Protocol liver allograft biopsies. Transplantation. 2008;85:1686-1692. [PMID: 18580457 DOI: 10.1097/tp.0b013e318176b1fd]

Liver transplantation immunology: Immunosuppression, rejection, and immunomodulation

Outcomes after liver transplantation have continuously improved over the past decades, but long-term survival rates are still lower than in the general population. The liver has distinct immunological functions linked to its unique anatomical configuration and to its harbouring of a large number of cells with fundamental immunological roles. The transplanted liver can modulate the immunological system of the recipient to promote tolerance, thus offering the potential for less aggressive immunosuppression. The selection and adjustment of immunosuppressive drugs should be individualised to optimally control alloreactivity while mitigating toxicities. Routine laboratory tests are not accurate enough to make a confident diagnosis of allograft rejection. Although several promising biomarkers are being investigated, none of them is sufficiently validated for routine use; hence, liver biopsy remains necessary to guide clinical decisions. Recently, there has been an exponential increase in the use of immune checkpoint inhibitors due to the unquestionable oncological benefits they provide for many patients with advanced-stage tumours. It is expected that their use will also increase in liver transplant recipients and that this might affect the incidence of allograft rejection. Currently, the evidence regarding the efficacy and safety of immune checkpoint inhibitors in liver transplant recipients is limited and cases of severe allograft rejection have been reported. In this review, we discuss the clinical relevance of alloimmune disease, the role of minimisation/withdrawal of immunosuppression, and provide practical guidance for using checkpoint inhibitors in liver transplant recipients.

Regular protocol liver biopsy is useful to adjust immunosuppressant dose after adult liver transplantation

INTRODUCTION

Adjusting immunosuppression to minimal levels post-adult liver transplantation (LT) is critical; however, graft rejection has been reported in LT recipients with normal liver function evaluated by liver biopsy (LBx). Continual protocol liver biopsy (PLB) is performed regularly in LT recipients with normal liver function in some centers; however, its usefulness remains inadequately evaluated. This study aimed to assess retrospectively the usefulness of late PLB after adult LT.

METHODS

LBx evaluations of LT recipients with normal liver function and hepatitis B and C virus seronegativity were defined as PLB. The cases requiring immunosuppressive therapy for rejection findings based on Banff criteria were extracted from the PLBs, and pathological data collected before and after immunosuppressive dosage adjustment (based on modified histological activity index [HAI] score) were compared.

RESULTS

Among 548 LBx cases, 213 LBx in 110 recipients fulfilled the inclusion criteria for PLB. Immunosuppressive therapy after PLB was intensified in 14 LBx (6.6%) recipients (12.7%); of these, nine had late-onset acute rejection, three had isolated perivenular inflammation, one had plasma cell-rich rejection, and one had early chronic rejection. Follow-up LBx after immunosuppressive dose adjustment showed improvement in the modified HAI score grading in 10 of 14 cases (71.4%). No clinical background and blood examination data, including those from the post-LT period, immunosuppressant trough level, or examination for de novo DSA, predicted rejection in PLB. Complications of PLB were found in only three cases.

CONCLUSION

PLB is useful in the management of seemingly stable LT recipients, to discover subclinical rejection and allow for appropriate immunosuppressant dose adjustment.

Clinical and financial impacts of abnormal liver biochemistry after liver transplantation

OBJECTIVE

After liver transplant (LT), many investigations are needed to evaluate abnormal liver function test (LFT), which has poor specificity for graft function and complication. A single center retrospective audit of all adult single organ LT from 1/1/2015 to 31/12/2017 was performed. Demographic, clinical and investigation data from the LT database and electronic medical records and cost data from the hospital's Business Intelligence Unit were analyzed. Patients were classified into uncomplicated or complicated LFT by 2 independent investigators and the number, type, and cost of investigations in the first 30 post-operative days were analyzed. Investigations prior to liver biopsy was sub-analyzed.

RESULTS

There was 170 LT with 87 cases of uncomplicated LFT (51.2%) and 83 cases of complicated LFT (48.8%). Most patients with complicated LFT had additional investigations (97.6%), most commonly cholangiogram (55.4%) and liver biopsy (LBx) (50.6%). The additional investigations cost was $1863.3 (95% CI 1289.0-2437.6). Although most LBx (73.8%) showed evidence of rejection, LBx was often not the initial investigation of choice. Current LFT based post-transplant monitoring is inefficient. It remains difficult to determine which patient will benefit from an early invasive procedure like LBx, using LFT alone without further imaging investigations.

