Analysis of the reversibility of chronic liver allograft rejection implications for a staging schema

Chronic rejection after liver transplantation: Opening the Pandora’s box

Chronic rejection (CR) of liver allografts causes damage to intrahepatic vessels and bile ducts and may lead to graft failure after liver transplantation. Although its prevalence has declined steadily with the introduction of potent immunosuppressive therapy, CR still represents an important cause of graft injury, which might be irreversible, leading to graft loss requiring re-transplantation. To date, we still do not fully appreciate the mechanisms underlying this process. In addition to T cell-mediated CR, which was initially the only recognized type of CR, recently a new form of liver allograft CR, antibody-mediated CR, has been identified. This has indeed opened an era of thriving research and renewed interest in the field. Liver biopsy is needed for a definitive diagnosis of CR, but current research is aiming to identify new non-invasive tools for predicting patients at risk for CR after liver transplantation. Moreover, the minimization or withdrawal of immunosuppressive therapy might influence the establishment of subclinical CR-related injury, which should not be disregarded. Therapies for CR may only be effective in the “early” phases, and a tailored management of the immunosuppression regimen is essential for preventing irreversible liver damage. Herein, we provide an overview of the current knowledge and research on CR, focusing on early detection, identification of non-invasive biomarkers, immunosuppressive management, re-transplantation and future perspectives of CR.

Graft Dysfunction and Management in Liver Transplantation

Graft dysfunction of the liver allograft manifests across a spectrum in both timing posttransplantation and clinical presentation. This can range from mild transient abnormalities of liver tests to acute liver failure potentially leading to graft failure. The causes of graft dysfunction can be divided into those resulting in early and late graft dysfunction. Although nonspecific, liver biochemistry abnormalities are still the mainstay investigation used in monitoring for dysfunction. This article provides a summary of the main causes and management strategies for liver graft dysfunction in the early through late posttransplant stages.

Acute and Chronic Rejection After Liver Transplantation: What A Clinician Needs to Know

While antibody mediated hyper-acute vasculitic rejection is rare in liver transplant recipients, acute and chronic rejection have clinical significance. The liver allograft behaves differently to other solid organ transplants as acute rejection generally does not impair graft survival and chronic rejection (CR) is uncommon. The incidence of acute and chronic rejection has declined in current era due to improved immunosuppressive regimens. Acute rejection generally improves with steroid boluses and steroid resistant rejection is uncommon. CR may improve with escalation of immunosuppression or may result in irreversible loss of graft function leading to retransplantation or death. The current review discusses diagnosis and management of acute and chronic liver allograft rejection.

Histological and Clinicopathological Evaluation of Liver Allograft Biopsy: An Initial Experience of Fifty Six Biopsies

INTRODUCTION

Liver biopsy is gold standard for diagnosis of allograft dysfunction.

AIM

The aim of study was to evaluate liver allograft biopsies performed for graft dysfunction, study the pattern of injury and intensity, and timeline of occurrence of graft dysfunction.

MATERIALS AND METHODS

Retrospective study was carried out of 56 liver allograft biopsies and their histological findings with clinical presentation were correlated. Totally 56 needle liver allograft biopsies from January 1210 to July 2014, obtained from 35 patients were studied for histological and clinicopathological evaluation.

RESULTS

The mean age was 53.2±5.48 years. The most common original disease was alcoholic cirrhosis. The most common histological lesion was acute cellular rejection (ACR) in 31 (55.36%) biopsies followed by preservation-reperfusion injury (PRI) in 10 (17.86%) biopsies and drug toxicity in 8 (14.29%) biopsies. Chronic rejection was reported in 2 (3.57%) and recurrence of HCV in 3 (5.36%). Ischemic coagulative necrosis and acute cholangitis were seen in 1 (1.79 %) case each.

CONCLUSION

Alcoholic cirrhosis was the most common etiology for end stage liver disease. ACR and PRI were the major complications in liver allograft biopsies at our centre.

Abnormal Localization of STK17A in Bile Canaliculi in Liver Allografts: An Early Sign of Chronic Rejection

The biological significance of STK17A, a serine/threonine kinase, in the liver is not known. We analyzed STK17A expression in HepG2 cells and human liver tissue. Accordingly, we investigated whether STK17A could help in identifying earlier changes during the evolution of chronic rejection (CR) after liver transplantation. RT-PCR and immunofluorescence were used to analyze STK17A expression in HepG2 cells. Antibody microarray was performed using human liver samples from CR and healthy donors. Immunohistochemistry was used to verify the clinical utility of STK17A on sequential biopsies for the subsequent development of CR. A novel short isoform of STK17A was found in HepG2 cells. STK17A was localized in the nuclei and bile canaliculi in HepG2 cells and human livers. Microarray of STK17A revealed its decrease in failed liver allografts by CR. During the evolution of CR, the staining pattern of bile canalicular STK17A gradually changed from diffuse linear to focal intermittent. The focal intermittent staining pattern was observed before the definite diagnosis of CR. In conclusion, the present study was the first to find localization of STK17A in normal bile canaliculi. Abnormal expression and localization of STK17A were associated with CR of liver allografts since the early stage of the rejection process.

