Donor-Specific Anti-HLA Antibodies and Endothelial C4d Deposition-Association With Chronic Liver Allograft Failure

BACKGROUND

The significance of humoral immune response for allograft survival after liver transplantation (LT) is still a matter of debate. The aim of this cross-sectional study was to assess immunological and clinical factors associated with advanced fibrosis (F3-F4) and chronic graft failure in LT recipients.

METHODS

Serum samples from 174 patients prospectively enrolled and followed up for 12 months were tested for anti-HLA antibodies and compared against donor HLA types. Immunohistochemical C4d staining was performed on formalin-fixed, paraffin-embedded liver tissue.

RESULTS

Mean time period from LT to enrollment was 66.9 ± 51.9 months. Independent predictive factors for graft failure included donor-positive cytomegalovirus serostatus (P = 0.02), donor-specific antibodies (DSA) against HLA class II (P = 0.03), donor age (P = 0.01), hepatitis C virus allograft reinfection (P = 0.0008), and biliary complications (P = 0.003). HLA class II DSA and HLA class I antibody positivity, hepatitis C virus reinfection, and mycophenolate mofetil-free regimens were significant risk factors for advanced fibrosis after LT. There was a significant association between C4d deposition on allograft endothelial cells and presence of class II DSA (P < 0.0001). Patients with C4d deposits had a 4.3 times higher risk of graft failure than those with negative staining and a significantly lower median time to graft failure (94.6 months [range, 3.6-158.9 months] vs 176.4 months [range, 9.4-217.8 months], P < 0.0001).

CONCLUSIONS

Screening for HLA DSA might be useful for early identification of LT recipients at increased risk of graft failure who could benefit from closer surveillance and tailored immunosuppressive regimens.

Impact of different immunosuppressive regimens on the health-related quality of life following orthotopic liver transplantation

BACKGROUND

The influence of immunosuppression on the recipients' quality of life (QoL) is of major importance after OLT and has not yet been evaluated.

METHODS

The impact of different immunosuppression regimens after OLT was evaluated in 275 patients using the Short Form 36 (SF-36) survey. The following immunosuppressive strategies were compared: (a) CNI, (b) mTOR inhibitors, and (c) mTOR combined with CNI. All regimens were prescribed alone (mono) or in combination (+) with prednisolone and/or mycophenolate mofetil (MMF).

RESULTS

Highest scores were evident in patients in the mTOR+ group. There were significantly higher values for general health perceptions (GH, p = 0.049), vitality (VIT, p = 0.020), and physical component summary (PCS, p = 0.041) when compared to CNImono and for GH (p = 0.042) and VIT (p = 0.043), when compared to mTORmono. Early conversion to mTOR inhibitors (<two months after OLT) was associated with higher values for 7 of 10 scales, when compared to a late conversion (>two months after OLT), with a statistically significant improvement for the dimension role-emotional (RE, p = 0.027).

DISCUSSION

mTOR inhibitor-based regimens appear to have beneficial effects on QoL after OLT, especially after an early conversion.

Longitudinal studies of a B cell-derived signature of tolerance in renal transplant recipients

Biomarkers of transplant tolerance would enhance the safety and feasibility of clinical tolerance trials and potentially facilitate management of patients receiving immunosuppression. To this end, we examined blood from spontaneously tolerant renal transplant recipients and patients enrolled in two interventional tolerance trials using flow cytometry and gene expression profiling. Using a previously reported tolerant cohort as well as newly identified tolerant patients, we confirmed our previous finding that tolerance was associated with increased expression of B cell-associated genes relative to immunosuppressed patients. This was not accounted for merely by an increase in total B cell numbers, but was associated with the increased frequencies of transitional and naïve B cells. Moreover, serial measurements of gene expression demonstrated that this pattern persisted over several years, although patients receiving immunosuppression also displayed an increase in the two most dominant tolerance-related B cell genes, IGKV1D-13 and IGLL-1, over time. Importantly, patients rendered tolerant via induction of transient mixed chimerism, and those weaned to minimal immunosuppression, showed similar increases in IGKV1D-13 as did spontaneously tolerant individuals. Collectively, these findings support the notion that alterations in B cells may be a common theme for tolerant kidney transplant recipients, and that it is a useful monitoring tool in prospective trials.

Posttransplant lymphoproliferative disorders following liver transplantation: Where are we now?

Liver transplantation has emerged as a life-saving treatment for several patients with acute liver failure, end stage liver disease and primary hepatic malignancies. However, long term immunosuppressive therapy aiming to reduce the risk of transplant rejection increases the incidence of several complications including malignancies. This is illustrated by the observation of a high ratio between observed and expected cases of lymphoproliferative disorders following liver transplantation. Despite a huge heterogeneity in morphological appearance of these disorders ranging from reactive-like lesions to real lymphomas, they are collectively termed posttransplant lymphoproliferative disorders. In this review we will provide an overview of this rare but challenging disorder as a complication of liver transplantation.

Tolerance signatures in transplant recipients

PURPOSE OF REVIEW

The intent of this review was to describe biomarkers that predict or identify individuals who exhibit tolerance to a transplanted organ. The identification of tolerance biomarkers would spare some individuals the toxicity of immunosuppressive agents, enhance the safety of studies to induce tolerance, and provide insights into mechanisms of tolerance that may aid in designing new regimens.

RECENT FINDINGS

Studies of tolerant kidney transplant recipients have revealed an association with B cells. More recent studies have suggested that these B cells may be less mature than from those in nontolerant recipients, and especially suited to suppress alloimmune responses. Biomarkers in tolerant liver transplant patients appear to be distinct from those associated renal tolerance. Most reports have identified an association with natural killer and/or γδ T cells rather than B cells. Recent data indicate biomarkers associated with iron homeostasis within the transplanted liver more accurately predict the tolerant state than do biomarkers expressed in the blood, suggesting that the renal allograft itself, which is infrequently sampled, would be informative.

SUMMARY

Given the encouraging progress in identifying tolerance biomarkers, it will be important to validate these markers in larger studies of transplant recipients undergoing prospective minimization or withdrawal of immunosuppression.

Lost in translation? Microchimersim detection in experimental and clinical transplantation

The importance of further elucidating the properties surrounding microchimerism in various experi- mental models and clinical transplantation are limited by current techniques and the sensitivity of available platforms. Development of reliable methods and use routine use of microchimerism detection in clinical practice could guide clinical decision making regarding rejection, stable function, and tolerance.

