Mitochondrial folate pathway regulates myofibroblast differentiation and silica-induced pulmonary fibrosis.

BACKGROUND: Silica-induced pulmonary fibrosis (silicosis) is a diffuse interstitial fibrotic disease characterized by the massive deposition of extracellular matrix in lung tissue. Fibroblast to myofibroblast differentiation is crucial for the disease progression. Inhibiting myofibroblast differentiation may be an effective way for pulmonary fibrosis treatment. METHODS: The experiments were conducted in TGF-ß treated human lung fibroblasts to induce myofibroblast differentiation in vitro and silica treated mice to induce pulmonary fibrosis in vivo. RESULTS: By quantitative mass spectrometry, we revealed that proteins involved in mitochondrial folate metabolism were specifically upregulated during myofibroblast differentiation following TGF-ß stimulation. The expression level of proteins in mitochondrial folate pathway, MTHFD2 and SLC25A32, negatively regulated myofibroblast differentiation. Moreover, plasma folate concentration was significantly reduced in patients and mice with silicosis. Folate supplementation elevated the expression of MTHFD2 and SLC25A32, alleviated oxidative stress and effectively suppressed myofibroblast differentiation and silica-induced pulmonary fibrosis in mice. CONCLUSION: Our study suggests that mitochondrial folate pathway regulates myofibroblast differentiation and could serve as a potential target for ameliorating silica-induced pulmonary fibrosis.

Yangqing Chenfei formula attenuates silica-induced pulmonary fibrosis by suppressing activation of fibroblast via regulating PI3K/AKT, JAK/STAT, and Wnt signaling pathway.

BACKGROUND: Yangqing Chenfei formula (YCF) has been demonstrated its clinical efficiency on silicosis patients. However, the effect of YCF against silicotic fibrosis and its mechanism remain unclear. PURPOSE: This study is aimed to investigate active compounds and molecular mechanism of YCF in treating silicosis. METHOD: YCF was orally administrated to silicosis rats induced by crystalline silica. The effective fraction of YCF and the compounds was isolated and identified by using macroporous resin and HPLC-MS, respectively. The targets and potential molecular mechanism of YCF against silicotic fibrosis were investigated through pharmacological network and RNA-sequencing analysis and in vitro-experimental validation. RESULTS: YCF could remarkably improve the lung function and pathological changes of silicotic rats, reduce the aggregation of fibrocytes and deposition of ECM, such as collagen I, III, FN, and α-SMA, and suppress the TGF-ß/Smad3 signaling. Furthermore, YCF6, the effective fraction derived from YCF, could significantly inhibit fibroblast activation induced by TGF-ß. Then, 135 compounds were identified from YCF6 by using HPLC-MS, and Network pharmacology analysis predicted total 941 targets for these compounds. Moreover, 409 differentially expressed genes of fibroblast activation induced by TGF-ß were identified. Then, integrated analysis of the 941 targets with 409 differentially expressed genes showed that YCF6 contains multiple compounds, such as tangeretin, L-Malic acid, 2-Monolinolein etc., which inhibits fibroblast activation probably by targeting different proteins, such as PIK3CA, AKT1, JAK2, STAT3, GSK3ß, leading to regulate the signal network, such as PI3K/AKT signaling pathway, JAK/STAT signaling pathway, and Wnt signaling pathway. Finally, in vitro experiment indicated that tangeretin, the active compound contained in YCF6, could significantly inhibit TGF-ß induced fibroblast activation. Moreover, YCF6 and tangeretin could markedly inhibit the activation of PI3K/AKT, JAK/STAT, and Wnt pathway. CONCLUSION: YCF contained multiple compounds and targeted various proteins that regulated the fibroblast activation, which might be the molecular mechanisms of it in treating silicosis.

Protective effects of intranasal curcumin on silica-induced lung damage.

