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

Rejection in Liver Transplantation Recipients

Rejection following liver transplantation continues to impact transplant recipients although rates have decreased over time with advances in immunosuppression management. The diagnosis of rejection remains challenging with liver biopsy remaining the reference standard for diagnosis. Proper classification of rejection type and severity is imperative as this guides management and ultimately graft preservation. Future areas of promise include non-invasive testing for detection of rejection to reduce the morbidity associated with invasive testing and further advances in immunosuppression management to reduce toxicities associated with immunosuppression while minimizing rejection related morbidity.

Banff 2022 Liver Group Meeting report: Monitoring long-term allograft health

The Banff Working Group on Liver Allograft Pathology met in September 2022. Participants included hepatologists, surgeons, pathologists, immunologists, and histocompatibility specialists. Presentations and discussions focused on the evaluation of long-term allograft health, including noninvasive and tissue monitoring, immunosuppression optimization, and long-term structural changes. Potential revision of the rejection classification scheme to better accommodate and communicate late T cell-mediated rejection patterns and related structural changes, such as nodular regenerative hyperplasia, were discussed. Improved stratification of long-term maintenance immunosuppression to match the heterogeneity of patient settings will be central to improving long-term patient survival. Such personalized therapeutics are in turn contingent on a better understanding and monitoring of allograft status within a rational decision-making approach, likely to be facilitated in implementation with emerging decision-support tools. Proposed revisions to rejection classification emerging from the meeting include the incorporation of interface hepatitis and fibrosis staging. These will be opened to online testing, modified accordingly, and subject to consensus discussion leading up to the next Banff conference.

The incidence and risk factors of chronic rejection in acutely rejected pediatric liver transplantation

Background. Chronic graft rejection (CR) represents an increasing concern in pediatric liver transplantation (LT). Risk factors of CR in this population are uncertain. In present study, we aimed to ascertain if clinical parameters could predict the occurrence of CR in LT children.

Methods. We retrospectively analyzed the results from 47 children who had experienced acute hepatic rejection in Namazee hospital, Shiraz, Iran during 2007–2017.

Results. Out of 47 children, 22 (46.8%) and 25 (53.2%) were boys and girls respectively. Ascites, gastrointestinal bleeding, and spontaneous bacterial peritonitis were observed in 20 (44.4%), 14 (31.1%), and 4 (9.1%) respectively. Posttransplant vascular and biliary complications were observed in 3 (7%) and 4 (9.3%) cases respectively. The mean time from LT to normalization of liver enzymes was 14.2 ± 7.5 days. The mean of acute rejection episodes was 1.4 ± 0.6 (median = 1 (22, 46.8%), range of 1–3). Six (12.7%) patients experienced CR. The mean time from LT to CR was 75 ± 28.4 days. A significant association was found between CR and patients’ condition (being inpatient or outpatient) before surgery (P = 0.03). No significant relationship was found between CR and post-transplant parameters except for biliary complications (P = 0.01). Both biliary complication (RR = 33.7, 95% CI: 2.2–511, P = 0.01) and inpatient status (RR = 10.9, 95% CI: 1.1–102.5, P = 0.03) significantly increased the risk of CR.

Conclusion. Being hospitalized at the time of LT, and development of biliary complications might predict risk factors for development of CR in LT children.

Advances in Rejection Management: Prevention and Treatment

Extended survival of liver transplant recipients has brought rejection management to the forefront of liver transplant research. This article discusses T-cell-mediated rejection, antibody-mediated rejection, and chronic rejection. We focus on the prevention and then discuss treatment options. Future directions of rejection management include biomarkers of rejection, which may allow for monitoring of patients who are considered high risk for rejection and detection of rejection before there is any clinical evidence to improve graft and patient survival. With improved graft life and survival of liver transplant recipients, the new frontier of rejection management focuses on immunosuppression minimization, withdrawal, and personalization.

Chronic Antibody-Mediated Liver Rejection: More than Meets the Eye

Understanding the role of donor-specific antibodies (DSAs) in liver transplantation remains an investigative priority. Acute and chronic rejection associated with DSAs have been described. However, most transplant protocols did not consider the presence of DSAs at the moment of liver transplantation (LTx) or for the follow-up. A 65-year-old man received an ABO-compatible LTx for cirrhosis. Ten years after the LTx, he presented with a progressive elevation of liver enzymes and bilirubin. The single antigen Luminex bead assay showed the presence of DSAs against several DQ2, DQ7, and DQ8 alleles. The patient received several desensitization treatments regarding the persistence of DSAs. The anatomopathological study confirms chronic rejection. Although in this case the immunohistochemical deposits of C4d were negative, the data revealed morphological criteria of chronic graft injury and DSAs’ incompatibilities explained by structural analysis. These data support an antibody-mediated rejection (AMR). It could be reasonable to establish a protocol for human leukocyte antigen (HLA) typing of every LTx donor and recipient as well as a periodic follow-up to assess the presence of DSAs. This will make it possible to carry out studies of donor–recipient incompatibility and to confirm the existence of probable cases of AMR.

[Liver transplantation. Current aspects of pretransplantation diagnosis and rejection]

Liver transplantation is an established treatment option for patients with end-stage liver disease. The therapy management of these patients is interdisciplinary and requires pathologists to have both clinical and immunological knowledge. Continuous advances in treatment and increasing clinical experience are accompanied by the further development of pathological transplant diagnostics. This article presents and discusses the latest classification of T‑cell-mediated rejection (TCMR), antibody-mediated rejection (AMR), and aspects of pretransplant diagnostics.

