Angiogenesis and portal-systemic collaterals in portal hypertension

Collateral circulation caused by end-stage hepatic alveolar echinococcosis

BACKGROUND

Hepatic alveolar echinococcosis (HAE), as a benign parasitic disease with malignant infiltrative activity, grows slowly in the liver, allowing sufficient time for collateral vessels to emerge in the process of vascular occlusion.

METHODS

The portal vein (PV), hepatic vein and hepatic artery were observed by enhanced CT and the inferior vena cava (IVC) by angiography, respectively. Analysis of the anatomical characteristics of the collateral vessels helped to look into the pattern and characteristics of vascular collateralization caused by this specific etiology.

RESULTS

33, 5, 12 and 1 patients were included in the formation of collateral vessels in PV, hepatic vein, IVC and hepatic artery, respectively. PV collateral vessels were divided into two categories according to different pathways: type I: portal -portal venous pathway (13 cases) and type II: type I incorporates a portal-systemic circulation pathway (20 cases). Hepatic vein (HV) collateral vessels fell into short hepatic veins. The patients with IVC collateral presented with both vertebral and lumbar venous varices. Hepatic artery collateral vessels emanating from the celiac trunk maintains blood supply to the healthy side of the liver.

CONCLUSIONS

Due to its special biological nature, HAE exhibited unique collateral vessels that were rarely seen in other diseases. An in-depth study would be of great help to improve our understanding related to the process of collateral vessel formation due to intrahepatic lesions and its comorbidity, in addition to providing new ideas for the surgical treatment of end-stage HAE.

Transcriptome analysis of mesenteric arterioles changes and its mechanisms in cirrhotic rats with portal hypertension

Portal hypertension (PHT) is a major cause of liver cirrhosis. The formation of portosystemic collateral vessels and splanchnic vasodilation contribute to the development of hyperdynamic circulation, which in turn aggravates PHT and increases the risk of complications. To investigate the changes in mesenteric arterioles in PHT, cirrhotic rat models were established by ligating the common bile ducts. After 4 weeks, the cirrhotic rats suffered from severe PHT and splanchnic hyperdynamic circulation, characterized by increased portal pressure (PP), cardiac output (CO), cardiac index (CI), and superior mesenteric artery (SMA) flow. Mesenteric arterioles in cirrhotic rats displayed remarkable vasodilation, vascular remodeling, and hypocontractility. RNA sequencing was performed based on these findings. A total of 1,637 differentially expressed genes (DEGs) were detected, with 889 up-regulated and 748 down-regulated genes. Signaling pathways related to vascular changes were enriched, including the vascular endothelial growth factor (VEGF), phosphatidylinositol-3-kinase-AKT (PI3K-AKT), and nuclear factor kappa light chain enhancer of activated B cells (NF-κB) signaling pathway, among others. Moreover, the top ten hub genes were screened according to the degree nodes in the protein-protein interaction (PPI) network. Functional enrichment analyses indicated that the hub genes were involved in cell cycle regulation, mitosis, and cellular response to oxidative stress and nitric oxide (NO). In addition, promising candidate drugs for ameliorating PHT, such as resveratrol, were predicted based on hub genes. Taken together, our study highlighted remarkable changes in the mesenteric arterioles of cirrhotic rats with PHT. Transcriptome analyses revealed the potential molecular mechanisms of vascular changes in splanchnic hyperdynamic circulation.

Emerging Therapeutic Targets for Portal Hypertension

Purpose of Review

Portal hypertension is responsible of the main complications of cirrhosis, which carries a high mortality. Recent treatments have improved prognosis, but this is still far from ideal. This paper reviews new potential therapeutic targets unveiled by advances of key pathophysiologic processes.

Recent Findings

Recent research highlighted the importance of suppressing etiologic factors and a safe lifestyle and outlined new mechanisms modulating portal pressure. These include intrahepatic abnormalities linked to inflammation, fibrogenesis, vascular occlusion, parenchymal extinction, and angiogenesis; impaired regeneration; increased hepatic vascular tone due to sinusoidal endothelial dysfunction with insufficient NO availability; and paracrine liver cell crosstalk. Moreover, pathways such as the gut-liver axis modulate splanchnic vasodilatation and systemic inflammation, exacerbate liver fibrosis, and are being targeted by therapy. We have summarized studies of new agents addressing these targets.

Summary

New agents, alone or in combination, allow acting in complementary mechanisms offering a more profound effect on portal hypertension while simultaneously limiting disease progression and favoring regression of fibrosis and of cirrhosis. Major changes in treatment paradigms are anticipated.

