Association between interleukin-6 polymorphism in the -174 G/C region and hearing loss in the elderly with a history of occupational noise exposure

INTRODUCTION: The biological processes involved in noise-induced hearing loss (NIHL) are still unclear. The involvement of inflammation in this condition has been suggested. OBJECTIVE: To investigate the association between interleukin - 6 (IL-6) polymorphism and susceptibility to NIHL. METHODS: This was a cross-sectional study with a sample of 191 independent elderly individuals aged > 60 years of age. Information on exposure to occupational noise was obtained by interviews. Audiological evaluation was performed using pure tone audiometry and genotyped through PCR by restriction fragment length polymorphism - PCR-RFLP. Data were analyzed using the Chi-square test and the Odds ratio (OR), with the significance level set at 5%. RESULTS: Among elderly with hearing loss (78.0%), 18.8% had a history of exposure to occupational noise. There was a statistically significant association between the genotype frequencies of the IL-6 -174 and NIHL. The elderly with the CC genotype were less likely to have hearing loss due to occupational noise exposure when compared to those carrying the GG genotype (OR = 0.0124; 95% CI 0.0023-0.0671; p < 0.001). CONCLUSION: This study suggests there is an association of polymorphisms in the IL- 6 gene at position - G174C with susceptibility to noise-induced hearing loss.

研究背景：噪声性听力损失（noise-induced hearing loss, NIHL）相关的生物学过程目前仍未明确，有研究提示炎症反应参与了该疾病的发生发展。
研究目的：探讨白细胞介素-6（interleukin-6, IL-6）基因多态性与噪声性听力损失易感性之间的关联。
研究方法：本研究为横断面研究，纳入191名年龄大于60岁的独立老年受试者作为研究样本。通过访谈收集职业噪声暴露相关信息，采用纯音测听进行听力评估，通过聚合酶链反应-限制性片段长度多态性（polymerase chain reaction-restriction fragment length polymorphism, PCR-RFLP）方法完成基因分型。数据分析采用卡方检验及比值比（Odds ratio, OR），设定显著性水平为5%。
研究结果：在出现听力损失的老年受试者中（占比78.0%），18.8%有职业噪声暴露史。IL-6基因-174位点的基因型频率与噪声性听力损失存在统计学意义上的显著关联。与携带GG基因型的受试者相比，携带CC基因型的老年个体因职业噪声暴露导致听力损失的风险更低（OR=0.0124；95%置信区间（confidence interval, CI）：0.0023-0.0671；p<0.001）。
研究结论：本研究提示，IL-6基因-174G>C位点的多态性与噪声性听力损失的易感性存在关联。