Perspective review on solid-organ transplant: needs in point-of-care optical biomarkers

Solid-organ transplant is one of the most complex areas of modern medicine involving surgery. There are challenging opportunities in solid-organ transplant, specifically regarding the deficiencies in pathology workflow or gaps in pathology support, which may await alleviations or even de novo solutions, by means of point-of-care, or point-of-procedure optical biomarkers. Focusing the discussions of pathology workflow on donor liver assessment, we analyze the undermet need for intraoperative, real-time, and nondestructive assessment of the donor injuries (such as fibrosis, steatosis, and necrosis) that are the most significant predictors of post-transplant viability. We also identify an unmet need for real-time and nondestructive characterization of ischemia or irreversible injuries to the donor liver, earlier than appearing on morphological histology examined with light microscopy. Point-of-procedure laparoscopic optical biomarkers of liver injuries and tissue ischemia may also facilitate post-transplant management that is currently difficult for or devoid of pathological consultation due to lack of tools. The potential and pitfalls of point-of-procedure optical biomarkers for liver assessment are exemplified in breadth for steatosis. The more general and overarching challenges of point-of-procedure optical biomarkers for liver transplant pathology, including the shielding effect of the liver capsule that was quantitated only recently, are projected. The technological and presentational benchmarks that a candidate technology of point-of-procedure optical biomarkers for transplant pathology must demonstrate to motivate clinical translation are also foreseen.

Acute, Chronic, and Humoral Rejection: Pathologic Features Under Current Immunosuppressive Regimes

Under current immunosuppressive regimes, T-cell-mediated acute and chronic rejection remain common and important posttransplant complications. The definition of humoral (antibody-mediated) rejection has been greatly expanded in recent years. The histopathologic assessment of allograft biopsies continues to serve an important role in the diagnosis of rejection and to facilitate patient management. The diagnosis of both acute and chronic antibody-mediated rejection requires integration of the results of donor-specific antibody testing and C4d immunostaining, as well as exclusion of other potential etiologies of allograft dysfunction. Chronic antibody-mediated rejection should also be included in the differential diagnosis for unexplained allograft fibrosis.

The beneficial role of simultaneous splenectomy after extended hepatectomy: experimental study in pigs

BACKGROUND

The role of hepatic hemodynamic modulation in the development of "small-for-size" syndrome (SFSS) after extended hepatectomy (EH) or living-donor liver transplantation is still controversial. We have designed an experimental study to investigate the effect of hemodynamic parameters of the liver circulation on the development of SFSS after EH in a porcine model.

METHODS

Eighteen pigs were randomly divided into two groups: group A has received EH (75%-80%) without splenectomy, and group B with EH and simultaneous splenectomy was carried out. Portal hemodynamics, liver function tests, histologic findings, injury and survival rates were compared between groups A and B.

RESULTS

The 7-d survival rate in the splenectomy group was significantly improved compared with group A (88.9% versus 44.4%, P < 0.05). Portal vein pressure, portal vein flow, and liver function tests in the splenectomy group were significantly lower than in group A immediately after splenectomy and postoperatively until the day of sacrifice. Histologic findings in group A clearly illustrate severe inflammation, bridging necrosis, ischemic cholangitis, and severe congestion, while in group B there were less serious histologic changes.

CONCLUSIONS

Our experimental study indicates that perioperative portal modulation can successfully prevent the manifestation of SFSS after EH. Therefore, by focusing on "flow" rather than on "size," researchers may understand better the pathophysiology of this syndrome.

Early Predictors of Long-term Outcomes of HCV-negative Liver Transplant Recipients Having Survived the First Postoperative Year

BACKGROUND

The non-improvement in >1-year post-liver transplant (LT) survival and diminishing importance of hepatitis C (HCV) with modern antivirals justify identification of early factors predictive of long-term outcome post-LT in HCV-negative recipients.

METHODS

This nationwide study included all 631 HCV-negative adult patients transplanted in Finland 1982-2013 with at least 1-year graft survival (6311 person-year follow-up). We tested 37 variables, including immunosuppression, for their association with >1-year combined graft loss/mortality, late rejection, cancer, or infections.

RESULTS

Significant multivariate predictors of graft loss/mortality were male gender (HR 2.40, P = 0.001), pretransplant hepatocellular (HR 2.92, P = 0.001) or biliary cancer (HR 12.7, P < 0.001), glomerular filtration rate (HR 0.89, P = 0.002), hypertension (HR 0.44, P < 0.001), early posttransplant infections (HR 1.52-1.67, P = 0.007-0.03), and alkaline phosphatase (ALP) (HR 1.05, P < 0.001). Elevated ALP at 1 year, affecting 30% of patients, predicted both graft loss and rejection, independent of immunologic stability, etiology, and immunosuppression type. Area under the curve of ALP in predicting graft loss from rejection was 0.81 (95% CI 0.71-0.90) and 0.85 (95% CI 0.72-0.98, P = 0.001) among patients under 50. Among immunologically stable patients who underwent transplantation after 2000, antimetabolite use at 1 year was associated with improved survival (P = 0.04), specifically in the subgroup with native-liver hepatocellular or biliary cancer (P = 0.02).

CONCLUSIONS

Easily measurable, widely available, and noninvasive factors known at 1 year post-LT can help stratify patients according to their long-term risk of death or graft loss, and thus facilitate a personalization of long-term follow-up. ALP deserves routine monitoring, and the cause for an elevated ALP should be sought.

Prognostic factors for the evolution and reversibility of chronic rejection in pediatric liver transplantation

OBJECTIVE

Chronic rejection remains a major cause of graft failure with indication for re-transplantation. The incidence of chronic rejection remains high in the pediatric population. Although several risk factors have been implicated in adults, the prognostic factors for the evolution and reversibility of chronic rejection in pediatric liver transplantation are not known. Hence, the current study aimed to determine the factors involved in the progression or reversibility of pediatric chronic rejection by evaluating a series of chronic rejection cases following liver transplantation.

METHODS

Chronic rejection cases were identified by performing liver biopsies on patients based on clinical suspicion. Treatment included maintaining high levels of tacrolimus and the introduction of mofetil mycophenolate. The children were divided into 2 groups: those with favorable outcomes and those with adverse outcomes. Multivariate analysis was performed to identify potential risk factors in these groups.

RESULTS

Among 537 children subjected to liver transplantation, chronic rejection occurred in 29 patients (5.4%). In 10 patients (10/29, 34.5%), remission of chronic rejection was achieved with immunosuppression (favorable outcomes group). In the remaining 19 patients (19/29, 65.5%), rejection could not be controlled (adverse outcomes group) and resulted in re-transplantation (7 patients, 24.1%) or death (12 patients, 41.4%). Statistical analysis showed that the presence of ductopenia was associated with worse outcomes (risk ratio=2.08, p=0.01).

