Extrahepatic angiogenesis hinders recovery of portal hypertension and collaterals in rats with cirrhosis resolution. Clin Sci (Lond). 2018;132:669-683. [PMID: 29449343 DOI: 10.1042/cs20171370]

Recompensation in Cirrhosis: Biomarkers and Strategies

The onset of decompensation in advanced chronic liver disease (ACLD) is a hallmark in natural history, with a poor prognosis and a significantly increased liver-related mortality. Etiological treatments for viral hepatitis or abstinence in cirrhosis due to alcohol abuse have demonstrated that some patients experience partial to complete clinical and analytical improvement, a stage termed "recompensation." Although recompensation is primarily defined clinically based on treatable etiologies, it is still evolving for conditions like metabolic dysfunction-associated steatotic liver disease (MASLD). Despite the need for specific biomarkers in hepatic recompensation, no biomarkers have been thoroughly studied in this context. Biomarkers identified in compensated ACLD (cACLD) following etiological treatment might be explored for recompensation. Although the pathophysiology mechanisms underlying the hepatic recompensation remain unclear, understanding the mechanism involved in cirrhosis decompensation could help identify potential targets for recompensation. This review provides an update on the hepatic recompensation concept, examines the existing data on invasive and non-invasive biomarkers, mainly in cACLD after cure, that could be raised in recompensation, and explores future therapeutic targets for the hepatic recompensation process.

Persistent varices in cured patients: Understanding the role of hepatic venous pressure gradient

Background & Aims

Etiologic factor removal (ER) drives recompensation and improves portal hypertension in cirrhosis. Esophageal varices (EV) and portosystemic shunts (PSS) have been found in patients despite hepatic venous pressure gradient (HVPG) dropping below 10 mmHg after ER, questioning HVPG accuracy in reflecting true portal pressure in the setting of ER. We aim to evaluate the correlation of HVPG with direct portal pressure (DPP) in patients with persistence of EV after ER despite HVPG <10 mmHg.

Methods

This is a bicentric 'proof of concept' study evaluating HVPG and ultrasound-guided percutaneous DPP in patients with HCV or alcohol-related cirrhosis with persistent varices and HVPG <10 mmHg after at least 5 years of ER.

Results

Seven patients with HCV and three with alcohol-related cirrhosis with persistent varices and HVPG <10 mmHg after at least 5 years of ER were included. At evaluation, all patients had a patent portal vein and were compensated. The median platelet count was 129.5 (IQR 95-145) × 109/ml, and the median liver stiffness measurement was 16.15 (IQR 14.4-22.3) kPa. In five patients, EV remained the same size (two large and three small), and five downsized to small after ER. Wedge hepatic vein pressure (median 19 [IQR 16.5-20] mmHg) and portal pressure (median 18 [IQR 15-19.5] mmHg) had an excellent correlation (R = 0.93, p <0.0001). Portal pressure gradient (PPG) confirmed the absence of clinically significant portal hypertension as identified by HVPG across all the patients.

Conclusions

HVPG accurately reflects PPG in the context of HCV and alcohol-related cirrhosis regression. After ER, EV may persist despite HVPG <10 mmHg. The benefit of prophylaxis in patients with EV and HVPG <10 mmHg is unknown. Future studies with clinical endpoints are needed to validate our findings.

Impact and implications

Despite a favorable evolution after the removal of the etiologic factor, varices persist in some patients, and there is a lack of concise guidelines for the evaluation and management of portal hypertension in this population. Our research underscores the persistence of varices in the absence of clinically significant portal hypertension and significantly demonstrates the accuracy of hepatic venous pressure gradient (HVPG) in reflecting portal vein pressure in this specific patient group. These findings emphasize the crucial role of HVPG in the assessment of portal hypertension after etiologic factor removal and lay the groundwork for further investigation into clinical outcomes and the necessity of non-selective beta-blockers in individuals with persistent varices after the removal of etiologic factor.

Recompensation in cirrhosis: unravelling the evolving natural history of nonalcoholic fatty liver disease

Recompensation has gained increasing attention in the field of cirrhosis, particularly in chronic liver disease with a definite aetiology. The current global prevalence of obesity and nonalcoholic fatty liver disease (NAFLD) is increasing, but there is currently a lack of a clear definition for recompensation in NAFLD-related cirrhosis. Here, we provide an up-to-date perspective on the natural history of NAFLD, emphasizing the reversible nature of the disease, summarizing possible mechanisms underlying recompensation in NAFLD, discussing challenges that need to be addressed and outlining future research directions in the field. Recompensation is a promising goal in patients with NAFLD-related cirrhosis, and further studies are needed to explore its underlying mechanisms and uncover its clinical features.

Angiopoietin 2 levels decrease after HCV-cure and reflect the evolution of portal hypertension

BACKGROUND

Portal hypertension (PH) does not resolve in a considerable proportion of patients who achieved HCV-cure.

