Excessive Fibrin Deposition Research Articles

Increased expression of factor XIII-A in patients with chronic rhinosinusitis with nasal polyps

Profound edema or formation of a pseudocyst containing plasma proteins is a prominent characteristic of nasal polyps (NP). However, the mechanisms underlying NP retention of plasma proteins in the submucosa remain unclear. Recently, we reported that impairment of fibrinolysis causes excessive fibrin deposition in NP and this might be involved in the retention of plasma proteins. Although the coagulation cascade plays a critical role in fibrin clot formation at extravascular sites, the expression and role of coagulation factors in NP remain unclear. The objective of this study was to investigate the expression of coagulation factors in patients with chronic rhinosinusitis (CRS). Sinonasal tissues were collected from patients with CRS and control subjects. We assayed mRNA for factor XIII-A (FXIII-A) by using real-time PCR and measured FXIII-A protein by means of ELISA, immunohistochemistry, and immunofluorescence. FXIII-A mRNA levels were significantly increased in NP tissue from patients with CRS with NP (P < .001) compared with uncinate tissue from patients with CRS or control subjects. Similarly, FXIII-A protein levels were increased in NP. Immunofluorescence analysis revealed that FXIII-A expression in inflammatory cells and FXIII-A(+) cell numbers were significantly increased in NP. Most FXIII-A staining was observed within CD68(+)/CD163(+) M2 macrophages in NP. Levels of FXIII-A correlated with markers of M2 macrophages, suggesting that M2 macrophages are major FXIIIA-producing cells in NP. Overproduction of FXIII-A by M2 macrophages might contribute to the excessive fibrin deposition in the submucosa of NP, which might contribute to the tissue remodeling and pathogenesis of CRS with NP.

Excessive Fibrin Deposition Caused by a Fibrinolytic Disorder Associated with Reduction of Tissue Plaminogen Activator Expression in Nasal Polyps

Excessive Fibrin Deposition Caused by a Fibrinolytic Disorder Associated with Reduction of Tissue Plaminogen Activator Expression in Nasal Polyps

The Impact and Nature of Inflammation in the Olfactory Cleft On Olfaction in Patients with Chronic Rhinosinusitis

S A T U R D A Y 210 Excessive Fibrin Deposition Caused by a Fibrinolytic Disorder Associated with Reduction of Tissue Plaminogen Activator Expression in Nasal Polyps Tetsuji Takabayashi, MD, Atsushi Kato, PhD, Anju Peters, MD, Kathryn E. Hulse, PhD, Lydia Suh, BSc, Roderick Carter, BSc, James Norton, MS, Leslie C. Grammer, MD, FAAAAI, Seong Ho Cho, MD, Bruce Tan, MD, Rakesh Chandra, MD, David Conley, MD, Robert Kern, MD, Shigeharu Fujieda, MD, Robert P. Schleimer, PhD, FAAAAI; Northwestern University Feinberg School Medicine, Chicago, IL, Northwestern University Feinberg School of Medicine, Chicago, IL, Department of Medicine, Division of Allergy-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL, Northwestern University Feinberg School of Medicine, Chicago, IL, University of Fukui, Fukui, Japan. RATIONALE: Nasal polyps (NP) are characterized by intense edema or pseudocyst formation with a high content of plasma proteins, mainly albumin. However, the mechanisms underlying NP retention of plasma proteins in submucosa remain unclear. We hypothesized that formation of fibrin mesh retains plasma proteins in NP.We assessed the fibrin deposition and expression of the fibrinolytic components in patients with chronic rhinosinusitis (CRS). METHODS: We collected nasal tissue from patients with CRS and control subjects. We assessed fibrin deposition by means of immunofluorescence. Fibrinolytic components, d-dimer and plasminogen activators were measured using ELISA, real-time PCR, and immunohistochemistry. We also performed gene expression and protein quantification analysis in primary airway epithelial cells. RESULTS: Immunofluorescence data showed profound fibrin deposition in NP compared with uncinate tissue (UT) from CRS and control subjects (6.6 fold increase, p<.001). Levels of the cross-linked fibrin cleavage product d-dimer were significantly decreased in NP compared with UT from CRS and control, suggesting reduced fibrinolysis (4.3 fold, p<.01). Expression levels of tissue plasminogen activator (t-PA) mRNA and protein were significantly decreased in NP compared with UT from CRS and control (P < .001). Immunohistochemistry demonstrated clear reduction of t-PA in NP, primarily in the epithelium and glands. Additionally, plasminogen activator protein levels in UT were lower than inferior turbinate tissue from both CRS and control. Th2 cytokine stimulated cultured airway epithelial cells showed downregulation of t-PA. CONCLUSIONS: A reduction of t-PA might lead to excessive fibrin deposition in the submucosa of NP, possibly contributing to the tissue remodeling and pathogenesis of CRSwNP.

