Serum MASP-1 in complex with MBL activates endothelial cells

TY - JOUR

T1 - Serum MASP-1 in complex with MBL activates endothelial cells

AU - Megyeri, Márton

AU - Jani, Péter K

AU - Kajdácsi, Erika

AU - Dobó, József

AU - Schwaner, Endre

AU - Major, Balázs

AU - Rigó, János

AU - Závodszky, Péter

AU - Thiel, Steffen

AU - Cervenak, László

AU - Gál, Péter

N1 - Copyright © 2014 Elsevier Ltd. All rights reserved.

PY - 2014/5

Y1 - 2014/5

N2 - The complement system plays an important role in the induction of inflammation. In this study we demonstrate that the initiation complexes of the lectin pathway, consisting of mannose-binding lectin (MBL) and associated serine proteases (MASPs) elicit Ca(2+) signaling in cultured endothelial cells (HUVECs). This is in agreement with our previous results showing that the recombinant catalytic fragment of MASP-1 activates endothelial cells by cleaving protease activated receptor 4. Two other proteases, MASP-2 and MASP-3 are also associated with MBL. Earlier we showed that recombinant catalytic fragment of MASP-2 cannot activate HUVECs, and in this study we demonstrate that the same fragment of MASP-3 has also no effect. We find the same to be the case if we use recombinant forms of the N-terminal parts of MASP-1 and MASP-2 which only contain non-enzymatic domains. Moreover, stable zymogen mutant form of MASP-1 was also ineffective to stimulate endothelial cells, which suggests that in vivo MASP-1 have the ability to activate endothelial cells directly as well as to activate the lectin pathway simultaneously. We show that among the components of the MBL-MASPs complexes only MASP-1 is able to trigger response in HUVECs and the proteolytic activity of MASP-1 is essential. Our results strengthen the view that MASP-1 plays a central role in the early innate immune response.

AB - The complement system plays an important role in the induction of inflammation. In this study we demonstrate that the initiation complexes of the lectin pathway, consisting of mannose-binding lectin (MBL) and associated serine proteases (MASPs) elicit Ca(2+) signaling in cultured endothelial cells (HUVECs). This is in agreement with our previous results showing that the recombinant catalytic fragment of MASP-1 activates endothelial cells by cleaving protease activated receptor 4. Two other proteases, MASP-2 and MASP-3 are also associated with MBL. Earlier we showed that recombinant catalytic fragment of MASP-2 cannot activate HUVECs, and in this study we demonstrate that the same fragment of MASP-3 has also no effect. We find the same to be the case if we use recombinant forms of the N-terminal parts of MASP-1 and MASP-2 which only contain non-enzymatic domains. Moreover, stable zymogen mutant form of MASP-1 was also ineffective to stimulate endothelial cells, which suggests that in vivo MASP-1 have the ability to activate endothelial cells directly as well as to activate the lectin pathway simultaneously. We show that among the components of the MBL-MASPs complexes only MASP-1 is able to trigger response in HUVECs and the proteolytic activity of MASP-1 is essential. Our results strengthen the view that MASP-1 plays a central role in the early innate immune response.

KW - Blotting, Western

KW - Calcium

KW - Cells, Cultured

KW - Complement Activation

KW - Complement Pathway, Mannose-Binding Lectin

KW - Human Umbilical Vein Endothelial Cells

KW - Humans

KW - Immunity, Innate

KW - Mannose-Binding Lectin

KW - Mannose-Binding Protein-Associated Serine Proteases

KW - Microscopy, Fluorescence

KW - Mutation

KW - Peptide Fragments

KW - Protein Binding

KW - Proteolysis

KW - Recombinant Proteins

U2 - 10.1016/j.molimm.2014.01.001

DO - 10.1016/j.molimm.2014.01.001

M3 - Journal article

C2 - 24472859

SN - 0161-5890

VL - 59

SP - 39

EP - 45

JO - Molecular Immunology

JF - Molecular Immunology

IS - 1

ER -