Prediction of long-term morbidity and mortality after liver transplantation using two-dimensional shear wave elastography compared with liver biopsy

The role of noninvasive liver disease assessment by two-dimensional shear wave elastography (2D-SWE) to diagnose fibrosis is well described in patients with chronic liver disease. However, its role in prognosis, especially after liver transplantation (LT) has not been adequately examined. We hypothesized that elevated liver stiffness measurement (LSM) as measured by 2D-SWE after LT predicts future morbidity and mortality independent of fibrosis by liver biopsy. In a prospective cohort study, consecutive LT recipients underwent concomitant protocol 2D-SWE and protocol liver biopsy (2012-2014), with the assessor blinded to biopsy findings. We examined the baseline correlation of LSM with fibrosis stage and the association between elevated LSM and the development of subsequent clinical outcomes and all-cause mortality. A total of 187 LT recipients (median age 58 years, 38.5% women, median body mass index 26.5 kg/m² , 55.1% hepatitis C virus, 17.6% nonalcoholic steatohepatitis/cryptogenic) were examined. Median time between LT and biopsy/2D-SWE assessment was 4.0 years, and the median follow-up time after LSM determination was 3.5 years. Median LSM was 9 kPa (8 kPa [F0/F1], 11.5 kPa [F2], 12 kPa [F3/F4]). There was a positive correlation between LSM and fibrosis stage (r_s  = 0.41; p < 0.001). LSM ≥11 kPa was associated with lower survival within 3 years (84.8 vs. 93.7%; p = 0.04). After adjusting for age, sex, and fibrosis stage, LSM ≥11 kPa was independently associated with mortality (hazard ratio, 2.45; 95% confidence interval, 1.08-5.60). Elevated LSM by 2D-SWE is associated with increased mortality after LT independent of hepatic fibrosis. Given the overall decrease in the use of liver biopsy in the current era, 2D-SWE may serve as a novel noninvasive prognostic tool to predict relevant outcomes late after LT.

Outcome and safety of a surveillance biopsy guided personalized immunosuppression program after liver transplantation

Graft survival beyond year 1 has not changed after orthotopic liver transplantation (OLT) over the last decades. Likewise, OLT causes comorbidities such as infection, renal impairment and cancer. We evaluated our single-center real-world individualized immunosuppression program after OLT, based on 211 baseline surveillance biopsies (svLbx) without any procedural complications. Patients were classified as low, intermediate and high rejection risk based on graft injury in svLbx and anti-HLA donor-specific antibodies. While 32% of patients had minimal histological inflammation, 57% showed histological inflammation and 23% advanced fibrosis (>F2), which was not predicted by lab parameters. IS was modified in 79% of patients after svLbx. After immunosuppression reduction in 69 patients, only 5 patients showed ALT elevations and three of these patients had a biopsy-proven acute rejection, two of them related to lethal comorbidities. The rate of liver enzyme elevation including rejection was not significantly increased compared to a svLbx control cohort prior to the initiation of our structured program. Immunosuppression reduction led to significantly better kidney function compared to this control cohort. In conclusion, a biopsy guided personalized immunosuppression protocol after OLT can identify patients requiring lower immunosuppression or patients with graft injury in which IS should not be further reduced.

Value of posttransplant protocol biopsies in 2 biliary autoimmune liver diseases: A step toward personalized immunosuppressive treatment

The value of protocol liver graft biopsies with good liver function was evaluated in patients with primary sclerosing cholangitis (PSC) or primary biliary cholangitis (PBC).A total of 250 protocol liver biopsy reports from 182 PSC and PBC patients were compared. Overall histopathological findings and those leading to changes in immunosuppression therapy were retrospectively analyzed.The mean time to first protocol biopsy after transplantation was 5.5 (±4.5) years for PSC patients and 9.3 (±6.6) years for PBC patients. More than 1 abnormal histopathological parameter was found in 43% and 62% of PSC and PBC patients, respectively. However, the histology was interpreted as normal by the pathologist in 78% of PSC and 60% of PBC patients. Immunosuppression therapy was reduced in 10% and increased in 6% patients due to protocol biopsy findings. Biopsies leading to increased immunosuppression therapy had more portal (P = .004), endothelial (P = .008), interphase (P = .021), and lobular (P = .000) inflammation.Mild histopathological findings were frequently found in the protocol biopsies despite the normal biochemistry. PBC patients had more histological abnormalities than those transplanted due to PSC; however, PBC patients had longer follow-up times. Immunosuppression therapy could be safely increased or decreased according to protocol biopsy findings after multidisciplinary meeting discussions.

The Need for Alternatives to Liver Biopsies: Non-Invasive Analytics and Diagnostics

Histology remains essential for the diagnosis and management of many disorders affecting the liver. However, the biopsy procedure itself is associated with a low risk of harm to the patient and cost to the health services; samples may not be adequate and are subject to sampling variation. Furthermore, interpretation often depends on the skill of the pathologist. Increasingly, new techniques are becoming available that are altering the indications for liver biopsy. Many diseases of the liver can be diagnosed and managed using serological and radiological techniques; the degree of fibrosis and fat can often be assessed by serological or imaging techniques and the nature of space occupying lesions defined by serology, imaging and use of liquid biopsy. However, these techniques, too, are subject to limitations: sensitivity and specificity is not always adequate for diagnosis or management; some techniques are expensive and often also require expert interpretation. Although there may be less need for liver biopsy today, histology remains the gold standard as well as an essential tool for the diagnosis and management of many conditions, especially where there are multiple pathologies, or where a diagnosis cannot or has not been made by alternative approaches. Until less invasive techniques become more reliable and accessible, liver histology will remain a key investigation.

