Thrombin induces the expression of oncostatin M via AP-1 activation in human macrophages: a link between coagulation and inflammation

The Role of Myeloid Cells in Thromboinflammatory Disease

Inflammation contributes to the development of thrombosis, but the mechanistic basis for this association remains poorly understood. Innate immune responses and coagulation pathways are activated in parallel following infection or injury, and represent an important host defense mechanism to limit pathogen spread in the bloodstream. However, dysregulated proinflammatory activity is implicated in the progression of venous thromboembolism and arterial thrombosis. In this review, we focus on the role of myeloid cells in propagating thromboinflammation in acute inflammatory conditions, such as sepsis and coronavirus disease 2019 (COVID-19), and chronic inflammatory conditions, such as obesity, atherosclerosis, and inflammatory bowel disease. Myeloid cells are considered key drivers of thromboinflammation via upregulated tissue factor activity, formation of neutrophil extracellular traps (NETs), contact pathway activation, and aberrant coagulation factor-mediated protease-activated receptor (PAR) signaling. We discuss how strategies to target the intersection between myeloid cell-mediated inflammation and activation of blood coagulation represent an exciting new approach to combat immunothrombosis. Specifically, repurposed anti-inflammatory drugs, immunometabolic regulators, and NETosis inhibitors present opportunities that have the potential to dampen immunothrombotic activity without interfering with hemostasis. Such therapies could have far-reaching benefits for patient care across many thromboinflammatory conditions.

The Complex Role of Thrombin in Cancer and Metastasis: Focus on Interactions with the Immune System

Thrombin, a pleiotropic enzyme involved in coagulation, plays a crucial role in both procoagulant and anticoagulant pathways. Thrombin converts fibrinogen into fibrin, initiates platelet activation, and promotes clot formation. Thrombin also activates anticoagulant pathways, indirectly inhibiting factors involved in coagulation. Tissue factor triggers thrombin generation, and the overexpression of thrombin in various cancers suggests that it is involved in tumor growth, angiogenesis, and metastasis. Increased thrombin generation has been observed in cancer patients, especially those with metastases. Thrombin exerts its effects through protease-activated receptors (PARs), particularly PAR-1 and PAR-2, which are involved in cancer progression, angiogenesis, and immunological responses. Thrombin-mediated signaling promotes angiogenesis by activating endothelial cells and platelets, thereby releasing proangiogenic factors. These functions of thrombin are well recognized and have been widely described. However, in recent years, intriguing new findings concerning the association between thrombin activity and cancer development have come to light, which justifies a review of this research. In particular, there is evidence that thrombin-mediated events interact with the immune system, and may regulate its response to tumor growth. It is also worth reevaluating the impact of thrombin on thrombocytes in conjunction with its multifaceted influence on tumor progression. Understanding the role of thrombin/PAR-mediated signaling in cancer and immunological responses is crucial, particularly in the context of developing immunotherapies. In this systematic review, we focus on the impact of the thrombin-related immune system response on cancer progression.

Role of oncostatin-M in ECM remodeling and plaque vulnerability

Atherosclerosis is a multifactorial inflammatory disease characterized by the development of plaque formation leading to occlusion of the vessel and hypoxia of the tissue supplied by the vessel. Chronic inflammation and altered collagen expression render stable plaque to unstable and increase plaque vulnerability. Thinned and weakened fibrous cap results in plaque rupture and formation of thrombosis and emboli formation leading to acute ischemic events such as stroke and myocardial infarction. Inflammatory mediators including TREM-1, TLRs, MMPs, and immune cells play a critical role in plaque vulnerability. Among the other inflammatory mediators, oncostatin-M (OSM), a pro-inflammatory cytokine, play an important role in the development and progression of atherosclerosis, however, the role of OSM in plaque vulnerability and extracellular matrix remodeling (ECM) is not well understood and studied. Since ECM remodeling plays an important role in atherosclerosis and plaque vulnerability, a detailed investigation on the role of OSM in ECM remodeling and plaque vulnerability is critical. This is important because the role of OSM has been discussed in the context of proliferation of vascular smooth muscle cells and regulation of cytokine expression but the role of OSM is scarcely discussed in relation to ECM remodeling and plaque vulnerability. This review focuses on critically discussing the role of OSM in ECM remodeling and plaque vulnerability.

Enoxaparin attenuates pyrrolizidine alkaloids-induced hepatic sinusoidal obstruction syndrome by inhibiting oncostatin M expression

BACKGROUND AND AIMS

The definitive treatment for pyrrolizidine alkaloids (PAs)-induced hepatic sinusoidal obstruction syndrome (HSOS) is not available. The effectiveness of anticoagulation therapy remains controversial. The efficacy of low molecular weight heparin (LMWH) should be investigated in patients and animal models, and the underlying mechanism should be explored.

METHODS

The prognosis of patients with PAs-HSOS who received anticoagulation therapy was retrospectively analysed. The effect of enoxaparin on the liver injury was determined in animal models of monocrotaline (MCT)-induced HSOS was determined, and the underlying mechanism was investigated using a murine model.

RESULTS

The cumulative survival rate of patients with PAs-induced HSOS was 60.00% and 90.90% in the non-anticoagulation group and anticoagulation group. Enoxaparin attenuated liver injury effectively in a rat model of MCT-induced HSOS. Additionally, the improvement of severe liver injury was observed in MCT-treated mice after the administration of enoxaparin (40 mg/kg). The alleviation of liver injury was observed in mice with hepatocyte-specific deletion of oncostatin M (Osm^△Hep ). In MCT-treated mice administrated with enoxaparin, no significant differences in liver injury were observed between Osm^△Hep mice and Osm^flox/flox mice. Additionally, adenovirus-mediated overexpression of Osm resulted in severe liver injury in MCT-induced mice after the administration of enoxaparin.

CONCLUSIONS

LMWH attenuated severe liver injury in patients with PAs-Induced HSOS and animal models of MCT-induced HSOS, which provides a rationale for the application of anticoagulation therapy.

P2Y12 Inhibition Suppresses Proinflammatory Platelet-Monocyte Interactions

BACKGROUND

 Monocyte-platelet aggregates (MPAs) represent the crossroads between thrombosis and inflammation, and targeting this axis may suppress thromboinflammation. While antiplatelet therapy (APT) reduces platelet-platelet aggregation and thrombosis, its effects on MPA and platelet effector properties on monocytes are uncertain.

OBJECTIVES

 To analyze the effect of platelets on monocyte activation and APT on MPA and platelet-induced monocyte activation.

METHODS

 Agonist-stimulated whole blood was incubated in the presence of P-selectin, PSGL1, PAR1, P2Y12, GP IIb/IIIa, and COX-1 inhibitors and assessed for platelet and monocyte activity via flow cytometry. RNA-Seq of monocytes incubated with platelets was used to identify platelet-induced monocyte transcripts and was validated by RT-qPCR in monocyte-PR co-incubation ± APT.

