Microvascular Thrombosis and Liver Fibrosis Progression: Mechanisms and Clinical Applications

Strain- and sex-dependent variability in hepatic microcirculation and liver function in mice

BACKGROUND

The integrity and functionality of the hepatic microcirculation are essential for maintaining liver health, which is influenced by sex and genetic background. Understanding these variations is crucial for addressing disparities in liver disease outcomes.

AIM

To investigate the sexual dimorphism and genetic heterogeneity of liver microcirculatory function in mice.

METHODS

We assessed hepatic microhemodynamics in BALB/c, C57BL/6J, and KM mouse strains using laser Doppler flowmetry and wavelet analysis. We analyzed the serum levels of alanine transaminase, glutamic acid aminotransferase, total bile acid, total protein, alkaline phosphatase, and glucose. Histological and immunohistochemical staining were employed to quantify microvascular density and the expression levels of cluster of differentiation (CD) 31, and estrogen receptor α, and β. Statistical analyses, including the Mantel test and Pearson correlation, were conducted to determine the relationships among hepatic function, microcirculation, and marcocirculation between different sexes and across genetic backgrounds.

RESULTS

We identified sex-based disparities in hepatic microhemodynamics across all strains, with males exhibiting higher microvascular perfusion and erythrocyte concentration, but lower blood velocity. Strain-specific differences were evident, particularly in the endothelial oscillatory characteristics of the erythrocyte concentration. No sex-dependent differences in estrogen receptor expression were observed, while significant variations in CD31 expression and microvascular density were observed. The correlations highlighted relationships between hepatic microhemodynamics and liver function indicators.

CONCLUSION

Our findings indicate the influence of genetic and sex differences on hepatic microcirculation and liver function, highlighting the necessity of incorporating both genetic background and sex into hepatic physiology studies and potential liver disease management strategies.

Microvesicle Tissue Factor Procoagulant Activity Is Elevated and Correlated With Disease Severity in Patients With Cirrhosis

BACKGROUND AND AIMS

Tissue factor-expressing microvesicles (MV-TF) have been found to correlate with thrombotic complications in various diseases. Simultaneously, there is expanding research regarding the effect of the coagulation cascade on liver fibrosis progression. The aim of our manuscript was to evaluate MV-TF activity in patients with cirrhosis and its correlation with disease severity.

METHODS

We prospectively enrolled 82 patients [11 with cirrhosis and hepatocellular cancer (Group 1), 50 with cirrhosis (Group 2) and 21 controls (Group 3)]. Extensive workup for disease staging and exclusion criteria was undertaken. Exclusion criteria included thrombophilia, history of thrombosis, recent hospitalisation, ongoing infection, alcohol dependence, cancer, haematological diseases and use of anticoagulant, antiplatelet or contraceptive drugs. Plasma tissue factor antigen concentration and MV-TF activity were assessed.

RESULTS

MV-TF showed median values of 4.03 [1.57], 3.17 [1.59] and 2.26 [1.23] pg/mL in Groups 1, 2 and 3, respectively. There was a statistically significant difference between Groups 1 and 3 (p < 0.001) and Groups 2 and 3 (p = 0.003), while Group 1 had higher values than Group 2 without statistical significance (p = 0.088). In Group 2, the patients' Child-Pugh (CP) stage was A in 56%, B in 26% and C in 18% of cases. MV-TF activity significantly correlated with decompensated cirrhosis (p = 0.005) and higher CP stage (p = 0.011). Finally, MV-TF activity significantly correlated with 12-month mortality (p = 0.021).

CONCLUSIONS

MV-TF activity is elevated in patients with cirrhosis, showing a significant correlation with disease severity. MV-TF may play a role in the procoagulant imbalance of liver cirrhosis and their contribution in disease progression should be studied further.

Relationship between coagulopathy score and survival in critically ill patients with liver cirrhosis and sepsis: a retrospective study

BACKGROUND

This research focused on exploring the association between coagulopathy scores and the survival outcomes, both short-term and long-term, in individuals diagnosed with liver cirrhosis complicated by sepsis.

METHODS

This study retrospectively analyzed data from individuals with liver cirrhosis and sepsis who were admitted to the intensive care unit (ICU) at Beth Israel Deaconess Medical Center between 2008 and 2022. The main outcome of interest was all-cause mortality within 28 days post-admission, while the secondary outcome assessed mortality within 90 days. We used the Kaplan-Meier analysis to compare the mortality risk among the different groups. To evaluate the relationship between coagulopathy score and mortality risk in patients with liver cirrhosis and sepsis, a multivariate Cox proportional hazards regression analysis was performed. The predictive performance of the coagulopathy score for short- and long-term all-cause mortality was assessed using receiver operating characteristic (ROC) curve analysis, which included evaluation of its sensitivity, specificity, and area under the curve. Subgroup analyses were performed to evaluate the relationship between coagulopathy score and survival across different groups.

