Plasminogen activator inhibitor-1 (PAI-1): a key factor linking fibrinolysis and age-related subclinical and clinical conditions

Characterization of a small molecule inhibitor of plasminogen activator inhibitor type 1 that accelerates the transition into the latent conformation

A novel class of small molecule inhibitors for plasminogen activator inhibitor type 1 (PAI-1), represented by AZ3976, was identified in a high throughput screening campaign. AZ3976 displayed an IC(50) value of 26 μm in an enzymatic chromogenic assay. In a plasma clot lysis assay, the compound was active with an IC(50) of 16 μm. Surprisingly, AZ3976 did not bind to active PAI-1 but bound to latent PAI-1 with a K(D) of 0.29 μm at 35 °C and a binding stoichiometry of 0.94, as measured by isothermal calorimetry. Reversible binding was confirmed by surface plasmon resonance direct binding experiments. The x-ray structure of AZ3976 in complex with latent PAI-1 was determined at 2.4 Å resolution. The inhibitor was bound in the flexible joint region with the entrance to the cavity located between α-helix D and β-strand 2A. A set of surface plasmon resonance experiments revealed that AZ3976 inhibited PAI-1 by enhancing the latency transition of active PAI-1. Because AZ3976 only had measurable affinity for latent PAI-1, we propose that its mechanism of inhibition is based on binding to a small fraction in equilibrium with active PAI-1, a latent-like prelatent form, from which latent PAI-1 is then generated more rapidly. This mode of action, with induced accelerated latency transition of active PAI-1 may, together with supporting x-ray data, provide improved opportunities for small molecule drug design in the hunt for therapeutically useful PAI-1 inhibitors.

The urokinase plasminogen activator system in breast cancer invasion and metastasis

The urokinase plasminogen activator system, which is a serine protease family include urokinase-type plasminogen activator (uPA), the uPA receptor and plasminogen activator inhibitors (PAIs). uPA catalyzes the transformation of plasminogen to its active form plasmin, which is able to degrade the extracellular matrix (ECM) and basement membranes, directly or indirectly through activating pro-matrix metalloproteinases (pro-MMPs), promoting cancer cell metastasis and invasion. Both uPA and PAI-1 are poor prognosis markers in primary breast cancer. Evidence has been presented that the uPA system facilitates breast cancer metastasis by several different mechanisms, such as the Ras-ERK pathway and p38 MAPK pathway. This review focuses on uPA system, summarizes their biological effects, highlights the molecular mechanism and pathway, and discusses the role of uPA system in the prevention and treatment of human breast cancers.

Association of adipokines and adhesion molecules with indicators of obesity in women undergoing mammography screening

BACKGROUND

The soluble cell adhesion molecules and adipokines are elevated in patients with obesity, hypertension, type 2 diabetes mellitus, breast cancer and atherosclerosis.

OBJECTIVE

To investigate the relationship between anthropometric profile, dietary intake, lipid profile and fasting glycemia with serum levels of adipokines (adiponectin and PAI-1) and adhesion molecules (ICAM-1 and VCAM-1) in women without breast cancer undergoing routine mammographic screening.

DESIGN

Transversal study.

SUBJECTS

One hundred and forty-five women over 40-years old participated in this study.

RESULTS

In 39.3% of cases the BMI was above 30 kg/m2; 46.9% had hypertension, 14.5% had type 2 Diabetes Mellitus, 31.7% had dyslipidemia and 88.3% presented a waist-to-hip ratio ≥ 0.8. A linear correlation was found between serum levels of PAI-1 and triglycerides, between serum levels of PAI-1 and WHR and between serum levels of VCAM-1 and BMI.

CONCLUSION

We found a high prevalence of obesity and metabolic syndrome. PAI-1 and VCAM-1 levels were correlated with clinical indicators of obesity and overweight.

Gastrectomy for early gastric cancer is associated with decreased cardiovascular mortality in association with postsurgical metabolic changes

BACKGROUND

Bariatric surgery effectively induces weight loss and resolves cardiovascular comorbidities in obese patients. We investigated cardiovascular and all-cause mortality in patients who underwent gastrectomies for early gastric cancer (EGC) and analyzed the changes in metabolic parameters after surgery.

