Thromb Haemost 2015; 114(05): 1028-1037
DOI: 10.1160/TH14-12-1031
Blood Cells, Inflammation and Infection
Schattauer GmbH

Divergent effects of Tlr9 deletion in experimental late venous thrombosis resolution and vein wall injury

Nicholas A. Dewyer*
1  Department of Vascular Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA
,
Osama M. El-Sayed*
1  Department of Vascular Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA
,
Catherine E. Luke
1  Department of Vascular Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA
,
Megan Elfline
1  Department of Vascular Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA
,
Nicolai Kittan
2  Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, USA
,
Ron Allen
2  Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, USA
,
Adriana Laser
1  Department of Vascular Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA
,
Carson Oostra
3  Jobst Vascular Institute, Toledo Hospital, Toledo, Michigan, USA
,
Anthony Comerota
3  Jobst Vascular Institute, Toledo Hospital, Toledo, Michigan, USA
,
Cory Hogaboam
2  Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, USA
,
Steven L. Kunkel
2  Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, USA
,
Peter K. Henke
1  Department of Vascular Surgery, University of Michigan Medical School, Ann Arbor, Michigan, USA
› Institutsangaben
Financial support: This work was supported by NIH HL092129 and HL31237 and a Howard Hughes Medical Institute Medical Student Research Fellowship.
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Publikationsverlauf

Received: 14. Dezember 2014

Accepted after major revision: 07. Mai 2015

Publikationsdatum:
06. Dezember 2017 (online)

Summary

Deep-vein thrombosis (DVT) resolves via a sterile inflammatory response. Defining the inflammatory response of DVT may allow for new therapies that do not involve anticoagulation. Previously, we have shown that Toll-like receptor 9 (Tlr9) gene deleted mice had impaired venous thrombosis (VT) resolution. Here, we further characterise the role of Tlr9 signalling and sterile inflammation in chronic VT and vein wall responses. First, we found a human precedent exists with Tlr9 + cells present in chronic post thrombotic intraluminal tissue. Second, in a stasis VT mouse model, endogenous danger signal mediators of uric acid, HMGB-1, and neutrophil extracellular traps marker of citrullinated histone-3 (and extracellular DNA) were greater in Tlr9-/- thrombi as compared with wild-type (WT), corresponding with larger VT at 8 and 21 days. Fewer M1 type (CCR2+) monocyte/macrophages (MØ) were present in Tlr9-/- thrombi than WT controls at 8 days, suggesting an impaired inflammatory cell influx. Using bone marrow-derived monocyte (BMMØ) cell culture, we found decreased fibrinolytic gene expression with exposure to several endogenous danger signals. Next, adoptive transfer of cultured Tlr9+/+ BMMØ to Tlr9-/- mice normalised VT resolution at 8 days. Lastly, although the VT size was larger at 21 days in Tlr9-/- mice and correlated with decreased endothelial antigen markers, no difference in fibrosis was found. These data suggest that Tlr9 signalling in MØ is critical for later VT resolution, is associated with necrosis clearance, but does not affect later vein wall fibrosis. These findings provide insight into the Tlr9 MØ mechanisms of sterile inflammation in this disease process.

* These authors contributed equally to this work.