BACKGROUND:Biliary tract obstruction (BTO) is a common complication after liver transplantation (LT) with high potential for morbidity. A comprehensive assessment of post-LT BTO, including patient and intraoperative characteristics predictive of postoperative obstruction, remains lacking. STUDY DESIGN:A prospectively collected database of all LTs performed at a single-center institution from 2014 to 2022 was analyzed. Diagnostic methods used in the evaluation of post-LT biliary obstruction were correlated with clinical data to identify high-yield diagnostic modalities. Subsequently, management strategies were analyzed to identify therapeutic approaches associated with optimal patient outcomes. RESULTS:Of 1,302 primary LT recipients, 137 (10.5%) experienced a posttransplant biliary obstruction event. The median time to post-LT BTO was 150 (68 to 275) days. One hundred nineteen obstruction events (86.9%) were attributable to anastomotic strictures, 11 (8.03%) to ischemic cholangiopathy, and 7 (5.1%) to T-tube or stent obstruction. On receiver operator characteristic analysis, gamma-glutamyl transferase demonstrated superior predictive power (area under the curve 0.80, 95% CI 0.69 to 0.91) in the detection of post-LT BTO as compared with total bilirubin (area under the curve 0.64, 95% CI 0.50 to 0.78) and alkaline phosphatase (area under the curve 0.57, 95% CI 0.41 to 0.72). History of coronary artery disease (odds ratio 4.26, p = 0.03) and postoperative hepatic artery thrombosis (odds ratio 6.01, p = 0.001) independently predicted stricture recurrence after an attempted stent-free trial. CONCLUSIONS:Obstruction of the biliary ductal system remains a common complication post-LT, with most cases occurring within 1 year of transplant. Gamma-glutamyl transferase demonstrates superior sensitivity and specificity in the detection of post-LT BTO and may be of significant diagnostic use. After an initial stent-free trial, several key risk factors may identify patients who merit additional monitoring for stricture recurrence.

The clinical significance of occult HCC identified on explant pathology in liver transplantation (LT) remains unclear. Among recipients of LT, discordance between pre-LT radiographic assessment of HCC and explant tumor burden is common. Data regarding the association of incidental HCC (no pre-LT radiographic diagnosis) and occult multifocal hepatocellular carcinoma (omHCC, pre-LT radiology underestimates a number of explant tumors) with outcomes are scarce. Post-LT recurrence and survival were compared among recipients of LT (n=919, 2002-2019) with incidental HCC (n=129), omHCC (n=349), and non-omHCC (n=437). Multivariable analysis identified independent predictors of omHCC in the subset of patients with kHCC. Compared to kHCC, incidental HCC had similar 5-year overall (OS) and recurrence-free survival (RFS), lower post-LT recurrence (6.9% vs. 16.2%, p =0.0019), but higher non-HCC-related mortality (38.4% vs. 23.7%, p =0.0042). Of 790 kHCC, 349 (44.1%) had omHCC, who demonstrated greater radiographic number of lesions ( p =0.049) and locoregional treatments ( p <0.001) but similar maximum and pre-LT alphafetoprotein compared to non-omHCC. Compared to kHCC without omHCC, patients with omHCC had inferior 5-year OS (60.4% vs. 70.9%, p =0.010) and RFS (56.8% vs. 69.7%, p <0.001), higher recurrence (23.8% vs. 9.2%, p <0.001), and similar non-HCC-related mortality. These observations remained true within patients who remained within Milan throughout preoperative imaging (5-y OS: 62.1% vs. 72.6%, p =0.027; RFS: 58.6% vs. 71.7%, p =0.010; recurrence: 21.7% vs. 7.6%, p <0.001). Multivariable predictors of omHCC tumor included a number of pre-LT locoregional therapies (OR 1.62 for 2 treatments, 95% CI 1.15-2.28, p =0.005; OR 1.98 for 3+ treatments, 1.36-2.88, p <0.001). In patients with kHCC prior to LT, the presence of omHCC is common and associated with inferior post-LT survival and higher recurrence rates. The development of improved radiographic and serum biomarkers that more accurately reflect explant tumor burden may improve patient selection and post-LT outcomes.

