title: Antimicrobial Peptide LL-37 Is Both a Substrate of Cathepsins S and K and a Selective Inhibitor of Cathepsin L.
abstract: Lung cysteine cathepsins B, K, L, and S contribute to physiological and pathological processes including degradation of antimicrobial peptides/proteins (AMPs) such as surfactant protein SP-A, lactoferrin, secretory leukocyte peptidase inhibitor, and beta-defensins-2 and -3. Substantial amounts of uncleaved LL-37, a 37-mer cationic AMP, were observed in the sputum of patients with cystic fibrosis (CF). Nevertheless LL-37 was degraded after prolonged incubation in CF sputum, and the hydrolysis was blocked by E-64, a selective inhibitor of cysteine proteases. Cathepsins K and S, expressed in human alveolar macrophages, thoroughly hydrolyzed LL-37 in vitro, whereas it competitively inhibited cathepsin L (Ki = 150 nM). Cleavage of LL-37 by cathepsins S and K impaired its antimicrobial activity against Pseudomonas aeruginosa and Staphylococcus aureus, in a time- and concentration-dependent manner. The exchange of residues 67 and 205 in the S2 pockets of cathepsins L (Leu67Tyr/Ala205Leu) and K (Tyr67Leu/Leu205Ala) switched the specificity of these mutants toward LL-37. Molecular modeling suggested that LL-37 interacted with the active site of cathepsin L in both forward (i.e., substrate-like) and reverse orientations with similar binding energies. Our data support the hypothesis that cysteine cathepsins modulate the innate immunity response by degrading distinct and representative members of the AMP family.
authors.affiliation: †INSERM, UMR 1100, Pathologies Respiratoires: protéolyse et aérosolthérapie, Centre d'Etude des Pathologies Respiratoires, Equipe 2: "Mécanismes Protéolytiques dans l'Inflammation", Université François Rabelais, F-37032 Tours cedex, France.
authors.forename: Pierre-Marie
authors.initials: PM
authors.lastname: Andrault
authors.affiliation: ‡Structural Bioinformatics, BIOTEC TU Dresden, Tatzberg 47-51, 01307 Dresden, Germany.
authors.forename: Sergey A
authors.initials: SA
authors.lastname: Samsonov
authors.affiliation: §INSERM, UMR 1069, Nutrition Croissance et Cancer, Université François Rabelais, F-37032 Tours cedex, France.
authors.forename: Gunther
authors.initials: G
authors.lastname: Weber
authors.affiliation: ∥CNRS UMR 6270, Plate-forme de Protéomique "PISSARO" de l'IRIB, Université de Rouen, F-76821 Mont-Saint Aignan, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Coquet
authors.affiliation: ⊥Department of Oral Biochemistry, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU Universiteit Amsterdam, 1081 LA, Amsterdam, The Netherlands.
authors.forename: Kamran
authors.initials: K
authors.lastname: Nazmi
authors.affiliation: ⊥Department of Oral Biochemistry, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU Universiteit Amsterdam, 1081 LA, Amsterdam, The Netherlands.
authors.forename: Jan G M
authors.initials: JG
authors.lastname: Bolscher
authors.affiliation: #INRA, UMR 1282 Infectiologie et Santé Publique, Université François Rabelais, F-37380 Nouzilly, France.
authors.forename: Anne-Christine
authors.initials: AC
authors.lastname: Lalmanach
authors.affiliation: ∥CNRS UMR 6270, Plate-forme de Protéomique "PISSARO" de l'IRIB, Université de Rouen, F-76821 Mont-Saint Aignan, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Jouenne
authors.affiliation: ○Department of Oral Biological and Medical Sciences, The University of British Columbia, Vancouver, British Columbia V6T1Z3, Canada.
authors.forename: Dieter
authors.initials: D
authors.lastname: Brömme
authors.affiliation: ‡Structural Bioinformatics, BIOTEC TU Dresden, Tatzberg 47-51, 01307 Dresden, Germany.
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Pisabarro
authors.affiliation: †INSERM, UMR 1100, Pathologies Respiratoires: protéolyse et aérosolthérapie, Centre d'Etude des Pathologies Respiratoires, Equipe 2: "Mécanismes Protéolytiques dans l'Inflammation", Université François Rabelais, F-37032 Tours cedex, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Lalmanach
authors.affiliation: †INSERM, UMR 1100, Pathologies Respiratoires: protéolyse et aérosolthérapie, Centre d'Etude des Pathologies Respiratoires, Equipe 2: "Mécanismes Protéolytiques dans l'Inflammation", Université François Rabelais, F-37032 Tours cedex, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Lecaille
mesh_terms: D000595:Amino Acid Sequence; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D001992:Bronchoalveolar Lavage Fluid; D056657:Cathepsin K / Q000378:metabolism*; D056668:Cathepsin L / Q000037:antagonists & inhibitors*; D002403:Cathepsins / Q000378:metabolism*; D002942:Circular Dichroism; D015853:Cysteine Proteinase Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D003550:Cystic Fibrosis / Q000382:microbiology; D006801:Humans; D016676:Macrophages, Alveolar / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D013379:Substrate Specificity; D054804:Cathelicidins
chemical_list: D023181:Antimicrobial Cationic Peptides; D015853:Cysteine Proteinase Inhibitors; D002403:Cathepsins; D056668:Cathepsin L; C028217:cathepsin S; D056657:Cathepsin K; D054804:Cathelicidins