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

Aberrant DNA methylation profile in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a notoriously lethal epithelial cancer originating from the biliary system. As radical resection offers a poor success rate and limited effective adjuvant modalities exist in its advanced stage, the disease leads to a fairly poor prognosis. As the incidence of CCA is increasing, although the mortality rate remains stable, and few other definite etiologies have yet to be established, renewing our knowledge of its fundamental carcinogenesis is advisable. The latest advances in molecular carcinogenesis have highlighted the roles of epigenetic perturbations and cancer-related inflammation in CCA. This review focuses on the reciprocal effects between aberrant DNA methylation and inflammatory microenvironment in CCA.

Epithelial-mesenchymal transition induced by transforming growth factor-{beta}1/Snail activation aggravates invasive growth of cholangiocarcinoma

Epithelial-mesenchymal transition is an important mechanism behind initiation of cancer invasion and metastasis. This study was performed to clarify the involvement of epithelial-mesenchymal transition in the progression of cholangiocarcinoma. Cholangiocarcinoma cell lines, CCKS-1 and TFK-1, were treated with transforming growth factor-beta1 (TGF-beta1), and the phenotypic changes and invasive activity were examined. Immunohistochemical analysis was performed using tissue sections of cholangiocarcinoma. In vitro, TGF-beta1 induced mesenchymal features in CCKS-1 and TFK-1 characterized by the reduction of E-cadherin and cytokeratin 19 expression and the induction of mesenchymal markers, such as vimentin and S100A4. TGF-beta1 also induced the nuclear expression of Snail, and the invasive activity was significantly increased in both cell lines. Studies using a mouse xenograft model showed that TGF-beta1 worsened the peritoneal dissemination of CCKS-1. All these changes by TGF-beta1 were inhibited by the simultaneous administration of soluble TGF-beta type II receptor. In vivo, six (16%) of 37 cholangiocarcinoma cases showed marked immunoreactivity of Snail in their nuclei. In these six cases, the immuno-expression of cytokeratin 19 was significantly reduced, and the expression of vimentin was significantly increased. The Snail expression significantly correlated with the lymph node metastasis and a poor survival rate of the patients. These results suggest that epithelial-mesenchymal transition induced by TGF-beta1/Snail activation is closely associated with the aggressive growth of cholangiocarcinoma, resulting in a poor prognosis.

Advances in biliary atresia: from patient care to research

Biliary atresia, the most common cause of liver transplantation in children, remains a challenge for clinicians and investigators. The development of new therapeutic options, besides the typical hepatoportoenterostomy, depends on a greater understanding of its pathogenesis and how it relates to the clinical phenotypes at diagnosis and the rate of disease progression. In this review, we present a perspective of how recent research has advanced the understanding of the disease and has improved clinical care protocols. Molecular and morphological analyses at diagnosis point to the potential contributions of polymorphism in the CFC1 and VEGF genes to the pathogenesis of the disease, and to an association between the degree of bile duct proliferation and long-term outcome. In experimental models, cholangiocytes do not appear to have antigen-presenting properties despite a substantial innate and adaptive immune response that targets the biliary epithelium and produces duct obstruction. Initial clinical trials assessing the efficacy of corticosteroids in decreasing the inflammation and improving outcome do not show a superior effect of corticosteroids as an adjuvant treatment following hepatoportoenterostomy. The best outcome still remains linked to an early diagnosis and surgical treatment. In this regard, the Yellow Alert campaign by the Sociedade Brasileira de Pediatria and the inclusion of the Stool Color Card in the health booklet given to every neonate in Brazil have the potential to decrease the age of diagnosis, shorten the time between diagnosis and surgical treatment, and improve the long-term outcome of children with this devastating disease.

Nonalcoholic fatty liver disease: pathology and pathogenesis

Nonalcoholic fatty liver disease (NAFLD) is recognized as the leading cause of chronic liver disease in adults and children. NAFLD encompasses a spectrum of liver injuries ranging from steatosis to steatohepatitis with or without fibrosis. Fibrosis may progress to cirrhosis and complications including hepatocellular carcinoma. Histologic findings represent the complexity of pathophysiology. NAFLD is closely associated with obesity and is most closely linked with insulin resistance; the current Western diet, high in saturated fats and fructose, plays a significant role. There are several mechanisms by which excess triglycerides are acquired and accumulate in hepatocytes. Formation of steatotic droplets may be disordered in NAFLD. Visceral adipose tissue dysfunction in obesity and insulin resistance results in aberrant cytokine expression; many cytokines have a role in liver injury in NAFLD. Cellular stress and immune reactions, as well as the endocannabinoid system, have been implicated in animal models and in some human studies.

