Prothrombin fragment 1 + 2 and thrombin-antithrombin III complex as markers of activation of blood coagulation in inflammatory bowel diseases

Cardiovascular implications of inflammatory bowel disease: An updated review

Emerging data highlights the heightened risk of atherosclerotic cardiovascular diseases (ASCVD) in patients with chronic inflammatory disorders, particularly those afflicted with inflammatory bowel disease (IBD). This review delves into the epidemiological connections between IBD and ASCVD, elucidating potential underlying mechanisms. Furthermore, it discusses the impact of current IBD treatments on cardiovascular risk. Additionally, the cardiovascular adverse effects of novel small molecule drugs used in moderate-to-severe IBD are investigated, drawing parallels with observations in patients with rheumatoid arthritis. This article aims to comprehensively evaluate the existing evidence supporting these associations. To achieve this, we conducted a meticulous search of PubMed, spanning from inception to August 2023, using a carefully selected set of keywords. The search encompassed topics related to IBD, such as Crohn's disease and ulcerative colitis, as well as ASCVD, including coronary artery disease, cardiovascular disease, atrial fibrillation, heart failure, conduction abnormalities, heart blocks, and premature coronary artery disease. This review encompasses various types of literature, including retrospective and prospective cohort studies, clinical trials, meta-analyses, and relevant guidelines, with the objective of providing a comprehensive overview of this critical intersection of inflammatory bowel disease and cardiovascular health.

Thromboembolic Events in Patients with Inflammatory Bowel Disease: A Comprehensive Overview

Inflammatory bowel disease (IBD), Crohn’s disease and ulcerative colitis are chronic inflammatory disorders of the intestines. The underlying inflammation activates the coagulation cascade leading to an increased risk of developing arterial and venous thromboembolic events such as deep vein thrombosis and pulmonary embolism. Patients with IBD are at a 2–3-fold increased risk of developing thromboembolism. This risk increases in patients with active IBD disease, flare-ups, surgery, steroid treatment, and hospitalization. These complications are associated with significant morbidity and mortality making them important in clinical practice. Clinicians should consider the increased risk of thromboembolic events in patients with IBD and manage them with appropriate prophylaxis based on the risk. In this review, we discuss the literature associated with the pathophysiology of thromboembolism in patients with IBD, summarize the studies describing the various thromboembolic events, and the management of thromboembolism in patients with IBD.

Frequency and risk factors for thromboembolic complications in patients with inflammatory bowel diseases

Background. Inflammatory bowel diseases (IBD) are characterized by chronic immune inflammation of the mucous membrane and/or the thickness of the intestinal wall, and are also accompanied by disorders of the blood clotting system and the development of a hypercoagulation state. Aim. To identify the frequency of thromboembolic complications (TEC) in IBD patients and to determine the influence of acquired and inherited hypercoagulation factors that contribute to the development of TEС. Materials and methods. The clinical status of 1,238 IBD patients who were treated in 2019 was evaluated. Of these, 748 patients with ulcerative colitis (UC) and 490 patients with Crohn's disease (CD). Among UC patients, there were 369 (49.3%) men and 379 (50.7%) women. In 10.1% of patients with UC, there were clinically significant feasibility studies. There were 227 (46.3%) men and 263 (53.7%) women among patients with CD; 7.3% of patients with CD had clinically significant feasibility studies. Results. In general 112 (9.0%) of 1,238 IBD patients had clinically significant feasibility studies. Among patients with UC (n=748), 76 (10.2%) showed clinically significant feasibility studies. Among patients with CD (n=490), 36 (7.3%) had a feasibility study. Of 112 IBD patients with clinically significant TEC, 45 (40.2%) had genetic polymorphisms that increase affinity for fibrinogen, increase platelet aggregation, and contribute to a decrease in the activity of folate cycle enzymes, including methylenetetrahydrofolate reductase, which may be manifested by a moderate increase in homocysteine levels. Of the 45 IBD patients with clinically significant TEC due to inherited factors, 30 (66.6%) patients had UC, 15 (33.7%) patients had CD (hazard ratio 1.038, 95% confidence interval 0.7461.444; 2=0.049; p=0.83921); 67 (59.8%) patients with IBD who had clinically significant TEC did not have genetic polymorphisms leading to hypercoagulation. Conclusion. Based on the analysis, we can conclude that such risk factors for the development of TEC as the status of a smoker, long bed rest, taking hormonal contraceptives, varicose veins of the lower extremities, high activity of the disease, glucocorticoids therapy, the extent of intestinal damage in patients with IBD, genetic factors, should be taken into account by gastroenterologists in the treatment of patients with UC and CD. The hereditary factor of hypercoagulation equally affects the development of TEC, both in patients with UC and CD.

Liver-side of inflammatory bowel diseases: Hepatobiliary and drug-induced disorders

Hepatobiliary disorders are among the most common extraintestinal manifestations in inflammatory bowel diseases (IBD), both in Crohn’s disease and ulcerative colitis (UC), and therefore represent a diagnostic challenge. Immune-mediated conditions include primary sclerosing cholangitis (PSC) as the main form, variant forms of PSC (namely small-duct PSC, PSC-autoimmune hepatitis overlap syndrome and IgG4-related sclerosing cholangitis) and granulomatous hepatitis. PSC is by far the most common, presenting in up to 8% of IBD patients, more frequently in UC. Several genetic foci have been identified, but environmental factors are preponderant on disease pathogenesis. The course of the two diseases is typically independent. PSC diagnosis is based mostly on typical radiological findings and exclusion of secondary cholangiopathies. Risk of cholangiocarcinoma is significantly increased in PSC, as well as the risk of colorectal cancer in patients with PSC and IBD-related colitis. No disease-modifying drugs are approved to date. Thus, PSC management is directed against symptoms and complications and includes medical therapies for pruritus, endoscopic treatment of biliary stenosis and liver transplant for end-stage liver disease. Other non-immune-mediated hepatobiliary disorders are gallstone disease, whose incidence is higher in IBD and reported in up to one third of IBD patients, non-alcoholic fatty liver disease, pyogenic liver abscess and portal vein thrombosis. Drug-induced liver injury (DILI) is an important issue in IBD, since most IBD therapies may cause liver toxicity; however, the incidence of serious adverse events is low. Thiopurines and methotrexate are the most associated with DILI, while the risk related to anti-tumor necrosis factor-α and anti-integrins is low. Data on hepatotoxicity of newer drugs approved for IBD, like anti-interleukin 12/23 and tofacitinib, are still scarce, but the evidence from other rheumatic diseases is reassuring. Hepatitis B reactivation during immunosuppressive therapy is a major concern in IBD, and adequate screening and vaccination is warranted. On the other hand, hepatitis C reactivation does not seem to be a real risk, and hepatitis C antiviral treatment does not influence IBD natural history. The approach to an IBD patient with abnormal liver function tests is complex due to the wide range of differential diagnosis, but it is of paramount importance to make a quick and accurate diagnosis, as it may influence the therapeutic management.

Human endothelial cells and fibroblasts express and produce the coagulation proteins necessary for thrombin generation

In a previous study, we reported that human endothelial cells (ECs) express and produce their own coagulation factors (F) that can activate cell surface FX without the additions of external proteins or phospholipids. We now describe experiments that detail the expression and production in ECs and fibroblasts of the clotting proteins necessary for formation of active prothrombinase (FV-FX) complexes to produce thrombin on EC and fibroblast surfaces. EC and fibroblast thrombin generation was identified by measuring: thrombin activity; thrombin-antithrombin complexes; and the prothrombin fragment 1.2 (PF1.2), which is produced by the prothrombinase cleavage of prothrombin (FII) to thrombin. In ECs, the prothrombinase complex uses surface-attached FV and γ-carboxyl-glutamate residues of FX and FII to attach to EC surfaces. FV is also on fibroblast surfaces; however, lower fibroblast expression of the gene for γ-glutamyl carboxylase (GGCX) results in production of vitamin K-dependent coagulation proteins (FII and FX) with reduced surface binding. This is evident by the minimal surface binding of PF1.2, following FII activation, of fibroblasts compared to ECs. We conclude that human ECs and fibroblasts both generate thrombin without exogenous addition of coagulation proteins or phospholipids. The two cell types assemble distinct forms of prothrombinase to generate thrombin.

