Investigation of the effect of probiotic exposure on filaggrin expression in an experimental model of canine atopic dermatitis

Abstract

Atopic dermatitis (AD) results from complex interactions between an impaired skin barrier and immunological stimulation. Filaggrin is a key protein for the skin barrier, and its expression is decreased in subsets of atopic dogs and can be modified by inflammation; thus, immunomodulatory approaches may alter its expression. Probiotics have been explored for the prevention and treatment of allergies, owing to their immunomodulatory properties; however, it is currently unknown whether they can modulate filaggrin expression. The purpose of this study was to evaluate whether probiotics can modulate filaggrin expression in an experimental model of canine AD. Eighteen atopic (11 probiotic exposed and seven control) and five normal beagles were challenged for three consecutive days with Dermatophagoides farinae. Skin biopsies were taken before (day0), at the peak (day3) and after the end of the allergen challenge (day10). Immunohistochemistry for filaggrin was done using a polyclonal antibody specific for canine filaggrin, and staining was scored both subjectively (for intensity, granularity and continuity) and objectively, by tracing the stratum granulosum and calculating the percentage of filaggrin per unit traced area. Analysis of variance of the percentage of filaggrin in the stratum granulosum showed a significant effect of group (P=0.0414, AD<normal), time (P=0.0066, days3 and 10>day0) and marginal group×time interaction (P=0.0606). Within the atopic group, exposure to probiotics did not change filaggrin expression. No significant differences were found in the subjective scores among groups. It is concluded that probiotic exposure early in life does not alter filaggrin expression in this AD model.