Monocyte tissue factor-dependent activation of coagulation in hypercholesterolemic mice and monkeys is inhibited by simvastatin

HuR inhibition reduces post-ischemic cardiac remodeling by dampening myocyte-dependent inflammatory gene expression and the innate immune response

The RNA-binding protein human antigen R (HuR) has been shown to reduce cardiac remodeling following both myocardial infarction and cardiac pressure overload, but the full extent of the HuR-dependent mechanisms within cells of the myocardium has yet to be elucidated. Wild-type mice were subjected to 30 min of cardiac ischemia (via LAD occlusion) and treated with a novel small molecule inhibitor of HuR at the time of reperfusion, followed by direct in vivo assessment of cardiac structure and function. Direct assessment of HuR-dependent mechanisms was done in vitro using neonatal rat ventricular myocytes (NRVMs) and bone marrow-derived macrophages (BMDMs). HuR activity is increased within 2 h after ischemia/reperfusion (I/R) and is necessary for early post-I/R inflammatory gene expression in the myocardium. Despite an early reduction in inflammatory gene expression, HuR inhibition has no effect on initial infarct size at 24 h post-I/R. However, pathological remodeling is reduced with preserved cardiac function at 2 weeks post-I/R upon HuR inhibition. RNA sequencing analysis of gene expression in NRVMs treated with LPS to model damage-associated molecular pattern (DAMP)-mediated activation of toll-like receptors (TLRs) demonstrates a HuR-dependent regulation of pro-inflammatory chemokine and cytokine gene expression in cardiomyocytes. Importantly, we show that conditioned media transfer from NRVMs pre-treated with HuR inhibitor loses the ability to induce inflammatory gene expression and M1-like polarization in bone marrow-derived macrophages (BMDMs) compared to NRVMs treated with LPS alone. Functionally, HuR inhibition reduces macrophage infiltration to the post-ischemic myocardium in vivo. Additionally, we show that LPS-treated NRVMs induce the migration of peripheral blood monocytes in a HuR-dependent endocrine manner. These studies demonstrate that HuR is necessary for early pro-inflammatory gene expression in cardiomyocytes following I/R injury that subsequently mediates monocyte recruitment and macrophage activation in the post-ischemic myocardium.

Exploring the Pleiotropy of PCSK9: A Wide Range of Influences from Lipid Regulation to Extrahepatic Function

In cardiovascular disease, the discovery of the proprotein convertase subtilisin/kexin type 9 (PCSK9) has undoubtedly opened a new chapter in regulating blood lipids. Since its first identification as a key regulator of low-density lipoprotein receptor (LDLR) degradation in 2003, the role of PCSK9 in cholesterol metabolism has been extensively studied. However, with further research, the pleiotropy of PCSK9 has gradually emerged, and its impact extends far beyond cholesterol metabolism in the liver. The purpose of this review is to systematically explore the pleiotropy of PCSK9, extending from its important role in lipid regulation to its extensive effects in extrahepatic tissues, and to reveal its potential role in cardiovascular health, nervous system function, and tumor biology. By integrating the latest research findings, this paper summarizes the complex mechanisms of action of PCSK9 in different biological processes and explores its potential and challenges as a therapeutic target.

Low HDL Cholesterol is Associated with Reduced Bleeding Risk in Patients who Underwent PCI: Findings from the PRACTICE Study

BACKGROUND

 We sought to examine the dose-response relationship between high-density lipoprotein cholesterol (HDL-C) and bleeds in coronary artery disease (CAD) patients who underwent percutaneous coronary intervention (PCI).

METHODS

 All the 15,250 participants were from the Personalized Antiplatelet Therapy According to CYP2C19 Genotype in Coronary Artery Disease (PRACTICE) study, which is a large, single-center, prospective cohort study based on case records and a follow-up registry performed in the First Affiliated Hospital of Xinjiang Medical University from December 2016 to October 2021. We divided all the patients into five groups according to their HDL-C levels: the ≤35 mg/dL group (n = 4,732), 35 to 45 mg/dL group (n = 6,049), 45 to 55 mg/dL group (n = 2,826), 55 and 65 mg/dL group (n = 1,117), and >65 mg/dL group (n = 526). The incidence of bleeds, mortality, ischemic events, and net adverse clinical events (NACEs) among the five groups was compared.

RESULTS

 A total of 713 bleeds, 1,180 ischemic events, 456 deaths, and 1,893 NACEs were recorded during the up to 60-month follow-up period. After adjusting for confounders, we observed a nonlinear relation for bleeds, with the highest risk at intermediate HDL-C levels (45-55 mg/dL). We also identified a dose-response relationship for ischemic events. A threshold value of HDL-C ≤35 mg/dL (adjusted hazard ratio = 0.560, 95% confidence interval: 0.360-0.872, p = 0.010) was associated with a decreased risk for bleeds in the multivariable Cox regression model. The results were consistent in multiple sensitivity analyses and propensity score-matching analysis.

CONCLUSION

 In the present study, a nonlinear association was identified between HDL-C levels and bleeds in CAD patients who underwent PCI, with a higher risk at intermediate levels. However, further multicenter studies are warranted.

Effects of Lipophilic Statins on Cell Viability and Tissue Factor Expression in Canine Haemangiosarcoma Cells

Canine haemangiosarcoma (HSA) is a highly aggressive cancer often associated with coagulation abnormalities. Statins, inhibitors of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR) clinically prescribed for hypercholesterolemia, are also believed to possess antitumour and anticoagulant properties by inhibiting downstream Akt activation. Akt phosphorylation is involved in the mechanism of the antitumour and tissue factor (TF)-lowering effects of statins. In the present study, we aimed to investigate whether statins could inhibit cell viability while concurrently inducing anticoagulant properties by regulating the expression of TFs in canine HSA cells. Using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), we initially exclusively detected HMGCR mRNA expression in canine HSA tissues and cell lines but not in normal cephalic vein and spleen tissues. Moreover, treatment with lipophilic statins, including atorvastatin, fluvastatin, and simvastatin, inhibited cell viability in a concentration-dependent manner and decreased TF expression both at the mRNA and protein levels, as evidenced by cell viability assays, RT-qPCR, and immunoblotting, respectively. Further investigation using cell viability assays and flow cytometry revealed that simvastatin decreased Akt phosphorylation, and MK-2206, a specific Akt inhibitor, mirrored the effect of simvastatin on cell viability and cell cycle arrest. However, MK-2206 exhibited different effects on TF expression depending on the cell type, indicating that Akt phosphorylation may not consistently regulate TF expression. Overall, this study provides insights into the potential therapeutic use of statins in targeting tumour growth and coagulation abnormalities in canine HSA. Further research is warranted to fully elucidate the underlying mechanisms and clinical applications of statins in canine HSA treatment.

Hepatocyte-independent PAR1-biased signaling controls liver pathology in experimental obesity

BACKGROUND

Protease-activated receptor-1 (PAR1) has emerged as an important link between coagulation and the complications of obesity including metabolic dysfunction-associated steatotic liver disease (MASLD). PAR1 is expressed by various cells and cleaved by different proteases to generate unique tethered agonists that activate distinct signaling pathways. Mice expressing PAR1 with an R41Q mutation have disabled canonical thrombin-mediated signaling, whereas R46Q mice express PAR1 resistant to noncanonical signaling by activated protein C.

METHODS

Mice with whole body and hepatocyte-selective PAR1 deficiency as well as PAR1 R41Q and R46Q mice were fed a high-fat diet (HFD) to induce MASLD.

RESULTS

HFD-fed R41Q mice displayed reduced hepatic steatosis and liver/body weight ratio. In contrast, HFD-fed R46Q mice displayed increased relative liver weight and hepatic steatosis alongside increased serum alanine aminotransferase activity. Surprisingly, despite the distinct impact of PAR1 mutations on steatosis, selective deletion of PAR1 in hepatocytes had no impact. To evaluate a viable PAR1-targeted approach, mice with HFD-induced obesity were treated with the allosteric PAR1 modulator NRD-21, which inhibits canonical PAR1 inflammatory signaling but promotes PAR1 protective, noncanonical anti-inflammatory signaling. NRD-21 treatment reduced plasma tumor necrosis factor-alpha, serum alanine aminotransferase activity, hepatic steatosis, and insulin resistance (Homeostatic Model Assessment for Insulin Resistance) but increased plasma active glucagon-like peptide-1.

CONCLUSION

The results suggest that nonhepatocellular canonical PAR1 cleavage drives MASLD in obese mice and provide translational proof-of-concept that selective pharmacologic modulation of PAR1 yields multiple metabolic benefits in experimental obesity.

