Induction of plasminogen activator inhibitor type 1 and type 1 collagen expression in rat cardiac microvascular endothelial cells by interleukin-1 and its dependence on oxygen-centered free radicals

The Roles of Fibrinolytic Factors in Bone Destruction Caused by Inflammation

Chronic inflammatory diseases, such as rheumatoid arthritis, spondyloarthritis, systemic lupus erythematosus, Crohn's disease, periodontitis, and carcinoma metastasis frequently result in bone destruction. Pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and IL-17 are known to influence bone loss by promoting the differentiation and activation of osteoclasts. Fibrinolytic factors, such as plasminogen (Plg), plasmin, urokinase-type plasminogen activator (uPA), its receptor (uPAR), tissue-type plasminogen activator (tPA), α2-antiplasmin (α2AP), and plasminogen activator inhibitor-1 (PAI-1) are expressed in osteoclasts and osteoblasts and are considered essential in maintaining bone homeostasis by regulating the functions of both osteoclasts and osteoblasts. Additionally, fibrinolytic factors are associated with the regulation of inflammation and the immune system. This review explores the roles of fibrinolytic factors in bone destruction caused by inflammation.

Role of SARS-CoV-2 -induced cytokines and growth factors in coagulopathy and thromboembolism

Severe COVID-19 patients frequently present thrombotic complications which commonly lead to multiorgan failure and increase the risk of death. Severe SARS-CoV-2 infection induces the cytokine storm and is often associated with coagulation dysfunction. D-dimer, a hallmark of venous thromboembolism (VTE), is observed at a higher level in the majority of hospitalized COVID-19 patients. The precise molecular mechanism of the disproportionate effect of SARS-CoV-2 infection on the coagulation system is largely undefined. SARS-CoV-2 -induced endotheliopathy and, induction of cytokines and growth factors (GFs) most likely play important roles in platelet activation, coagulopathy, and VTE. Generally, viral infections lead to systemic inflammation and induction of numerous cytokines and GFs and many of them are reported to be associated with increased VTE. Most importantly, platelets play key thromboinflammatory roles linking coagulation to immune mediators in a variety of infections including response to viral infection. Since the pathomechanism of coagulopathy and VTE in COVID-19 is largely undefined, herein we highlight the association of dysregulated inflammatory cytokines and GFs with thrombotic complications and coagulopathy in COVID-19.

Leonurine Ameliorates Oxidative Stress and Insufficient Angiogenesis by Regulating the PI3K/Akt-eNOS Signaling Pathway in H2O2-Induced HUVECs

Thrombus is considered to be the pathological source of morbidity and mortality of cardiovascular disease and thrombotic complications, while oxidative stress is regarded as an important factor in vascular endothelial injury and thrombus formation. Therefore, antioxidative stress and maintaining the normal function of vascular endothelial cells are greatly significant in regulating vascular tension and maintaining a nonthrombotic environment. Leonurine (LEO) is a unique alkaloid isolated from Leonurus japonicus Houtt (a traditional Chinese medicine (TCM)), which has shown a good effect on promoting blood circulation and removing blood stasis. In this study, we explored the protective effect and action mechanism of LEO on human umbilical vein endothelial cells (HUVECs) after damage by hydrogen peroxide (H₂O₂). The protective effects of LEO on H₂O₂-induced HUVECs were determined by measuring the cell viability, cell migration, tube formation, and oxidative biomarkers. The underlying mechanism of antioxidation of LEO was investigated by RT-qPCR and western blotting. Our results showed that LEO treatment promoted cell viability; remarkably downregulated the intracellular generation of reactive oxygen species (ROS), malondialdehyde (MDA) production, and lactate dehydrogenase (LDH); and upregulated the nitric oxide (NO) and superoxide dismutase (SOD) activity in H₂O₂-induced HUVECs. At the same time, LEO treatment significantly promoted the phosphorylation level of angiogenic protein PI3K, Akt, and eNOS and the expression level of survival factor Bcl2 and decreased the expression level of death factor Bax and caspase3. In conclusion, our findings suggested that LEO can ameliorate the oxidative stress damage and insufficient angiogenesis of HUVECs induced by H₂O₂ through activating the PI3K/Akt-eNOS signaling pathway.

Promising Therapy for Heart Failure in Patients with Severe COVID-19: Calming the Cytokine Storm

The coronavirus disease 19 (COVID-19) pandemic poses a serious global threat to human health and the economy. Based on accumulating evidence, its continuous progression involves not only pulmonary injury but also damage to the cardiovascular system due to intertwined pathophysiological risks. As a point of convergence in the pathophysiologic process between COVID-19 and heart failure (HF), cytokine storm induces the progression of COVID-19 in patients presenting pre-existing or new onset myocardial damage and even HF. Cytokine storm, as a trigger of the progression of HF in patients with COVID-19, has become a novel focus to explore therapies for target populations. In this review, we briefly introduce the basis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and illuminate the mechanism and links among COVID-19, cytokine storm, and HF. Furthermore, we discuss drugs and therapeutic targets for patients with COVID-19 and HF.

The role of miR-320 in glucose and lipid metabolism disorder-associated diseases

Glucose and lipids are important nutrients that provide the majority of energy for each organ to maintain homeostasis of the body. With the continuous improvement in living standards, the incidence of metabolic disorder-associated diseases, such as diabetes, hyperlipidemia, and atherosclerosis, is increasing worldwide. Among them, diabetes, which could be induced by both glucose and lipid metabolic disorders, is one of the five diseases with the highest incidence and mortality worldwide. However, the detailed molecular mechanisms underlying glucose and lipid metabolism disorders and target-organ damage are still not fully defined. MicroRNAs (miRNAs) are small, non-coding, single-stranded RNAs, which usually affect their target mRNAs in the cytoplasm by post-transcriptional regulation. Previously, we have found that miR-320 contributed to glucose and lipid metabolism via different signaling pathways. Most importantly, we identified that nuclear miR-320 mediated diabetes-induced cardiac dysfunction by activating the transcription of fatty acid metabolic genes to cause lipotoxicity in the heart. Here, we reviewed the roles of miR-320 in glucose and lipid metabolism and target-organ damage.

Low-dose hydralazine improves endotoxin-induced coagulopathy and multiple organ dysfunction via its anti-inflammatory and anti-oxidative/nitrosative properties

Coagulopathy is the major cause of organ injury as well as a strong predictor of mortality in septic patients. Systemic inflammatory response and redox imbalance are regarded as the major causes of sepsis-induced coagulopathy. There is growing evidence that a vasodilator hydralazine has beneficial effects on heart failure, hypertension, and ischemia/reperfusion injury via its antioxidant and anti-inflammatory properties. However, the effects of hydralazine on sepsis have not been examined. Therefore, we evaluated the effects of low-dose hydralazine on coagulopathy and multiple organ dysfunction in septic rats induced by endotoxin. Sepsis-induced coagulopathy was established by intravenous injection of rats with lipopolysaccharide (LPS). The changes of blood pressure, heart rate, blood glucose, hemostatic variables, prothrombin time, organ function indices, interleukin-6 (IL-6) concentration, and nitric oxide (NO) level were assessed during the experimental period. In addition, the aortas, lungs, livers, and kidneys were dissected to analyze superoxide levels and protein expressions. LPS induced (i) coagulopathy, multiple organ dysfunction, and circulatory failure successfully, and (ii) excessive superoxide, NO, and IL-6 production, accompanied by the overexpression of iNOS and Wnt5a in animals. Treatment of LPS-induced septic rats with low-dose hydralazine not only improved coagulopathy but also ameliorated multiple organ dysfunction. These could be due to attenuation of the overproduction of superoxide, NO, and IL-6, which were attributed to reduction of the overexpression of iNOS and Wnt5a. Thus, these findings indicate that low-dose hydralazine could be a potential therapy for sepsis-induced coagulopathy and multiple organ dysfunction via its anti-inflammatory and anti-oxidative/nitrosative properties.