Functional role of cellular senescence in biliary injury

Cellular senescence is a state of irreversible cell cycle arrest that has been involved in many gastrointestinal diseases, including human cholestatic liver disorders. Senescence may play a role in biliary atresia, primary sclerosing cholangitis, cellular rejection, and primary biliary cirrhosis, four liver diseases affecting cholangiocytes and the biliary system. In this review, we examine proposed mechanisms of senescence-related biliary diseases, including hypotheses associated with the senescence-associated phenotype, induction of senescence in nearby cells, and the depletion of stem cell subpopulations. Current evidence for the molecular mechanisms of senescence in the previously mentioned diseases is discussed in detail, with attention to recent advances on the role of pathways associated with senescence-associated phenotype, stress-induced senescence, telomere dysfunction, and autophagy.

Consensus on the histopathological evaluation of liver biopsies from patients following allogeneic hematopoietic cell transplantation

After allogeneic hematopoietic cell transplantation (alloHCT) liver biopsy is performed for enigmatic liver disorders when noninvasive diagnostic steps have failed in establishing a definitive diagnosis. This document provides an updated consensus on the prerequisites for proper evaluation of liver biopsies in alloHCT patients and the histological diagnostic criteria for liver graft-versus-host disease (GvHD). The Working Group's recommendations for the histological diagnosis of liver GvHD were derived from the peer-reviewed literature and from the consensus diagnosis of a total of 30 coded liver biopsies. Acceptance of the recommendations was tested by a survey distributed to all HCT centers in Austria, Germany and Switzerland. Consensus was achieved for biopsy indications, methods of sample acquisition and processing, reporting and interpretation of biopsy findings. As GvHD is variably treated and the treatment modalities have changed over time, the panel endorses the use of more frequent biopsies in clinical studies in order to improve the present challenging clinical and diagnostic situation.

Histopathological causes of late liver allograft dysfunction: analysis at a single institution

Background

We summarize our experience in the pathological diagnosis of late complications of liver transplantation (LT) to better understand the causes of late allograft dysfunction in a population mostly composed of patients with hepatitis B virus (HBV) infection.

Methods

We reviewed 361 post-transplant liver biopsies from 174 patients who underwent LT and first presented with liver function abnormalities 3 months post-procedure. The underlying diseases included HBV-associated liver disease (77%), toxic or alcoholic liver disease (10.3%), hepatitis C virus (HCV)-associated liver disease (8.6%), primary biliary cirrhosis (1.2%), primary sclerosing cholangitis (1.2%), and metabolic disease (1.7%).

Results

The three most common late complications were acute rejection (32.5%), recurrent disease (19.1%), and biliary complication (17.1%). Patients who underwent LT for HBV infection or for drug- or alcohol-related liver disease had a lower incidence of recurring disease than those who underwent transplantation for HCV infection. During post-transplantation months 3-12, acute rejection was the most common cause of allograft dysfunction and recurring disease was the leading cause for allograft dysfunction (p=0.039). The two primary causes of late allograft dysfunction have overlapping histological features, although acute rejection more frequently showed bile duct damage and vascular endothelialitis than recurring HBV infection, and recurring HBV infection had more frequent lobular activity and piecemeal necrosis.

Conclusions

The causes of late liver allograft dysfunction are closely associated with the original liver diseases and the period after LT. Careful attention is required for differential diagnosis between acute rejection and recurrent HBV.

The immunoreactive patient: Rejection and autoimmune disease

1. Despite highly potent immunosuppression regimens, there is a small cohort of patients at risk of graft failure due to rejection. 2. Steroid-resistant rejection is managed by the escalation of immunosuppression, but only one-third of patients with chronic rejection respond to this approach. 3. Interferon therapy for recurrent hepatitis C may induce an immunoreactive state and increase rejection rates. 4. Cyclosporine reduces the risk of recurrence of primary biliary cirrhosis but does not alter survival rates. 5. Patterns of primary sclerosing cholangitis recurrence are not affected by immunosuppression. 6. Autoimmune hepatitis recurrence and de novo autoimmune hepatitis are corticosteroid-responsive in most cases.

Muromonab-CD3 for the successful treatment of early chronic rejection after pediatric liver transplantation: report of a case

A four-and-a-half-year-old boy underwent living-donor liver transplantation (LDLT) for progressive familial intrahepatic cholestasis. Immunosuppressive therapy was commenced with tacrolimus and methylprednisolone, despite which derangement of liver function tests (LFTs) became evident on postoperative day (POD) 7. A diagnosis of acute cellular rejection was made and steroid pulse therapy (SPT) was initiated. Although the LFTs improved transiently after SPT, they deteriorated again, and failed to respond to repeated SPT. Jaundice was prolonged and transudative ascitic fluid accumulated. Liver needle biopsies on PODs 20 and 24 confirmed severe graft damage constituting early chronic rejection. Based on the poor response to steroid therapy, coagulopathy, and protein-losing ascites, 3 mg/body weight of muromonab-CD3 was given from POD 24, increasing to 5 mg/body weight from POD 29. A rebound in LFTs appeared after the muromonab-CD3 therapy was discontinued and the LFTs normalized. The ascites and jaundice also disappeared, and the patient's general condition improved. Liver needle biopsies on POD 47 and 61 confirmed dramatic recovery from severe graft damage.

