Polymorphisms of the TNF-α gene interact with plasma fatty acids on inflammatory biomarker profile: a population-based, cross-sectional study in Sao Paulo, Brazil

The aim of the present study was to investigate the relationship of four TNF-alpha SNP with inflammatory biomarkers and plasma fatty acids (FA), and the interaction among them in a population-based, cross-sectional study in Sao Paulo, Brazil. A total of 281 subjects, aged > 19 and < 60 years, participated in a cross-sectional, population-based study performed in Brazil. The following SNP spanning the TNF-alpha gene were genotyped: -238G/A (rs361525), -308G/A (rs1800629), -857C/T (rs1799724) and -1031T/C (rs1799964). In all, eleven plasma inflammatory biomarkers and plasma FA profile were determined. To analyse the interaction between TNF-alpha SNP and plasma FA, a cluster analysis was performed to stratify individuals based on eleven inflammatory biomarkers into two groups used as outcome: inflammatory (INF) and non-inflammatory clusters. The -238A allele carriers had higher TNF-alpha (P=0.033), IL-6 (P=0.013), IL-1 beta (P=0.037), IL-12 (0.048) and IL-10 (P=0.010) than the GG genotype. The -308A allele carriers also had lower levels of plasma palmitoleic acid (P=0.009), oleic acid (P=0.039), total MUFA (P=0.014), stearoyl-CoA desaturase (SCD) activity index-16 (P=0.007), SCD-18 (P=0.020) and higher levels of PUFA (P=0.046) and DHA (P=0.044). Significant interactions modifying the risk of belonging to the INF cluster were observed with inflammatory cluster as outcome between -857C/T and plasma alpha-linolenic acid (P=0.026), and also between -308G/A and plasma stearic acid (P=0.044) and total SFA (P=0.040). Our study contributes to knowledge on TNF-alpha SNP and their association with inflammatory biomarker levels, plasma FA and the interaction among them, of particular interest for the Brazilian population.