Novel oral plasminogen activator inhibitor‑1 inhibitor TM5275 attenuates hepatic fibrosis under metabolic syndrome via suppression of activated hepatic stellate cells in rats

An orally bioavailable small molecule inhibitor of plasminogen activator inhibitor-1 (PAI-1) is currently being clinically assessed as a novel antithrombotic agent. Although PAI-1 is known to serve a key role in the pathogenesis of metabolic syndrome (MetS) including nonalcoholic steatohepatitis (NASH), the pharmacological action of an oral PAI-1 inhibitor against the development of MetS-related liver fibrosis remains unclear. The current study was designed to explicate the effect of TM5275, an oral PAI-1 inhibitor, on MetS-related hepatic fibrogenesis. The in vivo antifibrotic effect of orally administered TM5275 was investigated in two different rat MetS models. Fischer 344 rats received a choline-deficient L-amino-acid-defined diet for 12 weeks to induce steatohepatitis with development of severe hepatic fibrosis. Otsuka Long-Evans Tokushima Fatty rats, used to model congenital diabetes, underwent intraperitoneal injection of porcine serum for 6 weeks to induce hepatic fibrosis under diabetic conditions. In each experimental model, TM5275 markedly ameliorated the development of hepatic fibrosis and suppressed the proliferation of activated hepatic stellate cells (HSCs). Additionally, the hepatic production of tumor growth factor (TGF)-β1 and total collagen was suppressed. In vitro assays revealed that TGF-β1 stimulated the upregulation of Serpine1 mRNA expression, which was inhibited by TM5275 treatment in cultured HSC-T6 cells, a rat HSC cell line. Furthermore, TM5275 substantially attenuated the TGF-β1-stimulated proliferative and fibrogenic activity of HSCs by inhibiting AKT phosphorylation. Collectively, TM5275 demonstrated an antifibrotic effect on liver fibrosis in different rat MetS models, suppressing TGF-β1-induced HSC proliferation and collagen synthesis. Thus, PAI-1 inhibitors may serve as effective future therapeutic agents against NASH-based hepatic fibrosis.

E8002 Inhibits Peripheral Nerve Adhesion by Enhancing Fibrinolysis of l-Ascorbic Acid in a Rat Sciatic Nerve Model

Perineural adhesions leading to neuropathy are one of the most undesirable consequences of peripheral nerve surgery. However, there are currently no widely used compounds with anti-adhesive effects in the field of peripheral nerve surgery. E8002 is a novel, anti-adhesive, multi-layer membrane that contains L-ascorbic acid (AA). Here, we investigated the effect and mechanism of E8002 in a rat sciatic nerve adhesion model. A total of 21 rats were used. Six weeks after surgery, macroscopic adhesion scores were significantly lower in the E8002 group (adhesion procedure followed by nerve wrapping with E8002) compared to the E8002 AA(−) group (adhesion procedure followed by nerve wrapping with the E8002 membrane excluding AA) and adhesion group (adhesion procedure but no treatment). Correspondingly, a microscopic examination revealed prominent scar tissue in the E8002 AA(−) and adhesion groups. Furthermore, an in vitro study using human blood samples showed that AA enhanced tissue-type, plasminogen activator-mediated fibrinolysis. Altogether, these results suggest that E8002 may exert an anti-adhesive action via AA and the regulation of fibrinolysis.

Reactive Oxygen Species in Venous Thrombosis

Reactive oxygen species (ROS) have physiological roles as second messengers, but can also exert detrimental modifications on DNA, proteins and lipids if resulting from enhanced generation or reduced antioxidant defense (oxidative stress). Venous thrombus (DVT) formation and resolution are influenced by ROS through modulation of the coagulation, fibrinolysis, proteolysis and the complement system, as well as the regulation of effector cells such as platelets, endothelial cells, erythrocytes, neutrophils, mast cells, monocytes and fibroblasts. Many conditions that carry an elevated risk of venous thrombosis, such as the Antiphospholipid Syndrome, have alterations in their redox homeostasis. Dietary and pharmacological antioxidants can modulate several important processes involved in DVT formation, but their overall effect is unknown and there are no recommendations regarding their use. The development of novel antioxidant treatments that aim to abrogate the formation of DVT or promote its resolution will depend on the identification of targets that enable ROS modulation confined to their site of interest in order to prevent off-target effects on physiological redox mechanisms. Subgroups of patients with increased systemic oxidative stress might benefit from unspecific antioxidant treatment, but more clinical studies are needed to bring clarity to this issue.

The Role of Fibrinolytic Regulators in Vascular Dysfunction of Systemic Sclerosis

Systemic sclerosis (SSc) is a connective tissue disease of autoimmune origin characterized by vascular dysfunction and extensive fibrosis of the skin and visceral organs. Vascular dysfunction is caused by endothelial cell (EC) apoptosis, defective angiogenesis, defective vasculogenesis, endothelial-to-mesenchymal transition (EndoMT), and coagulation abnormalities, and exacerbates the disease. Fibrinolytic regulators, such as plasminogen (Plg), plasmin, α2-antiplasmin (α2AP), tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA) and its receptor (uPAR), plasminogen activator inhibitor 1 (PAI-1), and angiostatin, are considered to play an important role in the maintenance of endothelial homeostasis, and are associated with the endothelial dysfunction of SSc. This review considers the roles of fibrinolytic factors in vascular dysfunction of SSc.

Suppression of plasminogen activator inhibitor-1 (PAI-1) activity by crocin ameliorates lipopolysaccharide-induced thrombosis in rats

The imbalance between clot formation and fibrinolysis is mainly attributed to increased levels of plasminogen activator inhibitor type 1 (PAI-1), an inhibitor of fibrinolysis closely involved in inflammatory responses such as septic shock. This increase is mediated by many factors, including reactive oxygen species (ROS). The present study was designed to evaluate the prophylactic effect of crocin, a potent natural antioxidant, on PAI-1 in the rat model of endotoxic shock. Lipopolysaccharide-infused rats (500 μg/kg) showed significant changes in thrombosis-related haematological parameters such as decrease of platelet blood counts and increase (7 fold) of PAI-1 concentration in blood plasma. No effect on t-PA activity was observed. Crocin administration in two different doses (10 mg/kg and 100 mg/kg) 30 min prior to the injection of LPS, inhibited the reduction of platelet counts and ameliorated the concentration of PAI-1 in the liver and the brain. Moreover, crocin inhibited the deposition of fibrin in the renal glomeruli. No significant changes were recorded in the healthy groups of crocin (10 mg/kg and 100 mg/kg) compared to the control group. These data demonstrate the potential of crocin to prevent LPS-induced organ injury and suggest it is worthwhile to investigate the use of antioxidants for the treatment of septicemia.

Uric acid enhances alteplase-mediated thrombolysis as an antioxidant

Uric acid (UA) therapy may prevent early ischemic worsening after acute stroke in thrombolysis patients. The aim of this study was to examine the influence of UA on the thrombolytic efficacy of alteplase in human blood samples by measuring thrombolysis under flow conditions using a newly developed microchip-based flow-chamber assay. Human blood samples from healthy volunteers were exposed to UA, alteplase, or a combination of UA and alteplase. Whole blood and platelet-rich plasma were perfused over a collagen- and thromboplastin-coated microchip, and capillary occlusion was monitored with a video microscope and flow-pressure sensor. The area under the curve (extent of thrombogenesis or thrombolysis) at 30 minutes was 92% lower in the UA-alteplase-treated group compared with the alteplase-treated group. D-dimers were measured to evaluate these effects in human platelet-poor plasma samples. Although hydrogen peroxide significantly decreased the elevation of D-dimers by alteplase, UA significantly inhibited the effect of hydrogen peroxide. Meanwhile, rat models of thromboembolic cerebral ischemia were treated with either alteplase or UA-alteplase combination therapy. Compared with alteplase alone, the combination therapy reduced the infarct volume and inhibited haemorrhagic transformation. UA enhances alteplase-mediated thrombolysis, potentially by preventing oxidative stress, which inhibits fibrinolysis by alteplase in thrombi.

Inflammation - Cause or Consequence of Heart Failure or Both?

PURPOSE OF REVIEW

With the intention to summarize the currently available evidence on the pathophysiological relevance of inflammation in heart failure, this review addresses the question whether inflammation is a cause or consequence of heart failure, or both.