RESULTS

 Consistent with a proinflammatory platelet effector role, MPAs were increased in patients with COVID-19. RNA-Seq revealed a thromboinflammatory monocyte transcriptome upon incubation with platelets. Monocytes aggregated to platelets expressed higher CD40 and tissue factor than monocytes without platelets (p < 0.05 for each). Inhibition with P-selectin (85% reduction) and PSGL1 (87% reduction) led to a robust decrease in MPA. P2Y12 and PAR1 inhibition lowered MPA formation (30 and 21% reduction, p < 0.05, respectively) and decreased monocyte CD40 and TF expression, while GP IIb/IIIa and COX1 inhibition had no effect. Pretreatment of platelets with P2Y12 inhibitors reduced the expression of platelet-mediated monocyte transcription of proinflammatory SOCS3 and OSM. CONCLUSIONS:  Platelets skew monocytes toward a proinflammatory phenotype. Among traditional APTs, P2Y12 inhibition attenuates platelet-induced monocyte activation.

Identification of AP-1 as a Critical Regulator of Glutathione Peroxidase 4 (GPX4) Transcriptional Suppression and Acinar Cell Ferroptosis in Acute Pancreatitis

Glutathione peroxidase 4 (GPX4)-dependent ferroptosis in pancreatic acinar cells plays a critical role in acute pancreatitis (AP). However, potential upstream regulators of GPX4 are not well defined. Here, we observed a marked reduction in acinar GPX4 expression and ferroptotic cell death in mice with cerulein-induced AP. To determine the critical factors involved in acinar cell ferroptosis, pancreas transcriptome data from an AP mouse model were analyzed and overlapped with predicted transcription factors of Gpx4, and an upregulated transcription factor active protein 1 (AP-1) protein, Jun, was identified. The administration of a specific ferroptosis inhibitor liproxstatin-1 alleviated AP pathology and significantly decreased Jun levels. Bioinformatic analysis indicated that the Gpx4 promoter contains a putative AP-1 binding site. Jun binds directly to the Gpx4 promoter and inhibits Gpx4 transcription under pancreatic conditions. AP-1 inhibition by a selective inhibitor SR11302 reversed GPX4 reduction and ameliorated AP pathology in a GPX4-dependent manner. Collectively, our study demonstrates that the downregulation of GPX4 by AP-1 is critical in the aggravation of acinar cell ferroptosis during the progression of AP. Strategies targeting the AP-1/GPX4 axis may be potentially effective for the prevention and treatment of AP.

Prothrombotic state, endothelial injury, and echocardiographic changes in non-active sarcoidosis patients

Sarcoidosis is a multisystem inflammatory granulomatous disease of unknown cause that most commonly affects lungs and lymph nodes, with frequent yet asymptomatic cardiac involvement. The epidemiologically associated cardiovascular risk suggests an underlying prothrombotic state and endothelial dysfunction, currently understudied in the available literature. Therefore, we aimed to investigate prothrombotic plasma properties together with selected echocardiographic and laboratory biomarkers of cardiovascular injury in that disease. N = 53 patients with pulmonary sarcoidosis in clinical remission and N = 66 matched controls were assessed for inflammatory and endothelial injury biomarkers, plasma thrombin generation profile, and echocardiographic and lung function parameters. Sarcoidosis cases had impaired systolic and diastolic left ventricular function, higher concentrations of inflammatory markers, D-dimer and factor VIII activity compared to the controls. The coexistence of extrapulmonary disease was associated with elevated circulating vascular cell adhesion molecule 1, while cases with hypercalcemia had higher thrombomodulin concentration. Sarcoidosis was characterized by the unfavorably altered thrombin generation profile, reflected by the 16% higher endogenous thrombin potential (ETP), 24% increased peak thrombin concentration, and 12% shorter time to thrombin peak in comparison to the control group. ETP was higher in cases with proxies of pulmonary restriction, extrapulmonary-extracutaneous manifestation, and need for corticosteroids use. Despite the clinical remission, sarcoidosis is related to prothrombotic plasma properties and signs of endothelial injury, likely contributing to the higher risk of cardiovascular events. In addition, subclinical cardiac involvement may play an additional role, although further clinical and experimental studies are needed to verify these findings.

Immunomodulatory role of thrombin in cancer progression

Coagulation proteases and the generation of thrombin are increased in tumors. In addition, chemotherapeutic agents commonly used to treat malignant cancers can exacerbate cancer-associated thromboses. Thrombin can modify tumor cell behavior directly through the activation of protease-activated receptors (PAR) or indirectly by generating fibrin matrices. In addition to its role in generating fibrin to promote hemostasis, thrombin acts directly on multiple effector cells of the immune system impacting both acute and chronic inflammatory processes. Thrombin-mediated release of interleukin-6, tumor necrosis factor-α, and monocyte chemoattractant protein-1 leads to the accumulation of multiple tumor-infiltrating immunosuppressive cell populations including myeloid derived suppresser cells, M2-like macrophages, and T regulatory cells. Ablation of PAR-1 from the tumor microenvironment, but not the tumor, has been shown to dramatically reduce tumor growth and metastasis in multiple tumor models. Thrombin-activated platelets release immunosuppressive cytokines including transforming growth factor-β that can inhibit natural killer cell activity, helping tumor cells to evade host immunosurveillance. Taken together, there is strong evidence that thrombin influences cancer progression via multiple mechanisms, including the tumor immune response, with thrombin emerging as a target for novel therapeutic strategies for cancer.

Neutrophil-Derived Oncostatin M Triggers Diverse Signaling Pathways during Pneumonia

Pneumonia is a major public health concern, causing significant morbidity and mortality annually despite the broad use of antimicrobial agents. Underlying many of the severe sequelae of acute lung infections is dysfunction of the immune response, which remains incompletely understood yet is an attractive target of adjunct therapy in pneumonia. Here, we investigate the role of oncostatin M (OSM), a pleiotropic cytokine of the interleukin-6 (IL-6) family, and how its signaling modulates multiple innate immune pathways during pneumonia. Previously, we showed that OSM is necessary for neutrophil recruitment to the lungs during pneumonia by stimulating STAT3-driven CXCL5 expression. In this study, transcriptional profiling of whole-lung pneumonia with OSM neutralization revealed 241 differentially expressed genes following only 6 h of infection. Many downregulated genes are associated with STAT1, STAT3, and interferon signaling, suggesting these pathways are induced by OSM early in pneumonia. Interestingly, STAT1 and STAT3 activation was subsequently upregulated with OSM neutralization by 24 h, suggesting that OSM interruption dysregulates these central signaling pathways. When we investigated the source of OSM in pneumonia, neutrophils and, to a lesser extent, macrophages appear to be primary sources, suggesting a positive feedback loop of OSM production by neutrophils. From these studies, we conclude that OSM produced by recruited neutrophils tunes early innate immune signaling pathways, improving pneumonia outcomes.

