Biliary atresia (BA) is a progressive, fibrosing cholangiopathy of infancy characterized by inflammatory obstruction of the bile ducts, ultimately leading to end-stage liver disease if untreated. Early diagnosis and timely surgical intervention via hepatoportoenterostomy (HPE) are critical for improving outcomes; however, prognostication remains challenging due to heterogeneous responses to surgery and variable clinical trajectories. This review provides a comprehensive synthesis of current research on prognostic biomarkers in BA, encompassing clinical indicators, routine laboratory parameters, novel serum biomarkers, histopathologic features, hepatic gene expression profiles, imaging modalities, and both in vitro and computational prognostic modeling systems. While traditional clinical factors, such as age at HPE and postoperative serum bilirubin levels, continue to serve as important predictors of outcome, they lack sufficient discriminatory power for individualized risk stratification. Recent advances have identified emerging biomarkers, including inflammatory cytokines, immune activation markers, and indicators of fibrosis and extracellular matrix remodeling, which show potential in correlating with disease progression and native liver survival. Imaging modalities such as ultrasound elastography have also demonstrated promise in noninvasively assessing liver stiffness and predicting clinical outcomes. Furthermore, the identification of hepatic gene expression signatures and multigene prognostic classifiers offers new avenues for precision risk assessment. However, most of these advancements have not translated into clinical practice due to small sample sizes and limited external validation. Future research efforts must focus on large-scale, multicenter studies to validate findings and establish robust, integrative prognostic models that can inform clinical decision-making and facilitate personalized therapeutic strategies in BA.

Deficiencies in the development of epithelial structures and delays in cellular maturation can increase the susceptibility of neonates to disease early in life. To investigate human biliary development and its vulnerability to biliary atresia, a severe pediatric cholangiopathy, we engineered multi-compartment biliary organoids (MBOs) from co-cultures of human liver-derived epithelial organoid cells with human endothelial and mesenchymal cells. MBOs derived from normal livers effectively replicated the epithelial structure of the bile duct epithelium and peribiliary glands (PBGs). Conversely, MBOs from diseased livers exhibited defective epithelial layers, a significant epithelial-mesenchymal transition (EMT), and an activation of the TGF-β/Activin-SMAD2/3 signaling, primarily due to intermediary cell sub-populations. Inhibition of TGF-β signaling suppressed EMT and promoted biliary epithelial development in human MBOs and suppressed the phenotype of experimental biliary atresia in neonatal mice. Thus, the modulation of TGF-β-dependent EMT regulates bile duct epithelial development and influences the susceptibility of neonates to biliary injuries.

Background:Matrix metalloproteinase 7 (MMP-7) is a novel biomarker for diagnosis of biliary atresia (BA), the most common cholestatic liver disease in infancy. There is a pressing need to determine the utility of MMP-7 levels in infants with congenital heart disease (CHD) to avoid unnecessary invasive diagnostic procedures in this high-risk population. We investigated the utility of MMP-7 in discriminating BA from non-BA cholestasis in infants with CHD and whether MMP-7 elevation was present in infants requiring treatment for clinically significant PH. Methods: This is a single center cross sectional study including infants <180 days of age with cholestasis and serum MMP-7 levels collected from 2019-2023. Demographic data and descriptive statistics were summarized with medians with interquartile ranges and frequencies with percentages. Median MMP-7 levels were assessed via Wilcoxon rank-sum test. Results: A total of 149 patients were included. Patients with CHD had significantly elevated MMP-7 levels relative to the non-CHD cohort (50 vs. 34 ng/mL, p=0.009). Sub-analysis comparing infants with and without PH revealed significantly elevated median MMP-7 levels in those with clinically significant PH (125 vs. 39 ng/mL, p=0.010). CHD patients with PH had greater median MMP-7 compared to CHD patients without PH (154 vs 43 ng/mL, p=0.028). Conclusions:Serum MMP-7 levels in infants with CHD-C were significantly elevated compared to those with cholestasis alone. MMP-7 may help identify non-BA cholestatic infants who have concurrent clinically significant pulmonary hypertension. Larger, prospective studies are needed to validate this finding and establish CHD-specific MMP-7 cutoffs.

