Toll-Like Receptor 4-Dependent Platelet-Related Thrombosis in SARS-CoV-2 Infection.

BACKGROUND: SARS-CoV-2 is associated with an increased risk of venous and arterial thrombosis, but the underlying mechanism is still unclear. METHODS: We performed a cross-sectional analysis of platelet function in 25 SARS-CoV-2 and 10 healthy subjects by measuring Nox2 (NADPH oxidase 2)-derived oxidative stress and thromboxane B2, and investigated if administration of monoclonal antibodies against the S protein (Spike protein) of SARS-CoV-2 affects platelet activation. Furthermore, we investigated in vitro if the S protein of SARS-CoV-2 or plasma from SARS-CoV-2 enhanced platelet activation. RESULTS: Ex vivo studies showed enhanced platelet Nox2-derived oxidative stress and thromboxane B2 biosynthesis and under laminar flow platelet-dependent thrombus growth in SARS-CoV-2 compared with controls; both effects were lowered by Nox2 and TLR4 (Toll-like receptor 4) inhibitors. Two hours after administration of monoclonal antibodies, a significant inhibition of platelet activation was observed in patients with SARS-CoV-2 compared with untreated ones. In vitro study showed that S protein per se did not elicit platelet activation but amplified the platelet response to subthreshold concentrations of agonists and functionally interacted with platelet TLR4. A docking simulation analysis suggested that TLR4 binds to S protein via three receptor-binding domains; furthermore, immunoprecipitation and immunofluorescence showed S protein-TLR4 colocalization in platelets from SARS-CoV-2. Plasma from patients with SARS-CoV-2 enhanced platelet activation and Nox2-related oxidative stress, an effect blunted by TNF (tumor necrosis factor) α inhibitor; this effect was recapitulated by an in vitro study documenting that TNFα alone promoted platelet activation and amplified the platelet response to S protein via p47phox (phagocyte oxidase) upregulation. CONCLUSIONS: The study identifies 2 TLR4-dependent and independent pathways promoting platelet-dependent thrombus growth and suggests inhibition of TLR4. or p47phox as a tool to counteract thrombosis in SARS-CoV-2.

PAD4-Induced NETosis Via Cathepsin G-Mediated Platelet-Neutrophil Interaction in ChAdOx1 Vaccine-Induced Thrombosis-Brief Report.

BACKGROUND: Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare syndrome characterized by platelet anti-PF4 (platelet-activating antiplatelet factor 4)-related thrombosis. Platelet-neutrophil interaction has been suggested to play a role, but the underlying mechanism has not been fully elucidated. METHODS: The study included 10 patients with VITT after ChAdOx1 (chimpanzee adenovirus Oxford 1) nCoV-19 (Oxford-AstraZeneca) vaccine administration, 10 patients with ischemic stroke (IS), 10 patients with acute deep vein thrombosis, and 10 control subjects in whom blood levels of neutrophil extracellular traps (NETs), soluble TF (tissue factor), and thrombin generation were examined. Furthermore, we performed in vitro studies comparing the effect of serum from patients and controls on NETs formation. Finally, immunohistochemistry was performed in cerebral thrombi retrieved from a patients with VITT and 3 patients with IS. RESULTS: Compared with patients with IS, patients with deep vein thrombosis, controls, and patients with VITT had significantly higher blood values of CitH3 (citrullinated histone H3), soluble TF, D-dimer, and prothrombin fragment 1+2 (P<0.0001). Blood CitH3 significantly correlated with blood soluble TF (Spearman rank correlation coefficient=0.7295; P=0.0206) and prothrombin fragment 1+2 (Spearman rank correlation coefficient=0.6809; P<0.0350) in patients with VITT. Platelet-neutrophil mixture added with VITT plasma resulted in higher NETs formation, soluble TF and thrombin generation, and platelet-dependent thrombus growth under laminar flow compared with IS and deep vein thrombosis plasma; these effects were blunted by PAD4 (protein arginine deiminase 4) and cathepsin G inhibitors, anti-FcγRIIa (Fc receptor for IgG class IIa), and high doses of heparin. Immunohistochemistry analysis showed a more marked expression of PAD4 along with more diffuse neutrophil infiltration and NETs formation as well as TF and cathepsin expression in VITT thrombus compared with thrombi from patients with IS. CONCLUSIONS: Patients with VITT display enhanced thrombogenesis by PAD4-mediated NETs formation via cathepsin G-mediated platelet/neutrophil interaction.