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.

Evaluation of Graft Fibrosis, Inflammation and Donor-specific Antibodies at Protocol Liver Biopsies in Pediatric Liver Transplant Patients: a Single Center Experience

BACKGROUND

The impact of graft fibrosis and inflammation on the natural history of pediatric liver transplants (LT) is still debated. Our objectives were to evaluate the evolution of posttransplant fibrosis and inflammation over time at protocol liver biopsies (PLBs), risk factors for fibrosis, presence of donor-specific antibodies (DSAs) and/or their correlation with graft and recipient factors.

METHODS

A single-center, retrospective (2000-2019) cross-sectional study on pediatric LT recipients who had at least one PLB, followed by a longitudinal evaluation in those who had at least two PLBs, was conducted. Fibrosis was assessed by the Liver Allograft Fibrosis Semiquantitative score, inflammation by the Rejection Activity Index, DSAs by Luminex®.

RESULTS

A total of 134 PLBs from 94 patients were included. Fibrosis was detected in 87% (30% mild, 45% moderate, 12% severe), 80% in the portal tracts. There was an increase in fibrosis between the 1-3 and the 4-6 year group (p=0.01), then it was stable. Inflammation was observed in 44% (30% mild, 13% moderate, 1% severe), 90% in the portal tracts. Anti-HLA II (IgG) DSAs were detected in 14/40 (35%). Portal fibrosis was associated with portal inflammation in the 1-3 year group (p=0.04). Low immunosuppression levels were correlated with sinusoidal fibrosis (p=0.04) and DSA positivity (p-value=0.006). There was no statistically significant correlation between DSA positivity and the presence of graft fibrosis or inflammation.

CONCLUSIONS

This study corroborates the concept of an early evolution of silent graft fibrosis. Suboptimal immunosuppression may play a role in the development of fibrosis and DSAs.

Responsive Trimodal Probes for In Vivo Imaging of Liver Inflammation by Coassembly and GSH-Driven Disassembly

Noninvasive in vivo imaging of hepatic glutathione (GSH) levels is essential to early diagnosis and prognosis of acute hepatitis. Although GSH-responsive fluorescence imaging probes have been reported for evaluation of hepatitis conditions, the low penetration depth of light in liver tissue has impeded reliable GSH visualization in the human liver. We present a liver-targeted and GSH-responsive trimodal probe (GdNPs-Gal) for rapid evaluation of lipopolysaccharide- (LPS-) induced acute liver inflammation via noninvasive, real-time in vivo imaging of hepatic GSH depletion. GdNPs-Gal are formed by molecular coassembly of a GSH-responsive Gd(III)-based MRI probe (1-Gd) and a liver-targeted probe (1-Gal) at a mole ratio of 5/1 (1-Gd/1-Gal), which shows high r ₁ relaxivity with low fluorescence and fluorine magnetic resonance spectroscopic (¹⁹F-MRS) signals. Upon interaction with GSH, 1-Gd and 1-Gal are cleaved and GdNPs-Gal rapidly disassemble into small molecules 2-Gd, 2-Gal, and 3, producing a substantial decline in r ₁ relaxivity with compensatory enhancements in fluorescence and ¹⁹F-MRS. By combining in vivo magnetic resonance imaging (¹H-MRI) with ex vivo fluorescence imaging and ¹⁹F-MRS analysis, GdNPs-Gal efficiently detect hepatic GSH using three independent modalities. We noninvasively visualized LPS-induced liver inflammation and longitudinally monitored its remediation in mice after treatment with an anti-inflammatory drug, dexamethasone (DEX). Findings highlight the potential of GdNPs-Gal for in vivo imaging of liver inflammation by integrating molecular coassembly with GSH-driven disassembly, which can be applied to other responsive molecular probes for improved in vivo imaging.

Enhancing the Value of Histopathological Assessment of Allograft Biopsy Monitoring

Traditional histopathological allograft biopsy evaluation provides, within hours, diagnoses, prognostic information, and mechanistic insights into disease processes. However, proponents of an array of alternative monitoring platforms, broadly classified as "invasive" or "noninvasive" depending on whether allograft tissue is needed, question the value proposition of tissue histopathology. The authors explore the pros and cons of current analytical methods relative to the value of traditional and illustrate advancements of next-generation histopathological evaluation of tissue biopsies. We describe the continuing value of traditional histopathological tissue assessment and "next-generation pathology (NGP)," broadly defined as staining/labeling techniques coupled with digital imaging and automated image analysis. Noninvasive imaging and fluid (blood and urine) analyses promote low-risk, global organ assessment, and "molecular" data output, respectively; invasive alternatives promote objective, "mechanistic" insights by creating gene lists with variably increased/decreased expression compared with steady state/baseline. Proponents of alternative approaches contrast their preferred methods with traditional histopathology and: (1) fail to cite the main value of traditional and NGP-retention of spatial and inferred temporal context available for innumerable objective analyses and (2) belie an unfamiliarity with the impact of advances in imaging and software-guided analytics on emerging histopathology practices. Illustrative NGP examples demonstrate the value of multidimensional data that preserve tissue-based spatial and temporal contexts. We outline a path forward for clinical NGP implementation where "software-assisted sign-out" will enable pathologists to conduct objective analyses that can be incorporated into their final reports and improve patient care.

