A prospective pilot study of circulating endothelial cells as a potential new biomarker in portal hypertension

Nonalcoholic fatty liver disease and portal hypertension

Nonalcoholic fatty liver disease (NAFLD) is a substantial and growing problem worldwide and has become the second most common indication for liver transplantation as it may progress to cirrhosis and develop complications from portal hypertension primarily caused by advanced fibrosis and erratic tissue remodeling. However, elevated portal venous pressure has also been detected in experimental models of fatty liver and in human NAFLD when fibrosis is far less advanced and cirrhosis is absent. Early increases in intrahepatic vascular resistance may contribute to the progression of liver disease. Specific pathophenotypes linked to the development of portal hypertension in NAFLD include hepatocellular lipid accumulation and ballooning injury, capillarization of liver sinusoidal endothelial cells, enhanced contractility of hepatic stellate cells, activation of Kupffer cells and pro-inflammatory pathways, adhesion and entrapment of recruited leukocytes, microthrombosis, angiogenesis and perisinusoidal fibrosis. These pathological events are amplified in NAFLD by concomitant visceral obesity, insulin resistance, type 2 diabetes and dysbiosis, promoting aberrant interactions with adipose tissue, skeletal muscle and gut microbiota. Measurement of the hepatic venous pressure gradient by retrograde insertion of a balloon-tipped central vein catheter is the current reference method for predicting outcomes of cirrhosis associated with clinically significant portal hypertension and guiding interventions. This invasive technique is rarely considered in the absence of cirrhosis where currently available clinical, imaging and laboratory correlates of portal hypertension may not reflect early changes in liver hemodynamics. Availability of less invasive but sufficiently sensitive methods for the assessment of portal venous pressure in NAFLD remains therefore an unmet need. Recent efforts to develop new biomarkers and endoscopy-based approaches such as endoscopic ultrasound-guided measurement of portal pressure gradient may help achieve this goal. In addition, cellular and molecular targets are being identified to guide emerging therapies in the prevention and management of portal hypertension.

Exploring the Link Between Platelet Numbers and Vascular Homeostasis Across Early and Late Stages of Fibrosis in Hepatitis C

BACKGROUND

Thrombocytopenia is a hallmark of advanced liver disease. Platelets, growth factors (GFs), and vascular integrity are closely linked factors in disease pathogenesis, and their relationship, particularly in early disease stages, is not entirely understood. The aim was to compare circulating platelets, growth factors, and vascular injury markers (VIMs) in hepatitis C-infected (HCV) patients with early fibrosis and cirrhosis.

METHODS

Retrospective evaluation of serum GFs and VIMs by ELISA were evaluated from twenty-six HCV patients. Analytes from an earlier time-point were correlated with MELD at a later time-point.

RESULTS

Platelets and GFs decreased, and VIMs increased with fibrosis. Platelets correlated positively with PDGF-AA, PDGF-BB, TGFB1, EGF, and P-selectin, and negatively with ICAM-3 and VCAM-1. P-selectin showed no correlations with VIMs but positively correlated with PDGF-AA, PDGF-BB, TGFB1, and EGF. Soluble VCAM-1 and ICAM-3 were linked to increasing fibrosis, liver enzymes, and synthetic dysfunction. Higher VCAM-1 and ICAM-3 and lower P-selectin at an earlier time-point were linked to higher MELD score at a later time-point.

CONCLUSION

In chronic HCV, progressive decline in platelets and growth factors with fibrosis and their associations suggest that platelets are an important source of circulating GFs and influence GF decline with fibrosis. Enhanced markers of vascular injury in patients with early fibrosis suggest an earlier onset of endothelial dysfunction preceding cirrhosis. Associations of VIMs with platelets suggest a critical link between platelets and vascular homeostasis. Circulating markers of vascular injury may not only have prognostic importance but emphasize the role of vascular dysfunction in liver disease pathogenesis (NCT00001971).

