A Single-Cell Landscape of Human Liver Transplantation Reveals a Pathogenic Immune Niche Associated with Early Allograft Dysfunction

Liver transplantation(LT)is the standard therapy for individuals afflicted with end-stage liver disease.Despite notable advancements in LT technology,the incidence of early allograft dysfunction(EAD)remains a critical concern,exacerbating the current organ shortage and detrimentally affecting the prognosis of recipients.Unfortunately,the perplexing hepatic heterogeneity has impeded characterization of the cellular traits and molecular events that contribute to EAD.Herein,we constructed a pioneering single-cell transcriptomic landscape of human transplanted livers derived from non-EAD and EAD patients,with 12 liver samples collected from 7 donors during the cold perfusion and portal reperfusion stages.Comparison of the 75231 cells of non-EAD and EAD patients revealed an EAD-associated immune niche comprising mucosal-associated invariant T cells,granzyme B^(+)(GZMB^(+))granzyme K^(+)(GZMK^(+))natural killer cells,and S100 calcium binding protein A12^(+)(S100A12^(+))neutrophils.Moreover,we verified this immune niche and its association with EAD occurrence in two independent cohorts.Our findings elucidate the cellular characteristics of transplanted livers and the EAD-associated pathogenic immune niche at the single-cell level,thus,offering valuable insights into EAD onset.

Evaluation of the updated definition of early allograft dysfunction in donation after brain death and donation after cardiac death liver allografts

BACKGROUND:An updated definition of early allograft dysfunction(EAD) was recently validated in a multicenter study of 300 deceased donor liver transplant recipients.This analysis did not differentiate between donation after brain death(DBD) and donation after cardiac death(DCD) allograft recipients.METHODS:We reviewed our prospectively entered database for all DBD(n=377) and DCD(n=38) liver transplantations between January 1,2006 and October 30,2011.The incidence of EAD as well as its ability to predict graft failure and survival was compared between DBD and DCD groups.RESULTS:EAD was a valid predictor of both graft and patient survival at six months in DBD allograft recipients,but in DCD allograft recipients there was no significant difference in the rate of graft failure in those with EAD(11.5%) compared with those without EAD(16.7%)(P=0.664) or in the rate of death in recipients with EAD(3.8%) compared with those without EAD(8.3%)(P=0.565).The graft failure rate in the first 6 months in those with international normalized ratio ≥1.6 on day 7 who received a DCD allograft was 37.5% compared with 6.7% for those with international normalized ratio <1.6 on day 7(P=0.022).CONCLUSIONS:The recently validated definition of EAD is a valid predictor of patient and graft survival in recipients of DBD allografts.On initial assessment,it does not appear to be a useful predictor of patient and graft survival in recipients of DCD allografts,however a study with a larger sample size of DCD allografts is needed to confirm these findings.The high ALT/AST levels in most recipients of DCD livers as well as the predisposition to biliary complications and early cholestasis make these parameters as poor predictors of graft failure.An alternative definition of EAD that gives greater weight to the INR on day 7 may be more relevant in this population.

Zinc finger protein A20 protects rats against chronic liver allograft dysfunction

AIM： To investigate the effect of zinc finger protein A20 on chronic liver allograft dysfunction in rats. METHODS： AIIogeneic liver transplantation from DA rats to Lewis rats was performed. Chronic liver allograft dysfunction was induced in the rats by administering low-dose tacrolimus at postoperative day （POD） 5. Hepatic overexpression of A20 was achieved by recom- binant adenovirus （rAd.）-mediated gene transfer ad- ministered intravenously every 10 d starting from POD 10. The recipient rats were injected with physiologi- cal saline, rAdEasy-A20 （1 × 109 pfu/30 g weight） or rAdEasy （1 × 109 pfu/30 g weight） every 10 d through the tail vein for 3 mo starting from POD 10. Liver tissue samples were harvested on POD 30 and POD 60. RESULTS： Liver-transplanted rats treated with only tacrolimus showed chronic allograft dysfunction with severe hepatic fibrosis. A20 overexpression ameliorated the effects on liver function, attenuated liver allograft fibrosis and prolonged the survival of the recipient rats. Treatment with A20 suppressed hepatic protein pro- duction of tumor growth factor （TGF）-β1, interleukin- 113, caspase-8, CD40, CD40L, intercellular adhesion molecule-i, vascular cell adhesion molecule-1 and E-selectin. A20 treatment suppressed liver cell apopto- sis and inhibited nuclear factor-KB activation of Kupffer cells （KCs）, liver sinusoidal endothelial cells （LSECs） and hepatic stellate cells （HSCs）, and it subsequently decreased cytokine mRNA expression in KCs and LSECs and reduced the production of TGF-β1 in HSCs. CONCLUSION： A20 might prevent chronic liver allogra- ft dysfunction by re-establishing functional homeostasis of KCs, LSECs and HSCs.