Transient elastography for non-invasive evaluation of post-transplant liver graft fibrosis in children

As graft survival in pediatric LT is often affected by progressive fibrosis, numerous centers carry out protocol liver biopsies. Follow-up biopsy protocols differ from center to center, but all biopsies are progressively spaced out, as time from transplant increases. Therefore, there is a need for non-invasive techniques to evaluate graft fibrosis progression in those children who have no clinical or serological signs of liver damage. Indirect markers, such as the APRI, should be relied on with caution because their sensitivity in predicting fibrosis can be strongly influenced by the etiology of liver disease, severity of fibrosis, and patient age. A valid alternative could be TE, a non-invasive technique already validated in adults, which estimates the stiffness of the cylindrical volume of liver tissue, 100-fold the size of a standard needle biopsy sample. The aims of this study were to evaluate the reliability of TE in children after LT and to compare both the TE and the APRI index results with the histological scores of fibrosis on liver biopsies. A total of 36 pediatric LT recipients were studied. All patients underwent both TE and biopsy within a year (median interval -0.012 months) at an interval from LT of 0.36 to 19.47 years (median 3.02 years). Fibrosis was assessed on the biopsy specimens at histology and staged according to METAVIR. There was a statistically significant correlation between TE stiffness values and METAVIR scores (P = .005). The diagnostic accuracy of TE for the diagnosis of significant fibrosis (F ≥ 2) was measured as the area under the curve (AUROC = 0.865), and it demonstrated that the method had a good diagnostic performance. APRI was not so accurate in assessing graft fibrosis when compared to METAVIR (AUROC = 0.592). A liver stiffness cutoff value of 5.6 kPa at TE was identified as the best predictor for a significant graft fibrosis (METAVIR F ≥ 2) on liver biopsy, with a 75% sensitivity, a 95.8% specificity, a 90% positive predictive value, and an 88.5% negative predictive value. These data suggest that TE may represent a non-invasive, reliable tool for the assessment of graft fibrosis in the follow-up of LT children, alerting the clinicians to the indication for a liver biopsy, with the aim of reducing the number of protocol liver biopsies.

Tolerance after liver transplantation: Where are we?

Impeccable management of immunosuppression is required to ensure the best longterm outcomes for liver transplant recipients. This is particularly challenging for children who arguably need 8 decades of graft and patient survival. Too little risks chronic, often subclinical allo-immune injury while too much risks insidious and cumulative toxicities. Historically, immunosuppression minimization or withdrawal has been a strategy to optimize the longevity of liver transplant recipients. The literature is sprinkled with single-center reports of operationally tolerant patients - those with apparently normal liver function and liver tests. However, without biopsy evidence of immunological quiescence, confidence in the phenotypic assignment of tolerance is shaky. More recently, multicenter trials of immunosuppression withdrawal for highly selected, stable, longterm adult and pediatric liver recipients have shown tolerance rates, based on both biochemical and histological assessment, of 40% and 60%, respectively. Extended biochemical and histologic follow-up of children over 8 years, equivalent to 7+ years off of drug, suggests that operational tolerance is robust. Therefore, clearly, immunosuppression can be completely and safety withdrawn from highly-selected subsets of adults and children. However, these trials have also confirmed that clinically ideal recipients - those eligible for immunosuppression withdrawal trial - can harbor significant and worrisome inflammation and/or fibrosis. Although the etiology and prognosis of these findings remain unknown, it is reasonable to surmise that they may reflect an anti-donor immune response that is insufficiently controlled. To achieve the outcomes that we are seeking and that our patients are demanding, we desperately need noninvasive but accurate biomarkers that identify whether immunosuppression is neither too much nor too little but "just right." Until these are available, liver histology remains the gold standard to assess allograft health and guide immunosuppression management. Liver Transplantation 23 1601-1614 2017 AASLD.

Serum aspartate aminotransferase levels and previous histopathological findings enable reduction of protocol liver biopsies after liver transplantation for hepatitis C

BACKGROUND

Hepatitis C virus (HCV) infection remains the leading indication for liver transplantation (LT) worldwide. Recurrent hepatitis C following LT is universal, and significant fibrosis (SF, Metavir fibrosis stage ≥2) apparent on protocol biopsy typically prompts antiviral therapy.

