Decreased chronic cellular and antibody-mediated injury in the kidney following simultaneous liver-kidney transplantation

Novel indications for referral and care for simultaneous liver kidney transplant recipients

PURPOSE OF REVIEW

Kidney dysfunction is challenging in liver transplant candidates to determine whether it is reversible or not. This review focuses on the pertinent data on how to best approach liver transplant candidates with kidney dysfunction in the current era after implementing the simultaneous liver kidney (SLK) allocation policy and safety net.

RECENT FINDINGS

The implementation of the SLK policy inverted the steady rise in SLK transplants and improved the utilization of high-quality kidneys. Access to kidney transplantation following liver transplant alone (LTA) increased with favorable outcomes. Estimating GFR in liver transplant candidates remains challenging, and innovative methods are needed. SLK provided superior patient and graft survival compared to LTA only for patients with advanced CKD and dialysis at least 3 months. SLK can provide immunological protection against kidney rejection in highly sensitized candidates. Post-SLK transplant care is complex, with an increased risk of complications and hospitalization.

SUMMARY

The SLK policy improved kidney access and utilization. Transplant centers are encouraged, under the safety net, to reserve SLK for liver transplant candidates with advanced CKD or dialysis at least 3 months while allowing lower thresholds for highly sensitized patients. Herein, we propose a practical approach to liver transplant candidates with kidney dysfunction.

Combined liver-kidney transplantation in pediatric patients

Combined liver-kidney transplantation (CLKT) is a surgical procedure that involves transplanting both liver and kidney organs. There are two types of CLKT: simultaneous liver-kidney transplantation (smLKT) and sequential LKT (sqLKT). CLKT accounts for a small percentage of liver transplantations (LTs), particularly in pediatric cases. Nevertheless, the procedure has demonstrated excellent outcomes, with high survival rates and lower rejection rates. The main indications for CLKT in pediatric patients differ somewhat from that in adults, in which end-stage kidney disease after LT is the major indication. In children, congenital diseases are common reason for performing CLKT; the examples of such diseases include autosomal recessive polycystic kidney disease with congenital hepatic fibrosis which equally affects both organs, and primary hyperoxaluria type 1, a primary liver disease leading kidney failure. The decision between smLKT or sqLKT depends on the dominant organ failure, the specific pathophysiology, and available organ sources. However, there remain significant surgical and societal challenges surrounding CLKT. Innovations in pharmacology and genetic engineering have decreased the necessity for CLKT in early-diagnosed cases without portal hypertension or kidney replacement therapy. Nonetheless, these advancements are not universally accessible. Therefore, decision-making algorithms should be crafted, considering region-specific organ allocation systems and prevailing medical environments.

Liver Inclusion Appears to Be Protective Against Graft Loss-Due-to Chronic But Not Acute Rejection Following Intestinal Transplantation

In intestinal transplantation, while other centers have shown that liver-including allografts have significantly more favorable graft survival and graft loss-due-to chronic rejection (CHR) rates, our center has consistently shown that modified multivisceral (MMV) and full multivisceral (MV) allografts have significantly more favorable acute cellular rejection (ACR) and severe ACR rates compared with isolated intestine (I) and liver-intestine (LI) allografts. In the attempt to resolve this apparent discrepancy, we performed stepwise Cox multivariable analyses of the hazard rates of developing graft loss-due-to acute rejection (AR) vs. CHR among 350 consecutive intestinal transplants at our center with long-term follow-up (median: 13.5 years post-transplant). Observed percentages developing graft loss-due-to AR and CHR were 14.3% (50/350) and 6.6% (23/350), respectively. Only one baseline variable was selected into the Cox model indicating a significantly lower hazard rate of developing graft loss-due-to AR: Transplant Type MMV or MV (p < 0.000001). Conversely, two baseline variables were selected into the Cox model indicating a significantly lower hazard rate of developing graft loss-due-to CHR: Received Donor Liver (LI or MV) (p = 0.002) and Received Induction (p = 0.007). In summary, while MMV/MV transplants (who receive extensive native lymphoid tissue removal) offered protection against graft loss-due-to AR, liver-containing grafts appeared to offer protection against graft loss-due-to CHR, supporting the results of other studies.

Renal damage in Hepatorenal Syndrome: A still unsolved issue

Acute kidney injury (AKI) is a common complication of cirrhosis, burdened by high morbidity and mortality rates and progression to chronic kidney disease. Hepatorenal syndrome (HRS) is a peculiar type of functional AKI observed in cirrhotic patients with ascites. HRS diagnosis is still clinical, once pre-renal azotemia and intrinsic kidney damage have been excluded by applying well-established and internationally adopted criteria. HRS is considered reversible because of the absence of intrinsic renal damage. However, HRS reversibility has been questioned, due to the lack of response to treatment with vasoconstrictors plus albumin in a relevant percentage of patients and to the persistence of renal dysfunction in HRS patients who underwent liver transplantation (LT). Indeed, LT is the only ultimate treatment, as it solves both liver failure and portal hypertension. Thus, the presence of renal damage in HRS can be hypothesized. In this scenario, neutrophil gelatinase-associated lipocalin (NGAL), one of the most promising biomarkers, may help in characterizing the type of renal injury, distinguishing between HRS and acute tubular necrosis. This review gathers the available evidence in favor and against the presence of structural lesions in HRS in terms of either renal histology and urinary biomarkers with a particular focus on NGAL. The ability to properly characterize which component of renal dysfunction prevails - functional rather than structural - entails a relevant clinical impact for the treatment of these patients, both in terms of medical therapy and liver vs. combined liver-kidney transplantation.

The Italian data on SARS-CoV-2 infection in transplanted patients support an organ specific immune response in liver recipients

Introduction

The study of immune response to SARSCoV-2 infection in different solid organ transplant settings represents an opportunity for clarifying the interplay between SARS-CoV-2 and the immune system. In our nationwide registry study from Italy, we specifically evaluated, during the first wave pandemic, i.e., in non-vaccinated patients, COVID-19 prevalence of infection, mortality, and lethality in liver transplant recipients (LTRs), using non-liver solid transplant recipients (NL-SOTRs) and the Italian general population (GP) as comparators.

Methods

Case collection started from February 21 to June 22, 2020, using the data from the National Institute of Health and National Transplant Center, whereas the data analysis was performed on September 30, 2020.To compare the sex- and age-adjusted distribution of infection, mortality, and lethality in LTRs, NL-SOTRs, and Italian GP we applied an indirect standardization method to determine the standardized rate.

Results

Among the 43,983 Italian SOTRs with a functioning graft, LTRs accounted for 14,168 patients, of whom 89 were SARS-CoV-2 infected. In the 29,815 NL-SOTRs, 361 cases of SARS-CoV-2 infection were observed. The geographical distribution of the disease was highly variable across the different Italian regions. The standardized rate of infection, mortality, and lethality rates in LTRs resulted lower compared to NL-SOTRs [1.02 (95%CI 0.81-1.23) vs. 2.01 (95%CI 1.8-2.2); 1.0 (95%CI 0.5-1.5) vs. 4.5 (95%CI 3.6-5.3); 1.6 (95%CI 0.7-2.4) vs. 2.8 (95%CI 2.2-3.3), respectively] and comparable to the Italian GP.

