Importance of genetic polymorphisms in liver transplantation outcomes

CYP3A5 and POR gene polymorphisms as predictors of infection and graft rejection in post-liver transplant patients treated with tacrolimus - a cohort study

Liver transplantation is the only curative option for patients with advanced stages of liver disease, with tacrolimus used as the immunosuppressive drug of choice. Genetic variability can interfere with drug response, potentially leading to overexposure or underexposure. This study aims to investigate the association of CYP3A4 (rs2740574, rs2242480, rs35599367), CYP3A5 (rs776746, rs10264272), POR (rs1057868) and ABCB1 (rs1128503, rs2229109, rs9282564) gene polymorphisms with infection, acute rejection, and renal failure. The logistic regression model found an influence of CYP3A5 (rs776746) and POR28 (rs1057868) on the development of acute rejection after liver transplantation (p = 0.028). It also found an association between carriers of the variant allele of the POR*28 gene and infection.

Understanding immunological insights of liver transplantation: a practice for attaining operational tolerance

Liver transplantation has been at the forefront of medical research, with efforts concentrated on understanding the intricate cellular and molecular dynamics involved this complex procedure. This body of work has chronicled critical clinical advancements, identified challenges, and highlighted progressive improvements in surgical practices. These concerted efforts have significantly contributed to the evolution and enhancement of liver transplantation, elevating it to its current level of sophistication. A successful liver transplant now demands an integrated, multidisciplinary approach that includes not only expanding the donor pool from deceased to living donors but also embracing advances in surgical methods, efficiently managing post-transplant complications, and, importantly, achieving operational tolerance. The latter, operational tolerance, is a state wherein the recipient's immune system is coaxed into accepting the transplanted organ without the long-term use of immunosuppressive drugs, thereby minimizing potential side effects, and improving quality of life. Understanding the critical immune mechanisms that aim to prevent graft rejection is essential from an immunological perspective. This review aims to highlight the crucial areas of host versus graft immune responses, making a clear distinction between organs received from living and deceased donors. It examines how these immune responses, both innate and adaptive, are initiated and proposes the exploration of molecular docking sites as a strategy to curb unwanted immune reactions. Additionally, this review explores the promising potential of biomarkers in predicting graft rejection, and emphasizes the importance of achieving tolerance and the continuous quest for innovative strategies to enhance the success and longevity of liver transplants.

Thrombotic complications post liver transplantation: Etiology and management

Liver transplantation (LT) is the life saving therapeutic option for patients with acute and chronic end stage liver disease. This is a routine procedure with excellent outcomes in terms of patient survival and quality of life post LT. Orthotopic LT (OLT) patients require a critical care as they are prone to variety of post-operative vascular, cardiovascular, biliary, pulmonary and abdominal complications. Thrombotic complications (both arterial and venous) are not uncommon post liver transplant surgery. Such vascular problems lead to increased morbidity and mortality in both donor and graft recipient. Although thromboprophylaxis is recommended in general surgery patients, no such standards exist for liver transplant patients. Drastic advancements of surgical and anesthetic procedures have improvised survival rates of patients post OLT. Despite these, haemostatic imbalance leading to thrombotic events post OLT cause significant graft loss and morbidity and even lead to patient's death. Thus it is extremely important to understand pathophysiology of thrombosis in LT patients and shorten the timing of its diagnosis to avoid morbidity and mortality in both donor and graft recipient. Present review summarizes the current knowledge of vascular complications associated with LT to highlight their impact on short and long-term morbidity and mortality post LT. Also, present report discusses the lacunae existing in the literature regarding the risk factors leading to arterial and venous thrombosis in LT patients.

Effect of donor GSTM3 rs7483 genetic variant on tacrolimus elimination in the early period after liver transplantation

Purpose

Glutathione S-transferase mu (GSTM) belongs to the group of phase II drug-metabolizing enzymes, and the GSTM1 genetic variant has been reported to have a potential association with the metabolism of immunosuppressive drug after renal transplantation. The effect of donor and recipient GSTMs genetic variants on tacrolimus (Tac) metabolism was the focus of our investigation in this study.

