Lack of detection of circulating skin-specific IgE autoantibodies in dogs with moderate or severe atopic dermatitis

Vitamin D shows in vivo efficacy in a placebo-controlled, double-blinded, randomised clinical trial on canine atopic dermatitis

Atopic dermatitis (AD) in dogs is among the most common skin diseases in small animal practice. It is an inflammatory disease based on a genetic predisposition to develop hypersensitivity against environmental and food allergens and typical clinical signs up exposure. Treatment sometimes can be difficult and associated with adverse effects. Previous studies evaluating cholecalciferol as treatment for human AD have shown promising results. With canine AD being a good animal model for its human counterpart, it was hypothesised that cholecalciferol might have beneficial clinical effects in dogs, too. In this randomised, placebo-controlled, double-blinded eight-week cross-over study, 23 client-owned dogs received either systemic cholecalciferol (n=16), a vitamin D receptor analogue (n=8) or placebo (n=13). Blood samples for ionised calcium were obtained regularly during the study, and Canine Atopic Dermatitis Extent and Severity Index and pruritus scores, blood levels of vitamin D metabolites, measurements of skin pH and transepidermal water loss were determined before and after. Pruritus and lesion scores decreased significantly in the cholecalciferol group versus placebo. No differences in water loss or skin pH were observed. An increase in serum 25-hydroxycholecalciferol strongly correlated with a reduction in pruritus. Systemic cholecalciferol may be a viable treatment option for canine AD.

Gene expression in canine atopic dermatitis and correlation with clinical severity scores

BACKGROUND

Canine atopic dermatitis (cAD) is a common condition in dogs that may be a naturally occurring model for human atopic dermatitis (hAD). Despite this, comparative research is limited, particularly into the genetic background of cAD.

OBJECTIVES

1. Measure candidate gene expression in cAD skin using quantitative real time PCR (qPCR). 2. Correlate gene expression to clinical cAD scores (Canine Atopic Dermatitis Extent and Severity Index[CADESI]-03 and intradermal allergen test [IDT]).

METHODS

mRNA was extracted from biopsies of non-lesional and lesional skin from atopic dogs, and healthy skin from non-atopic dogs. Gene expression was quantified using qPCR, and compared between non-lesional atopic, lesional atopic and healthy skin. Gene expression in atopic skin was correlated with clinical severity (CADESI-03) and the number of positive reactions on an IDT.

RESULTS

Of the 20 quantified genes, 11 demonstrated statistically significant altered mRNA expression between atopic and healthy skin; dipeptidyl-peptidase-4 (DPP4), phosphatidylinositol-3,4,5-trisphosphate-5-phosphatase-2 (INPPL1), serine protease inhibitor kazal type-5 (SPINK5), sphingosine-1-phosphate lyase-1 (SGPL1), peroxisome proliferator-activated receptor gamma (PPARgamma), S100 calcium-binding protein A8 (S100A8), Plakophilin-2 (PKP2), Periostin (POSTN), Cullin4A, TNF-alpha and metalloproteinase inhibitor-1 (TIMP-1). Three genes correlated with CADESI-03: serum amyloid A 1 (SAA-1), S100A8, and PKP2; and four with IDT results: mast cell protease I (CMA1), SAA-1, S100A8 and SPINK5.

CONCLUSION

Genes with altered expression included those relevant to skin barrier formation and immune function, suggesting both are relevant in the pathogenesis of AD. Many of these genes reflect the proposed pathogenesis in hAD, supporting the use of dogs as a model for hAD. Furthermore, these genes may be considered suitable targets for future genetic and protein function studies in human and canine AD.