Lipid ratios representing SCD1, FADS1, and FADS2 activities as candidate biomarkers of early growth and adiposity.

BACKGROUND: Altered lipid metabolism in early life has been associated with subsequent weight gain and predicting this could aid in obesity prevention and risk management. Here, a lipidomic approach was used to identify circulating markers for future obesity risk in translational murine models and validate in a human infant cohort. METHODS: Lipidomics was performed on the plasma of APOE*3 Leiden, Ldlr-/-.Leiden, and the wild-type C57BL/6J mice to capture candidate biomarkers predicting subsequent obesity parameters after exposure to high-fat diet. The identified candidate biomarkers were mapped onto corresponding lipid metabolism pathways and were investigated in the Cambridge Baby Growth Study. Infants' growth and adiposity were measured at 0-24 months. Capillary dried blood spots were sampled at 3 months for lipid profiling analysis. FINDINGS: From the mouse models, cholesteryl esters were correlated with subsequent weight gain and other obesity parameters after HFD period (Spearman's r≥0.5, FDR p values <0.05) among APOE*3 Leiden and Ldlr-/-.Leiden mice, but not among the wild-type C57BL/6J. Pathway analysis showed that those identified cholesteryl esters were educts or products of desaturases activities: stearoyl-CoA desaturase-1 (SCD1) and fatty acid desaturase (FADS) 1 and 2. In the human cohort, lipid ratios affected by SCD1 at 3 months was inversely associated with 3-12 months weight gain (B±SE=-0.31±0.14, p=0.027), but positively with 12-24 months weight and adiposity gains (0.17±0.07, p=0.02 and 0.17±0.07, 0.53±0.26, p=0.04, respectively). Lipid ratios affected by SCD1 and FADS2 were inversely associated with adiposity gain but positively with height gain between 3-12 months. INTERPRETATION: From murine models to human setting, the ratios of circulating lipid species indicating key desaturase activities in lipid metabolism were associated with subsequent body size increase, providing a potential tool to predict early life weight gain.

Intervention with a caspase-1 inhibitor reduces obesity-associated hyperinsulinemia, non-alcoholic steatohepatitis and hepatic fibrosis in LDLR-/-.Leiden mice.

BACKGROUND/OBJECTIVES: Non-alcoholic steatohepatitis (NASH) is a serious liver condition, closely associated with obesity and insulin resistance. Recent studies have suggested an important role for inflammasome/caspase-1 in the development of NASH, but the potential therapeutic value of caspase-1 inhibition remains unclear. Therefore, we aimed to investigate the effects of caspase-1 inhibition in the ongoing disease process, to mimic the clinical setting. SUBJECTS/METHODS: To investigate effects of caspase-1 inhibition under therapeutic conditions, male LDLR-/-.Leiden mice were fed a high-fat diet (HFD) for 9 weeks to induce a pre-diabetic state before start of treatment. Mice were then continued on HFD for another 12 weeks, without (HFD) or with (HFD-YVAD) treatment with the caspase-1 inhibitor Ac-YVAD-cmk (40 mg kg(-1) per day). RESULTS: Nine weeks of HFD feeding resulted in an obese phenotype, with obesity-associated hypertriglyceridemia, hypercholesterolemia, hyperglycemia and hyperinsulinemia. Treatment with Ac-YVAD-cmk did not affect further body weight gain or dyslipidemia, but did attenuate further progression of insulin resistance. Histopathological analysis of livers clearly demonstrated prevention of NASH development in HFD-YVAD mice: livers were less steatotic and neutrophil infiltration was strongly reduced. In addition, caspase-1 inhibition had a profound effect on hepatic fibrosis, as assessed by histological quantification of collagen staining and gene expression analysis of fibrosis-associated genes Col1a1, Acta2 and Tnfa. CONCLUSIONS: Intervention with a caspase-1 inhibitor attenuated the development of NASH, liver fibrosis and insulin resistance. Our data support the importance of inflammasome/caspase-1 in the development of NASH and demonstrate that therapeutic intervention in the already ongoing disease process is feasible.

