Multiplex Cytokine Analyses in Ear Canals of Dogs Suggest Involvement of IL-8 Chemokine in Atopic Otitis and Otodectic Mange—Preliminary Results

Abstract

Cutaneous cytokines and chemokines are involved in the pathogenesis of human and canine atopic dermatitis. The aim of the present study was to discriminate cytokine expression in the ear canals of atopic dogs with otitis, dogs with non-allergic inflammatory otitis (otodectic mange) and healthy non-atopic dogs. The ear canals of nine atopic dogs suffering from non-infected otitis externa (n = 14 ears), 10 healthy dogs suffering from otodectic mange (n = 20 ears) and 21 healthy controls (39 ears) were swabbed. The concentrations of a panel of 13 cytokines and chemokines on the aural surface were measured by multiplex analyses (Milliplex Canine Cytokine Panel). In addition, Canine Atopic Dermatitis Extent and Severity Index (CADESI)-04 and Otitis Index Score (OTIS3) scores were used to evaluate the overall status of the dogs. The concentration of IL-8 was significantly higher in the ears of atopic dogs and dogs with otodectic mange compared to those of healthy dogs. Significant increases in the levels of IL-10 were also overexpressed in atopic otitis but at lower rates. The concentrations of interleukin(IL)-8 were positively correlated with the OTIS3 hyperplasia score in atopic dogs. Taken together, these results suggest that IL-8 is overexpressed in atopic otitis and otodectic mange and that levels correlate with the otitis severity in atopic dogs.

Non-invasive evaluation of cytokine expression using the cerumen of dogs with otitis externa

“…However, in this study, no significant increases in these cytokines were observed in the dogs with ceruminous Malassezia OE; specifically, IL-6 was barely detected in these samples. A previous study using the Luminex ® assay demonstrated that IL-6 was undetectable in the ear canal of dogs with atopic OE (6). In contrast, this study showed significantly increased concentrations of IL-1ß and IL-6 in the cerumen of dogs with suppurative bacterial OE.…”

“…In an analysis of cytokine expression in conjunctival swabs, IL-8 was the only cytokine that was significantly increased in atopic dogs, showing a positive correlation with conjunctival and pruritus scores (7). In addition, the concentration of IL-8 is also significantly higher in the ears of atopic dogs than in healthy dogs (6). Interestingly, in contrast to the present study, the previous study only selected non-infected otitis patients to avoid the production of pro-inflammatory cytokines related to microbes.…”

“…Therefore, research on non-invasive methods for analyzing skin cytokine expression has recently become of interest. These methods employ collecting samples from the cerumen, ocular surface, and stratum corneum by tape stripping (3,(5)(6)(7). These non-invasive methods allow sampling from many patients and analysis of the expression of cytokines in the skin.…”

“…A previous study investigating miRNA expression in dogs with otitis externa (OE) demonstrated miRNA profile changes between healthy and otitis-affected dogs, and bio-informatics showed that altered miRNAs in the cerumen may be involved in the modulation of the host immune response (5). In addition, a previous study using multiplex cytokine analyses in the ear canals of dogs with OE caused by atopic dermatitis showed increased levels of interleukin (IL)-8 and IL10 (6). However, the previous study selected only non-infected OE to avoid the production of pro-inflammatory cytokines related to microorganism contamination/proliferation.…”

External Otitis Associated with Atopy Disease in Dogs: A Case-Control Study

“…A study conducted in 2022 demonstrated the presence of inflammatory biomarkers in atopic otitis in dogs, particularly the chemokine IL-8 [27]. Unlike on the skin, inflammatory biomarkers have never been identified in the ear canals of atopic dogs.…”