Objective: To construct a recombinant lentiviral vector for mouse miR-204 overexpression, and to verify the targeted regulation of miR-204 and DVL3 in silica (SiO(2)) -induced mouse lung epithelial cells (MLE-12 cells) . Methods: In October 2019, the pre-miR-204 gene was amplified from the mouse genome by the polymerase chain reaction (PCR) method. After sequencing, the amplified product was cloned into the pLenti-CMV-EGFP lentiviral vector. The positive clones were identified by PCR screening and sequencing. The miR-204 overexpressed lentiviral vector was transfected into 293T cells, and lentiviral packaging and titer determination were performed. The experiment was divided into SiO(2) control group, virus control group, and miR-204 virus group, and the expressions of miR-204 and DVL3 gene were detected by real-time PCR. Results: The miR-204 lentiviral expression vector Lv-miR-204-5p was constructed and identified correctly by PCR and sequencing, and a virus dilution with a titer of 9.57×10(8) IU/ml was obtained. The results of real-time PCR showed that the expression of miR-204 in MLE-12 cells of the miR-204 virus group was higher than that of SiO(2) control group and virus control group, and the expression of DVL3 gene was lower than that of SiO(2) control group and virus control group, the differences were statistically significant (P<0.05) . Conclusion: Overexpression of miR-204 by lentiviral vector may inhibit the expression of DVL3 gene in silica-induced mouse lung epithelial cells.
Animals ; Epithelial Cells ; Genetic Vectors ; Lentivirus/metabolism* ; Lung ; Mice ; MicroRNAs/metabolism* ; Silicon Dioxide/toxicity* ; Transfection

Animals ; Lung/metabolism* ; Rats ; Silicon Dioxide/toxicity* ; Thioredoxins/metabolism*

Aged ; Alcohol Drinking ; blood ; Asian Continental Ancestry Group ; Biomarkers ; Dust ; Humans ; Male ; Middle Aged ; Occupational Exposure ; Silicon Dioxide ; toxicity ; Silicosis ; blood ; Smoking ; blood ; Uteroglobin ; blood

Exposure to free silica induces silicosis and myofibroblasts are regarded as primary effector cells. Fibrocytes can differentiate into myofibroblast. Therefore, the present study was designed to investigate whether fibrocytes participate in silicosis. The rat model of silicosis was established. Hematoxylin-eosin stainings and Masson stainings were used to evaluate the histopathology and collagen deposition. Flow cytometry and immunofluorescence were performed to detect the number of fibrocytes and their contribution to myofibroblasts. Results showed that fibrocytes participate in silicosis. Trend analysis of different sources of myofibroblasts during silicosis indicated that fibrocytes and lung type II epithelial cell-derived myofibroblasts play an important role in the early stage of silicosis, while resident lung fibroblast-derived myofibroblasts play a predominant role during the fibrosis formative period.
Animals ; Disease Models, Animal ; Lung ; cytology ; Myofibroblasts ; drug effects ; pathology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Silicon Dioxide ; toxicity ; Silicosis ; etiology ; pathology

OBJECTIVETo investigate the subchronic oral toxicity of silica nanoparticles (NPs) and silica microparticles (MPs) in rats and to compare the difference in toxicity between two particle sizes.

METHODSSprague-Dawley rats were randomly divided into seven groups: the control group; the silica NPs low-, middle-, and high-dose groups; and the silica MPs low-, middle-, and high-dose groups [166.7, 500, and 1,500 mg/(kg•bw•day)]. All rats were gavaged daily for 90 days, and deionized water was administered to the control group. Clinical observations were made daily, and body weights and food consumption were determined weekly. Blood samples were collected on day 91 for measurement of hematology and clinical biochemistry. Animals were euthanized for necropsy, and selected organs were weighed and fixed for histological examination. The tissue distribution of silicon in the blood, liver, kidneys, and testis were determined.

RESULTSThere were no toxicologically significant changes in mortality, clinical signs, body weight, food consumption, necropsy findings, and organ weights. Differences between the silica groups and the control group in some hematological and clinical biochemical values and histopathological findings were not considered treatment related. The tissue distribution of silicon was comparable across all groups.

CONCLUSIONOur study demonstrated that neither silica NPs nor silica MPs induced toxicological effects after subchronic oral exposure in rats.

Administration, Oral ; Animals ; Dose-Response Relationship, Drug ; Female ; Male ; Nanoparticles ; toxicity ; Particle Size ; Rats ; Rats, Sprague-Dawley ; Silicon Dioxide ; toxicity ; Toxicity Tests, Subchronic

OBJECTIVEThe aim of this study was to investigate the effects of SiO2 on fibrocytes and whether fibrocytes participate in silicosis in vivo.

