Role of interleukin-6 −174 G/C promoter polymorphism in trace metal levels of autopsy kidney and liver tissues

Abstract

Interleukin-6 (IL-6) gene is a multifunctional cytokine which is expressed in lymphocytes, fibroblasts, macrophages, in response to different types of inflammatory stimuli. IL-6 also controls induction and expression of metallothioneins (MTs) which maintain homeostasis of zinc and copper. In human, IL-6 gene is located on chromosome 7p21 and -174 G/C polymorphism located in its promoter region. Recently, genetic studies showed that IL-6 -174 G/C promoter polymorphism influences IL-6 gene transcription and plasma cytokine levels. The aim of this study is to determine the IL-6 promoter polymorphism effect on trace element levels and toxic metal accumulation in the kidney and liver tissues. Kidney and liver tissues were collected from 122 autopsy cases in Ankara district. IL-6 promoter polymorphism was detected by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis. The genotype frequencies were found as 54.9% homozygote typical (GG), 39.3% heterozygote (GC) and 5.7% homozygote atypical (CC). The allele frequencies in all subjects were consistent with Hardy-Weinberg equilibrium (χ(2) = 0.179; p > 0.05). In order to assess the cadmium (Cd), lead (Pb), zinc (Zn) and copper (Cu) levels in the autopsy tissues, a dual atomic absorption spectrophotometer system was used. As a result, no statistical association was found between the IL-6 promoter polymorphism and Pb, Cd, and Cu (p > 0.05) levels in the kidney and liver tissues but statistically significant differences were detected with the Zn concentration (p < 0.05).