Early acute cellular rejection: no effect on late hepatic allograft function in man

Usefulness of Diffusion-Weighted Imaging in Evaluating Acute Cellular Rejection and Monitoring Treatment Response in Liver Transplant Recipients

Acute cellular rejection (ACR) is a significant immune issue among recipients following liver transplantation. Although diffusion-weighted magnetic resonance imaging (DWI) is widely used for diagnosing liver disease, it has not yet been utilized for monitoring ACR in patients after liver transplantation. Therefore, the aim of this study was to evaluate the efficacy of DWI in monitoring treatment response among recipients with ACR. This study enrolled 25 recipients with highly suspected ACR rejection, and all subjects underwent both biochemistry and DWI scans before and after treatment. A pathological biopsy was performed 4 to 24 h after the first MRI examination to confirm ACR and degree of rejection. All patients were followed up and underwent a repeated MRI scan when their liver function returned to the normal range. After data acquisition, the DWI data were post-processed to obtain the apparent diffusion coefficient (ADC) map on a voxel-by-voxel basis. Five regions of interest were identified on the liver parenchyma to measure the mean ADC values from each patient. Finally, the mean ADC values and biochemical markers were statistically compared between ACR and non-ACR groups. A receiver operating characteristic (ROC) curve was constructed to evaluate the performance of the ADC and biochemical data in detecting ACR, and correlation analysis was used to understand the relationship between the ADC values, biochemical markers, and the degree of rejection. The histopathologic results revealed that 20 recipients had ACR, including 10 mild, 9 moderate, and 1 severe rejection. The results demonstrated that the ACR patients had significantly lower hepatic ADC values than those in patients without ACR. After treatment, the hepatic ADC values in ACR patients significantly increased to levels similar to those in non-ACR patients with treatment. The ROC analysis showed that the sensitivity and specificity for detecting ACR were 80% and 95%, respectively. Furthermore, the correlation analysis revealed that the mean ADC value and alanine aminotransferase level had strong and moderate negative correlation with the degree of rejection, respectively (r = -0.72 and -0.47). The ADC values were useful for detecting hepatic ACR and monitoring treatment response after immunosuppressive therapy.

CT of acute rejection after liver transplantation: a matched case-control study

PURPOSE

This study was conducted in order to investigate computed tomography (CT) findings associated with acute cellular rejection (ACR) following liver transplantation (LT) and their relevance to clinical outcomes.

MATERIALS AND METHODS

We analyzed 120 patients with newly diagnosed ACR following LT for various liver diseases and 119 controls matched for age, sex, type of liver graft, and date of CT exam following LT. Two radiologists analyzed the images for morphological characteristics of the graft, morphological change in the major draining vein, graft enhancement in the portal venous phase, graft attenuation on noncontrast CT, and periportal halo. Univariate analysis was used to determine the association between radiological findings and ACR. Clinical outcomes, including treatment response and graft survival, were compared between patients with and without associated radiological findings.

RESULTS

Morphological characteristics of the graft (i.e., globular swelling), morphological change in the major draining vein (i.e., nonanastomotic luminal narrowing), and heterogeneous enhancement were significantly associated with ACR (all p < 0.001). On univariate analysis, the severity of morphological characteristics of the grafts (mild/severe: odds ratio [OR], 19.98/32.24) and morphological change in the major draining vein (without/with prestenotic dilatation: OR, 4.17/22.5) were significantly associated with the increased possibility of an ACR diagnosis. Clinical outcomes for treatment response and graft survival were not significantly different between patients with and without associated radiological findings.

CONCLUSIONS

Globular swelling, nonanastomotic stenosis with or without prestenotic dilatation of the major draining vein, and heterogeneous enhancement of the graft on portal venous-phase CT were significantly associated with ACR.

KEY POINTS

• Globular swelling of the graft, nonanastomotic narrowing in the major vein, and heterogeneous graft enhancement on CT were significantly associated with acute cellular rejection (ACR). • Associated CT findings were highly specific but not sensitive for differentiating ACRs from matched controls.

Graft Dysfunction and Management in Liver Transplantation

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

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

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

Management of Immunosuppression in Liver Transplantation

Liver transplantation outcomes have significantly improved over the past few decades owing largely to the introduction of effective immunosuppression medications. Further comprehension of the unique immune microenvironment of the liver has led to the development of newer molecular targeted therapeutics. Understanding the mechanism of action and adverse effect profiles of these medications is crucial for appropriate management of posttransplant patients. In this review, the author describes the immunologic response elicited by liver transplantation, chronicles the various immunosuppressant drug classes, discusses the evidence behind their use, and evaluates the management of special subpopulations of posttransplantation patients.