METHODS

A total of 2,477 patients who underwent gastrectomies for EGC between 1995 and 2004 were enrolled in the study and followed for mortality through 2007. Standardized mortality ratios (SMRs) were calculated using sex- and age-matched mortality in the general Korean population in 2005. Effects of gastrectomy on changes in body weight and metabolic parameters were investigated in 51 of the patients before and after surgery.

RESULTS

During the 15,096.4 person-years of follow-up, 244 deaths were recorded. The all-cause mortality was not significantly different from that of the general population (SMR [95 % confidence interval (CI)] = 1.01 [0.89 - 1.14]); however, cardiovascular mortality was significantly lower (SMR = 0.35 [0.22 - 0.53]). In the 51 patients included in the second part of the study, significant reductions in body weight and visceral fat areas occurred after surgery, regardless of whether the patients were previously obese. Triglycerides, LDL-cholesterol, and plasminogen activator inhibitor-1 levels were significantly decreased, whereas HDL-cholesterol and adiponectin levels were increased. Carotid intima-media thickness also was significantly decreased in previously obese and nonobese patients.

CONCLUSIONS

Patients with EGC who undergo gastrectomy have a lower cardiovascular mortality but similar all-cause mortality as that of the general population. In these patients, a significant reduction in body weight and visceral fat after surgery may improve impaired lipid metabolism and prevent atherosclerotic changes.

Metabolic syndrome: a novel high-risk state for colorectal cancer

Metabolic syndrome (MS) and related disorders, including cancer, are steadily increasing in most countries of the world. However, mechanisms underlying the link between MS and colon carcinogenesis have yet to be fully elucidated. In this review article we focus on the relationships between various individual associated conditions (obesity, dyslipidemia, diabetes mellitus type 2 and hypertension) and colon cancer development, and demonstrate probable related factors revealed by in vivo and in vitro studies. Furthermore, molecules suggested to be involved in cancer promotion are addressed, and the potential for cancer prevention by targeting these molecules is discussed.

Intermittent hypoxia-induced renal antioxidants and oxidative damage in male mice: hormetic dose response

Obstructive sleep apnea causes cardiovascular disease via chronic intermittent hypoxia (IH), which may be related to oxidative stress. Nuclear factor-erythroid 2-related factor 2 (Nrf2) is an important cellular defense mechanism against oxidative stress by regulating its down-stream multiple antioxidants. The present study was to define whether IH can induce renal pathogenic damage and if so, whether Nrf2 and its down-stream antioxidants are involved in IH-induced pathogenic changes. Mice were culled for exposure to intermittent air as control or IH that consisted of 20.9% O2/ 8% O2 FIO2 alternation cycles (30 episodes per h) with 20 seconds at the nadir FIO2 for 12 h a day during daylight. Short-term IH exposure (3 - 7 days) induced significant increases in renal inflammatory response and antioxidant levels along with a reduction of the spontaneous content of malondialdehyde while long-term IH exposure (8 weeks) induced a significant decrease of antioxidant levels and significant increases of renal inflammation, oxidative damage, cell death, and fibrosis. This study suggests that IH induces a hormetic response, i.e.: short-term IH exposure is able to induce a protective response to protect the kidney from oxidative damage while long-term IH exposure is able to induce a damage effect on the kidney.

