ABSTRACT
OBJECTIVE: To explore the effects of nano-silicon dioxide( SiO_2) on the survival and poly( ADP-ribose)polymerase-1( PARP-1) expression in human bronchial epithelial cells( 16 HBE cells). METHODS: i) The 16 HBE cells were treated with nano-SiO_2 at concentrations ranging from 0 to 100 mg/L for 24. 0 hours,and CCK-8 assay was used to examine cell viability. ii) The 16 HBE cells were divided into 6 groups: solvent control group( equal volume solvent treatment),micro-SiO_2 control group( treated with 20 mg/L micro-SiO_2),5,10,and 20 mg/L nano-SiO_2 groups( treated with the corresponding final dose of nano-SiO_2),and curcumin group. The curcumin group was given pretreatment with curcumin at a final concentration of 10 μmol/L for 2. 0 hours followed by treatment with a final concentration of 20 mg/L of nano-SiO_2. Cells in each group were harvested at time points of 4. 0,12. 0 and 24. 0 hours after treatment. The relative expression of PARP-1 mRNA and protein in 16 HBE cells was detected by quantitative real-time polymerase chain reaction and Western blotting respectively. RESULTS: i) The survival of 16 HBE cells decreased with increasing nano-SiO_2 treatment dose,showing a dose-effect relationship( P < 0. 01). ii) The expression of PARP-1 mRNA and protein in 16 HBE cells were dose-dependently decreased after nano-SiO_2 stimulation at the 12. 0 and 24. 0 hours time points( P < 0. 01). The expression of PARP-1 mRNA and protein in 5,10,and 20 mg/L nano-SiO_2 groups decreased at the above mentioned time points( P < 0. 05),compared with the solvent control group at the same time points. The expression of PARP-1 mRNA and protein in 20 mg/L nano-SiO_2 group was lower than that in the micro-SiO_2 control group at the same 12. 0 and 24. 0 hours time point( P < 0. 05). The above two indexes of cells were higher in curcumin group than that of 20 mg/L nano-SiO_2 group at the 12. 0 hours time point( P < 0. 05). CONCLUSION: Nano-SiO_2 stimulation can lead to decrease survival of 16 HBE cells in a dose-dependent manner and down-regulation of PARP-1 expression may be one of the mechanisms of proliferation and inhibition of 16 HBE cells induced by nano-SiO_2. Curcumin has certain protective effect on nano-SiO_2-induced 16 HBE cell injury.
ABSTRACT
Objective To explore the effect and mechanism of CD4+CD25+Tregs(Tregs)on the protective efficacy of glutha?tione?S?transferase(GST)against Schistosoma japonicum in mice. Methods Female BALB/c mice were divided randomly into five groups:a normal control group,an infected control group,an anti?CD25mAb group,a GST immunization group and a com?bination group with GST immunization and anti?CD25 mAb. The GST group and combination group were injected percutaneously with GST 50μg each mouse,the other two groups were injected with equal volume PBS. The immunization was performed for 3 times for two?week interval,and 2 weeks after the last immunization,each mouse was challenged with 40 S. japonicum cercaria. Two weeks post?infection,the combination group and anti?CD25 mAb group were injected intraperitoneally with 300μg anti?CD25 mAb each mouse. The mice were succumbed 2 weeks,3 weeks,4 weeks and 5 weeks post?infection respectively. The per?centages of CD4+CD25+Tregs in splenocytes of mice were measured with flow cytometer. The levels of IFN?γ,IL?2,IL?4,IL?5 and TGF?βin cell cultural supernatants were determined by sandwich?ELISA after stimulation with Con A. The liver sections were stained with hematoxylin and eosin. Results The worm burden in the combination group(15.80 ± 2.74)was significantly lower than those of the infected control group(27.78 ± 3.15),anti?CD25 mAb group(21.50 ± 4.21),and GST group(20.84 ± 6.46). Compared to those of the infected control group,the percentages of CD4+CD25+Tregs were significantly higher in the GST group,while the percentages of CD4+CD25+Tregs were significantly lower post?anti?CD25 mAb?administration. Regardless of GST administration,the levels of IFN?γ,IL?2,IL?4 and IL?5 after anti?CD25 mAb were significantly higher than those of the in?fected control groups. There were no significant differences of egg granuloma and the level of TGF?βbetween each group. Con?clusion CD4+CD25+Tregs could be partially blocked by anti?CD25 mAb while Th1 and Th2 type immunization response could be enhanced,which plays a role in improving the protective efficacy of GST against of S. japonicum.