Profiling immunologic risk for acute rejection in liver transplantation: Recipient age is an important risk factor

BACKGROUND

Careful management of induction and maintenance of immunosuppression is paramount to prevent acute rejection in liver transplantation. A methodical analysis of risk factors for acute cellular rejection may provide a more comprehensive method to profile the immunologic risk of candidates.

METHODS

Using registry data from the Organ Procurement and Transplantation Network (OPTN), we identified 42,508 adult recipients who underwent orthotopic liver transplant (OLT) between 2002 and 2013. We excluded recipients with a blank entry for treated rejection. We analyzed this all inclusive cohort in addition to a subset of 27,493 patients with just tacrolimus immunosuppression. Multivariate logistic regression was used on both cohorts and identified independent risk factors for treated acute rejection at one year.

RESULTS

Recipient age (reference group was 40 to 60years) was a dominant risk factor for rejection in both cohorts and had a dose response relationship. The strongest risk factors in the inclusive cohort were: age 18-25 (OR 2.20), age 26-29 (OR 2.03), and primary biliary cholangitis (OR 1.55). The most protective factors were age 70 and older (OR 0.68), and age 65-69 (OR 0.70). The rates of rejection had a similar pattern.

CONCLUSIONS

Although prior studies have suggested age as a risk factor for rejection in liver transplantation, this is the first study of national-level data to demonstrate a robust dose dependent relationship between age and risk for rejection at one year. Clinicians should place significant weight on recipient age when they assess their recipients for the immunologic risk of rejection.

Management of immunosuppressant agents following liver transplantation: Less is more

Immunosuppression in organ transplantation was revolutionary for its time, but technological and population changes cast new light on its use. First, metabolic syndrome (MS) is increasing as a public health issue, concomitantly increasing as an issue for post-orthotopic liver transplantation patients; yet the medications regularly used for immunosuppression contribute to dysfunctional metabolism. Current mainstay immunosuppression involves the use of calcineurin inhibitors; these are potent, but nonspecifically disrupt intracellular signaling in such a way as to exacerbate the impact of MS on the liver. Second, the impacts of acute cellular rejection and malignancy are reviewed in terms of their severity and possible interactions with immunosuppressive medications. Finally, immunosuppressive agents must be considered in terms of new developments in hepatitis C virus treatment, which undercut what used to be inevitable viral recurrence. Overall, while traditional immunosuppressive agents remain the most used, the specific side-effect profiles of all immunosuppressants must be weighed in light of the individual patient.

Long term management of liver transplant rejection in children

The current management of hepatic allograft rejection after liver transplantation in children requires effective baseline immunosuppression to prevent rejection and rapid diagnosis and treatment to manage acute rejection episodes. The subsequent impact on chronic rejection is dependent on the combination of adequate prevention and the treatment of acute rejection. Tacrolimus is a macrolide lactone that inhibits the signal transduction of interleukin-2 (IL-2) via calcineurin inhibition. Introduced in 1989, tacrolimus was first used in the salvage of refractory acute or chronic rejection under cyclosporin or to rescue patients with significant cyclosporin-related complications. The majority of paediatric transplant centres use a combination of steroids with tacrolimus as a basic immunosuppressant regimen following paediatric liver transplantation. This combination has allowed the acute cellular rejection-free rate to increase to between 30 and 60%, while lowering the rate of refractory rejection to less than 5%. Corticosteroid-resistant rejection is commonly treated with monoclonal (muromonab CD3) or polyclonal preparations. Although most episodes of acute cellular rejection occur during the first 6 weeks after liver transplant, the appearance of late acute liver allograft rejection must raise the question of noncompliance, especially in the adolescent population. Chronic rejection is becoming increasingly rare under tacrolimus-based immunosuppression. Tacrolimus is effective in reversing refractory acute cellular rejection or early chronic rejection in patients initially treated with cyclosporin-based regimens. Patients with a history of noncompliance as well as children with autoimmune liver disease are at risk of chronic rejection. Retransplantation therapy for chronic rejection has, fortunately, become more rare in the tacrolimus era with only 3% of retransplants being performed for this indication. Newer immunosuppressive agents are further modifying the long term management of liver allograft rejection. These include mycophenolate mofetil, rapamycin and IL-2 antibodies such as daclizumab. The development of these agents is allowing patient-specific immunosuppressive management to minimise rejection as well as the complications related to immunosuppression.