Methods

A total of 203 liver transplant patients were recruited for the study. In the training set (n = 110), twenty-one SNPs in five genes (GSTM1-5) were genotyped by the drug-metabolizing enzymes and transporter (DMET) microarray. CYP3A5 rs776746 and GSTM3 rs7483 were genotyped using a Mass ARRAY platform in the validating set (n = 93).

Results

Tac C/D ratios of donor GSTM3 rs7483 AA carriers were significantly lower than those with the G allele at weeks 1, 2, 3 and 4 after liver transplantation (LT). Multivariate analysis was conducted on the training set and validating set, donor and recipient CYP3A5 rs776746, donor GSTM3 rs7483 and total bilirubin were identified as independent predictors of Tac C/D ratios in the early period after LT. Combining CYP3A5 rs776746 and donor GSTM3 rs7483 genotypes, Tac C/D ratios were observed to be increasingly lower with increasing numbers of alleles associated with fast metabolism. Moreover, the risk of a supratherapeutic C0 (Tac > 15 ug/L) was significantly higher for poor metabolizers than the other groups at week 1 after LT.

Conclusions

There was a significant association between the donor GSTM3 rs7483 genetic variant and Tac metabolism in the early period after LT. Genotype classification might have a better predictive ability of the initial Tac doses.

The Role of Vitamin D Metabolism Genes and Their Genomic Background in Shaping Cyclosporine A Dosage Parameters after Kidney Transplantation

Background: Kidney transplantation is followed by immunosuppressive therapy involving calcineurin inhibitors (CNIs) such as cyclosporin A. However, long-term high CNIs doses can lead to vitamin D deficiency, and genetic variations influencing vitamin D levels can indirectly impact the necessary CNIs dosage. This study investigates the impact of genetic variations of vitamin D binding protein (DBP) rs2282679 and CYP2R1 hydroxylase rs10741657 polymorphisms on the cyclosporin A dosage in kidney transplant recipients. Additional polymorphisims of genes that are predicted to influence the pharmacogenetic profile were included. Methods: Gene polymorphisms in 177 kidney transplant recipients were analyzed using data mining techniques, including the Random Forest algorithm and Classification and Regression Trees (C&RT). The relationship between the concentration/dose (C/D) ratio of cyclosporin A and genetic profiles was assessed to determine the predictive value of DBP rs2282679 and CYP2R1 rs10741657 polymorphisms. Results: Polymorphic variants of the DBP (rs2282679) demonstrated a strong predictive value for the cyclosporin A C/D ratio in post-kidney transplantation patients. By contrast, the CYP2R1 polymorphism (rs10741657) did not show predictive significance. Additionally, the immune response genes rs231775 CTLA4 and rs1800896 IL10 were identified as predictors of cyclosporin A response, though these did not result in statistically significant differences. Conclusions:DBP rs2282679 polymorphisms can significantly predict the cyclosporin A C/D ratio, potentially enhancing the accuracy of CNI dosing. This can help identify patient groups at risk of vitamin D deficiency, ultimately improving the management of kidney transplant recipients. Understanding these genetic influences allows for more personalized and effective treatment strategies, contributing to better long-term outcomes for patients.

