Difficult-to-Treat Asthma Calls for Alternative Therapies and Reduced Exposure to Mold Early in Life

Published January 2017
Journal of Clinical Immunology

Children exposed to mold, fungus and mildew in their homes and communities are more likely to develop asthma than non-exposed children. This can be so severe that their asthma is difficult to treat or develops resistance to standard therapies and anti-inflammatory steroids.

A new study finds that children with high values on the Environmental Relative Moldiness Index (EMRI) scale do not have to be allergic to mold or fungus for severe asthma to develop. Cincinnati asthma specialists are recommending a new protocol for these difficult-to-treat patients, including renewed efforts to reduce childhood exposure to fungus and mold.

“What our study found is that children can have mold or fungal exposure that’s very detrimental to their asthma, even if they’re not sensitive to the mold,” says Gurjit Khurana Hershey, MD, PhD, director of the Division of Asthma Research. “We found that even spores and fragments of mold can cause asthma symptoms.”

Difficult-to-treat asthma accounts for more than 50 percent of asthma healthcare utilization. The new study compared data from the Cincinnati Childhood Allergy and Air Pollution Study (CCAPS), and laboratory tests that measured immune responses in mice exposed to various levels of mold, fungus and b-Glucan, a component of mold cell walls. Researchers looked for high immunologic levels of IL-17-A, a cytokine linked to inflammation, and TH2 and TH17 helper cells, implicated in steroid-resistant responses.

Fungal exposure—even to spores or components of  mold—can promote more severe asthma symptoms and steroid resistance, the study found.

Hershey and her team suggest that subgroups of asthmatic patients with high fungal exposure and mixed TH2/Th17 responses might benefit from anti-IL-17A therapy alone or in combination with steroids.

Fungal exposure is associated with increased serum IL-17A levels and increased asthma severity in children. A. This bar chart shows that the percentage of children in the Cincinnati Childhood Allergy and Air Pollution Study with high IL-17A serum levels is higher in the group with high Environmental Relative Moldiness Index (ERMI) values versus those with low ERMI values. B. This bar chart shows a higher percentage of fungal exposure among children in the Greater Cincinnati Pediatric Repository (GCPCR) children who exhibit symptoms more than once a week (n = 258) versus those showing symptoms less than once a week (n = 81). C. This proposed working model describes how the responses occur.

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Citation

Zhang Z, Biagini Myers JM, Brandt EB, Ryan PH, Lindsey M, Mintz-Cole RA, Reponen T, Vesper SJ, Forde F, Ruff B, Bass SA, LeMasters GK, Bernstein DI, Lockey J, Budelsky AL, Khurana Hershey GK. β-Glucan exacerbates allergic asthma independent of fungal sensitization and promotes steroid-resistant TH2/TH17 responses. J Allergy Clin Immunol. 2017 Jan;139(1):54-65 e58.