Fig. 3

Menthol-flavored JUUL aerosol plus HDM exposures disrupt pulmonary iron metabolism homeostasis and MMP12 deficiency attenuates this effect. Sub-chronic (60 days) exposures to JUUL menthol-flavored aerosol plus HDM. a–d significantly increased the lung protein concentration of ferroportin and lactoferrin in WT mice compared to air controls, while no changes were seen in MMP12 KO mice; e–h significantly decreased the lung protein concentrations of ferritin and transferrin in WT mice compared to air controls, while no changes were seen in MMP12 KO mice. Data represent the mean ± SEM for n = 3–4 animals per group. One-way ANOVA followed by the Tukey’s test post-hoc test. *p < 0.05 and **p < 0.01 statistically different from Air control. i 20 × magnification images of Perl’s Prussian blue (PPB)-stained lung tissues from WT and MMP12 KO mice from which BALF were previously collected. Arrows indicate blue-stained iron-laden macrophages from the lungs. Scale bar = 10 µm