Effects of immunosuppression on the development of cochlear disease in the MRL-Fas(lpr) mouse.
OBJECTIVE
The MRL-Fas(lpr) mouse, an animal that spontaneously develops multisystemic autoimmune disease, has been proposed as model of immune-mediated 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 etiology of the observed strial disease may be immune, genetic, or uremic, a study was designed to attempt to delineate between these possible etiologic factors.


METHODS
Prospective, controlled animal study.


METHODS
Dexamethasone, which is known to suppress autoantibody production and glomerulonephritis in these animals, was administered systemically on a daily basis to experimental animals, beginning at 6 weeks of age. Control animals received no treatment. Animals were allowed to age, with control animals predictably manifesting systemic disease at 20 weeks of age, at which point all animals were sacrificed.


RESULTS
Animals receiving dexamethasone treatment manifested a significant reduction in serum immunoglobulin levels, lymphoid hyperplasia, and a significant improvement in the level of renal function. However, morphologic analysis revealed a persistence of strial disease despite the elimination of strial antibody deposition.


CONCLUSIONS
The results of this experiment support the hypothesis that genetic mechanisms may be responsible for the observed strial disease. Further studies are under way to confirm these findings.
Ruckenstein
M J
MJ
Department of Otolaryngology-Head and Neck Surgery, University of Tennessee, Memphis, USA.
Sarwar
A
A
Hu
L
L
Shami
H
H
Marion
T N
TN
D000818:Animals; D000917:Antibody Formation / Q000276:immunology; D001323:Autoantibodies / Q000276:immunology; D015834:Cochlear Diseases / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology; D003907:Dexamethasone / Q000627:therapeutic use; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005260:Female; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D007165:Immunosuppression Therapy / Q000379:methods*; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D051379:Mice; D019463:Mice, Inbred MRL lpr; D013316:Stria Vascularis / Q000276:immunology / Q000473:pathology
D001323:Autoantibodies; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007166:Immunosuppressive Agents; D003907:Dexamethasone