Allergic fungal airway disease

Abstract

Fungi are ubiquitous and form their own kingdom. Up to 80 genera of fungi have been linked to type I allergic disease, and yet, commercial reagents to test for sensitization are available for relatively few species. In terms of asthma, it is important to distinguish between species unable to grow at body temperature and those that can (thermotolerant) and thereby have the potential to colonize the respiratory tract. The former, which include the commonly studied Alternaria and Cladosporium genera, can act as aeroallergens whose clinical effects are predictably related to exposure levels. In contrast, thermotolerant species, which include fungi from the Candida, Aspergillus, and Penicillium genera, can cause a persistent allergenic stimulus independent of their airborne concentrations. Moreover, their ability to germinate in the airways provides a more diverse allergenic stimulus, and may result in noninvasive infection, which enhances inflammation. The close association between IgE sensitization to thermotolerant filamentous fungi and fixed airflow obstruction, bronchiectasis, and lung fibrosis suggests a much more tissue-damaging process than that seen with aeroallergens. This review provides an overview of fungal allergens and the patterns of clinical disease associated with exposure. It clarifies the various terminologies associated with fungal allergy in asthma and makes the case for a new term (allergic fungal airway disease) to include all people with asthma at risk of developing lung damage as a result of their fungal allergy. Lastly, it discusses the management of fungirelated asthma. Key words: Thermotolerant fungi. Allergic fungal airway disease (AFAD). ABPA. SAFS. Asthma. Allergic fungal rhinosinusitis (AFRS). Immune responses. Diagnosis. Treatment. ResumenLos hongos son obicuos y forman su propio reino. Hasta 80 géneros de hongos han sido asociados con la enfermedad alérgica tipo I; sin embargo, los reactivos comerciales para testar las sensibilizaciones a los mismos, se encuentran disponibles para un número relativamente pequeño de especies. En cuanto al asma, es importante distinguir entre especies incapaces de crecer en temperatura ambiente y aquellas que son termotolerantes y que, por lo tanto, tienen una capacidad potencial para colonizar el tracto respiratorio. Los primeros, que incluyen los géneros comúnmente estudiados Alternaria y Cladosporium, pueden actuar como aeroalérgenos y sus efectos clínicos están relacionados con los niveles de exposición. En contraste, las especies termotolerantes, que incluyen hongos del género Candida, Aspergillus y Penicillium, pueden causar un estímulo alergénico persistente independiente de su concentración en el aire. Además, su capacidad para germinar en las vías aéreas da lugar a estímulos alergénicos más diversos y puede dar como resultado infecciones no invasivas que facilitan la inflamación. La estrecha asociación entre sensibilización dependiente de IgE a hongos filamentosos termotolerantes y la obstrucción del flujo aéreo, bronquiectasias y fib...

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