Fig. 2

Mmp12 increases serum cotinine levels in house-dust mite treated mice exposed to JUUL menthol for 60 days. a 3-day of JUUL-flavored menthol aerosol exposure significantly increased Mmp12 gene expression in WT mice compared to air controls. Student’s t-test. Data represent the mean ± SEM for n = 4 animals per group. *p < 0.05 statistically different from Air control animals. Sub-chronic (60 days) exposures to JUUL menthol-flavored aerosol b significantly up-regulated the expression of the Mmp12 gene in HDM treated animals; c significantly increased serum cotinine levels in WT animals, while reducing levels in KO mice (d); e dysregulated the expression of the alpha-7 nicotinic receptor compared to air controls in WT mice; and f modulated the gene expression of the alpha-7 nicotinic receptor in KO mice. Data represent the mean ± SEM for n = 4–8 animals per group. One-way ANOVA followed by the Tukey’s test post-hoc test. *p < 0.05 statistically different from Air control