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

Mapping Binding Domains of Viral and Allergenic Proteins with Dual-Cleavable Cross-Linking Technology

The dual-cleavable nature of the cross-linking technology (DUCCT) enhances the reliable identification of cross-linked peptides via mass spectrometry. The DUCCT approach uses a cross-linking agent that can be selectively cleaved by two different tandem mass spectrometry techniques: collision-induced dissociation (CID) and electron transfer dissociation (ETD). This results in distinct signatures in two independent mass spectra for the same cross-linked precursor, leading to unambiguous identification and the validation of the spectra. In this study, we expanded the application of the DUCCT cross-linker to evaluate the binding domains of a specific cat dander allergen, Fel d 1, which exists as the Fel d 1 A and B protein complex, and a viral spike protein from SARS-CoV-2, which invades host cells. To assess the cross-linked products obtained by DUCCT, we utilized a software tool called Cleave-XL, which effectively identified cross-linked sites using data from CID and ETD. Dual cleavable cross-linking studies identified cross-linked peptides in these complexes, which have been reported in bioinformatics analysis and proposed for immunotherapy using synthetic peptides. A benchmark study was also conducted using a commercial cross-linker disuccinimidyl suberate (DSS). Overall, we expect that DUCCT cross-linking technology will greatly facilitate the rapid screening of binding interfaces, thereby advancing structural biology and cell signaling investigations.

Impaired respiratory functions in children with cat sensitization in the early ages of childhood

BACKGROUND

To evaluate the respiratory functions in children with cat sensitization accompanying allergic respiratory diseases and to compare these with those of healthy controls, as well as within themselves by classifying according to their diseases, domestic cat exposure, and age groups.

METHODS

This prospective case-control study included 130 children aged 3-17 years with cat sensitization (CS group) accompanying respiratory allergic diseases and 70 age- and sex-matched healthy controls (HC group). The cases' demographic parameters were recorded, and respiratory functions were analyzed using IOS and spirometry.

RESULTS

At IOS evaluation, zR5, R5-20, Fres, and AX values were higher in children in the CS group compared to the HC group (p = 0.029, p = 0.008, p = 0.001, and p < 0.001, respectively), while zX5 and zX20 values were lower (p = 0.001 and p < 0.001). R5-20 and AX were higher in asthma compared to allergic rhinitis (p = 0.008, p = 0.015), but were insignificant compared to asthma and allergic rhinitis coexistent group (p > 0.05). R5-20, Fres, and AX were higher, and zX20 was lower in the preschool age group (p < 0.001). No correlation was found between zFEV1, zFVC, zFEV1/FVC, zFEF25-75, and zR5 values in the CS group (p > 0.05).

CONCLUSIONS

Pulmonary resistance was higher and reactance was lower in the entire and peripheral airways in children with cat sensitization accompanying respiratory allergic diseases compared to the healthy controls. Peripheral airway resistance and reactance were more impaired in the asthma group compared to allergic rhinitis. However, peripheral airway resistance and main airway reactance were more impaired in the preschool age group than in the older ones.

Targeted Gene Knock-Out of Fel d1 in Fetal Fibroblasts Using CRISPR-Cas9: Implications for Cat Allergies

Fel d1 is the most important allergen secreted by cats, which can trigger asthma in sensitive individuals. Our objective was to knock-out the Fel d1 gene in the fetal fibroblasts of cats through CRISPR-Cas9 technology with two sgRNAs and to determine the impact of such mutations on the antigenicity of the Fel d1 protein. DNA samples from 38 domestic cats were collected and amplified by PCR to obtain the complete sequence of the Fel d1 gene. Throughout evolution, Fel d1 polypeptide chain 1(CH1) has proven to be much more conserved than Fel d1 polypeptide chain 2(CH2); therefore, we targeted CH2 and designed two single-guide RNAs (CH2-sgRNA-1 and CH2-sgRNA-2) for this region. Using these constructed sgRNAs, we performed gene knock-out in fetal fibroblasts, resulting in two mutations within the target gene. Following this, DNA was extracted and the target site product was cloned using TA cloning via PCR, and a single colony from this process was sequenced to analyze the physicochemical properties, antigenic sites, and three-dimensional structure of the mutated protein. The results revealed that there were 12 and 51 polymorphic loci (single-nucleotide polymorphisms, or SNPs) found in the CH1 and CH2 sequences, respectively, with most loci located in the GC-rich intron 2, while others were found in exon 2, intron 3, and exon 3. These SNPs guided sgRNA design by identifying conserved regions in the CH2 gene. The gene editing efficiency for the CH2 region, with this dual CRISPR system, was 40%, with 35% attributed to Type 1 mutation and 5% to Type 2 mutation. In conclusion, CH1 is significantly more conserved than CH2, and the antigenicity of the Fel d1 CH2 gene in domestic cats can be effectively reduced through CRISPR-Cas9 gene editing.