Role of the postoperative cholesterol in early allograft dysfunction and survival after living donor liver transplantation

BACKGROUND:Many studies have confirmed that serum total cholesterol(sTC) concentrations were associated with underlying liver damage and the synthesis capacity of liver.However, the role of postoperative sTC level on evaluating graft function and predicting survival of recipients who underwent liver transplantation has not been discussed.METHODS:Clinical data of 231 living donor liver transplantation recipients from May 2003 to January 2015 were retrospectively collected. Patients were stratified into the low sTC group(sTC <1.42 mmol/L, 57 recipients) and high sTC group(sTC ≥1.42 mmol/L, 174 recipients) according the sTC level on postoperative day 3 based on receiver-operating characteristic curve analysis. The clinical characteristics and postoperative short-and long-term outcomes were compared between the two groups.RESULTS:Recipients with sTC <1.42 mmol/L experienced more severe preoperative disease conditions, a higher incidence of postoperative early allograft dysfunction(38.6% vs 10.3%, P<0.001), 90-day mortality(28.1% vs 10.9%, P=0.002)and severe complications(29.8% vs 17.2%, P=0.041) compared to recipients with sTC ≥1.42 mmol/L. The multivariate analysis demonstrated that sT C <1.42 mmol/L had a 4.08-fold(95% CI:1.83-9.11, P=0.001) and 2.72-fold(95% CI:1.23-6.00,P=0.013) greater risk of developing allograft dysfunction and 90-day mortality, and patients with sTC <1.42 mmol/L had poorer overall recipient and graft survival rates at 1-, 3-, and 5-year than those with sTC ≥1.42 mmol/L(67%, 61% and 61% vs 83%, 71% and 69%, P=0.025; 65%, 59% and 59% vs 81%,68% and 66%, P=0.026, respectively). Cox multivariate anal-ysis showed that sTC <1.42 mmol/L was an independent predicting factor for total recipient survival(HR=2.043; 95% CI:1.173-3.560; P=0.012) and graft survival(HR=1.905; 95% CI:1.115-3.255; P=0.018).CONCLUSIONS:sTC <1.42 mmol/L on postoperative day 3 was an independent risk factor of postoperative early allograft dysfunction, 90-day mortality, recipient and graft survival, which can be used as a marker for predicting postoperative short-and long-term outcomes.

Chronic lung allograft dysfunction post-lung transplantation:The era of bronchiolitis obliterans syndrome and restrictive allograft syndrome

Chronic lung allograft dysfunction(CLAD)following lung transplantation limits long-term survival considerably.The main reason for this is a lack of knowledge regarding the pathological condition and the establishment of treatment.The consensus statement from the International Society for Heart and Lung Transplantation on CLAD in 2019 classified CLAD into two main phenotypes:Bronchiolitis obliterans syndrome and restrictive allograft syndrome.Along with this clear classification,further exploration of the mechanisms and the development of appropriate prevention and treatment strategies for each phenotype are desired.In this review,we summarize the new definition of CLAD and update and summarize the existing knowledge on the underlying mechanisms of bronchiolitis obliterans syndrome and restrictive allograft syndrome,which have been elucidated from clinicopathological observations and animal experiments worldwide.

Diagnosis and management of late hepatic allograft dysfunction

Late hepatic allograft dysfunction (LHAD) is common after liver transplantation (LT) and can cause graft failure,retransplantation,or even death.A variety of etiologies including rejection,vascular complications,bile duct complications,recurrent diseases,infections,de novo diseases,neoplasms and drug toxicity can result in LHAD.The recurrent diseases have the potential to become the most serious problems facing LT in the future.It is difficult to differentiate late acute rejection from recurrent viral or autoimmune hepatitis.Accurate diagnosis of the cause of LHAD has therapeutic importance.

Risk scores for allograft failure: Are they still useful in liver recipients from donation after circulatory death?

