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Objective: To investigate the effect of melatonin (MT) on p38 mitogen-activated protein kinase (MAPK) signaling pathway in rats with phosgene-induced lung injury., Methods: Fifty specific pathogen-free male Sprague-Dawley rats were randomly divided into phosgene inhalation group, air control group, saline control group, MT treatment group, and SB203580 (specific inhibitor of p38 MAPK) group, with 10 mice in each group. All groups except the air control group were exposed to phosgene, and the animals were sacrificed 6 h later. Lung wet/dry weight (W/D) ratio and the content of malondialdehyde (MDA) and nitric oxide (NO) and activity of myeloperoxidase (MPO) in bronchoalveolar lavage fluid (BALF) were measured. The qualitative and quantitative expression of p38 MAPK and phospho-p38 MAPK (p-p38) was measured by immunohistochemistry (IHC) and Western blot, respectively. Inducible nitric oxide synthase (iNOS) level in lung tissue was determined by Western blot., Results: Compared with the air control group, the phosgene inhalation group had significantly increased lung W/D ratio and neutrophil count in BALF (P < 0.01); the MT treatment group had significantly lower neutrophil count and lung W/D ratio than the phosgene inhalation group (P < 0.05). IHC demonstrated that the air control group had relatively weak expression of p-p38 in lung tissue; the expression of p-p38 was significantly up-regulated after phosgene inhalation, and it was mainly distributed in infiltrating inflammatory cells and vascular endothelial cells, positive in the cytoplasm and nucleus of many cells. The distribution of p-p38-positive cells in the MT treatment and SB203580 groups was similar to that in the phosgene inhalation group, but the MT treatment and SB203580 groups had a significantly reduced number of cells with p-p38-positive nuclei and a significantly reduced intensity of p-p38 expression signals. The phosgene inhalation group had significantly increased content of MDA and NO and activity of MPO compared with the air control group (P < 0.01); the MT treatment and SB203580 groups had significantly reduced content of MDA and NO and activity of MPO compared with the phosgene inhalation group (P < 0.05), but had higher content of MDA and NO and activity of MPO than the air control group. The Western blot showed that the phosgene inhalation group had significantly increased expression of iNOS and p-p38 compared with the air control group (P < 0.01); the MT treatment and SB203580 groups had lower expression of iNOS and p-p38 than the phosgene inhalation group (P < 0.05)., Conclusion: MT and SB203580 have a significant protective effect in rats with phosgene-induced lung injury, and the mechanism may be associated with scavenging free radicals and inhibiting activation of p38 MAPK and expression of iNOS.

Objective: To investigate the effects of adenovirus-delivered angiopoietin-1 siRNA (Ad. Ang-1siRNA) on the expression of matrix metalloproteinase-2, 9 (MMP-2, 9) and tissue inhibitor of metallopro-teinase-1 (TIMP-1) in rats with acute lung injury (ALI) induced by phosgene (Psg)., Methods: We first established a rat model of Psg-induced acute lung injury (ALI). The rats were randomly divided into 6 groups: air control group with exposure to air, air+adenovirus (air+Ad) group with caudal vein injection of 1×10(8) pfu/ml adenovirus 1 h after air exposure, air+Ad/Ang1 group with caudal vein injection of 1×10(8) pfu/ml Ad.Ang-1siRNA 1 h after air exposure, Psg group with exposure to 8.33 mg/L Psg (purity 100%, of the same volume as the inhaled air in the air control group) for 5 min, Psg+Ad group with caudal vein injection of 1×10(8) pfu/ml adenovirus 1 h after exposure to the same dose of Psg, and Psg+Ad/Ang1 group with caudal vein injection of 1×10(8) pfu/ml Ad.Ang-1siRNA 1 h after exposure to the same dose of Psg. Serum, bronchoalveolar lavage fluid (BALF), and lung tissue were collected 36 h after exposure. The protein expression of Ang-1, MMP-2, 9, and TIMP-1 in serum and BALF was determined by double-antibody sandwich ELISA. RT-PCR was used to determine the mRNA levels of Ang-1, MMP-2, 9, and TIMP-1 in lung tissue. The protein expression of MMP-2, 9 and TIMP-1 in lung tissue was determined by Western blot., Results: A rat model of Psg-induced ALI was successfully established. The levels of MMP-2, 9 in serum, BALF, and lung tissue were significantly increased in the Psg group and Psg+Ad/Ang1 group as compared with the control group (P<0.01); no significant change was observed in serum TIMP-1 protein expression (P>0.05); interestingly, TIMP-1 protein expression in BALF and lung tissue was significantly increased (P<0.01). Compared with the Psg group, the Psg+Ad/Ang1 group showed a significant decrease in MMP-2, 9 expression in BALF, serum, and lung tissue (P<0.05), but no significant change in protein expression of TIMP-1 was discovered (P>0.05)., Conclusion: Ad.Ang-1siRNA has a potential beneficial effect in rats with Psg-induced ALI through inhibition of MMP-2, 9 expression, but has no significant effect on the expression of TIMP-1.