Discussion

According to the most recent studies on SOTRs and SARS-CoV-2 infection, our data strongly suggest that, in contrast to what was observed in NL-SOTRs receiving a similar immunosuppressive therapy, LTRs have the same risk of SARS-CoV-2 infection, mortality, and lethality observed in the general population. These results suggest an immune response to SARS-CoV-2 infection in LTRS that is different from NL-SOTRs, probably related to the ability of the grafted liver to induce immunotolerance.

Issues in multi-organ transplantation of the liver with kidney or heart in polycystic liver-kidney disease or congenital heart disease: Current practices and immunological aspects

Solid organ transplantation has become an integral part of the management of patients with end-stage diseases of the kidney, liver, heart and lungs. Most procedures occur in isolation, but multi-organ transplantation of the liver with either the kidney or heart has become an option. As more patients with congenital heart disease and cardiac cirrhosis survive into adulthood, particularly after the Fontan procedure, liver transplant teams are expected to face questions regarding multi-organ (heart-liver) transplantation. Similarly, patients with polycystic kidneys and livers may be managed by multi-organ transplantation. Herein, we review the indications and outcomes of simultaneous liver-kidney transplantation for polycystic liver-kidney disease, and discuss the indications, timing and procedural aspects of combined heart-liver transplantation. We also summarise the evidence for, and potential mechanisms underlying, the immunoprotective impact of liver allografts on the simultaneously transplanted organs.

Examining the Role for Donor-specific Antibody Testing in Simultaneous Liver-kidney Transplantation: A Single-center Analysis of Outcomes

BACKGROUND

Simultaneous liver-kidney transplantation (SLKT) is increasingly used for patients with concurrent end-stage liver and renal disease. Emerging evidence suggests that simultaneous liver transplant can provide a tolerogenic benefit to multiorgan transplant recipients. Posttransplant donor-specific antibody (DSA) may be associated with worse outcomes; however, the role for testing DSA in SLKT is unclear.

METHODS

This study retrospectively assessed the impact of DSA on outcomes following primary SLKT at a large-volume center between 2008 and 2018. Patients were grouped by positive DSA, negative DSA, and DSA not tested, and data were obtained from our institutional database and chart review.

RESULTS

The cohort included 138 SLKT recipients with a mean age of 56.1 ± 9.7 y; 61.6% were male, and 55.8% were Hispanic. Overall, 62 patients were tested for DSA posttransplant, and 33 patients (23.9%) had at least 1 DSA detected. A total of 34 patients (24.6%) experienced at least 1 episode of liver rejection, and 23 patients (16.7%) experienced kidney rejection. Over 50% of patients with de novo DSA changed status during their posttransplant course. Rates of both liver and kidney rejection were slightly higher in the DSA + group, but liver allograft, kidney allograft, and patient survival did not differ when grouped by whether DSA testing was performed or DSA positivity.

CONCLUSIONS

These data demonstrate that SLKT is associated with excellent long-term patient and allograft survival with a relatively low rate of rejection. In our experience, testing for DSA does not impact SLKT outcomes' and further multicenter analyses are needed to establish standard of care.

Modified Mercedes Single Incision for Combined Liver Kidney Transplant: A Case Series Report

BACKGROUND

The traditional approach in combined liver-kidney transplantation involves 2 separate and sequential incisions. We describe a modification of the standard Mercedes incision that allows a single-incision operation while providing and maintaining adequate exposure to enable safe dual-allograft transplantation.

METHODS

Modification of the standard Mercedes incision includes bilateral, subcostal, muscle splitting incision 4 fingerbreadths below the rib edge with a midline, cephalad incision and inferior ± medial ipsilateral extension on the side of intended iliac fossa laterality for renovascular and ureteroneocystostomy anastomosis.

RESULTS

Five consecutive patients (3 women/2 men; mean age, 49 years; median body mass index, 29.8 kg/m²) underwent combined liver-kidney transplantation for end-stage liver disease and progressive hepatorenal syndrome via a modified Mercedes single-incision approach (at a median Model for End-stage Liver Disease of 37) without an additional kidney transplant incision, extraperitoneal exposure, or addition of wound retractors. Two out of the 5 patients experienced postoperative wound complications, including 1 with delayed wound healing and 1 with superficial dehiscence. All patients have normal dual-allograft function at or beyond 6 months posttransplantation.

CONCLUSIONS

The modified Mercedes single-incision technique is safe and feasible. Lowering the subcostal incisions with unilateral, inferomedial extension allows adequate visualization of the lower abdominopelvic area without compromising exposure of the upper abdomen for both renal and liver allograft implantation. Further studies are needed to prove the theoretical benefits of this technique.

Liver mesenchymal stem cells are superior inhibitors of NK cell functions through differences in their secretome compared to other mesenchymal stem cells

Liver-resident mesenchymal stem cells (L-MSCs) are superior inhibitors of alloreactive T cell responses compared to their counterparts from bone marrow (BM-MSCs) or adipose tissue (A-MSCs), suggesting a role in liver’s overall tolerogenic microenvironment. Whether L-MSCs also impact NK cell functions differently than other MSCs is not known. We generated and characterized L-MSCs, A-MSCs and BM-MSCs from human tissues. The mass spectrometry analysis demonstrated that L-MSC secretome is uniquely different than that of A-MSC/BM-MSC, with enriched protein sets involved in IFNγ responses and signaling. When co-cultured with primary human NK cells, L-MSCs but not other MSCs, decreased surface expression of activating receptors NKp44 and NKG2D. L-MSCs also decreased IFNγ secretion by IL-2-stimulated NK cells more effectively than other MSCs. Cytolytic function of NK cells were reduced significantly when co-cultured with L-MSCs, whereas A-MSCs or BM-MSCs did not have a major impact. Mechanistic studies showed that the L-MSC-mediated reduction in NK cell cytotoxicity is not through changes in secretion of the cytotoxic proteins Perforin, Granzyme A or B, but through increased production of HLA-C1 found in L-MSC secretome that inhibits NK cells by stimulating their inhibitory receptor KIRDL2/3. L-MSCs are more potent inhibitors of NK cell functions than A-MSC or BM-MSC. Combined with their T cell inhibitory features, these results suggest L-MSCs contribute to the tolerogenic liver microenvironment and liver-induced systemic tolerance often observed after liver transplantation.

