Survey of cytokines on ocular surfaces of atopic dogs by multiplex analysis using two sampling methods – a pilot study

Abstract

Background -Conjunctivitis in atopic dogs has already been described yet is rarely observed, and likely underdiagnosed in practice.Objectives -To assay various cytokines in tears and conjunctivae from atopic and normal dogs, and to compare canine atopic dermatitis-associated conjunctivitis with controls.Animals -Ten atopic and ten normal client-owned dogs.Methods and materials -Ocular surfaces were sampled bilaterally in a prospective study, using two different methods. Tear samples were obtained with a sterile swab previously moistened with saline solution (method A). Conjunctival impressions were obtained with a conjunctival impression device (method B). For each sample, the concentrations of a panel of 13 cytokines were measured by multiplex analyses. CADESI-4, pruritus (PS) and conjunctival (CS) scores were determined.Results -Among the measured cytokines, only granulocyte-macrophage colony-stimulating factor (GM-CSF), keratinocyte-derived chemokine (KC)-like and interleukin (IL)-8 were above the limit of quantification in most samples. Absolute amounts of each cytokine were always higher in samples obtained with method A than with method B. GM-CSF amounts were lower in atopic dogs (method A, P=0.02; method B, P=0.0005). KC levels were higher in atopic dogs, yet the differences were not significant. IL-8 amounts were higher in atopic dogs (method A, P=0.0003; method B, P=0.006).Conclusions and clinical relevance -Regardless of the method, these preliminary results suggest an overexpression of IL-8 in conjunctivae and tears of atopic dogs despite subtle conjunctival symptoms. As IL-8 is commonly found in many inflammatory conditions, further studies are needed to determine its specificity in atopic conjunctivitis.

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

“…In a recent pilot study, concentrations of cytokines were measured by a Luminex assay in the tears and the conjunctiva of atopic dogs and compared with the concentrations detected in normal dogs. IL-8 was found to be over-expressed in conjunctiva and tears of atopic dogs despite subtle conjunctival symptoms [ 30 ]. Finally, a recent study showed that the plasma concentrations of IL-8, IL-7, and IL-15 cytokines were elevated in canine AD patients compared to in control dogs [ 31 ].…”

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

“…Similarly, significantly increased IL-8/CXCL8 concentrations have been reported in previous studies that analyzed cytokines by swabbing the cerumen or occlusal surface of dogs with atopic dermatitis (6, 7). 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).…”

“…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.…”

Clinical and Microbiological Performances and Effects on Lipid and Cytokine Production of a Ceruminolytic Ear Cleaner in Canine Erythemato-Ceruminous Otitis Externa

“…IL-8 is a potent chemoattractant for neutrophils and a proinflammatory mediator. It has been shown to be significantly elevated in some atopic dogs [1], including ear canals [28] and conjunctivae [29], but also in ear canals infested with O. cynotis [28]. Its 45% reduction compared to baseline is likely linked to the decrease in aural inflammation.…”