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|Year : 2015
: 17 | Issue : 79 | Page
|Association between polymorphism of interleukin-6 in the region -174G/C and tinnitus in the elderly with a history of occupational noise exposure
Marcelo Yugi Doi1, Ana Carolina Marcotti Dias1, Regina Célia Poly-Frederico2, Maira Gabriela Sasso Rosa Maria3, Maria Nazaré de Oliveira3, Luciana Lozza de Moraes Marchiori4
1 Department of Centre of Research in Health Sciences, University of Northern Parana, Londrina-PR, Brazil
2 Department of Molecular Biology, Centre of Research in Health Sciences, University of Northern Parana, Londrina-PR, Brazil
3 Student of Audiology and Speech Therapy, University of Northern Parana, Londrina-PR, Brazil
4 Department of Audiology and Speech Therapy, Centre of Research in Health Sciences, University of Northern Parana, Londrina-PR, Brazil
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|Date of Web Publication||17-Nov-2015|
Tinnitus is a symptom usually related to cochlear change that may arise from noise exposure and induces expression of proinflammatory cytokines including interleukin-6 (IL6). This study aimed to evaluate the association between the polymorphism of the IL6 gene in the region 174G/C and tinnitus in elderly with history of occupational noise exposure. Settings and Design: This was a cross-sectional study with a sample of 179 independent elderly individuals aged >60 years. Information on exposure to occupational noise was obtained by interviews. Audiological evaluation was performed using pure tone audiometry and genotyped through polymerase chain reaction 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%. Among the study subjects, 24.6% were homozygous for the G allele, 39.7% were homozygous for the C allele, and 35.8% were heterozygous for IL6 (P > 0.05). Of these, 33.5% reported noise exposure history, with 42.5% having tinnitus. We found significant association between the genotype and allele frequencies of the IL6 −174 gene (rs1800795) and tinnitus among the elderly with history of exposure to occupational noise (P = 0.03). The elderly with the C allele were less likely to have tinnitus associated with history of exposure to occupational noise [OR = 0.167, confidence interval (CI) 95% 0.167-0.749; P = 0.004] when compared to those carrying the G allele. This study suggests that there is an association between polymorphisms in the IL6 gene at region - 174G/C and susceptibility to tinnitus.
Keywords: Elderly, genetic polymorphism, interleukin-6 (IL6), occupational noise, tinnitus
|How to cite this article:|
Doi MY, Dias AM, Poly-Frederico RC, Maria MS, de Oliveira MN, de Moraes Marchiori LL. Association between polymorphism of interleukin-6 in the region -174G/C and tinnitus in the elderly with a history of occupational noise exposure. Noise Health 2015;17:406-10
|How to cite this URL:|
Doi MY, Dias AM, Poly-Frederico RC, Maria MS, de Oliveira MN, de Moraes Marchiori LL. Association between polymorphism of interleukin-6 in the region -174G/C and tinnitus in the elderly with a history of occupational noise exposure. Noise Health [serial online] 2015 [cited 2021 Dec 8];17:406-10. Available from: https://www.noiseandhealth.org/text.asp?2015/17/79/406/169703
| Introduction|| |
There has been an increase in the aging population in both developed countries and developing countries.  It is estimated that by 2040, developing countries will have 1 billion people aged 60 or older.  Given the high speed and extent of this growth, care for this particular group is essential so that they can age in good health with good quality of life. 
Tinnitus is a poorly understood auditory percept that occurs in the absence of an external stimulus and is typically associated with hearing loss.  It is a highly prevalent symptom worldwide and affects about 15% of Americans.  A study to determine the prevalence of tinnitus in elderly Nigerians and their impact on quality of life found that tinnitus was present in 14.1% of the population. The authors concluded that tinnitus is associated with treatable health conditions, such as otitis media, sinusitis, head injuries, noise, and hypertension.  In a study in Australia that evaluated 602 subjects, the buzz was present in 30.3%, being present for at least 6 years in 50% of cases. Despite tinnitus being described as mildly to extremely annoying by 67%, only 37% had sought professional help, and only 6% had received any treatment. 