BACKGROUND:Ischemia-reperfusion injury (IRI) is a significant clinical concern in liver transplantation, with a key influence on short-term and long-term allograft and patient survival. Myeloid cells trigger and sustain tissue inflammation and damage associated with IRI, but the mechanisms regulating these activities are unknown. To address this, we investigated the molecular characteristics of intragraft myeloid cells present in biopsy-proven IRI- and IRI+ liver transplants. METHODS:RNA-sequencing was performed on 80 pre-reperfusion and post-reperfusion biopsies from 40 human recipients of liver transplantation (23 IRI+, 17 IRI-). We used transcriptional profiling and computational approaches to identify specific gene coexpression network modules correlated with functional subsets of MPO+, lysozyme+, and CD68+ myeloid cells quantified by immunohistochemistry on sequential sections from the same patient biopsies. RESULTS:A global molecular map showed gene signatures related to myeloid activation in all patients regardless of IRI status; however, myeloid cell subsets differed dramatically in their spatial morphology and associated gene signatures. IRI- recipients were found to have a natural corticosteroid production and response profile from pre-reperfusion to post-reperfusion, particularly among monocytes/macrophages. The pre-reperfusion signature of IRI+ recipients included acute inflammatory responses in neutrophils and increased translation of adaptive immune-related genes in monocytes/macrophages coupled with decreased glucocorticoid responses. Subsequent lymphocyte activation at post-reperfusion identified transcriptional programs associated with the transition to adaptive immunity found only among IRI+ recipients. CONCLUSIONS:Myeloid subset-specific genes and related signaling pathways provide targets for the development of therapeutic strategies aimed at limiting IRI in the clinical setting of liver transplantation.

HCC recurrence following liver transplantation (LT) is highly morbid and occurs despite strict patient selection criteria. Individualized prediction of post-LT HCC recurrence risk remains an important need. Clinico-radiologic and pathologic data of 4981 patients with HCC undergoing LT from the US Multicenter HCC Transplant Consortium (UMHTC) were analyzed to develop a REcurrent Liver cAncer Prediction ScorE (RELAPSE). Multivariable Fine and Gray competing risk analysis and machine learning algorithms (Random Survival Forest and Classification and Regression Tree models) identified variables to model HCC recurrence. RELAPSE was externally validated in 1160 HCC LT recipients from the European Hepatocellular Cancer Liver Transplant study group. Of 4981 UMHTC patients with HCC undergoing LT, 71.9% were within Milan criteria, 16.1% were initially beyond Milan criteria with 9.4% downstaged before LT, and 12.0% had incidental HCC on explant pathology. Overall and recurrence-free survival at 1, 3, and 5 years was 89.7%, 78.6%, and 69.8% and 86.8%, 74.9%, and 66.7%, respectively, with a 5-year incidence of HCC recurrence of 12.5% (median 16 months) and non-HCC mortality of 20.8%. A multivariable model identified maximum alpha-fetoprotein (HR = 1.35 per-log SD, 95% CI,1.22-1.50, p < 0.001), neutrophil-lymphocyte ratio (HR = 1.16 per-log SD, 95% CI,1.04-1.28, p < 0.006), pathologic maximum tumor diameter (HR = 1.53 per-log SD, 95% CI, 1.35-1.73, p < 0.001), microvascular (HR = 2.37, 95%-CI, 1.87-2.99, p < 0.001) and macrovascular (HR = 3.38, 95% CI, 2.41-4.75, p < 0.001) invasion, and tumor differentiation (moderate HR = 1.75, 95% CI, 1.29-2.37, p < 0.001; poor HR = 2.62, 95% CI, 1.54-3.32, p < 0.001) as independent variables predicting post-LT HCC recurrence (C-statistic = 0.78). Machine learning algorithms incorporating additional covariates improved prediction of recurrence (Random Survival Forest C-statistic = 0.81). Despite significant differences in European Hepatocellular Cancer Liver Transplant recipient radiologic, treatment, and pathologic characteristics, external validation of RELAPSE demonstrated consistent 2- and 5-year recurrence risk discrimination (AUCs 0.77 and 0.75, respectively). We developed and externally validated a RELAPSE score that accurately discriminates post-LT HCC recurrence risk and may allow for individualized post-LT surveillance, immunosuppression modification, and selection of high-risk patients for adjuvant therapies.

