Nicotine inhibits the production of inflammatory mediators in U937 cells through modulation of nuclear factor-kappaB activation.

Cigarette smoke is a major risk factor for lung cancer and respiratory infections. This increased susceptibility may result from cigarette smoke-induced impairment of the immune system. In this study, we evaluated the effect of nicotine on the production of inflammatory mediators by activated macrophages. Pretreatment with nicotine caused a significant inhibition of LPS-induced IL-1, IL-8, and PGE2 expression at the transcriptional level in U937 cells. Nicotine inhibited the activation of a transcription factor, NF-kappaB, which in turn, binds to and mediates transcriptional activation of these genes. These inhibitory effects of nicotine may contribute to cigarette smoke-induced immunosuppression.