CONCLUSION

The presence of ductopenia is associated with poor prognosis in pediatric patients with chronic graft rejection.

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.

A proteomic analysis of transplanted liver in a rat model of chronic rejection

BACKGROUND

Chronic rejection (CR) is an important cause of liver allograft failure. In the latter condition, re-transplantation of the liver (ReLT) is the only option for survival. Unfortunately, with the current state of knowledge, it is difficult to diagnose and treat early CR.

OBJECTIVE

To explore the biomarkers of the chronic rejection in orthotopic liver transplantation (OLT).

METHODS

A rat model of chronic liver allograft rejection was established, and the differential protein expression in chronic allograft rejection (CR) was analyzed by iTRAQ-MALDI-TOF/TOF.

RESULTS

Expression of sixty-two proteins was found to be significantly changed in CR rats. In the present study, CLU, Lcn2 and Krt19 were identified and quantified as early and reliable biomarkers for chronic rejection.

CONCLUSION

Analysis of differential protein expression by iTRAQ-MALDI-TOF/TOF is a potentially effective method to help understand the mechanism of CR in orthotopic liver transplantation. The proteins CLU, Lcn2 and Krt19 might be potential prognostic markers for predicting chronic rejection after liver transplantation.

Pretransplant replacement of donor liver grafts with recipient Kupffer cells attenuates liver graft rejection in rats

BACKGROUND AND AIM

Rejection of liver grafts is a difficult issue that has not been resolved. Preoperative replacement of liver cells in the graft with cells from the intended recipient may attenuate rejection. We investigated whether preoperative transplant of recipient bone marrow cells (BMCs) to the donor replaced liver allograft cells and attenuated rejection.

METHODS

We used a rat model of allogeneic liver transplant (LT) from Dark Agouti (DA) to Lewis (LEW) rats. In BMC group, DA rats received BMC transplants from LacZ-transgenic LEW rats at 1 week before LT. In the control group, DA rats received no preoperative treatment. We evaluated graft damage at 7 days after LT and the survival of the recipient rats.

RESULTS

Rats in the BMC group experienced prolonged survival that was abrogated by the administration of gadolinium chloride to donors at 24 h before LT. Serum concentrations of total bilirubin and hyaluronic acid on day 7 were significantly lower in the BMC group, and histopathological analyses revealed that rejection of the liver graft was attenuated. X-gal staining and immunohistostaining of the liver graft revealed that BMCs engrafted in the sinusoidal space differentiated into Kupffer cells.

CONCLUSIONS

Preoperative transplant of recipient BMCs to LT donors replaced donor Kupffer cells and attenuated post-LT rejection, indicating that this strategy may increase the success of LT.

Gut-liver axis improves with meloxicam treatment after cirrhotic liver resection

AIM: To investigate the effect of meloxicam on the gut-liver axis after cirrhotic liver resection.

METHODS: Forty-four male Wistar rats were assigned to three groups: (1) control group (CG); (2) bile duct ligation with meloxicam treatment (BDL + M); and (3) bile duct ligation without meloxicam treatment (BDL). Secondary biliary liver cirrhosis was induced via ligature of the bile duct in the BDL + M and BDL groups. After 2 wk, the animals underwent a 50% hepatectomy. In the BDL + M group 15 min prior to the hepatectomy, one single dose of meloxicam was administered. Parameters measured included: microcirculation of the liver and small bowel; portal venous flow (PVF); gastrointestinal (GI) transit; alanine aminotransferase (ALT); malondialdehyde; interleukin 6 (IL-6), transforming growth factor beta 1 (TGF-β1) and hypoxia-inducible factor 1 alpha (HIF-1α) levels; mRNA expression of cyclooxigenase-2 (COX-2), IL-6 and TGF-β1; liver and small bowel histology; immunohistochemical evaluation of hepatocyte and enterocyte proliferation with Ki-67 and COX-2 liver expression.

RESULTS: Proliferative activity of hepatocytes after liver resection, liver flow and PVF were significantly higher in CG vs BDL + M and CG vs BDL group (P < 0.05), whereas one single dose of meloxicam ameliorated liver flow and proliferative activity of hepatocytes in BDL + M vs BDL group. COX-2 liver expression at 24 h observation time (OT), IL-6 concentration and mRNA IL-6 expression in the liver especially at 3 h OT, were significantly higher in BDL group when compared with the BDL + M and CG groups (P < 0.01, P < 0.001, P < 0.01, respectively). Liver and small bowel histology, according to a semi quantitative scoring system, showed better integrity in BDL + M and CG as compared to BDL group. ALT release and HIF-1α levels at 1 h OT were significantly higher in BDL + M compared to CG and BDL group (P < 0.001 and P < 0.01, respectively). Moreover, ALT release levels at 3 and 24 h OT were significantly higher in BDL group compared to CG, P < 0.01. GI transit, enterocyte proliferative activity and number of goblet cells were in favor of meloxicam treatment vs BDL group (P < 0.05, P < 0.001, P < 0.01, respectively). Additionally, villus length were higher in BDL + M as compared to BDL group.

CONCLUSION: One single dose of meloxicam administered after cirrhotic liver resection was able to cause better function and integrity of the remaining liver and small bowel.

Assessment of chronic rejection in liver graft recipients receiving immunosuppression with low-dose calcineurin inhibitors

BACKGROUND & AIMS

Calcineurin inhibitors represent the cornerstone immunosuppressants after liver transplantation despite their side effects. As liver graft is particularly well tolerated, low doses may be proposed. The aim of this study was to assess the prevalence of chronic rejection in patients with low calcineurin inhibitors regimen and to compare their characteristics with patients under standard doses.

METHODS

All patients with liver transplantation between 1997 and 2004 were divided into two groups. Low-dose patients (n=57) had tacrolimus baseline levels <5ng/ml or cyclosporine levels <50ng/ml at t0 or <100ng/ml at t+2h and were prospectively proposed a liver biopsy, searching for chronic rejection according to Banff criteria. The remaining patients constituted the standard-doses group (n=40).