Management of the liver transplant patient

Liver transplantation is currently the definitive treatment of end-stage liver disease. This article reviews the complex multidisciplinary care of the liver transplant recipient beginning immediately after transplantation but extending into the long term. The presentation, evaluation and treatment of common post-transplant complications are outlined. Importantly, immunosuppression strategies along with the issues of acute and chronic rejection are discussed in detail with an emphasis on how practice has evolved over time. The spectrum of infectious problems is systematically presented, based on the time since transplantation and the institution of immunosuppression. Finally, the substantial challenges of recurrent disease and long-term medical comorbidities are addressed as these are clearly the primary issues that threaten the longevity and wellbeing of the liver transplant recipient.

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

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

The clinical significance of early histological rejection with or without biochemical abnormality in adult living donor liver transplantation for hepatitis B virus related end stage liver disease

There is no agreement regarding the treatment of early allograft rejection (EAR) in adult living donor liver transplantation (LDLT). A protocol biopsy was performed in 62 adult LDLT recipients. Twenty-one patients (33.9%) had histological evidence of EAR. Of these, 14 patients had biochemical abnormalities and seven patients had no associated biochemical abnormalities. None of the seven patients with subclinical EAR (11.3% of the entire study population) were treated, and no subsequent rejection was observed. Gender mismatch (female-to-male) was the single independent risk factor for histological EAR [odds ratio (OR) = 13.458; 95% confidence interval (CI), 1.836-98.649] and the cumulative probability for a subsequent rejection was higher in patients with EAR (OR = 11.085; 95% CI, 1.221-100.654). However, the actuarial 1 year patient and graft survival rate in patients with EAR (81.0% and 85.5%) were similar to those without EAR (92.7% and 97.25%; P = 0.127 and 0.302, respectively). The presence of an initial biochemical abnormality was an independent risk factor for both a decreased patient survival (OR = 5.827; 95% CI, 1.095-31.017; P = 0.039) and graft loss (OR = 20.646; 95% CI, 2.044-208.524; P = 0.010). Subsequent rejection developed more frequently in patients with EAR. However, the survival is not determined by the presence of EAR but by the presence of a biochemical abnormality.

Are preformed antibodies to biliary epithelial cells of clinical importance in liver transplantation?

During acute liver allograft rejection, most of the tissue damage to bile duct epithelium is thought to occur as a consequence of direct immunologic injury by T-cell-mediated immune effector mechanisms. However, the role of antibodies to biliary epithelial cells (BECs) in liver transplant rejection is not known. We therefore investigated cross-match sera obtained immediately before liver transplantation from 95 patients for the presence of BEC-reactive antibodies to determine their association with acute rejection. BECs were isolated from one normal healthy liver. Antibody binding was detected by using flow cytometric analysis. Donor lymphocyte-specific cross-matches using complement-dependent cytotoxicity (CDC) and flow cytometric assays also were performed. The 2-year patient survival rate in this study was 86.3%. Eleven patients were positive for either CDC or flow cytometric cross-matches. BEC antibodies were detected in 41 serum samples (43.2%). Patients with BEC antibodies experienced acute rejection more frequently (65.9%) compared with 42.5% without antibodies (P <.03). HLA specificity determinations indicated that in 5 of 41 cases, anti-BEC reactivity was caused by HLA antibodies. No correlations between the presence of BEC antibodies and patient survival and the occurrence of cholangitis and nonsurgical bile duct strictures were found within 2 years of follow-up. In conclusion, preformed antibodies to BECs are associated with acute rejection. Thus, the presence of these antibodies before transplantation may facilitate acute liver graft rejection.

Effect of immunosuppressive regimen on acute rejection and liver graft function

Despite the use of modern immunosuppressive drugs, acute liver rejection (AR) continues to affect up to 70% of transplant recipients. The aim of this retrospective study was to assess the incidence of acute rejection episodes in patients treated with different immunosuppressive protocols. In our series, 37.3% of patients developed a clinical episode of AR. Analysis of immunosuppression has shown that the most effective immunosuppressive protocols, with regard to prevention of AR, include: antibody anti-IL-2R (anti-IL-2R) + tacrolimus (Tac) + mycophenolate mofetil (MMF) + prednisolone (Pred); anti-IL-2R + tacrolimus (Tac) + Pred; or Tac + Pred (25% vs 28.6% vs 30.4%, respectively). The highest rate of AR (66.6%) was observed among patients with anti-IL-2R and Tac but no steroid treatment, mostly (77.7%) in the initial period after liver transplantation. There were no statistical differences in liver function tests between the group treated with a CsA-based versus a Tac-based therapy. Strong immunosuppression contributed to a relatively low incidence of clinical AR in our series. The lowest rate of AR was observed among patients treated with anti-IL-2R antibody. Tac, and Pred. Deprivation of steroids in the early phase after liver transplantation substantially increased the risk of acute rejection episodes despite the use of anti-CD25. There were no statistically significant differences in liver function tests among those treated with Tac versus CsA in the short-term follow-up.