RESULTS

The study included a total of 2,278 patients. Kaplan-Meier survival analysis demonstrated that individuals with elevated coagulopathy scores exhibited markedly higher rates of ICU mortality, in-hospital mortality, as well as 28-day and 90-day mortality, with all log-rank tests yielding P-values of less than 0.001. The results of the multivariate Cox regression analysis showed that an elevated coagulopathy score was independently linked to higher 28-day and 90-day all-cause mortality, both before and after controlling for potential confounders. ROC curve analysis showed that although the coagulopathy score was slightly less predictive of prognosis than the Model for End-stage Liver Disease score, it significantly outperformed the Sequential Organ Failure Assessment score and the Sepsis-induced Coagulopathy score. Subgroup analysis revealed no significant interaction between the coagulopathy score and survival across the different subgroups.

CONCLUSIONS

Higher coagulopathy scores in critically ill patients with liver cirrhosis and sepsis were independently associated with poor prognosis. Due to its simplicity and potential predictive value, the coagulopathy score can serve as an effective complement to existing clinical tools for managing critically ill patients with liver cirrhosis and sepsis.

Possible Role of Platelets in the Development and Progression of Non-Alcoholic Fatty Liver Disease

To date, an increasing body of evidence supports the potential role of activated platelets in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). This is likely due to their ability to secrete biologically active substances that regulate liver regeneration processes, ensure hemostasis, and participate in the immune response. Additionally, several studies have demonstrated the efficacy of antiplatelet agents in reducing inflammation, the severity of liver fibrosis, and the progression of fibrosis in non-alcoholic steatohepatitis (NASH). Since NAFLD is not an independent indication for antiplatelet therapy, the primary evidence regarding their efficacy in NAFLD has been derived from studies using animal models of NAFLD or in patients with concomitant cardiovascular diseases. This narrative review will discuss the main functions of platelets, their unique interactions with liver cells, and the outcomes of these interactions, as well as the results of studies evaluating the efficacy and safety of antiplatelet therapy in patients with NAFLD.

The Covert Side of Ascites in Cirrhosis: Cellular and Molecular Aspects

Ascites, a common complication of portal hypertension in cirrhosis, is characterized by the accumulation of fluid within the peritoneal cavity. While traditional theories focus on hemodynamic alterations and renin-angiotensin-aldosterone system (RAAS) activation, recent research highlights the intricate interplay of molecular and cellular mechanisms. Inflammation, mediated by cytokines (interleukin-1, interleukin-4, interleukin-6, tumor necrosis factor-α), chemokines (chemokine ligand 21, C-X-C motif chemokine ligand 12), and reactive oxygen species (ROS), plays a pivotal role. Besides pro-inflammatory cytokines, hepatic stellate cells (HSCs), sinusoidal endothelial cells (SECs), and smooth muscle cells (SMCs) contribute to the process through their activation and altered functions. Once activated, these cell types can worsen ascites accumulationthrough extracellular matrix (ECM) deposition and paracrine signals. Besides this, macrophages, both resident and infiltrating, through their plasticity, participate in this complex crosstalk by promoting inflammation and dysregulating lymphatic system reabsorption. Indeed, the lymphatic system and lymphangiogenesis, essential for fluid reabsorption, is dysregulated in cirrhosis, exacerbating ascites. The gut microbiota and intestinal barrier alterations which occur in cirrhosis and portal hypertension also play a role by inducing inflammation, creating a vicious circle which worsens portal hypertension and fluid accumulation. This review aims to gather these aspects of ascites pathophysiology which are usually less considered and to date have not been addressed using specific therapy. Nonetheless, it emphasizes the need for further research to understand the complex interactions among these mechanisms, ultimately leading to targeted interventions in specific molecular pathways, aiming towards the development of new therapeutic strategies.

