RESUMO
Paraquat (PQ) intoxication causes thousands of mortalities every year, worldwide. Its pulmonary-targeted accumulation and the acute lung injury it subsequently causes, remain a challenge for detoxification treatment. A previous study has demonstrated that the upregulation of nuclear factor erythroid-2 related factor 2 (Nrf2) prevents PQ toxicity in cell line and murine models. As Nrf2 target genes include a group of membrane transporters, the current study assessed the protective mechanism exerted by Nrf2 against PQ toxicity and intracellular PQ accumulation via its effects on P-glycoprotein (P-gp), a downstream transporter of Nrf2. Adenovirus vectors containing the Nrf2 gene were transfected into A549 cells. Cell proliferation was assessed by Cell Counting Kit-8. The levels of LDH, MDA, SOD, TNF-α, IL-6 levels were detected using their respective ELISA kits. In addition, the levels of Nrf2 and P-gp protein expression were detected by western blot analysis. The concentration of PQ was measured by HPLC. The results revealed that overexpressed Nrf2 significantly increased P-gp protein levels, decreased the intracellular accumulation of PQ and attenuated PQ-induced toxicity. However, the protective effects of Nrf2 overexpression on PQ-challenged A549 cells were abrogated following cyclosporine A treatment, a competitive inhibitor of P-gp, which also increased intracellular PQ levels. These data indicated that Nrf2 gene overexpression prevented PQ toxicity in A549 cells, potentially via the upregulation of P-gp activity and the inhibition of intracellular PQ accumulation. Thus, Nrf2 and P-gp may serve as potential therapeutic targets for the treatment of PQ-induced injury.
RESUMO
OBJECTIVE: To investigate the intervention effect of thalidomide on paraquat-induced acute lung injury in mice and its mechanism. METHODS: Male ICR mice were randomly allocated to negative control group (n = 30), thalidomide control group (n = 30), paraquat poisoning group (n = 30), 50 mg/kg thalidomide treatment group (n = 30), 100 mg/kg thalidomide treatment group (n = 30), and 150 mg/kg thalidomide treatment group (n = 30). The negative control group was intraperitoneally injected with the same volume of saline; the thalidomide control group was intraperitoneally injected with thalidomide (150 mg/kg); the paraquat poisoning group was intraperitoneally injected with diluted paraquat solution (22 mg/kg); each thalidomide treatment group was intraperitoneally injected with the same volume of paraquat solution (22 mg/kg) and was injected with thalidomide (50, 100, or 150 mg/kg) 1 h later. All mice were anesthetized and sacrificed at 1, 3, or 7 d after paraquat poisoning, and their lung tissue was collected. The levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, and IL-6 in lung tissue were measured by double-antibody sandwich ELISA; the mRNA expression of nuclear factor-kappa B (NF-κB) was measured by RT-PCR; the protein expression of nuclear NF-kgr;B p65 was measured by Western blot. The pathological changes of lung tissue were observed under light microscope; the wet/dry ratio of the lung was calculated. RESULTS: Compared with the negative control group, the paraquat poisoning group had significantly increased levels of TNF-α, IL-1ß, IL-6, NF-κB mRNA, and nuclear NF-κB p65 and wet/dry ratio of the lung (P < 0.05). Compared with the paraquat poisoning group, the thalidomide treatment groups had significantly decreased levels of TNF-α, IL-1ß, IL-6, NF-κB mRNA, and nuclear NF-κB p65 and wet/dry ratios of the lung (P < 0.05), and the 150 mg/kg thalidomide treatment group showed the most significant decrease in the levels of TNF-α, IL-1ß, IL-6, NF-κB mRNA, and nuclear NF-κB p65. The observation of pathological changes showed that the paraquat poisoning group had the most marked lung tissue damage at 3 d after poisoning, and the lung tissue damage was lessened in the thalidomide treatment groups. CONCLUSION: Thalidomide can reduce paraquat-induced acute lung injury and lung edema. The mechanism may include inhibition of NF-κB activation and expression and downregulation of TNF-α, IL-1ß, and IL-6.
