Sputum trace metals are biomarkers of inflammatory and suppurative lung disease.
BACKGROUND
Induced sputum cytology and protein biomarkers can be used to assess airways inflammation. Increases in sputum iron have been described in inflammatory lung disease. We hypothesized that other sputum metals may be affected by airways inflammation and investigated their potential value as biomarkers.


METHODS
Sputum was obtained from 20 healthy control subjects and from patients with inflammatory pulmonary diseases (23 with cystic fibrosis [CF], 16 with bronchiectasis, 17 with asthma, and 23 with COPD), and iron, zinc, manganese, and copper were measured. Fourteen patients with CF were also studied through an exacerbation cycle.


RESULTS
Sputum zinc and iron were elevated in CF and non-CF bronchiectasis vs controls (P < .001, zinc; P < .01 iron). Manganese was elevated in asthma (P < .01) and bronchiectasis (P < .05) vs controls. Copper was elevated in CF vs controls (P < .05). Zinc decreased (P < .01) following treatment of CF exacerbation. In subjects with CF zinc levels correlated with other biomarkers.


CONCLUSIONS
These results suggest a relationship of high concentrations of total zinc and iron with airways inflammation in CF and non-CF bronchiectasis, with longitudinal changes being observed in CF. Further work is required to elucidate potential inflammatory mechanisms related to these observations.
School of Molecular and Clinical Medicine, University of Edinburgh, Western General Hospital, Edinburgh, Scotland. r.d.gray@ed.ac.uk
Robert D
RD
Gray
Andrew
A
Duncan
Donald
D
Noble
Margaret
M
Imrie
Dennis St J
DS
O'Reilly
J Alastair
JA
Innes
David J
DJ
Porteous
Andrew P
AP
Greening
A Christopher
AC
Boyd
D000328:Adult; D000368:Aged; D001249:Asthma / Q000175:diagnosis* / Q000378:metabolism; D015415:Biomarkers / Q000032:analysis*; D001987:Bronchiectasis / Q000175:diagnosis* / Q000378:metabolism; D003300:Copper / Q000032:analysis; D003550:Cystic Fibrosis / Q000175:diagnosis* / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007501:Iron / Q000032:analysis; D008297:Male; D008345:Manganese / Q000032:analysis; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000378:metabolism; D015203:Reproducibility of Results; D013057:Spectrum Analysis; D013183:Sputum / Q000737:chemistry*; D013492:Suppuration; D014131:Trace Elements / Q000032:analysis*; D015032:Zinc / Q000032:analysis
D015415:Biomarkers; D014131:Trace Elements; D008345:Manganese; D003300:Copper; D007501:Iron; D015032:Zinc