Macrorheology of cystic fibrosis, chronic obstructive pulmonary disease and normal sputum

Serisier, David J., Carroll, Mary P., Shute, Janis K. and Young, Simon A. (2009) Macrorheology of cystic fibrosis, chronic obstructive pulmonary disease and normal sputum. Respiratory Research, 10 63: 63-1-63-8. doi:10.1186/1465-9921-10-63


Author Serisier, David J.
Carroll, Mary P.
Shute, Janis K.
Young, Simon A.
Title Macrorheology of cystic fibrosis, chronic obstructive pulmonary disease and normal sputum
Journal name Respiratory Research   Check publisher's open access policy
ISSN 1465-9921
1465-993X
Publication date 2009-07-01
Year available 2009
Sub-type Article (original research)
DOI 10.1186/1465-9921-10-63
Open Access Status DOI
Volume 10
Issue 63
Start page 63-1
End page 63-8
Total pages 8
Editor Jan Lötvall
Place of publication London, United Kingdom
Publisher Biomed Central
Collection year 2010
Language eng
Subject 920115 Respiratory System and Diseases (incl. Asthma)
110203 Respiratory Diseases
Formatted abstract
Background
Prior microrheologic assessments of selected, microlitre plugs of cystic fibrosis (CF) sputum suggest no intrinsic rheologic abnormality. However, such analyses may not be representative of CF sputum as a whole. We therefore reassessed this question using whole sputum macrorheology. Additionally, we wished to further explore the relationships between sputum rheology, inflammation and infection.

Methods
Dynamic oscillatory macrorheometry was performed on whole expectorated sputum from stable adults with CF (n = 18) and COPD (n = 12) and induced sputum from normal controls (n = 7). Concomitant sputum inflammatory mediator levels were measured in CF and COPD samples. Sputum collected from CF subjects (n = 6) at commencement and completion of intravenous antibiotic therapy for an infective exacerbation was also assessed.

Results
CF sputum neutrophil elastase activity (NE) was significantly related to degree of sputum purulence (p = 0.049) and correlated significantly with measures of sputum viscoelasticity (r = 0.696, p = 0.008 for storage modulus G' at 9 Hz). There were significant differences in viscoelasticity between subject groups when samples were compared irrespective of appearance/degree of sputum purulence. However, the macrorheology of mucoid CF sputum did not differ from normal sputum (eg median (range) G' at 9 Hz 2.25 (0.79, 3.26) vs 2.04 (1.4,4.6) Pa, p = 1). In contrast, mucoid COPD samples demonstrated significantly greater viscoelasticity (G' at 9 Hz 4.5 (2.4, 23) Pa) than sputum from both CF (p = 0.048) & normal subjects (p = 0.009). Antibiotic therapy during exacerbations was associated with significant reductions in CF sputum viscoelasticity, with mean (SD) G' at 9 Hz decreasing from 28.5 (11.5) Pa at commencement to 6.4 (4.6) Pa on day 7 (p = 0.01).

Conclusion
The macrorheologic properties of whole, mucoid CF sputum are not different from normal, confirming the results of prior microrheologic studies. Instead, CF sputum viscoelasticity is related to secondary infection, decreases with intravenous antibiotic therapy and correlates with inflammation. In contrast, COPD sputum demonstrates inherently greater viscoelasticity, providing a novel target for potential therapeutic interventions.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2010 Higher Education Research Data Collection
School of Medicine Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 10 times in Thomson Reuters Web of Science Article | Citations
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Created: Thu, 08 Apr 2010, 02:02:35 EST by Maree Knight on behalf of Medicine - Princess Alexandra Hospital