Pseudomonas aeruginosa slime glycolipoprotein is a potent stimulant of tumor necrosis factor alpha gene expression and activation of transcription activators nuclear factor kappa B and activator protein 1 in human monocytes.
Pseudomonas aeruginosa, an opportunistic pathogen, causes infections associated with a high incidence of morbidity and mortality in immunocompromised hosts. Production of tumor necrosis factor alpha (TNF-alpha), primarily by cells of monocytic lineage, is a crucial event in the course of these infections. During in vivo infections with P. aeruginosa, both lipopolysaccharide (LPS) and extracellular slime glycolipoprotein (GLP) produced by mucoid and nonmucoid strains are released. In the present study, we sought to explore the relative contributions of these two bacterial products to TNF-alpha production by human monocytes. To this end, fresh human monocytes and THP-1 human monocytic cells were stimulated with P. aeruginosa LPS or GLP. GLP was found to be a more potent stimulus for TNF-alpha production (threefold higher) by human monocytes than LPS. Moreover, its effect was comparable to that of viable bacteria. Quantitative mRNA analysis revealed predominantly transcriptional regulation. Electrophoretic mobility shift assays and transfection assays demonstrated activation of NF-kappa B and activator protein 1 (AP-1). NF-kappa B activation by GLP was rapid and followed the same time course as that by viable bacteria, suggesting that bacteria could directly activate NF-kappa B through GLP. Moreover P. aeruginosa GLP induced the formation of AP-1 complex with delayed kinetics compared with NF-kappa B but much more efficiently than the homologous LPS. These results identify GLP as the most important stimulant for TNF-alpha production by human monocytes. Activation of NF-kappa B and AP-1 by P. aeruginosa GLP may be involved not only in TNF-alpha induction but also in many of the inflammatory responses triggered in the course of infection with P. aeruginosa.
Lagoumintzis
George
G
University of Patras Medical School, Department of Microbiology, Patras 26500, Greece.
Christofidou
Myrto
M
Dimitracopoulos
George
G
Paliogianni
Fotini
F
D001426:Bacterial Proteins / Q000737:chemistry / Q000633:toxicity*; D002460:Cell Line; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D009000:Monocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D016328:NF-kappa B / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000276:immunology* / Q000472:pathogenicity*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics*; D014774:Virulence
D001426:Bacterial Proteins; D016328:NF-kappa B; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; C025431:extracellular slime proteins, bacterial