Venous stasis-induced fibrinolysis prevents thrombosis in mice: role of α2-antiplasmin.

Stasis of venous blood triggers deep vein thrombosis by activating coagulation, yet its effects on the fibrinolytic system are not fully understood. We examined the relationship between stasis, fibrinolysis, and the development of experimental venous thrombosis. Effects of stasis-induced deep vein thrombosis and fibrinolysis on thrombosis were examined by inferior vena cava ligation in congenic mice with and without α2-antiplasmin (α2AP), the primary inhibitor of plasmin. Venous thrombus weights were measured and thrombus composition was determined by Martius scarlet blue and immunofluorescence staining. Venous thrombi from α2AP+/+ mice contained plasminogen activators, plasminogen activator inhibitor-1, plasminogen, and α2AP, which changed with thrombus age. Normal, α2AP+/+ mice developed large, occlusive thrombi within 5 hours after ligation; thrombi were even larger in plasminogen-deficient mice (P < .001). No significant thrombus formation was seen in α2AP-/- mice (P < .0001) or in α2AP+/+ mice treated with an α2AP-inactivating antibody (P < .001). Venous stasis activated fibrinolysis, measured by D-dimer levels, in α2AP-/- mice vs α2AP+/+ mice (P < .05). Inhibition of fibrinolysis by the indirect plasmin inhibitor ε-aminocaproic acid or by α2AP restored thrombosis in α2AP-/- mice. In addition to its effects on acute thrombosis, thrombus formation was also markedly suppressed in α2AP-/- mice vs α2AP+/+ mice (P < .0001) 1, 7, and 14 days after ligation. We conclude that experimental venous stasis activates the fibrinolytic system to block the development of venous thrombosis. Suppression of fibrinolysis by α2AP appears essential for stasis-induced thrombus development, which suggests that targeting α2AP may prove useful for preventing venous thrombosis.

Toll-like receptor 9 gene expression in the post-thrombotic syndrome, residual thrombosis and recurrent deep venous thrombosis: A case-control study.

OBJECTIVE: Animal models suggest that toll-like receptor 9 (TLR9) promotes thrombus resolution after acute deep venous thrombosis (DVT). We hypothesized that TLR9 expression is lower in patients with post-thrombotic syndrome (PTS) and investigated the role of TLR9 in residual thrombosis (RT) and recurrence. METHODS: Patients with a history of DVT with PTS (cases, n=30) and without PTS after minimal 24 months follow-up (controls, n=30) were selected. Healthy individuals (HI, n=29) without DVT were included as reference. TLR9 mRNA expression in leukocytes was determined by qPCR and normalized to the housekeeping succinate dehydrogenase subunit A gene using the ΔCt method. Sub analyses were performed to explore the TLR9 expression in patients with and without RT and multiple DVT episodes. RESULTS: The median TLR9 expression was 0.45 (interquartile range 0.31 to 0.93), 0.39 (0.25 to 0.69) and 0.62 (0.32 to 0.75) in cases, controls and HI respectively (p=0.61). The median TLR9 expression was 0.39 (0.26 to 0.51) in patients with RT compared to 0.55 (0.30 to 0.86, p=0.13) in those without. The median TLR9 expression was significantly lower in patients who had one DVT compared to patients with recurrent DVT, 0.37 (0.23 to 0.63) versus 0.55 (0.43 to 0.96) respectively (p<0.01). CONCLUSION: No significant difference in TLR9 expression was found between cases, controls and HI. However TLR9 expression seems lower in individuals with DVT and RT, albeit not significant. Interestingly, TLR9 might play a role in recurrent DVT, as the TLR9 expression was significantly higher in patients with recurrent DVT.

Genetic polymorphisms of vein wall remodeling in chronic venous disease: a narrative and systematic review.

Chronic venous disease encompasses a spectrum of disorders caused by an abnormal venous system. They include chronic venous insufficiency, varicose veins, lipodermatosclerosis, postthrombotic syndrome, and venous ulceration. Some evidence suggests a genetic predisposition to chronic venous disease from gene polymorphisms associated mainly with vein wall remodeling. The literature exploring these polymorphisms has not been reviewed and compiled thus far. In this narrative and systematic review, we present the current evidence available on the role of polymorphisms in genes involved in vein wall remodeling and other pathways as contributors to chronic venous disease. We searched the EMBASE, Medline, and PubMed databases from inception to 2013 for basic science or clinical studies relating to genetic associations in chronic venous disease and obtained 38 relevant studies for this review. Important candidate genes/proteins include the matrix metalloproteinases (extracellular matrix degradation), vascular endothelial growth factors (angiogenesis and vessel wall integrity), FOXC2 (vascular development), hemochromatosis (involved in venous ulceration and iron absorption), and various types of collagen (contributors to vein wall strength). The data on associations between these genes/proteins and the postthrombotic syndrome are limited and additional studies are required. These associations might have future prognostic and therapeutic implications.

Residual vein thrombosis and onset of post-thrombotic syndrome: influence of the 4G/5G polymorphism of plasminogen activator inhibitor-1 gene.