Thrombin Inhibition by Argatroban: Potential Therapeutic Benefits in COVID-19

Thrombin is a trypsin-like serine protease with multiple physiological functions. Its role in coagulation and thrombosis is well-established. Nevertheless, thrombin also plays a major role in inflammation by activating protease-activated receptors. In addition, thrombin is also involved in angiogenesis, fibrosis, and viral infections. Considering the pathogenesis of COVID-19 pandemic, thrombin inhibitors may exert multiple potential therapeutic benefits including antithrombotic, anti-inflammatory, and antiviral activities. In this review, we describe the clinical features of COVID-19, the thrombin’s roles in various pathologies, and the potential of argatroban in COVID-19 patients. Argatroban is a synthetic, small molecule, direct, competitive, and selective inhibitor of thrombin. It is approved to parenterally prevent and/or treat heparin-induced thrombocytopenia in addition to other thrombotic conditions. Argatroban also possesses anti-inflammatory and antiviral activities and has a well-established pharmacokinetics profile. It also appears to lack a significant risk of drug–drug interactions with therapeutics currently being evaluated for COVID-19. Thus, argatroban presents a substantial promise in treating severe cases of COVID-19; however, this promise is yet to be established in randomized, controlled clinical trials.

Oncostatin M in the Regulation of Connective Tissue Cells and Macrophages in Pulmonary Disease

Oncostatin M (OSM), as one of the gp130/IL-6 family of cytokines, interacts with receptor complexes that include the gp130 signaling molecule and OSM receptor β OSMRβ chain subunits. OSMRβ chains are expressed relatively highly across a broad array of connective tissue (CT) cells of the lung, such as fibroblasts, smooth muscle cells, and epithelial cells, thus enabling robust responses to OSM, compared to other gp130 cytokines, in the regulation of extracellular matrix (ECM) remodeling and inflammation. OSMRβ chain expression in lung monocyte/macrophage populations is low, whereas other receptor subunits, such as that for IL-6, are present, enabling responses to IL-6. OSM is produced by macrophages and neutrophils, but not CT cells, indicating a dichotomy of OSM roles in macrophage verses CT cells in lung inflammatory disease. ECM remodeling and inflammation are components of a number of chronic lung diseases that show elevated levels of OSM. OSM-induced products of CT cells, such as MCP-1, IL-6, and PGE2 can modulate macrophage function, including the expression of OSM itself, indicating feedback loops that characterize Macrophage and CT cell interaction.

Stimulation of bone formation by monocyte-activator functionalized graphene oxide in vivo

Nanosystems are able to enhance bone regeneration, a complex process requiring the mutual interplay between immune and skeletal cells. Activated monocytes can communicate pro-osteogenic signals to mesenchymal stem cells and promote osteogenesis. Thus, the activation of monocytes is a promising strategy to improve bone regeneration. Nanomaterials specifically selected to provoke immune-mediated bone formation are still missing. As a proof of concept, we apply here the intrinsic immune-characteristics of graphene oxide (GO) with the well-recognized osteoinductive capacity of calcium phosphate (CaP) in a biocompatible nanomaterial called maGO-CaP (monocytes activator GO complexed with CaP). In the presence of monocytes, the alkaline phosphatase activity and the expression of osteogenic markers increased. Studying the mechanisms of action, we detected an up-regulation of Wnt and BMP signaling, two key osteogenic pathways. The role of the immune activation was evidenced by the over-production of oncostatin M, a pro-osteogenic factor produced by monocytes. Finally, we tested the pro-osteogenic effects of maGO-CaP in vivo. maGO-CaP injected into the tibia of mice enhanced local bone mass and the bone formation rate. Our study suggests that maGO-CaP can activate monocytes to enhance osteogenesis ex vivo and in vivo.

Inflammation Induced by Platelet-Activating Viperid Snake Venoms: Perspectives on Thromboinflammation

Envenomation by viperid snakes is characterized by systemic thrombotic syndrome and prominent local inflammation. To date, the mechanisms underlying inflammation and blood coagulation induced by Viperidae venoms have been viewed as distinct processes. However, studies on the mechanisms involved in these processes have revealed several factors and signaling molecules that simultaneously act in both the innate immune and hemostatic systems, suggesting an overlap between both systems during viper envenomation. Moreover, distinct classes of venom toxins involved in these effects have also been identified. However, the interplay between inflammation and hemostatic alterations, referred as to thromboinflammation, has never been addressed in the investigation of viper envenomation. Considering that platelets are important targets of viper snake venoms and are critical for the process of thromboinflammation, in this review, we summarize the inflammatory effects and mechanisms induced by viper snake venoms, particularly from the Bothrops genus, which strongly activate platelet functions and highlight selected venom components (metalloproteases and C-type lectins) that both stimulate platelet functions and exhibit pro-inflammatory activities, thus providing insights into the possible role(s) of thromboinflammation in viper envenomation.

Thromboinflammation: challenges of therapeutically targeting coagulation and other host defense mechanisms

Thrombosis with associated inflammation (thromboinflammation) occurs commonly in a broad range of human disorders. It is well recognized clinically in the context of superficial thrombophlebitis (thrombosis and inflammation of superficial veins); however, it is more dangerous when it develops in the microvasculature of injured tissues and organs. Microvascular thrombosis with associated inflammation is well recognized in the context of sepsis and ischemia-reperfusion injury; however, it also occurs in organ transplant rejection, major trauma, severe burns, the antiphospholipid syndrome, preeclampsia, sickle cell disease, and biomaterial-induced thromboinflammation. Central to thromboinflammation is the loss of the normal antithrombotic and anti-inflammatory functions of endothelial cells, leading to dysregulation of coagulation, complement, platelet activation, and leukocyte recruitment in the microvasculature. α-Thrombin plays a critical role in coordinating thrombotic and inflammatory responses and has long been considered an attractive therapeutic target to reduce thromboinflammatory complications. This review focuses on the role of basic aspects of coagulation and α-thrombin in promoting thromboinflammatory responses and discusses insights gained from clinical trials on the effects of various inhibitors of coagulation on thromboinflammatory disorders. Studies in sepsis patients have been particularly informative because, despite using anticoagulant approaches with different pharmacological profiles, which act at distinct points in the coagulation cascade, bleeding complications continue to undermine clinical benefit. Future advances may require the development of therapeutics with primary anti-inflammatory and cytoprotective properties, which have less impact on hemostasis. This may be possible with the growing recognition that components of blood coagulation and platelets have prothrombotic and proinflammatory functions independent of their hemostatic effects.

Mesenchymal stem cell-macrophage crosstalk and bone healing

Recent research has brought about a clear understanding that successful fracture healing is based on carefully coordinated cross-talk between inflammatory and bone forming cells. In particular, the key role that macrophages play in the recruitment and regulation of the differentiation of mesenchymal stem cells (MSCs) during bone regeneration has been brought to focus. Indeed, animal studies have comprehensively demonstrated that fractures do not heal without the direct involvement of macrophages. Yet the exact mechanisms by which macrophages contribute to bone regeneration remain to be elucidated. Macrophage-derived paracrine signaling molecules such as Oncostatin M, Prostaglandin E2 (PGE2), and Bone Morphogenetic Protein-2 (BMP2) have been shown to play critical roles; however the relative importance of inflammatory (M1) and tissue regenerative (M2) macrophages in guiding MSC differentiation along the osteogenic pathway remains poorly understood. In this review, we summarize the current understanding of the interaction of macrophages and MSCs during bone regeneration, with the emphasis on the role of macrophages in regulating bone formation. The potential implications of aging to this cellular cross-talk are reviewed. Emerging treatment options to improve facture healing by utilizing or targeting MSC-macrophage crosstalk are also discussed.

