Innate type 2 response to Alternaria extract enhances ryegrass-induced lung inflammation

Area of Science:

• Immunology
• Allergy Research
• Respiratory Medicine

Background:

• Alternaria alternata and ryegrass pollen are linked to severe asthma during thunderstorms.
• Previous studies showed Alternaria extract induces innate type 2 lung inflammation in mice.
• This study investigated if Alternaria enhances ryegrass-induced lung inflammation.

Purpose of the Study:

• To determine if Alternaria extract exposure enhances ryegrass-induced lung inflammation.
• To examine the impact of Alternaria on eosinophilic responses and airway inflammation.
• To explore the role of innate lymphoid cells type 2 (ILC2) and Th2 cells.

Main Methods:

• Mice were sensitized to ryegrass allergen and challenged with Alternaria extract.
• Evaluated eosinophils, neutrophils, Th2 cells, ILC2, IL-5, and IL-13 in bronchoalveolar lavage (BAL).
• Assessed airway inflammation and mucus production.

Main Results:

• Ryegrass sensitization and challenge induced an eosinophilic lung response.
• Alternaria extract exposure, before or after ryegrass challenges, increased eosinophils, inflammation, and mucus.
• Alternaria extract increased type 2 ILC2 and Th2 cell recruitment and proliferation.

Conclusions:

• Alternaria extract exposure enhances type 2 lung inflammation in ryegrass-sensitized mice.
• This enhancement involves Th2 cell recruitment and ILC2 expansion.
• Combined exposure to grass pollen and Alternaria may contribute to thunderstorm-asthma in humans.