Mitigating Vascular Inflammation by Mimicking AIBP Mechanisms: A New Therapeutic End for Atherosclerotic Cardiovascular Disease

Atherosclerosis, characterized by the accumulation of lipoproteins and lipids within the vascular wall, underlies a heart attack, stroke, and peripheral artery disease. Endothelial inflammation is the primary component driving atherosclerosis, promoting leukocyte adhesion molecule expression (e.g., E-selectin), inducing chemokine secretion, reducing the production of nitric oxide (NO), and enhancing the thrombogenic potential. While current therapies, such as statins, colchicine, anti-IL1β, and sodium-glucose cotransporter 2 (SGLT2) inhibitors, target systemic inflammation, none of them addresses endothelial cell (EC) inflammation, a critical contributor to disease progression. Targeting endothelial inflammation is clinically significant because it can mitigate the root cause of atherosclerosis, potentially preventing disease progression, while reducing the side effects associated with broader anti-inflammatory treatments. Recent studies highlight the potential of the APOA1 binding protein (AIBP) to reduce systemic inflammation in mice. Furthermore, its mechanism of action also guides the design of a potential targeted therapy against a particular inflammatory signaling pathway. This review discusses the unique advantages of repressing vascular inflammation or enhancing vascular quiescence and the associated benefits of reducing thrombosis. This approach offers a promising avenue for more effective and targeted interventions to improve patient outcomes.

Monocyte bioenergetics: An immunometabolic perspective in metabolic dysfunction-associated steatohepatitis

Monocytes (Mos) are crucial in the evolution of metabolic dysfunction-associated steatotic liver disease (MASLD) to metabolic dysfunction-associated steatohepatitis (MASH), and immunometabolism studies have recently suggested targeting leukocyte bioenergetics in inflammatory diseases. Here, we reveal a peculiar bioenergetic phenotype in circulating Mos of patients with MASH, characterized by high levels of glycolysis and mitochondrial (mt) respiration. The enhancement of mt respiratory chain activity, especially complex II (succinate dehydrogenase [SDH]), is unbalanced toward the production of reactive oxygen species (ROS) and is sustained at the transcriptional level with the involvement of the AMPK-mTOR-PGC-1α axis. The modulation of mt activity with dimethyl malonate (DMM), an SDH inhibitor, restores the metabolic profile and almost abrogates cytokine production. Analysis of a public single-cell RNA sequencing (scRNA-seq) dataset confirms that in murine models of MASH, liver Mo-derived macrophages exhibit an upregulation of mt and glycolytic energy pathways. Accordingly, the DMM injection in MASH mice contrasts Mo infiltration and macrophagic enrichment, suggesting immunometabolism as a potential target in MASH.

Advances in the study of vascular related protective effect of garlic (Allium sativum) extract and compounds

Garlic (Allium sativum) is a functional food containing multiple bioactive compounds that find widespread applications in culinary and medicinal practices. It consists of multiple chemical components, including allicin and alliin. This article offers a comprehensive review of the protective effects of garlic extracts and their active constituents on the vascular system. In vitro and in vivo experiments have shown that garlic extracts and their active ingredients possess various bioactive properties. These substances demonstrate beneficial effects on blood vessels by demonstrating anti-inflammatory and antioxidant activities, inhibiting lipid accumulation and migration, preventing lipid peroxidation, promoting angiogenesis, reducing platelet aggregation, enhancing endothelial function, and inhibiting endothelial cell apoptosis. In clinical studies, garlic and its extracts have demonstrated their efficacy in managing vascular system diseases, including atherosclerosis, diabetes, and high cholesterol levels. In summary, these studies highlight the potential therapeutic roles and underlying mechanisms of garlic and its constituents in managing conditions like diabetes, atherosclerosis, ischemic diseases, and other vascular disorders.

Crosstalk of ferroptosis and oxidative stress in infectious diseases

Ferroptosis is a type of programmed cell death that pathogens can leverage to enhance their replication, transmission, and pathogenicity. Hosts typically combat pathogenic infections by utilizing oxidative stress as a defense mechanism. Nonetheless, some pathogens can trigger considerable oxidative stress while infecting, inducing an intense inflammatory response in the host's immune system and activating cell death. The process of ferroptosis is closely linked to oxidative stress, with their interaction exerting a substantial impact on the outcome of infectious diseases. This article presents an overview of the interrelated mechanisms of both Ferroptosis and oxidative stress in infectious diseases, identifying potential targets for treating such diseases in the context of their interaction.

Extracellular vesicles in venous thromboembolism and pulmonary hypertension

Venous thromboembolism (VTE) is a multifactorial disease, and pulmonary hypertension (PH) is a serious condition characterized by pulmonary vascular remodeling leading with increased pulmonary vascular resistance, ultimately leading to right heart failure and death. Although VTE and PH have distinct primary etiologies, they share some pathophysiologic similarities such as dysfunctional vasculature and thrombosis. In both conditions there is solid evidence that EVs derived from a variety of cell types including platelets, monocytes, endothelial cells and smooth muscle cells contribute to vascular endothelial dysfunction, inflammation, thrombosis, cellular activation and communications. However, the roles and importance of EVs substantially differ between studies depending on experimental conditions and parent cell origins of EVs that modify the nature of their cargo. Numerous studies have confirmed that EVs contribute to the pathophysiology of VTE and PH and increased levels of various EVs in relation with the severity of VTE and PH, confirming its potential pathophysiological role and its utility as a biomarker of disease severity and as potential therapeutic targets.

Tissue factor activates the coagulation cascade in mouse models of acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is associated with a high risk of bleeding and thrombosis. APL patients have an activated coagulation system, hyperfibrinolysis, and thrombocytopenia. APL cells express tissue factor (TF), a receptor and cofactor for factor VII/VIIa. This study had 2 goals. Firstly, we measured biomarkers of coagulation and fibrinolysis activation as well as platelet counts and bleeding in both mouse xenograft and allograft models of APL. Secondly, we determined the effect of inhibiting TF on the activation of coagulation in these models. We observed increased levels of plasma thrombin-antithrombin complexes (TAT), D-dimer, and plasmin-antiplasmin complexes, reduced platelet counts, and increased tail bleeding in both mouse models of APL. Fibrinogen levels decreased in the xenograft model but not in the allograft model. In contrast, the red blood cell count decreased in the allograft model but not in the xenograft model. Inhibition of APL-derived human TF with an anti-human TF monoclonal antibody reduced the level of TAT, increased platelet count, and normalized tail bleeding in a xenograft model. Inhibition of all sources of TF (APL cells and host cells) in the allograft model with a rat anti-mouse TF monoclonal antibody decreased the levels of TAT but did not affect the platelet count. Our study demonstrates that TF plays a central role in the activation of coagulation in both the xenograft and allograft mouse models of APL. These APL mouse models can be used to investigate the mechanisms of coagulopathy and thrombocytopenia in APL.

Toll-like Receptors as Pro-Thrombotic Drivers in Viral Infections: A Narrative Review

Toll-like receptors (TLRs) have a critical role in the pathogenesis and disease course of viral infections. The induced pro-inflammatory responses result in the disturbance of the endovascular surface layer and impair vascular homeostasis. The injury of the vessel wall further promotes pro-thrombotic and pro-coagulatory processes, eventually leading to micro-vessel plugging and tissue necrosis. Moreover, TLRs have a direct role in the sensing of viruses and platelet activation. TLR-mediated upregulation of von Willebrand factor release and neutrophil, as well as macrophage extra-cellular trap formation, further contribute to (micro-) thrombotic processes during inflammation. The following review focuses on TLR signaling pathways of TLRs expressed in humans provoking pro-thrombotic responses, which determine patient outcome during viral infections, especially in those with cardiovascular diseases.

Cholesterol confers ferroptosis resistance onto myeloid-biased hematopoietic stem cells and prevents irradiation-induced myelosuppression

There is growing appreciation that hematopoietic alterations underpin the ubiquitous detrimental effects of metabolic disorders. The susceptibility of bone marrow (BM) hematopoiesis to perturbations of cholesterol metabolism is well documented, while the underlying cellular and molecular mechanisms remain poorly understood. Here we reveal a distinct and heterogeneous cholesterol metabolic signature within BM hematopoietic stem cells (HSCs). We further show that cholesterol directly regulates maintenance and lineage differentiation of long-term HSCs (LT-HSCs), with high levels of intracellular cholesterol favoring maintenance and myeloid bias of LT-HSCs. During irradiation-induced myelosuppression, cholesterol also safeguards LT-HSC maintenance and myeloid regeneration. Mechanistically, we unravel that cholesterol directly and distinctively enhances ferroptosis resistance and boosts myeloid but dampens lymphoid lineage differentiation of LT-HSCs. Molecularly, we identify that SLC38A9-mTOR axis mediates cholesterol sensing and signal transduction to instruct lineage differentiation of LT-HSCs as well as to dictate ferroptosis sensitivity of LT-HSCs through orchestrating SLC7A11/GPX4 expression and ferritinophagy. Consequently, myeloid-biased HSCs are endowed with a survival advantage under both hypercholesterolemia and irradiation conditions. Importantly, a mTOR inhibitor rapamycin and a ferroptosis inducer imidazole ketone erastin prevent excess cholesterol-induced HSC expansion and myeloid bias. These findings unveil an unrecognized fundamental role of cholesterol metabolism in HSC survival and fate decisions with valuable clinical implications.