Plaque Calcification During Atherosclerosis Progression and Regression

Plaque calcification develops by the inflammation-dependent mechanisms involved in progression and regression of atherosclerosis. Macrophages can undergo two distinct polarization states, that is, pro-inflammatory M1 phenotype in progression and anti-inflammatory M2 phenotype in regression. In plaque progression, predominant M1 macrophages promote the initial calcium deposition within the necrotic core of the lesions, called as microcalcification, through not only vesicle-mediated mineralization as the result of apoptosis of macrophages and vascular smooth muscle cells (VSMCs), but also VSMC differentiation into early phase osteoblasts. On the other hand, in plaque regression M2 macrophages are engaged in the healing response to plaque inflammation. In association with the resolution of chronic inflammation, M2 macrophages may facilitate macroscopic calcium deposition, called as macrocalcification, through induction of osteoblastic differentiation and maturation of VSMCs. Oncostatin M, which has been shown to promote osteoblast differentiation in bone, may play a pivotal role in the development of plaque calcification. Clinically, two types of plaque calcification have distinct implications. Macrocalcification leads to plaque stability, while microcalcification is more likely to be associated with plaque rupture. Statin therapy, which reduces cardiovascular mortality, has been shown to exert its dual actions on plaque morphology, that is, regression of atheroma and increment of macroscopic calcium deposits. Statins may facilitate the healing process against plaque inflammation by enhancing M2 polarization of macrophages. Vascular calcification has pleiotropic properties as pro-inflammatory “microcalcification” and anti-inflammatory “macrocalcification”. The molecular mechanisms of this process in relation with plaque progression as well as plaque regression should be intensively elucidated.

The barrier hypothesis and Oncostatin M: Restoration of epithelial barrier function as a novel therapeutic strategy for the treatment of type 2 inflammatory disease

Mucosal epithelium maintains tissue homeostasis through many processes, including epithelial barrier function, which separates the environment from the tissue. The barrier hypothesis of type 2 inflammatory disease postulates that epithelial and epidermal barrier dysfunction, which cause inappropriate exposure to the environment, can result in allergic sensitization and development of type 2 inflammatory disease. The restoration of barrier dysfunction once it's lost, or the prevention of barrier dysfunction, have the potential to be exciting new therapeutic strategies for the treatment of type 2 inflammatory disease. Neutrophil-derived Oncostatin M has been shown to be a potent disrupter of epithelial barrier function through the induction of epithelial-mesenchymal transition (EMT). This review will discuss these events and outline several points along this axis at which therapeutic intervention could be beneficial for the treatment of type 2 inflammatory diseases.

Neutrophils are a major source of the epithelial barrier disrupting cytokine oncostatin M in patients with mucosal airways disease

BACKGROUND

We have previously shown that oncostatin M (OSM) levels are increased in nasal polyps (NPs) of patients with chronic rhinosinusitis (CRS), as well as in bronchoalveolar lavage fluid, after segmental allergen challenge in allergic asthmatic patients. We also showed in vitro that physiologic levels of OSM impair barrier function in differentiated airway epithelium.

OBJECTIVE

We sought to determine which hematopoietic or resident cell type or types were the source of the OSM expressed in patients with mucosal airways disease.

METHODS

Paraffin-embedded NP sections were stained with fluorescence-labeled specific antibodies against OSM, GM-CSF, and hematopoietic cell-specific markers. Live cells were isolated from NPs and matched blood samples for flow cytometric analysis. Neutrophils were isolated from whole blood and cultured with the known OSM inducers GM-CSF and follistatin-like 1, and OSM levels were measured in the supernatants. Bronchial biopsy sections from control subjects, patients with moderate asthma, and patients with severe asthma were stained for OSM and neutrophil elastase.

RESULTS

OSM staining was observed in NPs, showed colocalization with neutrophil elastase (n = 10), and did not colocalize with markers for eosinophils, macrophages, T cells, or B cells (n = 3-5). Flow cytometric analysis of NPs (n = 9) showed that 5.1% ± 2% of CD45+ cells were OSM+, and of the OSM+ cells, 56% ± 7% were CD16+Siglec-8-, indicating neutrophil lineage. Only 0.6 ± 0.4% of CD45+ events from matched blood samples (n = 5) were OSM+, suggesting that increased OSM levels in patients with CRS was locally stimulated and produced. A majority of OSM+ neutrophils expressed arginase 1 (72.5% ± 12%), suggesting an N2 phenotype. GM-CSF levels were increased in NPs compared with those in control tissue and were sufficient to induce OSM production (P < .001) in peripheral blood neutrophils in vitro. OSM+ neutrophils were also observed at increased levels in biopsy specimens from patients with severe asthma. Additionally, OSM protein levels were increased in induced sputum from asthmatic patients compared with that from control subjects (P < .05).

CONCLUSIONS

Neutrophils are a major source of OSM-producing cells in patients with CRS and severe asthma.

Proinflammatory signaling functions of thrombin in cancer

Thrombin-induced activation of protease-activated receptors (PARs) represents a link between inflammation and cancer. Proinflammatory signaling functions of thrombin are associated with several inflammatory diseases including neurodegenerative, cardiovascular, and of special interest in this review cancer. Thrombin-induced inflammatory responses up-regulates expression of cytokines, adhesion molecules, angiogenic factors, and matrix-degrading proteases that facilitate tumor cells proliferation, angiogenesis, invasion, and metastasis. This review summarizes the current knowledge about the mechanisms of thrombin-mediated proinflammatory responses in cancer pathology for a better understanding and hence a better management of this disease.

Insulin-induced cytokine production in macrophages causes insulin resistance in hepatocytes

Overweight and obesity are associated with hyperinsulinemia, insulin resistance, and a low-grade inflammation. Although hyperinsulinemia is generally thought to result from an attempt of the β-cell to compensate for insulin resistance, there is evidence that hyperinsulinaemia itself may contribute to the development of insulin resistance and possibly the low-grade inflammation. To test this hypothesis, U937 macrophages were exposed to insulin. In these cells, insulin induced expression of the proinflammatory cytokines IL-1β, IL-8, CCL2, and OSM. The insulin-elicited induction of IL-1β was independent of the presence of endotoxin and most likely mediated by an insulin-dependent activation of NF-κB. Supernatants of the insulin-treated U937 macrophages rendered primary cultures of rat hepatocytes insulin resistant; they attenuated the insulin-dependent induction of glucokinase by 50%. The cytokines contained in the supernatants of insulin-treated U937 macrophages activated ERK1/2 and IKKβ, resulting in an inhibitory serine phosphorylation of the insulin receptor substrate. In addition, STAT3 was activated and SOCS3 induced, further contributing to the interruption of the insulin receptor signal chain in hepatocytes. These results indicate that hyperinsulinemia per se might contribute to the low-grade inflammation prevailing in overweight and obese patients and thereby promote the development of insulin resistance particularly in the liver, because the insulin concentration in the portal circulation is much higher than in all other tissues.

