The relation of antigen levels in the middle ear and round window membrane permeability in antigen-induced otitis media

Abstract

By using an antigen induced (Arthus) otitis media (OM) model in chinchillas sensitized with human serum albumin (HSA), we investigated the passage of HSA through the round window membrane (RWM) by measuring HSA levels in both the middle ear fluid (MEF) and the perilymph (PL). The effect of corticosteroid treatment on HSA passage was also studied. HSA (0.5, 5, and 50mg/ml; 1ml) was instilled into the left middle ear bulla (MEB) of both control and sensitized animals (control and Arthus group), and HSA containing 12.5mg/ml of Triamcinolone diacetate was instilled into the right MEB of both animals (control+steroid and Arthus+steroid groups). Mean values of HSA levels in both the MEF and the PL were proportional to the original three different HSA levels (0.5, 5 and 50mg/ml) instilled into the MEB. HSA levels in the MEF differed significantly among the three groups in the following order (Arthus<Arthus+steroid<control). In the control, HSA levels in the PL were significantly reduced by a steroid treatment (p<0.025, 50mg/ml and p<0.05, 5mg/ml). The percentage of HSA positive PL samples was significantly lower in the Arthus group than the control group (p<0.05, 5mg/ml). HSA levels in the PL appear to depend on HSA levels in the MEF which were reduced in the sensitized animals. These results suggest that an immunological reaction may be involved in the reduction of HSA passage through the RWM by reducing HSA levels in the MEF. Corticosteroid treatment may reduce the passage of HSA into the PL in case of non-sensitized animals.