Oleuropein, a Component of Extra Virgin Olive Oil, Improves Liver Steatosis and Lobular Inflammation by Lipopolysaccharides-TLR4 Axis Downregulation.

Gut-dysbiosis-induced lipopolysaccharides (LPS) translocation into systemic circulation has been suggested to be implicated in nonalcoholic fatty liver disease (NAFLD) pathogenesis. This study aimed to assess if oleuropein (OLE), a component of extra virgin olive oil, lowers high-fat-diet (HFD)-induced endotoxemia and, eventually, liver steatosis. An immunohistochemistry analysis of the intestine and liver was performed in (i) control mice (CTR; n = 15), (ii) high-fat-diet fed (HFD) mice (HFD; n = 16), and (iii) HFD mice treated with 6 µg/day of OLE for 30 days (HFD + OLE, n = 13). The HFD mice developed significant liver steatosis compared to the controls, an effect that was significantly reduced in the HFD + OLE-treated mice. The amount of hepatocyte LPS localization and the number of TLR4+ macrophages were higher in the HFD mice in the than controls and were lowered in the HFD + OLE-treated mice. The number of CD42b+ platelets was increased in the liver sinusoids of the HFD mice compared to the controls and decreased in the HFD + OLE-treated mice. Compared to the controls, the HFD-treated mice showed a high percentage of intestine PAS+ goblet cells, an increased length of intestinal crypts, LPS localization and TLR4+ expression, and occludin downregulation, an effect counteracted in the HFD + OLE-treated mice. The HFD-fed animals displayed increased systemic levels of LPS and zonulin, but they were reduced in the HFD + OLE-treated animals. It can be seen that OLE administration improves liver steatosis and inflammation in association with decreased LPS translocation into the systemic circulation, hepatocyte localization of LPS and TLR4 downregulation in HFD-induced mouse model of NAFLD.

Gut barrier dysfunction and endotoxemia in heart failure: A dangerous connubium?

Heart failure (HF) is a leading cause of death worldwide despite recent advances in pharmacological treatments. Gut microbiota dysbiosis and gut barrier dysfunction with consequent bacterial translocation and increased blood endotoxemia has gained much attention as one of the key pathogenetic mechanisms contributing to increased mortality of patients at risk or with cardiovascular disease. Indeed, increased blood levels of lipopolysaccharide (LPS), a glycolipid of outer membrane of gut gram-negative bacteria, have been detected in patients with diabetes, obesity and nonalcoholic fatty liver disease or in patients with established coronary disease such as myocardial infarction or atrial fibrillation, suggesting endotoxemia as aggravating factor via systemic inflammation and eventually vascular damage. Upon interaction with its receptor Toll-like receptor 4 (TLR4) LPS may, in fact, act at different cellular levels so eliciting formation of proinflammatory cytokines or exerting a procoagulant activity. Increasing body of evidence pointed to endotoxemia as factor potentially deteriorating the clinical course of patients with HF, that, in fact, is associated with gut dysbiosis-derived changes of gut barrier functionality and eventually bacteria or bacterial product translocation into systemic circulation. The aim of this review is to summarize current experimental and clinical evidence on the mechanisms linking gut dysbiosis-related endotoxemia with HF, its potential negative impact with HF progression, and the therapeutic strategies that can counteract endotoxemia.

Lipopolysaccharide induces platelet activation in HIV patients: the role of different viral load patterns.

