Study of MTOR and PPP3CA polymorphisms in renal transplant recipients and its relationship with the response to immunosuppressive agents.

Author(s)

Patricia de Cássia Salgado

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2012-10-26

Examining board members

Rosario Dominguez Crespo Hirata; Niels Olsen Saraiva Câmara; Claudia Rosso Felipe

• Advisor: Rosario Dominguez Crespo Hirata

Abstract

The immunosuppressant tacrolimus (Tac) and Sirolimus (Srl) are widely used in renal transplantation. These drugs have a narrow therapeutic range and are associated with a wide range of side effects. Single nucleotide polymorphisms (SNPs) have a significant impact on the pharmacokinetics of immunosuppressants. In order to evaluate the association of SNPs in genes MTOR and PPP3CA with the pharmacological response of immunosuppressive drugs tacrolimus and sirolimus were selected 156 individuals referred for kidney transplantation among patients treated in the Hospital do Rim e Hipertensão, UNIFESP. These individuals were treated with tacrolimus-based immunosuppressive regimen or converted to sirolimus. Blood samples were collected before transplantation for DNA extraction. Determinations of blood concentrations of Tac were determined by Chemiluminescent microparticle immunoassay (CMIA) and blood concentrations Srl were obtained by the technique of HPLC (High-Performance Liquid Chromatography). Polymorphisms of MTOR (c.1437T>C, T c.2997C>T and c.4731G>A) and PPP3CA (c.249G>A) were identified by real-time PCR. The Polymorphism PPP3CA c.246G>A was not associated with the daily dose of tacrolimus or sirolimus. The blood concentration of tacrolimus was lower in carriers of the allele on the third day and third month of study. The Polymorphisms of MTOR were related to blood concentration corrected by the dose of tacrolimus. The carriers of rare alleles G, T and C polymorphisms c.4731G> A, c.14337T> C and c.2997C> T, respectively, had values of Co/Do tacrolimus lower than the non-carriers of these alleles. Significant differences occurred mainly during the first three months of study. The blood concentration of tacrolimus was generally lower in carriers of the rare alleles being significantly lower on the fourteenth day. Higher doses of tacrolimus were associated with alleles c.14337T T>C and C c.2997C>T. In the sixth month of study, the carriers of rare alleles received doses of sirolimus significantly higher than non-carriers. SNPs c.2997C>T and c.1437T>C MTOR are in linkage disequilibrium (D \'= 0.981; r2 = 0.690). In the first three months of study, carriers of the TC haplotype received lower doses of tacrolimus and presented the best value for Co/Do. It was observed that after randomization, the TC haplotype remained associated with lower doses of tacrolimus and sirolimus and continued the trend of higher rates of Co/Do of both drugs. Polymorphisms c.1437T>C and c.4731G>A were associated with renal function parameters in the TAC group. The G allele of SNP c.4731G> A was related to lower levels of urea in the pre-Tx, a smaller reduction of urea and creatinine between the pre-Tx and sixth months of study. The T allele of SNP c.1437T>C was also related to lower levels of urea in the pre-Tx and a smaller reduction of creatinine. In the TAC group, the rare allele of SNP PPP3CA c.249G>A was related to lower levels of triglycerides in the pre-Tx and the SRL group a smaller variation of LDL-cholesterol. The C allele of the SNP c.2997C>T showed a lower increase in total cholesterol and LDL cholesterol between pre-Tx and sixth months of study, higher HDL cholesterol in pre-Tx and lower levels of triglycerides in the sixth month of study. The T allele of SNP c.1437T>C showed a lower increase in total cholesterol, LDL cholesterol, VLDL cholesterol and triglycerides. In the sixth month of the study, they had lower triglyceride levels compared to non-carriers of this allele. The G allele of SNP c.4731G>A change had lower total cholesterol, VLDL cholesterol and triglycerides. There was no relationship between the studied polymorphisms and biopsy-proven acute rejection or chronic allograft nephropathy. These results suggest that MTOR and PPP3CA polymorphisms are associated with dose and blood concentration of immunosuppressants tacrolimus and sirolimus, as well as a less atherogenic lipid profile. (AU)

• FAPESP's process: 10/03463-3 - Study of expression and polymorphisms of MTOR, PPP3CA and PPP3CB genes in renal transplant recipients undergoing immunosuppressive therapy
• Grantee: Patricia de Cássia Salgado
• Support Opportunities: Scholarships in Brazil - Master