Surgical removal of inflamed epididymal white adipose tissue attenuates the development of non-alcoholic steatohepatitis in obesity.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is strongly associated with abdominal obesity. Growing evidence suggests that inflammation in specific depots of white adipose tissue (WAT) has a key role in NAFLD progression, but experimental evidence for a causal role of WAT is lacking. METHODS: A time-course study in C57BL/6J mice was performed to establish which WAT depot is most susceptible to develop inflammation during high-fat diet (HFD)-induced obesity. Crown-like structures (CLS) were quantified in epididymal (eWAT), mesenteric (mWAT) and inguinal/subcutaneous (iWAT) WAT. The contribution of inflamed WAT to NAFLD progression was investigated by surgical removal of a selected WAT depot and compared with sham surgery. Plasma markers were analyzed by enzyme-linked immunosorbent assay (cytokines/adipokines) and lipidomics (lipids). RESULTS: In eWAT, CLS were formed already after 12 weeks of HFD, which coincided with maximal adipocyte size and fat depot mass, and preceded establishment of non-alcoholic steatohepatitis (NASH). By contrast, the number of CLS were low in mWAT and iWAT. Removal of inflamed eWAT after 12 weeks (eWATx group), followed by another 12 weeks of HFD feeding, resulted in significantly reduced NASH in eWATx. Inflammatory cell aggregates (-40%; P<0.05) and inflammatory genes (e.g., TNFα, -37%; P<0.05) were attenuated in livers of eWATx mice, whereas steatosis was not affected. Concomitantly, plasma concentrations of circulating proinflammatory mediators, viz. leptin and specific saturated and monounsaturated fatty acids, were also reduced in the eWATx group. CONCLUSIONS: Intervention in NAFLD progression by removal of inflamed eWAT attenuates the development of NASH and reduces plasma levels of specific inflammatory mediators (cytokines and lipids). These data support the hypothesis that eWAT is causally involved in the pathogenesis of NASH.

Psychiatric disorders in Huntington's disease: a 2-year follow-up study.

OBJECTIVE: This study investigates the presence and course of formal psychiatric disorders according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) in 142 Huntington's disease (HD) mutation carriers in a two-year follow-up design. METHOD: Of the 142 mutation carriers, 106 (75%) participated in the second measurement of an ongoing cohort study on psychopathology in HD. Presence of psychiatric disorders was assessed using the Composite International Diagnostic Interview. RESULTS: Of the 91 patients without a formal psychiatric disorder at baseline, 14 (15%) had a psychiatric disorder after 2 years, mostly a major depressive disorder (MDD) (64%). The baseline characteristics of lower education, having no children, a lower level of global daily functioning, a lifetime psychiatric diagnosis, and the use of psychotropic medication were predictive of incident psychiatric disorders after 2 years. Of the 15 patients with a psychiatric diagnosis at baseline, eight (53%) no longer had a psychiatric disorder at follow-up. All seven patients (47%) with a persistent psychiatric disorder were female and their most prevalent diagnosis was generalized anxiety disorder. CONCLUSION: This cohort study confirms that psychiatric disorders, in particular MDD, frequently occur in patients with HD. Professionals working with HD patients should therefore be aware of the high risk of psychopathology in HD because early diagnosis and treatment of psychiatric disorders may improve the quality of life of patients and their caregivers.

Metabolic stress-induced inflammation plays a major role in the development of osteoarthritis in mice.

