Influence of MDR1 gene polymorphisms on calcineurin inhibitors' metabolism and kidney graft function

Transplantacija bubrega je najbolji način lečenja bolesnika u terminalnoj fazi hronične bolesti bubrega. Uvođenje kalcineurinskih inhibitora (KNI) u imunosupresivne protokole je jedan od najznačajnijih koraka u razvoju transplantacione medicine koji je značajno poboljšao preživljavanje kako alografta, tako i bolesnika sa presađenim bubregom. Ovi lekovi blokiraju sintezu citokina potrebnih za aktivaciju T-limfocita (interleukina-2, interleukina-4, interferona-γ i faktora nekroze tumora-α) i tako ostvaruju svoj imunosupresivni efekat. Imaju vrlo uzak terapijski opseg, izraženu interidividaulnu i intraindividualnu varijabilnost, kao i veliki broj neželjenih efekata koji utiču na funkciju alografta. Samo neki od neželjenih efekata mogu se objasniti neadektavnom koncentracijom leka u krvi. Brojna istraživanja bavila su se ispitivanjem povezanosti genskih polimorfizama i farmakokinetske i farmakodinamske varijabilnosti KNI. Jedan od najznačajnijih gena za metabolizma KNI je MDR1 gen koji kodira sintezu P-glikoproteina koji je proteinski nosač KNI iz intracelularnog u ekstracelularni prostor. Ciljevi istraživanja: Osnovni cilj našeg istraživanja bio je da se ispita učestalost genotipova pojedinačnih nukleotidnih polimorfizama (C1236T, G2677T/A i C3435T) MDR1 gena i njihovih haplotipova. Pored toga, ispitivali smo i uticaj genotipova i haplotipova MDR1 gena na farmakokinetiku KNI, učestalost akutnog odbacivanja (AO), učestalost odložene funkcije alografta (OFA) i funkciju alografta. Imajući u vidu mnogobrojne neželjene efekte KNI, ispitivali smo i uticaj genotipova i haplotipova MDR1 gena na koncentraciju glukoze, kalijuma, mokraćne kiseline, holesterola, triglicerida i aminotransferaza u serumu. Metode: Studija je dizajnirana kao neinterventno retrospektivno opservaciono ispitivanje, sprovedeno u Klinici za nefrologiju Kliničkog centra Srbije i Institutu za mikrobiologiju i imunologiju Medicinskog fakulteta Univerziteta u Beogradu. U ispitivanje su uključena 152 bolesnika sa presađenim bubregom koji su imali CYP3A5*3*3 genotip. Izolacija molekula DNK vršena je iz uzoraka pune krvi standardnom metodom kolonica. Podaci o dozama i koncentracijama KNI, funkciji alografta, AO i OFA, kao i vrednosti glikemije, hemoglobina, hematokrita, mokraćne kiseline, kalijuma, aspartat- i alaninaminotransferaze, ukupnog holesterola i triglicerida, dobijeni su iz ambulantnog kartona bolesnika sa presađenim bubregom...Kidney transplantation is the best treatment option for patients with end stage chronic kidney disease. The introduction of calcineurin inhibitors (CNI) in immunosuppressive protocols have played an important role in improving the outcome of kidney transplantation. These drugs block the cytokine synthesis needed to activate T-lymphocytes and thereby achieve their immunosuppressive effect. They have a narrow therapeutic range, interindividual and intraindividual variability, and a large number of side effects that affect the function of the allograft. However, only some of the side effects can be explained by an inadequate drug concentration in the blood. Numerous studies have investigated the relationship between gene polymorphisms and pharmacokinetic and pharmacodynamic variability of CNI. One of the most significant genes for CNI metabolism is the MDR1 gene that encodes the synthesis of the protein carrier CNI. Objective: The primary aim of our study was to examine the frequency of genotypes of SNPs (C1236T, G2677T/A and C3435T) of the MDR1 gene and their haplotypes. In addition, we examined the influence of genotypes and haplotypes of the MDR1 gene on the CNI pharmacokinetics, the frequency of acute rejection (AR), the frequency of delayed function (DGF) and the allograft function. Also, we examined the influence of SNPs and haplotypes of the MDR1 gene on the serum level of glucose, potassium, uric acid, cholesterol, triglyceride and aminotransferase. Methods: This study was designed as a retrospective observation study conducted at the Clinical Center of Serbia, Clinic of Nephrology and the Institute of Microbiology and Immunology at the University of Belgrade, Medical Faculty. This study included 152 patients who were kidney transplant recipients with a CYP3A5 * 3 * 3 genotype. DNA molecules were extracted from whole blood samples using a standard colonic method. The patient charts revealed data about the CNI dosage and concentration, allograft function, frequency of AR and DGF, as well as the serum level of glucose, hemoglobin, hematocrit, uric acid, potassium, aspartate and alanine aminotransferase, total cholesterol and triglyceride. AR was diagnosed by allograft biopsy or on the basis of allograft function deterioration that has improved after high-dose of corticosteroid therapy. DGF was defined as a need for hemodialysis during the first two weeks after kidney transplantation..