Immune-mediated cholangiopathies in children: the need to better understand the pathophysiology for finding the future possible treatment targets.

Cholangiopathies are defined as focal or extensive damage of the bile ducts. According to the pathogenetic mechanism, it may be immune-mediated or due to genetic, infectious, toxic, vascular, and obstructive causes. Their chronic evolution is characterized by inflammation, obstruction of bile flow, cholangiocyte proliferation, and progression toward fibrosis and cirrhosis. Immune-mediated cholangiopathies comprise primary sclerosing cholangitis (PSC), autoimmune cholangitis and IgG4-associated cholangitis in adults and biliary atresia (BA), neonatal sclerosing cholangitis (NSC) in children. The main purpose of this narrative review was to highlight the similarities and differences among immune-mediated cholangiopathies, especially those frequent in children in which cholangiocyte senescence plays a key role (BA, NSC, and PSC). These three entities have many similarities in terms of clinical and histopathological manifestations, and the distinction between them can be hard to achieve. In BA, bile duct destruction occurs due to aggression of the biliary cells due to viral infections or toxins during the intrauterine period or immediately after birth. The consequence is the activation of the immune system leading to severe inflammation and fibrosis of the extrahepatic biliary tract, lumen stenosis, and impairment of the biliary flow. PSC is characterized by inflammation and fibrosis of intra- and extrahepatic bile ducts, leading to secondary biliary cirrhosis. It is a multifactorial disease that occurs because of genetic predisposition [human leukocyte antigen (HLA) and non-HLA haplotypes], autoimmunity (cellular immune response, autoantibodies, association with inflammatory bowel disease), environmental factors (infections or toxic bile), and host factors (intestinal microbiota). NSC seems to be a distinct subgroup of childhood PSC that appears due to the interaction between genetic predisposition (HLA B8 and DR3) and the disruption of the immune system, validated by elevated IgG levels or specific antibodies [antinuclear antibody (ANA), anti-smooth muscle antibody (ASMA)]. Currently, the exact mechanism of immune cholangiopathy is not fully understood, and further data are required to identify individuals at high risk of developing these conditions. A better understanding of the immune mechanisms and pathophysiology of BA, NSC, and PSC will open new perspectives for future treatments and better methods of preventing severe evolution.

Childhood Cholestatic Liver Diseases that Persist Into Adulthood: Lessons for the Adult Gastroenterologist.

Children with cholestatic liver diseases are increasingly living into adulthood, thanks to innovations in medical and surgical therapies. The excellent outcomes observed in pediatric liver transplantation for diseases, such as biliary atresia, have transformed the life trajectory of children born with once-fatal liver diseases. The evolution of molecular genetic testing, has helped expedite the diagnosis of other cholestatic disorders, improving the clinical management, disease prognosis, and family planning for inherited disorders, such as progressive familial intrahepatic cholestasis and bile acid synthesis disorders. The expanding list of therapeutics, including bile acids and the newer ileal bile acid transport inhibitors, has also helped slow the progression of disease and improve the quality of life for certain diseases, like Alagille syndrome. More and more children with cholestatic disorders are expected to require care from adult providers familiar with the natural history and potential complications of these childhood diseases. The aim of this review is to bridge the gap between pediatric and adult care in children with cholestatic disorders. The present review addresses the epidemiology, clinical features, diagnostic testing, treatment, prognosis, and transplant outcomes of 4 hallmark childhood cholestatic liver diseases: biliary atresia, Alagille syndrome, progressive familial intrahepatic cholestasis, and bile acid synthesis disorders.

The presence of high-risk varices after sclerotherapy in biliary atresia.