Gender specifics of the association between blood fibrinolytic activity and cardiovascular disease or diabetes mellitus in a cohort of Muscovites aged 55 years or older

Aim. To investigate potential gender differences in the association between plasma fibrinolytic activity (FLA) and atherosclerotic pathology in elderly people. Material and methods. This analysis was performed as a part of the prospective population-based cohort study “Stress, Ageing, and Health in Russia”. The study included randomly selected Moscow residents of both genders and age of ≥55 years (n=1863; 889 men and 974 women). Based on the levels of blood FLA (time of spontaneous lysis of euglobin blood fraction, or euglobin lysis time, ELT), all participants were divided into three groups: with normofibrinolysis (ELT 180-260 minutes), hypofibrinolysis (ELT >260 minutes), and hyperfibrinolysis (ELT <180 minutes). Results. In this cohort of elderly Muscovites, the association between FLA and the presence of cardiovascular disease (CVD) or Type 2 diabetes mellitus (DM-2) differed in men and women. The link between hypofibrinolysis, atherogenic changes in lipid profile, or high fasting levels of insulin and arterial hypertension (AH), myocardial infarction (MI), or DM-2 was present only in men. In women, either reduced or increased FLA was not related to DM-2. Men with hyperfibrinolysis demonstrated lower odds of AH and DM-2, while women with hyperfibrinolysis had lower odds of AH, coronary heart disease, or angina. Conclusion. In elderly people, high FLA appears to provide protection against atherothrombotic pathology, regardless of gender. Low FLA was associated with higher odds of CVD and DM-2 in men only.

Plasminogen activator inhitor-1 associates with cardiovascular risk factors in healthy young adults in the Cardiovascular Risk in Young Finns Study

AIMS

Hypofibrinolysis displayed by elevated serum plasminogen activator inhibitor 1 (PAI-1) level has been associated with cardiovascular disease (CVD) and its risk factors such as obesity and insulin resistance. However, no studies have examined associations between PAI-1 and CVD risk factors in healthy subjects. We examined associations between serum PAI-1, ultrasound markers of atherosclerosis and CVD risk factors and whether PAI-1 improves prediction of atherosclerosis over known risk factors in a cohort of asymptomatic adults.

METHODS

We analyzed PAI-1 and CVD risk factors and assessed carotid intima-media thickness (cIMT), distensibility (CDist) and the presence of a carotid atherosclerotic plaque and flow-mediated dilation (FMD) ultrasonographically for 2202 adults (993 men and 1,209 women, aged 30-45 years) participating in the ongoing longitudinal cohort study, The Cardiovascular Risk in Young Finns Study. High cIMT was defined as >90th percentile and/or carotid plaque and low CDist and low FMD as <20th percentile.

RESULTS

In bivariate analyses, PAI-1 correlated directly with cIMT and the risk factors: blood pressure, BMI, waist and hip circumference, alcohol use, total and LDL-cholesterol, triglycerides, glomerular filtration rate, high-sensitivity CRP and glucose (all P<0.005). PAI-1 was higher in men and increased with age. Inverse correlation was observed with CDist, HDL-cholesterol and adiponectin in both sexes, with testosterone and sex hormone binding globulin in men and with creatinine and oral contraceptive use in women (P<0.005). Independent direct associations were observed between PAI-1 and waist circumference, serum triglycerides, insulin, alcohol use and age and inverse with serum creatinine, HDL-cholesterol and adiponectin. PAI-1 did not improve estimation of high cIMT, low CDist and low FMD over conventional risk factors (P for difference in area under curve ≥ 0.37).

CONCLUSION

PAI-1 was independently associated with several known CVD risk factors, especially obesity markers, in both men and women. However, addition of PAI-1 to known risk factors did not improve cross-sectional prediction of high cIMT, low CDist and low FMD suggesting that PAI-1 is not a clinically important biomarker in early atherosclerosis.

Protective effect of curcumin on pulmonary and cardiovascular effects induced by repeated exposure to diesel exhaust particles in mice

