PT - JOURNAL ARTICLE AU - Jane F. Chisholm AU - Siddharth K. Shenoy AU - Julie K. Shade AU - Victor Kim AU - Nirupama Putcha AU - Kathryn A. Carson AU - Robert Wise AU - Nadia N. Hansel AU - Justin S. Hanes AU - Jung Soo Suk AU - Enid Neptune TI - Nanoparticle diffusion in spontaneously expectorated sputum as a biophysical tool to probe disease severity in COPD AID - 10.1183/13993003.00088-2019 DP - 2019 Aug 01 TA - European Respiratory Journal PG - 1900088 VI - 54 IP - 2 4099 - http://erj.ersjournals.com/content/54/2/1900088.short 4100 - http://erj.ersjournals.com/content/54/2/1900088.full SO - Eur Respir J2019 Aug 01; 54 AB - Perturbations in airway mucus properties contribute to lung function decline in patients with chronic obstructive pulmonary disease (COPD). While alterations in bulk mucus rheology have been widely explored, microscopic mucus properties that directly impact on the dynamics of microorganisms and immune cells in the COPD lungs are yet to be investigated.We hypothesised that a tightened mesh structure of spontaneously expectorated mucus (i.e. sputum) would contribute to increased COPD disease severity. Here, we investigated whether the mesh size of COPD sputum, quantified by muco-inert nanoparticle (MIP) diffusion, correlated with sputum composition and lung function measurements.The microstructure of COPD sputum was assessed based on the mean squared displacement (MSD) of variously sized MIPs measured by multiple particle tracking. MSD values were correlated with sputum composition and spirometry. In total, 33 samples collected from COPD or non-COPD individuals were analysed.We found that 100 nm MIPs differentiated microstructural features of COPD sputum. The mobility of MIPs was more hindered in sputum samples from patients with severe COPD, suggesting a tighter mucus mesh size. Specifically, MSD values inversely correlated with lung function.These findings suggest that sputum microstructure may serve as a novel risk factor for COPD progression and severity.Microstructural properties of COPD sputum probed by motility of 100 nm muco-inert particles correlate with disease severity characterised by pulmonary lung function http://bit.ly/2WOf7yF