Incidence and severity of acute cellular rejection in recipients undergoing adult living donor or deceased donor liver transplantation

Pretransplant use of immune checkpoint inhibitors for hepatocellular carcinoma: A multicenter, retrospective cohort study

Immune checkpoint inhibitors (ICIs) as a downstaging or bridging therapy for liver transplantation (LT) in hepatocellular carcinoma patients are rapidly increasing. However, the evidence about the feasibility and safety of pre-LT ICI therapy is limited and controversial. To this end, a multicenter, retrospective cohort study was conducted in 11 Chinese centers. The results showed that 83 recipients received pre-LT ICI therapy during the study period. The median post-LT follow-up was 8.1 (interquartile range 3.3-14.6) months. During the short follow-up, 23 (27.7%) recipients developed allograft rejection, and 7 of them (30.4%) were diagnosed by liver biopsy. Multivariate logistics regression analysis showed that the time interval between the last administration of ICI therapy and LT (TLAT) ≥ 30 days was an independent protective factor for allograft rejection (odds ratio = 0.096, 95% confidence interval 0.026-0.357; P < .001). Multivariate Cox analysis showed that allograft rejection was an independent risk factor for overall survival (hazard ratio = 9.960, 95% confidence interval 1.006-98.610; P = .043). We conclude that patients who receive a pre-LT ICI therapy with a TLAT shorter than 30 days have a much higher risk of allograft rejection than those with a TLAT longer than 30 days. The presence of rejection episodes might be associated with higher post-LT mortality.

Alterations in CD4+ T-cell Subsets in Living Donor Liver Transplantation Associated With Graft Rejection

Background and objectives

Regulatory T-cells (Tregs) play a key role in immune homeostasis after organ transplantation. However, the role of CD4+ T cell subsets in early acute rejection is still not well understood. Therefore, our aim was to determine changes in CD4+ T-cell subsets in living donor liver transplantation (LDLT).

Methods

LDLT patients were assessed for T-cell subsets, Tregs frequencies and their functionality by flow-cytometry at peri- and post-transplant in the span of 1 year.

Results

33 patients were followed up and 11 (33%) patients have developed early acute cellular rejection (ACR). At peri-transplant time point, MFI of Foxp3+ Tregs was significantly increased compared to HC (P = 0.04). However, CD4+CD25+Foxp3+/CD127- Tregs numbers and IL-10, IL-17 and TGF-β secreting functional Tregs were significantly decreased at 3 months compared to peri-transplant (P = 0.003). But in patients with rejection, CD4+CD25+FOXP3+ and CD4+CD25+CD127- Tregs were significantly decreased at day 3 compared to no rejection group (P = 0.048). Patients with rejection also showed significantly decreased numbers of IL-17 and TGF-β secreting CD4+CD25+FOXP3+ Tregs at peri-transplant time (P = 0.04, P = 0.03) compared to no rejection. Further, rejection group showed decreased terminally differentiated effector memory (TEMRA) at peri-transplant and day 7 (P = 0.048 and P = 0.01). Additionally, CD4+ central memory (CM) was decreased at peri-transplant (P = 0.05), 1 month (P = 0.04), and 3 to 6 month (P = 0.02).

Interpretation and conclusion

Tregs frequencies were significantly decreased in peri-TX in rejection patients. Further, decreased frequencies of CD4+ TEMRA and CD4+ CM at day 7 and 1 month were associated with rejection.

Early Graft Loss With Suspected Seventh-Day Syndrome Following Pediatric Liver Transplantation

INTRODUCTION

Allograft dysfunction within the first week posttransplant is an uncommon but known complication following liver transplantation. Seventh-Day Syndrome (7DS) is a rare complication of allograft dysfunction following liver transplantation characterized by the rapid clinical deterioration of a formerly well-functioning allograft within the first week posttransplant. The etiology of 7DS is unknown, and treatment options remain limited. While cases of graft survival have been reported, the risk of mortality remains exceedingly high without urgent retransplantation.

METHODS

Patient data was retrospectively analyzed and a literature review performed.

RESULTS

We present a unique case of split liver transplantation into two pediatric recipients in which one recipient developed rapidly progressive graft failure approximately 1 week postoperatively requiring urgent retransplantation while the other recipient had an unremarkable postoperative course. Upon clinical manifestation of progressive graft failure, the patient was treated with thymoglobulin, rituximab, intravenous immunoglobulin, and plasmapheresis. Despite this, the patient's clinical status continued to decline and she underwent retransplantation 11 days following her initial liver transplant.

CONCLUSION

Seventh-Day Syndrome is a rare complication following liver transplantation that is associated with a high risk of morbidity and mortality. Our case adds to the limited literature on 7DS in children and is the first to report a comparative posttransplant clinical course in two recipients who received split grafts from the same donor.

Basics and Art of Immunosuppression in Liver Transplantation

Liver transplantation is one of the most challenging areas in the medical field. Despite that, it has already been established as a standard treatment option, especially in decompensated cirrhosis and selected cases of hepatocellular carcinoma and acute liver failure. Complications due to graft rejection, including mortality and morbidity, have greatly improved over time due to better immunosuppressive agents and management protocols. Currently, immunosuppression in liver transplant patients makes use of the best possible combinations of effective agents to achieve optimal immunosuppression for long-term graft survival. Induction agents are no longer used routinely, and the aim is to provide minimal immunosuppression in the maintenance phase. Currently available immunosuppressive agents are mainly classified as biological and pharmacological agents. Though the protocols may vary among the centers and over time, the basics of effective use usually remain similar. Most protocols use the combination of multiple agents with different mechanisms of action to reduce the dose and minimize the side effects. Along with the improvement in operative and perioperative techniques, this art of immunosuppression has contributed to the recent progress made in the outcomes of liver transplants. In this review, we will discuss the various types of immunosuppressive agents currently in use, the different protocols of immunosuppression used, and the art of optimal use for achieving maximum immunosuppression without increasing toxicity. We will also discuss the practical aspects of various immunosuppression regimens, including drug monitoring, and briefly discuss the concepts of immunosuppression minimization and withdrawal.

Spatially resolved immune exhaustion within the alloreactive microenvironment predicts liver transplant rejection

Allograft rejection is common following clinical organ transplantation, but defining specific immune subsets mediating alloimmunity has been elusive. Calcineurin inhibitor dose escalation, corticosteroids, and/or lymphocyte depleting antibodies have remained the primary options for treatment of clinical rejection episodes. Here, we developed a highly multiplexed imaging mass cytometry panel to study the immune response in archival biopsies from 79 liver transplant (LT) recipients with either no rejection (NR), acute T cell-mediated rejection (TCMR), or chronic rejection (CR). This approach generated a spatially resolved proteomic atlas of 461,816 cells (42 phenotypes) derived from 96 pathologist-selected regions of interest. Our analysis revealed that regulatory (HLADR+ Treg) and PD1+ T cell phenotypes (CD4+ and CD8+ subsets), combined with variations in M2 macrophage polarization, were a unique signature of active TCMR. These data provide insights into the alloimmune microenvironment in clinical LT, including identification of potential targets for focused immunotherapy during rejection episodes and suggestion of a substantial role for immune exhaustion in TCMR.

