title: The antimicrobial peptide cathelicidin interacts with airway mucus.
abstract: Antimicrobial peptides (AMPs) and mucins are components of airway secretions and both contribute to the innate host defense system. At neutral pH, AMPs are positively charged, mucins negatively. It was the aim of the study to test whether these opposite charges result in interactions between AMPs and mucins. We measured binding of mucins isolated from porcine gastric mucosa to the cathelicidin LL-37 coated to multiwell plates and found that LL-37 electrostatically interacts with mucins. Circular dichroism spectra of the peptide revealed the induction of alpha-helical conformation by mucins. Addition of mucins to solutions of LL-37 significantly decreased the antimicrobial activity of the peptide against Pseudomonas aeruginosa and Streptococcus pneumoniae. We then tested whether LL-37 is bound to mucins in airway secretions from human subjects and found that a significant proportion of the peptide and its propeptide are bound to high molecular weight components. Together these data show that cationic AMPs interact with anionic mucins in airway secretions. Functions of AMPs are modulated by this interaction.
authors.affiliation: Department of Internal Medicine, Division for Pulmonary Diseases, Philipps-Universität Marburg, 35043 Marburg, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Felgentreff
authors.forename: Christoph
authors.initials: C
authors.lastname: Beisswenger
authors.forename: Matthias
authors.initials: M
authors.lastname: Griese
authors.forename: Tanja
authors.initials: T
authors.lastname: Gulder
authors.forename: Gerhard
authors.initials: G
authors.lastname: Bringmann
authors.forename: Robert
authors.initials: R
authors.lastname: Bals
mesh_terms: D000328:Adult; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism*; D006801:Humans; D009093:Mucus / Q000378:metabolism*; D020545:Respiratory Mucosa / Q000378:metabolism*; D013552:Swine; D054804:Cathelicidins
chemical_list: D023181:Antimicrobial Cationic Peptides; D054804:Cathelicidins