Hepatocyte cytokeratin 7 expression in chronic allograft rejection

We examined hepatocyte cytokeratin 7 (CK7) expression in chronic allograft rejection (CR), a ductopenic condition in which this has not been systematically evaluated, in 20 patients with the clinicopathologic diagnosis of CR and age-, sex-, and native-disease-matched control subjects. We also studied baseline biopsy specimens from both groups. Three pathologists independently reviewed H&E- and CK7-stained sections, counting interlobular bile ducts (BDs) and portal tracts (PTs), noting the morphologic pattern of injury and scoring hepatocyte CK7 expression (0, none; 1+, rare; 2+, multifocal, predominantly periportal; 3+, extension into the lobule; 4+, diffuse). Mean BD/PT ratios and CK7 scores were calculated. The mean BD/PT ratio (0.58) and CK7 score (1.01) for the "CR, diagnostic" group were significantly different from all other group means (P < .05); no other comparisons were significant (P > .05). A CK7 score of 1 or more was observed in 9 (56%) of 16 CR specimens and in 3 (7%) of 41 remaining specimens. Hepatocyte CK7 expression is frequently noted in CR, and it would appear to reflect ductopenia. CK7 staining may be a useful diagnostic adjunct in evaluation of transplant liver biopsy specimens.

Chronic liver allograft dysfunction

Approximately 90% of liver transplant patients are alive after 1 year and 75% after 5 years with the majority leading full and near-normal lives. However, although early mortality rates after transplantation have fallen dramatically over the last 2 decades, the rates of late graft loss and patient death have remained constant. Thus, understanding of the causes of graft and patient failure is essential to improve long-term outcomes. In the early days after liver transplantation, ischemia and reperfusion injuries predominate, with acute cellular rejection relatively common in first 3 months. Thereafter, the causes of graft dysfunction are variable with disease recurrence as a major cause of graft loss. In this review, we discuss causes of graft dysfunction after 6 months.

Seeking beyond rejection: an update on the differential diagnosis and a practical approach to liver allograft biopsy interpretation

Pathologic evaluation of liver allograft biopsies plays an integral role in the management of patients after liver transplantation. This review summarizes the clinical context and classical histology of different types of allograft rejection and also the common entities that enter the differential diagnosis of allograft rejection, and provides practical approaches to liver allograft biopsy interpretation. In addition, some of the new developments in the field of liver transplant pathology are updated. The purpose of this review is to provide guidance for pathologists interpreting liver allograft biopsies, particularly those interested in developing expertise in the field of liver transplant pathology.

Interface hepatitis is associated with a high incidence of late graft fibrosis in a group of tightly monitored pediatric orthotopic liver transplantation patients

Chronic graft dysfunction, manifesting with elevated liver enzymes and histological features of interface hepatitis (IH), is being increasingly recognized as a long-term problem after liver transplantation. The aim of this study was to characterize our group of post-orthotopic liver transplantation (OLT) patients with respect to clinical, laboratory, and histological signs of IH. A retrospective study of charts and liver biopsy specimens from patients transplanted between 1986 and 1999 was used. Histological features of IH were found in 29/119 patients at a median interval of 23.9 months (95% confidence interval -28.2 to 52.6) after OLT. All patients with IH had risk factors for chronic rejection, such as steroid-resistant rejection, acute rejection later than 3 months post-OLT, female receiver of male graft, or pretransplant cytomegalovirus (CMV)-positive serology with a CMV-negative donor liver. None of the 29 had features favoring a diagnosis of de novo autoimmune hepatitis, but 4 had isolated hypergammaglobulinemia, and 4 had non-organ-specific autoantibodies without hyperimmunoglobulin G. Sixteen of 29 patients also had features of chronic rejection, such as foam cell arteriopathy, loss of bile ducts, or pericentral fibrosis. After abnormal biopsy, all but 1 patient were switched to tacrolimus. During a median follow-up of 12 years, death occurred in 5, retransplantation occurred in 7, and definite cirrhosis occurred in 4. In conclusion, IH was detected in 24.4% of our patients and was associated with a high degree of fibrosis development. Most likely, IH represents a form of chronic rejection directed against periportal hepatocytes.

Epithelial-mesenchymal transition contributes to portal tract fibrogenesis during human chronic liver disease

The relationship between bile duct damage and portal fibrosis in chronic liver diseases remains unclear. This study was designed to show whether human intrahepatic biliary epithelial cells can undergo epithelial-mesenchymal cell transition, thereby directly contributing to fibrogenesis. Primary human cholangiocytes were stimulated with transforming growth factor-beta (TGFbeta) or TGFbeta-presenting T cells and examined for evidence of transition to a mesenchymal phenotype. Liver sections were labelled to detect antigens associated with biliary epithelial cells (cytokeratin 7 and 19 and E-cadherin), T cells (CD8), epithelial-mesenchymal transition (S100A4, vimentin and matrix metalloproteinase-2 (MMP-2)), myofibroblasts (alpha-smooth muscle actin) and intracellular signal-transduction mediated by phosphorylated (p)Smad 2/3; in situ hybridisation was performed to detect mRNA encoding TGFbeta and S100A4. Stimulation of cultured cells with TGFbeta induced the expression of pSmad2/3, S100A4 and alpha-smooth muscle actin; these cells became highly motile. Although normal bile ducts expressed ALK5 (TGFbeta RI), low levels of TGFbeta mRNA and nuclear pSmad2/3, they did not express S100A4, vimentin or MMP-2. However, TGFbeta mRNA and nuclear pSmad2/3 were strongly expressed in damaged ducts, which also expressed S100A4, vimentin and MMP-2. Fibroblast-like cells which expressed S100A4 were present around many damaged bile ducts. Cells in the 'ductular reaction' expressed both epithelial and mesenchymal markers together with high levels of TGFbeta mRNA and pSmad2/3. In conclusion, the cells forming small- and medium-sized bile ducts and the ductular reaction undergo EMT during chronic liver diseases, resulting in the formation of invasive fibroblasts; this process may be driven by a response to local TGFbeta, possibly presented by infiltrating T cells.

