and IL-6 responses to particulate matter in vitro: variation according to PM size, season, and polycyclic aromatic hydrocarbon and soil content

• Published in: Environmental health perspectives 2016-04, p.406
• Main Authors: Manzano-Leon, Natalia, Serrano-Lomelin, Jesus, Sanchez, Brisa N, Quintana-Belmares, Raul, Vega, Elizabeth, Vazquez- Lopez, Ines, Rojas-Bracho, Leonora, Lopez-Villegas, Maria Tania, Vadillo-Ortega, Felipe, De Vizcaya-Ruiz, Andrea, Perez, Irma Rosas, O'Neill, Marie S, Osornio-Vargas, Alvaro R
• Format: Article
• Language: English
• Subjects: Air pollution; Analysis; Health aspects; Interleukins; Polycyclic aromatic hydrocarbons; Tumor necrosis factor
• ISSN: 0091-6765; 1552-9924
• DOI: 10.1289/ehp.1409287

BACKGROUND: Observed seasonal differences in particulate matter (PM) associations with human health may be due to their composition and to toxicity-related seasonal interactions. OBJECTIVES: We assessed seasonality in PM composition and in vitro PM pro-inflammatory potential using multiple PM samples. METHODS: We collected 90 weekly [PM.sub.10] and [PM.sub.2.5] samples during the rainy-warm and dry-cold seasons in five urban areas with different pollution sources. The elements, polycyclic aromatic hydrocarbons (PAHs), and endotoxins identified in the samples were subjected to principal component analysis (PCA). We tested the potential of the PM to induce tumor necrosis factor alpha (TNFα) and interleukin 6 (IL-6) secretion in cultured human monocytes (THP-1), and we modeled pro-inflammatory responses using the component scores. RESULTS: PM composition varied by size and by season. PCA identified two main components that varied by season. Combustion-related constituents (e.g., vanadium, [benzo[a]pyrene, [benzo[a] anthracene) mainly comprised component 1 ([C.sub.1]). Soil-related constituents (e.g., endotoxins, silicon, aluminum) mainly comprised component 2 ([C.sub.2]). PM from the rainy-warm season was high in [C.sub.2]. PM (particularly [PM.sub.2.5]) from the dry-cold season was rich in [C.sub.1]. Elevated levels of cytokine production were associated with [PM.sub.10] and [C.sub.2] (rainy-warm season), whereas reduced levels of cytokine production were associated with [PM.sub.2.5] and [C.sub.1] (dry-cold season). TNFα secretion was increased following exposure to PM with high (vs. low) [C.sub.2] content, but TNFα secretion in response to PM was decreased following exposure to samples containing ≥ 0.1% of [C.sub.1]-related PAHs, regardless of [C.sub.2] content. The results of the IL-6 assays suggested more complex interactions between PM components and particle size. CONCLUSIONS: Variations in PM soil and PAH content underlie seasonal and PM size-related patterns in TNFα secretion. These results suggest that the mixture of components in PM explains some seasonal differences in associations between health outcomes and PM in epidemiologic studies.