Cochlin Expression in Patients with Ménière Disease

Abstract

Objective: 1) Determine the distribution of cochlin in the vestibular endorgans of patients with Ménière disease (MD) through quantitative immunohistochemistry and real-time PCR (RT-PCR). 2) Compare cochlin expression in the vestibular endorgans in normal vs MD patients. 3) Correlate changes in cochlin expression with underlying pathophysiology in MD. Method: Vestibular endorgans were obtained from 8 patients with MD who underwent ablative labyrinthectomy from 1997 to 2010. Control specimens were obtained from 8 patients undergoing labyrinthectomy for acoustic neuroma excision and 5 autopsy specimens with normal audiovestibular function. Quantitative immunohistochemistry of cochlin expression and RT-PCR were performed in vestibular endorgans. Results: In the normal control specimens, cochlin immunoreactivity (IR) was found evenly distributed in the stroma of the cristae ampullaris and maculae of the utricle. In the MD specimens, cochlin IR was markedly increased and intense. Diffuse cochlin precipitate was found within the stroma and basement membrane underlying the sensory epithelium in both the maculae of the utricle and the cristae ampullaris in vestibular endorgans from MD patients. Increased cochlin expression in MD specimens was confirmed with RT-PCR. Conclusion: Cochlin upregulation has been implicated in DFNA9, a hereditary audiovestibulopathy with similar symptomatology to MD. The overexpression of cochlin in vestibular endorgans of MD patients may contribute to dysfunctional inner ear homeostasis. These findings warrant the future study of cochlin and its associated extracellular matrix molecules in MD pathology.