Introduction

Analysis of differentially expressed genes (OEGs) in the skin of atopic dogs provides an important approach to understand the etiopathogenesis in canine atopic dermatitis (CAD.) The diet is also known to have an impact on the gene expression.

Objectives

To find DEGs in the skin of atopic Staffordshire bull terriers using RNA-Seq, with and without the consideration of the diet.

Methods

Skin biopsies were taken from four dogs diagnosed with CAD and four healthy dogs. Half of them were fed raw diet and half of them dry diet for a median of 139 days. The differential expression analysis was done with EdgeR and DeSeq2 algorithms and functional analyses with Ingenuity Pathway Analysis Software.

Results

Altogether 149 DEGs were found in CAD dogs compared to healthy dogs, e.g., calcyclin, ribosomal protein-L23, and transglutaminases (TGMs). Top canonical pathways in the CAD dogs were angiopoietin and epidermal growth factor signaling. When the diet was considered, 856 and 60 DEGs between CAD and healthy dogs were found in the dry and raw diet groups, respectively. In the dry diet group, TGMs, filaggrin-2, and 23 keratins were among differentially expressed genes in CAD dogs, lipopolysaccharide/interleukin-1-mediated inhibition of the retinoid X receptors being one of the top canonical pathways. In the raw diet group e.g., angiotensinogen and TGM6 were upregulated in the CAD dogs. The top canonical pathway was y-linolate biosynthesis II.

Conclusions

This study reports novel genes involved in CAD. The diet also has an impact on skin gene expression, which should be taken into account in future studies.