Chronic rejection after liver transplantation: Opening the Pandora’s box

Diagnostic and predictive biomarkers of acute rejection after liver transplantation

Liver transplantation serves as a vital therapeutic intervention for individuals suffering from end-stage liver disease globally. A significant complication encountered by liver transplant recipients during the postoperative period is acute rejection, which has traditionally been identified through invasive graft biopsy procedures. Furthermore, assessing the immune status of liver transplant patients is essential for effective posttransplant management and represents a significant advancement toward the personalization of immunosuppressive therapy. Nevertheless, current immunological monitoring after the transplantation predominantly depends on clinical judgment and the measurement of immunosuppressive drug levels, lacking a comprehensive evaluation of actual immune system suppression. In contrast, biomarkers offer a comparatively novel and safer approach for the detection and prediction of transplant rejection, though their clinical application remains constrained due to the absence of prospective validation studies. This review examines the existing literature on potential biomarkers for acute rejection following liver transplantation, and their implications for clinical decision-making.

Ex vivo machine perfusion as a platform for lentiviral gene delivery in rat livers

Developing new strategies for local monitoring and delivery of immunosuppression is critical to making allografts safer and more accessible. Ex vivo genetic modification of grafts using machine perfusion presents a promising approach to improve graft function and modulate immune responses while minimizing risks of off-target effects and systemic immunogenicity in vivo. This proof-of-concept study demonstrates the feasibility of using normothermic machine perfusion (NMP) to mimic in vitro conditions for effective gene delivery. In this study, lentiviral vectors encoding the secreted biomarker Gaussia Luciferase (GLuc) and red fluorescent protein (RFP) were introduced ex vivo to rodent livers during a 72-h machine perfusion protocol. After an initial 24-h exposure to viral vectors, the organs were maintained in perfusion for an additional 48 h to monitor gene expression, aligning with in vitro benchmarks. Control livers were perfused in similar fashion, but without viral injections. Virally perfused livers exhibited nearly a 10-fold increase in luminescence compared to controls (p < 0.0001), indicating successful genetic modification of the organs. These findings validate the use of machine perfusion systems and viral vectors to genetically engineer whole organs ex vivo, laying the groundwork for a broad range of applications in transplantation through genetic manipulation of organ systems. Future studies will focus on refining this technology to enhance precision in gene expression and explore its implications for clinical translation.

Latin American association for the study of the liver (ALEH) guidance on postoperative care after liver transplantation

Liver transplantation (LT) is a well-established therapy for patients with decompensated cirrhosis and early-stage hepatocellular carcinoma. Liver transplantation activity varies sharply across Latin American (LATAM) countries due to differences in resources, expertise, and funding and local attitudes toward organ donation and transplantation. This current guidance of postoperative care after LT is the first position paper of the Latin American Association for the Study of the Liver (ALEH) Special Interest Group (SIG), drawing evidence-based recommendations regarding immediate and long-term postoperative care of LT recipients, taking into consideration their applicability in Latin America.

Where Are All the Clinical Trials for Chronic Rejection?

Chronic rejection is arguably the main obstacle to long-term graft survival. Yet, clinical trials focusing on this condition are disappointingly scarce. Significant advances in treating chronic rejection cannot happen if there is no conduit for testing novel therapies. Here, we identified the main hurdles holding back clinical trials for chronic rejection and outlined a series of actions to address these roadblocks. We suggest that a new strategic plan combining expertise in basic and clinical research and leveraging complementary resources be launched to specifically target chronic rejection and achieve long-awaited progress. We only need the will.

Two-Dimensional Shear Wave Ultrasound Elastography for Monitoring Pediatric Liver Transplantation: A Review of Recent Advances

Pediatric liver transplantation (PLT) is a life-saving procedure for children with end-stage liver disease. However, post-transplant monitoring, particularly the diagnosis and prognosis of complications such as allograft fibrosis, remains challenging. Traditionally, liver biopsy has been the gold standard for assessing allograft fibrosis, despite its invasive nature and inherent procedural risks. Recently, shear wave ultrasound elastography (SWE) has seen increasing use as a noninvasive method to provide real-time, quantitative measurements of liver stiffness as a proxy for fibrosis. In this review, the latest developments in the use of SWE as a method to assess allograft fibrosis post-PLT are presented, including the current technical challenges associated with its clinical implementation.

Animal models for transplant immunology: bridging bench to bedside

The progress of transplantation has been propelled forward by animal experiments. Animal models have not only provided opportunities to understand complex immune mechanisms in transplantation but also served as a platform to assess therapeutic interventions. While small animals have been instrumental in uncovering new therapeutic concepts related to immunosuppression and immune tolerance, the progression to human trials has largely been driven by studies in large animals. Recent research has begun to explore the potential of porcine organs to address the shortage of available organs. The consistent progress in transplant immunology research can be attributed to a thorough understanding of animal models. This review provides a comprehensive overview of the available animal models, detailing their modifications, strengths, and weaknesses, as well as their historical applications, to aid researchers in selecting the most suitable model for their specific research needs.