OBJECTIVES: This study aimed to assess whether gut-derived lipopolysaccharide (LPS) could affect platelet function in HIV-1 patients with residual viral load. METHODS: In 23 HIV-1 patients on effective antiretroviral treatment, 10 treatment-naïve HIV-1 subjects and 20 healthy subjects (HS), LPS, zonulin, markers of platelet activation and oxidative stress were evaluated. In vitro, platelets from HS were exposed to plasma from HIV-1-infected treated and untreated patients. RESULTS: Compared with HS, LPS was higher in treated and treatment-naïve subjects with HIV-1 (7.7 ± 2.9, 80.9 ± 13.7 and 75.3 ± 22.6 pg/mL, P < 0.001 vs. HS) as well as serum zonulin (1.3 ± 0.5, 6.1 ± 1.5 and 5.3 ± 1.7 ng/mL, P < 0.001 vs. HS). LPS and zonulin were correlated in HIV patients (Spearman correlation coefficient (rS) = 0.73, P < 0.0001). Levels of soluble CD40 ligand (sCD40L), soluble P-selectin (sP-selectin) and thromboxane B2 (TxB2 ) were higher in HIV-1-treated and treatment-naïve subjects compared with HS as well as NADPH oxidase 2 (NOX2) activation and hydrogen peroxide (H2 O2 ) production. In vitro, sCD40L, sP-selectin and TxB2 production, NOX2 activation and p47phox phosphorylation were higher in platelets exposed to plasma from HIV-1 patients with different viral load compared with the exposure to plasma from HS. This effect was blunted in platelets pre-treated with TLR4 or TLR7 inhibitors. CONCLUSIONS: Low-grade endotoxaemia and persistent viraemia increase platelet function with a mechanism mediated by NOX2 in patients with HIV-1 infection.

Proprotein Convertase Subtilisin Kexin Type 9 Inhibitors Reduce Platelet Activation Modulating ox-LDL Pathways.

Background: Proprotein convertase subtilisin kexin type 9 inhibitors (PCSK9i) lower LDL-cholesterol and slow atherosclerosis preventing cardiovascular events. While it is known that circulating PCSK9 enhances platelet activation (PA) and that PCSK9i reduce it, the underlying mechanism is not still clarified. Methods: In a multicenter before-after study in 80 heterozygous familial hypercholesterolemia (HeFH) patients on treatment with maximum tolerated statin dose ± ezetimibe, PA, soluble-NOX2-derived peptide (sNOX2-dp), and oxidized-LDL (ox-LDL) were measured before and after six months of PCSK9i treatment. In vitro study investigates the effects of plasma from HeFH patients before and after PCK9i on PA in washed platelets (wPLTs) from healthy subjects. Results: Compared to baseline, PCSK9i reduced the serum levels of LDL-c, ox-LDL, Thromboxane (Tx) B2, sNOX2-dp, and PCSK9 (p < 0.001). The decrease of TxB2 correlates with that of ox-LDL, while ox-LDL reduction correlated with PCSK9 and sNOX2-dp delta. In vitro study demonstrated that wPLTs resuspended in plasma from HeFH after PCSK9i treatment induced lower PA and sNOX2-dp release than those obtained using plasma before PCSK9i treatment. This reduction was vanished by adding ox-LDL. ox-LDL-induced PA was blunted by CD36, LOX1, and NOX2 inhibition. Conclusions: PCSK9i treatment reduces PA modulating NOX2 activity and in turn ox-LDL formation in HeFH patients.

Environmental impacts of household appliances in Europe and scenarios for their impact reduction.

Assessing the environmental impact due to consumption of goods and services is a pivotal step towards achieving the sustainable development goal related to responsible production and consumption (i.e. SDG 12). Household appliances plays a crucial role and should be assessed in a systemic manner, namely considering all life cycle stages, technological efficiency, and affluence aspects. The present study assess the impact of such household appliances used in Europe, and tests scenarios of potential impact reduction at various scales. Life cycle assessment is applied to 14 different household appliances (ranging from dishwashers to television devices) selected to build a set of representative products, based on their economic value and diffusion in households in Europe. Related impacts are calculated with the Environmental Footprint method for calculating a Consumer Footprint "appliances" for the baseline year 2010. A number of scenarios encompassing eco-solutions on a technical level, changes in consumption pattern, behavioral changes, as well as the combination of all these aspects are run to estimate the Consumer Footprint related to household appliances for the year 2030, compared against this baseline scenario. The baseline Consumer Footprint is confirming the importance of the use phase in leading the impacts in almost all impact categories. Testing different scenarios concludes that there is a reduction of the impact for most of the categories (with up to 67% for the ozone depletion potential, and still around 35% for the global warming potential), while two of the here examined impact categories (i.e. land-use and mineral resource depletion) show an overall potential that is even negative - i.e. the results of all scenarios are higher than the ones of the 2010 baseline scenario. The increase in purchase and use of such appliances may offset energy efficiency benefits in some of the examined categories. Hence, the assessment of sustainability of appliances consumption should always include several scales, from the efficiency of the products (micro scale), to the improvement of the energy mix (meso scale), up to accounting for socio-economic drivers and patterns of consumption affecting the overall appliances stock (macro scale).