Allergy Treatment: A Comprehensive Review of Nanoparticle-based Allergen Immunotherapy

Allergic disorders rising in prevalence globally, affecting a substantial proportion of individuals in industrialized nations. The imbalance in the immune system, characterized by elevated allergen-specific T helper 2 (Th2) cells and immunoglobulin E (IgE) antibodies, is a key factor in allergy development. Allergen-specific immunotherapy (AIT) is the only treatment capable of alleviating allergic symptoms, preventing new sensitizations, and reducing asthma risk in allergic rhinitis patients. Traditional AIT, however, faces challenges such as frequent administration, adverse effects, and inconsistent patient outcomes. Nanoparticle-based approaches have emerged as a promising strategy to enhance AIT. This review explores the utilization of nanoparticles in AIT, highlighting their ability to interact with the immune system and improve therapeutic outcomes. Various types of nanoparticles, including polyesters, polysaccharide polymers, liposomes, protamine-based nanoparticles (NPs), and polyanhydrides, have been employed as adjuvants or carriers to enhance AIT's efficacy and safety. Nanoparticles offer advantages such as allergen protection, improved immune response modulation, targeted cell delivery, and reduced side effects. This review provides an overview of the current landscape of nanoparticle-based allergen immunotherapy, discussing its potential to revolutionize allergy treatment compared to traditional immunotherapy.

Assessing the predictive ability of computational epitope prediction methods on Fel d 1 and other allergens

While computational epitope prediction methods have found broad application, their use, specifically in allergy-related contexts, remains relatively less explored. This study benchmarks several publicly available epitope prediction tools, focusing on the allergenic IgE and T-cell epitopes of Fel d 1, an extensively studied allergen. Using a variety of tools accessible via the Immune Epitope Database (IEDB) and other resources, we evaluate their ability to identify the known linear IgE and T-cell epitopes of Fel d 1. Our results show a limited effectiveness for B-cell epitope prediction methods, with most performing only marginally better than random selection. We also explored the general predictive abilities on other allergens, and the results were largely random. When predicting T-cell epitopes, ProPred successfully identified all known Fel d 1 T-cell epitopes, whereas the IEDB approach missed two known epitopes and demonstrated a tendency to over-predict. However, when applied to a larger test set, both methods performed only slightly better than random selection. Our findings show the limitations of current computational epitope prediction methods in accurately identifying allergenic epitopes, emphasizing the need for methodological advancements in allergen research.

Treatment of Allergies to Fur Animals

Allergy to fur animals is becoming an increasingly common clinical problem in everyday medical practice. Depending on the route of exposure to the allergen, patients present with many, often non-specific symptoms. The most common illnesses among people with allergies to the above-mentioned allergens are as follows: allergic rhinitis, allergic conjunctivitis, atopic bronchial asthma, food allergy, allergic contact dermatitis, and sometimes anaphylactic shock. In recent years, there has been a change in the holistic approach to the treatment of allergy patients. The method of treatment should be tailored to a specific patient, taking into account his or her predispositions, economic possibilities, and therapeutic goals. The article describes the main methods of treating allergies, focusing primarily on allergies to fur animals. Allergy treatment always requires great care, and qualification for specific types of therapy should be preceded by a thorough and accurate diagnosis.

Human-Animal Interaction in Animal-Assisted Interventions (AAI)s: Zoonosis Risks, Benefits, and Future Directions-A One Health Approach

Animal-assisted interventions (AAI)s represent the expression of integrated medicine, according to the One Health approach. Actually, animal-assisted therapies and animal-assisted activities are implemented in hospitals, rehabilitation centers, etc. The efficacy of AAIs is based on interspecific interactions and would be impacted by different factors, such as the characters of both the animal and the handler, a suitable selection of animal species, an appropriate animal educational protocol, the relationship between the handler and the animal, and mutual relationship among the animal, the patients, and members of the working team. AAIs produce many advantages for the patients but could expose them to zoonotic-pathogens transmission. Therefore, positive animal welfare, as preventative medicine to avoid incidents or transmission of zoonosis, is a relevant aspect with implications for human and animal health and wellbeing. This review aims to summarize the current published knowledge regarding the occurrence of pathogens in AAIs and to discuss their relevance in light of health and safety in AAIs participants. In addition, this review will contribute to defining the state of the art of AAIs through a careful benefits/challenges analysis and offers discussion points on the possible future developments according to the One Health approach.

PREDICTION OF ASTHMA CONTROL STATUS IN SCHOOL-AGE CHILDREN SENSITIZED TO CAT ALLERGENS

OBJECTIVE

The aim: To develop a model for predicting asthma control status in school-age children sensitized to cat allergens.

PATIENTS AND METHODS

Materials and methods: The study included 302 children aged 6-17 years who were sensitized to cat allergens. The ALEX² test (Macro Array Diagnostics GmbH, Austria) was used to analyze the sensitization profile in these children. After 12 months of treatment, control of clinical asthma symptoms was achieved in 185 (61.26%) children. Single-factor logistic regression models were constructed to analyze the probability of achieving asthma control in school-age children with sensitization to cat allergens.

RESULTS

Results: It was found that asthma control status depended on the FeNO dynamics after 3 months of treatment, the number of cat allergens to which sensitization was detected, and the duration of exposure to a domestic cat after sensitization tests, which were conducted to verify the allergic capacity to cat allergens. The investigation resulted in the creation of a mathematical model for predicting the probability of asthma control, sensitivity 94.6 (95% CI 90.3 - 97.4) %, specificity - 81.2 (95% CI 72.9 - 87.8) %, PPV = 88.8 (95% CI 84.5 - 92.1) %, NPV = 90.5 (95% CI 83.8 - 94.6) %.

CONCLUSION

Conclusions: A model for predicting the probability of asthma control was created. The formula is used to calculate the patient's P. P > 0.44 allows predicting the achievement of asthma control after 12 months of treatment.