BACKGROUND: Esophagogastric varices (EGVs) may develop as a result of portal hypertension in children with biliary atresia (BA). Although endoscopic injection sclerotherapy (EIS) with ethanolamine oleate (EO) is reported useful for children, risk factors associated with the presence of high-risk EGVs after treatment remain unknown. METHODS: The subjects were BA patients under 15 years of age who underwent EO-EIS. We retrospectively reviewed a total of 28 treatment sessions of EGVs with red signs and those larger than F2, which were considered to be at high risk of bleeding. Survival analysis was performed for the presence of high-risk EGVs at the time of follow-up endoscopy as the occurrence of an event. RESULTS: Univariate analysis showed a significantly increased risk of the presence of high-risk EGVs post-EO-EIS in patients with increased liver stiffness (LS) and Mac-2 binding protein glycan isomer (M2BPGi), with hazard ratios of 1.48 and 1.15, respectively. The median presence-free period was significantly shorter in the LS ≥ 2.8 m/s patients than in those with LS <2.8 m/s (189 vs. 266 days). Similarly, the median presence-free period was significantly shorter in patients with M2BPGi ≥ 4.0 than in those with M2BPGi < 4.0 (182 vs. 203 days). The results of multivariate analysis revealed that the risk of the presence of high-risk EGVs was significantly higher only in the high-LS group, with a hazard ratio of 2.76. CONCLUSIONS: Increased LS is associated with risk of the presence of high-risk EGVs following EO-EIS in children with BA.

[New advances in the diagnosis and treatment of biliary atresia]. / 胆道闭锁的诊断及治疗新进展.

The diagnosis of biliary atresia (BA) is mainly based on clinical manifestations, screening, and related biochemistry tests. In recent years, the development of blood biomarkers and the improvement in ultrasound examination have made it possible for BA to be diagnosed at a younger age. In particular, matrix metalloproteinase-7 shows high sensitivity and specificity and has a higher diagnostic efficiency than existing biochemical parameters, thereby holding a promise for clinical application. Sound touch elastography can increase the diagnostic efficiency for BA in terms of diagnosis and prognostic evaluation. Surgery is still the only method for the treatment of BA at present, with the preferred surgical treatment regimen of Kasai portoenterostomy combined with pharmacotherapies for alleviating infection and inflammation, and the patients who fail Kasai portoenterostomy or have liver dysfunction may require liver transplantation to save their lives. Therefore, the current research on BA should focus on the biomarkers for early diagnosis, specifically targeted drugs, and drugs for preventing progressive liver fibrosis. This article reviews the current diagnosis and treatment methods for BA and discusses the potential research directions.

Biliary Atresia in Children: Update on Disease Mechanism, Therapies, and Patient Outcomes.

Biliary atresia is a rare disease but remains the most common indication for pediatric liver transplantation as there are no effective medical therapies to slow progression after diagnosis. Variable contribution of genetic, immune, and environmental factors contributes to disease heterogeneity among patients with biliary atresia. Developing a deeper understanding of the disease mechanism will help to develop targeted medical therapies and improve patient outcomes.

Maternal regulation of biliary disease in neonates via gut microbial metabolites.

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.

Biliary Atresia/Neonatal Cholestasis: What is in the Horizon?

"Biliary atresia (BA) is a common cause of jaundice in infancy. There is increasing evidence that newborn screening with direct or conjugated bilirubin leads to earlier diagnosis. Although the Kasai portoenterostomy is the primary treatment, there are scientific advances in adjuvant therapies. As pediatric patients transition to adult care, multidisciplinary care is essential, given the complexity of this patient population."

Assessment of Lactobacillus casei rhamnosus (LGG) therapy in children with biliary atresia - Randomized placebo controlled trial.

BACKGROUND: The role of microbiota in biliary atresia (BA) remains unclear. The aim of our study was to assess efficacy and safety of LGG treatment in children with BA after HPE with special focus on bacterial cholangitis (BCH) and quantitative assessment of the gut microbiota composition and metabolism. METHODS: We performed double-blind placebo controlled trial with patients randomized into treatment group who received LGG (n = 14) and placebo (n = 16). The gut microbiota and short-chain fatty acids (SCFA) were assessed at baseline and after 6 months of treatment. Clinical and laboratory parameters including episodes of bacterial cholangitis (BCH) were collected during the study period and after 2-year follow-up. Additionally, stool composition of BA patients was compared with healthy age-matched control group. RESULTS: There were lower concentration of SCFA in children with BA compared to control group and significant increase in the number of Enterococcus bacteria. After 6 months of treatment, neither laboratory parameters nor gut microbiota composition differed between LGG group and placebo. PP analysis results were similar to ITT analysis, no significant differences between study and control group. Overall, there were 11 (36%) patients who developed at least one episode of bacterial cholangitis; 3 (21%) in the LGG group compared to 8 (50%) placebo group (p = 0.14). Bacterial cultures were positive in 22% of cases and recurrence after the first episode was observed in 27% of patients. The level of total bilirubin decreased below 2 mg/dl after 6 months of the study in 6 (42.8%) patients in the LGG group and in 8 (50%) patients in the placebo group (p = 0.73). During 2-year follow-up 6 out of 14 patients (42.8%) in the LGG group and 11 out of 16 placebo patients (68.7%) underwent liver transplantation (p = 0.27). CONCLUSIONS: Patients with BA present with specific microbiota profiles and decreased SCFA what gives opportunities to implement novel therapeutic options based on modulation of  microbiota. Whether LGG is an effective therapy needs to be studied in a larger group with similar outcome parameters.