Shedding Light on Hemostasis in Patients With Inflammatory Bowel Diseases

Patients with inflammatory bowel diseases (IBD) have an increased risk of thrombosis, possibly due to changes in blood cells and molecules involved in hemostasis. They have increased platelet counts and reactivity as well as increased platelet-derived large extracellular vesicles. Coagulation is continuously activated in patients with IBD, based on measured markers of thrombin generation, and the anticoagulant functions of endothelial cells are damaged. Furthermore, fibrinogen is increased and fibrin clots are denser. However, pathogenesis of thrombosis in patients with IBD appears to differ from that of patients without IBD. Patients with IBD also take drugs that might contribute to risk of thrombosis, complicating the picture. We review the features of homeostasis that are altered in patients with IBD and possible mechanisms of this relationship.

The Role of Extracellular Matrix Components in Inflammatory Bowel Diseases

The remodeling of extracellular matrix (ECM) within the intestine tissues, which simultaneously involves an increased degradation of ECM components and excessive intestinal fibrosis, is a defining trait of the progression of inflammatory bowel diseases (IBDs), which include ulcerative colitis (UC) and Crohn's disease (CD). The increased activity of proteases, especially matrix metalloproteinases (MMPs), leads to excessive degradation of the extracellular matrix and the release of protein and glycoprotein fragments, previously joined with the extracellular matrix, into the circulation. MMPs participate in regulating the functions of the epithelial barrier, the immunological response, and the process of wound healing or intestinal fibrosis. At a later stage of fibrosis during IBD, excessive formation and deposition of the matrix is observed. To assess changes in the extracellular matrix, quantitative measurement of the concentration in the blood of markers dependent on the activity of proteases, involved in the breakdown of extracellular matrix proteins as well as markers indicating the formation of a new ECM, has recently been proposed. This paper describes attempts to use the quantification of ECM components as markers to predict intestinal fibrosis and evaluate the healing process of the gut. The markers which reflect increased ECM degradation, together with the ones which show the process of creating a new matrix during IBD, allow the attainment of important information regarding the changes in the intestinal tissue, epithelial integrity and extracellular matrix remodeling. This paper contains evidence confirming that ECM remodeling is an integral part of directional cell signaling in the progression of IBD, and not only a basis for the ongoing processes.

Experimental and Clinical Evidence of Endothelial Dysfunction in Inflammatory Bowel Disease

The endothelium has a crucial role in proper hemodynamics. Inflammatory bowel disease (IBD) is mainly a chronic inflammatory condition of the gastrointestinal tract. However, considerable evidence points to high cardiovascular risk in patients with IBD. This review positions the basic mechanisms of endothelial dysfunction in the IBD setting (both clinical and experimental). Furthermore, we review the main effects of drugs used to treat IBD in endothelial (dys)function. Moreover, we leave challenging points for enlarging the therapeutic arsenal for IBD with new or repurposed drugs that target endothelial dysfunction besides inflammation.

Platelet hyaluronidase-2 regulates the early stages of inflammatory disease in colitis

Platelets are specialized cells essential for hemostasis that also function as crucial effectors capable of mediating inflammatory and immune responses. These sentinels continually survey their environment and discriminate between homeostatic and danger signals such as modified components of the extracellular matrix. The glycosaminoglycan hyaluronan (HA) is a major extracellular matrix component that coats the vascular lumen and, under normal conditions, restricts access of inflammatory cells. In response to tissue damage, the endothelial HA matrix enhances leukocyte recruitment and regulates the early stages of the inflammatory response. We have shown that platelets can degrade HA from the surface of activated endothelial cells via the enzyme hyaluronidase-2 (HYAL2) and that HYAL2 is deficient in platelets isolated from patients with inflammatory bowel disease (IBD). Platelets are known to be involved in the pathogenesis of several chronic disease states, including IBD, but they have been largely overlooked in the context of intestinal inflammation. We therefore wanted to define the mechanism by which platelet HYAL2 regulates the inflammatory response during colitis. In this study, we provide evidence that HA catabolism is disrupted in human intestinal microvascular endothelial cells isolated from patients with IBD. Furthermore, mice deficient in HYAL2 are more susceptible to an acute model of colitis, and this increased susceptibility is abrogated by transfusion of HYAL2-competent platelets. Finally, we show that platelets, via HYAL2-dependent degradation of endothelial HA, regulate the early stages of inflammation in colitis by limiting leukocyte extravasation.

Hyaluronan in inflammatory bowel disease: Cross-linking inflammation and coagulation

Hyaluronan, a major extracellular matrix component, is an active participant in many disease states, including inflammatory bowel disease (IBD). The synthesis of this dynamic polymer is increased at sites of inflammation. Hyaluronan together with the enzymes responsible for its synthesis, degradation, and its binding proteins, directly modulates the promotion and resolution of disease by controlling recruitment of immune cells, by release of inflammatory cytokines, and by balancing hemostasis. This review discusses the functional significance of hyaluronan in the cells and tissues involved in inflammatory bowel disease pathobiology.

Transurethral resection versus holmium laser enucleation of the prostate: A prospective randomized trial comparing perioperative thrombin generation and fibrinolysis

OBJECTIVES

The purpose of this study was to compare transurethral resection of the prostate (TURP) versus holmium laser enucleation of the prostate (HoLEP) in patients with benign prostatic hyperplasia (BPH) focusing on perioperative thrombin generation and fibrinolysis.

METHODS

Sixty-five BPH patients were prospectively randomly assigned to undergo TURP (n = 32) or HoLEP (n = 33). The prothrombin fragment (PF) 1+2, thrombin-antithrombin complex (TAT), tissue plasminogen activator (t-PA), and plasminogen activator inhibitor-1 (PAI-1) were measured preoperatively, at the 1st day and 3rd day after surgery.

RESULTS

PF1+2, TAT, t-PA, and PAI-1 significantly elevated at day 1 and day 3 after surgery (P < .05) and remarkedly decreased from the 1st day to the 3rd day (P < .05). The levels of PF1+2 and TAT were higher in TURP group postoperatively than that in HoLEP group (P < .05). There is no significant difference between 2 groups in regard of t-PA and PAI-1 (P > .05).

CONCLUSION

The activation of thrombin generation and fibrinolysis system were noticed in BPH patients after TURP or HoLEP. TURP may associate with a higher hypercoagulable thrombotic risk than HoLEP.

Overview of Link Between Inflammatory Bowel Disease and Cardiovascular Disease

Inflammation has been shown to play an increasingly important role in the pathogenesis of atherosclerosis and in precipitating thrombotic events. Inflammatory bowel disease (IBD) is a systemic inflammatory disorder with a wide range of extraintestinal manifestations including a clinically significant increase in the risk of venous thromboembolism compared to matched controls in several studies. The data for the association between IBD and ischemic heart disease are less clear; multiple population-based studies have shown both positive and negative associations between the 2 conditions. While the systemic inflammation should theoretically increase the risk for cardiovascular disease, inflammatory bowel also potentially provides a cardioprotective effect in several ways. Patients with IBD typically enter the healthcare system at an earlier age and experience a lower incidence of obesity, hypercholesterolemia, and hyperlipidemia. Given the complex interplay among the proatherogenic, prothrombogenic, and cardioprotective effects, IBD should be taken into consideration as a nontraditional risk factor for cardiovascular disease in specific subsets of patients.

Infliximab for Crohn's Disease: More Than 13 Years of Real-world Experience

BACKGROUND

The purpose of this study was to compare the long-term safety of infliximab and nonbiologic agents as Crohn's disease (CD) therapy.

METHODS

Patients with CD were prospectively evaluated in this large, observational registry.