Pathologic Etiologies of Late and Very Late Stent Thrombosis following First-Generation Drug-Eluting Stent Placement

Several randomized and observational studies have reported steady increase in cumulative incidence of late and very late ST (LST/VLST) following first-generation drug-eluting stents (DES: sirolimus-(SES) and paclitaxel-(PES)) up to 5 years. Pathologic studies have identified uncovered struts as the primary substrate responsible for LST/VLST following DES, where delayed arterial healing is associated with stent struts penetrating into the necrotic core, long/overlapping stents, and bifurcation stenting especially in flow divider region. Grade V stent fracture also induces LST/VLST and restenosis. Hypersensitivity reaction is exclusive to SES as an etiology of LST/VLST, whereas malapposition secondary to excessive fibrin deposition is associated with PES. Uncovered struts can be identified in SES and PES with duration of implant beyond 12 months, particularly in stents placed for “off-label” indications. Neoatherosclerosis is another important contributing factor for VLST in DES and bare metal stents (BMS); however, DES shows rapid and more frequent development of neoatherosclerosis than BMS. Future pathologic studies should address the long-term safety of newer generation DES including zotarolimus- and everolimus-eluting stents in terms of the improvement in reendothelialization, decreased inflammation and fibrin deposition as well as a lower incidence of stent fracture-related adverse events, and reduced neoatherosclerosis, which likely contribute to the decreased risk of LST/VLST and better patient outcomes.

Excessive Fibrin Deposition in Nasal Polyps Caused by Fibrinolytic Impairment through Reduction of Tissue Plasminogen Activator Expression

Nasal polyps (NPs) are characterized by intense edema or formation of pseudocysts filled with plasma proteins, mainly albumin. However, the mechanisms underlying NP retention of plasma proteins in their submucosa remain unclear. We hypothesized that formation of a fibrin mesh retains plasma proteins in NPs. We assessed the fibrin deposition and expression of the components of the fibrinolytic system in patients with chronic rhinosinusitis (CRS). We assessed fibrin deposition in nasal tissue from patients with CRS and control subjects by means of immunofluorescence. Fibrinolytic components, d-dimer, and plasminogen activators were measured using ELISA, real-time PCR, and immunohistochemistry. We also performed gene expression and protein quantification analysis in cultured airway epithelial cells. Immunofluorescence data showed profound fibrin deposition in NP compared with uncinate tissue (UT) from patients with CRS and control subjects. Levels of the cross-linked fibrin cleavage product protein, d-dimer, were significantly decreased in NP compared with UT from patients with CRS and control subjects, suggesting reduced fibrinolysis (P < 0.05). Expression levels of tissue plasminogen activator (t-PA) mRNA and protein were significantly decreased in NP compared with UT from patients with CRS and control subjects (P < 0.01). Immunohistochemistry demonstrated clear reduction of t-PA in NP, primarily in the epithelium and glands. Th2 cytokine-stimulated cultured airway epithelial cells showed down-regulation of t-PA, suggesting a potential Th2 mechanism in NP. A Th2-mediated reduction of t-PA might lead to excessive fibrin deposition in the submucosa of NP, which might contribute to the tissue remodeling and pathogenesis of CRS with nasal polyps.

Fibrin-Induced epithelial-to-mesenchymal transition of peritoneal mesothelial cells as a mechanism of peritoneal fibrosis: effects of pentoxifylline.