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

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

Post-Transplant Management and Complications of Autoimmune Hepatitis, Primary Biliary Cholangitis, and Primary Sclerosing Cholangitis including Disease Recurrence

Autoimmune liver diseases have unique post-transplant considerations. These recipients are at increased risk of rejection, and recurrent disease may also develop, which can progress to graft loss and increase mortality. Monitoring for and managing these complications is therefore important, though data on associated risk factors and immunosuppression strategies has in most cases been mixed. There are also other disease-specific complications that require management and may impact these decisions, including inflammatory bowel disease in PSC. Further work to better understand the optimal management strategies for these patients post-transplant is needed.

Comparing High- and Low-Model for End-Stage Liver Disease Living-Donor Liver Transplantation to Determine Clinical Efficacy: A Systematic Review and Meta-Analysis (CHALICE Study)

INTRODUCTION

Various studies have demonstrated that low-Model for End-Stage Liver Disease (MELD) living-donor liver transplant (LDLT) recipients have better outcomes with improved patient survival than deceased-donor liver transplantation (DDLT) recipients. LDLT recipients gain the most from being transplanted at MELD <25-30; however, some existing data have outlined that LDLT may provide equivalent outcomes in high-MELD and low-MELD patients, although the term "high" MELD is arbitrarily defined in the literature and various cut-off scores are outlined between 20 and 30, although most commonly, the dividing threshold is 25. The aim of this meta-analysis was to compare LDLT in high-MELD with that in low-MELD recipients to determine patient survival and graft survival, as well as perioperative and postoperative complications.

METHODS

Following PROSPERO registration CRD-42021261501, a systematic database search was conducted for the published literature between 1990 and 2021 and yielded a total of 10 studies with 2183 LT recipients; 490 were HM-LDLT recipients and 1693 were LM-LDLT recipients.

RESULTS

Both groups had comparable mortality at 1, 3 and 5 years post-transplant (5-year HR 1.19; 95% CI 0.79-1.79; p-value 0.40) and graft survival (HR 1.08; 95% CI 0.72, 1.63; p-value 0.71). No differences were observed in the rates of major morbidity, hepatic artery thrombosis, biliary complications, intra-abdominal bleeding, wound infection and rejection; however, the HM-LDLT group had higher risk for pulmonary infection, abdominal fluid collection and prolonged ICU stay.

CONCLUSIONS

The high-MELD LDLT group had similar patient and graft survival and morbidities to the low-MELD LDLT group, despite being at higher risk for pulmonary infection, abdominal fluid collection and prolonged ICU stay. The data, primarily sourced from high-volume Asian centers, underscore the feasibility of living donations for liver allografts in high-MELD patients. Given the rising demand for liver allografts, it is sensible to incorporate these insights into U.S. transplant practices.

Liver Transplantation for Acute Liver Failure- Indication, Prioritization, Timing, and Referral

Acute liver failure (ALF) is a major success story in gastroenterology, with improvements in critical care and liver transplant resulting in significant improvements in patient outcomes in the current era compared to the dismal survival rates in the pretransplant era. However, the ever-increasing list of transplant candidates and limited organ pool makes judicious patient selection and organ use mandatory to achieve good patient outcomes and prevent organ wastage. Several scoring systems exist to facilitate the identification of patients who need a liver transplant and would therefore need an early referral to a specialized liver unit. The timing of the liver transplant is also crucial as transplanting a patient too early would lead to those who would recover spontaneously receiving an organ (wastage), and a late decision might result in the patient becoming unfit for transplant (delisted) or have an advanced disease which would result in poor post-transplant outcomes. The current article reviews the indications and contraindications of liver transplant in ALF patients, the various prognostic scoring systems, etiology-specific outcomes, prioritization and timing of referral.

Outcome of split liver transplantation vs living donor liver transplantation: A systematic review and meta-analysis

BACKGROUND

The outcomes of liver transplantation (LT) from different grafts have been studied individually and in combination, but the reports were conflicting with some researchers finding no difference in both short-term and long-term outcomes between the deceased donor split LT (DD-SLT) and living donor LT (LDLT).

AIM

To compare the outcomes of DD-SLT and LDLT we performed this systematic review and meta-analysis.

METHODS

This systematic review was performed in compliance with the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. The following databases were searched for articles comparing outcomes of DD-SLT and LDLT: PubMed; Google Scholar; Embase; Cochrane Central Register of Controlled Trials; the Cochrane Database of Systematic Reviews; and Reference Citation Analysis (https://www.referencecitationanalysis.com/). The search terms used were: "liver transplantation;" "liver transplant;" "split liver transplant;" "living donor liver transplant;" "partial liver transplant;" "partial liver graft;" "ex vivo splitting;" and "in vivo splitting."

RESULTS

Ten studies were included for the data synthesis and meta-analysis. There were a total of 4836 patients. The overall survival rate at 1 year, 3 years and 5 years was superior in patients that received LDLT compared to DD-SLT. At 1 year, the hazard ratios was 1.44 (95% confidence interval: 1.16-1.78; P = 0.001). The graft survival rate at 3 years and 5 years was superior in the LDLT group (3 year hazard ratio: 1.28; 95% confidence interval: 1.01-1.63; P = 0.04).

CONCLUSION

This meta-analysis showed that LDLT has better graft survival and overall survival when compared to DD-SLT.

Spatially resolved immune exhaustion within the alloreactive microenvironment predicts liver transplant rejection

Allograft rejection is a frequent complication following solid organ transplantation, but defining specific immune subsets mediating alloimmunity has been elusive due to the scarcity of tissue in clinical biopsy specimens. Single cell techniques have emerged as valuable tools for studying mechanisms of disease in complex tissue microenvironments. Here, we developed a highly multiplexed imaging mass cytometry panel, single cell analysis pipeline, and semi-supervised immune cell clustering algorithm to study archival biopsy specimens from 79 liver transplant (LT) recipients with histopathological diagnoses of either no rejection (NR), acute T-cell mediated rejection (TCMR), or chronic rejection (CR). This approach generated a spatially resolved proteomic atlas of 461,816 cells derived from 98 pathologist-selected regions of interest relevant to clinical diagnosis of rejection. We identified 41 distinct cell populations (32 immune and 9 parenchymal cell phenotypes) that defined key elements of the alloimmune microenvironment (AME), identified significant cell-cell interactions, and established higher order cellular neighborhoods. Our analysis revealed that both regulatory (HLA-DR+ Treg) and exhausted T-cell phenotypes (PD1+CD4+ and PD1+CD8+ T-cells), combined with variations in M2 macrophage polarization, were a unique signature of TCMR. TCMR was further characterized by alterations in cell-to-cell interactions among both exhausted immune subsets and inflammatory populations, with expansion of a CD8 enriched cellular neighborhood comprised of Treg, exhausted T-cell subsets, proliferating CD8+ T-cells, and cytotoxic T-cells. These data enabled creation of a predictive model of clinical outcomes using a subset of cell types to differentiate TCMR from NR (AUC = 0.96 ± 0.04) and TCMR from CR (AUC = 0.96 ± 0.06) with high sensitivity and specificity. Collectively, these data provide mechanistic insights into the AME in clinical LT, including a substantial role for immune exhaustion in TCMR with identification of novel targets for more focused immunotherapy in allograft rejection. Our study also offers a conceptual framework for applying spatial proteomics to study immunological diseases in archival clinical specimens.

