Risk factors for chronic rejection after pediatric liver transplantation

Pediatric Liver Transplantation: Selection Criteria and Post-transplant Medical Management

Pediatric liver transplantation remains the gold standard for life-threatening acute and chronic liver diseases and multiple liver-based inherited metabolic defects. Advances in surgical techniques, better perioperative care and immunosuppression regimes have resulted in excellent long-term graft and patient survival. The success of pediatric liver transplantation does however bring the additional challenge of long-term patient outcomes including graft hepatitis-related fibrosis and suboptimal biopsychosocial outcomes. In this review, authors will explore the current landscape of pediatric liver transplantation including indications, timing of referral for liver transplantation, surgical techniques and long-term outcomes such as recurrence of pre-transplant liver disease, idiopathic graft hepatitis and biopsychosocial outcomes. Ultimately, early identification and management of potential issues long-term helps ensure our recipients achieve a "meaningful survival".

Factors Associated with Chronic Rejection in Liver Transplant Recipients: A Retrospective Cohort Study From Shiraz Organ Transplant Center

OBJECTIVES

Identification of chronic rejection risk factors in liver transplant recipients is critical for early detection and prevention of further graft loss. We investigated characteristics of liver transplant recipients who had experienced chronic rejection and the associated risk factors versus patients without chronic rejection.

MATERIALS AND METHODS

Data from 3022 adult liver transplant recipients between 2011 and 2018 were analyzed; of these, 80 patients had experienced chronic rejection. The control group included 98 randomly selected liver transplant recipients who did not have chronic rejection.

RESULTS

The age of the recipients and the donors was significantly lower in the group with chronic rejection versus the group without chronic rejection.The results indicated that chronic rejection was significantly associated with the sex of the recipients (hazard ratio 3.2, 95% CI 1.77-6.08; P < .001) and with the sex concordance between the recipients and donors (hazard ratio 2.93, 95% CI 1.67-5.13; P < .001, respectively). Also, in the group without chronic rejection, there were no male donors; however, the group with chronic rejection had mostly male donors (P <.001). Cold ischemia time was longer in patients with chronic rejection versus that shown in the control group (P = .031), and there was a significant difference between the 2 groups in acute rejection frequency (P < .001).

CONCLUSIONS

Recipient sex and sex concordance were independent risk factors for chronic rejection. Most transplantrecipients with chronic rejection responded to medicaltreatment, and the rate of graftloss was low among our recipients.

Evolving challenges with long-term care of liver transplant recipients

The number of liver transplants (LT) performed worldwide continues to rise, and LT recipients are living longer post-transplant. This has led to an increasing number of LT recipients requiring lifelong care. Optimal care post-LT requires careful attention to both the allograft and systemic issues that are more common after organ transplantation. Common causes of allograft dysfunction include rejection, biliary complications, and primary disease recurrence. While immunosuppression prevents rejection and reduces incidences of some primary disease recurrence, it has detrimental systemic effects. Most commonly, these include increased incidences of metabolic syndrome, various malignancies, and infections. Therefore, it is of utmost importance to optimize immunosuppression regimens to prevent allograft dysfunction while also decreasing the risk of systemic complications. Institutional protocols to screen for systemic disease and heightened clinical suspicion also play an important role in providing optimal long-term post-LT care. In this review, we discuss these common complications of LT as well as unique considerations when caring for LT recipients in the years after transplant.

Understanding humoral immunity and multiple sclerosis severity in Black, and Latinx patients

People identified with Black/African American or Hispanic/Latinx ethnicity are more likely to exhibit a more severe multiple sclerosis disease course relative to those who identify as White. While social determinants of health account for some of this discordant severity, investigation into contributing immunobiology remains sparse. The limited immunologic data stands in stark contrast to the volume of clinical studies describing ethnicity-associated discordant presentation, and to advancement made in our understanding of MS immunopathogenesis over the past several decades. In this perspective, we posit that humoral immune responses offer a promising avenue to better understand underpinnings of discordant MS severity among Black/African American, and Hispanic/Latinx-identifying patients.

Recipient Age Predicts 20-Year Survival in Pediatric Liver Transplant

INTRODUCTION

Pediatric liver transplant recipients have demonstrated excellent long-term survival. The purpose of this analysis is to investigate factors associated with 20-year survival to identify areas for improvement in patient care.

METHODS

Kaplan-Meier with log-rank test as well as univariate and multivariate logistic regression methods were used to retrospectively analyze 4,312 liver transplant recipients under the age of 18 between September 30, 1987 and March 9, 1998. Our primary endpoint was 20-year survival among one-year survival.

RESULTS

Logistic regression analysis identified recipient age as a significant risk factor, with recipients below 5 years old having a higher 20-year survival rate (p < 0.001). A preoperative primary diagnosis of a metabolic dysfunction was found to be protective compared to other diagnoses (OR 1.64, CI 1.20-2.25). African-American ethnicity (OR 0.71, CI 0.58-0.87) was also found to be a risk factor for mortality. Technical variant allografts (neither living donor nor cadaveric) were not associated with increased or decreased rates of 20-year survival.

CONCLUSIONS

Our analysis suggests that long-term survival is inversely correlated with recipient age following pediatric liver transplant. If validated with further studies, this conclusion may have profound implications on the timing of pediatric liver transplantation.

