Distribution and regulation of plasminogen activator inhibitor-1 in murine adipose tissue in vivo. Induction by tumor necrosis factor-alpha and lipopolysaccharide

Overexpression of Plg-RKT protects against adipose dysfunction and dysregulation of glucose homeostasis in diet-induced obese mice

The plasminogen receptor, Plg-RKT, is a unique cell surface receptor that is broadly expressed in cells and tissues throughout the body. Plg-RKT localizes plasminogen on cell surfaces and promotes its activation to the broad-spectrum serine protease, plasmin. In this study, we show that overexpression of Plg-RKT protects mice from high fat diet (HFD)-induced adipose and metabolic dysfunction. During the first 10 weeks on the HFD, the body weights of mice that overexpressed Plg-RKT (Plg-RKT-OEX) were lower than those of control mice (CagRosaPlgRKT). After 10 weeks on the HFD, CagRosaPlgRKT and Plg-RKT-OEX mice had similar body weights. However, Plg-RKT-OEX mice showed a more metabolically favourable body composition phenotype. Plg-RKT-OEX mice also showed improved glucose tolerance and increased insulin sensitivity. We found that the improved metabolic functions of Plg-RKT-OEX mice were mechanistically associated with increased energy expenditure and activity, decreased proinflammatory adipose macrophages and decreased inflammation, elevated brown fat thermogenesis, and higher expression of adipose PPARγ and adiponectin. These findings suggest that Plg-RKT signalling promotes healthy adipose function via multiple mechanisms to defend against obesity-associated adverse metabolic phenotypes.

Tale of two systems: the intertwining duality of fibrinolysis and lipoprotein metabolism

Fibrinolysis is an enzymatic process that breaks down fibrin clots, while dyslipidemia refers to abnormal levels of lipids and lipoproteins in the blood. Both fibrinolysis and lipoprotein metabolism are critical mechanisms that regulate a myriad of functions in the body, and the imbalance of these mechanisms is linked to the development of pathologic conditions, such as thrombotic complications in atherosclerotic cardiovascular diseases. Accumulated evidence indicates the close relationship between the 2 seemingly distinct and complicated systems-fibrinolysis and lipoprotein metabolism. Observational studies in humans found that dyslipidemia, characterized by increased blood apoB-lipoprotein and decreased high-density lipoprotein, is associated with lower fibrinolytic potential. Genetic variants of some fibrinolytic regulators are associated with blood lipid levels, supporting a causal relationship between these regulators and lipoprotein metabolism. Mechanistic studies have elucidated many pathways that link the fibrinolytic system and lipoprotein metabolism. Moreover, profibrinolytic therapies improve lipid panels toward an overall cardiometabolic healthier phenotype, while some lipid-lowering treatments increase fibrinolytic potential. The complex relationship between lipoprotein and fibrinolysis warrants further research to improve our understanding of the bidirectional regulation between the mediators of fibrinolysis and lipoprotein metabolism.

Blood tissue Plasminogen Activator (tPA) of liver origin contributes to neurovascular coupling involving brain endothelial N-Methyl-D-Aspartate (NMDA) receptors

BACKGROUND

Regulation of cerebral blood flow (CBF) directly influence brain functions and dysfunctions and involves complex mechanisms, including neurovascular coupling (NVC). It was suggested that the serine protease tissue-type plasminogen activator (tPA) could control CNV induced by whisker stimulation in rodents, through its action on N-methyl-D-Aspartate receptors (NMDARs). However, the origin of tPA and the location and mechanism of its action on NMDARs in relation to CNV remained debated.

METHODS

Here, we answered these issues using tPA^Null mice, conditional deletions of either endothelial tPA (VECad-Cre^ΔtPA) or endothelial GluN1 subunit of NMDARs (VECad-Cre^ΔGluN1), parabioses between wild-type and tPA^Null mice, hydrodynamic transfection-induced deletion of liver tPA, hepatectomy and pharmacological approaches.

RESULTS

We thus demonstrate that physiological concentrations of vascular tPA, achieved by the bradykinin type 2 receptors-dependent production and release of tPA from liver endothelial cells, promote NVC, through a mechanism dependent on brain endothelial NMDARs.

CONCLUSIONS

These data highlight a new mechanism of regulation of NVC involving both endothelial tPA and NMDARs.

Liang-Ge Decoction Ameliorates Coagulation Dysfunction in Cecal Ligation and Puncture-Induced Sepsis Model Rats through Inhibiting PAD4-Dependent Neutrophil Extracellular Trap Formation

Liang-Ge (LG) decoction could ameliorate coagulation dysfunction in septic model rats. However, the mechanism of LG in treating sepsis still needs to be clarified. Our current study established a septic rat model to evaluate the effect of LG on coagulation dysfunction in septic rats first. Second, we investigated the effect of LG on NET formation in septic rats. Finally, NETs and PAD4 inhibitors were further used to clarify if LG could improve the mechanism of sepsis coagulation dysfunction by inhibiting NET formation. Our findings indicated that treatment with LG improved the survival rate, reduced inflammatory factor levels, enhanced hepatic and renal function, and reduced pathological changes in rats with sepsis. LG could also alleviate coagulation dysfunction in septic model rats. Besides, LG treatment reduced NETs formation and decreased PAD4 expression in neutrophiles. In addition, LG treatment showed a similar result in comparison to the treatment with either NET inhibitors or PAD4 inhibitors alone. In conclusion, this study confirmed that LG has therapeutic effects on septic rats. Furthermore, the improvement of coagulation dysfunction in septic rats by LG was achieved through inhibiting PAD4-mediated NET formation.

The Association of Acute Phase Proteins in Stress and Inflammation-Induced T2D

Acute phase proteins (APPs), such as plasminogen activator inhibitor-1 (PAI-1), serum amyloid A (SAA), and C-reactive protein (CRP), are elevated in type-2 diabetes (T2D) and are routinely used as biomarkers for this disease. These APPs are regulated by the peripheral mediators of stress (i.e., endogenous glucocorticoids (GCs)) and inflammation (i.e., pro-inflammatory cytokines), with both implicated in the development of insulin resistance, the main risk factor for the development of T2D. In this review we propose that APPs, PAI-1, SAA, and CRP, could be the causative rather than only a correlative link between the physiological elements of risk (stress and inflammation) and the development of insulin resistance.

Elevated plasma levels of plasminogen activator inhibitor-1 are associated with risk of future incident venous thromboembolism

BACKGROUND

Plasminogen activator inhibitor-1 (PAI-1), the main inhibitor of fibrinolysis, is frequently elevated in obesity and could potentially mediate the risk of venous thromboembolism (VTE) in obese subjects. However, whether PAI-1 is associated with VTE remains uncertain.

OBJECTIVE

To investigate the association between plasma PAI-1 levels and risk of future incident VTE and whether PAI-1 could mediate the VTE risk in obesity.