BACKGROUND Liver grafts from donation after circulatory death(DCD)are associated with a higher risk of early graft dysfunction,determined by the warm ischemia and cold ischemia times.It is essential to have precise criteria to identify this complication in order to guide therapeutic strategies.AIM To validate different graft and recipient survival scores in patients undergoing liver transplantation(LT)with DCD grafts.METHODS A retrospective and observational unicentric study was conducted on 65 LT patients with grafts obtained from controlled DCD donors from November 2013 to November 2022.The United Kingdom(UK)risk score,early allograft dysfunction(EAD)Olthoff score,and model for early allograft function(MEAF)score were used to evaluate the risk of graft and recipient survival post-transplant.For survival analysis purposes,we used the Kaplan-Meier method,and the differences between subgroups were compared using the log-rank(Mantel-Cox)test.RESULTS Sixty-five patients were included in the study.The UK risk score did not demonstrate predictive capacity for recipient or graft survival.However,in donors aged over 70 years old(18.4%),it significantly predicted graft survival(P<0.05).According to Kaplan-Meier survival curves,graft survival rates at 6 months,2 years,and 5 years in the futility group dramatically decreased to 50%compared to the other groups(log-rank 8.806,P<0.05).The EAD Olthoff and MEAF scores did not demonstrate predictive capacity for recipient or graft survival.Based on Kaplan-Meier survival curves,patients with a MEAF score≥7 had a lower graft survival rate at 6 months,2 years,and 5 years compared to patients with a lower MEAF score(log-rank 4.667,P<0.05).CONCLUSION In our series,both UK DCD risk score and MEAF score showed predictive capability for graft survival.

Severity of early allograft dysfunction following donation after circulatory death liver transplantation:a multicentre study

Background:Early allograft dysfunction(EAD)is associated with decreased graft and patient survival rates.This study aimed to identify the severity of EAD and develop a predictive model for EAD after donation after circulatory death(DCD)liver transplantation(LT).Furthermore,the influence of operative time on EAD incidence was also evaluated.Methods:In this retrospective,multicentre cohort study,nomograms were established based on a single-centre training cohort(n=321)and validated in a 3-center validation cohort(n=501).Results:The incidence rate of EAD was 46.4%(149/321)in the training cohort and 40.5%(203/501)in the validation cohort.Of the 149 EAD patients in the training cohort,77 patients with either elevated alanine aminotransferase(ALT)or aspartate aminotransferase(AST)were classified as having EAD type A,and the rest of the EAD patients were classified as having EAD type B.Recipients with EAD type B had lower graft and patient survival rates than recipients with EAD type A(P=0.043 and 0.044,respectively).We further developed a nomogram to predict EAD(graft weight,cold ischemia time,donor age,model for end-stage liver disease(MELD)score)and another nomogram to predict EAD type B(graft weight,cold ischemia time,MELD score).The nomograms for the prediction of EAD and EAD type B had good discrimination[concordance index(C-index)=0.712(0.666-0.758),0.707(0.641-0.773)]and calibration[Hosmer-Lemeshow(HL)P=0.384,P=0.425]in the validation cohort.An increased operative time(>6 h)was associated with increased EAD and EAD type B incidence in the high-risk group(P=0.005,P=0.020,respectively).Conclusions:EAD type B was associated with decreased graft and patient survival rates.The novel nomograms effectively predicted the incidence of EAD and EAD type B in DCD LT patients.

Association of donor hepatectomy time with liver transplantation outcomes: A multicenter retrospective study

BACKGROUND Prolonged donor hepatectomy time may be implicated in early and late complications of liver transplantation.AIM To evaluate the impact of donor hepatectomy time on outcomes of liver transplant recipients,mainly early allograft dysfunction.METHODS This multicenter retrospective study included brain-dead donors and adult liver graft recipients.Donor-recipient matching was obtained through a crossover list.Clinical and laboratory data were recorded for both donors and recipients.Donor hepatectomy,cold ischemia,and warm ischemia times were recorded.Primary outcome was early allograft dysfunction.Secondary outcomes included need for retransplantation,length of intensive care unit and hospital stay,and patient and graft survival at 12 months.RESULTS From January 2019 to December 2021,a total of 243 patients underwent a liver transplant from a brain-dead donor.Of these,57(25%)developed early allograft dysfunction.The median donor hepatectomy time was 29(23–40)min.Patients with early allograft dysfunction had a median hepatectomy time of 25(22–38)min,whereas those without it had a median time of 30(24–40)min(P=0.126).CONCLUSION Donor hepatectomy time was not associated with early allograft dysfunction,graft survival,or patient survival following liver transplantation.

