Immunosuppression with mTOR inhibitors prevents the development of donor-specific antibodies after liver transplant

Impact of very early introduction of everolimus on liver regeneration after partial liver transplantation in rats

BACKGROUND/PURPOSE

This experimental study in rats aimed to investigate the impact of very early introduction (within 3 h) of everolimus (EVR) + reduced-tacrolimus (TAC) after partial liver transplantation (LT) on liver regeneration, rejection, and survival.

METHODS

Based on appropriate dose of EVR + reduced-TAC in 70% hepatectomy (Experiment 1), allogeneic 30% partial LT (Experiment 2) and whole LT (Experiment 3) were performed.

RESULTS

After partial LT in EVR + reduced-TAC therapy, restoration of liver graft weight (to that of the whole liver) was delayed compared with standard dose TAC monotherapy (standard-TAC) on day 3 (59.3% vs. 72.9%; p < .001) and 14 (88.1% vs. 95.5%; p = .01). Survival was 75%, which was not as high as the value of 100% observed for standard-TAC, because neither infection nor rejection could be prevented. By contrast, survival after whole LT was 100% as neither infection nor rejection occurred.

CONCLUSIONS

The very early introduction of EVR + reduced-TAC after partial LT delayed liver regeneration, and made it difficult to manage the dose required to suppress both infection and rejection. On the other hand, EVR + reduced-TAC could be introduced safely very early after whole LT.

Donor-Specific Antibodies Against Donor Human Leukocyte Antigen are Associated with Graft Inflammation but Not with Fibrosis Long-Term After Liver Transplantation: An Analysis of Protocol Biopsies

Background

Donor-specific antibodies (DSA) against donor human leukocyte antigen after liver transplantation, which are associated with histological changes, have been widely studied with respect to their sustained impact on transplant function. However, their long-term impact after liver transplantation remains unclear.

Methods

We performed a cross-sectional analysis from June 2016 to July 2017 that included all patients who presented themselves for scheduled follow-up after receiving a liver transplantation between September 1989 and December 2016. In addition to a liver protocol biopsy, patients were screened for human leukocyte antigen antibodies (HLAab) and donor-specific antibodies. Subsequently, the association between human leukocyte antigen antibodies, donor-specific antibodies, histologic and clinical features, and immunosuppression was analyzed.

Results

Analysis for human leukocyte antigen antibodies and donor-specific antibodies against donor human leukocyte antigen was performed for 291 and 271 patients. A significant association between higher inflammation grades and the presence of human leukocyte antigen antibodies and donor-specific antibodies was detected, while fibrosis stages remained unaffected. These results were confirmed by multivariate logistic regression for inflammation showing a significant increase for presence of human leukocyte antigen antibodies and donor-specific antibodies (OR: 4.43; 95% CI: 1.67–12.6; p=0.0035). Furthermore, the use of everolimus in combination with tacrolimus was significantly associated with the status of negative human leukocyte antigen antibodies and donor-specific antibodies. Viral etiology for liver disease, hepatocellular carcinoma (HCC) and higher steatosis grades of the graft were significantly associated with a lower rate of human leukocyte antigen antibodies. The impact of human leukocyte antigen antibodies and donor-specific antibodies against donor human leukocyte antigen was associated with higher levels of laboratory parameters, such as transaminases and bilirubin.

Conclusion

Donor-specific antibodies against donor human leukocyte antigen are associated with histological and biochemical graft inflammation after liver transplantation, while fibrosis seems to be unaffected. Future studies should validate these findings for longer observation periods and specific subgroups.

Long-term outcomes and clinical impact of anti-HLA donor-specific antibodies (DSA) after liver transplantation: a prospective study in a pilot cohort

INTRODUCTION

the presence of donor-specific antibodies (DSA) is thought to affect survival of the allograft and patient after liver transplantation (LT). However, their significance is not well understood.

PATIENTS AND METHODS

a prospective study was performed of 32 adult patients who underwent LT in 2011 to analyze the existence of DSA, associated risk factors and medium-term impact. Immunological determinations were performed immediately before LT and at three, six, 12 months and five years after LT.

RESULTS

eight patients (24.2 %) presented pre-formed DSA. However, titers were negative in all patients five years after LT and there were no associated events. Eight out of 24 patients (33.3 %) developed de novo DSA. After five years, only two remained positive; both were class II with high mean fluorescence intensity (MFI) values at diagnosis (over 15,000). No association was found between the development of DSA and the risk of rejection, graft loss or death. However, an increase in liver stiffness values was observed in patients with persistent DSA, and focal sinusoidal deposition of C4d and moderate liver fibrosis were reported.

CONCLUSION

the incidence of DSA is high after LT. In addition, the persistence of de novo DSA could be associated with silent liver fibrosis with a potential impact on graft outcomes.