METHODS

A population-based nested case-control study, comprising 383 VTE cases and 782 age- and sex-matched controls, was derived from the Tromsø Study cohort. PAI-1 antigen levels were measured in samples collected at cohort inclusion. Logistic regression was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs) for VTE across PAI-1 tertiles.

RESULTS

The VTE risk increased dose-dependently across PAI-1 tertiles (P for trend <.001) in the age- and sex-adjusted model. The OR of VTE for the highest versus lowest tertile was 1.73 (95% CI 1.27-2.35), and risk estimates were only slightly attenuated with additional stepwise adjustment for body mass index (BMI; OR 1.59, 95% CI 1.16-2.17) and C-reactive protein (CRP; OR 1.54, 95% CI 1.13-2.11). Similar results were obtained for provoked/unprovoked events, deep vein thrombosis, and pulmonary embolism. In obese subjects (BMI of ≥30 kg/m2 vs. <25 kg/m2 ), PAI-1 mediated 14.9% (95% CI 4.1%-49.4%) of the VTE risk in analysis adjusted for age, sex, and CRP.

CONCLUSION

Our findings indicate that plasma PAI-1 is associated with increased risk of future incident VTE and has the potential to partially mediate the VTE risk in obesity.

PAI-1: A Major Player in the Vascular Dysfunction in Obstructive Sleep Apnea?

Obstructive sleep apnea is a chronic and prevalent condition that is associated with endothelial dysfunction, atherosclerosis, and imposes excess overall cardiovascular risk and mortality. Despite its high prevalence and the susceptibility of CVD patients to OSA-mediated stressors, OSA is still under-recognized and untreated in cardiovascular practice. Moreover, conventional OSA treatments have yielded either controversial or disappointing results in terms of protection against CVD, prompting the need for the identification of additional mechanisms and associated adjuvant therapies. Plasminogen activator inhibitor-1 (PAI-1), the primary inhibitor of tissue-type plasminogen activator (tPA) and urinary-type plasminogen activator (uPA), is a key regulator of fibrinolysis and cell migration. Indeed, elevated PAI-1 expression is associated with major cardiovascular adverse events that have been attributed to its antifibrinolytic activity. However, extensive evidence indicates that PAI-1 can induce endothelial dysfunction and atherosclerosis through complex interactions within the vasculature in an antifibrinolytic-independent matter. Elevated PAI-1 levels have been reported in OSA patients. However, the impact of PAI-1 on OSA-induced CVD has not been addressed to date. Here, we provide a comprehensive review on the mechanisms by which OSA and its most detrimental perturbation, intermittent hypoxia (IH), can enhance the transcription of PAI-1. We also propose causal pathways by which PAI-1 can promote atherosclerosis in OSA, thereby identifying PAI-1 as a potential therapeutic target in OSA-induced CVD.

High visceral to subcutaneous fat area ratio predicts early postoperative small bowel obstruction after surgery for colorectal cancer

PURPOSE

Risks for postoperative small bowel obstruction have been demonstrated in several reports, most of which indicated male sex was a risk factor, but with the reason remaining unknown. We tested the hypothesis that it could be because males have more visceral fat than females. This prospective observational study aims to examine risks of early postoperative small bowel obstruction (EPSBO) after colorectal cancer surgery and the association between visceral to subcutaneous fat area ratio (V/S ratio) and EPSBO.

METHODS

Four hundred and seventy-four patients who underwent colectomy for colorectal cancer in our hospital were enrolled in this study. The influence of several factors including V/S ratio on the development of EPSBO was analyzed.

RESULTS

Thirty-one of the 474 patients (6.5%) developed EPSBO. EPSBO occurred more frequently in males (p = 0.03) and cases who developed postoperative anastomotic leakage (p < 0.001) or wound infection (p = 0.02). Higher V/S ratio was strongly related to male sex (p < 0.001). Multivariate analysis revealed higher V/S ratio (OR 2.25; p = 0.049) and anastomotic leakage (OR 5.86; p < 0.001) were independent risk factors for EPSBO.

CONCLUSION

Higher V/S ratio was significantly related to EPSBO, suggesting that one of the reasons EPSBO was more likely to occur in males because they have more visceral fat than females. Preoperative identification of this risk factor could help us watch out for this potential complication.

Visceral fat-specific regulation of plasminogen activator inhibitor-1 in aged septic mice

Elevated plasma levels of plasminogen activator inhibitor-1 (PAI-1) are documented in patients with sepsis and levels positively correlate with disease severity and mortality. Our previous work demonstrated that visceral adipose tissues (VAT) are a major source of PAI-1, especially in the aged (murine endotoxemia), that circulating PAI-1 protein levels match the trajectory of PAI-1 transcript levels in VAT (clinical sepsis), and that PAI-1 in both VAT and plasma are positively associated with acute kidney injury (AKI) in septic patients. In the current study utilizing preclinical sepsis models, PAI-1 tissue distribution was examined and cellular sources, as well as mechanisms mediating PAI-1 induction in VAT, were identified. In aged mice with sepsis, PAI-1 gene expression was significantly higher in VAT than in other major organs. VAT PAI-1 gene expression correlated with PAI-1 protein levels in both VAT and plasma. Moreover, VAT and plasma levels of PAI-1 were positively associated with AKI markers, modeling our previous clinical data. Using explant cultures of VAT, we determined that PAI-1 is secreted robustly in response to recombinant transforming growth factor β (TGFβ) and tumor necrosis factor α (TNFα) treatment; however, neutralization was effective only for TNFα indicating that TGFβ is not an endogenous modulator of PAI-1. Within VAT, TNFα was localized to neutrophils and macrophages. PAI-1 protein levels were fourfold higher in stromal vascular fraction (SVF) cells compared with mature adipocytes, and among SVF cells, both immune and nonimmune compartments expressed PAI-1 in a similar fashion. PAI-1 was localized predominantly to macrophages within the immune compartment and preadipocytes and endothelial cells within the nonimmune compartment. Collectively, these results indicate that induction and secretion of PAI-1 from VAT is facilitated by a complex interaction among immune and nonimmune cells. As circulating PAI-1 contributes to AKI in sepsis, understanding PAI-1 regulation in VAT could yield novel strategies for reducing systemic consequences of PAI-1 overproduction.

Effect of sera from lupus patients on the glomerular endothelial fibrinolysis system

BACKGROUND

Dysregulation of the coagulation fibrinolysis system in resident glomerular cells is associated with the pathogenesis of lupus nephritis. However, the role of plasminogen activator inhibitor-1 (PAI-1) and tissue plasminogen activator (tPA) in resident glomerular cells remains undetermined.

METHODS

We examined the expression of PAI-1 and tPA mRNA in cultured normal human glomerular endothelial cells (GECs) treated with serum from patients with systemic lupus erythematosus (SLE) using quantitative reverse transcription polymerase chain reactions. We determined the relationship between PAI-1/tPA mRNA expression and several clinical/laboratory parameters. Serum from 16 patients (nine patients with new-onset SLE and seven patients with stable SLE) was used in the study.