RESULTS

Patients (n = 6273) participated in this observational registry from July 1999 through March 2012; 3440 (54.8%) received infliximab (20,971 patient-years), and 2833 (45.2%) received other treatments only (14,806 patient-years). Overall, 59,875 infliximab infusions were administered (80%, 5 mg/kg); 3006 (89.9%) patients received ≥2 infusions. Adverse events (AEs), most commonly those related to CD (eg, abdominal pain, diarrhea), and serious AEs occurred at a higher rate among infliximab-treated patients. Mortality (0.57/100 patient-years, 0.67/100 patient-years) and malignancy rates (0.69/100 patient-years, 0.71/100 patient-years) for infliximab-treated and other-treatments-only patients, respectively, were generally similar. Serious infection rates were higher for infliximab-treated (2.15/100 patient-years) than other-treatments-only patients (0.86/100 patient-years). Infliximab dose was not associated with mortality or serious infection. An increased risk of serious infection was observed with age (>52 years vs ≤30 years) when examined in infliximab-treated patients. Nonserious cerebrovascular accidents (13 events, 0.06/100 patient-years; 5 events, 0.03/100 patient-years) and pulmonary embolisms (11 events, 0.05/100 patient-years; 4 events 0.03/100 patient-years) also occurred at higher rates among infliximab-treated patients than other-treatments-only patients.

CONCLUSIONS

Through more than 13 years of registry experience and an overall median duration of patient follow-up >6 years, mortality was similar between the infliximab-treated and other-treatments-only groups. These final cumulative results are representative of real-world experience among infliximab-treated patients with CD and are consistent with the known risks of disease activity and tumor necrosis factor antagonist therapy.

Thrombin Cleavage of Inter-α-inhibitor Heavy Chain 1 Regulates Leukocyte Binding to an Inflammatory Hyaluronan Matrix

Dynamic alterations of the extracellular matrix in response to injury directly modulate inflammation and consequently the promotion and resolution of disease. During inflammation, hyaluronan (HA) is increased at sites of inflammation where it may be covalently modified with the heavy chains (HC) of inter-α-trypsin inhibitor. Deposition of this unique, pathological form of HA (HC-HA) leads to the formation of cable-like structures that promote adhesion of leukocytes. Naive mononuclear leukocytes bind specifically to inflammation-associated HA matrices but do not adhere to HA constitutively expressed under homeostatic conditions. In this study, we have directly investigated a role for the blood-coagulation protease thrombin in regulating the adhesion of monocytic cells to smooth muscle cells producing an inflammatory matrix. Our data demonstrate that the proteolytic activity of thrombin negatively regulates the adhesion of monocytes to an inflammatory HC-HA complex. This effect is independent of protease-activated receptor activation but requires proteolytic activity toward a novel substrate. Components of HC-HA complexes were predicted to contain conserved thrombin-susceptible cleavage sites based on sequence analysis, and heavy chain 1 (HC1) was confirmed to be a substrate of thrombin. Thrombin treatment is sufficient to cleave HC1 associated with either cell-surface HA or serum inter-α-trypsin inhibitor. Furthermore, thrombin treatment of the inflammatory matrix leads to dissolution of HC-HA cable structures and abolishes leukocyte adhesion. These data establish a novel mechanism whereby thrombin cleavage of HC1 regulates the adhesive properties of an inflammatory HA matrix.

Phosphotidylserine exposure and neutrophil extracellular traps enhance procoagulant activity in patients with inflammatory bowel disease

Inflammatory bowel disease (IBD)-associated thromboembolic event often lacks precise aetiology. The aim of this study was to investigate the contribution of phosphatidylserine (PS) exposure and neutrophil extracellular traps (NETs) towards the hypercoagulable state in IBD. We demonstrated that the levels of PS exposed MPs and the sources of MP-origin, platelets, erythrocytes, leukocytes and cultured endothelial cells (ECs) were higher in IBD groups than in healthy controls using flow cytometry and confocal microscopy. Wright-Giemsa and immunofluorescence staining demonstrated that the elevated NETs were released by activated IBD neutrophils or by control neutrophils treated with IBD sera obtained from patients with the active disease. MPs and MP-origin cells in IBD groups, especially in active stage, markedly shortened coagulation time and had increased levels of fibrin, thrombin and FXa production as assessed by coagulation function assays. Importantly, we found that on stimulated ECs, PS rich membranes provided binding sites for FXa and FVa, promoting fibrin formation while TNF blockage or IgG depletion attenuated this effect. Treatment of control neutrophils with TNF and isolated IgG from PR3-ANCA-positive active IBD patients also resulted in the release of NETs. Blockade of PS with lactadherin prolonged coagulation time, decreased fibrin formation to control levels, and inhibited the procoagulant enzymes production in the MPs and MP-origin cells. NET cleavage by DNase I partly decreased PCA in IBD or stimulated neutrophils. Our study reveals a previously unrecognised link between hypercoagulable state and PS exposure or NETs, and may further explain the epidemiological association of thrombosis within IBD patients.

Overview of venous thrombosis in inflammatory bowel disease

Thrombosis in inflammatory bowel disease (IBD) is an increasingly noted extraintestinal manifestation with high morbidity and mortality. While controlling the activity of the disease with the appropriate therapy, thromboembolism prophylaxis should be applied to all patients. All common risk factors for thromboembolism are also valid for patients with IBD; however, it is clear that uncontrolled disease and hospitalization are major disease-specific risk factors for venous thromboembolism in patients with IBD. Pharmacological thromboprophylaxis with currently available anticoagulants does not increase the risk of further bleeding in patients with IBD with mild-to-moderate bleeding. In severe bleeding or with increased risk of further bleeding due to other comorbid conditions, thromboprophylaxy with mechanical methods should be the treatment option. Whether thrombosis is the cause or the result of intestinal inflammation remains to be elucidated, and other issues in the etiology, such as the role of intestinal flora in thrombosis pathogenesis, will be the subject of future studies.

Thrombosis in inflammatory bowel diseases: what's the link?

Inflammatory bowel disease affects more than 2 million people in Europe, with almost 20% of patients being diagnosed in pediatric age. Patients with inflammatory bowel disease are at increased risk of thromboembolic complications which may affect patients’ morbidity and mortality. The risk of the most common thromboembolic events, such as deep venous thrombosis and pulmonary embolism, are estimated to be three-fold increased compared to controls, but many other districts can be affected. Moreover, patients with ulcerative colitis and Crohn’s disease experience thromboembolic events at a younger age compared to general population. Many factors have been investigated as determinants of the pro-thrombotic tendency such as acquired risk factors or genetic and immune abnormalities, but a unique cause has not been found. Many efforts have been focused on the study of abnormalities in the coagulation cascade, its natural inhibitors and the fibrinolytic system components and both quantitative and qualitative alterations have been demonstrated. Recently the role of platelets and microvascular endothelium has been reviewed, as the possible link between the inflammatory and hemostatic process.

The relationship between coagulation state and inflammatory bowel disease: current understanding and clinical implications

Inflammatory bowel disease (IBD) is associated with a hypercoagulable state and subsequently with an increased risk for venous thromboembolism (VTE). VTE in IBD is characterized by a high recurrence rate and is associated with the disease activity. Acquired endothelial dysfunction, abnormalities of platelets, activation of coagulation system and impaired fibrinolysis are the main changes in the coagulation state in IBD. The development of VTE in IBD has been considered to be the result of multiple interactions between acquired and inherited risk factors. The treatment of VTE in IBD patients is recommended to be similar and to follow the same protocols as for non-IBD patients. In the clinical practice, the management of IBD patients and especially the hospitalized patients should include thromboprophylaxis.

