Abstract
Otitis externa is one of the most common diseases in dogs. It is associated with bacteria and yeast, which are regarded as secondary causes. Cerumen is a biological substance playing an important role in the protection of ear skin. The involvement of cerumen in immune defense is poorly understood. MicroRNAs can modulate the host immune response and can provide promising biomarkers for several inflammatory and infectious disorder diagnosis. The aims of this study were to profile the cerumen miRNA signature associated with otitis externa in dogs, integrate miRNAs to their target genes related to immune functions, and investigate their potential use as biomarkers. Cerumen was collected from healthy and otitis affected dogs and the expression of miRNAs was profiled by Next Generation Sequencing; the validation of the altered miRNAs was performed using RT-qPCR. The potential ability of miRNAs to modulate immune-related genes was investigated using bioinformatics tools. The results pointed out that 32 miRNAs, of which 14 were up- and 18 down-regulated, were differentially expressed in healthy vs. otitis-affected dogs. These results were verified by RT-qPCR. To assess the diagnostic value of miRNAs, ROC analysis was carried out, highlighting that 4 miRNAs are potential biomarkers to discriminate otitis-affected dogs. Bioinformatics showed that cerumen miRNAs may be involved in the modulation of host immune response. In conclusion, we have demonstrated for the first time that miRNAs can be efficiently extracted and quantified from cerumen, that their profile changes between healthy and otitis affected dogs, and that they may serve as potential biomarkers. Further studies are necessary to confirm their diagnostic value and to investigate their interaction with immune-related genes.
Highlights
Otitis externa is defined as the inflammation of the external ear canal and represents one of the most prevalent skin disorders in dogs [1,2,3,4]
The findings of this study provided for the first-time evidence that (a) miRNAs can be efficiently extracted, sequenced, and quantified by RT-qPCR from canine cerumen and (b) cerumen microRNAs quantities change during otitis externa
In the first part of the investigation, a pilot sequencing study was performed to profile the miRNome of cerumen, showing that otitis externa
Summary
Otitis externa is defined as the inflammation of the external ear canal and represents one of the most prevalent skin disorders in dogs [1,2,3,4]. The causes of otitis externa can be divided into primary and secondary [5, 6]. Primary causes of otitis include inflammatory conditions, such as autoimmune or immunemediated diseases, keratinization and glandular disorders, and ectoparasites. The host immune response to microorganisms in the external ear canal likely plays a pivotal role, but few data are available in dogs, except for studies on the immune reaction against Malassezia [8,9,10]. Proteins belonging to β-defensin families were detected [13], suggesting a possible role in the local innate immune response
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