Lack of correlation between infection with reovirus 3 and extrahepatic biliary atresia or neonatal hepatitis

Congenital aflatoxicosis, mal-detoxification genomics & ontogeny trigger immune-mediated Kotb disease biliary atresia variant: SANRA compliant review

Biliary atresia (BA) is the most common indication for pediatric liver transplantation. We describe The BA variant: Kotb disease. Liver tissue in the Kotb disease BA is massively damaged by congenital aflatoxicosis resulting in inflammation, adhesions, fibrosis, bile duct proliferation, scarring, cholestasis, focal syncytial giant cell transformation, and typical immune response involving infiltration by CD4+, CD8+, CD68+, CD14+, neutrophil infiltration, neutrophil elastase spill, heavy loads of aflatoxin B1, accelerated cirrhosis, disruption of p53 and GSTPi, and have null glutathione S transferase M1 (GSTM1). All their mothers are heterozygous for GSTM1. This inability to detoxify aflatoxicosis results in progressive inflammatory adhesions and obliterative cholangiopathy early in life. The typical disruption of both p53 and GSTPi causes loss of fidelity of hepatic regeneration. Hence, regeneration in Kotb disease BA typically promotes accelerated cirrhosis. The immune response in Kotb disease BA is for damage control and initiation of regeneration, yet, this friendly fire incurs massive structural collateral damage. The Kotb disease BA is about actual ongoing hepatic entrapment of aflatoxins with lack of ability of safe disposal due to child detoxification-genomics disarray. The Kotb disease BA is a product of the interaction of persistent congenital aflatoxicosis, genetic lack of GSTM1 detoxification, ontogenically impaired activity of other hepatic detoxification, massive neutrophil-elastase, immune-induced damage, and disturbed regeneration. Ante-natal and neonatal screening for aflatoxicosis, avoiding cord milking, and stringent control of aflatoxicosis content of human, poultry and live-stock feeds might prove effective for prevention, prompt diagnosis and management based on our recent understanding of its patho-genomics.

Biliary atresia: pathology, etiology and pathogenesis

Biliary atresia is a progressive fibrosing obstructive cholangiopathy of the intrahepatic and extrahepatic biliary system, resulting in obstruction of bile flow and neonatal jaundice. Histopathological findings in liver biopsies include the expansion of the portal tracts, with edematous fibroplasia and bile ductular proliferation, with bile plugs in duct lumen. Lobular morphological features may include variable multinucleate giant cells, bilirubinostasis and hemopoiesis. The etiopathogenesis of biliary atresia is multifactorial and multiple pathomechanisms have been proposed. Experimental and clinical studies have suggested that viral infection initiates biliary epithelium destruction and release of antigens that trigger a Th1 immune response, which leads to further injury of the bile duct, resulting in inflammation and obstructive scarring of the biliary tree. It has also been postulated that biliary atresia is caused by a defect in the normal remodelling process. Genetic predisposition has also been proposed as a factor for the development of biliary atresia.

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.

Sclerosing and obstructive cholangiopathy in biliary atresia: mechanisms and association with biliary innate immunity

Biliary atresia (BA) is histologically characterized by a progressive, sclerosing cholangitis and the obstruction of extrahepatic bile ducts. In terms of the etiology and pathogenesis of BA, several viral infections consisting of dsRNA, including Reoviridae, have been implicated. Human biliary epithelial cells (BECs) possess an innate immune system consisting of Toll-like receptors (TLRs). BECs have negative regulatory mechanisms of TLR tolerance to avoid an excessive inflammatory response to lipopolysaccharide (LPS), a TLR4 ligand; however, they lack the tolerance to poly(I:C) (a synthetic analog of viral dsRNA), a TLR3 ligand. Treatment with poly(I:C) induces the expression of the apoptosis-inducer TNF-related apoptosis-inducing ligand (TRAIL), along with the antiviral molecule IFN-β1, and reduces the viability of BECs by enhancing apoptosis. In response, surviving BECs increase their expression of various markers, including basic FGF [an epithelial-mesenchymal transition (EMT)-inducer], S100A4 (a mesenchymal marker), and Snail (a transcriptional factor), and decrease that of epithelial markers such as CK19 and E-cadherin before undergoing EMT. Extrahepatic bile ducts in BA infants frequently show a lack of epithelial markers and an aberrant expression of vimentin, in addition to the enhancement of TRAIL and apoptosis. dsRNA viruses may directly induce apoptosis and EMT in human BECs as a result of the biliary innate immune response, supporting the notion that Reoviridae infections may be directly associated with the pathogenesis of cholangiopathies in BA.

Evidence for viral infection as a causative factor of human biliary atresia

OBJECTIVES

To explore the evidence for viral infections triggering human biliary atresia (BA) by reviewing archival original articles that analyzed human samples via polymerase chain reaction (PCR) experiments, considering the recent experimental trend of extensive use of rotaviral BA animal models.

METHODS

A PubMed search retrieved original articles that reported the results of PCR experiments for detecting viral DNA or RNA in patient samples as proof of past infection. Search terms included the often-debated DNA or RNA viruses and BA. Special focus was directed toward PCR analyses that targeted reovirus and rotavirus, where PCR accuracy, specimen characteristics and their interpretations were compared.

RESULTS

Nineteen studies were conducted on 16 different kinds of viruses using PCR, with 5 studies on reovirus, 3 on rotavirus, 10 on cytomegalovirus, 5 on Epstein-Barr virus, 4 on parvovirus B19, and so on. Among the papers suggesting a possible viral link to only BA, there was no study on reovirus, 1 on rotavirus, 3 on cytomegalovirus, 1 on EB virus, and 1 on papillomavirus. Of the 6 PCR studies on Reoviridae, 3 on reovirus and 2 on rotavirus were evaluated rigorously for experimental accuracy, including their sensitivity. Two research groups analyzed preoperative stool samples in addition to generic hepatobiliary tissue obtained at surgery. Sample collection timing varied widely, with storage period prior to PCR experimentation not revealed in most reports on Reoviridae.

CONCLUSION

Although a considerable number of PCR studies have sought to clarify a viral role in the pathogenesis of BA using human samples, the findings have been contradictory and have not succeeded in achieving an obvious differentiation between causative and accidental infection of the focused virus. Reproducible and convincing evidence for a causative Reoviridae infection has been lacking based on objective data from highly sensitive PCR experiments. Even though the possibility remains of viral disappearance at the timing of collection, to avoid further ambiguous interpretations of PCR results, rigorous and meticulous collection of large numbers of specimens at carefully planned timing, along with a strictly adjusted and finely tuned PCR system, is strongly recommended for obtaining more reliable and consistent results.