Adaptation of Imaging Mass Cytometry to Explore the Single Cell Alloimmune Landscape of Liver Transplant Rejection

Rejection continues to be an important cause of graft loss in solid organ transplantation, but deep exploration of intragraft alloimmunity has been limited by the scarcity of clinical biopsy specimens. Emerging single cell immunoprofiling technologies have shown promise in discerning mechanisms of autoimmunity and cancer immunobiology. Within these applications, Imaging Mass Cytometry (IMC) has been shown to enable highly multiplexed, single cell analysis of immune phenotypes within fixed tissue specimens. In this study, an IMC panel of 10 validated markers was developed to explore the feasibility of IMC in characterizing the immune landscape of chronic rejection (CR) in clinical tissue samples obtained from liver transplant recipients. IMC staining was highly specific and comparable to traditional immunohistochemistry. A single cell segmentation analysis pipeline was developed that enabled detailed visualization and quantification of 109,245 discrete cells, including 30,646 immune cells. Dimensionality reduction identified 11 unique immune subpopulations in CR specimens. Most immune subpopulations were increased and spatially related in CR, including two populations of CD45+/CD3+/CD8+ cytotoxic T-cells and a discrete CD68+ macrophage population, which were not observed in liver with no rejection (NR). Modeling via principal component analysis and logistic regression revealed that single cell data can be utilized to construct statistical models with high consistency (Wilcoxon Rank Sum test, p=0.000036). This study highlights the power of IMC to investigate the alloimmune microenvironment at a single cell resolution during clinical rejection episodes. Further validation of IMC has the potential to detect new biomarkers, identify therapeutic targets, and generate patient-specific predictive models of clinical outcomes in solid organ transplantation.

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

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

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

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

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

Living Donor Versus Deceased Donor Pediatric Liver Transplantation: A Systematic Review and Meta-analysis

Reduced-size deceased donors and living donor liver transplantation (LDLT) can address the organ shortage for pediatric liver transplant candidates, but concerns regarding technical challenges and the risk of complications using these grafts have been raised. The aim of this study was to compare outcomes for pediatric LDLT and deceased donor liver transplantation (DDLT) via systematic review.

METHODS

A systematic literature search was performed to identify studies reporting outcomes of pediatric (<18 y) LDLT and DDLT published between 2005 and 2019. A meta-analysis was conducted to examine peri- and postoperative outcomes using fixed- and random-effects models.

RESULTS

Overall, 2518 abstracts were screened, and 10 studies met criteria for inclusion. In total, 1622 LDLT and 6326 DDLT pediatric patients from 4 continents were examined. LDLT resulted in superior patient survival when compared with DDLT at 1, 3, and 5 y post-LT (1-y hazard ratio: 0.58, 95% confidence interval [CI] 0.47-0.73, P < 0.0001). Similarly, LDLT resulted in superior graft survival at all time points post-LT when compared with DDLT (1-y hazard ratio: 0.56 [95% CI 0.46-0.68], P < 0.0001]. The OR for vascular complications was 0.73 (95% CI 0.39-1.39) and 1.31 (95% CI 0.92-1.86) for biliary complications in LDLT compared with DDLT, whereas LDLT was associated with lower rates of rejection (OR: 0.66 [95% CI 0.45-0.96], P = 0.03).

CONCLUSIONS

This meta-analysis demonstrates that LDLT may offer many advantages when compared with DDLT in children and suggests that LDLT should continue to be expanded to optimize outcomes for pediatric LT candidates.

Glutathione S-Transferase T1 Mismatch Is a Risk Factor for Chronic Ductopenic Rejection of Liver Allografts

The underlying causes of chronic rejection (CR) after liver transplantation (LT) are not completely known. The main aim of this study was to explore the involvement of the minor histocompatibility antigen glutathione S-transferase T1 (GSTT1) in CR. We retrospectively studied 611 patients who underwent LTs at University Hospital Virgen del Rocío between 2003 and 2016 with a median follow-up of 7.4 ± 4.2 years. The GSTT1 genotype was determined by polymerase chain reaction. We defined GSTT1 mismatch as a specific donor/recipient combination in which a recipient who was homozygous for the deletion allele received a transplant from a positive donor. The prevalence of CR in our whole cohort was 11.6% (71/611), and the prevalence in the GSTT1-mismatched group was 18.8% (16/85) versus 10.5% (55/526) in the GSTT1-matched group. In the cyclosporine A (CsA) group, the prevalence was 26.3% (26/99), much higher than the 8.8% (45/512) observed in the tacrolimus (Tac) group. For statistical analysis, the patients were distributed into 2 groups: group 1, regarded as GSTT1 mismatched, which included the donor (D)+/recipient (R)- allelic combination; and group 2, regarded as GSTT1 matched, which included the other allelic combinations of D+/R+, D-/R-, and D-/R+. All relevant clinical information was collected, and a diagnosis of CR was always confirmed by liver biopsy. GSTT1 mismatch (hazard ratio [HR], 1.99; 95% confidence interval [CI], 1.08-3.66; P = 0.03) and use of CsA/Tac (P < 0.001) were independent risk factors for CR. CR increased the risk of mortality (HR, 2; 95% CI, 1.2-3.6; P = 0.01). Out of the 71 CR patients, 12 (16.9%) needed retransplantation. In conclusion, the GSTT1 D+/R- allelic mismatch is an independent risk factor for CR. A long follow-up of LT patients is recommended because the incidence of CR in adults seems to be underestimated.