Histopathology of graft versus host disease of the liver

AIMS

To analyse the histological features of 33 patients (48 biopsy specimens) with a clinicopathological diagnosis of graft vs. host disease of the liver (L-GVHD).

RESULTS

The time of biopsy post-haematopoietic stem cell transplantation (HSCT) ranged from 22 to 1082 days (median 144 days). Bile duct damage (BDD) was present in all biopsies except one. The bile duct to portal ratio ranged from 0.3 to 1 (median 0.8). Moderate/severe lobular hepatitis was present in 11 biopsies. Endotheliitis was present in four biopsies (8%). The majority of the biopsies showed none [25 (52%)] or mild [17 (35%)] fibrosis. The only significant difference between biopsies earlier ("acute") or later ("chronic" GVHD) than 100 days post-HSCT was the presence of portal inflammation in the "chronic" GVHD group.

CONCLUSION

BDD is the predominant change in L-GVHD. In about a quarter of biopsies the appearance may be of a lobular hepatitis. L-GVHD is not a fibrogenic process. The significance of separating acute versus chronic L-GVHD based on a cut-off of 100 days post-HSCT is questionable. Further studies are needed to understand the relationships between the mechanisms of BDD, bile duct loss and regeneration.

Preservation of bile ductules mitigates bile duct loss

The finer branches of the biliary tree (FBBT) contain a regenerative compartment. We hypothesized that preservation of the FBBT together with its microvasculature will lead to recovery of biliary damage and prolonged preservation of bile ductules during the development of chronic liver allograft rejection. The interlobular bile ducts, portal bile ductules and extraportal biliary cells with and without microvessels were studied in sequential biopsies in five patients who fulfilled the Banff criteria of early chronic rejection (CR) (imminence group). Biopsies of CR patients (n = 12) served as controls. Biopsies were double immunostained with CD34 (microvessels) and cytokeratin 7 (biliary structures). Proliferation and proangiogenic activity were assessed with Ki67 and VEGF-A immunostaining. Severe damage of bile ducts in the imminence group did not progress to significant bile duct loss. This was associated with a high proliferative activity in all biliary structures and preservation of the microvascular compartment. VEGF-A expression was increased in all but the reperfusion biopsies. In conclusion, both regenerative activity of the FBBT and an intact microvascular compartment are associated with less damage of the biliary tree and could therefore be prerequisites for biliary regeneration.

Distinguishing between recurrent primary sclerosing cholangitis and chronic rejection

1. Recurrent primary sclerosing cholangitis (PSC) is extremely difficult, if not impossible, to distinguish from other causes of biliary strictures or sclerosing cholangitis in allografts using needle biopsy evaluation alone. Technical problems with biliary reconstruction, long cold ischemic times, non-heart beating donors, ABO blood group incompatibility, antibody-mediated rejection, and small-for-size syndrome in reduced-size or living donor livers can also cause similar manifestations in a peripheral core biopsy. 2. Some difficulties in distinguishing between sclerosing cholangitis and chronic rejection (CR) arise because: a) at risk populations are similar; b) both can cause "cholestatic" elevation of liver injury tests; and c) both can lead to intrahepatic cholestasis and small bile duct loss. 3. Etiopathogenesis and pathology of CR and sclerosing cholangitis have some overlapping features, but show distinct differences that result in significantly different and discriminating pathologic manifestations. 4. Clues in the clinical history, evaluation of serial biopsies, and histopathology can be used to distinguish with confidence between sclerosing cholangitis and CR. 5. Potential discriminating features include liver size and gross appearance, and histopathology findings in the arterial tree, hilar lymph nodes, large and small bile ducts, interface zone, lobular, and perivenular regions.

Biliary wound healing, ductular reactions, and IL-6/gp130 signaling in the development of liver disease

Basic and translational wound healing research in the biliary tree lag significantly behind similar studies on the skin and gastrointestinal tract. This is at least partly attributable to lack of easy access to the biliary tract for study. But clinical relevance, more interest in biliary epithelial cell (BEC) pathophysiology, and widespread availability of BEC cultures are factors reversing this trend. In the extra-hepatic biliary tree, ineffectual wound healing, scarring and stricture development are pressing issues. In the smallest intra-hepatic bile ducts either impaired BEC proliferation or an exuberant response can contribute to liver disease. Chronic inflammation and persistent wound healing reactions in large and small bile ducts often lead to liver cancer. General concepts of wound healing as they apply to the biliary tract, importance of cellular processes dependent on IL-6/gp130/STAT3 signaling pathways, unanswered questions, and future directions are discussed.

Diagnosis and management of allograft failure

The article focuses on diagnosis and management of allograft failure in four main categories: (1) ischemic-reperfusion injury (primary nonfunction), (2) technical complications (hepatic artery and portal vein thrombosis), (3) chronic rejection, and (4) recurrent disease. It also discusses the complex problems involved in retransplantation for allograft failure.

NIDDK data repository: a central collection of clinical trial data

Background

The National Institute of Diabetes and Digestive and Kidney Diseases have established central repositories for the collection of DNA, biological samples, and clinical data to be catalogued at a single site. Here we present an overview of the site which stores the clinical data and links to biospecimens.

Description

The NIDDK Data repository is a web-enabled resource cataloguing clinical trial data and supporting information from NIDDK supported studies. The Data Repository allows for the co-location of multiple electronic datasets that were created as part of clinical investigations. The Data Repository does not serve the role of a Data Coordinating Center, but rather as a warehouse for the clinical findings once the trials have been completed. Because both biological and genetic samples are collected from many of the studies, a data management system for the cataloguing and retrieval of samples was developed.