Ferroptosis and multi-organ complications in COVID-19: mechanisms and potential therapies

COVID-19 is an infectious disease caused by SARS-CoV-2, with respiratory symptoms as primary manifestations. It can progress to severe illness, leading to respiratory failure and multiple organ dysfunction. Recovered patients may experience persistent neurological, respiratory, or cardiovascular symptoms. Mitigating the multi-organ complications of COVID-19 has been highlighted as a crucial part of fighting the epidemic. Ferroptosis is a type of cell death linked to altered iron metabolism, glutathione depletion, glutathione peroxidase 4 (GPX4) inactivation, and increased oxidative stress. Cell death can prevent virus replication, but uncontrolled cell death can also harm the body. COVID-19 patients with multi-organ complications often exhibit factors related to ferroptosis, suggesting a possible connection. Ferroptosis inhibitors can resist SARS-CoV-2 infection from damaging vital organs and potentially reduce COVID-19 complications. In this paper, we outline the molecular mechanisms of ferroptosis and, based on this, discuss multi-organ complications in COVID-19, then explore the potential of ferroptosis inhibitors as a supplementary intervention for COVID-19. This paper will provide a reference for the possible treatment of SARS-CoV-2 infected disease to reduce the severity of COVID-19 and its subsequent impact.

Inflammasome activation mediated by oxidised low-density lipoprotein in patients with sleep apnoea and early subclinical atherosclerosis

BACKGROUND

Atherosclerosis is a common comorbidity of obstructive sleep apnoea (OSA) patients, caused by the interaction of dyslipidaemia and systemic inflammation. The OSA pro-inflammatory response is mediated by NLRP3 inflammasome activation, which requires a priming signal mediated by intermittent hypoxia (IH) and an activation signal provided by soluble stimulus present in plasma. Our objectives were to study oxidised low-density lipoprotein (oxLDL) expression in OSA patients with or without early subclinical atherosclerosis (eSA) as well as its contribution to NLRP3 activation and tissue factor (TF) release.

METHODS

We analysed oxLDL, key components of the NLRP3 inflammasome cascade and TF in plasma and monocytes from OSA patients and non-apnoeic subjects, with or without eSA as determined by increased carotid intima-media thickness without the appearance of atherosclerotic plaques. The oxLDL contribution to NLRP3 inflammasome activation was assessed using in vitro models.

RESULTS

High levels of oxLDL were identified in plasma from OSA patients, particularly in those with eSA, as well as an overexpression of NLRP3 cascade components and TF. Furthermore, in vitro models showed that both oxLDL and plasma from OSA patients with eSA act synergistically with IH as a priming and activation signal of NLRP3 that enhances the inflammatory response, pyroptosis and TF release.

CONCLUSIONS

OSA patients with eSA exhibit NLRP3 activation by IH and the presence of oxLDL capable of releasing TF, constituting a pathway for the interaction between dyslipidaemia and systemic inflammation in the development of atherosclerotic lesions.

HuR inhibition reduces post-ischemic cardiac remodeling by dampening acute inflammatory gene expression and the innate immune response

Myocardial ischemia/reperfusion (I/R) injury and the resulting cardiac remodeling is a common cause of heart failure. The RNA binding protein Human Antigen R (HuR) has been previously shown to reduce cardiac remodeling following both I/R and cardiac pressure overload, but the full extent of the HuR-dependent mechanisms within cells of the myocardium have yet to be elucidated. In this study, we applied a novel small molecule inhibitor of HuR to define the functional role of HuR in the acute response to I/R injury and gain a better understanding of the HuR-dependent mechanisms during post-ischemic myocardial remodeling. Our results show an early (two hours post-I/R) increase in HuR activity that is necessary for early inflammatory gene expression by cardiomyocytes in response to I/R. Surprisingly, despite the reductions in early inflammatory gene expression at two hours post-I/R, HuR inhibition has no effect on initial infarct size at 24-hours post-I/R. However, in agreement with previously published work, we do see a reduction in pathological remodeling and preserved cardiac function at two weeks post-I/R upon HuR inhibition. RNA-sequencing analysis of neonatal rat ventricular myocytes (NRVMs) at two hours post-LPS treatment to model damage associated molecular pattern (DAMP)-mediated activation of toll like receptors (TLRs) demonstrates a broad HuR-dependent regulation of pro-inflammatory chemokine and cytokine gene expression in cardiomyocytes. We show that conditioned media from NRVMs pre-treated with HuR inhibitor loses the ability to induce inflammatory gene expression in bone marrow derived macrophages (BMDMs) compared to NRVMs treated with LPS alone. Functionally, HuR inhibition in NRVMs also reduces their ability to induce endocrine migration of peripheral blood monocytes in vitro and reduces post-ischemic macrophage infiltration to the heart in vivo. In summary, these results suggest a HuR-dependent expression of pro-inflammatory gene expression by cardiomyocytes that leads to subsequent monocyte recruitment and macrophage activation in the post-ischemic myocardium.

Statins and Hemostasis: Therapeutic Potential Based on Clinical Evidence

Hemostasis preserves blood fluidity and prevents its loss after vessel injury. The maintenance of blood fluidity requires a delicate balance between pro-coagulant and fibrinolytic status. Endothelial cells (ECs) in the inner face of blood vessels maintain hemostasis through balancing anti-thrombotic and pro-fibrinolytic activities. Dyslipidemias are linked to hemostatic alterations. Thus, it is necessary a better understanding of the underlying mechanisms linking hemostasis with dyslipidemia. Statins are drugs that decrease cholesterol levels in the blood and are the gold standard for treating hyperlipidemias. Statins can be classified into natural and synthetic molecules, approved for the treatment of hypercholesterolemia. The classical mechanism of action of statins is by competitive inhibition of a key enzyme in the synthesis pathway of cholesterol, the HMG-CoA reductase. Statins are frequently administrated by oral ingestion and its interaction with other drugs and food supplements is associated with altered bioavailability. In this review we deeply discuss the actions of statins beyond the control of dyslipidemias, focusing on the actions in thrombotic modulation, vascular and cardiovascular-related diseases, metabolic diseases including metabolic syndrome, diabetes, hyperlipidemia, and hypertension, and chronic diseases such as cancer, chronic obstructive pulmonary disease, and chronic kidney disease. Furthermore, we were prompted to delved deeper in the molecular mechanisms by means statins regulate coagulation acting on liver, platelets, and endothelium. Clinical evidence show that statins are effective regulators of dyslipidemia with a high impact in hemostasis regulation and its deleterious consequences. However, studies are required to elucidate its underlying molecular mechanism and improving their therapeutical actions.

Tissue Factor, Thrombosis, and Chronic Kidney Disease

Coagulation abnormalities are common in chronic kidney disease (CKD). Tissue factor (TF, factor III) is a master regulator of the extrinsic coagulation system, activating downstream coagulation proteases, such as factor Xa and thrombin, and promoting fibrin formation. TF and coagulation proteases also activate protease-activated receptors (PARs) and are implicated in various organ injuries. Recent studies have shown the mechanisms by which thrombotic tendency is increased under CKD-specific conditions. Uremic toxins, such as indoxyl sulfate and kynurenine, are accumulated in CKD and activate TF and coagulation; in addition, the TF-coagulation protease-PAR pathway enhances inflammation and fibrosis, thereby exacerbating renal injury. Herein, we review the recent research studies to understand the role of TF in increasing the thrombotic risk and CKD progression.

Immune and inflammatory mechanisms of abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a life-threatening cardiovascular disease. Immune-mediated infiltration and a destruction of the aortic wall during AAA development plays significant role in the pathogenesis of this disease. While various immune cells had been found in AAA, the mechanisms of their activation and function are still far from being understood. A better understanding of mechanisms regulating the development of aberrant immune cell activation in AAA is essential for the development of novel preventive and therapeutic approaches. In this review we summarize current knowledge about the role of immune cells in AAA and discuss how pathogenic immune cell activation is regulated in this disease.