Non-invasive screening for subclinical liver graft injury in adults via donor-specific anti-HLA antibodies

The majority of liver grafts exhibit abnormal histological findings late after transplantation, even when liver enzymes are normal. Such subclinical graft injuries were associated with rejection and fibrosis progression in recent studies. The identification of non-invasive biomarkers for subclinical graft injury might help to individualize immunosuppression. Therefore, graft injury was assessed in 133 liver biopsies with normal/near normal liver enzymes from a prospective liver biopsy program. Cytokeratin-18 cell death marker (M65) and donor specific anti-HLA antibodies (DSA) were measured as non-invasive markers in paired plasma samples in addition to routine parameters. M65 was associated with subclinical graft injury but this association was too weak for reasonable clinical application. DSA positivity was associated with more graft inflammation (OR = 5.4) and more fibrosis (OR = 4.2). Absence of DSA excluded fibrosis in 87–89%, while presence of DSA excluded histological criteria for immunosuppression minimization attempts in 92–97%. While CK18 cell death marker had no diagnostic value for the detection of subclinical liver graft injury, DSA testing can help to preselect patients for immunosuppression reduction in case of DSA negativity, while DSA positivity should prompt elastography or liver biopsy for the assessment of subclinical graft injury.

HLA class II donor specific antibodies are associated with graft cirrhosis after liver transplant independent of the mean fluorescence intensity level

Background

The importance of donor-specific antibodies (DSA) after liver transplantation (LT) for graft and patient survival is an ongoing controversy. So far it has not been elucidated when and in how far DSA are harmful for graft and patient survival. Therefore, we had the aim to investigate the association of DSA with complications after LT.

Methods

Data of 430 LT recipients were collected and statistically analyzed. Detection of HLA antibodies (Ab) was performed by Luminex assay.

Results

DSA were detected in 81 patients (18.8%). These were mainly HLA class II Ab (81.5%). HLA class II Ab show a higher MFI (median: 5.300) compared to HLA class I Ab (median: 2.300). There is no association between MFI levels and development of complications after LT. However, cirrhosis occurred significantly more often in DSA positive patients (18%) than in patients without detectable DSA (9%, P = 0.027). All DSA positive patients with cirrhosis of the graft showed HLA class II antibodies (OR: 3.028; 95% CI: 1.51–6.075; P = 0.002).

Conclusion

Occurrence of HLA class II DSA after LT is associated with graft cirrhosis and may indicate a higher risk to develop graft damage independent on MFI and requires an individualized risk management.

The Effect of Immunosuppression on Coagulation After Liver Transplantation

Everolimus (EVR) is a mammalian target of rapamycin (mTOR) inhibitor commonly used for immunosuppression (IS) after liver transplantation (LT). However, there are concerns about whether mTOR inhibitors may move the hemostatic balance toward a higher likelihood of thrombosis. The present study aimed to investigate potential coagulation disorders after the administration of EVR. We evaluated 54 patients after conversion to an EVR-based IS regimen (n = 26) and compared those patients with patients who were switched to extended-release tacrolimus (TAC) but had never received EVR (n = 28). At baseline and again at 1 month and 6 months after conversion, we measured international normalized ratio, activated partial thromboplastin time, and anticoagulation and fibrinolysis factors, and we performed rotational thromboelastometry (ROTEM). Data were analyzed with a Mann-Whitney U test, a repeated-measure analysis of variance, and a Fisher's exact test. Statistical significance was set at the level of P ≤ 0.05. Plasma levels of von Willebrand factor, fibrinogen, and factor VIII were significantly higher than baseline levels at 1 month and 6 months after conversion of IS to EVR (P < 0.001); plasma levels of protein C, protein S, and plasminogen also increased significantly (P < 0.001). ROTEM confirmed a significant increase in maximum clot firmness in EXTEM, INTEM, and FIBTEM assays (P < 0.001). In all assays, maximum lysis was significantly lower than baseline levels at 1 month and 6 months after conversion to EVR. Patients converted to IS with extended-release TAC exhibited no significant changes in coagulation variables. Retrospective analysis showed a significantly higher incidence of thromboembolic complications among patients treated with EVR-based IS than among those treated with extended-release TAC (P < 0.01). In conclusion, the administration of EVR after LT seems to modify hemostasis to a procoagulant state. Thrombophilia screening before conversion may determine which patients will benefit from conversion to EVR-based IS.

Everolimus-based Immunosuppression Possibly Suppresses Mean Fluorescence Intensity Values of De Novo Donor-specific Antibodies After Primary Kidney Transplantation

PURPOSE

We evaluated de novo donor-specific antibody (DSA) production of everolimus (EVR)-based immunosuppression for primary kidney transplant recipients involved in the A1202 study at our institute.

METHODS

From March 2008 to August 2009, 24 recipients were prospectively randomized into 2 groups. The EVR group received reduced cyclosporin A and EVR. The standard protocol (STD) group received standard cyclosporin A and mycophenolate mofetil. Both groups received basiliximab and steroids. De novo DSA was identified using LABScreen single antigen beads (One Lambda, Canoga Park, Calif., United States). Mean fluorescence intensity (MFI) values > 1000 were considered positive. P < .05 was considered significant.