Excessive fibrin deposition in the peritoneum is thought to be involved in the development of encapsulating peritoneal sclerosis (EPS), an important cause of morbidity and mortality in peritoneal dialysis patients. We investigated fibrin-induced epithelial-to-mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs) as a possible mechanism of fibrin involvement in EPS. In vitro, fibrin overlay of PMCs altered their morphology; increased α-smooth muscle actin, fibronectin, fibroblast specific protein-1, and αvβ3 integrin expression; and decreased cytokeratin 18 and E-cadherin expression. Fibrin overlay also increased focal adhesion kinase and Src kinase phosphorylation. Fibrin-induced changes were inhibited by treating the cells with αvβ3 integrin antibody or pentoxifylline (PTX). In a rat model, intraperitoneal injection of Staphylococcus aureus and fibrinogen induced severe EPS features, which were attenuated by PTX treatment. PTX-treated rats also showed preserved peritoneal ultrafiltration function and lower concentrations of cytokines than the untreated rats. S. aureus- and fibrinogen-injected rats had higher percentage of cytokeratin-positive cells in the omentum fibrotic tissue than controls; this was also reduced by PTX treatment. Our results suggest that fibrin induces EMT of PMCs by engaging αvβ3 integrin and activating associated kinases. Our EPS animal model showed that fibrin-induced EMT was involved in the pathogenesis of peritoneal fibrosis and was inhibited by PTX.

Thrombin generates previously unidentified C5 products that support the terminal complement activation pathway

AbstractThe coagulation and complement pathways simultaneously promote homeostasis in response to injury but cause tissue damage when unregulated. Mechanisms by which they cooperate are poorly understood. To delineate their interactions, we studied the effects of thrombin and C5 convertase on C5 in purified and plasma-based systems, measuring release of the anaphylatoxin C5a, and generation of C5b, the initial component of the lytic membrane attack complex. Thrombin cleaved C5 poorly at R751, yielding minimal C5a and C5b. However, thrombin efficiently cleaved C5 at a newly identified, highly conserved R947 site, generating previously undescribed intermediates C5T and C5bT. Tissue factor-induced clotting of plasma led to proteolysis of C5 at a thrombin-sensitive site corresponding to R947 and not R751. Combined treatment of C5 with thrombin and C5 convertase yielded C5a and C5bT, the latter forming a C5bT-9 membrane attack complex with significantly more lytic activity than with C5b-9. Our findings provide a new paradigm for complement activation, in which thrombin and C5 convertase are invariant partners, enhancing the terminal pathway via the generation of newly uncovered C5 intermediates. Delineating the molecular links between coagulation and complement will provide new therapeutic targets for diseases associated with excess fibrin deposition and complement activation.

Preeclampsia: the role of tissue factor and tissue factor pathway inhibitor

Preeclampsia (PE) is a multi-system disorder of human pregnancy, whose etiology remains poorly understood. Preeclamptic women are known to have an increased hypercoagulable state that result in excess fibrin deposition in several organs, which compromises their function. Tissue factor (TF) is the main physiological initiator of blood coagulation and its activity is regulated by a specific inhibitor known as Tissue factor pathway inhibitor (TFPI). Based on the important role of TF and TFPI in hemostasis, we hypothesize that their levels may change in the severe PE contributing to exacerbate hypercoagulable state. Some studies have assessed the balance between TF and TFPI in preeclamptic women, but results are inconsistent. Therefore, the aim of this study was to examine these inconsistencies and to assess TF and TFPI plasma levels in three groups of age matched women; pregnant with severe PE (n = 60), normotensive pregnant (n = 50) and normotensive non-pregnant women (n = 50). There was not significantly different among the three groups for TF plasma levels; severe PE women: 338.4 pg/mL (248.1-457.6), normotensive pregnant women: 301.5 pg/mL (216.4-442.9) and normotensive non-pregnant women 393 pg/mL (310.3-522.9). TFPI plasma levels were higher in severe PE comparing to normotensive pregnant women and normotensive non-pregnant women, 115.8 ng/mL (75-149.8); 80.3 ng/mL (59.6-99.7) and 74.5 ng/mL (47.1-98.0), respectively No difference was found between normotensive pregnant women and normotensive non-pregnant women. As for gestational age, a significant difference in TFPI levels was found between severe PE and normotensive pregnant women up to the 33rd week of pregnancy (p = 0.001), and severe PE and non-pregnant women up to the 34th (p = 0.01). In summary, our results indicated that TF plasma levels did not vary in the studied groups, while TFPI plasma levels were significantly increased in severe PE compared to normotensive pregnant and normotensive non-pregnant women. So, our data do not explain the exacerbated hypercoagulability state observed in severe PE. Further studies evaluating genes expression, TF activity and antigen, total and free TFPI and TFPI-2, both in plasma and obstetric tissues, throughout the pregnancy in PE (mild and severe forms) are required.