Evaluation of hemostasis disorders using the thrombodynamic test in patients with chronic glomerulonephritis with nephrotic syndrome

Background. Nephrotic syndrome (NS) is accompanied by a risk of thrombotic complications due to hypercoagulability. Routine laboratory tests are not sensitive enough to detect these disorders, and therefore the use of integral coagulation tests, including a new thrombodynamic test (TT) in patients with NS, is of high relevance. Aim. Using a TT to determine hemostasis disorders in patients with chronic glomerulonephritis (CGN) with NS. Materials and methods. The study included 49 patients with CGN, mean age 37 years, of which 25 (51%) women and 24 (49%) men. Of all the examined patients, 20 (40.8%) of people had NS, 29 (59.2%) had no NS. The process of clot formation was assessed by TT. Results. According to TT, 30% (6/20) of patients with NS and 13.7% (4/29) of patients without NS have hypercoagulation with changes in parameters that go beyond the reference values. In patients with NS, an increase in clot density (D), clot formation rate (V) and clot size (CS) was found, especially when albumin decreased below 25 g/l. Negative correlations were found between the levels of albumin, creatinine and clot density (D), which reflects the level of hyperfibrinogenemia, the rate of clot formation (V) and the integral index of coagulation (CS). The results indicate mainly the activation of the plasma hemostasis due to the internal coagulation pathway. However, the correlation of Tlag (delay time for the onset of clot formation after contact of blood plasma with the insert-activator) with serum cholesterol levels may also indicate activation of the extrinsic coagulation pathway. Conclusion. In CGN patients with NS, activation of the plasma hemostasis is noted, as evidenced by an increase in the rate of formation (V) and size of the clot (CS) after 30 minutes, as well as the density of the formed clot (D).

Trained Immunity as a Trigger for Atherosclerotic Cardiovascular Disease-A Literature Review

Atherosclerosis remains the leading cause of cardiovascular diseases and represents a primary public health challenge. This chronic state may lead to a number of life-threatening conditions, such as myocardial infarction and stroke. Lipid metabolism alterations and inflammation remain at the forefront of the pathogenesis of atherosclerotic cardiovascular disease, but the overall mechanism is not yet fully understood. Recently, significant effects of trained immunity on atherosclerotic plaque formation and development have been reported. An increased reaction to restimulation with the same stimulator is a hallmark of the trained innate immune response. The impact of trained immunity is a prominent factor in both acute and chronic coronary syndrome, which we outline in this review.

Coagulation and Endothelial Dysfunction Associated with NAFLD: Current Status and Therapeutic Implications

Non-alcoholic fatty liver disease (NAFLD) is closely related to insulin resistance, type 2 diabetes mellitus and obesity. It is considered a multisystem disease and there is a strong association with cardiovascular disease and arterial hypertension, which interfere with changes in the coagulation system. Coagulation disorders are common in patients with hepatic impairment and are dependent on the degree of liver damage. Through a review of the literature, we consider and discuss possible disorders in the coagulation cascade and fibrinolysis, endothelial dysfunction and platelet abnormalities in patients with NAFLD.

Thrombodynamics as a tool for monitoring hemostatic disorders in patients with chronic glomerulonephritis complicated by nephrotic syndrome

Nephrotic syndrome (NS) is associated with a high risk for venous and arterial thrombosis due to hypercoagulability. Integral tests designed to assess hemostasis can become an alternative for measuring hypercoagulability in patients with NS. STUDY OBJECTIVE: To assess hemostatic disorders in CGN patients complicated by NS using the thrombodynamics test. MATERIALS AND METHODS: The study included 60 adult patients with chronic glomerulonephritis (CGN), mean age 37 years, 31 (52%) women, and 29 (48%) men. Among all patients, 53 % of patients had NS, 47 % had no sign of NS. Hemostasis was assessed using the thrombodynamics test. The results were compared with biochemical parameters, which are usually associated with NS and renal dysfunction. RESULTS: According to the thrombodynamics test, CGN patients with NS demonstrated a tendency to hypercoagulability: increased rates of V (rate of clot growth), increased D (clot density), and increased CS (clot size) after 30 minutes. A positive correlation of these parameters with the serum albumin, creatinine levels, and glomerular filtration rate (GFR) indicates the influence of severe NS and renal dysfunction on the hemostasis activation in CGN patients with NS. CONCLUSION: According to the thrombodynamics test, CGN patients with NS demonstrate increased rates of clot formation, increased clot size after 30 minutes, and increased clot density due to secondary hemostasis activation. These changes positively correlate with the severity of hypoalbuminemia, hypercholesterolemia, and renal dysfunction in NS patients.

Pleiotropic Effects of PCSK9: Focus on Thrombosis and Haemostasis

The proprotein convertase subtilisin/keying 9 (PCSK9) is a serine protease that has gained importance in recent years as a drug target, mainly due to its effect on cholesterol metabolism in promoting the degradation of the low-density lipoprotein receptor (LDLR). However, this protease may also play an important role in lipid-independent reactions, including the process of thrombogenesis. Considering this, we reviewed the effects and implications of PCSK9 on platelet function and blood coagulation. PCSK9 knockout mice exhibited reduced platelet activity and developed less agonist-induced arterial thrombi compared to the respective control animals. This is in line with known research that elevated blood levels of PCSK9 are associated with an increased platelet reactivity and total number of circulating platelets in humans. Moreover, PCSK9 also has an effect on crucial factors of the coagulation cascade, such as increasing factor VIII plasma levels, since the degradation of this blood clotting factor is promoted by the LDLR. The aforementioned pleiotropic effects of the PCSK9 are important to take into account when evaluating the clinical benefit of PCSK9 inhibitors.

Aberrant stromal tissue factor localisation and mycolactone-driven vascular dysfunction, exacerbated by IL-1β, are linked to fibrin formation in Buruli ulcer lesions

Buruli ulcer (BU) is a neglected tropical disease caused by subcutaneous infection with Mycobacterium ulcerans and its exotoxin mycolactone. BU displays coagulative necrosis and widespread fibrin deposition in affected skin tissues. Despite this, the role of the vasculature in BU pathogenesis remains almost completely unexplored. We hypothesise that fibrin-driven ischemia can be an ‘indirect’ route to mycolactone-dependent tissue necrosis by a mechanism involving vascular dysfunction. Here, we tracked >900 vessels within contiguous tissue sections from eight BU patient biopsies. Our aim was to evaluate their vascular and coagulation biomarker phenotype and explore potential links to fibrin deposition. We also integrated this with our understanding of mycolactone’s mechanism of action at Sec61 and its impact on proteins involved in maintaining normal vascular function. Our findings showed that endothelial cell dysfunction is common in skin tissue adjacent to necrotic regions. There was little evidence of primary haemostasis, perhaps due to mycolactone-dependent depletion of endothelial von Willebrand factor. Instead, fibrin staining appeared to be linked to the extrinsic pathway activator, tissue factor (TF). There was significantly greater than expected fibrin staining around vessels that had TF staining within the stroma, and this correlated with the distance it extended from the vessel basement membrane. TF-induced fibrin deposition in these locations would require plasma proteins outside of vessels, therefore we investigated whether mycolactone could increase vascular permeability in vitro. This was indeed the case, and leakage was further exacerbated by IL-1β. Mycolactone caused the loss of endothelial adherens and tight junctions by the depletion of VE-cadherin, TIE-1, TIE-2 and JAM-C; all Sec61-dependent proteins. Taken together, our findings suggest that both vascular and lymphatic vessels in BU lesions become “leaky” during infection, due to the unique action of mycolactone, allowing TF-containing structures and plasma proteins into skin tissue, ultimately leading to local coagulopathy and tissue ischemia.

To date, the debilitating skin disease Buruli ulcer remains a public health concern and financial burden in low or middle-income countries, especially in tropical regions. Late diagnosis is frequent in remote areas, perhaps due to the painlessness of the disease. Hence patients often present with large, destructive opened ulcers leading to delayed wound closure or even lifelong disability. The infectious agent produces a toxin called mycolactone that drives the disease. We previously found evidence that the vascular system is disrupted by mycolactone in these lesions, and now we have further explored potential explanations for these findings by looking at the expression of vascular markers in BU. In a detailed analysis of patient skin punch biopsies, we identified distinct expression patterns of certain proteins and found that tissue factor, which initiates the so-called extrinsic pathway of blood clotting, is particularly important. Mycolactone is able to disrupt the barrier function of the endothelium, further aggravating the diseased phenotype, which may explain how clotting factors access the tissue. Altogether, such localised hypercoagulation in Buruli ulcer skin lesions may contribute to the development of the lesion.