Nomogram based on spleen volume expansion rate predicts esophagogastric varices bleeding risk in patients with hepatitis B liver cirrhosis

BACKGROUND

We aimed to explore the risk factors for hemorrhage of esophagogastric varices (EGVs) in patients with hepatitis B cirrhosis and to construct a novel nomogram model based on the spleen volume expansion rate to predict the risk of esophagogastric varices bleeding.

METHODS

Univariate and multivariate logistic regression analysis was used to analyze the risk factors for EGVs bleeding. Nomograms were established based on the multivariate analysis results. The predictive accuracy of the nomograms was assessed using the area under the curve (AUC or C-index) of the receiver operating characteristic (ROC) and calibration curves. Decision curve analysis was used to determine the clinical benefit of the nomogram. We created a nomogram of the best predictive models.

RESULTS

A total of 142 patients' hepatitis B cirrhosis with esophagogastric varices were included in this study, of whom 85 (59.9%) had a history of EGVs bleeding and 57 (40.1%) had no EGVs bleeding. The spleen volume expansion rate, serum sodium levels (mmol/L), hemoglobin levels (g/L), and prothrombin time (s) were independent predictors for EGVs bleeding in patients with hepatitis B liver cirrhosis (P < 0.05). The above predictors were included in the nomogram prediction model. The area under the ROC curve (AUROC) of the nomogram was 0.781, the C-index obtained by internal validation was 0.757, and the calibration prediction curve fit well with the ideal curve. The AUROCs of the PLT-MELD and APRI were 0.648 and 0.548, respectively.

CONCLUSION

In this study, a novel nomogram for predicting the risk of EGVs bleeding in patients with hepatitis B cirrhosis was successfully constructed by combining the spleen volume expansion rate, serum sodium levels, hemoglobin levels, and prothrombin time. The predictive model can provide clinicians with a reference to help them make clinical decisions.

Portopulmonary Hypertension: A Review of the Current Literature

Portopulmonary hypertension is defined as the development of pulmonary arterial hypertension in the setting of portal hypertension with or without liver cirrhosis. Portal hypertension-associated haemodynamic changes, including hyperdynamic state, portosystemic shunts and splanchnic vasodilation, induce significant alterations in pulmonary vascular bed and play a pivotal role in the pathogenesis of the disease. If left untreated, portopulmonary hypertension results in progressive right heart failure, with a poor prognosis. Although Doppler echocardiography is the best initial screening tool for symptomatic patients and liver transplantation candidates, right heart catheterisation remains the gold standard for the diagnosis of the disease. Severe portopulmonary hypertension exerts a prohibitive risk to liver transplantation by conferring an elevated perioperative mortality risk. It is important for haemodynamic parameters to correspond with non-severe portopulmonary hypertension before patients can proceed with the liver transplantation. Small uncontrolled studies and a recent randomised controlled trial have reported promising results with vasodilatory therapies in clinical and haemodynamic improvement of patients, allowing a proportion of patients to undergo liver transplantation. In this review, the epidemiology, pathogenesis, diagnostic approach and management of portopulmonary hypertension are discussed. We also highlight fields of ongoing investigation pertinent to risk stratification and optimal patient selection to maximise long-term benefit from currently available treatments.

COX-2/sEH Dual Inhibitor PTUPB Alleviates CCl 4 -Induced Liver Fibrosis and Portal Hypertension

Background: 4-(5-phenyl-3-{3-[3-(4-trifluoromethylphenyl)-ureido]-propyl}-pyrazol-1-yl) -benzenesulfonamide (PTUPB), a dual cyclooxygenase-2 (COX-2)/soluble epoxide hydrolase (sEH) inhibitor, was found to alleviate renal, pulmonary fibrosis and liver injury. However, few is known about the effect of PTUPB on liver cirrhosis. In this study, we aimed to explore the role of PTUPB in liver cirrhosis and portal hypertension (PHT).

Method: Rat liver cirrhosis model was established via subcutaneous injection of carbon tetrachloride (CCl₄) for 16 weeks. The experimental group received oral administration of PTUPB (10 mg/kg) for 4 weeks. We subsequently analyzed portal pressure (PP), liver fibrosis, inflammation, angiogenesis, and intra- or extrahepatic vascular remodeling. Additionally, network pharmacology was used to investigate the possible mechanisms of PTUPB in live fibrosis.