Maternal Malaria Induces a Procoagulant and Antifibrinolytic State That Is Embryotoxic but Responsive to Anticoagulant Therapy

Low birth weight and fetal loss are commonly attributed to malaria in endemic areas, but the cellular and molecular mechanisms that underlie these poor birth outcomes are incompletely understood. Increasing evidence suggests that dysregulated hemostasis is important in malaria pathogenesis, but its role in placental malaria (PM), characterized by intervillous sequestration of Plasmodium falciparum, proinflammatory responses, and excessive fibrin deposition is not known. To address this question, markers of coagulation and fibrinolysis were assessed in placentae from malaria-exposed primigravid women. PM was associated with significantly elevated placental monocyte and proinflammatory marker levels, enhanced perivillous fibrin deposition, and increased markers of activated coagulation and suppressed fibrinolysis in placental plasma. Submicroscopic PM was not proinflammatory but tended to be procoagulant and antifibrinolytic. Birth weight trended downward in association with placental parasitemia and high fibrin score. To directly assess the importance of coagulation in malaria-induced compromise of pregnancy, Plasmodium chabaudi AS-infected pregnant C57BL/6 mice were treated with the anticoagulant, low molecular weight heparin. Treatment rescued pregnancy at midgestation, with substantially decreased rates of active abortion and reduced placental and embryonic hemorrhage and necrosis relative to untreated animals. Together, the results suggest that dysregulated hemostasis may represent a novel therapeutic target in malaria-compromised pregnancies.

Protease-Activated Receptor 4 (PAR4) Plays a Critical Role in Fetal Loss and Peripheral Thrombosis in a Mouse Model of Thrombophilia

