Alternaria as an Inducer of Allergic Sensitization

Abstract

Alternaria alternata is a saprophytic mold whose spores are disseminated in warm dry air, the typical weather of the Mediterranean climate region (from 30° to 45°), with a peak during the late summer and early autumn. Alternaria spores are known to be biological contaminants and a potent source of aeroallergens. One consequence of human exposure to Alternaria is an increased risk of developing asthma, with Alt a 1 as its main elicitor and a marker of primary sensitization. Although the action mechanism needs further investigation, a key role of the epithelium in cytokine production, TLR-activated alveolar macrophages and innate lymphoid cells in the adaptive response was demonstrated. Furthermore, sensitization to A. alternata seems to be a trigger for the development of co-sensitization to other allergen sources and may act as an exacerbator of symptoms and an elicitor of food allergies. The prevalence of A. alternata allergy is increasing and has led to expanding research on the role of this fungal species in the induction of IgE-mediated respiratory diseases. Indeed, recent research has allowed new perspectives to be considered in the assessment of exposure and diagnosis of fungi-induced allergies, although more studies are needed for the standardization of immunotherapy formulations.

Aspergillus fumigatus—Host Interactions Mediating Airway Wall Remodelling in Asthma

“…In other patient cohorts, Alternaria and Cladosporium appeared to be especially frequent in patients with asthma and fungal sensitisation [5,134]. Detailed mechanistic studies investigating whether these other fungi and the factors they produce, can activate and damage the airway epithelium are limited [135,136]. Furthermore, emerging evidence points to an important role for sensation to a range of fungal allergens in the skin of atopic dermatitis patients, in particular those derived from Alternaria and Malassezia, Aspergillus, Saccharomyces and Cladosporium [135,137].…”

“…Detailed mechanistic studies investigating whether these other fungi and the factors they produce, can activate and damage the airway epithelium are limited [135,136]. Furthermore, emerging evidence points to an important role for sensation to a range of fungal allergens in the skin of atopic dermatitis patients, in particular those derived from Alternaria and Malassezia, Aspergillus, Saccharomyces and Cladosporium [135,137]. Such allergens may contribute to the process of 'atopic march', where sensitisation in the skin during infancy leads to subsequent development of allergic disease at other sites, including the airways.…”

Fungal Allergen and Mold Allergy Diagnosis: Role and Relevance of Alternaria alternata Alt a 1 Protein Family

“…To a lesser degree, they can act as animal pathogens, causing disease in human and animals, developing infections, toxicosis and allergic diseases [ 10 , 12 ]. In the field of human ailments, allergic disease is undoubtedly the most common human pathology caused by Alternaria [ 11 , 13 , 14 , 15 ]. The Global Asthma and Allergy European Network (GA2LEN) is a consortium of leading European research centers specialized in allergic diseases, which include asthma.…”

Alt a 1 Promotes Allergic Asthma In Vivo Through TLR4-Alveolar Macrophages

“…Fungal spores constitute the largest proportion of airborne particles, although the majority of mold sensitization research performed points to a few fungal genera to be relevant in airway diseases ( 2 ). Alternaria alternata is one of the most common aeroallergens sources ( 3 ). It has been long described as an outdoor and indoor mold, and a clear risk factor for asthmatic people when spores reach their highest levels in the air during late summer and/or early autumn period ( 4 , 5 ).…”

“…It has been long described as an outdoor and indoor mold, and a clear risk factor for asthmatic people when spores reach their highest levels in the air during late summer and/or early autumn period ( 4 , 5 ). Thus, mouse models have been widely used to characterize the ability of Alternaria to induce T2 immune responses ( 3 , 6 ).…”