PCSK9 Induces Tissue Factor Expression by Activation of TLR4/NFkB Signaling

Proprotein convertase subtilisin kexin 9 (PCSK9) increases LDL cholesterol (C) concentration by accelerating the hepatic degradation of the LDL receptor (R) thus promoting atherogenesis. The molecule, however, also exerts proinflammatory effects independent of circulating LDL-C by enhancing local cytokine production and activation of NFkB, a process that might involve Toll-like receptor 4 (TLR4), a crucial component of the innate immunity system. Tissue factor (TF), a glycoprotein which plays an essential role in coagulation and inflammation, is rapidly induced by circulating monocytes stimulated by proinflammatory agents through NFkB-dependent mechanisms. The aims of our study were (1) to assess whether PCSK9 may induce monocytic TF expression and (2) to evaluate whether the TLR4/NFkB signaling pathway may contribute to that effect. Experiments were carried out in peripheral blood mononuclear cells (PBMCs), THP-1 cells, and HEK293 cells transfected with plasmids encoding the human TLR4 complex. PCSK9 increased procoagulant activity (PCA), mRNA and TF protein expression in both PBMCs and THP-1 cultures. Pre-treatment with inhibitors of TLR4/NFkB signaling such as LPS-RS, CLI-095, and BAY 11-7082, downregulated PCSK9-induced TF expression. A similar effect was obtained by incubating cell cultures with anti-PCSK9 human monoclonal antibody. In TLR4-HEK293 cells, PCSK9 activated the TLR4/NFkB signaling pathway to an extent comparable to LPS, the specific agonist of TLR4s and quantitative confocal microscopy documented the colocalization of PCSK9 and TLR4s. In conclusion, PCSK9 induces TF expression through activation of TLR4/NFkB signaling.

Coagulation, Protease-Activated Receptors, and Diabetic Kidney Disease: Lessons from eNOS-Deficient Mice

Endothelial nitric oxide synthase (eNOS) dysfunction is known to exacerbate the progression and prognosis of diabetic kidney disease (DKD). One of the mechanisms through which this is achieved is that low eNOS levels are associated with hypercoagulability, which promotes kidney injury. In the extrinsic coagulation cascade, the tissue factor (factor III) and downstream coagulation factors, such as active factor X (FXa), exacerbate inflammation through activation of the protease-activated receptors (PARs). Recently, it has been shown that the lack of or reduced eNOS expression in diabetic mice, as a model of advanced DKD, increases renal tissue factor levels and PAR1 and 2 expression in their kidneys. Furthermore, pharmaceutical inhibition or genetic deletion of coagulation factors or PARs ameliorated inflammation in DKD in mice lacking eNOS. In this review, we summarize the relationship between eNOS, coagulation, and PARs and propose a novel therapeutic option for the management of patients with DKD.

Macrophage activation syndrome in COVID-19

The novel coronavirus epidemic is characterized by high rates of morbidity and relatively high mortality. Laboratory test results in patients include leukopenia, an increase in liver function tests and ferritin levels reaching hundreds, and sometimes thousands of units. These data remind us about the macrophage activation syndrome (MAC). Secondary hemophagocytic lymphohistiocytosis syndrome, MAC, which pathogenesis is based on a defect in the mechanisms of T-cell cytotoxicity and decreased level of natural killer cells associated with the defect in the perforin-encoding gene as well as hyperproduction of a number of cytokines – interleukin (IL)-1â, tumor necrosis factor-á, etc. by T-lymphocytes and histiocytes, indirectly leading to the activation of macrophages and production of proinflammatory cytokines, in particular IL-6 hyperproduction. MAC is one of "hyperferritinemic syndromes". These disorders have similar clinical and laboratory manifestations, and they also respond to similar treatments, suggesting that hyperferritinemia may be involved in the overall pathogenesis and is characterized by elevated ferritin level and cytokine storm. Despite the fact that data on the immune and inflammatory status in patients with COVID-19 have only started to appear, it is already clear that hyperinflammation and coagulopathy affect the disease severity and increase the risk of death in patients infected with SARS-CoV-2. Hence, understanding the pathogenesis of the novel coronavirus infection can help in its early diagnostics and treatment.

Effects of simvastatin on tissue factor pathway of blood coagulation in STATCOPE (Simvastatin in the prevention of COPD exacerbations) trial

BACKGROUND

Statins are widely used to lower lipids and reduce cardiovascular events. In vitro studies and small studies in patients with hyperlipidemias show statins inhibit tissue factor (TF) and blood coagulation mechanisms. We assessed the effects of simvastatin on TF and coagulation biomarkers in patients entered in STATCOPE, a multicenter, randomized, placebo-controlled trial of simvastatin (40 mg daily) versus placebo on exacerbation rates in patients with chronic obstructive pulmonary disease (COPD).

METHODS

In 227 patients (114 simvastatin, 113 placebo; mean [± standard error of the mean] age 62 ± 0.53 years, 44.5% women) we measured (baseline, and 6 and 12 months): whole blood membrane TF-procoagulant activity (TF-PCA) and plasma factors VIIa, VII, VIII, fibrinogen, TF antigen, tissue factor pathway inhibitor (TFPI), thrombin-antithrombin complexes (TAT), and D-dimer. We excluded patients with diabetes, cardiovascular disease, and those taking or requiring a statin.

RESULTS

In the statin group, there was a small increase in TF-PCA (from 25.18 ± 1.08 to 30.36 ± 1.10 U/ml; p = .03) over 12 months; factors VIIa and VIII, fibrinogen, TAT, and D-dimer did not change. Plasma TFPI (from 52.4 ± 1.75 to 44.7 ± 1.78 ng/ml; p < .0001) and FVIIC (1.23 ± 0.04 to 1.15 ± 0.03 U/ml; p = .03) decreased and correlated with total cholesterol levels. No changes in biomarkers were observed with placebo.

CONCLUSIONS

In contrast to previous studies on statins, in COPD patients without diabetes, cardiovascular disease, or requiring a statin treatment, simvastatin (40 mg per day) did not decrease TF or factors VIIa and VIII, fibrinogen, TAT, or D-dimer. The decreases in TFPI and factor VII reflect the decrease in serum lipids.

Myeloid cell-derived coagulation tissue factor is associated with renal tubular damage in mice fed an adenine diet

Patients with chronic kidney disease (CKD) commonly exhibit hypercoagulability. Increased levels of uremic toxins cause thrombogenicity by increasing tissue factor (TF) expression and activating the extrinsic coagulation cascade. TF is induced in monocytes and macrophages under pathological conditions, such as inflammatory diseases. However, the role of monocyte myeloid cell TF in CKD progression remains unclear. We aimed to clarify this issue, and the present study found that patients with CKD had elevated levels of D-dimer, a marker of fibrin degradation, which was associated with decreased estimated glomerular filtration rate and increased serum levels of uremic toxins, such as indoxyl sulfate. In vitro studies showed that several uremic toxins increased cellular TF levels in monocytic THP-1 cells. Mice with TF specifically deleted in myeloid cells were fed an adenine diet to cause uremic kidney injury. Myeloid TF deletion reduced tubular injury and pro-inflammatory gene expression in the kidneys of adenine-induced CKD but did not improve renal function as measured by plasma creatinine or blood urea nitrogen. Collectively, our findings suggest a novel concept of pathogenesis of coagulation-mediated kidney injury, in which elevated TF levels in monocytes under uremic conditions is partly involved in the development of CKD.

Drug repurposing for hyperlipidemia associated disorders: An integrative network biology and machine learning approach

Hyperlipidemia causes diseases like cardiovascular disease, cancer, Type II Diabetes and Alzheimer's disease. Drugs that specifically target HL associated diseases are required for treatment. 34 KEGG pathways targeted by lipid lowering drugs were used to construct a directed protein-protein interaction network and driver nodes were determined using CytoCtrlAnalyser plugin of Cytoscape 3.6. The involvement of driver nodes of HL in other diseases was verified using GWAS. The central nodes of the network and 34 overrepresented pathways had a critical role in Hyperlipidemia. The PI3K-AKT signalling pathway, non-essentiality, non-centrality and approved drug target status were the predominant features of the driver nodes. Next, a Random Forest classifier was trained on 1445 molecular descriptors calculated using PaDEL for 50 approved lipid lowering and 84 lipid raising drugs as the positive and negative training set respectively. The classifier showed average accuracy of 76.8 % during 5-fold cross validation with AUC of 0.79 ± 0.06 for the ROC curve. The classifier was applied to select molecules with favourable properties for lipid lowering from the 130 approved drugs interacting with the identified driver nodes. We have integrated diverse network data and machine learning to predict repurposing of nine drugs for treatment of HL associated diseases.