Objective: To study apoptosis of pulmonary epithelial cells and endothelial cells in mice with pulmonary edema induced by phosgene exposure., Methods: Thirty-two mice were divided into normal group and phosgene group with 16 mice in each group. The mice in phosgene group were exposed to phosgene (11.9 mg/L) for 5 min and those in the control group to air. Four hours after exposure, alveolar type II cells were isolated and cultured to observe their apoptosis by electron microscope and flow cytometry. The lung tissues were also taken for DNA gel electrophoresis and TUNEL assay., Results: Apoptotic bodies were observed in alveolar type II cells under electron microscope in phosgene group, which had higher cell apoptosis rate than the control group [(40.26+/-7.74)% vs (1.58+/-1.01)%, P<0.001] as determined by flow cytometry. Ladder-like DNA fragmentation pattern was observed in DNA gel electrophoresis in phosgene group with apoptosis of the pulmonary epithelial and endothelial cells observed by TUNEL., Conclusions: Phosgene can induce pulmonary epithelial and endothelial cell apoptosis in mice, suggesting that the mechanism of phosgene-induced pulmonary edema involves apoptosis of the lung cells.

Objective: To study the apoptosis of alveolar type II cells, alterations of vascular endothelial growth factor (VEGF), VEGF receptor (Flt1) in serum and lung and expression of VEGF mRNA in lung in pulmonary edema mice induced by phosgene., Methods: Twenty-six BALB/C mice were randomly divided into 2 groups: control group, exposed group (13 mice in each group). Mice of exposed group were intoxicated by inhalation of phosgene 11.9 mg/L for 5 minutes. Mice of control group were treated as the same way by inhalation of air. Isolation of mice alveolus type II cells 4 h after intoxication was carried out to observe their apoptosis under electron microscope. Contents of VEGF and Flt1 in lung and serum by ELISA, and expression of VEGF mRNA were determined., Results: Alveolar type II cells were identified by tannic acid staining and electron microscopy. After exposed to 11.9 mg/L of phosgene for 5 minutes, the apoptotic body in alveolus type II cells was found in exposed group. The contents of VEGF in serum and lung and Flt1 in lung of exposed mice [(134.07 +/- 120.26), (477.76 +/- 98.06), (1,2818.48 +/- 2,304.15) pg/ml] were significantly lower than those of control group [(445.57 +/- 173.30), (1,026.87 +/- 474.56), (21,976.51 +/- 7,421.01) pg/ml, P < 0.05] but the content of Flt1 in serum [(2,369.56 +/- 381.70) pg/ml] was higher than that in control group [(1,898.00 +/- 453.69) pg/ml, P < 0.05]. The expression of VEGF mRNA in pulmonary edema mice was decreased., Conclusion: Phosgene can induce apoptosis of alveolar type II cells, and decrease in the content of VEGF and Flt1, and expression of VEGF mRNA in lung.

Objective: To observe the significance of ricin (RT) with chemical nidification to reduce the hepatotoxicity in mice and its anticancer effect., Methods: Mice were exposed to RT and RT-PDP [ricin chemically modified by N-succinimidyl 3-(2-pyridyldithio)-propionate, (SPDP)] respectively, and their serum activity of glutathione-S-transferase (GST) and liver glutathione (GSH) content were determined. The ultramicro-structure under electron microscope was also observed., Results: The GST activity increased with doses, and the increase in ricin group was higher than that in RT-PDP group; the activities of GST in RT group at 12.5, 15.0 micro g/kg [(93.65 +/- 12.30), (153.71 +/- 26.64) IU/L respectively] were higher than those in RT-PDP group [(62.97 +/- 11.22), (78.20 +/- 15.71) IU/L] (P < 0.05). The contents of GSH were decreased with doses; but the contents of GSH in RT-PDP group at 2.5, 5.0, 7.5, 10.0, 15.0 micro g/kg [(6.34 +/- 1.43), (4.14 +/- 1.82), (3.54 +/- 0.64), (2.73 +/- 1.82), (1.82 +/- 0.62) micro mol/L respectively] were still higher than those in RT group [(3.53 +/- 0.95), (2.12 +/- 0.54), (1.82 +/- 0.71), (1.52 +/- 0.34), (0.81 +/- 0.36) micro mol/L] (P < 0.01). Electron microscopic examination showed that the injury of liver cells in RT group was more severe than that in RT-PDP group., Conclusion: The hepatotoxicity of ricin in mice may be reduced by chemical modification.