Withdrawal of immunosuppression in liver transplantation and the mechanism of tolerance

BACKGROUND

Immunosuppression reagents have side effects and cause considerable long-term morbidity and mortality in patients after liver transplantation. Sufficient evidences showed that minimization or withdrawal of immunosuppression reagents does not deteriorate the recipient's immune response and physiological function and therefore, is feasible in some recipients of liver transplantation. However, the mechanisms are not clear. The present review was to update the current status of immunosuppression in liver transplantation and the mechanism of minimization or withdrawal of immunosuppression in liver recipients.

DATA SOURCES

We searched articles in English on minimization or withdrawal of immunosuppression in liver transplantation in PubMed. We focused on the basic mechanisms of immune tolerance in liver transplantation. Studies on immunosuppression minimization or withdrawal protocols and biomarker in tolerant recipients were also analyzed.

RESULTS

Minimization or withdrawal of immunosuppression can be achieved by the induction of immune tolerance, which may not be permanent and can be affected by various factors. However, accurately evaluating immune status post-transplant is a prerequisite to achieve individualized immunosuppression. Numerous mechanisms for immune tolerance have been found, including immunophenotypic shift of memory CD8+ T cells and CD4+ T cell subsets. Activation of the inflammasome through apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC) in dendritic cells is associated with rejection after liver transplantation.

CONCLUSIONS

Minimization or withdrawal of immunosuppression can be achieved by the induction of immune tolerance via different mechanisms. This process could be affected by immunophenotypic shift of memory CD8+ T cells and CD4+ T cell subsets, which may be correlated with activation of the inflammasome through ASC in dendritic cells.

Adult liver transplantation in the congenital absence of inferior vena cava

Whereas congenital absence of inferior vena cava observed in paediatric population more often than not, as an isolated or syndromic variety, this is seldom encountered in adult liver transplant recipients. There appear few sporadic reports in the literature on experience of such anomaly in adults. Given the rarity of situation, surprising encounters of such anomalies may pose challenge to the unprepared transplant surgeon and unfavourable outcomes may even have resulted in under-reportage of this condition. In this brief report we document our recent experience with two such cases and this is supplemented with extensive reference to the literature on classification of such anomalies with the endeavour to document implications of such in the adult liver transplant setting.

CMV Primary Infection Is Associated With Donor-Specific T Cell Hyporesponsiveness and Fewer Late Acute Rejections After Liver Transplantation

Viral infections, including cytomegalovirus (CMV), abrogate transplantation tolerance in animal models. Whether this also occurs in humans remains elusive. We investigated how CMV affects T cells and rejection episodes after liver transplantation (LT). Phenotype and alloreactivity of peripheral and allograft-infiltrating T cells from LT patients with different CMV status were analyzed by flow cytometry. The association of CMV status with early and late acute rejection was retrospectively analyzed in a cohort of 639 LT patients. CMV-positivity was associated with expansion of peripheral effector memory T cell subsets after LT. Patients with CMV primary infection showed donor-specific CD8(+) T cell hyporesponsiveness. While terminally differentiated effector memory cells comprised the majority of peripheral donor-specific CD8(+) T cells in CMV primary infection patients, they were rarely present in liver allografts. Retrospective analysis showed that R(-) D(+) serostatus was an independent protective factor for late acute rejection by multivariate Cox regression analysis (hazard ratio [HR] = 0.18, 95% CI = 0.04-0.86, p = 0.015). Additionally, CMV primary infection patients showed the highest Vδ1/Vδ2 γδ T cell ratio, which has been shown to be associated with operational tolerance after LT. In conclusion, our data suggest that CMV primary infection may promote tolerance to liver allografts, and CMV status should be considered when tapering or withdrawing immunosuppression.

ABO-compatible liver allograft antibody-mediated rejection: an update

PURPOSE OF REVIEW

Liver allograft antibody-mediated rejection (AMR) studies have lagged behind parallel efforts in kidney and heart because of a comparative inherent hepatic resistance to AMR. Three developments, however, have increased interest: first, solid phase antibody testing enabled more precise antibody characterization; second, increased expectations for long-term, morbidity-free survival; and third, immunosuppression minimization trials.

RECENT FINDINGS

Two overlapping liver allograft AMR phenotypic expressions are beginning to emerge: acute and chronic AMR. Acute AMR usually occurs within the several weeks after transplantation and characterized clinically by donor-specific antibodies (DSA) persistence, allograft dysfunction, thrombocytopenia, and hypocomplementemia. Acute AMR appears histopathologically similar to acute AMR in other organs: diffuse microvascular endothelial cell hypertrophy, C4d deposits, neutrophilic, eosinophilic, and macrophag-mediated microvasculitis/capillaritis, along with liver-specific ductular reaction, centrilobular hepatocyte swelling, and hepatocanalicular cholestasis often combined with T-cell-mediated rejection (TCMR). Chronic AMR is less well defined, but strongly linked to serum class II DSA and associated with late-onset acute TCMR, fibrosis, chronic rejection, and decreased survival. Unlike acute AMR, chronic AMR is a slowly evolving insult with a number of potential manifestations, but most commonly appears as low-grade lymphoplasmacytic portal and perivenular inflammation accompanied by unusual fibrosis patterns and variable microvascular C4d deposition; capillaritis can be more difficult to identify than in acute AMR.

SUMMARY

More precise DSA characterization, increasing expectations for long-term survival, and immunosuppression weaning precipitated a re-emergence of liver allograft AMR interest. Pathophysiological similarities exist between heart, kidney, and liver allografts, but liver-specific considerations may prove critical to our ultimate understanding of all solid organ AMR.