Graft-Derived Cell-Free DNA Quantification following Liver Transplantation Using Tissue-Specific DNA Methylation and Donor-Specific Genotyping Techniques: An Orthogonal Comparison Study

Background: Graft-derived cell-free DNA (gdcfDNA) analysis has shown promise as a non-invasive tool for monitoring organ health following solid organ transplantation. A number of gdcfDNA analysis techniques have been described; however, the majority rely on sequencing or prior genotyping to detect donor-recipient mis-matched genetic polymorphisms. Differentially methylated regions of DNA can be used to identify the tissue-of-origin of cell-free DNA (cfDNA) fragments. In this study, we aimed to directly compare the performance of gdcfDNA monitoring using graft-specific DNA methylation analysis and donor-recipient genotyping techniques in a pilot cohort of clinical samples from patients post-liver transplantation. Results: 7 patients were recruited prior to LT, 3 developed early, biopsy-proven TCMR in the first 6 weeks post-LT. gdcfDNA was successfully quantified in all samples using both approaches. There was a high level of technical correlation between results using the two techniques (Spearman testing, r_s = 0.87, p < 0.0001). gdcfDNA levels quantified using the genotyping approach were significantly greater across all timepoints in comparison to the tissue-specific DNA methylation-based approach: e.g., day 1 post-LT median 31,350 copies/mL (IQR 6731-64,058) vs. 4133 copies/mL (IQR 1100-8422), respectively. Qualitative trends in gdcfDNA levels for each patient were concordant between the two assays. Acute TCMR was preceded by significant elevations in gdcfDNA as quantified by both techniques. Elevations in gdcfDNA, using both techniques, were suggestive of TCMR in this pilot study with a 6- and 3-day lead-time prior to histological diagnosis in patients 1 and 2. Conclusions: Both the graft-specific methylation and genotyping techniques successfully quantified gdcfDNA in patients post-LT with statistically significant concordance. A direct comparison of these two techniques is not only important from a technical perspective for orthogonal validation, but significantly adds weight to the evidence that gdcfDNA monitoring reflects the underlying biology. Both techniques identified LT recipients who developed acute TCMR, with several days lead-time in comparison to conventional diagnostic workflows. Whilst the two assays performed comparably, gdcfDNA monitoring based on graft-specific DNA methylation patterns in cfDNA offers major practical advantages over the donor-recipient genotyping, and hence enhances the potential to translate this emerging technology into clinical practice.

Steroid Avoidance After Adult Living Donor Liver Transplant: A Cohort Analysis

Although steroid avoidance (SA) has been studied in deceased donor liver transplant, little is known about SA in living donor liver transplant (LDLT). We report the characteristics and outcomes, including the incidence of early acute rejection (AR) and complications of steroid use, in 2 cohorts of LDLT recipients.

Methods

Routine steroid maintenance (SM) after LDLT was stopped in December 2017. Our single-center retrospective cohort study spans 2 eras. Two hundred forty-two adult recipients underwent LDLT with SM (January 2000-December 2017), and 83 adult recipients (December 2017-August 2021) underwent LDLT with SA. Early AR was defined as a biopsy showing pathologic characteristics within 6 mo after LDLT. Univariate and multivariate logistic regressions were performed to evaluate the effects of relevant recipient and donor characteristics on the incidence of early AR in our cohort.

Results

Neither the difference in early AR rate between cohorts (SA 19/83 [22.9%] versus SM 41/242 [17%]; P = 0.46) nor a subset analysis of patients with autoimmune disease (SA 5/17 [29.4%] versus SM 19/58 [22.4%]; P = 0.71) reached statistical significance. Univariate and multivariate logistic regressions for early AR identified recipient age to be a statistically significant risk factor (P < 0.001). Of the patients without diabetes before LDLT, 3 of 56 (5.4%) on SA versus 26 of 200 (13%) on SM needed medications prescribed for glucose control at the time of discharge (P = 0.11). Patient survival was similar between SA and SM cohorts (SA 94% versus SM 91%, P = 0.34) 3 y after transplant.

Conclusions

LDLT recipients treated with SA do not exhibit significantly higher rates of rejection or increased mortality than patients treated with SM. Notably, this result is similar for recipients with autoimmune disease.

Risk factors for acute rejection in liver transplantation and its impact on the outcomes of recipients

OBJECTIVE

To determine the risk factors for acute rejection in liver transplantation and its impact on the outcomes of the recipients.

METHODS

Clinicopathological data of 290 patients who underwent liver transplantation from January 2012 to December 2021 at our center were retrospectively evaluated. Patients were grouped into an acute rejection (AR) group and a normal (NM) group based on the confirmed histopathological diagnosis of acute rejection. Univariate and multivariate logistic regression were used to determine the risk factors for acute rejection.

RESULTS

244 patients were included in the study. Acute rejection occurred in 27 (11.1%) of the patients. Warm ischemia time (P = 0.137), cold ischemia time (P = 0.064) and chronic liver failure (P = 0.001) were potential risk factors for acute rejection. Chronic liver failure (P < 0.001, OR = 8.22, 95% CI = 2.47-27.32) was the independent risk factor. There was no significant difference in overall survival between recipients with acute rejection and those without it (P = 0.985). The 1-, 3- and 5-year overall survival in the NM group was 98.1%, 85.7% and 78.6% respectively vs 88.9%, 82.5% and 82.5% respectively in the AR group.

CONCLUSION

Acute rejection does not appear to affect the long-term survival of the recipients. Only chronic liver failure was an independent risk factor for acute rejection. Our findings further illustrate that contradictions still exist on which factors influence acute rejection in liver transplant recipients.

SUMMARY

Clinicopathological data of 290 liver transplant recipients at our center between January 2012 and December 2021 were retrospectively evaluated to determine the risk factors for acute rejection and its impact on the outcomes of the recipients. 244 patients were included in the analysis. 27 of the 244 experienced acute rejection. Propensity score matching was performed to reduce the confounding effect. Patients were assigned to an acute rejection group (n = 27) and a normal group (n = 54). Chronic liver failure (P < 0.001, OR = 8.22, 95% CI = 2.47-27.32) was the determined to be independent risk factor for acute rejection. Acute rejection did not appear to affect the long-term survival of the recipients and there was no significant difference in overall survival between the patients with acute rejection and those without it.

Immunological Tolerance in Liver Transplant Recipients: Putative Involvement of Neuroendocrine-Immune Interactions

The transplantation world changed significantly following the introduction of immunosuppressants, with millions of people saved. Several physicians have noted that liver recipients that do not take their medication for different reasons became tolerant regarding kidney, heart, and lung transplantations at higher frequencies. Most studies have attempted to explain this phenomenon through unique immunological mechanisms and the fact that the hepatic environment is continuously exposed to high levels of pathogen-associated molecular patterns (PAMPs) or non-pathogenic microorganism-associated molecular patterns (MAMPs) from commensal flora. These components are highly inflammatory in the periphery but tolerated in the liver as part of the normal components that arrive via the hepatic portal vein. These immunological mechanisms are discussed herein based on current evidence, although we hypothesize the participation of neuroendocrine-immune pathways, which have played a relevant role in autoimmune diseases. Cells found in the liver present receptors for several cytokines, hormones, peptides, and neurotransmitters that would allow for system crosstalk. Furthermore, the liver is innervated by the autonomic system and may, thus, be influenced by the parasympathetic and sympathetic systems. This review therefore seeks to discuss classical immunological hepatic tolerance mechanisms and hypothesizes the possible participation of the neuroendocrine-immune system based on the current literature.