Current perspectives and trends of neutrophil extracellular traps in organ fibrosis: a bibliometric and visualization study

New insights into the role of immune responses in the fibrosis process provide valuable considerations for the treatment of organ fibrotic diseases. Neutrophil extracellular traps (NETs) represent a novel understanding of neutrophil functions, and their involvement in organ fibrotic diseases has garnered widespread attention in recent years. This study aims to conduct a bibliometric analysis and literature review focusing on the mechanisms by which NETs participate in fibrotic diseases. Specifically, we utilized a bibliometric dataset that includes 220 papers published in 139 journals, originating from 425 organizations across 39 countries, with a total citation count of 12,301. Keyword co-occurrence analysis indicates that the research focus on the mechanisms of NETs in organ fibrosis is likely to center on NETosis, immune responses, immune thrombosis, inflammation, and tissue damage associated with NET formation. In conclusion, our findings underscore the current status and emerging trends in NET research related to organ fibrosis, offering novel insights into the mechanisms by which NETs contribute to the pathogenesis of fibrotic diseases, as well as potential therapeutic strategies.

Neutrophil extracellular traps-induced pyroptosis of liver sinusoidal endothelial cells exacerbates intrahepatic coagulation in cholestatic mice

BACKGROUND

Neutrophil extracellular traps (NETs) and NOD-like receptor protein 3 (NLRP3) inflammation are key contributors to cholestatic liver disease (CLD). However, the relationship between NETs release and inflammasome activation, as well as its contribution to intrahepatic coagulation in CLD, remains unexplored. This study explores NETs-induced liver sinusoidal endothelial cells (LSECs) pyroptosis on intrahepatic coagulation in CLD.

METHODS

Wild-type (WT) and PAD4-/- mice underwent bile duct ligation (BDL) or sham surgery for 7 or 14 days. The liver analysis assessed intrahepatic coagulation, inflammation, fibrosis, NETs release, and NLRP3 activation. Primary LSECs were exposed to NETs with or without MCC950. Pyroptosis and LSECs procoagulant activity were quantified.

RESULTS

BDL mice exhibited significantly increased inflammation, tissue factor (TF), and fibrin deposition compared with controls. NETs release in the liver was increased significantly in WT BDL mice and was responsible for intrahepatic coagulation. PAD4 deficiency reduced TF and fibrin expression, improving hepatic sinusoid function. RNA-seq revealed BDL-induced enrichment of coagulation, neutrophil activation, and pyroptosis pathways. In vivo, NETs increased intrahepatic NLRP3 and IL-1β expression in BDL mice. However, NLRP3 inhibition (MCC950) or activation (BMS-986299) did not alter NETs release. Furthermore, NETs-induced NLRP3 activation increased intrahepatic coagulation, inflammation, and fibrosis. Finally, we demonstrated that NETs triggered LSECs dysfunction and pyroptosis, upregulating TF and phosphatidylserine production and enhancing procoagulant activity.

CONCLUSIONS

NETs-induced LSECs pyroptosis exacerbates intrahepatic coagulation in cholestasis. Targeting NETs and LSECs pyroptosis holds promise for treating chronic liver injury in CLD.

Analysis of Factors Related to Pulmonary Nodules in Patients With Fatty Liver: A Large-Scale Cohort Study Based on a Physical Examination Population

Purpose

People with fatty liver are at high risk for pulmonary nodules, but the underlying mechanism is unclear. This study aimed to investigate the occurrence of lung nodules in fatty liver patients and explore influencing factors.

Patients and Methods

We retrospectively analyzed 57,119 individuals who underwent health checkups at the People's Hospital of Guangxi from May 2020 to May 2024. Patients with fatty liver were divided into pulmonary nodule and no pulmonary nodule groups. Univariate and multifactorial analyses were conducted using physical examination data, laboratory test indexes, and imaging information. Logistic regression analysis was used to identify independent predictors of pulmonary nodules in fatty liver patients.

Results

A total of 20,042 patients with fatty liver were included in the study, with 12,334 (61.5%) in the lung nodule group and 7708 (38.5%) in the non-lung nodule group. Age, gender, systolic and diastolic blood pressure were significantly higher in the pulmonary nodule group, while body weight, waist circumference, hemoglobin, uric acid, and glutamyltransferase were lower. Multifactorial logistic regression analysis showed that male gender, body weight, age, and diastolic blood pressure were significant factors influencing lung nodule development in fatty liver patients.

Conclusion

Fatty liver disease is independently associated with an increased incidence of pulmonary nodules, highlighting its importance in lung cancer screening and prevention.