Network meta-analysis of pharmacological treatment for antibody-mediated rejection after organ transplantation

Objective

This study aims to assess the efficacy of pharmacological interventions in mitigating graft injury in transplant patients with antibody-mediated rejection (AMR) through a network meta-analysis (NMA).

Methods

A search was conducted on databases such as Cochrane Library, PubMed, EmBase, and Web of Science for randomized controlled trials (RCTs) on pharmacological interventions for alleviating graft injury following AMR. The search was performed for publications up to April 12, 2024. Two reviewers conducted independent reviews of the literature, extracted data, and assessed the risk of bias (ROB) in the included studies using the ROB assessment tool recommended by the Cochrane Handbook for Systematic Reviews of Interventions 5.1.0. A Bayesian NMA was conducted using R 4.4.0, RStudio software, and the GeMTC package to assess the outcomes in estimated glomerular filtration rate (eGFR), mean fluorescence intensity (MFI), g-score, and infection under pharmacological treatments.

Results

A total of 8 RCTs involving 215 patients and 6 different pharmacological treatments were included in this NMA. The results indicated that the increase in eGFR by eculizumab (SUCRA score: 81) appeared to be more promising. The decrease in MFI by bortezomib (SUCRA score: 72.3), rituximab (SUCRA score: 68.2), and clazakizumab (SUCRA score: 67.1) demonstrated better efficacy. The decrease in g-score by eculizumab (SUCRA score: 74.3), clazakizumab (SUCRA score: 72.2), and C1INH (SUCRA score: 63.6) appeared to have more likelihood. For infection reduction, clazakizumab (SUCRA score: 83.5) and bortezomib (SUCRA score: 66.8) might be better choices.

Conclusion

The results of this study indicate that eculizumab has the potential to enhance eGFR and reduce g-score. Bortezomib demonstrates superior efficacy in reducing MFI. Clazakizumab appears to be more effective in reducing infections.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42024546483.

Evaluating the Impact of Phosphatidylethanol Testing on Hospital Outcomes

Background

Alcohol dependence remains a significant global health issue, exacerbated by the coronavirus disease 2019 (COVID-19) pandemic. Phosphatidylethanol (PEth), a direct biomarker of recent alcohol consumption, offers improved specificity, sensitivity, and a longer detection window of 2 - 4 weeks compared to traditional biomarkers. This study evaluates the association between PEth testing and hospital outcomes in hospitalized patients by comparing outcomes among patients with positive PEth and negative PEth test results.

Methods

This retrospective cohort study used data from the TriNetX database, comprising de- identified medical records from 66 US healthcare organizations from 2015 to 2024. The study population included patients with documented PEth test results. Patients were divided into two groups: positive PEth test results (≥ 20 ng/mL) and negative PEth test results (≤ 19 ng/mL). Propensity score matching was performed to minimize bias, balancing for age, sex, race, ethnicity, and comorbidities such as cirrhosis, diabetes mellitus, hypertension, coronary artery disease, and chronic obstructive pulmonary disease (COPD). Key hospital outcomes assessed included mortality, delirium tremens, endoscopy/colonoscopy, liver transplant status, liver transplant rejection, liver transplant complications, hepatorenal syndrome, intensive care unit (ICU) admission, hepatic encephalopathy, and sarcopenia. These outcomes were chosen based on their prevalence in patients with alcohol use.

Results

Patients with positive PEth results demonstrated significantly worse outcomes compared to patients in the negative PEth group. Positive PEth results were associated with higher mortality (odds ratio, 10.037; P < 0.001), ICU admissions, and rates of complications such as hepatorenal syndrome, hepatic encephalopathy, and sarcopenia. Postoperative liver transplant complications and rejection were also more frequent in the positive cohort.

Conclusions

This study highlights the association between recent alcohol use, as identified by PEth testing, and severe hospital outcomes. While PEth testing provides an objective measure of recent alcohol consumption, further research is needed to explore its role in improving clinical outcomes and guiding interventions for patients with alcohol use.

Role of mTOR Inhibitors in Pediatric Liver Transplant Recipients: A Systematic Review

BACKGROUND

Immunosuppressive medications play a crucial role in determining both organ and patient survival following liver transplantation (LT). Typically, immunosuppressive protocols for pediatric LT patients rely on calcineurin inhibitors (CNIs). While inhibitors of mammalian target of rapamycin (mTOR) have demonstrated beneficial outcomes in adult recipients of liver allografts, such as improved renal function post-LT, their application in pediatric liver transplant recipients is a subject of debate due to uncertain efficacy and potential adverse effects.

OBJECTIVES

This review evaluates the potential roles of mTOR inhibitors in the context of pediatric LT patients.

METHODS

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol for conduct and reporting. Databases until 31 August 2023 were searched using specific terms and keywords. All clinical studies focusing on mTOR inhibitors in pediatric LT were included.

