Preservation of bile ductules mitigates bile duct loss

From immunosuppression to tolerance

The past three decades have seen liver transplantation becoming a major therapeutic approach in the management of end-stage liver diseases. This is due to the dramatic improvement in survival after liver transplantation as a consequence of the improvement of surgical and anaesthetic techniques, of post-transplant medico-surgical management and of prevention of disease recurrence and other post-transplant complications. Improved use of post-transplant immunosuppression to prevent acute and chronic rejection is a major factor in these improved results. The liver has been shown to be more tolerogenic than other organs, and matching of donor and recipients is mainly limited to ABO blood group compatibility. However, long-term immunosuppression is required to avoid severe acute and chronic rejection and graft loss. With the current immunosuppression protocols, the risk of acute rejection requiring additional therapy is 10-40% and the risk of chronic rejection is below 5%. However, the development of histological lesions in the graft in long-term survivors suggest atypical forms of graft rejection may develop as a consequence of under-immunosuppression. The backbone of immunosuppression remains calcineurin inhibitors (CNI) mostly in association with steroids in the short-term and mycophenolate mofetil or mTOR inhibitors (everolimus). The occurrence of post-transplant complications related to the immunosuppressive therapy has led to the development of new protocols aimed at protecting renal function and preventing the development of de novo cancer and of dysmetabolic syndrome. However, there is no new class of immunosuppressive drugs in the pipeline able to replace current protocols in the near future. The aim of a full immune tolerance of the graft is rarely achieved since only 20% of selected patients can be weaned successfully off immunosuppression. In the future, immunosuppression will probably be more case oriented aiming to protect the graft from rejection and at reducing the risk of disease recurrence and complications related to immunosuppressive therapy. Such approaches will include strategies aiming to promote stable long-term immunological tolerance of the liver graft.

Sorafenib therapy for hepatocellular carcinoma prior to liver transplant is associated with increased complications after transplant

This study compared post-transplant outcomes of patients with hepatocellular carcinoma (HCC) who took sorafenib prior to orthotopic liver transplantation (OLT) with those patients who were not treated with sorafenib. Thirty-three patients with HCC who were listed for liver transplantation were studied: 10 patients were treated with sorafenib prior to transplantation in an attempt to prevent progression of HCC while awaiting transplant. The remaining 23 patients were considered controls. The mean duration of sorafenib use was 19.2 (SD 25.2) weeks. Overall death rates were similar between the sorafenib group and control group (20% vs. 8.7%, respectively, P = 0.56). However, the patients in the sorafenib group had a higher incidence of acute cellular rejection following transplantation (67% vs. 22%, OR = 7.2, 95% CI 1.3-39.6, P = 0.04). The sorafenib group also had a higher rate of early biliary complications (67% vs. 17%, OR = 9.5, 1.6-55.0, P = 0.01). The use of sorafenib was found to be an independent predictor of post-transplant biliary complications (OR 12.6, 1.4-116.2, P = 0.03). Sorafenib administration prior to OLT appears to be associated with an increase in biliary complications and possibly in acute rejection following liver transplantation. Caution should be taken in this setting until larger studies are completed.

Localization of apoptosis proteins and lymphocyte subsets in chronic rejection of human liver allograft

In chronic liver rejection lymphocyte mediated processes lead to chronic inflammation, necrosis and repair mechanisms. The aim of the present study was to investigate the expression of apoptosis related proteins (FAS/APO-1, FAS-L, Bcl-2, Bax, TNF-α, and INF-γ). ApopTag reaction and immunohistochemistry were performed on liver samples of chronically rejected allografts and compared with normal donor livers. In chronic rejection, apoptosis was detected in pericentral hepatocytes and in the biliary epithelium. Bcl-2 was strongly expressed on lymphocytes around the bile ducts, but not on the biliary epithelium itself. Bax, FAS, TNF-α and INF-γ were present in pericentral areas. T-cells showed up around bile ducts, whereas macrophages around pericentral areas. In pericentral areas apoptosis seems to be fostered through TNF-α and INF-γ and by the lack of Bcl-2. Based on these results both downregulation and upregulation of apoptotic proteins can be observed in chronic liver allograft rejection: FAS is upregulated in biliary epithelium and zone 2, protein levels of FASL remain unchanged, BAX is upregulated in zone 3, BCL2 is downregulated in both biliary epithelium and zone 1 and both TNFa and IFN are upregulated in zone 3. Our results suggest that the balance between pro- and antiapoptotic patterns was shifted to the proapoptotic side, mainly in the centrilobular area of the hepatic lobule, and in the bile ducts. According to these findings in chronic rejection the predictive sites of apoptosis are the biliary epithelium and the pericentral areas.

Architectural and immunohistochemical characterization of biliary ductules in normal human liver

The canals of Hering or biliary ductules have been described to connect the bile canaliculi with the interlobular bile ducts, and thus forming the distal part of the biliary tree. Studies in the last two decades suggested that the cells constructing these ductules could behave as hepatic progenitor cells. The canals of Hering are confined to the periportal space in the rat, while they have been reported to spread beyond the limiting plate in human liver. The distribution of the distal biliary ductules in normal human hepatic tissue has been investigated in our recent experiments. We could demonstrate the presence of interlobular connective tissue septa in a rudimentary form in healthy livers. The canals of Hering run in these septa in line with the terminal branches of the portal vein and hepatic arteries. This arrangement develops in the postnatal period but regresses after early childhood. The canals of Hering can be identified by the unique epithelial membrane antigen (EMA)-/CD56+/CD133+ immunophenotype. The canals of Hering leave the periportal space and spread into the liver parenchyma along rudimentary interlobular septa outlining the hepatic lobules. Our observations refine the original architectural description of the intraparenchymal portion of the canals of Hering in the human liver. The distinct immunophenotype supports their unique biological function.

Vanishing bile duct syndrome

Perhaps no condition associated with chronic cholestasis is less understood than vanishing bile duct syndrome, a term that refers loosely to the group of acquired disorders associated with progressive destruction and disappearance of the intrahepatic bile ducts and, ultimately, cholestasis. Although the array of insults resulting in poor bile flow is vast, most adult patients who have chronic cholestasis have either primary biliary cirrhosis (or primary sclerosing cholangitis; in some cases, however, a cause cannot be identified. This article reviews the multiple causes, postulated pathophysiology, clinical features, and treatment options for this syndrome.