Prevalence of hypercoagulable disorders in inflammatory bowel disease

OBJECTIVE. Inflammatory bowel disease (IBD) can be associated with hypercoagulable disorders. Aim of this single-center, prospective study was an in-depth evaluation of acquired hypercoagulable states in IBD patients. METHODS. A total of 110 patients with Crohn's disease (CD) (aged 19-69; mean 40.5, median 38.5 years), 43 with ulcerative colitis (UC) (aged 17-72; mean 42, median 36 years), and 30 controls were enrolled. Full blood count, serum C-reactive protein (CRP), proteins C and S, activated protein C (APC) resistance, thrombin-antithrombin complex (TAT), F1+F2 fragments, tissue factor pathway inhibitor (TFPI) total and truncated, TFPI-factor Xa, tissue plasminogen activator (tPA) and PAI-I antigen were investigated in peripheral blood samples. RESULTS. Only 18 of 153 (11.8%) IBD patients had hemocoagulation parameters within normal range. Significant difference between IBD patients and controls was found in thrombocyte volume (p < 0.001), protein C (p = 0.025), protein S (p = 0.003), APC resistance (p < 0.001), F1+F2 fragments (p < 0.001), and tPA (p = 0.002). In CD patients who were divided into two subgroups according to serum CRP values (non-active disease: <5 mg/L; active disease ≥5 mg/L), thrombocyte count was significantly lower (p = 0.001), thrombocyte volume was significantly higher (p = 0.002), F1+F2 fragments were significantly lower (p = 0.007) and tPA was significantly higher (p = 0.038) in the subgroup with CRP <5 mg/L. In UC patients, no significant difference depending on CRP was found. CONCLUSIONS. Acquired hypercoagulable abnormalities in IBD patients are frequent. Patients with active CD, but not UC, displayed significantly different hemocoagulable parameters, when compared to non-active CD/UC subjects. In patients with active CD (with increased serum CRP concentration) and patients with active extensive UC found at endoscopy (despite low CRP values), prophylactic anticoagulation therapy should be considered.

Clinical syndromes associated with acquired antithrombin deficiency via microvascular leakage and the related risk of thrombosis

Antithrombin (AT) is a 65kDa glycoprotein belonging to a group of inhibitory factors known as serpins (serine protease inhibitors). It plays a critical role in the inhibition of coagulation and inflammation processes within the environment of the vascular endothelium. Inadequate levels of functional AT in plasma results in an increased risk of thrombotic events, both venous and arterial. AT deficiency can be inherited or acquired. Congenital AT deficiency is the most severe inherited thrombophilic condition with an odds ratio of 20 for the increased risk of venous thrombosis. Acquired AT deficiency occurs in a variety of physiologic and pathologic medical conditions with similar risks of increased thrombosis. In this article, we review clinical settings characterized by an acquired AT deficiency largely or partly subsequent to protein microvascular leakage. Other different mechanisms of AT depletion are implied in some clinical conditions together with endothelial loss, and, therefore, outlined. In addition, we provide a description of the current knowledge on the specific mechanisms underlying endothelial AT leakage and on the consequences of this protein decrease, specifically looking at thrombosis. We identify potential directions of research that might prove useful in patients with acquired AT deficiency.

Venous and arterial disease in inflammatory bowel disease

Awareness is increasing that risk of venous thromboembolism and development of atherosclerosis is elevated in patients with some chronic inflammatory diseases. This review aimed to examine the risk of vascular disease in patients with inflammatory bowel disease (IBD) and to identify potential pathogenic mechanisms and therapeutic approaches. An extensive literature search was conducted using MEDLINE database, Cochrane Library and international conference abstracts for studies pertaining to venous and arterial thromboembolism in adult IBD patients. There is a 1.1-3.6 fold risk of venothromboembolism in IBD, affecting 0.55-6.15% of patients. Risks are increased during a flare or with chronically active inflammation. Evidence is building that there may be a modestly increased risk of arterial disease overall, despite evidence that traditional risk factors may be reduced. Multiple pathogenic factors have been identified including endothelial dysfunction, inflammation-mediated calcium deposition in the media of arteries, hyperhomocysteinemia, platelet activation, and altered coagulation and fibrinolysis. The key to active and preventive therapy is to effectively treat inflammation. Recommendations for prophylaxis of venothromboembolism have followed guidelines where they exist and have been extrapolated from studies of other at-risk conditions, as have those for arterial disease, where screening for risk factors and actively treating abnormalities is encouraged. In conclusion, patients with IBD are at considerably increased risk of venothromboembolism and probably of arterial disease, in particular mesenteric ischemia and ischemic heart disease. Increased penetration of gaps between this knowledge and clinical therapeutic action to prevent thromboembolic events into IBD clinical practice is needed.

Venous thrombotic events in hospitalized children and adolescents with inflammatory bowel disease

BACKGROUND

Adults with inflammatory bowel disease (IBD) have an increased risk of venous thrombotic events (TEs). We sought to evaluate the risk for TE in children and adolescents with IBD using a large population database.

METHODS

The triennial Healthcare Cost and Utilization Project Kids' Inpatient Database was used in a retrospective cohort study of hospitalized children in the United States across 1997, 2000, 2003, 2006, and 2009. Billing codes were used to identify discharges with Crohn disease, ulcerative colitis, pulmonary embolism, deep vein thrombosis, thrombophlebitis, thrombosis of intracranial venous sinus, Budd-Chiari syndrome, and portal vein thrombosis. A logistic regression model was fitted to quantify the increased risk of TE in children with IBD, while adjusting for other risk factors of thrombosis.

RESULTS

The total weighted number of pediatric discharges was 7,448,292, and 68,394 (0.92%) were identified with IBD. The incidence of any TE in a hospitalized child or adolescent with IBD was 117.9/10,000 with a relative risk (95% confidence interval) of 2.36 (2.15-2.58). The adjusted odds ratio for any TE in a patient with IBD without surgery was 1.22 (1.08-1.36). Risk factors for TE among patients with IBD include older age, central venous catheter, parenteral nutrition, and an identified hypercoagulable condition. There is an increasing trend of TE in both the IBD and non-IBD patients.

CONCLUSIONS

Hospitalized children and adolescents with IBD are at increased risk for TE. Conservative methods of TE prevention including hydration, mobilization, or pneumatic devices should be considered in hospitalized patients with IBD.

Increased procoagulant function of microparticles in pediatric inflammatory bowel disease: role in increased thrombin generation

OBJECTIVES

Patients with inflammatory bowel disease (IBD) have a higher risk for venous thromboembolism compared with non-IBD subjects. The pathogenic mechanisms of the thrombotic events are not fully understood. We investigated levels of circulating microparticles and their influence on thrombin generation in pediatric patients with IBD during active and quiescent disease compared with healthy controls.

METHODS

Plasma samples were collected from 33 pediatric patients with Crohn disease (CD), 20 pediatric patients with ulcerative colitis (UC), and 60 healthy controls. Microparticles' procoagulant activity was measured by enzyme-linked immunosorbent assay, and the dependency of thrombin generation on microparticles-derived tissue factor was determined by means of calibrated automated thrombography.

RESULTS

The procoagulant function of microparticles was significantly increased in patients with active and inactive CD, and active UC compared with controls. Endogenous thrombin potential was significantly higher in patients with CD and UC compared with controls. A minor influence of microparticles on thrombin generation was only observed for patients with active UC.

CONCLUSIONS

Our study shows increased procoagulant function of microparticles in pediatric patients with active and quiescent CD and active UC compared with controls, but demonstrates that they are not a major cause for the higher thrombin generation in pediatric patients with IBD.

Thrombin-antithrombin levels are associated with survival in patients resuscitated from cardiac arrest

BACKGROUND

Following successful resuscitation from cardiac arrest, a prothrombotic state may contribute to end-organ dysfunction. We examined whether the level of serum thrombin-antithrombin (TAT) in patients hospitalized after cardiac arrest was associated with survival or the development of multiple organ failure (MOF).

METHODOLOGY

A prospective cohort study of subjects with in-hospital cardiac arrest (IHCA) or out-of-hospital cardiac arrest (OHCA) treated between 1/1/2007 and 5/30/2010 at a single tertiary care referral center. TAT levels were measured at hospital arrival and 24h after cardiac arrest. Logistic regression was used to determine associations between TAT levels and survival and development of MOF.