International Liver Transplantation Society Consensus Statement on Immunosuppression in Liver Transplant Recipients

Effective immunosupression management is central to achieving optimal outcomes in liver transplant recipients. Current immunosuppression regimens and agents are highly effective in minimizing graft loss due to acute and chronic rejection but can also produce a substantial array of toxicities. The utilization of immunosuppression varies widely, contributing to the wide disparities in posttransplant outcomes reported between transplant centers. The International Liver Transplantation Society (ILTS) convened a consensus conference, comprised of a global panel of expert hepatologists, transplant surgeons, nephrologists, and pharmacologists to review the literature and experience pertaining to immunosuppression management to develop guidelines on key aspects of immunosuppression. The consensus findings and recommendations of the ILTS Consensus guidelines on immunosuppression in liver transplant recipients are presented in this article.

Short-term outcomes of paediatric liver transplant recipients after transition to Adult Healthcare Service

BACKGROUND & AIMS

Survival rates after liver transplantation (LT) in paediatric recipients have significantly improved over time. However, data regarding outcomes after transition from Paediatric to Adult Healthcare Service (AHS) are still lacking. Therefore, we aimed to prospectively evaluate the outcome of LT recipients after transition, to access patients' non-adherence and identify potential risk factors for non-adherence.

METHODS

All consecutive adolescent LT recipients moving to the AHS at Padua University Hospital were evaluated between 2010 and 2015. Demographic data, liver function tests, incidence of acute or chronic rejection episodes and adherence to medical prescription, were prospectively evaluated. An educational pilot study was implemented since 2015 to foster adherence during transition.

RESULTS

In all, 32 patients (M/F 16/16, median age: 23 years) were evaluated. Median interval time between LT and transition was 15 years (range: 1-26 years). The main indication for LT was biliary atresia (31%), whereas immunosuppression regimen was tacrolimus-based in 75%. After a median follow-up of 29 months (range: 12-83), no significant modifications of liver function tests were observed. Biopsy-proven chronic rejection was diagnosed in 6/32 (18%) of patients, who had higher standard deviation of tacrolimus trough level than patients without (1.5 vs 1, P = .03). Non-adherence was reported in 8/32 (25%) of patients and was significantly associated with alcohol consumption (P = .003). Patient and graft survival were 96% and 93%, respectively.

CONCLUSIONS

Adolescent LT patients who undergo transition to the AHS have good long-term outcomes. However, a multidisciplinary approach aiming at fostering adherence should be used.

Cytomegalovirus Infection under a Hybrid Strategy in Pediatric Liver Transplantation: A Single-Center Experience

PURPOSE

To evaluate the outcomes of a hybrid prophylactic strategy to prevent cytomegalovirus (CMV) disease in pediatric liver transplantation (LT) patients.

METHODS

CMV DNAemia was regularly monitored by quantitative nucleic acid amplification test (QNAT) and was quantified in all children. CMV infection and disease were defined according to the International Consensus Guidelines. The hybrid strategy against CMV infection consisted of universal 3-week prophylaxis and preemptive treatment of intravenous ganciclovir regardless of the recipient's serostatus.

RESULTS

A total of 143 children who underwent living donor LT were managed using the hybrid strategy. The overall incidence of CMV infection by QNAT was 48.3% (n=69/143). The highest CMV DNAemia positivity was observed in 49.2% (n=60/122) of children in the D+/R+ group, followed by 46.7% (n=7/15) in the D+/R- group. CMV disease was noted in 26.1% (n=18/69) patients. Forty-three (62.3%) children had undergone preemptive therapy consisting of intravenous ganciclovir. No symptomatic patients developed tissue-invasive disease, resulting in no CMV-associated mortality.

CONCLUSION

The incidence of CMV infection was high in pediatric LT patients despite the hybrid strategy. However, tissue-invasive disease in pediatric LT did not occur.

Comparative Peripheral Blood T Cells Analysis Between Adult Deceased Donor Liver Transplantation (DDLT) and Living Donor Liver Transplantation (LDLT)

Background

T lymphocytes are an essential component of allograft rejection and tolerance. The aim of the present study was to analyze and compare the characteristics of T cell subsets in patients who underwent deceased donor liver transplantation (DDLT) versus living donor liver transplantation (LDLT).

Material/Methods

Between April 2013 and June 2014, 64 patients underwent adult liver transplantation. The distribution of peripheral blood T lymphocyte subsets before transplantation and at 4, 8, 12, and 24 weeks post-transplantation were monitored serially.

Results

In the serial peripheral blood samples, the absolute CD3+ T cell counts in the LDLT group were higher than those in the DDLT group (p=0.037). The CD4+, CD8+, CD4/CD8, Vδ1, Vδ2, and γδ T cell counts did not change significantly over time in either group. The Vδ1/Vδ2 ratio was higher in patients with cytomegalovirus (CMV) infection than in patients without CMV infection (0.12 versus 0.26; p=0.033). The median absolute CD3+ and CD8+ T cell counts in patients with biopsy-proven acute rejection (BPAR) were 884 (range, 305–1,320) and 316 (range, 271–1,077), respectively, whereas they were 320 (range, 8–1,167) and 257 (range, 58–1,472) in patients without BPAR. The absolute CD3+ and CD8 T cell counts were higher in patients with BPAR than in patients without BPAR (p=0.007 and p=0.039, respectively).

Conclusions

With the exception of CD3+ T cells, T cell populations did not differ significantly between patients who received DDLT versus LDLT. In liver transplantation patients, CMV infection and BPAR were closely associated with T cell population changes.