Immunologic benefits of maternal living donor allografts in pediatric liver transplantation: fewer rejection episodes and no evidence of de novo allosensitization

BACKGROUND

Pediatric liver transplant (LT) recipients of maternal living liver donor (LLD) grafts have been reported to experience fewer rejection episodes. However, it is unclear whether this benefit translates to reduction in developing donor-specific antibody (DSA) among maternal-LLD recipients. The aim of this study was to compare immunologic outcomes among maternal-LLD, non-maternal-LLD, and deceased donor liver transplant (DDLT) recipients.

METHODS

Children (≤18 years) who underwent LT between 1/1998 and 12/2019 at two high-volume LT centers in North America were evaluated. Patients were divided into three groups by type of graft received (maternal-LLD, non-maternal LLD, and DDLT). Clinical variables and outcomes were compared according to each graft type.

RESULTS

A total of 450 pediatric primary LT were analyzed: 275 (61.1%) DDLT, 73 (16.2%) maternal-LLD, and 102 (22.6%) non-maternal-LLD. Children receiving LLD grafts were less likely to develop rejection when compared to the DDLT group (DDLT 46.9% vs. maternal-LLD 31.5% vs. non-maternal-LLD 28.4%, p = 0.001). There was no difference in rejection rates between maternal and non-maternal-LLD recipients. A higher percentage of maternal-LLD recipients were on immunosuppression monotherapy compared to non-maternal-LLD and DDLT recipients (6.7% vs. 1.2 vs. 2.4%, respectively). A subgroup of 68 patients were tested for DSA post-LT. Maternal-LLD recipients were less likely to develop de novo DSA (maternal-LLD 11.8% vs. non-maternal-LLD 19.3% vs. DDLT 43%, p = 0.018). None of the maternal-LLD recipients developed antibody-mediated rejection.

CONCLUSIONS

These data support the concept of immunologic benefit of maternal-LLD in pediatric LT, with lower rates of rejection and allosensitization post-LT when compared to DDLT recipients.

Use of blood oxygen level-dependent magnetic resonance imaging to detect acute cellular rejection post-liver transplantation

OBJECTIVES

Acute cellular rejection (ACR) is a major immune occurrence post-liver transplant that can cause abnormal liver function. Blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) can be used to evaluate liver disease, but it has not been utilized in the diagnosis of ACR post-liver transplant. Therefore, the purpose of this study is to evaluate the diagnostic performance of BOLD MRI and to monitor treatment response in recipients with ACR.

METHODS

This prospective study was approved by the local institutional review board. Fifty-five recipients with highly suspected ACR were enrolled in this study. Each patient underwent hepatic BOLD MRI, blood biochemistry, and biopsy before treatment. Of 55 patients, 19 recipients with ACR received a follow-up MRI after treatment. After obtaining the R2* maps, five regions-of-interest were placed on liver parenchyma to estimate the mean R2* values for statistical analysis. Receiver operating characteristic curve (ROC) analysis was performed to assess the diagnostic performance of R2* values in detecting patients with ACR.

RESULTS

The histopathologic results showed that 27 recipients had ACR (14 mild, 11 moderate, and 2 severe) and their hepatic R2* values were significantly lower than those of patients without ACR. ROC analysis revealed that the sensitivity and specificity of the R2* values for detection of ACR were 82.1% and 89.9%, respectively. Moreover, the R2* values and liver function in patients with ACR significantly increased after immunosuppressive treatment.

CONCLUSION

The non-invasive BOLD MRI technique may be useful for assessment of hepatic ACR and monitoring of treatment response after immunosuppressive therapy.

KEY POINTS

• Patients with acute cellular rejection post-liver transplant exhibited significantly decreased R2* values in liver parenchyma. • R2* values and liver function were significantly increased after immunosuppressive therapy. • R2* values were constructive indicators in detecting acute cellular rejection due to their high sensitivity and specificity.

Hematological and biochemical characteristics and diagnostic imaging results in acute T cell-mediated rejection after pediatric liver transplantation

BACKGROUND

Liver biopsy is the gold standard for diagnosing TCMR after LT. However, complications caused by liver biopsy may occur especially during the immediate post-transplantation period and other effective methods for predicting TCMR have not been established. Thus, we investigated whether hematological and biochemical characteristics and Doppler ultrasonography findings are associated with acute TCMR.

METHODS

A multiple logistic regression analysis was performed to identify the prognostic factors of acute TCMR, defined as a RAI ≥4. Then, a ROC curve analysis was conducted to evaluate for diagnostic performance. The relationship between prognostic factors and each histological category of RAI was investigated.

RESULTS

Eighty-nine liver biopsies were performed on 85 patients between January 2012 and December 2019. The RAI of 62 (69.7%) liver biopsies was ≥4. AEC (×10⁴ /μl), direct bilirubin level (mg/dl), and MHVV (cm/s) were found to be associated with acute TCMR (OR: 4.96, 95% CI: 1.44-17.0, p = .011; OR: 1.41, 95% CI: 1.04-1.91, p = .025; OR: 1.05, 95% CI: 1.02-1.08, p < .001, respectively). The area under the ROC curves for predicting acute TCMR was 0.86 (95% CI: 0.78-0.94). There was a correlation between AEC, direct bilirubin level, and MHVV as well as the severity of RAI.

CONCLUSIONS

AEC, direct bilirubin level, and MHVV were the independent risk factors for acute TCMR. This study could provide information regarding the identification of patients requiring liver biopsy.

Activated CD4+ T Cells and Highly Differentiated Alloreactive CD4+ T Cells Distinguish Operationally Tolerant Liver Transplantation Recipients

Spontaneous operational tolerance to the allograft develops in a proportion of liver transplantation (LT) recipients weaned off immunosuppressive (IS) drugs. Several studies have investigated whether peripheral blood circulating T cells could play a role in the development or identify operational tolerance, but never characterized alloreactive T cells in detail due to the lack of a marker for these T cells. In this study, we comprehensively investigated phenotypic and functional characteristics of alloreactive circulating T cell subsets in tolerant LT recipients (n = 15) using multiparameter flow cytometry and compared these with LT recipients on IS drugs (n = 23) and healthy individuals (n = 16). Activation-induced CD137 was used as a marker for alloreactive T cells upon allogenic stimulation. We found that central and effector memory CD4+ T cells were hyporesponsive against donor and third-party splenocyte stimulation in tolerant LT recipients, whereas an overall hyperresponsiveness was observed in alloreactive terminally differentiated effector memory CD4+ T cells. In addition, elevated percentages of circulating activated T helper cells were observed in these recipients. Lastly, tolerant and control LT recipients did not differ in donor-specific antibody formation. In conclusion, a combination of circulating hyperresponsive highly differentiated alloreactive CD4+ T cells and circulating activated T helper cells could discriminate tolerant recipients from a larger group of LT recipients.

HO-1/BMMSC perfusion using a normothermic machine perfusion system reduces the acute rejection of DCD liver transplantation by regulating NKT cell co-inhibitory receptors in rats

Background

Liver transplantation (LT) is required in many end-stage liver diseases. Donation after cardiac death (DCD) livers are often used, and treatment of acute rejection (ACR) requires the use of immunosuppressive drugs that are associated with complications. Bone marrow mesenchymal stem cells (BMMSCs) are used in treatment following LT; however, they have limitations, including low colonization in the liver. An optimized BMMSC application method is required to suppress ACR.

Methods

BMMSCs were isolated and modified with the heme oxygenase 1 (HO-1) gene. HO-1/BMMSCs were perfused into donor liver in vitro using a normothermic machine perfusion (NMP) system, followed by LT into rats. The severity of ACR was evaluated based on liver histopathology. Gene chip technology was used to detect differential gene expression, and flow cytometry to analyze changes in natural killer (NK) T cells.

