Association Of PON1Genetic And Epigenetic Variation With The Clinical Efficacy Of Dual-antiplatelet Therapy

Coronary Atherosclerotic heart Disease(CAD) is one of the most important causes of death, also consumes huge medical resources of disease. Abnormal lipid metabolism and hypertension are major risk factors for coronary heart disease. Aging, sex, diet, smoking, drugs, and psychological stress are all associated with the development of the disease to a certain extent. In addition to a number of environmental factors, coronary heart disease is also a multi-gene-related disease, that is,40%-60%of the disease can be effectivly resolved from the perspective of genetics. So, CAD is the result of both genetic and environmental factors.Gene has its characteristic of relative-stability, thus, there is important significance of researching genetic risk factors of CAD to prevent or delay the occurrence of the disease. Percutaneous coronary intervention (PCI) is one of the significant progress in the treatment history of coronary heart disease. In patients undergoing PCI, the combination of aspirin and clopidogrel is the most commonly treatment of antiplatelet therapy, and also it has played an important role in improving patient outcomes. However, clinical efficacy of this treatment has individual differences, even some ineffective treatment can directly lead to death. Genetic pharmacology studies found that the gene polymorphisms of enzymes that relatede to drug metabolizing, transporting, as well as the drug receptor are the major causes.Human paraoxonase1(PON1) is one of the important enzymes in the liver. It is closely related with the occurence and development of CAD because of its involvement in lipid-metabolism of the human body. Rencently, PON1has been reported to participate in hydrolyzing a variety of drugs including aspirin and/or clopidogrel in the liver. PON1gene-polymorphisms, such as Q192R and L55M exon region as well as-108C/T in the gene promoter region had been reported to be associated with CAD. In recent years, papers had reported that mutations of these sites might affect the clinical efficacy of the anti-antiplatelet therapy in patients undergoing PCI. Epigenetics confirmed that the DNA methylation of the CpG island within the gene-promoter region might be related to the expression of genes. There was a typical CpG island within the promoter region of PON1,71.3%of which was made up of G and C, and in which the rate ofoccurrence of CpG dinucleotides is also up to0.74. In the CpG island, there were the special sequences that the transcription factor Spl and other transcription associated factors binding to.We suspected that wheather there was a significant association between the methylation of the CpG island and the concentration of plasma PON1. Thus, this study, on one hand, is to reveal the relationship of the PON1gene-polymorphisms and the development of CAD as well as the clinical efficacy of the anti-antiplatelet therapy in patients undergoing PCI; on the other hand, to explore the role that the DNA methylation of the CpG island within the PON1gene-promoter region may play in affecting the clinical efficacy of the anti-antiplatelet therapy of aspirin and clopidogrel.Methods and results:1.1077individuals (538CAD patients and539healthy controls) were sequentially recruited in this study. Five genetic variants of PON1(-108C/T,-126C/Q-162A/G&L55M, Q192R) were genotyped by a direct sequencing method. The effect of genetic variants on disease risk was assessed by genotype and haplotype association analyses. After being adjusted for confounding factors(p≥0.05), PON1-126C allele was associated with a higher risk ofC AD (adjusted p=0.0127); Haplotype analyses showed a similar result. Male, aging, hypertension, and diabetes were risk factors for CAD (p<0.05).2.538CAD patients undergoing PCI and receiving dual-antiplatelet therapy were sequentially recruited and followed up-to one year. The effect of genetic variants on clinical outcome of MACE in1yeart or bleeding in6months was assessed by the genotype and haplotype association analyses as well as the survival regression analyses. PON1-Q192R genotype was significantly associated with an increased risk of the primary endpoint of MACE (HR=1.60, adjusted p=0.0487), but a decreased risk of safety endpoint of bleeding events (OR=0.61, adjusted p=0.0066). L55M mutation could increase the risk of bleeding events (OR=2.96, adjusted p=0.0209).-126C showed to be a risk of bleeding (OR=1.68, adjusted p=0.017).Complications of hypertension or/and diabetes were risk factors of MACE, and diabetes could also increase the risk of bleeding(p<0.05).3.89of the538CAD patients followed up-to1year were recruited in this part. Among them,29patients had the primary endpoint of MACE in1year,32had safety endpoint of bleeding events in6months, and28had neither of MACE or bleeding events. Methylation of the CpG island within the PON1promoter region was detected by adjusted bisulfite-sequencing-PCR method. We found in our results that methylation of the CpG island was higher in patients with MACE, but lower in patients with the safety endpoint of bleeding (p<0.05). The difference was significantly showed in the first5CpG sites (PON1-183、-169、-162、-160、-141).4.486of the538CAD patients, including41with the primary endpoint of MACE in1year and61with the safety endpoint of bleeding in6months, were recruited in this part. Methylation of the first5CpG sites (PON1-183、-169、-162、-160、-141)was detected by Pyrosequencing method. Data was analysed by uni-variate and multi-variate logistic regression analyses. We found that lower methylation of PON1-160site was significantly associated with the increased risk of bleeding event (p<0.0001). And it interacted with the-108C/T variation within the PON1promoter region to work on risks of bleed ing(p<0.0001).Conclusions:1. PON1-126C allele contributes to a higher riskof CAD. Male, aging, having complications of hypertension or diabetes were risk factors of CAD.2. PON1-Q192R was associated with an increased risk of MACE in1year,but a decreased risk of bleeding in6months. PON1-126C allele and L55M were risk factors of bleeding events in dual antiplatelet treated CAD patients after PCI..3. Methylation of the CpG island of PON1was higher in patients with MACE, but lower in patients with the safety endpoint of bleeding.4. Lower methylation of PON1-160C site was significantly associated with a increased risk of bleeding event in6months. And it interacted with the-108C/T variation within the PON1promoter region to work on risks of bleeding.