Conclusion

The Data Repository provides a unique resource for researchers in the clinical areas supported by NIDDK. In addition to providing a warehouse of data, Data Repository staff work with the users to educate them on the datasets as well as assist them in the acquisition of multiple data sets for cross-study analysis. Unlike the majority of biological databases, the Data Repository acts both as a catalogue for data, biosamples, and genetic materials and as a central processing point for the requests for all biospecimens. Due to regulations on the use of clinical data, the ultimate release of that data is governed under NIDDK data release policies. The Data Repository serves as the conduit for such requests.

The influence of late acute rejection episodes on long-term graft outcome after liver transplantation

Acute cellular rejection represents the most important single risk factor for the occurrence of chronic rejection after organ transplantation. We correlated late acute rejections with the occurrence of chronic graft failure after liver transplantation. We followed 1426 liver transplants for late acute rejection episodes defined as occurring >3 months after OLT. The overall incidence of chronic rejection in our patient population was 3.7%. In summary, we observed a predictive increase of transaminase levels prior to routine biopsies among patients with histologic evidence of late acute rejections. In contrast to other organ systems, late acute rejection episodes were not associated with the occurrence of chronic graft deterioration in liver grafts.

FK778 and FK506 Combination Therapy to Control Acute Rejection after Rat Liver Allotransplantation

BACKGROUND

In organ transplantation, several immunosuppressants are currently used to control graft rejection. Clinically, no single immunosuppressive agent can completely prevent posttransplantation immunoreaction; thus, combination therapy is usually performed. Novel agents with more powerful immunosuppressive activity and less toxicity need to be developed.

METHODS

Lewis rat livers were orthotopically transplanted into Brown-Norway recipients. FK778 was administered orally from day 0 to day 6 to prevent acute rejection and from day 7 to day 13 to rescue ongoing rejection. To assess the combined effects, recipients were treated with intramuscular injection of FK506 and oral administration of FK778 from day 0 to day 6. Blood chemistry and histopathologic findings were measured to determine the patient's general condition and the graft condition. Allospecific antibodies were measured using enzyme-linked immunosorbent assays. The FK778 trough concentration was examined by using high-performance liquid chromatography.

RESULTS

The acute immune response was suppressed by FK778 alone in a dose-dependent manner. The optimal FK778 dosage was determined to be 20 mg/kg per day, because adverse effects (weight loss and intestinal bleeding) occurred at 30 mg/kg per day. FK778 treatment from day 7 to day 13 rescued liver grafts from ongoing rejection. The intramuscular FK506 (0.125 mg/kg per day) injection and the oral FK778 (20 mg/kg per day) gavages suppressed acute liver graft rejection effectively and maintained better graft condition compared with monotherapy. CONCLUSIONS.: FK778 treatment effectively prevented acute rejection and rescued ongoing rejection after liver transplantation. The optimal dosage was determined to be 20 mg/kg per day. Combination therapy with FK506 was more beneficial than FK778 monotherapy.

Recurrent Hepatitis C in Liver Allografts

RATIONALE AND DESIGN

The accuracy of a prospective histopathologic diagnosis of rejection and recurrent hepatitis C (HCV) was determined in 48 HCV RNA-positive liver allograft recipients enrolled in an "immunosuppression minimization protocol" between July 29, 2001 and January 24, 2003. Prospective entry of all pertinent treatment, laboratory, and histopathology results into an electronic database enabled a retrospective analysis of the accuracy of histopathologic diagnoses and the pathophysiologic relationship between recurrent HCV and rejection.

RESULTS

Time to first onset of acute rejection (AR) (mean, 107 days; median, 83 days; range, 7-329 days) overlapped with the time to first onset of recurrent HCV (mean, 115 days; median, 123 days; range, 22-315 days), making distinction between the two difficult. AR and chronic rejection (CR) with and without co-existent HCV showed overlapping but significantly different liver injury test profiles. One major and two minor errors occurred (positive predictive values for AR = 91%; recurrent HCV = 100%); all involved an overdiagnosis of AR in the context of recurrent HCV. Retrospective analysis of the mistakes showed that major errors can be avoided altogether and the impact of unavoidable minor errors can be minimized by strict adherence to specific histopathologic criteria, close clinicopathologic correlation including examination of HCV RNA levels, and a conservative approach to the use of additional immunosuppression. In addition, histopathologic diagnoses of moderate and severe AR and CR were associated with relatively low HCV RNA levels, whereas relatively high HCV RNA levels were associated with a histopathologic diagnosis of hepatitis alone, particularly the cholestatic variant of HCV.

CONCLUSIONS

Liver allograft biopsy interpretation can rapidly and accurately distinguish between recurrent HCV and AR/CR. In addition, the histopathologic observations suggest that the immune mechanism responsible for HCV clearance overlap with those leading to significant rejection.

