miR-210 regulates the inflammation of otitis media with effusion by inhibiting the expression of hypoxia-inducible factor (HIF)-1a

https://doi.org/10.1016/j.bbrc.2020.11.068Get rights and content

Highlights

  • MiR-210 expression level reduced in serum and middle ear effusion of OME patients.

  • ∙miR-210 expression level is closed to bone conduction disorders of OME patients.

  • ∙miR-210 regulate inflammation level, cell viability and apoptosis in HMEEC cells by targeting HIF-1a.

Abstract

Otitis media with effusion (OME) is the major cause of hearing impairment in children. miR-210 plays a critical role in inflammatory diseases, however, its role in OME is unknown. In this study, the miR-210 level in serum and middle ear effusion of is significantly down-regulated in serum, middle ear effusion from OME patients (100 cases) compared with healthy volunteers (50 cases). The expression of miR-210 is closely related to inflammatory factors and bone conduction disorder in patients with OME. In the in vitro study,the miR-210 level is significantly reduced in culture supernatant of lipopolysaccharide (LPS) treated human middle ear epithelial cells (HMEECs). miR-210 overexpression inhibited the LPS-induced in inflammatory cytokines production, cell viability reduction and cell apoptosis. Bioinformatics and dual-luciferase reporter assay showed that HIF-1a was a target gene of miR-210. The biological effects of miR-210 on cell viability, cell apoptosis and inflammation cytokines in LPS-induced HMEECs were reversed by HIF-1a overexpression. Furthermore, phosphorylation of NF-κB p65 was significantly decreased by miR-210 mediated HIF-1a in LPS-induced HMEECs. This study suggested that miR-210 may play a role in OME. Further studies are warranted to assess miR-210 as a potential target for the diagnosis and treatment of OME.

Introduction

Otitis media with effusion (OME) exhibits a middle ear effusion in the absence of symptoms of acute ear infection and is one of main reasons of hearing impairment in children [1,2]. The etiology of OME is initiated by many factors, including upper respiratory tract infection, eustachian tube dysfunction, iron deficiency, gastroesophageal reflux disease and middle ear bacterial infection [3,4]. The clinical synonyms for OME mainly manifests ear fluid, secretory, or nonsuppurative otitis media [3]. Currently, a combination of watchful waiting, medical therapy and surgical intervention is used for treatment of OME [5,6]. However, the current therapies are limited, so some potential targeted therapeutics for OME needs to be explored. Molecular signaling involved in the pathophysiology of OME may offer novel alternatives for OME targeted therapy, however the molecular mechanism that contributes to OME pathogenesis remain unknown.

MicroRNAs (miRNAs) are a class of small non-coding RNAs that are 19–22 nucleotides in length that regulate gene expression of different biological processes by binding to target 3’ UTR of mRNAs, then directing targeting mRNAs degradation or translational inhibition [7,8]. Previous studies showed that some miRNAs involved in the occurrence and progression of otologic pathologies including Otitis media [9,10]. Hypoxia is the common pathogenic characteristics of inflammation and other pathological states. microRNA-210 (miR-210) is the Master Hypoxamir due to its high hypoxia-inducible characteristics [11,12]. Previous reports confirmed that miR-210 inhibition induces neuroprotection by ameliorating mitochondrial dysfunction, oxidative stress, and neuronal loss in hypoxic-ischemic brain injury and increased glucocorticoid receptor protein abundance [13,14]. In addition, miR-210 as an oncogene plays a key role in cancer cell proliferation, apoptosis, invasion and metastasis by regulating hypoxia-related targeting gene expression [[15], [16], [17]].

Hypoxia-inducible factor-1 alpha (HIF-1α) is an oxygen-dependent transcriptional activator, which plays critical roles in the innate immunity, proinflammatory gene expression, antibacterial activities and cell migration [18,19]. The mice model of HIF-1α myeloid-specific deletion reveals impaired inflammatory responses. In neutrophils, hypoxia induces survival of neutrophil cells by HIF-1a-dependent NF-kB activity that results in sustained inflammation [20]. Selective ablation of HIF-prolyl hydroxylase 3 (PHD3) in neutrophils reduces neutrophilic inflammation in a colitis model [21]. In summary, the relationship between the hypoxic and inflammatory is closely regulated by the hypoxia pathway.

In this study, we found that the expression level of miR-210 in serum and middle ear effusion of patients with OME significantly reduced. In addition, we demonstrated the effect of miR-210 on cell viability, cell apoptosis and inflammation through targeting HIF-1a in human middle ear epithelial cells (HMEEC) cells. Our results confirmed biologic function of miR-210 in OME.

Section snippets

Clinical data

100 OME patients were collected in our hospital from January 2019 to January 2020. The inclusive criteria were as follows: I) patients diagnosed as unilateral OME with bone conduction hearing level lower than 30 dB at each frequency of normal contralateral ear; Ⅱ) patients under 50 years old with a course of less than 30 days; Ⅲ) patients without specific causes of sensorineural hearing loss such as systemic ototoxicity drugs, head injury, noise exposure; IV) patients willing to undergo

Demographics assay

The study population consisted of 59 male (59.00%) and 41 females (41.00%) and the mean age was 16.22 ± 6.18. The control group consisted of 50 male (50.00%) and 50 females (50.00%) and the mean age was 15.69 ± 5.91. Thirty out of 100 (30.00%) patients had bone conduction hearing impairment in the OME group and one out of 100 (1.00%) patients had one conduction hearing impairment in the control group (P < 0.05). Seventy-two out of 100 (72.00%) patients had upper respiratory tract infections in

Discussion

In the present study, we showed that miR-210 expression level significantly reduced in serum and middle ear effusion of otitis media patients with effusion and in LPS-treated HMEEC cells. LPS treatment significantly inhibited cell viability, promoted cell apoptosis and inflammatory cytokines in HMEEC cells. Furthermore, overexpressed miR-210 mimic can significantly promote cell viability, down-regulate cell apoptosis and inflammation level in LPS induced HMEEC cells. In addition, HIF-1a is a

Declaration of competing interest

The authors declare that they have no conflicts of interest to disclose.

Acknowledgements

This study is supported by Foundation of Zhejiang Provincial Education Department (Grant No. Y201942045) and Science and Technology program of yiwu Science and Technology Bureau (Grant No. 18-3-26).

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