Objective:To examine liver retransplantation (ReLT) over 35 years at a single center. Background:Despite the durability of liver transplantation (LT), graft failure affects up to 40% of LT recipients. Methods:All adult ReLTs from 1984 to 2021 were analyzed. Comparisons were made between ReLTs in the pre versus post-model for end-stage liver disease (MELD) eras and between ReLTs and primary-LTs in the modern era. Multivariate analysis was used for prognostic modeling. Results:Six hundred fifty-four ReLTs were performed in 590 recipients. There were 372 pre-MELD ReLTs and 282 post-MELD ReLTs. Of the ReLT recipients, 89% had one previous LT, whereas 11% had & GE;2. Primary nonfunction was the most common indication in the pre-MELD era (33%) versus recurrent disease (24%) in the post-MELD era. Post-MELD ReLT recipients were older (53 vs 48, P = 0.001), had higher MELD scores (35 vs 31, P = 0.01), and had more comorbidities. However, post-MELD ReLT patients had superior 1, 5, and 10-year survival compared with pre-MELD ReLT (75%, 60%, and 43% vs 53%, 43%, and 35%, respectively, P < 0.001) and lower in-hospital mortality and rejection rates. Notably, in the post-MELD era, the MELD score did not affect survival. We identified the following risk factors for early mortality (& LE;12 months after ReLT): coronary artery disease, obesity, ventilatory support, older recipient age, and longer pre-ReLT hospital stay. Conclusions:This represents the largest single-center ReLT report to date. Despite the increased acuity and complexity of ReLT patients, post-MELD era outcomes have improved. With careful patient selection, these results support the efficacy and survival benefit of ReLT in an acuity-based allocation environment.

Background:Nonalcoholic steatohepatitis (NASH) is a severe immune-mediated stage of nonalcoholic fatty liver disease that is rapidly becoming the most common etiology requiring liver transplantation (LT), with Hispanics bearing a disproportionate burden. This study aimed to uncover the underlying immune mechanisms of the disparities experienced by Hispanic patients undergoing LT for NASH.Methods:We enrolled 164 LT recipients in our institutional review board-approved study, 33 of whom presented with NASH as the primary etiology of LT (20%), with 16 self-reported as Hispanic (48%). We investigated the histopathology of prereperfusion and postreperfusion biopsies, clinical liver function tests, longitudinal soluble cytokines via 38-plex Luminex, and immune cell phenotypes generated by prereperfusion and postreperfusion blood using 14-color flow cytometry and enzyme-linked immunosorbent assay.Results:Hispanic LT recipients transplanted for NASH were disproportionately female (81%) and disproportionately suffered poor outcomes in the first year posttransplant, including rejection (26%) and death (38%). Clinically, we observed increased pro-inflammatory and apoptotic histopathological features in biopsies, increased AST/international normalized ratio early posttransplantation, and a higher incidence of presensitization to mismatched HLA antigens expressed by the donor allograft. Experimental investigations revealed that blood from female Hispanic NASH patients showed significantly increased levels of leukocyte-attracting chemokines, innate-to-adaptive switching cytokines and growth factors, HMGB1 release, and TLR4/TLR8/TLR9/NOD1 activation, and produced a pro-inflammatory, pro-apoptotic macrophage phenotype with reduced CD14/CD68/CD66a/TIM-3 and increased CD16/CD11b/HLA-DR/CD80.Conclusions:A personalized approach to reducing immunological risk factors is urgently needed for this endotype in Hispanics with NASH requiring LT, particularly in females.