Low-density lipoproteins cause atherosclerotic cardiovascular disease: pathophysiological, genetic, and therapeutic insights: a consensus statement from the European Atherosclerosis Society Consensus Panel

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The role of iron in the pathogenesis of COVID-19 and possible treatment with lactoferrin and other iron chelators

Iron overload is increasingly implicated as a contributor to the pathogenesis of COVID-19. Indeed, several of the manifestations of COVID-19, such as inflammation, hypercoagulation, hyperferritinemia, and immune dysfunction are also reminiscent of iron overload. Although iron is essential for all living cells, free unbound iron, resulting from iron dysregulation and overload, is very reactive and potentially toxic due to its role in the generation of reactive oxygen species (ROS). ROS react with and damage cellular lipids, nucleic acids, and proteins, with consequent activation of either acute or chronic inflammatory processes implicated in multiple clinical conditions. Moreover, iron-catalyzed lipid damage exerts a direct causative effect on the newly discovered nonapoptotic cell death known as ferroptosis. Unlike apoptosis, ferroptosis is immunogenic and not only leads to amplified cell death but also promotes a series of reactions associated with inflammation. Iron chelators are generally safe and are proven to protect patients in clinical conditions characterized by iron overload. There is also an abundance of evidence that iron chelators possess antiviral activities. Furthermore, the naturally occurring iron chelator lactoferrin (Lf) exerts immunomodulatory as well as anti-inflammatory effects and can bind to several receptors used by coronaviruses thereby blocking their entry into host cells. Iron chelators may consequently be of high therapeutic value during the present COVID-19 pandemic.

Efficacy of nobiletin in improving hypercholesterolemia and nonalcoholic fatty liver disease in high-cholesterol diet-fed mice

BACKGROUND/OBJECTIVES

Nobiletin (NOB), a citrus flavonoid, is reported to have beneficial effects on cardiovascular and metabolic health. However, there is limited research investigating the effect of long-term supplementation with low-dose NOB on high-cholesterol diet (HCD)-induced hypercholesterolemia and non-obese nonalcoholic fatty liver disease (NAFLD). Therefore, we investigated the influence of NOB on hypercholesterolemia and NAFLD in HCD-fed mice.

SUBJECTS/METHODS

C57BL/6J mice were fed a normal diet (ND) or HCD (35 kcal% fat, 1.25% cholesterol, 0.5% cholic acid) with or without NOB (0.02%) for 20 weeks.

RESULTS

HCD feeding markedly reduced the final body weight compared to ND feeding, with no apparent energy intake differences. NOB supplementation suppressed HCD-induced weight loss without altering energy intake. Moreover, NOB significantly decreased the total cholesterol (TC) levels and the low-density lipoprotein (LDL)/very-LDL-cholesterol to TC ratio, and increased the high-density lipoprotein-cholesterol/TC ratio in plasma, compared to those for HCD feeding alone. The plasma levels of inflammatory and atherosclerosis markers (C-reactive protein, oxidized LDL, interleukin [IL]-1β, IL-6, and plasminogen activator inhibitor-1) were significantly lower, whereas those of anti-atherogenic adiponectin and paraoxonase were higher in the NOB-supplemented group than in the HCD control group. Furthermore, NOB significantly decreased liver weight, hepatic cholesterol and triglyceride contents, and lipid droplet accumulation by inhibiting messenger RNA expression of hepatic genes and activity levels of cholesterol synthesis-, esterification-, and fatty acid synthesis-associated enzymes, concomitantly enhancing fatty acid oxidation-related gene expression and enzyme activities. Dietary NOB supplementation may protect against hypercholesterolemia and NAFLD via regulation of hepatic lipid metabolism in HCD-fed mice; these effects are associated with the amelioration of inflammation and reductions in the levels of atherosclerosis-associated cardiovascular markers.

CONCLUSIONS

The present study suggests that NOB may serve as a potential therapeutic agent for the treatment of HCD-induced hypercholesterolemia and NAFLD.

Natural IgM antibodies inhibit microvesicle-driven coagulation and thrombosis

Thrombosis and its associated complications are a major cause of morbidity and mortality worldwide. Microvesicles (MVs), a class of extracellular vesicles, are increasingly recognized as mediators of coagulation and biomarkers of thrombotic risk. Thus, identifying factors targeting MV-driven coagulation may help in the development of novel antithrombotic treatments. We have previously identified a subset of circulating MVs that is characterized by the presence of oxidation-specific epitopes and bound by natural immunoglobulin M (IgM) antibodies targeting these structures. This study investigated whether natural IgM antibodies, which are known to have important anti-inflammatory housekeeping functions, inhibit the procoagulatory properties of MVs. We found that the extent of plasma coagulation is inversely associated with the levels of both free and MV-bound endogenous IgM. Moreover, the oxidation epitope-specific natural IgM antibody LR04, which recognizes malondialdehyde adducts, reduced MV-dependent plasmatic coagulation and whole blood clotting without affecting thrombocyte aggregation. Intravenous injection of LR04 protected mice from MV-induced pulmonary thrombosis. Of note, LR04 competed the binding of coagulation factor X/Xa to MVs, providing a mechanistic explanation for its anticoagulatory effect. Thus, our data identify natural IgM antibodies as hitherto unknown modulators of MV-induced coagulation in vitro and in vivo and their prognostic and therapeutic potential in the management of thrombosis.

The Impact of Dabigatran Treatment on Sinusoidal Protection Against Hepatic Ischemia/Reperfusion Injury in Mice

Thrombin is a key player in the coagulation cascade, and it is attracting much attention as a promotor of cellular injured signaling. In ischemia/reperfusion injury (IRI), which is a severe complication of liver transplantation, thrombin may also promote tissue damage. The aim of this study is to reveal whether dabigatran, a direct thrombin inhibitor, can attenuate hepatic IRI with focusing on a protection of sinusoidal endothelial cells (SECs). Both clinical patients who underwent hepatectomy and in vivo mice model of 60-minute hepatic partial-warm IRII, thrombin generation was evaluated before and after IRI. In next study, IRI mice were treated with or without dabigatran. In addition, hepatic SECs and hepatocytes pretreated with or without dabigatran were incubated in hypoxia/reoxygenation (H-R) environment in vitro. Thrombin generation evaluated by thrombin-antithrombin complex (TAT) was significantly enhanced after IRI in the clinical study and in vivo study. Thrombin exacerbated lactate dehydrogenase cytotoxicity levels in a dose-dependent manner in vitro. In an IRI model of mice, dabigatran treatment significantly improved liver histological damage, induced sinusoidal protection, and provided both antiapoptotic and anti-inflammatory effects. Furthermore, dabigatran not only enhanced endogenous thrombomodulin (TM) but also reduced excessive serum high-mobility group box-1 (HMGB-1). In H-R models of SECs, not hepatocytes, pretreatment with dabigatran markedly attenuated H-R damage, enhanced TM expression in cell lysate, and decreased extracellular HMGB-1. The supernatant of SECs pretreated with dabigatran protected hepatocytes from H-R damage and cellular death. Thrombin exacerbated hepatic IRI, and excessive extracellular HMGB-1 caused severe inflammation-induced and apoptosis-induced liver damage. In this situation, dabigatran treatment improved vascular integrity via sinusoidal protection and degraded HMGB-1 by endogenous TM enhancement on SECs, greatly ameliorating hepatic IRI.

Potential Role of Antioxidant and Anti-Inflammatory Therapies to Prevent Severe SARS-Cov-2 Complications

The coronavirus disease 2019 (COVID-19) pandemic is caused by a novel severe acute respiratory syndrome (SARS)-like coronavirus (SARS-CoV-2). Here, we review the molecular pathogenesis of SARS-CoV-2 and its relationship with oxidative stress (OS) and inflammation. Furthermore, we analyze the potential role of antioxidant and anti-inflammatory therapies to prevent severe complications. OS has a potential key role in the COVID-19 pathogenesis by triggering the NOD-like receptor family pyrin domain containing 3 inflammasome and nuclear factor-kB (NF-kB). While exposure to many pro-oxidants usually induces nuclear factor erythroid 2 p45-related factor2 (NRF2) activation and upregulation of antioxidant related elements expression, respiratory viral infections often inhibit NRF2 and/or activate NF-kB pathways, resulting in inflammation and oxidative injury. Hence, the use of radical scavengers like N-acetylcysteine and vitamin C, as well as of steroids and inflammasome inhibitors, has been proposed. The NRF2 pathway has been shown to be suppressed in severe SARS-CoV-2 patients. Pharmacological NRF2 inducers have been reported to inhibit SARS-CoV-2 replication, the inflammatory response, and transmembrane protease serine 2 activation, which for the entry of SARS-CoV-2 into the host cells through the angiotensin converting enzyme 2 receptor. Thus, NRF2 activation may represent a potential path out of the woods in COVID-19 pandemic.

