Figure 4

Magnéli phases concentrate in pulmonary macrophages following a single exposure and are retained in the lung. (A) Following a single airway exposure to 100 ppm, titanium associated with the Magnéli phases were retained in the lungs and detected using ICP-MS for over 7 days post-expsure. Control tissues were collected from animals exposed to 100 ppm Ti₆O₁₁ and immediately euthanized. (B–D) Representative H&E stained tissue sections used for histopathology evaluation. (B) Vehicle control showing no nanoparticles or pathology. (C) Significant airway inflammation was observed in LPS treated animals, but no evidence of inflammation was found in the mice treated with Magnéli phases at any timepoint evaluated. (D) Larges areas of macrophages containing Magnéli phases were found in all treated animals (yellow box). (E–G) The majority of pulmonary macrophages contain Magnéli phases, with no other cell types appearing to contain or associate with the nanoparticles determined using dark field microscopy. Darkfield images were taken of (E) Ti₆O₁₁ nanoparticles alone or the lungs of mice 7 days post-exposure to either (F) PBS or (G) 100 ppm Magnéli phases. (G) Particles in the tissues were identified by bright punctate dots, almost exclusively localized in macrophages. Representative H&E stained lung sections (Scale bar = 50 μm). All data are expressed as mean ± SEM (n = 7/group). **p < 0.01.