OC 03.4 - Glycated albumin modulates the contact system with implications for the kallikrein-kinin and intrinsic coagulation systems

Saturday, July 9, 2022

1:45 PM – 2:00 PM

Location: ICC Capital Suite Room 7&12

Presentation Format: In-Person

Presenting Author(s)

Lewis J. Hardy, PhD

Post-doctoral research scientist
Leeds Institute of Cardiovascular & Metabolic Medicine (LICAMM), University of Leeds, Leeds, West Yorkshire, United Kingdom
Leeds, England, United Kingdom

Co-Author(s)

Dillon Bohinc

Research Associate II
Case Western Reserve University
Cleveland, Ohio, United States
KB

Kara Bane

Research scientist
CWRU School of Medicine
Cleveland, Ohio, United States
SH

Samantha Heal

Research Scientist
University of Leeds
Leeds, England, United Kingdom
EH

Emma Hethershaw

Research Scientist
Unversity of Leeds
Leeds, England, United Kingdom
MA

Majid Ali

Research Scientist
University of Leeds
Leeds, England, United Kingdom
RF

Richard Foster

Associate Professor
University of Leeds
Leeds, England, United Kingdom
CL

Colin Longstaff

Biotherapeutics Group Lead
National Institute for Biological Standards and Control
Hertfordshire, England, United Kingdom
TR

Thomas Renne

Professor
Institute for Clinical Chemistry and Laboratory Medicine
Eppendorf, Hamburg, Germany
Evi X. Stavrou, MD

Associate Professor
Department of Medicine, Hematology and Oncology Division, CWRU School of Medicine, Cleveland, OH, USA.
Cleveland, Ohio, United States
Helen Philippou, PhD

Professor
University of Leeds.
Leeds, England, United Kingdom

Background: Factor(F) XII is a coagulation factor at the frontier of coagulation, inflammation, innate immunity, and fibrinolysis. Misfolded proteins are factor XII (FXII) activators that can trigger the proinflammatory kallikrein-kinin system (KKS) and the intrinsic pathway of coagulation, via plasma kallikrein (PKa) and activated Factor XI (FXIa), respectively. The chronic hyperglycaemic conditions in diabetes mellitus (DM) patients induce a non-enzymatic Maillard reaction that denatures plasma proteins to form advanced glycation end products (AGEs) which accumulate within the vasculature and tissues.

Aims: Human serum albumin (HSA) is the most abundant protein in plasma and is sensitive to glycation in vivo. We investigated the relationship between plasma glycation levels and activation of the contact pathway in diabetic patients and characterised the effects of HSA-AGE on FXII, PK, FXI activation, and thrombus formation.

Methods: Plasma was obtained from 10 DM patients (2 T1DM, 8 T2DM), 10 age-matched euglycemic volunteers and were subjected to immunoblotting for activated FXII(a) and cleaved high molecular weight kininogen (cHK). Plasma PKa activity was measured via chromogenic assay. Kinetic modulation of FXII, PK, FXI and their respective full active serine proteases by in vitro generated HSA-AGE were explored using chromogenic assays, plasma clotting assays, and an in vitro flow model using whole blood.

Results: Plasma obtained from DM patients has increased plasma AGEs, FXIIa, cHK, along with increased plasma PKa enzymatic activity levels which positively correlated with HbA1C levels. In vitro generated HSA-AGE triggered FXIIa-dependent PKa activation but limits procoagulant intrinsic pathway activation by directly inhibiting FXIa, and separately, activated Factor IX (FIXa)-dependent Factor X (FX) activation in plasma.

Conclusion(s): These data suggest a proinflammatory role of AGEs in the pathophysiology of DM via FXII and KKS activation. The expected procoagulant signal from FXII activation was lost through the inhibition of FXIa and (FIXa)-dependent Factor X (FX) activation.