Simvastatin attenuates silica-induced pulmonary inflammation and fibrosis in rats via the AMPK-NOX pathway.

BACKGROUND: Simvastatin (Sim), a hydroxy-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, has been widely used in prevention and treatment of cardiovascular diseases. Studies have suggested that Sim exerts anti-fibrotic effects by interfering fibroblast proliferation and collagen synthesis. This study was to determine whether Sim could alleviate silica-induced pulmonary fibrosis and explore the underlying mechanisms. METHODS: The rat model of silicosis was established by the tracheal perfusion method and treated with Sim (5 or 10 mg/kg), AICAR (an AMPK agonist), and apocynin (a NOX inhibitor) for 28 days. Lung tissues were collected for further analyses including pathological histology, inflammatory response, oxidative stress, epithelial mesenchymal transformation (EMT), and the AMPK-NOX pathway. RESULTS: Sim significantly reduced silica-induced pulmonary inflammation and fibrosis at 28 days after administration. Sim could reduce the levels of interleukin (IL)-1ß, IL-6, tumor necrosis factor-α and transforming growth factor-ß1 in lung tissues. The expressions of hydroxyproline, α-SMA and vimentin were down-regulated, while E-cad was increased in Sim-treated rats. In addition, NOX4, p22pox, p40phox, p-p47phox/p47phox expressions and ROS levels were all increased, whereas p-AMPK/AMPK was decreased in silica-induced rats. Sim or AICAR treatment could notably reverse the decrease of AMPK activity and increase of NOX activity induced by silica. Apocynin treatment exhibited similar protective effects to Sim, including down-regulating of oxidative stress and inhibition of the EMT process and inflammatory reactions. CONCLUSIONS: Sim attenuates silica-induced pulmonary inflammation and fibrosis by downregulating EMT and oxidative stress through the AMPK-NOX pathway.

Daphnetin alleviates silica-induced pulmonary inflammation and fibrosis by regulating the PI3K/AKT1 signaling pathway in mice.

Silicosis is a hazardous occupational disease caused by inhalation of silica, characterized by persistent lung inflammation that leads to fibrosis and subsequent lung dysfunction. Moreover, the complex pathophysiology of silicosis, the challenges associated with early detection, and the unfavorable prognosis contribute to the limited availability of treatment options. Daphnetin (DAP), a natural lactone, has demonstrated various pharmacological properties, including anti-inflammatory, anti-fibrotic, and pulmonary protective effects. However, the effects of DAP on silicosis and its molecular mechanisms remain uncover. This study aimed to evaluate the therapeutic effects of DAP against pulmonary inflammation and fibrosis using a silica-induced silicosis mouse model, and investigate the potential mechanisms and targets through network pharmacology, proteomics, molecular docking, and cellular thermal shift assay (CETSA). Here, we found that DAP significantly alleviated silica-induced lung injury in mice with silicosis. The results of H&E staining, Masson staining, and Sirius red staining indicated that DAP effectively reduced the inflammatory response and collagen deposition over a 28-day period following lung exposure to silica. Furthermore, DAP reduced the number of TUNEL-positive cells, increased the expression levels of Bcl-2, and decreased the expression of Bax and cleaved caspase-3 in the mice with silicosis. More importantly, DAP suppressed the expression levels of NLRP3 signaling pathway-related proteins, including NLRP3, ASC, and cleaved caspase-1, thereby inhibiting silica-induced lung inflammation. Further studies demonstrated that DAP possesses the ability to inhibit the epithelial mesenchymal transition (EMT) induced by silica through the inhibition of the TGF-ß1/Smad2/3 signaling pathway. The experimental results of proteomic analysis found that the PI3K/AKT1 signaling pathway was the key targets of DAP to alleviate lung injury induced by silica. DAP significantly inhibited the activation of the PI3K/AKT1 signaling pathway induced by silica in lung tissues. The conclusion was also verified by the results of molecular and CETSA. To further verify this conclusion, the activity of PI3K/AKT1 signaling pathway was inhibited in A549 cells using LY294002. When the A549 cells were pretreated with LY294002, the protective effect of DAP on silica-induced injury was lost. In conclusion, the results of this study suggest that DAP alleviates pulmonary inflammation and fibrosis induced by silica by modulating the PI3K/AKT1 signaling pathway, and holds promise as a potentially effective treatment for silicosis.

Celastrol Pyrazine Derivative Alleviates Silicosis Progression via Inducing ROS-Mediated Apoptosis in Activated Fibroblasts.