Iron Deficiency Impairs Intra-Hepatic Lymphocyte Mediated Immune Response

Hepatic expression of iron homeostasis genes and serum iron parameters predict the success of immunosuppression withdrawal following clinical liver transplantation, a phenomenon known as spontaneous operational tolerance. In experimental animal models, spontaneous liver allograft tolerance is established through a process that requires intra-hepatic lymphocyte activation and deletion. Our aim was to determine if changes in systemic iron status regulate intra-hepatic lymphocyte responses. We used a murine model of lymphocyte-mediated acute liver inflammation induced by Concanavalin A (ConA) injection employing mice fed with an iron-deficient (IrDef) or an iron-balanced diet (IrRepl). While the mild iron deficiency induced by the IrDef diet did not significantly modify the steady state immune cell repertoire and systemic cytokine levels, it significantly dampened inflammatory liver damage after ConA challenge. These findings were associated with a marked decrease in T cell and NKT cell activation following ConA injection in IrDef mice. The decreased liver injury observed in IrDef mice was independent from changes in the gut microflora, and was replicated employing an iron specific chelator that did not modify intra-hepatic hepcidin secretion. Furthermore, low-dose iron chelation markedly impaired the activation of isolated T cells in vitro. All together, these results suggest that small changes in iron homeostasis can have a major effect in the regulation of intra-hepatic lymphocyte mediated responses.

Immune monitoring of immunosuppression withdrawal of liver transplant recipients

Several studies have shown that some liver transplant recipients may tolerate immunosuppression withdrawal. Mechanisms and biomarkers of tolerance are not well known.

METHODS

Twenty-four LT patients with immunosuppression side-effects underwent progressive immunosuppression withdrawal. Peripheral lymphocyte populations and secretion of cytokines were analyzed at baseline and during withdrawal until tolerance (n = 15) or rejection (n = 9), as well as 3 months after tolerance achievement or rejection resolution (as follow-up). Immunological markers were compared among groups.

RESULTS

The percentages of CD3+CD4+ cells progressively decreased in both groups. CD3+CD8+ cells gradually increased in tolerant patients. B lymphocytes gradually decreased in tolerant and initially in non-tolerant patients, reverting at rejection. Regulatory T cells progressively increased until rejection in non-tolerants, decreasing to basal levels after renewing immunosuppression; no significant changes were found in tolerant patients. The percentages and absolute counts of natural killer cells significantly increased in both groups, being more evident in tolerant patients. The secretion of several cytokines was higher in non-tolerant patients when rejection was diagnosed.

CONCLUSIONS

The greater increase of natural killer cells in tolerant patients suggests their potential role in the tolerance phenomenon.

Spontaneous restoration of transplantation tolerance after acute rejection

Transplantation is a cure for end-stage organ failure but, in the absence of pharmacological immunosuppression, allogeneic organs are acutely rejected. Such rejection invariably results in allosensitization and accelerated rejection of secondary donor-matched grafts. Transplantation tolerance can be induced in animals and a subset of humans, and enables long-term acceptance of allografts without maintenance immunosuppression. However, graft rejection can occur long after a state of transplantation tolerance has been acquired. When such an allograft is rejected, it has been assumed that the same rules of allosensitization apply as to non-tolerant hosts and that immunological tolerance is permanently lost. Using a mouse model of cardiac transplantation, we show that when Listeria monocytogenes infection precipitates acute rejection, thus abrogating transplantation tolerance, the donor-specific tolerant state re-emerges, allowing spontaneous acceptance of a donor-matched second transplant. These data demonstrate a setting in which the memory of allograft tolerance dominates over the memory of transplant rejection.

Emergent Transcriptomic Technologies and Their Role in the Discovery of Biomarkers of Liver Transplant Tolerance

Liver transplantation offers a unique window into transplant immunology due, in part, to the considerable proportion of recipients who develop immunological tolerance to their allograft. Biomarkers are able to identify and predict such a state of tolerance, and thereby able to establish suitable candidates for the minimization of hazardous immunosuppressive therapies, are not only of great potential clinical benefit but might also shed light on the immunological mechanisms underlying tolerance and rejection. Here, we review the emergent transcriptomic technologies serving as drivers of biomarker discovery, we appraise efforts to identify a molecular signature of liver allograft tolerance, and we consider the implications of this work on the mechanistic understanding of immunological tolerance.

Safety and efficacy of ipilimumab to treat advanced melanoma in the setting of liver transplantation

Ipilimumab is a first-in-class immunological checkpoint blockade agent and monoclonal antibody against Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4) that has demonstrated survival benefit and durable responses in patients with metastatic melanoma. To date, solid organ transplant recipients have been excluded from clinical trials with cancer immunotherapies on the basis of their concurrent treatment with immunosuppressive agents. We present the first case to our knowledge of a patient with advanced cutaneous melanoma receiving ipilimumab status post orthotopic liver transplantation with a partial response. Transaminitis was observed 4 months after administration of ipilimumab that resolved with close observation. No evidence of graft rejection has been observed to date. This case advocates for further investigation of the safety and efficacy of cancer immunotherapies in solid organ transplant recipients.

Review on immunosuppression in liver transplantation

The optimal level of immunosuppression in solid organ transplantation, in particular for the liver, is a delicate balance between the benefit of preventing rejection and the adverse side effects of immunosuppression. There is uncertainty about when this level is achieved in any individual recipient. Immunosuppression regimens vary between individual centers and changes with time as new agents and data are available. Presently concerns about the adverse side effects of calcineurin inhibitor, the main class of immunosuppressive agents used in liver transplantation (LT), has led to consideration of the use of antibody induction therapies for patients at higher risk of developing adverse side effects. The longevity of the transplanted organ is potentially improved by better management of rejection episodes and special consideration for tailoring of immunosuppression to the individual with viral hepatitis C, hepatocellular carcinoma or pregnancy. This review provides an overview of the current strategies for post LT immunosuppression and discusses modifications to consider for special patient populations.

Management of adrenal tumors in pregnancy

Adrenal diseases, including Cushing syndrome (CS), primary aldosteronism (PA), pheochromocytoma, and adrenocortical carcinoma, are uncommon in pregnancy; a high degree of clinical suspicion must exist. Physiologic changes to the hypothalamus-pituitary-adrenal axis in a normal pregnancy result in increased cortisol, renin, and aldosterone levels, making the diagnosis of CS and PA in pregnancy challenging. However, catecholamines are not altered in pregnancy and allow a laboratory diagnosis of pheochromocytoma that is similar to that of the nonpregnant state. Although adrenal tumors in pregnancy result in significant maternal and fetal morbidity, and sometimes mortality, early diagnosis and appropriate treatment often improve outcomes.

Novel biomarkers and functional assays to monitor cell-therapy-induced tolerance in organ transplantation

PURPOSE OF REVIEW

Cell-based immunotherapy offers a novel approach to minimize the need for immunosuppressive drugs and to promote a state of immunological tolerance to a transplanted organ. We review the most promising biomarkers and functional assays able to identify patients tolerant to their graft. Such a signature of tolerance is essential in the assessment of the efficacy with which trials of cellular therapies promote immunoregulation and minimize graft rejection.

