Regular articleChronic thromboembolic pulmonary hypertension-associated dysfibrinogenemias exhibit disorganized fibrin structure☆
Introduction
After acute venous thromboembolism, thrombi either resolve completely or are replaced by chronic intravascular scars, which may have various clinical effects. In the case of acute pulmonary emboli, residual lung perfusion defects are common [1], [2], [3], [4], [5], [6] and probably represent minor degrees of intravascular scarring. However, more extensive scars within the pulmonary arteries may result in chronic thromboembolic pulmonary hypertension (CTEPH), a life-threatening disease [7]. Likewise, residual intraluminal venous thickening is common after acute deep vein thrombosis [8], whereas extensive scarring within the deep veins produces chronic thrombotic venous disease (CTVD), a cause of post-thrombotic syndrome [9].
The factors that contribute to poor resolution of venous thromboemboli and the intravascular scar formation that leads to CTEPH and CTVD are not fully understood. Polymerized fibrin is a major component of acute venous thromboemboli, and resistance to lysis is characteristic of some abnormally formed fibrin clots [10]. We previously reported an unusually high prevalence of dysfibrinogenemias among CTEPH patients [11], which may contribute to a relative resistance to plasmin-mediated fibrinolysis in some cases [12].
We undertook the current series of experiments to determine if CTEPH-associated dysfibrinogenemias lead to abnormal fibrin network formation. In particular, we are interested in alterations that might be implicated in delayed fibrinolysis, abnormal cellular responses to thrombi and subsequent remodeling of thrombotic material into scar tissue.
Section snippets
Materials
Human α-thrombin and glu-plasminogen were purchased from Enzyme Research Laboratories (South Bend, IN). Recombinant human tissue-type plasminogen activator (tPA), 2-chain form, was obtained from Burroughs Wellcome (Research Triangle Park, NC). Human fibrinogen conjugated with Alexa Fluor 488 (9 moles dye/mole protein) was purchased from Molecular Probes (Grand Island, NY). Glass bottom 96-well plates (No. 1.5, uncoated) were obtained from MatTek Corporation (Ashland, MA).
Subjects
The cohort of patients
Fibrinogen Regions Affected by Dysfibrinogenemias
The five dysfibrinogenemias previously reported in CTEPH patients [11] are listed in Table 1. Each occurred in a different patient and all result from heterozygous missense mutations in one or more of the fibrinogen genes. Two patients had compound mutations. None of these mutations were found in a group of 20 healthy controls without a history of venous thromboembolism [11]. The patient with Bβ 235 Pro/Leu dysfibrinogenemia was also heterozygous for the common Bβ 448 Arg/Lys polymorphism, and
Discussion
We observed that fibrin clots derived from patients with CTEPH-associated dysfibrinogenemias have disorganized polymeric structures that may be implicated in delayed thrombolysis and replacement of thrombi by connective tissue. The abnormal fibrin network structures resemble experimentally produced “fine” fibrin clots [20], composed of “thin” fibrin fibers, which may have slower lysis rates than clots with thicker fibers [10], [21], [22], [23]. In keeping with this, we have previously reported
Conflict of Interest Statement
All authors declare no financial or personal conflict of interest.
Acknowledgements
The authors wish to acknowledge the support and inspiration of Dr. Virgil Woods throughout this and other projects. This work was supported by National Institutes of Health grants R01 HL095089 and T32 HL098062. Laser scanning confocal microscopy was performed at the UCSD School of Medicine Light Microscopy Facility, which is supported, in part, by grant P30 NS047101 from the National Institutes of Health.
References (42)
- et al.
Persistent post-embolic pulmonary hypertension
Chest
(Dec 1972) Pulmonary embolism. A study of late prognosis
Lancet
(Oct 15 1960)- et al.
Natural course of treated pulmonary embolism. Evaluation by perfusion lung scintigraphy, gas exchange, and chest roentgenogram
Chest
(Mar 1990) Structure of fibrin: impact on clot stability
J Thromb Haemost
(Jul 2007)- et al.
