Interferon-gamma expression in the inner ear of rats following secondary immune reaction in the endolymphatic sac.

Recently, we demonstrated increased intercellular adhesion molecule-1 (ICAM-1) expression in the inner ear of systemically pre-sensitized rats after antigen [keyhole limpet hemocyanin (KLH)] challenge into the endolymphatic sac (ES), in good correlation with the cellular infiltration. Interferon-gamma (IFN-gamma) is an important cytokine that upregulates the expression of ICAM-1. Here, we report upregulation of IFN-gamma expression in the inner ear of systemically pre-sensitized rats after antigen (KLH) challenge into the ES. Immunoreactivity for IFN-gamma was detected in the spiral ligament, suprastrial region, spiral modiolar veins, spiral collecting venules, surface membrane of the perilymphatic compartment and perilymphatic space of immunized, but not control, rats. IFN-gamma expression was detected at 1.5 h post-challenge, peaked at 6 h and gradually returned to baseline levels after 7 days. Interestingly, the time kinetics of IFN-gamma expression were in good correlation with those of ICAM-1. These observations demonstrate that antigen challenge into the ES induces IFN-gamma expression, which can then upregulate ICAM-1 expression and induce cell infiltration, suggesting that IFN-gamma may play a crucial role in immune-mediated inner ear diseases.

Induction of apoptosis in the vestibule of guinea pigs after middle ear inoculation with lipopolysaccharide (LPS).

OBJECTIVE: During the process of apoptosis, double-stranded DNA is broken into single-stranded DNA (ssDNA) by the action of caspases and caspase activated deoxyribonuclease (CAD). We immunohistochemically examined the apoptotic changes induced by endotoxin in the vestibule of guinea pigs. METHODS: Lipopolysaccharide (LPS) (5 mg/ml, 0.2 ml), a bacterial endotoxin, was transtympanically injected into the middle ear. 48 h after injection of LPS, animals were sacrificed by intracardiac perfusion of fixative. The temporal bones were then removed and immunohistochemically stained for ssDNA, CAD and caspase 3. RESULTS: ssDNA was detected after 48 h in the dark cell area of the LPS group, not in the sensory epithelium. CAD was observed both in the dark cell area and the sensory epithelium. Caspase 3 was also detected both in the dark cell area and the sensory epithelium. CONCLUSION: Our findings suggest that apoptosis is involved in the dysfunction of the vestibule under inflammatory conditions.

Expression of caspase-activated deoxyribonuclease (CAD) and caspase 3 (CPP32) in the cochlea of cisplatin (CDDP)-treated guinea pigs.

Cisplatin, an anti-cancer drug, is known to induce apoptosis. During apoptosis, double-stranded DNA is broken into single-stranded DNA by the action of caspases and caspase activated deoxyribonuclease (CAD). We immunohistochemically examined the cochlea of guinea pigs for signs of the apoptosis after the administration of cisplatin. Cisplatin (10 mg/kg b.w.) was intraperitoneally injected to guinea pigs and 3 days later, the animals were sacrificed by intracardiac perfusion of 4% paraformaldehyde. The temporal bones were then removed and immunohistochemically stained for CAD and caspase 3, using the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labelling method. CAD was observed in the stria vascularis and the spiral ligament. Caspase 3 was also detected in the stria vascularis, the spiral ligament and the supporting cells of the organ of Corti. These findings suggest that apoptosis is involved in the cochlear damage observed in cancer patients treated with cisplatin.

Immunoreactivity for myeloperoxidase (MPO) in the vestibule after the injection of bacterial lipopolysaccharide into the middle ear.

OBJECTIVE: In this study, the effect of endotoxin on the vestibule of the ear of guinea pigs was immunohistochemically examined. METHODS: Bacterial lipopolysaccharide was injected into the middle ear transtympanically. After 48 h, the animals were sacrificed by intracardiac perfusion of fixative; then, the temporal bones were removed and processed for immunohistochemical staining with the anti-myeloperoxidase antibody. RESULTS: Myeloperoxidase could be detected after 48 h in the sensory epithelium and the dark cell area. CONCLUSION: It is reported that radical oxygen species, which are cytotoxic, are detected under inflammatory conditions. Our results suggest that myeloperoxidase and reactive oxygen species are involved in vestibular dysfunction under inflammation.