RESULTS

Plasminogen activator inhibitor-1 and tPA mRNA expression was significantly higher in GECs treated with serum of patients with new-onset SLE than other groups. The PAI-1 and tPA mRNA levels were also significantly correlated in GECs treated with serum from patients with SLE. Interestingly, both PAI-1 and tPA mRNA levels in GECs were inversely correlated with serum C4 level and positively correlated with SLE disease activity.

CONCLUSIONS

These results suggest that serum from patients with SLE may activate the fibrinolysis system in glomerulus, which may be involved in the pathogenesis of lupus nephritis.

In situ Pulmonary Artery Thrombosis: A Previously Overlooked Disease

Pulmonary thromboembolism (PTE) is the third leading cause of death in cardiovascular diseases. PTE is believed to be caused by thrombi detached from deep veins of lower extremities. The thrombi travel with systemic circulation to the lung and block pulmonary arteries, leading to sudden disruption of hemodynamics and blood gas exchange. However, this concept has recently been challenged by accumulating evidence demonstrating that de novo thrombosis may be formed in pulmonary arteries without deep venous thrombosis. On the other hand, chronic thromboembolic pulmonary hypertension (CTEPH), a subtype of pulmonary hypertension, could have different pathogenesis than traditional PTE. Therefore, this article summarized and compared the risk factors, the common and specific pathogenic mechanisms underlying PTE, in situ pulmonary artery thrombosis, and CTEPH at molecular and cellular levels, and suggested the therapeutic strategies to these diseases, aiming to facilitate understanding of pathogenesis, differential diagnosis, and precision therapeutics of the three pulmonary artery thrombotic diseases.

Plasminogen activator inhibitor 1 and venous thrombosis in pancreatic cancer

Pancreatic cancer patients have a high risk of venous thromboembolism (VTE). Plasminogen activator inhibitor 1 (PAI-1) inhibits plasminogen activators and increases the risk of thrombosis. PAI-1 is expressed by pancreatic tumors and human pancreatic cell lines. However, to date, there are no studies analyzing the association of active PAI-1 and VTE in pancreatic cancer patients. We investigated the association of active PAI-1 in plasma and VTE in pancreatic cancer patients. In addition, we determined if the presence of human pancreatic tumors expressing PAI-1 impairs venous thrombus resolution in mice. Plasma levels of active PAI-1 in patients with pancreatic cancer and mice bearing human tumors were determined by enzyme-linked immunosorbent assay. We measured PAI-1 expression in 5 different human pancreatic cancer cell lines and found that PANC-1 cells expressed the highest level. PANC-1 tumors were grown in nude mice. Venous thrombosis was induced by complete ligation of the inferior vena cava (IVC). Levels of active PAI-1 were independently associated with increased risk of VTE in patients with pancreatic cancer (subdistribution hazard ratio per doubling of levels: 1.39 [95% confidence interval, 1.09-1.78], P = .007). Mice bearing PANC-1 tumors had increased levels of both active human and active mouse PAI-1 and decreased levels of plasmin activity. Importantly, mice bearing PANC-1 tumors exhibited impaired venous thrombus resolution 8 days after IVC stasis compared with nontumor controls. Our results suggest that PAI-1 contributes to VTE in pancreatic cancer.

A Serpin With a Finger in Many PAIs: PAI-1's Central Function in Thromboinflammation and Cardiovascular Disease

Plasminogen activator inhibitor 1 (PAI-1) is a member of the serine protease inhibitor (serpin) superfamily. PAI-1 is the principal inhibitor of the plasminogen activators, tissue plasminogen activator (tPA), and urokinase-type plasminogen activator (uPA). Turbulence in the levels of PAI-1 tilts the balance of the hemostatic system resulting in bleeding or thrombotic complications. Not surprisingly, there is strong evidence that documents the role of PAI-1 in cardiovascular disease. The more recent uncovering of the coalition between the hemostatic and inflammatory pathways has exposed a distinct role for PAI-1. The storm of proinflammatory cytokines liberated during inflammation, including IL-6 and TNF-α, directly influence PAI-1 synthesis and increase circulating levels of this serpin. Consequently, elevated levels of PAI-1 are commonplace during infection and are frequently associated with a hypofibrinolytic state and thrombotic complications. Elevated PAI-1 levels are also a feature of metabolic syndrome, which is defined by a cluster of abnormalities including obesity, type 2 diabetes, hypertension, and elevated triglyceride. Metabolic syndrome is in itself defined as a proinflammatory state associated with elevated levels of cytokines. In addition, insulin has a direct impact on PAI-1 synthesis bridging these pathways. This review describes the key physiological functions of PAI-1 and how these become perturbed during disease processes. We focus on the direct relationship between PAI-1 and inflammation and the repercussion in terms of an ensuing hypofibrinolytic state and thromboembolic complications. Collectively, these observations strengthen the utility of PAI-1 as a viable drug target for the treatment of various diseases.

Assessing Plasmin Generation in Health and Disease

Fibrinolysis is an important process in hemostasis responsible for dissolving the clot during wound healing. Plasmin is a central enzyme in this process via its capacity to cleave fibrin. The kinetics of plasmin generation (PG) and inhibition during fibrinolysis have been poorly understood until the recent development of assays to quantify these metrics. The assessment of plasmin kinetics allows for the identification of fibrinolytic dysfunction and better understanding of the relationships between abnormal fibrin dissolution and disease pathogenesis. Additionally, direct measurement of the inhibition of PG by antifibrinolytic medications, such as tranexamic acid, can be a useful tool to assess the risks and effectiveness of antifibrinolytic therapy in hemorrhagic diseases. This review provides an overview of available PG assays to directly measure the kinetics of plasmin formation and inhibition in human and mouse plasmas and focuses on their applications in defining the role of plasmin in diseases, including angioedema, hemophilia, rare bleeding disorders, COVID-19, or diet-induced obesity. Moreover, this review introduces the PG assay as a promising clinical and research method to monitor antifibrinolytic medications and screen for genetic or acquired fibrinolytic disorders.

