Cochlear and Renal Pathology in Murine Lupus

Abstract

We investigated the role of immunological mechanisms in sensorineural hearing disorders and the relationship between inner ear and renal pathologies. Controls, and NZB/kl and MRL/lpr strain mice, in which autoimmune disease can be spontaneously induced, were used in this study. The mice were tested for acoustic brain stem response (ABR), cochlear and renal pathology and circulating immune-complexes (CIC) serology, using enzyme immunoassay (EIA). For ABR, click and high frequency tone bursts were used as stimuli. Pathological studies consisted of tissue changes observed following hematoxylin-eosin (HE) and indirect immunofluorescent staining under light microscopy. Compared to controls, hearing was impaired in NZB/kl mice while hearing remained unaffected in MRL/lpr mice. On HE staining, no histological changes were observed in the cochleae of either strain of mice. However, indirect fluorescent staining showed IgG deposits in the stria vascularis in both strains of mice. In both strains, renal pathology consisted of an immune-complex glomerulonephritis. CIC values were significantly higher in MRL/lpr mice, but were not correlated to stria vascular lesions. The lesions in the stria vascularis in the two strains were different, which probably explains the discrepancy in hearing impairment, whereas the lesions in the kidney were similar. NZB/kl mice that had hearing impairment showed severe stria vascular lesions and there was a correlation between the degree of hearing impairment and the severity of stria vascular lesions. However, no correlation was seen between stria vascular and renal lesions and CIC values. These findings suggest that autoimmune mechanisms exist in the cochlea, mainly in stria vascularis. The NZB/kl mouse can be a useful model of sensorineural hearing disorder secondary to immunological disorders. © 1991, The Society of Practical Otolaryngology. All rights reserved.