Tissue factor is induced by interleukin-33 in human endothelial cells: a new link between coagulation and inflammation

Tissue factor (TF) is the primary trigger of coagulation. Elevated levels of TF are found in atherosclerotic plaques, and TF leads to thrombus formation when released upon plaque rupture. Interleukin (IL)-33 was previously shown to induce angiogenesis and inflammatory activation of endothelial cells (ECs). Here, we investigated the impact of IL-33 on TF in human ECs, as a possible new link between inflammation and coagulation. IL-33 induced TF mRNA and protein in human umbilical vein ECs and coronary artery ECs. IL-33-induced TF expression was ST2- and NF-κB-dependent, but IL-1-independent. IL-33 also increased cell surface TF activity in ECs and TF activity in ECs-derived microparticles. IL-33-treated ECs reduced coagulation time of whole blood and plasma but not of factor VII-deficient plasma. In human carotid atherosclerotic plaques (n = 57), TF mRNA positively correlated with IL-33 mRNA expression (r = 0.691, p < 0.001). In this tissue, IL-33 and TF protein was detected in ECs and smooth muscle cells by immunofluorescence. Furthermore, IL-33 and TF protein co-localized at the site of clot formation within microvessels in plaques of patients with symptomatic carotid stenosis. Through induction of TF in ECs, IL-33 could enhance their thrombotic capacity and thereby might impact on thrombus formation in the setting of atherosclerosis.

Loss of Biglycan Enhances Thrombin Generation in Apolipoprotein E -Deficient Mice

Objective—

Thrombin signaling promotes atherosclerosis by initiating inflammatory events indirectly through platelet activation and directly via protease-activated receptors. Therefore, endogenous thrombin inhibitors may be relevant modulators of atheroprogression and cardiovascular risk. In addition, endogenous thrombin inhibitors may affect the response to non–vitamin K-dependent oral anticoagulants. Here, the question was addressed whether the small leucine-rich proteoglycan biglycan acts as an endogenous thrombin inhibitor in atherosclerosis through activation of heparin cofactor II.

Approach and Results—

Biglycan concentrations were elevated in the plasma of patients with acute coronary syndrome and in male Apolipoprotein E -deficient ( ApoE −/− ) mice. Biglycan was detected in the glycocalyx of capillaries and the subendothelial matrix of arterioles of ApoE −/− mice and in atherosclerotic plaques. Thereby a vascular compartment is provided that may mediate the endothelial and subendothelial activation of heparin cofactor II through biglycan. ApoE and Bgn double-deficient ( ApoE −/− /Bgn −/0 ) mice showed higher activity of circulating thrombin, increased platelet activation and platelet adhesion in vivo, supporting a role of biglycan in balancing thrombin activity. Furthermore, concentrations of circulating cytokines and aortic macrophage content were elevated in ApoE −/− /Bgn −/0 mice, suggesting a proinflammatory phenotype. Elevated platelet activation and macrophage accumulation were reversed by treating ApoE −/− /Bgn −/0 mice with the thrombin inhibitor argatroban. Ultimately, ApoE −/− /Bgn −/0 mice developed aggravated atherosclerosis.

Conclusions—

The present results indicate that biglycan plays a previously unappreciated protective role during the progression of atherosclerosis by inhibiting thrombin activity, platelet activation, and finally macrophage-mediated plaque inflammation.

Dabigatran etexilate retards the initiation and progression of atherosclerotic lesions and inhibits the expression of oncostatin M in apolipoprotein E-deficient mice

Objective

Thrombin has multiple proatherogenic effects including platelet activation and the induction of inflammatory processes. Recently, the cytokine oncostatin M has been shown to have proinflammatory effects. This study was designed to investigate the effects of thrombin inhibition on the initiation and progression of atherosclerosis and on the expression of oncostatin M.

Methods

Apolipoprotein E-deficient mice at different ages were fed the thrombin inhibitor dabigatran etexilate. The mean lesion area was measured in the aortic sinus and in the innominate artery. CD45-positive cells within the aortic tissue were measured by flow cytometry. Oncostatin M expression was measured in the tissue sections by immunocytochemistry.

Results

Treatment with dabigatran etexilate resulted in a significant reduction of the mean area of atherosclerotic lesions in the aortic sinus in both the young mice (11,176±1,500 μm² (control) versus 3,822±836 μm² (dabigatran etexilate), P<0.05) and selectively in the older mice at 28 weeks (234,099±13,500 μm² (control) versus 175,226±16,132 μm² (dabigatran etexilate), P<0.05). There were also fewer CD45-positive cells within the aortas of the dabigatran-treated mice and enhanced NO production in endothelial cells pretreated with dabigatran. In addition, the expression of oncostatin M was reduced in the lesions of dabigatran etexilate-treated mice.

Conclusion

Inhibition of thrombin by dabigatran retards the development of early lesions and the progression of some established lesions in ApoE–/– mice. It improves endothelial function and retards macrophage accumulation within the vascular wall. Dabigatran also inhibits the expression of oncostatin M, and this suggests that oncostatin M may play a role in the initiation and progression of atherosclerosis.

Thrombin inhibits the anti-myeloperoxidase and ferroxidase functions of ceruloplasmin: relevance in rheumatoid arthritis

Human ceruloplasmin (CP) is a multifunctional copper-binding protein produced in the liver. CP oxidizes Fe(2+) to Fe(3+), decreasing the concentration of Fe(2+) available for generating harmful oxidant species. CP is also a potent inhibitor of leukocyte myeloperoxidase (MPO) (Kd=130nM), a major source of oxidants in vivo. Rheumatoid arthritis (RA) is an inflammatory autoimmune disease affecting flexible joints and characterized by activation of both inflammatory and coagulation processes. Indeed, the levels of CP, MPO, and thrombin are markedly increased in the synovial fluid of RA patients. Here we show that thrombin cleaves CP in vitro at (481)Arg-Ser(482) and (887)Lys-Val(888) bonds, generating a nicked species that retains the native-like fold and the ferroxidase activity of the intact protein, whereas the MPO inhibitory function of CP is abrogated. Analysis of the synovial fluid of 24 RA patients reveals that CP is proteolytically degraded to a variable extent, with a fragmentation pattern similar to that observed with thrombin in vitro, and that proteolysis is blocked by hirudin, a highly potent and specific thrombin inhibitor. Using independent biophysical techniques, we show that thrombin has intrinsic affinity for CP (Kd=60-270nM), independent of proteolysis, and inhibits CP ferroxidase activity (KI=220±20nM). Mapping of thrombin binding sites with specific exosite-directed ligands (i.e., hirugen, fibrinogen γ'-peptide) and thrombin analogues having the exosites variably compromised (i.e., prothrombin, prethrombin-2, βT-thrombin) reveals that the positively charged exosite-II of thrombin binds to the negatively charged upper region of CP, while the protease active site and exosite-I remain accessible. These results suggest that thrombin can exacerbate inflammation in RA by impairing the MPO inhibitory function of CP via proteolysis and by competitively inhibiting CP ferroxidase activity. Notably, local administration of hirudin, a highly potent and specifc thrombin inhibitor, reduces the concentration of active MPO in the synovial fluid of RA patients and has a beneficial effect on the clinical symptoms of the disease.