RESULTS

Graft survival was 100% in the EVR group and 90.9% in the STD group. All patients remained on the primary protocol in the EVR group, but 3 patients in the STD group (27.3%) were converted to tacrolimus due to DSA and non-adherence. Estimated glomerular filtration rate was similar in both groups. No EVR group recipients and 9.1% of STD group recipients were treated for T-cell-mediated rejection. No recipients of the EVR group exhibited peritubular capillaritis, while 9.1% in STD group developed chronic active antibody-mediated rejection. LABScreen revealed an accumulative class II DSA production rate of 15.4% in the EVR group and 18.3% in the STD group at 10 years. When the MFI cut-off level was set to 6000, anti-HLA antibody and de novo DSA-free survival was significantly better in the EVR group.

CONCLUSIONS

EVR-based immunosuppression provided equivalent or even better clinical outcomes. EVR suppressed de novo DSA production at 10 years follow-up; however, further follow-up is inevitable.

Targeting the mTOR regulatory network in hepatocellular carcinoma: Are we making headway?

The mechanistic target of rapamycin (mTOR) pathway coordinates organismal growth and homeostasis in response to growth factors, nutrients, and cellular energy stage. The pathway regulates several major cellular processes and is implicated in various pathological conditions, including hepatocellular carcinoma (HCC). This review summarizes recent advances of the mTOR pathway, highlights the potential of the mTOR pathway as a therapeutic target, and explores clinical trials targeting the mTOR pathway in HCC. Although the review focuses on the mTOR pathway involved in HCC, more comprehensive discussions (eg, developing a rational design for future trials targeting the mTOR pathway) are also applicable to other tumors.

Prevalence and Impact of Reformed and De Novo Anti-HLA Donor-Specific Antibodies in Liver Transplantation

INTRODUCTION

The prevalence and impact of pre-existing and de novo anti-HLA donor-specific antibodies (DSAs) after orthotopic liver transplantation (OLT) is still controversial. We investigated the prevalence of DSAs and their implication in the development of allograft dysfunction after OLT.

PATIENTS AND METHODS

A total of 65 liver transplant patients were tested for anti-HLA antibodies, with single antigen bead technology, before, 1, 3, 6, and 12 months after transplantation, and thereafter annually, along with other risk factors. Sixteen out of 65 patients (24.6%) had circulating pre-existing anti-HLA antibodies, and 4 of them (25%) had DSAs. All patients positive for anti-HLA antibodies (100%) presented allograft dysfunction. Fourteen out of 65 patients (21.5%) had circulating de novo DSAs, and 12 out of 14 (85.7%) presented allograft dysfunction. The investigated risk factors for allograft dysfunction were: recipient and donor age, time on the waiting list, cold ischemia time, cytomegalovirus infection, immunosuppression regimen, de novo DSAs, Model for End-Stage Liver Disease, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase (GGT), direct bilirubin and total bilirubin peak post-transplant, and alkaline phosphatase. The multivariate analysis showed that de novo DSAs and time on the waiting list were independent risk factors for allograft dysfunction.

CONCLUSION

Our results show that de novo DSAs are an independent risk factor for allograft dysfunction, along with time on the waiting list.

Ab initio Everolimus-based Versus Standard Calcineurin Inhibitor Immunosuppression Regimen in Liver Transplant Recipients

AIM

We designed a retrospective case-control study to determine the efficacy and feasibility of everolimus (EVR) combined with low-dose tacrolimus (Tac) ab initio versus standard-dose Tac after liver transplantation (LT).

METHODS

Seventy-one adult LT patients, receiving EVR and low-dose Tac without corticosteroids or induction therapy from postoperative day 1 (EVR group) were compared with a well-matched control group of 61 recipients treated with standard-dose Tac in association with antimetabolite.

RESULTS

Baseline characteristics for the two groups were comparable. The overall patient and graft survival rates were similar (P = .908). Liver function was stable during the follow-up. In the EVR group, biopsy-proven acute rejection occurred in two cases (2.8%), whereas chronic rejection occurred in one (1.4%). The EVR group experienced a better renal function already after 2 weeks (estimated glomerular filtration rate: 89.85 [36.46 to 115.3] mL/min/1.73 m2 vs. 68.77 [16.11 to 115.42] mL/min/1.73 m2; P = .013), which was also observed after a median time of 27 months (range, 0 to 82 months) from LT (estimated glomerular filtration rate: 80 [45 to 118.3] mL/min/1.73 m2 vs. 70.9 [45 to 88.4] mL/min/1.73 m2; P = .04). After a median time of 27 months, the EVR group showed lower incidence of arterial hypertension and insulin-dependent diabetes mellitus.

CONCLUSION

Ab initio EVR-based immunosuppression could be a valid option immediately after surgery in recipients at high-risk for post-LT renal impairment.