All liver recipients benefit from the protocol 10-year liver biopsies

The value of late protocol biopsies after liver transplantation remains to be evaluated to highlight the therapeutic policies. The study population was composed of patients who survived with the initial graft and with an available 10-year protocol biopsy (n = 143). The long-term histologic outcome of the graft, particularly the rate of ductopenia in cases with chronic rejection (CR), and Metavir scoring of fibrosis in cases with viral chronic hepatitis (VCH), were assessed. Fibrosis progression (FP) rates were compared over 3 periods (0-5, 5-10, and 0-10 years). At 10 years, histologic abnormalities present in 80% of the patients were not identifiable from liver function tests (LFTs), which were strictly normal in 52% of the patients. Histologic CR occurred in 24% at 10 years, with a mean rate of ductopenia higher at 10 years than at 5 years (49% vs. 34%, P <.001). In cases of VCH, fibrosis worsened, with a median FP rate of 0.20 fibrosis units/year. During the first 5 years, FP was as follows; hepatitis B virus infection was greater than recurrent hepatitis C virus (HCV) infection, which was greater than acquired HCV infection (P =.029). In patients with HCV, FP was higher during the second 5-year period than during the first one (P =.042). In conclusion, given the high prevalence of histologic abnormalities and the lack of sensitivity and specificity of LFTs, late protocol biopsies clearly are justified to adjust treatments, not only in HCV-infected patients in whom FP was fast and not linear, but also in the whole population of recipients.

Chronic rejection of small bowel grafts: pediatric and adult study of risk factors and morphologic progression

One hundred and seventy-two patients underwent small bowel transplantation at Children's Hospital of Pittsburgh and University of Pittsburgh Medical Center between May 1990 and August 2001. Thirty-four patients had complete or partial resection of their primary graft and in 15, histologic features of chronic rejection were present in the resected small bowel. This is a descriptive and correlative study of the demographic, perioperative, and histologic features associated with progression to intestinal graft failure. Variable features associated with an increased risk of chronic rejection included acute rejection within the 1st month, increased number and higher grade of acute rejection episodes, isolated small bowel grafts rather than small bowel-liver grafts, older recipient age, non-Caucasian race, and Caucasian to non-Caucasian transplant. The mucosal biopsies showed predictive changes many months before the grafts were excised. The mucosal biopsy diagnosis of chronic vascular rejection can be difficult because the affected vessels, the distal branches of the mesenteric arteries, and the larger arteries of the subserosa and submucosa are not routinely sampled. The possibility of underlying arteriopathy, however, can be inferred in some instances from the presence of secondary mucosal changes in the small bowel biopsies though the "early" changes lack specificity. It is the progression of biopsy findings over time that is predictive of outcome. It is important to recognize the persistence of "late" mucosal changes of chronic rejection so that patients are not subjected to increased immune suppression when it is unlikely to be of significant benefit.

Recent advances in liver transplantation

Advances in liver transplantation continue to evolve but are hampered by continued increasing shortages in donor organs. This has resulted in a high incidence of patients dying while on the United Network for Organ Sharing waiting list. Indeed, we continue to assess ways of expanding the donor pool by using marginal donors, living donor liver transplantation, split liver transplantation, domino transplantation, and hepatic support systems to prolong survival long enough for the patient to undergo liver transplantation. Changes in the liver allocation policy to reduce the number of people dying while waiting for an organ are discussed. Implementation of the model for end-stage liver disease allocation system should help alleviate the problem of increasing deaths of patients while on the waiting list. Recurrent disease, particularly recurrent hepatitis C, continues to be a major problem, and effective therapy is needed to prevent both progression of hepatitis C and recurrence in the graft and avoid retransplantation. The use of pegylated interferon in combination with ribavirin holds promise for improving the success in overcoming recurrent hepatitis C. Finally, advances in immunosuppression have reduced the incidence of acute cellular rejection and chronic rejection. However, these therapies have been fraught with metabolic complications that are now affecting quality of life and long-term survival. Tailoring immunosuppressive regimens to the individual patient is discussed.

Real-time monitoring of acute liver-allograft rejection using the Banff schema

BACKGROUND

The Banff schema is the internationally accepted standard for grading acute liver-allograft rejection, but it has not been prospectively tested.

METHODS

Complete Banff grading was prospectively applied to 2,038 liver-allograft biopsies from 901 adult tacrolimus-treated primary hepatic allograft recipients between August 1995 and September 2001. Histopathologic data was melded with demographic, clinical, and laboratory data into a database on an ongoing basis using locally developed software.

RESULTS

Acute rejection developed in 575 of 901 (64%) patients and the worst grade was mild in 422 of 575 (73%). At least one episode of moderate or severe acute rejection developed in 153 of 901 (17%) patients and most episodes, irrespective of severity, occurred within the first year after transplantation. Patients with moderate or severe acute rejection showed higher alanine aminotransferase (P =0.007) and aspartate aminotransferase ( P=0.07) levels and were more likely to develop perivenular fibrosis on follow-up biopsies (P =0.001) and graft failure from acute or chronic rejection ( P=0.004) than those with mild rejection. Regardless of severity, 80% of patients with acute rejection did not develop significant fibrosis in follow-up biopsies, and graft failure from acute or chronic rejection occurred in only 11 of 901 (1%) allografts.

CONCLUSIONS

Most acute-rejection episodes are mild and do not lead to clinically significant architectural sequelae. When tested prospectively under real-life and -time conditions, the Banff schema can be used to identify those few patients who are potentially at risk for more significant problems. Creation, capture, and integration of non-free text, or "digital," pathology data can be used to prospectively conduct outcomes-based research in transplantation.