Effectiveness of Preemptive Therapy for Cytomegalovirus Disease in Pediatric Liver Transplantation

BACKGROUND

Most pediatric liver transplantation (LT) centers administer long courses of prophylaxis against cytomegalovirus (CMV) without evidence of benefit and with significant drug exposure and costs. We aimed at evaluating overall outcomes, direct and putative indirect effects of CMV, possible impact of viremia and risk factors for CMV infection in pediatric LT recipients managed with ganciclovir-based preemptive therapy (PET).

METHODS

The records of all the children who underwent LT between 2008 and 2014 were retrospectively analyzed.

RESULTS

One hundred children were included. Three children had CMV disease; no CMV-related death or graft loss was recorded. The only identified risk factor for CMV infection was the donor/recipient serostatus (odds ratio, 17.23; 95% confidence interval, 1.88-157.87; P = 0.012), while viremia per se did not worsen LT outcomes, such as the incidence of acute rejection, Epstein-Barr virus infection, sepsis, biliary and vascular complications, nor graft dysfunction/loss or death at 3 and 5 years after LT. When compared with a historical cohort of children receiving ganciclovir prophylaxis, PET did not differ from prophylaxis for any of the selected outcomes, but was rather associated with lower antiviral drug exposure (6.4 ± 13 days vs 38.6 ± 14 days, P < 0.0001) and cost per patient (2.2 ± 3.9 k&OV0556; vs 6.6 ± 8.2 k&OV0556;, P = 0.001).

CONCLUSIONS

PET is effective in controlling CMV in children receiving LT, with lower costs and lower exposure to antivirals.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Racial and socioeconomic disparities in pediatric and young adult liver transplant outcomes

Racial and socioeconomic disparities exist in liver transplantation (LT) outcomes among adults, but little research exists for pediatric LT populations. We examined racial differences in graft survival and mortality within a retrospective cohort of pediatric and young adult LT recipients at a large children's transplant center in the Southeast between 1998 and 2011. The association between race/ethnicity and rates of graft failure and mortality was examined with Cox proportional hazards models that were adjusted for demographic and clinical factors as well as individual-level and census tract-level socioeconomic status (SES). Among the 208 LT recipients, 51.0% were white, 34.6% were black, and 14.4% were other race/ethnicity. Graft survival and patient survival were higher for whites versus minorities 1, 3, 5, and 10 years after transplantation. The 10-year graft survival rates were 84% [95% confidence interval (CI) = 76%-91%] for white patients, 60% (95% CI = 46%-74%) for black patients, and 49% (95% CI = 23%-77%) for other race/ethnicity patients. The 10-year patient survival rates were 92% (95% CI = 84%-96%), 65% (95% CI = 52%-79%), and 76% (95% CI = 54%-97%) for the white, black, and other race/ethnicity groups, respectively. In analyses adjusted for demographic, clinical, and socioeconomic characteristics, the rates of graft failure [black: hazard ratio (HR) = 2.59, 95% CI = 1.29-5.45; other: HR = 3.01, 95% CI = 1.23-7.35] and mortality (black: HR = 4.24, 95% CI = 1.54-11.69; other: HR = 3.09, 95% CI = 0.78-12.19) were higher for minority groups versus whites. In conclusion, at a large pediatric transplant center in the Southeastern United States, racial/ethnic disparities exist in pediatric and young adult LT outcomes that are not fully explained by measured SES and clinical factors.

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.

Current issues in pediatric liver transplantation

Pediatric patients with ESLD requiring liver transplantation often have a multitude of comorbidities ranging from pulmonary hypertension to renal and cardiovascular insufficiency that impairs our ability to safely care for these critically ill children. As organ allocation techniques advance, many of these patients may be healthier on arrival to the operating room. However, postoperative surgical complications and immunosuppressive regimens still daunt us. As we continue to care for these challenging patients, hopefully, advances in ESLD management and technology will dramatically improve outcomes in the future.

Markers of operational immune tolerance after pediatric liver transplantation in patients under immunosuppression

A prospective identification of the estimated 20-50% of pediatric LTX recipients developing operational tolerance would be of great clinical advantage. So far markers of immune tolerance - T-cell subpopulations or gene expression profiles - have been investigated only retrospectively in successfully weaned patients. Fifty children aged 8-265 months (median 89) were investigated 1-180 months (median 44) after LTX under ongoing immunosuppression. T-cell subpopulations were measured during regular post-transplant visits using FACS (Vδ1- vs. Vδ2-γδ-T cells and Tregs). A Vδ1/Vδ2-γδ-T-cell ratio ≥1.42 previously reported in operational tolerance was found in 12 of 50 (24%) patients. In analogy, a Treg count ≥44 per μL was found in 35 of 50 (70%) patients and a Treg proportion ≥2.23% of CD3(+) -T cells in 39 of 50 (78%) patients. Only 9 of 50 patients (18%) fulfilled both criteria. The parameters Vδ1/Vδ2-γδ-T-cell ratio and Tregs were not significantly correlated to each other or with donor type or immunosuppression. Vδ1/Vδ2-γδ-T-cell ratio was more stable in serial examinations compared with Treg analyses. The observed proportion of 18% pediatric LTX patients with potential operational tolerance is in accordance with previous reports. However, clinical experience shows that rejections may happen even after long-time weaning of immunosuppression. This suggests that operational tolerance is a dynamic process, with uncertain prediction by Vδ1/Vδ2-γδ-T-cell ratio and/or Tregs under immunosuppression.

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.

