Lipid analysis reveals skin differences in dogs with atopic dermatitis

Abstract

BACKGROUND: Canine atopic dermatitis (cAD) is a complex skin disease characterised by barrier dysfunction. Studies regarding the role of skin surface lipids (SSL) in cAD are needed. OBJECTIVES/HYPOTHESIS: Evaluate the feasibility of using D-squame tape-stripping for SSL collection and ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS) for untargeted lipidomic analysis. A secondary objective was to identify significant differences in SSL between atopic and healthy dogs, and between different body sites. ANIMALS: Sixteen client-owned Labrador retrievers, eight atopic and eight healthy were recruited through vaccination or dermatology appointments. MATERIALS AND METHODS: Skin samples were collected from three body sites (thigh, interdigital and inguinal) using D-Squame tapes. Untargeted lipidomic analysis was conducted using UHPLC-HRMS, and data were processed with MS-DIAL and LipidSearch software. RESULTS: This study identified 114 SSLs, predominantly ceramides (66.2%) and diacylglycerols (30.5%). The percentage of lipid classes and ceramide subclasses did not significantly differ between healthy and atopic dogs. Two ceramide and two triacylglycerol species were significantly higher in atopic dogs, while another two ceramide species were significantly lower. Additionally, notable regional differences in lipid profiles were observed. CONCLUSIONS AND CLINICAL RELEVANCE: Our findings suggest that D-squame tape-stripping combined with UHPLC-HRMS is a feasible method for SSL research in cAD. Lipid species-specific differences and significant regional variations were found, emphasising the importance of considering body sites in future studies. This study underscores the need for further research to understand the role of SSL in cAD and the insights that untargeted lipidomic analysis can provide.