Elevated postischemic tissue injury and leukocyte-endothelial adhesive interactions in mice with global deficiency in caveolin-2: role of PAI-1

Ischemia/reperfusion (I/R)-induced rapid inflammation involving activation of leukocyte-endothelial adhesive interactions and leukocyte infiltration into tissues is a major contributor to postischemic tissue injury. However, the molecular mediators involved in this pathological process are not fully known. We have previously reported that caveolin-2 (Cav-2), a protein component of plasma membrane caveolae, regulated leukocyte infiltration in mouse lung carcinoma tumors. The goal of the current study was to examine if Cav-2 plays a role in I/R injury and associated acute leukocyte-mediated inflammation. Using a mouse small intestinal I/R model, we demonstrated that I/R downregulates Cav-2 protein levels in the small bowel. Further study using Cav-2-deficient mice revealed aggravated postischemic tissue injury determined by scoring of villi length in H&E-stained tissue sections, which correlated with increased numbers of MPO-positive tissue-infiltrating leukocytes determined by IHC staining. Intravital microscopic analysis of upstream events relative to leukocyte transmigration and tissue infiltration revealed that leukocyte-endothelial cell adhesive interactions in postcapillary venules, namely leukocyte rolling and adhesion were also enhanced in Cav-2-deficient mice. Mechanistically, Cav-2 deficiency increased plasminogen activator inhibitor-1 (PAI-1) protein levels in the intestinal tissue and a pharmacological inhibition of PAI-1 had overall greater inhibitory effect on both aggravated I/R tissue injury and enhanced leukocyte-endothelial interactions in postcapillary venules in Cav-2-deficient mice. In conclusion, our data suggest that Cav-2 protein alleviates tissue injury in response to I/R by dampening PAI-1 protein levels and thereby reducing leukocyte-endothelial adhesive interactions.NEW & NOTEWORTHY The role of caveolin-2 in regulating ischemia/reperfusion (I/R) tissue injury and the mechanisms underlying its effects are unknown. This study uses caveolin-2-deficient mouse and small intestinal I/R injury models to examine the role of caveolin-2 in the leukocyte-dependent reperfusion injury. We demonstrate for the first time that caveolin-2 plays a protective role from the I/R-induced leukocyte-dependent reperfusion injury by reducing PAI-1 protein levels in intestinal tissue and leukocyte-endothelial adhesive interactions in postcapillary venules.

Effect of water-extractive components from funazushi, a fermented crucian carp, on the activity of fibrinolytic factors

BACKGROUND

Japanese fermented foods, including funazushi, have have been studied insufficiently. Related research into fermented products has led to the hope that they might have positive effects on blood circulation, including anti-thrombosis effects. The possible antithrombotic effects of funazushi on the fibrinolytic system were examined.

RESULTS

The administration of extracts from funazushi increased the activity of plasmin and tissue plasminogen activators in the fibrinolytic system but decreased the activity of plasminogen activator inhibitor type-1 (PAI-1). This decrease was positively correlated with the decreased plasma triglyceride levels. Funazushi extract directly inhibited PAI-1 activity in vitro despite alimentary enzyme digestion, although direct PAI-1 inhibition was not observed in an extract from salted crucian carp.

CONCLUSION

These results suggest that funazushi extracts are closely involved in the antithrombotic effects of the fibrinolytic system, and that they exert their effect through a reduction in PAI-1 activity. The findings also indicate that fermentation processing is necessary to achieve the antithrombotic effects of funazushi. © 2020 Society of Chemical Industry.

Uncovering the Role of p38 Family Members in Adipose Tissue Physiology

The complex functions of adipose tissue have been a focus of research interest over the past twenty years. Adipose tissue is not only the main energy storage depot, but also one of the largest endocrine organs in the body and carries out crucial metabolic functions. Moreover, brown and beige adipose depots are major sites of energy expenditure through the activation of adaptive, non-shivering thermogenesis. In recent years, numerous signaling molecules and pathways have emerged as critical regulators of adipose tissue, in both homeostasis and obesity-related disease. Among the best characterized are members of the p38 kinase family. The activity of these kinases has emerged as a key contributor to the biology of the white and brown adipose tissues, and their modulation could provide new therapeutic approaches against obesity. Here, we give an overview of the roles of the distinct p38 family members in adipose tissue, focusing on their actions in adipogenesis, thermogenic activity, and secretory function.

Isolation of Secretome with Enhanced Antifibrotic Properties from miR-214-Transfected Adipose-Derived Stem Cells

BACKGROUND

Secretome refers to the total set of molecules secreted or surface-shed by stem cells. The limitations of stem cell research have led numerous investigators to turn their attention to the use of secretome instead of stem cells. In this study, we intended to reinforce antifibrotic properties of the secretome released from adipose-derived stem cells (ASCs) transfected with miR-214.

METHODS

We generated miR-214-transfected ASCs, and extracted the secretome (miR214-secretome) from conditioned media of the transfected ASCs through a series of ultrafiltrations. Subsequently, we intravenously injected the miR-214-secretome into mice with liver fibrosis, and determined the effects of miR-214-secretome on liver fibrosis.

RESULTS

Compared with that by naïve secretome, liver fibrosis was ameliorated by intravenous infusion of miR-214-secretome into mice with liver fibrosis, which was demonstrated by significantly lower expression of fibrosis-related markers (alpha-smooth muscle actin, transforming growth factor-β, and metalloproteinases-2) in the livers as well as lower fibrotic scores in the special stained livers compared with naïve secretome. The infusion of miR-214-secretome also led to lesser local and systemic inflammation, higher expression of an antioxidant enzyme (superoxide dismutase), and higher liver proliferative and synthetic function.

CONCLUSION

MicroRNA-214 transfection stimulates ASCs to release the secretome with higher antifibrotic and anti-inflammatory properties. miR-214-secretome is thus expected to be one of the prominent ways of overcoming liver fibrosis, if further studies consistently validate its safety and efficiency.

Plasminogen activator inhibitor-1 (PAI-1) expression in endometriosis

Purpose

Deep infiltrating endometriosis (DIE) is defined as an endometriotic lesion penetrating to a depth of >5 mm and is associated with pelvic pain, but the underlying mechanisms are unclear. Our objective is to investigate whether plasminogen activator inhibitor-1 expression (PAI-1) in endometriotic tissues is increased in women with DIE.

Methods

In this blinded in vitro study, immunohistochemistry and Histoscore were used to examine the expression of PAI-1 in glandular epithelium (GECs) and stroma (SCs) in a total of 62 women: deep infiltrating uterosacral/rectovaginal endometriosis (DIE; n = 13), ovarian endometrioma (OMA; n = 14), superficial peritoneal uterosacral/cul-de-sac endometriosis (SUP; n = 23), uterine (eutopic) endometrium from women with endometriosis (UE; n = 6), and non-endometriosis eutopic endometrium (UC; n = 6). The following patient characteristics were also collected: age, American Fertility Society stage, hormonal suppression, phase of menstrual cycle, dysmenorrhea score and deep dyspareunia score.

Results

PAI-1 expression in GECs and SCs of the DIE group was significantly higher than that of SUP group (p = 0.01, p = 0.01, respectively) and UE group (p = 0.03, p = 0.04, respectively). Interestingly, increased PAI-1 expression in GECs and SCs was also significantly correlated with increased dysmenorrhea (r = 0.38, p = 0.01; r = 0.34, p = 0.02, respectively).

Conclusions

We found higher expression of PAI-1 in DIE, and an association between PAI-1 and worse dysmenorrhea.

