Two cases of Schizophyllum asthma: Is this a new clinical entity or a precursor of ABPM?
Introduction
There has been increasing interest in the relationship between severe asthma and fungal sensitization [1], [2], [3]. Therefore, testing in adults with asthma that does not respond to first-line treatments should include not only such routine investigations as lung function, sinus CT scanning, sensitization to common inhalant allergens or evaluation of evidence for allergic bronchopulmonary aspergillosis (ABPA) [4], but should also include an evaluation for evidence of colonization with a range of fungi, including Alternaria, Candida, and Trichophyton, as well as Aspergillus species [5].
Recent research has focused on the possible role of basidiomycetous (BM) fungi as a fungal aeroallergen [6], and allergic fungal respiratory diseases [7] caused by BM fungi have been increasingly reported [8], [9], [10]. Although it is well-known that Schizophyllum commune (S. commune), one of the BM fungi, causes mucoid impaction of bronchi (MIB) [11], allergic bronchopulmonary mycosis (ABPM) [12] and allergic fungal sinusitis (AFS) [13], however, it remains unclear whether this fungus really causes or triggers asthma symptoms similar to Aspergillus species [14].
This report describes two patients with bronchial asthma caused by S. commune; so-called Schizophyllum asthma. Except for the criteria of pulmonary involvement, such as central bronchiectasis and mucoid impaction, both cases met the criteria for ABPM caused by S. commune. Therefore, it was difficult to distinguish Schizophyllum asthma from eosinophilic bronchitis involved in ABPM caused by S. commune.
This raises the question of whether the proposed Schizophyllum asthma is actually a new clinical entity similar to both Trichophyton asthma [15], [16] and Candida asthma [17], or is instead a precursor of ABPM caused by S. commune.
Section snippets
Preparation of the antigenic solution of S. commune
One liter of Sabouraud’s dextrose broth in 3 L flasks was sterilized. Five milliliters of a S. commune spore suspension (105 spores per ml) in sterile physiological saline from 14 day-old Sabouraud’s dextrose agar culture were used to inoculate a flask. The flask was shaken at 25 °C at 150 rpm in a rotary shaker incubator for 14 days. Mycelia were separated by filtration, and centrifuged. The supernatants were dialyzed against 5 mM ammonium bicarbonate and lyophilized.
Intradermal skin test and serological test
The antigenic solution
Discussion
It is important to elucidate the etiological agents and the exacerbating factors involved in allergic fungal respiratory diseases (AFRD) [7]. In particular, there has been increasing interest in the association between severe asthma and fungal sensitization [1], [2], [3]. Recently, it was stated in the Global Initiative for Asthma (GINA) 2009 that describing patients as having allergic asthma is usually of little benefit, unless a single specific trigger can be identified [21]. However, in
Conflict of interest
All authors declare that they have no competing interests that might be perceived to influence the results and discussion reported in the present manuscript.
Acknowledgments
The authors wish to thank Dr. Masakatsu Seo (Seo Laboratory) for extending his help in the macroscopic identification of the fungal species, and Dr. Kazuo Akiyama (Clinical Research Center for Allergy and Rheumatology, National Hospital Organization, Sagamihara National Hospital) for preparing the antigenic solution. This study was supported in part by a grant-in-aid for Scientific Research from the Ministry of Education, Culture, Sports Science and Technology - Japan (No. 17607003).
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