A phase I trial and viral clearance study of reovirus (Reolysin) in children with relapsed or refractory extra-cranial solid tumors: a Children's Oncology Group Phase I Consortium report

BACKGROUND

Reovirus is a naturally occurring human virus that is cytopathic to malignant cells possessing an activated Ras signaling pathway. We conducted a phase I trial of Reolysin, a manufactured, proprietary isolate of purified reovirus, in children with relapsed/refractory extracranial solid tumors to define the recommended phase 2 dose (RP2D), toxicities, and pharmacokinetic properties when administered as a single agent or in combination with cyclophosphamide.

PROCEDURES

Reolysin was administered intravenously for 5 consecutive days, every 28 days. Using a 3 + 3 design, the following dose levels were evaluated: 3 × 10(8) Tissue Culture Inhibitory Dose 50% (TCID50 )/kg; 5 × 10(8) TCID50 /kg (maximum dose was 3 × 10(10) TCID50 ); and 5 × 10(8) TCID50 /kg plus oral cyclophosphamide (50 mg/m(2) /day × 21 days).

RESULTS

Twenty-nine patients were enrolled; 28 were eligible and 24 were evaluable for toxicity and response. There were no hematologic dose-limiting toxicities. Grade 5 respiratory failure and a Grade 5 thromboembolic event were reported, both in the setting of progressive disease. The median time to clear the reovirus viremia was 6.5 days. Eight of 24 patients were viremic beyond the 5 days of therapy, all were negative by day 17. No patient had detectable viral RNA in saliva or stool. There were no objective responses.

CONCLUSIONS

Reolysin at a dose of 5 × 10(8) TCID50 /kg daily for 5 days was well tolerated in children alone and in combination with oral cyclophosphamide. Virus was cleared rapidly from the serum and shedding in stool and saliva was not detectable.

Interleukin-32 production associated with biliary innate immunity and proinflammatory cytokines contributes to the pathogenesis of cholangitis in biliary atresia

Biliary atresia (BA) is thought to be associated with infections by viruses such as Reoviridae and is characterized histologically by fibrosclerosing cholangitis with proinflammatory cytokine-mediated inflammation. Interleukin (IL)-32 affects the continuous inflammation by increasing the production of proinflammatory cytokines. In this study, the role of IL-32 in the cholangitis of BA was examined. Immunohistochemistry for IL-32 and caspase 1 was performed using 21 samples of extrahepatic bile ducts resected from BA patients. Moreover, using cultured human biliary epithelial cells (BECs), the expression of IL-32 and its induction on stimulation with a Toll-like receptor [(TLR)-3 ligand (poly(I:C)] and proinflammatory cytokines was examined. BECs composing extrahepatic bile ducts showing cholangitis expressed IL-32 in BA, but not in controls. Caspase 1 was expressed constantly on BECs of both BA and control subjects. Furthermore, poly(I:C) and proinflammatory cytokines [(IL-1β, interferon (IFN)-γ and tumour necrosis factor (TNF)-α] induced IL-32 expression strongly in cultured BECs, accompanying the constant expression of TLR-3 and caspase 1. Our results imply that the expression of IL-32 in BECs was found in the damaged bile ducts of BA and induced by biliary innate immunity via TLR-3 and proinflammatory cytokines. These findings suggest that IL-32 is involved initially in the pathogenic mechanisms of cholangitis in BA and also plays an important role in the amplification and continuance of periductal inflammatory reactions. It is therefore tempting to speculate that inhibitors of IL-32 could be useful for attenuating cholangitis in BA.

Clues to the etiology of bile duct injury in biliary atresia

Biliary atresia (BA) is an infantile obstructive cholangiopathy of unknown etiology with suboptimal therapy, which is responsible for 40 to 50% of all pediatric liver transplants. Although the etiology of bile duct injury in BA in unknown, it is postulated that a pre- or perinatal viral infection initiates cholangiocyte apoptosis and release of antigens that trigger a Th1 immune response that leads to further bile duct injury, inflammation, and obstructive fibrosis. Humoral immunity and activation of the innate immune system may also play key roles in this process. Moreover, recent investigations from the murine BA model and human data suggest that regulatory T cells and genetic susceptibility factors may orchestrate autoimmune mechanisms. What controls the coordination of these events, why the disease only occurs in the first few months of life, and why a minority of infants with perinatal viral infections develop BA are remaining questions to be answered.

Detection of hepatotropic viruses has no impact on the prognosis after Kasai procedure

BACKGROUND/PURPOSE

A viral origin of biliary atresia (BA) is discussed, and several studies have demonstrated different viral strains in liver biopsies of patients undergoing Kasai portoenterostomy. We hypothesized that the presence of hepatotropic viruses in patients undergoing portoenterostomy contributes to the progression of the disease and negatively affect the outcome.

METHODS

Liver biopsies were prospectively taken from 70 patients undergoing portoenterostomy in our department from April 1996 to April 2004. Samples were screened by polymerase chain reaction for all common hepatic viruses. Primary outcome parameter was survival with the native liver. Secondary parameters were postoperative serum activity of liver enzymes and serum bilirubin levels at different time points. Patients underwent regular follow-up until October 2008.

RESULTS

Twenty-eight patients (40%) were positive for 1 or more hepatotropic viruses. Four patients were lost to follow-up. In the remaining 66 patients, there was no significant difference in survival with their native liver between virus-positive and virus-negative patients. After a mean follow-up of 7.7 years (range, 4.6-16.1 years), 15 (23%) of 66 patients still lived with their native liver. There was no difference in liver enzymes, C-reactive protein, or bilirubin at any time point between both groups.

CONCLUSION

A significant number of our patients tested positive for hepatotropic viruses in liver biopsies at the time of the Kasai procedure, but the presence of virus had no influence on the course of BA. This suggests that the ongoing inflammatory process of BA leading to liver cirrhosis in most Kasai-treated patients is not affected by hepatotropic viruses. Our data question the necessity to aggressively screen for and treat viral infections in patients with BA.

Biliary atresia: a multidisciplinary approach to diagnosis and management

CONTEXT

Biliary atresia is an inflammatory cholangiopathy of infancy that results in progressive fibrosis and obliteration of bile ducts and represents the main indication for liver transplant in young children. In spite of extensive investigation, its etiology has remained poorly understood. Timely surgical intervention (Kasai procedure) may result in significant benefit to these patients and represents the final goal of an accurate diagnostic evaluation.

