Homogenous phenomenon of graft liver CYP2C19 genotypes after living donor liver transplantation

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.

Liver Graft Pathology and Low Serum 25-Hydroxyvitamin D after Living Donor Liver Transplantation

BACKGROUND

Most cases of advanced liver diseases are associated with low serum 25-hydroxyvitamin D and vitamin D deficiency. This phenomenon may occur in living donor liver transplantation (LDLT).

AIMS

We conducted this study to explore the interplay between VDR and CYP2R1 in liver graft and compared our findings with the pathological interpretation of serum 25(OH)D concentration.

METHODS

In total, 60 patients received liver graft biopsy after LDLT and were separated (1:1) into two groups: graft rejection group and graft non-rejection group. We extracted both of the recipients' and donors' serum DNA to investigate the vitamin D receptor (VDR) rs2228530 and CYP2R1 rs10741657 single nucleotide polymorphisms (SNPs) using real-time polymerase chain reaction. We also extracted DNA from liver graft tissues to explore the genetic alleles of VDR rs2228530 and CYP2R1 rs10741657 after LDLT. Serum biochemistry profile and 25(OH)D concentrations were measured before and after LDLT.

RESULTS

There were no significant differences in serum VDR rs2228530 and CYP2R1 rs10741657 genetic alleles between recipients and donors. The percentage of genetic modification was 33.4% (10/30) for the rejection and non-rejection groups in VDR rs2228530, and 66.7% (20/30) for both groups in CYP2R1 rs10741657. Serum 25(OH)D concentrations were significantly lower after LDLT D30 than that before LDLT in the rejection (p = 0.0001) and non-rejection graft pathology (p = 0.0017) groups.

CONCLUSIONS

The presence of low serum 25(OH)D concentrations after LDLT suggested that post-transplant low serum 25(OH)D concentrations may develop with the homogenous phenomenon of VDR rs2228530 and CYP2R1 rs10741657 genetic modifications in recipients regardless of graft pathology.

Genetic polymorphisms of the hepatic pathways of fatty liver disease after living donor liver transplantation

BACKGROUND & AIMS

Fatty liver disease is an important complication associated with liver transplantation, and the cytochrome P-450 system of the donor liver may be involved in its pathogenesis. To explore the effects of the CYP27A1, CYP27B1, CYP2R1, and vitamin D receptor pathways on vitamin D maintenance after living donor liver transplantation, we investigated the interplay between serum 25(OH)D and common variants in 60 paired donors and recipients who underwent living donor liver transplantation.

METHODS

We prospectively collected 60 donor/recipient pairs from our liver transplantation programmes and extracted serum DNA to evaluate single nucleotide polymorphisms in CYP27A1 rs4674344, CYP27B1 rs10877012, CYP2R1 rs10741657, and VDR rs2228530 alleles using real-time polymerase chain reaction. We measured serum 25(OH)D concentrations of donors (D-D0) and recipients before (R-D0) and after (R-D30) living donor liver transplantation for comparison with repeated-measures analysis of variance in generalized estimating equations analysis.

RESULTS

Fatty liver disease was noted in 28.3% of the cases after living donor liver transplantation, and the graft rejection rate was 25%. There were significant differences in low serum 25(OH)D concentrations between D-D0 and R-D0 and between R-D0 and R-30 groups. Significant associations were observed for serum CYP27A1 rs4674344 in recipients and donors as well as for graft liver tissue with VDR rs2228530. There was no significant relationship with serum CYP27B1 rs10877012 in recipients and donors or with graft liver tissue with CYP2R1 rs10741657.

CONCLUSIONS

Donor/recipient CYP27A1 rs4674344 and graft VDR rs2228570 may be related to low serum 25(OH)D and may play a major role in the development of fatty liver disease in recipients after living donor liver transplantation.

