Extended Data Fig. 10: Toxicity studies showing that bismuth drugs are not cytotoxic.
a, b, Bismuth drugs show no toxicity in cells. The cell viability was measured by XTT assay under the treatment of different concentrations of bismuth drugs for 48 hours. The bismuth drugs showed negligible toxicity to human lung epithelial cells and embryonic kidney cells even at very high concentrations. c, Bismuth drugs show negligible hemolytic activity. Percent of hemolysis was calculated concerning the positive control (Triton X-100). (a–c) All the tests were performed in triplicate and all the data are presented as mean ± SD. d, Hematoxylin and eosin (H&E) staining of the mice lungs under treatment of single dose (-1d) or three doses (-3d) of 100 mg/kg CBS. e, Survival curves of mice treated with PBS, 100 mg/kg, and 200 mg/kg of CBS (n = 4) by the intranasal administration. f, The biodistribution of bismuth in mice after treatment by the intranasal administration of 100 mg/kg CBS. g, Proposed the mechanism of action for the synergy of bismuth with antibiotics. Bismuth restores the susceptibility of P. aeruginosa to antibiotics through iron deprivation by interacting with siderophores and Fur. Consequently, the activity of iron-dependent cellular respiration complexes (for example, NADH dehydrogenase) is inhibited, resulting in dissipating the proton motive force (PMF), which further leads to repressed ATP synthesis and impaired multi-drug efflux pump. Ultimately, more antibiotics are rapidly accumulated inside bacterial cells, resulting in the death of cells. For Fig. a–c error bars represent mean ± SEM for three biological replicates. For Fig. d, four mice were included in each group, and similar results were obtained. For Fig. f error bars represent mean ± SEM for four mice samples.
