Fig. 7

Copper drives the observed effects of NAO brake-wear PM. ATII cells were exposed to 6 concentrations of NAO BWPM (0.5, 1, 2, 4, 8, and 16 µg/cm²) for 24 h, after which the supernatant was harvested and the cells were washed 3 times before lysis with Chelex-100 treated MilliQ H2O. The lysates were then analysed for their elemental composition using ICP-MS, to determine the concentrations of the metals in cells after NAO BWPM exposure. A Intracellular copper concentration following NAO BWPM exposure. n = 3. Following this, ATII cells were exposed to either metal chelators alone (TEPA 50 µM, DFX 12.5 µM, or TPEN 1 µM), NAO BWPM (8 µg/cm²) alone, or the NAO BWPM and metal chelators together (NAO + TEPA, NAO + DFX, or NAO + TPEN) for 24 h. Following this, HMOX1 gene expression (B), MT1G gene expression (C), and IL-6 protein secretion (D) were examined. n = 4. In all cases, bars represent mean + SEM, and a RM one-way ANOVA test was used with a Dunnett’s post-hoc test to test for significance. * = p ≤ 0.05. ** = p ≤ 0.01, *** = p ≤ 0.001. **** = p ≤ 0.0001