Fig. 4

The effect of cigarette smoke extract (CSE) and electronic cigarette vapour (ECVE) exposure on the capacity of key lung pathogens to stimulate IL-8 [(a)-(d) (i)] and TNF-α [(a)-(d)(ii)]production from A549 cells (n = 8). Cell pathway signaling inhibitors were added to determine the contribution of each pathway to the cytokine production observed and the subsequent reduction in secretion of IL-8 or TNF- α measured. P-values are shown in (Additional file 1: Table S3)