The MRL-lpr/lpr mouse: a potential model of autoimmune inner ear disease

Most attempts at developing a model of autoimmune inner ear disease have focused on the immunization of healthy animals with cochlear tissue. We have chosen an alternate route of studying this entity utilizing the MRL-lpr/lpr (Lupus) mouse, an animal known to spontaneously develop multisystemic, organ nonspecific autoimmune disease. We report on the auditory pathology found in animals at early stages of this systemic disease. At the onset of clinical signs of illness (cachexia, weight loss, lethargy) animals were sacrificed and their cochleas and kidney prepared for morphologic analysis. Significant pathology was seen in the MRL/lpr animals involving the basal and middle turns of the cochlea which could not be correlated with the presence or degree of glomerulonephritis. Findings included outer and inner haircell degeneration, strial edema and degeneration, and an acellular infiltrate in the tunnel of Corti. Cochlear pathology was not found in control animals. Thus, at early stages of systemic disease, MRL/lpr mice manifest significant cochlear pathology not seen in control animals. The implications of these results with regard to the pathogenesis of these lesions as well as their clinical relevance are discussed.