Dithiocarbamates enhance tumor necrosis factor-α production by rabbit alveolar macrophages, despite inhibition of NF-ΚB

The tissue-fixed macrophage (M0) plays a key role in coordinating the excessive inflammatory response following shock or sepsis. Rt active oxygen intermediates have been recently described as second messengers involved in signal transduction in these cells, including the activation of the transcription factors NF-kappa B and AP-1. The dithiocarbamates are potent antioxidants that inhibit NF-kappa B activation. We postulated that dithiocarbamates would inhibit M0 activation via inhibition of NF-kappa B. Rabbit alveolar M0 were obtained by bronchoalveolar ravage End exposed to either pyrrolidine dithiocarbamate (PDTC) or diethyl dithiocarbamate (DDTC) followed by stimulation with LPS (10 ng/mL). Supernatants were analyzed for TNF and prostaglandin E-2, (PGE(2)) and F2-isoprostane (ISP), a marker of membrane lipid peroxidation, production at 18 h. PDTC and DDTC significantly enhanced production of TNF while inhibiting PGE(2) and ISP production compared with LPS alone (p < .05). Northern blots revealed increased mRNA for TNF after pretreatment with PDTC, compared with LPS alone. Western blots and oligonucleotide gel shifts of nuclear proteins revealed inhibition of NF-kappa B activation by both PDTC and DDTC. AP-1 activity was shifted to earlier time points by PDTC pretreatment. These results demonstrate transcriptional and functional enhancement of TNF production despite inhibition of NF-kappa B activation. This may be due in part to a loss of autocrine feedback inhibition by PGE(2) and enhancement of AP-1 activity. On the basis of these results, we conclude NF-kappa B may be necessary but, in contrast to prior analyzes, is not sufficient for optimal response of the alveolar M0 to endotoxin.