Dog and Cat Allergies and Allergen Avoidance Measures in Korean Adult Pet Owners Who Participated in a Pet Exhibition

Increasing Prevalence of Sensitization to Cat/Dog Allergens in the COVID-19 Pandemic

INTRODUCTION

Cat and dog allergens are common indoor triggers for respiratory allergies such as allergic rhinitis and asthma. This study aims to evaluate the prevalence of cat and dog allergies in adults and analyze changes during the COVID-19 pandemic.

METHODS

We retrospectively analyzed the medical records of 8,102 patients who visited an allergy clinic and underwent skin prick testing (SPT) from March 2018 to March 2022: 2 years before and 2 years during the pandemic. Demographic information, clinical attributes, and laboratory results were examined based on patient records.

RESULTS

Of 8,102 SPTs performed, 400 (4.9%) were sensitized to cat allergen and 289 (3.6%) to dog allergen. Allergic rhinitis was the predominant clinical diagnosis in both groups. Of the 400 subjects exposed to cats, 240 (60%) experienced allergic symptoms, while of the 289 subjects exposed to dogs, 65 (22.5%) experienced allergic symptoms during exposure. Within the cat-sensitized group, anaphylaxis was observed in 5 patients (1.3%), while no cases of anaphylaxis were reported in the dog-sensitized group. Compared to the pre-pandemic period, patients presenting during the pandemic had higher rates of cat and dog sensitization (5.7% vs. 4.1%; p < 0.05, 5.2% vs. 1.7%; p < 0.05).

CONCLUSION

During the COVID-19 pandemic, there was an increase in cat and dog allergies among adults. Increased exposure to pet antigens, both directly and indirectly, has resulted in more people becoming sensitized to cats or dogs.

KAAACI Guidelines for Allergen Immunotherapy

Allergen immunotherapy (AIT) is a causative treatment for various allergic diseases such as allergic rhinitis, allergic asthma, and bee venom allergy that induces tolerance to offending allergens. The need for uniform practice guidelines in AIT is continuously growing because of the increasing discovery of potential candidates for AIT and evolving interest in new therapeutic approaches. This guideline is an updated version of the Korean Academy of Asthma Allergy and Clinical Immunology recommendations for AIT published in 2010. This updated guideline proposes an expert opinion by allergy, pediatrics, and otorhinolaryngology specialists with an extensive literature review. The guideline deals with basic knowledge and methodological aspects of AIT, including mechanisms, clinical efficacy, patient selection, allergens extract selection, schedule and doses, management of adverse reactions, efficacy measurements, and special consideration in pediatrics. The guidelines for sublingual immunotherapy will be covered in detail in a separate article.

The holo beta-lactoglobulin lozenge reduces symptoms in cat allergy-Evaluation in an allergen exposure chamber and by titrated nasal allergen challenge

BACKGROUND

The allergists´ tool box in cat allergy management is limited. Clinical studies have shown that holo beta-lactoglobulin (holoBLG) can restore micronutritional deficits in atopic immune cells and alleviate allergic symptoms in a completely allergen-nonspecific manner. With this study, we aimed to provide proof of principle in cat allergy.

METHODS

A novel challenge protocol for cat allergy in a standardized ECARF allergen exposure chamber (AEC) was developed. In an open pilot study (NCT05455749), patients with clinically relevant cat allergy were provoked with cat allergen for 120 min in the AEC before and after a 3-month intervention phase (holoBLG lozenge 2x daily). Nasal, conjunctival, bronchial, and pruritus symptoms were scored every 10 min- constituting the total symptom score (TSS). Peak nasal inspiratory flow (PNIF) was measured every 30 min. In addition, a titrated nasal provocation test (NPT) was performed before and after the intervention. Primary endpoint was change in TSS at the end of final exposure compared to baseline. Secondary endpoints included changes in PNIF, NPT, and occurrence of late reactions up to 24 h after exposure.