RECENT FINDINGS

A multitude of novel cellular therapies have entered early-phase clinical trials in solid-organ transplant patients. Recent multicentre collaborations have enabled the determination of distinct tolerance profiles for both liver and kidney transplant recipients. These have been shown to be highly predictive of tolerance in certain settings and show utility in identifying patients in whom immunosuppressive drugs can be weaned or discontinued.

SUMMARY

In order to become a viable treatment option in solid-organ transplantation, the latest large, multicentre clinical trials of cellular therapies must utilize, validate and discover the biomarkers with the capacity to reliably identify a signature of immune tolerance.

Update on the management of the liver transplant patient

PURPOSE OF REVIEW

To review and highlight recent literature regarding the medical management of adult patients undergoing liver transplantation.

RECENT FINDINGS

The addition of serum sodium concentration to the model for end-stage liver disease (MELD) score more accurately predicts 90-day waitlist mortality. Predictors of waitlist mortality and posttransplant survival include lower albumin and the presence of ascites, varices, and encephalopathy, as well as more nontraditional predictors such as older age, obesity, frailty, and sarcopenia. Indications for liver transplantation are evolving with the advent of effective therapy for hepatitis C and the increased prevalence of nonalcoholic steatohepatitis. Disparities persist in the current allocation system, including geographic variation and MELD inflation for hepatocellular carcinoma. Share 35 allows for broader regional sharing of organs for patients with the highest need, without detrimental effects on waitlist mortality or survival. Everolimus is a recently approved option for posttransplant immunosuppression that spares renal function.

SUMMARY

The MELD score has enabled the liver transplant community to equitably allocate organs. Recent literature has focused on the limitations of the MELD score and the disparities inherent in the current system. The next steps for liver transplantation will be to develop strategies to further optimize waitlist prioritization and organ allocation.

Efficacy and safety of basiliximab in liver transplantation for patients with hepatitis B virus-related diseases: a single centre study

AIMS

We aim to evaluate the efficacy and safety of basiliximab in liver transplantation (LT) for patients with hepatitis B virus-related diseases.

METHODS

A total of 268 patients with hepatitis B virus-related diseases undergoing LT were enrolled and divided into two groups according to the usage of basiliximab. Total survival, the survival of high-risk patients defined by the posttransplant model for predicting mortality, acute rejection rate, biochemical parameters and other follow-up data were compared between the two groups.

RESULTS

Group Bas was composed of 131 patients who received basiliximab, and Group Triple enrolled the other 137 patients who did not. Between the two groups, there was no significant difference in the cumulative survival of patients without hepatocellular carcinoma (HCC) or in the cumulative survival of patients with HCC. For patients with benign end-stage liver diseases, Group Bas had more patients with a high risk of short- and medium-term mortality than Group Triple (22.81% vs. 8.85%, p = 0.017), but the survival curves of the two groups were not significantly different. The 1-year incidence of acute rejection was lower in Group Bas, although the difference was not significant (8.75% vs. 15.33%, p > 0.05). In both Group Bas and Group Triple, the level of serum creatinine (Scr) at 1 week posttransplantation was significantly lower than pretransplantation (61.00 vs. 88.50 μmol/l, p < 0.001; 61.50 vs. 74.00 μmol/l, p < 0.001; respectively). There was a significant difference in the pretransplantation Scr between the two groups (88.50 vs. 74.00 μmol/l, p = 0.005), but the values of Scr decreased to the same level 1 week (61.00 vs. 61.50 μmol/l, p > 0.05) and 4 weeks (61.00 vs. 59.00 μmol/l, p > 0.05) after transplantation. Significantly fewer recipients in Group Bas experienced hepatitis B relapse than in Group Triple (2/131 vs. 13/137, p = 0.006).

CONCLUSIONS

A basiliximab-induced immunosuppressive protocol is a safe regimen that achieves similar survival without increasing the acute rejection rate for LT recipients with hepatitis B virus-related diseases. For patients with benign end-stage liver diseases, this regimen reduces medium-term mortality in high-risk patients. This regimen remarkably improves renal function in the first month after LT and is correlated with a decreased hepatitis B recurrence rate in adult patients after LT.

Hepatocellular carcinoma in children

Liver tumors are relatively rare in childhood, but may be associated with a range of diagnostic, genetic, therapeutic, and surgical challenges sufficient to tax even the most experienced clinician. This article outlines the epidemiology, etiology, pathologic condition, initial workup, and management of hepatocellular carcinoma in children and adolescents.

Hand transplants and the mandate for tolerance

PURPOSE OF REVIEW

The field of vascularized composite allograft (VCA) to achieve its full potential will require induction of tolerance. This review will introduce a new method of potential inducing tolerance in hand transplantation.

RECENT FINDINGS

Hand transplantation is never a life-extending transplant. This fact resulted in considerable debate both for and against the use of immunosuppression for nonlife-extending transplants. There is considerable debate about the ethics of hand transplantation. There is now consensus that nonlife-extending transplants are acceptable in properly selected patients. However, ideally, hand transplants should not receive life-long immunosuppression. Therefore, attempts to achieve drug-free tolerance through nonlife-endangering therapies are warranted. To this end, we propose implementation of tolerizing therapy long after periinflammation has subsided and drug minimization has proven successful. Evidence that short-term treatment with low doses of IL-2 or a long-lived IL-2 immunoglobulin (Ig) can tilt the balance of immunity from tissue destructive to tolerance come from preclinical demonstrations in mouse and nonhuman primate models of autoimmunity and/or transplantation and even more recent clinical trials.

SUMMARY

We believe that with the proper use of low-dose IL-2 given at an opportune time in the inflammatory process of transplant that reduce immunosuppression and even tolerance can be induced in hand transplantation. We propose that tolerance can be inducted after a long period of conventional treatment to avoid 'tolerance-hindering' adverse inflammation that occurs in the posttransplant period. With abatement of posttransplant inflammation and with time, we will institute low-dose IL-2-based therapy to support the proliferation, viability and functional phenotype of regulatory T cells.