EDITORIAL article Front. Pediatr., 28 March 2023Sec. Pediatric Gastroenterology, Hepatology and Nutrition Volume 11 - 2023 | https://doi.org/10.3389/fped.2023.1175231

BACKGROUND AND AIMS:Although a dysregulated type 1 immune response is integral to the pathogenesis of biliary atresia, studies in both humans and mice have uncovered a type 2 response, primarily driven by type 2 innate lymphoid cells. In nonhepatic tissues, natural type 2 innate lymphoid cell (nILC2s) regulate epithelial proliferation and tissue repair, whereas inflammatory ILC2s (iIlC2s) drive tissue inflammation and injury. The aim of this study is to determine the mechanisms used by type 2 innate lymphoid cell (ILC2) subpopulations to regulate biliary epithelial response to an injury.APPROACH AND RESULTS:Using Spearman correlation analysis, nILC2 transcripts, but not those of iILC2s, are positively associated with cholangiocyte abundance in biliary atresia patients at the time of diagnosis. nILC2s are identified in the mouse liver through flow cytometry. They undergo expansion and increase amphiregulin production after IL-33 administration. This drives epithelial proliferation dependent on the IL-13/IL-4Rα/STAT6 pathway as determined by decreased nILC2s and reduced epithelial proliferation in knockout strains. The addition of IL-2 promotes inter-lineage plasticity towards a nILC2 phenotype. In experimental biliary atresia induced by rotavirus, this pathway promotes epithelial repair and tissue regeneration. The genetic loss or molecular inhibition of any part of this circuit switches nILC2s to inflammatory type 2 innate lymphoid cell-like, resulting in decreased amphiregulin production, decreased epithelial proliferation, and the full phenotype of experimental biliary atresia.CONCLUSIONS:These findings identify a key function of the IL-13/IL-4Rα/STAT6 pathway in ILC2 plasticity and an alternate circuit driven by IL-2 to promote nILC2 stability and amphiregulin expression. This pathway induces epithelial homeostasis and repair in experimental biliary atresia.

Maternal seeding of the microbiome in neonates promotes a long-lasting biological footprint, but how it impacts disease susceptibility in early life remains unknown. We hypothesized that feeding butyrate to pregnant mice influences the newborn's susceptibility to biliary atresia, a severe cholangiopathy of neonates. Here, we show that butyrate administration to mothers renders newborn mice resistant to inflammation and injury of bile ducts and improves survival. The prevention of hepatic immune cell activation and survival trait is linked to fecal signatures of Bacteroidetes and Clostridia and increases glutamate/glutamine and hypoxanthine in stool metabolites of newborn mice. In human neonates with biliary atresia, the fecal microbiome signature of these bacteria is under-represented, with suppression of glutamate/glutamine and increased hypoxanthine pathways. The direct administration of butyrate or glutamine to newborn mice attenuates the disease phenotype, but only glutamine renders bile duct epithelial cells resistant to cytotoxicity by natural killer cells. Thus, maternal intake of butyrate influences the fecal microbial population and metabolites in newborn mice and the phenotypic expression of experimental biliary atresia, with glutamine promoting survival of bile duct epithelial cells.

BACKGROUND:Biliary atresia is a neonatal disease characterized by choledochal obstruction and progressive cholangiopathy requiring liver transplantation in most patients. Hypoxia-ischemia affecting the biliary epithelium may lead to biliary obstruction. We hypothesized that ischemic cholangiopathy involving disruption of the peribiliary vascular plexus could act as a triggering event in biliary atresia pathogenesis. METHODS:Liver and porta hepatis paraffin-embedded samples of patients with biliary atresia or intrahepatic neonatal cholestasis (controls) were immunohistochemically evaluated for HIF-1alpha-nuclear signals. Frozen histological samples were analyzed for gene expression in molecular profiles associated with hypoxia-ischemia. Prospective clinical-laboratory and histopathological data of biliary atresia patients and controls were reviewed. RESULTS:Immunohistochemical HIF-1alpha signals localized to cholangiocytes were detected exclusively in liver specimens from biliary atresia patients. In 37.5% of liver specimens, HIF-1alpha signals were observed in biliary structures involving progenitor cell niches and peribiliary vascular plexus. HIF-1alpha signals were also detected in biliary remnants of 81.8% of porta hepatis specimens. Increased gene expression of molecules linked to REDOX status, biliary proliferation, and angiogenesis was identified in biliary atresia liver specimens. In addition, there was a trend towards decreased GSR expression levels in the HIF-1alpha-positive group compared to the HIF-1alpha-negative group. CONCLUSION:Activation of the HIF-1alpha pathway may be associated with the pathogenesis of biliary atresia, and additional studies are necessary to confirm the significance of this finding. Ischemic cholangiopathy and REDOX status disturbance are putative explanations for HIF-1alpha activation. These findings may give rise to novel lines of clinical and therapeutic investigation in the BA field.