Abstract 373We generated a mouse model of thrombophilia by combining two common risk factors for thrombosis in humans; transgenic for high levels of FIX (TgFIX+) and activated protein C resistance due to factor V Leiden mutation (FVLQ). Breedings were used in which both parents were heterozygous for the FVL (FVLR/Q) mutation, but only one carried the TgFIX+(resulting in ∼5-fold higher of normal levels). More than 200 newborns were obtained but surprisingly no animal of FVLQ/Q/ TgFIX+ genotype was identified. When pregnancies were interrupted at embryonic age of E9.5 to E16.5, no deviation from the expected/observed embryo genotypes ratios was observed. However, the number of reabsorbed embryos increased significantly from 13% (E9.5) to 33% (E.16.5), p<0.02. All FVLQ/Q/ TgFIX+ embryos exhibited findings consistent with disseminated intravascular coagulation. Placental analysis (n=18) of these embryos harvested at E12.5 or later demonstrated prothrombotic abnormalities such as excessive fibrin deposition and innumerous apoptotic cells, determined by TUNEL assay, localized mainly in the labyrinthine trophoblast zone. The maternal genotype clearly influenced the pregnancy outcome since the number of newborns per litter was 2-fold lower when the mother carried the TgFIX+versus the paternal (average 4.3 vs. 8.3, respectively; p<0.02). No other genotypes analyzed (n=112) presented similar abnormalities in either embryos or in placental tissue. Maternal anticoagulant therapy with heparin or specific thrombin or factor Xa inhibitors reverted the prothrombotic placental phenotype, although a few newborns reached to term, none survived beyond day 1. Although FVLR/Q/ TgFIX+mice developed normally when reaching 8–10 months of age we observed a high rate of spontaneous peripheral thrombotic episodes (3/40; 7.5%) and histological analysis confirmed venous thrombosis. Thus, these mice represent a novel murine model of venous thrombosis. Moreover, this complication was also present in 5.2% of the FVLR/R/ TgFIX+ whereas no other age-matched mice (n=74) developed such complications. There was an age-dependent increase in TAT and D-Dimer levels in both prothrombotic strains by comparing samples collected at 2 and 10 months time points. In the FVLR/Q/ TgFIX+ or FVLR/R/ TgFIX+, levels of TAT (70ng/ml, n=28/group) and D-dimers (230ng/ml, n=17/group) were ∼ 2-fold higher (P<0.04), when compared to mice (TAT: 30ng/ml and D-Dimer: 100ng/ml) of other genotypes. Similarly, the highest fibrin deposition determined by Western blot analysis of tissues harvested was found in the FVLR/Q/ TgFIX+ followed by FVLR/R/ TgFIX+ mice when compared to the other animals (P<0.05). Thus, this model provides a unique opportunity to test the effect of modulators of thrombosis in a chronic thrombophilia status rather than simply upon chemical- or laser-induced acute vascular injury. Since thrombin-mediated mouse platelet activation is PAR4 dependent in an acute vascular injury model, we sought to determine whether PAR4 could modulate the prothrombotic phenotype in our chronic thrombophilia model. Using triallelic crosses FVLQ/Q/TgFIX+/PAR4(−/−) and FVLQ/Q/TgFIX+/PAR4(+/−) animals were generated. Interestingly, we were able to rescue the fetal mortality of FVLQ/Q/ TgFIX+by introducing just one PAR4 null allele. Notably, PAR4 deficiency in heterozygous or homozygous mice of FVLQ/Q/ TgFIX+allowed them to reach term and develop normally. Kaplan-Meier analysis of both FVLQ/Q/TgFIX+/PAR4(−/−)and FVLQ/Q/TgFIX+/PAR4(+/−)mice showed survival rates of 87.5% and 65%, respectively, at the 10-month time point (ongoing observation). Notably, these rescued mice showed no evidence of peripheral thrombosis. In conclusion, we have characterized a mouse model of chronic hypercoagulability and have shown that in this model PAR4 plays a central role in modulating thrombophilic complications. Disclosures:No relevant conflicts of interest to declare.

Therapeutic Modulation of Coagulation and Fibrinolysis in Acute Lung Injury and the Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) are characterized by excessive intraalveolar fibrin deposition, driven, at least in part by inflammation. The imbalance between activation of coagulation and inhibition of fibrinolysis in patients with ALI/ARDS favors fibrin formation and appears to occur both systemically and in the lung and airspace. Tissue factor (TF), a key mediator of the activation of coagulation in the lung, has been implicated in the pathogenesis of ALI/ARDS. As such, there have been numerous investigations modulating TF activity in a variety of experimental systems in order to develop new therapeutic strategies for ALI/ARDS. This review will summarize current understanding of the role of TF and other proteins of the coagulation cascade as well the fibrinolysis pathway in the development of ALI/ARDS with an emphasis on the pathways that are potential therapeutic targets. These include the TF inhibitor pathway, the protein C pathway, antithrombin, heparin, and modulation of fibrinolysis through plasminogen activator- 1 (PAI-1) or plasminogen activators (PA). Although experimental studies show promising results, clinical trials to date have proven unsuccessful in improving patient outcomes. Modulation of coagulation and fibrinolysis has complex effects on both hemostasis and inflammatory pathways and further studies are needed to develop new treatment strategies for patients with ALI/ARDS.

Pathology of First-generation Drug-eluting Stents in Humans

First-generation sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES) have dramatically reduced restenosis, although concern still exists about the long-term safety of this technology since observational studies have shown a steady increase in the rate of late stent thrombosis (LST), an infrequent but catastrophic complication. Although the mechanisms of LST are multifactorial, our laboratory has demonstrated that delayed arterial healing accompanied by poor endothelialisation is the primary pathogical substrate underlying this event. Delayed arterial healing is associated with penetration of necrotic core, long/overlapping stents and bifurcation stenting, especially in flow divider (high shear) regions. Grade V stent fracture is also associated with adverse pathogical findings including LST and restenosis. Moreover, localised hypersensitivity reaction is exclusive to SES as an underlying mechanism of LST, while malapposition secondary to excessive fibrin deposition is associated with PES. Uncovered struts are still identified in both SES and PES with implant duration beyond 12 months, particularly in stents placed for ‘off-label’ indications. In conclusion, the first generation of drug-eluting stents (DES) certainly reduce neointimal growth but this comes at the price of delayed healing.

