Using novel RNA therapy to understand the role of fibrinogen in thromboinflammation in acute and chronic venous thrombosis - PROJECT SUMMARY/ABSTRACT Deep venous thrombosis (DVT) is a major cause of short and long-term morbidity and mortality. Despite the use of gold-standard anticoagulation therapies for the prevention and treatment of DVT, such as heparins and direct oral anticoagulants (DOACs), the incidence of DVT remains high in certain at-risk populations such as trauma patients and patients who suffer from chronic inflammatory diseases. Furthermore, current therapies have increased risks of bleeding. 40-70% of patients develop Post Thrombotic Syndrome (PTS) due to the extensive nature of the clot or poor clot resolution resulting in chronic thrombosis and vein wall scarring. Clinically, there are few treatments for PTS, which is characterized by pain, leg swelling, and ulcer formation. At the cellular level, the development and subsequent resolution of thrombus occurs through a complex interplay between the coagulation system and inflammation. Fibrinogen is the most abundant protein in circulation that is involved in the process of thrombus formation and resolution. The fibrin matrix serves as a platform for cellular infiltration, thrombus growth, and can result in dense clots resistant to lysis. Inadequate clot resolution and vein wall scarring, processes that are in part regulated by matrix metalloproteases (MMPs), lead to chronic DVT. The proposed aims of this project will investigate the role of fibrinogen in thromboinflammation in post-traumatic and acute DVT and the interplay between fibrinogen and MMPs in thrombus resolution and vein wall remodeling/fibrosis. To address these aims we will use novel RNA therapy to reduce circulating levels of fibrinogen. We have developed small interfering RNA (siRNA) directed against fibrinogen messenger RNA (mRNA) that can be delivered into cells using lipid nanoparticles (LNPs). Within the cell, the siRNA is released from the LNP and induces degradation of the target mRNA, preventing translation of the protein product. I will use LNPs similar to those used in the COVID-19 mRNA vaccines as a delivery platform, which naturally accumulate in the liver after intravenous injection, where fibrinogen is synthesized. We will use the LNP-RNA therapy in models of rodent and swine thrombosis to provide rigorous pre-clinical data. We hypothesize that fibrinogen plays a central role in regulating inflammatory cell infiltration in the developing thrombus and in regulating the activity of MMPs to promote thrombus resolution and vein wall healing. Through selective control of fibrinogen levels using a highly specific approach, targeting fibrinogen is not expected to increase the risk of bleeding. These studies will provide mechanistic insights into the role of fibrinogen in regulating thromboinflammation in settings of acute and chronic venous thrombosis. I have assembled a mentorship team with expertise in RNA therapy, LNP biochemistry, and coagulation biology that will oversee my successful completion of the proposed studies and development of the professional and scientific skills to transition to independence.