From immunosuppression to tolerance

The past three decades have seen liver transplantation becoming a major therapeutic approach in the management of end-stage liver diseases. This is due to the dramatic improvement in survival after liver transplantation as a consequence of the improvement of surgical and anaesthetic techniques, of post-transplant medico-surgical management and of prevention of disease recurrence and other post-transplant complications. Improved use of post-transplant immunosuppression to prevent acute and chronic rejection is a major factor in these improved results. The liver has been shown to be more tolerogenic than other organs, and matching of donor and recipients is mainly limited to ABO blood group compatibility. However, long-term immunosuppression is required to avoid severe acute and chronic rejection and graft loss. With the current immunosuppression protocols, the risk of acute rejection requiring additional therapy is 10-40% and the risk of chronic rejection is below 5%. However, the development of histological lesions in the graft in long-term survivors suggest atypical forms of graft rejection may develop as a consequence of under-immunosuppression. The backbone of immunosuppression remains calcineurin inhibitors (CNI) mostly in association with steroids in the short-term and mycophenolate mofetil or mTOR inhibitors (everolimus). The occurrence of post-transplant complications related to the immunosuppressive therapy has led to the development of new protocols aimed at protecting renal function and preventing the development of de novo cancer and of dysmetabolic syndrome. However, there is no new class of immunosuppressive drugs in the pipeline able to replace current protocols in the near future. The aim of a full immune tolerance of the graft is rarely achieved since only 20% of selected patients can be weaned successfully off immunosuppression. In the future, immunosuppression will probably be more case oriented aiming to protect the graft from rejection and at reducing the risk of disease recurrence and complications related to immunosuppressive therapy. Such approaches will include strategies aiming to promote stable long-term immunological tolerance of the liver graft.

Autoimmune hepatitis in a murine autoimmune polyendocrine syndrome type 1 model is directed against multiple autoantigens

Autoimmune polyendocrine syndrome type 1 (APS-1) is caused by mutations of the autoimmune regulator (AIRE) gene. Mouse studies have shown that this results in defective negative selection of T cells and defective early seeding of peripheral organs with regulatory T cells (Tregs). Aire deficiency in humans and mice manifests as spontaneous autoimmunity against multiple organs, and 20% of patients develop an autoimmune hepatitis (AIH). To study AIH in APS-1, we generated a murine model of human AIH on a BALB/c mouse background, in which Aire is truncated at exon 2. A subgroup of 24% of mice is affected by AIH, characterized by lymphoplasmacytic and periportal hepatic infiltrates, autoantibodies, elevated aminotransferases, and a chronic and progressive course of disease. Disease manifestation was dependent on specific Aire mutations and the genetic background of the mice. Though intrahepatic Treg numbers were increased and hyperproliferative, the intrahepatic CD4/CD8 ratio was decreased. The targets of the adaptive autoimmune response were polyspecific and not focussed on essential autoantigens, as described for other APS-1-related autoimmune diseases. The AIH could be treated with prednisolone or adoptive transfer of polyspecific Tregs.

CONCLUSION

Development of AIH in APS-1 is dependent on specific Aire mutations and genetic background genes. Autoimmune response is polyspecific and can be controlled by steroids or transfer with Tregs. This might enable new treatment options for patients with AIH.

Outcomes in liver transplantation: does sex matter?

A growing literature has highlighted important differences in transplant-related outcomes between men and women. In the United States there are fewer women than men on the liver transplant waitlist and women are two times less likely to receive a deceased or living-related liver transplant. Sex-based differences exist not only in waitlist but also in post-transplant outcomes, particularly in some specific liver diseases, such as hepatitis C. In the era of individualized medicine, recognition of these differences in the approach to pre and post-liver transplant care may impact short and long-term outcomes.

Posttransplant metabolic syndrome in the withdrawal of immunosuppression in Pediatric Liver Transplant Recipients (WISP-R) pilot trial

Posttransplant metabolic syndrome (PTMS)-obesity, hypertension, elevated triglycerides, low HDL and glucose intolerance-is a major contributor to morbidity after adult liver transplant. This analysis of the Withdrawal of Immunosuppression in Pediatric Liver Transplant Recipients (WISP-R) pilot trial is the first prospective study of PTMS after pediatric liver transplant. Twenty children were enrolled in WISP-R, at median age 8.5 years (IQR 6.4-10.8), and weaned from calcineurin-inhibitor monotherapy. The 12 children who tolerated complete immunosuppression withdrawal were compared to matched historical controls. At baseline, 45% of WISP-R subjects and 58% of controls had at least one component of PTMS. Calcineurin-inhibitor withdrawal in the WISP-R subjects did not impact the prevalence of PTMS components compared to controls. At 5 years, despite weaning off of immunosuppression, 92% of the 12 tolerant WISP-R subjects had at least one PTMS component and 58% had at least two; 33% were overweight or obese, 50% had dyslipidemia, 33% glucose intolerance and 42% systolic hypertension. Overweight/obesity increased the risk of hypertension in all children. Compared to controls, WISP-R tolerant subjects had similar GFR at baseline but did have higher GFR at 2, 3 and 4 years. Further study of PTMS and immunosuppression withdrawal after pediatric liver transplant is warranted.

Transplantation tolerance and its outcome during infections and inflammation

Much progress has been made toward understanding the mechanistic basis of transplantation tolerance in experimental models, which implicates clonal deletion of alloreactive T and B cells, induction of cell-intrinsic hyporesponsiveness, and dominant regulatory cells mediating infectious tolerance and linked suppression. Despite encouraging success in the laboratory, achieving tolerance in the clinic remains challenging, although the basis for these challenges is beginning to be understood. Heterologous memory alloreactive T cells generated by infections prior to transplantation have been shown to be a critical barrier to tolerance induction. Furthermore, infections at the time of transplantation and tolerance induction provide a pro-inflammatory milieu that alters the stability and function of regulatory T cells as well as the activation requirements and differentiation of effector T cells. Thus, infections can result in enhanced alloreactivity, resistance to tolerance induction, and destabilization of the established tolerance state. We speculate that these experimental findings have relevance to the clinic, where infections have been associated with allograft rejection and may be a causal event precipitating the loss of grafts after long periods of stable operational tolerance. Understanding the mechanisms by which infections prevent and destabilize tolerance can lead to therapies that promote stable life-long tolerance in transplant recipients.