Results

NMP induced BMMSCs to colonize the donor liver during in vitro preservation. The survival of HO-1/BMMSCs in liver grafts was significantly longer than that of unmodified BMMSCs. When the donor liver contained HO-1/BMMSCs, the local immunosuppressive effect was improved and prolonged, ACR was controlled, and survival time was significantly prolonged. The application of HO-1/BMMSCs reduced the number of NKT cells in liver grafts, increased the expression of NKT cell co-inhibitory receptors, and reduced NKT cell expression of interferon-γ.

Conclusions

NK cell and CD8⁺ T cell activation was inhibited by application of HO-1/BMMSCs, which reduced ACR of transplanted liver. This approach could be developed to enhance the success rate of LT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02647-5.

Molecular Mismatch Predicts T Cell-Mediated Rejection and De Novo Donor-Specific Antibody Formation After Living Donor Liver Transplantation

Human leukocyte antigen (HLA) molecular mismatch (MM) analysis improves the prediction of clinical outcomes in kidney transplantation compared with prediction via traditional antigen MM. However, it remains unclear whether the level of MM can be used for risk stratification among liver transplantation (LT) recipients. A retrospective observational study of 45 living donor LTs was performed to evaluate eplet MM as a risk factor for both T cell-mediated rejection (TCMR) in the first month and de novo donor-specific antibody (dnDSA) formation. A total of 9 (20%) patients displayed TCMR. HLA-A, HLA-B, HLA-C, and HLA-DRB1 eplet MM numbers were not associated with TCMR. By contrast, HLA-DQB1 eplet MM (DQB1-EpMM) number was significantly high in patients with TCMR. The predicted indirectly recognizable HLA epitopes (PIRCHE-II) score for the HLA-DQB1 locus (DQB1-PIRCHE-II) was also significantly higher in the TCMR group than in the no-TCMR group. There was a high probability for TCMR to occur with either a DQB1-EpMM ≥7 or a DQB1-PIRCHE-II ≥13. Pretransplant mixed lymphocyte response analyses indicated that there were no significant differences between the antidonor T cell proliferation activities of patients with low-number (<7) and high-number (≥7) DQB1-EpMMs. However, the proportion of CD25 expression on proliferating antidonor CD8⁺ T cells, used as a cytotoxic activity marker, was high in DQB1-EpMMs ≥7. Moreover, both DQB1-EpMMs ≥9 and DQB1-PIRCHE-II ≥3 were predictors of dnDSA formation. Thus, MM analysis may be applied toward tailored immunosuppression based on individual risks.

Immunosuppression in liver and intestinal transplantation

Immunosuppression handling plays a key role in the early and long-term results of transplantation. The development of multiple immunosuppressive drugs led to numerous clincial trials searching to reach the ideal regimen. Due to heterogeneity of the studied patient cohorts and flaws in many, even randomized controlled, study designs, the answer still stands out. Nowadays triple-drug immunosuppression containing a calcineurin inhibitor (preferentially tacrolimus), an antimetabolite (using mycophenolate moffettil or Azathioprine) and short-term steroids with or without induction therapy (using anti-IL2 receptor blocker or anti-lymphocytic serum) is the preferred option in both liver and intestinal transplantation. This chapter aims, based on a critical review of the definitions of rejection, corticoresistant rejection and standard immunosuppression to give some reflections on how to reach an optimal immunosuppressive status and to conduct trials allowing to draw solid conclusions. Endpoints of future trials should not anymore focus on biopsy proven, acute and chronic, rejection but also on graft and patient survival. Correlation between early- and long-term biologic, immunologic and histopathologic findings will be fundamental to reach in much more patients the status of operational tolerance.

miR-210 Participates in Hepatic Ischemia Reperfusion Injury by Forming a Negative Feedback Loop With SMAD4

BACKGROUND AND AIMS

Hepatic ischemia-reperfusion (IR) injury is a major complication of liver transplantation, resection, and hemorrhagic shock. Hypoxia is a key pathological event associated with IR injury. MicroRNA-210 (miR-210) has been characterized as a micromanager of hypoxia pathway. However, its function and mechanism in hepatic IR injury is unknown.

APPROACH AND RESULTS

In this study, we found miR-210 was induced in liver tissues from patients subjected to IR-related surgeries. In a murine model of hepatic IR, the level of miR-210 was increased in hepatocytes but not in nonparenchymal cells. miR-210 deficiency remarkably alleviated liver injury, cell inflammatory responses, and cell death in a mouse hepatic IR model. In vitro, inhibition of miR-210 decreased hypoxia/reoxygenation (HR)-induced cell apoptosis of primary hepatocytes and LO2 cells, whereas overexpression of miR-210 increased cells apoptosis during HR. Mechanistically, miR-210 directly suppressed mothers against decapentaplegic homolog 4 (SMAD4) expression under normoxia and hypoxia condition by directly binding to the 3' UTR of SMAD4. The pro-apoptotic effect of miR-210 was alleviated by SMAD4, whereas short hairpin SMAD4 abrogated the anti-apoptotic role of miR-210 inhibition in primary hepatocytes. Further studies demonstrated that hypoxia-induced SMAD4 transported into nucleus, in which SMAD4 directly bound to the promoter of miR-210 and transcriptionally induced miR-210, thus forming a negative feedback loop with miR-210.

CONCLUSIONS

Our study implicates a crucial role of miR-210-SMAD4 interaction in hepatic IR-induced cell death and provides a promising therapeutic approach for liver IR injury.

Understanding, predicting and achieving liver transplant tolerance: from bench to bedside

In the past 40 years, liver transplantation has evolved from a high-risk procedure to one that offers high success rates for reversal of liver dysfunction and excellent patient and graft survival. The liver is the most tolerogenic of transplanted organs; indeed, immunosuppressive therapy can be completely withdrawn without rejection of the graft in carefully selected, stable long-term liver recipients. However, in other recipients, chronic allograft injury, late graft failure and the adverse effects of anti-rejection therapy remain important obstacles to improved success. The liver has a unique composition of parenchymal and immune cells that regulate innate and adaptive immunity and that can promote antigen-specific tolerance. Although the mechanisms underlying liver transplant tolerance are not well understood, important insights have been gained into how the local microenvironment, hepatic immune cells and specific molecular pathways can promote donor-specific tolerance. These insights provide a basis for the identification of potential clinical biomarkers that might correlate with tolerance or rejection and for the development of novel therapeutic targets. Innovative approaches aimed at promoting immunosuppressive drug minimization or withdrawal include the adoptive transfer of donor-derived or recipient-derived regulatory immune cells to promote liver transplant tolerance. In this Review, we summarize and discuss these developments and their implications for liver transplantation.

