Recent studies have demonstrated that variation between particulate matter compositions have universally adverse effects on cells and living tissues. Carbon black and titanium dioxide are two such particulates that we are continuously exposed to, yet there is limited research to examine the potential deleterious effects on living tissue. The objective of this study is to characterize the effect of carbon black (CB) and titanium dioxide (TiO2) particulates on A549 human alveolar epithelial lung cells. CB and TiO2 powders were dispersed throughout a solution of water and bovine serum albumin by high-powered sonication. The effects of these particulates on A549 cells were analyzed through fluorescent microscope imaging, DAPI nuclear fluorescent staining, western blotting, H2DCFDA fluorescent staining. Death assays with DAPI revealed that both particulate types exhibit toxicity to cells and induce apoptosis. Live cell imaging showed perinuclear localization of both CB and TiO2 particulates. The human A549 cells were tested for reactive oxygen species (ROS) levels, which revealed a significant increase in ROS production induced by CB, but lowered ROS induction by TiO2. Interplay between ROS and intracellular calcium was examined; 2-APB, a calcium blocker was added to cells treated with CB. Results indicated that 50uM 2-APB provided notable protection to cells by decreasing ROS induction levels. Further research is required to determine through which apoptotic signaling pathway CB causes cell death and to definitively identify the signaling pathways involved in TiO2 associated toxicity. Further investigation of the explicit involvement of the ER in particulate induced apoptosis is a promising direction for future research.
Alvarado, Sarah; Manes, Brianna; and Brewster, Jay L., "Carbon Black and Titanium Dioxide Nanoparticles Differentially Activate Oxidative Stress and Apoptosis in A549 Human Alveolar Epithelial Cells" (2013). Pepperdine University, Featured Research. Paper 64.