Asian Dust Particles Induce Macrophage Inflammatory Responses via Mitogen-Activated Protein Kinase Activation and Reactive Oxygen Species Production
Figure 4
Asian dust particles-induced reactive oxygen species (ROS) production mediates tumor necrosis factor-α (TNF-α) production in RAW264.7 cells. (a) RAW264.7 cells were incubated in phenol red-free Dulbecco’s modified Eagle’s medium containing 20 μM 2′,7′-dichlorodihydrofluorescein diacetate for 30 min. The cells were then treated for 6 h with 100 μg/mL of one of the Asian dust particles (ADP1 or ADP2) or soil dust samples (SDP1, SDP2, SDP3, and SDP4) or culture medium. ROS production was measured as the fluorescence intensity of dichlorodihydrofluorescein. (b, c) RAW264.7 cells were preincubated for 30 min with (b) 250 μM of butylated hydroxyanisole (BHA), a broad-spectrum ROS scavenger, or (c) 1 or 2 μM of diphenyleneiodonium chloride (DPI), a specific inhibitor of NADPH oxidase. The cells were then treated for 6 h with 100 μg/mL of ADP1 or ADP2 or 1.5 μg/mL of LPS. Dimethyl sulfoxide (0.1%) vehicle was used as control (Cont.). The level of TNF-α in the culture supernatants was assessed by means of an enzyme-linked immunosorbent assay. Results are expressed as mean ± SD; ; ; N.D., not detected.
