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.