title: Oxidation increases mucin polymer cross-links to stiffen airway mucus gels.
abstract: Airway mucus in cystic fibrosis (CF) is highly elastic, but the mechanism behind this pathology is unclear. We hypothesized that the biophysical properties of CF mucus are altered because of neutrophilic oxidative stress. Using confocal imaging, rheology, and biochemical measures of inflammation and oxidation, we found that CF airway mucus gels have a molecular architecture characterized by a core of mucin covered by a web of DNA and a rheological profile characterized by high elasticity that can be normalized by chemical reduction. We also found that high levels of reactive oxygen species in CF mucus correlated positively and significantly with high concentrations of the oxidized products of cysteine (disulfide cross-links). To directly determine whether oxidation can cross-link mucins to increase mucus elasticity, we exposed induced sputum from healthy subjects to oxidizing stimuli and found a marked and thiol-dependent increase in sputum elasticity. Targeting mucin disulfide cross-links using current thiol-amino structures such as N-acetylcysteine (NAC) requires high drug concentrations to have mucolytic effects. We therefore synthesized a thiol-carbohydrate structure (methyl 6-thio-6-deoxy-α-D-galactopyranoside) and found that it had stronger reducing activity than NAC and more potent and fast-acting mucolytic activity in CF sputum. Thus, oxidation arising from airway inflammation or environmental exposure contributes to pathologic mucus gel formation in the lung, which suggests that it can be targeted by thiol-modified carbohydrates.
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94143, USA.
authors.forename: Shaopeng
authors.initials: S
authors.lastname: Yuan
authors.affiliation: Centre for Synthesis and Chemical Biology, School of Chemistry and Chemical Biology, University College Dublin, Dublin, Ireland.
authors.forename: Martin
authors.initials: M
authors.lastname: Hollinger
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.
authors.forename: Marrah E
authors.initials: ME
authors.lastname: Lachowicz-Scroggins
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.
authors.forename: Sheena C
authors.initials: SC
authors.lastname: Kerr
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.
authors.forename: Eleanor M
authors.initials: EM
authors.lastname: Dunican
authors.affiliation: Department of Respiratory Therapy, University of California, San Francisco, San Francisco, CA 94143, USA.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Daniel
authors.affiliation: Department of Pathobiology, Proteomics Laboratory, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Sudakshina
authors.initials: S
authors.lastname: Ghosh
authors.affiliation: Department of Pathobiology, Proteomics Laboratory, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Serpel C
authors.initials: SC
authors.lastname: Erzurum
authors.affiliation: Department of Pathobiology, Proteomics Laboratory, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA. Department of Cellular and Molecular Medicine, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Belinda
authors.initials: B
authors.lastname: Willard
authors.affiliation: Department of Cellular and Molecular Medicine, Cleveland Clinic, Cleveland, OH 44195, USA.
authors.forename: Stanley L
authors.initials: SL
authors.lastname: Hazen
authors.affiliation: Lung Biology Center, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.
authors.forename: Xiaozhu
authors.initials: X
authors.lastname: Huang
authors.affiliation: Veterinary Science Center, University College Dublin, Dublin, Ireland.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Carrington
authors.affiliation: Centre for Synthesis and Chemical Biology, School of Chemistry and Chemical Biology, University College Dublin, Dublin, Ireland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Oscarson
authors.affiliation: Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94143, USA. Division of Pulmonary and Critical Care Medicine, University of California, San Francisco, San Francisco, CA 94143, USA. john.fahy@ucsf.edu.
authors.forename: John V
authors.initials: JV
authors.lastname: Fahy
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D001696:Biomechanical Phenomena / Q000187:drug effects; D003432:Cross-Linking Reagents / Q000378:metabolism*; D003550:Cystic Fibrosis / Q000473:pathology / Q000503:physiopathology; D004247:DNA / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism; D004548:Elasticity / Q000187:drug effects; D005100:Expectorants / Q000494:pharmacology; D005690:Galactose / Q000737:chemistry / Q000494:pharmacology; D005782:Gels / Q000378:metabolism*; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000502:physiology*; D008810:Mice, Inbred C57BL; D009077:Mucins / Q000378:metabolism*; D009093:Mucus / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D011108:Polymers / Q000378:metabolism*; D019163:Reducing Agents / Q000494:pharmacology; D013183:Sputum / Q000187:drug effects; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000494:pharmacology
chemical_list: D003432:Cross-Linking Reagents; D004220:Disulfides; D005100:Expectorants; D005782:Gels; D009077:Mucins; D011108:Polymers; D019163:Reducing Agents; D013438:Sulfhydryl Compounds; D004247:DNA; D000111:Acetylcysteine; D005690:Galactose