Especially in the elderly, various metabolic and circulatory disorders that may be associated with exposure to occupational noise can cause various symptoms such as hearing loss, vertigo, and tinnitus. ,,,
The presence of inflammatory cells in the stationary state and its increase after lesions in the inner ear has been reported by several researchers. ,,,
Noise exposure induces expression of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin-1b (IL1b), and interleukin-6 (IL6).  So et al. (2007) reported a transient upregulation of IL6 in animal models treated with cisplatin. Wakabayashi et al. (2010) investigated the effect of inhibiting IL6 using an anti-IL6 antibody (MR16-1) in mice. These authors found that MR16-1 showed a protective effect against noise-induced cochlear damage, mainly due to the suppression of neuronal loss and presumably through the relief of the inflammatory response. Similar data were found by Nakamoto et al. (2012). These authors suggested that the suppression of heat shock transcription factor 1 (HSF-1) proinflammatory cytokine in the cochlea by the administration of geranylgeranylacetone (GGA) can be an important way to protect the inner ear.
The expression of cytokines may be influenced by genetic variation, resulting in pathogenic conditions,  and several studies have investigated single nucleotide polymorphisms (SNPs) as risk factors for inflammatory diseases.  These SNPs may affect the expression, secretion, and cellular transport of interleukins, , and can also decrease the level of IL1 receptor antagonist (IL1Ra), which increases the production and activity of IL1β. 
−174 SNP in the region of the IL6 gene is the exchange of G to C, while the presence of the C allele is a protective function due to reduced production of IL6. 
While tinnitus is a symptom usually related to cochlear change that may arise from noise exposure, this study aimed to evaluate the association between the polymorphism in IL6 and the complaint of tinnitus with a history of occupational noise exposure in the environment by physically independent elderly Brazilians.
| Methods|| |
This cross-sectional study was approved by the Ethics Committee on Human Research of the University of North Paraná (0070/09). It is part of a wider research project, "Study on aging and longevity," which the study has been conducted in Londrina in 2009. The city of Londrina (about 500,000 inhabitants) is located in the northern state of Paraná, Brazil.
From a population of 43,610 elderly enrolled in 38 basic health units in the urban area of the city, the sample size was set at 343 individuals, considering a 95% confidence interval (CI) and a margin of error of 5% 21. With the aim of sampling representativeness, random stratification of regions of the city and gender was done. The study included individuals aged 60 years or more, of both sexes, who were living independently, and at level 3 or 4 according to the classification proposed by Spirduso.  This rating assesses the level of independence of the elderly, with Level 1 indicating a lack of self-mobility and Level 5 indicating athletes. Elderly people who had an illness or limitation preventing the performance of the tests, such as a physical or mental disability, were excluded from the sample. All participants signed a free and informed consent form.
In order to accomplishment of research in relation to the audiologic data, routine audiological evaluation from Audiology Department of the Clinic of Speech, University of Northern Paraná (UNOPAR) based on the protocol for anamnesis by Miller, incluinding question about age, gender and tinnitus. 
Evaluation of occupational noise exposure
The assessment of occupational noise exposure was obtained through interviews with the elderly participants using a semistructured questionnaire. We collected information on the following: If work environment was noisy or not, how many years of work in a noisy environment, and whether they wore hearing aids. In addition, demographic characteristics were collected.
Genotyping for IL6 174G/C (rs1800795) gene polymorphism
Peripheral blood samples were collected in vacuum tubes containing 6% ethylenediaminetetraacetic acid (EDTA), and DNA was extracted from peripheral blood leukocytes, using the protocol described by Olerup and Zetterquist. 
Based on the original sample, the DNA was diluted to a concentration of 100 ng/μL. The concentration was determined by spectrophotometer at 260 nm and 280 nm (Biomate 3, Thermo Fisher Scientific, Madison, Wisconsin USA).
The G-to-C polymorphic site located at position −174 of the IL6 (rs1800795) gene was amplified by polymerase chain reaction (PCR), resulting in a 99-bp fragment. The PCR mixture contained a mixture of a buffer solution pH 8.0, 1× PCR buffer, 1.5 mM of MgCl 2 , 8 mM each of deoxyribonucleotide triphosphates, 1 μM of each primer, and 1 U Taq DNA polymerase (Invitrogen, Carlsbad, CA, USA). The primers used were F: 5'-TTGTCAAGACATGCCAAGTGCT-3' and R: 5' GCCTCAGAGACATCTCCAGTCC-3' (Invitrogen, Carlsbad, CA, USA). 
PCR amplification was performed in a thermocycler (TC-512 Techne resistance, Burlington, NJ, USA) under the following conditions: initial denaturation at 95°C for 5 min followed by 30 cycles of 95°C for 1 min, 56°C for 1 min, and 72°C for 1 min, and final extension at 72°C for 5 min.