OBJECTIVE: Being anti-inflammatory and an antioxidant in nature, curcumin has been studied for its anti-asthmatic effects, but its impact on silicosis has not been investigated before. It is a form of occupational lung illness caused by inhaling crystalline silica. It is particularly common among those who work in construction-related sectors. Therefore, present study has been undertaken to investigate impact of intranasal curcumin on silica induced lung damage in mice model of silicosis. MATERIALS AND METHODS: Mice model of silicosis was developed by intranasal silica instillation (2.5 mg/mice) for different durations mainly 7, 14 and 21 days, where the longest duration of silica exposure (21 days) mimics chronic occupational exposure of silica dust leading to silicosis. Curcumin (5 mg/kg,i.n) and /or dexamethasone, a known corticosteroid (10 mg/kg,i.p) was administered an hour prior to silica administration. RESULTS: Present study revealed silica induced lung damage in the mice model of silicosis characterized by airway inflammation, collagen deposition and enhanced expression of fibrosis markers (MMP-9, α-SMA, Hydroxyproline), which were significantly reduced in curcumin treatment groups. Inhibitory effects of curcumin were compared with standard drug, dexamethasone, a corticosteroid and was found better in protecting structural alterations in the lung. Damaged and abnormal mitochondria (enlarged and irregular shapes) were observed in silicosis group which were reduced in curcumin and dexamethasone treatment groups as revealed in transmission electron microscopic studies. CONCLUSIONS: Present study shows protective effects of intranasal curcumin on silica-induced airway inflammation and structural changes thereby lung damage. Hence, it can be considered as an alternative and complementary medication for silicosis.

[Interventional effect of asiaticosdide on rats exposed to silica dust].

Objective: To investigate the effect of asiaticoside for fibrosis in lung tissues of rats exposed to silica and to explore its possible mechanism. Methods: 144 SD male rats were randomly divided into control group, model group, positive drug control group, asiaticoside high-dose group, medium-dose group and low-dose group, each group included 24 rats. Rats in the control group were perfused with 1.0 ml of normal saline, and the other groups were given 1.0 ml 50 mg/ml SiO(2) suspension. Gavage of herbal was given from the next day after model establishment, once a day. Rats in the positive drug control group were administration with 30 mg/kg tetrandrine and rats in the low-dose group, medium-dose group and high-dose group were given 20 mg/kg, 40 mg/kg and 60 mg/kg asiaticoside for fibrosis respectively. Rats in the control group and the model group were given 0.9% normal saline. The rats were sacrificed in on the 14th, 28th and 56th day after intragastric administration and collect the lung tissues to detect the content of hydroxyproline, TGF-ß(1) and IL-18, observe the pathological changes of the lung tissues by HE and Masson staining and determine the expressions of Col-I, a-SMA, TGF-ß in lung tissues by Western Blot. Results: On the 14th day, 28th day and 56th day after model establishment, the lung tissues of rats in the model group showed obvious inflammatory response and accumulation of collagen fibers, and the degree of inflammation and fibrosis increased with time. The intervention of asiaticoside could effectively inhibit the pathological changes of lung tissues. The contents of hydroxyproline, IL-18 and TGF-ß1 in lung tissues of model group were higher than those in the control group (P<0.05) , while the level of hydroxyproline, IL-18 and TGF-ß1 in asiaticoside groups were significantly decreased, and the difference was statistically signicant (P<0.05) . Compared with the control group, the expression levels of Col-I, TGF-ß1and α-SMA in lung tissue of model group were increased (P<0.05) , while the expression level of Col-I, TGF-ß1 and α-SMA were decreased after the intervention of asiaticoside, and the difference was statistically signicant (P<0.05) . Conclusion: Asiaticoside can inhibit the increase of Col-I, TGF-ß1 and α-SMA content in the SiO(2)-induced lung tissues of rats, reduce the release of TGF-ß1 and IL-18 inflammatory factors in lung tissue, and then inhibit the synthesis and deposition of extracellular matrix in rat lung tissue, and improve silicosis fibrosis.

Exploration study on serum metabolic profiles of Chinese male patients with artificial stone silicosis, silicosis, and coal worker's pneumoconiosis.