RESULTS

Among the low-dose group, 36 patients in the low-dose group were assessed by biopsy. No chronic rejection was found. Fifty-six percent had only calcineurin inhibitors and 8% received other immunosuppressants only. The median time between liver transplantation and biopsy was 90 months (64-157) and between IS regimen decrease and biopsy was 41 months (11-115). Liver tests were normal in 72% of the patients. Low-dose patients had more often hepatitis B (p=0.045), less past acute rejection episodes (p=0.028), and better renal function (p=0.040). Decrease of calcineurin inhibitors failed in 15% of standard-dose patients without impacting the graft function. In the low-dose group, co-prescription of other immunosuppressants facilitated the decrease (p=0.051).

CONCLUSIONS

The minimization, or even cessation, of calcineurin inhibitors may be an achievable goal in the long term for most of the liver graft recipients.

Liver Transplant Pathology: Review of Challenging Diagnostic Situations

Histopathologic assessment of allograft liver biopsies has an important role in managing patients who have undergone liver transplantation. In this review, several topics are discussed that create diagnostic problems in transplant pathology, with emphasis on pathologic features and differential diagnosis. The topics discussed are acute cellular rejection, late acute rejection (centrizonal/parenchymal rejection), chronic rejection, plasma cell hepatitis, idiopathic posttransplant chronic hepatitis, fibrosing cholestatic hepatitis, selected viral infections (cytomegalovirus, Epstein-Barr virus, and hepatitis E), and acute antibody-mediated rejection.

Prospective study on CMV-reactivations under preemptive strategy in CMV-seropositive adult liver transplant recipients

BACKGROUND

Cytomegalovirus (CMV) is a significant infectious agent after liver transplantation. To prevent CMV, most centres use prophylaxis for high-risk CMV-seronegative recipient/seropositive donor and many even for all seropositive recipients. However, pre-emptive therapy is commonly used for seropositive patients.

OBJECTIVES

A prospective, long-term follow-up of CMV-seropositive adult liver-transplant patients under pre-emptive strategy was investigated.

STUDY DESIGN

CMV-seropositive liver recipients were monitored for CMV by real-time quantitative plasma polymerase chain reaction (PCR) and received ganciclovir/valganciclovir pre-emptive therapy. The 161 patients with follow-up of >4 years were included in the study.

RESULTS

No CMV was detected in most cases 98/161 (61%), but 63/161 (39%) developed CMV-DNAaemia mean 49 days (7-183 days) after transplantation. Only 25/63 reactivations exceeded 5000 copies/ml, which was considered as cut-off for the pre-emptive treatment by the method used (median 21,500, range 5100-813300 copies/ml) and most were self-limiting, low-level DNAaemias (median 850, range 234-4000 copies/ml). Thus, low-level temporal CMV viraemia occurred in 38/161 patients (23.5%) and only 25/161 (15.5%) demonstrated significant viral loads. Recurrent CMV appeared in one patient with low-level and in 11/25 with high-level DNAaemia, only 5/11 exceeding 5000 copies/ml. CMV infections were successfully treated with ganciclovir/valganciclovir. Four patients with low and three with high DNAaemia have been retransplanted. Five patients with low and two with high DNAaemia have died subsequently. No patient or graft was lost due to CMV.

CONCLUSIONS

Most CMV-seropositive liver recipients did not develop CMV reactivation, and if reactivations occurred, most were temporal, low-level DNAaemias. Significant CMV infections were successfully treated and recurrences were rare.

Risk for immune-mediated graft dysfunction in liver transplant recipients with recurrent HCV infection treated with pegylated interferon

BACKGROUND & AIMS

Patients with recurrent hepatitis C virus infection treated with pegylated interferon (PEG) after liver transplantation can develop severe immune-mediated graft dysfunction (IGD) characterized by plasma cell hepatitis or rejection.

METHODS

We conducted a multicenter case-control study of 52 liver transplant recipients with hepatitis C to assess the incidence of, risk factors for, and outcomes of PEG-IGD. Data from each patient were compared with those from 2 matched patients who did not develop PEG-IGD (n = 104). We performed a multivariate analysis of risk factors and analyzed treatment and outcomes of graft dysfunction subtypes.

RESULTS

Overall incidence of PEG-IGD during a 10-year study period was 7.2%. Risk factors included no prior PEG therapy (odds ratio = 5.3; P < .0001), therapy with PEGα-2a (odds ratio = 4.7; P = .03), and immune features (mainly plasma cell hepatitis) on pre-PEG therapy liver biopsies (odds ratio = 3.9; P = .005). The PEG-IGD group had lower long-term patient (61.5% vs 91.3% of controls) and graft (38.5% vs 85.6% of controls) survival and higher rates of retransplantation (34.6% vs 6.7% of controls) (all, P < .0001), without increases in sustained virologic response. Variables associated with increased mortality included acute rejection as the PEG-IGD sub-type (hazard ratio [HR] = 2.4; P = .002), a high level of alkaline phosphatase at PEG initiation (HR = 1.003; P = .005), and lack of a sustained virologic response (HR = 3.3; P = .04). Variables associated with graft failure included a high level of alkaline phosphatase at PEG initiation (HR = 1.002; P = .04) and lack of a sustained virologic response (HR = 2.1; P = .04).

CONCLUSIONS

PEG-IGD has high morbidity and mortality and is not associated with increased rates of virologic response. It is important to avoid PEG therapy in liver transplant recipients with specific clinical, biochemical, and histologic risk factors for PEG-IGD.

What is the long-term outcome of the liver allograft?

With improved long-term survival following liver transplantation (LT), issues relating to the assessment of the liver allograft in long-term survivors are becoming increasingly relevant. Histological abnormalities are commonly present in late post-transplant biopsies, including protocol biopsies from patients who appear to be well with good graft function. Recurrent disease is the commonest recognised cause of abnormal graft histology, but may be modified by the effects of immunosuppression or interactions with other graft complications, resulting in complex or atypical changes. Other abnormalities seen in late post-transplant biopsies include rejection (which often has different appearances to those seen in the post-transplant period), de novo disease, "idiopathic" post-transplant hepatitis (IPTH) and nodular regenerative hyperplasia. In many cases graft dysfunction has more than one cause and liver biopsy may help to identify the predominant cause of graft damage. Problems exist with the terminology used to describe less well understood patterns of graft injury, but there is emerging evidence to suggest that late rejection, de novo autoimmune hepatitis and IPTH may all be part of an overlapping spectrum of immune-mediated injury occurring in the late post-transplant liver allograft. Careful clinico-pathological correlation is very important and the wording of the biopsy report should take into account therapeutic implications, particularly whether changes in immunosuppression may be indicated. This article will provide an overview of the main histological changes occurring in long-term survivors post-LT, focusing on areas where the assessment of late post-transplant biopsies is most relevant clinically.

