Figure 1

The inhibitory actions of nicotine on LPS-induced IL-6 and TNF-α productions are mechanistically different. (A) ELISA and (B) q-PCR detection of IL-6 and TNF-α in RAW264.7 macrophages incubated with vehicle or the indicated amounts of nicotine for 10 min and then stimulated with vehicle or 100 ng/ml LPS for 9 h. (C) ELISA detection of IL-6 and TNF-α in the supernatant of peritoneal macrophages incubated with vehicle or the indicated concentrations of nicotine for 10 min and stimulated with vehicle or 1 ng/ml LPS for 9 h. (D) q-PCR detection of IL-6 and TNF-α mRNAs in peritoneal macrophages treated with 1 ng/ml LPS in the presence or absence of 0.1 nM nicotine. (E) RAW264.7 cells were transfected with control siRNA or siRNA against Dicer for 48 h (Dicer protein was examined with immunoblotting, left panel, representative of three independent experiments), and stimulated with LPS in the presence or absence of 5 mM nicotine. IL-6 and TNF-α were measured by ELISA. The percentages were calculated using LPS alone as 100%. Data represent mean ± SD (n = 3). ^*P < 0.05, ^**P < 0.01 by Student's t-test.