Anthony J. Demetris

Cell migration, chimerism, and graft acceptance

The chimeric nature of the transplanted liver was first shown in our long-surviving human recipients of orthotopic hepatic allografts in 1969.1 When liver grafts were obtained from cadaveric donors of the opposite sex, karyotyping studies showed that hepatocytes and endothelium of major blood vessels retained their donor specificity, whereas the entire macrophage system, including Kuppfer cells, was replaced with recipient cells.2 Where donor cells that had left the liver had gone was unknown, but their continued presence was confirmed by the acquisition and maintenance in recipient blood of new donor-specific immunoglobulin (Gm) types1,3 and red-blood-cell alloantibodies, if donors with ABO non-identity were used.4 Davies et al5 attributed the secretion of new soluble HLA class I antigens of donor type to transplanted hepatocytes. However, these HLA molecules come from bone-marrow-derived macrophages and/or dendritic cells,6 and probably have the same origin from migrated donor cells as the additional Gm types and red-cell antibodies.

Antibody-mediated rejection criteria - an addition to the Banff 97 classification of renal allograft rejection.

Antibody‐mediated rejection (AbAR) is increasingly recognized in the renal allograft population, and successful therapeutic regimens have been developed to prevent and treat AbAR, enabling excellent outcomes even in patients highly sensitized to the donor prior to transplant. It has become critical to develop standardized criteria for the pathological diagnosis of AbAR. This article presents international consensus criteria for and classification of AbAR developed based on discussions held at the Sixth Banff Conference on Allograft Pathology in 2001. This classification represents a working formulation, to be revisited as additional data accumulate in this important area of renal transplantation.

Banff '05 Meeting Report: Differential Diagnosis of Chronic Allograft Injury and Elimination of Chronic Allograft Nephropathy (‘CAN’)

The 8th Banff Conference on Allograft Pathology was held in Edmonton, Canada, 15–21 July 2005. Major outcomes included the elimination of the non‐specific term ‘chronic allograft nephropathy’ (CAN) from the Banff classification for kidney allograft pathology, and the recognition of the entity of chronic antibody‐mediated rejection. Participation of B cells in allograft rejection and genomics markers of rejection were also major subjects addressed by the conference.

A novel prognostic subtype of human hepatocellular carcinoma derived from hepatic progenitor cells

The variability in the prognosis of individuals with hepatocellular carcinoma (HCC) suggests that HCC may comprise several distinct biological phenotypes. These phenotypes may result from activation of different oncogenic pathways during tumorigenesis and/or from a different cell of origin. Here we address whether the transcriptional characteristics of HCC can provide insight into the cellular origin of the tumor. We integrated gene expression data from rat fetal hepatoblasts and adult hepatocytes with HCC from human and mouse models. Individuals with HCC who shared a gene expression pattern with fetal hepatoblasts had a poor prognosis. The gene expression program that distinguished this subtype from other types of HCC included markers of hepatic oval cells, suggesting that HCC of this subtype may arise from hepatic progenitor cells. Analyses of gene networks showed that activation of AP-1 transcription factors in this newly identified HCC subtype might have key roles in tumor development.

Banff ’09 Meeting Report: Antibody Mediated Graft Deterioration and Implementation of Banff Working Groups

The 10th Banff Conference on Allograft Pathology was held in Banff, Canada from August 9 to 14, 2009. A total of 263 transplant clinicians, pathologists, surgeons, immunologists and researchers discussed several aspects of solid organ transplants with a special focus on antibody mediated graft injury. The willingness of the Banff process to adapt continuously in response to new research and improve potential weaknesses, led to the implementation of six working groups on the following areas: isolated v‐lesion, fibrosis scoring, glomerular lesions, molecular pathology, polyomavirus nephropathy and quality assurance. Banff working groups will conduct multicenter trials to evaluate the clinical relevance, practical feasibility and reproducibility of potential changes to the Banff classification. There were also sessions on quality improvement in biopsy reading and utilization of virtual microscopy for maintaining competence in transplant biopsy interpretation. In addition, compelling molecular research data led to the discussion of incorporation of omics‐technologies and discovery of new tissue markers with the goal of combining histopathology and molecular parameters within the Banff working classification in the near future.

Classification and prediction of survival in hepatocellular carcinoma by gene expression profiling

We analyzed global gene expression patterns of 91 human hepatocellular carcinomas (HCCs) to define the molecular characteristics of the tumors and to test the prognostic value of the expression profiles. Unsupervised classification methods revealed two distinctive subclasses of HCC that are highly associated with patient survival. This association was validated via 5 independent supervised learning methods. We also identified the genes most strongly associated with survival by using the Cox proportional hazards survival analysis. This approach identified a limited number of genes that accurately predicted the length of survival and provides new molecular insight into the pathogenesis of HCC. Tumors from the low survival subclass have strong cell proliferation and antiapoptosis gene expression signatures. In addition, the low survival subclass displayed higher expression of genes involved in ubiquitination and histone modification, suggesting an etiological involvement of these processes in accelerating the progression of HCC. In conclusion, the biological differences identified in the HCC subclasses should provide an attractive source for the development of therapeutic targets (e.g., HIF1a) for selective treatment of HCC patients. Supplementary material for this article can be found on the HEPATOLOGY Web site (http://interscience.wiley.com/jpages/0270‐9139/suppmat/index.html) (HEPATOLOGY 2004;40:667–676.)