Long-term outcomes of crossmatch positive simultaneous liver-kidney transplantations in the United States

The long-term outcomes of positive crossmatch (+XM) simultaneous liver-kidney (SLK) transplantations are conflicting. We examined the association between crossmatch status and SLK outcomes in recipients discharged on tacrolimus and mycophenolate with or without steroids. We analyzed the Scientific Registry of Transplant Recipients for all primary SLK recipients between 2003 and 2020 with available crossmatch and induction data. We grouped recipients according to the crossmatch status: negative crossmatch (-XM; n = 3040) and +XM (n = 407). Kaplan-Meier curves were generated to examine recipient, death-censored liver, and death-censored kidney survival by crossmatch status. Cox proportional hazard models were used to investigate the association between crossmatch status and outcomes of interest with follow-up censored at 10 years. Models were adjusted for recipient age, sex, diabetes mellitus, Model for End-Stage Liver Disease score, duration on the liver waiting list, induction immunosuppression, steroid maintenance, hepatitis C infection, donor age and sex, local vs. shared organ, cold ischemia time, and previous liver transplantation status. In the univariable analysis, crossmatch status was not associated with recipient survival (log-rank p = 0.63), death-censored liver graft survival (log-rank p = 0.05), or death-censored kidney graft survival (log-rank p = 0.11). Compared with -XM, +XM recipients had a similar 1-year liver rejection rate, but higher kidney rejection rate (4.6% vs. 8.9%, p = 0.002). In the multivariable models, +XM status was not associated with deleterious long-term recipient, liver, or kidney grafts survival. -XM and +XM SLK transplantations have comparable long-term recipient, liver graft, and kidney survival with a slightly increased risk of early kidney allograft rejection in the +XM group. Crossmatch positivity in SLK transplantations should not influence the decision to use organs from a specific donor.

Incidence of acute rejection and patient survival in combined heart-liver transplantation

Combined heart-liver transplantation (CHLT) is indicated for patients with concomitant end-stage heart and liver disease or patients with amyloid heart disease where liver transplantation mitigates progression. Limited data suggest that the liver allograft provides immunoprotection for heart and kidney allografts in combined transplantation from the same donor. We hypothesized that CHLT reduces the incidence of acute cellular rejection (ACR) and the development of de novo donor-specific antibodies (DSAs) compared with heart-alone transplantation (HA). We conducted a retrospective analysis of 32 CHLT and 280 HA recipients in a single-center experience. The primary outcome was incidence of ACR based on protocol and for-cause myocardial biopsy. Rejection was graded by the International Society of Heart and Lung Transplantation guidelines with Grade 2R and higher considered significant. Secondary outcomes included the development of new DSAs, cardiac function, and patient and cardiac graft survival rates. Of CHLT patients, 9.7% had ACR compared with 45.3% of HA patients (p < 0.01). Mean pretransplant calculated panel reactive antibody (cPRA) levels were similar between groups (CHLT 9.4% vs. HA 9.5%; p = 0.97). Among patients who underwent testing, 26.9% of the CHLT and 16.7% of HA developed DSA (p = 0.19). Despite the difference in ACR, patient and cardiac graft survival rates were similar at 5 years (CHLT 82.1% vs. HA 80.9% [p = 0.73]; CHLT 82.1% vs. HA 80.9% [p = 0.73]). CHLT reduced the incidence of ACR in the cardiac allograft, suggesting that the liver offers immunoprotection against cellular mechanisms of rejection without significant impacts on patient and cardiac graft survival rates. CHLT did not reduce the incidence of de novo DSA, possibly portending similar long-term survival among cardiac allografts in CHLT and HA.

Impact of DSA and immunosuppression minimization on rejection, graft, and patient survival after simultaneous liver–kidney transplantation

Background

Acute rejection rate is low after simultaneous liver–kidney transplantation (SLKT), leading some groups to minimize immunosuppressive (IS) regimens. However, the impact of preformed (pDSA) or de novo donor-specific antibodies (dnDSA) on the graft remains unclear.

Methods

We performed a retrospective analysis of 102 consecutive SLKT patients to study the impact of anti-HLA antibodies.

Results

Anti-HLA antibodies were detected in 75 recipients (class I 23.8%, both classes I and II 23.8%, and class II 14.3%). In total, 42.8% of the patients had pDSA and 21.7% developed dnDSA. Overall patient survival at 1–3 and 5 years, was respectively 88, 84, and 80%. Acute rejection occurred respectively in 3 (2.9%) liver and 6 kidney (5.9%) recipients. pDSA with titers over 10,000 mean fluorescence intensity (14.3%) was associated with lower patient survival (40 vs. 82%) but not with acute rejection. In a multivariable Cox regression analysis, the risk of death was associated with maleness, the highest titer of pDSA (p < 0.0007) or the sum of pDSA >10,000. Renal function did not differ between patients with class I pDSA (p = 0.631) and those with class II pDSA (p = 0.112) or between patients with and without a positive cross-match (p = 0.842). dnDSA were not associated with acute rejection, graft dysfunction or patient survival. IS minimization was not associated with rejection, graft dysfunction or death.

Conclusion

In SLKT, high levels of pDSA >10,000 were associated with lower patient survival, but not rejection or graft survival. Minimization of maintenance immunosuppression regimen was not associated with a poorer outcome.

Predictors of Kidney Delayed Graft Function and Its Prognostic Impact following Combined Liver-Kidney Transplantation: A Recent Single-Center Experience

Combined liver−kidney transplantation (CLKT) improves patient survival among liver transplant recipients with renal dysfunction. However, kidney delayed graft function (kDGF) still represents a common and challenging complication that can negatively impact clinical outcomes. This retrospective study analyzed the incidence, potential risk factors, and prognostic impact of kDGF development following CLKT in a recently transplanted cohort. Specifically, 115 consecutive CLKT recipients who were transplanted at our center between January 2015 and February 2021 were studied. All transplanted kidneys received hypothermic pulsatile machine perfusion (HPMP) prior to transplant. The primary outcome was kDGF development. Secondary outcomes included the combined incidence and severity of developing postoperative complications; development of postoperative infections; biopsy-proven acute rejection (BPAR); renal function at 1, 3, 6, and 12 months post-transplant; and death-censored graft and patient survival. kDGF was observed in 37.4% (43/115) of patients. Multivariable analysis of kDGF revealed the following independent predictors: preoperative dialysis (p = 0.0003), lower recipient BMI (p = 0.006), older donor age (p = 0.003), utilization of DCD donors (p = 0.007), and longer delay of kidney transplantation after liver transplantation (p = 0.0003). With a median follow-up of 36.7 months post-transplant, kDGF was associated with a significantly increased risk of developing more severe postoperative complication(s) (p < 0.000001), poorer renal function (particularly at 1 month post-transplant, p < 0.000001), and worse death-censored graft (p = 0.00004) and patient survival (p = 0.0002). kDGF may be responsible for remarkable negative effects on immediate and potentially longer-term clinical outcomes after CLKT. Understanding the important risk factors for kDGF development in CLKT may better guide recipient and donor selection(s) and improve clinical decisions in this increasing group of transplant recipients.

Pros and Cons of the Safety Net Rule for Prioritization of Liver Transplant Recipients Who Receive Liver Alone Transplant but Develop End-Stage Renal Disease

The number of patients presenting with cirrhosis with kidney injury and the potential need for SLKT is increasing. In 2017, standardized criteria were implemented to identify candidates for SLKT as well as criteria for prioritizing LTA recipients for kidney transplant if they developed kidney failure, which is referred to as the 'safety net rule.' Goal of the safety net rule is to provide a pathway that provides increased priority to LTA recipients with renal failure who may have previously undergone SLKT. This article reviews the pros and cons of the safety net rule for liver transplant recipients who develop ESRD.

