Interleukin-10 gene promoter polymorphisms and susceptibility to brucellosis in Iranian patients

Background: Brucella spp. is the causative agent of brucellosis. It was clarified that type-1 immunity is important in controlling Brucella infection. In this regard, macrophages have critical roles. Interleukin-10 (IL-10) which is a Th2-type cytokine that inhibits macrophage activation has been inversely associated with the disease severity in human. It is known that production of IL-10 is affected by its gene promoter polymorphisms. In this study, we investigated the relationship between IL-10 gene promoter polymorphisms and susceptibility to brucellosis. Methods: A total of 190 patients with brucellosis and 81 healthy subjects who owned infected animals and consumed their contaminated dairy products were included in this study. All individuals were genotyped for three bi-allelic IL-10 gene promoter polymorphisms at positions -1082(G/A), -819(T/C), and -592(A/C) using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results: The distribution of CC genotypes and C alleles at positions -592 and -819 of IL-10 were significantly higher in patients than in the healthy subjects (P=0.034 and P=0.0086, respectively). IL-10 ATA single and double haplotypes were significantly higher in controls, compared to the patients (P= 0.0278 and P=0.013, respectively). Conclusion: Higher frequency of C alleles at positions -592 and -819 of IL-10 and lower frequency of ATA/ATA haplotype in patients can be considered as genetic factors for susceptibility to brucellosis.