Long-term exposure to inhaled silica dust induces pneumoconiosis, which remains a heavy burden in developing countries. Modern industry provides new resources of occupational SiO2 leading to artificial stone silicosis especially in developed countries. This study aimed to characterize the serum metabolic profile of pneumoconiosis and artificial stone silicosis patients. Our case-control study recruited 46 pairs of pneumoconiosis patients and dust-exposed workers. Nontargeted metabolomics and lipidomics by ultra-high-performance liquid chromatography-tandem mass spectrometry platform were conducted to characterize serum metabolic profile in propensity score-matched (PSM) pilot study. 54 differential metabolites were screened, 24 of which showed good screening efficiency through receiver operating characteristics (ROC) in pilot study and validation study (both AUC > 0.75). 4 of the 24 metabolites can predict pneumoconiosis stages, which are 1,2-dioctanoylthiophosphatidylcholine, phosphatidylcholine(O-18:1/20:1), indole-3-acetamide and l-homoarginine. Kynurenine, N-tetradecanoylsphingosine 1-phosphate, 5-methoxytryptophol and phosphatidylethanolamine(22:6/18:1) displayed the potential as specific biomarkers for artificial stone silicosis. Taken together, our results confirmed that tryptophan metabolism is closely related to pneumoconiosis and may be related to disease progression. Hopefully, our results could supplement the biomarkers of pneumoconiosis and provide evidence for the discovery of artificial stone silicosis-specific biomarkers.

Interventional effect of asiaticosdide on rats exposed to silica dust / 中华劳动卫生职业病杂志

Objective: To investigate the effect of asiaticoside for fibrosis in lung tissues of rats exposed to silica and to explore its possible mechanism. Methods: 144 SD male rats were randomly divided into control group, model group, positive drug control group, asiaticoside high-dose group, medium-dose group and low-dose group, each group included 24 rats. Rats in the control group were perfused with 1.0 ml of normal saline, and the other groups were given 1.0 ml 50 mg/ml SiO(2) suspension. Gavage of herbal was given from the next day after model establishment, once a day. Rats in the positive drug control group were administration with 30 mg/kg tetrandrine and rats in the low-dose group, medium-dose group and high-dose group were given 20 mg/kg, 40 mg/kg and 60 mg/kg asiaticoside for fibrosis respectively. Rats in the control group and the model group were given 0.9% normal saline. The rats were sacrificed in on the 14th, 28th and 56th day after intragastric administration and collect the lung tissues to detect the content of hydroxyproline, TGF-β(1) and IL-18, observe the pathological changes of the lung tissues by HE and Masson staining and determine the expressions of Col-I, a-SMA, TGF-β in lung tissues by Western Blot. Results: On the 14th day, 28th day and 56th day after model establishment, the lung tissues of rats in the model group showed obvious inflammatory response and accumulation of collagen fibers, and the degree of inflammation and fibrosis increased with time. The intervention of asiaticoside could effectively inhibit the pathological changes of lung tissues. The contents of hydroxyproline, IL-18 and TGF-β1 in lung tissues of model group were higher than those in the control group (P<0.05) , while the level of hydroxyproline, IL-18 and TGF-β1 in asiaticoside groups were significantly decreased, and the difference was statistically signicant (P<0.05) . Compared with the control group, the expression levels of Col-I, TGF-β1and α-SMA in lung tissue of model group were increased (P<0.05) , while the expression level of Col-I, TGF-β1 and α-SMA were decreased after the intervention of asiaticoside, and the difference was statistically signicant (P<0.05) . Conclusion: Asiaticoside can inhibit the increase of Col-I, TGF-β1 and α-SMA content in the SiO(2)-induced lung tissues of rats, reduce the release of TGF-β1 and IL-18 inflammatory factors in lung tissue, and then inhibit the synthesis and deposition of extracellular matrix in rat lung tissue, and improve silicosis fibrosis.

Alpha-lipoic acid attenuates silica-induced pulmonary fibrosis by improving mitochondrial function via AMPK/PGC1α pathway activation in C57BL/6J mice.

Silicosis is characterized by pulmonary interstitial fibrosis that arises as a result of chronic exposure to silica. The few available treatments only delay its progression. As α-lipoic acid (ALA) has been shown to have various beneficial effects, including mitoprotective, antioxidant, and anti-inflammatory effects, we hypothesized that it may exhibit therapeutic effects in pulmonary fibrosis. Therefore, in the present study, we used a murine model of silicosis to investigate whether supplementation with exogenous ALA could attenuate silica-induced pulmonary fibrosis by improving mitochondrial function. ALA was administered to the model mice via continuous intragastric administration for 28 days, and then the antioxidant and mitoprotective effects of ALA were evaluated. The results showed that ALA decreased the production of reactive oxygen species, protected mitochondria from silica-induced dysfunction, and inhibited extracellular matrix deposition. ALA also decreased hyperglycemia and hyperlipidemia. Activation of the mitochondrial AMPK/PGC1α pathway might be responsible for these ALA-mediated anti-fibrotic effects. Exogenous ALA blocked oxidative stress by activating NRF2. Taken together, these findings demonstrate that exogenous ALA effectively prevents the progression of silicosis in a murine model, likely by stimulating mitochondrial biogenesis and endogenous antioxidant responses. Therefore, ALA can potentially delay the progression of silica-induced pulmonary fibrosis.