Precisely Controlling the Activation of an Iron-Locked Drug Generator in the Liver Sinusoid to Enhance Barrier Penetration and Reduction of Liver Fibrosis

Complex physical barriers and the nanomaterial's clearance mechanism in the liver greatly hinder the feasibility of using a conventional liver-targeting nanoplatform to deliver antifibrotic drugs to pathological sites for the treatment of liver fibrosis. Here, a novel drug delivery strategy was designed to overcome drug penetration barriers in a fibrotic liver and cooperated with oral nattokinase (NKase)-mediated antifibrosis therapy as a proof of concept, which relies on the coadministration of a nanosized iron-locked drug generator (named Pro-HAase) and orally absorbed iron chelator deferasirox (DFX). Such a strategy starts from the rapid accumulation of intravenously injected Pro-HAase in the microcapillaries of the fibrotic liver followed by disrupting the polyphenol-iron coordination inside Pro-HAase by DFX, liberating antifibrotic components, including procyanidine (PA) and hyaluronidase (HAase). Attractively, absorption of DFX requires the sequential processes of traversing the intestinal mucosa and targeting the liver, which enable DFX to preferentially disassemble Pro-HAase accumulated in the liver sinusoid rather than in systemic circulation or other organs, thus avoiding the off-target activation of Pro-HAase and depletion of the normal iron pool. The in situ disassembly process decreases the sequestration of Pro-HAase by cells of the mononuclear phagocyte system and promotes gradient-driven permeation of therapeutic components to surrounding liver tissues within 2 h, accompanied by biliary excretion of the inactive iron-DFX complex. As a result, the cooperation of Pro-HAase and DFX not only allows NKase-mediated therapy to completely reverse liver fibrosis but also suppresses the chronic hepatotoxicity of residual liver iron after multiple doses of Pro-HAase. The high spatiotemporal precision, unique barrier-penetration mechanism, and self-detoxification ability of this strategy will inspire the rational design of analogous iron-locked nanosystems to improve the therapeutic outcomes of liver fibrosis or other liver diseases.

Endothelial Dysfunction and Liver Cirrhosis: Unraveling of a Complex Relationship

Endothelial dysfunction (ED) is the in the background of multiple metabolic diseases and a key process in liver disease progression and cirrhosis decompensation. ED affects liver sinusoidal endothelial cells (LSECs) in response to different damaging agents, causing their progressive dedifferentiation, unavoidably associated with an increase in intrahepatic resistance that leads to portal hypertension and hyperdynamic circulation with increased cardiac output and low peripheral artery resistance. These changes are driven by a continuous interplay between different hepatic cell types, invariably leading to increased reactive oxygen species (ROS) formation, increased release of pro-inflammatory cytokines and chemokines, and reduced nitric oxide (NO) bioavailability, with a subsequent loss of proper vascular tone regulation and fibrosis development. ED evaluation is often accomplished by serum markers and the flow-mediated dilation (FMD) measurement of the brachial artery to assess its NO-dependent response to shear stress, which usually decreases in ED. In the context of liver cirrhosis, the ED assessment could help understand the complex hemodynamic changes occurring in the early and late stages of the disease. However, the instauration of a hyperdynamic state and the different NO bioavailability in intrahepatic and systemic circulation-often defined as the NO paradox-must be considered confounding factors during FMD analysis. The primary purpose of this review is to describe the main features of ED and highlight the key findings of the dynamic and intriguing relationship between ED and liver disease. We will also focus on the significance of FMD evaluation in this setting, pointing out its key role as a therapeutic target in the never-ending battle against liver cirrhosis progression.

Impact of Treatment with Direct Antivirals on Coagulation Parameters in Patients with Hepatitis C Virus-Related Liver Cirrhosis and Sustained Virological Response

Background and Objectives: Sustained virologic responses (SVRs) lead to a decrease in portal hypertension, the regression of fibrosis, and the improvement in the hepatic synthesis of procoagulant and anticoagulant factors. We aimed to assess the influence of SVR on coagulation parameters in cirrhotic patients with HCV treated with DAAs. Methods: We performed a prospective study in the Institute of Gastroenterology and Hepatology Iasi, Romania, between January 2022 and February 2024. We included patients diagnosed with compensated and decompensated HCV-related liver cirrhosis, treated with direct antivirals (PrOD ± RBV or SOF/LED ± RBV) for 12/24 weeks. Blood samples for biochemical, immunological, and coagulation tests were collected at the baseline, end of treatment (EOT), and once sustained virological response had been achieved over a period of 12/24 weeks (SVR12/24). Results: We analyzed a group of 52 patients with HCV-related liver cirrhosis, predominantly female (68.0%), and the degree of severity of cirrhosis placed the patients mainly in Child-Pugh classes B (40%) and C (36%). All patients achieved SVRs. The MELD score decreased at EOT (13.48 ± 4.273; p = 0.001) and SVR (9.88 ± 2.774; p = 0.000), compared to the baseline (14.92 ± 4.707). The FibroScan values decreased at SVR (17.596 ± 3.7276; p = 0.000) compared to the baseline (26.068 ± 7.0954). For all common coagulation parameters (platelets, INR, PT, fibrinogen, aPTT), there was a trend towards improvement during treatment, including changes which were statistically significant for the majority of patients. Factor II was low at the baseline (75.40 ± 7.506) but increased at EOT (87.40 ± 9.587) and, later, at SVR (99.12 ± 11.695; p = 0.000). The FVIII values increased at the baseline (175.52 ± 16.414) and decreased at EOT (151.48 ± 13.703) and SVR (143.40 ± 13.937). The FvW values decreased during treatment (146.84 ± 9.428, at baseline; 141.32 ± 9.690, p = 0.000, at EOT; and 126.68 ± 17.960, at SVR). In regard to the anticoagulant factors (PC, PS, ATIII), a significant improvement was brought on by SVR. Advanced stages of liver disease showed the most diminished FII activity, while at the baseline and in Child-Pugh C patients we recorded the highest values of FVIII and FvW. Conclusions: Our study proved that the "reset" of coagulopathy might be due to the improvement in liver function due to viral eradication secondary to AAD therapy.