RESULTS

Data were available for 86 subjects. TAT levels decreased over time. Initial TAT levels (OR 0.03; 95%CI 0.001, 0.62) and category of illness severity (OR 0.39; 95% CI 0.21, 0.73) were associated with survival. Male gender (OR 3.86; 95% CI 1.17, 12.75) and category of illness severity (OR 1.86; 95% CI 1.09, 3.20), but not TAT levels were associated with development of MOF. Neither the 24-h TAT level, nor the change in TAT from initial to 24h was associated with survival when adjusted for category of illness severity.

CONCLUSIONS

Initial serum TAT levels and category of illness severity are associated with survival. TAT levels are not associated with development of MOF. Initial TAT levels may be a useful prognostic adjunct in the post arrest population.

Thrombin generation in pediatric patients with Crohn's disease

BACKGROUND

Patients with inflammatory bowel disease (IBD) have an increased risk of thromboembolic complications. The pathogenesis of IBD is not really clear and a high thrombin activity might contribute to the pathogenesis. We measured thrombin generation by means of calibrated automated thrombography (CAT), a new tool better reflecting overall hemostasis, in children with Crohn's disease (CD) during active and inactive disease and compared it to conventional markers of activity. We wanted to see whether children with CD have a higher potential for thrombin generation and if there is a correlation between hypercoagulability and disease activity.

METHODS

Plasma samples were collected from 22 patients with CD and from 61 healthy children. Thrombin generation was measured by means of CAT. The disease activity was estimated using the Pediatric Crohn's Disease Activity Index (PCDAI). In addition, F1+2, TAT, tissue factor pathway inhibitor (TFPI), fibrinogen, prothrombin (FII), antithrombin (AT), erythrocyte sedimentation rate (ESR), platelet count, α2-globulin, and orosomucoide were measured.

RESULTS

In all patients we found a significantly higher endogenous thrombin potential (ETP) and higher peak values during active disease. In accordance with this we also found significantly higher mean ETP values during active disease compared with the control group. We observed a significantly positive correlation between PCDAI and thrombin generation parameters.

CONCLUSIONS

Our study clearly shows that the active state of CD in children is associated with the potential for high thrombin generation, but this seems to be caused mainly by the inflammatory process and not by a preexisting propensity for high thrombin generation.

Continuous active state of coagulation system in patients with nonthrombotic inflammatory bowel disease

This study was planned for searching possible changes of the total coagulation and fibrinolysis system in inflammatory bowel disease (IBD) in order to obtain some clues for explaining the relation between IBD and hypercoagulability. A total of 24 patients with ulcerative colitis, 12 patients with Crohn disease, and 20 healthy controls were studied. Platelets; prothrombin time (PT); partial thromboplastin time (PTT); fibrinogen; D-dimer; fibrinogen degradation products; protein C; protein S; antithrombin; thrombin time; von Willebrand factor; coagulation factors V, VII, VIII, IX, XI, and XIII; plasminogen; antiplasmin; tissue plasminogen activator; plasminogen activator inhibitor 1; and prothrombin fragments 1 + 2 were studied. Most of the procoagulants (platelets, fibrinogen, von Willebrand factor, coagulation factor IX, and plasminogen activator inhibitor 1) were found increased together with decreases in some anticoagulants (protein S and antithrombin) in IBD. Also the activation markers of coagulation (D-dimer, fibrinogen degradation products, and prothrombin fragments 1 + 2) were all increased. The parameters of the total coagulation-fibrinolysis system were increased in IBD, regardless of the form and the activity of the disease.

Risk of ischemic stroke in patients with Crohn's disease: a population-based nested case-control study

BACKGROUND

Observational studies have linked Crohn's disease (CD) to an increased risk of venous thromboembolic complications. Case reports of ischemic stroke in CD patients have raised the question of a similar association, but data from observational studies are lacking.

METHODS

Using data from the UK General Practice Research Database we conducted a nested case-control analysis within a population-based cohort of 8054 patients with and 161,078 patients without CD. A total of 1748 cases of ischemic stroke were identified to whom 17,348 controls were matched on age, sex, and year of cohort entry. Adjusted odds ratios (ORs) of ischemic stroke associated with CD were calculated by conditional logistic regression. Stratified analyses were performed for age and sex.

RESULTS

While CD was not associated with an overall increased risk of ischemic stroke (OR 1.10, 95% confidence interval [CI] 0.85-1.43), stratified analyses revealed an increase in risk in younger patients (<50 years: OR 2.93; 95% CI 1.44-5.98) but not in elderly patients (> or =50 years: OR 0.99; 95% CI 0.75-1.30; P for interaction <0.01). The interaction with age remained statistically significant even after changing the cutoff value for the younger and older age group to 45, 55, or 60 years in a sensitivity analysis. There was no interaction with sex (P = 0.79).

CONCLUSIONS

The study indicates that younger patients with CD may be under an increased risk of ischemic stroke.

Blood flow patterns spatially associated with platelet aggregates in murine colitis

In the normal murine mucosal plexus, blood flow is generally smooth and continuous. In inflammatory conditions, such as chemically-induced murine colitis, the mucosal plexus demonstrates markedly abnormal flow patterns. The inflamed mucosal plexus is associated with widely variable blood flow velocity as well as discontinuous and even bidirectional flow. To investigate the mechanisms responsible for these blood flow patterns, we used intravital microscopic examination of blood flow within the murine mucosal plexus during dextran sodium sulphate-and trinitrobenzenesulfonic acid-induced colitis. The blood flow patterns within the mucosal plexus demonstrated flow exclusion in 18% of the vessel segments (P < 0.01). Associated with these segmental exclusions was significant variation in neighboring flow velocities. Intravascular injection of fluorescent platelets demonstrated platelet incorporation into both fixed and rolling platelet aggregates. Rolling platelet aggregates (mean velocity 113 microm/sec; range, 14-186 microm/sec) were associated with reversible occlusions and flow variations within the mucosal plexus. Gene expression profiles of microdissected mucosal plexus demonstrated enhanced expression of genes for CCL3, CXCL1, CCL2, CXCL5, CCL7, CCL8, and Il-1b (P < 0.01), and decreased expression of CCL6 (P < 0.01). These results suggest that platelet aggregation, activated by the inflammatory mileau, contributes to the complex flow dynamics observed in acute murine colitis.

Multiple pathogenic roles of microvasculature in inflammatory bowel disease: a Jack of all trades

The etiology of Crohn's disease and ulcerative colitis, the two major forms of inflammatory bowel disease (IBD), is still largely unknown. However, it is now clear that the abnormalities underlying pathogenesis of intestinal inflammation are not restricted to those mediated by classic immune cells but also involve nonimmune cells. In particular, advances in vascular biology have outlined a central and multifaceted pathogenic role for the microcirculation in the initiation and perpetuation of IBD. The microcirculation and its endothelial lining play a crucial role in mucosal immune homeostasis through tight regulation of the nature and magnitude of leukocyte migration from the intravascular to the interstitial space. Chronically inflamed IBD microvessels display significant alterations in microvascular physiology and function compared with vessels from healthy and uninvolved IBD intestine. The investigation into human IBD has demonstrated how endothelial activation present in chronically inflamed IBD microvessels results in a functional phenotype that also includes leakiness, chemokine and cytokine expression, procoagulant activity, and angiogenesis. This review contemplates the newly uncovered contribution of intestinal microcirculation to pathogenesis and maintenance of chronic intestinal inflammation. In particular, we assess the multiple roles of the microvascular endothelium in innate immunity, leukocyte recruitment, coagulation and perfusion, and immune-driven angiogenesis in IBD.

