Airway iron and iron-regulatory cytokines in cystic fibrosis

Iron availability is critical to Pseudomonas aeruginosa. The current authors determined sputum iron, ferritin, microalbumin levels and total cell counts (TCC) in 19 adult patients with cystic fibrosis (CF) during an acute exacerbation and repeated analyses following a median of 12 days antibiotic treatment. The current authors also determined sputum interleukin (IL)-1β and tumour necrosis factor (TNF)-α levels because of their putative role in intracellular iron homeostasis. Additional data were obtained from 17 stable CF patients, eight patients with stable chronic obstructive pulmonary disease (COPD) and six normal subjects. Overall, sputum iron, ferritin, microalbumin, IL-1β and TNF-α concentrations and TCCs were significantly elevated in the CF patients compared to those with COPD and normal controls. Sputum ferritin levels were significantly elevated in acute versus stable CF patients and there was a trend for sputum TCC to be higher, but all other inflammatory indices were similar. In the CF patients, sputum iron was positively and strongly related to IL-1β, TNF-α, ferritin and microalbumin levels, but negatively related to forced expiratory volume in one second % predicted. In those acute patients who clinically improved with antibiotics (n=14), there were significant decreases in sputum TCC, iron, ferritin and IL-1β content, but not TNF-α or albumin levels. However, changes in sputum TNF-α in acute patients were still closely related to changes in iron, ferritin and albumin content, and changes in IL-1β were related to changes in sputum ferritin content. Iron and iron-regulatory cytokines may play a role in cystic fibrosis lung disease and the increased iron content may even facilitate Pseudomonas aeruginosa infection. © ERS Journals Ltd 2004.