The consumer footprint: Monitoring sustainable development goal 12 with process-based life cycle assessment.

Sustainable and responsible production and consumption are at the heart of sustainable development, explicitly mentioned as one of the sustainable development goals (SDG12). Life cycle assessment, with its integrated holistic approach, is considered a reference method for the assessment of the environmental impact of production and consumption. This paper presents a study on the environmental impacts of final consumption in Europe in five areas of consumption: food, mobility, housing, household goods, and appliances. Based on the selection of a set of representative products to meet food, mobility, housing, and other consumers' needs, environmental impacts of products are assessed over their full life cycle: from raw material extraction to production, distribution, use, and end-of-life phase. Life cycle inventories of representative products are multiplied by consumption statistics to assess the impact of an average European citizen in 2010 and 2015. Impacts are assessed considering the sixteen impact categories of the Environmental Footprint method. Results reveal that food is the most relevant area of consumption driving environmental impacts. Use phase is the most important life cycle stage for many impact categories, especially for the areas of consumption housing, mobility, and appliances. For the areas of consumption food and household goods, the most important life cycle phase is related to upstream processes, which corresponds to agricultural activities for food and manufacturing of products components for household goods. Apart from the results, the paper includes a detailed discussion on further methodological improvements and research needs to make use of the Consumer Footprint as an indicator for monitoring SDG 12 and for supporting sustainable production and consumption policies.

Environmental impacts of household consumption in Europe: Comparing process-based LCA and environmentally extended input-output analysis.

The environmental impacts generated by household consumption are generally calculated through footprints, allocating the supply-chain impacts to the final consumers. This study compares the result of the Consumer Footprint indicator, aimed at assessing the impacts of household consumption in Europe, calculated with the two standard approaches usually implemented for footprint calculations: (i) a bottom-up approach, based on process-Life cycle assessment of a set of products and services representing household consumption, and (ii) a top-down approach, based on environmentally extended input-output tables (EXIOBASE 3). Environmental impacts are calculated considering 14 environmental impact categories out of the 16 included in the EF2017 impact assessment method. Both footprints show similar total values regarding climate change, freshwater eutrophication and fossil resource use, but in the meantime very large differences (more than a factor 2) regarding particulate matter, photochemical ozone formation, land use and mineral resource use. The exclusion of services in the bottom-up approach can explain only to some extent these differences. However, the two approaches converge in identifying food as the main driver of impact in most of the impact categories considered (with a generally lower contribution in top-down compared to bottom-up). Housing and mobility are relevant as well for some impact categories (e.g. particulate matter and fossil resource depletion). Some substances are identified as hotspot by both approaches, e.g. the emission of NH3 to air (for acidification and terrestrial eutrophication), of NOx to air (for acidification, marine and terrestrial eutrophication, and, to some extent, photochemical ozone formation), of P to water and to soil (for freshwater eutrophication) and of fossil CO2 to air (for climate change). Significant differences at the inventory side are key drivers for the differences in total impacts. These include: (i) differences in the intensity of emissions, (ii) differences in the coverage of elementary flows, (iii) differences in the level of detail relative to elementary flows. Overall, the key converging results from both approaches (in particular regarding most contributing areas of consumption and substances) can be considered as a robust basis to support the definition of policies aimed at reducing the environmental footprint of household consumption in Europe.

Glucocorticoids impair platelet thromboxane biosynthesis in community-acquired pneumonia.