A Meta-analysis of the Value of vWF in the Diagnosis of Liver Cirrhosis with Portal Hypertension

Background and Aims: Studies have indicated that serum von Willebrand factor (vWF) has a positive correlation with hepatic venous pressure gradient. However, information on the value of vWF in the diagnosis of liver cirrhosis with portal hypertension has been lacking. The purpose of this meta-analysis was to assess the value of vWF in the diagnosis of liver cirrhosis with portal hypertension. Methods: Studies that analyzed the sensitivity, specificity, diagnostic odds ratio combined with likelihood ratios and test for heterogeneity of vWF in the diagnosis of liver cirrhosis with portal hypertension were found in the Cochrane Library, Ovid, VOS-SCI, CNKI, PubMed, Medline, EMBASE, CMB and Wanfang databases. In the end, the data was used to draw the summary receiver operating characteristic curve and to calculate the area under the curve. Results: Four studies involving 662 patients were analyzed. The results showed that serum vWF in liver cirrhosis with portal hypertension were significantly higher than in those without portal hypertension. Sensitivity combined was 0.823 (95% CI: 0.788, 0.855). Specificity combined was 0.782 (95% CI: 0.708, 0.845). +LR combined was 3.777 (95% CI: 2.794, 5.107). -LR combined was 0.221 (95% CI: 0.180, 0.272). Diagnostic odds ratio combined was 18.347 (95% CI: 11.725, 28.708). The area under the curve was 0.8896. Conclusions: Serum vWF can be used as an effective and feasible method for noninvasive diagnosis of liver cirrhosis with portal hypertension. However, further studies are still needed to evaluate the severity of liver cirrhosis with portal hypertension.

Non-invasive Markers of Portal Hypertension: Appraisal of Adult Experience and Potential Utilisation in Children

Portal hypertension (PHT) is a significant cause of morbidity and mortality in children with chronic liver disease and portal vein obstruction. Increased portal pressure results in variceal formation along the gastrointestinal (GI) tract resulting in major bleeding. Identifying children with significant PHT who are more likely to suffer GI bleeding has been challenging and the role of surveillance upper GI endoscopy has been debated. This review analyses research done on serum biomarkers and imaging techniques as possible predictors of significant PHT. We evaluated the research performed on adult population, as well as the limited work done on children, to identify promising areas for future research. A literature search was conducted on "PubMed." Several search terms were used including "portal hypertension," "paediatric portal hypertension," "non-invasive markers of portal hypertension," "spleen stiffness," "liver stiffness," "elastography," and "endothelial damage." The articles included were selected based on their relevance to the purpose of our review. The research suggests a combination of several biomarkers, in addition to an imaging technique such as transient elastography or magnetic resonance elastography, would allow for the best prediction of significant varices. The most promising indicators would be those that are applicable in both intra- and extra-hepatic causes of PHT. Further research on these predictors in children with PHT is required to determine their potential role as selection criteria for PHT and stratification of surveillance GI endoscopies.

von Willebrand factor as a novel noninvasive predictor of portal hypertension and esophageal varices in hepatitis B patients with cirrhosis

OBJECTIVE

At present, there is no perfect noninvasive method to assess portal hypertension and esophageal varices. Early predicting esophageal varices can provide evidence for managing cirrhotic patients. We aimed to further investigate von Willebrand factor (vWF) as a noninvasive predictor of portal hypertension, especially of esophageal varices.

MATERIAL AND METHODS

A total of 60 hepatitis B patients with cirrhosis and 45 healthy subjects were enrolled in this study. Levels of six markers were examined. All patients underwent hepatic venous pressure gradient (HVPG) and esophagogastroduodenoscopy. We evaluated the performance of six factors for diagnosis of portal hypertension and esophageal varices. The vWF levels in liver tissues were observed by immunohistochemistry. Correlations between the level of vWF in liver tissues and HVPG and between levels of vWF in tissues and plasma were examined.

RESULTS

Cutoff values of plasma vWF (1510.5 mU/mL and 1701 mU/mL) showed high positive predictive value (PPV, 90.2% and 87.5%) in predicting clinically significant portal hypertension and severe portal hypertension. Cutoff values of vWF (1414 mU/ml and 1990 mU/mL, PPV 90.3% and 86.3%, respectively) were provided to detect the presence and degree of esophageal varices. Linear correlations were observed between levels of vWF in liver tissues and HVPG (r(2) = 0.552, p < 0.001) and between the level of vWF in liver tissues and in plasma (r(2) = 0.461, p < 0.001).

CONCLUSION

The vWF is a noninvasive predictor of portal hypertension and esophageal varices in hepatitis B patients with cirrhosis. Increased levels of vWF in liver tissues may induce the elevated plasma vWF levels, but molecular mechanism is needed for further study.

Soluble CD146, a novel endothelial marker, is related to the severity of liver disease

OBJECTIVES

Angiogenesis and inflammation have been involved in the progression of fibrosis in patients with chronic liver disease (CLD). Soluble CD146 (sCD146), a biomarker that was recently characterized as a novel component of the endothelial junction is implicated in endothelial proliferation. Our study evaluates the performance of sCD146 in assessing liver fibrosis and cirrhosis, and determines if its levels are related to the severity of liver disease in patients with cirrhosis.