Association between Subclinical Low Serum 25(OH)D in Donors and Fatty Liver Disease in Recipients after Living Donor Liver Transplantation

To explore subclinical fatty liver disease (FLD) in donors as a possible mechanism leading to FLD in recipients of living donor liver transplantation (LDLT), we extracted thirty donor-recipient pairs' serum DNA and explored the presence of CYP2R1 single nucleotide polymorphism (SNP) rs10741657 and vitamin D receptor (VDR) SNP rs2228530 A/G alleles using real-time polymerase chain reaction. We measured the serum 25(OH)D concentrations and investigated the CYP2R1 and VDR genotypes of the donors and recipients before and after LDLT for comparison with the histological findings from the donors on wedge biopsy, the recipients' removed native liver, and selective liver biopsy after LDLT. There was a significant difference in low serum 25(OH)D concentration between the donors and recipients before LDLT and in the recipients before versus after LDLT (13.90 ± 8.85 versus 47.9 ± 14.88 versus 11.82 ± 10.36, P < 0.001), and significant difference in FLD was detected on wedge biopsy from the donors and the native liver from the recipients as well as the native liver and follow-up biopsy from the recipients (P < 0.001). CYP2R1 and VDR genotype were predominant, both for the AG and for the GG alleles. For the donor VDR SNP rs2228570, low serum 25(OH)D was significantly different between genotypes AA and AG (P = 0.024) as well as between genotypes AA and AG plus GG (P = 0.042). Our data suggest that donors' VDR rs2228570 AA alleles may play a major role in low serum 25(OH)D regarding pathological FLD in recipients after LDLT.

Observational Study of Associations between Voriconazole Therapeutic Drug Monitoring, Toxicity, and Outcome in Liver Transplant Patients

The aim of this study was to investigate the variability of the voriconazole plasma level and its relationships with clinical outcomes and adverse events among liver transplant recipients to optimize the efficacy and safety of their treatment. Liver transplant recipients treated with voriconazole were included, and voriconazole trough levels were quantified by a validated high-performance liquid chromatography method. Cytochrome P450 genotypes for CYP2C19 were evaluated in allograft liver tissues. A total of 832 voriconazole trough levels from 104 patients were measured. Proven, probable, and possible invasive fungal infections were reported for 8/104 (7.7%), 42/104 (40.4%), and 54/104 (51.9%) patients, respectively. Receiver operating characteristic (ROC) curve analysis indicated that trough concentrations of ≥1.3 μg/ml minimized the incidence of treatment failure (95% confidence interval [CI], 0.68 to 0.91 μg/ml) (P < 0.001) and that those of <5.3 μg/ml minimized the incidence of any adverse events (95% CI, 0.83 to 0.97 μg/ml) (P < 0.001). Voriconazole trough levels were significantly higher for heterozygous extensive metabolizers, poor metabolizers, and individuals receiving coadministration with proton pump inhibitors. For ultrarapid metabolizers, oral administration of voriconazole, and concomitant use of glucocorticoids, voriconazole blood concentrations were significantly reduced. Furthermore, there was no statistically significant association of patient age, weight, or gender or coadministration of tacrolimus and cyclosporine with the voriconazole trough level. In conclusion, the results of our analysis indicate large inter- and intraindividual variabilities of voriconazole concentrations in liver transplant recipients. Voriconazole trough concentrations of ≥1.3 μg/ml and <5.3 μg/ml are optimal for treatment and for minimization of adverse events. Optimization of drug efficacy and safety requires the use of rational doses for voriconazole therapy.

Association of IL28B SNPs rs12979860 and rs8099917 on Hepatitis C Virus-RNA Status in Donors/Recipients of Living Donor Liver Transplantation

To investigate the effect of IL28B single nucleotide polymorphisms (SNPs) (rs8099917 and rs12979860) in the donors and recipients on the outcome of Hepatitis C virus-RNA clearance after living donor liver transplantation (LDLT). The rs8099917 and rs12979860 genotypes in 50 donor and recipients pairs were explored on the pre-operative day (POD) and post-operative day 30 (POD30). There was a significant difference in HCV-RNA clearance before (12%, 6/50) and after (48%, 24/50) liver transplantation (P < 0.001). The rs8099917 genotype TT was dominant in both the recipients (82%, 41/50) and donors (86%, 43/50), but had no significant effect on HCV-RNA clearance (87.5%, 21/24) and recurrence (76.9%, 20/26) after LDLT. One recipient was detected with genotype GG on POD, which changed to genotype GT on POD30. Prevalence of rs12979860 genotype CT was 98% (49/50 recipient) and 92% (46/50 donor) and prevalence of genotype CC was 2% (1/50 recipient) and 8% (4/50 donor) on POD and POD30, respectively. Of the 4 recipients with rs12979860 genotype CC on POD30, 3 recipients (12.5%, 3/24) exhibited HCV clearance and 1 experienced recurrence (3.9%, 1/26), however, this was not statistically significant. In conclusion, alterations in IL28B SNP genotype may occur after LDLT, leading to modifications in the host genome or donor proteome by HCV. This predicted mechanism will need to be investigated further.