RESULTS

Out of 888 identified articles, 30 studies, involving 386 children who had undergone liver transplantation and received mTOR-inhibitor-based immunosuppressive regimens, met the inclusion criteria. The beneficial impacts of switching from a CNI to an mTOR inhibitor or adding an mTOR inhibitor to CNI-reduced immunosuppression in LT pediatric patients with impaired kidney function are controversial, and high-powered clinical studies are need. It appears that enhancing immunosuppression by adding an mTOR inhibitor to CNI is helpful for pediatric LT recipients who are experiencing refractory acute rejection or chronic rejection. mTOR-inhibitor-containing regimens failed to reduce the occurrence of post-transplant lymphoproliferative disorders (PTLD) among children with LT that may be due to concomitant high CNI concentration among studied patients. The effectiveness of mTOR inhibitors in treating PTLD remains uncertain; however, in patients with PTLD who are at high risk of rejection, mTOR inhibitors may be administered. Conversion to or the addition of mTOR inhibitors to maintenance immunosuppression seems to be suitable for pediatric patients who received a transplant due to hepatic malignancies such as hepatoblastoma or hepatocellular carcinoma or for those with post-transplant primary or recurrent malignancies. Switching to an mTOR inhibitor may improve some CNI-related adverse effects such as gingival hyperplasia, neurotoxicity, nephropathy, hypertrophic cardiomyopathy, or thrombotic microangiopathy.

CONCLUSION

Although the exact role of mTOR inhibitors among pediatric patients who have received a liver transplant needs further study, two algorithms are presented in this review to guide conversion from CNIs to mTOR inhibitors or the addition of mTOR inhibitor to a CNI-minimization immunosuppressive regimen for pediatric patients who may benefit from this class of drugs. This review mainly consisted of retrospective studies with inadequate sample sizes and lacked a control group, which represents the main limitation of this study.

Nanoparticle-assisted Targeting Delivery Technologies for Preventing Organ Rejection

Although organ transplantation is a life-saving medical procedure, the challenge of posttransplant rejection necessitates safe and effective immune modulation strategies. Nanodelivery approaches may have the potential to overcome the limitations of small-molecule immunosuppressive drugs, achieving efficacious treatment options for transplant tolerance without compromising overall host immunity. This review highlights recent advances in biomaterial-assisted formulations and technologies for targeted nanodrug delivery with transplant organ- or immune cell-level precision for treating graft rejection after transplantation. We provide an overview of the mechanism of transplantation rejection, current clinically approved immunosuppressive drugs, and their relevant limitations. Finally, we discuss the targeting principles and advantages of organ- and immune cell-specific delivery technologies. The development of biomaterial-assisted novel therapeutic strategies holds considerable promise for treating organ rejection and clinical translation.

Plasma immune signatures can predict rejection-free survival in the first year after pediatric liver transplantation

BACKGROUND & AIMS

After pediatric liver transplantation (pLT), children undergo life-long immunosuppression since reliable biomarkers for the assessment of rejection probability are scarce. In the multicenter (n = 7) prospective clinical cohort "ChilSFree" study, we aimed to characterize longitudinal dynamics of soluble and cellular immune mediators during the first year after pLT and identify early biomarkers associated with outcome.

METHODS

Using a Luminex-based multiplex technique paired with flow cytometry, we characterized longitudinal dynamics of soluble immune mediators (SIMs, n = 50) and immune cells in the blood of 244 patients at eight visits over 1 year: before, and 7/14/21/28 days and 3/6/12 months after pLT.

RESULTS

The unsupervised clustering of patients based on SIM profiles revealed six unique SIM signatures associated with clinical outcome. From three signatures linked to improved outcome, one was associated with 1-year-long rejection-free survival and stable graft function and was characterized by low levels of pro-inflammatory SIMs (CXCL8/9/10/12, CCL7, SCGF-β, sICAM-1), and high levels of regenerative (SCF, TNF-β) and pro-apoptotic (TRAIL) SIMs (all, p <0.001, fold change >100). Of note, this SIM signature appeared 2 weeks after pLT and remained stable over the entire year, pointing towards its potential as a novel early biomarker for minimizing or weaning immunosuppression. In the blood of these patients, a higher frequency of CD56bright natural killer cells (p <0.01), a known hallmark also associated with operationally tolerant pLT patients, was detected. The concordance of the model for prediction of rejection based on identified SIM signatures was 0.715, and 0.795, in combination with living-related transplantation as a covariate, respectively.

CONCLUSIONS

SIM blood signatures may enable the non-invasive and early assessment of rejection risks in the first year after pLT, paving the way for improved clinical management.

IMPACT AND IMPLICATIONS

ChilSFree represents the largest pediatric liver transplant (pLT) cohort with paired longitudinal data on soluble immune mediators (SIMs) and immune phenotyping in the first year after pLT. SIM signatures allow for the selection of rejection-free patients 2 weeks after pLT independently of patient diagnosis, sex, or age. The SIM signatures may enable the non-invasive and early assessment of rejection risks, paving the way for minimization or withdrawal of immunosuppression after pLT.