Multiple pathogenic roles of microvasculature in inflammatory bowel disease: a Jack of all trades

The etiology of Crohn's disease and ulcerative colitis, the two major forms of inflammatory bowel disease (IBD), is still largely unknown. However, it is now clear that the abnormalities underlying pathogenesis of intestinal inflammation are not restricted to those mediated by classic immune cells but also involve nonimmune cells. In particular, advances in vascular biology have outlined a central and multifaceted pathogenic role for the microcirculation in the initiation and perpetuation of IBD. The microcirculation and its endothelial lining play a crucial role in mucosal immune homeostasis through tight regulation of the nature and magnitude of leukocyte migration from the intravascular to the interstitial space. Chronically inflamed IBD microvessels display significant alterations in microvascular physiology and function compared with vessels from healthy and uninvolved IBD intestine. The investigation into human IBD has demonstrated how endothelial activation present in chronically inflamed IBD microvessels results in a functional phenotype that also includes leakiness, chemokine and cytokine expression, procoagulant activity, and angiogenesis. This review contemplates the newly uncovered contribution of intestinal microcirculation to pathogenesis and maintenance of chronic intestinal inflammation. In particular, we assess the multiple roles of the microvascular endothelium in innate immunity, leukocyte recruitment, coagulation and perfusion, and immune-driven angiogenesis in IBD.

Venous thromboembolism with inflammatory bowel disease

Venous thrombosis and thromboembolism appear to be increased in patients with inflammatory bowel disease. Although several acquired and genetic risk factors are known, about half that develop a thromboembolic event have no identifiable risk factor. Control of the inflammatory process is thought to be the key factor in risk reduction for thrombotic events. Prophylactic use of anticoagulants is not universally recommended, but possible use should be reviewed in an individual patient after evaluation of the risks, such as hemorrhage, compared to potential benefits. Particular consideration should be given if there has been a prior thrombotic event, if hospitalization will require surgery, or if an underlying coagulation disorder is present.

Tissue factor: a mediator of inflammatory cell recruitment, tissue injury, and thrombus formation in experimental colitis

There is growing evidence for an interplay between inflammatory and coagulation pathways in acute and chronic inflammatory diseases. However, it remains unclear whether components of the coagulation pathway, such as tissue factor (TF), contribute to intestinal inflammation, and whether targeting TF will blunt the inflammatory cell recruitment, tissue injury, and enhanced thrombus formation that occur in experimental colitis. Mice were fed 3% dextran sodium sulfate (DSS) to induce colonic inflammation, with some mice receiving a mouse TF-blocking antibody (muTF-Ab). The adhesion of leukocytes and platelets in colonic venules, light/dye-induced thrombus formation in cremaster muscle microvessels, as well as disease activity index, thrombin-antithrombin (TAT) complexes in plasma, and histopathologic changes in the colonic mucosa were monitored in untreated and muTF-Ab-treated colitic mice. In untreated mice, DSS elicited the recruitment of adherent leukocytes and platelets in colonic venules, caused gross and histologic injury, increased plasma TAT complexes, and enhanced thrombus formation in muscle arterioles. muTF-Ab prevented elevation in TAT complexes, reduced blood cell recruitment and tissue injury, and blunted thrombus formation in DSS colitic mice. These findings implicate TF in intestinal inflammation and support an interaction between inflammation and coagulation in experimental colitis.

Inflammation and coagulation in inflammatory bowel disease: The clot thickens

Inflammation and coagulation play crucial roles in the pathogenesis of multiple chronic inflammatory disorders. Growing evidence highlights a tight mutual network in which inflammation, coagulation, and fibrinolysis play closely related roles. Crohn's disease (CD) and ulcerative colitis (UC), the two major forms of inflammatory bowel disease (IBD), are chronic inflammatory conditions, characterized by a hypercoagulable state and prothrombotic conditions, and accompanied by abnormalities in coagulation. From a pathophysiological point of view, cells and molecules classically implicated in the physiological process of coagulation have now been shown to behave abnormally in IBD and possibly to also play an active role in disease pathogenesis and/or disease progression. This paper reviews studies performed on the coagulation profile and risk factors for thrombosis in IBD. In particular, an overview is provided of the epidemiology, clinical features, and etiology of thromboembolic complications in IBD. Furthermore, we review hemostatic abnormalities in IBD, as well as the cell types involved in such processes. Finally, we highlight the coagulation system as a dynamic participant in the multifaceted process of chronic intestinal inflammation. Overall, an overview is provided that the coagulation system represents an important, though previously underestimated, component of IBD pathogenesis, and may be a possible target for therapeutic intervention.

Systemic thromboembolism in inflammatory bowel disease: mechanisms and clinical applications

Systemic thromboembolism is an extraintestinal manifestation of inflammatory bowel disease (IBD), and an important cause of patient morbidity and mortality. The underlying basis for the hypercoagulable state in IBD is complex, and involves altered activity of all three components that govern hemostasis: platelets, fibrinolysis, and the coagulation cascade. Currently, there are no distinct guidelines for treating or preventing thromboembolic (TE) events in IBD patients compared with the general population. However, the prothrombotic state in IBD stems, at least in part, from several modifiable factors, such as hyperhomocysteinemia and an active inflammatory state. In this review we summarize the mechanisms that favor thrombosis in IBD, and the principles that need to be applied for the primary and secondary prevention of TE in this selected group of patients.

Activation of proteinase-activated receptor-1 inhibits neurally evoked chloride secretion in the mouse colon in vitro

The proteinase-activated thrombin receptor-1 (PAR-1) belongs to a unique family of G protein-coupled receptors activated by proteolytic cleavage. We studied the effect of PAR-1 activation in the regulation of ion transport in mouse colon in vitro. Expression of PAR-1 in mouse colon was assessed by RT-PCR and immunohistochemistry. To study the role of PAR-1 activation in chloride secretion, mouse colon was mounted in Ussing chambers. Changes in short-circuit current (Isc) were measured in tissues exposed to either thrombin, saline, the PAR-1-activating peptide TFLLR-NH2, or the inactive reverse peptide RLLFT-NH2, before electrical field stimulation (EFS). Experiments were repeated in the presence of either a PAR-1 antagonist or in PAR-1-deficient mice to assess receptor specificity. In addition, studies were conducted in the presence of chloride-free buffer or the muscarinic antagonist atropine to assess chloride dependency and the role of cholinergic neurons in the PAR-1-induced effect. PAR-1 mRNA was expressed in full-thickness specimens and mucosal scrapings of mouse colon. PAR-1 immunoreactivity was found on epithelial cells and on neurons in submucosal ganglia where it was colocalized with both VIP and neuropeptide Y. After PAR-1 activation by thrombin or TFLLR-NH2, secretory responses to EFS but not those to forskolin or carbachol were significantly reduced. The reduction in the response to EFS was not observed in the presence of the PAR-1 antagonist, in PAR-1-deficient mice, when chloride was excluded from the bathing medium, or when atropine was present. PAR-1 is expressed in submucosal ganglia in the mouse colon and its activation leads to a decrease in neurally evoked epithelial chloride secretion.

Association between enhanced soluble CD40 ligand and prothrombotic state in inflammatory bowel disease

BACKGROUND

Inflammatory bowel disease is associated with an increased incidence of thromboembolic complications. The aim of this study was to investigate the role of the soluble CD40 ligand (sCD40L), which displays prothrombotic properties, in patients with ulcerative colitis (UC) and Crohn's disease (CD) in comparison with inflammatory and healthy controls.

METHODS

Plasma levels of sCD40L, prothrombin fragment 1+2 (F1+2), thrombin-antithrombin (TAT) complex and soluble P-selectin were measured in 104 inflammatory bowel disease patients (54 ulcerative colitis and 50 Crohn's disease), in 18 cases with other causes of intestinal inflammation and in 80 healthy controls using commercially available enzyme-linked immunosorbent assays. Plasma levels of sCD40L were correlated with disease activity, type, localization and treatment as well as with the measured thrombophilic parameters.

RESULTS

CD patients had significantly higher sCD40L levels than both groups of controls (CD vs HC P < 0.001; CD vs non-IBD P < 0.05). UC patients had higher but not significantly different sCD40L levels compared with the controls. Both UC and CD patients with active disease had significantly higher sCD40L levels in comparison with patients with inactive disease. Plasma levels of sCD40L were correlated with platelet count (r = 0.27, P = 0.001). They also showed a correlation with prothrombin F1+2 (r = 0.16, r = 0.03) and TAT (r = 0.15, r = 0.04) as well as with P-selectin (r = 0.19, P = 0.01).