OBJECTIVE

To present an overview of biliary atresia, including clinical and surgical approaches to this disease, with emphasis on the histopathologic evaluation.

DATA SOURCES

Review of relevant literature indexed in PubMed (US National Library of Medicine).

CONCLUSION

A well-coordinated multidisciplinary approach is required in the assessment of suspected cases of biliary atresia. Pathologic examination of biopsy specimens is an integral part of the diagnostic algorithm and, therefore, plays a pivotal role in the diagnostic evaluation of this disease.

Cytomegalovirus-specific T-cell reactivity in biliary atresia at the time of diagnosis is associated with deficits in regulatory T cells

Biliary atresia (BA) is a progressive, inflammatory cholangiopathy that culminates in fibrosis of extrahepatic and intrahepatic bile ducts. A leading theory on the pathogenesis of BA is that the bile duct damage is initiated by a virus infection, followed by a bile duct-targeted autoimmune response. One mechanism of autoimmunity entails a diminished number or function of regulatory T cells (Tregs). The aim of this study was to identify potential virus-specific liver T cells from infants with BA at the time of diagnosis, implicating the virus involved in early bile duct damage. A subaim was to determine if the presence of virus infection was associated with quantitative changes in Tregs. Liver T cells from BA and control patients were cultured with antigen-presenting cells in the presence of a variety of viral or control proteins. 56% of BA patients had significant increases in interferon-gamma-producing liver T cells in response to cytomegalovirus (CMV), compared with minimal BA responses to other viruses or the control group CMV response. In addition, a positive correlation between BA plasma CMV immunoglobulin M (IgM) and liver T-cell CMV reactivity was identified. Investigation of peripheral blood Tregs revealed significant deficits in Treg frequencies in BA compared with controls, with marked deficits in those BA patients who were positive for CMV.

CONCLUSION

Liver T-cell responses to CMV were identified in the majority of BA patients at diagnosis, suggesting perinatal CMV infection as a plausible initiator of bile duct damage. Deficiency of Tregs in BA implies decreased inhibition of inflammation and autoreactivity, potentially allowing for exaggerated bile duct injury.

Biliary atresia

Biliary atresia (BA) is a cholangiodestructive disease affecting biliary tract, which ultimately leads to cirrhosis, liver failure and death if not treated. The incidence is higher in Asian countries than in Europe. Up to 10% of cases have other congenital anomalies, such as polysplenia, asplenia, situs inversus, absence of inferior vena cava and pre-duodenal portal vein, for which we have coined the term Biliary Atresia Splenic Malformation (BASM) syndrome. For these infants the aetiology lies within the first trimester of gestation. For others affected with BA, aetiology is more obscure and perinatal destruction of fully-formed ducts perhaps by the action of hepatotropic viruses has been suggested. Whatever the cause, the lumen of the extrahepatic duct is obliterated at a variable level and this forms the basis for the commonest classification (Types I, II, III). All patients with BA present with varying degree of conjugated jaundice, pale non-pigmented stools and dark urine. Key diagnostic tests include ultrasonography, biochemical liver function tests, viral serology, and (in our centre) a percutaneous liver biopsy. In some centres, duodenal intubation and measurement of intralumenal bile is the norm. Currently BA is being managed in two stages. The first stage involves the Kasai operation, which essentially excises all extrahepatic biliary remnants leaving a transected portal plate, followed by biliary reconstruction using a Roux loop onto that plate as a portoenterostomy. If bile flow is not restored by Kasai procedure or life-threatening complications of cirrhosis ensue then consideration should be given to liver transplantation as a second stage. The outcome following the Kasai operation can be assessed in two ways: clearance of jaundice to normal values and the proportion who survive with their native liver. Clearance of jaundice (<2 mg/dL or <34 µmol/L) after Kasai has been reported to be around 60%, whereas five years survival with native liver ranges from 40% to 65%.

Biliary innate immunity: function and modulation

Biliary innate immunity is involved in the pathogenesis of cholangiopathies in patients with primary biliary cirrhosis (PBC) and biliary atresia. Biliary epithelial cells possess an innate immune system consisting of the Toll-like receptor (TLR) family and recognize pathogen-associated molecular patterns (PAMPs). Tolerance to bacterial PAMPs such as lipopolysaccharides is also important to maintain homeostasis in the biliary tree, but tolerance to double-stranded RNA (dsRNA) is not found. In PBC, CD4-positive Th17 cells characterized by the secretion of IL-17 are implicated in the chronic inflammation of bile ducts and the presence of Th17 cells around bile ducts is causally associated with the biliary innate immune responses to PAMPs. Moreover, a negative regulator of intracellular TLR signaling, peroxisome proliferator-activated receptor-γ (PPARγ), is involved in the pathogenesis of cholangitis. Immunosuppression using PPARγ ligands may help to attenuate the bile duct damage in PBC patients. In biliary atresia characterized by a progressive, inflammatory, and sclerosing cholangiopathy, dsRNA viruses are speculated to be an etiological agent and to directly induce enhanced biliary apoptosis via the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Moreover, the epithelial-mesenchymal transition (EMT) of biliary epithelial cells is also evoked by the biliary innate immune response to dsRNA.

Biliary atresia

Biliary atresia (BA) is a condition unique to infancy. It results from inflammatory destruction of the intrahepatic and extrahepatic bile ducts. It is the most frequent surgically correctable liver disorder in infancy and the most frequent indication for liver transplantation in paediatric age. Clinical presentation is in the first few weeks of life with conjugated hyperbilirubinaemia (dark urine and pale stools); other manifestations of liver disease, such as failure to thrive, splenomegaly and ascites, appear only later, when surgery is unlikely to be successful. Hence, all infants with conjugated hyperbilirubinaemia must be urgently referred to specialised centres for appropriate treatment. Success of surgery depends on the age at which it is performed. With corrective surgery, followed, when necessary, by liver transplantation, the overall survival rate is approximately 90%. The cause of BA is unknown, but there is evidence for the involvement of infectious, genetic and immunologic mechanisms, which will be discussed in this review.