Adipokines demonstrate the interacting influence of central obesity with other cardiometabolic risk factors of metabolic syndrome in Hong Kong Chinese adults

OBJECTIVE

Metabolic syndrome (MetS) or prediabetes is a complex disorder that is defined by a clustering of cardiometabolic risk factors, including obesity, hypertriglyceridemia, reduced high-density lipoprotein (HDL) cholesterol, hypertension, and insulin resistance. Among cardiometabolic risk factors, central obesity plays a key role in the development of MetS through alterations in the secretion of adipokines and interacts with other MetS risk factors to unfavorably influence overall cardiometabolic risk. Obesity has grasped epidemic proportions in Asia, which has the highest number of people with diabetes in the world. But, the importance of central obesity in the clustering of all four MetS risk factors or vice versa in predicting severity of MetS has not yet been investigated in Asian population. Therefore, the present study examined the influence of central obesity on circulating levels of adipokines through its interaction with the clustering of cardiometabolic risk factors of MetS including hyperglycemia, hypertriglyceridemia, dyslipidemia and hypertension in Hong Kong Chinese adults.

SUBJECTS

Blood samples from 83 Hong Kong Chinese adults, who were previously screened for MetS according to the guideline of the United States National Cholesterol Education Program Expert Panel Adult Treatment Panel III criteria were selected. Insulin and adipokines, including visfatin, chemerin, plasminogen activator inhibitor-1 (PAI-1), resistin, C-C motif chemokine ligand 2 (CCL-2), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), tumour necrosis factor-α (TNF-α), leptin and adiponectin were assessed.

RESULTS

The interacting effect of central obesity with all of the other four MetS risk factors increased the proinflammatory status of adipokines (TNF-α, leptin) and decreased the anti-inflammatory status of adipokine (adiponectin).

CONCLUSION

Our results indicate that the inflammatory status of MetS may be more severe in the presence of central obesity. Adipokines, as biomarkers for pathophysiological changes, may help to improve early patient identification and to predict MetS-associated morbidity and mortality.

Regulation of plasminogen activation on cell surfaces and fibrin

The fibrinolytic system dissolves fibrin and maintains vascular patency. Recent advances in imaging analyses allowed visualization of the spatiotemporal regulatory mechanism of fibrinolysis, as well as its regulation by other plasma hemostasis cofactors. Vascular endothelial cells (VECs) retain tissue-type plasminogen activator (tPA) after secretion and maintain high plasminogen (plg) activation potential on their surfaces. As in plasma, the serpin, plasminogen activator inhibitor type 1 (PAI-1), regulates fibrinolytic potential via inhibition of the VEC surface-bound plg activator, tPA. Once fibrin is formed, plg activation by tPA is initiated and effectively amplified on the surface of fibrin, and fibrin is rapidly degraded. The specific binding of plg and tPA to lytic edges of partly degraded fibrin via newly generated C-terminal lysine residues, which amplifies fibrin digestion, is a central aspect of this pathophysiological mechanism. Thrombomodulin (TM) plays a role in the attenuation of plg binding on fibrin and the associated fibrinolysis, which is reversed by a carboxypeptidase B inhibitor. This suggests that the plasma procarboxypeptidase B, thrombin-activatable fibrinolysis inhibitor (TAFI), which is activated by thrombin bound to TM on VECs, is a critical aspect of the regulation of plg activation on VECs and subsequent fibrinolysis. Platelets also contain PAI-1, TAFI, TM, and the fibrin cross-linking enzyme, factor (F) XIIIa, and either secrete or expose these agents upon activation in order to regulate fibrinolysis. In this review, the native machinery of plg activation and fibrinolysis, as well as their spatiotemporal regulatory mechanisms, as revealed by imaging analyses, are discussed.

Mechanical Activation of Adipose Tissue and Derived Mesenchymal Stem Cells: Novel Anti-Inflammatory Properties

The adipose tissue is a source of inflammatory proteins, such as TNF, IL-6, and CXCL8. Most of their production occurs in macrophages that act as scavengers of dying adipocytes. The application of an orbital mechanical force for 6-10 min at 97 g to the adipose tissue, lipoaspirated and treated according to Coleman procedures, abolishes the expression of TNF-α and stimulates the expression of the anti-inflammatory protein TNF-stimulated gene-6 (TSG-6). This protein had protective and anti-inflammatory effects when applied to animal models of rheumatic diseases. We examined biopsy, lipoaspirate, and mechanically activated fat and observed that in addition to the increased TSG-6, Sox2, Nanog, and Oct4 were also strongly augmented by mechanical activation, suggesting an effect on stromal cell stemness. Human adipose tissue-derived mesenchymal stem cells (hADSCs), produced from activated fat, grow and differentiate normally with proper cell surface markers and chromosomal integrity, but their anti-inflammatory action is far superior compared to those mesenchymal stem cells (MSCs) obtained from lipoaspirate. The expression and release of inflammatory cytokines from THP-1 cells was totally abolished in mechanically activated adipose tissue-derived hADSCs. In conclusion, we report that the orbital shaking of adipose tissue enhances its anti-inflammatory properties, and derived MSCs maintain such enhanced activity.

The study of markers of endothelial dysfunction in metabolic syndrome

BACKGROUND

Metabolic syndrome (MetS) consists of a constellation of metabolic abnormalities that confer increased risk of cardiovascular disease (CVD) and diabetes mellitus (DM). Endothelial dysfunction is one of the key components of MetS which is caused by imbalance between vasodilatory substances like nitric oxide (NO) and vaso-constrictive substances like endothelin and prothrombotic factors like plasminogen activator inhibitor-1 (PAI-1).

OBJECTIVE

To study the markers of endothelial dysfunction (NO and endothelin) and prothrombotic markers (PAI-1) among the study subjects.

MATERIALS AND METHODS

We enrolled 50 diagnosed cases of MetS as per International Diabetes Federation (IDF) criteria and 50 healthy volunteers as controls. Clinical evaluation included anthropometric, routine biochemical, hematological, serum insulin, NO, endothelin and PAI-1 measurements.

RESULTS

Subjects with MetS had higher insulin, endothelin and PAI-1 levels and low NO levels as compared to controls and the difference was found to be significant. The serum insulin levels were positively correlated with PAI-1 and endothelin, and negatively correlated with NO.

CONCLUSION

Endothelial functional status as reflected by decreased NO and increased serum endothelin levels along with insulin resistance is seen in MetS. Moreover, higher serum level of PAI-1 also tilts towards a more prothrombotic milieu in the vascular endothelium. Hence endothelial dysfunction and prothrombotic markers may be used to guide for early diagnosis of cardiovascular disease and type 2 diabetes in patients with MetS.