METHODSA macrophagocyte (AM)/fibrocyte coculture system was established, and AMs were treated with 100 μg/mL SiO2. Flow cytometry was used to detect the number of fibrocytes. Real-time PCR was performed to measure the expression of collagen I, collagen III, and α-SMA mRNA. The levels of collagen I, collagen III, and TGF-β1 protein were determined by ELISA. Immunohistochemical staining was performed to measure α-SMA protein expression. A rat silicosis model was induced by intratracheal instillation of SiO2. Lung histopathological evaluation was conducted using HE and Masson's trichrome staining after 1 and 9 weeks. The number of fibrocytes in peripheral blood or lung tissue of rat was detected by flow cytometry. Double-color immunofluorescence was applied to identify fibrocytes in the lung tissue.

RESULTSPeripheral blood monocytes were found to differentiate into fibrocytes in vitro in a time-dependent manner, and exposure to crystalline silica might potentiate fibrocyte differentiation. In addition, fibrocytes were able to migrate from peripheral blood to the lung tissue, and the number of fibrocytes was increased after SiO2 exposure.

CONCLUSIONSilica exposure potentiates fibrocyte differentiation, and fibrocytes may participate in silicosis in vivo.

Animals ; Cell Differentiation ; drug effects ; Collagen ; metabolism ; Fibroblasts ; drug effects ; Lung ; metabolism ; pathology ; Male ; Rats ; Silicon Dioxide ; toxicity ; Silicosis ; metabolism ; pathology

OBJECTIVEWe investigated the role of endoplasmic reticulum stress (ERS) in silica-induced apoptosis in alveolar macrophages in vitro.

METHODSRAW264.7 cells were incubated with 200 μg/mL silica for different time periods. Cell viability was assayed by the MTT assay. Cell apoptosis was evaluated by DAPI staining, flow cytometry analysis, and Western blot analysis of caspase-3. Morphological changes in the endoplasmic reticulum were observed by transmission electron microscopy. The expression of ERS markers binding protein (BiP) and CCAAT-enhancer-binding protein homologous protein (CHOP) was examined by Western blotting and real-time PCR. As an inhibitor of ERS, 4-phenylbutyric acid (4-PBA) was used in the experiments.

RESULTSSilica exposure induced nuclear condensation and caspase-3 expression in RAW264.7 cells. The number of apoptotic cells increased after silica exposure in a time-dependent manner. Silica treatment induced expansion of the endoplasmic reticulum. In addition, the expression of BiP and CHOP increased in silica-stimulated cells. Furthermore, 4-PBA treatment inhibited silica-induced endoplasmic reticulum expansion and the expression of BiP and CHOP. Moreover, 4-PBA treatment attenuated nuclear condensation, reduced apoptotic cells, and downregulated caspase-3 expression in silica-stimulated cells.

CONCLUSIONSilica-induced ERS is involved in the apoptosis of alveolar macrophages.

Animals ; Apoptosis ; drug effects ; Butylamines ; Cell Survival ; drug effects ; Endoplasmic Reticulum Stress ; physiology ; Mice ; RAW 264.7 Cells ; Silicon Dioxide ; toxicity

OBJECTIVEThe effect of the silica nanoparticles (SNs) on lungs injury in rats was investigated to evaluate the toxicity and possible mechanisms for SNs.

METHODSMale Wistar rats were instilled intratracheally with 1 mL of saline containing 6.25, 12.5, and 25.0 mg of SNs or 25.0 mg of microscale SiO2 particles suspensions for 30 d, were then sacrificed. Histopathological and ultrastructural change in lungs, and chemical components in the urine excretions were investigated by light microscope, TEM and EDS. MDA, NO and hydroxyproline (Hyp) in lung homogenates were quantified by spectrophotometry. Contents of TNF-α, TGF-β1, IL-1β, and MMP-2 in lung tissue were determined by immunohistochemistry staining.

RESULTSThere is massive excretion of Si substance in urine. The SNs lead pulmonary lesions of rise in lung/body coefficients, lung inflammation, damaged alveoli, granuloma nodules formation, and collagen metabolized perturbation, and lung tissue damage is milder than those of microscale SiO2 particles. The SNs also cause increase lipid peroxidation and high expression of cytokines.

CONCLUSIONThe SNs result into pulmonary fibrosis by means of increase lipid peroxidation and high expression of cytokines. Milder effect of the SNs on pulmonary fibrosis comparing to microscale SiO2 particles is contributed to its elimination from urine due to their ultrafine particle size.