Particulate air pollution has been associated with increased risk of cardiopulmonary diseases. However, the underlying mechanisms are not fully understood. We have previously demonstrated that single dose exposure to diesel exhaust particle (DEP) causes lung inflammation and peripheral thrombotic events. Here, we exposed mice with repeated doses of DEP (15µg/animal) every 2^nd day for 6 days (a total of 4 exposures), and measured several cardiopulmonary endpoints 48 h after the end of the treatments. Moreover, the potential protective effect of curcumin (the yellow pigment isolated from turmeric) on DEP-induced cardiopulmonary toxicity was assessed. DEP exposure increased macrophage and neutrophil numbers, tumor necrosis factor α (TNF α) in the bronchoalveolar lavage (BAL) fluid, and enhanced airway resistance to methacoline measured invasively using Flexivent. DEP also significantly increased plasma C-reactive protein (CRP) and TNF α concentrations, systolic blood pressure (SBP) as well as the pial arteriolar thrombosis. It also significantly enhanced the plasma D-dimer and plasminogen activator inhibitor-1 (PAI-1). Pretreatment with curcumin by oral gavage (45 mg/kg) 1h before exposure to DEP significantly prevented the influx of inflammatory cells and the increase of TNF α in BAL, and the increased airway resistance caused by DEP. Likewise, curcumin prevented the increase of SBP, CRP, TNF α, D-dimer and PAI-1. The thrombosis was partially but significantly mitigated. In conclusion, repeated exposure to DEP induced lung and systemic inflammation characterized by TNFα release, increased SBP, and accelerated coagulation. Our findings indicate that curcumin is a potent anti-inflammatory agent that prevents the release of TNFα and protects against the pulmonary and cardiovascular effects of DEP.

Blood biomarkers and measures of pulmonary function--a study from the Swedish twin registry

OBJECTIVE

There is great need of biomarkers for research and clinical purposes in COPD. This study explored the relationships between ten putative plasma biomarkers of COPD and physiological measures of reduced lung function.

METHODS

FEV(1), FVC, residual volume/total lung capacity (RV/TLC) and CO diffusion capacity (D(L)CO) were assessed in 357 subjects from the Swedish Twin Registry. The lung function measures were studied in relation to plasma levels of desmosines, C-reactive protein (CRP), plasminogen inhibitor activator (PAI-1) concentration and activity, tissue inhibitor of metalloproteinase (TIMP-1), clara cell protein 16 (CC16), surfactant protein D (SPD), matrix metalloproteinase 9 (MMP-9), hepatocyte growth factor (HGF) and interleukin (IL)-8.

RESULTS

After adjustments for age, sex, height, BMI and smoking, FEV(1) was significantly associated with PAI-1 activity and desmosines. RV/TLC was significantly associated with CC16, PAI-1 concentration and PAI-1 activity, and D(L)CO was significantly associated with desmosines, TIMP-1 and CRP. When the multivariate analysis was restricted to subjects with COPD (i.e., FEV(1)/FVC < 0.70), CRP and desmosines were inversely associated with lung function.

CONCLUSION

Several biomarkers were associated with lung function in this cross-sectional study. Especially CRP and desmosines could be useful markers to assess disease severity in subjects with COPD.

Local and systemic expressions of MMP-9, TIMP-1 and PAI-1 in patients undergoing surgery for clinically suspected appendicitis

BACKGROUND/AIMS

To examine, compare and correlate the expressions of matrix metalloproteinase 9 (MMP-9), tissue inhibitor of metalloproteinase 1 (TIMP-1) and plasminogen activator inhibitor type 1 (PAI-1) in appendiceal tissue and pre- and postoperative blood samples in patients undergoing surgery for clinically suspected appendicitis.

METHODS

Fifty-seven patients with complete tissue and blood samples were included and divided into groups of noninflamed appendix/lymphadenitis (n = 7), phlegmonous appendicitis (n = 30), gangrenous appendicitis (n = 11) and perforated appendicitis (n = 9). The protein expressions were assessed with ELISAs. The local expressions of MMP-9, TIMP-1 and PAI-1 were correlated with the systemic expressions at the time of surgery while the systemic individual differences between surgery and recovery were compared.

RESULTS

There was a positive correlation between tissue and plasma PAI-1 (p < 0.05). The individual differences for plasma MMP-9 and PAI-1 were statistically nonsignificant, while they were higher for TIMP-1 in patients with perforated appendicitis compared with phlegmonous (p < 0.0001) and gangrenous appendicitis (p < 0.01).

CONCLUSIONS

Plasma PAI-1 reflected the levels in appendiceal tissue at the time of surgery. Systemic TIMP-1 could have the potential of distinguishing perforated from nonperforated appendicitis.