The Varying Histology of Hepatic Sarcoidosis and the Relation of Bile Duct Damage and Loss to the Presence of Portal Hypertension and Cirrhosis

Background and Aims

Sarcoidosis is a multisystem disorder characterized by nonnecrotizing granulomas. Studies suggest 20%-70% of patients with sarcoidosis have abnormal liver chemistries or abdominal imaging. Hepatic sarcoidosis may be complicated by portal hypertension (portal HTN) with or without cirrhosis. Few studies have reviewed the liver histopathology of sarcoidosis.

Methods

Searching the pathology database using the terms "sarcoidosis" and "liver," patients were identified and cross-referenced to patients in the Sarcoidosis Clinic. Patients met the diagnostic criteria for sarcoidosis. Those with isolated granulomatous hepatitis were excluded. Demographics, abdominal imaging, biochemistries, and detailed histological features were cataloged.

Results

Patients were separated into 2 groups: those with portal HTN with or without cirrhosis (pHTN+) and those without portal HTN (pHTN-). Fifty-three patients had biopsies available for review (pHTN+, n = 33; pHTN-, n = 20). The groups did not differ in the location, type, or number of granulomas. The pHTN + group had more bile duct damage (P = .025) and loss (P = .019). Patients in the pHTN + group also had biliary cirrhosis, nodular regenerative hyperplasia, or outflow obstruction.

Conclusion

There are several causes for portal HTN in sarcoidosis. Thus, liver biopsy is essential in its evaluation. Bile duct damage and loss are associated with the presence of portal HTN and cirrhosis. Biliary abnormalities may occur independently of granulomatous inflammation, and can thus identify a subset of patients at risk for progressive liver disease.

Colorectal cancer in ulcerative colitis after liver transplantation for primary sclerosing cholangitis: a systematic review and pooled analysis of oncological outcomes

INTRODUCTION

Patients with ulcerative colitis (UC) receiving liver transplantation (LT) due to primary sclerosing cholangitis (PSC) have higher risk of developing colorectal cancers (CRC). Aim of this systematic review was to define the patients' features, immunosuppressive management, and oncological outcomes of LT recipients with UC-PSC developing CRC.

METHODS

Searches were conducted in PubMed (MEDLINE), Cochrane Library, Web of Science for all English articles published until September 2023. Inclusion criteria were original articles including patients specifying outcomes of interest. Primary endpoints comprised incidence of CRC, disease free survival (DFS), overall survival (OS) and cancer recurrence. Secondary endpoints were patient's and tumor characteristics, graft function, immunosuppressive management and PSC recurrence. PROSPERO CRD42022369190.

RESULTS

Fifteen studies included, 88 patients were identified. Patients (mean age: 50 years) had a long history of UC (20 years), mainly with active colitis (79%), and developed tumor within the first 3 years from LT, while receiving a double or triple immunosuppressive therapy. Cumulative incidence of tumor was 5.5%. At one, two and three years, DFS was 92%, 82% and 75%, while OS was 87%, 81% and 79% respectively. Disease progression rate was 15%. After CRC surgery, 94% of patients maintained a good graft functionality, with no reported cases of PSC recurrence.

CONCLUSIONS

After LT, patients with PSC and UC have an increased risk of CRC, especially in presence of long history of UC and active colitis. Surgical resection guarantees satisfactory mid-term oncological outcomes, but samples are limited, and long-term data are lacking. National and international registry are auspicial to evaluate long-term oncological outcomes and to optimize clinical management.

The use of extracorporeal photopheresis in solid organ transplantation-current status and future directions

Prevention and management of allograft rejection urgently require more effective therapeutic solutions. Current immunosuppressive therapies used in solid organ transplantation, while effective in reducing the risk of acute rejection, are associated with substantial adverse effects. There is, therefore, a need for agents that can provide immunomodulation, supporting graft tolerance, while minimizing the need for immunosuppression. Extracorporeal photopheresis (ECP) is an immunomodulatory therapy currently recommended in international guidelines as an adjunctive treatment for the prevention and management of organ rejection in heart and lung transplantations. This article reviews clinical experience and ongoing research with ECP for organ rejection in heart and lung transplantations, as well as emerging findings in kidney and liver transplantation. ECP, due to its immunomodulatory and immunosuppressive-sparing effects, offers a potential therapeutic option in these settings, particularly in high-risk patients with comorbidities, infectious complications, or malignancies.