MATERIAL AND METHODS

sCD146 levels were determined by a commercially available immunoenzymatic technique in 62 consecutive patients with cirrhosis, 43 patients with CLD and 27 healthy controls.

RESULTS

Patients with cirrhosis compared to non-cirrhotics with CLD had a higher median sCD146 concentration (639 vs. 317 ng/ml). In receiver operating characteristic (ROC) curve analysis, the cut-off of 412 ng/ml showed a sensitivity of 78% and a specificity of 75% for diagnosis of cirrhosis, offering good diagnostic accuracy (area under the ROC curve [AUROC: 0.838]). Patients with compensated compared to those with decompensated cirrhosis had a lower median sCD146 concentration (399 vs. 848 ng/ml, respectively). A cut-off of 534 ng/ml offered a sensitivity of 83% and a specificity of 78% for differentiating compensated from decompensated cirrhosis (AUROC: 0.866). Furthermore, in cirrhotics, sCD146 correlated positively with AST, bilirubin levels and most importantly with international normalized ratio and model for end-stage liver disease (r = 0.648, p < 0.001 and r = 0.567, p < 0.001, respectively).

CONCLUSION

sCD146 can be used as a surrogate, inexpensive biomarker for the diagnosis of cirrhosis. It is also well correlated with severity of liver disease in cirrhotic patients. Further studies are needed to define its role in clinical practice.

Novel inflammatory biomarkers of portal pressure in compensated cirrhosis patients

The rationale for screening inflammatory serum biomarkers of the hepatic vein pressure gradient (HVPG) is based on the fact that portal hypertension is pathogenically related to liver injury and fibrosis, and that in turn these are associated with the activation of inflammatory pathways. This was a nested cohort study in the setting of a randomized, clinical trial to assess the development of gastroesophageal varices (GEV) (N Engl J Med 2005;353:2254). Patients had cirrhosis and portal hypertension but did not have GEV. A total of 90 patients who had baseline day-1 sera available were enrolled in the present study. The objective of this study was to determine whether inflammatory biomarkers in conjunction with clinical parameters could be used to develop a predictive paradigm for HVPG. The correlations between HVPG and interleukin (IL)-1β (P=0.0052); IL-1R-α (P=0.0085); Fas-R (P=0.0354), and serum VCAM-1 (P=0.0007) were highly significant. By using multivariate logistic regression analysis and selected parameters (transforming growth factor beta [TGFβ]; heat shock protein [HSP]-70; at-risk alcohol use; and Child class B) we could exclude HVPG ≥ 12 mmHg with 86% accuracy (95% confidence interval [CI]: 67.78 to 96.16%) and the sensitivity was 87.01% (95% CI: 69.68 to 96.34%). Therefore, the composite test could identify 86% of compensated cirrhosis patients with HVPG below 12 mmHg and prevent unnecessary esophagogastroduodenoscopy with its associated morbidity and costs in these patients. Our diagnostic test was not efficient in predicting HVPG ≥ 12 mmHg.

CONCLUSION

A blood test for HVPG could be performed in cirrhosis patients to prevent unnecessary esophagogastroduodenoscopy.

Angiogenesis in liver regeneration and fibrosis: "a double-edged sword"

Angiogenesis, defined as the formation of new microvasculature from preexisting blood vessels and mature endothelial cells, plays a major role in wound healing and scar formation, and it is associated with inflammatory responses. Angiogenesis can occur in physiological conditions, such as during liver regeneration, and in pathological situations, such as during the progression of fibrosis to cirrhosis and also during tumor angiogenesis. Cellular cross-talk among liver sinusoidal endothelial cells (LSECs), hepatic stellate cells and hepatocytes is believed to play an important role in the angiogenesis process during both liver regeneration and development of cirrhosis. In addition to mature endothelial cells, bone marrow (BM)-derived circulating endothelial progenitor cells (EPCs) have been recently identified for their contribution to post-natal vasculogenesis/angiogenesis. In vivo, EPCs are mobilized into the peripheral blood in response to tissue ischemia or traumatic injury, migrate to the sites of injured endothelium and differentiate into mature endothelial cells. In our recent studies, we have explored the role of EPC-mediated angiogenesis in liver regeneration and/or cirrhosis. Results have demonstrated significantly increased endogenous levels of circulating EPCs in cirrhotic patients in comparison to the controls. Also, EPCs from cirrhotic patients have been observed to stimulate substantial angiogenesis by resident LSECs in vitro via paracrine factors such as vascular endothelial growth factor and platelet-derived growth factor. This review gives an overview of the angiogenesis process in liver regeneration and disease and discusses a new mechanism for intrahepatic angiogenesis mediated by BM-derived EPCs.