Epithelial-mesenchymal transition induced by biliary innate immunity contributes to the sclerosing cholangiopathy of biliary atresia

Infections of Reoviridae consisting of a double-stranded RNA (dsRNA) genome and the biliary innate immune response to dsRNA are implicated in the aetiopathogenesis of biliary atresia (BA). Epithelial-mesenchymal transition (EMT) has recently been proposed as a mechanism behind the sclerosing cholangitis in BA. We hypothesized that the innate immune response to dsRNA in biliary epithelial cells plays an important role in peribiliary fibrosis via biliary EMT. Experiments using cultured human biliary epithelial cells revealed that stimulation with poly(I : C) (a synthetic analogue of viral dsRNA) increased the expression of basic fibroblast growth factor (bFGF, an EMT-inducer), S100A4 (a mesenchymal marker) and Snail (a transcriptional factor), and decreased that of epithelial markers (biliary-type cytokeratin 19 and E-cadherin) and Bambi (TGF-beta1 pseudoreceptor). The expression of TGF-beta1 (EMT-inducer) and vimentin (a mesenchymal marker) was not affected by poly(I : C). Both EMT-inducers, bFGF and TGF-beta1, evoked a decrease and increase in the expression of the epithelial markers and of vimentin respectively, and the expression of Bambi was down-regulated on stimulation with bFGF. Combined treatment with bFGF and TGF-beta1 quickly and completely induced a transformation of morphology as well as change from epithelial to mesenchymal features in cultured biliary epithelial cells. Immunohistochemistry revealed that biliary epithelial cells lining extrahepatic bile ducts and peribiliary glands in BA frequently show a lack of epithelial markers and an aberrant expression of vimentin. Moreover, the biliary epithelium showing sclerosing cholangitis expressed bFGF accompanied by bFGF-positive mononuclear cells. In conclusion, the EMT may contribute to the histogenesis of sclerosing cholangiopathy, and the biliary innate immune response to dsRNA viruses induces biliary epithelial cells to undergo EMT via the production of bFGF and the increased susceptibility to TGF-beta1 caused by the down-regulation of Bambi expression.

Incidence of hepatotropic viruses in biliary atresia

Biliary atresia (BA) is the most frequent indication for paediatric liver transplantation. We tested the hypothesis of a viral aetiology of this disease by screening liver samples of a large number of BA patients for the common human hepatotropic viruses. Moreover, we correlated our findings to the expression of Mx protein, which has been shown to be significantly up-regulated during viral infections. Seventy-four liver biopsies (taken during Kasai portoenterostomy) were tested by polymerase chain reaction (PCR) for DNA viruses (herpes simplex virus [HSV], Epstein-Barr virus [EBV], varicella zoster virus [VZV], cytomegalovirus [CMV], adenovirus, parvovirus B19 and polyoma BK) and RNA viruses (enteroviruses, rotavirus and reovirus 3). Mx protein expression was assessed by immunohistochemistry. Virus DNA/RNA was found in less than half of the biopsies (8/74 CMV, 1/74 adenovirus; 21/64 reovirus, 1/64 enterovirus). A limited number presented with double infection. Patients that had detectable viral RNA/DNA in their liver biopsies were significantly older than virus-free patients (P = 0.037). The majority (54/59) of the liver biopsies showed expression of Mx proteins in hepatocytes, bile ducts and epithelium. Our data suggest that the known hepatotropic viruses do not play a major role in the aetiology and progression of BA. Their incidence appears to be, rather, a secondary phenomenon. Nonetheless, the inflammatory response in the livers of BA patients mimics that observed during viral infections.

Biliary atresia: recent progress

Extrahepatic biliary atresia (EHBA), an inflammatory sclerosing cholangiopathy, is the leading indication for liver transplantation in children. The cause is still unknown, although possible infectious, genetic, and immunologic etiologies have received much recent focus. These theories are often dependent on each other for secondary or coexisting mechanisms. Concern for EHBA is raised by a cholestatic infant, but the differential diagnosis is large and the path to diagnosis remains varied. Current treatment is surgical with an overall survival rate of approximately 90%. The goals of this article are to review the important clinical aspects of EHBA and to highlight some of the more recent scientific and clinical developments contributing to our understanding of this condition.

Incidence of hepatotropic viruses in biliary atresia

Biliary atresia (BA) is the most frequent indication for paediatric liver transplantation. We tested the hypothesis of a viral aetiology of this disease by screening liver samples of a large number of BA patients for the common human hepatotropic viruses. Moreover, we correlated our findings to the expression of Mx protein, which has been shown to be significantly up-regulated during viral infections. Seventy-four liver biopsies (taken during Kasai portoenterostomy) were tested by polymerase chain reaction (PCR) for DNA viruses (herpes simplex virus [HSV], Epstein-Barr virus [EBV], varicella zoster virus [VZV], cytomegalovirus [CMV], adenovirus, parvovirus B19 and polyoma BK) and RNA viruses (enteroviruses, rotavirus and reovirus 3). Mx protein expression was assessed by immunohistochemistry. Virus DNA/RNA was found in less than half of the biopsies (8/74 CMV, 1/74 adenovirus; 21/64 reovirus, 1/64 enterovirus). A limited number presented with double infection. Patients that had detectable viral RNA/DNA in their liver biopsies were significantly older than virus-free patients (P = 0.037). The majority (54/59) of the liver biopsies showed expression of Mx proteins in hepatocytes, bile ducts and epithelium. Our data suggest that the known hepatotropic viruses do not play a major role in the aetiology and progression of BA. Their incidence appears to be, rather, a secondary phenomenon. Nonetheless, the inflammatory response in the livers of BA patients mimics that observed during viral infections.

Induction of innate immune response and absence of subsequent tolerance to dsRNA in biliary epithelial cells relate to the pathogenesis of biliary atresia

BACKGROUND/AIMS

Biliary epithelial cells (BECs) possess negative regulatory mechanisms of Toll-like receptor (TLR)-based tolerance to bacteria (e.g. endotoxin tolerance). Viral infections of the Reoviridae genus with a dsRNA genome are suspected to be part of the aetiology of biliary atresia (BA), but the negative biliary mechanisms remain unexplored.

METHODS

Cultured human intrahepatic BECs (HIBECs) pretreated with polyinosinic-polycytidylic acid [poly(I:C)] (a synthetic analogue of viral dsRNA) for 24 h were exposed to poly(I:C) in fresh medium. The activation of nuclear factor-kappaB (NF-kappaB) and the expression of myxovirus resistance protein A (MxA) and tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) mRNAs were evaluated. Moreover, after the pretreatment, the transition of these molecules was examined in poly(I:C)-free conditions.