Elevated Tumor Expression of PAI-1 and SNAI2 in Obese Esophageal Adenocarcinoma Patients and Impact on Prognosis

OBJECTIVES:

Obesity is linked to increased mortality from many cancer types, and esophageal adenocarcinoma (EAC) displays one of the strongest epidemiological associations. The aims of this study are to dissect molecular pathways linking obesity with EAC and to determine if obesity is linked to increased aggressiveness of this disease.

METHODS:

Affymetrix microarrays identified altered signaling pathways in an EAC cell line following coculture with visceral adipose tissue or isolated adipocytes from viscerally obese EAC patients (n=6). Differentially expressed genes were subsequently investigated in patient tumor biopsies by quantitative reverse transcriptase PCR and examined with respect to obesity status, tumor biology, and patient survival.

RESULTS:

Visceral adipose tissue induced expression of genes involved in epithelial mesenchymal transition (EMT), plasminogen activator inhibitor (PAI)-1, and transcription factor SNAI2, in an EAC cell line. In EAC patient tumor biopsies from obese patients, we noted elevated expression of these genes, together with reduced expression of epithelial marker E-cadherin. SNAI2 was associated with EAC prognosis.

CONCLUSIONS:

Expression of EMT genes, PAI-1 and SNAI2, was elevated in tumors of obese EAC patients, and SNAI2 was associated with poor survival. Genes deregulated in obesity and associated with prognosis may represent potential targets for treatment stratification of obese EAC patients.

Increased PAI-1 in females compared with males is protective for abdominal aortic aneurysm formation in a rodent model

The serine proteases, along with their inhibitor plasmin activator inhibitor-1 (PAI-1), have been shown to play a role in abdominal aortic aneurysm (AAA) formation. The aim of this study is to determine if PAI-1 may be a protective factor for AAA formation and partially responsible for the gender difference observed in AAAs. Male and female wild-type (WT) C57BL/6 and PAI-1(-/-) mice 8-12 wk of age underwent aortic perfusion with porcine pancreatic elastase. Animals were harvested 14 days following perfusion and analyzed for phenotype, PAI-1 protein levels, and matrix metalloproteinase (MMP)-9 and -2 activity. WT males had an average increase in aortic diameter of 80%, whereas females only increased 32% (P < 0.001). PAI-1(-/-) males increased 204% and females 161%, significantly more than their WT counterparts (P < 0.001). Western blot revealed 61% higher PAI-1 protein levels in the WT females compared with the WT males (P = 0.01). Zymography revealed higher levels of pro-MMP-2 and active MMP-2 in the PAI-1(-/-) males and females compared with their WT counterparts. PAI-1(-/-) females had significantly higher serum plasmin levels compared with WT females (P = 0.003). In conclusion, WT female mice are protected from aneurysm formation and have higher levels of PAI-1 compared with males during experimental aneurysm formation. Additionally, both male and female PAI-1(-/-) animals develop significantly larger aneurysms than WT animals, correlating with higher pro- and active MMP-2 levels. These findings suggest that PAI-1 is protective for aneurysm formation in the elastase model of AAA and plays a role in the gender differences seen in AAA formation.

