The presence of serotonin in cigarette smoke: A possible mechanistic link to 5-HT-induced airway inflammation

Kwok Wai LAU, Louise Yuting CUI, Stanley Chi Hang CHAN, Mary Sau Man IP, Judith Choi Wo MAK

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5 Citations (Scopus)


We previously reported the involvement of serotonin (5-HT) metabolism in cigarette smoke-induced oxidative stress in rat lung in vivo. Here, we report cigarette smoke as a source of serotonin (5-HT) to the airways and aim at investigating the effects of 5-HT on oxidative stress and inflammation in human bronchial epithelial cells (BEAS-2B). A 5-HT analog was identified to be present in aqueous phase cigarette smoke using the LC-MS/MS approach, which was later confirmed by a 5-HT enzyme-linked immune assay (EIA). Furthermore, exposure to 5-HT caused a time-dependent elevation of intracellular ROS level, which was blocked in the presence of apocynin (a NOX inhibitor). In support, the immunoblot analysis indicated that there was an increase in the expression of NOX2 time-dependently. 5-HT-induced elevation of IL-8 at both mRNA and protein levels was observed, which was inhibited by TEMPOL (a free radical scavenger), and inhibitors for p38 MAPK (SB203580) and ERK (U0126), in line with the time-dependent phosphorylation of p38 MAPK and ERK. In conclusion, our findings suggest that 5-HT presented in bronchial epithelium of smokers may be involved in cigarette smoke-induced oxidative stress and inflammation via activation of p38 MAPK and ERK pathway after the formation of free radicals. Copyright © 2016 Taylor & Francis.

Original languageEnglish
Pages (from-to)495-502
JournalFree Radical Research
Issue number5
Early online date26 Feb 2016
Publication statusPublished - May 2016



Lau, W. K. W., Cui, L. Y., Chan, S. C. H., Ip, M. S. M., & Mak, J. C. W. (2016). The presence of serotonin in cigarette smoke: A possible mechanistic link to 5-HT-induced airway inflammation. Free Radical Research, 50(5), 495-502. doi: 10.3109/10715762.2016.1145355


  • Airway inflammation
  • Cigarette smoking
  • Interleukin-8
  • Reactive oxygen species
  • Serotonin