RESULTS

Treatment with poly(I:C) significantly upregulated NF-kappaB activity in fresh HIBECs, and pretreatment failed to show tolerance to poly(I:C). The production of MxA and TRAIL was also preserved. Moreover, upregulation in the pretreated HIBECs was well preserved in poly(I:C)-free medium for at least 72 h.

CONCLUSIONS

BECs fail to show tolerance to poly(I:C), and once innate immunity is activated it is sustained in poly(I:C)-free conditions, suggesting that the initiation of the immune response to dsRNA in HIBECs and its presence after the clearance of virus are closely associated with the progression of BA.

Insignificant seasonal and geographical variation in incidence of biliary atresia in Japan: a regional survey of over 20 years

PURPOSE

Biliary atresia (BA) is the leading cause of obstructive jaundice in the newborn and the major indication for liver transplantation in Japan. Viral infection has been implicated in its etiology because of seasonality and space clustering. However, this has been controversial among whites. The present study investigates space-time clustering of the incidence of BA in Japan.

METHODS

Birth prevalence rates of BA were analyzed in infants born in Hyogo prefecture between 1985 and 2004 to assess time clustering among 3 seasons. The birth prevalence rates were also analyzed for space clustering between the northern (Hokkaido) and the southern islands (Kyushu) (difference of latitude, 10 degrees ) based on the Japanese Biliary Atresia Society Survey 1996-2004. We compared the prevalence rates between these groups using relative risks (RRs) calculated from 2 x 2 contingency tables.

RESULTS

One hundred nineteen infants were born with BA in Hyogo (1.1/10000 live births). Seasonal clustering in April to July did not significantly differ from that of the reference period (RR, 1.45; 95% confidence interval, 0.93-2.27). Based on Japanese registry data, space clustering between the northern and southern islands did not significantly differ (RR, 1.24; 95% confidence interval, 0.83-1.86).

CONCLUSIONS

Neither seasonal nor spatial clustering was statistically proven in Japan.

Innate immune response to double-stranded RNA in biliary epithelial cells is associated with the pathogenesis of biliary atresia

Infections of Reoviridae consisting of a double-stranded RNA (dsRNA) genome are a possible cause of biliary atresia (BA). The aim of the present study is to clarify the pathophysiological function of dsRNA viruses in the pathogenesis of BA. The expression of dsRNA pattern-recognizing receptors, Toll-like receptor 3 (TLR3), retinoic acid inducible gene I (RIG-I), melanoma differentiation-associated gene-5 (MDA-5), and dsRNA-activated protein kinase R (PKR) was constitutively detected in cultured human biliary epithelial cells (BECs). Stimulation with polyinosinic-polycytidylic acid [poly(I:C), a synthetic analog of viral dsRNA] induced the activation of transcription factors [nuclear factor (NF)-kappaB and interferon regulatory factor 3 (IRF3)] and the production of interferon-beta1 (IFN-beta1) and MxA as potent antiviral responses. Moreover, poly(I:C) up-regulated the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), and both poly(I:C) and TRAIL reduced the viability of cultured human BECs by enhancing apoptosis. Experiments in vivo using tissue sections of extrahepatic bile ducts from patients with BA and controls (choledochal cysts and nonbiliary diseases) showed that the activation of NF-kappaB, interferon regulatory factor-3 (IRF-3), and PKR, and the enhancement of TRAIL and single-stranded DNA (ssDNA)-positive apoptosis were significant in BA, although extrahepatic bile ducts diffusely and constantly expressed TLR3 in all diseases.

CONCLUSION

dsRNA viruses could directly induce the expression of TRAIL and apoptosis in human biliary epithelial cells as a result of the biliary innate immune response, supporting the notion that Reoviridae infections are directly associated with the pathogenesis of cholangiopathies in cases of BA.

Risk factors for isolated biliary atresia, National Birth Defects Prevention Study, 1997–2002

Biliary atresia is a rare birth defect that affects 1 in 12,000 to 1 in 19,500 live births. We used data from the National Birth Defects Prevention Study, a multistate case-control study, to identify potential risk factors for isolated biliary atresia (no additional unrelated major birth defects diagnosed). Infants were identified from eight states from 1997 to 2002, with clinical information abstracted from medical records. Potential risk factors assessed include: demographic factors, seasonality, preterm birth, maternal smoking, maternal alcohol use, maternal illicit drug use, maternal health, maternal medication use, maternal vitamin use, and maternal nutrition. Infants of non-Hispanic black mothers were more likely to have biliary atresia than infants of non-Hispanic white mothers (adjusted odds ratio (aOR) = 2.29, 95% confidence interval (CI) 1.07-4.93) and infants conceived during the spring season were more likely to have biliary atresia than infants conceived in winter (aOR = 2.33, 95%CI 1.05-5.16). Low intakes of vitamin E, copper, phosphorus, and beta tocopherol were associated with the occurrence of isolated biliary atresia (borderline significance). Low iron intake had a borderline inverse association with biliary atresia. While this analysis provides support for previous reports of a possible association between seasonal variation and the occurrence of biliary atresia, more data are needed to evaluate whether the seasonal variation is related to infectious agents. The role of nutrients in the development of biliary atresia remains unclear. Further studies of genetic, infectious, and nutrient exposures and the association of biliary atresia are warranted.

Biliary atresia

Biliary atresia (BA) is a rare disease characterised by a biliary obstruction of unknown origin that presents in the neonatal period. It is the most frequent surgical cause of cholestatic jaundice in this age group. BA occurs in approximately 1/18,000 live births in Western Europe. In the world, the reported incidence varies from 5/100,000 to 32/100,000 live births, and is highest in Asia and the Pacific region. Females are affected slightly more often than males. The common histopathological picture is one of inflammatory damage to the intra- and extrahepatic bile ducts with sclerosis and narrowing or even obliteration of the biliary tree. Untreated, this condition leads to cirrhosis and death within the first years of life. BA is not known to be a hereditary condition. No primary medical treatment is relevant for the management of BA. Once BA suspected, surgical intervention (Kasai portoenterostomy) should be performed as soon as possible as operations performed early in life is more likely to be successful. Liver transplantation may be needed later if the Kasai operation fails to restore the biliary flow or if cirrhotic complications occur. At present, approximately 90% of BA patients survive and the majority have normal quality of life.

