Anti-microbial immunity is impaired in COPD patients with frequent exacerbations

Aran Singanayagam; Su-Ling Loo; Maria Calderazzo; Lydia J Finney; Maria-Belen Trujillo Torralbo; Eteri Bakhsoliani; Jason Girkin; Punnam Veerati; Prabuddha S Pathinayake; Kristy S Nichol; Andrew Reid; Joseph Foottit; Sebastian L Johnston; Nathan W Bartlett; Patrick Mallia

We have previously reported that rhinovirus-induced secondary bacterial infection occurs through neutrophil elastase-mediated cleavage and reduction of the anti-microbial peptides (AMPs) SLPI and elafin, a process that occurs in COPD but not healthy subjects and may be further accentuated by inhaled corticosteroid use 21 . Given our observation of increased bacterial loads in frequent exacerbators, we next examined whether this sub-group of COPD patients have concurrently reduced SLPI and elafin levels. There were no differences in sputum SLPI or elafin levels between frequent and infrequent exacerbators either at baseline ( Supplementary Fig 2a-b) or during exacerbation ( Supplementary Fig 1c-d) . This suggested that differential expression of these AMPs does not underlie increased secondary bacterial infection in frequent exacerbators.