PAI-1 in tissue fibrosis

Fibrosis is defined as a fibroproliferative or abnormal fibroblast activation-related disease. Deregulation of wound healing leads to hyperactivation of fibroblasts and excessive accumulation of extracellular matrix (ECM) proteins in the wound area, the pathological manifestation of fibrosis. The accumulation of excessive levels of collagen in the ECM depends on two factors: an increased rate of collagen synthesis and or decreased rate of collagen degradation by cellular proteolytic activities. The urokinase/tissue type plasminogen activator (uPA/tPA) and plasmin play significant roles in the cellular proteolytic degradation of ECM proteins and the maintenance of tissue homeostasis. The activities of uPA/tPA/plasmin and plasmin-dependent MMPs rely mostly on the activity of a potent inhibitor of uPA/tPA, plasminogen activator inhibitor-1 (PAI-1). Under normal physiologic conditions, PAI-1 controls the activities of uPA/tPA/plasmin/MMP proteolytic activities and thus maintains the tissue homeostasis. During wound healing, elevated levels of PAI-1 inhibit uPA/tPA/plasmin and plasmin-dependent MMP activities, and, thus, help expedite wound healing. In contrast to this scenario, under pathologic conditions, excessive PAI-1 contributes to excessive accumulation of collagen and other ECM protein in the wound area, and thus preserves scarring. While the level of PAI-1 is significantly elevated in fibrotic tissues, lack of PAI-1 protects different organs from fibrosis in response to injury-related profibrotic signals. Thus, PAI-1 is implicated in the pathology of fibrosis in different organs including the heart, lung, kidney, liver, and skin. Paradoxically, PAI-1 deficiency promotes spontaneous cardiac-selective fibrosis. In this review, we discuss the significance of PAI-1 in the pathogenesis of fibrosis in multiple organs.

Emerging role of serpinE2/protease nexin-1 in hemostasis and vascular biology

Serine protease inhibitors, termed serpins, are key regulators in many biologic events. Protease nexin-1 (PN-1) is a serpin that is barely detectable in plasma but found in many organs and produced by most cell types, including monocytes, platelets, and vascular cells. It has a large inhibition spectrum because it is the most efficient tissue inhibitor of thrombin but also a powerful inhibitor of plasminogen activators and plasmin. It has a high affinity for glycosaminoglycans, such as heparan sulfates, which potentiate its activity toward thrombin and target it to the pericellular space. PN-1 has been previously largely described as a crucial regulator of the proteolytic activity in nerves and of central and peripheral nervous system function. In contrast, little was known about its involvement in hemostasis and vascular biology. This article reviews recent data underlining its emerging role as a key factor in the responses of vessels to injury. Indeed, studies of PN-1-deficient mice have established important antithrombotic and antifibrinolytic properties of this serpin that have heretofore gone unrecognized. The roles of PN-1 in the areas of hemostasis and thrombosis summarized here provide insights that may allow the development of drugs and treatment strategies to prevent or limit thrombotic disorders.

Plasma plasminogen activator inhibitor-1 levels in the different phenotypes of the polycystic ovary syndrome

We aimed to evaluate plasma plasminogen activator inhibitor-1 (PAI-1) antigen levels in women with polycystic ovary syndrome (PCOS) and different levels of adiposity and PCOS phenotypes. We studied 199 women with PCOS and 50 age-matched healthy women divided in normal weight (n=100 and n=25, respectively) and overweight/obese (n=99 and n=25, respectively). Normal weight and overweight/obese patients with PCOS were further divided in patients diagnosed according to the 1990 criteria (i.e. with anovulation and hyperandrogenemia; 1990 criteria group) and in patients with the additional phenotypes introduced in 2003 (i.e. with polycystic ovaries and either anovulation or hyperandrogenemia; additional 2003 criteria group). In normal weight subjects, plasma PAI-1 levels did not differ between women with PCOS (regardless of group) and controls, or between the 1990 criteria and the additional 2003 criteria groups of PCOS. In overweight/obese subjects, plasma PAI-1 levels were higher in both the 1990 criteria and the additional 2003 criteria groups of PCOS compared with controls (p<0.001 and p=0.004, respectively), but did not differ between the 1990 criteria and the additional 2003 criteria groups of PCOS. In conclusion, plasma PAI-1 levels are elevated in overweight/obese women with PCOS but not in normal weight women with this syndrome. Plasma PAI-1 levels do not differ between the phenotypes of PCOS.

