Correlation between clinical findings, mast cell count and interleukin 31 immunostaining in the skin of dogs with atopic dermatitis

Abstract

In this study the correlation between the clinical score, mast cell count and interleukin 31 (IL-31) immunostaining in the skin of dogs with atopic dermatitis was determined. A total of 31 dogs of different breeds, from one to eight years of age, were chosen for the study. The 20 females and 11 males were categorized based on the CADESI-4 system, as having discrete, moderate or marked atopic dermatitis. Skin samples were collected from the axillary and interdigital regions and stained with hematoxylin and eosin for cytohistomorphological analyses and toluidine blue to evaluate the mast cell counts, and immunohistochemistry for the IL-31 immunostaining. Animals revealing higher atopic dermatitis scores had greater numbers of mast cells and IL-31 immunolabeled cells. More numbers of cells immunolabeled for IL-31 were evident in the axillary skin compared with the interdigital skin in dogs having this condition. A correlation was identified between the clinical scores and mast cell numbers in the interdigital region, as well as between the clinical scores and number of cells immunolabeled for IL-31 in the axillary area. A correlation was also reported between the mast cell numbers and IL-31 immunolabeled cells only in the axillary skin, and none in the interdigital regions. It was thus concluded that the mast cells and IL-31 are involved in the pathogenesis of the canine atopic dermatitis (CAD), as well as lymphocytes and plasma cells. It was also observed that the higher the degree of clinical severity of the disease, the more the numbers of mast cells and IL-31 in the skin of those animals suffering from CAD, which implies the influence of these immunological constituents on the genesis of pruritus and disease progression.

IL‐31 and IL‐31 receptor expression in acute experimental canine atopic dermatitis skin lesions

“…10,11 Another study using canine atopic skin samples reported the production of IL-31 by lymphocytes and plasma cells; however, the specificity of the primary antibody used to detect canine was not validated. 12 Likewise, only two poster presentations confirmed the expression of the IL-31 receptor alpha chain (IL-31RA) on canine keratinocytes, but detailed results have not been published yet. 13,14 As is well-known in both humans and dogs, the cytokine milieu changes during the evolution of atopic skin lesions.…”

“…Two papers demonstrated that T cells, likely type 2 helper T (Th2) cells, produced IL‐31; however, these studies were performed in stimulated peripheral blood cells 10,11 . Another study using canine atopic skin samples reported the production of IL‐31 by lymphocytes and plasma cells; however, the specificity of the primary antibody used to detect canine IL‐31 was not validated 12 . Likewise, only two poster presentations confirmed the expression of the IL‐31 receptor alpha chain (IL‐31RA) on canine keratinocytes, but detailed results have not been published yet 13,14…”

Canine atopic dermatitis: systemic immunomodulatory protocol based on clinical phenotype

“…Interleukin-31 (IL-31) is produced by Th2 cells and also by mast cells (BRANDT & SIVAPRASAD, 2011), being largely expressed in damaged skin of atopic animals (GONÇALVES et al, 2018;SHIOMITSU et al, 2021). It is associated with pruritus through a neurological stimulation and elongation of sensory fibers (GONZALES et al, 2013).…”

Application of a Synbio-Glucan Functional Spray for Canine Atopic Dermatitis

“…The efficacy of the functional spray was evaluated clinically using previously known methods, to effectively quantify the severity of the AD symptoms before and after treatment (11,17,43,48). The degree of pruritus-related behaviors, such as scratching, licking, biting, and rubbing, was evaluated by the pruritus visual analog scale (PVAS) according to the following scores by each caregiver: 0 = normal; 1-2 = rarely itching (occasional episodes); 3-4 = mild pruritus (semi-frequent episodes); 5-6 = moderate pruritus (frequent episodes); 7-8 = moderate to severe pruritus (prolonged episodes); 9-10 = severe pruritus (extremely continuous itching) (17,48).…”

“…The sum of the evaluated values was expressed as mild , moderate , and severe (more than 60). With 20 sites, three lesions, and four severity scores (0-3), the maximum score was 180 (20 × 3 × 3 = 180) and the minimum score was 0 (11). The evaluations were made by one assessor for consistency.…”