Re: Integrated research on the association between climate change and Bjerkandera allergy

The Role of Toll-Like Receptors and Myeloid Differentiation Factor 88 in Bjerkandera adusta-Induced Lung Inflammation

BACKGROUND

Recently, a cluster of patients with an intractable allergic fungal cough who were characterized by sensitization to Bjerkandera adusta was reported. In the present study, the role of Toll-like receptors and myeloid differentiation factor 88 (MyD88) in B. adusta-induced lung inflammation was investigated.

METHODS

Wild-type (WT), TLR2-/-,TLR4-/-, and MyD88-/- BALB/c mice were intratracheally challenged with B. adusta 4 times at 2-week intervals. Lung pathology, bronchoalveolar lavage fluid (BALF) cytological profiles, and inflammatory mediators in BALF were investigated. Bone marrow-derived macrophages (BMDM) from TLR2-/-,TLR4-/-, TLR2/4-/-, TLR7/9-/-,MyD88-/-, and WT C57BL/6J mice were stimulated with B. adusta for 12 h, and inflammatory mediators in the culture medium were measured.

RESULTS

B. adusta caused lung inflammation along with Th2 cytokine [interleukin (IL)-5 and IL-13] and eosinophil-related chemokine [eotaxin and monocyte chemotactic protein (MCP-3)] production, an increase in eosinophils in BALF, and eosinophil infiltration in the airways in WT and TLR4-/- mice. However, Th2 and eosinophil-related responses in TLR2-/- and MyD88-/- mice were low or undetectable. The induction of neutrophils and IL-6, IL-12, IL-17A, and MCP-1 in the BALF of MyD88-/- mice was attenuated compared to that in WT mice. The induction of IL-6, TNF-α, MCP-1, and macrophage inflammatory protein-1α was reduced or undetectable in B. adusta-stimulated BMDM from TLR7/9-/- and MyD88-/- mice compared to WT mice.

CONCLUSIONS

These results suggest that TLR2 and the adapter protein MyD88 may play an important role in the induction of eosinophils by B. adusta. However, TLR7/9-MyD88 might be important in the induction of neutrophils and the relevant inflammatory mediators, especially IL-17A.

Atopic cough and fungal allergy

We have shown that some patients presenting with chronic bronchodilator-resistant non-productive cough have a global atopic tendency and cough hypersensitivity without nonspecific bronchial hyperresponsiveness, abbreviated as atopic cough (AC). The cough can be treated successfully with histamine H1 antagonists and/or glucocorticoids. Eosinophilic tracheobronchitis and cough hypersensitivity are pathological and physiological characteristics of AC. Fungus-associated chronic cough (FACC) is defined as chronic cough associated with basidiomycetous (BM) fungi found in induced sputum, and recognition of FACC has provided the possibility of using antifungal drugs as new treatment strategies. Bjerkandera adusta is a wood decay BM fungus, which has attracted attention because of its potential role in enhancing the severity of cough symptoms in FACC patients by sensitization to this fungus. Before making a diagnosis of "idiopathic cough" in cases of chronic refractory cough, remaining intractable cough-related laryngeal sensations, such as "a sensation of mucus in the throat (SMIT)," which is correlated with fungal colonization, should be evaluated and treated appropriately in each patient. The new findings, i.e., the detection of environmental mushroom spores that should not be present in the human airways in addition to the good clinical response of patients to antifungal drugs, may lead to the development of novel strategies for treatment of chronic cough.

Fungus-associated asthma: overcoming challenges in diagnosis and treatment

With regard to fungal colonization and fungal sensitization, the goals of fungus-associated asthma management are as follows: 1) to survey fungi colonizing the airways of patients repeatedly; 2) to evaluate the tendency of the colonizing fungi to sensitize patients and the influence on clinical manifestations of asthma; 3) to follow disease development to allergic bronchopulmonary mycosis or sinobronchial allergic mycosis; and 4) to determine whether fungal eradication from the airway of patients is beneficial from the viewpoints of future risk factors. Recent developments in molecular biological analyses have facilitated the identification of basidiomycetous fungi that were not previously thought to be of concern in fungal allergy. The total control of fungus-associated asthma will be accomplished by environmental management established from the viewpoint of both the ecology and life cycle of the responsible fungi.