BACKGROUND: Plasminogen activator inhibitor-1 (PAI-1) is the most important inhibitor of plasminogen activator. The functional 4G/5G polymorphism of the gene coding for PAI-1 may affect PAI-1 plasmatic activity, influencing the imbalance between coagulation and fibrinolysis cascades. In this prospective cohort analytic study, we investigated the role of this single nucleotide polymorphism in the persistence of thrombotic lesion and the occurrence of post-thrombotic syndrome. PATIENTS/METHODS: In a group of 168 patients with post-surgical deep vein thrombosis of the legs, we analyzed the 4G/5G polymorphism in the promoter of PAI-1 gene and plasmatic PAI-1 activity. Enrolled patients were divided in two groups: patients with 4G/5G polymorphism and increased PAI-1 activity (n=85) and patients without 4G/5G polymorphism and normal PAI-1 activity (n=83). All patients were treated according to current protocols and re-examined after 3, 12 and 36 months in order to evaluate the persistence of thrombotic lesion and the occurrence of post-thrombotic syndrome. RESULTS: We found a significantly increased PAI activity in carrier of the 4G allele, who experienced much more frequently a persistence of thrombosis after 3, 12 and 36 months and/or the development of post-thrombosis syndrome, in spite of the anticoagulant treatment. CONCLUSIONS: These data not only confirm the role played by PAI-1 activity and by the 4G/5G SNP of the PAI-1 gene, but also suggest that current therapeutic protocols, recommending the administration of low weight molecular heparin and oral anticoagulant for the treatment of deep vein thrombosis, could be non sufficient for patients genetically predisposed to a less efficient clot lysis.

Deletion of cysteine-cysteine receptor 7 promotes fibrotic injury in experimental post-thrombotic vein wall remodeling.

OBJECTIVE: Deep vein thrombosis (VT) can result in vein wall injury, which clinically manifests as post-thrombotic syndrome. Postinjury fibrosis may be modulated in part through cellular cysteine-cysteine receptor 7 (CCR7)-mediated events. We tested the hypothesis that late vein wall fibrotic remodeling is dependent on CCR7. APPROACH AND RESULTS: CCR7(-/-) and C57BL/6 wild-type mice had inferior vena cava VT induced by nonstasis or stasis mechanisms. In both models, VT size was largest at day 1 and trended down by day 21, and CCR7(+) cells peaked at day 8 in wild-type mice. No significant differences in VT resolution were found in CCR7(-/-) as compared with wild type in either model. In the nonstasis VT model, vein wall changes consistent with fibrotic injury were evidenced by significant increases in collagen I, III, matrix metalloproteinase 2, and transforming growth factor-ß gene expression, increases in α-smooth muscle actin and fibroblast specific protein-1 antigen, and total collagen at 8 days. Correspondingly, SM22α and fibroblast specific protein-1, but not DDR2(+) cells, were increased at 8 days. Early wild-type thrombus exposure inhibited profibrotic gene expression in CCR7(-/-) in ex vivo vein wall culture. Bone marrow chimera experiments further showed that circulating CCR7(+) leukocytes partially rescued midterm profibrotic changes in CCR7(-/-) mice. In human histological sections of chronic thrombosed femoral veins, CCR7(+) cells were present in the fibrotic areas. CONCLUSIONS: Post-thrombotic vein wall remodeling is impaired in CCR7(-/-) mice, with a profibrotic phenotype, is dependent on the thrombotic mechanism, and is mediated by circulating CCR7(+) cells. Unlike other postinjury fibrotic responses, CCR7(+) signaling may be important for positive vein wall remodeling after VT.

Platelet endothelial cell adhesion molecule 1 deficiency misguides venous thrombus resolution.

Platelet endothelial cell adhesion molecule 1 (PECAM-1) is involved in leukocyte migration and angiogenesis, which are key components of venous thrombus resolution. This study investigated the effect of PECAM-1 deficiency on thrombus resolution in FVB/n mice and the extent to which levels of soluble PECAM-1 (sPECAM-1) correlate with delayed thrombus resolution in humans after acute symptomatic deep vein thrombosis (DVT). In a mouse stagnant flow venous thrombosis model Pecam-1(-/-) thrombi were larger, persisted for longer periods of time, and displayed attenuated macrophage invasion and decreased vessel formation in the presence of increased fibrosis. In humans, higher levels of truncated plasma sPECAM-1 possibly cleaved from cell surfaces, were found in patients with delayed thrombus resolution (assessed via duplex-based thrombus scoring) relative to those whose thrombi resolved (median, 25th/75th percentile): 92.5 (87.7/103.4) ng/mL vs 71.5 (51.1/81.0) ng/mL; P < .001. Furthermore, unresolved human deep vein thrombus specimens stained positively with antibodies specific for the extracellular, but not the cytoplasmic domain of PECAM-1, consistent with accumulation of cleaved PECAM-1. Our data suggest a regulatory role of PECAM-1 in venous thrombus resolution and suggest a predictive value of sPECAM-1 for postthrombotic syndrome (PTS) after acute DVT.

[Hereditary hyperferritinemia cataract syndrome]. / Das hereditäre Hyperferritinämie-Katarakt-Syndrom.

HISTORY: A 42-year-old man was found to have a four to six fold increase in the level of plasma ferritin since four years. In the age of 10 he had undergone unilateral resection of a dysplastic kidney associated with systemic hypertension. He had also developed recurrent venous thromboses caused by atresia of the inferior vena cava with azygos continuation, known since 23 years. Iron overload or hemochromatosis had been excluded, but despite numerous investigations the exact cause of the hyperferritinemia had not been elucidated. The patient, his grandfather, his mother and a brother had undergone cataract surgeries in both eyes. He presented at admission with prominent veins over the abdomen a postthrombotic syndrome. INVESTIGATION: Laboratory tests revealed a ferritin level 6 times above the upper limit of normal, but iron, transferrin saturation, and transferrin levels were normal. The patient was on oral anticoagulation (INR 2.2). Molecular genetic tests revealed heterozygous mutation IRE+ 32 G > T. DIAGNOSIS, TREATMENT AND COURSE: The findings indicated a hereditary hyperferritinemia cataract syndrome with an autosomal dominant trait. As functions of other organs are not affected, bilateral cataract surgery is "curative". CONCLUSION: Early and correct diagnosis avoids unnecessary diagnostic and therapeutic interventions, such as extended and repeated laboratory tests, liver biopsies, phlebotomies and chelation therapy.