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

The potential roles of gut microbiome in porto-sinusoidal vascular disease: an under-researched crossroad

Accumulating evidence indicates that patients with liver diseases exhibit distinct microbiological profiles, which can be attributed to the bidirectional relationship of the gut-liver axis. Porto-sinusoidal vascular disease (PSVD) has recently been introduced to describe a group of vascular diseases of the liver, involving the portal venules and sinusoids. Although the pathophysiology of PSVD is not yet fully understood, several predisposing conditions, including immunodeficiency, inflammatory bowel disease, abdominal bacterial infections are associated with the increasing in intestinal permeability and microbial translocation, supporting the role of altered gut microbiota and gut-derived endotoxins in PSVD etiopathogenesis. Recent studies have proposed that the gut microbiome may play a crucial role in the pathophysiology of intrahepatic vascular lesions, potentially influencing the onset and progression of PSVD in this context. This review aims to summarize the current understanding of the gut microbiome's potential role in the pathogenesis of hepatic microvascular abnormalities and thrombosis, and to briefly describe their interactions with PSVD. The insights into gut microbiota and their potential influence on the onset and progression of PSVD may pave the way for new diagnostic, prognostic, and therapeutic strategies.

Transient elastography and von Willebrand factor as predictors of portal hypertension and decompensation in children

Background & Aims

Von Willebrand factor antigen (vWFAg), a protein measured to test the level of vWF released from the vascular endothelium has gained much attention as a marker for portal hypertension (PHT) severity. The objectives of this study were to investigate the use of vWFAg as a biomarker along with liver and spleen stiffness measurements by transient elastography as potential predictors of clinically significant varices (CSV), variceal bleeding (VB) and decompensation in children with PHT.

Methods

This observational prospective cohort study included 117 children (median age 10 [IQR 6-14] years) who underwent oesophagogastroduodenoscopy between January'2012 to November'2021 and a validation group of 33 children who underwent the same procedure between December'2021 to March'2023. Measurements of vWFAg and glycoprotein Ib binding activity of VWF (GPIbR) were available in 97 patients in the study group and in all patients in the validation group.Results: vWFAg and GPIbR were significantly higher in children with CSV (223 IU/dl and 166 IU/dl; p = 0.015 and p = 0.04, respectively) and VB (218 IU/dl and 174 IU/dl; p = 0.077 and p = 0.03, respectively) than in those without CSV or VB, respectively. Ninety-six patients had liver and spleen stiffness measurements. Spleen stiffness was significantly higher in patients with CSV compared to those without CSV (p = 0.003). In a chronic liver disease subgroup, a predictive scoring tool based on vWFAg, GPIbR, platelet count, and spleen/liver stiffness measurements could predict CSV with an AUROC of 0.76 (p = 0.04).

Conclusions

This study suggests the predictive value of vWF for CSV and VB increases when combined with spleen stiffness, with AUROCs of 0.88 and 0.82, respectively. Hence, a combination of biomarkers could assist clinicians in diagnosing CSV, preventing unnecessary invasive procedures.

Impacts and implications

Surveillance endoscopies in children with portal hypertension (PHT) have their own risks and non-invasive markers, such as von Willebrand factor antigen, glycoprotein Ib binding activity of VWF (GPIbR), and transient elastography could be used to predict clinically significant varices, variceal bleeding and disease compensation in children with PHT. Such non-invasive markers for PHT and varices are lacking in the paediatric population. The results show that von Willebrand factor and GPIbR along with transient elastography can be used to formulate a scoring system which can be used as a clinical tool by paediatric hepatologists to monitor the progression of PHT and risk of bleeding, and hence to stratify the performance of invasive endoscopic procedures under general anaesthesia. However, there is a need to validate the scoring system in children with portal vein thrombosis and for hepatic decompensation in a multi-centre registry in the future.