The PCR product was digested with 2 U of restriction enzyme NlaIII (Invitrogen, Carlsbad, CA, USA) overnight at 65°C. The digested fragments were separated on 2% agarose gel (Invitrogen Life Technologies, São Paulo, Brazil). A sample with known genotype was used as positive PCR control and ultrapure water was used as negative control.
The 100-bp DNA molecular weight marker (Ladder, Invitrogen, Waltham, Massachusetts, USA) was included on each gel stained with SYBR Safe (Invitrogen Life Technologies, Sγo Paulo, Brazil) and visualized under ultraviolet (UV) illumination. The reading and interpretation of agarose gels were done with the LabImage L-PIX (HE) 1D-L340 (Loccus Biotecnologia, São Paulo, Brazil) program. Fragments of 13 bp, 227 bp, and 59 bp (allele G) and fragments of 13 bp, 118 bp, 109 bp, and 59 bp (allele C) were observed.
Data analysis was performed with IBM SPSS Statistics 20.0 software (IBM Corporation Software Group, New York, USA). To verify the association between genotype frequency and tinnitus related to a history of occupational noise exposure, the chi-square test was performed. The Hardy-Weinberg equilibrium was tested in each group using the chi-square test. The odds ratio (OR) with 95% CI was calculated. The significance level was set at 5%.
| Results|| |
Of the total of 343 subjects, molecular genetics procedures were conducted in 179 elderly. Of these, 33.5% reported noise exposure history, with 42.5% having tinnitus. Of the 66.5% without noise exposure history, 28.5% had tinnitus. The mean age was 68.9 ± 5.25 years, with a higher proportion (65.4%) of female elderly [Table 1].
|Table 1: General characteristics and allele/genotypes frequencies among elderly (N = 179)|
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Of the patients included, 24.6% were homozygous for the G allele, 39.7% were homozygous for the C allele, and 35.8% were heterozygous for IL6 [Table 1]. The genotype distribution for the IL6 gene was in agreement with Hardy-Weinberg equilibrium (P > 0.05).
We found significant association between the genotype and allele frequencies of the IL6 −174 gene (rs1800795) and tinnitus among the elderly with history of exposure to occupational noise (P = 0.03) [Table 2]. The elderly with the C allele were less likely to have tinnitus associated with history of exposure to occupational noise (OR = 0.167, CI 95% 0.167-0.749; P = 0.004) when compared to those carrying the G allele.
|Table 2: Association between genotype frequency for the IL6 174G/C gene polymorphism and tinnitus related to history of occupational noise exposure (N = 179)|
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However, we did not find any significant association between the genotypic frequency of the IL6 -174 gene (rs1800795) and tinnitus among the elderly without considering history of exposure to occupational noise [Table 3].
|Table 3: Association between genotype frequency for the IL6 174G/C gene polymorphism and tinnitus (N = 179)|
Click here to view
| Discussion|| |
Tinnitus is more challenging than many other health conditions because there is no objective measurement of the condition and no consensus regarding diagnostic assessment.  Although the mechanism and the role of proinflammatory cytokines in noise-induced hearing loss (NIHL) and tinnitus are not yet well understood, the SNP present results in obvious pathological consequences (Satoh et al. 2003). The functionality of SNPs with respect to gene expression is an important subject for disease association studies (Dinarello 2011) and may be useful regarding diagnostic approach in tinnitus.
An association was found between the IL6 allele and tinnitus with history of exposure to occupational noise (χ2 = 6.771; P = 0,031). The elderly with the C allele are less likely to have tinnitus as a result of occupational exposure to noise when compared to those carrying the G allele (OR = 0.167, CI 95%, 0.037-0.749; P = 0.019). However, it is stated that the presence of the C allele results in a lower expression of IL6 after an inflammatory stimulus compared with the G allele, based on the belief that the CC genotype confers a protective effect against the development of comorbidities. 
Fujioka et al.  indicated the possibility of inflammatory changes in the cochlea after noise stimulus, and demonstrated for the first time the induction of proinflammatory cytokines in the cochlea exposed to noise and observed the increased expression of TNF-α, IL1b and IL6, 3 h after noise exposure. These authors pointed out that this mechanism is self-protection against exposure to large amounts of noise, and the consequent excessive expression of interleukins for long periods should worsen the cochlear function.