Pharmacokinetics of drugs in adult living donor liver transplant patients: regulatory factors and observations based on studies in animals and humans

INTRODUCTION

Limited information is available on the pharmacokinetics of drugs in the donors and recipients following adult living donor liver transplantation (LDLT). Given that both the donors and recipients receive multiple drug therapies, it is important to assess the pharmacokinetics of drugs used in these patients.

AREAS COVERED

Pathophysiological changes that occur post-surgery and regulatory factors that may influence pharmacokinetics of drugs, especially hepatic drug metabolism and transport in both LDLT donors and the recipients are discussed. Pharmacokinetic data in animals with partial hepatectomy are presented. Clinical pharmacokinetic data of certain drugs in LDLT recipients are further reviewed.

EXPERT OPINION

It takes up to six months for the liver volume to return to normal after LDLT surgery. In the LDLT recipients, drug exposure generally is higher with lower clearance during early period post-transplant; lower initial dosages of immunosuppressants are used than deceased donor liver transplant recipients during the first six months post-transplantation. In animals, the activities of hepatic drug metabolizing enzymes and transporters are known to be altered differentially during liver regeneration. Future studies on the actual hepatic function with reference to drug metabolism, drug transport, and biliary secretion in both LDLT donors and recipients are required.

Repeated-measures implication of hepatocellular carcinoma biomarkers in living donor liver transplantation

Objective

Hepatocellular carcinoma (HCC) and its recurrence are major problems in living donor liver transplantation (LDLT). Several biomarkers have been used to investigate this event. We conducted a prospective controlled study to determine the activities of the basic fibroblast growth factor (FGF-2), survivin, Ki67, endostatin, and vascular endothelial growth factor (VEGF) in different conditions before, early after, and late after LDLT with and without HCC recurrence.

Methods

Fifty patients with virus-related HCC who underwent LDLT were enrolled in this 2-year cross-sectional study. During the study period, recurrent HCC was identified in 9 patients (study group, n = 9) and 41 patients (control group, n = 41) had no recurrence after LDLT. The mean time to HCC recurrence was 587.11 ± 398.64 days (range, 90–1352 days). Microvascular invasion (MVI) was found in 66.7% (6/9) of the recipients, as determined on pathological examination. The serum biomarkers were investigated by using enzyme-linked immunosorbent assay at the different LDLT stages.

Results

The serum levels of the biomarkers significantly correlated with LDLT and HCC recurrence in the repeated-measures analysis (F = 31.676, P = 0.000). Significant differences were observed in the effects of all biomarkers (F = 85.313, P = 0.000) and the time to HCC recurrence after LDLT (F = 3.178, P = 0.046). The biomarkers, ordered by the observed power of the test for HCC recurrence after LDLT, were FGF-2 (1.000) > survivin (0.999) > Ki67 (0.949) > endostatin (0.411) > VEGF (0.305).

Conclusions

Different biomarker activities may be implicated in the pathogenesis of HCC recurrence after LDLT. Oncogenes may not exist in the new graft but may still be present in the peripheral blood. The timing of HCC recurrence and impact of MVI in the explanted liver requires confirmation in larger studies with a longer follow-up.

Cytochrome P450 in living donor liver transplantation

Cytochrome P450 metabolizes many drugs in the liver. Three genotypes of CYP2C19 with extensive, intermediate, and poor metabolizing activity, respectively, have been identified in peripheral blood of transplant recipients and new liver grafts in living donor liver transplantation (LDLT). The expression of the final genotype in liver graft biopsies depends on the donor, whereas the expression in peripheral blood mononuclear cells depends on the recipient. The metabolizing isoenzyme of the major anti-rejection agents passes through CYP3A4, CYP3A5 and MDR1, which have also been identified to have similar biological characteristics as genotype of CYP2C19 in liver tissue. Recently, pyrosequencing has been used to investigate the expressions of different genotypes in liver grafts in LDLT. This review focuses on recent findings regarding the biological expressions of the CYP2C19, CYP3A4, CYP3A5 and MRD1 genotypes in liver grafts before and after LDLT. The application of pyrosequencing may be beneficial in further research on liver transplantation. Laser capture microdissection of hepatocytes in liver grafts may be a direction for future research.

