Seasonal atopic dermatitis in dogs sensitive to a major allergen of Japanese cedar (Cryptomeria japonica) pollen

Evaluation of the correlation of serological and intradermal allergen testing with clinical history in 29 dogs with atopic dermatitis

BACKGROUND

Limited information exists about the correlation between clinical history and positive serum (SAT) and intradermal allergen test (IDAT) results in atopic dogs.

OBJECTIVES

To evaluate the correlation between clinical history and SAT/IDAT results in atopic dogs.

ANIMALS

Twenty-nine client-owned dogs with nonseasonal atopic dermatitis with or without seasonal exacerbation were enrolled.

MATERIALS AND METHODS

IDAT, SAT (immunoglobulin (Ig)M antibody capture enzyme-linked immunosorbent assay [MacELISA] with bromelain CCD inhibitor) and clinical information collected in a questionnaire regarding seasonal variations in pruritus affecting the dogs were performed on the same day. Two independent investigators (Inv A and Inv B) recorded IDAT results.

RESULTS

The kappa coefficients agreement for positive IDAT scores between Inv A and B was substantial. The agreement between IDAT and SAT results at different ELISA absorbance units (EAU) cut-offs (>79 and ≥300) was slight and fair for both investigators, respectively. A higher agreement was observed between IDAT and SAT (≥300 EAU) than between IDAT and SAT (>79 EAU) with the exception of mite and flea allergens. There was a statistically significant association between clinical history and positive IDAT results for seasonal allergens (Inv A and Inv B, p = 0.016). There was no significance between positive SAT results and clinical history. Five (IDAT) and 12 of 13 (SAT) atopic dogs without clinical seasonal exacerbation showed positive results for seasonal allergens.

CONCLUSIONS AND CLINICAL RELEVANCE

The agreement between IDAT and SAT ≥300 EAU results was fair and the agreement between IDAT and SAT >79 EAU results was slight for all allergens. Only positive IDAT results significantly correlated with clinical history.

Development and characterization of a unique anti-IgE mouse monoclonal antibody cross-reactive between human and canine IgE

Background

The efficacy assessment of human anti‐IgE monoclonal antibodies (mAbs) in animal models before clinical trials is hampered due to the lack of cross‐reactivity of anti‐IgE mAbs between species.

Objective

We developed CRE‐DR (an anti‐dog IgE monoclonal antibody), an anti‐IgE mouse mAb that recognizes canine and human IgE, and then examined its IgE specificity and cross‐reactivity between three animal and human species.

Methods

After mouse immunization with a synthetic peptide derived from canine IgE (²⁸²NTNDWIEGETYYC²⁹⁴), we generated a hybridoma producing CRE‐DR. The CRE‐DR purified from the ascites of hybridoma‐inoculated mice was used for ELISA and Western blot analysis to examine reactivity to dog, human, and rodent IgEs as well as recombinant bovine serum albumin (BSA)‐conjugated to canine, human, and rodent IgE amino acid peptides corresponding to the immunizing sequence. We then performed enzyme‐linked immunosorbent assays (ELISAs) for dog IgE using sera from dogs with atopic dermatitis (AD) after inhibition with canine IgE and IgG. The amino acid sequence recognized by CRE‐DR was identified by ELISA using synthetic peptides.

Results

CRE‐DR is a monoclonal mouse IgG1κ specific for dog IgE, and the ELISA values in atopic dog sera were inhibited by dog IgE, but not dog IgG. The binding of CRE‐DR to human IgE was relatively maintained, but not to rodent IgEs, which results were confirmed with the BSA‐conjugated IgE peptides of the various species. The CRE‐DR reactivity was supported by the comparison of amino acid sequence of CRE‐DR epitope, DWIEGETYYC, in dog IgE; one, two, and three amino acids were substituted in the human, rat, and mouse IgE epitopes, respectively.

Conclusions and Clinical Relevance

CRE‐DR is a mAb cross‐reactive to dog and human IgEs, which can allow the use of a dog model of allergy to test the efficacy of a CRE‐DR‐derived anti‐IgE therapeutic mAb before human clinical trials.

Multivariable analysis of the influence of cross-reactive carbohydrate determinant inhibition and other factors on intradermal and serological allergen test results: a prospective, multicentre study

BACKGROUND

Serological allergen testing (SAT) is used widely to formulate allergen-specific immunotherapy for atopic dogs. Serum immunoglobulin (Ig)E specific for cross-reactive carbohydrate determinants (CCD) can produce false-positive reactions, creating discrepancy between SAT and intradermal allergen test (IDAT) results.

OBJECTIVES

The primary objective was to determine if inhibition of anti-CCD IgE in a commercial assay improved correlation with IDAT. The secondary objective was to assess the influence of dog- and clinic-specific factors, environmental factors, putative allergen exposure and prior medications on intradermal and SAT reactivity.

