title: Induction of dendritic cell maturation by pertussis toxin and its B subunit differentially initiate Toll-like receptor 4-dependent signal transduction pathways.
abstract: OBJECTIVE
  Pertussis toxin (PT) has the capacity to activate dendritic cells (DCs) for the augmentation of cell-mediated immune responses. To investigate the mechanism(s) by which PT activates DCs, we investigated the effects of PT and its B-oligomer (PTB) on the maturation of human and mouse DCs and determined whether PT could act as a pathogen-associated molecular pattern to activate one of the Toll-like receptors (TLRs).
  
  
  METHODS
  The effects of PT and PTB on the maturation of human and mouse DCs were analyzed in terms of surface marker expression, cytokine production, antigen-presenting capacity, and intracellular signaling. The participation of TLR4 in PT-induced signaling was determined by comparing the effect of PT on DCs derived from TLR4-deficient and wild-type mice, as well as by measuring PT-induced NF-kappaB activation in HEK293 cells transiently transfected to express various TLRs.
  
  
  RESULTS
  Although both promoted phenotypic and functional maturation DCs, however, unlike PT that induced DC production of interleukin (IL)-6, tumor necrosis factor-alpha, IL-12, and interferon-inducible protein, PTB was capable of stimulating the production of interferon-inducible protein. Bone marrow-derived DCs from C3H/HeJ mice with defective TLR-4 alleles were unresponsive to PT and PTB, whereas DCs from C3H/HeN mice responded. In addition, PT induced NF-kappaB activation and IL-8 production in HEK293 cells transfected with a combination of TLR4 and MD2 but not in nontransfected or TLR2-transfected HEK293 cells. Comparison of the patterns of cytokine induction and intracellular signaling events in DCs treated by PT and PTB revealed that although PT, like lipopolysaccharide, triggered both MyD88-dependent and -independent pathways, PTB preferentially triggered MyD88-independent pathways. Interestingly, mouse splenocyte proliferation in response to PT and PTB was only partially dependent on TLR4.
  
  
  CONCLUSIONS
  The data identify PT as another pathogen-associated molecular pattern that induces DC maturation in a TLR4-dependent manner. Unlike PT, which triggers both MyD88-dependent and -independent pathways, PTB only triggers the MyD88-independent pathway in DCs.
authors.affiliation: Intramural Basic Research Program, SAIC-Frederick, Inc, USA.
authors.forename: Zhao Yuan
authors.initials: ZY
authors.lastname: Wang
authors.forename: De
authors.initials: D
authors.lastname: Yang
authors.forename: Qian
authors.initials: Q
authors.lastname: Chen
authors.forename: Cindy A
authors.initials: CA
authors.lastname: Leifer
authors.forename: David M
authors.initials: DM
authors.lastname: Segal
authors.forename: Shao Bo
authors.initials: SB
authors.lastname: Su
authors.forename: Rachel R
authors.initials: RR
authors.lastname: Caspi
authors.forename: Zack O M
authors.initials: ZO
authors.lastname: Howard
authors.forename: Joost J
authors.initials: JJ
authors.lastname: Oppenheim
mesh_terms: D000818:Animals; D003713:Dendritic Cells / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D008809:Mice, Inbred C3H; D037342:Pertussis Toxin / Q000494:pharmacology*; D021122:Protein Subunits; D015398:Signal Transduction / Q000502:physiology*; D051197:Toll-Like Receptor 4 / Q000502:physiology*; D014162:Transfection
chemical_list: D021122:Protein Subunits; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D037342:Pertussis Toxin