Results: CCl₄ exposure induced liver fibrosis, inflammation, angiogenesis, vascular remodeling and PHT, and PTUPB alleviated these changes. PTUPB decreased PP from 17.50 ± 4.65 to 6.37 ± 1.40 mmHg, reduced collagen deposition and profibrotic factor. PTUPB alleviated the inflammation and bile duct proliferation, as indicated by decrease in serum interleukin-6 (IL-6), liver cytokeratin 19 (CK-19), transaminase, and macrophage infiltration. PTUPB also restored vessel wall thickness of superior mesenteric arteries (SMA) and inhibited intra- or extrahepatic angiogenesis and vascular remodeling via vascular endothelial growth factor (VEGF), von Willebrand factor (vWF), etc. Moreover, PTUPB induced sinusoidal vasodilation by upregulating endothelial nitric oxide synthase (eNOS) and GTP-cyclohydrolase 1 (GCH1). In enrichment analysis, PTUPB engaged in multiple biological functions related to cirrhosis, including blood pressure, tissue remodeling, immunological inflammation, macrophage activation, and fibroblast proliferation. Additionally, PTUPB suppressed hepatic expression of sEH, COX-2, and transforming growth factor-β (TGF-β).

Conclusion: 4-(5-phenyl-3-{3-[3-(4-trifluoromethylphenyl)-ureido]-propyl}-pyrazol-1-yl)- benzenesulfonamide ameliorated liver fibrosis and PHT by inhibiting fibrotic deposition, inflammation, angiogenesis, sinusoidal, and SMA remodeling. The molecular mechanism may be mediated via the downregulation of the sEH/COX-2/TGF-β.

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.

Phosphodiesterases in the Liver as Potential Therapeutic Targets of Cirrhotic Portal Hypertension

Liver cirrhosis is a frequent condition with high impact on patients' life expectancy and health care systems. Cirrhotic portal hypertension (PH) gradually develops with deteriorating liver function and can lead to life-threatening complications. Other than an increase in intrahepatic flow resistance due to morphological remodeling of the organ, a functional dysregulation of the sinusoids, the smallest functional units of liver vasculature, plays a pivotal role. Vascular tone is primarily regulated by the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway, wherein soluble guanylate cyclase (sGC) and phosphodiesterase-5 (PDE-5) are key enzymes. Recent data showed characteristic alterations in the expression of these regulatory enzymes or metabolite levels in liver cirrhosis. Additionally, a disturbed zonation of the components of this pathway along the sinusoids was detected. This review describes current knowledge of the pathophysiology of PH with focus on the enzymes regulating cGMP availability, i.e., sGC and PDE-5. The results have primarily been obtained in animal models of liver cirrhosis. However, clinical and histochemical data suggest that the new biochemical model we propose can be applied to human liver cirrhosis. The role of PDE-5 as potential target for medical therapy of PH is discussed.

Early changes in ammonia levels and liver function in patients with advanced hepatocellular carcinoma treated by lenvatinib therapy

We aimed to investigate the early changes in ammonia levels and liver function in patients with advanced hepatocellular carcinoma treated with lenvatinib. This retrospective study included 23 patients with advanced hepatocellular carcinoma who were able to receive lenvatinib continuously for at least 1 week. We compared their ammonia levels (NH3), total bilirubin (Bil), albumin, and prothrombin (PT) activity at before and after 1 week of lenvatinib administration, and additionally, compared the 2 groups which were divided based on the presence/absence of portosystemic collaterals (PSCs). Before administration of lenvatinib the patients with PSCs had significantly worse ammonia levels and liver function than the patients without PSCs (NH₃: P = 0.013, Bil: P = 0.004, PT: P = 0.047, respectively). Moreover, the indices were worse in all the patients after 1 week of lenvatinib than before administration (NH3: P = 0.001, Bil: P = 0.025, PT: P < 0.001, respectively). Moreover, the changes in ammonia levels were investigated for 4 weeks. The ammonia level increased, to peak at 2 weeks, but decreased after 3 weeks. None of the patients discontinued lenvatinib therapy because of an adverse event. The ammonia levels of the study patients increased from baseline at 1 week after lenvatinib administration, but therapy could be continued for 4 weeks by appropriate management.

Plasma Nogo-A and placental growth factor levels are associated with portal hypertension in patients with liver cirrhosis

BACKGROUND

Clinically significant portal hypertension (CSPH) and severe portal hypertension (SPH) increase the risk for decompensation and life-threatening complications in liver cirrhosis. Pathologic angiogenesis might contribute to the formation of these conditions. Placental growth factor (PlGF) and Nogo-A protein are biomarkers of pathological angiogenesis, but data on their role in liver cirrhosis and portal hypertension is scarce.

AIM

To determine plasma levels of PlGF and Nogo-A in patients with liver cirrhosis, CSPH, SPH and potential to predict portal hypertension.