Osteopontin Promotes Oncostatin M Production in Human Osteoblasts: Implication of Rheumatoid Arthritis Therapy

Accumulating evidence indicates that subchondral bone might play an essential role in rheumatoid arthritis (RA). Osteopontin (OPN) induces the production of an important proinflammatory cytokine involved in the pathogenesis of RA. This study evaluated the activation of oncostatin M (OSM) by OPN in human primary osteoblasts to understand RA pathogenesis and characterized the intracellular signaling pathways involved in this activation. Quantitative PCR, ELISA, and Western blot results indicated that stimulation of human primary osteoblasts with OPN induces OSM expression through αvβ3 integrin/c-Src/platelet-derived growth factor receptor transactivation/MEK/ERK. Treatment of osteoblasts with OPN also increased c-Jun phosphorylation, AP-1 luciferase activity, and c-Jun binding to the AP-1 element on the OSM promoter, as demonstrated using chromatin immunoprecipitation assay. Moreover, inhibition of OPN expression using lentiviral-OPN short hairpin RNA resulted in the amelioration of articular swelling, cartilage erosion, and OSM expression in the ankle joint of mice with collagen-induced arthritis as shown using microcomputed tomography and immunohistochemistry staining. Our results imply that OSM expression in osteoblasts increases in response to OPN-induced inflammation in vitro. Finally, lentiviral-OPN short hairpin RNA ameliorates the inflammatory response and bone destruction in mice with collagen-induced arthritis. Therefore, OPN may be a potential therapeutic target for RA.

Modulation of vascular smooth muscle cell phenotype by STAT-1 and STAT-3

OBJECTIVE

Smooth muscle cell (SMC) de-differentiation is a key step that leads to pathological narrowing of blood vessels. De-differentiation involves a reduction in the expression of the SMC contractile genes that are the hallmark of quiescent SMCs. While there is considerable evidence linking inflammation to vascular diseases, very little is known about the mechanisms by which inflammatory signals lead to SMC de-differentiation. Given that the Signal Transducers and Activators of Transcription (STAT) transcriptional factors are the key signaling molecules activated by many inflammatory cytokines and growth factors, the aim of the present study was to determine if STAT transcriptional factors play a role SMC de-differentiation.

METHODS AND RESULTS

Using shRNA targeted to STAT-1 and STAT-3, we show by real time RT-PCR and Western immunoblots that STAT-1 significantly reduces SMC contractile gene expression. In contrast, STAT-3 promotes expression of SMC contractile genes. Over-expression studies of STAT-1 and STAT-3 confirmed our observation that STAT-1 down-regulates whereas STAT-3 promotes SMC contractile gene expression. Bioinformatics analysis shows that promoters of all SMC contractile genes contain STAT binding sites. Finally, using ChIP analysis, we show that both STAT-1 and STAT-3 associate with the calponin gene.

CONCLUSION

These data indicate that the balance of STAT-1 and STAT-3 influences the differentiation status of SMCs. Increased levels of STAT-1 promote SMC de-differentiation, whereas high levels of STAT-3 drive SMC into a more mature phenotype. Thus, inhibition of STAT-1 may represent a novel target for therapeutic intervention in the control of vascular diseases such as atherosclerosis and restenosis.

Inflammation and coagulation in atherosclerosis

Cardiovascular diseases remain to be the leading cause of death in Western societies. Despite major findings in vascular biology that lead to a better understanding of the pathomechanisms involved in atherosclerosis, treatment of the disease has only changed slightly within the last years. A big body of evidence suggests that atherosclerosis is a chronic inflammatory disease of the vessel wall. Accumulation and peroxidation of LDL-particles within the vessel wall trigger a strong inflammatory response, causing macrophage and T-cell accumulation within the vessel wall. Additionally, B-cells and specific antibodies against LDL-particles, as well as the complement system are implicated in atherogenesis. Besides data from clinical trials and autopsy studies it was the implementation of mouse models of atherosclerosis and the emerging field of direct gen-modification that lead to a thorough description of the pathophysiological mechanisms involved in the disease and created overwhelming evidence for a participation of the immune system. Recently, the cross-talk between coagulation and inflammation in atherogenesis has gained attention. Serious limitations and disparities in the pathophysiology of atherosclerosis in mice and men complicated the translation of experimental data into clinical practice. Despite these limitations, new anti-inflammatory medical therapies in cardiovascular disease are currently being tested in clinical trials.

Endogenous glucocorticoids inhibit myocardial inflammation induced by lipopolysaccharide: involvement of regulation of histone deacetylation

Emerging evidence indicates that myocardial inflammation plays a key role in the pathogenesis of cardiac diseases. But the exact mechanisms for this chronic inflammatory disorder have not been elucidated. Glucocorticoids (GCs) are the most effective anti-inflammatory treatments available for many inflammatory diseases. However, it is unknown whether endogenous GCs are able to exert anti-inflammatory effect on myocardial inflammation. In this study, the potential role of endogenous GCs in the regulation of myocardial inflammation was investigated. We showed that the reduction of endogenous GC level by adrenalectomy promoted the production of basal and lipopolysaccharide (LPS)-induced proinflammatory cytokines, which could be partly reversed by supplementing with exogenous physiological level of hydrocortisone. Inhibition of GC receptor (GR) signaling pathway with GR antagonist mifepristone (RU486) or histone deacetylase inhibitor trichostatin A (TSA) also increased the levels of basal and LPS-induced proinflammatory cytokines. Moreover, blockade of GC-GR signaling pathway by adrenalectomy, RU486 or TSA enhanced LPS-induced myocardial nuclear factor-κB activation and histone acetylation but inhibited myocardial histone deacetylase expression and activity. Cardiac function studies demonstrated that blockade of the GC-GR signaling pathway aggravated inflammation-induced cardiac dysfunction. These findings indicate that endogenous GCs are able to inhibit myocardial inflammation induced by LPS. Endogenous GCs represent an important endogenous anti-inflammatory mechanism for myocardium in rats and such mechanism injury may be an important factor for pathogenesis of cardiac diseases.

