Effects of immunosuppression on the development of cochlear disease in theMRL-Fas(lpr) mouse

Objectives: The MRL-Fas(lpr) mouse, an animal that spontaneously develops m ultisystemic autoimmune disease, has been proposed as model of immune-media ted inner ear disease. Previous studies revealed that this mouse manifested elevated auditory brainstem response thresholds, hydropic degeneration of strial cells, and antibody deposition within strial capillaries, As the eti ology of the observed strial disease may be immune, genetic, or uremic, a s tudy was designed to attempt to delineate between these possible etiologic factors, Study Design: Prospective, controlled animal study. Methods: Dexam ethasone, which is known to suppress autoantibody production and glomerulon ephritis in these animals, was administered systemically on a daily basis t o experimental animals, beginning at 6 weeks of age, Control animals receiv ed no treatment, Animals were allowed to age, with control animals predicta bly manifesting systemic disease at 20 weeks of age, at which point all ani mals were sacrificed, Results: Animals receiving dexamethasone treatment ma nifested a significant reduction in serum immunoglobulin levels, lymphoid h yperplasia, and a significant improvement in the level of renal function. H owever, morphologic analysis revealed a persistence of strial disease despi te the elimination of strial antibody deposition, Conclusion: The results o f this experiment support the hypothesis that genetic mechanisms may be res ponsible for the observed strial disease. Further studies are under way to confirm these findings.