Studies of serum total immunoglobulin E concentrations in atopic and non-atopic dogs

Investigation of the relationship between atopic dermatitis of dogs and intestinal epithelial damage

BACKGROUND

A significant association between atopic dermatitis and leaky gut syndrome has been demonstrated in humans. No studies have been conducted to determine whether there is an association between atopic dermatitis and intestinal damage in dogs.

OBJECTIVES

This study aimed to determine whether there is an association between canine atopic dermatitis and intestinal damage using selected intestinal-related biomarkers.

METHODS

Twenty-six dogs with atopic dermatitis and 10 healthy dogs were included. Moderate-to-severe pruritus, erythema, erosion and alopecia on different parts of the body were sought in dogs to suspect atopic dermatitis. The presence of atopic dermatitis was confirmed by an allergic skin test. Serum biomarkers including intestinal fatty acid binding protein (I-FABP), intestinal alkaline phosphatase (IAP), trefoil factor-3 (TFF-3), immunoglobulin E (IgE), interleukin-4 (IL-4) and interleukin-13 (IL-13) concentrations were measured from venous blood samples.

RESULTS

Of the 26 dogs tested for allergens, 16 were found to be sensitive to mould mites, 10 to vernal grass, eight to house dust mites, five to wheat dust and five to grass pollen mix allergens. Significant increases in serum IAP, TFF-3, IgE, IL-4 and IL-13 concentrations were determined.

CONCLUSION

It was thought that the increase in TFF-3 and IAP concentrations may be due to the presence of intestinal epithelial damage and the repair of this damage. In addition, the development of atopic dermatitis may be predisposed to the entry of allergens into the body through sites of intestinal damage.

Phosphodiesterase 4D, miR-203 and selected cytokines in the peripheral blood are associated with canine atopic dermatitis

Canine Atopic Dermatitis (AD) is a common complex and multifactorial disease involving immune dysregulation, genetic predisposition, skin barrier defects, environmental factors and allergic sensitization. To date, diagnosis of canine AD relies on a combination of patient history, clinical examination, allergy testing and response to diet trials/therapies with no reliable biomarkers available to distinguish AD from other diseases with similar clinical presentations. A handful of studies to identify potential biomarkers in the peripheral blood of AD dogs and healthy controls have been performed with some showing inconsistent and contradictory results. In this study, we, for the first time, report statistically significant increases in expression of phosphodiesterase 4D (PDE4D) gene in peripheral blood mononuclear cells (PBMCs) and miR-203 in plasma from AD dogs compared to healthy controls. In addition, we report a statistically non-significant change of the CD4⁺/CD8⁺ ratio, a dramatic decrease of three gene markers (PIAS1, RORA and SH2B1) as well as a panel of differential expression of cytokines in AD dogs in comparison to the healthy controls. Our study provides important insight into the complexities of canine AD, and further studies to verify the specificity of these findings for canine AD at a larger-scale are warranted.

Total IgE and allergen-specific IgE and IgG antibody levels in sera of atopic dermatitis affected and non-affected Labrador- and Golden retrievers

Canine atopic dermatitis (CAD) is an allergic skin disease associated with IgE and IgG antibodies (Ab) to environmental allergens. The aim of this study was to determine which other factors influence serum Ab levels in CAD-affected and non-affected dogs as this has only been poorly investigated in dogs so far. Total and allergen-specific IgE levels and Dermatophagoides farinae (DF)-specific IgG1 and IgG4 were measured by ELISA in sera of 145 CAD-affected and 271 non-affected Labrador- and Golden retrievers. A multivariable logistic regression analysis including the factors age, breed, gender, castration, clinical CAD status and allergen-specific immunotherapy (ASIT) was performed. Golden retrievers had more frequently total (OR=1.87, 95% CI=1.26-2.87, p<0.01) and specific IgE levels above the threshold value than Labrador retrievers, suggesting that genetic factors influence IgE levels in dogs. Castration was generally associated with low Ab levels (OR=0.43-0.65, p<0.05). Surprisingly, dogs with CAD did not have increased odds for high IgE against any of the allergens tested. ASIT with DF was associated with high DF-specific IgG1 (OR=4.32, 95% CI 1.46-12.8, p<0.01) but was not associated with DF-specific IgG4 or decreased IgE levels. Further studies are needed to understand the role of allergen-specific IgE in CAD and of IgG1 in ASIT.