Prostaglandin E₂ induces oncostatin M expression in human chronic wound macrophages through Axl receptor tyrosine kinase pathway

Monocytes and macrophages (m) are plastic cells whose functions are governed by microenvironmental cues. Wound fluid bathing the wound tissue reflects the wound microenvironment. Current literature on wound inflammation is primarily based on the study of blood monocyte-derived macrophages, cells that have never been exposed to the wound microenvironment. We sought to compare pair-matched monocyte-derived macrophages with m isolated from chronic wounds of patients. Oncostatin M (OSM) was differentially overexpressed in pair-matched wound m. Both PGE₂ and its metabolite 13,14-dihydro-15-keto-PGE₂ (PGE-M) were abundant in wound fluid and induced OSM in wound-site m. Consistently, induction of OSM mRNA was observed in m isolated from PGE₂-enriched polyvinyl alcohol sponges implanted in murine wounds. Treatment of human THP-1 cell-derived m with PGE₂ or PGE-M caused dose-dependent induction of OSM. Characterization of the signal transduction pathways demonstrated the involvement of EP4 receptor and cAMP signaling. In human m, PGE₂ phosphorylated Axl, a receptor tyrosine kinase (RTK). Axl phosphorylation was also induced by a cAMP analogue demonstrating interplay between the cAMP and RTK pathways. PGE₂-dependent Axl phosphorylation led to AP-1 transactivation, which is directly implicated in inducible expression of OSM. Treatment of human m or mice excisional wounds with recombinant OSM resulted in an anti-inflammatory response as manifested by attenuated expression of endotoxin-induced TNF-α and IL-1β. OSM treatment also improved wound closure during the early inflammatory phase of healing. In summary, this work recognizes PGE₂ in the wound fluid as a potent inducer of m OSM, a cytokine with an anti-inflammatory role in cutaneous wound healing.

Positive regulation of NADPH oxidase 5 by proinflammatory-related mechanisms in human aortic smooth muscle cells

NADPH oxidase Nox5 subtype expression is significantly increased in vascular smooth muscle cells (SMCs) underlying fibro-lipid atherosclerotic lesions. The mechanisms that up-regulate Nox5 are not understood. Consequently, we characterized the promoter of the human Nox5 gene and investigated the role of various proinflammatory transcription factors in the regulation of Nox5 in human aortic SMCs. The Nox5 promoter was cloned in the pGL3 basic reporter vector. Functional analysis was done employing 5' deletion mutants to identify the sequences necessary to effect high levels of expression in SMCs. Transcriptional initiation site was detected by rapid amplification of the 5'-cDNA ends. In silico analysis indicated the existence of typical NF-kB, AP-1, and STAT1/STAT3 sites. Transient overexpression of p65/NF-kB, c-Jun/AP-1, or STAT1/STAT3 increased significantly the Nox5 promoter activity. Chromatin immunoprecipitation demonstrated the physical interaction of c-Jun/AP-1 and STAT1/STAT3 proteins with the Nox5 promoter. Lucigenin-enhanced chemiluminescence, real-time PCR, and Western blot assays showed that pharmacological inhibition and the silencing of p65/NF-kB, c-Jun/AP-1, or STAT1/STAT3 reduced significantly the interferon γ-induced Ca(2+)-dependent Nox activity and Nox5 expression. Up-regulated Nox5 correlated with increases in intracellular Ca(2+), an essential condition for Nox5 activity. NF-kB, AP-1, and STAT1/STAT3 are important regulators of Nox5 in SMCs by either direct or indirect mechanisms. Overexpressed Nox5 may generate free radicals in excess, further contributing to SMCs dysfunction in atherosclerosis.

The aging patient with hemophilia

The prospects for many boys born with hemophilia today include a normal life expectancy and minimal to no joint disease. However, despite the availability of safe replacement clotting factor concentrates and effective antiviral treatment, the aging patient with hemophilia today faces many challenges. These include management of their hemophilia as well as the same age-related health issues as experienced in the general population. While increasing, data on the prevalence of comorbidities and their management in the hemophilia population remain limited. This review will focus on issues related to management of hemophilia and complications of cardiovascular, musculoskeletal, hepatic, and renal disease. Available research is summarized and potential approaches to management are discussed.

Vascular effects of glycoprotein130 ligands--part I: pathophysiological role

The vessel wall is no longer considered as only an anatomical barrier for blood cells but is recognized as an active endocrine organ. Dysfunction of the vessel wall occurs in various disease processes including atherosclerosis, hypertension, peripheral artery disease, aneurysms, and transplant and diabetic vasculopathies. Different cytokines were shown to modulate the behavior of the cells, which constitute the vessel wall such as immune cells, endothelial cells and smooth muscle cells. Glycoprotein 130 (gp130) is a common cytokine receptor that controls the activity of a group of cytokines, namely, interleukin (IL)-6, oncostatin M (OSM), IL-11, ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), cardiotrophin-1 (CT-1), cardiotrophin-like cytokine (CLC), IL-27, and neuropoietin (NP). Gp130 and associated cytokines have abundantly diverse functions. Part I of this review focuses on the pathophysiological functions of gp130 ligands. We specifically describe vascular effects of these molecules and discuss the respective underlying molecular and cellular mechanisms.

Thrombin as a multi-functional enzyme. Focus on in vitro and in vivo effects

Thrombin is the central protease in the coagulation cascade and one of the most extensively studied of all enzymes. In addition to its recognised role in the coagulation cascade and haemostasis, thrombin is known to have multiple pleiotropic effects, which mostly have been shown only in in vitro studies: it plays a role in inflammation and cellular proliferation and displays a mitogen activity on smooth muscle cells and endothelial cells, predominantly by activation of angiogenesis. In vivo , thrombin effects were examined in animal models of intravenous or intraarterial thrombin infusion. An extensive literature search regarding in vivo data showed that i) thrombin administered as a bolus causes microembolism, ii) thrombin infused slowly at steady-state conditions (up to 1.6 U/kg/min) leads to bleeds but not to intravascular clotting, iii) large quantity of thrombin infused at low rates (0.05 U/kg/min) does not have any measurable effect, and iv) thrombin increases vascular permeability leading to tissue damage. Although several decades of research on thrombin functions have provided a framework for understanding the biology of thrombin, animal and human studies with use of newer laboratory techniques are still needed to confirm the pleiotropic thrombin functions shown in in vitro studies.

Adipose tissue expression of interleukin-18 mRNA is elevated in subjects with metabolic syndrome and independently associated with fasting glucose

BACKGROUND

The metabolic syndrome (MetS) is a cluster of risk factors that are highly associated with increased risk for cardiovascular disease (CVD). Increased serum levels of plasminogen activator inhibitor-1 (PAI-1), interleukin-6 (IL-6) and IL-18 have been reported to be associated with CVD. Recently, IL-18 has been shown to be predictive for cardiovascular events in subjects with MetS. We have investigated the expression of PAI-1, IL-6 and IL-18 in subcutaneous adipose tissue (AT) of subjects with (n = 22) and without (n = 36) MetS. Furthermore, we have analysed the expression of IL-18 in monocyte-derived macrophages (MDMs) in an in vitro model of hyperglycaemia.

METHODS

We studied the expression of PAI-1, IL-6 and IL-18 in biopsies of subcutaneous adipose tissue using Real-time PCR. After isolation and cultivation of MDMs, expression of IL-18 was determined by Real-time PCR.

RESULTS

Expression of IL-18 was increased in subcutaneous AT of subjects with MetS (p < 0.05). Multivariate analysis revealed fasting plasma glucose to be the only MetS component being independently associated with expression of IL-18 in AT (p < 0.05). Exposure to hyperglycaemia, increased in expression of IL-18 in MDMs (p < 0.01).

