Figure 6. Four-month exposure to ENDS vapor reduces the expression of surfactant proteins.

(A) Quantification of SP-D by ELISA from BAL fluid. n = 4 or 5 per group. (B and C) Relative gene expression of surfactant-associated proteins (SP-A, SP-B, SP-C, and SP-D) from whole lung homogenate. n = 4 or 5 per group. The quantified results are expressed as means ± SEM. Significance was determined by 1-way ANOVA with Bonferroni’s correction for multiple comparisons. **P < 0.01. NS, not significant.