Daiji Iwami

Apoptosis and cell proliferation in biliary atresia

Biliary atresia (BA), which is thought to result from progressive destruction of the bile ducts by a necroinflammatory process, is the most common cause of obstructive jaundice in infancy. Abnormalities in the cell turnover of remodelling ductal plates are considered one of the important aetiological factors in this disorder, but little work has been done on this topic. Programmed cell death or apoptosis was therefore examined by TdT‐mediated dUTP biotin nick end labelling (TUNEL) and cell proliferation by Ki67 immunostaining in 34 cases of BA. The results were compared with normal control liver (five cases) and congenital dilatation of the bile ducts (CDB, five cases) in order to study the cell turnover or tissue dynamics of BA. The TUNEL labelling index (LI) in bile ducts (48·9±13·2 per cent) was significantly higher than that of the control normal liver (3·6±2·8 per cent) and of CDB (2·5±5·1 per cent). The Ki67 LI in the bile ducts of BA (15·0±5·57 per cent) was also significantly higher than that of CDB (8·6±5·4 per cent). No significant differences of the TUNEL and Ki67 LIs in hepatocytes were, however, observed between BA, CDB, and normal liver. The TUNEL LI was significantly higher than the Ki67 LI in the bile ducts of BA. BA is therefore associated with increased and disorganized cell turnover of the bile ducts, which is related to malformation of the ductal plate or abnormal bile duct development. Copyright

In situ expression of fibrogenic growth factors and their receptors in biliary atresia: comparison between early and late stages.

Progressive fibrosis, despite successful surgical treatment, is one of the serious complications of biliary atresia. To understand the mechanism of this fibrosis, the in situ expression of fibrogenic growth factors (TGF‐β and PDGF) and their corresponding receptors was studied by immunohistochemistry using frozen sections. The results were compared between the early (n=12) and late (n=6) stages. The early stage was characterized by abundant expression of all ligands and receptors, together with type I procollagen (PC‐I). The major cellular sources were activated fibroblasts/myofibroblasts distributed mostly in the portal tracts. Macrophages also expressed all the ligands and the receptors, but to a lesser degree. Bile duct cells strongly expressed TGF‐β RI and RII and PDGF AA and BB, but focally expressed TGF‐β. All of these decreased in the late stage of biliary atresia. These results suggest that TGF‐β and PDGF play important roles in the fibrogenesis of biliary atresia, especially in its early stage, acting either by autocrine or paracrine mechanisms involving activated fibroblasts/myofibroblasts, bile duct cells, and macrophages. Copyright

E‐cadherin, α‐catenin and β‐catenin in biliary atresia: Correlation with apoptosis and cell cycle

Biliary atresia (BA) is the most common cause of obstructive jaundice in infancy. Although the etiology of BA remains unknown, the ductal plate malformation has been considered to play an important role in the development of BA. Cell–cell adhesion has long been recognized as one of the most important processes in organogenesis. E‐cadherin is involved in cell–cell adhesion, together with the catenins. Abnormalities of E‐cadherin and associated catenins have not been examined in detail in the liver with BA. We therefore examined immunolocalization of E‐cadherin and α‐ and β‐catenins in the BA liver (n= 45) and compared the findings with those in non‐BA (n= 11) and fetal liver (n= 21). We semiquantitatively evaluated the findings using H score, which were generated according to the percentage of immunopositive cells and their immunointensity. We also examined mRNA localization of E‐cadherin using mRNA in situ hybridization. We then studied the correlation of E‐cadherin immunoreactivity with apoptotic cells, and cyclin‐dependent kinase inhibitor p27Kip1 immunolocalization of bile duct cells in BA liver (n= 10) and fetal liver (n= 10). In fetal liver, H score of E‐cadherin, but not of α‐ and β‐catenins, was significantly lower in the remodeling stage than in the ductal plate (P= 0.0034) and remodeled stages (P= 0.0024). In addition, the H score of E‐cadherin, but not α‐ and β‐catenin, in bile duct cells was significantly lower in BA liver than in non‐BA liver (P= 0.0132). E‐cadherin mRNA hybridization signals were relatively conserved in bile duct cells of BA liver, but decreased in remodeling ductal plate cells of fetal liver. An inverse correlation was detected between the H score of E‐cadherin and the TUNEL labeling index (LI) in both fetal and BA liver. In contrast, a positive correlation was detected between the H score of E‐cadherin and p27 LI in both fetal and BA liver. These findings suggest that impaired expression of E‐cadherin in bile ducts may play an important role in the biological features of BA, possibly associated with cell cycle and apoptosis.