Hepatic hydrothorax in a child and its management.

Hepatic hydrothorax is a rare complication of portal hypertension. The optimal treatment for this condition is liver transplantation. Liver transplantation is significantly more manageable in children who weigh more than 8 kg. Here, an implantable pleural access device was used in a 5-month-old infant for painless iterative punctures to relieve respiratory symptoms, while waiting for liver transplantation and the patient's growth. The patient underwent successful transplantation 3 months later with a more optimal weight.

Liver Immune Profiling Reveals Pathogenesis and Therapeutics for Biliary Atresia.

Biliary atresia (BA) is a severe cholangiopathy that leads to liver failure in infants, but its pathogenesis remains to be fully characterized. By single-cell RNA profiling, we observed macrophage hypo-inflammation, Kupffer cell scavenger function defects, cytotoxic T cell expansion, and deficiency of CX3CR1+effector T and natural killer (NK) cells in infants with BA. More importantly, we discovered that hepatic B cell lymphopoiesis did not cease after birth and that tolerance defects contributed to immunoglobulin G (IgG)-autoantibody accumulation in BA. In a rhesus-rotavirus induced BA model, depleting B cells or blocking antigen presentation ameliorated liver damage. In a pilot clinical study, we demonstrated that rituximab was effective in depleting hepatic B cells and restoring the functions of macrophages, Kupffer cells, and T cells to levels comparable to those of control subjects. In summary, our comprehensive immune profiling in infants with BA had educed that B-cell-modifying therapies may alleviate liver pathology.

Predicting native liver injury and survival in biliary atresia.

Several patient and treatment related factors significantly modify outcomes of biliary atresia. The extremely variable prognosis mandates intensive postoperative monitoring following portoenterostomy. Accurate prediction of outcome and progression of liver injury would enable individualized treatment and follow-up protocols, patient counseling and meaningful stratification of patients into clinical trials. While results on most biomarkers of cholestasis, hepatocyte function, fibrosis and inflammation studied so far are inconsistent or have not been validated in independent patient cohorts, postoperative serum bilirubin level 3 months after portoenterostomy remains the most accurate clinically feasible predictor of native liver survival. Although liver stiffness and a novel marker of cholangiocyte integrity, serum matrix metalloproteinase-7, correlate with liver fibrosis and may discriminate biliary atresia from other causes of neonatal cholestasis, further information on their ability to predict portoenterostomy outcomes is needed. Recent gene expression profiling has shown promise in overcoming the sampling error associated with histological quantification of liver fibrosis, and provides an important possibility to stratify patients for clinical trials according to the prognosis of native liver survival already preoperatively. As activity and extent of ductular reaction is linked with progression of liver fibrosis in cholangiopathies, further research is also warranted to evaluate predictive value of ductular reaction, matrix metalloproteinase-7 and the underlying gene expression signatures in relation to circulating bile acids in biliary atresia. Discovery of accurate predictive tools will ultimately increase our understanding of the unpredictable response to surgery and pathophysiology of progressive liver injury in biliary atresia.

Transitional care of biliary atresia.

Worldwide native liver survival (NLS) for young adults (>20 years) with biliary atresia varies between 14% and 44% with the majority of patients developing complications in adulthood. Cholangitis and portal hypertension with variceal bleeding are the most common complications and development of these during adolescence associated with the need for liver transplantation during adulthood. Adult listing criteria, typically developed on the background of adult liver disease might not be applicable to this patient population and leads to longer waiting time and risk of deterioration of their medical condition. Current data on growth and puberty in young people with biliary atresia surviving with native liver are rare. Pregnancy has been associated with serious complications in particular for those patients with advanced liver disease and, close follow up by specialist teams recommended. The long-term effect of having a chronic liver disease such as biliary atresia on neuro-cognitive and pubertal development has not been sufficiently explored to date despite reports of a high prevalence of additional educational needs in this cohort. In addition, patients and parents report inferior health related quality of life compared to healthy peers and similar to that of children post liver transplantation. Moving on from paediatric to adult services is challenging for young people and their parents and adult health professionals might not be familiar with the condition and complications. Young people deserve to be looked after by specialist, multidisciplinary services who provide holistic care and address their psychosocial needs in addition to the medical needs.