Expression of P450 and nuclear receptors in normal and end-stage Chinese livers

AIM: To investigate the expression of P450 enzyme genes by using end-stage liver disease samples and trimmed normal Chinese donor livers.

METHODS: The end-stage liver disease samples [n = 93, including hepatocellular carcinoma (HCC), peri-HCC tissue, hepatitis B virus cirrhosis, alcoholic cirrhosis, and severe cirrhosis] and trimmed normal Chinese donor livers (n = 35) from The Institute of Organ Transplantation in Beijing, China. Total RNA was extracted, purified, and subjected to real-time RT-PCR analysis.

RESULTS: For cytochrome P450 enzymes 1 (CYP1) family, the expression of CYP1A2 was decreased 90% in HCC, 80% in alcoholic cirrhosis, and 65% in severe cirrhosis. For CYP2 family, the expression of CAR was decreased 50% in HCC, but increased 50% in peri-HCC tissues. Similar decreases (about 50%) of CYP2B6, CYP2C9, CYP2C19, CYP2D6 and CYP2E1 were observed in HCC, as compared to peri-HCC tissues and normal livers. CYP2C19 were decreased in all end-stage liver diseases and CYP2E1 also decreased in alcoholic cirrhosis and severe cirrhosis. For CYP3 family, the expression of PXR was decreased 60% in HCC, together with decreases in CYP3A4, CYP3A5, and CYP3A7. In contrast, the expression of CYP3A7 was slightly increased in HBV cirrhosis. The expression of CYP4A11 was decreased 85% in HCC, 7% in alcoholic cirrhosis and severe liver cirrhosis, along with decreases in PPARα. The 93 end-stage livers had much higher inter-individual variations in gene expression than 35 normal livers.

CONCLUSION: The expression of CYP enzyme genes and corresponding nuclear receptors was generally decreased in end-stage liver diseases, and significant differences in gene expression were evident between peri-HCC and HCC.

Homogeneous phenomenon of the graft when using different genotype characteristic of recipients/donors in living donor liver transplantation

AIM: To investigate the evidence of homogeneous phenomenon on CYP3A5*3 MDR1-3435 and CYP3A4*18 of the liver graft after living donor liver transplantation (LDLT).

METHODS: We identified the proportional change of the CYP3A5*3, MDR1-3435 and CYP3A4*18 from the peripheral blood mononuclear cell of 41 pairs recipient/donor with different genotype polymorphisms and 119 liver graft biopsy samples used with the pyrosequencing technique after LDLT. Polymerase chain reaction/ligase detection reaction assay and restriction fragment length polymorphism was employed for genotyping the CYP3A5*3 and CYP3A4*18 single nucleotide polymorphisms (SNPs). All of the recipients and donors expressed with the similar SNP genotype of CYP3A5*3, MDR1-3435 or CYP3A4*18 were excluded.

RESULTS: The final genetic polymorphisms of the liver graft biopsy samples of CYP3A5*3, MDR1-3435 and CYP3A4*18 was predominated depends on the donor with restriction fragment length polymorphism and seems to be less related to the recipient. The proportional changes of G to A alleles of the 119 samples of CYP3A5*3 (included A > A/G, A/G > A, A/G > G, G > A, G > A/G and A > G), C to T alleles of the 108 samples of MDR1-3435 (included C > C/T, C/T > C, C/T > T, T > C/T and T > C), and T to C alleles of 15 samples of CYP3A4*18 (included T/C > T and T > C/T) were significant different between the recipients and the liver graft biopsy samples (P < 0.0001) and less difference when compared with the donors in the pyrosequencing analysis after LDLT.

CONCLUSION: The CYP3A5*3, MDR1-3435 and CYP3A4*18 of the recipient could be modified by the donor so-called homogenous phenomenon when the recipient’s blood drained into the liver graft.