Immunostaining Patterns of Posttransplant Liver Biopsies Using 2 Anti-C4d Antibodies

Histopathologic diagnosis of antibody-mediated rejection in posttransplant liver biopsies is challenging. The recently proposed diagnostic criteria by the Banff Working Group on Liver Allograft Pathology require positive C4d immunohistochemical staining to establish the diagnosis. However, the reported C4d staining patterns vary widely in different studies. One potential explanation may be due to different antibody preparations used by different investigators. In this study, posttransplant liver biopsies from 69 patients histopathologically diagnosed with acute cellular rejection, chronic rejection, or recurrent hepatitis C were immunohistochemically stained using 2 polyclonal anti-C4d antibodies. On the basis of the distribution of C4d immunoreactivity, 5 different staining patterns were observed: portal vein and capillary, hepatic artery, portal stroma, central vein, and sinusoids. The frequency, extent, and intensity of positive C4d staining with the 2 antibody preparations differed significantly for portal veins/capillaries and central veins, but not for hepatic arteries and portal stroma. Positive sinusoidal staining was seen in only 1 case. There were no significant differences in the frequency, extent, and intensity of positive C4d staining among the acute cellular rejection, chronic rejection, and recurrent hepatitis C groups with the 2 anti-C4d antibodies. These data show that different anti-C4d antibodies can show different staining patterns, which may lead to different interpretation. Caution is thus needed when selecting C4d antibodies for clinical use to aid in the diagnosis of antibody-mediated rejection.

Intrahepatic Microdialysis for Monitoring of Metabolic Markers to Detect Rejection Early After Liver Transplantation

OBJECTIVES

The clinical and biochemical manifestations of acute rejection after liver transplantation are nonspecific, and a liver biopsy is often needed to verify the diagnosis. This may delay treatment. The aim of this study was to evaluate whether monitoring of intrahepatic glucose, lactate, pyruvate, and glycerol by microdialysis can be used to predict rejection early after liver transplantation.

METHODS

Seventy-one patients undergoing liver transplantation were included in the study. The patients were monitored using microdialysis for up to 6 days postoperatively. Patients who developed acute rejection within 1 month were identified according to standard protocol. Area under the curve (AUC) was calculated for 12-hour intervals for glucose, lactate, pyruvate, glycerol, and lactate/pyruvate ratio. Patients with and without rejection were compared with respect to these parameters, as well as standard liver blood investigations and time-zero biopsies.

RESULTS

The lactate/pyruvate ratio was higher at 0 to 12 hours in the group with rejection as compared to the group without rejection. Glucose was lower in the group with rejection at 24 to 48 hours. Also, the intrahepatic lactate levels at 48 to 72 hours and pyruvate levels at 60 to 72 hours after liver transplantation, were higher in the rejection group. The lactate/pyruvate ratio at 0 to 12 hours and lactate at 60 to 72 hours were two independent risk factors for rejection within the first month after liver transplantation. No significant differences in glycerol levels could be detected between the two patient groups.

CONCLUSIONS

Microdialysis monitoring following liver transplantation may be useful in the detection of the metabolic events that precede rejection. The metabolic patterns detected by microdialysis early after transplantation indicate a possible relation between primary ischemia-reperfusion injury and the development of rejection. Identifying these patterns may help to identify patients at risk for the development of acute rejection and may help select those who may benefit from higher dose of immunosuppression early after liver transplantation.

The Human Immune Response to Cadaveric and Living Donor Liver Allografts

The liver is an important contributor to the human immune system and it plays a pivotal role in the creation of both immunoreactive and tolerogenic conditions. Liver transplantation provides the best chance of survival for both children and adults with liver failure or cancer. With current demand exceeding the number of transplantable livers from donors following brain death, improved knowledge, technical advances and the desire to prevent avoidable deaths has led to the transplantation of organs from living, ABO incompatible (ABOi), cardiac death donors and machine based organ preservation with acceptable results. The liver graft is the most well-tolerated, from an immunological perspective, of all solid organ transplants. Evidence suggests successful cessation of immunosuppression is possible in ~20–40% of liver transplant recipients without immune mediated graft injury, a state known as “operational tolerance.” An immunosuppression free future following liver transplantation is an ambitious but perhaps not unachievable goal. The initial immune response following transplantation is a sterile inflammatory process mediated by the innate system and the mechanisms relate to the preservation-reperfusion process. The severity of this injury is influenced by graft factors and can have significant consequences. There are minimal experimental studies that delineate the differences in the adaptive immune response to the various forms of liver allograft. Apart from ABOi transplants, antibody mediated hyperacute rejection is rare following liver transplant. T-cell mediated rejection is common following liver transplantation and its incidence does not differ between living or deceased donor grafts. Transplantation in the first year of life results in a higher rate of operational tolerance, possibly due to a bias toward Th2 cytokines (IL4, IL10) during this period. This review further describes the current understanding of the immunological response toward liver allografts and highlight the areas of this topic yet to be fully understood.

Ectonucleoside triphosphate diphosphohydrolase 1 and 5'-nucleotidase ecto gene polymorphisms and acute cellular rejection after liver transplantation

The single nucleotide polymorphisms (SNPs) rs11188513, rs7071836, rs10748643, rs9450279, rs4458647, and rs6922 map in the genes of ectonucleoside triphosphate diphosphohydrolase 1 (ENTPD1) and 5'-nucleotidase ecto. We investigated whether these SNPs and haplotypes of these SNPs are associated with an acute cellular rejection after liver transplantation. A total of 69 recipients with an acute cellular rejection and 138 recipients without an acute cellular rejection were analyzed. Analyzed individually, no SNP demonstrates an association, but the haplotype rs11188513T-rs7071836G-rs10748643A of the ENTPD1 gene appeared more frequently in recipients without rejection and conversely, the haplotype rs11188513T-rs7071836G-rs10748643G of the ENTPD1 gene was more often represented in recipients with rejection. These two haplotypes seem to be important for the susceptibility of an acute cellular rejection after liver transplantation.

Surveillance for acute cellular rejection after lung transplantation

Acute cellular rejection (ACR) is a common complication following lung transplantation (LTx), affecting almost a third of recipients in the first year. Established, comprehensive diagnostic criteria exist but they necessitate allograft biopsies which in turn increases clinical risk and can pose certain logistical and economic problems in service delivery. Undermining these challenges further, are known problems with inter-observer interpretation of biopsies and uncertainty as to the long-term implications of milder or indeed asymptomatic episodes. Increased risk of chronic lung allograft dysfunction (CLAD) has long been considered the most significant consequence of ACR. Consensus is lacking as to whether this applies to mild ACR, with contradictory evidence available. Given these issues, research into alternative, minimal or non-invasive biomarkers represents the main focus of research in ACR. A number of potential markers have been proposed, but none to date have demonstrated adequate sensitivity and specificity to allow translation from bench to bedside.

Performance of B-mode ratio and 2D shear wave elastography for the detection and quantification of hepatic steatosis and fibrosis after liver transplantation

OBJECTIVES

To evaluate the diagnostic performance of B-mode ratio and shear wave elastography (SWE) for the assessment of steatosis and liver fibrosis after liver transplantation.

MATERIALS AND METHODS

Patients hospitalized for a systematic check-up after liver transplantation underwent the same day hepatic ultrasound with B-mode ratio and SWE, followed by liver biopsy and biological examinations. Steatosis was measured using hepatorenal sonographic index of B-mode ratio and liver stiffness using SWE. Liver biopsy, used as gold standard, graded steatosis S0(<5%), S1(5-<33%), S2(33-<66%), or S3(≥66%) and liver fibrosis according to the Metavir score. The results were tested against two external validation cohorts.