CONCLUSIONS

The increased sCD40L plasma levels may represent, at least in some degree, a molecular link between inflammatory bowel disease and the procoagualant state.

PAR1-dependent and independent increases in COX-2 and PGE2 in human colonic myofibroblasts stimulated by thrombin

Subepithelial myofibroblast-derived prostaglandin E(2) (PGE(2)) regulates epithelial chloride secretion in the intestine. Thrombin is elevated in inflammatory conditions of the bowel. Therefore, we sought to determine a role for thrombin in regulating PGE(2) synthesis by colonic myofibroblasts. Incubation of cultured CCD-18Co colonic myofibroblasts with thrombin, the proteinase-activated receptor 1 (PAR(1))-activating peptide (Cit-NH(2)), and peptides corresponding to 2 noncatalytic regions of thrombin (TP367 and TP508) for 18 h increased both cyclooxygenase (COX)-2 expression (immunocytochemistry) and PGE(2) synthesis (enzyme immunoassay). Inhibition of thrombin by D-Phe-Pro-Arg-chloromethylketone (PPACK) did not significantly reduce PGE(2) synthesis, which remained elevated compared with control. We also investigated the basic fibroblast growth factor (bFGF) dependence of thrombin-induced PGE(2) elevations. Recombinant human bFGF concentration dependently increased PGE(2) synthesis, and a bFGF neutralizing antibody inhibited PGE(2) synthesis induced by TP367 and TP508 (approximately 40%) and by thrombin (approximately 20%) (but not Cit-NH(2)). Thrombin, therefore, upregulates COX-2-derived PGE(2) synthesis by both catalytic cleavage of PAR(1) and bFGF-dependent noncatalytic activity. This presents a novel mechanism by which intestinal myofibroblasts might regulate epithelial chloride secretion.

Prevalence of factor V G1691A (Leiden), prothrombin G20210A, and methylene tetrahydrofolate reductase C677T thrombophilic mutations in children with inflammatory bowel disease

BACKGROUND

Patients with inflammatory bowel disease (IBD) have an increased incidence of thromboembolic events. This risk may be caused by an increased frequency of thrombophilic mutations such as factor V Leiden G1691A (FVL), prothrombin G20210A (PT), or methylene tetrahydrofolate reductase C667T (MTHFR). Prevalence rates of heterozygous mutations in FVL, PT, and MTHFR are reported for whites (1.8%, 1.3%, 26.6%, respectively), blacks (0.8%, 0.3%, and 12.4%, respectively), and Hispanics (1.2%, 2.4%, and 41.5%, respectively). We sought to determine the prevalence of these thrombophilic mutations in a large cohort of children with IBD.

METHODS

Children aged 21 years or younger with IBD were genotyped for FVL, PT, and MTHFR mutations by polymerase chain reaction amplification and restriction enzyme digestion. Prevalence rates were compared with established rates in the respective populations.

RESULTS

Of 92 patients enrolled, 89 (62 with Crohn disease, 24 with ulcerative colitis, and 3 with indeterminate colitis) had genotype results available. The mean age was 13.3 +/- 4.2 years (range, 2-21 years). Statistical analysis was performed on 89 FVL, PT, and MTHFR allele pairs. Polymerase chain reaction genotyping identified 5 patients with heterozygous FVL mutations, 3 patients heterozygous for the PT mutation, and 36 patients heterozygous and 4 patients homozygous for the MTHFR mutation. The thrombophilic allele mutation frequencies in our sample were not significantly different from predicted weighted average values: FVL, 2.8% versus 1.5%; PT, 1.7% versus 1.1%; and MTHFR, 24.7% versus 24.4%. In 24 patients with a family history of thrombosis, 1 was heterozygous for FVL and for MTHFR, 1 was heterozygous for FVL and homozygous for MTHFR, 2 were heterozygous for PT, and 9 were heterozygous MTHFR. There was no significant correlation between family history of thrombosis and presence of a thrombophilic mutation. The four patients with homozygous mutations for MTHFR, two of whom also were heterozygous for FVL, did not have either a personal history of thrombosis or a family history of thrombotic events. Two patients had thrombotic events without mutations in these genotypes: one had protein S deficiency and the other had no identifiable cause.

CONCLUSIONS

The presence of genetic mutations that predispose to hypercoagulable states does not appear to correlate with the prevalence of IBD or to thromboembolic events in patients with IBD. There was no statistical difference between the proportions of the mutated allele frequency in our study patients and the general population.

Activation of proteinase-activated receptor 1 stimulates epithelial chloride secretion through a unique MAP kinase- and cyclo-oxygenase-dependent pathway

Proteinase-activated receptor 1 (PAR-1) is activated by thrombin and induces chloride secretion by intestinal epithelial cells. To elucidate further the mechanisms whereby PAR-1 stimulates secretion, monolayers of SCBN intestinal epithelial cells were studied in modified Ussing chambers. Short circuit current responses were determined after basolateral application of thrombin and the PAR-1-activating peptide, Ala-parafluoro-Phe-Arg-cyclohexyl-Ala-Citrulline-Tyr (Cit-NH2) in the presence or absence of a variety of signal transduction and cyclo-oxygenase (COX) pathway inhibitors. Increased kinase activity was monitored by immunoprecipitation and Western blot analysis of target phosphoproteins. The PAR-1-induced chloride secretory response was significantly attenuated by inhibitors of the EGF receptor tyrosine kinase, Src-kinase, MEK1/2, as well as by inhibitors of cytosolic phospholipase (cPL) A2, COX-1 and COX-2. PAR-1-induced activation of cPLA2, as shown by Western blot of phosphoserine residues, was blocked in cells treated with the MEK inhibitor U0126, indicating that the MEK-ERK1/2 MAP kinase pathway mediated PAR-1-induced cPLA2 phosphorylation. Our data show that PAR-1-induced chloride secretion in SCBN cells involves Src, EGF receptor trans-activation, activation of a MAPK pathway, phosphorylation of cPLA2, COX activity, but not PGF2alpha or PGE2. These findings may be of clinical importance in inflammatory diseases of the intestine where secretory dysfunction is evident and thrombin levels are elevated.

Coagulation factor XIII and markers of thrombin generation and fibrinolysis in patients with inflammatory bowel disease

OBJECTIVE

To relate factor XIII levels and other prothrombotic markers to inflammatory bowel disease and investigate the frequency of valine34leucine and its effect on factor XIII cross-linking activity in patients with inflammatory bowel disease.

DESIGN

Fifty patients with active inflammatory bowel disease but no venous thromboembolism (32 with ulcerative colitis, 18 with Crohn's disease), 50 patients with inactive inflammatory bowel disease but no venous thromboembolism (32 with ulcerative colitis, 18 with Crohn's disease), two age- and gender-matched healthy control groups of 100 subjects each were recruited. To further explore the relationship between valine34leucine and inflammatory bowel disease, 21 patients with the disease (13 with ulcerative colitis and eight with Crohn's disease) and venous thromoembolism (male to female ratio = 7 : 14, median age 59.5 years (range, 19-80 years)) were recruited. Two hundred and fifteen control subjects (M : F = 121 : 94, median age 62 years (28-74 years)), with venous thromboembolism (119 with deep venous thrombosis, and 96 with pulmonary embolism) were drawn from the same geographical area as the patients.

METHODS

Factor XIII A, B-subunit antigen and A2B2 tetramer levels were measured using an in-house sandwich enzyme-linked immunoassay method.

RESULTS

Factor XIII A2B2 tetramer and the A-subunit were significantly decreased in patients with active inflammatory bowel disease compared with controls (59% vs 95%, P < 0.0001 and 75% vs 102%, P < 0.0001, respectively), but not between the inactive inflammatory bowel disease group and controls. The D-dimer and prothrombin 1+2 fragment levels in patients with active inflammatory bowel disease were raised compared with controls (178 (152) vs 109 (84), P = 0.0007 and 82 (43) vs 55 (28), P = 0.0001, respectively). The factor XIII B-subunit and factor XIII cross-linking activity were not significantly different between patients with active or inactive inflammatory bowel disease and controls. There was no significant difference in genotype distribution in inflammatory bowel disease patients with or without venous thromboembolism and respective control subjects. Levels of tissue plasminogen activator antigen were significantly increased in patients with active inflammatory bowel disease when compared to inactive inflammatory bowel disease and controls (8.9 (3.7) vs 6.7 (3.4) vs 6.9 (3.4), P < 0.001).