Serum Proteomics Uncovers Biomarkers of Clinical Portal Hypertension in Children With Biliary Atresia

Children with biliary atresia (BA) often develop portal hypertension (PHT) and its complications, which are associated with high morbidity and mortality. The goal of this study was to identify serum biomarkers of PHT by using large-scale proteomics. We applied the slow off-rate modified aptamer scan (SOMAscan) to measure 1,305 proteins in serum samples of children with BA with and without clinical evidence of PHT in validation and discovery cohorts enrolled in the Biliary Atresia Study of Infants and Children. Serum proteomics data was analyzed using logistic regression to identify protein(s) with an area under the receiver operating characteristic curve (AUROC) ≥ 0.90. Immunostaining was used to characterize the cellular localization of the new biomarker proteins in liver tissues. We identified nine proteins in the discovery cohort (n = 40 subjects) and five proteins in the validation cohort (n = 80 subjects) that individually or in combination predicted clinical PHT with AUROCs ≥ 0.90. Merging the two cohorts, we found that semaphorin 6B (SEMA6B) alone and three other protein combinations (SEMA6B+secreted frizzle protein 3 [SFRP3], SEMA6B+COMM domain containing 7 [COMMD7], and vascular cell adhesion molecule 1 [VCAM1]+BMX nonreceptor tyrosine kinase [BMX]) had AUROCs ≥ 0.90 in both cohorts, with high positive- and negative-predictive values. Immunostaining of the new protein biomarkers showed increased expression in hepatic endothelial cells, cholangiocytes, and immune cells within portal triads in BA livers with clinical PHT compared to healthy livers. Conclusion: Large-scale proteomics identified SEMA6B, SFRP3, COMMD7, BMX, and VCAM1 as biomarkers highly associated with clinical PHT in BA. The expression of the biomarkers in hepatic epithelial, endothelial, and immune cells support their potential role in the pathophysiology of PHT.

Increased Prevalence of Left Lobe Atrophy in Long-standing Extrahepatic Portal Vein Obstruction

OBJECTIVES

The aim of this study was to describe long-term changes in standard blood tests and ultrasound (US) findings in pediatric patients with Extrahepatic Portal Vein Obstruction (EHPVO) who have not undergone Meso-Rex Bypass (MRB) surgery.

METHODS

US, laboratory, and endoscopic data of 77 patients were analyzed and compared at 2 different points in time: at initial workup and at most recent follow-up. Differences were assessed using McNemar and Wilcoxon tests, while correlations were evaluated using generalized estimating equations.

RESULTS

Upper gastrointestinal bleeding was the most frequent initial manifestation of EHPVO, in 45.4% of subjects. The mean age at diagnosis was 4.3 years. Seventy-four percentage had a previous history of umbilical catheterization and/or neonatal sepsis. Over time, there was a significant increase in the prevalence of leukopenia, thrombocytopenia, and, interestingly, of left lobe atrophy (LLA), even though the number of esophageal varices and the need for endoscopic interventions reduced. A significant correlation was found between history of umbilical catheterization and LLA, splenomegaly and LLA, and gallbladder wall thickening and LLA. Overall, the number of patients with cholelithiasis at initial workup was low (and therefore, not analyzed with inferential statistics); however, we observed a relative increase over time.

CONCLUSIONS

In this cohort of patients with EHPVO followed over more than 8 years without treatment with MRB, we report the novel finding of a significant increase in the prevalence of LLA over time. LLA correlated with past medical history of umbilical catheterization, and findings of splenomegaly and gallbladder wall thickening. We propose that that LLA should be further explored as a marker of portal hypertension, particularly in the context of a history of umbilical catheterization.

Pretransplantation and Post-Transplantation Liver Disease Assessment in Adolescents Undergoing Isolated Heart Transplantation for Fontan Failure

OBJECTIVE

To describe the assessment of Fontan-associated liver disease and determine the clinical and imaging measures that may identify hepatic morbidity risk in isolated heart transplantation candidates and trend those measures post-isolated heart transplantation.

STUDY DESIGN

Retrospective analysis of pre-isolated heart transplantation and post-isolated heart transplantation Fontan-associated liver disease (FALD) status using blood tests, magnetic resonance imaging (MRI), and liver biopsy analysis within 6 months before isolated heart transplantation and 12 months after isolated heart transplantation in 9 consecutive patients with Fontan. Pre- and post-isolated heart transplantation standard laboratory values; varices, ascites, splenomegaly, thrombocytopenia (VAST) score; Fontan liver MRI score; liver biopsy scores; Model for End-stage Liver Disease (MELD); MELD excluding the International Normalized Ratio (MELD-XI); AST to platelet ratio index, and cardiac catheterization data were compared.