Pathology of First-generation Drug-eluting Stents in Humans

First-generation sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES) have dramatically reduced restenosis, although concern still exists about the long-term safety of this technology since observational studies have shown a steady increase in the rate of late stent thrombosis (LST), an infrequent but catastrophic complication. Although the mechanisms of LST are multifactorial, our laboratory has demonstrated that delayed arterial healing accompanied by poor endothelialisation is the primary pathogical substrate underlying this event. Delayed arterial healing is associated with penetration of necrotic core, long/overlapping stents and bifurcation stenting, especially in flow divider (high shear) regions. Grade V stent fracture is also associated with adverse pathogical findings including LST and restenosis. Moreover, localised hypersensitivity reaction is exclusive to SES as an underlying mechanism of LST, while malapposition secondary to excessive fibrin deposition is associated with PES. Uncovered struts are still identified in both SES and PES with implant duration beyond 12 months, particularly in stents placed for ‘off-label’ indications. In conclusion, the first generation of drug-eluting stents (DES) certainly reduce neointimal growth but this comes at the price of delayed healing.

Coronary Responses and Differential Mechanisms of Late Stent Thrombosis Attributed to First-Generation Sirolimus- and Paclitaxel-Eluting Stents

The purpose of this study was to assess the mechanism(s) of late stent thrombosis (LST) and vascular healing responses in first-generation polymeric drug-eluting stents (DES). Recent clinical trials have reported variations in late lumen loss between first-generation sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES). Little is known, however, about the vascular responses, time course of healing, and underlying mechanism(s) of complications of LST between platforms in human coronary implants. The overall analysis included 174 cases (230 DES lesions) from the CVPath Institute's stent registry. Histomorphometry was performed on coronary stents from 127 patients (171 lesions) who died ≥ 30 days after receiving stent implants in which fibrin deposition, endothelial strut coverage, inflammatory response, and mechanism(s) of in-stent thrombosis were assessed. Both platforms demonstrated increased neointimal thickness over time where values were greater in PES (mean 0.13 mm; range 0.03 to 0.20 mm) than SES (mean 0.10 mm; range 0.04 to 0.15 mm; p = 0.04). The percentage of uncovered struts was similar between SES and PES including stents with LST (SES = 21% vs. PES = 27%; p = 0.47). The underlying mechanism(s) of LST, however, was strikingly different between platforms; localized strut hypersensitivity was exclusive to SES, whereas malapposition secondary to excessive fibrin deposition was the underlying cause in PES. Moreover, although both PES and SES showed nearly complete strut coverage after 12 months for on-label use, the majority of stents placed for off-label indications remained unhealed after 12 months in both types of DES. Differential mechanisms of LST involving either hypersensitivity or excessive fibrin were identified between first-generation DES in which overall stent healing was further delayed in DES placed for off-label indications.

Placental expression of proteases and their inhibitors in patients with HELLP syndrome

In preeclampsia and hemolysis, elevated liver enzymes and low platelet (HELLP) syndrome, impaired trophoblast invasion and excessive fibrin deposition in the placental intervillous space is associated with fetal compromise. However, little information is available whether modulation of placental protease expression--potentially causing impaired trophoblast invasion--is associated with the HELLP syndrome. Total RNA and protein were extracted from placental tissue from 11 females with HELLP syndrome and 8 controls matched for gestational age. mRNA expression of matrix metalloprotease (MMP) -2 and -9, tissue inhibitors of metalloprotease (TIMP) -1, -2, and -3, and urokinase-type plasminogen activator receptor (uPAR) was determined by Northern blotting. Protein expression of MMP-2 and -9, and TIMP-1 and -2 was detected by Western blotting and that of uPA, uPAR, and plasminogen activator inhibitor (PAI) -1 by ELISA. In patients with HELLP syndrome, mRNA expression of MMP-2 and TIMP-2 was decreased, whereas TIMP-1 and -3 levels were unchanged. MMP-9 and uPAR mRNA was undetectable in both groups. Protein expression of all investigated proteolytic factors remained unchanged. Our findings at the mRNA level suggest a decrease in matrix remodeling in placentae from patients with HELLP syndrome compared with control pregnancies, although this is not supported at the protein level.

