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

Viruses are a major aetiological trigger for exacerbations 6, 7 and data exists to suggest that COPD may be associated with deficient anti-viral immunity 8, 9 . However, not all studies have shown this abnormality 10, 11 , suggesting that it may vary according to disease phenotype. Frequent exacerbators could represent one sub-group in whom defective anti-viral immunity is more prominent. Both experimental and naturally-occurring exacerbation studies also confirm that an initial virus infection can precipitate secondary bacterial infection in COPD 12, 13 with neutrophil elastase-induced cleavage of anti-microbial peptides believed to be important mechanistically 12 . Although bacterial colonisation at stable state has been shown to be associated with increased exacerbation frequency 14 , antimicrobial peptide responses and propensity to develop secondary bacterial infection during virusinfections in frequent versus infrequent exacerbators has not previously been studied.