Previous reports suggest that community-acquired pneumonia (CAP) is associated with an enhanced risk of myocardial infarction (MI) and that enhanced platelet activation may play a role. Aims of this study were to investigate if urinary excretion of 11-dehydro-thromboxane (Tx) B2, a reliable marker of platelet activation in vivo, was elevated in CAP and whether glucocorticoid administration reduced platelet activation. Three-hundred patients hospitalized for CAP were recruited and followed-up until discharge. Within the first 2 days from admission, urinary 11-dehydro-TxB2 and serum levels of methylprednisolone and betamethasone were measured. 11-Dehydro-TxB2 was also measured in a control group of 150 outpatients, matched for age, sex, and comorbidities. Finally, in-vitro studies were performed to assess if glucocorticoids affected platelet activation, at the same range of concentration found in the peripheral circulation of CAP patients treated with glucocorticoids. Compared to controls, CAP patients showed significantly higher levels of 11-dehydro-TxB2 (110 [69-151] vs. 163 [130-225] pg/mg creatinine; p < 0.001). During the in-hospital stay, 31 patients experienced MI (10%). A COX regression analysis showed that 11-dehydro-TxB2 independently predicted MI (p = .005). CAP patients treated with glucocorticoids showed significantly lower levels of 11-dehydro-TxB2 compared to untreated ones (147 [120-201] vs. 176 [143-250] pg/mg creatinine; p < 0.001). In vitro, glucocorticoids-treated platelets showed a dose-dependent decrease of ADP-induced platelet aggregation, TxB2 production, cPLA2 phosphorylation and arachidonic acid release from the platelet membrane. In conclusion, platelet TxB2 is overproduced in CAP patients and may be implicated in MI occurrence. Glucocorticoids reduce platelet release of TxB2 in vitro and urinary excretion of 11-dehydro-TxB2 in vivo and may be a novel tool to decrease platelet activation in this setting.

Oleuropein, a component of extra virgin olive oil, lowers postprandial glycaemia in healthy subjects.

AIMS: Extra virgin olive oil lowers postprandial glycaemia. We investigated if oleuropein, a component of extra virgin olive oil, exerts a similar effect on postprandial glycaemia and the underlying mechanism. METHODS: Twenty healthy subjects were randomly allocated in a cross-over design to 20 mg oleuropein or placebo immediately before lunch. Postprandial glycaemia along with blood insulin, dipeptidyl-peptidase-4 (DPP-4) and glucagon-like peptide-1 and oxidative stress, which included soluble NADPH oxidase-derived peptide activity (sNox2-dp), 8-iso-prostaglandin-2α and platelet p47phox phosphorylation, were analysed before and 2 h after meal. RESULTS: After 2 h, subjects who assumed oleuropein had significantly lower blood glucose, DPP-4 activity and higher insulin and glucagon-like peptide-1 compared to placebo. Furthermore, sNox2-dp, 8-iso-PGF2α and platelet p47phox phosphorylation were significantly lower in oleuropein- compared to placebo-treated subjects. DPP-4 significantly correlated with sNox2-dp [Spearman's rho (Rs) = 0.615; P < 0.001], p47phox phosphorylation (Rs = 0.435; P < 0.05) and 8-iso- prostaglandin-2α (Rs = 0.33; P < 0.05). In vitro study demonstrated that hydroxytyrosol, a metabolite of oleuropein, significantly reduced p47phox phosphorylation and isoprostane formation. CONCLUSIONS: These findings indicate that oleuropein improves postprandial glycaemic profile via hampering Nox2-derived oxidative stress.

Systematic analysis of secondary life cycle inventories when modelling agricultural production: A case study for arable crops.