Current views on rejection pathology in liver transplantation

Histological assessments continue to play an important role in the diagnosis and management of liver allograft rejection. The changes occurring in acute and chronic rejection are well recognized and liver biopsy remains the 'gold standard' for diagnosing these two conditions. Recent interest has focused on the diagnosis of late cellular rejection, which may have different histological appearances to early acute rejection and instead has features that overlap with so-called 'de novo autoimmune hepatitis' and 'idiopathic post-transplant chronic hepatitis'. There is increasing evidence to suggest that 'central perivenulitis' may be an important manifestation of late rejection, although other causes of centrilobular necro-inflammation need to be considered in the differential diagnosis. There are also important areas of overlap between rejection and recurrent hepatitis C infection and the distinction between these two conditions continues to be a problem in the assessment of liver allograft biopsies. Studies using immunohistochemical staining for C4d as a marker for antibody-mediated damage have found evidence of C4d deposition in liver allograft rejection, but the functional significance of these observations is currently uncertain. This review will focus on these difficult and controversial areas in the pathology of rejection, documenting what is currently known and identifying areas where further clarification is required.

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.

Improved preservation and microcirculation with POLYSOL after partial liver transplantation in rats

BACKGROUND

Due to the severe shortage of deceased donors, demand for living-donor liver transplantation (LDLT) has increased worldwide. Here, we compared POLYSOL, a recently developed low-viscosity preservation solution, and histidine-tryptophan-ketoglutarate (HTK) for cold storage of partial liver graft in this study.

METHODS

Partial liver transplantations with 30% of the native liver were performed in Lewis rats. The graft livers were flushed with either HTK or POLYSOL (n = 25, respectively) and stored in the respective solution for 3 h at 5°C. Graft function was evaluated regarding ischemia-reperfusion injury and regeneration at 1, 3, 24, and 168 h after reperfusion.

RESULTS

POLYSOL preservation resulted in improvement of portal venous flow (HTK versus POLYSOL; mean ± SEM: 16.8 ± 2.2 versus 21.6 ± 2.1 mL/min; P = 0.005), microcirculation (383 ± 63 versus 532 ± 64 Flux; P = 0.045), ALT (310.2 ± 56.1 versus 181.8 ± 17.0 IU/L; P = 0.0262), LDH (4052.4 ± 764.4 versus 2494.1 ± 410.0 IU/L; P = 0.0215), total bilirubin (21.6 ± 14.2 versus 4.0 ± 0.6 IU/L; P = 0.0236), malondialdehyde (100.0 ± 4.3 versus 69.2 ± 4.0 nmol/mL; P = 0.0015), as well histologic findings at 24 h. Liver regeneration was improved in POLYSOL with regards to liver weight (4.0 ± 0.2 versus 4.3 ± 0.3 g; P = 0.038) and Ki-67 labeling index (9.67 ± 2.17 versus 1.10 ± 0.14%; P < 0.0001) at 24 h with higher up-regulation of portal VEGF (31.55 ± 5.78 versus 91.94 ± 9.27 pg/mL; P = 0.0052).

CONCLUSIONS

This study showed that POLYSOL improves microcirculation and thus improves the preservation quality of partial liver transplantation.

Liver transplant pathology - messages for the non-specialist

This review, based on a presentation at the BDIAP meeting in London 2008, aims to guide histopathologists working outside transplant centres in the differential diagnosis of late post transplant liver biopsies. It focuses on the histological patterns of the late post transplant complications - autoimmune hepatitis, acute and chronic rejection, recurrent viral hepatitis, and biliary disease. Analysis of the character and distribution of inflammatory infiltrate, bile duct changes, and fibrosis by the histopathologist must then be set within the clinical context to arrive at the most appropriate diagnosis. For this reason, review of the biopsy at the transplant centre is recommended. In a broader context, the tabulation of diagnostic features in chronic inflammatory liver diseases produced by the Banff Working Group can, with the exception of rejection, usefully be applied outside the transplant setting.

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.

Platelets prevent acute liver damage after extended hepatectomy in pigs

BACKGROUND/PURPOSE

Platelets develop tissue repair and promote liver regeneration. We investigated whether platelets prevented acute liver damage after extended hepatectomy in pigs.

METHODS

Thrombocytosis was induced by the following two methods; afterwards 80% hepatectomy was performed in pigs. In the first method, the pigs received administration of thrombopoietin [TPO (+) group], and they were compared with a control group [TPO (-) group]. In the second method, the pigs received a splenectomy [Sp (+) group], and theywere compared with another control group [Sp (-) group]. Platelet counts, biochemical examination of blood, and histopathological findings of the residual liver were examined.

RESULTS

Serum aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), and total bilirubin (T-Bil) levels were significantly decreased in the thrombocytotic groups compared with the control groups in the early period after hepatectomy. In the histopathological findings, hemorrhagic necrosis with a bile plug was observed in the control groups, but this phenomenon was not observed in the thrombocytotic groups. On transmission electron microscopy, the sinusoidal endothelial lining was destroyed and detached into the sinusoidal space with enlargement of Disse's spaces in the thrombocytotic groups, but these findings were not observed in the control groups.

CONCLUSION

An increased number of platelets prevents acute liver damage after extended hepatectomy.

Incidence of liver retransplantation and its effect on patient survival

PURPOSE

The purpose of this study was to review our institutional experience with re-liver transplantation (OLT) after split and full-size OLT.

PATIENTS AND METHODS

We evaluated data corresponding to retransplanted patients over an 8-year period who underwent deceased donor OLT at our institution. Variables analyzed included indications for primary OLT, and re-OLT, the type of graft used during the initial versus re-OLT, the time from initial to re-OLT, and patient survival after re-OLT.

