Heliyon (Sep 2024)

Pseudomonas aeruginosa exotoxin A as a novel allergen induced Non-TH2 inflammation in a murine model of steroid-insensitive asthma

  • Huancheng Xie,
  • Linmei Li,
  • Yuhe Guo,
  • Linghui Zhou,
  • Linyi Ma,
  • Andong He,
  • He Lai,
  • Ying He,
  • Yongping Liu,
  • Huifang Chen,
  • Liping Luo,
  • Yuyi Huang,
  • Xiangyin Sha,
  • Huanping Zhang,
  • Jie Yan,
  • Qingling Zhang,
  • Ailin Tao

Journal volume & issue
Vol. 10, no. 18
p. e37512

Abstract

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Background: Despite the immediate in vivo occurrence of anaphylactic and allergic reactions following treatment with Pseudomonas aeruginosa exotoxin A (PEA)-based immunotoxins, the immunological role of PEA in asthma pathogenesis remains unclear. Objective: This study investigated the allergenic potential of PEA and the specific type of asthma induced. Methods: Recombinant PEA (rPEA) lacking domain Ia (to eliminate non-specific cytotoxicity) was expressed, purified, and employed to detect serum PEA-specific IgE levels in asthmatic patients. Competitive ELISA assays were used to assess rPEA's IgE binding capacity and allergenicity. Additionally, rPEA-challenged C57BL/6 mice were subjected to inflammatory endotyping and therapeutic assays to characterize the allergic nature of PEA. Results: PEA-specific IgE was identified in 17 (14.2 %) of 120 asthma patients. The rPEA-sensitized and challenged mice had increased PEA-specific immunoglobulins (such as IgE, IgG1 and IgG2a) and developed asthma-like phenotypes with airway hyperresponsiveness, severe airway inflammation, and airway remodeling. Lungs from these mice displayed significant increases in neutrophils and IL-17A+ cells. Innate lymphoid cells (ILCs) produced type 2 cytokines (IL-4, IL-5, and IL-13), whereas Th cells did not. Nonetheless, airway inflammation, rather than hyperresponsiveness, was elicited in non-sensitized mice upon challenge with rPEA. Importantly, rPEA-induced asthmatic mice were unresponsive to dexamethasone treatment. Conclusion: PEA is a novel allergen that sensitizes asthmatic patients. Furthermore, mice developed steroid-resistant asthma, characterized by an atypical cytokine profile associated with non-TH2 inflammation, only after being sensitized and challenged with rPEA. These findings suggest a potentially significant role for PEA in asthma development, warranting consideration in clinical diagnosis and treatment strategies.

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