OBJECTIVE

To determine the optimal timing of protocol liver biopsies in this setting.

METHODS

A total of 151 patients who underwent LT related to HCV infection between July 2004 and December 2009 were analyzed retrospectively. Data regarding protocol liver biopsies at six, 12 and 24 months post-LT, conventional laboratory parameters and demographic information were obtained.

RESULTS

The 151 patients included in the present study had significantly lower serum aspartate aminotransferase (AST) levels than the four patients who progressed to receive antiviral treatment for SF before six months post-LT (P<0.001). AST level, but not alanine aminotransferase level, histological activity or fibrosis stage at the six-month biopsy was independently associated with the progression to SF at 12 months (P<0.05). However, AST level, histological activity and fibrosis stage at the 12-month biopsy emerged as independent parameters associated with progression to SF at 24 months (P<0.05).

CONCLUSION

The protocol liver biopsy at six months could be eliminated, especially in patients who consistently exhibit low AST levels. Histological activity, the presence or absence of fibrosis, and AST values at the 12-month biopsy may lead to the decision to defer the protocol biopsy at 24 months or result in earlier introduction of antiviral therapy.

Living donor liver transplantation for non-alcoholic steatohepatitis: A single center experience

AIM

The number of patients referred for liver transplantation (LT) with non-alcoholic steatohepatitis (NASH) continues to increase, but information about living donor liver transplantation (LDLT) for NASH is scarce. We conducted this study to document the details of LDLT for NASH in a Japanese LT center.

METHODS

Among all LDLT recipients in our institution from March 1996 to March 2013 (n = 425), we identified seven patients that underwent LDLT for NASH.

RESULTS

Of all the seven recipients, most of the patients (86%) were obese. The median follow-up period post-LDLT was 5.3 years. All were alive at the last follow-up. Recurrent NASH was detected in one patient (14%), and no recurrent hepatic steatosis was detected among the remaining six recipients on prospectively performed ultrasonography. No significant comorbidities were observed following donor surgery among the respective living donors during the follow-up period. We also retrospectively reviewed 22 patients with NASH-related end-stage liver disease (ESLD) who were evaluated but rejected for LDLT during the same period. The reasons for rejection for LDLT were presumably associated with the nature of NAFLD/NASH in either potential recipients or donors.

CONCLUSION

The post-transplant outcome of LDLT for NASH-related ESLD in our institution was feasible, although the sample size was small. Further studies in a larger patient cohort are warranted to investigate the long-term outcome of LDLT for NASH, both for recipients and living donors.

Protocol liver biopsy is the only examination that can detect mid-term graft fibrosis after pediatric liver transplantation

AIM: To assessed the clinical significance of protocol liver biopsy (PLB) in pediatric liver transplantation (LT).

METHODS: Between July 2008 and August 2012, 89 and 55 PLBs were performed in pediatric patients at two and five years after LT, respectively. We assessed the histopathological findings using the Metavir scoring system, including activity (A) and fibrosis (F), and we identified factors associated with scores of ≥ A1 and ≥ F1. Our results clarified the timing and effectiveness of PLB.

RESULTS: The incidences of scores of ≥ A1 and ≥ F1 were 24.7% and 24.7%, respectively, at two years after LT and 42.3% and 34.5%, respectively, at five years. Independent risk factors in a multivariate analysis of a score of ≥ A1 at two years included ≥ 2 h of cold ischemic time, no acute cellular rejection and an alanine amino transaminase (ALT) level of ≥ 20 IU/L (P = 0.028, P = 0.033 and P = 0.012, respectively); however, no risk factors were identified for a score of ≥ F1. Furthermore, no independent risk factors associated with scores of ≥ A1 and ≥ F1 at five years were identified using multivariate analysis. A ROC curve analysis of ALT at two years for a score of ≥ A1 demonstrated the recommended cutoff value for diagnosing ≥ A1 histology to be 20 IU/L. The incidence of scores of ≥ A2 or ≥ F2 at two years after LT was 3.4% (three cases), and all patients had an absolute score of ≥ A2. In contrast to that observed for PLBs at five years after LT, the incidence of scores of ≥ A2 or ≥ F2 was 20.0% (11 cases), and all patients had an absolute score of ≥ F2. In all cases, the dose of immunosuppressants was increased after the PLB, and all ten patients who underwent a follow-up liver biopsy improved to scores of ≤ A1 or F1.

CONCLUSION: PLB at two years after LT is an unnecessary examination, because the serum ALT level reflects portal inflammation. In addition, immunosuppressive therapy should be modulated to maintain the ALT concentration at a level less than 20 IU/L. PLB at five years is an excellent examination for the detection of early reversible graft fibrosis because no serum markers reflect this finding.