Synergistic effects of magnesium ions and simvastatin on attenuation of high-fat diet-induced bone loss

Introduction

Magnesium (Mg) has a prophylactic potential against the onset of hyperlipidemia. Similar to statin, Mg is recommended as lipid-lowering medication for hypercholesterolemia and concomitantly exhibits an association with increased bone mass. The combination of statin with Mg ions (Mg²⁺) may be able to alleviate the high-fat diet (HFD)-induced bone loss and reduce the side-effects of statin. This study aimed to explore the feasibility of combined Mg²⁺ with simvastatin (SIM) for treating HFD-induced bone loss in mice and the involving mechanisms.

Materials and methods

C57BL/6 male mice were fed with a HFD or a normal-fat diet (NFD). Mice were intraperitoneally injected SIM and/or orally received water with additional Mg²⁺ until sacrificed. Enzyme-linked immunosorbent assay was performed to measure cytokines and cholesterol in serum and liver lysates. Bone mineral density (BMD) and microarchitecture were assessed by micro-computed tomography (μCT) in different groups. The adipogenesis in palmitate pre-treated HepG2 cells was performed under various treatments.

Results

μCT analysis showed that the trabecular bone mass was significantly lower in the HFD-fed group than that in NFD-fed group since week 8. The cortical thickness in HFD-fed group had a significant decrease at week 24, as compared with NFD-fed group. The combination of Mg²⁺ and SIM significantly attenuated the trabecular bone loss in HFD-fed mice via arresting the osteoclast formation and bone resorption. Besides, such combination also reduced the hepatocytic synthesis of cholesterol and inhibited matrix metallopeptidase 13 (Mmp13) mRNA expression in pre-osteoclasts.

Conclusions

The combination of Mg²⁺ and SIM shows a synergistic effect on attenuating the HFD-induced bone loss. Our current formulation may be a cost-effective alternative treatment to be indicated for obesity-related bone loss.

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High-fat diet-fed mouse has a susceptibility to lower trabecular bone mass as compared with that of normal-fat diet-fed mouse.

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The combination of Mg²⁺ and simvastatin attenuates the trabecular bone loss in high-fat diet-fed mice.

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The combination of Mg²⁺ and simvastatin reduces the hepatocytic synthesis of cholesterol.

Dabigatran mitigates cisplatin-mediated nephrotoxicity through down regulation of thrombin pathway

Introduction

Cisplatin (CDDP) nephrotoxicity is one of the most significant complications limiting its use in cancer therapy.

Objectives

This study investigated the pivotal role played by thrombin in CDDP-mediated nephrotoxicity. This work also aimed to clarify the possible preventive effect of Dabigatran (Dab), a direct thrombin inhibitor, on CDDP nephrotoxicity.

Methods

Animals were grouped as follow; normal control group, CDDP nephrotoxicity group, CDDP + Dab 15, and CDDP + Dab 25 groups. Four days following CDDP administration, blood and urine samples were collected to evaluate renal function. Moreover, tissue samples were collected from the kidney to determine apoptosis markers, oxidative stress and histopathological evaluation. An immunofluorescence analysis of tissue factor (TF), thrombin, protease-activated receptor-2 (PAR2), fibrin, pERK1/2 and P53 proteins expression was also performed.

Results

Thrombin, pERK, cleaved caspase-3, and oxidative stress markers were significantly elevated in CDDP-treated group. However, pretreatment of animals with either low or high doses of Dab significantly improved kidney function and decreased oxidative stress and apoptotic markers.

Conclusion

We conclude that thrombin is an important factor in the pathogenesis of CDDP kidney toxicity via activation of ERK1/2, P53 and caspase-3 pathway, which can be effectively blocked by Dab.

Recent advances in understanding, diagnosing and treating venous thrombosis

Focusing on the current state of the art, this article (a) describes recent advances in the understanding of the pathogenesis of venous thromboembolism (VTE), (b) discusses current approaches for the prevention, diagnosis and treatment of VTE, (c) outlines the role of aspirin for VTE prevention and treatment, and (d) highlights the unmet needs in VTE management and describes novel approaches to address them.

Modulation of the Innate Immune Response by Targeting Toll-like Receptors: A Perspective on Their Agonists and Antagonists

Toll-like receptors (TLRs) are a class of proteins that recognize pathogen-associated molecular patterns (PAMPs) and damaged-associated molecular patterns (DAMPs), and they are involved in the regulation of innate immune system. These transmembrane receptors, localized at the cellular or endosomal membrane, trigger inflammatory processes through either myeloid differentiation primary response 88 (MyD88) or TIR-domain-containing adapter-inducing interferon-β (TRIF) signaling pathways. In the last decades, extensive research has been performed on TLR modulators and their therapeutic implication under several pathological conditions, spanning from infections to cancer, from metabolic disorders to neurodegeneration and autoimmune diseases. This Perspective will highlight the recent discoveries in this field, emphasizing the role of TLRs in different diseases and the therapeutic effect of their natural and synthetic modulators, and it will discuss insights for the future exploitation of TLR modulators in human health.

Oxidized Low-Density Lipoprotein Induces Macrophage Production of Prothrombotic Microparticles

Background Activated vascular cells produce submicron prothrombotic and proinflammatory microparticle vesicles. Atherosclerotic plaques contain high levels of microparticles. Plasma microparticle levels increase during acute coronary syndromes and the thrombotic consequences of plaque rupture likely involve macrophage-derived microparticles (MΦMPs). The activation pathways that promote MΦMP production remain poorly defined. This study tested the hypothesis that signals implicated in atherogenesis also stimulate MΦMP production. Methods and Results We stimulated human primary MΦs with proinflammatory cytokines and atherogenic lipids, and measured MΦMP production by flow cytometry. Oxidized low-density lipoprotein (oxLDL; 25 µg/mL) induced MΦMP production in a concentration-dependent manner (293% increase; P<0.001), and these oxLDL MΦMP stimulatory effects were mediated by CD36. OxLDL stimulation increased MΦMP tissue factor content by 78% (P<0.05), and oxLDL-induced MΦMP production correlated with activation of caspase 3/7 signaling pathways. Salvionolic acid B, a CD36 inhibitor and a CD36 inhibitor antibody reduced oxLDL-induced MΦMP by 67% and 60%, respectively. Caspase 3/7 inhibition reduced MΦMP release by 52% (P<0.01) and caspase 3/7 activation increased MΦMP production by 208% (P<0.01). Mevastatin pretreatment (10 µM) decreased oxLDL-induced caspase 3/7 activation and attenuated oxLDL-stimulated MΦMP production and tissue factor content by 60% (P<0.01) and 43% (P<0.05), respectively. Conclusions OxLDL induces the production of prothrombotic microparticles in macrophages. This process depends on caspases 3 and 7 and CD36 and is inhibited by mevastatin pretreatment. These findings link atherogenic signaling pathways, inflammation, and plaque thrombogenicity and identify a novel potential mechanism for antithrombotic effects of statins independent of LDL lowering.

Tissue factor in atherosclerosis and atherothrombosis

Atherosclerosis is a chronic inflammatory disease that is characterized by the formation of lipid rich plaques in the wall of medium to large sized arteries. Atherothrombosis represents the terminal manifestation of this pathology in which atherosclerotic plaque rupture or erosion triggers the formation of occlusive thrombi. Occlusion of arteries and resultant tissue ischemia in the heart and brain causes myocardial infarction and stroke, respectively. Tissue factor (TF) is the receptor for the coagulation protease factor VIIa, and formation of the TF:factor VIIa complex triggers blood coagulation. TF is expressed at high levels in atherosclerotic plaques by both macrophage-derived foam cells and vascular smooth muscle cells, as well as extracellular vesicles derived from these cells. Importantly, TF mediated activation of coagulation is critically important for arterial thrombosis in the setting of atherosclerotic disease. The major endogenous inhibitor of the TF:factor VIIa complex is TF pathway inhibitor 1 (TFPI-1), which is also present in atherosclerotic plaques. In mouse models, increased or decreased expression of TFPI-1 has been found to alter atherosclerosis. This review highlights the contribution of TF-dependent activation of coagulation to atherthrombotic disease.