OBJECTIVE: Obesity is associated with systemic inflammation and is a risk factor for osteoarthritis (OA) development. We undertook this study to test the hypothesis that metabolic stress-induced inflammation, and not mechanical overload, is responsible for the development of high-fat diet-induced OA in mice. METHODS: Human C-reactive protein (CRP)-transgenic mice received a high-fat diet without or with 0.005% (weight/weight) rosuvastatin or 0.018% (w/w) rosiglitazone, 2 different drugs with antiinflammatory properties. Mice fed chow were included as controls. After 42 weeks, mice were killed and histologic OA grading of the knees was performed. To monitor the overall inflammation state, systemic human CRP levels were determined. RESULTS: Male mice on a high-fat diet had significantly higher OA grades than mice on chow and showed no correlation between OA severity and body weight. In male mice, high-fat diet-induced OA was significantly inhibited by rosuvastatin or rosiglitazone to OA grades observed in control mice. Both treatments resulted in reduced human CRP levels. Furthermore, a positive correlation was found between the relative individual induction of human CRP evoked by a high-fat diet on day 3 and OA grade at end point. CONCLUSION: High-fat diet-induced OA in mice is due to low-grade inflammation and not to mechanical overload, since no relationship between body weight and OA grade was observed. Moreover, the OA process was inhibited to a great extent by treatment with 2 drugs with antiinflammatory properties. The inflammatory response to a metabolic high-fat challenge may predict individual susceptibility to developing OA later in life. The use of statins or peroxisome proliferator-activated receptor γ agonists (e.g., rosiglitazone) could be a strategy for interfering with the progression of OA.

Pathogenesis of postoperative adhesion formation.

BACKGROUND: Current views on the pathogenesis of adhesion formation are based on the 'classical concept of adhesion formation', namely that a reduction in peritoneal fibrinolytic activity following peritoneal trauma is of key importance in adhesion development. METHODS: A non-systematic literature search (1960-2010) was performed in PubMed to identify all original articles on the pathogenesis of adhesion formation. Information was sought on the role of the fibrinolytic, coagulatory and inflammatory systems in the disease process. RESULTS: One unifying concept emerged when assessing 50 years of studies in animals and humans on the pathogenesis of adhesion formation. Peritoneal damage inflicted by surgical trauma or other insults evokes an inflammatory response, thereby promoting procoagulatory and antifibrinolytic reactions, and a subsequent significant increase in fibrin formation. Importantly, peritoneal inflammatory status seems a crucial factor in determining the duration and extent of the imbalance between fibrin formation and fibrin dissolution, and therefore in the persistence of fibrin deposits, determining whether or not adhesions develop. CONCLUSION: Suppression of inflammation, manipulation of coagulation as well as direct augmentation of fibrinolytic activity may be promising antiadhesion treatment strategies.

Human visceral adipose tissue and the plasminogen activator inhibitor type 1.

OBJECTIVE: The objective of this study was to systematically evaluate the molecular basis of the association between visceral fat mass and plasma plasminogen activator inhibitor-1 (PAI-1) levels in man. DESIGN: A comprehensive approach comprising observational, in vitro, and human intervention studies. MEASUREMENTS AND RESULTS: We confirmed an exclusive relationship between visceral fat and plasma PAI-1 levels (r=0.79, P<0.001) and corroborated preferential PAI-1 release from adipose tissue explants. Yet, messenger RNA analysis and in vivo measurement of PAI-1 release from visceral fat (AV-differences over the omentum) not only excluded visceral adipose tissue as a relevant source of circulating PAI-1, but also excluded visceral fat as a significant source of proinflammatory mediators such as tumor necrosis factor-alpha, IL-1 or transforming growth factor-beta that could induce PAI-1 expression in tissues other than visceral fat. Short-term interventions with acipimox and growth hormone (GH) as well as statistical evaluation excluded free fatty acids and GH as metabolic links. Further analysis of the metabolic data in a stepwise regression model indicated that plasma PAI-1 levels and visceral fat rather are co-correlates that both relate to impaired lipid handling. CONCLUSION: Our PAI-1 studies show that visceral fat mass and plasma PAI-1 levels are co-correlated rather than causatively related, with lipid load as common denominator.

