Distinct MicroRNA Profiles in the Perilymph and Serum of Patients With Menière's Disease

Abstract

Hypothesis: Menière's disease microRNA (miRNA) profiles are unique and are reflected in the perilymph and serum of patients.Background: Development of effective biomarkers for Menière's disease are needed. miRNAs are small RNA sequences that downregulate mRNA translation and play a significant role in a variety of disease states, ultimately making them a promising biomarker. miRNAs can be readily isolated from human inner ear perilymph and serum, and may exhibit disease-specific profiles.Methods: Perilymph sampling was performed in 10 patients undergoing surgery; 5 patients with Meniere's disease and 5 patients with otosclerosis serving as controls. miRNAs were isolated from the serum of 5 patients with bilateral Menière's disease and compared to 5 healthy age-matched controls. For evaluation of miRNAs an Agilent miRNA gene chip was used. Analysis of miRNA expression was carried out using Qlucore and Ingenuitey Pathway Analysis software. Promising miRNAs biomarkers were validated using qPCR.Results: In the perilymph of patients with Menière's disease, we identified 16 differentially expressed miRNAs that are predicted to regulate over 220 different cochlear genes. Six miRNAs are postulated to regulate aquaporin expression and twelve miRNAs are postulated to regulate a variety of inflammatory and autoimmune pathways. When comparing perilymph with serum samples, miRNA-1299 and−1270 were differentially expressed in both the perilymph and serum of Ménière's patients compared to controls. Further analysis using qPCR confirmed miRNA-1299 is downregulated over 3-fold in Meniere's disease serum samples compared to controls.Conclusions: Patients with Ménière's disease exhibit distinct miRNA expression profiles within both the perilymph and serum. The altered perilymph miRNAs identified can be linked to postulated Ménière's disease pathways and may serve as biomarkers. miRNA-1299 was validated to be downregulated in both the serum and perilymph of Menière's patients.

Metabolomic Studies in Inner Ear Pathologies

“…Previous studies have identified endolymphatic hydrops in these patients. However, the pathophysiological mechanisms are not yet fully understood, although genetic, vascular, immunological origin, the aberrant expression of aquaporins, or a combination of causes have been proposed [ 27 ]. Several research teams have been interested in identifying biomarkers and mechanisms in this pathology.…”

“…Several research teams have been interested in identifying biomarkers and mechanisms in this pathology. Using miRNA profiles, some authors found altered perilymph linked with Ménière’s disease, which could serve as a potential biomarker [ 27 ]. Proteonomic analysis has allowed for the identification of protein short-chain dehydrogenase/reductase family 9C member 7 in perilymph from patients with Ménière’s disease [ 28 ].…”

Up-Regulated Expression of Interferon-Gamma, Interleukin-6 and Tumor Necrosis Factor-Alpha in the Endolymphatic Sac of Meniere's Disease Suggesting the Local Inflammatory Response Underlies the Mechanism of This Disease

“…As EH has been proposed to result from a disturbance in endolymphatic volume regulation that is associated with changes in the microenvironment of luminal fluid of the ES (12), understanding the molecular pathomechanism(s) underpinning the regulation of the immune reaction in the luminal fluids of ES is important both for furthering our knowledge of the physiopathology of EH and for identifying biomarkers for diagnosis or prognosis of pathologies of the MD. Recently, there has been a growing interest in developing a "liquid biopsy" of the inner ear as a surrogate for tissue biopsy to identify molecular biomarkers (13)(14)(15)(16). Proteomics analysis in samples of perilymph (13) and ES luminal fluid (ELF) (14,15) from patients with MD and controls suggested that increased inflammatory reactions Abbreviations: MD, Meniere's disease; EH, endolymphatic hydrops; ES, endolymphatic sac; ELF, ES luminal fluid; AN, acoustic neuroma; EDB, endolymphatic duct blockage; TNF-α, tumor necrosis factor α; IFN-γ, interferon-γ; IL, interleukin; Simoa, single-molecular array; RGP, resorufin β-D-galactopyranoside; PBST, triton-phosphate buffered saline; DAPI, 4 ′ ,6diamidino-2-phenylindole; ANOVA, analysis of variance; IF, immunofluorescence; SNHL, sensorineural hearing loss.…”

“…As EH has been proposed to result from a disturbance in endolymphatic volume regulation that is associated with changes in the microenvironment of luminal fluid of the ES ( 12 ), understanding the molecular pathomechanism(s) underpinning the regulation of the immune reaction in the luminal fluids of ES is important both for furthering our knowledge of the physiopathology of EH and for identifying biomarkers for diagnosis or prognosis of pathologies of the MD. Recently, there has been a growing interest in developing a “liquid biopsy” of the inner ear as a surrogate for tissue biopsy to identify molecular biomarkers ( 13 – 16 ). Proteomics analysis in samples of perilymph ( 13 ) and ES luminal fluid (ELF) ( 14 , 15 ) from patients with MD and controls suggested that increased inflammatory reactions in the inner ear may contribute to the pathology of MD.…”

“…Proteomics analysis in samples of perilymph ( 13 ) and ES luminal fluid (ELF) ( 14 , 15 ) from patients with MD and controls suggested that increased inflammatory reactions in the inner ear may contribute to the pathology of MD. The results of the micro(mi)RNA expression profiles of perilymph from patients with MD and patients with otosclerosis indicated that 12 of the 16 miRNAs unique to MD were directly predicted to regulate inflammation and/or autoimmune pathways ( 16 ). However, The MD-specific changes accounting for the observed inflammation in the microenvironment of luminal fluid of the ES have to be validated through additional studies with a larger number of samples, also including the identification of the molecular target(s) of these samples from performing “liquid biopsy” in patients with MD.…”