Expression of the interferon-induced Mx proteins in biliary atresia

Biliary atresia (BA) is a rare disease of the newborn for which the Kasai procedure is curative only for a few of the patients. The dilemma is that all therapeutic attempts to cure the disease are symptomatic because the etiology is still unclear. One theory suggests a progressive inflammatory process, possibly induced by a viral infection. The aim of the present study was to investigate the activity of type I interferons (IFNs) in the livers of patients with BA. Mx proteins, which mediate an early innate immune response, are a very sensitive marker for type I IFN activity (eg, to viral infection). Liver biopsies were taken during the Kasai procedure from 13 newborns with BA who were serologically negative for hepatotropic viruses. Age-matched controls originated from 7 patients with neonatal cholestasis (eg, inspissated bile syndrome), 3 aborted fetuses, and a 10-year-old child. The immunostaining procedure (alkaline phosphatase anti-alkaline phosphatase) was performed with Mx-specific monoclonal antibody. Immunostaining for Mx proteins was positive in the hepatocytes of all newborns with BA, whereas the intrahepatic bile ducts were positive in all but one. In the control group, 8 of 11 liver samples were Mx-negative. This is the first study dealing with the detection of type I IFN activity in the liver of patients with BA. This observation supports the etiologic consideration of type I IFN-mediated immune response. Although positive findings of viruses in patients with BA are still inconsistent, the present study retraces the progressive inflammatory process in BA one more step toward its beginning.

Potential etiologies of biliary atresia

Biliary atresia is the most common cause of neonatal cholestasis and the leading indication for pediatric liver transplantation worldwide. The disease is caused by a progressive inflammatory and fibrosing obliteration of the extrahepatic bile ducts. Although the cause of this obstruction is largely unknown, patient-based studies have identified environmental and genetic factors that may interact and orchestrate disease pathogenesis. Chief among these factors are infectious and immunologic processes. While infectious agents have varied in different patient populations, studies of liver specimens at different phases of disease point to a pro-inflammatory commitment of lymphocytes at the time of diagnosis, and to their potential role in regulating bile duct obstruction. A review of these studies is the focus of this article.

Not all viruses are bad guys: the case for reovirus in cancer therapy

Efforts to improve on cancer therapy have begun to capitalize on recent advances in our understanding of tumorigenesis. Tumor-specific characteristics are being exploited to develop selective antibodies and pharmacological inhibitors that specifically target cancer cells, and these agents are already showing clinical promise. None of these approaches, however, has captured our imagination as much as the use of replication-competent viruses to kill cancer cells. Whereas normal cells resist replication, tumor cells have an impaired antiviral response that sensitizes them to oncolytic viruses. One such virus is reovirus, a benign, naturally occurring virus that can effect tumor regression in animal models. Reovirus is demonstrating much promise in pre-clinical studies of cancer therapy and in clinical trials, where a lack of toxicity and signs of efficacy are generating excitement for this novel potential cancer therapeutic.

Unraveling the pathogenesis and etiology of biliary atresia

Biliary atresia (BA) is the most common and important neonatal hepatobiliary disorder. Because current treatment is inadequate, there is an urgent need to better understand the etiology and pathogenesis of BA. Two major forms of BA are recognized: an embryonic form associated with other congenital anomalies and a perinatal form in which bile ducts were presumably formed normally but underwent fibro-obliteration in the perinatal period. There are currently several proposed pathogenic pathways leading to the phenotype of BA, including an immune or autoimmune response to a perinatal insult (e.g. cholangiotropic viral infection) and dysregulated embryonic development of the extra- or intrahepatic biliary system. Recent advances in developmental biology, genomics and genetics, and cell immunology and biology, coupled with the development of appropriate animal models, have provided support for these postulated mechanisms. Future investigations combining animal model work and evaluation of clinical specimens holds the promise of identifying the etiology of BA and providing a scientific basis for treatment and preventative interventions.

Biliary atresia is associated with CD4+ Th1 cell-mediated portal tract inflammation

A proposed mechanism in the pathogenesis of biliary atresia involves an initial virus-induced, progressive T cell-mediated inflammatory obliteration of bile ducts. The aim of this study was to characterize the inflammatory environment present within the liver of infants with biliary atresia to gain insight into the role of a primary immune-mediated process versus a nonspecific secondary response to biliary obstruction. Frozen liver tissue obtained from patients with biliary atresia, neonatal giant cell hepatitis, total parenteral nutrition (TPN)-related cholestasis, choledochal cysts, and normal control subjects was used for fluorescent immunohistochemistry studies of cellular infiltrates, cytokine mRNA expression, and in situ hybridization for localization of cytokine-producing cells. Immunohistochemistry revealed increases in CD8(+) and CD4(+) T cells and Kupffer cells (CD68(+)) in the portal tracts of biliary atresia. Reverse transcription-PCR analysis of biliary atresia tissue showed a Th1-type cytokine profile with expression of IL-2, interferon-gamma, tumor necrosis factor-alpha, and IL-12. This profile was not seen in normal, neonatal hepatitis or choledochal cyst livers but was present in TPN-related cholestasis. In situ hybridization revealed that the Th1 cytokine-producing cells were located in the portal tracts in biliary atresia and in the parenchyma of TPN-related cholestasis. A distinctive portal tract inflammatory environment is present in biliary atresia, involving CD4(+) Th1 cell-mediated immunity. The absence of similar inflammation in other pediatric cholestatic conditions suggests that the portal tract inflammation in biliary atresia is not a secondary response to cholestasis but rather indicates a specific immune response involved in the pathogenesis of biliary atresia.

The epidemiology of extrahepatic biliary atresia in New York State, 1983-98

The aetiology of biliary atresia, the leading cause of neonatal extrahepatic jaundice and the main indication for liver transplantation in children, is unknown. Recent research has focused on an infectious aetiology and the development of viral models in animals. The few published epidemiological studies report conflicting results for seasonal, geographical, and racial variations in incidence. In this study, New York State (NYS) Congenital Malformations Registry data from 1983 to 1998 were compared with resident live birth certificate data. County of residence, birth date, gestational age, birthweight, gender, maternal race and maternal age were extracted from the birth certificate data. Isolated and sequence cases were combined for analysis. Observed and expected numbers of cases were calculated by NYS region. Overall, 369 biliary atresia cases were reported in the 16-year study period, a rate of 0.85 [95% CI 0.76, 0.93] per 10,000 live births. Of these, 249 isolated/sequence cases were ascertained, a rate of 0.57 [95% CI 0.50, 0.64] per 10,000 live births. The rate ratio of biliary atresia in New York City (NYC) compared with other NYS was 2.19 [95% CI 1.69, 2.84]. Seasonal patterns varied by region with spring births at highest risk in NYC and September to November births at highest risk in other NYS. The rate ratio in black vs. white mothers was 1.94 [95% CI 1.48, 2.54]. Birthweight and gestational age were associated with biliary atresia with preterm low-birthweight infants at highest risk [RR 3.24, 95% CI 2.20, 4.76]. The association of isolated/sequence biliary atresia with season, preterm birth, and low birthweight in our study supports an infectious disease hypothesis.