Fenofibrate reduces atherogenesis in ApoE*3Leiden mice: evidence for multiple antiatherogenic effects besides lowering plasma cholesterol.

OBJECTIVE: To demonstrate, quantify, and mechanistically dissect antiatherosclerotic effects of fenofibrate besides lowering plasma cholesterol per se. METHODS AND RESULTS: ApoE*3Leiden transgenic mice received either a high-cholesterol diet (HC) or HC containing fenofibrate (HC+FF) resulting in 52% plasma cholesterol-lowering. In a separate low-cholesterol diet (LC) control group, plasma cholesterol was adjusted to the level achieved in the HC+FF group. Low plasma cholesterol alone (assessed in LC) resulted in reduced atherosclerosis (lesion area, number and severity) and moderately decreased plasma serum amyloid-A (SAA) concentrations. Compared with LC, fenofibrate additively reduced lesion area, number and severity, and the total aortic plaque load. This additional effect in HC+FF was paralleled by an extra reduction of aortic inflammation (macrophage content; monocyte adhesion; intercellular adhesion molecule-1 [ICAM-1], soluble vascular cell adhesion molecule-1, granulocyte-macrophage colony-stimulating factor (GM-CSF), MCP-1, and NF-kappaB expression), systemic inflammation (plasma SAA and fibrinogen levels), and by an upregulation of plasma apoE levels. Also, enhanced expression of ABC-A1 and SR-B1 in aortic macrophages may contribute to the antiatherosclerotic effect of fenofibrate by promoting cholesterol efflux. CONCLUSIONS: Fenofibrate reduces atherosclerosis more than can be explained by lowering total plasma cholesterol per se. Impaired recruitment of monocytes/macrophages, reduced vascular and systemic inflammation, and stimulation of cholesterol efflux may all contribute to these beneficial effect of fenofibrate.

HMG-CoA reductase inhibitors: effects on chronic subacute inflammation and onset of atherosclerosis induced by dietary cholesterol.

Besides classical risk factors such as hypercholesterolemia and hypertension, chronic subacute inflammation has recently been recognized as an important force driving the development of atherosclerosis, the most common underlying cause of myocardial infarction and stroke. There is compelling evidence that a disturbance of cholesterol homeostasis contributes to the development of a chronic inflammatory state and that inhibitors of HMG-CoA reductase (statins) may dampen inappropriate inflammatory responses. We review the evidence and suggest mechanisms by which dietary cholesterol can induce an atherogenic inflammatory response in liver and vessel wall, with particular emphasis on the time course of this inflammatory response during atherogenesis and the interplay between these tissues. We discuss how statins interfere in this process, and whether they may reduce chronic subacute inflammation via a) their cholesterol-lowering effect, and/or b) their cholesterol-independent (pleiotropic) vasculoprotective activities. Recent studies performed in (humanized) animal models allow us to distinguish the lipid-lowering-dependent from the lipid-lowering-independent functions of statins. Using these data, we discuss the degree to which the lipid-lowering-dependent and lipid-lowering-independent effects of statins contribute to a reduction of inflammation, allowing estimation of the relevance of pleiotropic statin effects for the human situation.

Low-grade inflammation may play a role in the etiology of the metabolic syndrome in patients with coronary heart disease: the HIFMECH study.

Risk of coronary heart disease has been related to insulin resistance, but the mechanism for this is incompletely understood. Variables attributed to insulin resistance are associated with low-grade inflammation. A case-control study was performed of 469 male myocardial infarction (MI) survivors aged < 60 years and 575 control subjects recruited from centers in northern and southern Europe. Principal factor analysis was used to explore correlations between insulin resistance and inflammatory variables. Three factors resulted: (a) "Metabolic Syndrome" (insulin/proinsulin/ triglyceride/body mass index [BMI]); (b) "Inflammation" (fibrinogen/C-reactive protein [CRP]/interleukin-6 [IL-6]); and (c) "Blood Pressure" (systolic and diastolic blood pressure). The "Metabolic Syndrome" factor was related to the "Inflammation" factor (largely independently of obesity), the "Blood Pressure" factor, smoking, and south location (all P < or = .0002). There were significant relationships between all 3 factors and case status (P < or = .0002). Markers of low-grade inflammation are strongly related to metabolic syndrome variables independently of obesity. This raises the possibility that links between insulin resistance and cardiovascular disease could, in part, represent common consequences of low-grade inflammation.