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver and a leading cause of death in the US and worldwide. HCC remains a global health problem and is highly aggressive with unfavorable prognosis. Even with surgical interventions and newer medical treatment regimens, patients with HCC have poor survival rates. These limited therapeutic strategies and mechanistic understandings of HCC immunopathogenesis urgently warrant non-palliative treatment measures. Irrespective of the multitude etiologies, the liver microenvironment in HCC is intricately associated with chronic necroinflammation, progressive fibrosis, and cirrhosis as precedent events along with dysregulated innate and adaptive immune responses. Central to these immunological networks is the complement cascade (CC), a fundamental defense system inherent to the liver which tightly regulates humoral and cellular responses to noxious stimuli. Importantly, the liver is the primary source for biosynthesis of >80% of complement components and expresses a variety of complement receptors. Recent studies implicate the complement system in liver inflammation, abnormal regenerative responses, fibrosis, carcinogenesis, and development of HCC. Although complement activation differentially promotes immunosuppressive, stimulant, and angiogenic microenvironments conducive to HCC development, it remains under-investigated. Here, we review derangement of specific complement proteins in HCC in the context of altered complement regulatory factors, immune-activating components, and their implications in disease pathogenesis. We also summarize how complement molecules regulate cancer stem cells (CSCs), interact with complement-coagulation cascades, and provide therapeutic opportunities for targeted intervention in HCC.

BACKGROUND AND AIMS:Biliary atresia is a severe inflammatory and fibrosing cholangiopathy of neonates of unknown etiology. The onset of cholestasis at birth implies a prenatal onset of liver dysfunction. Our aim was to investigate the mechanisms linked to abnormal cholangiocyte development.APPROACH AND RESULTS:We generated biliary organoids from liver biopsies of infants with biliary atresia and normal and diseased controls. Organoids emerged from biliary atresia livers and controls and grew as lumen-containing spheres with an epithelial lining of cytokeratin-19pos albuminneg SOX17neg cholangiocyte-like cells. Spheres had similar gross morphology in all three groups and expressed cholangiocyte-enriched genes. In biliary atresia, cholangiocyte-like cells lacked a basal positioning of the nucleus, expressed fewer developmental and functional markers, and displayed misorientation of cilia. They aberrantly expressed F-actin, β-catenin, and Ezrin, had low signals for the tight junction protein zonula occludens-1 (ZO-1), and displayed increased permeability as evidenced by a higher Rhodamine-123 (R123) signal inside organoids after verapamil treatment. Biliary atresia organoids had decreased expression of genes related to EGF signaling and FGF2 signaling. When treated with EGF+FGF2, biliary atresia organoids expressed differentiation (cytokeratin 7 and hepatocyte nuclear factor 1 homeobox B) and functional (somatostatin receptor 2, cystic fibrosis transmembrane conductance regulator [CFTR], aquaporin 1) markers, restored polarity with improved localization of F-actin, β-catenin and ZO-1, increased CFTR function, and decreased uptake of R123.CONCLUSIONS:Organoids from biliary atresia are viable and have evidence of halted epithelial development. The induction of developmental markers, improved cell-cell junction, and decreased epithelial permeability by EGF and FGF2 identifies potential strategies to promote epithelial maturation and function.