The association between cytomegalovirus immune globulin and long-term recipient and graft survival following liver transplantation

The association between cytomegalovirus (CMV) immune globulin (CMVIG) and long-term clinical outcomes has not been well defined. We examined the association between CMVIG and long-term recipient and graft survival in liver transplant recipients. Data were from the Scientific Registry of Transplant Recipients and included recipients transplanted between January 1995 and October 2008; follow-up was through March 2009. All recipients≤80 years of age with primary, single-organ liver transplants, given CMVIG with (n=2350) or without antivirals (n=455), antivirals without CMVIG (n = 32,939), or no CMV prophylaxis (n=28,508) before discharge were included. Kaplan-Meier analysis was used to examine rates of acute rejection (AR), graft loss, and death, over 7 years post transplantation. The adjusted risk of AR, graft loss, and death associated with CMVIG with and without antivirals vs. no prophylaxis was estimated using the Cox proportional hazards regression. In the univariate analysis, CMVIG, with and without antivirals, was associated with increased AR rates, but decreased mortality; CMVIG with antivirals was also associated with decreased graft loss compared with no prophylaxis. From the multivariable model, CMVIG with antivirals was associated with increased risk for AR, but decreased risk for graft loss and death; after adjustment, the association between CMVIG alone and mortality was not significant. CMVIG with antivirals is associated with increased risk of AR but greater long-term patient and graft survival after liver transplantation.

Towards minimizing immunosuppression in pediatric liver transplant recipients

Immunosuppression regimens after liver transplantation focus mainly on preventing rejection and subsequent graft loss. However, in children, morbidity and mortality rates from infections exceed those from rejection after transplant, and immunosuppression can hinder growth, renal function, and graft tolerance. We hypothesized that early steroid withdrawal, with a primary aim of TAC monotherapy would yield no penalty in terms of rejection and graft loss, while reducing risks of infection and maximizing growth. We prospectively evaluated 64 consecutive pediatric liver transplant recipients. One yr patient/graft survival was 93/90%, respectively. At one yr post-transplant, 75.4% of patients were on TAC monotherapy. No deaths or graft losses were caused by infection. Sixty-one percent of patients had at least one episode of rejection, most within three months following transplant and 3.8% were treated for chronic rejection. One non-compliant adolescent died from chronic rejection. CMV, EBV, and lymphoproliferative disease rates were 3.1%, 5.3%, 1.8%, respectively. Pretransplant and one yr post-transplant glomerular filtration rates were unchanged. One yr improved catch-up growth was observed. We conclude that immunosuppression minimization after pediatric liver transplant yields no serious complications from rejection, and might confer advantages with respect to infection, renal function, growth, and is deserving of wider application and study.

Clinical impact of cytokine and growth factor genetic polymorphisms in thoracic organ transplantation

Demographic and clinical risk factors may only partially predict short- and long-term outcomes after thoracic transplantation. The interindividual variability seen in rejection profiles could be related to the recipient's or donor's genetic background. Rejection, either acute or chronic, elicits an alloimmune response that involves a complex network of cytokines, growth factors, adhesion molecules, and other molecules, which may modulate the immune response toward rejection or, conversely, mediate graft acceptance. Herein, the authors discuss the current evidence regarding the importance of genetic polymorphisms as independent predictors of allograft outcome. They believe that pretransplant genotype profiling of patients, in combination with other relevant clinical information, might be useful to predict the risk for posttransplant adverse events and also to facilitate the implementation of individualized immunosuppression.

Long-term management of immunosuppression after pediatric liver transplantation: is minimization or withdrawal desirable or possible or both?

PURPOSE OF REVIEW

The aim is to review available data regarding the risks and benefits of indefinite immunosuppression against attempted immunosuppression withdrawal for children who have undergone liver transplantation.

RECENT FINDINGS

Emerging data suggest that conventional immunosuppression practices may well be responsible for a substantial proportion of the long-term mortality and morbidity burden borne by pediatric liver transplant recipients. The cumulative risk of chronic kidney disease, infection, malignancy, and cardiovascular risk factors such as hypertension, diabetes, and hyperlipidemia appear to threaten the health and well being of children more than that of acute or chronic allograft rejection. In parallel, single-center experiences have suggested that gradual immunosuppression withdrawal can be done safely with higher success rates in pediatric compared with adult liver transplant recipients. The coalescence of these two data streams has engendered substantial interest in systematic exploration of the safety and efficacy of immunosuppression withdrawal in conjunction with a vigorous scientific effort to elucidate an immunologic signature predictive of successful withdrawal.

SUMMARY

There is a concerted effort within the transplant community to identify biomarkers that can accurately predict the success of immunosuppression withdrawal after liver transplantation. Freedom from lifelong immunosuppression is likely to yield considerable benefit, particularly for children who face the longest lifetime horizons.

Hepatic IL-8 release during graft procurement is associated with impaired graft function after human liver transplantation

In experimental models, brain death induces inflammatory cascades, leading to reduced graft survival. Thus far, factors prior to graft preservation have gained less attention in clinical setting. We studied pre-preservation inflammatory response and its effects on graft function in 30 brain dead liver donors and the respective recipients. Before donor graft perfusion, portal and hepatic venous blood samples were drawn for phagocyte adhesion molecule expression and plasma cytokine determinations. Donor intensive care unit stay correlated with donor C-reactive protein (R = 0.472, p = 0.013) and IL-6 (R = 0.419, p = 0.026) levels, and donor (R = 0.478, p = 0.016) and recipient gamma-glutamyl transferase (R = 0.432, p = 0.019) levels. During graft procurement, hepatic IL-8 release was observed in 17/30 donors. Grafts with hepatic IL-8 release exhibited subsequently higher alkaline phosphatase [319 (213-405) IU/L vs. 175 (149-208) IU/L, p = 0.006] and bilirubin [101 (44-139) micromol/L vs. 30 (23-72) micromol/L, p = 0.029] levels after transplantation. Our findings support the concept that inflammatory response in the brain dead organ donor contributes to the development of graft injury in human liver transplantation.

