Saudi Journal of Kidney Diseases and Transplantation

ORIGINAL ARTICLE
Year
: 2014  |  Volume : 25  |  Issue : 6  |  Page : 1160--1165

Influence of p53 (rs1625895) polymorphism in kidney transplant recipients


Negar Azarpira1, Koorosh Kazemi2, Masumeh Darai1,  
1 Shiraz Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
2 Organ Transplant Center, Shiraz University of Medical Sciences, Shiraz, Iran

Correspondence Address:
Dr. Negar Azarpira
Organ Transplant Research Center Nemazi Hospital, Shiraz University of Medical Sciences, Shiraz
Iran

Abstract

Reperfusion injury predisposes the kidney allograft to acute rejection. Apoptosis is a mechanism that results in graft injury, and TP53 is an important involved gene. To determine the association between single nucleotide polymorphism (SNP) in the pro-apoptotic protein p53 (rs1625895) and acute rejection in renal transplants, we studied 100 recipients of kidney allografts and 100 healthy individuals served as controls. The polymorphism was determined by the polymerase chain reaction restriction-fragment length polymorphism (PCR-RFLP) test. Overall, 31 recipients developed rejection. There was no difference in the genotype frequencies between the recipients and the controls. However, we found a difference of genotype and allele frequencies between recipients with and those without rejection. The WW genotype was more frequent in recipients with rejection. Although rejection is a complex immunologic event and functional importance of SNPs has not been confirmed yet, we suggest that wild type p53 may promote apoptosis during inflammation.



How to cite this article:
Azarpira N, Kazemi K, Darai M. Influence of p53 (rs1625895) polymorphism in kidney transplant recipients.Saudi J Kidney Dis Transpl 2014;25:1160-1165


How to cite this URL:
Azarpira N, Kazemi K, Darai M. Influence of p53 (rs1625895) polymorphism in kidney transplant recipients. Saudi J Kidney Dis Transpl [serial online] 2014 [cited 2022 Jan 27 ];25:1160-1165
Available from: https://www.sjkdt.org/text.asp?2014/25/6/1160/144248


Full Text

 Introduction



The tumor protein gene Tp53 is considered as a central monitor in the cell and can be acti­vated by anoxia, inappropriate oncogene signa­ling or DNA damage. In non-stressed, healthy cells, the pro-apoptotic protein p53 has a short half-life (20 min). When the cell is stresssed, p53 undergoes post-transcriptional modifica­tions with an increase in its half-life. After that, transcription of many genes is triggered into two broad categories: Those that cause cell cycle arrest and those that cause apoptosis. The p53-induced apoptosis is mediated by several pro-apoptotic genes such as BAX and the p53 upregulated modulator of apoptosis (PUMA). If DNA damage can be repaired during cell cycle arrest, the cell continues to a normal state; if the repair fails, p53 induces apoptosis. Therefore, p53 has been called the "guardian of the genome." [1]

Ischemia reperfusion injury (IRI) remains a critical clinical issue in organ transplantation. It is associated with a higher incidence of acute and chronic rejection as well as long-term morbidity and mortality. [2],[3] Apoptosis is a major occurrence of IRI during organ transplantation. [3] During reperfusion, both endothelial cells and parenchymal cells are susceptible to apoptosis or programmed cell death. [4]

TP53 , located on (17p13), is supposed to have an important role in modulating apoptosis in acute kidney injury. [4],[5],[6] The p53 gene is highly polymorphic, with at least 13 different polymorphisms described. [7],[8]

An intronic polymorphism of p53 consisting of a G-A transition in intron 6 (rs1625895) was investigated in relation to many cancers such as lung, ovarian, breast and colon, with conflicting results. [8],[9],[10],[11]

There are few reports that investigated the relation between TP53 polymorphism and kid­ney transplant outcome. [12]

We aimed in this study to determine the association between single nucleotide poly­morphism (SNP) in the pro-apoptotic gene Tp53 (rs1625895) and acute rejection in renal transplants patients. We compared the geno­type and allele frequencies of p53 intron 6 (rs 1625895) between kidney allograft recipients and normal control subjects. Also, we com­pared the genetic and allele frequencies bet-when recipients with and without acute rejec­tion (ARs vs. non-ARs).

 Materials and Methods



We studied 100 renal transplant recipients between June 2010 and March 2011. A control group of 100 unrelated healthy Iranian indi­viduals of both genders was included for com­parison with the study patients. The Ethics Committee of Shiraz University of Medical Sciences approved the protocol and a written informed consent was obtained from all sub­jects in accordance with the Helsinki Decla­ration. They were followed for at least 2 months and, in this period, an episode of acute rejection was recorded. Among the study group, 31 patients reported to have an episode of acute rejection. An acute rejection episode was defined based on clinical or biopsy find­ings according to the Banff criteria. [13],[14] Clin­ical rejection was identified as an increase in the serum creatinine level that was ≥10% from the baseline value in the absence of infection, obstruction or evidence of drug toxicity. The clinical characteristics were retrieved from our Kidney Transplant Database. The routine immunosuppression regimen consisted of cyclosporine or tacrolimus, with mycophenolate mofetile and prednisolone.