Histopathological evaluation of recurrent hepatitis C after liver transplantation: A review

Although the morphological features of hepatitis C virus (HCV) recurrence after orthotopic liver transplantation (OLT) have been well established in the last decades, the differential diagnosis still represents a challenge for the pathologist, especially early recurrent hepatitis C vs mild acute cellular rejection. The present review focuses on the role of the pathologist and the pathology laboratory in the management of recipients with recurrent hepatitis C, the usefulness of early and late post-OLT liver biopsies, and the potential role of ancillary techniques (immunohistochemistry and reverse transcription-polymerase chain reaction, RT-PCR). The English literature on the topic is reviewed, focusing on the histopathology, the immunohistochemistry and the use of RT-PCR on HCV-positive post-OLT biopsies. The different histopathological illustrations of early and chronic recurrent hepatitis C are presented, with special focus on the main differential diagnoses and those features with prognostic relevance (cholestasis above all). The usefulness of ancillary techniques are discussed, especially HCV RNA quantitation by RT-PCR. Finally, the usefulness of long-term protocol biopsies is addressed: their usefulness for the study of allograft disease progression is clear, but their meaning in the long term is still debated. The significance of plasma cell infiltrate in HCV-positive allografts, the prognostic weight of graft steatosis, and the impact of donor age in recurrent hepatitis C also represent additional open issues.

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.

Progression of liver fibrosis in post-transplant hepatitis C: mechanisms, assessment and treatment

Liver fibrosis results from an excessive wound healing response in most chronic liver diseases, such as hepatitis C. Despite great advances in antiviral therapy in recent years, progressive liver fibrosis remains a major problem for patients with recurrent hepatitis C after liver transplantation. Liver biopsy remains a central tool in the management of HCV-positive liver transplant recipients, but reliable non-invasive methods for the assessment of liver fibrosis, such as ultrasound elastography, are increasingly being incorporated in the management of post-transplant patients, helping predict prognosis, guide treatment decisions, and stratify patients for emerging antifibrotic therapies. In this manuscript, we will review the natural history as well as tools to monitor fibrosis progression in the HCV-positive liver transplant recipient, the mechanisms underlying rapid fibrosis progression in up to 30% of these patients, the effect of antiviral therapies and highlight promising antifibrotic approaches.

Low-dose steroids associated with milder histological changes after pediatric liver transplantation

Controversy remains about the role of protocol liver biopsy for symptom-free recipients and about the long-term use of low-dose steroids after pediatric liver transplantation (LT). We conducted a national cross-sectional study of pediatric recipients who underwent LT between 1987 and 2007. Liver biopsy samples were taken from 54 patients (82% of survivors) after a median posttransplant follow-up of 11 years, and they were reviewed by 2 pathologists blinded to the clinical data. Biopsy samples from 18 patients (33%) showed nearly normal histology with no inflammation, fibrosis, or steatosis. Portal inflammation was detected in 14 samples (26%), showed no correlation with anti-nuclear antibodies, and was less frequent in the 35 patients whose immunosuppression included steroids (14% versus 47% of patients not using steroids, P = 0.008). Fibrosis was present in 21 biopsy samples (39%). According to the Metavir classification, 16 were stage 1, 3 were stage 2, and 2 were stage 3. The fibrosis stage correlated negatively with serum prealbumin levels (r = -0.364, P = 0.007) and positively with chronic cholestasis (cytokeratin 7 staining; r = 0.529, P < 0.001) and portal inflammation (r = 0.350, P = 0.01). Microvesicular steatosis was found in 23 biopsy samples (43% of patients in 5%-80% of hepatocytes), and it correlated with the body mass index (r = 0.458, P < 0.001) but not with steroid use. The age of the allograft (donor age plus follow-up time) correlated with higher serum gamma-glutamyltransferase (r = 0.472, P < 0.001) and conjugated bilirubin levels (r = 0.420, P = 0.002) as well as chronic cholestasis (r = 0.299, P = 0.03). The biopsy findings led to treatment changes in 10 patients (19%), whereas only 1 complication (subcapsular hematoma) was encountered. In conclusion, continuing low-dose steroids indefinitely after pediatric LT may have a positive effect on the long-term histological state of the liver graft. Allograft aging may lead to chronic cholestasis and thus contribute to the development of liver fibrosis.

Importance of liver biopsy findings in immunosuppression management: biopsy monitoring and working criteria for patients with operational tolerance

Obstacles to morbidity-free long-term survival after liver transplantation (LT) include complications of immunosuppression (IS), recurrence of the original disease and malignancies, and unexplained chronic hepatitis and graft fibrosis. Many programs attempt to minimize chronic exposure to IS by reducing dosages and stopping steroids. A few programs have successfully weaned a highly select group of recipients from all IS without apparent adverse consequences, but long-term follow-up is limited. Patients subjected to adjustments in IS are usually followed by serial liver chemistry tests, which are relatively insensitive methods for detecting allograft damage. Protocol biopsy has largely been abandoned for hepatitis C virus-negative recipients, at least in part because of the inability to integrate routine histopathological findings into a rational clinical management algorithm. Recognizing a need to more precisely categorize and determine the clinical significance of findings in long-term biopsy samples, the Banff Working Group on Liver Allograft Pathology has reviewed the literature, pooled the experience of its members, and proposed working definitions for biopsy changes that (1) are conducive to lowering IS and are compatible with operational tolerance (OT) and (2) raise concern for closer follow-up and perhaps increased IS during or after IS weaning. The establishment of guidelines should help us to standardize analyses of the effects of various treatments and/or weaning protocols and more rigorously categorize patients who are assumed to show OT. Long-term follow-up using standardized criteria will help us to determine the consequences of lowering IS and to define and determine the incidence and robustness of OT in liver allografts.