Herbal compounds in the treatment of pulmonary silicosis.

Herbal compounds including those already well-established in traditional Chinese medicine have been increasingly tested in the treatment of various diseases. Recent studies have shown that herbal compounds can be of benefit also for pulmonary silicosis as they can diminish changes associated with silica-induced inflammation, fibrosis, and oxidative stress. Due to a lack of effective therapeutic strategies, development of novel approaches which may be introduced particularly in the early stage of the disease, is urgently needed. This review summarizes positive effects of several alternative plant-based drugs in the models of experimental silicosis with a potential for subsequent clinical investigation and use in future.

Sodium tanshinone IIA sulfonate attenuates silica-induced pulmonary fibrosis in rats via activation of the Nrf2 and thioredoxin system.

Silicosis is characterized by pulmonary fibrosis due to long-term inhalation of silica particles. Although the cause of this serious disease is known, its pathogenesis remains unclear and there are currently no specific treatments. Recent studies have shown that the anti-oxidant transcription factor Nrf2 is expressed at reduced levels in fibrotic foci, which may be related to disease progression. However, the molecular mechanisms by which this might occur have yet to be elucidated. Sodium tanshinone IIA sulfonate (STS), an extract of Salvia miltiorrhiza, is used in traditional Chinese medicine in the treatment of coronary heart disease. STS has been shown to play a strong anti-oxidative role in various organs. Here, we employed a rat model to explore the effects of STS on oxidative stress and the progression of fibrosis in silicosis. STS significantly reduced collagen deposition in the lungs, thereby antagonising silicosis. Immunohistochemical and immunofluorescence staining showed that Nrf2 was differentially expressed in lung cells during silica induced fibrosis, and chromatin immunoprecipitation-sequencing experiments demonstrated that Nrf2 promoted the expression of the antioxidant proteins thioredoxin and thioredoxin reductase. Our results suggest that the anti-fibrotic effects of STS may be related to upregulation of Nrf2 nuclear expression, especially in fibrotic lesions, and the promotion of thioredoxin and thioredoxin reductase expression. Our findings may open up new avenues for the development of STS as a treatment for silicosis.

Earthworm extract attenuates silica-induced pulmonary fibrosis through Nrf2-dependent mechanisms.

Silicosis is an occupational pulmonary fibrosis caused by inhalation of silica (SiO2) and there are no ideal drugs to treat this disease. Earthworm extract (EE), a natural nutrient, has been reported to have anti-inflammatory, antioxidant, and anti-apoptosis effects. The purpose of the current study was to test the protective effects of EE against SiO2-induced pulmonary fibrosis and to explore the underlying mechanisms using both in vivo and in vitro models. We found that treatment with EE significantly reduced lung inflammation and fibrosis and improved lung structure and function in SiO2-instilled mice. Further mechanistic investigations revealed that EE administration markedly inhibited SiO2-induced oxidative stress, mitochondrial apoptotic pathway, and epithelial-mesenchymal transition in HBE and A549 cells. Furthermore, we demonstrate that Nrf2 activation partly mediates the interventional effects of EE against SiO2-induced pulmonary fibrosis. Our study has identified EE to be a potential anti-oxidative, anti-inflammatory, and anti-fibrotic drug for silicosis.

Ginsenoside Rg1 enhances lymphatic transport of intrapulmonary silica via VEGF-C/VEGFR-3 signaling in silicotic rats.

Ginsenoside Rg1, extracted mainly from Panax ginseng, has been shown to exert strong pro-angiogenic activities in vivo. But it is unclear whether ginsenoside Rg1 could promote lung lymphangiogenesis to improve lymphatic transport of intrapulmonary silica in silicotic rats. Here we investigated the effect of ginsenoside Rg1 on lymphatic transport of silica during experimental silicosis, and found that ginsenoside Rg1 treatment significantly raised the silicon content in tracheobronchial lymph nodes and serum to reduce the silicon level in lung interstitium, meanwhile increased pulmonary lymphatic vessel density by enhancing the protein and mRNA expressions of vascular endothelial growth factor-C (VEGF-C) and vascular endothelial growth factor receptor-3 (VEGFR-3). The stimulative effect of ginsenoside Rg1 on lymphatic transport of silica was actively correlated with its pro-lymphangiogenic identity. And VEGFR-3 inhibitor SAR131675 blocked these above effects of ginsenoside Rg1. These findings suggest that ginsenoside Rg1 exhibits good protective effect against lung burden of silica during experimental silicosis through improving lymphatic transport of intrapulmonary silica, which is potentially associated with the activation of VEGF-C/VEGFR-3 signaling pathway.