Significance of neutrophil microparticles in ischaemia-reperfusion: Pro-inflammatory effectors of endothelial senescence and vascular dysfunction

Endothelial senescence is an emerging cause of vascular dysfunction. Because microparticles are effectors of endothelial inflammation and vascular injury after ischaemia-reperfusion, we examined leucocyte-derived microparticles of spleen origin as possible contributors. Microparticles were generated from primary rat splenocytes by either lipopolysaccharide or phorbol-myristate-acetate/calcium ionophore, under conditions mimicking innate and adaptive immune responses. Incubation of primary porcine coronary endothelial cells with either type of microparticles, but not with those from unstimulated splenocytes, leads to a similar threefold raise in senescence-associated β-galactosidase activity within 48 hours, indicating accelerated senescence, to endothelial oxidative stress, and a fivefold and threefold increase in p21 and p16 senescence markers after 24 hours. After 12-hour incubation, the endothelial-dependent relaxation of coronary artery rings was reduced by 50%, at distinct optimal microparticle concentration. In vitro, microparticles were pro-thrombotic by up-regulating the local angiotensin system, by prompting tissue factor activity and a secondary generation of pro-coagulant endothelial microparticles. They initiated an early pro-inflammatory response by inducing phosphorylation of NF-κB, MAP kinases and Akt after 1 hour, and up-regulated VCAM-1 and ICAM-1 at 24 hours. Accordingly, VCAM-1 and COX-2 were also up-regulated in the coronary artery endothelium and eNOS down-regulated. Lipopolysaccharide specifically favoured the shedding of neutrophil- and monocyte-derived microparticles. A 80% immuno-depletion of neutrophil microparticles reduced endothelial senescence by 55%, indicating a key role. Altogether, data suggest that microparticles from activated splenocytes prompt early pro-inflammatory, pro-coagulant and pro-senescent responses in endothelial cells through redox-sensitive pathways. The control of neutrophil shedding could preserve the endothelium at site of ischaemia-reperfusion-driven inflammation and delay its dysfunction.

Pathological inflammation in patients with COVID-19: a key role for monocytes and macrophages

The COVID-19 pandemic caused by infection with SARS-CoV-2 has led to more than 200,000 deaths worldwide. Several studies have now established that the hyperinflammatory response induced by SARS-CoV-2 is a major cause of disease severity and death in infected patients. Macrophages are a population of innate immune cells that sense and respond to microbial threats by producing inflammatory molecules that eliminate pathogens and promote tissue repair. However, a dysregulated macrophage response can be damaging to the host, as is seen in the macrophage activation syndrome induced by severe infections, including in infections with the related virus SARS-CoV. Here we describe the potentially pathological roles of macrophages during SARS-CoV-2 infection and discuss ongoing and prospective therapeutic strategies to modulate macrophage activation in patients with COVID-19.

This Progress article from Merad and Martin examines our current understanding of the excessive inflammatory responses seen in patients with severe COVID-19. The authors focus on the emerging pathological roles of monocytes and macrophages and discuss the inflammatory pathways that are currently being targeted in the clinic.

Oxidized low-density lipoproteins induce tissue factor expression in T-lymphocytes via activation of lectin-like oxidized low-density lipoprotein receptor-1

AIMS

T-lymphocytes plays an important role in the pathophysiology of acute coronary syndromes. T-cell activation in vitro by pro-inflammatory cytokines may lead to functional tissue factor (TF) expression, indicating a possible contribution of immunity to thrombosis. Oxidized low-density lipoproteins (oxLDLs) are found abundantly in atherosclerotic plaques. We aimed at evaluating the effects of oxLDLs on TF expression in T cells and the role of the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1).

METHODS AND RESULTS

CD3+ cells were isolated from healthy volunteers. Gene, protein, and surface expression of TF, as well as of LOX-1, were assessed at different time-points after oxLDL stimulation. To determine whether oxLDL-induced TF was LOX-1 dependent, T cells were pre-incubated with an LOX-1 inhibiting peptide (L-RBP) or with an anti-LOX-1 blocking antibody. To exclude that TF expression was mediated by reactive oxygen species (ROS) generation, oxLDL-stimulated T cells were pre-incubated with superoxide dismutase + catalase or with 4-Hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol), an intracellular free radical scavenger. Finally, to determine if the observed findings in vitro may have a biological relevance, the presence of CD3+/TF+/LOX-1+ cells was evaluated by immunofluorescence in human carotid atherosclerotic lesions. oxLDLs induced functionally active TF expression in T cells in a dose- and time-dependent manner, independently on ROS generation. No effect was observed in native LDL-treated T cells. LOX-1 expression was also induced by oxLDLs in a time- and dose-dependent manner. Pre-incubation with L-RBP or anti-LOX-1 antibody almost completely inhibited oxLDL-mediated TF expression. Interestingly, human carotid plaques showed significant infiltration of CD3+ cells (mainly CD8+ cells), some of which were positive for both TF and LOX-1.

CONCLUSION

oxLDLs induce functional TF expression in T-lymphocytes in vitro via interaction of oxLDLs with LOX-1. Human carotid atherosclerotic plaques contain CD3+/CD8+cells that express both TF and LOX-1, indicating that also in patients these mechanisms may play an important role.

Antiapoptotic Effect by PAR-1 Antagonist Protects Mouse Liver Against Ischemia-Reperfusion Injury

BACKGROUND

Coagulation disturbances in several liver diseases lead to thrombin generation, which triggers intracellular injury via activation of protease-activated receptor-1 (PAR-1). Little is known about the thrombin/PAR-1 pathway in hepatic ischemia-reperfusion injury (IRI). The present study aimed to clarify whether a newly selective PAR-1 antagonist, vorapaxar, can attenuate liver damage caused by hepatic IRI, with a focus on apoptosis and the survival-signaling pathway.

METHODS

A 60-min hepatic partial-warm IRI model was used to evaluate PAR-1 expression in vivo. Subsequently, IRI mice were treated with or without vorapaxar (with vehicle). In addition, hepatic sinusoidal endothelial cells (SECs) pretreated with or without vorapaxar (with vehicle) were incubated during hypoxia-reoxygenation in vitro.

RESULTS

In naïve livers, PAR-1 was confirmed by immunohistochemistry and immunofluorescence analysis to be located on hepatic SECs, and IRI strongly enhanced PAR-1 expression. In IRI mice models, vorapaxar treatment significantly decreased serum transaminase levels, improved liver histological damage, reduced the number of apoptotic cells as evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling staining (median: 135 versus 25, P = 0.004), and induced extracellular signal-regulated kinase 1/2 (ERK 1/2) cell survival signaling (phospho-ERK/total ERK 1/2: 0.96 versus 5.34, P = 0.004). Pretreatment of SECs with vorapaxar significantly attenuated apoptosis and induced phosphorylation of ERK 1/2 in vitro (phospho-ERK/total ERK 1/2: 0.66 versus 3.04, P = 0.009). These changes were abolished by the addition of PD98059, the ERK 1/2 pathway inhibitor, before treatment with vorapaxar.

CONCLUSIONS

The results of the present study revealed that hepatic IRI induces significant enhancement of PAR-1 expression on SECs, which may be associated with suppression of survival signaling pathways such as ERK 1/2, resulting in severe apoptosis-induced hepatic damage. Thus, the selective PAR-1 antagonist attenuates hepatic IRI through an antiapoptotic effect by the activation of survival-signaling pathways.

Circulating Tissue Factor-Positive Procoagulant Microparticles in Patients with Type 1 Diabetes

AIM

To investigate the count of circulating tissue factor-positive (TF+) procoagulant microparticles (MPs) in patients with type 1 diabetes mellitus (T1DM).

METHODS

This case-control study included patients with T1DM and age and sex-matched healthy volunteers. The counts of phosphatidylserine-positive (PS+) MPs and TF+PS+MPs and the subgroups derived from different cell types were measured in the peripheral blood sample of the two groups using multicolor flow cytometric assay. We compared the counts of each MP between groups as well as the ratio of the TF+PS+MPs and PS+MPs (TF+PS+MPs/PS+MPs).

RESULTS

We recruited 36 patients with T1DM and 36 matched healthy controls. Compared with healthy volunteers, PS+MPs, TF+PS+MPs and TF+PS+MPs/PS+MPs were elevated in patients with T1DM (PS+MPs: 1078.5 ± 158.08 vs 686.84 ± 122.04/μL, P <0.001; TF+PS+MPs: 202.10 ± 47.47 vs 108.33 ± 29.42/μL, P <0.001; and TF+PS+MPs/PS+MPs: 0.16 ± 0.04 vs 0.19 ± 0.05, P = 0.004), mostly derived from platelet, lymphocytes and endothelial cells. In the subgroup analysis, the counts of total and platelet TF+PS+MPs were increased in patients with diabetic retinopathy (DR) and with higher HbA1c, respectively.

CONCLUSION

Circulating TF+PS+MPs and those derived from platelet, lymphocytes and endothelial cells were elevated in patients with T1DM.