title: Cleavage of kininogen and subsequent bradykinin release by the complement component: mannose-binding lectin-associated serine protease (MASP)-1.
abstract: Bradykinin (BK), generated from high-molecular-weight kininogen (HK) is the major mediator of swelling attacks in hereditary angioedema (HAE), a disease associated with C1-inhibitor deficiency. Plasma kallikrein, activated by factor XIIa, is responsible for most of HK cleavage. However other proteases, which activate during episodes of angioedema, might also contribute to BK production. The lectin pathway of the complement system activates after infection and oxidative stress on endothelial cells generating active serine proteases: MASP-1 and MASP-2. Our aim was to study whether activated MASPs are able to digest HK to release BK. Initially we were trying to find potential new substrates of MASP-1 in human plasma by differential gel electrophoresis, and we identified kininogen cleavage products by this proteomic approach. As a control, MASP-2 was included in the study in addition to MASP-1 and kallikrein. The proteolytic cleavage of HK by MASPs was followed by SDS-PAGE, and BK release was detected by HPLC. We showed that MASP-1 was able to cleave HK resulting in BK production. MASP-2 could also cleave HK but could not release BK. The cleavage pattern of MASPs is similar but not strictly identical to that of kallikrein. The catalytic efficiency of HK cleavage by a recombinant version of MASP-1 and MASP-2 was about 4.0×10(2) and 2.7×10(2) M(-1) s(-1), respectively. C1-inhibitor, the major inhibitor of factor XIIa and kallikrein, also prevented the cleavage of HK by MASPs. In all, a new factor XII- and kallikrein-independent mechanism of bradykinin production by MASP-1 was demonstrated, which may contribute to the pro-inflammatory effect of the lectin pathway of complement and to the elevated bradykinin levels in HAE patients.
authors.affiliation: Institute of Enzymology, Hungarian Academy of Sciences, Budapest, Hungary. dobo@enzim.hu
authors.forename: József
authors.initials: J
authors.lastname: Dobó
authors.forename: Balázs
authors.initials: B
authors.lastname: Major
authors.forename: Katalin A
authors.initials: KA
authors.lastname: Kékesi
authors.forename: István
authors.initials: I
authors.lastname: Szabó
authors.forename: Márton
authors.initials: M
authors.lastname: Megyeri
authors.forename: Krishnan
authors.initials: K
authors.lastname: Hajela
authors.forename: Gábor
authors.initials: G
authors.lastname: Juhász
authors.forename: Péter
authors.initials: P
authors.lastname: Závodszky
authors.forename: Péter
authors.initials: P
authors.lastname: Gál
mesh_terms: D001920:Bradykinin / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D006868:Hydrolysis; D007704:Kininogens / Q000378:metabolism*; D050606:Mannose-Binding Protein-Associated Serine Proteases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D007704:Kininogens; D011994:Recombinant Proteins; C084067:MASP1 protein, human; D050606:Mannose-Binding Protein-Associated Serine Proteases; D001920:Bradykinin