Vitamin D3 regulates PM-driven primary human neutrophil inflammatory responses

Area of Science:

• Immunology
• Environmental Health
• Toxicology

Background:

• Particulate matter (PM) air pollution is linked to respiratory infections and sepsis mortality.
• PM exposure may adversely affect neutrophil function, a key component of innate immunity.
• Strategies to mitigate PM's impact on immune cells are urgently needed.

Purpose of the Study:

• To investigate the effects of urban PM and PM2.5 on human neutrophil functions.
• To assess the role of vitamin D in modulating PM-induced neutrophil dysfunction.
• To explore vitamin D supplementation as a potential mitigation strategy.

Main Methods:

• Human peripheral blood neutrophils were exposed to standard urban PM (SRM1648a, NIST) and PM2.5 from Thailand.
• Neutrophil functions assessed included IL-8 production, CXCR2 expression, migration, and bacterial killing.
• Effects were evaluated in both sufficient and insufficient vitamin D states, with in vitro vitamin D3 supplementation.

Main Results:

• Both PM types increased IL-8 production but reduced CXCR2 expression and LPS-induced migration.
• PM-exposed neutrophils from vitamin D-insufficient individuals showed impaired E. coli killing.
• In vitro vitamin D3 supplementation improved bacterial killing and reduced IL-8 production in these cells.

Conclusions:

• Ambient PM exposure negatively impacts human neutrophil function, including migration and bacterial clearance.
• Vitamin D insufficiency exacerbates PM-induced neutrophil dysfunction.
• Vitamin D supplementation shows promise in attenuating adverse neutrophilic responses to PM.