Background and aims： Ingestion of paraquat （PQ）, a widely used herbicide, can cause severe toxicity in humans, leading to a poor survival rate and prognosis. One of the main causes of death by PQ is PQ-induced pul-...Background and aims： Ingestion of paraquat （PQ）, a widely used herbicide, can cause severe toxicity in humans, leading to a poor survival rate and prognosis. One of the main causes of death by PQ is PQ-induced pul- monary fibrosis, for which there are no effective therapies. The aim of this study was to evaluate the effects of ra- pamycin （PAPA） on inhibiting PQ-induced pulmonary fibrosis in mice and to explore its possible mechanisms. Methods： Male C57BL/6J mice were exposed to either saline （control group） or PQ （10 mg/kg body weight, intraper- itoneally; test group）. The test group was divided into four subgroups： a PQ group （PQ-exposed, non-treated）, a PQ＋RAPA group （PQ-exposed, treated with RAPA at I mg/kg intragastrically）, a PQ＋MP group （PQ-exposed, treated with methylprednisolone （MP） at 30 mg/kg intraperitoneally）, and a PQ＋MP＋RAPA group （PQ-exposed, treated with MP at 30 mg/kg intraperitoneally and with PAPA at 1 mg/kg intragastrically）. The survival rate and body weight of all the mice were recorded every day. Three mice in each group were sacrificed at 14 d and the rest at 28 d after intox- ication. Lung tissues were excised and stained with hematoxylin-eosin （H＆E） and Masson＇s trichrome stain for his- topathological analysis. The hydroxyproline （HYP） content in lung tissues was detected using an enzyme-linked im- munosorbent assay （ELISA） kit. The expression of transforming growth factor-β1 （TGF-β1） and α-smooth muscle actin （α-SMA） in lung tissues was detected by immunohistochemical staining and Western blotting. Results： A mice model of PQ-induced pulmonary fibrosis was established. Histological examination of lung tissues showed that PAPA treatment moderated the pathological changes of pulmonary fibrosis, including alveolar collapse and interstitial collagen depo- sition. HYP content in lung tissues increased soon after PQ intoxication but had decreased significantly by the 28th day after PAPA treatment. Immunohistochemical staining and Western blotting showed that PAPA treatment significantly down-regulated the enhanced levels of TGF-β1 and e-SMA in lung tissues caused by PQ exposure. However, PAPA treatment alone could not significantly ameliorate the lower survival rate and weight loss of treated mice. MP treatment enhanced the survival rate, but had no significant effects on attenuating PQ-induced pulmonary fibrosis or reducing the expression of TGF-β1 and a-SMA. Conclusions： This study demonstrates that PAPA treatment effectively suppresses PQ-induced alveolar collapse and collagen deposition in lung tissues through reducing the expression of TGF-β1 and a-SMA. Thus, RAPA has potential value in the treatment of PQ-induced pulmonary fibrosis.展开更多
基金supported by the National Key Technology R&D Program of China(No.2011BAI10B07)the National Basic Research Program(973)of China(No.2012CB517603)the National High-Tech R&D Program(863)of China(No.2012AA02A512)
文摘Background and aims： Ingestion of paraquat （PQ）, a widely used herbicide, can cause severe toxicity in humans, leading to a poor survival rate and prognosis. One of the main causes of death by PQ is PQ-induced pul- monary fibrosis, for which there are no effective therapies. The aim of this study was to evaluate the effects of ra- pamycin （PAPA） on inhibiting PQ-induced pulmonary fibrosis in mice and to explore its possible mechanisms. Methods： Male C57BL/6J mice were exposed to either saline （control group） or PQ （10 mg/kg body weight, intraper- itoneally; test group）. The test group was divided into four subgroups： a PQ group （PQ-exposed, non-treated）, a PQ＋RAPA group （PQ-exposed, treated with RAPA at I mg/kg intragastrically）, a PQ＋MP group （PQ-exposed, treated with methylprednisolone （MP） at 30 mg/kg intraperitoneally）, and a PQ＋MP＋RAPA group （PQ-exposed, treated with MP at 30 mg/kg intraperitoneally and with PAPA at 1 mg/kg intragastrically）. The survival rate and body weight of all the mice were recorded every day. Three mice in each group were sacrificed at 14 d and the rest at 28 d after intox- ication. Lung tissues were excised and stained with hematoxylin-eosin （H＆E） and Masson＇s trichrome stain for his- topathological analysis. The hydroxyproline （HYP） content in lung tissues was detected using an enzyme-linked im- munosorbent assay （ELISA） kit. The expression of transforming growth factor-β1 （TGF-β1） and α-smooth muscle actin （α-SMA） in lung tissues was detected by immunohistochemical staining and Western blotting. Results： A mice model of PQ-induced pulmonary fibrosis was established. Histological examination of lung tissues showed that PAPA treatment moderated the pathological changes of pulmonary fibrosis, including alveolar collapse and interstitial collagen depo- sition. HYP content in lung tissues increased soon after PQ intoxication but had decreased significantly by the 28th day after PAPA treatment. Immunohistochemical staining and Western blotting showed that PAPA treatment significantly down-regulated the enhanced levels of TGF-β1 and e-SMA in lung tissues caused by PQ exposure. However, PAPA treatment alone could not significantly ameliorate the lower survival rate and weight loss of treated mice. MP treatment enhanced the survival rate, but had no significant effects on attenuating PQ-induced pulmonary fibrosis or reducing the expression of TGF-β1 and a-SMA. Conclusions： This study demonstrates that PAPA treatment effectively suppresses PQ-induced alveolar collapse and collagen deposition in lung tissues through reducing the expression of TGF-β1 and a-SMA. Thus, RAPA has potential value in the treatment of PQ-induced pulmonary fibrosis.