Metabolic-Dysfunction-Associated Steatotic Liver Disease (MASLD) after Liver Transplantation: A Narrative Review of an Emerging Issue

The development of steatotic liver disease after liver transplant (LT) is widely described, and epidemiological data have revealed an increased incidence in recent times. Its evolution runs from simple steatosis to steatohepatitis and, in a small proportion of patients, to significant fibrosis and cirrhosis. Apparently, post-LT steatotic disease has no impact on the recipient's overall survival; however, a higher cardiovascular and malignancy burden has been reported. Many donors' and recipients' risk factors have been associated with this occurrence, although the recipient-related ones seem of greater impact. Particularly, pre- and post-LT metabolic alterations are strictly associated with steatotic graft disease, sharing common pathophysiologic mechanisms that converge on insulin resistance. Other relevant risk factors include genetic variants, sex, age, baseline liver diseases, and immunosuppressive drugs. Diagnostic evaluation relies on liver biopsy, although non-invasive methods are being increasingly used to detect and monitor both steatosis and fibrosis stages. Management requires a multifaceted approach focusing on lifestyle modifications, the optimization of immunosuppressive therapy, and the management of metabolic complications. This review aims to synthesize the current knowledge of post-LT steatotic liver disease, focusing on the recent definition of metabolic-dysfunction-associated steatotic liver disease (MASLD) and its metabolic and multisystemic concerns.

Effect of donor HSD17B13 genotype on patient survival after liver transplant: a retrospective cohort study

Background

Several genetic variants are associated with chronic liver disease. The role of these variants in outcomes after liver transplantation (LT) is uncertain. The aim of this study was to determine if donor genotype at risk-associated variants in PNPLA3 (rs738409 C>G, p.I148M) and HSD17B13 (rs72613567 T>TA; rs80182459, p.A192Lfs∗8) influences post-LT survival.

Methods

In this retrospective cohort study, data on 2346 adults who underwent first-time LT between January 1, 1999 and June 30, 2020 and who had donor DNA samples available at five large Transplant Immunology Laboratories in Texas, USA, were obtained from the United Network for Organ Sharing (UNOS). Duplicates, patients with insufficient donor DNA for genotyping, those who were <18 years of age at the time of transplant, had had a previous transplant or had missing genotype data were excluded. The primary outcomes were patient and graft survival after LT. The association between donor genotype and post-LT survival was examined using Kaplan-Meier method and multivariable-adjusted Cox proportional hazards models.

Findings

Median age of LT recipients was 57 [interquartile range (IQR), 50-62] years; 837 (35.7%) were women; 1362 (58.1%) White, 713 (30.4%) Hispanic, 182 (7.8%) Black/African-American. Median follow-up time was 3.95 years. Post-LT survival was not affected by donor PNPLA3 genotype but was significantly reduced among recipients of livers with two HSD17B13 loss-of-function (LoF) variants compared to those receiving livers with no HSD17B13 LoF alleles (unadjusted one-year survival: 82.6% vs 93.9%, P < 0.0001; five-year survival: 73.1% vs 82.9%, P = 0.0017; adjusted hazard ratio [HR], 2.25; 95% CI, 1.61-3.15 after adjustment for recipient age, sex, and self-reported ethnicity). Excess mortality was restricted to those receiving steroid induction immunosuppression (crude 90-day post-LT mortality, 9.3% [95% CI, 1.9%-16.1%] vs 1.9% [95% CI, 0.9%-2.9%] in recipients of livers with two vs no HSD17B13 LoF alleles, P = 0.0012; age, sex, and ethnicity-adjusted HR, 2.85; 95% CI, 1.72-4.71, P < 0.0001). No reduction was seen among patients who did not receive steroid induction (90-day mortality 3.1% [95% CI, 0%-7.3%] vs 2% [95% CI, 0.9%-3.1%], P = 0.65; adjusted HR, 1.17; 95% CI, 0.66-2.08, P = 0.60).

Interpretation

Donor HSD17B13 genotype adversely affects post-LT survival in patients receiving steroid induction. Additional studies are required to confirm this association.

Funding

The National Institutes of Health and American Society of Transplant Surgeons Collaborative Scientist Grant.