Objective: Despite the durability of liver transplantation (LT), graft failure affects up to 40% of LT recipients. We examined liver retransplantation (ReLT) over 35-years at a single center. Methods: All adult, ReLTs from 1984-2021 were analyzed. Comparisons were made between ReLTs in the pre- vs. post- model for end-stage liver disease (MELD) eras and between ReLTs and primary-LTs in the modern era. Multivariate analysis was used for prognostic modeling. Results: 654 ReLTs were performed in 590 recipients. There were 372 pre-MELD ReLTs and 282 post-MELD ReLTs. 89% of ReLT recipients had one previous LT, while 11% had ≥2. Primary non-function was the most common indication in the pre-MELD era (33%) vs. recurrent disease (24%) in the post-MELD era. Post-MELD ReLT recipients were older (53 vs. 48, P=0.001), had higher MELD scores (35 vs. 31, P=0.01), and more comorbidities. However, post-MELD ReLT patients had superior 1-, 5-, and 10-year survival compared to pre-MELD ReLT (75%, 60%, and 43% vs. 53%, 43%, and 35% respectively, P<0.001) and lower in-hospital mortality and rejection rates. Notably, in the post-MELD era, MELD score did not affect survival. We identified the following risk factors for early mortality (≤12 months): coronary artery disease, obesity, ventilatory support, older recipient age, longer pre-ReLT hospital stay. Conclusion: This represents the largest single center ReLT report to date. Despite increased acuity and complexity of ReLT patients, post-MELD era outcomes have improved. With careful patient selection, these results support the efficacy and survival benefit of ReLT in an acuity-based allocation environment.

Ischemia-reperfusion injury (IRI) during orthotopic liver transplantation (OLT) contributes to graft rejection and poor clinical outcomes. The disulfide form of high mobility group box 1 (diS-HMGB1), an intracellular protein released during OLT-IRI, induces pro-inflammatory macrophages. How diS-HMGB1 differentiates human monocytes into macrophages capable of activating adaptive immunity remains unknown. We investigated if diS-HMGB1 binds toll-like receptor (TLR) 4 and TLR9 to differentiate monocytes into pro-inflammatory macrophages that activate adaptive immunity and promote graft injury and dysfunction. Assessment of 106 clinical liver tissue and longitudinal blood samples revealed that OLT recipients were more likely to experience IRI and graft dysfunction with increased diSHMGB1 released during reperfusion. Increased diS-HMGB1 concentration also correlated with TLR4/TLR9 activation, polarization of monocytes into pro-inflammatory macrophages, and production of anti-donor antibodies. In vitro, healthy volunteer monocytes stimulated with purified diS-HMGB1 had increased inflammatory cytokine secretion, antigen presentation machinery, and reactive oxygen species production. TLR4 inhibition primarily impeded cytokine/chemokine and costimulatory molecule programs, whereas TLR9 inhibition decreased HLA-DR and reactive oxygen species production. diSHMGB1-polarized macrophages also showed increased capacity to present antigens and activate T memory cells. In murine OLT, diS-HMGB1 treatment potentiated ischemiareperfusion-mediated hepatocellular injury, accompanied by increased serum alanine transaminase levels. This translational study identifies the diS-HMGB1/TLR4/TLR9 axis as potential therapeutic targets in OLT-IRI recipients.

Immunosuppression withdrawal can be safely performed in select liver transplantation recipients, but the long-term outcomes and sustainability of tolerance have not been well studied. We completed a 10-year prospective, observational study of 18 pediatric liver transplantation recipients with operational tolerance to (1) assess the sustainability of tolerance over time, (2) compare the clinical characteristics of patients who maintained versus lost tolerance, (3) characterize liver histopathology findings in surveillance liver biopsies; and (4) describe immunologic markers in patients with tolerance. Comparator patients from two clinical phenotype groups termed "stable" and "nontolerant" patients were used as controls. Of the 18 patients with operational tolerance, the majority of patients were males (n = 14, 78%) who were transplanted for cholestatic liver disease (n = 12, 67%). Median age at transplantation was 1.9 (range, 0.6-8) years. Median time after transplantation that immunosuppression had been discontinued was 13.1 (range, 2.9-22.1) years. As many as 11 (61%) maintained tolerance for a median of 10.4 (range, 1.9-22.1) years, whereas 7 (39%) lost tolerance after a median of 3.2 (range, 1.5-18.6) years. Populations of T regulatory cells (%CD4+ CD25hi CD127lo ) were significantly higher in patients with tolerance (p = 0.02). Our results emphasize that spontaneous operational tolerance is a dynamic and nonpermanent state. It is therefore essential for patients who are clinically stable off immunosuppression to undergo regular follow-up and laboratory monitoring, as well as surveillance biopsies to rule out subclinical rejection.