Histologic and biochemical changes during the evolution of chronic rejection of liver allografts

Criteria for histologic diagnosis of chronic rejection (CR) are based on changes seen late in the disease process that are likely to be irreversible and unresponsive to treatment. Changes occurring during the evolution of CR are less clearly defined. The serial biopsy specimens, failed allografts, and biochemical profiles of 28 patients who underwent retransplantation for CR were examined with the aim of identifying histologic and biochemical features that were present during the early stages of CR. For each case, a point of acute deterioration in liver function tests (LFTs) was identified ("start time" [ST]) that subsequently progressed to graft failure. Biopsy specimens before, at the time of ("start biopsy" [SB]), and after the ST were assessed histologically, and findings were correlated with the biochemical changes. CR resulted from acute rejection (AR) that did not resolve. Centrilobular necroinflammation (CLNI) associated with an elevated aspartate transaminase (AST) level and portal tract features of AR were present at the start. Portal AR features resolved, CLNI persisted, AST level remained elevated, and bilirubin and alkaline phosphatase levels progressively increased throughout the evolution of CR. Portal tracts also showed a loss of small arterial and bile duct branches, with arterial loss occurring early and bile duct loss as a later progressive lesion. Foam cell arteriopathy was rarely seen in needle biopsy specimens. In conclusion, findings from this study may help identify patients at risk of progressing to graft loss from CR at a stage when the disease process is potentially reversible and amenable to treatment.

The significance of parenchymal changes of acute cellular rejection in predicting chronic liver graft rejection

BACKGROUND

Chronic rejection (CR) in liver allografts shows a rapid onset and progressive course, leading to graft failure within the first year after transplantation. Most cases are preceded by episodes of acute cellular rejection (AR), but histological features predictive for the transition toward CR are not well documented.

METHODS

We assessed the predictive value of centrilobular necrosis, central vein endothelialitis (CVE), central vein fibrosis, and lobular inflammation in the development of CR. One-week and one-month biopsy specimens of 12 patients with CR were compared with those of a control group consisting of 17 patients, who experienced AR without developing CR. The progress of the histological changes was further evaluated in follow-up biopsy specimens of the CR group taken at 2 months and beyond 3 months after transplantation.

RESULTS

Centrilobular necrosis, CVE, central vein fibrosis, and lobular inflammation were common features in both groups at 1 week. At 1 month, the incidence declined in the control group. The CR group showed an increased incidence and persistence of these features in the follow-up biopsy specimens. The incidence and median grade of severity of CVE was significantly higher in the CR group (P=0.04 and P<0.001). The severity of portal and lobular inflammation was also more pronounced in the CR group (P=0.01 and 0.068). Conversely, in the control group, the incidence of the lobular features decreased and the severity of CVE declined significantly (P=0.03).

CONCLUSION

The shift from a predominantly portal-based process toward lobular graft damage represents the early transition of AR to CR, for which a modification of immunosuppression might be necessary to prevent graft loss.

Accuracy of bile duct changes for the diagnosis of chronic liver allograft rejection: reliability of the 1999 Banff schema

Chronic rejection (CR) after liver transplantation is thought to be a dynamic and potentially reversible process. The Banff working group has developed recommendations for its histopathologic staging. The 1999 Banff classification of CR (i.e., bile duct dystrophy >50% and/or bile duct loss >20%) was applied to: 1) biopsies from patients retransplanted for CR (N = 19) and pathologies other than CR (N = 21) to evaluate its specificity and sensitivity, especially of the early stage lesions of CR; and 2) biopsies from nonretransplanted patients (N = 21) to evaluate the evolution of CR lesions. Atypical forms of CR were also described. Including an early stage into the definition of CR has resulted in a much higher sensitivity for its diagnosis, as compared with the former classification (i.e., bile duct loss >50%) (89% vs. 33%; P =.0001), while keeping an acceptable specificity (74% vs. 100%; P =.03). In 55% of the nonretransplanted patients, CR lesions were reversible. No histologic feature reliably predicted CR outcome. Transient lobular hepatitis, unrelated to viral infection, and veno-occlusive disease were seen significantly more often in the CR group (P =.04 and P =.03, respectively). We conclude that the application of the 1999 Banff classification is superior to the previous classification for the diagnosis of CR. However, limited information can be drawn regarding the outcome of CR based on histology alone. Transient lobular hepatitis, unrelated to viral infection and veno-occlusive disease, may be an unusual expression of CR.

Late hepatic allograft dysfunction

1. Lifelong monitoring of graft function, immunosuppressive levels, and screening for drug toxicity is required in all liver recipients. 2. Late hepatic allograft dysfunction is common and is caused by a variety of etiologies including rejection, infection, biliary/vascular abnormalities, recurrence of disease, and drug hepatotoxicity. 3. In all patients with late hepatic allograft dysfunction, liver biopsy should be performed to assess for the presence of rejection, and to thus avoid excessive use of bolus corticosteroid therapy and guide appropriate immunosuppressive management. 4. Recurrence of disease is the most common cause of late hepatic allograft dysfunction. 5. Hepatitis C universally reinfects the hepatic allograft, and is associated with decreased patient and graft survival and leads to the recurrence of cirrhosis in 28% of patients within 5 years of transplantation. 6. Major advances have been made in preventing recurrence of hepatitis B by the use of hepatitis B immune globulin in combination with lamivudine therapy. 7. Autoimmune liver diseases such as primary biliary cirrhosis, primary sclerosing cholangitis, and autoimmune hepatitis have a recurrence rate of approximately 20% to 30%. 8. In patients developing recurrence of autoimmune hepatitis, steroid withdrawal is the most common cause. 9. Recurrent hepatocellular cancer can be markedly reduced if strict guidelines are adhered to in selecting patients. 10. Drug hepatotoxicity must always be considered in the differential diagnosis of late hepatic allograft dysfunction.