High allergen-specific serum immunoglobulin E levels in nonatopic West Highland white terriers

Human and canine atopic dermatitis (AD) share an association with IgE specific to environmental allergens, but few studies have evaluated serum allergen-specific IgE in nonatopic dogs. This study compared serum allergen-specific IgE levels in 30 atopic and 18 nonatopic West Highland white terriers. Atopic dermatitis was confirmed using standard criteria. Nonatopic dogs were over 5 years of age and had no clinical signs or history of AD. Serum allergen-specific IgE levels were measured with Allercept(®) IgE ELISAs using a 48-allergen Australian panel. Positive reactions were defined as ≥150 ELISA absorbance units. Intradermal tests were performed in 16 atopic dogs, either at the time of or at various times prior to serum collection. In atopic dogs, the most common positive ELISA and intradermal test results were to Dermatophagoides farinae (11 of 30 dogs), but there were no statistically significant correlations between results from the two methods for any allergen. In nonatopic dogs, multiple high-positive ELISA reactions were reported to 45 of 48 allergens, most commonly D. farinae and Tyrophagus putrescentiae (17 of 18 dogs each). Positive ELISA results in nonatopic dogs were statistically significantly higher than those in atopic dogs for 44 of 48 allergens, including two allergens (D. farinae and Dermatophagoides pteronyssinus) commonly regarded as significant in canine AD. In conclusion, positive allergen-specific IgE ELISAs were not specific for canine AD, and high allergen-specific IgE levels were seen in nonatopic dogs. The clinical significance of this and whether it characterizes a protective phenotype is unclear.

Feline-specific serum total IgE quantitation in normal, asthmatic and parasitized cats

Immunoglobulin E (IgE) plays an important role in defense against parasitic infections as well as allergy. Knowledge of serum total IgE concentrations may have value in diagnosis and prognostication of various disorders; however, to date, no studies have reported feline serum total IgE concentrations. We hypothesize that serum total IgE concentrations will be greater in spontaneously parasitized and asthmatic cats compared to healthy pet cats. Healthy (n=10), parasitized (10) and asthmatic cats (eight) had measurement of serum total IgE by ELISA. Data were analyzed using a t-test with P<0.05 considered significant. Serum total IgE was higher in parasitized (mean±SEM, 328.4±123.8μg/ml; P<0.028) and asthmatic cats (85.5±19.5μg/ml; P<0.047) compared to healthy cats (45.9±19.6μg/ml). However, serum total IgE had poor discriminatory capability between diseased and healthy cats. In conclusion, this assay can detect small quantities of feline serum total IgE, which may be beneficial in future studies of parasitism or allergic disease.

Canine immunoglobulin E

Canine IgE discovery and characterization historically closely paralleled that of human IgE. The reason for this would seem to be the early recognition of the spontaneous manifestation of allergic diseases in dogs that are nearly identical to human allergic diseases. The discovery and characterization of human IgE being dependent upon its biological activity in sensitizing mast cells and basophils was matched early on by analogous approaches readily applied to dogs. Following the early work on IgE, cloning and sequencing of the IgE heavy chain, epsilon, lagged well behind the human and rodent for want of IgE producing canine myelomas. As with human allergic diseases, measurement of allergen-specific and total IgE in canine tissues and body fluids revealed the same associations with various disease manifestations that some times defied discovery of straight-forward cause and effect relationships because of the complexity of pathogenesis in spontaneous allergic disease. However it is clear that research on IgE in spontaneously allergic dogs offers many opportunities to explore novel immunotherapeutic approaches to the control of allergic disease that will benefit both dogs and humans.

Generation of therapeutic antibody responses against IgE in dogs, an animal species with exceptionally high plasma IgE levels

Allergic diseases are common in dogs and the involvement of IgE in the pathogenesis of canine atopic dermatitis (CAD) and flea allergy dermatitis (FAD) is documented. However, many dogs do not achieve sufficient control of their allergic disease, and there is a great need for new treatment strategies. In order to address this issue we first needed to obtain a better picture of IgE-levels in dogs and how plasma IgE-levels are affected by breed, age and health status. IgE is normally present at diminutive concentrations in sera and detection by diagnostic methods has been a technical challenge. Here, we present a new in vitro assay for determining absolute levels of total IgE in sera from dogs. In a panel of 76 adult dogs diagnosed either as healthy or suffering from atopic dermatitis, autoimmunity or infection by skin parasites, we show that levels of IgE range from 1 to 41 microg/ml. This is almost 100 times the level observed in non-atopic humans. However, these exceptionally high IgE-levels in the dogs could not be correlated to either breed or health status. To address the issue of novel treatment strategies, the possibility of reducing the IgE-levels in nine Beagle dogs by immunization with a new therapeutic vaccine was investigated. High levels of anti-IgE antibodies were induced in all dogs, and the IgE-levels were subsequently decreased by a mean of 65%. This shows that the allergy vaccine is potent enough to break the tolerance against IgE, even when the initial IgE-levels are as high as those observed in dogs. Thus, the vaccination treatment may have the potential to serve as a future therapy for dogs with atopic diseases.