Analysis of agricultural production with life cycle based methodologies is data demanding. To build comprehensive life cycle inventories, secondary datasets are commonly used when primary data are not available. However, different inventory data and modelling approaches are used to populate secondary datasets, leading to different results. The present study analyses the features of twelve secondary datasets to support datasets selection and proper interpretation of results. We assess twelve datasets for arable crop production in France, as modelled in three databases often used in the LCA field (Agri-footprint, ecoinvent and AGRIBALYSE). First, we compared system boundaries and general assumptions. Second, we focused on foreground systems comparing, inventory data, data sources and modelling approaches. Third, we performed a contribution analysis of impact assessment results to identify modelling choices that contribute most to differences in the results. Nine relevant elements were identified and assessed: definition of system boundaries and modelling of agricultural practices, characteristics of inventory data, agricultural operations, fertiliser application and fate, plant protection products application and fate, heavy metals inputs to the agricultural system and fate, irrigation assumptions, land use and transformation. The datasets differ greatly with respect to these elements. Hence, recommendations are drawn from the datasets comparison, supporting the selection of the datasets coherently with the goal and scope of a study and interpretation of results.

Risk of venous thromboembolism and arterial events in patients with hypoalbuminemia: a comprehensive meta-analysis of more than 2 million patients.

BACKGROUND: Albumin has antiplatelet and anticoagulant functions. Hypoalbuminemia, as defined by serum values of <3.5 g/dL, is associated with arterial thrombosis; its impact on venous thromboembolism (VTE) is unclear. OBJECTIVES: The objective of this meta-analysis is to assess the VTE risk in patients with hypoalbuminemia. METHODS: MEDLINE and EMBASE were searched up to January 2024 for observational studies and randomized trials reporting data of interest. Primary outcome was the risk of VTE, while secondary outcomes were myocardial infarction and stroke risk in patients with hypoalbuminemia versus those without hypoalbuminemia. The risk of bias was evaluated using Newcastle-Ottawa scale and Cochrane tool. Risk ratios (RRs) with 95% confidence intervals (CIs) were calculated in a random-effects model. RESULTS: Forty-three studies for a total of 2 531 091 patients (39 738 medical and 2 491 353 surgical) were included in primary analysis; 79.1% of the studies used 3.5 g/dL cut-off value for hypoalbuminemia definition. Follow-up duration was 30 days in 60.5% of studies. Patients with hypoalbuminemia had a higher risk of VTE (RR, 1.88; 95% CI, 1.66-2.13). RRs were similar in both medical (RR, 1.87; 95% CI, 1.53-2.27) and surgical patients (RR, 1.87; 95% CI, 1.61-2.16) and in patients with (RR, 1.86; 95% CI, 1.66-2.10) and without cancer (RR, 1.89; 95% CI, 1.47-2.44). Risk of myocardial infarction (RR, 1.88; 95% CI, 1.54-2.31) and stroke (RR, 1.77; 95% CI, 1.26-2.48) was higher in patients with hypoalbuminemia. CONCLUSION: Hypoalbuminemia is a risk factor for VTE in both medical and surgical patients irrespective of cancer coexistence. Serum albumin analysis may represent a simple and cheap tool to identify patients at VTE risk.

NOX2 as a Biomarker of Academic Performance: Evidence from University Students during Examination.

BACKGROUND: Cortisol levels, oxidative stress, and lower cerebral performance seem to be closely related. This study aimed to evaluate the question of whether exam stress affected oxidative stress and endothelial function parameters in the salivary samples of students. METHODS: A total of 114 healthy students were recruited. All students were subjected to a 21-item DASS questionnaire to assess perceived stress. Cortisol levels, biomarkers of oxidative stress, and endothelial function were evaluated at T0, during the semester, and T1, in the morning before the exam, in saliva samples. In vitro, HUVECs were stimulated with cortisol, and oxidative stress and endothelial function parameters were evaluated. RESULTS: At T1, cortisol levels were significantly increased compared with the levels during the semester. Moreover, exam results correlated inversely with the DASS score at T1. In addition, NOX2, H2O2 and endothelin-1 significantly increased, while NO bioavailability decreased. In vitro, HUVECs treatment with human cortisol determined the increase of oxidative stress and the decrease of endothelial function, in association with impaired eNOS phosphorylation. CONCLUSION: NOX2-mediated oxidative stress is a mechanism that could mediate cortisol-induced transient endothelial dysfunction during academic examination. Therefore, strategies to monitor or modulate oxidative stress could help students to reduce the impact of examination-related stress.

Association between endotoxemia and blood no in the portal circulation of cirrhotic patients: results of a pilot study.