Cardiac gene expression profiling - the quest for an atrium-specific biomarker

Biomarkers are gaining increasing interest to predict risk but also to aid in diagnostics. Tissue-specific biomarkers are of utmost importance to detect diseases of respective organs. As of yet there are no atrium-specific biomarkers for risk stratification of atrial disease, such as atrial fibrillation. Bioinformatics such as mRNA microarrays can help to detect tissue-enriched and possibly tissue-specific expressed genes that can be targets for biomarkers. We describe an approach to identify genes preferably expressed in atrial cardiomyocytes compared with ventricular cardiomyocytes by RNA microarray and confirmed by quantitative real-time polymerase chain reaction. By this approach we identified several atrium-enriched genes but also ventricle-enriched genes. As expected atrial natriuretic peptide (ANP) mRNA showed higher expression in atrial cardiomyocytes while with adrenergic stimulation expression was almost as high in ventricular as in atrial cells. Brain-type natriuretic peptide (BNP), however, was not different between atrial and ventricular cells giving a possible explanation for increased levels of NT-proBNP in atrial fibrillation patients. Interesting identified candidates are serpine1 and ltbp2 as atrium-enriched genes whereas alpha-adrenergic receptor subtype 1b and S100A1 expression was significantly higher in ventricular cells. The identified genes need to be confirmed in human tissue and might ultimately be tested as potential biomarkers for atrial stress. (Neth Heart J 2010;18:610-4.).

Involvement of NADPH oxidase in up-regulation of plasminogen activator inhibitor-1 and heat shock factor-1 in mouse embryo fibroblasts induced by oxidized LDL and in apolipoprotein E-deficient mice

The present study demonstrated that oxidized LDL (oLDL) increased the generation of superoxide and hydrogen peroxide (H(2)O(2)), the abundances of NADPH oxidase (NOX)4, NOX2, p22-phox and lectin-like oLDL receptor-1 (LOX-1) in wild-type or heat shock factor-1 (HSF1)-deficient mouse embryo fibroblasts (MEF). LOX-1 antibody inhibited LDL or oLDL-induced expression of NOX components in MEF. Abundance of HSF1 or plasminogen activator inhibitor-1 (PAI-1) was increased by oLDL in wild-type, but not in HSF1-deficient MEF. Diphenyleneiodonium or siRNA for NOX or p22-phox inhibited oLDL-induced increases of HSF1, PAI-1 and H(2)O(2) in MEF. Increased NOX4, NOX2, LOX1, HSF1 and PAI-1 were detected in aortae and hearts of apolipoprotein E-knockout (apoE-KO) mice compared to controls, which were associated with increased serum cholesterol or plasma PAI-1. The results suggest that NOX is required for oLDL-induced HSF1 or PAI-1 expression in MEF, which was supported by the up-regulation of NOX, LOX-1, HSF1 and PAI-1 in apoE-KO mice.

Particulate matter-induced lung inflammation increases systemic levels of PAI-1 and activates coagulation through distinct mechanisms

Background

Exposure of human populations to ambient particulate matter (PM) air pollution significantly contributes to the mortality attributable to ischemic cardiovascular events. We reported that mice treated with intratracheally instilled PM develop a prothrombotic state that requires the release of IL-6 by alveolar macrophages. We sought to determine whether exposure of mice to PM increases the levels of PAI-1, a major regulator of thrombolysis, via a similar or distinct mechanism.

Methods and Principal Findings

Adult, male C57BL/6 and IL-6 knock out (IL-6^−/−) mice were exposed to either concentrated ambient PM less than 2.5 µm (CAPs) or filtered air 8 hours daily for 3 days or were exposed to either urban particulate matter or PBS via intratracheal instillation and examined 24 hours later. Exposure to CAPs or urban PM resulted in the IL-6 dependent activation of coagulation in the lung and systemically. PAI-1 mRNA and protein levels were higher in the lung and adipose tissue of mice treated with CAPs or PM compared with filtered air or PBS controls. The increase in PAI-1 was similar in wild-type and IL-6^−/− mice but was absent in mice treated with etanercept, a TNF-α inhibitor. Treatment with etanercept did not prevent the PM-induced tendency toward thrombus formation.

Conclusions

Mice exposed to inhaled PM exhibited a TNF-α-dependent increase in PAI-1 and an IL-6-dependent activation of coagulation. These results suggest that multiple mechanisms link PM-induced lung inflammation with the development of a prothrombotic state.