Immune response against bacterial infection in organ transplant recipients

This comprehensive review delves into the intricate dynamics between the immune system and bacterial infections in organ transplant recipients. Its primary objective is to fill existing knowledge gaps while critically assessing the strengths and weaknesses of current research. The paper accentuates the delicate balance that must be struck between preventing graft rejection through immunosuppression and maintaining robust immunity against bacterial threats. In this context, personalized medicine emerges as a transformative concept, offering the potential to revolutionize clinical outcomes by tailoring immunosuppressive regimens and vaccination strategies to the unique profiles of transplant recipients. By emphasizing the pivotal role of continuous monitoring, the review underscores the necessity for vigilant surveillance of transplant recipients to detect bacterial infections and associated immune responses early, thereby reducing the risk of severe infections and ultimately improving patient outcomes. Furthermore, the study highlights the significance of the host microbiome in shaping immune responses, suggesting that interventions targeting the microbiome hold promise for enhancing bacterial immunity in transplant recipients, both in research and clinical practice. In terms of future research directions, the review advocates for large-scale, longitudinal studies encompassing diverse patient cohorts to provide more comprehensive insights into post-transplant immune responses. It also advocates integrating multi-omics approaches, including genomics, transcriptomics, proteomics, and microbiome data, to understand immune responses and their underlying mechanisms. In conclusion, this review significantly enriches our understanding of immune responses in transplant recipients. It paves the way for more effective and personalized approaches to managing infections in this complex setting.

Ex Vivo Machine Perfusion as a Platform for Lentiviral Gene Delivery in Rat Livers

Developing new strategies for local monitoring and delivery of immunosuppression is critical to making allografts safer and more accessible. Ex vivo genetic modification of grafts using machine perfusion presents a promising approach to improve graft function and modulate immune responses while minimizing risks of off-target effects and systemic immunogenicity in vivo. This proof-of-concept study demonstrates the feasibility of using normothermic machine perfusion (NMP) to mimic in vitro conditions for effective gene delivery. In this study, lentiviral vectors carrying biosensor constructs with Gaussia Luciferase (GLuc) were introduced to rodent livers during a 72-hour perfusion period, with a targeted delivery of 3 × 107 infection units (IU). Following the initial 24-hour exposure required for viral transduction, an additional 48 hours was necessary to observe gene expression, analogous to in vitro benchmarks. The perfused livers displayed significantly increased luminescence compared to controls, illustrating successful genetic modification. These findings validate the ex vivo use of lentiviral particles in a rodent liver model and lay the groundwork for a broad range of applications through genetic manipulation of organ systems. Future studies will focus on refining this technology to enhance precision in gene expression and explore its implications for clinical transplantation.

Antibody-Mediated Rejection in Liver Transplantation: Immuno-Pathological Characteristics and Long-Term Follow-Up

The diagnosis of liver antibody-mediated rejection (AMR) is challenging and likely under-recognized. The association of AMR with donor-specific antibodies (DSA), and its clinical course in relation to pathologic findings and treatment are ill defined. We identified cases of liver AMR by following the criteria outlined by the 2016 Banff Working Group. Patient demographics, native liver disease, histopathologic findings, treatment type, clinical outcome, and transaminase levels during AMR diagnosis, treatment, and resolution were determined. Patients (n = 8) with AMR average age was 55.2 years (range: 19-68). Seven of eight cases met the Banff criteria for AMR. Personalized treatment regimens consisted of optimization of immunosuppression, intravenous pulse steroids, plasmapheresis, IVIG, rituximab, and bortezomib. Five patients experienced complete resolution of AMR, return of transaminases to baseline, and decreased DSA at long-term follow-up. One patient developed chronic AMR and two patients required re-transplantation. Follow-up after AMR diagnosis ranged from one to 11 years. Because AMR can present at any time, crossmatch, early biopsy, and routine monitoring of DSA levels should be implemented following transaminase elevation to recognize AMR. Furthermore, treatment should be immediately implemented to reverse AMR and prevent graft failure, chronic damage, re-transplantation, and possibly mortality.

Nanotechnology-based Strategies for Molecular Imaging, Diagnosis, and Therapy of Organ Transplantation

Organ transplantation is the preferred paradigm for patients with end-stage organ failures. Despite unprecedented successes, complications such as immune rejection, ischemia-reperfusion injury, and graft dysfunction remain significant barriers to long-term recipient survival after transplantation. Conventional immunosuppressive drugs have limited efficacy because of significant drug toxicities, high systemic immune burden, and emergence of transplant infectious disease, leading to poor quality of life for patients. Nanoparticle-based drug delivery has emerged as a promising medical technology and offers several advantages by enhancing the delivery of drug payloads to their target sites, reducing systemic toxicity, and facilitating patient compliance over free drug administration. In addition, nanotechnology-based imaging approaches provide exciting diagnostic methods for monitoring molecular and cellular changes in transplanted organs, visualizing immune responses, and assessing the severity of rejection. These noninvasive technologies are expected to help enhance the posttransplantation patient survival through real time and early diagnosis of disease progression. Here, we present a comprehensive review of nanotechnology-assisted strategies in various aspects of organ transplantation, including organ protection before transplantation, mitigation of ischemia-reperfusion injury, counteraction of immune rejection, early detection of organ dysfunction posttransplantation, and molecular imaging and diagnosis of immune rejection.

