What may be the function of eosinophil DNA traps in allergic bronchopulmonary aspergillosis?

Published online: September 21, 2017

The incidence of fungal diseases has risen promptly over the last years, and allergic bronchopulmonary aspergillosis (ABPA) is the most significant and prevalent manifestation of allergic aspergillosis that occurs worldwide. ABPA is a lung injury characterized by an intense pulmonary infiltration of eosinophils that develops in response to repeated airways exposures and lung colonization by fungus of the genus Aspergillus, specifically Aspergillus fumigatus (A. fumigatus) (distributed widely in the environment). If undiagnosed or not treated, ABPA may result in progressive lung damage, pulmonary fibrosis, and death. Eosinophils have been described to have clearance roles for A. fumigatus, but the interactions between Aspergillus and eosinophils have been poorly understood.
In an article recently published in The Journal of Allergy & Clinical Immunology (JACI), Muniz and colleagues hypothesized that eosinophils might respond to A. fumigatus by releasing extracellular DNA traps. The release of extracellular DNA traps by leukocytes has being considered as an important mechanism of the immune system in different infectious diseases.

The authors characterized the presence of extracellular DNA traps in bronchial mucus samples of ABPA patients. They found that human blood eosinophils release DNA extracellular traps (EETs) in response to A. fumigatus in a process that did not promote the damage or killing of the fungus. The authors suggest that excessive release of EETs by eosinophils may contribute to the formation of sticky and viscous mucus, which may trigger breathing difficulty and airway obstruction, as well as contribute to the deleterious pulmonary inflammatory process typical of ABPA. Since EETs lack the killing activity against A. fumigatus, this might explain the persistent fungal colonization observed in ABPA individuals.

In this context, the authors’ findings may be important to improve knowledge regarding ABPA pathogenesis. Moreover targeting these regulatory pathways involved in the A. fumigatus-induced EETs release may represent an exciting alternative approach to the treatment of ABPA patients.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

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