RECENT FINDINGS

This review discusses the diversity (sterile, para-inflammation, chronic inflammation) and sources of inflammation and gives an overview of how inflammation (local versus systemic) can trigger heart failure. On the other hand, the review is outlined how heart failure-associated wall stress and signals released by stressed, malfunctioning, or dead cells (DAMPs: e.g., mitochondrial DNA, ATP, S100A8, matricellular proteins) induce cardiac sterile inflammation and how heart failure provokes inflammation in various peripheral tissues in a direct (inflammatory) and indirect (hemodynamic) manner. The crosstalk between the heart and peripheral organs (bone marrow, spleen, gut, adipose tissue) is outlined and the importance of neurohormonal mechanisms including the renin angiotensin aldosteron system and the ß-adrenergic nervous system in inflammation and heart failure is discussed. Inflammation and heart failure are strongly interconnected and mutually reinforce each other. This indicates the difficulty to counteract inflammation and heart failure once this chronic vicious circle has started and points out the need to control the inflammatory process at an early stage avoiding chronic inflammation and heart failure. The diversity of inflammation further addresses the need for a tailored characterization of inflammation enabling differentiation of inflammation and subsequent target-specific strategies. It is expected that the characterization of the systemic and/or cardiac immune profile will be part of precision medicine in the future of cardiology.

Plasminogen Activator Inhibitor Type-1 as a Regulator of Fibrosis

Fibrosis is known as a frequent and irreversible pathological condition which is associated with organ failure. Tissue fibrosis is a central process in a variety of chronic progressive diseases such as diabetes, hypertension, and persistent inflammation. This state could contribute to chronic injury and the initiation of tissue repair. Fibrotic disorders represent abnormal wound healing with defective matrix turnover and clearance that lead to excessive accumulation of extracellular matrix components. A variety of identified growth factors, cytokines, and persistently activated myofibroblasts have critical roles in the pathogenesis of fibrosis. Irrespective of etiology, the transforming growth factor-β pathway is the major driver of fibrotic response. Plasminogen activator inhibitor-1 (PAI-1) is a crucial downstream target of this pathway. Transforming growth factor-β positively regulates PAI-1 gene expression via two main pathways including Smad-mediated canonical and non-canonical pathways. Overexpression of PAI-1 reduces extracellular matrix degradation via perturbing the plasminogen activation system. Indeed, elevated PAI-1 levels inhibit proteolytic activity of tissue plasminogen activator and urokinase plasminogen activator which could contribute to a variety of inflammatory elements in the injury site and to excessive matrix deposition. This review summarizes the current knowledge of critical pathways that regulate PAI-1 gene expression and suggests effective approaches for the treatment of fibrotic disease. J. Cell. Biochem. 119: 17-27, 2018. © 2017 Wiley Periodicals, Inc.

Association of serum uric acid level with mortality and morbidity of patients with acute ST-elevation myocardial infarction

Introduction: Investigating the clinical impact of serum uric acid (UA) and its lowering agents on the complications and mortality of acute ST-elevation myocardial infarction (STEMI) can open a new era in STEMI treatment. The aim of this study was to evaluate the effect of on admission serum UA level on the mortality and morbidity of patients admitted with STEMI.

Methods: A number of 608 patients with STEMI were enrolled in this study from December 21, 2012 until February 19, 2014. Patients were followed for 20 months. Male to female ratio was 2.53, and the mean age of patients was 62.6±13.4. The relationship between the level of UA and patients’ mortality and morbidity, left ventricular ejection fraction (LVEF), atrial and ventricular arrhythmia was analyzed.

Results: Patients with high serum UA level had higher Killip class after STEMI (P=0.001). Mean LVEF was measured to be 39.5±9.6 in normal UA group and 34.6±11.6 in high UA group (P=0.001). In comparison with normal UA group, high UA group had significantly higher cTnI (2.68±0.09 vs 4.09±0.42, respectively, P=0.001), increased blood pressure (P=0.009), and higher atrial fibrillation (AF) occurrence (P=0.03), but no association was seen between ventricular tachycardia and serum UA level. Short term and midterm mortality were not different in two groups (P=0.44 and 0.31, respectively).

Conclusion: In the current study, high serum UA level in patients with acute myocardial infarction (MI) was not associated with higher in-hospital or midterm mortality, but it was associated with lower LVEF, higher Killip class, elevated cTnI, creatinine, triglyceride, and higher AF.

Plasminogen activator inhibitor 1, fibroblast apoptosis resistance, and aging-related susceptibility to lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disorder with unknown cause and no effective treatment. The incidence of and mortality from IPF increase with age, suggesting that advanced age is a major risk factor for IPF. The mechanism underlying the increased susceptibility of the elderly to IPF, however, is unknown. In this study, we show for the first time that the protein level of plasminogen activator inhibitor 1 (PAI-1), a protease inhibitor which plays an essential role in the control of fibrinolysis, was significantly increased with age in mouse lung homogenate and lung fibroblasts. Upon bleomycin challenge, old mice experienced augmented PAI-1 induction and lung fibrosis as compared to young mice. Most interestingly, we show that fewer (myo)fibroblasts underwent apoptosis and more (myo)fibroblasts with increased level of PAI-1 accumulated in the lung of old than in young mice after bleomycin challenge. In vitro studies further demonstrate that fibroblasts isolated from lungs of old mice were resistant to H2O2 and tumor necrosis factor alpha-induced apoptosis and had augmented fibrotic responses to TGF-β1, compared to fibroblasts isolated from young mice. Inhibition of PAI-1 activity with a PAI-1 inhibitor, on the other hand, eliminated the aging-related apoptosis resistance and TGF-β1 sensitivity in isolated fibroblasts. Moreover, we show that knocking down PAI-1 in human lung fibroblasts with PAI-1 siRNA significantly increased their sensitivity to apoptosis and inhibited their responses to TGF-β1. Together, the results suggest that increased PAI-1 expression may underlie the aging-related sensitivity to lung fibrosis in part by protecting fibroblasts from apoptosis.

Losartan-antioxidant hybrids: novel molecules for the prevention of hypertension-induced cardiovascular damage

We report the first examples of a new series of antioxidant-sartan hybrids (AO-sartans), which were made by adding an antioxidant fragment to the hydroxymethyl side chain of losartan. Experiments performed in cultured cells demonstrate that these new hybrids retain the ability to block the angiotensin II effect with increased antioxidant ability. In hypertensive rats, these compounds show properties that suggest they may be more useful than losartan for controlling hypertension and preventing hypertension-induced cardiovascular damage.

Clinical improvement in systemic sclerosis resulting from urokinase therapy explained by light and electron microscopy skin examination

OBJECTIVE

In our previous work, patients affected by SSc were treated with intravenous urokinase and showed clinical improvement. In this study we used microscopy to document ultrastructural alterations occurring in sclerodermic skin from SSc patients treated with urokinase.

METHODS

Ten patients with SSc were selected for this study. Skin biopsies were taken from the medial side of the right forearm on the third proximal on the volar surface. The patients were then treated with urokinase for 7 consecutive days. At the end of the treatment, the patients were examined and a new skin biopsy was taken close to the above-mentioned zone of the forearm for optic and electron microscopy examination.

RESULTS

The patients showed a gradual improvement of the skin after urokinase treatment. Raynaud's appeared to be less intense, and they had an increased articular range, with the restoration of movements that had previously been limited. Histological findings showed that, after treatment, skin alterations appeared attenuated, in particular the connective tissue showed a decreased density and inflammatory infiltrate was slight. Electron microscopy findings showed that collagen fibres appeared to have a more regular diameter, and the capillary vessels' lining was thicker, with fewer pinocytotic vesicles.

CONCLUSION

These observations show that urokinase treatment seems to be an interesting therapeutic strategy to consider for the treatment of SSc.

Administration of free radical scavenger edaravone associated with higher frequency of hemorrhagic transformation in patients with cardiogenic embolism

Free radicals are known to activate coagulation and inhibit fibrinolysis. Edaravone, a free radical scavenger, protects vascular endothelial cells and neurons during acute brain ischemia in in vitro models. Hemorrhagic transformation and treatment outcomes were retrospectively examined in 76 patients with acute cardiogenic embolism treated with edaravone in addition to routine treatment within 24 hours of the onset of symptoms. Hemorrhagic transformation was categorized according to European Cooperative Acute Stroke Study-II. Patient characteristics were also evaluated, including evidence of hypertension, diabetes mellitus, hyperlipidemia, coronary heart disease, history of smoking, National Institutes of Health Stroke Scale on arrival, and modified Rankin scale at 3 months post-onset. Edaravone administration was one of the factors that contributed to increased frequency of hemorrhagic transformation, but had showed no significant relationship with the outcome. The present study showed that edaravone administration increased the frequency of hemorrhagic transformation with heparin in patients with cardiogenic embolism. Free radical scavenging may have promoted the coagulating conditions. Edaravone administration may allow reduction of the dose of heparin and tissue plasminogen activator in patients with acute ischemic stroke.

