Correlations between human alveolar macrophage particulate matter load, air pollution particulate matter levels, and systemic inflammation markers in Mexico City

This study explores potential associations among ambient particulate matter (PM) exposure, PM load in alveolar macrophage (AM), and biomarkers collected from 53 healthy, adult, nonsmoking residents of the Iztapalapa and Iztacalco municipalities in Mexico City. Ambient PM_2.5 concentrations were estimated using an improved Land Use Regression (LUR) model to approximate PM exposure levels. The PM/carbon loading was quantified by the fraction of AM containing PM (%, %AMPM) and the PM area within the AM (µm²) from BAC cytospin microphotography using CellProfiler cell image analysis software. Concentrations of biomarkers were analyzed in bronchoalveolar lavage fluid (BALF), plasma, and urine. Most AM samples contained PM (median = 62.4%, interquartile range [IQR] = 50.0-73.0%). The median PM area in AM was 1.082 µm² (IQR = 0.607-1.855 µm²). Participant with low %AMPM (< 33 percentile) showed 8% increase in %AMPM per 10 µg/m³ increments of six-month averaged, LUR-estimated PM_2.5 concentrations. The %AMPM had a statistically significant, positive association with plasma von Willebrand Factor (vWF) (p = 0.016) and serum lactase dehydrogenase (LDH) (p = 0.026). These findings suggest that ambient urban PM exposure in Mexico City contributes to PM accumulation in AMs and may trigger systemic inflammation and oxidative stress in healthy young residents.