Air Pollutants ; toxicity ; Animals ; Dose-Response Relationship, Drug ; Lung ; drug effects ; pathology ; ultrastructure ; Male ; Microscopy, Electron, Transmission ; Nanoparticles ; toxicity ; Pulmonary Fibrosis ; chemically induced ; metabolism ; pathology ; Random Allocation ; Rats ; Rats, Wistar ; Silicon Dioxide ; toxicity ; Specific Pathogen-Free Organisms ; Spectrometry, X-Ray Emission ; Urine ; chemistry

Silicosis is one of the most serious occupational diseases in China and dates back to centuries ago. In this study, we successfully established a rat model of silicosis by intratracheal silica injection for 28 days and determined hydroxyproline levels to evaluate collagen metabolism in lung homogenates. Oxidative stress status was evaluated by detecting catalase and glutathione peroxidase activities. Expression levels of peroxiredoxins (Prx I and Prx VI) were detected by Western blotting. Pulmonary surfactant protein A (SP-A) levels in rat serum and lung tissue were analyzed by ELISA, and SP-A and Prx expression levels in lung tissues were detected by immunohistochemistry. The results suggest that Prx proteins may be involved in pulmonary fibrosis induced by silica. Downregulation of SP-A expression caused due to silica is an important factor in the occurrence and development of silicosis.
Animals ; Disease Models, Animal ; Humans ; Lung ; enzymology ; metabolism ; Male ; Oxidative Stress ; Peroxiredoxin VI ; genetics ; metabolism ; Peroxiredoxins ; genetics ; metabolism ; Pulmonary Surfactant-Associated Protein A ; genetics ; metabolism ; Rats ; Silicon Dioxide ; toxicity ; Silicosis ; genetics ; metabolism

OBJECTIVETo compare the effects of oral treatment with tetrandrine (TD) and N-acetylcys-teine (NAC) separately or jointly on silica-exposed rats.

METHODS40 sprague-Dawly (SD) rats were randomly divided into normal saline group, quartz group, TD treatment group (50 mg/kg), NAC treatment group (500 mg/kg) and combined treatment group (TD: 50 mg/kg + NAC: 500 mg/kg). Rats in normal saline group and other groups received intratracheal instillation of normal saline and quartz dust suspension respectively. Treatment groups were given TD, NAC separately or jointly via esophagus the next day after instillation, once a day and six times a week for 30 consecutive days. At the end of experiment, the pathological changes of lung tissues were evaluated by the methods of Foot, HE and Masson staining, the level of hydroxyproline (HYP), malondjalde-hyde (MDA), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in lung tissues were measured by alkaline hydrolysis method, the barbituric acid method and enzyme-linked immunosorbent assay (ELISA) respectively.

RESULTSCompared with the quartz group, lymph nodes/body coefficients in all treatment groups and lung/body coefficient in combined treatment group were significantly decreased (P < 0.05). Pathology results showed that the normal saline group demonstrated no obvious evidence of lung damage. The quartz group lungs silicotic lesions focused on II~III level, the TD treatment group was mainly with I level, the NAC treatment group was mainly with I~II level, and the combined treatment group only showed little silicotic nodule, no obvious fibrosis. HYP content in TD treatment group and combined treatment group were significantly lower than that in the quartz group (P < 0.05), while it showed no obvious change in NAC treatment group. MDA content in lung tissues of each treatment group (TD treatment group, NAC treatment group and combined treatment group) were 18.80 ± 2.94, 20.13 ± 4.01 and 17.05 ± 3.52 nmol/ml respectively, which lower than in the quartz group (23.99 ± 3.26 nmol/ml). The level of IL-6 in lung tissues of the quartz group were 89.57 ± 8.78 pg/ml. After TD and NAC monotherapy, the IL-6 content decreased to 79.22 ± 9.65 pg/ml and 81.63 ± 5.72 pg/ml, and it decreased more significantly after combined medication (74.37 ± 3.17 pg/ml). The level of TNF-α in the quartz group were 59.05 ± 4.48 pg/ml. After TD and NAC monotherapy, the TNF-α content decreased to 50.48 ± 2.76 pg/ml and 54.28 ± 4.30 pg/ml, and it decreased more significantly after combined medication (49.10 ± 4.98 pg/ml).

CONCLUSIONNAC and TD could reduce MDA, TNF-α and IL-6 levels in lung tissue, and alleviate SiO2-induced pulmonary fibrosis in rats. Combined treatment with TD and NAC was more effective than TD or NAC treatment separately.

Acetylcysteine ; pharmacology ; Animals ; Benzylisoquinolines ; pharmacology ; Disease Models, Animal ; Dust ; Hydroxyproline ; metabolism ; Interleukin-6 ; metabolism ; Lung ; pathology ; Malondialdehyde ; metabolism ; Pulmonary Fibrosis ; chemically induced ; drug therapy ; Quartz ; toxicity ; Rats ; Rats, Wistar ; Silicon Dioxide ; toxicity ; Silicosis ; drug therapy ; Tumor Necrosis Factor-alpha ; metabolism