson MS. Cell-specific regulation of expression of plasma-type platelet-activating factor acetylhydrolase in the liver. J Biol Chem. 1997;272:27543–8.PubMedCrossRefGoogle Scholar
  12. 12.
    Howard KM, Olson MS. The expression and localization of plasma platelet-activating factor acetylhydrolase in endotoxemic rats. J Biol Chem. 2000;275:19891–6.PubMedCrossRefGoogle Scholar
  13. 13.
    Cao Y, Stafforini DM, Zimmerman GA, McIntyre TM, Prescott SM. Expression of plasma platelet-activating factor acetylhydrolase is transcriptionally regulated by mediators of inflammation. J Biol Chem. 1998;273:4012–20.PubMedCrossRefGoogle Scholar
  14. 14.
    Narahara H, Johnston JM. Effects of endotoxins and cytokines on the secretion of platelet-activating factor-acetylhydrolase by human decidual macrophages. Am J Obstet Gynecol. 1993;169:531–7.PubMedGoogle Scholar
  15. 15.
    Chomczynski P, Sacchi N. Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. Anal Biochem. 1987;162:156–9.PubMedCrossRefGoogle Scholar
  16. 16.
    Guha M, Mackman N. LPS induction of gene expression in human monocytes. Cell Signal. 2001;13:85–94.PubMedCrossRefGoogle Scholar
  17. 17.
    Wu X, Zimmerman GA, Prescott SM, Stafforini DM. The p38 MAPK pathway mediates transcriptional activation of the plasma platelet-activating factor acetylhydrolase gene in macrophages stimulated with lipopolysaccharide. J Biol Chem. 2004;279:36158–65.PubMedCrossRefGoogle Scholar
  18. 18.
    Jungi TW, Brcic M, Eperon S. Human macrophages respond to LPS in a serum-independent, CD14-dependent manner. Immunol Lett. 1996;54:37–43.PubMedCrossRefGoogle Scholar
  19. 19.
    Zipfel A, Schenk M, Metzdorf B, Bode C, Viebahn R. Release of TNF-alpha from lipopolysaccharide (LPS)-stimulated Kupffer cells in serum- and nutrient-free medium. Inflammation. 2001;25:287–92.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Basel AG 2011

Authors and Affiliations

  • Katherine M. Howard
    • 1
  • Mohammed Abdel-al
    • 2
  • Marcia Ditmyer
    • 1
  • Nipa Patel
    • 1
  1. 1.Department of Biomedical SciencesUniversity of Nevada Las Vegas School of Dental MedicineLas VegasUSA
  2. 2.Department of ChemistryUniversity of Nevada Las Vegas School of Dental MedicineLas VegasUSA

Personalised recommendations