Hepatic resection versus transplantation for hepatocellular carcinoma

During the 10-year period (1980 to 1989), 76 patients with hepatocellular carcinoma (HCC) were treated by subtotal hepatic resection (HX) and 105 patients by orthotopic liver transplantation (TX) under cyclosporine-steroid therapy. Overall 1- to 5-year survival rates of the HX group were 71.1%, 55.0%, 47.2%, 37.2%, and 32.9%, respectively, and those of the TX group were 65.7%, 49.0%, 39.2%, 35.6%, and 35.6%, respectively. The survival rates after HX and after TX correlated well with pTNM stages and were similar in each stage between the two groups. However, when HCC was associated with cirrhosis of the liver, the survival rates after TX were significantly better than those after HX at each stage of pTNM classification. The tumor-recurrence rate was high both after HX (50%) and TX (43%), particularly in advanced stages of pTNM classification (60% or more). Twelve patients after HX and 13 patients after TX lived more than 5 years during this 10-year period. Fibrolamellar HCC and early stages of HCC were highly represented among the long-term survivors. Further improvement in survival rates depends on nonsurgical anti-cancer therapy before and/or after surgical removal of HCC.

Tolerogenic immunosuppression for organ transplantation

BACKGROUND Insight into the mechanisms of organ engraftment and acquired tolerance has made it possible to facilitate these mechanisms, by tailoring the timing and dosage of immunosuppression in accordance with two therapeutic principles: recipient pretreatment, and minimum use of post-transplant immunosuppression. We aimed to apply these principles in recipients of renal and extrarenal organ transplants. METHODS 82 patients awaiting kidney, liver, pancreas, or intestinal transplantation were pretreated with about 5 mg/kg of a broadly reacting rabbit antithymocyte globulin during several hours. Post-transplant immunosuppression was restricted to tacrolimus unless additional drugs were needed to treat breakthrough rejection. After 4 months, patients on tacrolimus monotherapy were considered for dose-spacing to every other day or longer intervals. FINDINGS We frequently saw evidence of immune activation in graft biopsy samples, but unless this was associated with graft dysfunction or serious immune destruction, treatment usually was not intensified. Immunosuppression-related morbidity was virtually eliminated. 78 (95%) of 82 patients survived at 1 year and at 13-18 months. Graft survival was 73 (89%) of 82 at 1 year and 72 (88%) of 82 at 13-18 months. Of the 72 recipients with surviving grafts, 43 are on spaced doses of tacrolimus monotherapy: every other day (n=6), three times per week (11), twice per week (15), or once per week (11). INTERPRETATION The striking ability to wean immunosuppression in these recipients indicates variable induction of tolerance. The simple therapeutic principles are neither drug-specific nor organ-specific. Systematic application of these principles should allow improvements in quality of life and long-term survival after organ transplantation.

Long-term survival after liver transplantation in 4,000 consecutive patients at a single center

ObjectiveTo evaluate the long-term survival outcomes of a large cohort of liver transplant recipients and to identify static and changing factors that influenced these outcomes over time. Summary Background DataLiver transplantation has been accepted as a therapeutic option for patients with end-stage liver disease since 1983, with continual improvements in patient survival as a result of advances in immunosuppression and medical management, technical achievements, and improvements in procurement and preservation. Although many reports, including registry data, have delineated short-term factors that influence survival, few reports have examined factors that affect long-term survival after liver transplantation. MethodsFour thousand consecutive patients who underwent liver transplantation between February 1981 and April 1998 were included in this analysis and were followed up to March 2000. The effect of donor and recipient age at the time of transplantation, recipient gender, diagnosis, and year of transplantation were compared. Rates of retransplantation, causes of retransplantation, and cause of death were also examined. ResultsThe overall patient survival for the entire cohort was 59%; the actuarial 18-year survival was 48%. Patient survival was significantly better in children, in female recipients, and in patients who received transplants after 1990. The rates of retransplantation for acute or chronic rejection were significantly lower with tacrolimus-based immunosuppression. The risk of graft failure and death was relatively stable after the first year, with recurrence of disease, malignancies, and age-related complications being the major factors for loss. ConclusionSignificantly improved patient and graft survival has been observed over time, and graft loss from acute or chronic rejection has emerged as a rarity. Age-related and disease-related causes of graft loss represent the greatest threat to long-term survival.

Modulation of nitrogen oxide synthesis in vivo: NG-monomethyl-L-arginine inhibits endotoxin-induced nitrate/nitrate biosynthesis while promoting hepatic damage.

Attempts were made to promote or inhibit nitric oxide (·N=O) synthesis in a murine model of hepatic damage (Corynebacterium parvum followed by lipopolysaccharide; LPS) to determine the role of N=O in the liver injury. Moderate hepatic damage and increases in circulating NO2 ‐/NO3 ‐ levels were detectable after C. parvum alone. Administration of LPS to these mice resulted in severe hepatic damage and acute elevations in circulating nitrogen oxide levels. L‐arg had no influence on the C. parvum or LPS‐induced changes. NG‐monomethyl‐L‐arginine (NMA) had no effect in the absence of LPS, but when given with LPS, a dose‐dependent suppression in plasma NO2 ‐/NO3 ‐ levels and an increase in liver injury were seen. The NMA‐induced changes were partially reversed by the simultaneous administration of L‐arg. These findings suggest a protective role for · N=O in this model.