Diagnosis, pathogenesis, and treatment of autoimmune hepatitis after liver transplantation

Autoimmune hepatitis can recur or appear de novo after liver transplantation, and it can result in hepatic fibrosis, graft loss, and re-transplantation. The goals of this review are to describe the prevalence, manifestations, putative pathogenic mechanisms, outcomes, and management of these occurrences. Autoimmune hepatitis recurs in 8-12 % of transplanted patients at 1 year and 36-68 % at 5 years. Recurrence may be asymptomatic and detected only by surveillance liver test abnormalities or protocol liver tissue examination. Autoantibodies that characterized the original disease, hypergammaglobulinemia, increased serum immunoglobulin G level, and histological findings of interface hepatitis, lymphoplasmacytic infiltration, perivenular hepatocyte necrosis, pseudo-rosetting, and acidophil bodies typify recurrence. Premature corticosteroid withdrawal and pre-transplant severity of the original disease are possible risk factors. De novo autoimmune hepatitis occurs in 1-7 % of patients 0.1-9 years after transplantation, especially in children. The appearance of autoantibodies may herald its emergence, and antibodies to glutathione-S-transferase T1 have been predictive of the disease. Recurrent disease may reflect recruitment of residual memory T lymphocytes and host-specific genetic predispositions, whereas de novo disease may reflect an allo-antigenic immune response and molecular mimicries that override self-tolerance. Treatment should be appropriate for autoimmune hepatitis and not based on anti-rejection drugs. Corticosteroid therapy alone or combined with azathioprine is the essential treatment. The substitution of mycophenolate mofetil for azathioprine and switch of the calcineurin inhibitor or its replacement with rapamycin have also been used for refractory disease. Re-transplantation has been necessary in 8-23 %.

Twenty-year protocol liver biopsies: Invasive but useful for the management of liver recipients

BACKGROUND & AIMS

Most liver transplant centres have discontinued the practice of protocol liver biopsies (LB), mainly because of the perceived lack of therapeutic benefit. This study aimed to examine the usefulness of 20-year LBs.

METHODS

Ten, 15, and 20-year protocol LBs from 147 patients surviving for >20 years were reviewed. Twenty-year biopsy findings were correlated with clinical data.

RESULTS

Twenty-year-biopsy patients (N=91) and 20-year-non-biopsy patients (N=56) were similar in terms of transplant data, adverse events, and liver function tests (LFTs). Twenty-year LBs revealed a 90% prevalence of abnormalities, among which viral chronic hepatitis (VCH) was the most common (46%). Between 15 and 20 years, hepatic structural abnormalities were the only disorder to increase (p=0.008). An individual progression of abnormalities occurred in 56% of patients. At 20 years, the negative and positive predictive values (PV) of LFTs with respect to histological abnormalities were 95% and 18%, respectively; in VCH, Fibrotest and transient elastography displayed poor discriminative ability for fibrosis (80% and 81% discordance, respectively), but were satisfactory regarding significant fibrosis (negative PV of 77.7% and 80%, respectively). A decrease in immunosuppression was less frequent (14/91 vs. 20/56, p=0.008) while an increase was more common (15/91 vs. 2/56, p=0.017) in 20-year-biopsy patients than in non-biopsy patients. Antiviral therapy was administered in seven of the 20-year biopsy patients, but in none of the non-biopsy patients (p=0.04).

CONCLUSIONS

Twenty-year LBs provided important histological information on graft function that was available to a limited degree from LFTs and non-invasive markers. They exerted an impact on immunosuppressive and antiviral therapies.

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.

Adding value to liver (and allograft) biopsy evaluation using a combination of multiplex quantum dot immunostaining, high-resolution whole-slide digital imaging, and automated image analysis

