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

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.