Introduction: With growing awareness of immune thrombosis and severe complications such as sepsis,
it is increasingly clear that coagulation and innate immunity function synergistically
as a unified response to injury [1]
[2]. We aim to understand and decipher the molecular mechanisms by which fibrin clots
regulate clot fate and orchestrate innate immune responses. Additionally, we seek
to explore how these immune responses, in turn, influence clot resolution. A critical
open question remains: how do clot fate and clot-homing factors differ across immunocompromised
backgrounds? Understanding the intricate innate immune networks could provide new
tools for clot resolution, cellular responses, and recovery.
Method: Mice (Mus musculus, background: B6 CD45.1) with a diverse set of innate immune or clotting defects were
selected for the study. These defects were categorized into four main groups: (a) immune response (C3 KO, Rag2 KO, Pd-1 KO, PDl1 KO, CCR2 KO), (b) clot structure (F8 KO, F13a1 KO), (c) vesicular transport (Itgam/Itgax), and (d) stress response (Akita mice). Submandibular blood samples were collected in EDTA or citrate, depending on
the analysis required, while separate whole blood samples were taken for clot proteome
analyses. Proteomic analyses of clot and EDTA-plasma samples (in triplicates) were
performed using DIA-MS and analyzed with Proteome Discoverer software [3]. Additionally, thrombin generation (TGA) and fibrinolysis markers (PAI-1 and SFMC
ELISA) was quantified in citrated plasma. All data were normalized to wild-type littermate
controls.
Results: A preliminary proteomic analysis revealed distinct patterns among F8 KO and immune-compromised mice (PD-1 KO and CCR2 KO). In plasma, a differential abundance of about 140 proteins was observed that belonged
to coagulation, complement, vesicular transport, or related pathways. Observationally,
F8 KO mice exhibited increased fibrinolytic activity and upregulation of plasminogen activator
inhibitors. In contrast, PD-1 KO mice displayed a prothrombotic profile driven by excessive immune activation, while
CCR2 KO mice showed reduced monocyte recruitment and impaired coagulation. Principal component
analysis (PCA) hinted towards distinct plasma proteomic signatures for PD1_KO, B7H1, CCR2 KO while WT, Rag2, and F8_KO showed similar plasma proteomic signatures. A detailed ongoing analysis of the clot
proteome and rest will further dissect the etiologies of these observations.
Conclusion: These provisional results demonstrate distinct immune-coagulation interactions. F8 KO mice exhibit clot instability, whereas PD-1 KO mice show hypercoagulability likely driven by immune-mediated tissue factor expression.
These findings underscore the complexity of immunothrombosis, where immune modulation
plays divergent roles in coagulation disorders. The results point to potential therapeutic
targets for addressing dysregulation in coagulation and immune responses.