Ileal bile acid transporter inhibition as an anticholestatic therapeutic target in biliary atresia and other cholestatic disorders.

Biliary atresia is a rare cholestatic liver disease that presents in infants and rapidly advances to death in the absence of intervention. As a result of blockage or destruction of the biliary tract, bile acids accumulate and drive inflammation, fibrosis, and disease progression. The standard of care, Kasai portoenterostomy (KPE), is typically performed shortly after diagnosis (currently at ~ 2 months of age) and aims to restore bile flow and relieve cholestasis. Nevertheless, most patients continue to experience liver injury from accumulation of bile acids after KPE, since there are no known effective therapeutics that may enhance survival after KPE. Improving cholestasis via interruption of the enterohepatic circulation of bile acids may directly attenuate hepatic bile acid retention and reduce the risk of early organ failure. Directly addressing intrahepatic accretion of bile acids to avoid inherent bile acid toxicities provides an attractive and plausible therapeutic target for biliary atresia. This review explores the novel therapeutic concept of inhibiting the sole ileal bile acid transporter (IBAT), also known as ASBT (apical sodium-bile acid transporter, encoded by SLC10A2), as a means to reduce hepatic bile acid concentration after KPE. By reducing return of bile acids to the cholestatic liver, IBAT inhibitors may potentially lessen or delay liver damage associated with the hepatotoxicity and cholangiopathy of bile acid accumulation. The clinical programs of 2 IBAT inhibitors in development for the treatment of pediatric cholestatic liver diseases, maralixibat and odevixibat, are highlighted.

Innate Immunity and Pathogenesis of Biliary Atresia.

Biliary atresia (BA) is a devastating fibro-inflammatory disease characterized by the obstruction of extrahepatic and intrahepatic bile ducts in infants that can have fatal consequences, when not treated in a timely manner. It is the most common indication of pediatric liver transplantation worldwide and the development of new therapies, to alleviate the need of surgical intervention, has been hindered due to its complexity and lack of understanding of the disease pathogenesis. For that reason, significant efforts have been made toward the development of experimental models and strategies to understand the etiology and disease mechanisms and to identify novel therapeutic targets. The only characterized model of BA, using a Rhesus Rotavirus Type A infection of newborn BALB/c mice, has enabled the identification of key cellular and molecular targets involved in epithelial injury and duct obstruction. However, the establishment of an unleashed chronic inflammation followed by a progressive pathological wound healing process remains poorly understood. Like T cells, macrophages can adopt different functional programs [pro-inflammatory (M1) and resolutive (M2) macrophages] and influence the surrounding cytokine environment and the cell response to injury. In this review, we provide an overview of the immunopathogenesis of BA, discuss the implication of innate immunity in the disease pathogenesis and highlight their suitability as therapeutic targets.

Routine Postoperative Antithrombotic Therapy in Pediatric Liver Transplantation: Impact on Bleeding and Thrombotic Complications.