Genetic polymorphisms impact the risk of acute rejection in pediatric heart transplantation: a multi-institutional study

OBJECTIVE

The objective of this study was to determine the association between the genetic polymorphisms of proinflammatory and regulatory cytokines and long-term rates of repeat and late acute rejection episodes in pediatric heart transplant (PHTx) recipients.

METHODS

Three hundred twenty-three PHTx recipients: 205 White non-Hispanic, 43 Black non-Hispanic, and 75 Hispanic were analyzed for time to first repeat and late acute rejection episodes by race, age at transplantation, and gene polymorphism (interleukin [IL]-6, -174 G/C, IL-10, -1082 G/A, -819 C/T, 592 C/A; vascular endothelial growth factor (VEGF) -2578 C/A, -460 C/T, +405 C/G; tumor necrosis factor alpha (TNF-alpha)-308 G/A).

RESULTS

Recipient black race and older age at transplant were risk factors for both repeat and late rejections, though black race was more significantly related to late rejection (P=0.006). Individually, TNF-alpha high, IL-6 high, VEGF high, and IL-10 low phenotypes did not impact the risk of repeat or late rejection. However, the combination VEGF high/IL-6 high and IL-10 low was associated with increased estimated risk of late rejection (P=0.0004) and only marginally with repeat rejection (P=0.051). In a multivariate analysis, adjusting for age and race, VEGF high/IL-6 high and IL-10 low still remained an independent risk factor for late acute rejection (RR=1.91, P<0.001).

CONCLUSION

This is the largest multicenter study to document the impact of genetic polymorphism combinations on PHTx recipients' outcome. The high proinflammatory (VEGF high/IL-6 high) and lower regulatory (IL-10 low) cytokine gene polymorphism profile exhibited increased risk for late rejection, irrespective of age and race/ethnicity.

The impact of race on liver transplant outcomes in the MELD era: still more questions than answers

Liver transplantation is a life-saving therapy for patients with end-stage liver disease (ESLD); however, donor livers are scarce. Several studies have demonstrated racial disparities in access to liver transplant as well as patient and graft survival after liver transplantation. These studies used data gathered before the model for end-stage liver disease (MELD) was used to determine priority for liver transplant. In this issue of the journal, Drs. Ananthakrishnan and Saeian examine survival after transplant in the MELD era by race and ethnicity, and show that the racial disparities in posttransplant outcomes persist despite MELD. This study provides further evidence that race, which is likely a proxy for a variety of biological and sociological factors, must be considered in any prognostic model for liver transplantation. The impact of race on liver transplantation outcomes should be evaluated further in a well-designed, multicentered, prospective study.

Review of nonimmunological causes for deteriorated graft function and graft loss after transplantation

Various factors determine the graft- and patient survival after transplantation. HLA-matching and immunological factors are of importance for the short- and long-term survival. Apart from these obvious determinants, nonimmunological factors play an important role in defining the baseline organ quality as well as the recipients' status. The influence of these parameters on graft- and patient survival is still underestimated and is a topic of debate. On account of the increasing acceptance of marginal-donor organs these events are of increasing importance for graft survival and long-term function. We review nonimmunological causes for deteriorated graft function and graft loss after solid organ transplantation.

Late acute rejection after liver transplantation impacts patient survival

Hepatic allograft rejection still remains an important problem following liver transplantation. Early acute rejection, occurring within three months of transplant, is a common event and usually of lesser significance with respect to prognosis than other non-immune-related post-transplant morbidities. However, little is known about late acute rejection (LAR) including factors affecting its occurrence and long-term outcome. In this study, we analyzed LAR including the incidence, clinical risk factors, patient survival, and graft survival. LAR was defined as acute cellular rejection later than six months after liver transplant. Adult patients who had a minimum of 24 months of graft survival were included in this study. A total of 1604 case records of consecutive adult patients (over age 18 yr) who underwent liver transplant between 1985 and 2003 were reviewed. Of the 1604 patients, 305 (19.0%) developed LAR. Patients with primary diagnoses of autoimmune hepatitis, primary biliary cirrhosis, and primary sclerosing cholangitis had higher incidences of LAR, while patients with metabolic disease and retransplant had lower incidence of LAR (p = 0.0024). The LAR group had more female and younger recipients than the no LAR group (p = 0.0026, p = 0.0131, respectively). Patient survival as well as graft survival were significantly lower in the LAR group (p = 0.0083, p = 0.0075, respectively). PTLD was the only significant independent predictor of late rejection. The careful management and treatment of PTLD, especially immunosuppressive management, is important to prevent LAR, which is related to poorer patient survival.