CONCLUSIONS

Active inflammatory bowel disease is associated with activation of coagulation. Factor XIII A and A2B2 tetramer levels were markedly decreased in active inflammatory bowel disease. Variations in the level of factor XIII in patients with inflammatory bowel disease could be multifactorial and in part may result from the increased formation of microthrombi and accelerated turnover of the factor XIII. We found no evidence of association of factor XIII valine34leucine polymorphism and inflammatory bowel disease.

Increased levels of lipoprotein (a) in Crohn's disease: a relation to thrombosis?

OBJECTIVE

Lipoprotein (a) is recognized as a risk factor for arterial and venous thrombosis, a property that might be related to its structural similarity to plasminogen. Since patients with inflammatory bowel disease frequently suffer from thromboembolic events, we studied the role of lipoprotein (a) in conjunction with lipids and apolipoproteins in Greek patients with ulcerative colitis and Crohn's disease.

METHODS

Lipoprotein (a), total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, apolipoprotein A-1 and apolipoprotein B-100 were determined in sera from 129 consecutive fasting Greek patients with inflammatory bowel disease (66 with ulcerative colitis and 63 with Crohn's disease) and from 66 matched healthy controls.

RESULTS

In Crohn's disease patients, the mean serum lipoprotein (a) level was significantly higher than in control patients (41.2 mg/dl vs 22.9 mg/dl; P = 0.005). Mean apolipoprotein A-1 and apolipoprotein B-100 levels were significantly lower in Crohn's disease patients than in the controls. In ulcerative colitis patients the mean levels of lipoprotein (a) and apolipoprotein A-1 were not significantly different to the controls, but the levels of apolipoprotein B-100 were significantly lower. Raised levels of lipoprotein (a) of > 30 mg/dl were found in 29 Crohn's disease patients (46%), 15 ulcerative colitis patients (23%) and 11 control patients (17%). Patients with active Crohn's disease had significantly higher mean lipoprotein (a) and lower apolipoprotein A-1 than patients with non-active disease.

CONCLUSIONS

Our results suggest that Crohn's disease patients have different lipoprotein (a) and apolipoprotein patterns compared to ulcerative colitis patients and healthy controls. These changes in Crohn's disease patients may possibly expose them to a higher risk of thrombosis.

Predictive value of inflammatory and coagulation parameters in the course of severe ulcerative colitis

Alterations in markers of coagulation have been found in patients with inflammatory bowel disease. Our aim was to study the predictive value of coagulation and inflammatory parameters in the course of severe ulcerative colitis. Twenty-seven patients were included. The disease course was followed for one year. Sensitivity, specificity, negative predictive value, positive predictive value, and likelihood ratio, as well as the clinical predictive value of laboratory variables were calculated. Inflammatory variables, such as ESR, CRP, and leukocyte and platelet count showed poor diagnostic accuracy. Several coagulation parameters, such as fibrinogen and fibrin(ogen) degradation products, were increased in patients with active ulcerative colitis, whereas coagulation factor XIII was decreased. No significant relationship between clinical course and coagulation parameters was demonstrated, though both inflammatory and coagulation parameters were useful in the assessment of disease activity in patients with active ulcerative colitis.

Hemostatic imbalance in active and quiescent ulcerative colitis

OBJECTIVE

In healthy conditions, factors inducing or inhibiting coagulation and factors inducing or inhibiting fibrinolysis are in balance. In ulcerative colitis, hypercoagulation is presumed, which may explain part of the clinical features of this disease. Therapy strategies affecting hemostasis may improve the course of ulcerative colitis. This study was conducted to evaluate the balance of coagulation and fibrinolysis in the course of treatment of active ulcerative colitis.

METHODS

Patients with active ulcerative colitis were studied by serial determination of markers of the coagulation cascade (thrombin-antithrombin complexes and fibrin degradation products [FbDP]) and the fibrinolytic cascade (fibrinogen degradation products [FgDP]). Parameters of inflammation were also measured (C-reactive protein [CRP], erythrocyte sedimentation rate [ESR], albumin, platelet count, and fibrinogen). Disease activity was assessed by endoscopic and histopathological scores. Follow-up measurement was performed in the course of treatment at the third or fourth month after baseline. Measurements were compared with healthy controls.

RESULTS

Thirty-three patients and 22 healthy controls were included. During active ulcerative colitis, inflammatory parameters (CRP, ESR, platelet count) and hemostatic parameters (thrombin-antithrombin complexes, fibrinogen, FgDP, and FbDP) were elevated in comparison with healthy controls. Albumin was decreased and antithrombin-III remained unchanged. During treatment, disease activity decreased significantly endoscopically and histopathologically (p < 0.001). CRP, ESR, platelet count, and fibrinogen also decreased significantly. The hemostatic balance, expressed as the ratio between the plasmin-dependent generation of FgDP and coagulation-dependent generation of FbDP, increased from 0.69 to 1.12 during treatment, mainly because of a decrease of FbDP. In healthy controls, this ratio was

CONCLUSIONS

The coagulation and fibrinolytic cascades were activated in active ulcerative colitis, with a hemostatic imbalance in favor of coagulation. This hypercoagulability persisted in 20% (7/33) of patients with ulcerative colitis in remission. The decrease of FbDP and the increase in the FgDP/FbDP ratio during reconvalescence of ulcerative colitis showed that the coagulation cascade was more activated than the fibrinolytic cascade in active disease.

Interaction of the protein C/protein S anticoagulant system, the endothelium and pregnancy

Normal pregnancy is associated with significant changes in haemostasis, lipid metabolism and endothelial function. This suggests that maternal adaptation in these systems is required for successful pregnancy outcome. A number of acquired and heritable prothrombotic abnormalities are associated with complications in pregnancy. A common feature of these abnormalities is their ability to alter endothelial function or the protein C/protein S system and increase thrombin generation. In this review the normal function of the endothelium and the protein C/protein S system is detailed. The changes which characterize normal and complicated pregnancies are outlined and the evidence for the impact of heritable and acquired disorders of the protein C/protein S system on pre-eclampsia and fetal loss are discussed.

Unfractioned heparin in the therapy of patients with highly active inflammatory bowel disease

OBJECTIVE

Unfractioned heparin reportedly improves severe ulcerative colitis and Crohn's disease, but most of the few observations made have been published as abstracts. This prospective study evaluated whether heparin results in improvement of disease activity in patients with highly active, refractory ulcerative colitis or Crohn's disease.

METHODS

Thirteen patients with ulcerative colitis and four patients with Crohn's disease received continuous intravenous heparin, aiming at a partial thromboplastin time of about 60 s for 2 wk. The following 6 wk, patients injected 12,500 units of heparin twice daily. All patients received sulphasalzine (1 g t.i.d.). Clinical and laboratory data were assessed weekly during the first month of treatment and every other week thereafter.

RESULTS

A significant decline of clinical activity (p = 0.0059), C-reactive protein (p = 0.0119), and erythrocyte sedimentation rate (p = 0.0096) was observed in the ulcerative colitis patients. In Crohn's disease clinical activity and laboratory values remained unchanged. Seven patients with ulcerative colitis but none of the Crohn's disease patients achieved complete remission after an average of 4 wk. In ulcerative colitis the histology (p = 0.0431) but not the endoscopic score (p = 0.1088) improved significantly. In one patient with ulcerative colitis, massive colonic bleeding was observed on day 11 of the study.

CONCLUSIONS

These data are further evidence of a beneficial effect of unfractioned heparin in the therapy of patients with highly active ulcerative colitis. Because of possible serious bleeding, intravenous heparin should be administered in hospitalized patients only.