Resolution of Deep Venous Thrombosis: Proposed Immune Paradigms.

Venous thromboembolism (VTE) is a pathology encompassing deep vein thrombosis (DVT) and pulmonary embolism (PE) associated with high morbidity and mortality. Because patients often present after a thrombus has already formed, the mechanisms that drive DVT resolution are being investigated in search of treatment. Herein, we review the current literature, including the molecular mechanisms of fibrinolysis and collagenolysis, as well as the critical cellular roles of macrophages, neutrophils, and endothelial cells. We propose two general models for the operation of the immune system in the context of venous thrombosis. In early thrombus resolution, neutrophil influx stabilizes the tissue through NETosis. Meanwhile, macrophages and intact neutrophils recognize the extracellular DNA by the TLR9 receptor and induce fibrosis, a complimentary stabilization method. At later stages of resolution, pro-inflammatory macrophages police the thrombus for pathogens, a role supported by both T-cells and mast cells. Once they verify sterility, these macrophages transform into their pro-resolving phenotype. Endothelial cells both coat the stabilized thrombus, a necessary early step, and can undergo an endothelial-mesenchymal transition, which impedes DVT resolution. Several of these interactions hold promise for future therapy.

Inflammatory biomarkers in deep venous thrombosis organization, resolution, and post-thrombotic syndrome.

OBJECTIVE: Venous thromboembolism (VTE) is a common disease with potentially devastating and long-term sequelae, such as pulmonary embolism and post-thrombotic syndrome (PTS). Given the mortality risk, prevalence of VTE, and limited access to diagnostic imaging, clinically relevant biomarkers for diagnosis and prognostication are needed. Therefore, this review aimed to summarize the data on clinically applicable biomarkers that best indicate acute VTE and chronic PTS. METHODS: We reviewed the medical and scientific literature from 2001 to 2019 for VTE biomarkers. Randomized controlled trials, meta-analyses, and review articles were included. Primary basic research papers with no clinical applicability, opinion papers, institutional guidelines, and case reports were excluded. RESULTS: We highlight the diagnostic value of D-dimer alongside other promising biomarkers, including cellular adhesion molecules, P-selectin, cytokines (interleukins 6 and 10), fibrin monomer complexes, and coagulation factors (factor VIII). CONCLUSIONS: High-sensitivity D-dimer remains the most clinically established VTE biomarker. Current research endeavors are under way to identify more precise biomarkers of VTE and PTS.