Coagulation Parameters in Cattle with Left Displacement of Abomasum

position of abomasum is positioned below the rumen in the right of the ventral midline. Left displacement of abomasum (LDA) is a condition in which abomasum is trapped between the rumen and left abdominal wall. LDA occurs most commonly in large, high-producing adult dairy cows after parturition (1). Many papers have been described risk factors, pathogenesis, diagnosis, treatment and outcome of LDA up to date . There is increasing recognition that abnormalities in blood clotting and fibrinolysis occur in both subclinical and clinical forms in many diseases . Disseminated intravascular coagulopathy (DIC) is a pathological process characterized by excessive fibrin deposition in microcirculatory system with ischemia, functional disorders, and a tendency for bleeding . This extreme of the clotting disorder is may vary in severity from occurrence of petechial haemorrhages in mucous membranes to life Kafkas Univ Vet Fak Derg 15 (2): 293-296, 2009 DOI:10.9775/kvfd.2009.012-A SHORT COMMUNICATION

Pulmonary Coagulopathy as a New Target in Lung Injury - A Review of Available Pre-Clinical Models

Despite recent advances in supportive care, acute lung injury (ALI) and its more severe form acute respiratory distress syndrome (ARDS) are clinical entities with high morbidity and high mortality. In systemic inflammation, like sepsis, uncontrolled host defense can lead to systemic activation of coagulation on the one hand, and attenuation of fibrinolysis on the other. In ALI/ARDS similar but local disturbances in fibrin turnover occur, leading to excessive alveolar fibrin deposition compromising pulmonary integrity and function. Therapies in patients with sepsis have specifically focused on coagulation disturbances. Evidence from preclinical and clinical investigations suggests pharmacologically targeting pulmonary "coagulopathy" could be of benefit to patients with ALI/ARDS as well. Recent animal studies have demonstrated that administration of heparins, activated protein C (APC), Antithrombin (AT), Tissue factor-Factor VIIa (TF-FVIIa) pathway inhibitors, plasminogen activators (PA) and thrombomodulin (TM) can attenuate pulmonary coagulopathy and reduce lung injury and/or improve oxygenation. Some of these studies have also shown anti-inflammatory effects of treatment targeting at coagulation. To date there are no published studies that have specifically studied the effects of anticoagulants on ALI/ARDS however there are on-going clinical trials. A solid base has to be provided by preclinical studies to justify clinical studies on new pharmacologic therapies for ALI/ARDS. In this systematic literature review we give an overview of the models for ALI/ARDS that have been used so far on the topic of pulmonary coagulopathy and focus on the pharmacological interventions that have been evaluated with these models. Finally, the applicability of the different approaches for future research on this subject will be discussed.

Current view on alveolar coagulation and fibrinolysis in acute inflammatory and chronic interstitial lung diseases

Acute inflammatory and chronic interstitial lung diseases are characterized by excessive and persistent fibrin deposition in the lung. Intraalveolar fibrin accumulation, observed under these conditions, arises from a leakage of plasma proteins (including fibrinogen) into the alveolar space in combination with a disbalance of alveolar haemostasis. Tissue factor in association with factor VIIa and inhibition of urokinase by plasminogen activator inhibitor-1 are major factors that are responsible for the procoagulant and antifibrinolytic state. In addition, in acute respiratory distress syndrome (ARDS) patients, factor VII-activating protease and extracellular RNA, which may be released into the extracellular milieu from damaged cells during lung injury, may contribute to fibrin formation as well. Fibrin itself can increase vascular permeability, influence the expression of inflammatory mediators and alter the migration and proliferation of various cell types. Additionally, fibrin may inactivate pulmonary surfactant and provide a matrix on which fibroblasts can migrate and produce collagen. Furthermore, cellular activities of haemostatic proteases may also contribute to proinflammatory and fibrotic processes in the lung. The application of coagulation inhibitors, like tissue factor pathway inhibitor, active site-inactivated factor VIIa, activated protein C, antithrombin, heparin or hirudin turned out to be beneficial in experimental models of acute and chronic lung injury. However, the ability of anticoagulant and profibrinolytic agents to improve clinical outcome remains to be elucidated. In the current article, the role of the alveolar coagulation and fibrinolysis systems in acute inflammatory and chronic interstitial lung diseases is discussed with regard to pathomechanisms and modalities of intervention.