Increased number and function of endothelial progenitor cells stimulate angiogenesis by resident liver sinusoidal endothelial cells (SECs) in cirrhosis through paracrine factors

BACKGROUND & AIMS

Recent studies have shown a pathological role of angiogenesis in the progression of chronic liver diseases (CLDs). The present study focused on numbers and angiogenic functions of circulating endothelial progenitor cells (EPCs) in patients with cirrhosis.

METHODS

Circulating EPCs were counted by flow-cytometry, and correlated with different parameters of liver disease. They were cultured in patients and controls to compare colony-formation, proliferation and tube formation. Interactions of EPCs with hepatic stellate cells (HSCs) and sinusoidal endothelial cells (SECs) were examined by indirect and direct co-cultures in presence of EPCs and EPC-conditioned medium, respectively. ELISA and inhibition assays were performed to assess the role of EPC-derived angiogenic factors.

RESULTS

The number of circulating EPCs was substantially higher in cirrhotic patients compared to controls (p<0.05), and showed good correlation with hepatic disease severity. Functional assays revealed that colonies and proliferation of EPCs were significantly increased in patients compared to controls (p<0.05). Direct and indirect co-cultures of patients' EPCs showed an increase in tube formation by SECs as compared to that observed with control EPCs (p<0.05). There was, however, no tube formation in HSC-EPC co-cultures. Levels of PDGF-BB and VEGF were substantially increased in patients' EPC media and inhibition of these factors by neutralizing antibodies led to a significant reduction in SECs proliferation.

CONCLUSIONS

Mobilization and proliferation of EPCs are significantly enhanced in cirrhotic patients in comparison to controls. EPCs may play an important paracrine role in liver angiogenesis by stimulating resident SECs in cirrhosis.

Continuous administration of recombinant human endostatin (Endostar): A pre-clinical safety study

The aim of this study was to evaluate the safety of the continuous administration of recombinant human endostatin (Endostar) in healthy mice. A total of 16 nude mice were randomly divided into four treatment groups: a continuous administration group injected intraperitoneally (i.p.) with 14 mg/kg Endostar over seven days, an intermittent administration group injected i.p. with 2 mg/kg Endostar daily for seven days, a saline injection group and an untreated control group. All mice were implanted with an intraperitoneal mini-osmotic drug pump filled with Endostar or saline. The serum concentration of Endostar, the cell fraction of CD11b(-)CD146(+)CD105(+) vascular endothelial cells in the peripheral blood, the injury of the myocardial, lung and kidney tissues and the density of microvessels within these organs were observed 24 h after the termination of drug or saline administration. Only trace amounts of Endostar were detected in the serum of the continuous administration and intermittent administration groups. Myocardial, lung and kidney tissues exhibited no detectable signs of injury and no differences in the density of microvessels were found in these organs among the four groups. Yet, the cell fraction (in %) of CD11b(-)CD146(+)CD105(+) vascular endothelial cells in the peripheral blood was higher in the continuous administration group compared with that in the other treatment groups (P=0.011). This suggests that intermittent Endostar delivery did not significantly impact the vascular endothelium, while continuous Endostar administration may promote injury of the endothelium. In conclusion, the continuous administration of Endostar does not appear to be a safe method by which to administer this antiangiogenic agent to healthy nude mice.

Comparison of circulating endothelial cell/platelet count ratio to aspartate transaminase/platelet ratio index for identifying patients with cirrhosis

BACKGROUND/OBJECTIVES

Circulating endothelial cells (CECs) are indicative of vascular injury and correlate with severity of vascular diseases. A pilot study showed that the ratio of CEC to platelet count (CEC/PC) was effective in predicting cirrhosis. Therefore, we evaluated CEC/PC in a larger cohort of patients, correlated it with cirrhosis, and compared its operating characteristics with previously described biomarker for cirrhosis, the AST/platelet ratio index (APRI).

METHODS

Fifty-three patients with cirrhosis, 20 matched healthy controls, and 9 patients with noncirrhotic liver disease were recruited. Peripheral blood sample was collected and analyzed to enumerate nucleated CEC CD146+, CD105+, CD45- using a commercial assay.