Recurrent rejections after liver transplantation for hepatocellular carcinoma with stem cell features in an adult patient

Patients with hepatoblastoma featuring carcinoma characteristics have better outcomes after liver transplantation, than after chemotherapy and resection. Possibly this should be extrapolated to aggressive subtypes of hepatocellular carcinomas in non-cirrhotic livers, where early liver transplantation might also be indicated. However, the risks associated with liver transplantation and immunosuppressive treatment after liver transplantation are once again demonstrated by this case of a 32-year-old women with a negative personal and familial history of liver diseases. She underwent transplantation (DBD) for a hepatocellular carcinoma with stem cell features (HCC-HS; an aggressive 'hepatoblast subtype' of hepatocellular carcinoma) after chemotherapeutical downstaging techniques failed to sufficiently downstage the tumor. Despite being on conventional immunosuppressive regimens (tacrolimus and mycophenolate mofetil with initial corticosteroids tapered), this patient still developed two severe rejection episodes, one of which necessitated retransplantation (DCD). Both episodes were preceded by alterations in tacrolimus trough levels, either intentionally, when tacrolimus was reduced within a nephroprotective regimen, or unintentionally, when rifampicin, a CYP3A4 inducer, significantly lowered the trough levels. Together, these episodes stress the importance of therapeutic drug monitoring of tacrolimus. Furthermore, the patient experienced an everolimus-linked drug-induced thrombotic microangiopathy, underwent multiple ERCPs for an anastomotic stricture and only one and a half year after the first liver transplantation she already suffers from long-term immunosuppressive-related side effects such as impaired glucose tolerance, hypertension and a potential cardiomyopathy. At present, she is still alive and experienced no recurrence of her primary tumor. Her case underscores the significant challenges in post-liver transplantation care.

Algorithmic Approach to Deranged Liver Functions After Transplantation

Liver transplant (LT) recipients require close follow-up with regular monitoring of the liver function tests (LFTs). Evaluation of deranged LFT should be individualized depending upon the time since LT, peri-operative events, clinical course, and any complications. These derangements can range from mild and asymptomatic to severe and symptomatic elevations requiring expedited personalized assessment and management. Pattern of LFT derangement (hepatocellular, cholestatic, or mixed), donor-recipient risk factors, timing after LT (post-operative, 1-12 months, and >12 months since LT) along with clinical context and symptomatology are important considerations before proceeding with the initial evaluation. Compliance to immunosuppression and drug interactions should be ascertained along with local epidemiology of infections. Essential initial evaluation must include an ultrasound abdomen with Doppler to rule out any structural causes such as biliary or vascular complications apart from focussed laboratory evaluation. Early allograft dysfunction, ischemia reperfusion injury, small-for-size syndrome, biliary leaks, hepatic artery, and portal vein thrombosis are usual culprits in the early post-operative period whereas viral hepatitis (acute or reactivation), opportunistic infections, and recurrence of the primary disease are more frequent in the later period. Graft rejection, biliary strictures, sepsis, and drug induced liver injury remain possible etiologies at all times points after LT. Initial evaluation algorithm must be customized based on history, clinical examination, risk factors, and pattern and severity of deranged LFT. Allograft rejection is a diagnosis of exclusion and requires liver biopsy to confirm and assess severity. Empirical treatment of rejection sans liver biopsy is discouraged.

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.

Immunology demystified: A guide for transplant hepatologists

Liver transplantation has become standard practice for treating end-stage liver disease. The success of the procedure relies on effective immunosuppressive medications to control the host's immune response. Despite the liver's inherent capacity to foster tolerance, the early post-transplant period is marked by significant immune reactivity. To ensure favorable outcomes, it is imperative to identify and manage various rejection types, encompassing T-cell-mediated, antibody-mediated, and chronic rejection. However, the approach to prescribing immunosuppressants relies heavily on clinical judgment rather than evidence-based criteria. Given that the majority of patients will require lifelong immuno suppression as the mechanisms underlying operational tolerance are still being investigated, healthcare providers must possess an understanding of immune responses, rejection mechanisms, and the pathways targeted by immunosuppressive drugs. This knowledge enables customization of treatments and improved patient care, even though a consensus on an optimal immunosuppressive regimen remains elusive.

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.

Computed Tomography and Magnetic Resonance Imaging Signs of Chronic Liver Rejection: A Case-Control Study

OBJECTIVE

In liver transplantation, chronic rejection is still poorly studied. This study aimed to investigate the role of imaging in its recognition.

METHODS

This study is a retrospective observational case-control series. Patients with histologic diagnosis of chronic liver transplant rejection were selected; the last imaging examination (computed tomography or magnetic resonance imaging) before the diagnosis was evaluated. At least 3 controls were selected for each case; radiological signs indicative of altered liver function were analyzed. χ 2 Test with Yates correction was used to compare the rates of radiologic signs in the case and control groups, also considering whether patients suffered chronic rejection within or after 12 months. Statistical significance was set at P < 0.050.

RESULTS

A total of 118 patients were included in the study (27 in the case group and 91 in the control group). Periportal edema was appreciable in 19 of 27 cases (70%) and in 6 of 91 controls (4%) ( P < 0.001); ascites and hepatomegaly were present in 14 of 27 cases (52%) and 12 of 27 cases (44%), respectively, and in 1 of 91 controls (1%) ( P < 0.001); splenomegaly was present in 13 of 27 cases (48%) and in 8 of 91 controls (10%) ( P < 0.001); and biliary tract dilatation was present in 13 of 27 cases (48%) and in 11 of 91 patients controls (5%) ( P < 0.001). In the controls, periportal edema was significantly less frequent beyond 12 months after transplant (1% vs 11%; P = 0.020); the other signs after 12 months were not significant.