Differential Release of Plasminogen Activator Inhibitors (PAIs) During Dual Perfusion of Human Placenta: Implications in Preeclampsia

Plasminogen activator inhibitors (PAIs) play critical roles in regulating cellular invasion and fibrinolysis. An increase in the ratio of PAI-1/PAI-2 in placenta and maternal serum is suggested to result in excessive intervillous fibrin deposition and placental infarction in pregnancies complicated by preeclampsia (PE) and intrauterine growth restriction (IUGR). In the current study we used dual (maternal and fetal) perfusion of human term placentas to examine the release of PAIs to the intervillous space. ELISA revealed a significant time-dependent increase in total PAI-1 levels in maternal perfusate (MP) between 1 and 7 h of perfusion. Conversely, PAI-2 levels decreased resulting in a 3-fold increase in the PAI-1/PAI-2 ratio in MP. Levels of PAI-1, but not PAI-2, in placental tissue extracts increased during perfusion. In perfusions carried out with xanthine and xanthine oxidase (X + XO), compounds used to generate reactive oxygen species (ROS), no time-dependent increase in total PAI-1 levels was observed. In addition, X + XO treatment promoted a 3-fold reduction in active PAI-1 levels in MP, indicating that ROS decrease PAI-1 release to MP. The finding of a time-dependent change in patterns of PAI expression and response to ROS indicates the utility of dual perfusion as a model to dissect mechanism(s) promoting aberrant fibrinolysis in pregnancies complicated by PE and IUGR.

Effects of aspirin on placenta and perinatal outcomes in patients with poor obstetric history

The aim of this study was to compare a low-dose aspirin treatment on placental and perinatal effects in the patients with poor obstetric history such as preeclampsia, intrauterine growth retardation (IUGR) in previous pregnancy. This retrospective study of 86 pregnant women was conducted between April 2002 and June 2005. In this study period 364 placentas were examined and the patients with poor obstetric history such as IUGR and preeclampsia were selected. Then the patients were assigned to three groups; group 1 (n = 30) was composed of women with no risk in previous pregnancy; group 2 (n = 27) was composed of patients with poor obstetric history (e.g., preeclampsia, IUGR) who were treated with aspirin and patients in group 3 (n = 29) had poor obstetric history without any treatment (patients who were started to follow-up after 14 weeks of gestation). Patients in group 2 were treated with a low-dose aspirin (80 mg/day) as soon as a urinary pregnancy test was positive. Treatment was usually stopped at 34 completed weeks of gestation. On histopathologic examination of the placenta, uteroplacental vascular pathologic features and secondary villous damage (such as fibrinoid necrosis of desidual vessels, villous infarct, severely increased villous fibrosis, severely increased syncytiotrophoblast knotting, obliteration of the vessel lumen, severely increased villous hypervascularity) and also lesions involving coagulation (such as excessive perivillous fibrin deposition, multiple occlusive thrombi in uteroplacental vessels, avascular villi ) were examined. There were no significant differences between the groups with respect to maternal age, body mass index at the first trimester and delivery. Also there were no significant differences among groups with respect to placental weight, fetal height, weight, gestational week, umbilical artery pH, pO2, pCO2 and base excess status. The incidences of preeclampsia were 3.3, 7.4, 6.8% and the incidences of IUGR were 6.7, 11.1, 6.8% in the groups, respectively (P > 0.05 for both). Although the percentages of all pathologic findings were higher in groups 2 and 3, these differences were not statistically important. When low-dose aspirin is taken, starting at the beginning of pregnancy in patients with poor obstetric history, there are still high frequencies of uteroplacental vascular and related villous lesions persisted on placental bed. Also it has no beneficial effects on perinatal outcomes in these patients.