CONCLUSION

Our findings suggest that subjects with MetS have a particular inflammatory pattern in AT, possibly driven by fasting glucose. MDMs might - at least in part - be the cellular source of this increased expression. Together with recent reports, showing IL-18 to be predictive for cardiovascular events, our findings could provide the basis for further research of the role of IL-18 as a link and possible target in the association between MetS and atherosclerosis.

The roles of thrombin and protease-activated receptors in inflammation

Inflammation and coagulation constitute two host defence systems with complementary physiological roles in limiting tissue damage, restoring homeostasis and eliminating invading pathogens, functions reliant on effective regulation of both processes at a variety of levels. Dysfunctional activation or regulation of either pathway may lead to pathology and contribute to human diseases as diverse as myocardial infarction and septic shock. The serine protease thrombin, a key protein in the coagulation pathway, can activate cellular signalling directly via proteolytic cleavage of the N-terminal domain of a family of G protein-coupled receptors or indirectly through the generation of molecules such as activated protein C. These events transmit signals to many cell types and can elicit the production of various pro-inflammatory mediators such as cytokines, chemokines and growth factors, thereby influencing cell activation, differentiation, survival and migration. This review discusses recent progress in understanding how thrombin and protease-activated receptors influence biological processes, highlighting the detrimental and protective cellular effects of thrombin and its signalling pathways.

Oncostatin M is expressed in atherosclerotic lesions: a role for Oncostatin M in the pathogenesis of atherosclerosis

OBJECTIVE

Chronic inflammation plays a pivotal role in the development and progression of atherosclerosis. The inflammatory response is mediated by cytokines. The aim of this study was to determine if Oncostatin M (OSM), a monocyte and T-lymphocyte specific cytokine is present in atherosclerotic lesions. We also investigated the roles of signal transducer and activator of transcription (STAT)-1 and STAT-3 in regulating OSM-induced smooth muscle cell (SMC) proliferation, migration and cellular fibronectin (cFN) synthesis.

METHODS AND RESULTS

Immunostaining of atherosclerotic lesions from human carotid plaques demonstrated the expression of OSM antigen in both macrophages and SMCs. Explanted SMCs from human carotid plaques expressed OSM mRNA and protein as determined by RT-PCR and Western blotting. Using the chow-fed ApoE(-/-) mouse model of atherosclerosis, we observed that OSM was initially expressed in the intima at 20 weeks of age. By 30 weeks, OSM was expressed in both the intima and media. In vitro studies show that OSM promotes SMC proliferation, migration and cFN synthesis. Lentivirus mediated-inhibition of STAT-1 and STAT-3 prevented OSM-induced SMC proliferation, migration and cellular fibronectin synthesis.

CONCLUSIONS

These findings demonstrate that OSM is expressed in atherosclerotic lesions and may contribute to the progression of atherosclerosis by promoting SMC proliferation, migration and extracellular matrix protein synthesis through the STAT pathway.

Oncostatin M-enhanced vascular endothelial growth factor expression in human vascular smooth muscle cells involves PI3K-, p38 MAPK-, Erk1/2- and STAT1/STAT3-dependent pathways and is attenuated by interferon-γ

The pleiotropic cytokine oncostatin M (OSM), a member of the glycoprotein (gp)130 ligand family, plays a key role in inflammation and cardiovascular disease. As inflammation precedes and accompanies pathological angiogenesis, we investigated the effect of OSM and other gp130 ligands on vascular endothelial growth factor (VEGF) production in human vascular smooth muscle cells (SMC). Human coronary artery SMC (HCASMC) and human aortic SMC (HASMC) were treated with different gp130 ligands. VEGF protein was determined by ELISA. Specific mRNA was detected by RT-PCR. Western blotting was performed for signal transducers and activators of transcription1 (STAT1), STAT3, Akt and p38 mitogen-activated protein kinase (p38 MAPK). OSM mRNA and VEGF mRNA expression was analyzed in human carotid endaterectomy specimens from 15 patients. OSM increased VEGF production in both HCASMC and HASMC derived from different donors. OSM upregulated VEGF and OSM receptor-specific mRNA in these cells. STAT3 inhibitor WP1066, p38 MAPK inhibitors SB-202190 and BIRB 0796, extracellular signal-regulated kinase1/2 (Erk1/2) inhibitor U0126, and phosphatidylinositol 3-kinase (PI3K) inhibitors LY-294002 and PI-103 reduced OSM-induced VEGF synthesis. We found OSM expression in human atherosclerotic lesions where OSM mRNA correlated with VEGF mRNA expression. Interferon-γ (IFN-γ), but not IL-4 or IL-10, reduced OSM-induced VEGF production in vascular SMC. Our findings that OSM, which is present in human atherosclerotic lesions and correlates with VEGF expression, stimulates production of VEGF by human coronary artery and aortic SMC indicate that OSM could contribute to plaque angiogenesis and destabilization. IFN-γ reduced OSM-induced VEGF production by vascular SMC.

Phosphorylation mechanisms in intensive care medicine

INTRODUCTION

The phosphorylation states of proteins, lipids, carbohydrates, amino acids, and nucleotides control the mechanisms behind nearly all cellular functions. Therefore, not surprisingly, recent findings have shown that alterations in these phosphorylation pathways play a central role in the development and progression of many disease states. This review provides a brief summary of the function and activity of various phosphorylation mechanisms, outlines some of the major phosphorylation signaling cascades, and describes the role of these phosphorylation mechanisms in intensive care medicine.

METHODS

This article will comprise a comprehensive review of the literature in the context of intensive care medicine. Specifically, we will discuss the involvement of phosphorylation in the pathogenesis, diagnosis, and treatment of heart failure, myocardial infarction, stroke, respiratory failure, ventilation-induced lung injury, traumatic brain injury, acute organ failure, systemic sepsis, and shock.

CONCLUSION

Phosphorylation mechanisms clearly play an important role in many pathologies and treatment strategies of intensive care and therefore further understanding of these mechanisms may lead to the development of novel therapies and improved patient care.

The complement component C5a is present in human coronary lesions in vivo and induces the expression of MMP-1 and MMP-9 in human macrophages in vitro

The complement component C5a is formed during activation of the complement cascade and exerts chemotactic and proinflammatory effects. Macrophages, which are localized in the rupture-prone shoulder regions of coronary plaques, are thought to play a major role in plaque destabilization and rupture through the production of matrix metalloproteinases (MMPs). When human monocyte-derived macrophages were stimulated in vitro with C5a, MMP-1 and MMP-9 mRNA levels were significantly increased. Furthermore, C5a up-regulated MMP-1 and MMP-9 antigens and activity, as determined by ELISA and specific activity assays. These effects were blocked by antibodies against the receptor C5aR/CD88. In addition, blocking experiments revealed that MMP-1 expression was mediated by activation of the transcription factor AP-1, and MMP-9 expression was induced by activation of NF-κB and AP-1. Immunohistochemical analysis of human coronary plaques demonstrated the colocalization of C5a, MMP-1, and MMP-9 in vivo. Together, these observations indicate that activation of the complement cascade and formation of C5a may play a role in the onset of acute coronary events by induction of MMPs in atherosclerotic lesions.