RESULTS

Sixty-four of 697 first OLT (9.2%) required re-OLT. Forty-nine cases were among 637 (7.6%) full-size OLT, while 15 were among 60 (25%) split OLT (P < .001). Median time to re-OLT was 8 days (range = 1-1885 days). Main indications for re-OLT were primary nonfunction/initial poor function (44%), hepatic artery thrombosis (26%), biliary complications (11%), and hepatitis C recurrence (6%). Forty-eight percent of the re-OLTs were performed within the first posttransplant week. The overall survival for these 64 patients was 55% and 48% at 1 and 3 years after the primary OLT, and 44% at both 1 and 3 years after the re-OLT, respectively.

CONCLUSIONS

The overall incidence of re-OLT remains 9%. Approximately half of all re-OLT occured within the first posttransplant week. Early retransplantation was associated with the best patient survival. Overall survival after re-OLT was about 10% to 20% lower than that after primary OLT.

[Quality and quantity in hepatopathology. Diagnostic and clinically relevant grading for non-tumourous liver diseases]

This article describes the grading and staging systems used in the clinical context for non-neoplastic liver diseases (chronic and autoimmune hepatitis, fatty liver and steatohepatitis, medicinal toxic liver damage, iron storage disease and gall duct diseases). Fibrotic parenchymal alterations can also be assessed as well as livers planned for transplantation, with respect to possible rejection reactions. The basis for the histopathological diagnostic procedure is the liver biopsy. The consistent and correct use of the histological scores is obligatory in the diagnostic assessment of non-neoplastic liver diseases. Different scores are available for the various liver diseases. These are qualitative and quantitative scores based on empiricism and the practical relevance has been effectively proven. Grading describes the inflammatory activity and staging the extent of fibrosis or structural disorders up to liver cirrhosis. In many instances staging is the histopathological criteria for the prognosis assessment and is, therefore, decisive for therapy indications and therapy initiation.

Morphological and functional heterogeneity of the mouse intrahepatic biliary epithelium

Rat and human biliary epithelium is morphologically and functionally heterogeneous. As no information exists on the heterogeneity of the murine intrahepatic biliary epithelium, and with increased usage of transgenic mouse models to study liver disease pathogenesis, we sought to evaluate the morphological, secretory, and proliferative phenotypes of small and large bile ducts and purified cholangiocytes in normal and cholestatic mouse models. For morphometry, normal and bile duct ligation (BDL) mouse livers (C57/BL6) were dissected into blocks of 2-4 microm(2), embedded in paraffin, sectioned, and stained with hematoxylin and eosin. Sizes of bile ducts and cholangiocytes were evaluated by using SigmaScan to measure the diameters of bile ducts and cholangiocytes. In small and large normal and BDL cholangiocytes, we evaluated the expression of cholangiocyte-specific markers, keratin-19 (KRT19), secretin receptor (SR), cystic fibrosis transmembrane conductance regulator (CFTR), and chloride bicarbonate anion exchanger 2 (Cl(-)/HCO(3)(-) AE2) by immunofluorescence and western blot; and intracellular cyclic adenosine 3',5'-monophosphate (cAMP) levels and chloride efflux in response to secretin (100 nM). To evaluate cholangiocyte proliferative responses after BDL, small and large cholangiocytes were isolated from BDL mice. The proliferation status was determined by analysis of the cell cycle by fluorescence-activated cell sorting, and bile duct mass was determined by the number of KRT19-positive bile ducts in liver sections. In situ morphometry established that the biliary epithelium of mice is morphologically heterogeneous, with smaller cholangiocytes lining smaller bile ducts and larger cholangiocytes lining larger ducts. Both small and large cholangiocytes express KRT19 and only large cholangiocytes from normal and BDL mice express SR, CFTR, and Cl(-)/HCO(3)(-) exchanger and respond to secretin with increased cAMP levels and chloride efflux. Following BDL, only large mouse cholangiocytes proliferate. We conclude that similar to rats, mouse intrahepatic biliary epithelium is morphologically and functionally heterogeneous. The mouse is therefore a suitable model for defining the heterogeneity of the biliary tree.

Significance of central perivenulitis in pediatric liver transplantation

Central perivenulitis (CP) encompasses dropout of zone 3 hepatocytes, red blood cell extravasation, and perivenular mononuclear inflammation. In the liver transplant setting, CP can occur in isolation or it can occur in association with portal-based disease such as acute cellular rejection (PB-ACR). Some CP is also thought to be a manifestation of chronic rejection, particularly when accompanied by zone 3 fibrosis. Prior studies of CP in pediatric liver allografts have been hampered by lack of protocol biopsies and low rates of histologic follow-up. We studied 62 consecutive liver allografts from 55 pediatric patients (age: < or =18 y) who underwent transplant from the years 1995 to 2007. Forty-nine allografts (79%) had > or =1 year of histologic follow-up, 32 (52%) > or =3 years, and 24 (39%) > or =5 years. We reviewed a total of 445 allograft biopsies (mean: 7.2 per allograft) obtained at 2 days to 11 years; 213 (48%) of these were protocol biopsies. Seven explanted livers that were removed during the course of retransplantation for graft failure in this group were also reviewed. All specimens were scored for the following features: (1) CP (mild, moderate, and severe), (2) portal ACR (mild, moderate, and severe), (3) zone 3 fibrosis (mild=perivenular or severe=bridging), and (4) ductopenia. CP was present in 120 (27%) of 445 biopsies, including 73 with CP+PB-ACR, 16 with CP within 1 month of PB-ACR, 27 with isolated CP, 3 with CP+de-novo autoimmune hepatitis, and 1 with CP+Epstein-Barr virus infection. Overall, CP was observed on at least 1 occasion in 41 (66%) allografts. It was not associated with any specific liver function test abnormality or pattern of liver function test abnormalities, it was not associated with vascular compromise as judged by Doppler ultrasound examinations, and it was not related to type of immunosuppression. CP overall was equally prevalent in the early (< or =3 mo) and late (>3 mo) post-transplant periods, but isolated CP increased in the late period. On follow-up, 6 (15%) of 41 allografts with CP developed ductopenic chronic rejection (4 requiring retransplantation) and 10 (25%) developed zone 3-based fibrosis without ductopenia (2 severe, 8 mild). In contrast, none of the 21 allografts without CP developed chronic rejection (P=0.09) and none had zone 3-based fibrosis on their last biopsy (P<0.001). All patients who developed ductopenia had 1 or more episodes of CP+PB-ACR. In contrast, isolated CP [seen in 17 (27%) allografts on at least 1 occasion] was associated with zone 3-based fibrosis in 50%, but did not lead to ductopenic chronic rejection. These results underscore the high frequency of CP in pediatric liver transplantation, occurring in 27% of all allograft biopsies and 66% of allografts overall. CP is most common in conjunction with portal ACR, where it carries a significant risk for the development of zone 3 fibrosis and a trend toward the development of ductopenic chronic rejection.