Pyrosequencing to identify homogeneous phenomenon when using recipients/donors with different CYP3A5*3 genotypes in living donor liver transplantation

This study used pyrosequencing to determine the proportional distribution of CYP3A5*3 genotypes to further confirm the homogeneous phenomenon that is observed when recipients and donors in living donor liver transplantation (LDLT) have a different single nucleotide polymorphism (SNP) genotype. We enrolled 42 recipient/living donor pairs and the SNPs of CYP3A5*3 were identified by polymerase chain reaction-restriction fragment length polymorphism. We performed 120 liver graft biopsies as part of clinical investigations after LDLT. Pyrosequencing of the CYP3A5*3 SNPs revealed that among the 16 recipients with the G/G genotype, 94.68% had the G and 5.32% the A allele. Among the 14 recipients with the A/G genotype, 78.08% had the G and 21.92% the A allele, and among the 12 recipients with the A/A genotype, 18.45% had the G and 81.55% the A allele. Among the 12 donors with the G/G genotype, 93.85% had the G and 6.14% the A allele. Among the 26 donors with the A/G genotype, 75.73% had the G and 24.27% the A allele, and among the 4 donors with the A/A genotype, 11.09% had the G and 88.91% the A allele. There were a total of 120 liver graft biopsy samples; among the 37 recipients with the G/G genotype, 89.74% had the G and 10.26% the A allele, among the 70 recipients with the A/G genotype, 71.57% had the G and 28.43% the A allele, and among the 13 recipients with the A/A genotype, 48.25% had the G and 51.75% the A allele. The proportional distribution of G and A alleles of the CYP3A5*3 SNP between recipients/donors and liver grafts after LDLT was significantly different (p<0.001). Pyrosequencing was useful in identifying detailed proportional changes of the CYP3A5*3 SNP allele distribution, and to confirm the homogeneous phenomenon when recipients and donors in LDLT have a different genotype.

Biological interactions of CYP2C19 genotypes with CYP3A4*18, CYP3A5*3, and MDR1-3435 in living donor liver transplantation recipients

Background

Polymorphisms in CYP2C19 are related to the metabolic oxidation of drugs to varying degrees. The CYP3A4*18, CYP3A5*3, and MDR1-3435 variant alleles are very important, particularly in tacrolimus metabolism in organ transplant rejection.

Aim

The aim of this study is o explore possible interactions among different CYP2C19 genotypes, namely, between homozygous extensive metabolizers (HomEM), heterozygous extensive metabolizers (HetEM), and poor metabolizers (PM), and the CYP3A4*18, CYP3A5*3, and MDR1-3435 variants in living donors and patients who received a living donor liver transplant (LDLT).

Methods

This prospective study enrolled 133 living donors and 133 corresponding recipients. On the basis of the HomEM, HetEM, and PM CYP2C19 genotypes, the distributions of CYP3A4*18 (exon 10; T878C), CYP3A5*3 (intron 3; A6986G), and MDR1-3435 (exon 26; C3435T) genotypes were analyzed for single nucleotide polymorphisms among donors and recipients.

Results

Among 102 HomEM genotypes, including 56 donors and 46 recipients, 91.2% of individuals harbored the T/T genotype of CYP3A4*18; 53.9% possessed G/G, and 34.3% had A/G genotypes of CYP3A5*3; and 38.2% had C/C and 50.0% had C/T genotypes at MDR1-3435. Among 130 HetEM genotypes, including 58 donors and 72 recipients, 97.7% of individuals possessed T/T genotype at CYP3A4*18; 50.0% harbored G/G and 41.5% had A/G genotypes at CYP3A5*3; and 40.0% had C/C and 49.2% had C/T genotypes at MDR1-3435. In 34 PMs, including 19 donors and 15 recipients, 88.2% had T/T genotypes at CYP3A4*18; 41.2% had G/G and 58.8% had A/G genotypes at CYP3A5*3; and 47.1% possessed C/C and 47.1% had C/T genotypes at MDR1-3435. On the basis of the CYP2C19 genotypes, no statistically significant distribution of genotypes were observed between donors and recipients for all genotypes of CYP3A4*18, CYP3A5*3, and MDR1-3435 (P >0.05).

Conclusions

In conclusion, the CYP2C19 genotypes do not affect the expression of CYP3A4*18, CYP3A5*3, or MDR1-3435 variants, which are independently distributed among donors and recipients during LDLT.