Colchicine to decrease NLRP3-activated inflammation and improve obesity-related metabolic dysregulation

Obesity is a major risk-factor for the development of insulin resistance, type 2 diabetes, and cardiovascular disease. Circulating molecules associated with obesity, such as saturated fatty acids and cholesterol crystals, stimulate the innate immune system to incite a chronic inflammatory state. Studies in mouse models suggest that suppressing the obesity-induced chronic inflammatory state may prevent or reverse obesity-associated metabolic dysregulation. Human studies, however, have been far less positive, possibly because targeted interventions were too far downstream of the inciting inflammatory events. Recently, it has been shown that, within adipose tissue macrophages, assembly of a multi-protein member of the innate immune system, the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, is essential for the induction of this inflammatory state. Microtubules enable the necessary spatial arrangement of the components of the NLRP3 inflammasome in the cell, leading to its activation and propagation of the inflammatory cascade. Colchicine, a medication classically used for gout, mediates its anti-inflammatory effect by inhibiting tubulin polymerization, and has been shown to attenuate macrophage NLRP3 inflammasome arrangement and activation in vitro and in vivo. Given these findings, we hypothesize that, in at-risk individuals (those with obesity-induced inflammation and metabolic dysregulation), long-term colchicine use will lead to suppression of inflammation and thus cause improvements in insulin sensitivity and other obesity-related metabolic impairments.

Increasing body condition score is positively associated interleukin-6 and monocyte chemoattractant protein-1 in Labrador retrievers

The accumulation of excess body fat is a growing problem in dogs as well as people. Contrary to prior understanding of adipose tissue, fat is now considered to be an active endocrine organ that promotes a chronic low-grade inflammatory state often characterized by an increase in pro-inflammatory cytokines and chemokines. These have been implicated in several obesity-related disorders such as insulin resistance, cardiovascular disease, and neoplasia. The purpose of this study was to characterize fasting plasma cytokine concentrations in ninety-two healthy client-owned Labrador retriever dogs of various ages and body condition scores. The dogs were grouped according to body condition score (BCS) into three categories, lean, overweight and obese. The following cytokines and chemokines were evaluated; tumor necrosis factor-alpha, interleukin-2, interleukin-6, interleukin-8, and monocyte chemotactic protein-1 (TNF-α, IL-2, IL-6, IL-8, MCP-1). Our results indicated that fasting plasma IL-6 and MCP-1 concentrations are associated with increasing BCS. This data suggest that certain markers of inflammation increase with increasing body condition score, and that dogs, similar to humans, may be fostering a chronic inflammatory state due to obesity.

Lipopolysaccharide preconditioning of adipose-derived stem cells improves liver-regenerating activity of the secretome

Introduction

Growing recognition of paracrine mechanisms in stem cell plasticity has resulted in considerable interest in stem cell-derived secretome. The aim of this study was to investigate the effects of lipopolysaccharide (LPS) preconditioning on the composition and hepatic regenerative activity of adipose-derived stem cell (ASC) secretome.

Methods

Conditioned medium (CM) and LPS-CM were obtained after culturing human ASCs without or with low-dose LPS (0.5 ng/mL) for 24 hours. Untreated and thioacetamide-treated mouse AML12 hepatocytes were incubated for 24 hours with the control medium, LPS (0.5 ng/mL), CM, and LPS-CM and then cell viabilities were compared. CM and LPS-CM were also intravenously administered to partially hepatectomized mice, and their effects on liver regeneration were assessed by using liver weight measurements, immunohistochemistry, and Western blotting.

Results

In the in vitro experiments, LPS preconditioning of ASCs enhanced the mRNA expression levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), hepatocyte growth factor, and vascular endothelial growth factor, which evoke inflammatory response or liver regeneration. LPS-CM significantly promoted thioacetamide-damaged AML12 cell viability compared with CM-incubated cells and the control cells (77%, 69%, and 65% P <0.05). In the in vivo experiment, LPS-CM infusion into the partially hepatectomized mice significantly reduced serum IL-6 and TNF-α levels compared with the other groups (P <0.05) on days 1 and 2 after partial hepatectomy. Moreover, LPS-CM infusion enhanced liver regeneration (based on the liver weight changes at day 7 after partial hepatectomy, 3.73% versus 3.22% in the CM group; P <0.05) and significantly reduced the elevated serum levels of aspartate transaminase and alanine transaminase (at day 1, P <0.05).

Conclusions

Our results suggest that LPS preconditioning effectively stimulates ASCs to produce the secretome beneficial to hepatic regeneration. Thus, optimizing ASC secretome profile by LPS preconditioning could be a promising approach to treat liver diseases by using stem cells.

Imbalance between protective (adiponectin) and prothrombotic (Plasminogen Activator Inhibitor-1) adipokines in metabolic syndrome

AIMS

The metabolic syndrome (MS) consists of a constellation of metabolic abnormalities that confer increased risk of cardiovascular disease (CVD) and diabetes mellitus (DM). Visceral adipose tissue actively produces a variety of adipokines that interact in various obesity related disorders such as metabolic syndrome, diabetes mellitus and heart diseases. Adiponectin has protective role in the vascular physiology while Plasminogen Activator Inhibitor-1 (PAI-1) has a prothrombotic and consequent deleterious effect on the endothelium. We attempted to assess the putative imbalance if any between these two mediators in subjects with metabolic syndrome in the Indian context.

MATERIALS AND METHODS

We enrolled 50 diagnosed case of metabolic syndrome as per International Diabetes Federation (IDF) criteria and 50 healthy volunteers as control. Clinical evaluation included anthropometric, routine biochemical analysis as well as adiponectin and PAI-1 measurement.

RESULT

Subject with MS had significantly lower adiponectin (9.8±1.0 vs 16±1.1 μg/ml) and higher PAI-1 (232±87 vs 185±96 ng/ml). A statistically significant correlation was observed between adiponectin and HDL levels (r=0.388, p=0.005).

CONCLUSION

Subjects with MS have lower adiponectin and higher PAI-1 levels as compared to controls. The subsequent tilt toward a more prothrombotic and pro inflammatory milieu in the vascular endothelium may be pathognomonic of metabolic syndrome. This understanding of the still undiscovered subtle vascular alterations may help in the better management of obesity and MS.

Vaspin (serpinA12) in obesity, insulin resistance, and inflammation

While genome-wide association studies as well as candidate gene studies have revealed a great deal of insight into the contribution of genetics to obesity development and susceptibility, advances in adipose tissue research have substantially changed the understanding of adipose tissue function. Its perception has changed from passive lipid storage tissue to active endocrine organ regulating and modulating whole-body energy homeostasis and metabolism and inflammatory and immune responses by secreting a multitude of bioactive molecules, termed adipokines. The expression of human vaspin (serpinA12) is positively correlated to body mass index and insulin sensitivity and increases glucose tolerance in vivo, suggesting a compensatory role in response to diminished insulin signaling in obesity. Recently, considerable insight has been gained into vaspin structure, function, and specific target tissue-dependent effects, and several lines of evidence suggest vaspin as a promising candidate for drug development for the treatment of obesity-related insulin resistance and inflammation. These will be summarized in this review with a focus on molecular mechanisms and pathways.

Mechanisms of thrombosis in obesity

PURPOSE OF REVIEW

Obesity has become a worldwide epidemic that is driving increased morbidity and mortality from thrombotic disorders such as myocardial infarction, stroke, and venous thromboembolism. Effective prevention and treatment of thrombosis in obese patients is limited by an incomplete understanding of the underlying prothrombotic mechanisms and by uncertainties about risks, benefits, and dosing of anticoagulant drugs in this patient population.

