Mechanisms of Particles in Sensitization, Effector Function and Therapy of Allergic Disease

Humans have always been in contact with natural airborne particles from many sources including biologic particulate matter (PM) which can exhibit allergenic properties. With industrialization, anthropogenic and combustion-derived particles have become a major fraction. Currently, an ever-growing number of diverse and innovative materials containing engineered nanoparticles (NPs) are being developed with great expectations in technology and medicine. Nanomaterials have entered everyday products including cosmetics, textiles, electronics, sports equipment, as well as food, and food packaging. As part of natural evolution humans have adapted to the exposure to particulate matter, aiming to protect the individual's integrity and health. At the respiratory barrier, complications can arise, when allergic sensitization and pulmonary diseases occur in response to particle exposure. Particulate matter in the form of plant pollen, dust mites feces, animal dander, but also aerosols arising from industrial processes in occupational settings including diverse mixtures thereof can exert such effects. This review article gives an overview of the allergic immune response and addresses specifically the mechanisms of particulates in the context of allergic sensitization, effector function and therapy. In regard of the first theme (i), an overview on exposure to particulates and the functionalities of the relevant immune cells involved in allergic sensitization as well as their interactions in innate and adaptive responses are described. As relevant for human disease, we aim to outline (ii) the potential effector mechanisms that lead to the aggravation of an ongoing immune deviation (such as asthma, chronic obstructive pulmonary disease, etc.) by inhaled particulates, including NPs. Even though adverse effects can be exerted by (nano)particles, leading to allergic sensitization, and the exacerbation of allergic symptoms, promising potential has been shown for their use in (iii) therapeutic approaches of allergic disease, for example as adjuvants. Hence, allergen-specific immunotherapy (AIT) is introduced and the role of adjuvants such as alum as well as the current understanding of their mechanisms of action is reviewed. Finally, future prospects of nanomedicines in allergy treatment are described, which involve modern platform technologies combining immunomodulatory effects at several (immuno-)functional levels.

Allergen-specific immunotherapy for patients with atopic dermatitis sensitized to animal dander

Introduction

Atopic dermatitis (AD) is a chronic inflammatory skin disease, and AD patients are commonly sensitized to house dust mite (HDM). Of the several treatment options available, allergen‐specific immunotherapy (AIT) has been recognized as an effective treatment modality that is directed toward the immunoglobulin E (IgE)‐mediated nature of AD, and subcutaneous administration using HDM is most commonly used for AIT in AD. For patients sensitized to animal (dog or cat) dander, the treatment may not be easy, especially when avoiding the allergen is not possible.

Methods

This study enrolled patients with AD who were sensitized to cat and/or dog dander and underwent AIT (n = 19). Patients’ medical information was obtained, including past treatment history, treatment duration of AIT, and the progress of treatment. Also, the specific IgE levels and IgG4 levels were measured before and after AIT.

Results

A total of 19 patients with AD underwent AIT using cat and/or dog dander. The patients consisted of 4 males and 15 females with an average age of 31.74 ± 9.71. Only two patients had AD only, and the other 17 patients had one or more concomitant allergic diseases, such as allergic rhinitis, allergic asthma, or allergic conjunctivitis. Seven patients were not sensitized to HDMs and only sensitized to cat and/or dog dander. The duration of AIT ranged from 2 to 58 months. The symptoms of 17 patients were well‐controlled, requiring only topical treatment and/or oral antihistamines. One patient required systemic cyclosporine, but only of low dose (25 mg/day). The specific IgE levels were decreased (P = .005) and IgG4 levels showed the tendency of increasing after AIT. No adverse events were observed in these patients.

Conclusion

Although a larger number of patients for a longer follow‐up period are needed to precisely assess the treatment efficacy, AIT using cat and/or dog dander may be an effective treatment option for AD patients, especially for severe AD patients with other respiratory allergic comorbidities who cannot completely avoid the exposure to animal dander.