Cat Allergy as a Source Intensification of Atopic Dermatitis in Adult Patients

Cytokines and chemokines modulation of itch

Itch (pruritus) is a common cutaneous symptom widely associated with many skin complaints, and chronic itch can be a severe clinical problem. The onset and perpetuation of itch are linked to cytokines, such as interleukin (IL)-31, IL-4, IL-13, IL-33, thymic stromal lymphopoietin, and tumor necrosis factor-alpha, and chemokines, such as chemokine (C-C motif) ligand 2 and C-X-C motif chemokine ligand 10. This review highlights research that has attempted to determine the attributes of various cytokines and chemokines concerning the development and modulation of itch. Through such research, clinical approaches targeting cytokines and/or chemokines may arise, which may further the development of itch therapeutics.

Aeroallergens in Atopic Dermatitis and Chronic Urticaria

PURPOSE OF REVIEW

While aeroallergens are a well-established trigger of asthma and allergic rhinitis, their role in allergic skin diseases such as atopic dermatitis and chronic urticaria remains controversial. This paper reviews the pathophysiology and clinical evidence for aeroallergens in these allergic skin diseases and summarizes current strategies for evaluation and management.

RECENT FINDINGS

Current evidence implicates aeroallergens as triggers of cutaneous reactions in atopic dermatitis. Direct skin contact is the likely route of trigger. Aeroallergens may also trigger chronic urticaria, though mechanistic studies are limited. These allergens may cross the skin barrier and directly trigger neurons to release substance P, resulting in mast cell degranulation and dumping of histamine and prostaglandin D2. Many studies link aeroallergen sensitization to chronic urticaria, and case reports suggest the utility of avoidance strategies. The role of aeroallergens as a trigger is clear in atopic dermatitis and becoming emergent in chronic urticaria. Skin prick testing or serum-specific immunoglobulin E testing may be used to determine sensitivities. Management at this time centers on avoidance, and further studies are necessary to evaluate the efficacy of aeroallergen immunotherapy for both conditions.

A basophil-neuronal axis promotes itch

Itch is an evolutionarily conserved sensation that facilitates expulsion of pathogens and noxious stimuli from the skin. However, in organ failure, cancer, and chronic inflammatory disorders such as atopic dermatitis (AD), itch becomes chronic, intractable, and debilitating. In addition to chronic itch, patients often experience intense acute itch exacerbations. Recent discoveries have unearthed the neuroimmune circuitry of itch, leading to the development of anti-itch treatments. However, mechanisms underlying acute itch exacerbations remain overlooked. Herein, we identify that a large proportion of patients with AD harbor allergen-specific immunoglobulin E (IgE) and exhibit a propensity for acute itch flares. In mice, while allergen-provoked acute itch is mediated by the mast cell-histamine axis in steady state, AD-associated inflammation renders this pathway dispensable. Instead, a previously unrecognized basophil-leukotriene (LT) axis emerges as critical for acute itch flares. By probing fundamental itch mechanisms, our study highlights a basophil-neuronal circuit that may underlie a variety of neuroimmune processes.

Pruritus Characteristics in Severe Atopic Dermatitis in Adult Patients

Atopic dermatitis (AD) is classified as a most common inflammatory skin disease. The condition is characterized by recurrent eczematous lesions and intense pruritus or itch, a hallmark of AD. The aim of this study was to identify the provoking factors of itch in severe AD adult patients. There were 34 adult patients suffering from AD of the median age of 40 years enrolled into the study and a control group that consisted of 20 healthy subjects. The severity of AD was assessed with the SCORing Atopic Dermatitis (SCORAD) index, pruritus intensity was assessed on a visual analog scale (VAS), and itch aggravating factors were assessed with a questionnaire. Specific IgE (sIgE) antibodies and interleukin IL-33 were measured in venous blood. We found that all the patients with severe AD had intensive itch (VAS: 9-10 points) during the whole day and 30 (88.2%) patients had it during nighttime. The most significant factors aggravating itch were the following: dry skin (27 patients; 79.4%), exposure to dust mite (22 patients; 64.7%,), and emotional distress (17 patients; 50%). Moreover, there was a positive correlation between the intensity of itch and the level of sIgE antibodies to dust mite (p < 0.001). The content of IL-33 was significantly higher in AD patients with severe skin lesions. This exploratory study shows that skin dryness, dust exposure, and distress play an essential role in the exacerbation of AD in the adult population.