Clinical-pathological and immunological biomarkers in dogs with atopic dermatitis

Canine atopic dermatitis (CAD) is a chronic, pruritic, genetic, and inflammatory disease. Its pathogenesis is very complex and involves skin barrier defects and immune system dysfunction. This study aimed to investigate hematological, biochemical, clinical, and immunological parameters to contribute to the identification of biomarkers applied to CAD. The results of the analysis on hematologic and clinical parameters showed increased neutrophil numbers and decreased lymphocyte counts. The ex vivo immunophenotyping of leukocytes demonstrated increased counts of circulating neutrophils, in addition to a high frequency of CD4⁺ T-cells and elevated CD4⁺/CD8⁺ T-cell ratio, which were the hallmark of atopic animals. Moreover, atopic dogs presented a mixed immune response, displaying both CD4⁺ and CD8⁺ T-cell subsets as relevant sources of IFN-γ and IL-4 cytokines. The morbidity analyzed by the CADESI index demonstrated that CAD severity is related to the low frequency of circulating CD14⁺ monocytes, CD21⁺ B-cells, and CD8⁺ T-cells. The reported biomarkers would be useful in CAD monitoring for treatment and prognosis analysis.