RESULTS

35 patients (mean age: 40 years) completed the study. Compared to baseline, holoBLG supplementation resulted in significant improvement in median TSS of 50% (p < 0.001), as well as in median nasal flow by 20 L/min (p = 0.0035). 20% of patients reported late reactions after baseline exposure, but 0% after the final exposure.

CONCLUSIONS

Cat allergic patients profited from targeted micronutrition with the holoBLG lozenge. As previously seen in other allergies, holoBLG supplementation also induced immune resilience in cat allergies, resulting in significant symptom amelioration.

Clinical characteristics of cat sensitized adults, cat ownership and cat owners' attitudes

Background: Cat allergen sensitization is a significant risk factor for allergic rhinitis and asthma. There are insufficient data on the preferences and attitudes of cat owners who have a cat allergy. Objective: To investigate the clinical characteristics of adults sensitized to cats and their association with cat ownership, and to assess owners' attitudes and behaviors. Methods: The study evaluated adult patients, ages between 19 and 74 years, who were sensitized to cat allergen as confirmed by skin-prick tests. The demographic and clinical data of the patients were obtained retrospectively from the hospital medical records system. A telephone interview with patients was conducted to evaluate whether they owned a cat and their attitudes toward cat allergy. A total of 143 patients who could not be reached by telephone or who refused to participate in the study were excluded. Patients were categorized into never owned a cat, early cat ownership (having a cat or cats in the first 2 years of the patient's life), and past and current cat ownership according to the status of patients at the time of their skin-prick test. Current cat owners were questioned whether they relinquished their cats and the presence and the degree of symptoms of both patients who relinquished their cats and patients who continued to live with their cats. Results: A total of 245 patients (women/men, 151/94) with a mean age of 31.56 ± 11.33 were included in the study. Eighty-three patients (33.9%) were current cat owners. After the skin-prick test, 54 cat owners (66.1%) continued living with their cats. Two-thirds of these owners were symptomatic, with 95% experiencing nasal symptoms. Only five of the patients with symptoms (14.3%) reported worsening symptoms. Any significant impact on symptoms was not determined with regard to number of cats, cat breeds, and precautionary measures. Conclusion: Cat allergen is a potential risk for public health. The clinician must engage in shared decision-making as to what type of environmental changes that the patient is willing to make and what treatment options, if any, they are ready to accept, recognizing that most patients will prefer to keep their cats.

The association between specific IgE antibodies to component allergens and allergic symptoms on dog and cat exposure among Korean pet exhibition participants

Background

Component resolved diagnostics (CRD) in dog and cat allergy is not sufficiently investigated, especially regarding new components such as Can f 4, Can f 6, and Fel d 7. The purpose of this study is to evaluate the potential role of CRD with new components in predicting allergic symptoms on dog and cat exposure.

Methods

Among 552 Korean adults who participated in a pet exhibition and completed questionnaires regarding exposure to dog or cat and allergic symptoms, 522 were venipunctured for measurement of IgE and IgG4 antibody concentration against dog and cat dander extract and underwent skin prick test (SPT). In 238 individuals who were sensitized for both dog and cat dander extract, the dog IgE components (Can f 1–6) and the cat components (Fel d 1/2/4/7) were analyzed.

Results

An increasing number of sensitizing components was associated with the likelihood of having any allergic symptoms (P < 0.001 for dog and P < 0.01 for cat), and those of asthma (P < 0.01 for dog and P < 0.05 for cat) and rhinoconjunctivitis (P < 0.001 for dog and P < 0.05 for cat). Pairwise correlation of IgE levels was r = 0.56 (P < 0.001) for Can f 6 and Fel d 4, r = 0.74 (P < 0.001) for Can f 1 and Fel d 7 and r = 0.84 (P < 0.001) for Can f 3 and Fel d 2.

Conclusions

Polysensitization to dog and cat allergen components is associated with high likelihood of having allergic symptoms during exposure to dogs and cats. Cross-reactivity between dog and cat allergen components is also identified. CRD has a potential in fine-tuning prediction for allergic symptoms on dog and cat exposure.