Biliary atresia revisited

Extrahepatic biliary atresia (EHBA) is an inflammatory fibrosing process affecting the extrahepatic and intrahepatic biliary tree resulting in fibrous obliteration of the extrahepatic biliary tract, ductopenia of intrahepatic bile ducts, and biliary cirrhosis. EHBA is divided into a correctable and a noncorrectable type with focal patency of the otherwise atretic biliary tree in the former and no patency of the biliary tree in the noncorrectable type. EHBA is divided in a fetal, prenatal or embryonic, and a more common, perinatal, acquired form. The symptoms of the former start shortly after birth and there is frequently an association with a variety of congenital anomalies. Children with the perinatal form become jaundiced several weeks after birth; no associated congenital anomalies are present. Morphologically, an inflammatory and fibrosing process of the extrahepatic biliary tree leads to complete lumenal obliteration. The liver is characterized by a nonspecific giant cell transformation, and portal expansion by fibrous connective tissue with marked ductular proliferation. With time, ductopenia and biliary cirrhosis develop. The diffential diagnosis with other conditions with similar microscopic patterns such as as alpha-1 antitrypsin deficiency, total parental nutrition, obstruction by a choledochal cyst, arteriohepatic dysplasia, familial progressive intrahepatic cholestasis, and alteration of the bile acid metabolism is discussed. In the fetal group, abnormalities in different genes seem to play a role; ductal plate malformation is another possibility. Different etiologies have been postulated in the perinatal form of EHBA: genetic susceptibility, vascular factors, toxins, and infections mainly by rotavirus and reovirus. The pathogenesis is complex. EHBA is a heterogenous disease, resulting from a combination of genetic factors, insults, and activation of different genetic and immunologic pathways. The treatment of EHBA is surgical, with anastomosis between the biliary tree and the intestine in the correctable type and a hepatic portoenterostomy (HPE) for the noncorrectable group. HPE is a temporizing treatment allowing the infant to develop and grow, followed in the majority of the patients by liver transplantation.

Lack of evidence for reovirus infection in tissues from patients with biliary atresia and congenital dilatation of the bile duct

BACKGROUND/AIMS

To clarify the association between the reovirus infection of the hepatobiliary tree and the development of infantile obstructive cholangiopathy (IOC) including biliary atresia (BA) and congenital dilatation of the bile duct (CBD).

METHODS

We designed reovirus common primers for nested RT-PCR based on the L3 gene segment. The spectrum and the sensitivity of common primers were evaluated with purified reoviral RNAs and reovirus mixed with stool samples. Then, nested RT-PCRs were performed with hepatobiliary and fecal samples obtained from patients with BA, CBD, and control diseases. Additionally, electron microscopy of stool samples was performed.

RESULTS

The L3 common primers could amplify cDNAs synthesized from RNAs of three prototypes of reovirus, and detect as much as 5.0x10(3) plaque forming unit of serotype 3 Dearing strain in 100 mg of fecal samples. However, no amplification product was detected in 136 hepatobiliary tissues taken from 67 patients including 26 BAs and 28 CBDs, or in 65 fecal samples obtained from 15 patients including 10 BAs and 1 CBD. Additionally, viral particles were not found in any stool specimens by the electron microscope.

CONCLUSIONS

These data do not suggest that reoviruses play a major role in the etiology of IOC or BA.

Biliary atresia

BA is a rare disease of unclear etiology; nevertheless, its impact in the field of pediatric hepatology is significant. It is the most common surgically correctable cause of neonatal cholestasis and is the most common pediatric disease referred for liver transplantation. Little progress has been made with regard to improving outcome or understanding its pathogenesis in the past decade. Fortunately, however, a national, government-sponsored collaborative endeavor has begun that will hopefully make a significant impact upon the progress of designing new treatments for BA and develop a better understanding of its pathogenesis.

Utilization of sialic acid as a coreceptor is required for reovirus-induced biliary disease

Infection of neonatal mice with some reovirus strains produces a disease similar to infantile biliary atresia, but previous attempts to correlate reovirus infection with this disease have yielded conflicting results. We used isogenic reovirus strains T3SA- and T3SA+, which differ solely in the capacity to bind sialic acid as a coreceptor, to define the role of sialic acid in reovirus encephalitis and biliary tract infection in mice. Growth in the intestine was equivalent for both strains following peroral inoculation. However, T3SA+ spread more rapidly from the intestine to distant sites and replicated to higher titers in spleen, liver, and brain. Strikingly, mice infected with T3SA+ but not T3SA- developed steatorrhea and bilirubinemia. Liver tissue from mice infected with T3SA+ demonstrated intense inflammation focused at intrahepatic bile ducts, pathology analogous to that found in biliary atresia in humans, and high levels of T3SA+ antigen in bile duct epithelial cells. T3SA+ bound 100-fold more efficiently than T3SA- to human cholangiocarcinoma cells. These observations suggest that the carbohydrate-binding specificity of a virus can dramatically alter disease in the host and highlight the need for epidemiologic studies focusing on infection by sialic acid-binding reovirus strains as a possible contributor to the pathogenesis of neonatal biliary atresia.

HLA and cytokine gene polymorphisms in biliary atresia

BACKGROUND/AIMS

Extrahepatic biliary atresia remains one of the major hepatic causes of death in early childhood. Though a number of hypotheses have been developed to account for this disease, its aetiopathogenesis is poorly understood. One possibility is that this is an immune mediated disease which occurs following either toxic or infectious insult in a genetically susceptible host. Earlier studies suggested weak HLA associations but these remain unconfirmed. More recently studies of viral and autoimmune liver disease have begun to investigate non-MHC immunoregulatory gene polymorphisms.

METHODS

In the present study we used molecular genotyping to investigate selected HLA A, B, DRB1, DQA1, DQB1 and DPB1 alleles as well as polymorphisms in the interleukin-1 gene family, interleukin-10 promoter sequence and tumour necrosis factor alpha promoter genes in 101 children referred for surgical assessment with extra hepatic biliary atresia. Genotyping data were compared with those of 134 racially and geographically matched healthy adult health care workers.