Donor and recipient polymorphisms of MAPK signaling pathway genes influence post-transplant liver function in Chinese liver transplant patients taking tacrolimus

Tacrolimus (TAC) is an immunosuppressive drug that is widely used for patients who underwent liver transplantation. In addition to inhibiting the action of calcineurin, TAC also exerts its immunosuppressive effects by interfering with mitogen activated protein kinase (MAPK) pathway. In this study, we investigated the impact of both recipient and donor genetic polymorphisms of MAPK kinase kinase (MAP3K) genes on clinical events in Han Chinese liver transplantation recipients taking TAC. Fifty-seven tag SNPs of 11 genes (MEKK1, MEKK2, MEKK4, MLK1, MLK3, ASK1, TAO1, TAO2, Tpl2, TAK1 and ZAK1) in the MAPK pathway were detected by MALDI-TOF MS assay in 175 TAC-treated liver transplant recipients. The associations of SNPs with incidence of acute rejection, TAC-induced acute nephrotoxicity, and post-transplantation liver and kidney function were explored using Kaplan-Meier survival analysis, Cox-proportional hazard model and linear mixed model, respectively. For the sites significantly associated with clinical events, the dual-luciferase reporter gene system was used to perform preliminary function verification. The results showed that (1) Donor-recipient combinational (D-R) MEKK1 rs62355944 and D-R MLK1 rs8006424 genotypes were significant influence factors of post-transplantation γ-glutamyl transpeptidase (GGT) level (P < 0.0001); (2) D-R MLK1 rs8006424 genotypes were found to significantly affect the alkaline phosphatase (ALP) level after transplantation (P < 0.0001). The results of the dual luciferase reporter gene system demonstrated that the luciferase activity of the pGL3-rs8006424A was significantly higher than that of pGL3-rs8006424G (3.47 ± 0.10 vs 2.97 ± 0.08, P = 0.002). Therefore, MEKK1 rs62355944 and MLK1 rs8006424 might serve as biomarkers to predict post-transplant liver function in liver transplant patients.

Impact of genetic polymorphisms on tacrolimus trough blood concentration in Chinese liver transplant recipients

Purpose: The aim of this study was to analyze the effects of various genetic polymorphisms and clinical factors on tacrolimus (TAC) concentration in the convalescence period (CP) and stabilization period (SP) post-liver transplantation. Patients & methods: A total of 13 SNPs were genotyped in 97 Chinese liver transplant recipients. Associations between SNPs and TAC trough blood concentration/dose ratio (C₀/D) were analyzed using different genetic models in both CP and SP. Results: Only five SNPs were significantly associated with TAC log (C₀/D) in the CP, and none showed a significant association in the SP. We identified rs15524 (CYP3A5), rs9200 (C6), albumin and creatinine as independent predictors of TAC C₀/D in the CP. Furthermore, a final model in the CP explained a total of 30.5% TAC variation. Conclusion: Our study results suggest that in the early stages post-transplantation surgery, recipients' genetic and clinical factors exert a short-term impact on TAC metabolism that gradually decreases with time.

Pharmacokinetic and pharmacodynamic considerations of antibiotics and antifungals in liver transplantation recipients

The liver plays a major role in drug metabolism. Liver transplantation impacts the intrinsic metabolic capability and extrahepatic mechanisms of drug disposition and elimination. Different levels of inflammation and oxidative stress during transplantation, the process of liver regeneration, and the characteristics of the graft alter the amount of functional hepatocytes and activity of liver enzymes. Binding of drugs to plasma proteins is affected by the hyperbilirubinemia status and abnormal synthesis of albumin and alpha-1-acid glycoproteins. Postoperative intensive care complications such as biliary, circulatory, and cardiac also impact drug distribution. Renally eliminated antimicrobials commonly present reduced clearance due to hepatorenal syndrome and the use of nephrotoxic immunosuppressants. In addition, liver transplantation recipients are particularly susceptible to multidrug-resistant infections due to frequent manipulation, multiple hospitalizations, invasive devices, and frequent use of empiric broad-spectrum therapy. The selection of appropriate anti-infective therapy must consider the pathophysiological changes after transplantation that impact the pharmacokinetics and pharmacodynamics of antibiotics and antifungal drugs.