HCV-induced immune responses influence the development of operational tolerance after liver transplantation in humans

Pathogen-induced immune responses prevent the establishment of transplantation tolerance in experimental animal models. Whether this occurs in humans as well remains unclear. The development of operational tolerance in liver transplant recipients with chronic hepatitis C virus (HCV) infection allows us to address this question. We conducted a clinical trial of immunosuppression withdrawal in HCV-infected adult liver recipients to elucidate (i) the mechanisms through which allograft tolerance can be established in the presence of an ongoing inflammatory response and (ii) whether anti-HCV heterologous immune responses influence this phenomenon. Of 34 enrolled liver recipients, drug withdrawal was successful in 17 patients (50%). Tolerance was associated with intrahepatic overexpression of type I interferon and immunoregulatory genes and with an expansion of exhausted PD1/CTLA4/2B4-positive HCV-specific circulating CD8(+) T cells. These findings were already present before immunosuppression was discontinued and were specific for HCV infection. In contrast, the magnitude of HCV-induced proinflammatory gene expression and the breadth of anti-HCV effector T cell responses did not influence drug withdrawal outcome. Our data suggest that in humans, persistent viral infections exert immunoregulatory effects that could contribute to the restraining of alloimmune responses, and do not necessarily preclude the development of allograft tolerance.

Markers of acute rejection and graft acceptance in liver transplantation

The evaluation of the immunosuppression state in liver transplanted patients is crucial for a correct post-transplant management and a major step towards the personalisation of the immunosuppressive therapy. However, current immunological monitoring after liver transplantation relies mainly on clinical judgment and on immunosuppressive drug levels, without a proper assessment of the real suppression of the immunological system. Various markers have been studied in an attempt to identify a specific indicator of graft rejection and graft acceptance after liver transplantation. Considering acute rejection, the most studied markers are pro-inflammatory and immunoregulatory cytokines and other proteins related to inflammation. However there is considerable overlap with other conditions, and only few of them have been validated. Standard liver tests cannot be used as markers of graft rejection due to their low sensitivity and specificity and the weak correlation with the severity of histopathological findings. Several studies have been performed to identify biomarkers of tolerance in liver transplanted patients. Most of them are based on the analysis of peripheral blood samples and on the use of transcriptional profiling techniques. Amongst these, NK cell-related molecules seem to be the most valid marker of graft acceptance, whereas the role CD4+CD25+Foxp3+ T cells has still to be properly defined.

Everolimus plus mycophenolate mofetil as initial immunosuppression in liver transplantation

BACKGROUND

The purpose of this study was to assess the efficacy and safety of a de novo immunosuppressive regimen with everolimus (EVL) plus mycophenolate mofetil (MMF) without calcineurin inhibitors (CNI) for liver transplantation. The secondary purpose was to compare the renal function with a control group of patients treated with tacrolimus plus MMF.

METHODS

Sixteen male and 4 female liver transplant patients received immunosuppression with EVL plus MMF without CNI, with induction with steroids and 16 with basiliximab also. In 10 cases it was indicated as induction immunosuppression without CNI as prevention against nephrotoxicity and neurotoxicity or recurrence of hepatocarcinoma in predisposed patients and in another 10 after withdrawing CNI during the immediate post-transplant period, before hospital discharge, as the result of toxicity, mainly nephrotoxicity and neurotoxicity or the presence of hepatocarcinoma with a high risk of recurrence. A control group comprising 31 patients taking tacrolimus plus MMF was included to compare the renal function.

RESULTS

The mean follow-up time was 24 months. One patient had a recurrence of hepatocarcinoma at 8 months after transplant. The cases of nephrotoxicity and neurotoxicity resolved favorably. There were 7 rejections (35%); 2 evolved to chronic rejection with both needing retransplantation, 2 resolved with dose adjustment, and 3 required conversion to CNI. The side effects were hyperlipidemia (25%), wound dehiscence (10%), lymphedema (10%), cytomegalovirus infection (25%), myelotoxicity (25%) and proteinuria >1 g in 1 case (5%). No differences were found in renal function between the two groups.

CONCLUSIONS

This regimen was proven to be efficient to prevent and treat nephrotoxicity and neurotoxicity with an acceptable tolerability profile. However, the high associated rejection rate indicates that great caution is required in its use during the immediate post-transplant period. It is advisable to associate the regimen with low doses of CNI and to have agile methods available to monitor EVL to enable rapid dose adjustment.

Organ-sparing Surgery in Treating Patients with Liposarcoma of the Spermatic Cord: Institutional Experience and Pooled Analysis

BACKGROUND

Liposarcoma of the spermatic cord is rare and frequently misdiagnosed. The standard therapeutic approach has been radical inguinal orchiectomy with wide local resection of surrounding soft tissues. The current trend of organ preservation in the treatment of several cancers has started to evolve. Herein we present our testis-sparing surgery experience in the treatment of spermatic cord liposarcoma and a pooled analysis on this topic.

MATERIALS AND METHODS

Clinical information from patient receiving organ-sparing surgery was described. Clinical studies evaluating this issue were identified by using a predefined search strategy, e.g., Pubmed database with no restriction on date of published papers. The literature search used the following terms: epidemiology , surgery , chemotherapy , radiotherapy , testis sparing surgery, spermatic cord sarcomas/ liposarcomas.

RESULTS

Patient received a complete excision of the lesion, preserving the spermatic cord and the testis. The final pathological report showed a well differentiated liposarcoma with negative surgical margins and no signs of local invasion. After 2-year of follow-up, there was no evidence of local recurrence. Since the first case reported in 1952, a total of about 200 well-documented spermatic cord liposarcoma cases have been published in English literature. Among these patients, only three instances were reported to have received an organ-sparing surgery in the treatment of spermatic cord liposarcoma.

CONCLUSIONS

Radical inguinal orchiectomy and resection of the tumor with a negative microscopic margin is the recommended treatment for liposarcoma of the spermatic cord. But for small, especially well-differentiated, lesions, testis-sparing surgery might be a good option if an adequate negative surgical margin is assured.

Is there such a thing as protocol immunosuppression in liver transplantation?

Protocol immunosuppression in liver transplantation is largely an outdated concept. Immunosuppression is now personalized to the individual patient on the basis of several factors including underlying etiology of original liver disease (e.g., HCV, hepatocellular carcinoma), renal function, metabolic co-morbidities and the patient's immunological state. These include omission of corticosteroids in HCV infection and those with major metabolic risk factors, the minimization of calcineurin inhibitors in the presence of renal dysfunction and the use of mTOR inhibitors in patients with malignancy. The basis for such decision-making is discussed in this editorial.

