Neonatal sclerosing cholangitis associated with autoimmune phenomena

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.

[Cholestasis-associated hepatopathies in neonates and infants]

Cholestasis in neonates and infants frequently confronts pediatricians and pathologists with diagnostic problems. A specific feature of the liver in neonates is the ability to react to different causative factors with a non-specific hepatitis-like picture, the so-called neonatal hepatitis. A diagnostic discrimination of the various diseases is histologically only possible with close attention to typical morphologic features. Thus, extrahepatic biliary obstructions, such as atresia or stenosis of the hepatic duct or choledochal cysts present with portal bile duct proliferation and signs of bile retention in the neoducts. In Alagille syndrome (arteriohepatic dysplasia), however, paucity of intrahepatic bile ducts is an important diagnostic feature. Metabolic disorders, such as fructosemia and galactosemia are additionally associated with steatosis. Knowledge of the clinical course and laboratory and imaging data are necessary to make the definitive diagnosis in synopsis with the morphologic findings and requires a close co-operation between the pediatrician and the pathologist.

Neonatal hepatitis syndrome

Conjugated hyperbilirubinaemia in an infant indicates neonatal liver disease. This neonatal hepatitis syndrome has numerous possible causes, classified as infective, anatomic/structural, metabolic, genetic, neoplastic, vascular, toxic, immune and idiopathic. Any infant who is jaundiced at 2-4 weeks old needs to have the serum conjugated bilirubin measured, even if he/she looks otherwise well. If conjugated hyperbilirubinaemia is present, a methodical and comprehensive diagnostic investigation should be performed. Early diagnosis is critical for the best outcome. In particular, palliative surgery for extrahepatic biliary atresia has the best chance of success if performed before the infant is 8 weeks old. Definitive treatments available for many causes of neonatal hepatitis syndrome should be started as soon as possible. Alternatively, liver transplantation may be life saving. Supportive care, especially with attention to nutritional needs, is important for all infants with neonatal hepatitis syndrome.

Sclerosing cholangitis

Primary sclerosing cholangitis is a chronic cholestatic disease that may have an autoimmune basis. Most patients have a circulating antineutrophil cytoplasmic antibody that appears to be targeted against a 50-kD nuclear envelope protein. The clinical applications of this antibody have not yet been defined. Other autoantibodies directed against antigens, such as cathepsin G, elastase, and anticardiolipin, may also be detected in some patients. It is suggested that primary sclerosing cholangitis may have a bacterial cause. Helicobacter gene sequences have been detected in liver tissues in primary sclerosing cholangitis. The role of Helicobacter spp and other bacteria in the etiopathogenesis of primary sclerosing cholangitis remains to be determined. Primary sclerosing cholangitis may overlap with autoimmune hepatitis in some cases, although the real prevalence of this association remains to be determined. Many prognostic models have been created, but they lack cross-validation, and their clinical usefulness remains limited. Endoscopic retrograde cholangiography remains the gold standard for diagnosis, but magnetic resonance imaging may be a viable alternative in many cases. Clinical trials with cladibrine, pentoxifylline, and budesonide have failed to demonstrate benefits. Orthotopic liver transplantation remains the only effective treatment.

Autoimmune liver disease

Autoimmune hepatitis in children may be associated with sclerosing cholangitis in the absence of inflammatory bowel disease. Wilson disease can have clinical and laboratory features that resemble autoimmune hepatitis, and it may respond initially to corticosteroids. Soluble HLA-DR antigens reflect clinical activity, and they may be useful markers of treatment response. Polymorphisms of the cytotoxic T lymphocyte antigen-4 gene may synergize with other autoimmune promoters or HLA risk factors to increase susceptibility and alter disease expression. DRB1*1301 distinguishes Argentine children from Argentine adults and identifies a unique subgroup. Antibodies to soluble liver antigen/liver-pancreas do not characterize a separate clinical entity. Their target antigen has been isolated, and it shares homologies with a selenocysteine-specific protecting factor (tRNP((Ser)Sec)). CYP2D6 is expressed on the hepatocyte surface, and it can be targeted by antibodies in autoimmune hepatitis and chronic hepatitis C. Perinuclear antineutrophil cytoplasmic antibodies lack sensitivity and specificity for autoimmune hepatitis, and they have diverse antigen specificities. Activation-induced cell death may be impaired in autoimmune hepatitis, and, in contrast to budesonide, mycophenolate mofetil has been effective in a small study of problematic patients.

North American Indian cirrhosis in children: a review of 30 cases

BACKGROUND

North American Indian childhood cirrhosis (NAIC) is a distinct, rapidly evolving form of familial cholestasis found in aboriginal children from northwestern Quebec. This is a retrospective review of the 30 patients treated in Quebec since the discovery of NAIC in 1970.

METHODS

The clinical records and histologic samples from 30 patients were reviewed. Extensive metabolic, biochemical, viral, genetic, and radiologic studies were performed in most patients.

RESULTS

Genetic analysis suggests autosomal recessive inheritance and a carrier frequency of 10% in this population. Gene mapping studies showed that the NAIC gene is located on chromosome 16q22. Typically, patients have neonatal cholestatic jaundice (70%) or hepatosplenomegaly (20%) with resolution of clinical jaundice by age 1 year but persistent direct hyperbilirubinemia. Portal hypertension was documented in 29 patients (91%). Variceal bleeding (15 patients, 50%) occurred as early as age 10 months. Surgical portosystemic shunting was performed in 13 of these 15 patients (87%); 4 (31%) rebled after 1 to 5 years. Fourteen patients died (47%). In 10 (71%), liver disease was the cause. Four children died of liver failure before liver transplantation became available. In transplanted livers, no recurrence of NAIC was observed after 1 to 10 years. Recognized infectious, metabolic, toxic, autoimmune, and obstructive causes of cirrhosis have been eliminated. The histologic features of NAIC show early bile duct proliferation and rapid development of portal fibrosis and biliary cirrhosis, suggesting a cholangiopathic phenomenon.

CONCLUSION

Together with gene mapping studies showing that the NAIC gene is different from those of other familial cholestases, these observations suggest that NAIC is a distinct entity that could be classified as "progressive familial cholangiopathy."