Expression of caspase-activated deoxyribonuclease (CAD) and caspase 3 (CPP32) in the hydropic cochlea of guinea pigs - second report.

Apoptosis was induced in the cochlea by the injection of keyhole limpet hemocyanin (KLH) into the endolymphatic sac of guinea pigs and immunohistochemically examined. Keyhole limpet hemocyanin was injected into the right endolymphatic sac. The temporal bones were fixed via cardiac infusion of fixative and immunohistochemically stained for caspase-activated deoxyribonuclease or caspase 3. Endolymphatic hydrops became evident in the cochlea 1 day after the injection of keyhole limpet hemocyanin (n=6). The temporal bones in the control group did not show any caspase-activated deoxyribonuclease or caspase 3 immunoreactivity (n=6). Immunoreactivity for caspase 3 was detected in the supporting cells of the organ of Corti, the stria vascularis and the spiral ganglion cells. Caspase-activated deoxyribonuclease was also detected in the same areas. These findings suggest that apoptosis is involved in the pathogenesis of endolymphatic hydrops. This phenomenon could lead to cochlear dysfunction, as seen in endolymphatic hydrops.

Carboplatin induces less apoptosis in the cochlea of guinea pigs than cisplatin.

BACKGROUND: Cisplatin (CDDP) is known to cause inner ear damage while carboplatin (CBDCA) induces less ototoxicity than CDDP. We examined apoptotic changes in the cochlea of guinea pigs after injection of CDDP or CBDCA using immunohistochemical and electrophysiological techniques. METHODS: Three days after the injection of each solution, the cochleas were immunohistochemically examined for the presence of fragments of single-stranded DNA (ssDNA). The auditory brain stem response was recorded before and three days after the injection. RESULTS: We detected fragments of ssDNA in the stria vascularis and the spiral ligament of the CDDP-treated cochlea. In this group, the threshold of the auditory brainstem response was significantly elevated, however, in the CBDCA group, no apparent change of the threshold was detected. In the CBDCA group, fragments of ssDNA were detected in the stria vascularis and the spiral ligament. The number of cells that stained positive for ssDNA, was less than that in the CDDP group. CONCLUSIONS: Our findings indicate that CBDCA induces less apoptosis than CDDP and that this phenomenon contributes to the ototoxicity of CDDP.

Local injection of OK-432 in the treatment of ranula: a case report.

We treated a 57-year-old woman for ranula. After aspirating the cyst's contents, we administered 0.1 KE/ml of OK-432 via local injection. One month later, the cyst had still persisted, so we repeated the procedure. After 2 weeks, the ranula began to shrink markedly, and at 4 weeks it had almost disappeared. No recurrence of the ranula was observed during the subsequent 1 year of follow-up. Following each injection, the patient developed transient fever and local swelling but no serious complications. Our experience suggests that OK-432 injection is an effective treatment for ranula. However, because this treatment causes the cyst to collapse rather than disappear completely, patients should be regularly monitored over the long term.

Nuclear-factor kappa B (NF-kappa B)-inducible nitric oxide synthase (iNOS/NOS II) pathway damages the stria vascularis in cisplatin-treated mice.

BACKGROUND: Cisplatin is reported to damage the stria vascularis of the cochlea. Free radicals, especially large amounts of nitric oxide catalyzed by inducible nitric oxide synthase, are considered to have an important role in this toxicity. The induction of inducible nitric oxide synthase is regulated by nuclear-factor kappa B (NF-kappa B). We examined the damage of the stria vascularis by immunohistochemical techniques. MATERIALS AND METHODS: Cisplatin (15 mg/kg b.w.) was injected intraperitoneally into the mice. Three days after the injection, the cochleas were immunohistochemically-stained using specific antibodies for nuclear-factor kappa B (NF-kappa B), inducible nitric oxide synthase (iNOS) or single-stranded DNA. RESULTS: NF-kappa B was expressed in the cisplatin-treated cochlea, especially in the stria vascularis and the spiral ligament. iNOS was also expressed in the stria vascularis and the spiral ligament. Fragments of DNA were observed only in the stria vascularis. CONCLUSION: The large amounts of NO catalyzed by iNOS led to inner ear dysfunction. Our results indicate that apoptosis is triggered by iNOS and that it mediates the ototoxicity induced by cisplatin.