So et al.  showed that IL6 acts as an inducer of acute cochlear damage, as after exposure the animals with cisplatin IL6, there was a transient upregulation. Some studies have shown that inhibition of IL6 production presents a cochlear protective effect. Wakabayashi et al.  used anti-IL6 antibody (MR10-1) to inhibit IL6 production in mice by finding a protective effect for noise-induced cochlear injury. Along the same line of research, Nakamoto et al.  found that GGA stimulates expression of the HSF gene, which, in turn, inhibits the inflammation of the inner ear protecting the cochlea.
It should be noted that these strong evidences of the association of IL6 with cochlear changes related to noise have been observed through research in animal models. ,,,
Evidence in humans related to proinflammatory interleukins and NIHL was recently reported by our group, were we investigated the association between the polymorphism of the interleukin (IL)-1β gene with complaints of hearing loss due to occupational noise exposure. The polymorphism in this gene has not been shown to be associated with NIHL in the evaluated elderly.  But subsequent findings showed that polymorphism in the IL6 gene should contribute to the risk of NIHL in elderly Brazilians. 
A recent study cites that inflammatory responses occur in the inner ear under various adverse conditions, including overstimulation with noise, although an association between the proinflammatory cytokines is rarely reported.  In addition, a study of a relaxing training program indicated that in individuals with chronic tinnitus symptoms, it can lead to significant reduction of stress, depression, anger, and perception of tinnitus, in parallel with a reduction of TNF-α. 
In this study, it can be seen that the frequency of G allele was higher in the group of elderly with history of occupational noise exposure and tinnitus (n = 28) than in the group with no history of occupational noise exposure and tinnitus (n = 18).
| Conclusion|| |
An association between the polymorphism of the IL6 gene in the region 174G/C and tinnitus in elderly with history of occupational noise exposure was found. The elderly with the C allele were less likely to have tinnitus associated with history of exposure to occupational noise (OR = 0.167, CI 95% 0.167-0.749; P = 0.004) when compared to those carrying the G allele.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Shrestha LB. Population aging in developing countries. Health Aff (Millwood) 2000;19:204-12.
Kinsella K, He W. An Aging World: 2008. Washington: U.S. Census Bureau; 2009. p. 2-17.
Veras R. Envelhecimento populacional contemporâneo: Demandas, desafios e inovações. Rev de Saúde Pública 2009;43:548-54.
Conrad I, Kleinstäuber M, Jasper K, Hiller W, Andersson G, Weise C. The role of dysfunctional cognitions in patients with chronic tinnitus. Ear Hear 2015;36:e279-89.
Sanchez TG, Ferrari GM. O que é zumbido? In: Samelli AG, editor. Zumbido: Avaliação, Diagnóstico e Reabilitação: Abordagens Atuais. São Paulo: Lovise; 2004. p. 17-22.
Lasisi AO, Abiona T, Gureje O. Tinnitus in the elderly: Profile, correlates, and impact in the Nigerian Study of Ageing. Otolaryngol Head Neck Surg 2010;143:510-5.
Sindhusake D, Mitchell P, Newall P, Golding M, Rochtchina E, Rubin G. Prevalence and characteristics of tinnitus in older adults: The Blue Mountains Hearing Study. Int J Audiol 2003;42:289-94.
Marchiori LL. Tinnitus complaint and blood hypertension in the aging process. Rev Bras Hipertens 2009;16:5-8.
Melo JJ, Meneses CL, Marchiori LL. Prevalence of tinnitus in elderly individuals with and without history of occupational noise exposure. Int Arch Otorhinolaryngol 2012;16:222-5.
Ferreira LM, Ramos AN Jr, Mendes EP. Caracterização do zumbido em idosos e de possíveis transtornos relacionados. Rev Bras Otorrinolaringol 2009;75:245-8.
Tan BT, Lee MM, Ruan R. Bone-marrow-derived cells that home to acoustic deafened cochlea preserved their hematopoietic identity. J Comp Neurol 2008;509:167-79.
Fujioka M, Kanzaki S, Okano HJ, Masuda M, Ogawa K, Okano H. Proinflammatory cytokines expression in noise-induced damaged cochlea. J Neurosci Res 2006;83:575-83.
So H, Kim H, Lee JH, Park C, Kim Y, Kim E, et al
. Cisplatin cytotoxicity of auditory cells requires secretions of proinflammatory cytokines via activation of ERK and NF-kappaB. J Assoc Res Otolaryngol 2007;8:338-55.
