ROS generated by CYP450, especially CYP2E1, mediate mitochondrial dysfunction induced by tetrandrine in rat hepatocytes.

AIM: Tetrandrine, an alkaloid with a remarkable pharmacological profile, induces oxidative stress and mitochondrial dysfunction in hepatocytes; however, mitochondria are not the direct target of tetrandrine, which prompts us to elucidate the role of oxidative stress in tetrandrine-induced mitochondrial dysfunction and the sources of oxidative stress. METHODS: Rat primary hepatocytes were isolated by two-step collagenase perfusion. Mitochondrial function was evaluated by analyzing ATP content, mitochondrial membrane potential (MMP) and the mitochondrial permeability transition. The oxidative stress was evaluated by examining changes in the levels of reactive oxygen species (ROS) and glutathione (GSH). RESULTS: ROS scavengers largely attenuated the cytotoxicity induced by tetrandrine in rat hepatocytes, indicating the important role of ROS in the hepatotoxicity of tetrandrine. Of the multiple ROS inhibitors that were tested, only inhibitors of CYP450 (SKF-525A and others) reduced the ROS levels and ameliorated the depletion of GSH. Mitochondrial function assays showed that the mitochondrial permeability transition (MPT) induced by tetrandrine was inhibited by SKF-525A and vitamin C (VC), both of which also rescued the depletion of ATP levels and the mitochondrial membrane potential. Upon inhibiting specific CYP450 isoforms, we observed that the inhibitors of CYP2D, CYP2C, and CYP2E1 attenuated the ATP depletion that occurred following tetrandrine exposure, whereas the inhibitors of CYP2D and CYP2E1 reduced the ROS induced by tetrandrine. Overexpression of CYP2E1 enhanced the tetrandrine-induced cytotoxicity. CONCLUSION: We demonstrated that CYP450 plays an important role in the mitochondrial dysfunction induced by the administration of tetrandrine. ROS generated by CYP450, especially CYP2E1, may contribute to the mitochondrial dysfunction induced by tetrandrine.

Effect of Feitai on bleomycin-induced pulmonary fibrosis in rats.

The current therapeutic approaches for pulmonary fibrosis, which is characterized by fibroblast proliferation and extracellular matrix remodeling, are unsatisfactory. Feitai, consisting of several herbs, is a folk formula for pulmonary tuberculosis therapy in China. To investigate the effects of Feitai on pulmonary fibrosis, Feitai was administered orally to bleomycin (BLM)-treated rats, and the lung toxicity effects were evaluated according to inflammatory cell count, protein concentration, and lactate dehydrogenase (LDH) activity in the bronchoalveolar lavage fluid (BALF), malondialdehyde level and hydroxyproline content in lung tissue 28 days post-BLM. Serial sections of the lung were stained with hematoxylin and eosin (HE) and Masson trichrome, respectively. The degree of fibrosis was assessed quantitatively using LEICA QWin image analyzer. Results showed that Feitai inhibited BLM-induced lung fibrotic lesions in a dose-dependent manner as reflected by decreased the lung hydroxyproline content and lung fibrosis fraction 28 days after BLM instillation. Treatment with Feitai also significantly ameliorated the BLM-induced lung toxicity effects detected in BALF and lung tissue. The effects in vitro on WI-38 human lung fibroblast cell line showed that Feitai significantly reduced the cell proliferation and transforming growth factor (TGF)-beta stimulated type I collagen synthesis. These results strongly demonstrate that Feitai may be useful in the treatment of pulmonary fibrosis.

Feitai attenuates bleomycin-induced pulmonary fibrosis in rats.

Pulmonary fibrosis is a common consequence of numerous pulmonary diseases. The current therapeutic approaches for this condition are unsatisfactory. Feitai, a composite formula consisting of several herbs, is used in China as a folk remedy for treating patients with pulmonary tuberculosis. In this study, we extensively investigate the effects and mechanisms of Feitai on bleomycin (BLM)-induced pulmonary fibrosis in rats. One hundred and twenty male Sprague-Dawley rats were randomly divided into four groups, referred to as the saline-water, saline-Feitai, BLM-water, and BLM-Feitai groups. Following a single instillation of BLM (5 mg/kg) or saline, rats were orally administered Feitai at a dose of 3 g/kg body weight or sterilized distilled water once daily. Rats were killed at 7, 14, or 28 d post-BLM. Inflammatory cell count, protein concentration, and lactate dehydrogenase activity in bronchoalveolar lavage fluid were measured, and myeloperoxidase activity and lipid peroxide content in lung homogenates were analyzed. Treatment with Feitai inhibited lung fibrotic progression induced by BLM, as indicated by the decrease in lung hydroproline content and lung fibrosis score at 28 d post-BLM. This was accompanied by significant amelioration of BLM-induced body weight loss, lung edema, and inflammatory response during the development of lung injury in the acute phase. The results strongly indicate the beneficial effects of Feitai in protecting against BLM-induced pulmonary fibrosis. Furthermore, the inflammatory response and lipid peroxidation were inhibited by Feitai, suggesting that the effect of this formula on BLM-induced lung injury and fibrosis is associated with antiinflammatory and antioxidant properties.