[Kidney failure after liver transplantation]

One third of cirrhotic patients present impaired kidney function. It has multifactorial causes and has a harmful effect on patients' morbi-mortality before and after liver transplant. Kidney function does not improve in all patients after liver transplantation and liver-transplant recipients are at high risk of developing chronic kidney disease. Causes for renal dysfunction can be divided in three groups: preoperative, peroperative and postoperative factors. To date, there is no consensus for the modality of evaluation the risk for chronic kidney disease after liver transplantation, and for its prevention. In the present review, we describe the outcome of kidney function after liver transplantation, and the prognostic factors of chronic kidney disease to determine a risk stratification for each patient. Furthermore, we discuss therapeutic options to prevent kidney dysfunction in this setting, and highlight the indications of combined liver-kidney transplantation.

Alloantibodies after simultaneous liver-kidney transplant: A story of primary nonfunction, retransplantation, and antibody-mediated rejection

Simultaneous liver-kidney transplant (SLKT) in the presence of antihuman leukocyte antigen (HLA) donor-specific antibodies (DSA) is a well-accepted practice. Herein, we describe the evolution of alloantibodies in a patient who received an SLKT. The pre-SLKT serum sample showed multiple strong DSA. As expected, all DSA cleared in a sample collected 4 days after the SLKT. Because of the primary nonfunction of the liver in the SLKT, the patient had a second liver transplant 4 days later. An abrupt increase in DSA levels against the kidney was detected 10 days after the second liver transplant. These DSA were refractory to treatment, and the transplanted kidney was lost due to antibody-mediated rejection (AMR). A detailed study of the HLA epitopes recognized by DSA and, after normalization with third-party alloantibodies to address the effect of multiple transfusions and liver allograft neutralization, showed that the elimination of these antibodies depended on the HLA antigens expressed by the transplanted liver cells. The return of DSA after removal of the first transplanted liver was associated with AMR in the transplanted kidney.

Two is better than one: when to consider multiorgan transplant

PURPOSE OF REVIEW

Patients with end-stage heart failure often present with concomitant end-stage renal or end-stage liver disease requiring transplantation. There are limited data regarding the risks, benefits and long-term outcomes of heart-kidney (HKT) and heart-liver transplantation (HLT), and guidelines are mainly limited to expert consensus statements.

RECENT FINDINGS

The incidence of HKT and HLT has steadily increased in recent years with favourable outcomes. Both single-centre and large database studies have shown benefits of HKT/HLT through improved survival, freedom from dialysis and lower rates of rejection and coronary allograft vasculopathy. Current guidelines are institution dependent and controversial due to the ethical considerations surrounding multiorgan transplantation (MOT).

SUMMARY

MOT is an effective and necessary option for patients with end-stage heart and kidney/liver failure. MOT is ethically permissible, and efforts should be made to consider eligible patients as early as possible to limit morbidity and mortality. Further research is needed regarding appropriate listing criteria and long-term outcomes.

Combined heart-liver-kidney transplant: The university of chicago medicine experience

Until recently, combined heart-liver-kidney transplantation was considered too complex or too high-risk an option for patients with end-stage heart failure who present with advanced liver and kidney failure as well. The objective of this paper is to present our institution's best practices for successfully executing this highly challenging operation. At our institution, referral patterns are most often initiated through the cardiac team. Determinants of successful outcomes include diligent multidisciplinary patient selection, detailed perioperative planning, and choreographed care transition and coordination among all transplant teams. The surgery proceeds in three distinct phases with three different teams, linked seamlessly in planned handoffs. The selection and perioperative care are executed with determined collaboration of all of the invested care teams. This article is protected by copyright. All rights reserved.

Crossmatch, Donor-specific Antibody Testing, and Immunosuppression in Simultaneous Liver and Kidney Transplantation: A Review

Since the introduction of simultaneous liver-kidney transplantation (SLKT) in the 1960s, the potential for immunological protection from the liver allograft to a simultaneously transplanted kidney has been recognized. Due to expanded indications and changes in allocation policies, there has been increased utilization of SLKT. Despite growing experience, a lack of consensus exists regarding the extent of the immunological privilege of the liver the role for donor-specific HLA antibody (DSA) and crossmatch testing, and appropriateness of modern immunosuppression protocols in SLKT recipients. This review provides a detailed analysis of SLKT outcomes in the context of these factors, suggesting that although the liver can reduce the incidence of antibody-mediated rejection, attention should be given to liver allograft function, previous failed transplants, and other risk factors in pretransplant risk assessment. Current methods of DSA and crossmatch testing in SLKT are also discussed, and the role of specific DSA (high mean fluorescence intensity antibody, C1q+ binding) and their potential importance in posttransplant risk assessment are examined. Finally, trends in SLKT immunosuppression are discussed, including the use of nondepleting agents for induction and de-escalating use of steroids for maintenance immunosuppression. Ongoing research, including multicenter or randomized trials, will be necessary to optimize immune-related outcomes in SLKT recipients.

Plasmacytoid dendritic cells mediate the tolerogenic effect of CD8+regulatory T cells in a rat tolerant liver transplantation model

BACKGROUND

Tolerance is more easily induced in liver transplant models than in other organs; CD8⁺CD45RC^lowregulatory T cells (Tregs) have been shown to induce tolerance in heart allografts. Whether CD8⁺CD45RC^lowTregs could induce tolerance in a liver transplant model and how dendritic cells (DCs) mediate the CD8⁺CD45RC^lowTregs effect remains to be investigated.

METHODS

A rat liver transplantation model was established and used to test tolerance and acute rejection compared to control groups. Liver function and histopathological changes of allograft were examined by enzyme-linked immunosorbent assay (ELISA) and haematoxylin and eosin (H&E) staining, respectively. The distribution and proportion of CD8⁺CD45RC^lowTregs and plasmacytoid dendritic cells (pDCs) in the allografts and spleen were determined using flow cytometry. Cytokine secretion levels were determined using ELISA and real-time quantitative PCR (qRT-PCR).

RESULTS

The rat liver transplantation model was well established, with a success rate of 93.3% (28/30). The mean survival time of the tolerant and acute-rejection rats were 156 and 14 days, respectively. The proportions of CD8⁺CD45RC^lowTegs were higher in the allografts of tolerant rats than in those of acute-rejection rats (33.1 ± 4.3 and 12.4 ± 4.6, respectively; P = 0.04). Significant accumulation of pDCs was observed in tolerant liver graft rats compared to that in acute-rejection rats (1.46 ± 0.23 and 0.80 ± 0.20, respectively; P = 0.02). Importantly, CD8⁺CD45RC^lowTregs were positively associated with the frequency of pDCs (P = 0.001, r² = 0.775). The protein and mRNA expression of IL-10 and TGF-β in the allograft group were increased, possibly being responsible for tolerance induction.

CONCLUSION

CD8⁺CD45RC^lowT cells interact with pDCs through the induction of IL-10 and TGF-β expression and are responsible for inducing immune tolerance in rat liver transplantation.