RECENT FINDINGS

This review summarizes our current understanding of established and emerging mechanisms contributing to the obesity-induced prothrombotic state. The mechanistic impact of chronic inflammation and impaired fibrinolysis in mediating obesity-associated thrombosis is highlighted. Recent data demonstrating the aberrant expression of adipokines and microRNAs, which appear to function as key modulators of proinflammatory and prothrombotic pathways in obesity, are also reviewed. Finally, some challenges and new approaches to the prevention and management of thrombotic disorders in obese and overweight patients are discussed.

SUMMARY

Obesity-driven chronic inflammation and impaired fibrinolysis appear to be major effector mechanisms of thrombosis in obesity. The proinflammatory and hypofibrinolytic effects of obesity may be exacerbated by dysregulated expression and secretion of adipokines and microRNAs, which further increase the risk of thrombosis and suggest new potential targets for therapy.

Obesity in haemophilia patients: effect on bleeding frequency, clotting factor concentrate usage, and haemostatic and fibrinolytic parameters

The prevalence of obesity in patients with haemophilia (PWH) is increasing. We investigated the effect of obesity on bleeding frequency and clotting factor concentrate (CFC) usage in PWH and assessed whether prothrombotic changes observed in obesity differ between controls and PWH. Number of bleeds and CFC usage were compared between obese (N = 51) and non-obese (N = 46) haemophilia A patients. Markers of haemostasis and fibrinolysis were compared between PWH, and gender-, age- and body mass index (BMI)-matched non-haemophilic controls (N = 91). Median number of bleeds/patient-month was comparable between obese and non-obese patients with severe haemophilia (P = 0.791). Obese patients with severe haemophilia used 1.4 times more CFC/patient-month than non-obese patients (P = 0.036). When adjusting for weight this difference disappeared (P = 0.451). von Willebrand factor plasma concentration (VWF:Ag), factor VIII activity and endogenous thrombin potential were higher in obese than in non-obese controls. Obesity did not influence these markers in PWH. Plasminogen activator inhibitor type 1 levels were higher in obese vs. non-obese PWH (P < 0.001), whereas levels were comparable between PWH and controls (P = 0.912). Plasmin-α2-antiplasmin complex (PAP) levels appeared to be lower in obese vs. non-obese subjects, both within controls (P = 0.011) and PWH (P = 0.008). However, in PWH, PAP levels were higher than in controls (P < 0.001). Obesity is associated with an increase in net CFC usage in PWH, but has no effect on bleeding frequency. In addition, obesity attenuates hyperfibrinolysis in PWH. Future research investigating whether obese PWH need CFC treatment dosed on weight or whether a lower dosage would suffice to prevent and treat bleedings is needed.

Plasma clot lysis time and its association with cardiovascular risk factors in black Africans

Studies in populations of European descent show longer plasma clot lysis times (CLT) in patients with cardiovascular disease (CVD) than in controls. No data are available on the association between CVD risk factors and fibrinolytic potential in black Africans, a group undergoing rapid urbanisation with increased CVD prevalence. We investigated associations between known CVD risk factors and CLT in black Africans and whether CLTs differ between rural and urban participants in light of differences in CVD risk.

Data from 1000 rural and 1000 urban apparently healthy black South Africans (35–60 years) were cross-sectionally analysed.

Increased PAI-1_act, BMI, HbA1c, triglycerides, the metabolic syndrome, fibrinogen concentration, CRP, female sex and positive HIV status were associated with increased CLTs, while habitual alcohol consumption associated with decreased CLT. No differences in CLT were found between age and smoking categories, contraceptive use or hyper- and normotensive participants. Urban women had longer CLT than rural women while no differences were observed for men.

CLT was associated with many known CVD risk factors in black Africans. Differences were however observed, compared to data from populations of European descent available in the literature, suggesting possible ethnic differences. The effect of urbanisation on CLT is influenced by traditional CVD risk factors and their prevalence in urban and rural communities.

Stimulated in vivo synthesis of plasminogen activator inhibitor-1 in human adipose tissue

Plasminogen activator inhibitor type-1 (PAI-1) is one of the most important inhibitors of endogenous fibrinolysis. Adipose tissue is a suggested source of the elevated plasma levels of PAI-1 in obesity. The relation between PAI-1 and inflammation is of particular interest, but current knowledge regarding regulation of PAI-1 in adipose tissue is mainly based on animal studies or ex vivo experiments on human cultured adipocytes. So far, no study has described stimulated gene expression and protein synthesis of PAI-1 in vivo in human adipose tissue. We used open heart surgery as a model of acute systemic inflammation. Twenty-two male patients underwent blood sampling and omental and subcutaneous adipose tissue biopsies for gene expression studies before and after surgery. Expression and localisation of PAI-1 antigen was evaluated by immunohistochemistry. After surgery gene expression of PAI-1 increased 27-fold in omental adipose tissue and three-fold in subcutaneous adipose tissue, but no differences were found in tissue-type plasminogen activator (t-PA) mRNA. PAI-1 antigen was localised within endothelial cells and in the adipose tissue interstitium close to vessels. The upregulated gene expression and protein synthesis in adipose tissue was followed by increased concentrations of PAI-1 antigen in plasma. In conclusion, we present for the first time that an acute systemic inflammation in humans increased gene expression and protein synthesis of PAI-1 in adipose tissue and that this increase was most prominent in omental adipose tissue. PAI-1 synthesis in adipose tissue due to acute systemic inflammation may be a link between inflammation and impaired endogenous fibrinolysis.

PAI-1, progress in understanding the clinical problem and its aetiology

Plasminogen activator inhibitor-1 (PAI-1, also known as SERPINE1) is a member of the serine protease inhibitor (SERPIN) superfamily and is the primary physiological regulator of urokinase-type plasminogen activator (uPA) and tissue-type plasminogen activator (tPA) activity. Although the principal function of PAI-1 is the inhibition of fibrinolysis, PAI-1 possesses pleiotropic functions besides haemostasis. In the quarter century since its discovery, a number of studies have focused on improving our understanding of PAI-1 functions in vivo and in vitro. The use of Serpine1-deficient mice has particularly enhanced our understanding of the functions of PAI-1 in various physiological and pathophysiological conditions. In this review, the results of recent studies on PAI-1 and its role in clinical conditions are discussed.

Pentoxifylline Lowers Plasminogen Activator Inhibitor 1 Levels in Obese Individuals: A Pilot Study

Plasminogen activator inhibitor 1 (PAI-1), the primary inhibitor of fibrinolysis and C-reactive protein (CRP), is a predictor of myocardial infarction. Both are upregulated by tumor necrosis factor-alpha (TNF-α) within the obese population. This pilot study tested the hypothesis that TNF-α blockade with pentoxifylline lowers PAI-1 and high-sensitivity CRP (hsCRP) in obese individuals. Twenty participants were treated with pentoxifylline for 8 weeks. A proportional odds model was used to compare the change in PAI-1 and CRP in the pentoxifylline and placebo groups. Plasminogen activator inhibitor 1, but not hsCRP levels, decreased over the 8-week period of the study ( P = .025 and P = NS). There was significant dropout of participants due to drug tolerability. These findings suggest that these markers of cardiovascular risk are differentially regulated in obesity and that PAI-1 levels can be reduced by pentoxifylline in this population.