Belatacept treatment for two yr after liver transplantation is not associated with operational tolerance

Belatacept was recently evaluated in liver transplantation (LT) in a phase II multicenter trial, which was terminated prematurely. Patients were more than two yr post-LT at the time. As high rates of spontaneous tolerance after LT have been reported and as belatacept has marked immunomodulatory effects, we decided to maintain the belatacept patients enrolled at our center (n = 4) on MMF monotherapy. All belatacept patients on MMF monotherapy developed graft dysfunction consistent with acute rejection after a mean period of 10.3 (7-14) wk. Patients were therefore switched to triple therapy with CNI, MMF, and corticosteroids. Graft dysfunction resolved within 1-3 wk after switch. At the time of belatacept discontinuation, mean eGFR was 105.1 mL/min/1.73 m² (92.1-118.9) in belatacept patients compared to 58 mL/min/1.73 m² (36.1-98.2) in controls (p = 0.022). One yr after the switch to CNI therapy, eGFR had declined by 27.4 mL (19.2-39.3; p = 0.008). Thus, LT patients treated with belatacept show superior kidney function that declines upon institution of CNIs. MMF monotherapy following withdrawal of belatacept is associated with a high incidence of graft dysfunction. Belatacept has no obvious immunomodulatory effects in LT recipients that would be sufficient to allow drug withdrawal with a high rate of success.

Current strategies for immunosuppression following liver transplantation

BACKGROUND

New strategies for immunosuppression (IS) after liver transplantation (LTx) are in part responsible for the increased patient and graft survival seen over time. With a few basic exceptions-notably the continued use of steroids and calcineurin inhibitors (CNIs)-IS drugs and regimens being used today are different from those used 30 years ago. While graft loss due to acute or chronic rejection has become rare, the side effect burden of IS drugs exerts a significant toll on patients.

CONCEPTS/TRENDS

CNIs continue to form the backbone of IS regimens, although their use is hampered by nephrotoxicity and other adverse effects. Consequently, a variety of CNI reduction or withdrawal strategies have formed the basis of clinical trials or entered into clinical practice. These trials have included the use of everolimus, an mTOR inhibitor, and anti-interleukin-2 receptor antibodies. Basiliximab, as well as other lymphocyte nondepleting and depleting agents, have shown benefit in induction regimens.

SUMMARY

Along with steroid reduction or elimination, current strategies for IS after LTx continue to explore novel combinations of agents, with an aim toward striking a balance between diminution of rejection and the need for avoiding adverse effects of the IS drugs. Long-term maintenance strategies are also discussed in this review, as is development of tolerance and antibody-mediated rejection.

Immunosuppression withdrawal following liver transplantation

Current immunosuppression regimens in liver transplantation provide excellent short-term survival rates but have many deleterious long-term side effects. They are therefore associated with the higher mortality and morbidity seen in liver transplant recipients compared to the general population and the notion that many liver transplant recipients are over-immunosuppressed is widely accepted. Liver allografts show a greater resistance to alloimmune responses than other solid organ transplants and recent research suggests up to 60% of highly selected recipients could wean off immunosuppression completely. In this review, we look at the evidence from immunosuppression withdrawal trials, the potential benefits of immunosuppression withdrawal and the identification of tolerant transplant recipients.

A Three-Gene Assay for Monitoring Immune Quiescence in Kidney Transplantation

Organ transplant recipients face life-long immunosuppression and consequently are at high risk of comorbidities. Occasionally, kidney transplant recipients develop a state of targeted immune quiescence (operational tolerance) against an HLA-mismatched graft, allowing them to withdraw all immunosuppression and retain stable graft function while resuming immune responses to third-party antigens. Methods to better understand and monitor this state of alloimmune quiescence by transcriptional profiling may reveal a gene signature that identifies patients for whom immunosuppression could be titrated to reduce patient and graft morbidities. Therefore, we investigated 571 unique peripheral blood samples from 348 HLA-mismatched renal transplant recipients and 101 nontransplant controls in a four-stage study including microarray, quantitative PCR, and flow cytometry analyses. We report a refined and highly validated (area under the curve, 0.95; 95% confidence interval, 0.92 to 0.97) peripheral blood three-gene assay (KLF6, BNC2, CYP1B1) to detect the state of operational tolerance by quantitative PCR. The frequency of predicted alloimmune quiescence in stable renal transplant patients receiving long-term immunosuppression (n=150) was 7.3% by the three-gene assay. Targeted cell sorting of peripheral blood from operationally tolerant patients showed a significant shift in the ratio of circulating monocyte-derived dendritic cells with significantly different expression of the genes constituting the three-gene assay. Our results suggest that incorporation of patient screening by specific cellular and gene expression assays may support the safety of drug minimization trials and protocols.

Spectrum of diverse genomic alterations define non-clear cell renal carcinoma subtypes

To further understand the molecular distinctions between kidney cancer subtypes, we analyzed exome, transcriptome and copy number alteration data from 167 primary human tumors that included renal oncocytomas and non-clear cell renal cell carcinomas (nccRCCs), consisting of papillary (pRCC), chromophobe (chRCC) and translocation (tRCC) subtypes. We identified ten significantly mutated genes in pRCC, including MET, NF2, SLC5A3, PNKD and CPQ. MET mutations occurred in 15% (10/65) of pRCC samples and included previously unreported recurrent activating mutations. In chRCC, we found TP53, PTEN, FAAH2, PDHB, PDXDC1 and ZNF765 to be significantly mutated. Gene expression analysis identified a five-gene set that enabled the molecular classification of chRCC, renal oncocytoma and pRCC. Using RNA sequencing, we identified previously unreported gene fusions, including ACTG1-MITF fusion. Ectopic expression of the ACTG1-MITF fusion led to cellular transformation and induced the expression of downstream target genes. Finally, we observed upregulation of the anti-apoptotic factor BIRC7 in MiTF-high RCC tumors, suggesting a potential therapeutic role for BIRC7 inhibitors.