Recent Progress and Future Direction for the Application of Multiomics Data in Clinical Liver Transplantation

Omics data address key issues in liver transplantation (LT) as the most effective therapeutic means for end-stage liver disease. The purpose of this study was to review the current application and future direction for omics in LT. We reviewed the use of multiomics to elucidate the pathogenesis leading to LT and prognostication. Future directions with respect to the use of omics in LT are also described based on perspectives of surgeons with experience in omics. Significant molecules were identified and summarized based on omics, with a focus on post-transplant liver fibrosis, early allograft dysfunction, tumor recurrence, and graft failure. We emphasized the importance omics for clinicians who perform LTs and prioritized the directions that should be established. We also outlined the ideal workflow for omics in LT. In step with advances in technology, the quality of omics data can be guaranteed using an improved algorithm at a lower price. Concerns should be addressed on the translational value of omics for better therapeutic effects in patients undergoing LT.

Genetic and Life Style Risk Factors for Recurrent Non-alcoholic Fatty Liver Disease Following Liver Transplantation

Recurrent or de novo non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) following liver transplantation (LT) is a frequent event being increasingly recognized over the last decade, but the influence of recurrent NASH on graft and patient outcomes is not yet established. Taking into consideration the long term survival of liver transplanted patients and long term complications with associated morbidity and mortality, it is important to define and minimize risk factors for recurrent NAFLD/NASH. Metabolic syndrome, obesity, dyslipidemia, diabetes mellitus are life style risk factors that can be potentially modified by various interventions and thus, decrease the risk of recurrent NAFLD/NASH. On the other hand, genetic factors like recipient and/or donor PNPLA3, TM6SF2, GCKR, MBOAT7 or ADIPOQ gene polymorphisms proved to be risk factors for recurrent NASH. Personalized interventions to influence the different metabolic disorders occurring after LT in order to minimize the risks, as well as genetic screening of donors and recipients should be performed pre-LT in order to achieve diagnosis and treatment as early as possible.

Evaluation of seven gene signature for predicting HCV recurrence post-liver transplantation

BACKGROUND

Orthotropic liver transplantation (OLT) offers a therapeutic choice for hepatocellular carcinoma (HCC) patients. The poor outcome of liver transplantation is HCV recurrence. Several genome-wide associated studies (GWAS) have reported many genetic variants to be associated with HCV recurrence. Seven gene polymorphisms formed a cirrhosis risk score (CRS) signature that could be used to distinguish chronic HCV patients at high risk from those at low risk for cirrhosis in non-transplant patients. This study aims to examine the association of CRS score and other clinical parameters with the probability for HCC emergence and/or the rate of HCV recurrence following liver transplantation.

RESULTS

Seven gene polymorphisms, forming the CRS, were genotyped by real-time PCR using allelic discrimination protocol in 199 end-stage liver disease patients (79 child A, 43 child B, and 77child C), comprising 106 patients who encountered liver transplantation. Recipient CRS scores were correlated with HCV recurrence (HCV-Rec) at the end of the third year after OLT. Around 81% (39) recipients with low steatosis (LS; < 3.5%) donor percentage revealed no HCV recurrence (non-Rec) (p<0.001). CRS score could distinguish between child A, child B, and child C only at the low-risk group. Among the HCV Rec group 27% (8/30), 40% (12/30), and 33% (10/30) fell into the high, moderate, and low CRS risk groups, respectively. Stepwise logistic regression evinced two features more likely to be seen in HCV-Rec patients: abnormal ALT [OR, 1.1; 95% CI, 1.02-1.2] and donor steatosis >3.5% [OR, 46.07; 95% CI, 1.5-1407.8].

CONCLUSIONS

Accordingly, the CRS score seems to be less useful to predict HCV recurrence after OLT. ALT and donor steatosis (exceed 3.5%) can significantly promote the HCV recurrence post-OLT. Moreover, the combination of MMF and CNI positively heightens HCV recurrence.