RESULTS

Pretransplantation maximum MELD and MELD-XI was 15 and 16, respectively. Central venous pressures and VAST scores decreased significantly post-transplantation. In 5 paired studies, Fontan liver MRI score maximum was 10 pretransplantation and decreased significantly post-transplantation. Arterially enhancing nodules on MRI persisted in 2 patients post-transplantation. Pretransplantation and post-transplantation liver biopsy scores did not differ in 4 paired biopsy specimens.

CONCLUSIONS

Patients with FALD and MELD <15, MELD-XI <16, Fontan liver MRI score <10, and VAST score ≤2 can have successful short-term isolated heart transplantation outcomes. Liver MRI and VAST scores improved post-transplantation. Post-transplantation liver biopsy scores did not change significantly. Pretransplantation liver biopsy demonstrating fibrosis alone should not exclude consideration of isolated heart transplantation. The persistence of hepatic vascular remodeling and fibrosis post-isolated heart transplantation suggests that continued surveillance for hepatic complications post-transplantation for patients with Fontan is reasonable.

Validation of Revised Baveno VI Criteria for Screening of Varices Needing Treatment in Children with Cirrhosis

Background

Baveno VI criteria for screening varices needing treatment (VNT) have not yet been validated in an exclusive pediatric and adolescent set of the population, in whom baseline parameters differ in relation to adults. Therefore, our primary objective was to validate Baveno VI and its expanded form in children below 18 years of age. The secondary aim was to elicit whether any revision of the above criteria with a target of not missing more than 5% VNT could be more accurate for this age group.

Materials and Methods

The work was carried out in two medical institutes, over a span of 3 years. Consecutively enrolled patients below 18 years of age, with compensated cirrhosis confirmed by liver biopsy, were evaluated for related blood parameters, transient elastography (TE) and esophagogastroduodenoscopy.

Results

Out of the 33 recruited patients, five (15.15%) met the criteria for VNT. The sensitivity, specificity, PPV and NPV of Baveno VI and Expanded Baveno VI were observed as 60%, 92.3%, 60% and 92.3%, and 20%, 100%, 100% and 88%, respectively. We found that the Revised Baveno VI criteria with TE <19 kPa and platelet count of >175×10⁹ cells/L, with sensitivity 100%, specificity 79%, PPV 45%, NPV 100% and accuracy of 82%, are more appropriate for this age group.

Conclusion

We propose that further multicentrer studies with a larger sample size should be conducted before incorporating Revised Baveno VI criteria for high-risk varices in patients below 18 years in future guidelines.

Characteristics and Outcomes of Autoimmune Hepatitis from a Tertiary Paediatric Centre, Cape Town, South Africa

OBJECTIVES

To describe the clinical characteristics, biochemical and histological features, outcomes and predictors of prognosis of children with autoimmune hepatitis (AIH) from a paediatric centre in South Africa.

METHODS

Thirty-nine children diagnosed with AIH at Red Cross War Memorial Children's Hospital between 2005 and 2015 were included. Relevant patient's data were retrieved from the hospital's medical records and database. Liver biopsy slides were reviewed. Ethical approval was obtained. Data were analysed using SPSS.

RESULTS

Females were 29 (74%). Mean age at presentation was 7.27 ± 3.35 years and the mean follow-up was 4.5 ± 2.4 years. Jaundice was present in 97% of patients at presentation. An acute presentation was observed in 26 (67%) even though cirrhosis was detected in 22 (56%). Autoantibody screening was completed in 35 patients, 20 (57%) were AIH-1, 1 (3%) was AIH-2 and 14 (40%) were seronegative AIH. Of the 25 patients who underwent magnetic resonance cholangiography 17 (68%) had associated autoimmune sclerosing cholangitis. The remission rate was 79%. However, 11 children relapsed later. One child required liver transplantation and one demised. Seronegative and seropositive patients have comparable characteristics and outcomes. While a higher alanine transaminase (ALT) level at presentation is a significant predictor of remission, a lower ALT level and cirrhosis are significant risk factors for unfavourable outcome. Overall survival rate was 97%.