Disappearance of T Cell-Mediated Rejection Despite Continued Antibody-Mediated Rejection in Late Kidney Transplant Recipients

The prevalent renal transplant population presents an opportunity to observe the adaptive changes in the alloimmune response over time, but such studies have been limited by uncertainties in the conventional biopsy diagnosis of T cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR). To circumvent these limitations, we used microarrays and conventional methods to investigate rejection in 703 unselected biopsies taken 3 days to 35 years post-transplant from North American and European centers. Using conventional methods, we diagnosed rejection in 205 biopsy specimens (28%): 67 pure TCMR, 110 pure ABMR, and 28 mixed (89 designated borderline). Using microarrays, we diagnosed rejection in 228 biopsy specimens (32%): 76 pure TCMR, 124 pure ABMR, and 28 mixed (no borderline). Molecular assessment confirmed most conventional diagnoses (agreement was 90% for TCMR and 83% for ABMR) but revealed some errors, particularly in mixed rejection, and improved prediction of failure. ABMR was strongly associated with increased graft loss, but TCMR was not. ABMR became common in biopsy specimens obtained >1 year post-transplant and continued to appear in all subsequent intervals. TCMR was common early but progressively disappeared over time. In 108 biopsy specimens obtained 10.2-35 years post-transplant, TCMR defined by molecular and conventional features was never observed. We conclude that the main cause of kidney transplant failure is ABMR, which can present even decades after transplantation. In contrast, TCMR disappears by 10 years post-transplant, implying that a state of partial adaptive tolerance emerges over time in the kidney transplant population.

The natural history of glycogen storage disease types VI and IX: Long-term outcome from the largest metabolic center in Canada

OBJECTIVES

Glycogen storage disease (GSD) types VI and IX are caused by phosphorylase system deficiencies. To evaluate the natural history and long-term treatment outcome of the patients with GSD-VI and -IX, we performed an observational retrospective case study of 21 patients with confirmed diagnosis of GSD-VI or -IX.

METHODS

All patients with GSD-VI or -IX, diagnosed at The Hospital for Sick Children, were included. Electronic and paper charts were reviewed for clinical features, biochemical investigations, molecular genetic testing, diagnostic imaging, long-term outcome and treatment by two independent research team members. All information was entered into an Excel database.

RESULTS

We report on the natural history and treatment outcomes of the 21 patients with GSD-VI and -IX and 16 novel pathogenic mutations in the PHKA2, PHKB, PHKG2 and PYGL genes. We report for the first time likely liver adenoma on liver ultrasound and liver fibrosis on liver biopsy specimens in patients with GSD-VI and mild cardiomyopathy on echocardiography in patients with GSD-VI and -IXb.

CONCLUSION

We recommend close monitoring in all patients with GSD-VI and -IX for the long-term liver and cardiac complications. There is a need for future studies if uncooked cornstarch and high protein diet would be able to prevent long-term complications of GSD-VI and -IX.

Is minimal, [almost] steroid-free immunosuppression a safe approach in adult liver transplantation? Long-term outcome of a prospective, double blind, placebo-controlled, randomized, investigator-driven study

OBJECTIVE

To investigate the safety of minimal immunosuppression (IS) in liver transplantation (LT).

BACKGROUND

The lack of long-term follow-up studies, including pathologic data, has led to a protean handling of IS in LT.

METHODS

Between February 2000 and September 2004, 156 adults were enrolled in a prospective, randomized, double-blind, placebo-controlled minimization trial comparing tacrolimus placebo (TAC-PLAC) and TAC short-term steroid (TAC-STER) IS. All patients had a minimum clinical, biochemical, and histological follow-up of 5 years.

RESULTS

Five-year actual patient and graft survival rates in TAC-PLAC and TAC-STER groups were 78.1% and 82.1% (P=0.89) and 74.2% and 76.9% (P=0.90), respectively. Five-year biopsies were available in 112 (89.6%) of 125 survivors. Twelve patients refused a biopsy because of their excellent evolution; tissue material was insufficient in 1 patient; 11 had normal liver tests; and 2 patients had developed alcoholic and secondary biliary cirrhosis. Histology was normal in 44 (39.3%) patients; 35 (31.3%) had disease recurrence. The remaining biopsies showed nonspecific chronic hepatitis (14.3%), mild inflammatory infiltrates (10.7%), and steatosis (3.5%). All findings were equally distributed between both groups. In each group, 3 patients (4.8%) presented with acute cellular rejection after the first year and only 1 (0.9%) TAC-PLAC patient developed chronic rejection after IS withdrawal because of pneumonitis. Arterial hypertension, diabetes mellitus, renal insufficiency, hypercholesterolemia, gout, and obesity were equally low in both groups.

CONCLUSIONS

Excellent long-term results can be obtained under minimal IS and absence of steroids. TAC-based monotherapy is feasible in most adult liver recipients until 5 years of follow-up.

Intrahepatic regulatory T cells in autoimmune hepatitis are associated with treatment response and depleted with current therapies

BACKGROUND & AIMS

Autoimmune hepatitis (AIH) is a chronic autoimmune liver disease usually requiring life-long immunosuppression. The mechanisms for disease initiation and chronicity are largely unknown. A contribution of deficient regulatory T cells (Tregs) in the blood was controversially discussed recently. So far investigations in the target organ have been limited to single parameter analysis in untreated AIH.

METHODS

We retrospectively analysed the pattern of liver infiltrating T, B and regulatory T cells quantitatively with simultaneous multicolour immunofluorescence before (n=45) and under (n=31) therapy in adult AIH type 1 (AIH-1) patients.

RESULTS

Intrahepatic CD4(+) cells dominate over CD8(+) at diagnosis, but with increasing disease activity the CD4(+)/CD8(+) ratio approached one. While there is no change of Tregs in the blood, they are enriched with effector T cells (Teffs) within the liver of patients with untreated AIH-1 with a constant Treg/Teff ratio. Even more importantly, immunosuppression mostly with steroids and azathioprine caused a disproportional loss of intrahepatic Tregs. Patients reaching biochemical remission had higher intrahepatic Treg/Teff and Treg/B cell ratios compared to patients failing to reach remission. In vitro proliferation of Tregs seemed to be more suppressed by prednisolone than expansion of Teffs. Furthermore, intraportal B cells correlated with serum IgG suggesting an autochthonous intrahepatic IgG production.

CONCLUSIONS

Intrahepatic Tregs are rather enriched than numerically deficient in untreated AIH-1. The disproportional decrease of intrahepatic Tregs during therapy might explain high relapse rates after discontinuation of immunosuppression. Thus, future therapies increasing intrahepatic immunoregulation might be better suited for long-term control of AIH.