Time course of peritoneal tissue plasminogen activator after experimental colonic surgery: effect of hyaluronan-based antiadhesive agents and bacterial peritonitis.

BACKGROUND: This study assessed the peritoneal fibrinolytic response during the first week after colonic surgery in rats with and without bacterial peritonitis, and possible modulation of the response by two hyaluronan-based antiadhesive agents. METHODS: A colonic anastomosis was constructed in 90 male Wistar rats. Peritonitis was induced in another 108 rats and a colonic anastomosis was constructed after 24 h. Rats in both groups were randomized into an untreated group or one of two groups treated with hyaluronan-based agents. One-third of each group was killed at each of days 1, 3 and 7 after operation, and tissue plasminogen activator (tPA) antigen and activity were measured in peritoneal biopsies. RESULTS: One day after colonic surgery in normal rats, tPA antigen concentration was significantly (P < 0.005) increased, whereas tPA activity levels were normal. By day 3 after operation tPA antigen had returned to baseline values while tPA activity was significantly increased (P < 0.05). One day after inducing peritonitis tPA antigen was significantly increased (P < 0.001), while tPA activity was significantly reduced (P < 0.05). Three and seven days after colonic surgery in rats with peritonitis tPA activity was increased (P < 0.001) while tPA antigen had returned to baseline values. Neither of the hyaluronan-based agents affected peritoneal tPA antigen levels or activity after colonic surgery. CONCLUSION: Both abdominal surgery and infection caused an early increase in peritoneal tPA antigen levels, followed by an increase in tPA activity. Peritonitis severely depressed early tPA activity. Application of hyaluronan-based agents did not affect the peritoneal fibrinolytic response to surgery and/or infection.

Adenovirus-mediated transfer of the 39 kD receptor-associated protein increases fibrinolytic capacity.

BACKGROUND: The mesothelium has an important role in maintaining an adequate fibrinolytic capacity in the peritoneal cavity and thus in preventing the formation of fibrinous peritoneal adhesions by secreting the fibrinolytic enzyme tissue-type plasminogen activator (t-PA). The fibrinolytic activity of human mesothelial cells (HMCs) is counteracted by rapid uptake of t-PA via the low-density lipoprotein receptor-related protein (LRP). The 39 kD receptor-associated protein (RAP) is an inhibitor of binding of t-PA to LRP, but RAP itself is also rapidly degraded via LRP. METHODS: Adenovirus-mediated RAP gene transfer technology was used to evaluate the effect of prolonged overexpression of RAP on t-PA accumulation in conditioned medium of HMCs under basal and inflammatory conditions. RESULTS: Infection of HMCs with a recombinant adenovirus carrying the RAP cDNA resulted within one day in t-PA levels that were maximally twofold to threefold increased as compared with noninfected or adenovirus-beta-galactosidase-infected cells. Whereas upon prolonged incubation, t-PA levels in the conditioned medium of uninfected cells leveled off because of rapid uptake and degradation via LRP, t-PA concentrations in the medium of adenovirus-RAP-infected cells continued to increase, reaching fivefold control levels after 72 hours. The increased t-PA accumulation persisted for seven days and then slowly returned to control values over the next few weeks. In contrast, the production of a specific inhibitor of t-PA, plasminogen activator inhibitor-1 (PAI-1), was not affected by adenoviral RAP gene transfer. Northern blotting analysis showed that t-PA, PAI-1, and LRP mRNA concentrations were not changed after adenoviral infection, underlining that the elevated t-PA levels are the result of RAP-blocked uptake and degradation of t-PA rather than increased t-PA synthesis. RAP gene transfer also restored diminished fibrinolytic activity of cytokine-treated mesothelial cells. CONCLUSIONS: Adenovirus-mediated transfer of the RAP gene provides an efficient way of transiently increasing the fibrinolytic capacity of mesothelial cells.

