PON2 and ATP2B2 gene polymorphisms with noise-induced hearing loss

Protective effect of ginsenoside Rd on military aviation noise-induced cochlear hair cell damage in guinea pigs

Noise pollution has become one of the important social hazards that endanger the auditory system of residents, causing noise-induced hearing loss (NIHL). Oxidative stress has a significant role in the pathogenesis of NIHL, in which the silent information regulator 1(SIRT1)/proliferator-activated receptor-gamma coactivator 1α (PGC-1α) signaling pathway is closely engaged. Ginsenoside Rd (GSRd), a main monomer extract from ginseng plants, has been confirmed to suppress oxidative stress. Therefore, the hypothesis that GSRd may attenuate noise-induced cochlear hair cell loss seemed promising. Forty-eight male guinea pigs were randomly divided into four groups: control, noise exposure, GSRd treatment (30 mg/kg Rd for 10d + noise), and experimental control (30 mg/kg glycerol + noise). The experimental groups received military helicopter noise exposure at 115 dB (A) for 4 h daily for five consecutive days. Hair cell damage was evaluated by using inner ear basilar membrane preparation and scanning electron microscopy. Terminal dUTP nick end labeling (TUNEL) and immunofluorescence staining were conducted. Changes in the SIRT1/PGC-1α signaling pathway and other apoptosis-related markers in the cochleae, as well as oxidative stress parameters, were used as readouts. Loss of outer hair cells, more disordered cilia, prominent apoptosis, and elevated free radical levels were observed in the experimental groups. GSRd treatment markedly mitigated hearing threshold shifts, ameliorated outer hair cell loss and lodging or loss of cilia, and improved apoptosis through decreasing Bcl-2 associated X protein (Bax) expression and increasing Bcl-2 expression. In addition, GSRd alleviated the noise-induced cochlear redox injury by upregulating superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels, decreasing malondialdehyde (MDA) levels, and enhancing the activity of SIRT1 and PGC-1α messenger ribonucleic acid (mRNA) and protein expression. In conclusion, GSRd can improve structural and oxidative damage to the cochleae caused by noise. The underlying mechanisms may be associated with the SIRT1/PGC-1α signaling pathway.

The Role of Genetic Variants in the Susceptibility of Noise-Induced Hearing Loss

Noised-induced hearing loss (NIHL) is an acquired, progressive neurological damage caused by exposure to intense noise in various environments including industrial, military and entertaining settings. The prevalence of NIHL is much higher than other occupational injuries in industrialized countries. Recent studies have revealed that genetic factors, together with environmental conditions, also contribute to NIHL. A group of genes which are linked to the susceptibility of NIHL had been uncovered, involving the progression of oxidative stress, potassium ion cycling, cilia structure, heat shock protein 70 (HSP70), DNA damage repair, apoptosis, and some other genes. In this review, we briefly summarized the studies primary in population and some animal researches concerning the susceptible genes of NIHL, intending to give insights into the further exploration of NIHL prevention and individual treatment.

Polymorphisms in the FAS gene are associated with susceptibility to noise-induced hearing loss

This study investigated the relationship between genetic polymorphisms in the FAS gene and noise-induced hearing loss (NIHL) risk among Chinese workers exposed to occupational noise, and the molecular mechanism of NIHL caused by noise. In this case-control study, 692 NIHL workers and 650 controls were selected for genotyping of four single nucleotide polymorphisms (SNPs) of the FAS gene. Logistic regression was used to calculate the odds ratio (OR) and 95% confidence interval (CI) of the association of these genetic polymorphisms and NIHL. At the same time, a noise-exposed rat model was constructed to further clarify the effect of noise exposure on fas gene expression and the pathogenic mechanism of NIHL. Two polymorphisms, rs1468063 and rs2862833, were associated with NIHL in the case-control study. Individuals with the rs1468063-TT or rs2862833-AA genotypes had decreased NIHL risk (p < 0.01, p = 0.02, respectively). Compared with the control group, the hearing threshold of the case group of rats increased, while serum MDA, urine 8-OHdG, and fas gene expression increased, but let-7e expression decreased. Genetic polymorphisms in the FAS gene are related to the risk of NIHL in the Chinese population. Noise can cause a large amount of reactive oxygen species (ROS) in the cochlea tissue and blood, which lead to oxidative stress, lipid peroxidation, and DNA damage, further activating the FAS gene, and ultimately leading to hearing loss.

Human Paraoxonase-2 (PON2): Protein Functions and Modulation

PON1, PON2, and PON3 belong to a family of lactone hydrolyzing enzymes endowed with various substrate specificities. Among PONs, PON2 shows the highest hydrolytic activity toward many acyl-homoserine lactones (acyl-HL) involved in bacterial quorum-sensing signaling. Accordingly, defense against pathogens, such as Brevundimonas aeruginosa (B. aeruginosa), was postulated to be the principal function of PON2. However, recent findings have highlighted the importance of PON2 in oxidative stress control, inhibition of apoptosis, and the progression of various types of malignancies. This review focuses on all of these aspects of PON2.