Effect of oxidative stress on the expression of t-PA, u-PA, u-PAR, and PAI-1 in endothelial cells

In this study we examined the effects of exogenous nitric oxide (sodium nitroprusside, SNP) and hydrogen peroxide (H2O2) on the expression level of tissue-type plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA), urokinase-type plasminogen activator receptor (u-PAR), and plasminogen activator inhibitor type 1 (PAI-1) in human umbilical vein endothelial cells (HUVEC). The expression of selected genes involved in fibrynolysis under the influence of oxidative stress was analyzed at the levels of mRNA, protein, and promoter activity. The results of the conducted studies revealed that oxidative stress in endothelial cells causes a significant increase in PAI-1 and u-PAR expression and a moderate increase in t-PA and u-PA expression at all of the investigated levels. We attempted to elucidate the molecular signaling mechanisms by which SNP and H2O2 regulate expression of the respective fibrinolytic factors. Therefore, we tested the protein levels of AP-1, NF-κB, and HIF-1 and their DNA-binding activity in endothelial cells subjected to oxidative stress. We found strong correlation between AP-1, NF-κB, and HIF-1 in the contribution of regulation of selected genes. In addition, we also found that the inhibition of PAI-1 synthesis by antisense oligonucleotide to PAI-1 mRNA results in markedly increased u-PAR expression and that NF-κB and AP-1 are involved in this regulation.

MicroRNA-320 expression in myocardial microvascular endothelial cells and its relationship with insulin-like growth factor-1 in type 2 diabetic rats

1. The aim of the present study was to determine the role of myocardial microvascular endothelial cells (MMVEC) in impaired angiogenesis of type 2 diabetic Goto-Kakizaki (GK) rats. 2. A microRNA (miRNA) microarray was used to assess miRNA expression in MMVEC from GK and Wistar rats. Upregulation of miRNA-320 was observed in MMVEC from GK rats using real-time reverse transcription-polymerase chain reaction (RT-PCR). 3. So far, nine miRNAs have been reported to target angiogenic factors and/or receptors, including kinase insert domain containing receptor (Flk-1), insulin-like growth factor 1 (IGF-1) and insulin-like growth factor 1 receptor (IGF-1R). The predicted genes targeted by miR-320 include Flk-1, IGF-1 and IGF-1R. Western blot analysis and RT-PCR were used to analyse the protein and mRNA expression, respectively, of the putative genes IGF-1 and IGF-1R. The expression of IGF-1 and IGF-1R proteins decreased significantly in diabetic MMVEC. However, the expression of IGF-1 mRNA increased rather than decreased. The mRNA expression of IGF-1R did not differ significantly between diabetic and control MMVEC. 4. Transfection of an miR-320 inhibitor into MMVEC from GK rats confirmed that miR-320 impaired angiogenesis. The proliferation and migration of diabetic MMVEC improved after transfection of the miR-320 inhibitor. In addition, the miR-320 inhibitor significantly increased the expression of IGF-1 protein, but had no effect on the expression of IGF-1R. 5. Eleven miRNAs were upregulated in MMVEC from GK rats compared with those in Wistar rats: let-7e, miR-129, miR-291-5p, miR-320, miR-327, mir-333, miR-363-5p, miR-370, miR-494, miR-503 and miR-664. 6. The results indicate that upregulation of miR-320 in MMVEC from GK rats may be responsible for the inconsistency between the expression of IGF-1 protein and mRNA and therefore related to impaired angiogenesis in diabetes. Transfection of an miR-320 inhibitor may be a therapeutic approach for the treatment of impaired angiogenesis in diabetes.

Impaired capacity for acute endogenous fibrinolysis in smokers is restored by ascorbic acid

Elevated levels of fibrinogen, C-reactive protein, and increased platelet aggregation are known to be increased by cigarette smoking, but the underlying mechanisms of the prothrombotic state in smokers are not completely understood. Since cigarette smoke contains several oxidants, we investigated the effect of the antioxidant ascorbic acid on stimulated fibrinolytic activity in smokers. Long-term heavy smokers and nonsmokers were studied by measurement of forearm blood flow; coinfusion of ascorbic acid was used to reduce oxidative stress. Concentrations of t-PA antigen and activity, of plasminogen activator inhibitor-1 (PAI-1) antigen and activity, and of C-reactive protein were determined by enzyme-linked immunosorbent assays and photometry, respectively. While dose-response curves of forearm blood flow elicited by substance P were not altered by the coadministration of ascorbic acid in nonsmokers, impaired flow in smokers markedly increased, P=0.003. Also, selectively in smokers, the maximal stimulated net release of t-PA antigen and of t-PA activity increased when ascorbic acid was infused simultaneously, P=0.002. In smokers CRP concentrations correlated significantly with the effect of ascorbic acid on maximal t-PA activity release, P<0.0001. Our data demonstrate that the endothelial capacity to acutely release t-PA is significantly reduced in heavy smokers and can be reversed by ascorbic acid. This association is particularly pronounced in smokers with high serum levels of C-reactive protein, suggesting that smoking-induced inflammation impairs fibrinolysis in these patients.

Oxidative stress, plasminogen activator inhibitor 1, and lung fibrosis

Fibrosis is characterized by excessive accumulation of extracellular matrix (ECM) in basement membranes and interstitial tissues, resulting from increased synthesis or decreased degradation of ECM or both. The plasminogen activator/plasmin system plays an important role in ECM degradation, whereas the plasminogen activator inhibitor 1 (PAI-1) is a physiologic inhibitor of plasminogen activators. PAI-1 expression is increased in the lung fibrotic diseases and in experimental fibrosis models. The deletion of the PAI-1 gene reduces, whereas the overexpression of PAI-1 enhances, the susceptibility of animals to lung fibrosis induced by different stimuli, indicating an important role of PAI-1 in the development of lung fibrosis. Many growth factors, including transforming growth factor beta (TGF-beta) and tumor necrosis factor alpha (TNF-alpha), as well as other chemicals/agents, induce PAI-1 expression in cultured cells and in vivo. Reactive oxygen and nitrogen species (ROS/RNS) have been shown to mediate the induction of PAI-1 by many of these stimuli. This review summarizes some recent findings that help us to understand the role of PAI-1 in the development of lung fibrosis and ROS/RNS in the regulation of PAI-1 expression during fibrogenesis.

Induction of PAI-1 expression by tumor necrosis factor alpha in endothelial cells is mediated by its responsive element located in the 4G/5G site

Plasminogen activator inhibitor type 1 (PAI-1) is induced by many proinflammatory and pro-oxidant factors. Among them, tumor necrosis factor alpha (TNFalpha), a pivotal early mediator that regulates and amplifies the development of inflammation, is one of the strongest PAI-1 synthesis activators. Location of the TNFalpha response element in the PAI-1 promoter is still ambiguous. In this study, we attempted to evaluate the significance of the element located in the 4G/5G site of the PAI-1 promoter in the TNFalpha stimulation of PAI-1 expression in endothelial cells. PAI-1 expression was monitored at: (a) the level of mRNA using real-time PCR, (b) PAI-1 gene transcription by transfection reporter assays, and (c) protein synthesis using the enzyme immunoassay. NF-kappaB activity was monitored using the electrophoretic mobility shift assay. Its activity was modified by either antisense oligonucleotides or transfection of endothelial cells with the wild-type or mutated IkappaBalpha. We have shown that TNFalpha-induced expression and gene transcription of PAI-1 involves a regulatory region present in segment -664/-680 of the PAI-1 promoter. This reaction involves the TNFalpha-induced generation of superoxide leading to activation of NF-kappaB, and can be abolished by antioxidants and by overexpression of a super-suppressor phosphorylation-resistant IkappaBalpha. Stimulation of PAI-1 under these conditions involves the motif of the PAI-1 promoter adjacent to the 4G/5G site, which can directly interact with NF-kappaB. We show that activation of PAI-1 gene by TNFalpha and reactive oxygen species is mediated by interaction of NF-kappaB with the cis-acting element located in the -675 4G/5G insertion/deletion in the PAI-1 promoter.