Mesenteric teratoma in an 8-month-old girl

The authors report the case of a solid, mature teratoma of the mesentery occurring in an 8-month-old girl. The tumor was enucleated from the ileocecal mesentery. Histologically the tumor included all three embryonal layers. This is the youngest patient reported to have mesenteric teratoma.

Cytokeratin subtypes in biliary atresia: immunohistochemical study.

The etiology of biliary atresia (BA) remains unknown, but ductal‐plate malformation and insufficient ductal‐plate remodeling have been suggested to play important roles, so it is beneficial to examine the maturation and differentiation of bile ducts in BA. Different epithelial types are characterized by the expression of specific cytokeratin (CK) subtypes. CK can therefore serve as a ‘lineage marker’ of epithelial cells. CK subtypes have not been previously examined in BA. In this study, we examined the maturation of bile‐duct cells in BA (n = 45) using immunohistochemistry of CK subtypes, with mouse monoclonal antibodies to CAM5.2, and CK subtypes 7, 8, 13, 14, 17, 19 and 20. We then compared these findings with pediatric non‐BA (n = 11) and fetal (n = 21) liver. We semiquantitatively evaluated the findings using a H score method. In the fetal liver, immunoreactivity for CAM5.2, CK‐7, CK‐8 and CK‐19 was detected in bile‐duct cells, and CAM5.2 and CK‐8 immunoreactivity was also detected in hepatocytes. The distribution of these CK subtypes was the same in fetal, pediatric non‐BA and BA liver. However, CK‐7 immunoreactivity was markedly weaker in bile ducts of fetal (H scores: ductal plate 0 ± 0; remodeling 9.5 ± 40.3; remodeled 37.3 ± 60.8) and BA (H score: 200.9 ± 55.3) liver compared to non‐BA liver (H score: 251.1 ± 33.5). In addition, CK‐20 was detected in the bile ducts of the fetal and BA liver, but not in non‐BA liver. These findings suggest that the expression patterns of CK subtypes in bile‐duct cells in BA are similar to that in developing bile‐duct cells, which is indicative of bile‐duct cell immaturity.

An autopsy case of malignant mesothelioma associated with asbestosis

An autopsy case of malignant mesothelioma with asbestosis caused by asbestos exposure for 17 years is reported. Autopsy revealed that mesothelioma spread extensively in all serosal tissues including pleura, pericardium, diaphragm, peritoneum and tunica vaginalis testis. Histopathologically, most of the tumor showed an epithelial form, but sarcomatous and microcystic patterns were also observed. The tumor cells had abundant glycogen and hyaluronic acid and, immunohistochemically, they were positive for cytokeratin, vimentin and epithelial membrane antigen (EMA). Long, slender microvilli were characteristically observed in these tumor cells. All of these data were compatible with malignant mesothelioma. Procollagen type I (procol.I) immunostaining was performed to reveal the mesenchymal character of mesothelioma. Both epithelial‐type cells and sarcomatous‐type cells showed positive staining for procol.I, although the latter showed stronger immunoreactivity. Immunostaining for procol.I was found to be one of the useful tools for distinguishing mesothelioma from adenocarcinoma. Using an extraction method for asbestos fibers, asbestos bodies were found in many tissues including lymph nodes, liver, small intestine, spleen, kidney, testis and pleura, in addition to lung parenchyma. Although multiple tumor metastases from an undetermined primary site is not ruled out, ‘multifocal tumorigenesis’ is suspected from the widespread deposit of asbestsos fibers.

The effect of hepatic portal dissection on the portal vein structure in biliary atresia.

Superior mesenteric portograms were performed on 30 patients with biliary atresia (BA) at the time of initial portoenterostomy in 20, and at the stoma closure operation in 10. A withered-branch-shaped irregularity of the intrahepatic portal vein (PV) and collateral vessels were seen in 2 of 11 patients with portal pressures (PP) of 200 to 300 mmH2O; in 1 of 2 patients with PPs of over 300 mmH2O at the initial operation; and in 3 jaundice-free patients with PPs of 285, 320, and 305 mmH2O, respectively, at the stoma closure operation. Collaterals were the only abnormalities seen in two additional jaundice-free patients with PPs of 370 and 183 mmH2O, respectively. No anatomic changes in the extrahepatic PV at the porta hepatis were found on the portograms of either group of patients. Thus, we conclude that portal dissection itself does not affect the PV structure anatomically, a finding which has important implications in determining whether or not portoenterostomy adversely affects potential liver transplantation.