AIMS

To investigate (i)whether HCV-cure impacts cytokines that orchestrate angiogenesis (i.e.,Ang1/Ang2/VEGF) and fibrogenesis (i.e.,PDGF/TGF-β) and (ii)whether their changes reflect PH-evolution and its complications.

METHODS

We measured plasma levels of cytokines and von Willebrand factor (VWF) and assessed hepatic venous pressure gradient (HVPG) before/after HCV-cure in 66 patients with pre-treatment PH and 23 patients without advanced disease, who served as controls.

RESULTS

Following HCV-cure, we observed a decrease in Ang2/TGF-β, but no changes in the other cytokines. The differences in circulating cytokine profiles in PH patients persisted after removing the primary etiological factor. Patients with pre-treatment HVPG≥10 mmHg with HVPG-reduction≥10% had a more pronounced relative decrease in Ang2. Finally, post-treatment Ang2 predicted FU-HVPG≥16 mmHg/decompensation with AUROC-values of 0.804/0.835.

CONCLUSIONS

HCV-cure decreases circulating Ang2 - a mediator/indicator of dysangiogenesis/endothelial dysfunction, as well as TGF-β - a profibrogenic cytokine. The dynamics of Ang2 mirrored those of PH, rendering FU-Ang2 a non-invasive test for pronounced PH at FU that also predicts hepatic decompensation. The pathophysiological significance of the persistently altered cytokine levels for mechanisms that hinder the PH-regression warrants further study.

A Simple and Quick Screening Method for Intrapulmonary Vascular Dilation in Cirrhotic Patients Based on Machine Learning

Background and Aims

Screening for hepatopulmonary syndrome in cirrhotic patients is limited due to the need to perform contrast enhanced echocardiography (CEE) and arterial blood gas (ABG) analysis. We aimed to develop a simple and quick method to screen for the presence of intrapulmonary vascular dilation (IPVD) using noninvasive and easily available variables with machine learning (ML) algorithms.

Methods

Cirrhotic patients were enrolled from our hospital. All eligible patients underwent CEE, ABG analysis and physical examination. We developed a two-step model based on three ML algorithms, namely, adaptive boosting (termed AdaBoost), gradient boosting decision tree (termed GBDT) and eXtreme gradient boosting (termed Xgboost). Noninvasive variables were input in the first step (the NI model), and for the second step (the NIBG model), a combination of noninvasive variables and ABG results were used. Model performance was determined by the area under the curve of receiver operating characteristics (AUCROCs), precision, recall, F1-score and accuracy.

Results

A total of 193 cirrhotic patients were ultimately analyzed. The AUCROCs of the NI and NIBG models were 0.850 (0.738–0.962) and 0.867 (0.760–0.973), respectively, and both had an accuracy of 87.2%. For both negative and positive cases, the recall values of the NI and NIBG models were both 0.867 (0.760–0.973) and 0.875 (0.771–0.979), respectively, and the precisions were 0.813 (0.690–0.935) and 0.913 (0.825–1.000), respectively.

Conclusions

We developed a two-step model based on ML using noninvasive variables and ABG results to screen for the presence of IPVD in cirrhotic patients. This model may partly solve the problem of limited access to CEE and ABG by a large numbers of cirrhotic patients.

Cellular and Molecular Mechanisms Underlying Liver Fibrosis Regression

Chronic liver injury of different etiologies may result in hepatic fibrosis, a scar formation process consisting in altered deposition of extracellular matrix. Progression of fibrosis can lead to impaired liver architecture and function, resulting in cirrhosis and organ failure. Although fibrosis was previous thought to be an irreversible process, recent evidence convincingly demonstrated resolution of fibrosis in different organs when the cause of injury is removed. In the liver, due to its high regenerative ability, the extent of fibrosis regression and reversion to normal architecture is higher than in other tissues, even in advanced disease. The mechanisms of liver fibrosis resolution can be recapitulated in the following main points: removal of injurious factors causing chronic hepatic damage, elimination, or inactivation of myofibroblasts (through various cell fates, including apoptosis, senescence, and reprogramming), inactivation of inflammatory response and induction of anti-inflammatory/restorative pathways, and degradation of extracellular matrix. In this review, we will discuss the major cellular and molecular mechanisms underlying the regression of fibrosis/cirrhosis and the potential therapeutic approaches aimed at reversing the fibrogenic process.