[High Expression of co-stimulatory molecule CD40 in silicosis patients and intervention effect of yiqi huoxue decoction].

OBJECTIVE: To study whether co-stimulatory molecule CD40 of alveolar macrophage (AM) participated in the occurrence and development of silicosis, and to explore the intervention of Yiqi Huoxue Decoction (YHD) in the fibrosis of silicosis patients. METHODS: Totally 46 silicosis inpatients and outpatients were recruited and randomly assigned to the Western treatment group (A) and the Chinese medicine (CM) treatment group (B), 23 in each group. Patients in Group A received routine symptomatic treatment such as anti-inflammation, phlegm resolving, anti-spasm, and asthma relief, and so on. Patients in Group B additionally took YHD, one dose daily for 14 successive days. Besides, another 18 patients with chronic cough and sense of laryngeal foreign bodies were recruited as the normal control group, who had no obvious lesion confirmed by bronchofi6roscope and clinical diagnosis of the lung. They were treated by symptomatic supporting treatment. The alveolar lavage fluid was collected from all patients and isolated, and AM cells were cultured. The level of CD40 mRNA was detected by RT-PCR. The expression of CD40 protein was detected by Western blot. RESULTS: Compared with the normal control group, expression levels of CD40 mRNA and CD40 protein significantly increased in Group A (P < 0.01). Compared with Group A, expression levels of CD40 mRNA and CD40 protein significantly decreased in Group B (P < 0.01). CONCLUSIONS: Highly expressed co-stimulatory molecule CD40 of AM might participate in pulmonary fibrosis. YHD could hinder its roles, inhibit the progression of fibrosis, thereby playing an interventional role of treatment.

Tamoxifen citrate: a glimmer of hope for silicosis.

BACKGROUND: Inhalation of crystalline silica nanoparticles causes pulmonary damage resulting in progressive lung fibrosis. Currently, there is no effective treatment for silicosis. Tamoxifen citrate is a selective estrogen receptor modulator, which is one of the adjuvant treatment choices for breast cancer. It is also known with its inhibitory effect on the production of transforming growth factor-beta (TGF-ß) and studied for the anti-fibrotic effect in some fibrotic diseases. The aim of the study was to determine the effect of tamoxifen citrate on the prevention of pulmonary fibrosis and the treatment of silicosis. METHODS: A total of 100 adult female Wistar Albino rats (200-250 g) were used in this study. The rats were divided into five groups including 20 rats in each. Rats were exposed to silica for 84 d in all groups. In group 1, rats were sacrificed on the day 84 without receiving treatment. In group 2, rats received 1 mg/kg tamoxifen (tmx1 + 1), from the first day of the study for the whole 114 d of the study. In group 3, (tmx10 + 10) rats were given 10 mg/kg tamoxifen from the first day of the study for the whole 114 d of the study. In group 4 (tmx1), rats were started 1 mg/kg of tamoxifen on day 84 and were given until day 114. In group 5 (tmx10), rats were fed with 10 mg/kg tamoxifen starting from day 84 to day 114. All rats except group 1 were sacrificed on 114 day of the study. Lung inflammation and fibrosis scores, serum TGF ß levels, lung smooth muscle antigen and tissue transforming growth factor ß (t-TGF-ß) antibody staining levels, and number of silicotic rats were compared between groups. RESULTS: Silicosis was caused successfully in all rats in group 1. There were six silicotic rats in group 3 and it was the lowest number of all groups. Plasma TGF-ß levels and fibrosis score were significantly lower in all groups when compared with the control group. Tamoxifen could have preventive or treating effects in silicosis and found that lung fibrosis score was significantly lower in rats treated with tamoxifen. CONCLUSIONS: Tamoxifen treatment after and/or before induction of silicosis decreased lung fibrosis score with blood TGF-ß levels. We hope that this study may introduce a new indication as prophylactic use of tamoxifen in high-risk groups for silicosis and for treatment of silicosis.