Case Report: Combined Liver-Kidney Transplantation to Correct a Mutation in Complement Factor B in an Atypical Hemolytic Uremic Syndrome Patient

Pathogenic gain-of-function variants in complement Factor B were identified as causative of atypical Hemolytic Uremic syndrome (aHUS) in 2007. These mutations generate a reduction on the plasma levels of complement C3. A four-month-old boy was diagnosed with hypocomplementemic aHUS in May 2000, and he suffered seven recurrences during the following three years. He developed a severe hypertension which required 6 anti-hypertensive drugs and presented acrocyanosis and several confusional episodes. Plasma infusion or exchange, and immunosuppressive treatments did not improve the clinical evolution, and the patient developed end-stage renal disease at the age of 3 years. Hypertension and vascular symptoms persisted while he was on peritoneal dialysis or hemodialysis, as well as after bilateral nephrectomy. C3 levels remained low, while C4 levels were normal. In 2005, a heterozygous gain-of-function mutation in Factor B (K323E) was found. A combined liver and kidney transplantation (CLKT) was performed in March 2009, since there was not any therapy for complement inhibition in these patients. Kidney and liver functions normalized in the first two weeks, and the C3/C4 ratio immediately after transplantation, indicating that the C3 activation has been corrected. After remaining stable for 4 years, the patient suffered a B-cell non-Hodgkin lymphoma that was cured by chemotherapy and reduction of immunosuppressive drugs. Signs of liver rejection with cholangitis were observed a few months later, and a second liver graft was done 11 years after the CLKT. One year later, the patient maintains normal kidney and liver functions, also C3 and C4 levels are within the normal range. The 12-year follow-up of the patient reveals that, in spite of severe complications, CLKT was an acceptable therapeutic option for this aHUS patient.

Current State of Multiorgan Transplantation and Implications for Future Practice and Policy

The incidence of kidney dysfunction has increased in liver transplant and heart transplant candidates, reflecting a changing patient population and allocation policies that prioritize the most urgent candidates. A higher burden of pretransplant kidney dysfunction has resulted in a substantial rise in the utilization of multiorgan transplantation (MOT). Owing to a shortage of available deceased donor kidneys, the increased use of MOT has the potential to disadvantage kidney-alone transplant candidates, as current allocation policies generally provide priority for MOT candidates above all kidney-alone transplant candidates. In this review, the implications of kidney disease in liver transplant and heart transplant candidates is reviewed, and current policies used to allocate organs are discussed. Important ethical considerations pertaining to MOT allocation are examined, and future policy modifications that may improve both equity and utility in MOT policy are considered.

Kidney Failure after Liver Transplantation

One-third of patients with cirrhosis present kidney failure (AKI and CKD). It has multifactorial causes and a harmful effect on morbidity and mortality before and after liver transplantation. Kidney function does not improve in all patients after liver transplantation, and liver transplant recipients are at a high risk of developing chronic kidney disease. The causes of renal dysfunction can be divided into three groups: pre-operative, perioperative and post-operative factors. To date, there is no consensus on the modality to evaluate the risk of chronic kidney disease after liver transplantation, or for its prevention. In this narrative review, we describe the outcome of kidney function after liver transplantation, and the prognostic factors of chronic kidney disease in order to establish a risk categorization for each patient. Furthermore, we discuss therapeutic options to prevent kidney dysfunction in this context, and highlight the indications of combined liver–kidney transplantation.

Renal Outcomes After Simultaneous Liver-Kidney Transplantation: Results from the US Multicenter Simultaneous Liver-Kidney Transplantation Consortium

Simultaneous liver-kidney transplantation (SLKT) is increasingly common in the United States. However, little is known about the renal-related outcomes following SLKT, which are essential to maximize the health of these allografts. We examined the factors impacting renal function following SLKT. This is an observational multicenter cohort study from the US Multicenter SLKT Consortium consisting of recipients of SLKT aged ≥18 years of transplantations performed between February 2002 and June 2017 at 6 large US centers in 6 different United Network for Organ Sharing regions. The primary outcome was incident post-SLKT stage 4-5 chronic kidney disease (CKD) defined as <30 mL/minute/1.73 m² or listing for kidney transplant. The median age of the recipients (n = 570) was 58 years (interquartile range, 51-64 years), and 37% were women, 76% were White, 33% had hepatitis C virus infection, 20% had nonalcoholic steatohepatitis (NASH), and 23% had alcohol-related liver disease; 68% developed ≥ stage 3 CKD at the end of follow-up. The 1-year, 3-year, and 5-year incidence rates of post-SLKT stage 4-5 CKD were 10%, 12%, and 16%, respectively. Pre-SLKT diabetes mellitus (hazard ratio [HR], 1.45; 95% CI, 1.00-2.15), NASH (HR, 1.58; 95% CI, 1.01-2.45), and delayed kidney graft function (HR, 1.72; 95% CI, 1.10-2.71) were the recipient factors independently associated with high risk, whereas the use of tacrolimus (HR, 0.44; 95% CI, 0.22-0.89) reduced the risk. Women (β = -6.22 ± 2.16 mL/minute/1.73 m² ; P = 0.004), NASH (β = -7.27 ± 3.27 mL/minute/1.73 m² ; P = 0.027), and delayed kidney graft function (β = -7.25 ± 2.26 mL/minute/1.73 m² ; P = 0.007) were independently associated with low estimated glomerular filtration rate at last follow-up. Stage 4-5 CKD is common after SLKT. There remains an unmet need for personalized renal protective strategies, specifically stratified by sex, diabetes mellitus, and liver disease, to preserve renal function among SLKT recipients.

Current and Evolving Indications for Simultaneous Liver Kidney Transplantation

This review will discuss the etiologies of kidney disease in liver transplant candidates, provide a historical background of the prior evolution of simultaneous liver-kidney (SLK) transplant indications, discuss the current indications for SLK including Organ Procurement and Transplantation Network policies and Model for End Stage Liver Disease exception points, as well as provide an overview of the safety net kidney transplant policy. Finally, the authors explore unanswered questions and future research needed in SLK transplantation.

Liver transplantation for congenital hepatic fibrosis

Congenital hepatic fibrosis (CHF) is a hereditary fibrocystic disease that can progress to portal hypertension and recurrent cholangitis requiring liver transplantation (LT). It can be associated with renal pathology and need for kidney transplantation (KT). We describe the clinical characteristics and outcomes of patients undergoing liver transplantation alone (LTA) and simultaneous liver-kidney transplantation (SLKT) for CHF using the Unites States Scientific Registry of Transplant Recipients. A total of 197 patients who received LT for CHF between 2002 and 2018 were identified - 87 (44.2%) received SLKT, 110 (55.8%) received LTA. The 1-, 3- and 5-year patient survival were 99.0%, 96.2% and 94.6%. The 1-, 3- and 5-year liver graft survival were 94.9%, 91.1% and 89.6%. No significant differences in patient or liver graft survival were observed between the SLKT and LTA groups, or between paediatric and adult recipients. 53.3% of patients with CHF necessitating LT also have significant renal disease requiring KT. Kidney graft survival for isolated KT prior to LT were poorer compared with KT performed simultaneously or after LT. Both LTA and SLKT for CHF are associated with excellent long-term outcomes in paediatric and adult patients.

Cell-Mediated Therapies to Facilitate Operational Tolerance in Liver Transplantation

Cell therapies using immune cells or non-parenchymal cells of the liver have emerged as potential treatments to facilitate immunosuppression withdrawal and to induce operational tolerance in liver transplant (LT) recipients. Recent pre-clinical and clinical trials of cellular therapies including regulatory T cells, regulatory dendritic cells, and mesenchymal cells have shown promising results. Here we briefly summarize current concepts of cellular therapy for induction of operational tolerance in LT recipients.

