MAPK signaling contributes to rotaviral-induced cholangiocyte injury and viral replication

BACKGROUND

Biliary atresia is a disease of newborns that results in obliteration of the biliary tree. Infection of mice with rhesus rotavirus (RRV) results in a cholangiopathy mirroring human disease. The Mitogen Associated Protein Kinase (MAPK) signaling pathway can be activated by viral binding to cell-surface receptors. We hypothesized that RRV infection of cholangiocytes results in activation of MAPK signaling.

METHODS

Extrahepatic bile ducts from BALB/c pups or immortalized cholangiocytes subjected to RRV infection or control were analyzed, using Western blots, for phosphorylated members of the MAPK family: p38, ERK 1/2, JNK 1/2, and downstream transcription factors. Inhibitors of the MAPK were used to downregulate activity. Viral replication and cytolysis in cholangiocytes were evaluated post-MAPK inhibition.

RESULTS

Phosphorylation of all MAPK increased in RRV-infected mice and cholangiocytes. Several downstream transcription factors had increased activity in vitro. Inhibition of p38 and ERK 1/2 resulted in decreased viral replication. ERK 1/2 inhibition decreased cytolysis without affecting viral entry or binding.

CONCLUSIONS

RRV infection of cholangiocytes resulted in increased MAPK signaling. Inhibition of p38 and ERK 1/2 influenced the ability of rotavirus to replicate. These novel findings provide insight into the signaling cascade involved in RRV-induced cholangiocyte injury.

Papillomatosis of intra- and extrahepatic biliary tree: Successful treatment with liver transplantation

Approximately 60 cases of biliary papillomatosis have been reported in the world literature, while only 6 cases have been reported to be treated with liver transplantation. This rare disease, which is characterized by relapsing episodes of obstructive jaundice and cholangitis that lead to secondary cirrhosis and death from sepsis or liver failure, it is also considered premalignant because of its frequent malignant transformation (25-50%). We present a case of a 43-year-old white man with papillomatosis of intra- and extrahepatic biliary tree who sought care for repeated episodes of obstructive jaundice and cholangitis. The diagnosis was suspected after endoscopic retrograde cholangiopancreatography and confirmed by liver and common bile duct biopsies. The patient underwent orthotopic liver transplantation with Roux-en-Y hepatico-jejunostomy to treat end-stage liver cirrhosis. Fifteen months' follow-up revealed a patient with normal graft function and with no clinically or laboratory findings of disease recurrence or cancer development.

Cytomegalovirus infection and proinflammatory cytokine activation modulate the surface immune determinant expression and immunogenicity of cultured murine extrahepatic bile duct epithelial cells

Murine extrahepatic bile duct epithelial cells (MEBEC) were isolated from extrahepatic bile ducts of BALB/c mice and established in primary culture. The epithelial origin was confirmed by positive cytokeratin 19 staining for these cells and the presence of microvilli and tight junctions under electron microscopy. By immunofluorescent staining with monoclonal antibodies and flow-cytometric analysis, MEBEC in culture constitutively express low levels of intercellular adhesion molecule (ICAM)-1, class I and class II major histocompatibility (MHC) antigens. The expression of ICAM-1 was significantly increased by interferon gamma (INF-gamma) or tumour necrosis factor alpha (TNF-alpha) stimulation. Class I and class II antigen expression were significantly enhanced by INF-gamma and in vitro murine cytomegalovirus (MCMV) infection. MEBEC infected with MCMV revealed a progressive cytopathic effect. MEBEC activated by INF-gamma or infected by MCMV induced a low but significant proliferation of allogeneic T cells and displayed a significant decrease in the absorbance at O.D. 550 nm in a microtitre tetrazolium assay after these treated cells were co-cultured with allogeneic T cells. These results suggest that following the up-regulation of surface MHC antigen and adhesion molecule expression with cytokines or MCMV, the MEBEC can function as antigen-presenting cells and initiate T-cell proliferation, which in turn trigger the recognition of MEBEC by effector T-cell-mediated cytotoxic responses. These findings may be implicated in the pathogenesis of virally induced, immune-mediated extrahepatic bile duct damage disorders.

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.

Detection of group C rotavirus in infants with extrahepatic biliary atresia

The purpose of this retrospective study was to examine liver tissue from patients with cholestatic disease for the presence of group C rotavirus RNA. The reverse transcriptase-polymerase chain reaction (PCR) for genes 5 and 6 was used, and the PCR products were subjected to liquid hybridization with a 32P-labeled probe. A second amplification with nested primers was also used. Samples from 32 subjects (20 with biliary atresia or choledochal cyst and 12 controls) were tested. Ten of 20 biliary atresia patients were positive for group C rotavirus RNA; no controls were positive (P < .003). Three of the positive patients were positive for both genes 5 and 6. Six of the 10 had > 1 sample that was positive. These data suggest a possible relationship between group C rotavirus and extrahepatic biliary atresia in the 10 patients in whom virus RNA was detected.

Reovirus 3 not detected by reverse transcriptase-mediated polymerase chain reaction analysis of preserved tissue from infants with cholestatic liver disease

Reovirus type 3 has been implicated in the origin and pathogenesis of extrahepatic biliary atresia and idiopathic neonatal hepatitis, but routine detection of this virus in hepatobiliary tissues from affected infants by culture and histological techniques has been unsuccessful. In this study, oligonucleotide primers specific to the M3 genome segment of reovirus 3 (Dearing) were used in a reverse transcriptase-mediated polymerase chain reaction technique to develop a sensitive and specific assay for the detection of reovirus 3 RNA in formalin-fixed, paraffin-embedded patient samples. Optimal reaction conditions were determined by testing infected murine tissues and preserved human liver tissue supplemented with reovirus 3. Archival specimens from 50 infants, including 14 with extrahepatic biliary atresia, 20 with idiopathic neonatal hepatitis, and 16 age-matched controls, were evaluated. Successful amplification of human albumin complementary DNA from the preserved tissues confirmed the presence of intact RNA in every patient specimen tested. Analysis of the amplification reactions by agarose gel electrophoresis and Southern blot hybridization detected the presence of reoviral RNA only once in a single patient sample. These results do not support a strong role for reovirus 3 in the development of neonatal cholestatic liver disease. The recent association of other RNA viruses of the Reoviridae family with murine liver disease and human extrahepatic biliary atresia indicates that continued investigation into a viral cause for idiopathic neonatal hepatobiliary disease is warranted.