Angiogenesis in the progression from liver fibrosis to cirrhosis and hepatocelluar carcinoma

Introduction: Persistent inflammation and hypoxia are strong stimulus for pathological angiogenesis and vascular remodeling, and are also the most important elements resulting in liver fibrosis. Sustained inflammatory process stimulates fibrosis to the end-point of cirrhosis and sinusoidal portal hypertension is an important feature of cirrhosis. Neovascularization plays a pivotal role in collateral circulation formation of portal vein, mesenteric congestion, and high perfusion. Imbalance of hepatic artery and portal vein blood flow leads to the increase of hepatic artery inflow, which is beneficial to the formation of nodules. Angiogenesis contributes to progression from liver fibrosis to cirrhosis and hepatocellular carcinoma (HCC) and anti-angiogenesis therapy can improve liver fibrosis, reduce portal pressure, and prolong overall survival of patients with HCC. Areas covers: This paper will try to address the difference of the morphological characteristics and mechanisms of neovascularization in the process from liver fibrosis to cirrhosis and HCC and further compare the different efficacy of anti-angiogenesis therapy in these three stages. Expert opinion: More in-depth understanding of the role of angiogenesis factors and the relationship between angiogenesis and other aspects of the pathogenesis and transformation may be the key to enabling future progress in the treatment of patients with liver fibrosis, cirrhosis, and HCC.

Regression of portal hypertension: underlying mechanisms and therapeutic strategies

Portal hypertension is the main non-neoplastic complication of chronic liver disease, being the cause of important life-threatening events including the development of ascites or variceal bleeding. The primary factor in the development of portal hypertension is a pathological increase in the intrahepatic vascular resistance, due to liver microcirculatory dysfunction, which is subsequently aggravated by extra-hepatic vascular disturbances including elevation of portal blood inflow. Evidence from pre-clinical models of cirrhosis has demonstrated that portal hypertension and chronic liver disease can be reversible if the injurious etiological agent is removed and can be further promoted using pharmacological therapy. These important observations have been partially demonstrated in clinical studies. This paper aims at providing an updated review of the currently available data regarding spontaneous and drug-promoted regression of portal hypertension, paying special attention to the clinical evidence. It also considers pathophysiological caveats that highlight the need for caution in establishing a new dogma that human chronic liver disease and portal hypertension is reversible.

Gut-liver axis signaling in portal hypertension

Portal hypertension (PHT) in advanced chronic liver disease (ACLD) results from increased intrahepatic resistance caused by pathologic changes of liver tissue composition (structural component) and intrahepatic vasoconstriction (functional component). PHT is an important driver of hepatic decompensation such as development of ascites or variceal bleeding. Dysbiosis and an impaired intestinal barrier in ACLD facilitate translocation of bacteria and pathogen-associated molecular patterns (PAMPs) that promote disease progression via immune system activation with subsequent induction of proinflammatory and profibrogenic pathways. Congestive portal venous blood flow represents a critical pathophysiological mechanism linking PHT to increased intestinal permeability: The intestinal barrier function is affected by impaired microcirculation, neoangiogenesis, and abnormal vascular and mucosal permeability. The close bidirectional relationship between the gut and the liver has been termed “gut-liver axis”. Treatment strategies targeting the gut-liver axis by modulation of microbiota composition and function, intestinal barrier integrity, as well as amelioration of liver fibrosis and PHT are supposed to exert beneficial effects. The activation of the farnesoid X receptor in the liver and the gut was associated with beneficial effects in animal experiments, however, further studies regarding efficacy and safety of pharmacological FXR modulation in patients with ACLD are needed. In this review, we summarize the clinical impact of PHT on the course of liver disease, discuss the underlying pathophysiological link of PHT to gut-liver axis signaling, and provide insight into molecular mechanisms that may represent novel therapeutic targets.

Cirrhosis regression: extrahepatic angiogenesis and liver hyperarterialization persist

Data on the consequences of cirrhosis regression on portal hypertension and on splanchnic and systemic hemodynamic are scarce. Previous studies have reported a decrease in hepatic venous pressure gradient following antiviral treatment in patients with hepatitis B or C related cirrhosis. However, these studies did not investigate splanchnic and systemic hemodynamic changes associated with virus control. To fill this gap in knowledge, in a recent issue of Clinical Science, Hsu et al. (vol. 132, issue 6, 669-683) used rat models of cirrhosis induced by thioacetamide and by bile duct ligation and provided a comprehensive analysis of the effects of cirrhosis regression on splanchnic and systemic hemodynamics. They observed a significant reduction in portal pressure accompanied by a normalization of systemic hemodynamic (normal cardiac index and systemic vascular resistance) and a decrease in intrahepatic vascular resistance. No change in extrahepatic vascular structures were observed despite normalization of collateral shunting, meaning that portosystemic collaterals persist but are not perfused. One intriguing part of their results is the only marginal effect of cirrhosis regression on liver hyperarterialisation. This result suggests that changes in splanchnic hemodynamic features induced by cirrhosis remain when hepatic vascular resistance decreases, raising the hypothesis of an autonomous mechanism persisting despite regression of intrahepatic vascular resistance. Microbiota changes and bacterial translocation might account for this effect. In conclusion cirrhosis regression normalizes systemic hemodynamics, but some splanchnic hemodynamic changes persist including extrahepatic angiogenesis and liver hyperarterialization.