Negative regulation of human fibrinogen gene expression by peroxisome proliferator-activated receptor alpha agonists via inhibition of CCAAT box/enhancer-binding protein beta.

Fibrinogen is a coagulation factor and an acute phase reactant up-regulated by inflammatory cytokines, such as interleukin 6 (IL-6). Elevated plasma fibrinogen levels are associated with coronary heart diseases. Fibrates are clinically used hypolipidemic drugs that act via the nuclear receptor peroxisome proliferator-activated receptor alpha (PPAR alpha). In addition, most fibrates also reduce plasma fibrinogen levels, but the molecular mechanism is unknown. In this study, we demonstrate that fibrates decrease basal and IL-6-stimulated expression of the human fibrinogen-beta gene in human primary hepatocytes and hepatoma HepG2 cells. Fibrates diminish basal and IL-6-induced fibrinogen-beta promoter activity, and this effect is enhanced in the presence of co-transfected PPAR alpha. Site-directed mutagenesis experiments demonstrate that PPAR alpha activators decrease human fibrinogen-beta promoter activity via the CCAAT box/enhancer-binding protein (C/EBP) response element. Co-transfection of the transcriptional intermediary factor glucocorticoid receptor-interacting protein 1/transcriptional intermediary factor 2 (GRIP1/TIF2) enhances fibrinogen-beta gene transcription and alleviates the repressive effect of PPAR alpha. Co-immunoprecipitation experiments demonstrate that PPAR alpha and GRIP1/TIF2 physically interact in vivo in human liver. These data demonstrate that PPAR alpha agonists repress human fibrinogen gene expression by interference with the C/EBP beta pathway through titration of the coactivator GRIP1/TIF2. We observed that the anti-inflammatory action of PPAR alpha is not restricted to fibrinogen but also applies to other acute phase genes containing a C/EBP response element; it also occurs under conditions in which the stimulating action of IL-6 is potentiated by dexamethasone. These findings identify a novel molecular mechanism of negative gene regulation by PPAR alpha and reveal the direct implication of PPAR alpha in the modulation of the inflammatory gene response in the liver.

Aberrant fibrin formation and cross-linking of fibrinogen Nieuwegein, a variant with a shortened Aalpha-chain, alters endothelial capillary tube formation.

A congenital dysfibrinogenemia, fibrinogen(Nieuwegein), was discovered in a young man without any thromboembolic complications or bleeding. A homozygous insertion of a single nucleotide (C) in codon Aalpha 453 (Pro) introduced a stop codon at position 454, which resulted in the deletion of the carboxyl-terminal segment Aalpha 454-610. The ensuing unpaired cysteine at Aalpha 442 generated fibrinogen-albumin complexes of different molecular weights. The molecular abnormalities of fibrinogen(Nieuwegein) led to a delayed clotting and a fibrin network with a low turbidity. Electron microscopy confirmed that thin fibrin bundles were organized in a fine network. The use of fibrinogen(Nieuwegein)-derived fibrin (fibrin(Nieuwegein)) in an in vitro angiogenesis model resulted in a strong reduction of tube formation. The ingrowth of human microvascular endothelial cells (hMVEC) was independent of alpha(v)beta(3), indicating that the reduced ingrowth is not due to the absence of the RGD-adhesion site at position Aalpha 572-574. Rather, the altered structure of fibrin(Nieuwegein) is the cause, since partial normalization of the fibrin network by lowering the pH during polymerization resulted in an increased tube formation. Whereas factor XIIIa further decreased the ingrowth of hMVEC in fibrin(Nieuwegein), tissue transglutaminase (TG), which is released in areas of vessel injury, did not. This is in line with the absence of the cross-linking site for TG in the alpha-chains of fibrinogen(Nieuwegein). In conclusion, this newly discovered congenital dysfibrinogenemia has a delayed clotting time and leads to the formation of an altered fibrin structure, which could not be cross-linked by TG and which is less supportive for ingrowth of endothelial cells.