Replicative senescence of biliary epithelial cells precedes bile duct loss in chronic liver allograft rejection: increased expression of p21(WAF1/Cip1) as a disease marker and the influence of immunosuppressive drugs

Early chronic liver allograft rejection (CR) is characterized by distinctive cytological changes in biliary epithelial cells (BECs) that resemble cellular senescence, in vitro, and precede bile duct loss. If patients suffering from early CR are treated aggressively, the clinical and histopathological manifestations of CR can be completely reversed and bile duct loss can be prevented. We first tested whether the senescence-related p21(WAF1/Cip1) protein is increased in BECs during early CR, and whether treatment reversed the expression. The percentage of p21+ BECs and the number of p21+ BECs per portal tract is significantly increased in early CR (26 +/- 17% and 3.6 +/- 3.1) compared to BECs in normal liver allograft biopsies or those with nonspecific changes (1 +/- 1% and 0.1 +/- 0.3; P: < 0.0001 and P: < 0.02), chronic hepatitis C (2 +/- 3% and 0.7 +/- 1; P: < 0.0001 and P: < 0.04) or obstructive cholangiopathy (7 +/- 7% and 0.7 +/- 0.6; P: < 0.006 and P: = 0.04). Successful treatment of early CR is associated with a decrease in the percentage of p21+ BECs and the number of p21+ BECs per portal tract. In vitro, nuclear p21(WAF1/Cip1) expression is increased in large and multinucleated BECs, and is induced by transforming growth factor (TGF)-beta. TGF-beta1 also increases expression of TGF-beta receptor II, causes phosphorylation of SMAD-2 and nuclear translocation of p21(WAF1/Cip1), which inhibits BEC growth. Because conversion from cyclosporine to tacrolimus is an effective treatment for early CR, we next tested whether these two immunosuppressive drugs directly influenced BEC growth in vitro. The results show that cyclosporine, but not tacrolimus, stimulates BEC TGF-beta1 production, which in turn, causes BEC mito-inhibition and up-regulation of nuclear p21(WAF1/Cip1). In conclusion, expression of the senescence-related p21(WAF1/Cip1) protein is increased in BECs during early CR and decreases with successful recovery. Replicative senescence accounts for the characteristic BEC cytological alterations used for the diagnosis of early CR and lack of a proliferative response to injury. The ability of cyclosporine to inhibit the growth of damaged BECs likely accounts for the relative duct sparing properties of tacrolimus.

Fibrous obliterative lesions of veins contribute to progressive fibrosis in chronic liver allograft rejection

Fibrosis in liver allografts undergoing chronic rejection (CR) is variable and poorly understood. The temporal and spatial relationships of venous, arterial, and biliary lesions were studied to clarify their potential contributions to graft fibrosis. The severity, prevalence, and morphology of intimal lesions of vessels were analyzed and compared with the fibrosis stage. Three groups were found; group 1 (n = 5) with no hepatic vein (HV) lesions, group 2 (n = 5) with HV lesions only, and group 3 with lesions of both HV and portal veins (PV). The earliest lesion to develop, in 71% of grafts, was concentric intimal thickening of small HV. This was significantly more severe and frequent in grafts from group 3. With increasing frequency and severity of small HV sclerosis, fibrosis developed in medium/large veins. The morphology of larger vessel lesions suggested organized thrombus. Centrilobular fibrosis was significantly more severe in group 3 and developed unpredictably and sometimes rapidly. Conversely, portal fibrosis scores were significantly higher in grafts with ductular proliferation and did not correlate with venous lesions. This suggests that in CR, veno-occlusive-like lesions develop commonly in terminal hepatic venules, probably caused by immune-mediated damage. In only a proportion, with increased frequency and severity of the lesions, stasis and thrombosis in portal and larger veins occur and could result in loss of hepatic and portal venous outflow, which leads to ischemia and fibrosis. The stage of fibrosis did not correlate with foam-cell arteriopathy. A second pathway of portal fibrosis occurs in patients with longstanding biliary proliferation.

Chronic liver allograft rejection in a population treated primarily with tacrolimus as baseline immunosuppression: long-term follow-up and evaluation of features for histopathological staging

BACKGROUND

Predisposing factors, long-term occurrence, and histopathological changes associated with recovery or progression to allograft failure from chronic rejection (CR) were studied in adult patients treated primarily with tacrolimus.

METHODS

CR cases were identified using stringent criteria applied to a retrospective review of computerized clinicopathological data and slides.

RESULTS

After 1973 days median follow-up, 35 (3.3%) of 1049 primary liver allograft recipients first developed CR between 16 and 2532 (median 242) days. The most significant risk factors for CR were the number (P<0.001) and histological severity (P<0.005) of acute rejection episodes and donor age >40 years (P<0.03). Other demographic and matching parameters were not associated with CR in this cohort. Ten patients died with, but not of, CR. Eight required retransplantation because of CR at a median of 268 days. Ten resolved either histologically or by normalization of liver injury tests over a median of 548 days. CR persisted for 340 to 2116 days in the remaining seven patients. More extensive bile duct loss (P<0.01), smallarterial loss (P<0.03), foam cell clusters (P<0.01) and higher total bilirubin (P<0.02) and aspartate aminotransferase (P<0.03) were associated with allograft failure from CR.

CONCLUSIONS

Early chronic liver allograft rejection is potentially reversible and a combination of histological, clinical, and laboratory data can be used to stage CR. Unique immunological and regenerative properties of liver allografts, which lead to a low incidence and reversibility of early CR, can provide insights into transplantation biology.