A Time-Based Meta-Analysis on the Incidence of New Onset Diabetes after Liver Transplantation

NODAT (new-onset diabetes after transplantation) is an important complication after liver transplant, however, there is variation in the reported incidence of NODAT. Therefore, a meta-analysis was performed to estimate the incidence of NODAT in liver transplant. Electronic databases were searched for articles regarding NODAT incidence after liver transplantation. Incidence of NODAT were analyzed at six different timepoints. Summary statistics were calculated using a generalized linear mixed model in random effects. 28 articles were included and out of a pooled population of 71,257 patients, overall incidence of NODAT was found to be 15.51%, 16.09%, 18.30%, 20.86%, 18.08%, 25.05% for three-months, six-months, one-year, three-year, five-year, and ten-year timepoints respectively. After a sensitivity analysis which only included articles with clear definitions of NODAT, the incidence of NODAT was found to be higher at three-year (21.79%), five-year (25.82%), and ten-year (44.95%) timepoints. Subgroup analysis according to ethnicity found no significant differences for all timepoints. However, studies with predominantly Asian participants generally had a higher incidence of NODAT. In conclusion, this meta-analysis provides a pooled estimate of the incidence of NODAT following liver transplantation. Further studies are required to provide a more comprehensive understanding on how ethnicity can affect the incidence of NODAT.

The influence of recipient SLCO1B1 rs2291075 polymorphism on tacrolimus dose-corrected trough concentration in the early period after liver transplantation

Purpose

To explore the relationship between rs2291075 polymorphism in SLCO1B1 gene, which encodes an influx transmembrane protein transporter, and tacrolimus dose–corrected trough concentration (C/D, ng ml⁻¹ mg⁻¹ kg⁻¹) in the early period after liver transplantation.

Methods

CYP3A5 rs776746 and SLCO1B1 rs2291075 polymorphisms of 210 liver transplantation patients and their corresponding donor livers were assessed by PCR amplification and DNA sequencing. The influence of gene polymorphisms on C/D values of tacrolimus was analyzed. The early postoperative period after liver transplantation was divided into the convalescence phase (1–14 days) and stationary phase (15–28 days) according to the change of liver function and tacrolimus C/D values.

Results

The combined analysis of donor and recipient CYP3A5 rs776746 could distinguish the metabolic phenotype of tacrolimus into three groups: fast elimination (FE), intermediate elimination (IE), and slow elimination (SE), which was entitled the FIS classification system. Tacrolimus C/D ratios of recipient SLCO1B1 rs2291075 CT and TT carriers were very close and were significantly lower than those of recipient SLCO1B1 rs2291075 CC genotype carriers in convalescence phase (p = 0.0195) and in stationary phase (p = 0.0152). There were no statistically significant differences between tacrolimus C/D ratios of patients carried with SLCO1B1 rs2291075 CT, TT genotype donors, and those carried with SLCO1B1 rs2291075 CC genotype donors. A model consisting of tacrolimus daily dose, total bilirubin, FIS classification, and recipient SLCO1B1 rs2291075 could predict tacrolimus C/D ratios in the convalescence phase by multivariate analysis. However, recipient SLCO1B1 rs2291075 genotype failed to enter forecast model for C/D ratios in stationary phase. Recipient SLCO1B1 rs2291075 genotype had significant effect on tacrolimus C/D ratios in convalescence phase (p = 0.0300) and stationary phase (p = 0.0400) in subgroup, which excluded the interference come from donor and recipient CYP3A5 rs776746.

Conclusion

SLCO1B1 rs2291075 could be a novel genetic locus associated with tacrolimus metabolism. The combined analysis of donor and recipient CYP3A5 rs776746, recipient SLCO1B1 rs2291075 genotypes, could be helpful to guide the personalized administration of tacrolimus in early period after liver transplantation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00228-020-03058-w.