Abstract:
Airway exposure to environmental allergens activates cellular stress pathways resulting in the release of danger signals known as alarmins. Allergens associated with the saprophytic fungus, Alternaria alternata exacerbate airway inflammation in sensitized asthma patients. Exposure of the airway epithelium to Alternaria induces oxidative stress, leading to the secretion of ATP, a primary alarmin that stimulates Ca²⁺ uptake, producing sustained increases in intracellular [Ca²⁺]. In the present study, we examined the mechanisms responsible for allergen-evoked DNA fragmentation and release from human airway epithelial cells and determined the role of extracellular DNA (eDNA) in type 2 immunity. Human bronchial epithelial (hBE) cells were used to investigate allergen-evoked DNA mobilization and release using comet assays to measure DNA fragmentation, double-stranded DNA assays to measure the kinetics of eDNA release, and DNA sequencing to determine eDNA composition. The role of eDNA in type 2 immunity was investigated in mice following intranasal exposure to Alternaria.

Alternaria extract rapidly stimulated mitochondrial and nuclear DNA release from hBE cells, whereas mitochondrial DNA, but not nuclear DNA release, was induced by house dust mite extract. Alternaria-induced increases in intracellular [Ca²⁺] activated the pro-protein convertase enzyme furin, which in turn produced non-canonical activation of caspase-3, ultimately leading to nuclear DNA fragmentation as shown in comet assays. eDNA displayed disproportionally higher amounts of promotor and exon sequences and lower intron and intergenic regions compared to predictions of random DNA fragmentation, indicating that the eDNA release was not a consequence of epithelial cell ETosis. In mice, pretreatment with polyamidoamine dendrimers, which function as DNA scavengers, blocked Alternaria-evoked type 2 immune responses. Furthermore, in caspase-3-deficient mice, Alternaria-stimulated eDNA release was inhibited. Lastly, co-administration of mouse genomic DNA along with Alternaria extract amplified IL-5 and IL-13 secretion into bronchoalveolar lavage fluid, whereas DNA alone produced no response. In conclusion, these results describe a previously unknown, allergen-stimulated mechanism of rapid genomic DNA release that augments type 2 immunity in airways.

Keywords: Alternaria; house dust mite; alarmins; extracellular DNA; Asthma; allergic inflammation.

Biography:
Scott M. O’Grady, currently affiliated with the University of Minnesota, Minneapolis/St. Paul, MN, is a distinguished researcher in the fields of Cell Physiology & Biophysics. Dr. O’Grady’s educational journey includes a Ph.D. in Physiology from the Department of Physiology and Biophysics at the University of Illinois, Urbana-Champaign. He received further training in epithelial ion transport during his Postdoctoral Fellowship at the University of Chicago, and as a Research Associate in the Department of Medicine at Columbia University, New York, NY. Dr. O’Grady’s research interests primarily revolve around understanding the intricate mechanisms and regulation of electrolyte transport across epithelial tissues, focusing primarily on airways. His laboratory also investigates innate immune function of the airway epithelium in relation to cystic fibrosis, asthma, and allergic airway disease. Collaborating with Dr. Hirohito Kita from the Mayo Clinic, they explore the role of the airway epithelium in allergic inflammation induced by environmental allergens and fungal lung infections. Dr. O’Grady’s dedication to advancing scientific knowledge is evident through his numerous honors and awards, including recognition in prestigious journals such as the Journal of Allergy and Clinical Immunology, Journal of Physiology and the American Journal of Physiology [Cell Physiology]. Additionally, he has contributed significantly to editorial service, serving on the editorial boards of the International Journal of Molecular Sciences, American Journal of Physiology [Cell Physiology], and International Archives of Clinical Pharmacology. His commitment to excellence extends beyond research, as evidenced by his teaching excellence award from the College of Veterinary Medicine at the University of Minnesota.

Tatiani MAIOLI is a Assistant Professor at Federal University of Minas Gerais, Belo Horizonte in Brazil. Tatiani Uceli Maioli is an academic researcher. The author has contributed to research on topics: FGF21 and natural killer T cell. The author has an index of 1, and co-authored 1 publication receiving 271 citations.