RESULTS

Fifty-eight patients were included. Mean B-ratio value was significantly higher in patients with steatosis (0.95 ± 0.13 versus 1.39 ± 0.41, P < 0.001). A B-mode ratio cutoff values at least 0.985 was found optimal for steatosis' detection [area under the receiver operating characteristic curve (AUROC) 0.902 ± 0.05, sensitivity 95%, specificity 79%]. A B-mode ratio value below 0.9 ruled out steatosis and above 1.12 ruled in steatosis. Mean SWE value for patients without significant fibrosis (≤F1) was 15.90 ± 9.2 versus 19.27 ± 7.7 kPa for patients with fibrosis (P = 0.185). A 2D-SWE value below 7.85 kPa ruled out significant fibrosis and above 26.35 kPa ruled it in.

CONCLUSION

The B-mode ratio is an efficient and accurate tool for the noninvasive diagnostic of steatosis in postliver transplantation patients. Yet, because liver stiffness is higher in postliver transplantation patients, 2D-SWE is not reliable in the diagnosis of significant fibrosis after liver transplantation.

CD47 blockade alleviates acute rejection of allogeneic mouse liver transplantation by reducing ischemia/reperfusion injury

Despite advances in immunosuppressive therapies, acute rejection response is still a serious concern especially in the early phase after liver transplantation. This study aimed to evaluate whether blocking the TSP1-CD47 signaling pathway could attenuate the acute rejection after liver transplantation. An allogeneic mouse orthotopic liver transplantation model (Balb/c→C3H) with prolonged cold ischemic phase was used to induce severe IRI and lethal acute rejection. CD47mAb or isotype matched-control IgG_2a was administered to donor liver during graft perfusion. Recipients were sacrificed at 1d, 3d, 5d and 7d after reperfusion. Blood samples were collected to evaluate serum alanine aminotransferase, total bilirubin, HMGB-1,TNF-α, IL-2 and INF-γ level. Flow cytometric analysis was used to detect the strength of innate and adaptive immune response. Liver tissue was obtained for HE, TUNEL staining and F4/80 immumohistochemical staining. Moreover, we conducted a mixed lymphocyte reaction treated with IgG_2a or CD47mAb. Mice in CD47mAb-treated group demonstrated improved survival and significantly lower increase in Suzuki score, apoptosis index, acute rejection index, serum alanine aminotransferase, total bilirubin, HMGB-1, TNF-α, IL-2, INF-γ level and the degree of Kupffer cells' activation especially in the early phase of acute rejection. In addition, Pearson's correlation analysis confirmed significant correlation between Suzuki score/ALT and acute rejection index. The in vitro inhibition assay showed that CD47 blockade couldn't directly inhibit recipient lymphocyte proliferation. Based on the evidence that TSP1-CD47 signaling blockade with CD47mAb could alleviate acute rejection by reducing the extent of IRI after liver transplantation indirectly, this study provided a basis for new interventions and management methods to support better transplant outcomes.

Protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene polymorphisms in liver transplant donors and impact on acute cellular liver transplant rejection

The PTPN22 gene encodes the lymphoid protein tyrosine phosphatase involved in regulation the immune response. The single nucleotide polymorphisms (SNPs) rs1217388, rs1310182, rs2476601, and rs2488457 are located within the PTPN22 gene. We investigated whether these SNPs in liver transplant donors are associated with acute cellular rejection in the recipients. The SNPs were analyzed in donors (n = 104) of recipients who did not develop an acute cellular rejection and in donors (n = 53) of corresponding recipients developing an acute cellular rejection. No significant differences in genotype and allele frequencies of these SNPs were detected in either of the group. Our data suggest that these SNPs in liver transplant donors have no impact on the susceptibility of acute cellular liver transplant rejection.

Immune function as predictor of infectious complications and clinical outcome in patients undergoing solid organ transplantation (the ImmuneMo:SOT study): a prospective non-interventional observational trial

Background

Solid organ transplantation (SOT) is a well-established and life-saving treatment for patients with end-stage organ failure. Organ rejection and infections are among the main complications to SOT and largely determines the clinical outcome. The correct level of immunosuppression is of major importance to prevent these complications. However, it is a consistent observation that in recipients on the same immunosuppressive regimens the clinical outcome varies, and no reliable marker exists to monitor immune function.

Methods

In a prospective, observational study, we plan to enroll 630 adult patients with a planned organ transplantation at Rigshospitalet, University of Copenhagen, Denmark. Prior to and on different time points up to two years after transplantation we will perform a complete immunological profile on the recipients. This profile will consist of classical descriptive immune phenotyping (flow cytometry and circulating biomarkers) and the functional assay TruCulture®. In TruCulture® whole blood is incubated ex vivo with stimulants imitating bacterial, viral and fungal infections, where after a panel of selected cytokines is quantified. Clinical data from electronic health records will be obtained from the PERSIMUNE (Centre of Excellence for Personalized Medicine of Infections Complications in Immune Deficiency at Rigshospitalet, Copenhagen) data repository, a warehouse of data generated as part of routine care including vital signs, biochemistry, microbiology, pathology as well as medication, demographics, diagnoses, hospital contacts, surgical procedures and mortality.

Discussion

This will be the first large scale study to determine several aspects of immune function and perform a complete immunological profiling in SOT recipients. It is expected that knowledge generated will provide information to generate prediction models identifying patients at increased risk of infection and/or rejection. If the study is successful, we will subsequently use the generated prediction models to propose personalized immunosuppressive regimens to be tested in future randomized controlled trials.

Trial registration

This study has been approved by the Regional ethical committee (H-17024315), the Danish Data Protection Agency (RH-2016-47, RH-2015-04, I-Suite 03605) and the Danish National board of Health (3–3013-1060/1). The trial is retrospectively registered at clinicaltrials.gov (NCT03847285) the 20th February 2019.

Inhibition of Autophagy Prolongs Recipient Survival Through Promoting CD8+ T Cell Apoptosis in a Rat Liver Transplantation Model

In liver transplantation (LT), although various immunosuppressants have been used in clinical practice, acute rejection remains a common complication that significantly shortens recipient survival. In recent years, manipulating immune tolerance has been regarded as one of the promising solutions to rejection. Autophagy, an evolutionarily conserved protein degradation system, has been reported to be involved in immune rejection and may be a target to establish immune tolerance. However, the role of autophagy in acute rejection reaction after LT has not been elucidated. Here, we showed that the autophagy of CD8⁺ T cells was strongly enhanced in patients with graft rejection and that the autophagy level was positively correlated with the severity of rejection. Similar findings were observed in a rat acute hepatic rejection model. Furthermore, administration of the autophagy inhibitor 3-methyladenine (3-MA) largely decreased the viability and function of CD8⁺ T cells through inhibiting autophagy, which significantly prolonged graft survival in rats. In addition, inhibiting the autophagy of activated CD8⁺ T cells in vitro considerably suppressed mitochondria mediated survival and downregulated T cell function.

Conclusions: We first showed that the inhibition of autophagy significantly prolongs liver allograft survival by promoting the apoptosis of CD8⁺ T cells, which may provide a novel strategy for immune tolerance induction.

Early post-operative intravenous tacrolimus in pediatric liver transplant recipients is not superior to oral tacrolimus

We aimed to compare the early results of i.v. with p.o. TAC as a primary immunosuppressant in pediatric patients undergoing LT. This retrospective study enrolled 75 children who underwent LT and received TAC-steroid regimens as a primary immunosuppressant between September 2011 and October 2015 at our institution. Thirty-five recipients received TAC i.v. and 40 received TAC p.o. Early results were evaluated and compared, including ACR, EBV, or CMV infection; renal adverse effects; and hospital stay. Comparisons of 90-day post-transplant results showed that the rates of overall viral (74% vs 40% P < 0.002), EBV (46% vs 17.5% P < 0.008), and CMV (51% vs 30% P = 0.05) infections were significantly higher in the i.v. than in the p.o. group. Neither regimen has any adverse effects on renal function. There were no between-group differences in ACR incidence and severity, serum creatinine concentration, and hospital stay. Patient and graft survival rates at 3 months and 1 year did not differ significantly between the two groups. Compared with p.o. treatment, i.v. administration of high TAC concentration did not have beneficial post-transplant effects on ACR incidence and severity, while increasing the incidence of viral infections in pediatric LT.

