[The role of caveolin-1 for carbon black nanoparticles uptake in vitro].

OBJECTIVE: To investigate the protein expression of caveolin-1 in type II alveolar epithelial cells (A549) exposed to carbon black nanoparticles (CB NPs) and the role of caveolin in the endocytosis of CB NPs. METHODS: A549 cells were exposed to 0, 25, 50, 100, 200, and 400 µg/ml CB NPs for 24 h; then, trypan blue assay was applied to determine the cell viability. A549 cells were also exposed to 0, 25, 50, and 100 µg/ml CB NPs for 24 h, then, transmission electron microscopy (TEM) and flow cytometry were applied to observe the morphological change of cells and cellular side scatter (SSC), and Western blot was used to analyze the effect of CB NPs on the protein expression of caveolin-1. A549 cells were co-exposed to1 µg/ml filipin and 100 µg/ml CB NPs for 24 h, then, the cellular SSC was observed. RESULTS: Compared with controls, the A549 cells exposed to 200 and 400 µg/ml CB NPs had the cell viability decreased by 38.2% and 46.6%, respectively (P < 0.05), while those exposed to 25, 50, and 100 µg/ml CB NPs showed no significant decrease in cell vitality (P > 0.05). The protein expression of caveolin-1 was significantly higher in the cells exposed to 50 and 100 µg/ml CB NPs than in controls (P < 0.05). The TEM showed that plasmalemmal vesicles containing black particles were found in the cytoplasm of the cells exposed to 50 and 100 µg/ml CB NPs. The flow cytometry showed that the cellular SSC ratio increased from 1.007 to 1.331 as the dose of CB NPs rose within 0 ∼ 100 µg/ml and fell to 1.25 after the cells were co-exposed to1 µg/ml filipin and 100 µg/ml CB NPs. CONCLUSION: Carbon black nanoparticles can be transferred into A549 cells by endocytosis, but caveolin-mediated endocytic pathway plays a minor role in this process.

[Pirfenidone diminishes SiO2 induced lung fibrosis in rats].

OBJECTIVE: to investigate whether pirfenidone (PFD) presents the antifibrotic effect in silicosis of rats. METHODS: SD rats were randomly divided into five groups: the non-treat group, the normal saline group, the normal saline + PFD group, the SiO2 group, the SiO2 + PFD group. Rats except in the non-treat group were intratracheally instilled with SiO2 (25 mg/ml) or normal saline. The rats in normal saline + PFD group and the SiO2 + PFD group were given PFD (50 mg/kg) orally the next day after instillation and throughout the study. Rats were respectively sacrificed 7, 21, 42 days after instillation. The pathology changes were evaluated by Haematoxylin-eosin (HE), Van Gieson and Foot staining, and the hydroxyproline (HYP) content of pulmonary tissue was determined. RESULTS: compared with the SiO2 group, PFD could relieve the fibrotic changes in the lungs of rats. The fibrotic degree in silicotic lesions of lungs was lower in the SiO2 + PFD group than that of SiO2 group. The HYP content in the lungs of the SiO2 + PFD group [(0.75 ± 0.12) mg/g] was significantly lower than that of the SiO2 group [(1.19 ± 0.17) mg/g] at 42 days after instillation (P < 0.05). CONCLUSION: these data support that PFD has an antifibrotic effect against SiO2 induced lung fibrosis in rats, Which appears to be changing collagen accumulation and inhibiting pulmonary fibrosis.