Wakabayashi K, Fujioka M, Kanzaki S, Okano HJ, Shibata S, Yamashita D, et al
. Blockade of interleukin-6 signaling suppressed cochlear inflammatory response and improved hearing impairment in noise-damaged mice cochlea. Neurosci Res 2010;66:345-52.
Satoh H, Firestein GS, Billings PB, Harris JP, Keithley EM. Proinflammatory cytokine expression in the endolymphatic sac during inner ear inflammation. J Assoc Res Otolaryngol 2003;4:139-47.
Dinarello CA. Interleukin-1 in the pathogenesis and treatment of inflammatory diseases. Blood 2011;117:3720-32.
Hwang JH, Chen JC, Yang SY, Wang MF, Chan YC. Expression of tumor necrosis factor-α and interleukin-1 β genes in the cochlea and inferior colliculus in salicylate-induced tinnitus. J Neuroinflammation 2011;8:30.
Santtila S, Savinainen K, Hurme M. Presence of the IL-1RA allele 2 (IL1RN*2) is associated with enhanced IL-1beta production in vitro
. Scand J Immunol 1998;47:195-8.
Bioque G, Crusius JB, Koutroubakis I, Bouma G, Kostense PJ, Meuwissen SG, et al
. Allelic polymorphism in IL-1 beta and IL-1 receptor antagonist (IL-1Ra) genes in inflammatory bowel disease. Clin Exp Immunol 1995;102:379-83.
Costa AM, Guimarães MC, de Souza ER, Nóbrega OT, Bezerra AC. Interleukin-6 (174G/C) and tumour necrosis factor-alpha (G-308A) gene polymorphisms in geriatric patients with chronic periodontitis. Gerodontology 2010;27:70-5
Spirduso WW. Physical Dimensions of Aging. 2 nd
ed. Barueri: Manole; 2005. p. 75-80.
Miller MH. A integração dos achados audiológicos. In: Katz J, editor. Tratado de audiologia clínica. 3 rd
ed. São Paulo: Manole; 1999. p. 268-70.
Olerup O, Zetterquist H. HLA-DR typing by PCR amplification with sequence-specific primers (PCR-SSP) in 2 hours: An alternative to serological DR typing in clinical practice including donor-recipient matching in cadaveric transplantation. Tissue Antigens 1992;39:225-35.
Olomolaiye O, Wood NA, Bidwell JL. A novel NlaIII polymorphism in the human IL-6 promoter. Eur J Immunogenet 1998;25:267.
Martinez C, Wallenhorst C, McFerran D, Hall DA. Incidence rates of clinically significant tinnitus: 10-year trend from a cohort study in England. Ear Hear 2015;36:e69-75.
Fishman D, Faulds G, Jeffery R, Mohamed-Ali V, Yudkin JS, Humphries S, et al
. The effect of novel polymorphisms in the interleukin-6 (IL-6) gene on IL-6 transcription and plasma IL-6 levels, and an association with systemic-onset juvenile chronic arthritis. J Clin Invest 1998;102:1369-76.
Nakamoto T, Mikuriya T, Sugahara K, Hirose Y, Hashimoto T, Shimogori H, et al
. Geranylgeranylacetone suppresses noise-induced expression of proinflammatory cytokines in the cochlea. Auris Nasus Larynx 2012;39:270-4.
Carvalho LC, Marchiori LL, Melo JJ, Maciel SM, Poli-Frederico RC. Interleukin-1β gene polymorphism and hearing loss related to the history of occupational noise exposure in Brazilian elderly. Noise Health 2013;15:160-4.
Braga MP, Maciel SM, Marchiori LL, Poli-Frederico RC. Association between interleukin-6 polymorphism in the -174 G/C region and hearing loss in the elderly with a history of occupational noise exposure. Braz J Otorhinolaryngol 2014;80:373-8.
Weber C, Arck P, Mazurek B, Klapp BF. Impact of a relaxation training on psychometric and immunologic parameters in tinnitus sufferers. J Psychosom Res 2002;52:29-33.
Luciana Lozza de Moraes Marchiori
Department of Audiology and Speech Therapy, Centre of Research in Health Sciences, University of Northern Parana (UNOPAR), Paris Avenue 675, Jd. Piza, CEP 86041-140, Londrina, PR
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2], [Table 3]
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