CONCLUSIONS

The identification of periportal edema, biliary dilatation, ascites, and hepatosplenomegaly can serve as potential warning signs of ongoing chronic liver rejection. It is especially important to investigate periportal edema if it is present 1 year or more after orthotopic liver transplantation.

Evaluation of Humoral Response following SARS-CoV-2 mRNA-Based Vaccination in Liver Transplant Recipients Receiving Tailored Immunosuppressive Therapy

Background: The role of tailored immunosuppression (IS) in the development of the humoral response (HR) to SARS-CoV-2 mRNA-based vaccination in liver transplant (LT) recipients is unknown. Methods: This is a single-centre prospective study of patients who underwent LT between January 2015 and December 2021 and who have received three doses of mRNA-based SARS-CoV-2 vaccination. Patients undergoing Tacrolimus-based immunosuppression (TAC-IS) were compared with those undergoing Everolimus-based immunosuppression (EVR-IS). Patients receiving the TAC-EVR combination were divided into two groups based on trough TAC concentrations, i.e., above or below 5 ng/mL. HR (analysed with ECLIA) was assessed at 30 to 135 days after vaccination. The primary outcome was the presence of a positive antibody titre (≥0.8 U/mL). Secondary outcomes were the presence of a highly protective antibody titre (≥142 U/mL), median antibody titre, and incidence of COVID-19. Results: Sixty-one participants were included. Twenty-four (40%) were receiving TAC-IS and thirty-seven (60%) were receiving EVR-IS. At the median follow-up of 116 (range: 89-154) days, there were no significant differences in positive antibody titre (95.8% vs. 94.6%; p = 0.8269), highly-protective antibody titre (83.3% vs. 81.1%; p = 0.8231), median antibody titre (2410 [IQ range 350-2500] vs. 1670 [IQ range 380-2500]; p = 0.9450), and COVID-19 incidence (0% vs. 5.4%; p = 0.5148). High serum creatinine and low estimated glomerular filtration rate were risk factors for a weak or absent HR. Conclusions: Three doses of mRNA-based SARS-CoV-2 vaccination yielded a highly protective HR in LT recipients. The use of TAC or EVR-based IS does not appear to influence HR or antibody titre, while renal disease is a risk factor for a weak or null HR.

Obliterative foam-cell arteriopathy. A unifying concept embracing several entities previously described as radiation, decidual, transplant, and intratumoral-associated arteriopathy

This review article aimed to postulate the existence of a specific arterial injury having as its histological hallmark a collection of macrophages loaded with lipids in the intima of small-sized and medium-sized arteries causing narrowing or complete obstruction. The proposal is made that a series of previously described entities, such as ionizing radiation arteriopathy, acute atherosis (foam-cell decidual arteriopathy), transplant chronic arteriopathy of solid organ allografts, and intratumoral-associated foam-cell arteriopathy constitute different manifestations of the same basic morphological process identified as obliterative foam-cell arteriopathy (OFCA). OFCA is a local (single-organ) lesion in the aforementioned diverse processes with variable etiopathogenesis but converges in a single morphological marker. This arteriopathy is essentially an intimal disease. The processes in which the OFCA appears are known under a variety of names partly dependent on the location of the lesion. The basic unifying mechanism of the different entities is endothelial activation and dysfunction (local arterial endotheliopathy), preferably in small-sized or medium-sized arteries (100 to 500 μm in external diameter).

Non-Invasive Measurement of Hepatic Fibrosis by Transient Elastography: A Narrative Review

Transient elastography by FibroScan® (Echosens, Paris, France) is a non-invasive method that can provide a reliable measurement of liver fibrosis through the evaluation of liver stiffness. Despite its limitations and risks, liver biopsy has thus far been the only procedure able to provide data to quantify fibrosis. Scientific evidence and clinical practice have made it possible to use FibroScan® in the diagnostic work-up of several liver diseases to monitor patients' long-term treatment response and for complication prevention. For these reasons, this procedure is widely used in clinical practice and is still being investigated for further applications. The aim of this narrative review is to provide a comprehensive overview of the main applications of transient elastography in the current clinical practice.

Liver transplantation immunology: Immunosuppression, rejection, and immunomodulation

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

Monitoring of Serological, Cellular and Genomic Biomarkers in Transplantation, Computational Prediction Models and Role of Cell-Free DNA in Transplant Outcome

The process and evolution of an organ transplant procedure has evolved in terms of the prevention of immunological rejection with the improvement in the determination of immune response genes. These techniques include considering more important genes, more polymorphism detection, more refinement of the response motifs, as well as the analysis of epitopes and eplets, its capacity to fix complement, the PIRCHE algorithm and post-transplant monitoring with promising new biomarkers that surpass the classic serum markers such as creatine and other similar parameters of renal function. Among these new biomarkers, we analyze new serological, urine, cellular, genomic and transcriptomic biomarkers and computational prediction, with particular attention to the analysis of donor free circulating DNA as an optimal marker of kidney damage.