Vascular endothelial dysfunction in diabetic cardiomyopathy: pathogenesis and potential treatment targets

Cardiovascular complications account for significant morbidity and mortality in the diabetic population. Diabetic cardiomyopathy, a prominent cardiovascular complication, has been recognized as a microvascular disease that may lead to heart failure. Pathogenesis of diabetic cardiomyopathy involves vascular endothelial cell dysfunction, as well as myocyte necrosis. Clinical trials have identified hyperglycemia as the key determinant in the development of chronic diabetic complications. Sustained hyperglycemia induces several biochemical changes including increased non-enzymatic glycation, sorbitol-myoinositol-mediated changes, redox potential alterations, and protein kinase C (PKC) activation, all of which have been implicated in diabetic cardiomyopathy. Other contributing metabolic abnormalities may include defective glucose transport, increased myocyte fatty acid uptake, and dysmetabolism. These biochemical changes manifest as hemodynamic alterations and structural changes that include capillary basement membrane (BM) thickening, interstitial fibrosis, and myocyte hypertrophy and necrosis. Diabetes-mediated biochemical anomalies show cross-interaction and complex interplay culminating in the activation of several intracellular signaling molecules. Studies in both animal and human diabetes have shown alteration of several factors including vasoactive molecules that may be instrumental in mediating structural and functional deficits at both the early and the late stages of the disease. In this review, we will highlight some of the important vascular changes leading to diabetic cardiomyopathy and discuss the emerging potential therapeutic interventions.

Abnormalities of coagulation, platelet function, and fibrinolysis associated with syndromes of insulin resistance

Insulin resistance that accompanies obesity, hypertension, polycystic ovary syndrome, and the early phases of type 2 diabetes is characterized by a prothrombotic state. The prothrombotic state is a reflection of the direct effects of hyperinsulinemia and associated metabolic abnormalities (postprandial hyperglycemia, increased free fatty acids, and hypertriglyceridemia) on platelets, coagulation, and fibrinolysis. Therapies that improve insulin sensitivity and thereby decrease insulin resistance, hyperinsulinemia, and metabolic abnormalities decrease the prothrombotic state.

Local inflammatory and thrombotic responses differ in a murine model of partial and complete hindlimb ischemia/reperfusion

BACKGROUND

These experiments were designed to quantitatively compare the patterns of tissue thrombosis, cytokine response, and tissue viability in a murine model of partial (PI) versus complete hindlimb ischemia (CI), alone or with reperfusion (RE).

METHODS

The control tension tourniquet was used to establish either PI or CI in the unilateral mouse hindlimb for 3 hours followed by 0, 4, and 24 hours of RE. Muscle viability, local neutrophil chemoattractant protein, interleukin 6, interleukin 1beta, D-dimer, thrombin-antithrombin III complex, plasminogen activator inhibitor 1, and tissue plasminogen activator levels were measured in protein extracts for each experimental interval.

RESULTS

Tissue viability after CI and 24 hours of RE was significantly less than tissue subjected to PI and 24 hours of RE (96% +/- 16 PI, 64% +/- 4 CI, P=.02). The local cytokine response was initially elevated in the PI group but dissipated by 24RE. In contrast, the local cytokine response to CI alone was small but greatly increased by 24RE. The thrombotic response to PI was increased throughout ischemia/reperfusion. While thrombosis during CI alone was negligible, reperfusion led to a significant thrombotic response.

CONCLUSIONS

Biochemical markers for tissue viability, thrombosis, and cytokine-mediated inflammation differ significantly in mice subjected to moderate and severe hindlimb ischemia/reperfusion. These biochemical markers may facilitate stratification of patients in clinical trials for treatment of ischemia/reperfusion injury and contribute to interpretation of their outcomes.

Protective effect of polyethylene glycol-superoxide dismutase on leukocyte dynamics in rat retinal microcirculation under lipid hydroperoxide-induced oxidative stress

The levels of lipid hydroperoxide (LHPs) in vitreous are elevated in a variety of retinal disorders. Recently, we have shown that increased levels of LHPs in the vitreous enhanced leukocyte-endothelium interaction in the retina, which should contribute to the initial disturbance of the retinal microcirculation. Based upon the previous work, the purpose of the present study was to investigate the effect of polyethylene glycol-superoxide dismutase (PEG-SOD), one of the important enzyme antioxidants, on leukocyte-endothelial interaction in the retinal microcirculation under LHP-induced oxidative stress. Male Brown-Norway rats weighing approximately 250 g were used. LHP(18:2) was made from linoleic acid (LA) with lipoxygenase and 10 microg of LHP dissolved in 5 microl of sodium borate buffer (SBB, 0.02 m) was slowly injected into the vitreous using a 33-gauge needle. PEG-SOD (5000 units/kg) was given intravenously 5 min before LHP injection. At 2, 4, 6, 12, 24 and 48 hr after the vitreous injections, we evaluated the number of rolling leukocytes along the major retinal veins and the number of leukocytes that accumulated in the retinal microvasculature with acridine orange digital fluorography. In LHP-treated rats, leukocyte rolling along the major retinal veins was maximal at 6 hr after LHP injection. The number of rolling leukocytes in the PEG-SOD-treated rats was decreased to 5.5% of those in the LHP-treated rats at 6 hr after LHP injection (P<0.01). No rolling leukocytes were observed in either control or vehicle-treated eyes. The number of accumulated leukocytes in LHP-treated eyes started to increase at 12 hr, and peaked at 24 hr which was significantly higher than in both control and vehicle-treated eyes (P<0.01). The number of accumulated leukocytes in the PEG-SOD-treated rats was reduced by 88.0% at 24 hr (P<0.01). Intravenous injection of PEG-SOD significantly inhibited the leukocyte rolling and its accumulation under LHP-induced oxidative stress. These results suggest that PEG-SOD might attenuate various retinal microcirculatory disorders associated with LHP.

Molecular mechanisms of tumor necrosis factor-alpha-mediated plasminogen activator inhibitor-1 expression in adipocytes

Increased expression of plasminogen activator inhibitor -1 (PAI-1) in adipose tissues is thought to contribute to both the cardiovascular and metabolic complications associated with obesity. Tumor necrosis factor alpha (TNF-alpha) is chronically elevated in adipose tissues of obese rodents and humans and has been directly implicated to induce PAI-1 in adipocytes. In this study, we used 3T3-L1 adipocytes to examine the mechanism by which TNF-alpha up-regulates PAI-1 in the adipocyte. Acute (3 h) and chronic (24 h) exposure of 3T3-L1 adipocytes to TNF-alpha induces PAI-1 mRNA by increasing the rate of transcription of the PAI-1 gene, and de novo protein synthesis is not required for this process. Although the p44/42 and PKC signaling pathways appear to be significant in the induction of PAI-1 mRNA in response to acute treatment with TNF-alpha, the more dramatic induction of PAI-1 mRNA observed in response to chronic exposure of adipocytes to TNF-alpha was mediated by these and additional signaling molecules, including p38, PI3-kinase, tyrosine kinases, and the transcription factor NF-kappaB. Moreover, the dramatic increase in PAI-1 observed after chronic exposure of adipocytes to TNF-alpha was accompanied by increased metabolic insulin resistance. Finally, we demonstrate that the PKC pathway is also central for PAI-1 induction in response to insulin and transforming growth factor-beta (TGF-beta), two additional molecules which are elevated in obesity and shown to directly induce PAI-1 in the adipocyte. The understanding of the mechanism of regulating PAI-1 expression in the adipocytes at the molecular level provides new insight to help identify novel targets in fighting the pathological complications of obesity.

Risk stratification in patients with unstable angina and/or non-ST-elevation myocardial infarction by Troponin T and plasminogen-activator-inhibitor-1 (PAI-1)

BACKGROUND

Increased Troponin T (TnT) and PAI-1 levels are markers of poor outcome in acute coronary syndromes (ACS). In order to stratify the risk for 30-day combined endpoint of mortality and/or reinfarction in unstable angina and/or non-ST-elevation myocardial infarction (UA/NSTEMI), TnT and PAI-1 levels were simultaneously assessed.