RESULTS AND CONCLUSIONS

Overall there were no statistically significant differences in the distribution of any of the genes tested comparing patients and controls. These data suggest that biliary atresia is not an HLA-associated disease and that polymorphisms in both the interleukin-1 and interleukin-10 genes are not risk factors for this disease.

Biliary atresia: an update on our understanding of the disorder

Biliary atresia is the leading cause of cholestasis in infants younger than 3 months. It is also the leading indication for liver transplantation in children. This review focuses on recent advances in the etiology, diagnosis, and management of biliary atresia.

Epidemiology of biliary atresia in France: a national study 1986-96

BACKGROUND/AIMS

The reported incidence of biliary atresia varies from 5 to 32/100000 live births. The existence of seasonality and/or clustering is controversial. Based on a large population analysis, we examined the incidence of biliary atresia in France, and the space-time distribution of cases.

METHODS

All patients with biliary atresia living in France and born in the years 1986-96 were recorded. Geographic distribution, seasonality, time clustering and space-time clustering were analysed. Statistical analysis used the Chi square test, the Spearman nonparametric correlation test, the Walter and Elwood test for seasonality of events and Knox analysis for time and space-time clustering.

RESULTS

We identified 461 patients: 421 born in metropolitan France (incidence 5.12 [4.63-5.61]/100000 live births), and 40 born in overseas territories. No significant regional variation in incidence was found in metropolitan France, while the incidence was higher in French Polynesia (incidence 29.4 [15.4-43.3]/100000 live births) (p<0.001). Seasonality, time-clustering and time-space clustering could not be demonstrated.

CONCLUSIONS

1) The incidence of BA was 5.7-fold higher in Polynesia than in metropolitan France. 2) Neither seasonal variation in incidence nor clustering was identified.

Pediatric liver disease

Pediatric hepatology has advanced greatly over the past few years. Many more children with severe liver disease are now surviving into adulthood. There is a number of conditions not seen in adult practice that have been the focus of research efforts, and many of these efforts have borne fruit in the past year. Disorders characterized by intrahepatic cholestasis in particular have now been substantially unravelled, and this work has elucidated a great deal about hepatic physiology. Liver-directed gene therapy is on the threshold of human application. This research has been facilitated by excellent animal models and the advent of isolated hepatocyte transplantation. Relatively common conditions such as biliary atresia, however, remain largely unexplained and the viral hepatitides have no effective form of treatment. It remains a hope that our increase in knowledge in the fields of genetics and immunology will translate into advances in therapy.

Biliary atresia and cytomegalovirus infection: a DNA study

The cause of extrahepatic biliary atresia (EHBA) is undetermined in most instances, but an infectious agent is widely suspected. Cytomegalovirus (CMV) infection has been associated with intrahepatic bile duct destruction and paucity, raising the question of its role in EHBA. We identified 12 children in the past 5 years with biliary atresia and examined the bile duct biopsy. These showed acute/chronic inflammation and epithelial degeneration. CMV inclusions were not identified. We used in situ hybridization and the polymerase chain reaction (PCR) for CMV-DNA on formalin-fixed, paraffin-embedded tissue. All samples showed the presence of amplifiable DNA using beta-globin primers. No biopsy tissue showed CMV DNA using specific probes and primers. The absence of demonstrable CMV DNA by in situ hybridization and PCR in EHBA biopsies implies that it is unlikely that this virus has any major role in the pathogenesis of this condition.

Presence of human papillomavirus in extrahepatic biliary atresia

BACKGROUND

In a previous study the human papillomavirus DNA was detected in seven cases of so-called idiopathic neonatal giant cell hepatitis by using nested polymerase chain reaction. The purpose of the present study was to study the prevalence and possible common causes of human papillomavirus-associated idiopathic neonatal giant cell hepatitis and extrahepatic biliary atresia.

METHODS

Formalin-fixed, paraffin-embedded archival tissues obtained in 18 cases of extrahepatic biliary atresia were studied for human papillomavirus DNA by nested polymerase chain reaction. In addition, in situ hybridization was performed on tissue obtained in 6 cases.

RESULTS

Tissue in 16 of the 18 cases studied showed amplified human papillomavirus DNA, whereas no human papillomavirus was amplified in any of 30 control samples. Main human papillomaviruses detected were types 6 and 18. Punctate intranuclear positive signals were detected in the hepatocytes after in situ hybridization for human papillomavirus DNA.

CONCLUSIONS

The high prevalence of human papillomavirus DNA in liver tissue in cases of extrahepatic biliary atresia suggests a strong correlation between this disorder and idiopathic neonatal giant cell hepatitis. It further suggests that this virus may be one of the causative agents in extrahepatic biliary atresia and may represent part of the spectrum of lesions associated with neonatal human papillomavirus-induced hepatic damage.

The viral association of neonatal cholestasis in Sweden: a possible link between cytomegalovirus infection and extrahepatic biliary atresia

BACKGROUND

In addition to earlier reports on the association between viral infections and intrahepatic neonatal cholestasis, in recent studies, investigators have suggested a similar link to extrahepatic biliary atresia.

METHODS

Fifty-nine cholestatic infants (mean age 8 weeks) were investigated for signs of infection with a large spectrum of viruses. Twenty-one infants had extrahepatic biliary atresia, 38 had intrahepatic cholestasis. The virologic methods included serologic investigation in 59 infants and 54 mothers, virus isolation from stools (49 infants), urine (58 infants) and liver biopsies (40 infants). Polymerase chain reaction was used to detect cytomegalovirus DNA in 25 of the liver biopsy specimens. Two control groups, one with 35 noncholestatic infants and one with 111 healthy, pregnant women were checked for serologic signs of cytomegalovirus.

RESULTS

Nineteen of 59 (32%) cholestatic infants, including 8 of 21 (38%) with extrahepatic biliary atresia, compared with 2 of 35 (6%) control infants had cytomegalovirus-immunoglobulin (Ig) M detected in serum (p < 0.01). Fifty-one of 54 (94%) tested mothers of cholestatic infants were seropositive for cytomegalovirus, compared with 83 of 111 (75%) control mothers (p < 0.01). Cytomegalovirus DNA in liver specimens was detected by polymerase chain reaction in 9 of 18 (50%) analyzed patients with biliary atresia and in specimens from 3 of 7 patients with intrahepatic cholestasis.

CONCLUSIONS

Cytomegalovirus infection may play a role, not only in intrahepatic neonatal cholestasis, as was suggested earlier, but also in extrahepatic biliary atresia. The pathogenetic mechanism for this link remains to be established.