Steroids and cytokines in endometrial angiogenesis.

Angiogenesis, the formation of new blood vessels from pre-existing ones, occurs physiologically in the endometrium and pathologically e.g. during tumour growth. Sex-steroid hormones affect angiogenesis in the endometrium during the menstrual cycle and might be implicated in cancer angiogenesis. Little information is presently available regarding the exact mechanisms by which these steroids exert their function on the process of both physiological and pathological angiogenesis. In this overview a survey is given of factors important for angiogenesis and of the effects of steroids on the expression of these factors. We have focused on endometrial angiogenesis, because the endometrium is unique in its cyclic growth pattern for which angiogenesis is indispensable. Stimulators and inhibitors of endometrial angiogenesis, that have been found (or suggested) to respond to ovarian steroids, are discussed These factors include vascular endothelial growth factor (VEGF), fibroblast growth factors (FGFs), tumour necrosis factor a (TNF-alpha), erythropoietin (Epo) and trombospondin-1 (TSP-1). Also, the influence of steroids on the expression of matrixdegrading proteases, in particular the plasminogen activator/plasmin system and matrixdegrading metalloproteinases (MMPs) are reviewed, because these proteases play an important role in the migration and invasion of endothelial cells during the process of angiogenesis. An insight into the effects of steroids on endometrial angiogenesis may be helpful to understand and anticipate the potential stimulatory and inhibitory effect of various steroids on angiogenesis in other tissues, in particular tumours.

Short-term effect of surgical trauma on rat peritoneal fibrinolytic activity and its role in adhesion formation.

BACKGROUND: Fibrin deposition, the primary step in the formation of post-surgical adhesions, is the result of a disbalance between the fibrin-forming and the fibrin-dissolving capacity of the peritoneum. Literature data suggest a transient reduction in local plasminogen activator activity after peritoneal trauma, which results in a reduction of fibrinolysis and permits deposited fibrin to become organized into fibrous, permanent adhesions. In the present study, the fibrinolytic parameters tissue-type plasminogen activator (tPA; antigen and activity) and plasminogen activator inhibitor type-1 (PAI-1; antigen and activity) were measured in peritoneal fluid, in peritoneal biopsies and in plasma to establish the time course of changes in fibrinolytic activity. DESIGN: A standardized peritoneal adhesion model in the rat. OUTCOME MEASURES: Analysis, over a 72-h period following surgical trauma. of the main fibrinolytic parameters in peritoneal lavage, in biopsies of damaged and undamaged peritoneum, and in plasma, and determination of fibrin and fibrin(ogen)-degradation products in peritoneal lavage fluid. RESULTS: At all time intervals, tPA antigen was found to be about six-fold increased in peritoneal lavage after surgical trauma. This significant rise in tPA antigen was accompanied by a large increase in its main inhibitor PAI-1, resulting in tPA activity levels similar to, or slightly higher than, those found in control animals. tPA activity was lowest at 4 h and increased thereafter. Also in biopsies from damaged peritoneum, tPA antigen was significantly increased. Tissue tPA activity was also lowest at 4 h, after which it increased, significantly so at 24 and 72 h. Similar, though smaller, changes were seen in the biopsies from undamaged areas of the peritoneal wall in operated rats. PAI-1 (antigen and activity) was not detected in peritoneal biopsies. Fibrin-related material (especially fibrin monomer/fibrinogen, an indicator of forming fibrin) in peritoneal fluid was slightly increased at 4 h, and abundantly present at 16 and 24 h, returning to control levels at 72 h. Fibrin degradation products were always present. From 2 h onward, adhesions were found. CONCLUSIONS: In contrast to the view that adhesions are formed as a result of a reduced fibrinolytic activity, our results demonstrate that tPA activity remained unchanged or slightly increased after surgical trauma, and point to increased fibrin formation rather than diminished fibrinolytic activity as the main cause of fibrin deposition after peritoneal trauma. Therapies directed at prevention of adhesion formation should therefore aim at avoiding massive fibrin production and at promoting fibrinolytic activity during the early period after trauma.