RESULTS

Median CEC counts were significantly higher in patients with cirrhosis (62 cells/4 mL, interquartile range [IQR]: 43.5-121) as compared with controls (31 cells/4 mL, IQR: 22.2-40). The CEC/PC was also significantly elevated in cirrhotics (0.69, IQR: 0.39-1.48) compared with controls (0.12, IQR: 0.09-0.20) and noncirrhotics (0.21, IQR: 0.08-0.43). Receiver operator characteristic (ROC) analysis revealed that CEC cutoff value of ≥37 cells/4 mL showed sensitivity of 81% and specificity of 75% for differentiating cirrhosis from controls (area under the curve [AUC]: 0.80; 95% confidence interval [CI] 0.67-0.91). The CEC/PC ratio cutoff value of ≥0.23 showed sensitivity of 91% and specificity of 82% (AUC: 0.92; 95% CI 0.83-0.99). The APRI cutoff value of ≥0.4 showed sensitivity of 94% and specificity of 85% for differentiating cirrhosis from control patients (AUC: 0.96; 95% CI 0.90-1.0). A product of CEC and APRI, termed CAPRI (CEC-APRI), effectively distinguished patients with cirrhosis from controls; with cutoff value of ≥12.7, showing higher sensitivity of 98% and specificity of 85% (AUC: 0.98; 95% CI 0.96-1.0).

CONCLUSION

The CEC/PC ratio is significantly elevated in patients with cirrhosis and demonstrates comparable operating characteristics to previously described APRI. Furthermore, CAPRI, compiled as product of CEC to APRI showed outstanding ability to distinguish patients with cirrhosis from controls, although larger studies are necessary for validation.

Endothelial dysfunction in the regulation of cirrhosis and portal hypertension

Portal hypertension is caused by an increased intrahepatic resistance, a major consequence of cirrhosis. Endothelial dysfunction in liver sinusoidal endothelial cells (LSECs) decreases the production of vasodilators, such as nitric oxide, and favours vasoconstriction. This contributes to an increased vascular resistance in the intrahepatic/sinusoidal microcirculation and develops portal hypertension. Portal hypertension, in turn, causes endothelial dysfunction in the extrahepatic, i.e. splanchnic and systemic, circulation. Unlike dysfunction in LSECs, endothelial dysfunction in the splanchnic and systemic circulation causes overproduction of vasodilator molecules, leading to arterial vasodilation. In addition, portal hypertension leads to the formation of portosystemic collateral vessels. Both arterial vasodilation and portosystemic collateral vessel formation exacerbate portal hypertension by increasing the blood flow through the portal vein. Pathological consequences, such as oesophageal varices and ascites, result. While the sequence of pathological vascular events in cirrhosis and portal hypertension has been elucidated, the underlying cellular and molecular mechanisms causing endothelial dysfunctions are not yet fully understood. This review article summarizes the current cellular and molecular studies on endothelial dysfunctions found during the development of cirrhosis and portal hypertension with a focus on the intra- and extrahepatic circulations. The article ends by discussing the future directions of the study for endothelial dysfunction.

Noninvasive evaluation of portal hypertension: emerging tools and techniques

Portal hypertension is the main cause of complications in patients with cirrhosis. However, evaluating the development and progression of portal hypertension represents a challenge for clinicians. There has been considerable focus on the potential role of noninvasive markers of portal hypertension that could be used to stratify patients with respect to the stage of portal hypertension and to monitor disease progression or treatment response in a longitudinal manner without having to undertake repeated invasive assessment. The pathogenesis of portal hypertension is increasingly understood and emerging knowledge of the vascular processes that underpin portal hypertension has paved the way for exploring novel biomarkers of vascular injury, angiogenesis, and endothelial dysfunction. In this paper we focus on the pathogenesis of portal hypertension and potential non-invasive biomarkers with particular emphasis on serum analytes.

Oesophageal varices in cirrhotic patients: from variceal screening to primary prophylaxis of the first oesophageal variceal bleeding

Bleeding from oesophageal varices is still a lethal complication in cirrhotic patients with portal hypertension. Approximately 5-10% of patients with cirrhosis will develop oesophageal varices per year, and about 25-30% of cirrhotic patients with oesophageal varices and without previous variceal haemorrhage will bleed from ruptured varices. To date, data on preventing the formation/growth of oesophageal varices (preprimary prophylaxis) are conflicting, with insufficient evidence to use β-blockers. There is evidence for the need for primary prophylaxis, and both β-blockers and endoscopic variceal ligation have shown the same efficacy in preventing first bleeding, but which one to prefer is still controversial. The present article reviews the established and potential therapeutic strategies for preventing the development and rupture of oesophageal varices.