Mohammad Habiby Kermany

Identification of 17 hearing impaired mouse strains in the TMGC ENU-mutagenesis screen.

The Tennessee Mouse Genome Consortium (TMGC) employed an N-ethyl-N-nitrosourea (ENU)-mutagenesis scheme to identify mouse recessive mutants with hearing phenotypes. We employed auditory brainstem responses (ABR) to click and 8, 16, and 32 kHz stimuli and screened 285 pedigrees (1819 mice of 8-11 weeks old in various mixed genetic backgrounds) each bred to carry a homozygous ENU-induced mutation. To define mutant pedigrees, we measured > or = 12 mice per pedigree in > or = 2 generations and used a criterion where the mean ABR threshold per pedigree was two standard deviations above the mean of all offspring from the same parental strain. We thus identified 17 mutant pedigrees (6%), all exhibiting hearing loss at high frequencies (> or = 16 kHz) with an average threshold elevation of 30-35 dB SPL. Interestingly, four mutants showed sex-biased hearing loss and six mutants displayed wide range frequency hearing loss. Temporal bone histology revealed that six of the first nine mutants displayed cochlear morphological defects: degeneration of spiral ganglia, spiral ligament fibrocytes or inner hair cells (but not outer hair cells) mostly in basal turns. In contrast to other ENU-mutagenesis auditory screens, our screen identified high-frequency, mild and sex-biased hearing defects. Further characterization of these 17 mouse models will advance our understanding of presbycusis and noise-induced hearing loss in humans.

Experimental autoimmune hearing loss is exacerbated in IL-10-deficient mice and reversed by IL-10 gene transfer.

Interleukin-10 (IL-10) has an important role in the homeostatic regulation of autoreactive T-cell repertoire. We hypothesized that endogenous IL-10 would regulate the severity of β-tubulin-induced experimental autoimmune hearing loss (EAHL) and that exogenous IL-10 would abrogate it. BALB/c wild-type (WT) and homozygous IL-10-deficient mice (IL-10−/−) underwent β-tubulin immunization to develop EAHL; some IL-10 mice with EAHL were administered IL-10 DNA at the peak of EAHL. Auditory brainstem responses were examined over time. EAHL developed progressively in both WT and IL-10−/− mice. However, the severity of hearing loss in the IL-10−/− mice was significantly greater than that in WT animals. Moreover, disease severity was associated with a significantly enhanced interferon-γ level and loss of hair cells in IL-10−/− mice. IL-10 administered to EAHL IL-10−/− mice promoted IL-10 expression. Consequently, hearing significantly improved by protecting hair cells in established EAHL. Importantly, IL-10 treatment suppressed proliferation of antigen-specific T-helper type 1 (Th1) cells, and the suppression can be attributed to inducing IL-10-secreting regulatory T cells that suppressed autoreactive T cells. We demonstrated that the lack of IL-10 exacerbated hearing loss, and the exogenous administration of IL-10 improved hearing. Mechanistically, our results indicate that IL-10 is capable of controlling autoimmune reaction severity by suppressing Th1-type proinflammatory responses and inducing IL-10-secreting regulatory T cells.

Induction of Tolerance by Oral Administration of Beta-Tubulin in an Animal Model of Autoimmune Inner Ear Disease

Induction of peripheral tolerance by oral administration of low-dose β-tubulin antigen may be an effective, antigen-specific method to suppress experimental autoimmune hearing loss. Five groups of mice were fed with phosphate-buffered saline (PBS), ovalbumin (OVA), 20, 30 or 200 μg of β-tubulin, respectively. All mice were then immunized by β-tubulin. Hearing thresholds were measured before and after immunization. Inner ear histology and cytokine profile were examined. Mice fed with 20 or 30 μg of β-tubulin showed less hearing loss and less inner ear damage compared to the groups treated with PBS, OVA or 200 μg of β-tubulin. Interferon-gamma (IFN-γ) was decreased while interleukin-4 (IL-4), IL-5, IL-13 and TGF-β were increased in both sera and in cell culture supernatants of the mice fed with 20 or 30 μg of β-tubulin. However, no cytokine profile change was found in the group treated with 200 μg of tubulin. These results suggest that a low dose of β-tubulin is active orally in an antigen-specific fashion and capable of inhibiting the autoimmune reactions in the inner ear by suppressingTh1 (IFN-γ) and increasing Th2 and Th3 (IL-4, IL-5, IL-13 and TGF-β) cytokines. Oral antigen tolerance may be used to treat autoimmune inner ear disease.

Murine autoimmune hearing loss mediated by CD4+ T cells specific for β-tubulin

Autoimmune inner ear disease is described as progressive, bilateral although asymmetric, sensorineural hearing loss and can be improved by immunosuppressive therapy. We showed that the inner ear autoantigen β-tubulin is capable of inducing experimental autoimmune hearing loss (EAHL) in mice. Immunization of BALB/c mice with β-tubulin resulted in hair cell loss and hearing loss, effects that were not seen in animals immunized with control peptide. Moreover, the EAHL model showed that β-tubulin responsiveness involved CD4(+) T cells producing IFN-γ, and T cell mediation of EAHL was determined by significantly increased auditory brainstem response after adoptive transfer of β-tubulin-activated CD4(+) T cells into naive BALB/c recipients. The potential mechanisms responsible for the observed pathology of EAHL can be attributed to decreased frequency and impaired suppressive function of regulatory T cells. Our study suggests that EAHL may be a T cell-mediated organ-specific autoimmune disorder of the inner ear.

Prevention and treatment of DNA vaccine encoding cockroach allergen Bla g 1 in a mouse model of allergic airway inflammation

To cite this article: Zhou B, Ensell M, Zhou Y, Nair U, Glickstein J, Kermany MH, Cai Q, Cai C, Liu W, Deng Y‐P, Kakigi A, Barbieri M, Mora M, Kanangat S, Yoo TJ. Prevention and treatment of DNA vaccine encoding cockroach allergen Bla g 1 in a mouse model of allergic airway inflammation. Allergy 2012; 67: 166–174.

Adoptive Cellular Gene Therapy for the Treatment of Experimental Autoimmune Polychondritis Ear Disease

In the past, the clinical therapy for autoimmune diseases, such as autoimmune polychondritis ear disease, was mostly limited to nonspecific immunosuppressive agents, which could lead to variable responses. Currently, gene therapy aims at achieving higher specificity and less adverse effects. This concept utilizes the adoptive transfer of autologous T cells that have been retrovirally transduced ex vivo to express and deliver immunoregulatory gene products to sites of autoimmune inflammation. In the animal model of collagen-induced autoimmune polychondritis ear disease (CIAPED), the adoptive transfer of IL-12p40-expressing collagen type II (CII)-specific CD4+ T-cell hybridomas resulted in a significantly lower disease incidence and severity compared with untreated or vector-only-treated animals. In vivo cell detection using bioluminescent labels showed that transferred CII-reactive T-cell hybridomas accumulated in the inflamed earlobes of the mice with CIAPED. In vitro analysis demonstrated that IL-12p40-transduced T cells did not affect antigen-specific T-cell activation or systemic anti-CII Ab responses. However, IL-12p40-transduced T cells suppressed IFN-γ and augmented IL-4 production, indicating their potential to act therapeutically by interrupting Th1-mediated inflammatory responses via augmenting Th2 responses. These results indicate that the local delivery of IL-12p40 by T cells could inhibit CIAPED by suppressing autoimmune responses at the site of inflammation.