[Changes of cell factor in bronchoalveolar lavage fluid in rats exposed to silica].

OBJECTIVE: To investigate the changes in the levels of inflammatory cytokines in bronchoalveolar lavage fluid (BALF) in rats exposed to silica dust. METHODS: Experimental rats were randomly divided into control group and three experimental groups (doses of dust: 15, 30, and 60 mg/ml), with 42 rats in each group. Each rat in the control group was treated with 1 ml of normal saline by intratracheal instillation, while each rat in the experimental groups was exposed to 1 ml of silica suspension by a single intratracheal instillation. Seven rats in each group were killed at 1, 3, 7, 14, 21, and 28 days after exposure, and then BALF was collected. Enzyme-linked immunosorbent assay was used to measure the levels of interleukin (IL)-1, IL-6, IL-16, macrophage inflammatory protein-1 alpha (MIP-1α), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), and transforming growth factor-ß (TGF-ß). RESULTS: The levels of cytokines in each experimental group were higher than those in the control group at any time point. In the early stage of exposure (day 1-3), BALF IL-1 level increased significantly with the increase in dust dose, and on day 14, BALF IL-6 and IL-16 levels increased significantly with the increase in dust dose; the levels of IL-1, IL-6, and IL-16 in the experimental groups reached the peak on day 14. There were significant differences in the levels of MIP-1α and MCP-1 between the experimental groups (FMIP-1α = 30.106, P<0.01; FMCP-1 = 17.193, P<0.01). In each group, the level of MCP-1 varied significantly at different time points (F = 0.618, P>0.05). On day 1-14, BALF TNF-α level increased with the increase in dust dose, with a significant dose-response relationship (P < 0.05). In each experimental group, TNF-α level reached the peak on day 14. On days 14, 21, and 28, the high-dose group had significantly higher BALF TGF-ß levels than the low-dose group (P<0.05); on days 14 and 28, the high-dose group had significantly higher BALF TGF-ß levels than the middle-dose group (P<0.05). CONCLUSION: IL-1, IL-6, IL-16, MIP-1α, MCP-1, and TNF-α play a role in the development and progression of silicosis inflammation. TGF-ß may be related to (related to; associated with; correlated with) fibrosis.

[Therapeutic efficacy of Jinshuibao capsules in treatment of silicosis].

OBJECTIVE: To investigate the therapeutic efficacy of Jinshuibao capsules in the treatment of silicosis. METHODS: A total of 270 patients with silicosis were randomly divided into treatment group (n = 141) and control group (n = 129). Both groups received conventional therapy. Additionally, the patients in the treatment group took 3 Jinshuibao capsules three times day for 2-3 courses of treatment (each course = 6 weeks). The therapeutic efficacy and the changes in tumor necrosis factor-α (TNF-α) and transforming growth factor-ß(1) (TGF-ß(1)) levels were observed after treatment. RESULTS: After treatment, cough, expectoration, chest pain, shortness of breath, and other respiratory symptoms were relieved significantly (P < 0.05). The treatment group showed significantly lower TNF-α and TGF-ß(1) levels than before treatment and the control group (P < 0.05) and significantly higher forced vital capacity, forced expiratory volume in one second, and maximum mid-expiratory flow than before treatment and the control group (P < 0.05). CONCLUSION: Jinshuibao capsules can decrease inflammatory response, increase vital capacity and maximum voluntary ventilation, reduce airflow limitation, and improve quality of life and thus have good therapeutic efficacy in the treatment of silicosis.

[Effects of Gymnadenia conopse alcohol extract on early protein profiles in lung tissue of rats exposed to silica].

