Cochlin expression in vestibular endorgans obtained from patients with Meniere’s disease

Abstract

The distribution of cochlin and its associated basement membrane proteins (collagen IV, collagen II, laminin-β2, and nidogen-1) was evaluated in the vestibular endorgans of subjects with Meniere’s disease and compared to normal specimens. Cochlin mRNA expression in vestibular endorgans from Meniere’s disease specimens was also investigated. Specimens were obtained from patients with Meniere’s disease who underwent ablative labyrinthectomy. Control specimens were obtained from both autopsy specimens with documented normal audiovestibular function and from patients undergoing labyrinthectomy for acoustic neuroma excision. In the normal control specimens, cochlin immunoreactivity was found evenly distributed in the stroma of the cristae ampullaris and maculae of the utricle. In Meniere’s specimens, cochlin immunoreactivity was markedly increased, which was associated with an increase in cochlin mRNA expression on real-time RT-PCR. Collagen IV and laminin-β2 immunoreactivity was significantly decreased in Meniere’s specimens. Nidogen-1 and collagen II immunoreactivity were unchanged in Meniere’s specimens when compared with normal specimens. Cochlin upregulation has been implicated in the hereditary audiovestibulopathy, DFNA9. The increased expression of cochlin and decreased expression of collagen IV and laminin in Meniere’s disease are suggestive that overexpression of cochlin may contribute to the dysfunctional inner ear homeostasis seen in Meniere’s disease.

Immunohistochemical techniques for the human inner ear

“…Formalin-fixed microdissected auditory and vestibular endorgans obtained from human temporal bone specimens have been successfully used to study the immunolocalization of aquaporins, several basement membrane proteins and cochlin in the vestibular endorgans and the cochlea (Lopez et al 2007; Ishiyama et al 2009, 2010; Calzada et al 2012a, b). Using the microdissection technique, the three cristae ampullares, maculae utricle and saccule, as well as the organ of Corti, are removed from the otic capsule of the temporal bone and separately processed for either light or transmission electron microscopic examination (Wright and Meyerhoff 1989).…”

“…In the human inner ear, the feasibility and utility of cryosections for IHC have been demonstrated with immunolocalization of several neurotransmitters and peptides (Ishiyama et al 1994; Kong et al 1998; Popper et al 2002), aquaporins (Lopez et al 2007), basement membrane proteins (Ishiyama et al 2009) and cochlin (Calzada et al 2012a, b). Surgically obtained cochlear and vestibular endorgans can also be processed into cryosections and used for IHC (Calzada et al 2012a, b; Ishiyama et al 2010; Liu et al 2009, 2015, 2016; Khalifa et al 2003). Khalifa et al (2003) and Rask-Andersen et al (2000 and Rask-Andersen et al (2016) used fresh surgically acquired human inner ear specimens to localize several proteins by IHC in the cochlea and spiral ganglia neurons.…”

Recent Research Trend for Ménièreʼs Disease

“…The subepithelial basement membrane, which lies interposed between the epithelium facing the endolymph and the connective stromal tissue within the perilymph, is markedly thickened and under TEM appears to be disorganized fibrils 26 . Additionally, the composition of the subepithelial basement membrane is altered: collagen IV expression is diminished 46 , and the sub-epithelial basement membrane thickening correlated with neuroepithelial damage and vestibular hair cell loss 26 . In Meniere's disease, both the sub-epithelial basement membrane and the capillary perivascular basement membrane forming the blood-perilymph barrier, exhibit thickening, edema, and disorganization in comparison with the normal basement membrane which is homogeneous, thin, with a continuous appearance due to a condensed filamentous pattern and homogeneous matrix.…”

The expression of glutamate aspartate transporter (GLAST) within the human cochlea and its distribution in various patient populations

“…The GLAST distribution in the spiral ligament was quantified at the apical, middle, and basal turns of the cochlea as per the protocol previously described by Ishiyama et al and Calzada et al (2010; 2012). To minimize bias, the first author was blinded to the identity of the tissue samples being analyzed.…”