METHODS

The TnT and PAI-1 levels of 113 patients with UA/NSTEM were estimated within the first 48 h. Initial therapy was medical. Percutaneous coronary interventions were performed in case of recurrent ischemia and/or hemodynamic and/or rhythmic instability.

RESULTS

Statistically significant differences in mean admission PAI-1 (4.2+/-3.4 vs. 2.8+/-2.4 U/ml, p<0.05), mean peak PAI-1 levels within the first 48 h (4.98 +/- 3.1 vs. 3.4 +/- 2.5 U/ml, p < 0.05), and no significant difference in any TnT level were observed between patients with and without 30-day mortality and/or reinfarction. The risk for 30-day mortality and/or reinfarction significantly increased in patients with admission PAI-1 levels > 4.0 U/ml (OR=4.44, 95%CI=1.47-13.4), peak PAI-1 levels > 4.0 U/ml (OR=5.78, 95%CI=1.838-18.20) and with simultaneously increased peak PAI-1 > 3.5 U/ml and TnT > 0.1 microg/l within the first 48 h (OR=4.9, 95%CI=1.569-15.385).

CONCLUSIONS

Simultaneous assessment of TnT and PAI-1 would provide complementary prognostic information and enable clinicians to stratify risk more effectively among patients with UA/NSTEMI.

Platelet function, coagulopathy, and impaired fibrinolysis in diabetes

Diabetes and the metabolic syndrome, including insulin resistance, that underlies it are hyper-coagulable states. Increased platelet reactivity,augmented activity of the coagulation system,and impaired fibrinolysis are characteristic and understood to a remarkable extent. In aggregate,these derangements contribute to accelerated atherosclerosis, premature coronary artery dis-ease, and a profound toll from both.

Prognostic utility of comparative methods for assessment of ST-segment resolution after primary angioplasty for acute myocardial infarction: the Controlled Abciximab and Device Investigation to Lower Late Angioplasty Complications (CADILLAC) trial

OBJECTIVE

This study was done to assess and compare the prognostic significance of multiple methods for measuring ST-segment elevation resolution (STR) following primary percutaneous coronary intervention (PCI).

BACKGROUND

Resolution of ST-segment elevation (STE) is a powerful predictor of both infarct-related artery patency and mortality in acute myocardial infarction (AMI). Recent thrombolytic studies have suggested that simple measures of STR may be as powerful as more complex algorithms. The optimal method of assessing STR following primary PCI has not been studied.

METHODS

We analyzed 700 patients with technically adequate baseline and post-PCI electrocardiograms from the Controlled Abciximab and Device Investigation to Lower Late Angioplasty Complications (CADILLAC) trial. Five methods were used to assess STR: 1) summed %STR across multiple leads (SigmaSTR); 2) %STR in the single lead with maximum baseline STE (MaxSTR); 3) absolute maximum STE before the procedure; 4) absolute maximum STE after intervention (MaxSTPost); and 5) a categorical variable based upon MaxSTPost (High Risk).

RESULTS

At 30 days, SigmaSTR, MaxSTR, and MaxSTPost all correlated strongly with mortality (p = 0.004, p = 0.005, and p < 0.0001, respectively) and the combined end point of mortality or reinfarction (p = 0.001, p = 0.001, and p < 0.0001). At one year, SigmaSTR and MaxSTPost correlated with mortality (p = 0.04, p = 0.0001), reinfarction (p = 0.02, p = 0.0015), and the combined end point (p = 0.02, p < 0.0001). By multivariate analysis, only the simpler measures of MaxSTPost and High Risk categorization independently predicted all outcomes at both time points.

CONCLUSIONS

The STR following primary PCI in AMI correlates strongly with mortality and reinfarction, independent of target vessel patency. The simple measure of the maximal residual degree of STE after primary PCI is a strong independent predictor of both survival and freedom from reinfarction at 30 days and 1 year.

Angioplasty-induced superoxide anions and neointimal hyperplasia in the rabbit carotid artery: suppression by the isoflavone trans-tetrahydrodaidzein

Reactive oxygen species (ROS) may contribute to the development of stenosis in balloon catheter injured arteries. As isoflavones exhibit effects on ROS and cell proliferation In vitro that appear useful in preventing such stenosis, we examined the effects of the isoflavone trans-tetrahydrodaidzein (trans-THD) on development of neointimal lesions in relation to elevations in ROS in balloon catheter injured arteries. Carotid arteries of rabbits treated with either vehicle or trans-THD were injured with an inflated balloon catheter and cell proliferation, collagen content, ROS and vessel structure determined over the ensuing 28 days. Seven days after injury neointimal smooth muscle cell proliferation was reduced by 50% (p < 0.05) whilst medial cell proliferation was largely unaffected (p > 0.10). At this time ROS levels in vehicle-treated rabbits were elevated 3-fold compared to uninjured arteries (p < 0.05). Treatment with trans-THD reduced ROS levels to those seen in uninjured arteries (p > 0.05). The antiproliferative effects of trans-THD on intimal cell proliferation persisted 14 days after the injury, and twenty eight days after injury the size of the lumen in trans-THD-treated animals was 27% greater (p < 0.05) and the intima area: vessel area reduced by 40% (p < 0.05). The small effects of trans-THD on collagen accumulation was not statistically significant, indicating that effects on neointimal cell proliferation was the major mechanism by which this isoflavone attenuated development of the neointima. Intimal smooth muscle cells and ROS represent potentially important targets for the antiproliferative actions of trans-THD in injured arteries. Strategies using such isoflavones may be useful for preventing restenosis after vascular manipulations in humans.

Oxidative stress and hypoxia: implications for plasminogen activator inhibitor-1 expression

Plasminogen activator inhibitor-1 (PAI-1) is the major physiological inhibitor of urokinase-type and tissue-type plasminogen activators. It has gained special interest among clinicians because a number of pathological conditions, such as myocardial infarction, atherosclerosis, thrombosis, several types of cancer, and the metabolic syndrome, as well as type 2 diabetes mellitus, are associated with increased PAI-1 levels. Interestingly, a number of these diseases are also accompanied by oxidative stress and the enhanced production of reactive oxygen species or tissue hypoxia. This article tries to summarize some aspects leading to enhanced PAI-1 production under oxidative stress or hypoxia.

Enhanced plasminogen activator inhibitor-1 expression in transgenic mice with hepatocyte-specific overexpression of superoxide dismutase or glutathione peroxidase

In this study, we developed a double-transgenic mouse model allowing hepatocyte-specific and regulated expression of the redox-modifying enzymes copper/zinc superoxide dismutase (SOD) and glutathione peroxidase (GPX) by using a tetracycline-regulatable gene expression system. Within this system, the SOD and GPX level can be regulated deliberately by addition or removal of doxycycline hydrochloride to the drinking water. As reactive oxygen species (ROS) have been implicated in a number of pathological conditions, such as atherosclerosis, thrombosis, or liver fibrosis, processes that are also frequently associated with enhanced levels of plasminogen activator inhibitor-1 (PAI-1), it was the aim of the present study to investigate the influence of SOD and GPX overexpression on the regulation of PAI-1. PAI-1 mRNA and protein levels in tetracycline transactivator-dependent SOD-overexpressing double-transgenic mice reached values 2.5- to threefold above the normal mRNA level. By applying doxycycline, a deinduction of the PAI-1 levels was observed. By using the same protocol, PAI-1 mRNA and protein levels were enhanced in GPX double-transgenic mice, and again this response was blunted by the addition of doxycycline. These studies provide some new information regarding the role of ROS within the proteolytic processes in hepatocytes that require PAI-1.