ANIMALS

Two-hundred and eleven client-owned dogs were enrolled from eight North American dermatology specialty practices.

METHODS AND MATERIALS

Collection of serum samples and IDAT were performed on the same day. Sera were assayed for detection of IgE specific to 25 allergens, before and after treatment with a proprietary inhibitor of anti-CCD IgE. Data for each dog were collected via a questionnaire filled out by veterinary personnel.

RESULTS

The correlation between the testing modalities was fair before (Spearman's rho, ρ = 0.2092) and after (ρ = 0.3042) inhibition of anti-CCD IgE. Ciclosporin dose (P = 0.003), independent of duration of use, and duration of lokivetmab use (P = 0.001), independent of dose administered, were associated with statistically significant decreases in IgE concentrations across all allergen types.

CONCLUSIONS AND CLINICAL RELEVANCE

Contrary to previous reports, this study demonstrated unchanged correlation between SAT and IDAT after inhibition of anti-CCD IgE. Ciclosporin dose and lokivetmab treatment duration may have unexplored effects on IgE concentration during SAT.

Epidemiological survey of anti-flea IgE in dogs in Japan by using an antigen-specific IgE quantitative measurement method

In Japan, an epidemiological survey was performed in dogs from October to December 2008 by using a quantitative measurement method for antigen-specific IgE towards specific Ctenocephalides felis antigens. 214 dogs from 22 veterinary clinics were included. These clinics were located as follows, from North to South: Hokkaido, Aomori, Fukushima, Tochigi, Saitama, Chiba, Tokyo (Tama-City and Ota-ku), Kanagawa, Gifu, Niigata, Kyoto, Nara, Osaka, Hyogo, Kagawa, Ehime, Hiroshima, Yamaguchi, Fukuoka, Kumamoto and Kagoshima. 110 dogs (51.4%) were seropositive for flea-specific IgE. No differences were associated with gender or breed. This survey confirms that flea infestation in dogs is a common problem in Japan. It especially shows that the infestation also occurs in Northern Japan where fleas are considered uncommon by the vet.

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.

DNA vaccination against Japanese cedar pollinosis in dogs suppresses type I hypersensitivity by controlling lesional mast cells

Sensitization to allergens of Japanese cedar pollen is known to cause canine atopic dermatitis as approximately 10% of atopic dogs in Japan were positive to the pollen allergen. Among the two major allergens of Japanese cedar pollen, since Cry j 1 is more important than Cry j 2 as an antigen to increase IgE in atopic dogs sensitized to Japanese cedar pollen, Cry j 1 can be a target for immunotherapy. In our study, efficacy of DNA vaccination with a plasmid containing the gene of a major allergen of Japanese cedar (Cryptomeria japnonica, CJ) pollen, Cry j 1, was examined using a dog model experimentally sensitized to CJ pollen allergen. Cry j 1 DNA plasmid and a vector plasmid (pCAGGS) were injected into six dogs and three dogs, respectively, five times with an interval of 1.5 month. After the treatment with Cry j 1 DNA plasmid, production of IgE against Cry j 1 decreased in four of the six dogs in the treatment group, whereas it increased in the three dogs of the control group. The reactivity to the pollen allergen in intradermal testing and provocation testing were obviously reduced in the treatment group, but not in the control group. The number of mast cells in alveolar area of the lung in the treatment group was smaller than that in the control group. Cry j 1 DNA plasmid was also injected into three atopic dogs sensitive to Cry j 1, resulting in improvement of clinical signs in the pollination season. These findings indicated that Cry j 1 DNA plasmid could regulate mast cell-mediated reaction against Cry j 1, which could be an alternative and effective treatment for CJ pollinosis.

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.

Identification of peptides containing T-cell epitopes of Japanese cedar (Cryptomeria japonica) pollen allergen (Cry j 1) in dogs

Japanese cedar (Cryptomeria japonica, CJ) pollen has been known to cause atopic dermatitis in dogs in Japan. However, since the mechanism of the CJ antigen recognition is not well understood in dogs, it is difficult to develop effective immunotherapy for atopic dermatitis caused by sensitization to CJ pollen. In order to aim at development of a peptide immunotherapy, we tried to identify T-cell epitopes of a major allergen of CJ pollen, Cry j 1, in dogs sensitive to CJ pollen allergen. Peripheral blood mononuclear cells (PBMCs) obtained from 22 dogs experimentally sensitized to CJ pollen allergen and 5 atopic dogs sensitive to CJ pollen allergen were used for mapping of T-cell epitopes of Cry j 1 using 35 kinds of synthesized overlapping peptides of Cry j 1. Reactive peptides were identified based on the results of blastogenic responses of PBMCs against the peptides when the stimulation indices were beyond 2.0. Three reactive peptides were identical in a relatively high population of experimental dogs, which were Nos. 8 (p71-90) (41%), 10 (p91-110) (50%), and 11 (p101-120) (41%). It was considered that these synthesized peptides should contain T-cell epitopes of Cry j 1 in the dogs. However, there were no reactive peptides identical among the five atopic dogs spontaneously sensitive to CJ pollen. The population of dogs experimentally sensitized to CJ pollen antigen will be used in order to investigate effects of a peptide immunotherapy using the reactive peptides. The results in atopic dogs sensitive to CJ pollen antigen will also provide useful information on necessity to develop a tailor-made immunotherapy using reactive peptides in each dog.