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.

Association of mast cells and liver allograft rejection

MCs are important effector cells in a broad range of immune responses. Their role in liver allograft rejection is not clear. Twenty-one liver transplant recipients (mean age +/- s.d.; 10.2 +/- 4.1 yr) who experienced a rejection episode are included in this study. Biopsy specimens from normal livers (allograft biopsy with normal histopathology n = 5 and naive livers n = 6), transplanted livers with CR (n = 5), and transplanted livers with ACR (n = 26) were studied. The total number of PT in each biopsy specimen was documented, and the number of PT that contained MCs was expressed as a percentage of the total number of PT. MCs, percentage of PT containing MCs and the average number of MCs/PT was significantly higher in rejection specimens than in control biopsy samples. All parameters were significantly higher in CR group than AR groups. Increasing grades of rejection was also associated with progressively more MCs and MC/PT (r = 0.68 p = 0.000; r = 0.58 p = 0.002). Only serum bilirubin level was related to the MCs in AR group. Only MC/PT was detected as an independent predictor of graft survival (p = 0.011, RR 2.87 95% CI 1.3-6.5). Despite the fact that the role of MCs in liver allograft rejection is still unknown; they exist in inflammatory infiltrates during pediatric liver allograft rejection. MC-rich portal infiltrates may distinguish chronic liver rejection from other inflammatory states such as AR, hepatitis and biliary obstruction.

The prevalence and natural history of untreated isolated central perivenulitis in adult allograft livers

Central perivenulitis (CP) in the allograft liver can be associated with portal-based acute cellular rejection and autoimmune hepatitis or can occur in isolation (isolated CP). Although several studies have demonstrated the significance of CP, the prevalence and natural history of untreated isolated CP have not been well studied. We examined 100 adult allograft liver recipients who had long-term follow-up, had routine protocol biopsies, and received no treatment for isolated CP. Isolated CP was identified in 28 (28%) patients. It occurred late at a mean of 658 days. Interestingly, patients with late isolated CP (defined as >3 months posttransplant) usually manifested only mildly to modestly elevated liver function tests. However, late isolated CP was associated with prior and subsequent allograft complications. Nearly all (94%) cases of late isolated CP occurred in patients who had early episodes of CP and/or acute cellular rejection. Of 13 patients who developed adverse outcomes in their allografts (zone 3 fibrosis in 10, de novo autoimmune hepatitis in 3, and ductopenia in 3), all experienced episodes of prior CP, and 12 (92%) had late CP; 1 patient required retransplant for chronic rejection, but all were alive within the last year. In summary, "transplant-associated" isolated CP occurs in 28% of adult patients, early CP is predictive of late CP, and late CP (often present as isolated CP) is associated with long-term liver injury in some patients.

Stability of cirrhotic systemic hemodynamics ensures sufficient splanchnic blood flow after living-donor liver transplantation in adult recipients with liver cirrhosis

AIM: To investigate the correlation between systemic hemodynamics and splanchnic circulation in recipients with cirrhosis undergoing living-donor liver transplantation (LDLT), and to clarify how systemic hemodynamics impact on local graft circulation after LDLT.

METHODS: Systemic hemodynamics, indocyanine green (ICG) elimination rate (K_ICG) and splanchnic circulation were simultaneously and non-invasively investigated by pulse dye densitometry (PDD) and ultrasound. Accurate estimators of optimal systemic hyperdynamics after LDLT [i.e., balance of cardiac output (CO) to blood volume (BV) and mean transit time (MTT), defined as the time required for half the administered ICG to pass through an attached PDD sensor in the first circulation] were also measured. Thirty recipients with cirrhosis were divided into two groups based on clinical outcomes corresponding to postoperative graft function.

RESULTS: Cirrhotic systemic hyperdynamics characterized by high CO, expanded BV and low total peripheral resistance (TPR) were observed before LDLT. TPR reflecting cirrhotic vascular alterations was slowly restored after LDLT in both groups. Although no significant temporal differences in TPR were detected between the two groups, CO/BV and MTT differed significantly. Recipients with good outcomes showed persistent cirrhotic systemic hyperdynamics after LDLT, whereas recipients with poor outcomes presented with unstable cirrhotic systemic hyperdynamics and severely decreased K_ICG. Systemic hyperdynamic disorders after LDLT impacted on portal venous flow but not hepatic arterial flow.

CONCLUSION: We conclude that subtle systemic hyperdynamics disorders impact on splanchnic circulation, and that an imbalance between CO and BV decreases portal venous flow, which results in critical outcomes.

FasL expression in hepatic antigen-presenting cells and phagocytosis of apoptotic T cells by FasL+ Kupffer cells are indicators of rejection activity in human liver allografts

Fas-Fas ligand (FasL) interaction and apoptosis are important in the mechanism of allograft rejection. However, the interaction between donor and recipient cells, specifically focusing on antigen-presenting cells (APCs), under various conditions is poorly understood in human liver allografts. FasL expression on APCs, its association with apoptosis, and the origin of apoptotic lymphocytes in human liver allografts were assessed by immunohistochemistry and in situ hybridization. We found increased expression of FasL on Kupffer cells (KCs) and endothelium in acute cellular rejection (n = 20) and to lesser extent in chronic rejection (n = 6) and septic cholangitis (n = 5) compared with stable grafts and normal controls. In addition, the graft specificity of infiltrating T cells was confirmed by polymerase chain reaction examination of T-cell receptor-gamma loci. T-cell apoptosis occurred at a higher rate in acute cellular rejection than in chronic rejection or septic cholangitis. The number of apoptotic bodies derived from recipient lymphocytes correlated with the severity of rejection and was reversed by treatment. FasL(+) KCs phagocytosed CD4(+) interferon-gamma(+) T cells, rather than CD4(+) interleukin-4(+) T cells, suggesting a role of KCs in regulating CD4(+) T-cell subset differentiation. In conclusion, our data suggest that FasL expression on APCs and phagocytosis of apoptotic T cells by FasL(+) KCs are indicators of rejection activity in human liver allografts.