Shukri N, Wong KK, Mohd Ashari NS. Zonula occludens-1 expression is reduced in nasal epithelial cells of allergic rhinitis patients

Allergic rhinitis (AR) is a common allergic disease characterized by disruption of nasal epithelial barrier. In this study, we investigated the mRNA expression of zonula occludens-1 (ZO-1), ZO-2 and ZO-3 and histone deacetylase 1 (HDAC1) and HDAC2 in AR patients compared to healthy controls. RNA samples were extracted from nasal epithelial cells of house dust mites (HDMs)-sensitized AR patients and healthy controls (n = 28 in each group). The RNAs were reverse transcribed into cDNAs for measurement of ZO-1, ZO-2, ZO-3, HDAC1 and HDAC2 expression levels by quantitative PCR. The mRNA expression of ZO-1 was significantly decreased in AR patients compared to healthy controls (p = 0.010). No significant difference was observed in the expression levels of ZO-2, ZO-3, HDAC1 and HDAC2 in AR patients compared to healthy controls. We found significant associations of higher HDAC2 levels in AR patients with lower frequency of changing bedsheet (p = 0.043) and with AR patients sensitized to Dermatophagoides farinae (p = 0.041). Higher expression of ZO-2 was observed in AR patients who had pets (p = 0.007). In conclusion, our data indicated that ZO-1 expression was lower in AR patients contributing to decreased integrity of nasal epithelial barrier integrity, and HDAC2 may be involved in the pathogenesis of the disease.

Human allergy to cats: A review for veterinarians on prevalence, causes, symptoms and control

PRACTICAL RELEVANCE

Human allergy to cats affects a substantial and growing proportion of the global population, and cat allergy is regarded as the third most common cause of human respiratory allergies, and the second most common indoor cause. Veterinarians will frequently encounter owners who are cat-allergic, and having an understanding of this disease and the methods available to help control the allergy will assist them in giving appropriate advice, alongside human healthcare professionals.

AIM

The aim of this review is to summarise currently available data on the prevalence, causes, symptoms and control of human allergy to cats. In terms of managing cat allergy, the emphasis is on reviewing current and emerging modalities to reduce environmental exposure to cat allergens rather than on pharmacotherapy or immunotherapy, as it is in these areas in particular that the veterinarian may be able to offer help and advice to complement that of human healthcare professionals.

EVIDENCE BASE

The information in this review is drawn from the current and historical literature on human allergy to cats, and approaches to reduce exposure to cat allergens and manage symptoms of cat allergy.

[Sensitization pattern of cat and dog dander allergen in 16 426 patients with allergic diseases]

Objective:To explore the sensitization feature of cat and dog dander and time trend in northern region. Methods:During year 2017 to year 2019, subjects with self-reported allergic diseases received skin prick test for cat and dog dander allergen. Skin index（SI） ≥2+ was considered as positive SPT. SI2+ was defined as mild sensitization, SI3+ was defined as moderate sensitization while SI4+ was defined as severe sensitization. The age and gender difference of sensitization rate between cat and dog dander allergen was analyzed. Meanwhile, the trend of cat and dog dander sensitization rate was analyzed. Results:Overall, 16 426 subjects were enrolled in this study. ① The sensitization rate of cat dander was significantly higher than dog dander（11.8% vs 6.0%, P<0.001）. Severe sensitization rate of cat dander was significantly higher than dog dander（5.9% vs 1.7%, P<0.001） while there was no significant difference of mild sensitization rate. ②Sensitization age of cat dander was younger than dog dander（P<0.001）. Sensitization rate of cat and dog dander was higher in subjects ≤18y compared with those >18y（20.2% vs 10.9%, P<0.001; 8.1% vs 5.7%, P<0, 001）. The highest sensitization rate was presented in 13-18y age group（27.3% vs 9.9%, P<0.001）, following by 7-12y age group（26.0% vs 9.2%, P<0.001）. Sensitization rate of cat dander was higher in male than in female（13.7% vs 10.7%, P<0.001） while no gender difference was observed in dog dander sensitization（6.2% vs 5.8%, P=0.411）. ③595 subjects（3.6%） were both sensitized to cat and dog dander while 1733 subjects（10.6%） were sensitized either to cat or dog dander. Single sensitization rate of cat dander was higher than single sensitization rate of dog dander（8.2% vs 2.3%, P<0.001）. There was a positive correlation between the cat and dog dander sensitization rate（r=0.386, P<0.001）. ④During 2017-2019, the sensitization rate of cat dander increased but without significantly statistic difference while dog dander sensitization rate was descending from 7.4% to 4.6% significantly（χ²=38.298, P<0.001）. Conclusion:Cat dander sensitization rate was higher than dog dander with a peak age in adolescence. A trend of rising for cat dander allergy and descending for dog dander allergy was observed during the past three years.