Evaluation of the clinical and allergen specific serum immunoglobulin E responses to oral challenge with cornstarch, corn, soy and a soy hydrolysate diet in dogs with spontaneous food allergy

Fourteen dogs with known clinical hypersensitivity to soy and corn were maintained on a limited antigen duck and rice diet until cutaneous manifestations of pruritus were minimal (78 days). Sequential oral challenges with cornstarch, corn and soy were then performed. Subsequently, the dogs were fed a diet containing hydrolysed soy protein and cornstarch. Throughout the study period the dogs were examined for cutaneous manifestations of pruritus and, additionally, serum was collected for measurement of allergen-specific and total immunoglobulin (Ig)E concentrations. Intradermal testing with food antigens was performed prior to entry into the study and after 83 days. A statistically significant clinical improvement was measured between days 0 and 83. Significant pruritus was induced after oral challenge with cornstarch, corn and soy (P = 0.04, 0.002, 0.01, respectively) but not with the hydrolysed diet (P = 0.5). The positive predictive value of the skin test for soy and corn allergy was reduced after feeding a soy and corn free diet. Although increases in soy and corn-specific serum IgE concentrations were measured in individual dogs post challenge they were not statistically significant and could not be used to predict clinical hypersensitivity.

Cytokine profiles of peripheral blood mononuclear cells from dogs experimentally sensitized to Japanese cedar pollen

Japanese cedar (Cryptomeria japonica, CJ) pollinosis is mediated by type-I hypersensitivity and induces seasonal rhinitis and conjunctivitis in humans. Previous studies showed that dogs could be experimentally sensitized with CJ pollen. In this study, we carried out quantitative analysis of mRNA levels of various cytokines in the peripheral blood mononuclear cells (PBMC) of 12 dogs experimentally sensitized to Japanese cedar pollen. Experimental sensitization was carried out by injection of crude CJ pollen extract with aluminium hydroxide gel. The expression levels of interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, IL-18, interferon (IFN)-gamma, transforming growth factor (TGF)-beta(1), and tumor necrosis factor (TNF)-alpha mRNAs in the PBMC were quantified using a real-time sequence detection system. In the PBMC tested without culture, the expression levels of IL-8 and TNF-alpha mRNAs in experimentally sensitized dogs were significantly higher than those in control dogs. The expression level of IFN-gamma mRNA in the sensitized group was significantly lower than that in the control group. When the PBMCs were cultured in the presence of CJ pollen extract, the level of IL-4 mRNA expression was markedly increased in the PBMC from the experimentally sensitized dogs. In the PBMC stimulated with the CJ pollen extract, the expression level of IL-2 mRNA in the sensitized group was also significantly higher than that in the control group. Our data indicated that a Th2 response and proliferation of PBMC occur in response to the sensitizing antigen in dogs experimentally sensitized with CJ pollen, and revealed the presence of antigen-specific Th2 cells in this canine model. In addition, the expression levels of the mRNAs encoding proinflammatory cytokines were shown to be elevated after CJ pollen sensitization, indicating the activation of monocytes and macrophages.

The ACVD task force on canine atopic dermatitis (XVI): laboratory evaluation of dogs with atopic dermatitis with serum-based "allergy" tests

Serum-based in vitro "allergy tests" are commercially available to veterinarians, and are widely used in diagnostic evaluation of a canine atopic patient. Following initial clinical diagnosis, panels of allergen-specific IgE measurements may be performed in an attempt to identify to which allergens the atopic dog is hypersensitive. Methodology for these tests varies by laboratory; few critical studies have evaluated performance of these tests, and current inter-laboratory standardization and quality control measures are inadequate. Other areas where information is critically limited include the usefulness of these tests in diagnosis of food allergy, the effect of extrinsic factors such as season of the year on results, and the influence of corticosteroid treatment on test results. Allergen-specific IgE serological tests are never completely sensitive, nor completely specific. There is only partial correlation between the serum tests and intradermal testing; however, the significance of discrepant results is unknown and unstudied. Variation in test methodologies along with the absence of universal standardization and reporting procedures have created confusion, varying study results, and an inability to compare between studies performed by different investigators.