Dysfunction of branded-chain amino acids catabolism in rat cardiac allograft

Objective Allograft vasculopathy ( AV) ,feature of chronic rejection,is a major serious long - term post - operation complication in organ transplantation. The accurate mechanisms for AV have not been definitively established,but extensive basic and clinical studies dem-

Portal vein arterialization in 25 liver transplant recipients:A Latin American single-center experience

BACKGROUND Portal vein arterialization(PVA)has been used in liver transplantation(LT)to maximize oxygen delivery when arterial circulation is compromised or has been used as an alternative reperfusion technique for complex portal vein thrombosis(PVT).The effect of PVA on portal perfusion and primary graft dysfunction(PGD)has not been assessed.All patients receiving PVA and LT at the Fundacion Santa Fe de Bogota between 2011 and 2022 were analyzed.To account for the time-sensitive effects of graft perfusion,patients were classified into two groups:prereperfusion(pre-PVA),if the arterioportal anastomosis was performed before graft revascularization,and postreperfusion(post-PVA),if PVA was performed afterward.The pre-PVA rationale contemplated poor portal hemodynamics,severe vascular steal,or PVT.Post-PVA was considered if graft hypoperfusion became evident.Conservative interventions were attempted before PVA.

Role of intelligent/interactive qualitative and quantitative analysisthree-dimensional estimated model in donor-recipient size mismatch following deceased donor liver transplantation

BACKGROUND Donor-recipient size mismatch(DRSM)is considered a crucial factor for poor outcomes in liver transplantation(LT)because of complications,such as massive intraoperative blood loss(IBL)and early allograft dysfunction(EAD).Liver volumetry is performed routinely in living donor LT,but rarely in deceased donor LT(DDLT),which amplifies the adverse effects of DRSM in DDLT.Due to the various shortcomings of traditional manual liver volumetry and formula methods,a feasible model based on intelligent/interactive qualitative and quantitative analysis-three-dimensional(IQQA-3D)for estimating the degree of DRSM is needed.AIM To identify benefits of IQQA-3D liver volumetry in DDLT and establish an estimation model to guide perioperative management.METHODS We retrospectively determined the accuracy of IQQA-3D liver volumetry for standard total liver volume(TLV)(sTLV)and established an estimation TLV(eTLV)index(eTLVi)model.Receiver operating characteristic(ROC)curves were drawn to detect the optimal cut-off values for predicting massive IBL and EAD in DDLT using donor sTLV to recipient sTLV(called sTLVi).The factors influencing the occurrence of massive IBL and EAD were explored through logistic regression analysis.Finally,the eTLVi model was compared with the sTLVi model through the ROC curve for verification.RESULTS A total of 133 patients were included in the analysis.The Changzheng formula was accurate for calculating donor sTLV(P=0.083)but not for recipient sTLV(P=0.036).Recipient eTLV calculated using IQQA-3D highly matched with recipient sTLV(P=0.221).Alcoholic liver disease,gastrointestinal bleeding,and sTLVi>1.24 were independent risk factors for massive IBL,and drug-induced liver failure was an independent protective factor for massive IBL.Male donor-female recipient combination,model for end-stage liver disease score,sTLVi≤0.85,and sTLVi≥1.32 were independent risk factors for EAD,and viral hepatitis was an independent protective factor for EAD.The overall survival of patients in the 0.85<sTLVi<1.32 group was better compared to the sTLVi≤0.85 group and sTLVi≥1.32 group(P<0.001).There was no statistically significant difference in the area under the curve of the sTLVi model and IQQA-3D eTLVi model in the detection of massive IBL and EAD(all P>0.05).CONCLUSION IQQA-3D eTLVi model has high accuracy in predicting massive IBL and EAD in DDLT.We should follow the guidance of the IQQA-3D eTLVi model in perioperative management.

