Figure 1.

Roles of reactive oxygen species (ROS) and TRPM8 in IL-8 induction by non-menthol cigarette smoke extract (Non-M-CSE) and menthol cigarette smoke extract (M-CSE) in human bronchial epithelial cells (HBECs). (A) Cells were exposed to medium alone, 0.5–2% Non-M-CSE or M-CSE for 24 h. (B,C) Cells were pretreated with 5–20 μM AMTB (a TRPM8 antagonist) for 1 h and then exposed to medium alone, 1% Non-M-CSE or 1% M-CSE for 24 h. (D) Cells were pretreated with N-acetyl-cysteine (NAC, a ROS scavenger; 1 mM), AMTB (20 μM), or EGTA (an extracellular Ca²⁺ chelator; 500 μM) for 1 h and then exposed to medium alone, 1% Non-M-CSE, or M-CSE for 24 h. Protein levels of IL-8 were analyzed by Western blot. Data from each group are means ± SEM from four independent experiments. ^*p < 0.05 vs. the medium group (A–D); ^@p < 0.05 vs. the Non-M-CSE group with the same concentrations (A,D); #p < 0.05 vs. the same type of CSE group without pretreatment (B–D).