An overview of research trends and genetic polymorphisms for noise-induced hearing loss from 2009 to 2018

Recently, there has been increased studies in noise-induced hearing loss (NIHL). We aimed to make an overview of research trends and genetic polymorphisms for NIHL from 2009 to 2018 with VOSviewer software. A total of 2391 papers were identified for research trends analysis in NIHL and 33 studies identified for a brief review of genetic polymorphisms in human NIHL. The number of publications has been increasing over the past decade. The journal Hearing Research published the most articles (218). The USA contributed the largest number of papers (1042; 43.58%), with the most citations (18,987) and the highest H-index (60). The University of Washington was the most contributive institution. Liberman MC published the most articles (32), and Kujawa SG possessed the highest co-citations (584). Except for high-frequency keywords identified by the software, "prevalence," "oxidative stress," "hair cells," and "cochlear implant" were also the latest research frontiers. HSPA1A rs1043618, HSPA1L rs2227956, PON2 rs12026 and rs7785846, SOD2 rs2855116, KCNE1 rs2070358, KCNQ4 rs34287852, GJB2 rs3751385, PCDH15 rs7095441 and rs11004085, GRHL2 rs1981361, ITGA8 rs10508489, MYH14 rs667907, and POU4F3 rs891969 were the research hotspots and were replicated in independent samples. Inflammation response underlying NIHL has emerged and should be considered as a pioneering field in the future for the prevention of NIHL and conservation of hearing.

Open chromatin dynamics in prosensory cells of the embryonic mouse cochlea

Hearing loss is often due to the absence or the degeneration of hair cells in the cochlea. Understanding the mechanisms regulating the generation of hair cells may therefore lead to better treatments for hearing disorders. To elucidate the transcriptional control mechanisms specifying the progenitor cells (i.e. prosensory cells) that generate the hair cells and support cells critical for hearing function, we compared chromatin accessibility using ATAC-seq in sorted prosensory cells (Sox2-EGFP⁺) and surrounding cells (Sox2-EGFP⁻) from E12, E14.5 and E16 cochlear ducts. In Sox2-EGFP⁺, we find greater accessibility in and near genes restricted in expression to the prosensory region of the cochlear duct including Sox2, Isl1, Eya1 and Pou4f3. Furthermore, we find significant enrichment for the consensus binding sites of Sox2, Six1 and Gata3—transcription factors required for prosensory development—in the open chromatin regions. Over 2,200 regions displayed differential accessibility with developmental time in Sox2-EGFP⁺ cells, with most changes in the E12-14.5 window. Open chromatin regions detected in Sox2-EGFP⁺ cells map to over 48,000 orthologous regions in the human genome that include regions in genes linked to deafness. Our results reveal a dynamic landscape of open chromatin in prosensory cells with potential implications for cochlear development and disease.

Paraoxonases Activities and Polymorphisms in Elderly and Old-Age Diseases: An Overview

Aging is defined as the accumulation of progressive organ dysfunction. There is much evidence linking the involvement of oxidative stress in the pathogenesis of aging. With increasing age, susceptibility to the development of diseases related to lipid peroxidation and tissue injury increases, due to chronic inflammatory processes, and production of reactive oxygen species (ROS) and free radicals. The paraoxonase (PON) gene family is composed of three members (PON1, PON2, PON3) that share considerable structural homology and are located adjacently on chromosome 7 in humans. The most studied member product is PON1, a protein associated with high-density lipoprotein with paraoxonase/esterase activity. Nevertheless, all the three proteins prevent oxidative stress. The major aim of this review is to highlight the importance of the role of PON enzymes in the aging process, and in the development of the main diseases present in the elderly: cardiovascular disease, diabetes mellitus, neurodegenerative diseases, and cancer.

[The genetic aspects of occupational hearing impairment]

This article was designed to be the overview of the current literature publications concerning the identification of the genetic markers of susceptibility to the noise-induced loss of hearing. The analysis of these data has demonstrated that the major gene polymorphisms associated with the development of this pathological condition are localized in the genes encoding for the antioxidant systems, potassium homeostasis, and adhesion molecules as well as in the genes involved in intercellular coupling, the mechanisms underlying the cellular response to stress, activation and regulation of heat shock proteins, and signaling function of the immune system. It is concluded that the further investigations into the genetic aspects of the full-genome sequencing techniques and the search for genomic associations could greatly contribute to the development of personalized medicine and the reduction of risks of occupational noise-induced sensorineural impairment of hearing.

Cross-sectional associations between genetic polymorphisms in metabolic enzymes and longer leukocyte telomere length induced by omethoate

Purpose

This study aimed to explore the effects of genetic polymorphisms in metabolic enzymes on relative telomere length changes and explore the mechanism of canceration induced by omethoate.

Materials and Methods

180 long-term omethoate-exposed workers and 115 healthy controls were recruited. Real-time PCR method was applied to determine the relative telomere length in peripheral blood leukocytes DNA, and Six polymorphic loci of GSTT1(+/−), GSTM1(+/−), GSTP1 rs1695, CYP2E1 rs6413432, CYP2E1 rs3813867 and PON2 rs12026 were detected by polymerase chain reaction and restriction fragment length polymorphism method; Multiple linear regression was conducted to explore the effects of omethoate exposure and genetic polymorphisms on the telomere length.

Results

The relative telomere lengths in the control group (0.94 [0.76, 1.32]) were significantly shorter than that in the exposure group (1.50 [1.11, 2.57]) (Z = 7.910, P < 0.001). Univariate analysis showed that the relative telomere lengths of the GSTM1-deletion individuals were significantly longer than that of the non - deletion genotype in the control group (Z = 2.911, P = 0.004), and the relative telomere lengths of GSTP1 rs1695 polymorphism locus (GG+AG) genotype individuals were longer than that of AA genotype in the exposure group. The difference was statistically significant (Z = 2.262, P = 0.024). Multivariate analysis found that pesticide-exposure (b = 0.524, P < 0.001) and GSTM1 polymorphism (b = −0.136, P = 0.029) had an impact on telomere length.

Conclusions

The relative telomere lengths of omethoate-exposure workers were longer than that in the control population. Also GSTM1 genetic polymorphism may influence the changes of the telomere length induced by omethoate.