IJCS | Volume 33, Nº3, May / June 2020

255 Silva et al. Polymorphisms in acute coronary syndrome Int J Cardiovasc Sci. 2020; 33(3):254-262 Original Article of cell types involved in atherosclerosis, in addition to being expressed in areas rich in macrophages of atherosclerotic lesions. 3-5 In addition to a potential role in the initiation and progression of atherosclerosis, IL-8 can also participate in the complications of this process by acting on destabilization of atherosclerotic plaque and specifically on thrombosis. 3,4 Single nucleotide polymorphism (SNP) in IL8 gene (rs 4073) has been shown to be associated with SCA in different populations. Its frequency is related to a high plasma level of its respective cytokine, which may contribute to an inflammation associated with the infiltration of macrophages and neutrophils, thus providing a substrate for the development of ACS. 5,6 This SNP has the ability to alter the transcriptional activity of the gene, contributing to the increase of IL-8 cytokine levels. 7-9 IL-16 is a pleiotropic and immunoregulatory proinflammatory cytokine. 10 Elevated levels of this cytokine were detected in patients with CAD. 11 In previous studies, this cytokine is related to the regulation of recruitment and activation of CD4 + T cells in the inflammatory process of CVDs. 12 Some studies report that the G mutant allele in its gene (rs11556218) is associated with a significantly increased risk of CDs. 13-15 The exact role of IL-16 in the pathogenesis of ACS remains unclear, but it is known that the rs11556218 T/G SNP may influence the expression of IL-16 cytokine and alteration of its serum levels may promote the production of other cytokines IL-1, IL-2 and IL-6 that are involved in the development of ACS. 15 These findings suggest that SNPs in the IL8 (rs4073) and IL16 (rs11556218) genes may be useful markers of genetic susceptibility toACS, allowing the identification of high-risk individuals by selecting for more invasive therapies 16 and closer monitoring. The lack of uniformity in positive results in several populations is the major problem for the study of genetic association. 17 Thus, it is necessary to study SNPs in specific populations to identify their association with diseases in a region. The aim of this study was to evaluate the association between SNPs in the IL8 (rs4073) and IL16 genes (rs11556218) and the risk of developingACS. In addition it was our intention to compare our blood donor populationwith other healthy populations fromdifferent countries, to contribute to the identification of molecular markers in disease susceptibility. Materials and Methods Study population Patients with ACS (n = 200) and non-ACS (n = 50) are adults of both genders admitted to the Real Hospital Português (RHP), Recife – PE, Brazil. Patients with ACS have their diagnosis performed by the clinical team and laboratory data suggestive of ischemic myocardial injury. Patients with nonACS were admitted to the RHP with other cardiac disease. For both groups, data were collected about the presence of the main risk factors for coronary artery disease such as diabetes mellitus, systemic arterial hypertension and dyslipidemia. A group of healthy adults (n = 220) blood donors with negative diagnosis for infectious and parasitic diseases was also selected. The collection period was from May 2012 to August 2016 for all subjects participating in the study. The sample sizewas obtained through the convenience selection of the patients. The present study was approved by the Research Ethics Committee of RHP (CAEE: 03187512.2.0000.5202) and all individuals signed the Informed Consent Term. It was decided not to perform ethnic correspondence, since previous studies in Brazilian populations have shown that skin color or self-defined ethnic origins are not considered accurate as biomarkers for ancestry in Brazil. 18 Genotyping Blood was collected in a tube with Ethylene Diamine Tetraacetic Acid (EDTA) and extracted DNA was amplified by the Polymerase Chain Reaction (PCR) method using specific primers and amplification conditions for each SNP (Table 1). As a negative control, reagents without DNA were used. The fragments were visualized on 1% agarose gel and subjected to DNA sequencing using the ABI 3500xL Genetic Analyzer (Applied Biosystems, USA). Dosage of inflammatory markers: The cytokines were dosed in the serum through the Human Quantikine ELISA Kit (R&D Systems, Minneapolis, MN), following themanufacturer’s guidelines, using the Enzyme Lynked Immunosorbent Assay (ELISA) method. Statistical analysis The X2 test was used to verify the Hardy-Weinberg equilibrium. Differences between the genotypic