PhD Scientific Days 2026

Poster Session 3.U - Molecular Medicine

In vivo thrombolytic resistance of venous thrombi related to the propensity for neutrophil extracellular trap (NET) formation

Name of the presenter

Csikós, Petra Metta

Institute/workplace of the presenter

Department of Biochemistry

Authors

Petra Metta Csikós¹, Barbara Baráth¹, Kristóf Molnár¹, Alexandra Raska¹, Kata Balog Virág¹, Zsombor Hegedűs², Zoltán Varga², Kraszimir Kolev¹, Nikolett Wohner¹
1: Department of Biochemistry
2: Department of Pharmacology and Pharmacotherapy

Text of the abstract

Introduction- Arterial and venous thrombi contain neutrophil extracellular traps (NETs), filamentous structures composed of DNA and attached proteins released from neutrophils. NETs inhibit plasminogen activation and the lytic phase of fibrinolysis in vitro. Peptidyl-arginine deiminase 4 (PAD4)-mediated protein citrullination promotes certain routes of NET-formation, whereas the serine protease inhibitor SERPINB1 suppresses it.
Aims- To investigate the in vivo effects of NETs on the lysis of venous thrombi in vivo.
Methods- Deep vein thrombosis was induced in WT, PAD4 KO and SERPINB1 KO mice by inferior vena cava (IVC) stenosis surgery, followed by intravenous tissue-type plasminogen activator (tPA) thrombolysis 48 hours later. Thrombus dynamics were monitored using a VEVO 3100 small-animal ultrasound system. After thrombus retrieval, citrullinated histone H3 (cH3) and histone H2B were assessed by indirect immunofluorescence. Prior thrombus removal, from retro-orbital blood sample thrombin generation was measured in whole blood.
Results- In the IVC stenosis model, all strains showed a transient thrombus enlargement at the onset of tPA induced thrombolysis, peaking at 60 min (WT: +88±6%, PAD4 KO: +19±6%, SERPINB1 KO: +27±7%). Between 60 and 120 min, thrombus area increased in WT mice (+24±9%), but rapid lysis occurred in PAD4 KO mice (–36±13%); SERPINB1 KO animals showed a moderate decrease (–14±6%). Thrombin generation (endogenous thrombin potential (ETP) and peak thrombin concentration) was significantly higher in WT than in PAD4 KO mice (ETP 12875(IQR1716;21292) vs. 4314(IQR1344;6247) nM.s), while SERPINB1 KO animals showed delayed increase in thrombin generation (ETP 21734(IQR18718;56751) vs 14008(IQR7726;22219) nM.s). In SERPINB1 KO mice, H2B and cH3 were significantly higher on postoperative day 2 compared to other strains.
Conclusion- PAD4 ablation was associated with reduced thrombus formation, enhanced thrombolysis, with lower thrombin generation and reduced NET-associated histone deposition. In contrast, SERPINB1 ablation was characterized by increased histone release, more persistent thrombi, and delayed increase in thrombin generation, enhanced NET-mediated lytic resistance in vivo.
Funding: HCEMM SE Thrombosis and Hemostasis research group