Predictive factors of short term outcome after liver transplantation: A review

Liver transplantation represents a fundamental therapeutic solution to end-stage liver disease. The need for liver allografts has extended the set of criteria for organ acceptability, increasing the risk of adverse outcomes. Little is known about the early postoperative parameters that can be used as valid predictive indices for early graft function, retransplantation or surgical reintervention, secondary complications, long intensive care unit stay or death. In this review, we present state-of-the-art knowledge regarding the early post-transplantation tests and scores that can be applied during the first postoperative week to predict liver allograft function and patient outcome, thereby guiding the therapeutic and surgical decisions of the medical staff. Post-transplant clinical and biochemical assessment of patients through laboratory tests (platelet count, transaminase and bilirubin levels, INR, factor V, lactates, and Insulin Growth Factor 1) and scores (model for end-stage liver disease, acute physiology and chronic health evaluation, sequential organ failure assessment and model of early allograft function) have been reported to have good performance, but they only allow late evaluation of patient status and graft function, requiring days to be quantified. The indocyanine green plasma disappearance rate has long been used as a liver function assessment technique and has produced interesting, although not univocal, results when performed between the 1th and the 5th day after transplantation. The liver maximal function capacity test is a promising method of metabolic liver activity assessment, but its use is limited by economic cost and extrahepatic factors. To date, a consensual definition of early allograft dysfunction and the integration and validation of the above-mentioned techniques, through the development of numerically consistent multicentric prospective randomised trials, are necessary. The medical and surgical management of transplanted patients could be greatly improved by using clinically reliable tools to predict early graft function.

Grade of donor liver microvesicular steatosis does not affect the postoperative outcome after liver transplantation

BACKGROUND:The potential effect of graft steatosis on the postoperative liver function is discussed controversially. The present study aimed to evaluate the effect of the donor liver microvesicular steatosis on the postoperative outcome after liver transplantation.METHODS:Ninety-four patients undergoing liver transplantation at the University Hospital Aachen were included in this study. The patient cohort was divided into three groups according to the grade of microvesicular steatosis(MiS):MiS <30%(n=27), MiS 30%-60%(n=41) and MiS >60%(n=26).The outcomes after liver transplantation were evaluated, including the 30-day and 1-year patient and graft survival rates and the incidences of early allograft dysfunction(EAD) and primary nonfunction(PNF). RESULTS:The incidences of EAD and PNF did not differ significantly between the groups. We observed 5 cases of PNF,one occurred in the MiS <30% group and 4 in the MiS 30%-60% group. The 30-day and 1-year graft survivals did not differ significantly between groups. The 30-day patient survival rates were 100% in all groups. The 1-year patient survival rates were 94.4% in the MiS <30% group, 87.9% in the MiS 30%-60% group and 90.9% in the MiS >60% group.CONCLUSION:Microvesicular steatosis of donor livers has no negative effect on the postoperative outcome after liver transplantation.

Links between donor macrosteatosis,interleukin-33 and complement after liver transplantation

BACKGROUND As prevalence of nonalcoholic fatty liver disease increases in the population,livers with steatosis will continue to infiltrate the donor pool.Safe utilization of these extended criteria grafts is paramount given the increased risk associated with their use in transplantation.Prognostic factors that can predict liver dysfunction immediately after transplantation with macrosteatotic grafts are lacking.AIM To understand the relationship between interleukin-33(IL-33)and complement in recipients immediately following liver reperfusion as a marker of liver dysfunction.METHODS Cohort consisted of patients who received a liver transplant from September 2016–September 2019 at our institution.Clinical variables were retrospectively extracted from the electronic medical record.Back-table donor biopsies were obtained with donor steatosis percentage retrospectively determined by a boardcertified pathologist.Blood samples were available immediately following liver transplantation.Quantification of plasma IL-33 and complement proteins,C3a and C5a,were determined by enzyme-linked immunosorbent assay.For mRNA expression,RNA was extracted from donor biopsies and used against a 780 gene panel.RESULTS Cohort consisted of 99 donor and recipients.Donor median age was 45 years and 55%male.Recipients had a median age of 59 years with 62%male.The main etiologies were alcoholic hepatitis,nonalcoholic steatohepatitis,and hepatocellular carcinoma.Median MELD-Na at transplant was 21.Donors were grouped based on moderate macrosteatosis(≥30%).Recipients implanted with moderate macrosteatotic grafts had significantly higher peak alanine aminotransferase/aspartate aminotransferase(P<0.001 and P<0.004),and increased incidence of early allograft dysfunction(60%compared to 18%).Circulating IL-33 levels were significantly elevated in recipients of≥30%macrosteatotic grafts(P<0.05).Recipients with detectable levels of circulating IL-33 immediately following reperfusion had significantly higher alanine aminotransferase/aspartate aminotransferase(P<0.05 and P<0.01).Activated complement(C3a and C5a)were elevated in recipients implanted with moderate macrosteatotic grafts.RNA expression analysis of donor biopsies revealed moderate steatotic grafts upregulated genes inflammatory processes while downregulated hepatocyte-produced complement factors.CONCLUSION Circulating IL-33 and activated complement levels immediately following liver reperfusion in recipients of moderate macrosteatotic grafts may identify which patients are at risk of early allograft dysfunction.