Redox regulation of HIF-1alpha levels and HO-1 expression in renal medullary interstitial cells

The present study hypothesized that superoxide (O2(-)*) importantly contributes to the regulation of hypoxia-inducible factor (HIF)-1alpha expression at posttranscriptional levels in renal medullary interstitial cells (RMICs) of rats. By Western blot analysis, it was found that incubation of RMICs with O2(-)* generators xanthine/xanthine oxidase and menadione significantly inhibited the hypoxia- or CoCl(2)-induced increase in HIF-1alpha levels and completely blocked the increase in HIF-1alpha levels induced by ubiquitin-proteasome inhibition with CBZ-LLL in the nuclear extracts from these cells. Under normoxic conditions, a cell-permeable O2(-)* dismutase (SOD) mimetic, 4-hydroxyl-tetramethylpiperidin-oxyl (TEMPOL) and PEG-SOD, significantly increased HIF-1alpha levels in RMICs. Two mechanistically different inhibitors of NAD(P)H oxidase, diphenyleneiodonium and apocynin, were also found to increase HIF-1alpha levels in these renal cells. Moreover, introduction of an anti-sense oligodeoxynucleotide specific to NAD(P)H oxidase subunit, p22(phox), into RMICs markedly increased HIF-1alpha levels. In contrast, the OH* scavenger tetramethylthiourea had no effect on the accumulation of HIF-1alpha in these renal cells. By Northern blot analysis, scavenging or dismutation of O2(-)* by TEMPOL and PEG-SOD was found to increase the mRNA levels of an HIF-1alpha-targeted gene, heme oxygenase-1. These results indicate that increased intracellular O2(-)* levels induce HIF-1alpha degradation independently of H(2)O(2) and OH* radicals in RMICs. NAD(P)H oxidase activity may importantly contribute to this posttranscriptional regulation of HIF-1alpha in these cells under physiological conditions.

The renin-angiotensin system is involved in the production of plasminogen activator inhibitor type 1 by cultured endothelial cells in response to chylomicron remnants

Triglyceride-rich lipoproteins have been suggested to promote atherosclerosis. Plasminogen activator inhibitor type 1 (PAI-1) plays an important role in the events of cardiovascular pathophysiology. The renin-angiotensin system influences various vascular functions, including PAI-1 production. We examined whether or not chylomicron remnants increased PAI-1 mRNA and protein production in endothelial cells and whether or not an inhibition of the renin-angiotensin system interfered with this effect. Chylomicron remnants were isolated from functionally hepatectomized rats injected with chylomicrons. Human umbilical vein endothelial cell cultures (HUVECs) were incubated with chylomicron remnants with or without an angiotensin-converting enzyme inhibitor (temocaprilat), an angiotensin II receptor type 1 antagonist (RNH-6270), or an angiotensin II receptor type 2 antagonist (PD123319). Chylomicron remnants increased PAI-1 secretion in HUVECs (0.5 microg/ml; 128.3 +/- 6.1%, the mean +/- SEM) as well as angiotensin II (10 nmol/l; 130.7 +/- 9.5%) in 18 h, as compared with the controls, as well as stimulated PAI-1 mRNA expression to a maximum level at 4 h. Temocaprilat and RNH-6270, but not PD123319, attenuated all of these effects. Chylomicron remnants enhanced nuclear extract binding to a very low-density lipoprotein response element in the PAI-1 promoter region and activated nuclear factor-kappaB. Extracellular signal-regulated kinase (ERK 1/2) was phosphorylated in response to chylomicron remnants. These effects were inhibited by temocaprilat or RNH-6270. In conclusion, chylomicron remnants increased protein secretion and mRNA expression of PAI-1 in HUVECs. Inhibition of the renin-angiotensin system reduced this stimulation.

Increased Expression of Plasminogen Activator Inhibitor-1 by Mediators of the Acute Phase Response: a Potential Progenitor of Vasculopathy in Hypertensives

Hypertension is an important risk factor for coronary atherosclerosis, which is accelerated by inflammation and diminished fibrinolysis. We have previously shown that levels of plasminogen activator inhibitor-1 (PAI-1), the major physiologic inhibitor of fibrinolysis, are increased with atherogenic metabolic derangement. Because the liver is one of the major sources of circulating PAI-1, we here examined the effects of two proinflammatory cytokines, interleukin (IL)-1beta, and IL-6, on PAI-1 production in a human hepatoma cell line, HepG2. IL-1beta (1 ng/ml) and IL-6 (1 ng/ml) increased the accumulation of PAI-1 in the conditioned media over 24 h (IL-1beta: 2.1 +/- 0.2 (mean +/- SD) fold over the control; IL-6:1.4 +/- 0.2 fold; Western blot, p < 0.05). The increase in PAI-1 protein accumulation correlated with the increased expression of PAI-1 mRNA (Northern blot). An HMG-CoA reductase inhibitor (mevastatin, 10 micromol/l) attenuated the PAI-1 production induced by IL-1beta and IL-6. The plasma PAI-1 activity level was higher in hypertensives than in normotensives (10.0 +/- 9.8 AU/ml vs. 6.2 +/- 4.5 AU/ml, p < 0.05). The plasma PAI-1 antigen level was also higher in hypertensives than in normotensives (30.9 +/- 22.4 ng/ml vs. 24.4 +/- 13.3 ng/ml, p < 0.05). Thus, 1) IL-1beta and IL-6 can increase PAI-1 production in hepatic cells and 2) mevastatin may exert anti-thrombotic effects by decreasing the PAI-1 protein production induced by these proinflammatory cytokines. These results provide further insights into how inflammation is involved in the atherothrombotic complications observed in hypertensives, which may be ameliorated by HMG-CoA reductase inhibitors.

Cardiac endothelial-myocardial signaling: its role in cardiac growth, contractile performance, and rhythmicity

Experimental work during the past 15 years has demonstrated that endothelial cells in the heart play an obligatory role in regulating and maintaining cardiac function, in particular, at the endocardium and in the myocardial capillaries where endothelial cells directly interact with adjacent cardiomyocytes. The emerging field of targeted gene manipulation has led to the contention that cardiac endothelial-cardiomyocytal interaction is a prerequisite for normal cardiac development and growth. Some of the molecular mechanisms and cellular signals governing this interaction, such as neuregulin, vascular endothelial growth factor, and angiopoietin, continue to maintain phenotype and survival of cardiomyocytes in the adult heart. Cardiac endothelial cells, like vascular endothelial cells, also express and release a variety of auto- and paracrine agents, such as nitric oxide, endothelin, prostaglandin I(2), and angiotensin II, which directly influence cardiac metabolism, growth, contractile performance, and rhythmicity of the adult heart. The synthesis, secretion, and, most importantly, the activities of these endothelium-derived substances in the heart are closely linked, interrelated, and interactive. It may therefore be simplistic to try and define their properties independently from one another. Moreover, in relation specifically to the endocardial endothelium, an active transendothelial physicochemical gradient for various ions, or blood-heart barrier, has been demonstrated. Linkage of this blood-heart barrier to the various other endothelium-mediated signaling pathways or to the putative vascular endothelium-derived hyperpolarizing factors remains to be determined. At the early stages of cardiac failure, all major cardiovascular risk factors may cause cardiac endothelial activation as an adaptive response often followed by cardiac endothelial dysfunction. Because of the interdependency of all endothelial signaling pathways, activation or disturbance of any will necessarily affect the others leading to a disturbance of their normal balance, leading to further progression of cardiac failure.

Plasminogen activator inhibitor-1 in patients with atrial arrhythmias during acute myocardial infarction, treated with streptokinase

Atrial arrhythmias (AA), especially atrial fibrillation (AF), during acute myocardial infarction (AMI) are often associated with increased mortality and heart failure. Impaired fibrinolysis with elevated plasminogen activator inhibitor-1 (PAI-1) activity is associated with resistance to fibrinolytic therapy in AMI patients, but it is also found in patients with AF. Our aim was a prospective study of the role of pre-treatment PAI-1 levels for the presence of AA in AMI patients and the influence of AA on in-hospital mortality. In 116 AMI patients, treated with streptokinase, pre-treatment PAI-1 levels were estimated by the chromogenic method (normal levels, 0.3-3.5 U/ml) and in-hospital AA were assessed as atrial fibrillation, flutter and/or tachycardias. Between patients with and without AA, a significant difference was observed in mean pre-treatment PAI-1 levels, in several in-hospital complications and mortality (24 versus 4.4%; P < 0.01; odds ratio, 6.45; 95% confidence interval, 1.66-25.0). The PAI-1 level > 7 U/ml was the most significant independent pre-treatment risk factor for AA (P < 0.05; odds ratio, 3.5; 95% confidence interval, 1.15-10.6). We conclude that AA were a significant risk for in-hospital mortality of AMI patients, treated with streptokinase. A pre-treatment PAI-1 level > 7 U/ml was the most significant pre-treatment risk for AA in these patients.

