Conserved nontypeable Haemophilus influenzae-derived TLR2-binding lipopeptides synergize with IFN-beta to increase cytokine production by resident murine and human alveolar macrophages.
Nontypeable Haemophilus influenzae (NTHi) is strongly associated with exacerbations of chronic obstructive pulmonary disease, which often coincide with viral respiratory infections. TLR2 contributes importantly to innate immunity to NTHi, but whether this pathway is affected by simultaneous antiviral responses is unknown. To analyze potential interactions, resident murine and human alveolar macrophages (AMphi) were exposed, in the presence or absence of the appropriate rIFN-beta, to synthetic lipopeptides corresponding to the triacylated N-terminal fragments of three outer membrane proteins (OMP) (PCP, P4, and P6) that are highly conserved among different NTHi strains. Synthetic OMP elicited strong release of IL-6, the principal inducer of airway mucin genes, and induced CCL5 and CXCL10 from murine AMphi only when IFN-beta was also present. Surprisingly, combined stimulation by OMPs and IFN-beta also markedly enhanced TNF-alpha release by murine AMphi. Stimulation with PCP plus IFN-beta induced IFN-regulatory factor 1 expression and sustained STAT1 activation, but did not alter the activation of MAPKs or NF-kappaB. AMphi derived from STAT1-deficient mice did not demonstrate increased production of TNF-alpha in response to PCP plus IFN-beta. Analysis of wild-type and STAT1-deficient AMphi using real-time PCR showed that increased TNF-alpha production depended on transcriptional up-regulation, but not on mRNA stabilization. The synergistic effect of synthetic OMP and IFN-beta was conserved between murine AMphi and human AMphi for IL-6, but not for TNF-alpha. Thus, IFN-beta, which is produced by virally infected respiratory epithelial cells, converts normally innocuous NTHi OMP into potent inflammatory stimulants, but does so via different mechanisms in mice and humans.
Punturieri
Antonello
A
Pulmonary and Critical Care Medicine Section, and Research Service, Department of Veterans Affairs Health System, VA Medical Center, 2215 Fuller Road, Ann Arbor, MI 48105, USA. puntieria@nih.nhlbi.gov
Copper
Phil
P
Polak
Timothy
T
Christensen
Paul J
PJ
Curtis
Jeffrey L
JL
D000276:Adjuvants, Immunologic / Q000378:metabolism / Q000502:physiology*; D000368:Aged; D000818:Animals; D001422:Bacterial Adhesion / Q000235:genetics / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism / Q000502:physiology*; D002460:Cell Line; D045744:Cell Line, Tumor; D017124:Conserved Sequence; D016207:Cytokines / Q000096:biosynthesis*; D005260:Female; D006193:Haemophilus influenzae / Q000145:classification / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D007370:Interferon Type I / Q000494:pharmacology; D016899:Interferon-beta / Q000502:physiology*; D008074:Lipoproteins / Q000378:metabolism / Q000502:physiology*; D016676:Macrophages, Alveolar / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor / Q000502:physiology; D051195:Toll-Like Receptor 2 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology*
D000276:Adjuvants, Immunologic; D001425:Bacterial Outer Membrane Proteins; D016207:Cytokines; D018836:Inflammation Mediators; D007370:Interferon Type I; D008074:Lipoproteins; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; C494080:Stat1 protein, mouse; C495342:TLR2 protein, human; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D014409:Tumor Necrosis Factor-alpha; D016899:Interferon-beta