Selected cytokine expression in dogs with alergic conjunctivitis: Correlation with disease activity

Abstract Introduction Canine allergic conjunctivitis (cAC) is described as the most frequent ocular manifestation associated with canine atopic dermatitis (cAD). Objectives Clinical and immunological characterization of cAD through IL-6, TNF-α and IL-12 mRNA expression quantification in canine conjunctivae. Procedures Twenty client-owned dogs with both cAC and cAD and twenty-one healthy controls were enrolled and clinician assessed CADESI-04 and grade of ocular signs were calculated. Conjunctival biopsies were performed on all animals and relative quantification of the interleukins mRNA expression performed by qRT-PCR. The correlation between cytokine gene expression and cAC score was evaluated, as well as CADESI-04 values. Results The qRT-PCR showed a significant gene upregulation of respectively 291.48 (p = 1.306e-09) and 4.85 (p = .00033) folds on IL-6 and IL-12 in dogs with allergic conjunctivitis compared to the control group. Regarding the average expression of TNF-α there were no statistical significant differences between both groups (p = .18). Higher cAC scores were associated with enhanced gene expression of TNF-α and IL-12. No correlation was found between the cytokine gene expression levels and the CADESI-04 values. Conclusion An increase of IL6 and IL12 in cAC was found in the studied population. These two cytokines may be potential immunotherapy targets cAC classification.