Simultaneous Heart-Liver Transplantation for Congenital Heart Disease in the United States: Rapidly Increasing With Acceptable Outcomes

BACKGROUND AND AIMS

There are more adults than children living with congenital heart disease (CHD) in the United States, with a growing proportion requiring heart-liver transplantation (HLT). Our aim was to ascertain the frequency, outcomes, and prognostic factors in this patient population.

APPROACH AND RESULTS

United Network for Organ Sharing data on adult patients who underwent heart transplantation (HT) from 2009 through March 2020 were analyzed. The primary study outcome was patient survival. Cox proportional-hazards modeling assessed for mortality associations. There were 1,084 HT recipients: 817 (75.4%) CHD HTs only, 74 (6.8%) CHD HLTs, 179 (16.5%) non-CHD HLTs, and 14 (1.3%) heart-liver-kidney transplants. The number of CHD HLTs increased from a prior rate of 4/year to 21/year in 2019. Among patients with CHD, the 5-year survival rates were 74.1% and 73.6% in HTs only and HLTs, respectively (P = 0.865). There was a higher rate of allograft failure attributable to rejection in CHD HTs only compared with CHD HLTs (3.2% versus 0.4%; P = 0.014). Only 25 out of 115 HT-performing hospitals undertook CHD HLTs. Higher-volume centers (averaging one CHD HLT per year) had a 5-year patient survival rate of 83.0% compared with 61.3% in lower-volume centers (P = 0.079). Among HLT recipients, total bilirubin (hazard ratio [HR], 1.06; 95% confidence interval [CI], 1.01-1.12) and diabetes (HR = 2.97, 95% CI = 1.21-7.31) were independently associated with increased mortality risk, whereas CHD and age were not.

CONCLUSIONS

The rate of HLT for adult CHD in the United States is rising dramatically. The survival outcomes between CHD HT only and CHD HLT groups are comparable; however, the HLT group had lower rates of acute rejection. Among HLT recipients, diabetes and elevated bilirubin are associated with increased posttransplant mortality risk. An average of one CHD HLT per year could be considered a minimum quality metric at transplant centers.

Comparable in vitro Function of Human Liver-Derived and Adipose Tissue-Derived Mesenchymal Stromal Cells: Implications for Cell-Based Therapy

Mesenchymal stem/stromal cells (MSCs) have been investigated extensively for their immunotherapeutic and regenerative properties, which may differ by cell source. In MSCs harvested from donors matched for sex, age, and body mass index, we compared the proliferative and migration functions of liver-derived MSCs (L-MSCs) and adipose tissue-derived MSCs (A-MSCs) (n = 6 donors each). Cellular senescence was evaluated by senescence-associated beta-galactosidase enzyme activity and expression of senescence-associated secretory phenotype (SASP) factors using real-time quantitative polymerase chain and by western blot assay. The pro-angiogenic and reparative potency of MSCs was compared by co-culturing MSCs with injured human umbilical vein endothelial cells (HUVEC). The proliferation and migration properties were similar in L-MSCs and A-MSCs. Although cell cycle arrest and SASP genes were similarly expressed in both MSCs, tumor necrosis factor alpha gene and protein expression were significantly downregulated in L-MSCs. In co-cultured injured HUVEC, A-MSCs restored significantly more tubes and tube connections than L-MSCs. Therefore, despite many functional similarities between L-MSCs and A-MSCs, L-MSCs have enhanced immunomodulatory properties, while A-MSCs appear to have better pro-angiogenic and vascular reparative potency. Availability of a broad range of cellular options might enable selecting cell-based therapy appropriate for the specific underlying disease.

Heart-After-Liver Transplantation Attenuates Rejection of Cardiac Allografts in Sensitized Patients

BACKGROUND

In patients undergoing heart transplantation, significant allosensitization limits access to organs, resulting in longer wait times and high waitlist mortality. Current desensitization strategies are limited in enabling successful transplantation.

OBJECTIVES

The purpose of this study was to describe the cumulative experience of combined heart-liver transplantation using a novel heart-after-liver transplant (HALT) protocol resulting in profound immunologic protection.

METHODS

Reported are the results of a clinical protocol that was instituted to transplant highly sensitized patients requiring combined heart and liver transplantation at a single institution. Patients were dual-organ listed with perceived elevated risk of rejection or markedly prolonged waitlist time due to high levels of allo-antibodies. Detailed immunological data and long-term patient and graft outcomes were obtained.

RESULTS

A total of 7 patients (age 43 ± 7 years, 86% women) with high allosensitization (median calculated panel reactive antibody = 77%) underwent HALT. All had significant, unacceptable donor specific antibodies (DSA) (>4,000 mean fluorescence antibody). Prospective pre-operative flow cytometric T-cell crossmatch was positive in all, and B-cell crossmatch was positive in 5 of 7. After HALT, retrospective crossmatch (B- and T-cell) became negative in all. DSA fell dramatically; at last follow-up, all pre-formed or de novo DSA levels were insignificant at <2,000 mean fluorescence antibody. No patients experienced >1R rejection over a median follow-up of 48 months (interquartile range: 25 to 68 months). There was 1 death due to metastatic cancer and no significant graft dysfunction.

CONCLUSIONS

A heart-after-liver transplantation protocol enables successful transplantation via near-elimination of DSA and is effective in preventing adverse immunological outcomes in highly sensitized patients listed for combined heart-liver transplantation.

A Role for Human Renal Tubular Epithelial Cells in Direct Allo-Recognition by CD4+ T-Cells and the Effect of Ischemia-Reperfusion

Direct allorecognition is the earliest and most potent immune response against a kidney allograft. Currently, it is thought that passenger donor professional antigen-presenting cells (APCs) are responsible. Further, many studies support that graft ischemia-reperfusion injury increases the probability of acute rejection. We evaluated the possible role of primary human proximal renal tubular epithelial cells (RPTECs) in direct allorecognition by CD4+ T-cells and the effect of anoxia-reoxygenation. In cell culture, we detected that RPTECs express all the required molecules for CD4+ T-cell activation (HLA-DR, CD80, and ICAM-1). Anoxia-reoxygenation decreased HLA-DR and CD80 but increased ICAM-1. Following this, RPTECs were co-cultured with alloreactive CD4+ T-cells. In T-cells, zeta chain phosphorylation and c-Myc increased, indicating activation of T-cell receptor and co-stimulation signal transduction pathways, respectively. T-cell proliferation assessed with bromodeoxyuridine assay and with the marker Ki-67 increased. Previous culture of RPTECs under anoxia raised all the above parameters in T-cells. FOXP3 remained unaffected in all cases, signifying that proliferating T-cells were not differentiated towards a regulatory phenotype. Our results support that direct allorecognition may be mediated by RPTECs even in the absence of donor-derived professional APCs. Also, ischemia-reperfusion injury of the graft may enhance the above capacity of RPTECs, increasing the possibility of acute rejection.

