Design and characterization of α1-antitrypsin variants for treatment of contact system-driven thromboinflammation

TY - JOUR

T1 - Design and characterization of α1-antitrypsin variants for treatment of contact system-driven thromboinflammation

AU - de Maat, Steven

AU - Sanrattana, Wariya

AU - Mailer, Reiner K

AU - Parr, Naomi M J

AU - Hessing, Martin

AU - Koetsier, Robert M

AU - Meijers, Joost C M

AU - Pasterkamp, Gerard

AU - Renné, Thomas

AU - Maas, Coen

N1 - Copyright © 2019 American Society of Hematology.

PY - 2019/11/7

Y1 - 2019/11/7

N2 - The contact system produces the inflammatory peptide bradykinin and contributes to experimental thrombosis. C1 esterase-inhibitor (C1INH) deficiency or gain-of-function mutations in Factor XII (FXII) cause hereditary angioedema, a life-threatening tissue swelling disease. C1INH is a relatively weak contact system enzyme inhibitor. Although α1-antitrypsin (α1AT) does not naturally inhibit contact system enzymes, a human mutation (M358R; α1AT-Pittsburgh) changes it into a powerful broad-spectrum enzyme inhibitor. It blocks the contact system, but also thrombin and activated protein C (APC), making it an unattractive candidate for therapeutic contact system blockade. We adapted the reactive center loop of α1AT-Pittsburgh (AIPR/S) to overcome these obstacles. Two α1AT variants (SMTR/S and SLLR/S) strongly inhibit plasma kallikrein, activated FXII and plasmin. α1AT-SMTR/S no longer inhibits thrombin, but residually inhibits APC. In contrast, α1AT-SLLR/S residually inhibits thrombin, but no longer APC. Additional modification at the P1' position (S→V) eliminates residual inhibition of thrombin and APC for both variants, while retaining their properties as contact system inhibitors. Both α1AT-SMTR/V and -SLLR/V are superior to C1INH in reducing bradykinin production in plasma. Owing to their capacity to selectively block contact system-driven coagulation, both variants block vascular occlusion in an in vivo model for arterial thrombosis. Furthermore, both variants block acute carrageenan-induced tissue edema in mice. Finally, α1AT-SLLR/V, our most powerful candidate, suppresses epithelial leakage of the gut in a mouse model of colitis. Our findings confirm that redesign of α1AT strongly alters its inhibitory behavior and can be used for the treatment of contact system-mediated thrombosis and inflammation.

AB - The contact system produces the inflammatory peptide bradykinin and contributes to experimental thrombosis. C1 esterase-inhibitor (C1INH) deficiency or gain-of-function mutations in Factor XII (FXII) cause hereditary angioedema, a life-threatening tissue swelling disease. C1INH is a relatively weak contact system enzyme inhibitor. Although α1-antitrypsin (α1AT) does not naturally inhibit contact system enzymes, a human mutation (M358R; α1AT-Pittsburgh) changes it into a powerful broad-spectrum enzyme inhibitor. It blocks the contact system, but also thrombin and activated protein C (APC), making it an unattractive candidate for therapeutic contact system blockade. We adapted the reactive center loop of α1AT-Pittsburgh (AIPR/S) to overcome these obstacles. Two α1AT variants (SMTR/S and SLLR/S) strongly inhibit plasma kallikrein, activated FXII and plasmin. α1AT-SMTR/S no longer inhibits thrombin, but residually inhibits APC. In contrast, α1AT-SLLR/S residually inhibits thrombin, but no longer APC. Additional modification at the P1' position (S→V) eliminates residual inhibition of thrombin and APC for both variants, while retaining their properties as contact system inhibitors. Both α1AT-SMTR/V and -SLLR/V are superior to C1INH in reducing bradykinin production in plasma. Owing to their capacity to selectively block contact system-driven coagulation, both variants block vascular occlusion in an in vivo model for arterial thrombosis. Furthermore, both variants block acute carrageenan-induced tissue edema in mice. Finally, α1AT-SLLR/V, our most powerful candidate, suppresses epithelial leakage of the gut in a mouse model of colitis. Our findings confirm that redesign of α1AT strongly alters its inhibitory behavior and can be used for the treatment of contact system-mediated thrombosis and inflammation.

U2 - 10.1182/blood.2019000481

DO - 10.1182/blood.2019000481

M3 - SCORING: Journal article

C2 - 31366623

VL - 134

SP - 1658

EP - 1669

JO - BLOOD

JF - BLOOD

SN - 0006-4971

IS - 19

ER -