OBJECTIVETo investigate the effect of paraquat (PQ) on reactive oxygen species (ROS) and neutrophil apoptosis and its possible signal transduction pathways.

METHODSCultured neutrophils were treated with different concentrations of PQ for 6-24 h. The apoptosis rate of neutrophils and ROS content were determined by flow cytometry. The exoressions of nuclear factor kappa B (NF-κB) and Caspase 3 were detected by Western blot. These parameters were checked again after NF-κB and Caspase 3 antagonist were applied.

RESULTSPQ could boost ROS generation and depress neutrophil apoptosis significantly. At the same time PQ could enhance the expression of NF-κB and inhibit the expression of Caspase 3. These effects could be reversed by ROS inhibitor diphenyleneiodonium (DPI) and NF-κB inhibitor pyrrolidinedithiocarbamate (PDTC).

CONCLUSIONPQ is a potent inducer of ROS and can inhibit neutrophil apoptosis by activating NF-κB and surpressing Caspase 3 activity.

Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Cells, Cultured ; NF-kappa B ; antagonists & inhibitors ; metabolism ; Neutrophils ; cytology ; drug effects ; Paraquat ; toxicity ; Pyrrolidines ; pharmacology ; Reactive Oxygen Species ; metabolism ; Signal Transduction ; Thiocarbamates ; pharmacology

Although 4,4'-diaminodiphenylsulfone (DDS, dapsone) has been used to treat several dermatologic conditions, including Hansen disease, for the past several decades, its mode of action has remained a topic of debate. We recently reported that DDS treatment significantly extends the lifespan of the nematode C. elegans by decreasing the generation of reactive oxygen species. Additionally, in in vitro experiments using non-phagocytic human fibroblasts, we found that DDS effectively counteracted the toxicity of paraquat (PQ). In the present study, we extended our work to test the protective effect of DDS against PQ in vivo using a mouse lung injury model. Oral administration of DDS to mice significantly attenuated the lung tissue damage caused by subsequent administration of PQ. Moreover, DDS reduced the local expression of mRNA transcripts encoding inflammation-related molecules, including endothelin-1 (ET-1), macrophage inflammatory protein-1alpha (MIP-1alpha), and transforming growth factor-beta (TGF-beta). In addition, DDS decreased the PQ-induced expression of NADPH oxidase mRNA and activation of protein kinase Cmicro (PKCmicro). DDS treatment also decreased the PQ-induced generation of superoxide anions in mouse lung fibroblasts. Taken together, these data suggest the novel efficacy of DDS as an effective protective agent against oxidative stress-induced tissue damages.
Animals ; Cells, Cultured ; Chemokine CCL3/drug effects/metabolism ; Dapsone/*administration & dosage ; Endothelin-1/drug effects/metabolism ; Fibroblasts/drug effects ; Herbicides/*antagonists & inhibitors/toxicity ; Lung Injury/chemically induced/*prevention & control ; Male ; Mice ; Mice, Inbred BALB C ; Oxidative Stress ; Paraquat/*antagonists & inhibitors/toxicity ; Protective Agents/*administration & dosage ; Protein Kinase C/genetics/metabolism ; Superoxides/analysis ; Transforming Growth Factor beta/drug effects/metabolism