Cat-NPC2, a Newly Identified Allergen, With High Cross-Reactivity to Can f 7

Purpose

Pet-derived allergens are the common indoor inhalant allergens. Among them, cat and dog allergens constitute more than 80% of animal allergic patients, which greatly affect the quality-of-life of patients and increase the burden of social health care. The aim of this study was to identify Cat-Niemann pick type C2 (NPC2) protein, a homologue of Can f 7, as a new allergen.

Methods

Cat-NPC2 complementary DNA (cDNA) was cloned and optimized for amplification and expression in Escherichia coli. Then, recombinant Cat-NPC2 (rCat-NPC2) was purified by Ni²⁺ affinity chromatography. The allergenicity was assessed by enzyme-linked immunosorbent assay (ELISA), western blot and basophil activation test (BAT). Based on the sequence similarity, the cross-reactivity between Cat-NPC2 and Can f 7 was investigated by inhibition ELISA. Circular dichroism spectroscopy and homology modeling were used to characterize the structure of Cat-NPC2.

Results

The cDNA sequence of Cat-NPC2 was cloned with a 450-bp open reading frame coding for 149 amino acids (GenBank MN_737596). The condon-optimized NPC2 gene was subcloned and expressed in E. coli with a molecular weight of 18.9 kDa. The native Cat-NPC2 was detected in cat dander extracts. The allergenicity determined by ELISA, western blot and BAT suggested at least 14.5% cat-allergic patients displayed high specific immunoglobulin E (IgE) recognition of Cat-NPC2. The predicted structure of Cat-NPC2 was found to consist of 7 β-strands arranged in 2 β-sheets. An ELISA based assay showed that rCat-NPC2 bound to cholesterol in a dose dependent manner. Based on the structure and sequence similarities, IgE cross-reactivity was demonstrated between Cat-NPC2 and Can f 7/Der f 2.

Conclusions

In the study, a novel cat allergen, belonging to the NPC2 protein family, was identified and characterized at both molecular and immunological levels. The study will offer a deeper understanding of cat allergens and improve a component-resolved diagnosis in pet allergy.

The role of allergen-specific IgE in predicting allergic symptoms on dog and cat exposure among Korean pet exhibition participants

BACKGROUND

The values of the skin prick test (SPT) and allergen-specific IgE (sIgE) measurement in predicting dog and cat allergies remain unclear. We aimed to evaluate the usefulness of SPT and sIgE measurement in predicting self-reported allergic symptoms during exposure to dogs and cats in Korean adults.

METHODS

A total of 552 participants in a pet exhibition in Korea completed questionnaires regarding exposure to dog or cat and the development of allergic symptoms during exposure. Study participants also underwent SPT using 3 different commercially available reagents, and had their blood drawn for measurement of serum total IgE and dog/cat-dander-IgE using ImmunoCAP®.

