Innate Immune Cell and Epithelial Subsets Coordinate Airway Responses to Allergen.

Area of Science:

• Immunology
• Respiratory Medicine
• Molecular Biology

Background:

• Mechanisms of allergic asthma are not fully understood.
• The role of crosstalk between innate immune cells and airway epithelium in response to inhaled allergens is critical.
• Investigating these interactions is key to understanding asthma pathogenesis.

Purpose of the Study:

• To identify transcriptional responses to allergen exposure in human airway samples.
• To analyze these responses in ex vivo airway epithelial cell (AEC) models.
• To elucidate the cellular and molecular players in allergic airway inflammation.

Main Methods:

• RNA-sequencing (RNA-seq) of induced sputum and epithelial brushings after allergen challenge.
• Single-cell RNA-seq (scRNA-seq) to analyze cell populations and gene expression.
• Ex vivo RNA-seq of primary AECs exposed to allergens in different cytokine environments (IL-13 or IFN-γ).

Main Results:

• Distinct inflammatory patterns observed, including mast cell (MC) and AEC gene activation.
• MCs increase post-allergen challenge and express IL5 and IL18.
• Basophils, initially absent, increase and express IL4 and IL13; epithelial CCL26 mediates basophil chemotaxis.
• AEC response involves glycolysis and cadherin binding, modulated by IL-13 or IFN-γ.

Conclusions:

• Allergen challenge induces diverse pro-inflammatory transcriptional responses in airways.
• MCs, basophils, and AECs play distinct, crucial roles in coordinating the allergic response.
• Airway responses to allergens can vary significantly based on the individual's baseline inflammatory endotype.