Figure 4.

Effects of acute flavored e-cigarette exposure on matrix metalloprotease protein levels in lung homogenate. Mice were exposed to air, PG/VG, and e-liquid flavors “Apple”, “Cherry”, “Strawberry”, “Wintergreen”, and “Smooth & Mild Tobacco” for 3 days for 1 h per day. Mice were sacrificed twenty-four hours after the final exposure. Protein levels for matrix metalloproteinases were measured in lung homogenate using Western blot. (A) MMP2 and MMP9 protein abundance in mouse lung homogenate from male and female exposed mice. (B) Band intensity was measured using densitometry and data are shown as fold change compared to air control mice. Data are shown as mean ± SEM with individual data points represented by the following symbols: Air (black circles), PG/VG (black squares), Apple (black triangles), Cherry (black diamonds), Strawberry (white circles), Wintergreen (white squares), Smooth & Mild Tobacco (white triangles), with * p < 0.05, ** p < 0.01, and *** p < 0.001 vs. air controls. n = 3 for male- and female-only groups.