TGF beta 1 genetic variants are associated with an increased risk of acute brucellosis

Abstract

Objective: Cytokines play a critical role in the regulation of the immune response against brucellosis infection, and mediate production of many pro- and anti-inflammatory signals. Transforming growth factor-beta 1 (TGF beta 1), a powerful suppressive cytokine, inhibits macrophage activation and modulates T-cell function, and plays crucial roles in regulation of microbial replication and host responses to brucella. Methods: The association of three polymorphisms in the TGF beta 1 gene (-509 C/T rs1800469, + 868 C/T rs1800470, and + 913 G/C rs1800471) in promoter, codons 10 and 25, respectively, with brucellosis infection was evaluated. This case-control study was performed on a total of 281 Iranian subjects including 153 patients with active brucellosis and 128 age- and sex-matched healthy individuals as controls. Genotyping for the TGF beta 1-509 C/T and + 868 C/T variants was performed using tetra amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR). Also, the + 913 G/C polymorphism was genotyped using an allele-specific PCR. Results: The results demonstrated that the TGF beta 1 + 868 C/T mutant homozygote genotype (TT vs CC), was a risk factor for developing brucellosis in the co-dominant and recessive models (odds ratio (OR) = 2.60, p = 0.023; OR = 2.602, p = 0.014, respectively). Additionally, the diplotype analyses revealed that TGF beta 1 codon 10 and 25 diplotype, TT/GG, was associated with an increased risk of brucellosis (OR = 2.49, p = 0.038). Other TGF beta 1 variants did not increase the risk of brucellosis infection. Conclusions: Our findings propose that TGF beta 1 + 868 TT genotype and TT/GG diplotype may confer increased risk of brucellosis in the examined population.