Unraveling Potential\nCausative Components for the\nDeleterious Effect of Atmospheric Fine Particulate Matter on Red Blood\nCells

Atmospheric fine particulate matter (PM<sub>2.5</sub>) poses threats\nto the cardiovascular system. Red blood cells (RBCs) are the most\nabundant cells in blood, which are actively involved in multiple hematological\ndiseases, such as blood clot formation and thrombosis. Exploring how\nPM<sub>2.5</sub> with spatiotemporal heterogeneity influences the\nhematological system by targeting RBCs would help gain insights into\nthe deleterious effects of PM<sub>2.5</sub> and provide clues for\nfinding the causative components therein. Herein, the PM<sub>2.5</sub> samples collected from 3 urban sites in Beijing (i.e., Chaoyang,\nShunyi, and Yanqing districts) during 4 seasons of 2022 were studied\nfor their toxicities to mouse RBCs, and the main contributing components\nwere further explored through chemical analysis and correlation measure.\nThe results showed that exposure to PM<sub>2.5</sub> samples decreased\nadenosine triphosphate (ATP) levels and increased phosphatidylserine\n(PS) externalization of RBCs, causing cell morphological deformity.\nThe Pearson correlation analysis showed that the aromaticity of the\ndissolved organic matter (DOM) in PM<sub>2.5</sub> samples was positively\ncorrelated with PS exposure of RBCs, showing that the lignin-like\ncompounds were the potential contributors. The negative correlation\nof zeta potentials of PM<sub>2.5</sub> samples with PS exposure of\nRBCs showed the particle-derived bioactivities of this airborne pollutant.\nThe simulative test based on artificial nanomaterials of carbon black\n(CB) and oxidized CB (OCB) confirmed the crucial role of particulate\ncarbon in PM<sub>2.5</sub>-induced effects on RBCs, and soot with\na certain oxidation degree was, thus, recognized as another contributor,\ngiven its ubiquitous existence in PM<sub>2.5</sub> samples. This study,\nfor the first time, revealed PM<sub>2.5</sub>-induced PS exposure\nof RBCs, and the causative components of DOM and soot were unraveled.\nConsidering the inevitable contact of airborne PM<sub>2.5</sub> with\nRBCs in the blood circulatory system, the findings obtained herein\nwould help bridge the gap between PM<sub>2.5</sub> exposure and the\nrisk of cardiovascular diseases, like thrombogenesis.