Oxidative stress and hemodynamic maladjustment in chronic renal disease: a therapeutic implication

Hemodynamic maladjustment with predominant constriction at the efferent arteriole has been encountered in a variety of clinical settings of glomerulonephropathy. In essence, it induces not only intraglomerular hypertension but also exaggeratedly reduces the peritubular capillary flow, which supplies the tubulointerstitial compartment. The hemodynamic maladjustment is believed to reflect a glomerular endothelial cell dysfunction. In this regard, oxidative stress and antioxidant defect are likely responsible for the glomerular endothelial dysfunction. Improvement in renal function was accomplished following the correction of oxidant and antioxidant imbalance with antioxidant therapy and vasodilators. Following such therapy, there was a correction in hemodynamic maladjustment with a decline in intraglomerular hydrostatic pressure and an increase in renal perfusion with a subsequent increase in renal functions namely creatinine clearance, glomerular filtration rate and a decline in FEMg.

Interleukin-10 protects nitric oxide-dependent relaxation during diabetes: role of superoxide

Interleukin (IL)-10, an anti-inflammatory cytokine, preserves endothelial function during acute inflammation. We tested the hypotheses that IL-10 plays a protective role in blood vessels during diabetes by suppressing impairment of endothelium-dependent relaxation and that protection by IL-10 is mediated by effects on superoxide (O(2-)). Streptozotocin (150 mg/kg i.p.) or citrate buffer was injected into IL-10-deficient (IL-10(-/-)) mice and wild-type controls (IL-10(+/+)). In IL-10(+/+) and IL-10(-/-) mice, blood glucose levels were approximately 120 mg/dl after citrate administration and approximately 400 mg/dl after streptozotocin administration. Vasorelaxation was examined in arteries in vitro 12-16 weeks later. Maximum relaxation to acetylcholine (30 micromol/l) was 88 +/- 3% (means +/- SE) in nondiabetic mice and 84 +/- 3% in diabetic IL-10(+ /+) mice (P > 0.05). Thus, at this time point, diabetes did not impair endothelium-dependent relaxation in vessels in wild-type mice. In contrast, maximum relaxation in vessels from diabetic IL-10(-/-) mice was significantly decreased (74 +/- 5%) compared with nondiabetic IL-10(-/-) mice (93 +/- 2%, P < 0.05). Superoxide dismutase with polyethylene glycol (PEG-SOD) restored impaired responses to acetylcholine to levels seen in controls. Responses to acetylcholine also were improved by allopurinol (an inhibitor of xanthine oxidase) in vessels from diabetic IL-10(- /-) mice. Thus, diabetes produces greater impairment of relaxation to acetylcholine in IL-10(-/-) mice than in IL-10(+/ +) mice. These findings provide direct evidence that IL-10 impedes mechanisms of endothelial dysfunction during diabetes. Restoration of vasorelaxation with PEG-SOD or allopurinol suggests that the mechanism(s) by which IL-10 preserves endothelium-dependent vasorelaxation involves O(2-), perhaps by reducing production of O(2-) by xanthine oxidase.

Valsartan improves fibrinolytic balance in atherosclerotic rabbits

OBJECTIVES

To examine the long-term effects of the angiotensin type I (AT1) receptor antagonist, valsartan, on fibrinolytic balance, coagulation parameters, endothelial function and structural alterations in atherosclerotic rabbits.

METHODS

Animals were submitted to a 1% cholesterol-enriched diet for 10 weeks. Half of the animals were treated with valsartan (3 or 10 mg/kg per day). Systolic arterial pressure was directly measured in awake rabbits. Tissue plasminogen activator (t-PA) and tissue plasminogen activator inhibitor (PAI-1) activities were measured. Plasma concentrations of cholesterol, D-dimer, factor VIII and fibrinogen, as well as thrombin time, were also determined. Responses to acetylcholine, sodium nitroprusside and angiotensin II were evaluated in aortic rings. Morphometric analysis of aortic segments was also performed to calculate atherosclerotic lesion.

RESULTS

Cholesterol-fed rabbits presented systolic arterial pressure levels comparable to controls. These animals presented aortic atherosclerotic lesions. Treatment with valsartan did not alter plasma cholesterol levels or arterial pressure in any group. Acetylcholine-induced relaxations and D-dimer and t-PA activity were lower (P < 0.05) in atherosclerotic than in normal rabbits. In contrast, PAI-1 activity was higher (P < 0.05) in atherosclerotic rabbits than in controls. Valsartan increased (P < 0.05) acetylcholine-induced relaxations, D-dimer concentration and t-PA activity, and reduced intimal thickening and PAI-1 activity in cholesterol-fed rabbits. Fibrinogen concentrations and factor VIII concentrations were lower (P < 0.05) and thrombin time was higher (P < 0.05) in atherosclerotic rabbits compared to controls. Valsartan did not affect factor VIII in any group, but reduced fibrinogen levels only in hypercholesterolemic rabbits. Valsartan 10 mg/kg per day reduced (P < 0.05) thrombin time in cholesterol-fed rabbits.

CONCLUSIONS

Impairment of fibrinolytic balance, associated with atherosclerosis in rabbits, appears to be related with angiotensin II via AT1receptors. The beneficial effect of valsartan on fibrinolysis seems to be related to the concomitant amelioration of endothelial dysfunction and reduction of intimal thickening, further supporting the importance of the blockade of angiotensin II actions to prevent thrombotic alterations associated with atherosclerosis.

Plasminogen activator inhibitor type 1 and outcome after successful cardiopulmonary resuscitation

OBJECTIVE

Patients after successful cardiopulmonary resuscitation have been shown to exhibit elevated plasma concentrations of plasminogen activator inhibitor (PAI) type 1, the main circulating antifibrinolytic protein. It has been suggested that elevations in PAI-1 contribute to cerebral no-reflow after successful cardiopulmonary resuscitation. We analyzed whether PAI-1 concentrations might predict cerebral outcome after cardiopulmonary resuscitation.

DESIGN

Prospective, controlled study.

SETTING

Intensive care unit at a university hospital.

PATIENTS

Thirty-five patients after successful cardiopulmonary resuscitation and 35 control patients who were not critically ill.

INTERVENTIONS

Blood sampling for determination of plasma concentrations of active and total PAI-1 antigen.

MEASUREMENTS AND MAIN RESULTS

Plasma concentrations of total and active PAI-1 antigen on the second day after successful cardiopulmonary resuscitation were significantly higher in patients after cardiopulmonary resuscitation than in controls (p <.0001) and were unrelated to duration of cardiopulmonary resuscitation. Both active and total PAI-1 antigen were higher in patients who developed acute renal failure after cardiopulmonary resuscitation. Patients with an unfavorable cerebral outcome after cardiopulmonary resuscitation had higher total PAI-1 antigen concentrations compared with patients with good outcome after cardiopulmonary resuscitation (p =.026). We identified 180 ng/mL as the best cutoff value for total PAI-1 antigen with respect to cerebral outcome (chi-square 11.8, p =.001). In a logistic regression analysis, only systemic inflammatory response syndrome (p =.028), acute renal failure after cardiopulmonary resuscitation (p =.017), and cardiopulmonary resuscitation duration >15 mins (p =.042) were significantly and independently associated with cerebral outcome after cardiopulmonary resuscitation. Total PAI-1 antigen reached only borderline significance (p =.058) but nevertheless slightly improved the correct prediction of cerebral outcome after cardiopulmonary resuscitation.

CONCLUSIONS

Acute renal failure after cardiopulmonary resuscitation, systemic inflammatory response syndrome, and cardiopulmonary resuscitation duration are better predictors of cerebral outcome after cardiopulmonary resuscitation than PAI-1 antigen, but determination of total PAI-1 antigen nevertheless might improve the early prediction of cerebral outcome after cardiopulmonary resuscitation. Whether elevated PAI-1 concentrations, possibly via prothrombogenic/antifibrinolytic effects, contribute causally to cerebral no-reflow and acute renal failure after cardiopulmonary resuscitation remains to be clarified.