High prevalence of dysfibrinogenemia among patients with chronic thromboembolic pulmonary hypertension
Blood
(Aug 27 2009) - et al.
Dusart syndrome: A new concept of the relationship between fibrin clot architecture and fibrin clot degradability: Hypofibrinolysis related to an abnormal clot structure
Blood
(1993) - et al.
Incorporation of vitronectin into fibrin clots. Evidence for a binding interaction between vitronectin and gamma A/gamma' fibrinogen
J Biol Chem
(Mar 1 2002) - et al.
Rearrangements of the fibrin network and spatial distribution of fibrinolytic components during plasma clot lysis. Study with confocal microscopy
J Biol Chem
(Jan 26 1996) - et al.
Novel fibrinogen gamma375 Arg– > Trp mutation (fibrinogen aguadilla) causes hepatic endoplasmic reticulum storage and hypofibrinogenemia
Hepatology
(Sep 2002) Determining the crystal structure of fibrinogen
J Thromb Haemost
(May 2004)
Native fibrin gel networks observed by 3D microscopy, permeation and turbidity
Biochim Biophys Acta
The effect of fibrin structure on fibrinolysis
J Biol Chem
Accessibility of epitopes on fibrin clots and fibrinogen gels
Blood
Flow and Antibody Binding Properties of Hydrated Fibrins Prepared From Plasma, Platelet Rich Plasma and Whole Blood
Thromb Res
Interactions of intercellular adhesion molecule-1 with fibrinogen
Trends Cardiovasc Med
Common variation in the C-terminal region of the fibrinogen beta-chain: effects on fibrin structure, fibrinolysis and clot rigidity
Blood
The sialic acid content of fibrinogen decreases during pregnancy and increases in response to fibrate therapy
Thromb Res
Late prognosis of acute pulmonary embolism
N Engl J Med
Long-term prognosis of treated acute massive pulmonary embolism
Br Heart J
Clinical course and late prognosis of treated subacute massive, acute minor, and chronic pulmonary thromboembolism
Br Heart J
Chronic thromboembolic pulmonary hypertension
Am J Respir Crit Care Med
Cited by (33)
Novel venous thromboembolism mouse model to evaluate the role of complete and partial factor XIII deficiency in pulmonary embolism risk
2021, Journal of Thrombosis and HaemostasisLate outcomes of pulmonary embolism: The post-PE syndrome
2018, Thrombosis ResearchCitation Excerpt :The B-knob binds to endothelial cells and fibroblasts and may induce cell signaling that leads to scar formation [37–40]. Abnormal variants of fibrinogen have been found in some CTEPH patients [41–43]. In parallel, acute PE induces a vigorous inflammatory response, consisting of neutrophil infiltration followed by monocytes and accompanying cytokines and chemokines [44].
Familial chronic thromboembolic pulmonary hypertension
2016, ChestCitation Excerpt :Interferon-c–induced protein-10 has been linked to decreased 6-min walk distance and poorer cardiac output in CTEPH patients and may play a role in the chronic thrombus formation.16 In addition, fibrinogen variants resistant to lysis and responsible for abnormal clot architecture have been identified in patients with CTEPH.3,17 Familial CTEPH has never been described.
Clot structure and fibrinolytic potential in patients with post thrombotic syndrome
2016, Thrombosis ResearchCitation Excerpt :Apart from impaired fibrinolysis, also fibrin clot structure might contribute to the development of PTS. Recent studies have shown denser fibrin clot structures with smaller pores and increased resistance to fibrinolysis in patients with DVT and other thrombotic disorders [9–13]. The role of fibrin structure in PTS is currently unknown.
From acute pulmonary embolism to chronic thromboembolic pulmonary hypertension: Pathobiology and pathophysiology
2017, Archivos de Cardiologia de Mexico
- ☆
This work was presented, in part, on May 22, 2012 at the 2012 International Conference of the American Thoracic Society, San Francisco, CA.