Not All Cellular Rejections Are the Same: Differences in Early and Late Hepatic Allograft Rejection

T cell-mediated rejection (TCMR) is common after liver transplantation (LT), and it is often thought to have a minimum impact on outcomes. Because alloimmune response changes over time, we investigated the role of the timing of TCMR on patient and allograft survival and examined the risk factors for early and late TCMR. We reviewed protocol liver biopsies for 787 consecutive LT recipients with an 8.6-year follow-up. The incidence of early TCMR (≤6 weeks after LT) was 33.5% with nonalcoholic steatohepatitis patients having the lowest incidence. Younger recipient age (P < 0.01), number of human leukocyte antigen mismatches (P < 0.01), and use of deceased donor allografts (P = 0.01) were associated with increased risk of early TCMR, which had no impact on allograft (hazard ratio [HR], 1.02; 95% CI, 0.79-1.32; P = 0.89) or overall survival (HR, 1.03; 95% CI, 0.78-1.34; P = 0.86). Late TCMR (>6 weeks after LT) was less common (17.7%) and was associated with different risk factors. The majority of late TCMR (56.2%) episodes had no antecedent early TCMR, although moderate-to-severe early TCMR (HR, 2.85; 95% CI, 1.55-5.23; P < 0.01) and steroid resistance (HR, 3.62; 95% CI, 1.87-6.99; P < 0.01) were associated with late TCMR. Late TCMR increased risk of mortality (HR, 1.89; 95% CI, 1.35-2.65; P = 0.001) and graft loss (HR, 1.71; 95% CI, 1.23-2.37; P = 0.001). Thus, these data suggest that the timing and histologic grade of TCMR determine its impact on patient and allograft survival. Early mild TCMR episodes after LT do not adversely impact patient or allograft survival provided that they are adequately treated. The occurrence of late TCMR carries deleterious effects with increased longterm risk of graft loss and decreased survival. Patients with moderate-to-severe early TCMR are at an increased risk for late TCMR and warrant closer clinical follow-up.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

KEY POINTS

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

Impact of TBX21, GATA3, and FOXP3 gene polymorphisms on acute cellular rejection after liver transplantation

The single nucleotide polymorphisms (SNPs) rs4794067, rs2275806, rs2232365, and rs3761548 map in the genes of TBX21, GATA3, and FOXP3 involved in mediating acute cellular rejection. We investigated whether these SNPs are associated with acute cellular liver transplant rejection. The SNPs were analyzed in recipients with early acute cellular rejection (n = 97), recipients with late acute cellular rejection (n = 49), and recipients without rejection (n = 149). There was no association between acute cellular rejection and SNPs rs4794067, rs2275806, and rs2232365. In contrast, the allele -3279A of FOXP3 SNP rs3761548 exhibited a higher frequency in recipients with late acute cellular rejection as compared with recipients without rejection. This result indicates that the allele -3279A of the SNP rs3761548 may predispose to the development of late acute cellular rejection.

Graft Dysfunction and Management in Liver Transplantation

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

Clinical and Morphologic Diagnostic Assessments of Liver Diseases After Liver Transplant

OBJECTIVES

At the National Scientific Center of Surgery named A. Syzganova, more than 100 liver transplants have been conducted from 2012 to November 2017. Survival and quality of life of patients in the posttransplant period largely depend on the compliance of patients, monitoring of complications, cause of liver disease, the severity of the condition of patients in the pretransplant period, and the technical features of the operation. The aims of the study were to analyze the results of liver biopsy in patients after liver transplant and to evaluate the value of morphologic studies of the liver for the diagnosis of complications in the posttransplant period.

MATERIALS AND METHODS

Liver transplant recipients undergoing liver biopsy between 2012 and 2017 were analyzed. Our study included 40 liver biopsies in 29 patients after orthotopic liver transplant who fulfilled the inclusion criteria.

RESULTS

In 51.7% of cases in patients (that is, in 15 of 29 patients), biopsy data revealed changes characteristic of rejection. Biliary complications were found in 10.34% of patients, recurrent liver diseases were confirmed in 17.24% of patients, 3.45% of patients had confirmed cholangitis, and 6.90% of patients were diagnosed with liver steatosis.

CONCLUSIONS

Histopathology assessment of allograft liver biopsies plays an important role in the differential diagnosis of posttransplant complications and in identifying the cause of graft damage; having this information can lead to the appropriate therapeutic intervention.

Acute allograft rejection in liver transplant recipients: Incidence, risk factors, treatment success, and impact on graft failure

Objective This study was performed to identify risk factors for acute cellular rejection after liver transplantation (LT). Methods Consecutive LT recipients who underwent surgery in our institution from 2002 to 2015 were retrospectively evaluated. Results In total, 176 patients were eligible for statistical analysis. During a mean observation period of 61.1 ± 36.3 months, 43 episodes of acute rejection were evident. Of these, 34 (79.0%) were responsive to methylprednisolone, 3 (7.0%) were treated by adjusting the dosage of immunosuppressive agents, and 6 (14.0%) were methylprednisolone-resistant and treated using anti-thymocyte globulin. Biliary complications (odds ratio [OR] = 4.89, 95% confidence interval [CI] = 2.00-11.98); donor-negative, recipient-positive CMV mismatch (OR = 9.88, 95% CI = 1.18-82.36); sex mismatch (OR = 3.16, 95% CI = 1.31-8.10); and sex mismatch with a female donor (OR = 3.00, 95% CI = 1.10-7.58) were identified as significant risk factors for acute graft rejection after LT. Conclusion In patients who develop acute cellular rejection after LT, biliary complications should be evaluated as a potential cause. Most acute rejections after LT respond to bolus corticosteroid therapy.

Lower tacrolimus trough levels in the late period after living donor liver transplantation contribute to improvements in long-term clinical outcomes

BACKGROUND

Previous studies have emphasized the need to reduce tacrolimus (TAC) trough levels in the early post-liver transplantation (LT) period. However, whether late-period TAC trough levels influence the long-term outcomes of liver recipients is not clear.

METHODS

We enrolled 155 adult liver recipients survived more than 3 years after living donor liver transplantation because of non-malignant liver diseases. The maintenance immunosuppressive regimens were TAC monotherapy and combined therapy with mycophenolate mofetil. Patients were divided into three groups according to their late-period TAC trough levels: < 3 ng/mL group, 3-5 ng/mL group, and  >5 ng/mL group. The complications and adverse effects of TAC were analyzed.

RESULTS

Each group showed similar rejection, graft loss and mortality. Patients achieved the < 5 ng/mL state in less than 4 years had fewer new-onset diabetes, hyperlipidemia, de novo malignancies, and hepatitis B virus recurrence; the complications of renal dysfunction and hypertension rates were the same among these 3 groups.

CONCLUSIONS

Collectively, our findings indicated that lower TAC trough levels in the late period of liver transplantation are safe, improve the long-term outcomes.