Current Status of Biomarkers and Molecular Diagnostic Tools for Rejection in Liver Transplantation: Light at the End of the Tunnel?

Strategies to minimize immune-suppressive medications after liver transplantation are limited by allograft rejection. Biopsy of liver is the current standard of care in diagnosing rejection. However, it adds to physical and economic burden to the patient and has diagnostic limitations. In this review, we aim to highlight the different biomarkers to predict and diagnose acute rejection. We also aim to explore recent advances in molecular diagnostics to improve the diagnostic yield of liver biopsies.

Killer Cell Immunoglobulin-like Receptors (KIR) and Human Leucocyte Antigen C (HLA-C) Increase the Risk of Long-Term Chronic Liver Graft Rejection

Chronic liver rejection (CR) represents a complex clinical situation because many patients do not respond to increased immunosuppression. Killer cell immunoglobulin-like receptors/Class I Human Leukocyte Antigens (KIR/HLA-I) interactions allow for predicting Natural Killer (NK) cell alloreactivity and influence the acute rejection of liver allograft. However, its meaning in CR liver graft remains controversial. KIR and HLA genotypes were studied in 513 liver transplants using sequence-specific oligonucleotides (PCR-SSO) methods. KIRs, human leucocyte antigen C (HLA-C) genotypes, KIR gene mismatches, and the KIR/HLA-ligand were analyzed and compared in overall transplants with CR (n = 35) and no-chronic rejection (NCR = 478). Activating KIR (aKIR) genes in recipients (rKIR2DS2⁺ and rKIR2DS3⁺) increased CR compared with NCR groups (p = 0.013 and p = 0.038). The inhibitory KIR (iKIR) genes in recipients rKIR2DL2⁺ significantly increased the CR rate compared with their absence (9.1% vs. 3.7%, p = 0.020). KIR2DL3 significantly increases CR (13.1% vs. 5.2%; p = 0.008). There was no influence on NCR. CR was observed in HLA-I mismatches (MM). The absence of donor (d) HLA-C2 ligand (dC2⁻) ligand increases CR concerning their presence (13.1% vs. 5.6%; p = 0.018). A significant increase of CR was observed in rKIR2DL3⁺/dC1⁻ (p = 0.015), rKIR2DS4/dC1⁻ (p = 0.014) and rKIR2DL3⁺/rKIR2DS4⁺/dC1⁻ (p = 0.006). Long-term patient survival was significantly lower in rKIR2DS1⁺rKIR2DS4⁺/dC1⁻ at 5–10 years post-transplant. This study shows the influence of rKIR/dHLA-C combinations and aKIR gene-gene mismatches in increasing CR and KIR2DS1⁺/C1-ligands and the influence of KIR2DS4⁺/C1-ligands in long-term graft survival.

The New Challenge in Pediatric Liver Transplantation: Chronic Antibody-Mediated Rejection

Antibody-mediated rejection (AMR) of liver allograft transplantation was considered as anecdotal for many decades. However recently, AMR has gained clinical awareness as a potential cause of chronic liver injury, leading to liver allograft fibrosis and eventual graft failure. (1) Methods: Literature on chronic AMR (cAMR) in pediatric post-liver transplant patients was reviewed for epidemiologic data, physiopathology, diagnosis, and treatment approaches. (2) Results: Accurate incidence of cAMR in pediatric liver transplantation remains unknown. Diagnostic criteria of cAMR were suggested by the Banff Working Group in 2016 and are based on standardized histopathological findings, C4d staining pattern, associated with the presence of donor-specific antibodies (DSA). Physio-pathological mechanisms are not clear for the technically difficult-to-obtain animal models reproducing cAMR. Treatment protocols are not established, being limited to case reports and case series, based on experience in ABO incompatible transplantation and kidney transplantation. Immunosuppression compliance with adequate dose adjustment may prevent cAMR. Conversion of Cyclosporine to Tacrolimus may improve pathological findings if treated in early phase. The association of steroids, Mycophenolate Mofetil (MMF) and mTOR inhibitors have shown some synergistic effects. Second-line treatments such as intravenous immunoglobulin (IVIG) and plasma exchange may decrease antibody titers based on ABO incompatible transplant protocols. The use of anti-CD20 (Rituximab) and proteasome inhibitors (Bortezomib) is controversial due to the lack of qualified studies. Therefore, multicenter randomized trials are needed to establish the best therapeutic strategy. In refractory cases, re-transplantation is the only treatment for allograft failure. (3) Conclusions: This literature review collects recent clinical, histopathological, and therapeutical advances of cAMR in liver allograft transplantation of pediatric patients. There are many physio-pathological aspects of cAMR to be clarified. Further efforts with multicenter prospective protocols to manage patients with cAMR are needed to improve its outcome.