Airborne environmental fine particles induce intense inflammatory response regardless of the absence of heavy metal elements.

This study intends to address this gap and provides a detailed characterization and immunotoxicity evaluation of PM collected in an urban area with heavy traffic congestion. Environmental particles were separated by different sizes though a sucrose gradient. This method allowed to achieve 4 sized fractions: EP f 15 % with a mean diameter of 284 nm ± 1.86 nm, EP f 25 % with a mean diameter of 461 nm ± 1.72 nm, EP f 35 % with a mean diameter of 1845 nm ± 251 nm and EP f 45 % with a mean diameter of 2204 nm ± 310 nm. Only the fractions with the smallest sizes (EP f 15 % and EP f 25 %) were subsequently studied. The chemical composition of both fractions was not substantially different, and the dominant elements were C, O, Ca and K. Only EP f 25 % showed to have a small amount of Fe. Therefore, the heavy metal elements were eliminated through centrifugation. Essentially, we found that the EP f 15 % was more cytotoxic in RAW 264.7 cells than EP f 25 %, which indicates the smaller size as the motive for the higher toxicity. In addition, both fractions of EP presented a good internalization in macrophages after 2 h exposure and induced the production of reactive oxygen species in a concentration-dependent manner. Moreover, EP f 15 % and EP f 25 % led to a strong secretion of proinflammatory cytokines (TNF-α and IL-6) in human peripheral blood mononuclear cells (hPBMCs) in the 3 concentrations tested. The inflammatory response observed was independent of the pr...

Source: Ecotoxicology and Environmental Safety - March 25, 2020 Category: Environmental Health Authors: Colaço M, Duarte A, Zuzarte M, Costa BFO, Borges O Tags: Ecotoxicol Environ Saf Source Type: research