PM2.5 Causes Increased Bacterial Invasion by Affecting HBD1 Expression in the Lung

Area of Science:

• Environmental Health
• Immunology
• Microbiology

Background:

• Fine particulate matter (PM2.5) is a significant environmental pollutant linked to increased infection risks.
• Human beta-defensin 1 (HBD1) is a crucial peptide for mucosal immunity in the airway epithelium.

Purpose of the Study:

• To investigate the impact of PM2.5 exposure on HBD1 expression and its role in Pseudomonas aeruginosa infection.
• To elucidate the molecular pathways involved in PM2.5-induced susceptibility to infection.

Main Methods:

• Utilized C57BL/6J mice and human bronchial epithelial (HBE) cells.
• Assessed HBD1 expression (mRNA and protein) following PM2.5 exposure and P. aeruginosa infection.
• Examined the effects of exogenous HBD1 administration and pathway inhibitors (MAPK, NF-κB).

Main Results:

• PM2.5 exposure decreased HBD1 expression and increased P. aeruginosa invasion in HBE cells and mice.
• Combined PM2.5 and P. aeruginosa exposure reduced mouse survival rates.
• Exogenous HBD1 administration and pathway inhibition ameliorated PM2.5-induced detrimental effects.

Conclusions:

• PM2.5 exposure exacerbates P. aeruginosa infections by suppressing HBD1 expression via MAPK and NF-κB pathways.
• Exogenous HBD1 offers a potential therapeutic strategy against PM2.5-associated lung infections.
• Findings provide insights into the pathogenesis of PM2.5-related respiratory infections.