Exopolysaccharides from Burkholderia cenocepacia inhibit neutrophil chemotaxis and scavenge reactive oxygen species.
Bacteria belonging to the Burkholderia cepacia complex are important opportunistic pathogens in compromised hosts, particularly patients with cystic fibrosis or chronic granulomatous disease. Isolates of B. cepacia complex may produce large amounts of exopolysaccharides (EPS) that endow the bacteria with a mucoid phenotype and appear to facilitate bacterial persistence during infection. We showed that EPS from a clinical B. cenocepacia isolate interfered with the function of human neutrophils in vitro; it inhibited chemotaxis and production of reactive oxygen species (ROS), both essential components of innate neutrophil-mediated host defenses. These inhibitory effects were not due to cytotoxicity or interference with intracellular calcium signaling. EPS also inhibited enzymatic generation of ROS in cell-free systems, indicating that it scavenges these bactericidal products. B. cenocepacia EPS is structurally distinct from Pseudomonas aeruginosa alginate, yet they share the capacity to scavenge ROS and inhibit chemotaxis. These properties could explain why the two bacterial species resist clearance from the infected cystic fibrosis lung.
Bylund
Johan
J
Department of Pediatrics, University of British Columbia, Child and Family Research Institute, Vancouver, British Columbia V5Z 4H4, Canada.
Burgess
Lee-Anna
LA
Cescutti
Paola
P
Ernst
Robert K
RK
Speert
David P
DP
D019117:Burkholderia / Q000737:chemistry* / Q000276:immunology / Q000472:pathogenicity; D002633:Chemotaxis / Q000187:drug effects*; D016166:Free Radical Scavengers; D006801:Humans; D007113:Immunity, Innate; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology*; D011135:Polysaccharides, Bacterial / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism*
D016166:Free Radical Scavengers; D011135:Polysaccharides, Bacterial; D017382:Reactive Oxygen Species