ADAMTS-13: A Prognostic Biomarker for Portal Vein Thrombosis in Japanese Patients with Liver Cirrhosis

Portal vein thrombosis (PVT), one of the most prevalent hepatic vascular conditions in patients with liver cirrhosis (LC), is associated with high mortality rates. An imbalance between a disintegrin-like metalloproteinase with thrombospondin type-1 motifs 13 (ADAMTS-13) enzyme and von Willebrand factor (VWF) is responsible for hypercoagulability, including spontaneous thrombus formation in blood vessels. Herein, we aimed to identify potential prognostic and diagnostic biomarkers in Japanese patients with LC and PVT. In total, 345 patients were divided into two groups: 40 patients who developed PVT (PVT group) and 305 who did not develop PVT (NPVT group). Among the 345 patients with LC, 81% (279/345) were deemed ineligible due to the presence of preventive comorbidities, active or recent malignancies, and organ dysfunction. The remaining 66 patients were divided into two groups: the PVT group (n = 33) and the NPVT group (n = 33). Plasma ADAMTS-13 activity (ADAMTS-13:AC) and the vWF antigen (VWF:Ag) were measured using enzyme-linked immunosorbent assays. Contrast-enhanced, three-dimensional helical computed tomography (CT) was used to detect and characterize PVT. ADAMTS-13:AC was significantly lower in the PVT group than in the NPVT group. No significant differences in plasma vWF:Ag or liver stiffness were observed between the two groups. ADAMTS-13:AC of <18.8 was an independent risk factor for PVT on multivariate analyses (odds ratio: 1.67, 95% confidence interval: 1.21-3.00, p < 0.002). The receiver operating characteristic analysis of ADAMTS-13:AC revealed an area under the curve of 0.913 in PVT detection. Patients with PVT having ADAMTS-13:AC ≥18.8 (n = 17) had higher albumin levels and better prognoses than those with ADAMTS-13:AC <18.8 (n = 16). No significant correlations of ADAMTS-13:AC levels with either fibrin degradation product or D-dimer levels were observed. ADAMTS-13:AC levels could be potential diagnostic and prognostic biomarkers for PVT in Japanese patients with LC.

Molecular Mechanisms Underlying Vascular Liver Diseases: Focus on Thrombosis

Vascular liver disorders (VLDs) comprise a wide spectrum of clinical-pathological entities that primarily affect the hepatic vascular system of both cirrhotic and non-cirrhotic patients. VLDs more frequently involve the portal and the hepatic veins, as well as liver sinusoids, resulting in an imbalance of liver homeostasis with serious consequences, such as the development of portal hypertension and liver fibrosis. Surprisingly, many VLDs are characterized by a prothrombotic phenotype. The molecular mechanisms that cause thrombosis in VLD are only partially explained by the alteration in the Virchow's triad (hypercoagulability, blood stasis, and endothelial damage) and nowadays their pathogenesis is incompletely described and understood. Studies about this topic have been hampered by the low incidence of VLDs in the general population and by the absence of suitable animal models. Recently, the role of coagulation imbalance in liver disease has been postulated as one of the main mechanisms linked to fibrogenesis, so a novel interest in vascular alterations of the liver has been renewed. This review provides a detailed analysis of the current knowledge of molecular mechanisms of VLD. We also focus on the promising role of anticoagulation as a strategy to prevent liver complications and to improve the outcome of these patients.