METHODS

A cohort of 122 patients with hepatitis C virus and/or alcohol-induced liver cirrhosis with characterized hepatic venous pressure gradient (HVPG) were included in the study. Demographic data, medical history, Child-Turcotte-Pugh and Model of End Stage liver disease score, clinical chemistry, liver stiffness values were recorded on the day of the procedure prior HVPG measurement. The degree of portal hypertension was determined by the invasive HVPG measurement. Nogo-A and PlGF plasma levels were evaluated using enzyme linked immunosorbent assay. The control group consisted of 30 healthy age- and sex- matched individuals.

RESULTS

Peripheral PlGF levels were higher and Nogo-A levels were lower in patients with liver cirrhosis (23.20 vs 9.85; P < 0.0001 and 2.19 vs 3.12; P = 0.004 respectively). There was a positive linear correlation between peripheral levels of PlGF and HVPG (r = 0.338, P = 0.001) and negative linear correlation between the peripheral Nogo-A levels and HVPG (r = -0.267, P = 0.007). PlGF levels were higher in CSPH and SPH (P = 0.006; P < 0.0001) whereas Nogo-A levels were lower (P = 0.01; P < 0.033). Area under the curve for the diagnosis of CSPH for PlGF was 0.68 (P = 0.003) and for Nogo-A - 0.67 (P = 0.01); for SPH 0.714 (P < 0.0001) and 0.65 (P = 0.014) respectively. PlGF levels were higher and Nogo-A levels were lower in patients with esophageal varices (P < 0.05). PlGF cut-off value of 25 pg/mL distinguished patients with CSPH at 55.7% sensitivity and 76.7% specificity; whereas Nogo-A cut-off value of 1.12 ng/mL was highly specific (93.1%) for the diagnosis of CSPH.

CONCLUSION

Plasma PlGF levels were higher while Nogo-A levels were lower in patients with liver cirrhosis and portal hypertension. Biomarkers showed moderate predictive value in determining CSPH and SPH.

Comparison of physical parameter measurements between peripheral and portal blood samples in patients with portal hypertension

BACKGROUND

Measuring portal venous pressure is necessary to examine, diagnose, and treat portal hypertension, but current methods are invasive.

OBJECTIVE

This study aimed to determine whether a noninvasive peripheral blood measurement could be used to estimate portal venous pressure by investigating correlations between certain physical parameter measurements in the peripheral blood with those obtained in portal blood samples.

METHODS

A total of 128 peripheral and portal blood samples from patients (n= 128) were analyzed for blood rheology and routine blood parameters.

RESULTS

The mean peripheral and portal whole blood viscosities under the shear rates of 200 s-1 (BV 200 s-1) were 2.97 ± 0.50 mPa.s and 3.06 ± 0.39 mPa.s. The mean peripheral and portal BV 30 s-1 values were 3.96 ± 0.79 mPa.s and 4.16 ± 0.64 mPa.s. We observed strong correlations between peripheral and portal blood measurements of BV 200 s-1 (r2= 0.9649), BV 30 s-1 (r2= 0.9622), BV 5 s-1 (r2= 0.9610), and BV 1 s-1 (r2= 0.9623).

CONCLUSIONS

Our results indicate that peripheral blood can be used to evaluate certain parameters in portal blood for use in biofluid mechanics studies, and to provide noninvasive measurement of portal venous pressure.

Restructuring of the vascular bed in response to hemodynamic disturbances in portal hypertension

In recent years, defined progress has been made in understanding the mechanisms of hemodynamic disturbances occurring in liver cirrhosis, which are based on portal hypertension. In addition to pathophysiological disorders related to endothelial dysfunction, it was revealed: There is the restructuring of the vasculature, which includes vascular remodeling and angiogenesis. In spite of the fact that these changes are the compensatory-adaptive response to the deteriorating conditions of blood circulation, taken together, they contribute to the development and progression of portal hypertension causing severe complications such as bleeding from esophageal varices. Disruption of systemic and organ hemodynamics and the formation of portosystemic collaterals in portal hypertension commence with neovascularization and splanchnic vasodilation due to the hypoxia of the small intestine mucosa. In this regard, the goal of comprehensive treatment may be to influence on the chemokines, proinflammatory cytokines, and angiogenic factors (vascular endothelial growth factor, placental growth factor, platelet-derived growth factor and others) that lead to the development of these disorders. This review is to describe the mechanisms of restructuring of the vascular bed in response to hemodynamic disturbances in portal hypertension. Development of pathogenetic methods, which allow correcting portal hypertension, will improve the efficiency of conservative therapy aimed at prevention and treatment of its inherent complications.