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The A2ml1-Knockout mouse as an animal model for non-syndromic otitis media
Christina L Elling1, Helen Z Gomez1, Nam K Lee1
1Department of Otolaryngology-Head and Neck Surgery, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA.
Background:
Inflammation and infection of the middle ear, known as otitis media (OM), is a leading cause of hearing loss and the most frequently diagnosed disease in children worldwide. Traditionally, mouse models for OM rely on inducing acute infection through inoculation of the middle ear, e.g. with the human otopathogen non-typeable Haemophilus influenzae (NTHi), and with very few genetic models with spontaneous or chronic OM. A2ML1 variants, including loss-of-function variants, were associated with susceptibility to OM in humans, but no animal model has been reported for A2ml1-related OM. Here, we report our middle ear findings in a mouse line with a CRISPR-induced knockout (KO) of A2ml1.
Methods:
Mice were X-rayed prior to harvest to determine if there are craniofacial or skeletal abnormalities. Tissue from mouse middle ears, as well as other upper respiratory mucosal tissues, were harvested. The harvested middle ear bullae were examined under microscope and submitted for histologic preparation to study phenotypic indications of OM. RNA samples isolated from middle ear tissue were assayed for expression of genes correlated with A2ML1 expression in humans.
Results:
Data from a total of 119 mice (35 wildtype, 40 heterozygous, 44 homozygous) are presented here, with each analyses being performed on subsets of these mice. There were no significant craniofacial differences by genotype (n = 22). Findings in mice with the A2ml1-KO indicated an increased incidence of OM (n=29; odds ratio = 11; CI: 1.1, 573.6; Fisher exact two-sided p = 0.02) with tympanic membrane perforations or thickening, as well as cases of middle ear effusion, inflammatory cells, or fluid from histologic sections. Dsp was upregulated in the middle ear tissues of homozygous mice (Wilcoxon test p = 0.001).
Conclusion:
Thus far, our results in this A2ml1-KO mouse line indicate spontaneous occurrence of OM and dysregulation of Dsp in the middle ear as a potential disease mechanism for A2ml1-related OM.
Insights
A new mouse model with a knockout of the A2ML1 gene shows spontaneous otitis media (OM), a common childhood ear infection. This finding offers a new model for studying A2ML1-related OM and its mechanisms.
Area of Science:
- Otolaryngology
- Genetics
- Immunology
Background:
- Otitis media (OM) is a prevalent childhood disease causing hearing loss.
- Current mouse models for OM often involve induced infections, with limited genetic models for spontaneous or chronic conditions.
- Loss-of-function variants in A2ML1 are linked to human OM susceptibility, but an animal model was lacking.
Purpose of the Study:
- To investigate the role of A2ML1 in otitis media pathogenesis.
- To characterize middle ear phenotypes in a mouse model with a CRISPR-induced A2ml1 knockout (KO).
Main Methods:
- Generated an A2ml1 knockout (KO) mouse line using CRISPR technology.
- Examined craniofacial and skeletal structures via X-ray.
- Performed histological analysis of middle ear tissues to identify OM indicators.
- Assayed middle ear RNA for gene expression, including Dsp.
Main Results:
- The A2ml1-KO mouse line exhibited a significantly increased incidence of spontaneous otitis media.
- Histological findings included tympanic membrane abnormalities, middle ear effusion, and inflammation.
- D অ্যাসিড (Dsp) gene expression was significantly upregulated in the middle ear tissues of homozygous A2ml1-KO mice.
Conclusions:
- The A2ml1-KO mouse line demonstrates spontaneous otitis media, providing a novel model for A2ML1-related OM.
- Dysregulation of Dsp in the middle ear is implicated as a potential mechanism in A2ML1-related otitis media.
