Impact of FOXP3 Polymorphisms on the Blood Level of Tacrolimus in Renal Transplant Recipients

FKBP-CaN-NFAT pathway polymorphisms selected by in silico biological function prediction are associated with tacrolimus efficacy in renal transplant patients

AIM

The aim of the present study was to investigate the potential effects of genetic variations in the FKBP-CaN-NFAT pathway on clinical events associated with tacrolimus efficacy in Chinese renal transplant patients.

METHODS

One hundred and forty Chinese renal transplant patients of Han ethnicity with over five years of follow-up were enrolled in our study. A pool of single nucleotide polymorphisms (SNPs) (1284 SNPs) was extracted from the Ensembl database according to chromosomal regions of the candidate genes. Next, 109 SNPs were screened out from this pool using multiple bioinformatics tools for subsequent genotyping using the MALDI-TOF-MS method. The associations of these candidate SNPs with acute rejection, nephrotoxicity, pneumonia and post-transplant estimated glomerular filtration rate (eGFR) were explored.

RESULTS

Fourty-four SNPs were found to be associated with tacrolimus-related clinical drug response. Specifically, eight SNPs were associated with the incidence of biopsy-proven acute rejection, four SNPs were associated with the rate of nephrotoxicity, 16 SNPs were correlated with the onset of pneumonia, and 26 SNPs were found to significantly influence post-transplant eGFR trend. An elaborate scoring system was implemented to prioritize the validation of these potentially causal SNPs. In particular, NFATC2 rs150348438 (G>T) performed well during integrative scoring (P_total=23.8) and was significantly associated with the occurrence of pneumonia (P = 0.0035, HR=0.91, 95% CI=0.85-0.97) and post-transplant eGFR levels (P = 0.000003).

CONCLUSIONS

NFATC2 rs150348438, rs6013219, rs1052653, and NFATC1 rs754093, ranking high in scoring, significantly affected the post-transplant eGFR and the incidence of pneumonia, acute rejection, and nephrotoxicity in renal transplant patients taking tacrolimus. Those SNPs may alter the expression and regulation of FKBP-CaN-NFAT pathway by influencing transcription regulation, mature mRNA degradation and RNA splicing, or protein coding. Critical SNPs of high ranking may serve as PD-associated pharmacogenetic biomarkers indicating individual response variability of TAC, and thus aid the clinical management of renal transplant patients.

Evaluation of Forkhead Box P3 gene polymorphisms in chronic HBV infection

BACKGROUND

Hepatitis B virus (HBV) infection causes liver failure, liver cirrhosis and hepatocellular carcinoma. The FOXP3 gene polymorphisms, the rs2232365 A/G and the rs3761548 A/C, were identified to be associated with regulatory T cell-mediated immunosuppression. The response to HBV infection may be affected by FOXP3 polymorphisms. The present study aimed to assess the relationship between FOXP3 gene polymorphisms and chronic HBV infection risk.

METHODS

FOXP3 gene polymorphisms were explored in 237 chronic HBV patients and in 237 individuals with HBV spontaneous clearance using a real-time polymerase chain reaction.

RESULTS

The patients with rs2232365 AG and rs3761548 AC genotype had a 1.20- and a 1.58-fold greater HBV risk than non-carriers patients, although they were not significant. Moreover, the AA genotypes of both polymorphisms in the males and females had an increased the persistent HBV risk, although this also was not statistically significant.

CONCLUSIONS

In conclusion, the present study is the first report to demonstrate that these polymorphisms have no effect on the risk of chronic HBV infection. This results suggest that FOXP3 gene polymorphisms and FOXP3 expression should be evaluated together with frequency of regulatory T cells in HBV infection.

Identification of genetic variants associated with tacrolimus metabolism in kidney transplant recipients by extreme phenotype sampling and next generation sequencing

An extreme phenotype sampling (EPS) model with targeted next-generation sequencing (NGS) identified genetic variants associated with tacrolimus (Tac) metabolism in subjects from the Deterioration of Kidney Allograft Function (DeKAF) Genomics cohort which included 1,442 European Americans (EA) and 345 African Americans (AA). This study included 48 subjects separated into 4 groups of 12 (AA high, AA low, EA high, EA low). Groups were selected by the extreme phenotype of dose-normalized Tac trough concentrations after adjusting for common genetic variants and clinical factors. NGS spanned >3 Mb of 28 genes and identified 18,661 genetic variants (3,961 previously unknown). A group of 125 deleterious variants, by SIFT analysis, were associated with Tac troughs in EAs (burden test, p=0.008), CYB5R2 was associated with Tac troughs in AAs (SKAT, p=0.00079). In CYB5R2, rs61733057 (increased allele frequency in AAs) was predicted to disrupt protein function by SIFT and PolyPhen2 analysis. The variants merit further validation.

