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. Author manuscript; available in PMC: 2020 Feb 21.
Published in final edited form as: Eur Respir J. 2018 Oct 10;52(4):1801118. doi: 10.1183/13993003.01118-2018

Figure 4. Roles of myeloperoxidase and methionine sulfoxide in the development of early CF bronchiectasis.

Figure 4.

Neutrophil (PMN) recruitment to airways may occur in early CF without an obvious pathogenic stimulus. In the current study, methionine sulfoxide (MetO) in early CF BALF was correlated strongly with CT scores of bronchiectasis. Following influx of neutrophils that secrete myeloperoxidase (MPO) into the lumen, oxidizing activity of MPO may generate MetO from methionine. MPO generates hypochlorous and hypobromous acid, which cause rapid, frequently irreversible damage to an array of biomolecules including tissue macromolecules. The oxidizing activity of MPO provides a common link between MetO and tissue injury which may lead to bronchiectasis. These processes may be insufficiently resolved in early CF and contribute to a feed-forward mechanism underlying sustained PMN recruitment. Whether MetO may directly participate in the promotion of CF airway disease is unclear at this time.