Cholestatic liver disease in children

Inherited syndromes of intrahepatic cholestasis and biliary atresia are the most common causes of chronic liver disease and the prime indication for liver transplantation in children. Our understanding of the pathogenesis of these diseases has increased substantially by the discovery of genetic mutations in children with intrahepatic cholestasis and the findings that inflammatory circuits are operative at the time of diagnosis of biliary atresia. Building on this solid foundation, recent studies provide new insight into genotype-phenotype relationships and how mutations produce altered bile composition and cholestasis. New evidence exists that although liver transplantation is curative for patients with end-stage liver disease owing to cholestasis, some patients may develop recurrence of cholestasis because of the emergence of autoantibodies that disrupt canalicular function in the new graft. Progress is also evident in biliary atresia, with recent studies identifying candidate modifier genes and directly implicating lymphocytes and inflammatory signals in the pathogenesis of bile duct injury and obstruction.

Differential expression of hepatic fibrosis mediators in sick and spontaneously recovered mice with experimental biliary atresia

BACKGROUND

Hepatic fibrosis leading to cirrhosis is the major morbidity in patients with biliary atresia (BA). This fibrosis is due to an imbalance in extracellular matrix (ECM) breakdown and deposition. We have previously demonstrated increased mRNA expression for inhibitors of ECM breakdown without increased expression for mediators of ECM deposition in our animal model of BA by d 14. However, only a mild degree of hepatic fibrosis was seen at this time. We hypothesized that expression patterns for these proteins may change once more significant fibrosis had been established, and added resuscitation to the model to improve survival. Interestingly, we found that some mice spontaneously recovered at later time points with resuscitation, and thus compared expression for inhibitors of ECM breakdown and deposition in sick and recovered mice to determine the differences.

METHODS

Newborn Balb/c mice received an intraperitoneal injection 1.0 x 10(6) fluorescence forming units of rhesus rotavirus 24h after birth. Mice were monitored daily for weight gain, development of jaundice, acholic stools, and bilirubinuria. Fifty muL/g of 5% dextrose in normal saline were subcutaneously injected daily to each mouse starting on d 7 until sacrifice. Mice that survived past d 14 were sacrificed at d 21 after saline or RRV infection. Livers were then harvested post-injection d 21 for histologic and immunohistochemical analysis. RNA expression of known mediators of fibrosis was evaluated using quantitative real-time PCR. Protein expression was assessed using ELISA. Weights and normally distributed data were compared using Student's t test. Histologic findings were compared using Fisher's exact test. Comparisons of gene expression and skewed data were performed by the Mann-Whitney U test. Statistical significance was assigned to any P value less than 0.05.

RESULTS

Daily resuscitation resulted in a 35% (24/68) survival rate to d 21 in our model. Mice that recovered were significantly heavier than those that remained ill on d 14 (6.15 +/- 1.16 versus 4.94 +/- 0.82, P = 0.02) and 21 (7.31 +/- 1.41 versus 4.14 +/- 0.53, P < 0.001) despite the fact that there was no difference between the groups with respect to weight on d 7 (4.29 +/- 0.90 versus 3.89 +/- 0.81, P = 0.32). We found that all (10/10) animals that displayed clinical signs of biliary atresia on d 21 had moderate or severe histologic findings, while only one (1/9) of the recovered animals had liver abnormalities at sacrifice (P < 0.001 versus sick group). We also found that the sick mice had statistically significant median fold-increases of mRNA expression for TIMP-1 (31.9 versus 9.1, P = 0.041), TIMP-4 (88.1 versus 1.8, P = 0.022), and MMP-7 (51.8 versus 11.9, P = 0.006) compared with those that recovered. There was a trend toward decreased mRNA expression for PAI-1, which did not reach statistical significance (median 27.7 versus 2.19, P = 0.066). Increased protein expression for TIMP-1 and PAI-1 were also found in the sick group. The mRNA expression for the fibrillar collagens, fibronectin-1, connective tissue growth factor, snail-1, TIMP-2 and -3, and MMP-2 and MMP-9 was not different in the sick and recovered groups 21 d after RRV infection, and was not elevated from baseline gene expression.

CONCLUSIONS

With resuscitation added to the animal model of BA, some mice spontaneously recover while others progress to more significant hepatic fibrosis. Mice with hepatic fibrosis have a continued increase in mRNA expression of TIMP-1, TIMP-4, and MMP-7, with a trend toward increased mRNA expression of PAI-1 on d 21. Protein levels for TIMP-1 and PAI-1 were also increased in the sick mice. Recovered mice display mild to no hepatic parenchymal disease and a normal pattern of mRNA expression for the mediators of fibrosis tested. No increase in mRNA expression for the mediators of ECM deposition was found in either group. These data further support the notion that inhibition of ECM breakdown alone is sufficient to induce hepatic fibrosis. Modulation of this process may be a putative target for preventing liver injury in patients with BA.