Estrogen, but not testosterone, down-regulates cytokine production in nicotine-induced murine macrophage

We have investigated the effects of 17beta-estradiol (E2) and testosterone (Te) on the production of proinflammatory factors by nicotine-induced murine macrophage (Ana-1). Ana-1 pretreated with or without E2/Te was challenged with different doses of nicotine at various time points. TNF-alpha, IL-1beta IFN-gamma, and IL-8 in the supernatant of Ana-1 were detected using radioimmunoassay (RIA) or enzyme-linked immunosorbent assay (ELISA). The presence of estrogen and androgen receptors in Ana-1 was detected by reverse transcription polymerase chain reaction (RT-PCR) and Western blotting. E2 could obviously suppress the expression of TNF-alpha and IL-1beta whereas Te could not. There were no obvious changes in the levels of either IL-8 or IFN-gamma in Ana-1 stimulated with nicotine or sex hormones (p>0.05). The antagonist tamoxifen of E2 abolished the effects of E2 on TNF-alpha and IL-1beta whereas the antagonist cyproterone of Te did not alter the effects of Te on Ana-1. Furthermore, RT-PCR and Western blotting showed that both the estrogen receptors (ER-alpha and ER-beta existed in Ana-1; however, androgen receptor (AR) was not detectable. Our data suggested that E2 could regulate the immunoreaction in the nicotine-induced inflammatory process possibly through classic intercellular ER, whereas Te had no significant effect in this process.