Various technologies including nucleic acid, protein, and metabolic array analyses of blood, liver tissue, and bile are emerging as powerful tools in the study of hepatic pathophysiology. The entire lexicon of liver disease, however, has been written using classical hematoxylin-eosin staining and light microscopic examination. The authors' goal is to develop new tools to enhance histopathologic examination of liver tissue that would enrich the information gained from liver biopsy analysis, enable quantitative analysis, and bridge the gap between various "-omics" tools and interpretation of routine liver biopsy results. This article describes the progress achieved during the past 2 years in developing multiplex quantum dot (nanoparticle) staining and combining it with high-resolution whole-slide imaging using a slide scanner equipped with filters to capture 9 distinct fluorescent signals for multiple antigens. The authors first focused on precise characterization of leukocyte subsets, but soon realized that the data generated were beyond the practical limits that could be properly evaluated, analyzed, and interpreted visually by a pathologist. Therefore, the authors collaborated with the open source FARSIGHT image analysis project (http://www.farsight-toolkit.org). FARSIGHT's goal is to develop and disseminate the next-generation toolkit of automated image analysis methods to enable quantification of molecular biomarkers on a cell-by-cell basis from multiparameter images. The resulting data can be used for histocytometric studies of the complex and dynamic tissue microenvironments that are of biomedical interest. The authors envisage that these tools will eventually be incorporated into the routine practice of surgical pathology and precipitate a revolution in the specialty.

Heterogeneous inflammatory changes in liver graft recipients with normal biochemistry

BACKGROUND

Patients with established liver grafts may receive excessive immune suppression. Liver biopsies were analyzed in those with normal liver biochemistry to identify parameters that might identify such cases.

METHODS

Patients with established grafts (>3 years from engraftment) and normal liver biochemistry (normal alanine transaminase, alkaline phosphatase, and bilirubin) were invited to undergo liver biopsy. Liver tissue was assessed by routine histopathology, a modified Ishak score, and immunohistochemistry for lymphocyte and cell-cycle markers. Circulating and intrahepatic lymphocytes were subjected to flow cytometry. Data were subjected to principal component analysis.

RESULTS

Two hundred twenty-five (40%) patients under regular review had an established graft with normal liver biochemistry; liver tissue was obtained in 55. Liver histology was normal in eight cases (14.5%). The most common abnormalities were mild nonspecific hepatitis in 25 (45.4%) and disease recurrence in 14 (25.4%). Principal component analysis identified a cluster of variables that accounted for a significant degree of variation within the dataset. These were lobular inflammation, portal inflammation, interface hepatitis, and fibrosis.

CONCLUSIONS

Inflammation persisted in established grafted livers in most patients with normal liver biochemistry. Systematic histological and lymphocyte phenotype analysis generated an index that distinguished patient groups. Those with least inflammation and the lowest alanine transaminase may have a reduced requirement for immune suppression.

What does the long-term liver allograft look like for the pediatric recipient?

1. Histological abnormalities are commonly present in late posttransplant biopsies from pediatric liver allograft recipients. 2. Many of the changes are seen in children who appear to be clinically well with good graft function. 3. In comparison with adults, children may be more prone to developing late rejection (possibly related to noncompliance with immunosuppression) and biliary/vascular complications, but they are much less likely to suffer problems with disease recurrence. 4. De novo autoimmune hepatitis occurs in 5% to 10% of children after transplantation and may represent a hepatitic form of late cellular rejection. Most cases respond to treatment with increased immunosuppression. 5. Recent studies have shown a high frequency of unexplained (idiopathic) chronic hepatitis in late posttransplant biopsies from children. This is associated with the development of graft fibrosis and cirrhosis. 6. Further studies are required to investigate the role of protocol liver biopsies in determining therapeutic strategies in children who appear to have good graft function according to noninvasive investigations.

Late protocol liver biopsies in the liver allograft: a neglected investigation?

As outcomes from liver transplantation have improved, attention has focused on long-term outcomes: patient and graft survival is affected by many factors, including the consequences of both overimmunosuppression (eg, renal failure and cancer) and underimmunosuppression (eg, rejection). The use of protocol (rather than event-driven) biopsies of the liver allograft, except for those grafted for HCV infection, has been largely abandoned. The aim of this study was to determine if protocol biopsies can improve the management of liver allograft recipients. A retrospective analysis of liver allograft recipients who had undergone protocol liver biopsies between 2000 and 2006 was performed. One hundred seventy-eight patients with normal liver tests (alcoholic liver disease, 49; autoimmune hepatitis, 20; and primary biliary cirrhosis, 107) who had undergone 235 protocol biopsies were identified. No significant complication from the biopsy was recorded. Liver histology was reported as normal or nearly normal in only 57 (24%). Chronic hepatitis (not obviously related to disease recurrence) was present in 78 (33%). Interpreted in the light of the calculated creatinine clearance, the biopsy findings indicated that overall immunosuppression (IMS) should be maintained or increased with standard calcineurin inhibitor (CNI)-based IMS in 25% of cases, that overall IMS should be reduced in 15% of cases, and that overall IMS should be maintained or increased by the substitution of non-nephrotoxic agents for CNIs in 9% of cases. The histological findings led to a documented change in IMS in 76 (32%) (increased IMS, 11; decreased IMS, 58; and switch from CNI, 7). In conclusion, protocol liver biopsy provides important histological information about graft function that is not available from standard liver tests and safely allows modification of IMS to ensure that long-term side effects of drug therapy (eg, renal failure) are minimized while graft function is sustained. Liver Transpl 15:931-938, 2009. (c) 2009 AASLD.