OBJECTIVE: To analyze the early expression differences of lung tissue proteins in rats exposed to silica using comparative proteomics method, to explore the effects of Chinese traditional medicine (Gymnadenia conopse alcohol extract, GcAE) on silicosis (50 mg/ml). METHODS: Adult male Wistar rats were randomly divided into silica-treated group and GcAE-treated group, four rats a group. The rats were exposed to silica by intratracheal (IT) instillation of 1 ml silica suspension for 24 h. After exposure, the rats in GcAE-treated group were intragastric administration with 0.8 ml GcAE (0.8 ml/100 g a day) and the rats in silica-treated group were intragastric administration with 2 ml sterilized saline a day for 14 days. Then all rats were sacrificed and lung tissues were collected. The total proteins were separated by means of two-dimensional gel electrophoresis (2-DE) and the differentially expressed proteins were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Western blotting was used to validate the expression of certain candidate proteins in lung tissues. RESULTS: Obvious pathological changes of lung could be observed in silica-treated group, such as the thicken of interalveolar septum, which was infiltrated with lymphocytes, macrophages and a few neutrophils with the proliferation of fibroblasts and smooth muscle cells. The accumulation of collagen, the destruction of alveolus structure and the more dotted fibrosis or granuloma could also be found. However, the pathological changes of lung in GcAE-treated group were lighter than those of silica-treated group. Thirty three differentially expressed proteins were identified, including cathepsin D precursor, peroxiredoxin-1 (Prx-1) and SEC14-like protein 3. Compared with silica-treated group, cathepsin D precursor and Prx-1 were significantly downregulated in GcAE-treated group, and SEC14-like protein 3 was significantly upregulated (P < 0.01). The results of western blot indicated that the expression level of Prx-1 in GcAE-treated group was 0.26 ± 0.02, which was significantly lower than that (0.35 ± 0.04) in silica-treated group (P < 0.01). CONCLUSION: GcAE may inhibit the progress of silicosis in the early period and cathepsin D precursor, SEC14-like protein 3 and Prx-1 may participate in this process.

Fibrogenic and redox-related but not proinflammatory genes are upregulated in Lewis rat model of chronic silicosis.

Silicosis, a fibrotic granulomatous lung disease, may occur through accidental high-dose or occupational inhalation of silica, leading to acute/accelerated and chronic silicosis, respectively. While chronic silicosis has a long asymptomatic latency, lung inflammation and apoptosis are hallmarks of acute silicosis. In animal models, histiocytic granulomas develop within days after high-dose intratracheal (IT) silica instillation. However, following chronic inhalation of occupationally relevant doses of silica, discrete granulomas resembling human silicosis arise months after the final exposure without significant lung inflammation/apoptosis. To identify molecular events associated with chronic silicosis, lung RNA samples from controls or subchronic silica-exposed rats were analyzed by Affymetrix at 28 wk after silica exposures. Results suggested a significant upregulation of 144 genes and downregulation of 7 genes. The upregulated genes included complement cascade, chemokines/chemokine receptors, G-protein signaling components, metalloproteases, and genes associated with oxidative stress. To examine the kinetics of gene expression relevant to silicosis, quantitative polymerase chain reaction (qPCR), enzyme-linked immunosorbent assay (ELISA), Luminex-bead assays, Western blotting, and/or zymography were performed on lung tissues from 4 d, 28 wk, and intermediate times after subchronic silica exposure and compared with 14-d acute silicosis samples. Results indicated that genes regulating fibrosis (secreted phosphoprotein-1, Ccl2, and Ccl7), redox enzymes (superoxide dismutase-2 and arginase-1), and the enzymatic activities of matrix metalloproteinases 2 and 9 were upregulated in acute and chronic silicosis models. However, proinflammatory cytokines were strongly upregulated only in acute silicosis. Thus, inflammatory cytokines are associated with acute but not chronic silicosis. Data suggest that genes regulating fibrosis, oxidative stress, and metalloproteases may contribute to both acute and chronic silicosis.

Granuloma formation induced by low-dose chronic silica inhalation is associated with an anti-apoptotic response in Lewis rats.