Optimizing the Selection of Patients for Simultaneous Liver-Kidney Transplant

Simultaneous liver-kidney transplantation has increased significantly in the Model for End Stage Liver Disease era. The transplantation policy has evolved significantly since the implementation of allocation based on the Model for End Stage Liver Disease. Current policy takes into account the medical eligibility criteria for simultaneous liver-kidney transplantation listing. It also provides a safety net option and prioritizes kidney transplant after liver transplant recipients who are unlikely to recover their renal function within 60 to 365 days after liver transplant alone. This review seeks to understand the underlying challenges in carefully selecting the candidates while optimizing the patient selection.

Immunosuppression considerations in simultaneous organ transplant

Solid organ transplantation is a life-saving procedure for patients in the end stage of heart, lung, kidney, and liver failure. For patients with more than one failing organ, simultaneous organ transplantation has emerged as a viable treatment option. Immunosuppression strategies and outcomes for simultaneous organ transplant recipients have been reported, but often involve limited populations. Transplanting dual organs poses challenges in terms of balancing immunosuppression with immunologic risk and allograft damage from surgical complications. Furthermore, transplanting certain organs can impose considerations on the management of immunosuppression. For example, liver allografts may confer immunologic privilege and lower rates of rejection of other allografts. This review article evaluates immunosuppression strategies for simultaneous kidney-pancreas, liver-kidney, heart-kidney, heart-liver, heart-lung, lung-liver, and lung-kidney transplants. To date, no comprehensive review exists to address immunosuppressive strategies in simultaneous organ transplant populations. Our review summarizes the available literature and provides evidence-based recommendations regarding immunosuppression strategies in simultaneous organ transplant recipients.

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

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

Combined liver-kidney transplantation for rare diseases

Combined liver and kidney transplantation (CLKT) is indicated in patients with failure of both organs, or for the treatment of end-stage chronic kidney disease (ESKD) caused by a genetic defect in the liver. The aim of the present review is to provide the most up-to-date overview of the rare conditions as indications for CLKT. They are major indications for CLKT in children. However, in some of them (e.g., atypical hemolytic uremic syndrome or primary hyperoxaluria), CLKT may be required in adults as well. Primary hyperoxaluria is divided into three types, of which type 1 and 2 lead to ESKD. CLKT has been proven effective in renal function replacement, at the same time preventing recurrence of the disease. Nephronophthisis is associated with liver fibrosis in 5% of cases and these patients are candidates for CLKT. In alpha 1-antitrypsin deficiency, hereditary C3 deficiency, lecithin cholesterol acyltransferase deficiency and glycogen storage diseases, glomerular or tubulointerstitial disease can lead to chronic kidney disease. Liver transplantation as a part of CLKT corrects underlying genetic and consequent metabolic abnormality. In atypical hemolytic uremic syndrome caused by mutations in the genes for factor H, successful CLKT has been reported in a small number of patients. However, for this indication, CLKT has been largely replaced by eculizumab, an anti-C5 antibody. CLKT has been well established to provide immune protection of the transplanted kidney against donor-specific antibodies against class I HLA, facilitating transplantation in a highly sensitized recipient.

Combined Liver-Kidney Transplantation With Preformed Anti-human Leukocyte Antigen Donor-Specific Antibodies

Introduction

The impact of preformed donor-specific anti–human leukocyte antigen (HLA) antibodies (pDSAs) after combined liver-kidney transplantation (CLKT) is still uncertain.

Methods

We conducted a retrospective study in 8 European high-volume transplant centers and investigated the outcome of 166 consecutive CLKTs, including 46 patients with pDSAs.

Results

Patient survival was lower in those with pDSAs (5-year patient survival rate of 63% and 78% with or without pDSA, respectively; P = 0.04). The presence of pDSAs with a mean fluorescence intensity (MFI) ≥ 5000 (hazard ratio 4.96; 95% confidence interval: 2.3–10.9; P < 0.001) and the presence of 3 or more pDSAs (hazard ratio 6.5; 95% confidence interval: 2.5–18.8; P = 0.05) were independently associated with death. The death-censored liver graft survival was similar in patients with or without pDSAs. Kidney graft survival was comparable in both groups. (The 1- and 5-year death-censored graft survival rates were 91.6% and 79.5%, respectively, in patients with pDSAs and 93% and 88%, respectively, in the donor-specific antibody [DSA]-negative group, P = not significant). Despite a higher rate of kidney graft rejection in patients with pDSAs (5-year kidney graft survival rate without rejection of 87% and 97% with or without pDSAs, respectively; P = 0.04), kidney function did not statistically differ between both groups at 5 years post-transplantation (estimated glomerular filtration rate 45 ± 17 vs. 57 ± 29 ml/min per 1.73 m², respectively, in patients with and without pDSAs). Five recipients with pDSAs (11.0%) experienced an antibody-mediated kidney rejection that led to graft loss in 1 patient.

Conclusion

Our results suggest that CLKT with pDSAs is associated with a lower patients’ survival despite good recipients’, liver and kidney grafts’ outcome.

Impact of Induction Immunosuppression Strategies in Simultaneous Liver/Kidney Transplantation

BACKGROUND

There is scant data on the use of induction immunosuppression for simultaneous liver/kidney transplantation (SLKT).

METHODS

We analyzed the Organ Procurement and Transplant Network registry from 1996 to 2016 to compare outcomes of SLKT, based on induction immunosuppression.

RESULTS

Of 5172 patients, 941 (18%) received T-cell depletion induction, 1635 (32%) received interleukin 2 receptor antagonist (IL2-RA), and 2596 (50%) received no induction (NI). At 5 years, patient survivals were 68% in the T-cell group, 74% in the IL2-RA group, and 71% in the NI group (P = 0.0006). Five-year liver and kidney allograft survivals were 67% and 64% in the T-cell group, 73% and 70% in the IL2-RA group, and 70% and 68% in the NI group (P = 0.001 and 0.003), respectively. On multivariate analysis, the type of induction had no impact on patient or allograft survival. Maintenance steroids and calcineurin inhibitors (CNIs) at discharge were associated with improved patient and graft survival (steroids: patient survival hazard ratio [HR] 0.37 [0.27-0.52], liver survival HR 0.43 [0.31-0.59], kidney survival HR 0.46 [0.34-0.63]; P < 0.0001, CNI: patient survival HR 0.3 [0.21-0.43], liver survival HR 0.3 [0.2-0.44], kidney survival HR 0.4 [0.26-0.59]; P < 0.0001). CNI maintenance in patients who received T-cell induction was associated with decreased patient, liver, and kidney allograft survivals (respective HR: 1.4 [1.1, 1.8]; 1.5 [1.1, 1.9]; 1.3 [1.08, 1.7]; P < 0.05) CONCLUSION.: Induction immunosuppression had no impact on patient and allograft survival in SLKT, while maintenance steroids and CNI were associated with improved patient and graft survivals. Given the inherent limitations of a registry analysis, these findings should be interpreted with caution.

Sequential Versus Combined Heart-Liver Transplantation in the USA

INTRODUCTION

Combined heart-liver transplantation (CHLT) has resulted in acceptable survival rates compared to orthotopic liver transplantation (OLT) alone and orthotopic heart transplantation alone. Using the US transplant registry, we compared outcomes following sequential and combined HLT.