Use of fibrinolytic agents in the prevention of postoperative adhesion formation.

OBJECTIVE: To review the events leading to the formation of adhesions, to describe the development of fibrinolytic agents, to review more than a century of research on the use of fibrinolytic agents in adhesion prevention, and to look at future aspects of adhesion prevention. RESULTS: A better understanding of the pathogenesis of adhesion formation has resulted in the use of fibrinolytic agents in their prevention. Fibrinolytic agents promote fibrinolytic activity during the early period after peritoneal trauma during which an increased formation of fibrin is seen in combination with a deficiency of endogenous fibrinolytic activity. Initially, chemical attacks on fibrin (fibrolysin and hypertonic glucose), foreign digestive ferments (pepsin, trypsin, and papain), and stimulation of intraperitoneal leukocytosis (amniotic fluid) were used. Development of new thrombolytic agents was soon followed by experiments in animal adhesion models and clinical studies to examine their antiadhesion properties. Plasmin preparations (plasmin, actase, and fibrinolysin) and plasmin activators (streptokinase, urokinase, and tissue-type plasminogen activator) were found to be efficacious in preventing adhesion formation in the greater part of reviewed animal and clinical studies. CONCLUSION(S): From the current literature, it can be concluded that postoperative intraperitoneal administration of thrombolytic agents can significantly decrease adhesion formation. Given the large number of experimental studies in animals, future studies should focus on the clinical use of fibrinolytic agents in the prevention of postsurgical adhesion formation.

Oral, but not transdermal, administration of estrogens lowers tissue-type plasminogen activator levels in humans without affecting endothelial synthesis.

Oral estrogen administration decreases plasma levels of tissue-type plasminogen activator (tPA), which may be explained by a decrease in endothelial tPA synthesis, an increase in its hepatic clearance, or both. In the present study, we determined (1) differences between oral (ie, via the liver) ethinyl estradiol and transdermal (ie, systemic) 17beta-estradiol administration on plasma antigen levels of tPA and plasminogen activator inhibitor type-1 before and after 4 months of hormone administration and (2) effects on endothelial tPA synthesis, by measuring the local increase in plasma tPA during venous occlusion of the upper extremity. Thirty transsexual males (median age 32 years, range 20 to 44 years ) were randomly assigned to either oral ethinyl estradiol (n=15) or transdermal 17beta-estradiol (n=15); both treatments included the antiandrogen cyproterone acetate (CA). Ten males were treated with CA alone. Seventeen transsexual females (median age 27 years, range 18 to 37 years) were treated with intramuscular testosterone esters. Only oral ethinyl estradiol plus CA but neither transdermal 17beta-estradiol plus CA, nor oral CA, nor parenteral testosterone lowered plasma tPA and plasminogen activator inhibitor-1 (P<0.001 for both). tPA release during venous occlusion was not affected by oral ethinyl estradiol plus CA in males (P=0.52) or by parenteral testosterone in females (P=0.89). These data are consistent with a previous observation, in rodents, that the decrease in tPA after oral estrogen administration can be explained by an increase in hepatic tPA clearance, leaving endothelial tPA synthesis unchanged, and suggest that these mechanisms also explain the decrease in tPA in humans.