Polymorphisms in mTOR and Calcineurin Signaling Pathways Are Associated With Long-Term Clinical Outcomes in Kidney Transplant Recipients

Monitoring of immunosuppressive drugs, such as calcineurin and mTOR inhibitors, is essential to avoid undesirable kidney transplant outcomes. Polymorphisms in pharmacokinetics-related genes have been associated with variability in blood levels of immunosuppressive drugs and adverse effects, but influence of pharmacodynamics-related genes remains to be elucidated. The influence of polymorphisms in genes of the mTOR and calcineurin signaling pathways on long-term clinical outcomes was investigated in Brazilian kidney transplant recipients within the 1-year post-transplant. Two-hundred and sixty-nine kidney transplant recipients were enrolled at a kidney transplant center in São Paulo city, Brazil, and treated with tacrolimus plus everolimus or mycophenolate sodium (clinical trial NCT01354301). Clinical and laboratory data, including renal function parameters and drug blood levels were recorded. Genomic DNA was extracted from blood samples. Polymorphisms in MTOR rs1057079 (c.4731G>A), rs1135172 (c.1437T>C), and rs1064261 (c.2997C>T); PPP3CA rs3730251 (c.249G>A); FKBP1A rs6033557 (n.259+24936T>C); FKBP2 rs2159370 (c.-2110G>T); and FOXP3 rs3761548 (c.-23+2882A>C) and rs2232365 (c.-22-902A>G) were analyzed by real-time PCR. Frequencies of gene polymorphisms did not differ among the treatment groups. Analysis of primary outcomes showed that patients carrying MTOR c.1437CC and FOXP3 c.-23+2882CC genotypes had higher serum creatinine than non-carriers (p < 0.05) at 1-year post-transplant. MTOR c.4731G allele (AG+GG genotype) was associated with increased risk for acute rejection (OR = 3.53, 95% CI = 1.09-11.48, p = 0.037). Moreover, 1-year cumulative incidence of rejection was higher in MTOR c.4731G allele carriers compared to AA genotype carriers (p = 0.027). Individually, analysis of secondary outcomes revealed that FKBP2 c.-2110GG genotype carriers had higher risk of leukopenia, FKBP1A n.259+24936C allele carriers had increased risk of constipation, and FOXP3 c.-22-902A or c.-23+2882A allele had higher risk of gastrointestinal disorders (p < 0.05). However, these results were not maintained in the multivariable analysis after p-value adjustment. In conclusion, variants in genes of mTOR and calcineurin pathways are associated with long-term impaired renal function, increased risk of acute rejection, and, individually, with adverse events in Brazilian kidney transplant recipients.

Functional Foxp3 polymorphisms and the susceptibility to cancer: An update meta-analysis

BACKGROUND

Forkhead box P3 (Foxp3) plays important roles in the development and pathogensis of cancer. To investigate the association of 3 polymorphisms of Foxp3 (rs3761548, rs 3761549 and rs2280883) and cancer risk, an updated meta-analysis was performed.

METHODS

Around 11 studies including 4344 cancer patients and 4665 healthy controls were selected for this meta-analysis. There were nine studies with 3783 cases and 4096 controls for rs3761548, 4 studies with 1669 cases and 1613 controls for rs3761549 and 4 studies with 1821 cases and 1799 controls for rs2280883. Odds radios (ORs) and 95% confidence intervals (CIs) were used to evaluate the cancer risk.

RESULTS

Meta-analysis showed that rs3761548 was associated with an increased cancer risk in the overall population under the recessive model (AA vs CA + CC: OR = 1.45, 95%CI = 1.03-2.02, P = .03). No association was found between rs3761549, rs2280883 polymorphisms, and cancer susceptibility in the overall population. Nonetheless, in the genotyping methods subgroup analysis of rs2280883, a lower risk of cancer was found in studies using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) under the allelic model (C vs T: OR = 0.70, 95%CI = 0.52-0.95, P = .02), heterozygote model (TC vs TT: OR = 0.60, 95%CI = 0.41-0.87, P = .008) and dominant model (CC + TC vs TT: OR = 0.63, 95%CI = 0.45-0.90, P = .01). In the subgroup analysis by cancer types showed C allele or TC carriers were insusceptible to cancer under 3 genetic models (C vs T: OR = 0.78, 95%CI = 0.64-0.95, P = .01; TC vs TT: OR = 0.50, 95%CI = 0.32-0.79, P = .003; CC + TC vs TT: OR = 0.64, 95%CI = 0.51-0.82, P < .001).

CONCLUSION

Our results suggest that rs3761548 polymorphism is associated with cancer risk.

[Correlation of blood concentration of tacrolimus with serum cystatin C in renal transplant recipients and effect of tacrolimus on glucose and lipid metabolism]

OBJECTIVE

To investigate the correlation between blood concentrations of tacrolimus (FK506) and cystatin C (Cys C) and the effect of FK506 on glycolipid metabolism in renal transplant recipients.

METHODS

A total of 325 patients receiving renal transplantation between August, 2014 and September, 2015 in Nanfang Hospital were divided into 4 groups according to the postoperative time (1 month group, 1-3 months group, 4-6 months group, and 7-12 months group). FK506 blood trough concentration was measured at the time of postoperative follow-up, and creatinine (Scr) and Cys C levels were also detected. Results Plasma FK506 concentration decreased with age in the recipients and showed a positive correlation with Cys C (r=0.985, P=0.015) but no obvious correlation with Scr (r=0.259, P=0.741). FK506 had no effect on blood glucose (5.53-5.59 mmol<L) or blood lipids (TG 1.47-1.55 mmol<L, TC 5.04-5.17 mmol<L, LDL-C 3.00-3.07 mmol<L, and VLDL 0.73-0.76 mmol<L) in patients 1-6 months after renal transplantation.

CONCLUSION

FK506 does not affect the level of glycolipid metabolism in patients after renal transplantation. Cys C is positively related to blood concentration of FK506 in the renal transplantation recipients. The rational use of FK506 can improve the effectiveness and safety of the treatment in the recipients.