BACKGROUND: Hepatic artery thrombosis (HAT) and portal vein thrombosis (PVT) are serious causes of morbidity and mortality after pediatric liver transplantation. To reduce thrombotic complications, routine antithrombotic therapy consisting of 1 week heparin followed by 3 months acetylsalicylic acid, was implemented in our pediatric liver transplant program in 2003. This study aimed to evaluate incidences of bleeding and thrombotic complications since the implementation of routine antithrombotic therapy and to identify risk factors for these complications. METHODS: This retrospective cohort study includes 200 consecutive pediatric primary liver transplantations performed between 2003 and 2016. Uni- and multivariate logistic regression analysis, Kaplan-Meier method, and Cox regression analysis were used to evaluate recipient outcome. RESULTS: HAT occurred in 15 (7.5%), PVT in 4 (2.0%), and venous outflow tract thrombosis in 2 (1.0%) recipients. Intraoperative vascular interventions (odds ratio [OR] 14.45 [95% confidence interval [CI] 3.75-55.67]), low recipient age (OR 0.81 [0.69-0.95]), and donor age (OR 0.96 [0.93-0.99]) were associated with posttransplant thrombosis. Clinically relevant bleeding occurred in 37%. Risk factors were high recipient age (OR 1.08 [1.02-1.15]), high Child-Pugh scores (OR 1.14 [1.02-1.28]), and intraoperative blood loss in mL/kg (OR 1.003 [1.001-1.006]). Both posttransplant thrombotic (hazard ratio [HR] 3.38 [1.36-8.45]; p = 0.009) and bleeding complications (HR 2.50 [1.19-5.24]; p = 0.015) significantly increased mortality. CONCLUSION: In 200 consecutive pediatric liver transplant recipients receiving routine postoperative antithrombotic therapy, we report low incidences of posttransplant vascular complications. Posttransplant antithrombotic therapy seems to be a valuable strategy in pediatric liver transplantation. Identified risk factors for bleeding and thrombotic complications might facilitate a more personalized approach in antithrombotic therapy.

Intestinal organoids in infants and children.

Recent advances in culturing of intestinal stem cells and pluripotent stem cells have led to the development of intestinal organoids. These are self-organizing 3D structures, which recapitulate the characteristics and physiological features of in vivo intestinal epithelium. Intestinal organoids have allowed the development of novel in vitro models to study various gastrointestinal diseases expanding our understanding of the pathophysiology of diseases and leading to the development of innovative therapies. This article aims to summarize the current usage of intestinal organoids as a model of gastrointestinal diseases and the potential applications of intestinal organoids in infants and children. Intestinal organoids allow the study of intestinal epithelium responses to stress factors. Mimicking intestinal injury such as necrotizing enterocolitis, intestinal organoids increases the expression of pro-inflammatory cytokine genes and shows disruption of tight junctions after they are injured by lipopolysaccharide and hypoxia. In cystic fibrosis, intestinal organoids derived from rectal biopsies have provided benefits in genetic studies and development of novel therapeutic gene modulation. Transplantation of intestinal organoids via enema has been shown to rescue damaged colonic epithelium in mice. In addition, tissue-engineered small intestine derived from intestinal organoids have been successfully established providing a potential novel treatment and a new hope for children with short bowel syndrome.

Living Donor Liver Transplantation in Biliary Atresia Children with Pulmonary Hypertension.

OBJECTIVE: Though living donor liver transplantation (LDLT) is commonly performed for pediatric patients with biliary atresia (BA), pulmonary hypertension (PH) is seldom encountered or reported previously. The aim of this study is mainly to identify the prevalence of PH in pediatric patients undergoing liver transplantation and assess whether PH significantly augment the operative risk and evaluate the outcomes in this series of patients. DESIGN: Retrospectively cohort study. SETTING: Renji hospital, Shanghai, China. PARTICIPANTS: This study comprised 161 pediatric patients undergoing LDLT. INTERVENTIONS: Patient diagnosed of PH in preoperative examination was compared to those without PH in intra- or post- operative complications or outcomes. MEASUREMENTS AND MAIN RESULTS: We collected clinical records of LDLT surgery for pediatric patients during the year of 2016 in our hospital. Results suggested that pediatric patients undergoing LDLT had a substantial number of PH with a prevalence of 16.1% in this study. No significant difference was identified between two groups of patients regarding intraoperative outcomes and postoperative complications and mortality. CONCLUSION: LDLT is a safe procedure in a selected group of BA patients with PH, however, further long-term clinical investigations and mechanical researches are needed.

Translational Research in Biliary Atresia: News from Mice and Men.

Biliary atresia (BA) is a fibro-obliterative cholangiopathy of unknown etiology. While Kasai portoenterostomy achieves temporary biliary drainage in some cases, BA remains the most common indication for liver transplantation during childhood. During the last few decades, observations on BA, like cholestatic diseases in animals and the introduction of different animal models for BA, have not achieved the anticipated results, and we are still not able to translate the basic research to the patient's bedside. This article presents a review of the literature on available BA animal models and gives a glimpse of future developments.