Assessing D-Squame as a Minimally Invasive Technique to Evaluate the Cutaneous Immune Response mRNA in a Dog Model of Canine Atopic Dermatitis.

BACKGROUND

Canine atopic dermatitis (cAD) is a multifactorial, inherited skin disease, estimated to affect ≤ 15% of dogs. Studies of skin messenger mRNA in cAD currently use invasive methods, including blood sampling and biopsy collection, whilst advances in human atopic dermatitis study methodology have demonstrated reliable use of minimally invasive skin sampling techniques for similar objectives.

OBJECTIVES

To validate the use of the minimally invasive D-Squame (tape stripping; TS) method for skin mRNA analysis in dogs, and to investigate the association of highly dysregulated mRNAs with clinical response in a canine model of cAD.

ANIMALS: Eight healthy beagles.

MATERIALS AND

METHODS

Dogs were epicutaneously sensitised twice weekly for 7 weeks (49 days) using house dust mites (HDM; Dermatophagoides farinae). The clinical response of individual dogs to sensitisation was categorised as low, average, or high. On Day 49, D-Squame TS samples were obtained from sensitised and nonsensitised sites from each dog, and transcriptomic analyses were performed. RNA-Seq data analyses were performed using R and Bioconductor with default parameters.

RESULTS

Comparing sensitised and control sites, 210 of 12,545 expressed genes were most differentially expressed (fold-change ≥ 2, p ≤ 0.05). CD2, CD3D/E, CD209 (T cell), IL13, TNFRSF4, CCL17 (T helper 2 cell [Th2]), FCER1A and CD80 (dendritic cells) were among the top 50 most dysregulated genes significantly correlating with sensitisation. Dysregulation of several key mRNAs, including those involved in the Th2 pathway, correlated with clinical response.

CONCLUSIONS AND CLINICAL RELEVANCE: This proof-of-concept study using a minimally invasive method to investigate skin mRNA in cAD lesions enables ethical research of immune biomarkers involved in cAD.