Sequential Histopathological Changes and Cytokine Expressions in Dogs Naturally Infested with Sarcoptes scabiei Mites.

Abstract

BACKGROUND: The diagnosis and treatment of canine scabies remain quite challenging as a result of the meddling of the invertebrate mite Sarcoptes scabiei var canis with the immunologic activity of its host. PURPOSE: This study aims to evaluate and better understand the immunologic, histomorphometric, histopathologic changes as well as their relationship in scabies infestation. METHOD: Ten healthy dogs were housed with five sarcoptes-ridden dogs. Skin biopsies were then obtained afterwards for 7 weeks into buffered formalin. Sections of obtained biopsies were processed and incubated in IL-4, IL-13, IL-17A and IL-23A antibodies, while the other sections were stained for cellular alterations, quantifications and measurement of tunnel height and diameters. Pearson's product-moment correlation was used to establish the association between the cytokines and the measured tunnel heights and diameters, while Student's t test and one-way analysis of variance were used to test for weekly significant differences in cytokine expressions. RESULTS: Histopathologic changes and early expression of all studied cytokines, eosinophils and mast cells were pronounced from the second week of infestation. Quite notable was the consistent amount of IL-13 and IL-23A all through the study duration. A dissimilar association was also observed between anti-inflammatory cytokines (IL-4 and IL-13) and pro-inflammatory cytokines (IL-17A and IL-23A). Also observed was the negative relationship between IL-13 and IL-23A as an increase in IL-13 was associated with a decrease in IL-23A. Tunnel height increase was also positively associated with pro-inflammation. CONCLUSION: Immunodiagnosis can possibly be achieved with IL-13 and IL-23A expressions, while immunotherapy seems possible with IL-13 cytokine therapy.