Genetic analysis

For genotype analysis, genomic DNA was extracted from a buffy coat with the use of the DNP DNA isolation kit (Cinagene, Tehran, Iran). Genotyping for p53 intron 6 (rs1625895) polymorphism was performed using a polymerase chain reaction (PCR) followed by restriction-fragment length polymorphism (RF LP), as described by Wu et al. [15]

The primers (5'-TGGCCATCTACAAG CA GTCA-3' and 5'-TTGCACATCTCATGG GG TTA-3') amplified a 404-bp fragment. The PCR product was digested with MspI (Fermentase, Litany). The DNA from WW homozygotes produced 68-bp and 336-bp bands; WM heterozygotes 68-bp, 336-bp and 404-bp bands; and MM homozygotes produced a 404-bp band [Figure 1].{Figure 1}

 Statistical Analysis



Analyses were performed with SPSS soft­ware (Statistical Package for the Social Sciences, version 18, SSPS Inc., Chicago, IL, USA) and Epi Info Statcalc version 5. Discrete and conti­nuous variables were compared between the rejection and non-rejection groups using the Pearson's test as appropriate. The Pearson's [2] test (3×2 contingency table) was used to assess the association of SNPs between the rejection and the non-rejection groups and also to compare the results between the study pa­tients and the controls.

 Results



The study patients included 60 males and the mean age was 30.4 ± 7.9 years. The detailed data of patients' demographic characteristics are shown in [Table 1]. Statistical analysis of the recipients demographic characteristics including donor and recipient age/gender, primary underlying kidney disease and immunosup­pressive regimen showed no differences between the ARs and non-ARs (P >0.05). The majority of organs were donated from the deceased donors.{Table 1}

Allele and genotype frequencies of the p53 intron 6 are shown in [Table 2]. There were no differences in the allele (P = 0.292; OR = 0.80; CI = 0.52-1.24) and genotype (P = 0.553) frequencies between the renal allograft reci­pients and the normal controls. There was only a significant difference of genotype (P = 0.0 09) and allele (P = 0.004; OR = 0.36; CI = 0.16-0.78) frequencies between the ARs and the non-ARs recipients. It was shown that the inheritance of minor allele (M) should be considered as a protective allele in the rejec­tion process.{Table 2}

Further, subjects were compared as WW geno­type vs WM + MM genotype [Table 3]. The results were the same as mentioned previously.{Table 3}

Only significant difference was found between the ARs vs the non-ARs groups (P = 0.002, OR = 0.25, CI = 0.09-0.68).

 Discussion



Kidney transplantation is an established treat­ment for patients suffering from end-stage renal diseases. However, ischemic reperfusion injury (IRI) of the allograft is an event that starts with the cessation of blood flow after organ procurement, cold ischemic time of the organ being donated and warm ischemic time during the organ transplantation. Re-establish­ment of blood flow in transplant recipients is characterized by an oxidative stress and in­flammation named as reperfusion injury. The IRI is associated with a higher incidence of graft rejection and loss. [16]

Apoptosis is one of the important pathways that results during the IRI. [16] The genes inclu­ding pro-apoptotic, anti-apoptotic/antioxidant and inflammatory response pathways are sup­posed to have a role in tubular apoptosis in human kidney allograft. The Tp53 gene plays a crucial role in mediating apoptotic cell death. [16],[17]

Previous studies showed that when the cold ischemia time (CIT) was longer than 24 h, the expressions of Bcl2, TP53 and CASP3 were significantly increased and higher TP53 expressions were associated with delayed graft function. [18],[19],[20] Wever et al found that apoptotic cells and apoptotic bodies were detected in tubular epithelia and tubular lumina in kidney biopsies during acute rejection. In our study, tubular expression of p53, Bcl-2 and BAX were also evaluated by the immunohistochemistry method. The expression of Tp53 and BAX (pro-apoptotic genes) was increased in the tubular nuclei during acute renal allograft rejection, which is considered important in the initiation of apoptosis. [21]

Conti et al studied gene expression profiling of the IRI in human liver transplants during the IRI process. [4] The gene expression analysis re­vealed that the genes involved in the apoptotic and inflammatory processes, as well as the genes encoding for heat shock proteins, were differentially expressed in the samples of the reperfused livers. They found that IRI also induces the up-regulation of some genes' co­ding for the adhesion molecules and the integrins. [4] Israni et al evaluated the relationship between donor SNP in the genes of the tumornecrosis factor alfa (TNF), transforming growth factor beta1 (TGFB1), interleukin 10 (IL10), p53 (TP53) and heme oxygenase 1 (HMOX1) and delayed graft function (DGF) after de­ceased donor kidney transplantation. [12] There was no association between the TGFB1, IL10, TP53 and HMOX1 genes and DGF. [12]

Increased expression of p53 in cardiac myocytes was also detected during acute cardiac allograft rejection. [22],[23]

In our study, the homozygote wild type geno­type of p53 intron 6 (rs1625895), WW, was significantly more frequent in renal allograft recipients with rejection and the inheritance of minor allele (M) was considered as a pro­tective allele during rejection.

We conclude that our study suggests that although the functional importance of this SNP is not confirmed yet, the functional wild type p53 may promote apoptosis during the inflam­matory process with more organ damage in allograft rejection. However, the small sample size of the enrolled population limited our con­clusions. Therefore, a study on larger sample size with consideration to other SNPs of p53, BAX, Bcl2 and the anti-apoptotic antioxidant heme oxygenase 1 gene (HMOX1) is advised.

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