Cystic fibrosis / infection / iron overload

2006-01-04 11:35:33 PM
<<snip>>
ironoverload of the sputum of cystic fibrosis patients
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1: Int J Immunopathol Pharmacol. 2005 Oct-Dec;18(4):661-70. Links
Iron availability influences aggregation, biofilm, adhesion and
invasion of Pseudomonas aeruginosa and Burkholderia cenocepacia.
Berlutti F, Morea C, Battistoni A, Sarli S, Cipriani P, Superti F,
Ammendolia MG, Valenti P.
Department of Public Health Sciences, University of Rome, La Sapienza,
Italy.
Pseudomonas aeruginosa and Burkholderia cenocepacia are predominant
opportunistic pathogens in cystic fibrosis (CF) patients. In healthy
humans the lower respiratory tract as well as all mucosa, contains a
very low free iron concentration (10-18 M), while in CF patients sputum
iron concentration is very high, showing a median value of 63x10-6 M.
Accumulation of catalytic reactive iron heavily contributes to
subsequent clinical complications in the lung disorders by the
production of reactive oxygen species and increases bacterial growth
and virulence. The data reported in this study indicate that low iron
concentration (Fe3+ 1 muM)induced free-living forms and motility both
in P. aeruginosa and B. cenocepacia, while high iron concentrations
(Fe3+ 10 and 100 muM) stimulated aggregation and biofilm formation
already in the fluid phases, so demonstrating that aggregation and
biofilm formation are positively iron-modulated in these bacteria.
Moreover, the different morphological forms (free-living, aggregates
and biofilm) showed different capabilities of adhering and invading the
bronchial cell line A549. P. aeruginosa PAO1 aggregates, and mostly
biofilm, exerted the highest adhesion efficiency, while B. cenocepacia
PV1 aggregates or biofilm the lowest. A significant reduction in
invasion efficiency by P. aeruginosa biofilm and a significant increase
in cell internalization by B. cenocepacia biofilm has been reported.
Therefore, the iron availability is an important signal to which P.
aeruginosa and B. cenocepacia counteract by leaving the motile
free-living forms and entering into a new lifestyle, i.e. biofilm.
These data could contribute to explain that the ironoverload of the
sputum of CF patients, inducing nonmotile forms, aggregates and
biofilm, may facilitate penetration of host epithelial barriers
contributing to the establishment of infection, colonization,
persistence and systemic spread of these opportunistic pathogens.
PMID: 16388713 [PubMed - in process]
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