Late graft loss or death in pediatric liver transplantation: an analysis of the SPLIT database

Late graft loss (LGL) and late mortality (LM) following liver transplantation (LT) in children were analyzed from the studies of pediatric liver transplantation (SPLIT) database. Univariate and multivariate associations between pre- and postoperative factors and LGL and LM in 872 patients alive with their primary allografts 1 year after LT were reviewed. Thirty-four patients subsequently died (LM) and 35 patients underwent re-LT (LGL). Patients who survive the first posttransplant year had 5-year patient and graft survival rates of 94.2% and 89.2%, respectively. Graft loss after the first year was caused by rejection in 49% of the cases with sequelae of technical complications accounting for an additional 20% of LGL. LT for tumor, steroid resistant rejection, reoperation in the first 30 days and >5 admissions during the first posttransplant year were independently associated with LGL in multivariate analysis. Malignancy, infection, multiple system organ failure and posttransplant lymphoproliferative disease accounted for 61.8% of all late deaths after LT. LT performed for FHF and tumor were associated with LM. Patients who are at or below the mean for weight at the time of transplant were also at an increased risk of dying. Frequent readmission was also found to be associated with LM.

Influence of the CYP3A5 genotype on tacrolimus pharmacokinetics and pharmacodynamics in young kidney transplant recipients

CYP3A enzyme plays a pivotal role in TAC metabolism. The aim of this study was to analyze retrospectively the influence of CYP3A5 gene polymorphism on TAC pharmacokinetics and pharmacodynamics in 30 teenage kidney transplant recipients. TAC dose, trough blood levels, apparent volume of distribution, as well as blood pressure and antihypertensive therapy obtained at different post-transplant periods, were correlated with the corresponding genotype. Despite a therapeutic monitoring strategy, heterozygotes (CYP3A5*1/*3) displayed a lower TAC blood concentration compared with homozygotes (CYP3A5*3/*3). Therefore, a two-fold increase of the daily TAC dose was required in the heterozygotes to reach the desired therapeutic target level. A significant group by time interaction effect was present for both variables (repeated measures ANOVA: p = 0.002) meaning a significant different pharmacokinetic response in these two cohorts. Mean blood pressure was also elevated in CYP3A5*1/*3 recipients despite similar antihypertensive treatment. This was parallel with an elevated apparent volume of distribution of TAC in this group. Thus, the allele-effect was correlated with one of the most common TAC side-effects suggesting a possible influence of CYP3A5 polymorphism on TAC pharmacodynamics. The authors concluded that a pre-emptive CYP3A5 pharmacogenetic screening could contribute to better individualization of TAC therapy.

Liver transplantation in children

Liver transplantation (LT) is now a standard treatment for children with end-stage liver disease with excellent 1- and 5-year survival. This has been achieved through improvement of surgical techniques and anti-rejection treatment and management. The donor pool for children has been extended by the use of cut-down, split, living-related and, recently, non-heart-beating donor and isolated hepatocyte transplantation. Though the majority of transplanted children enjoy an excellent quality of life, there remain a high number of possible complications, including short-term primary non-function, vascular and biliary problems, bowel perforation, severe rejection, infection, hypertension and long-term renal impairment, chronic rejection, de novo autoimmunity, lymphoproliferative disease and cancer, most of which are related to anti-rejection drug toxicity. Hence, the focus of research for paediatric LT should be induction of tolerance, avoiding long-term immunosuppression and its toxicity.

Disparate Distribution of 16 Candidate Single Nucleotide Polymorphisms Among Racial and Ethnic Groups of Pediatric Heart Transplant Patients

BACKGROUND

Allograft failure in African-Americans remains higher than in Caucasians. Single nucleotide polymorphisms (SNPs) have been associated with altered allograft outcomes.

METHODS

In this multi-center study we compared SNP frequencies in 364 pediatric heart recipients from three ethnic/racial groups: Caucasian (n = 243), African-American (n = 39), and Hispanic (n = 82). The target genes were: tumor necrosis factor-alpha, interleukin (IL)-10, IL-6, interferon (IFN)-gamma, vascular endothelial growth factor (VEGF), transforming growth factor-beta1, Fas, FasL, granzyme B, ABCB1, CYP3A5.

RESULTS

Compared to Caucasians, African-Americans exhibited a higher prevalence of genotypes associated with low expression of IFN-gamma (24% vs. 45.7%, P < 0.001) and IL-10 (33% vs. 57.1%, P = 0.052). African-Americans also exhibited an increased prevalence of high IL-6 (82.9% vs. 38.1%; P < 0.001). VEGF -2578 C/C and -460 C/C genotypes were found more frequently in African-Americans and Hispanics as compared to Caucasians (P < 0.001). G/G genotype of Fas and T/T genotype of FasL were expressed more often by African-American recipients. The prevalence of Granzyme B (-295A/G) genotype was differentially distributed in the three groups. Compared with Caucasians, African-Americans were twice as likely to carry the ABCB1 2677 G/G genotype (78.6% vs. 33.7%, P < 0.0025), and they were more frequent carriers of the CYP3A5 *1/*1 genotype (35.7% vs. 0.6% in Caucasians and 7.2% in Hispanics; P < 0.001).

CONCLUSION

African-Americans have a genetic background that may predispose to proinflammatory/lower regulatory environment, reduced drug exposure and immunosuppressive efficacy. In this ongoing multicenter study, these gene polymorphisms differences among ethnic/racial groups are being documented so that therapeutic strategies can be devised to optimize outcomes for pediatric transplant recipients.