Tissue factor-protease-activated receptor 2 signaling promotes diet-induced obesity and adipose inflammation

Tissue factor (TF), the initiator of the coagulation cascade, mediates coagulation factor VIIa-dependent activation of protease activated receptor-2 (PAR2). Here we delineate an unexpected role for coagulation signaling in obesity and its complications. Mice lacking PAR2 (F2rl1) or the cytoplasmic domain of TF (F3) are protected from high fat diet (HFD) induced weight gain and insulin resistance. In hematopoietic cells, genetic deletion of TF-PAR2 signaling reduces adipose tissue macrophage inflammation and specific pharmacological inhibition of macrophage TF signaling rapidly ameliorates insulin resistance. In contrast, non-hematopoietic cell TF-VIIa-PAR2 signaling specifically promotes obesity. Mechanistically, adipocyte TF cytoplasmic domain dependent VIIa signaling suppresses Akt phosphorylation with concordant adverse transcriptional changes of key regulators of obesity and metabolism. Pharmacological blockade of adipocyte TF in vivo reverses these effects of TF-VIIa signaling and rapidly improves energy expenditure. Thus, TF signaling is a potential therapeutic target to improve impaired metabolism and insulin resistance in obesity.

Effect of dibutyryl cyclic adenosine monophosphate on the gene expression of plasminogen activator inhibitor-1 and tissue factor in adipocytes

INTRODUCTION

Hypertrophic adipocytes in obese states express the elevated levels of plasminogen activator inhibitor-1 (PAI-1) and tissue factor (TF). An increase in the intracellular concentration of cyclic adenosine monophosphate (cAMP) promotes triglyceride hydrolysis and may improve dysregulation of adipocyte metabolism. Here, we investigate the effect of dibutyryl-cAMP (a phosphodiesterase-resistant analog of cAMP) on the gene expression of PAI-1 and TF in adipocytes.

MATERIALS AND METHODS

Differentiated 3T3-L1 adipocytes were treated with dibutyryl-cAMP and agents that would be expected to elevate intracellular cAMP, including cilostazol (a phosphodiesterase inhibitor with anti-platelet and vasodilatory properties), isoproterenol (a beta adrenergic agonist) and forskolin (an adenylyl cyclase activator). The levels of PAI-1 and TF mRNAs were measured using real-time quantitative reverse transcription-PCR.

RESULTS AND CONCLUSIONS

The treatment of adipocytes with dibutyryl-cAMP resulted in the inhibition of both lipid accumulation and TF gene expression. However, PAI-1 gene expression was slightly but significantly increased by dibutyryl-cAMP. On the other hand, cilostazol inhibited the expression of PAI-1 without affecting lipid accumulation. When the adipocytes were treated with cilostazol in combination with isoproterenol or forskolin, the inhibitory effect of cilostazol on PAI-1 gene expression was counteracted, thus suggesting that inhibition by cilostazol may not be the result of intracellular cAMP accumulation by phosphodiesterase inhibition. These results suggest the implication of cAMP in regulation of the gene expression of TF and PAI-1 in adipocytes. Our findings will serve as a useful basis for further research in therapy for obesity-associated thrombosis.

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.

Triglyceride concentration and waist circumference influence alcohol-related plasminogen activator inhibitor-1 activity increase in black South Africans

We investigated the association between alcohol consumption and plasminogen activator inhibitor-1 activity (PAI-1act) and fibrinogen concentration in a black South African population presenting with lower PAI-1act and higher fibrinogen than what is typically observed in white populations. We, furthermore, wanted to investigate the effect of urbanization, sex, central obesity, increased triglycerides, 4G/5G polymorphism (PAI-1 only) and BMI on the association of alcohol with PAI-1act and fibrinogen. Data from 2010 apparently healthy, randomly collected black South African volunteers from the Prospective Urban and Rural Epidemiological (PURE) study were cross-sectionally analyzed. Alcohol consumption was recorded using quantitative food frequency questionnaires and fasting blood samples were collected for biochemical analysis including PAI-1act and fibrinogen. Heavy alcohol consumption is associated with significantly increased PAI-1act, in the total population as well as in the women separately, and tended to be so in men. This alcohol-related PAI-1act increase was observed in volunteers with increased triglycerides and central obesity but not in volunteers with normal levels and waist circumference. Urbanization, the 4G/5G polymorphism and BMI did not affect the association of alcohol with PAI-1act. Moderate alcohol consumption is associated with decreased fibrinogen concentration. Sex and level of urbanization did not affect the association of alcohol with fibrinogen. Fibrinogen decreased in normal and overweight volunteers but not in obese and centrally obese volunteers following moderate alcohol consumption. Triglyceride levels and waist circumference influence alcohol-related PAI-1act increase potentially through modulating adipocyte and triglyceride-induced PAI-1 production. Obesity prevented alcohol-related fibrinogen decrease possibly by counteracting the anti-inflammatory effect of moderate alcohol consumption.

Oxidized LDL and lysophosphatidylcholine stimulate plasminogen activator inhibitor-1 expression through reactive oxygen species generation and ERK1/2 activation in 3T3-L1 adipocytes

Plasminogen activator inhibitor-1 (PAI-1) is secreted from adipose tissue and is considered to be a risk factor for both atherosclerosis and insulin resistance. Here we report for the first time that PAI-1 expression is enhanced by oxidized low-density lipoprotein (OxLDL) and its lipid component lysophosphatidylcholine (LPC) in mouse 3T3-L1 adipocytes. In fully differentiated 3T3-L1 cells, OxLDL treatment increased the mRNA expression and protein secretion of PAI-1 in a dose- and time-dependent manner, whereas native LDL had no effect. The addition of an anti-CD36 antibody suppressed OxLDL-stimulated PAI-1 expression by 50%, suggesting that adipose-derived CD36 contributes to roughly half of the PAI-1 expression stimulated by OxLDL. In addition, pharmacological experiments showed that the OxLDL-stimulated enhancement in PAI-1 expression was mediated through the generation of reactive oxygen species (ROS) and phosphorylation of extracellular signal-regulated kinase 1/2. Furthermore, LPC, a major lipid component of OxLDL, was responsible for the enhanced expression of PAI-1 as phospholipase A(2)-treated acetyl LDL, which generates LPC, strongly stimulated PAI-1 expression, whereas acetyl LDL itself had no such activity. These data demonstrate that the uptake of OxLDL and, in particular, its lipid component LPC into adipocytes triggers aberrant ROS-mediated PAI-1 expression, which may be involved in the pathogenesis of metabolic syndrome.