The long-term objective of this research program is to define the mechanisms by which the central hemostatic protease, thrombin, contributes to the development of sickle cell disease (SCD) pathologies. The seminal role of thrombin in hemostasis and vascular biology is underscored by the fact that this protease positively controls fibrin deposition, platelet activation, and endothelial cell (EC) signaling events via multiple substrates and receptors [e.g., protease-activated receptors, fibrinogen, factor XI, and factor XIII], as well as negatively controls further thrombin generation through the activation of protein C, a natural anticoagulant with known anti-inflammatory/cytoprotective properties. The control of thrombin activity has been intensely studied because thrombin-mediated proteolysis is fundamental to both physiological hemostasis and pathological vaso-occlusive events, including myocardial infarction, venous thrombosis and stroke. However, an additional driving force for detailed studies of thrombin and thrombin targets is that these proteins also control vascular permeability/barrier function, tissue repair, and inflammation, which together contribute to the development of multiple inflammatory diseases. Given that circulating sickle cells result in a combination of vascular damage, occlusive events and inflammatory changes, and given that local and systemic hemostatic system activation is a conspicuous feature of SCD, thrombin and thrombin targets are prime candidates to be clinically-significant modifiers of sickle cell disease pathobiology.
The aims of this project center on two general hypotheses: i) thrombin, as a master regulator of vascular biology, platelet/EC activation, fibrin deposition and inflammatory processes, is a major determinant of SCD pathologies, and ii) SCD-associated morbidities can be ameliorated by novel genetic or pharmacological interventions at the level of pro/thrombin and downstream thrombin substrates. These hypotheses will be tested through studies that focus on defining the importance of prothrombin in the development of multi-organ SCD pathologies and long-term survival in Berkeley sickle mice (Hba0/Hbb0 [Tg(Human HbS)]+/+)) (Aim 1);understanding the thrombin-mediated, fibrin(ogen)-dependent and fibrin(ogen)-independent mechanisms driving SCD pathologies (Aim 2);and establishing the potential benefit of thrombin-targeted pharmacological intervention in limiting SCD pathologies in mice (Aim 3). The proposed studies will provide for the first time a clear understanding of the significance of hemostatic factors in the pathogenesis of SCD and may illuminate novel therapeutic strategies for limiting SCD-induced morbidities.

Public Health Relevance

Sickle cell anemia affects over 100,000 Americans and millions worldwide and results in occlusion of blood vessels, pain crises, inflammation, damage to multiple organs, stroke and reduced life-expectancy. There is substantial evidence of coagulation ('clotting') factor activation in sickle cell patients;however, the precise contributin of coagulation factors to vessel occlusion and inflammation remains unclear. The primary goal of this research is to use modern molecular genetics to develop an in-depth understanding of the contribution of key coagulation factors in sickle cell disease and explore novel treatment strategies for patients with this disease.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL112603-01
Application #
8256975
Study Section
Special Emphasis Panel (ZRG1-VH-D (03))
Program Officer
Kindzelski, Andrei L
Project Start
2012-01-01
Project End
2016-11-30
Budget Start
2012-01-01
Budget End
2012-11-30
Support Year
1
Fiscal Year
2012
Total Cost
$382,500
Indirect Cost
$132,500
Name
Cincinnati Children's Hospital Medical Center
Department
Type
DUNS #
071284913
City
Cincinnati
State
OH
Country
United States
Zip Code
45229
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Flick, Matthew J; Bugge, Thomas H (2016) Plasminogen-receptor KT : Plasminogen activation and beyond. J Thromb Haemost :
Adams, Gregory N; Rosenfeldt, Leah; Frederick, Malinda et al. (2015) Colon Cancer Growth and Dissemination Relies upon Thrombin, Stromal PAR-1, and Fibrinogen. Cancer Res 75:4235-43
Raghu, Harini; Cruz, Carolina; Rewerts, Cheryl L et al. (2015) Transglutaminase factor XIII promotes arthritis through mechanisms linked to inflammation and bone erosion. Blood 125:427-37
Pawlinski, Rafal (2015) It's "PT" for SCD! Blood 126:1739-40
Prasad, Joni M; Gorkun, Oleg V; Raghu, Harini et al. (2015) Mice expressing a mutant form of fibrinogen that cannot support fibrin formation exhibit compromised antimicrobial host defense. Blood 126:2047-58
Arumugam, Paritha I; Mullins, Eric S; Shanmukhappa, Shiva Kumar et al. (2015) Genetic diminution of circulating prothrombin ameliorates multiorgan pathologies in sickle cell disease mice. Blood 126:1844-55
Joshi, N; Kopec, A K; O'Brien, K M et al. (2015) Coagulation-driven platelet activation reduces cholestatic liver injury and fibrosis in mice. J Thromb Haemost 13:57-71
Yuasa, Masato; Mignemi, Nicholas A; Nyman, Jeffry S et al. (2015) Fibrinolysis is essential for fracture repair and prevention of heterotopic ossification. J Clin Invest 125:3117-31
Kopec, Anna K; Joshi, Nikita; Towery, Keara L et al. (2014) Thrombin inhibition with dabigatran protects against high-fat diet-induced fatty liver disease in mice. J Pharmacol Exp Ther 351:288-97

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