The incidence and management of acute and chronic rejection after living donor liver transplantation

Living donor liver transplantation (LDLT) is a good alternative to cadaveric liver transplantation for end-stage liver disease. Herein we report the outcome of 132 LDLTs performed between 1999 and 2005, with special emphasis on the incidence and management of acute and chronic rejection. Among the LDLT population a first acute rejection episode (ARE) was clinically suspected in 24% and proven by liver biopsy in 11%. According to the Banff classification, 50% of AREs were grade 1, and 50%, grade 2. There was no grade 3 AREs. The first ARE occurred between 7 days and 23 months posttransplantation (mean 97 days, median 70 days). Ninety-seven percent (31/32) of the AREs occurred within the first year after transplantation and 3% (1/32) in the second year. Among the patients with ARE, 23% developed a second ARE between 4 and 11 months. A third ARE was detected in 8% of patients after month 18. All AREs responded to adjustment of immunosuppressive doses or steroid boluses. Chronic rejection (CR) was detected in 2%. In conclusion, the incidences of ARE and CR are consistent with the previously reported data. Acute and chronic rejections seem to be mild and easily manageable clinical conditions. Our results also showed a significant difference between clinically suspected and biopsy-proven ARE emphasizing the importance of indicated liver biopsies in the management of the LDLT population.

Randomized trial of basiliximab induction versus steroid therapy in pediatric liver allograft recipients under tacrolimus immunosuppression

Avoidance of corticosteroids could be beneficial after pediatric liver transplantation (LTx). To test this hypothesis, we performed a randomized prospective study to compare immunosuppression with tacrolimus (TAC) and steroids versus TAC and basiliximab (BAS) after pediatric LTx. Seventy-two patients were recruited, 36 receiving TAC and steroids and 36 TAC and BAS. The primary endpoint was the occurrence of the first rejection episode. Secondary endpoints were the cumulative incidence and severity of rejection, patient and graft survival, and incidence of adverse events. Overall 1-year patient and graft survival rates were 91.4% and 85.5% in the steroid group, and 88.6% and 80% in the BAS group (p = NS). Patients free from rejection were 87.7% in the BAS group and 67.7% in the steroid group (p = 0.036). The use of BAS was associated with a 63.6% reduction in incidence of acute rejection episodes. Overall incidence of infection was 72.3% in the steroid group and 50% in the BAS group (p = 0.035). We conclude that the combination of TAC with BAS is an alternative to TAC and steroid immunosuppression in pediatric LTx, which allows for a significant reduction in the incidence of acute rejection and infectious complications.

Cadaveric full-size liver transplantation and the graft alternatives in adults: a comparative study from a single centre

BACKGROUND/AIMS

This study aims to compare the results of living donor (LDLT), cadaveric split (SLT) and domino (DO) liver transplantation which are currently available alternatives to the conventional cadaveric full-size liver transplantation (CAD).

METHODS

Immunologic, vascular and biliary complications (BC) were evaluated in 38 LDLT, 20 SLT, 17 DO and 38 CAD recipients.

RESULTS

The incidence of acute rejection (AR) was similar between groups, and between blood-related and blood-unrelated patients. AR was more severe in the SLT group according to the Banff scores (P=0.03, P<0.001, P<0.001). The evolution of AR was similar between the groups, in terms of development of chronic rejection. No venous complications occurred in the overall population. The rate of arterial thrombosis (10.5, 10, 0 and 3%, respectively) was statistically similar between groups. The rate of BC (26, 40, 12, and 8%, respectively) was higher in the partial grafts than in the whole grafts (P=0.006), but was not significantly different within each group. There was an association between the severity of preservation injury and occurrence of AR (P=0.01) and arterial thrombosis (P=0.016), but not BC. One- and 2-year graft and patient survival rates were similar between groups.

CONCLUSIONS

None of the graft types seemed to confer immunological advantage. BC remained problematic in the partial grafts, independently from ischemia time.

Outcome of pediatric liver transplant recipients in Turkey: single center experience

To summarize the evolution of the pediatric liver transplant program in a developing country. Between April 1997, and September 2003, 32 cadaveric (CD) and 35 living donor (LD) liver transplantations were performed on 61 children (median age 3.8 yr, range 0.5-16) at Ege University Organ Transplantation and Research Center. The patient's charts were reviewed retrospectively. The outcome of patient and graft survival was analyzed and the incidence of graft loss, complications and rejections was calculated. Indications for liver transplantation were metabolic liver disease (n = 17), biliary atresia (n = 14), viral hepatitis (n = 4), autoimmune hepatitis (n = 6), cryptogenic cirrhosis (n = 11), fulminant liver failure (n = 5) and others (n = 5). Seven of 61 children with chronic liver disease had hepatocellular carcinoma concomitantly. Median pediatric end-stage liver disease score was 23 (range 1-54). Seven children (11.4%) were UNOS status I, 44 (72%) were UNOS status II and 10 (16.6%) were UNOS status III. The median follow-up of the study population was 3.6 yr (range 0.5-6). Actuarial patient survival rates at 1, 2, 3 and 4 yr were 86, 86, 71.3 and 65% in the CD group vs. 80, 76, 67 and 67% in the LR group, respectively (p = NS). Patients listed as UNOS status 1 had lower survival rates than patients listed as UNOS status 2 and 3 (p < 0.05). The mortality rate was 26.2%. Graft survival rates were 81, 81, 75 and 64% at 1, 2, 3 and 4-yr respectively. Six patients (9%) underwent retransplantation. The main complications were infections (64.7%) and surgical complications (43.2%) (including biliary complication, vascular problems, postoperative bleeding, small for size and large for size). The incidence of acute cellular rejection was 39.3%, whereas chronic rejection was 7.4%. The result of liver transplantation in Turkish children was slightly inferior to those reported for North American and European children. However, an important characteristic of these patients that distinguishes them from Europe and North America is that most were UNOS status IIa and UNOS status I (44%). Despite technical and medical progress, infectious and biliary problems have continued to be an important cause of mortality in these patients.