Phagocytosis of Pseudomonas aeruginosa fails to elicit heat shock protein expression in human monocytes.
Phagocytosis represents a powerful stress for the phagocytic cells. Phagocytosis of Staphylococcus aureus induces a stress response associated with the synthesis of specific heat shock/stress proteins (HSP). Here we investigated the stress response of human monocyte-macrophages (m phi) to Pseudomonas aeruginosa, a bacterium found, as for S. aureus, in the airways of patients suffering cystic fibrosis. P. aeruginosa activated in m phi the production of both extra- and intracellular O2-; increased Interleukin-1 beta and actin, but failed to induce host HSP. Neither S. aureus' exotoxins nor the scavenging property of P. aeruginosa's alginate, but the lower toxicity of P. aeruginosa and/or differential activation of proteine kinase C (PKC) by the two bacteria, might explain their differences in host HSP induction. While O2- is insufficient to induce HSP synthesis in m phi, hydroxyl radicals, generated in the presence of exogenous iron, is a likely additional signal, along with PKC activation, for HSP induction during bacterial phagocytosis.
Barazzone
C
C
Allergy Unit, University Hospital, Geneva, Switzerland.
Kantengwa
S
S
Suter
S
S
Polla
B S
BS
D000818:Animals; D003550:Cystic Fibrosis / Q000378:metabolism / Q000382:microbiology; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis*; D006801:Humans; D051379:Mice; D009000:Monocytes / Q000378:metabolism*; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism; D010587:Phagocytosis; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011550:Pseudomonas aeruginosa / Q000276:immunology* / Q000378:metabolism; D013211:Staphylococcus aureus / Q000276:immunology / Q000378:metabolism
D018840:HSP70 Heat-Shock Proteins; D011493:Protein Kinase C; D010100:Oxygen