RESULTS

Measurement of sIgE for dog and cat dander allergens provided the highest positive and negative predictive values and sensitivity, but not specificity (58%, 87.2%, 67.9%, and 93.1% for allergic symptoms on dog exposure; 64.7%, 83.2%, 74.8%, and 88.9% for those on cat exposure, respectively), in predicting self-reported allergic symptoms on dog and cat exposure. The sIgE level consistently exhibited the highest area under the receiver operating characteristic curve (0.749 and 0.719 for allergic symptoms on dog and cat exposure, respectively). Careful interpretation of SPT and sIgE measurements maximized the positive and negative predictive values, sensitivity, and specificity for predicting allergic symptoms on dog exposure (71.4%, 87.3%, 75.3%, and 99.3%) and those on cat exposure (71.4%, 85.3%, 79.3%, and 98.9%).

CONCLUSIONS

The measurement of dog and cat dander sIgE levels may be useful for the exclusion of allergic symptoms related to pet exposure. Collective interpretation of SPT and sIgE tests facilitates identification of allergic symptoms on dog or cat exposure, giving a better rule-in test result.

IgE recognition profile of aeroallergen components in young children sensitized to dogs

Background

Pet ownership is increasing rapidly and as growing numbers of dogs in household, clinicians are facing more allergic patients and so as in young children.

Objective

This study aims to profile the IgE recognition patterns to aeroallergen components in young children sensitized to dogs.

Methods

Through retrospective chart reviews, we evaluated the clinical, environmental, and laboratory findings of patients sensitized to dogs in early life. We further evaluated specific IgE to dog component allergens (Can f 1, Can f 2, and Can f 3) and other aeroallergens using a microarray.

Results

The median age of 28 patients sensitized to dogs (dog-specific IgE ≥ 0.35 kU/L; 0.38–101 kU/L) was 61 months and underlying diseases included doctor diagnosed atopic dermatitis (n = 17), asthma (n = 7), and allergic rhinitis (n = 5). Twenty patients (71.4%) had experienced self-reported dog allergy and 70.0% of them were symptomatic after exposed to dogs from others. Component-resolved diagnosis was performed on 18 patients. Can f 1 positivity was the most common (77.8%) but had no value in symptom prediction. The most common cosensitized aeroallergen was house dust mites (44.5%). The symptomatic group tended to be poly-sensitized to Can f 1, Can f 2, and Can f 3.

Conclusion

Can f 1 was dominantly detected and poly-sensitized to Can f 2 and/or Can f 3 simultaneously tend to develop hypersensitivity to dogs in young children. Most of them were exposed to dogs not living with.

The time window of pet ownership exposure modifies the relationship of Environmental Tobacco Smoke with lung function: A large population-based cohort study

There is a large body of evidence linking Environmental Tobacco Smoke (ETS) exposure with impaired lung function. However, it is not known whether exposure to pets modifies this relationship. To investigate if pet ownership changes the association between ETS exposure and lung function, a population-based sample of 7326 children, 7-14 years old, were randomly recruited from 24 districts in northeast China. Lung function including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), peak expiratory flow (PEF), and maximal mid-expiratory flow (MMEF) was measured by spirometry, while pet ownership time periods and ETS exposure were collected by questionnaire. Two-level regression analysis was done, with covariates controlled for. The results showed pet exposure in certain early lifetime windows modified the associations of ETS exposure on decreased lung function in children. Among children exposed to current ETS, those exposed to pets in utero had greater reductions in lung function (for instance: OR for reduced FVC (<85% predicted) = 10.86; 95% CI: 3.80-30.97) than those not exposed to pets in utero (OR = 2.32; 95% CI: 1.76-3.05) (p_interaction = 0.005). While, children exposed to current pet ownership reduced the lung function impairment induced by ETS exposure during the first 2 years of life and/or ETS exposure during pregnancy, especially for FVC impairment. For instance, OR (95%CI) for reduced FVC (<85% predicted) was 0.81 (0.56, 1.18) and 1.42 (1.15, 1.74), respectively, for children with or without current pet ownership exposed to ETS during the first 2 years of life (p_interaction = 0.010). Furthermore, pet type or number of pets did not significantly modify associations between ETS exposure and lung function. In conclusion, the timing of pet ownership modified associations between ETS exposure and lung function, pet ownership in utero and during the first 2 years of life significantly worsened the adverse impacts of passive smoking on lung function.