Chronic human silicosis results primarily from continued occupational exposure to silica and exhibits a long asymptomatic latency. Similarly, continued exposure of Lewis rats to low doses of silica is known to cause delayed granuloma formation with limited lung inflammation and injury. On the other hand, intratracheal exposure to large doses of silica induces acute silicosis characterized by granuloma-like formations in the lung associated with apoptosis, severe alveolitis, and alveolar lipoproteinosis. To ascertain similarities/differences between acute and chronic silicosis, in this communication, we compared cellular and molecular changes in established rat models of acute and chronic silicosis. In Lewis rats, acute silicosis was induced by intratracheal instillation of 35 mg silica, and chronic silicosis through inhalation of aerosolized silica (6.2 mg/m(3), 5 d/wk for 6 wk). Animals exposed to acute high-dose silica were sacrificed at 14 d after silica instillation while chronically silica-treated animals were sacrificed between 4 d and 28 wk after silica exposure. The lung granulomas formation in acute silicosis was associated with strong inflammation, presence of TUNEL-positive cells, and increases in caspase-3 activity and other molecular markers of apoptosis. On the other hand, lungs from chronically silica-exposed animals exhibited limited inflammation and increased expression of anti-apoptotic markers, including dramatic increases in Bcl-2 and procaspase-3, and lower caspase-3 activity. Moreover, chronic silicotic lungs were TUNEL-negative and overexpressed Bcl-3 and NF-kappaB-p50 but not NF-kappaB-p65 subunits. These results suggest that, unlike acute silicosis, chronic exposures to occupationally relevant doses of silica cause significantly lower lung inflammation and elevated expression of anti-apoptotic rather than proapoptotic markers in the lung that might result from interaction between NF-kappaB-p50 and Bcl-3.

[The anti-fibrotic effects of Qidan granule in experimental silicosis].

OBJECTIVE: To investigate the anti-fibrotic effects of Qidan granule in rats. METHODS: The rats were randomly divided into six experimental groups: normal group, model group, Qidan group, Tetrandrine group. All rats except normal group were treated with silicon dioxide (50 mg/rat) by intratracheal instillation to induce silicosis. Qidan group and Tetrandrine group were treated with Qidan granule (3125 mg/kg) or treated with Tetrandrine (22 mg/kg) respectively. All the rats were sacrificed after 5 months. Calculate Lung/body coefficient by weighting the lung wet weight and the body weight of rats. Content of Hydroxyproline was measured by alkaline hydrolysis. The gene expression of transforming growth factor-beta1 was examined by using enzyme-linked immunosorbent assay (ELISA). Paraffin embedded lung sections with HE staining, VG staining and Gomori staining were observed under light microscope. RESULTS: In Qidan group and Tetrandrine group, Lung/body coefficient and content of Hydroxyproline and expression of transforming growth factor-beta1 were lower as compared with model group (P < 0.05). Model group mainly showed III approximately IV grade silicotic nodule, which contained thick collagen and sparse reticulum fibe; Qidan group and Tetrandrine group appeared with II grade silicotic nodule, which contained tiny collagen and intensive reticulum fibe. Tetrandrine group showed injury of kidney, and others were normal. CONCLUSION: Qidan granule extract should prevent and from inhibit the remarkably silicotic fibrosis in rats.

[Effect of Chinese herbal drugs and tetrandrine on TGF-beta1 signaling pathway].

OBJECTIVE: To investigate the molecule mechanism of the anti-fibrotic effects of Chinese herbal drugs (Qidan granules) in rats. METHODS: The male rats were randomly divided into four experimental groups: normal group, model group, Qidan group, tetrandrine group. Every group had 10 rats. Normal group were treated with physiologic saline while others were treated with silicon dioxide (50 mg/rat) by intratracheal instillation to induce silicosis. On 30th day Qidan group and Tetrandrine group were treated with Qidan granules (3125 mg/kg) or treated with tetrandrine (22 mg/kg) respectively. All the rats were scarified after 5 months. Lung/body coefficient was measured. Content of hydroxyproline was measured by alkaline hydrolysis. The gene expression of transforming growth factor-beta1 in bronchoalveolar lavage fluid was examined by using enzyme-linked immunosorbent assay (ELISA). The gene expressions of transforming growth factor-beta1, transcription factor Smad 3 and Smad 7 in lung were analyzed by using immunohistochemical technique (SP) and the image analysis. RESULTS: Model group mainly had Grade III approximately IV silicotic nodule while Qidan group and tetrandrine group had Grade II silicotic nodule. In Qidan group and tetrandrine group, lung/body coefficient and content of hydroxyproline and expression of transforming growth factor-beta1 and Smad3 in lung and expression of transforming growth factor-beta1 in bronchoalveolar lavage fluid were lower than those in model group (P < 0.05). Expression of Smad 7 in lung was higher than model group (P < 0.05). Injury of kidney occurred in tetrandrine group. CONCLUSION: Qidan granules and tetrandrine could inhibit expression of both Smad 7 and transforming growth factor-beta1 and promote expression of Smad 3. Qidan granules and tetrandrine could inhibit remarkably silicotic fibrosis in rats. Qidan granules are safer than tetrandrine.