Chronic ductopenic rejection in patients with recurrent hepatitis C virus treated with pegylated interferon alfa-2a and ribavirin

BACKGROUND

Interferon use for post liver transplantation (LT) recurrent hepatitis C (HCV) has not consistently been associated with acute cellular rejection (ACR). We examined the incidence of chronic ductopenic rejection (CR) in patients receiving pegylated interferon alfa-2a and ribavirin (PEG) to treat recurrent HCV.

METHODS

A chart review of 12 patients developing CR while receiving an escalating dose regimen of PEG with protocol liver biopsies every 6 months was conducted. Values are shown as median (range).

RESULTS

Twelve of the 70 patients treated with PEG developed CR. Median age at LT was 53 (37-63) years; immunosuppression consisted of tacrolimus or cyclosporine with prednisone. PEG was started at 3.6 (0.2-13.5) years after LT. Two patients had one episode of ACR before PEG. Four patients had first ACR while receiving PEG. CR was diagnosed after 12 (4-17) months of PEG; by then 8 patients had undetectable HCV-RNA. Tacrolimus and cyclosporine levels (ng/mL) were 7.9 (3.2-18.9) and 76 (71-93) before PEG, and 6.9 (3.7-9.7) and 130 (81-153) at CR. Six patients were treated more than 1 year with PEG; three had undetectable HCV-RNA when CR was diagnosed. Five patients are being treated for CR; one has been listed for LT; two patients were retransplanted. Five patients died as a result of sepsis partially related to CR.

CONCLUSIONS

Treatment with pegylated-interferon alpha-2a and ribavirin may trigger rapidly progressive CR in patients with therapeutic immunosuppressive trough levels, with or without first inducing ACR.

C4d immunopositivity is uncommon in ABO-compatible liver allografts, but correlates partially with lymphocytotoxic antibody status

AIMS

To determine whether C4d immunopositivity helps recognition of humoral rejection in dysfunctional liver allografts.

METHODS AND RESULTS

C4d immunopositivity was retrospectively evaluated in liver allografts. There were three staining patterns: portal venular plexus, sinusoidal and hepatocellular. The latter was related to ischaemic necrosis and not scored as positive. C4d immunopositivity was not encountered in 10 preperfusion or 15 consecutive early protocol biopsies. However, three of 12 early protocol biopsy specimens from crossmatch-positive patients were C4d+, two showing repeated positivity on at least one further biopsy specimen, while others remained negative. C4d was also positive in 2/16 early moderate acute cellular rejections, 3/14 cases of centrilobular necroinflammation, 3/11 biliary obstructions, 3/13 chronic rejections and 1/10 primary non-functional allografts.

CONCLUSION

C4d immunopositivity is uncommon in liver allografts. There is a weak positive correlation with a positive lymphocytotoxic crossmatch and some patterns of allograft dysfunction. The morphological associations resemble those reported in lymphocytotoxic crossmatch-positive patients, plus occasional sinusoidal and hepatocellular injury. Although the practical utility of C4d immunohistochemistry seems limited, it may identify a small subgroup of individuals in whom chronic humoral microvascular injury contributes to allograft dysfunction.

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.

Liver biopsy interpretation for causes of late liver allograft dysfunction

Evaluation of needle biopsies and extensive clinicopathological correlation play an important role in the determination of liver allograft dysfunction occurring more than 1 year after transplantation. Interpretation of these biopsies can be quite difficult because of the high incidence of recurrent diseases that show histopathological, clinical, and serological features that overlap with each other and with rejection. Also, more than one insult can contribute to allograft injury. In an attempt to enable centers to compare and pool results, improve therapy, and better understand pathophysiological disease mechanisms, the Banff Working Group on Liver Allograft Pathology herein proposes a set of consensus criteria for the most common and problematic causes of late liver allograft dysfunction, including late-onset acute and chronic rejection, recurrent and new-onset viral and autoimmune hepatitis, biliary strictures, and recurrent primary biliary cirrhosis and primary sclerosing cholangitis. A discussion of differential diagnosis is also presented.

Does the Banff rejection activity index predict outcome in patients with early acute cellular rejection following liver transplantation?

The Banff schema incorporates a semiquantitative scoring system for grading of acute cellular rejection (ACR) of the liver allograft. The Banff rejection activity index (RAI) comprises 3 components scored from 0 to 3: venous endothelial inflammation (E); bile duct damage (B); and portal inflammation (P); the scores are combined to an overall score (the RAI). The purpose of this research was to determine the prognostic value of the Banff RAI score in predicting the response to increased immunosuppression and the long-term outcome of the graft. A retrospective study was done of patients undergoing primary liver transplantation between January 2000 and October 2004 with tacrolimus-based immunosuppression; 495 patients were included, 231 had histologically-confirmed ACR, 193 responded to 1 cycle of high-dose steroids. There was no correlation between the total RAI score and response to steroids, resistant rejection, development of chronic rejection, or graft survival. The E score was related to patient survival, a lower score being associated with a worse outcome (P = 0.048). In multivariable analysis, serum bilirubin, serum aspartate aminotransferase, and E score were significant predictors of death (P = 0.012). In univariable analysis, B score and bilirubin were significantly related to "resistant rejection" (P = 0.018 and 0.002, respectively), but only bilirubin was significant in multivariable analysis (logistic regression). In conclusion, although the Banff RAI score is a useful marker of the severity of rejection, neither the total RAI score nor any of the individual components correlated with response to steroids or graft survival.

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.