TLR5 Activation Exacerbates Airway Inflammation in Asthma

Area of Science:

• Immunology
• Environmental Health
• Genetics

Background:

• Innate immune activation by pollutants impacts asthma severity.
• Household lipopolysaccharide (LPS) is linked to increased asthma severity.

Purpose of the Study:

• To investigate if flagellin, a bacterial ligand, exacerbates airway inflammation and asthma via TLR5 activation.
• To assess flagellin in house dust and its association with asthma.

Main Methods:

• Utilized a murine model of allergic asthma with flagellin and ovalbumin co-exposure.
• Evaluated flagellin presence in asthma patient house dust.
• Analyzed TLR5 polymorphism (rs5744168) association with asthma symptoms.

Main Results:

• Bacterial flagellin was detected in house dust of asthma patients.
• Flagellin exposure exacerbated allergic airway inflammation in a mouse asthma model.
• A dominant-negative TLR5 polymorphism correlated with decreased asthma symptoms.

Conclusions:

• Microbial flagellin acts as an environmental pollutant exacerbating asthma.
• TLR5 deficiency represents a novel genetic protective factor against asthma severity.
• Identified flagellin and TLR5 variants as key factors influencing asthma severity.