METHODS

We conducted a retrospective cohort study. De-identified data were obtained from the United Network Organ Sharing Registry. The primary outcome was patient survival from the date of OLT. Secondary outcomes included liver allograft survival and heart allograft survival.

RESULTS

The study cohort included 301 CHLT recipients and six sequential heart-liver transplantation (SHLT) recipients. Patient survival after CHLT was 88% at 1 year, 84% at 3 years, and 82% at 5 years compared to 83%, 67%, and 50% in the SHLT group (p = 0.010). Liver allograft survival at 1, 3, and 5 years was 88%,83% and 82%, respectively, in the CHLT group compared to 83% and 67%, and 50%, respectively, in the SHLT group (p = 0.009). After OLT, heart allograft survival at 1, 3, and 5 years was 86%, 79%, and 74% in the CHLT group, respectively, compared to 83%, 67%, and 50% in the SHLT group (p = 0.037).

CONCLUSIONS

Despite the limited size of the SHLT cohort, we found that CHLT was superior to SHLT in survival rate and graft survival. The better outcomes noted in CHLT may relate to immunoprotection provided by liver transplantation from the same donor.

Transplant Tolerance Induction: Insights From the Liver

A comparison of pre-clinical transplant models and of solid organs transplanted in routine clinical practice demonstrates that the liver is most amenable to the development of immunological tolerance. This phenomenon arises in the absence of stringent conditioning regimens that accompany published tolerizing protocols for other organs, particularly the kidney. The unique immunologic properties of the liver have assisted our understanding of the alloimmune response and how it can be manipulated to improve graft function and survival. This review will address important findings following liver transplantation in both animals and humans, and how these have driven the understanding and development of therapeutic immunosuppressive options. We will discuss the liver's unique system of immune and non-immune cells that regulate immunity, yet maintain effective responses to pathogens, as well as mechanisms of liver transplant tolerance in pre-clinical models and humans, including current immunosuppressive drug withdrawal trials and biomarkers of tolerance. In addition, we will address innovative therapeutic strategies, including mesenchymal stem cell, regulatory T cell, and regulatory dendritic cell therapy to promote liver allograft tolerance or minimization of immunosuppression in the clinic.

Significance of progressive liver fibrosis in pediatric liver transplants: A review of current evidence

This article reviews the current evidence and knowledge of progressive liver fibrosis after pediatric liver transplantation. This often-silent histologic finding is common in long-term survivors and may lead to allograft dysfunction in advanced stages. Surveillance through protocolized liver allograft biopsy remains the gold standard for diagnosis, and recent evidence suggests that chronic inflammation precedes fibrosis.

Kidney Graft Outcomes in High Immunological Risk Simultaneous Liver-Kidney Transplants

Recipients of simultaneous liver-kidney transplantations (SLKTs) have a lower risk of rejection compared with recipients of kidney transplants alone. However, there is disagreement about the impact of pretransplant anti-human leukocyte antigen sensitization on patient and kidney graft survival in the long term. The aim of the study was to evaluate the impact of the recipient immunological risk and comorbidities in renal graft outcomes on SLKT. We reviewed the SLKTs performed in our center from May 1993 until September 2017. Patient and graft survival were analyzed according to the immunological risk, comorbidities, liver and kidney rejection episodes, immunosuppression, and infections. A total of 20 recipients of SLKT were considered in the high immunological risk (HIR) group, and 68 recipients were included in the low immunological risk (LIR) control group. The prevalence of hepatitis C virus infection, second renal transplant, and time on dialysis prior to transplantation were significantly higher in the HIR group. The incidence of acute kidney rejection was higher in the HIR group (P<0.01). However, death-censored kidney graft survival as well as the estimated glomerular filtration rate at follow-up were not different between the 2 groups. Comorbidities, but not the immunological risk, impact negatively on patient survival. Despite the higher incidence of rejection in the HIR SLKT group, longterm renal function and graft survival were similar to the LIR group.

Phenotypic, Transcriptional, and Functional Analysis of Liver Mesenchymal Stromal Cells and Their Immunomodulatory Properties

The liver is an immunologically active organ with a tolerogenic microenvironment at a quiescent state. The immunoregulatory properties of the liver appear to be retained after transplantation because liver allografts can reduce alloresponses against other organs that are simultaneously transplanted. Mechanisms of this phenomenon remain unknown. Given the known immunomodulatory properties of mesenchymal stromal cells (MSCs), we hypothesized that liver mesenchymal stromal cells (L-MSCs) are superior immunomodulators and contribute to liver-mediated tolerance. L-MSCs, generated from human liver allograft biopsies, were compared with adipose mesenchymal stromal cells (A-MSCs) and bone marrow mesenchymal stromal cells (BM-MSCs). Trilineage differentiation of L-MSCs was confirmed by immunohistochemistry. Comparative phenotypic analyses were done by flow cytometry and transcriptome analyses by RNA sequencing in unaltered cell cultures. The in vitro functional analyses were performed using alloreactive T cell proliferation assays. The transcriptome analysis showed that the L-MSCs are different than the A-MSCs and BM-MSCs, with significant enrichment of genes and gene sets associated with immunoregulation. Compared with the others, L-MSCs were found to express higher cell surface levels of several select immunomodulatory molecules. L-MSCs (versus A-MSCs/BM-MSCs) inhibited alloreactive T cell proliferation (22.7% versus 56.4%/58.7%, respectively; P < 0.05) and reduced the frequency of interferon ɤ-producing T cells better than other MSCs (52.8% versus 94.4%/155.4%; P < 0.05). The antiproliferative impact of L-MSCs was not dependent on cell-to-cell contact, could be reversed incompletely by blocking programmed death ligand 1, and required a higher concentration of the competitive inhibitor of indoleamine 2,3-dioxygenase for complete reversal. In conclusion, L-MSCs appear to be uniquely well-equipped immunomodulatory cells, and they are more potent than A-MSCs and BM-MSCs in that capacity, which suggests that they may contribute to liver-induced systemic tolerance.

Living donor liver transplantation for congenital hepatic fibrosis in children

Congenital hepatic fibrosis (CHF) often accompanies autosomal recessive polycystic kidney disease (ARPKD), which stems from a PKHD1 gene mutation. The aim of this study was to clarify the prognosis of children with CHF who received living donor liver transplantation (LDLT) from donors who might be heterozygous carriers of a hepatorenal fibrocystic disease. Fourteen children with CHF who underwent LDLT at our center were enrolled. Eight and two patients had ARPKD and nephronophthisis, respectively. Eight of the donors were the recipients' fathers, and six donors were their mothers. We examined the histological and radiological findings of the donor livers and complications in the recipients following the liver transplantation. Seven of the donor livers presented morphological abnormalities of the bile ducts. Abdominal computed tomography revealed liver cysts in eight donors. One recipient underwent re-LT for graft failure due to rejection. Three patients presented with rejection, and one presented with sepsis. The overall survival rate was 100% and the original graft survival rate was 93%. In conclusion, the prognosis of recipients who received a LDLT from their parents for CHF was excellent. However, the morphology of half the donor livers was abnormal. Careful follow-up is needed to ensure long-term graft survival.