Pathophysiology of portal vein thrombosis (PVT) in cirrhosis is still not entirely understood. Elevated levels of lipopolysaccharides (LPS) in portal circulation are significantly associated with hypercoagulation, increased platelet activation and endothelial dysfunction. The aim of the study was to investigate if LPS was associated with reduced portal venous flow, the third component of Virchow's triad, and the underlying mechanism. Serum nitrite/nitrate, as a marker of nitric oxide (NO) generation, and LPS were measured in the portal and systemic circulation of 20 patients with cirrhosis undergoing transjugular intrahepatic portosystemic shunt (TIPS) procedure; portal venous flow velocity (PVV) was also measured in each patient and correlated with NO and LPS levels. Serum nitrite/nitrate and LPS were significantly higher in the portal compared to systemic circulation; a significant correlation was found between LPS and serum nitrite/nitrate (R = 0.421; p < 0.01). Median PVV before and after TIPS was 15 cm/s (6-40) and 31 cm/s (14-79), respectively. Correlation analysis of PVV with NO and LPS showed a statistically significant negative correlation of PVV with portal venous NO concentration (R = - 0.576; p = 0.020), but not with LPS. In vitro study with endothelial cells showed that LPS enhanced endothelial NO biosynthesis, which was inhibited by L-NAME, an inhibitor of NO synthase, or TAK-242, an inhibitor of TLR4, the LPS receptor; this effect was accomplished by up-regulation of eNOS and iNOS. The study shows that in cirrhosis, endotoxemia may be responsible for reduced portal venous flow via overgeneration of NO and, therefore, contribute to the development of PVT.

Gut dysbiosis, endotoxemia and clotting activation: A dangerous trio for portal vein thrombosis in cirrhosis.

Liver cirrhosis (LC) is associated with portal venous thrombosis (PVT) in roughly 20% of cirrhotic patients but the underlying mechanism is still unclear. Low-grade endotoxemia by lipopolysaccharides (LPS), a component of outer gut microbiota membrane, is detectable in the portal circulation of LC and could predispose to PVT. LPS may translocate into systemic circulation upon microbiota dysbiosis-induced gut barrier dysfunction, that is a prerequisite for enhanced gut permeability and ensuing endotoxemia. Experimental and clinical studies provided evidence that LPS behaves a pro-thrombotic molecule so promoting clotting and platelet activation. Experiments conducted in the portal circulation of cirrhotic patients showed the existence of LPS-related enhanced thrombin generation as well as endothelial dysfunction, venous stasis, and platelet activation. The review will analyze 1) the pro-thrombotic role of endotoxemia in the context of LC 2) the biological plausibility linking endotoxemia with PVT and 3) the potentially interventional tools to lower endotoxemia and eventually hypercoagulation.

Gut dysbiosis-derived low-grade endotoxemia: A common soil for liver and cardiovascular disease.

Gut dysbiosis is characterized by bacteria overgrowth that ultimately leads to increased intestinal barrier permeability and bacteria or bacteria product translocation such as lipopolysaccharide (LPS) in the portal and eventually systemic circulation. Intestinal epithelial cells and hepatocytes encompass enzymatic armamentarium to counteract the LPS toxic effect, however impaired degradation results in LPS accumulation in hepatocytes and endothelial wall. Experimental and clinical study documented that in patients with liver disease, such as non-alcoholic fatty acid liver disease (NAFLD), low-grade endotoxemia by LPS is implicated in liver inflammation and thrombosis via interaction with its Toll-like receptor 4 (TLR4) expressed by hepatocytes and platelets. Furthermore, studies in patients with severe atherosclerosis documented that LPS localizes into atherosclerotic plaque in close association with activated macrophages expressing TLR4 suggesting a role for LPS in vascular inflammation, atherosclerotic progression, and thrombosis. Finally, LPS may directly interact with myocardial cells to induce electric and functional changes leading to atrial fibrillation or heart failure. This review will focus on experimental and clinical evidence suggesting low-grade endotoxemia as mechanism potentially accounting for vascular damage occurring at level of hepatic and systemic circulation and myocardial cells.