CONCLUSION

AIH responds well to therapy with excellent survival. Hence, it should be considered in any child presenting with viral screen negative hepatitis and start therapy timeously to prevent disease progression.

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.

Spleen and Liver Stiffness to Detect Esophageal Varices in Children with Biliary Atresia

OBJECTIVES

The aim of the study was to determine the accuracy of noninvasive parameters, such as liver (LS) and spleen stiffness (SS) to detect esophageal varices (EV) in children with biliary atresia (BA).

METHODS

Children with BA between 2000 and 2015 were recruited. All underwent esophagogastroduodenoscopy and transient elastography. Demographic data, laboratory investigations, alanine transferase-to-platelet ratio index (APRI), and Varices Prediction Rule (VPR) score were collected.

RESULTS

A total of 51 children (mean age 10.63 years, standard deviation (SD) = 6.08 years; 53% boys) were enrolled. There were differences in onset and outcome of portoenterostomy, spleen palpablility, platelet count, albumin, LS, SS, and VPR between the varice and varice-free groups (P < 0.05). In the varice group, the median LS was 18.12 (interquartile ratio, IQR 13.15-19.12) and the median SS was 46.85 (IQR 25.95-54.55) kPa. In the varice-free group, the median LS was 7.85 (IQR 5.88-16.75) and the median SS was 16.54 (IQR 11.75-21.75) kPa. Both LS and SS were higher in the varice than the varice-free group (P < 0001). The area under the receiver operating characteristic curve of LS, SS, spleen palpability, platelet count, APRI, and VPR were 0.734, 0.870, 0.817, 0.810, 0.751, and 0.794, respectively. Using a cut-off value of 12.5 kPa for LS, the sensitivity and specificity were 80 and 70%, respectively. Using a cut-off value of 28.9 kPa for SS, the sensitivity and specificity were 75 and 87%, respectively. Combination of LS and SS to diagnose varices increased the specificity to 93%.

CONCLUSIONS

SS as a single marker had the best diagnostic value to predict esophageal varices in children with BA. The combination of SS and LS furthermore, increased the diagnostic yield.

Transient Elastography Measurements of Spleen Stiffness as a Predictor of Clinically Significant Varices in Children

OBJECTIVES

Investigate the use of spleen stiffness measurements (SSMs), measured by transient elastography (TE), for the prediction of clinically significant varices (CSV) in children with portal hypertension.

METHODS

This observational cohort study included children selected for endoscopy, as per department protocol, between September 2015 and June 2016. Those included underwent single TE FibroScan for liver stiffness measurements and SSM. Clinical and laboratory data were collected and variceal prediction scores were calculated at time of elastography.

RESULTS

In total 67 children (32 boys) underwent TE. Fifty-two children (25 boys) had chronic liver disease (CLD), 15 (7 boys) portal vein thrombosis (PVT). In all children SSM was the best predictor of CSV+ve, with an optimal cut-off value of 38.0 kPa (area under the receiver operator curve [AUROC] = 0.92, sensitivity = 89%, specificity = 82%, P < 0.01). In the CLD group SSM was also the best predictor, with an optimal cut-off value of 38.05 kPa (AUROC = 0.90, sensitivity = 84%, specificity = 87%, P < 0.01). In the PVT group only SSM was predictive of CSV+ve, with an optimal cut-off value of 16.8 kPa (AUROC = 1.00, sensitivity = 100%, specificity = 100%, P < 0.001). For the prediction of GI bleeding (n = 6), liver stiffness measurement performed the best, with an optimal cut-off value of 34.3 kPa (AUROC = 0.84, sensitivity of 80%, specificity of 88%, P = 0.01).

CONCLUSIONS

SSM was the greatest predictor of CSV+ve in the whole cohort, and individual CLD and PVT groups. SSM could be used as a noninvasive screening tool for children with portal hypertension to stratify the risk of having CSV.