Silicosis is a complex occupational disease without recognized effective treatment. Celastrol, a natural product, has shown antioxidant, anti-inflammatory, and anti-fibrotic activities, but the narrow therapeutic window and high toxicity severely limit its clinical application. Through structural optimization, we have identified a highly efficient and low-toxicity celastrol derivative, CEL-07. In this study, we systematically investigated the therapeutic potential and underlying mechanisms of CEL-07 in silicosis fibrosis. By constructing a silicosis mouse model and analyzing with HE, Masson, Sirius Red, and immunohistochemical staining, CEL-07 significantly prevented the progress of inflammation and fibrosis, and it effectively improved the lung respiratory function of silicosis mice. Additionally, CEL-07 markedly suppressed the expression of inflammatory factors (IL-6, IL-1α, TNF-α, and TNF-ß) and fibrotic factors (α-SMA, collagen I, and collagen III), and promoted apoptosis of fibroblasts by increasing ROS accumulation. Moreover, bioinformatics analysis combined with experimental validation revealed that CEL-07 inhibited the pathways associated with inflammation (PI3K-AKT and JAK2-STAT3) and the expression of apoptosis-related proteins. Overall, these results suggest that CEL-07 may serve as a potential candidate for the treatment of silicosis.

2-Deoxy-D-glucose ameliorates inflammation and fibrosis in a silicosis mouse model by inhibiting hypoxia-inducible factor-1α in alveolar macrophages.

Inhaling silica causes the occupational illness silicosis, which mostly results in the gradual fibrosis of lung tissue. Previous research has demonstrated that hypoxia-inducible factor-1α (HIF-1α) and glycolysis-related genes are up-regulated in silicosis. The role of 2-deoxy-D-glucose (2-DG) as an inhibitor of glycolysis in silicosis mouse models and its molecular mechanisms remain unclear. Therefore, we used 2-DG to observe its effect on pulmonary inflammation and fibrosis in a silicosis mouse model. Furthermore, in vitro cell experiments were conducted to explore the specific mechanisms of HIF-1α. Our study found that 2-DG down-regulated HIF-1α levels in alveolar macrophages induced by silica exposure and reduced the interleukin-1ß (IL-1ß) level in pulmonary inflammation. Additionally, 2-DG reduced silica-induced pulmonary fibrosis. From these findings, we hypothesize that 2-DG reduced glucose transporter 1 (GLUT1) expression by inhibiting glycolysis, which inhibits the expression of HIF-1α and ultimately reduces transcription of the inflammatory cytokine, IL-1ß, thus alleviating lung damage. Therefore, we elucidated the important regulatory role of HIF-1α in an experimental silicosis model and the potential defense mechanisms of 2-DG. These results provide a possible effective strategy for 2-DG in the treatment of silicosis.

Targeting progranulin alleviated silica particles-induced pulmonary inflammation and fibrosis via decreasing Il-6 and Tgf-ß1/Smad.

Long term exposure to silica particles leads to various diseases, among which silicosis is of great concern. Silicosis is an interstitial lung disease caused by inhalation of silica particles in production environments. However, the mechanisms underlying silicosis remains unclear. Our previous studies revealed that progranulin (Pgrn) promoted the expression of pro-inflammatory factors in alveolar macrophages treated with silica particles and the secretion of extracellular matrix of pulmonary fibroblasts. Nevertheless, the role of Pgrn in silica particles-induced silicosis in vivo was unknown. This study found that silica particles increased Pgrn expression in silicosis patients. Pgrn deficiency reduced lung inflammation and fibrosis in silica particles-induced silicosis mouse models. Subsequently, based on transcriptional sequencing and interleukin (Il) -6 knockout mouse models, results demonstrated that Pgrn deficiency might decrease silicosis inflammation by reducing the production of Il-6, thereby modulating pulmonary fibrosis in the early stage of silicosis mouse models. Furthermore, another mechanism through which Pgrn deficiency reduced fibrosis in silicosis mouse models was the regulation of the transforming growth factor (Tgf) -ß1/Smad signaling pathway. Conclusively, Pgrn contributed to silicosis inflammation and fibrosis induced by silica particles, indicating that Pgrn could be a promising therapeutic target.

Celastrol as a candidate drug for silicosis: From bioinformatics and network pharmacology to experimental validation.

Silicosis, a highly lethal occupational respiratory disease characterized by irreversible pulmonary fibrosis, remains challenging to treat due to its unclear pathogenesis. In this study, bioinformatics, network pharmacology, and experimental validation were combined to explore potential mechanisms and therapeutic drugs for silicosis. First, the differentially expressed genes（DEGs）and pathway enrichment in pulmonary fibrosis were identified by GO and KEGG analysis. Next, the differential genes were submitted to cMap database for drug prediction and celastrol stood out as the most promising candidate drug. Then, network pharmacology analysis identified pharmacological targets of celastrol and demonstrated that celastrol could regulate JAK-STAT, MAPK, and Toll-like receptor signaling pathways. Finally, we verified the therapeutic role and mechanism of celastrol on silicosis. In vivo, celastrol significantly ameliorated CS-induced inflammation and fibrosis in silicosis mice, including inflammatory cell infiltration, collagen fiber and extracellular matrix deposition, fibroblast activation and related factor expression. Moreover, it dramatically improved lung respiratory function of silicosis mice. In vitro, celastrol suppressed CS-induced cytokine expression, apoptosis of macrophages and activation of Stat3 and Erk1/2 signals. Overall, our research identified and verified celastrol as a novel and promising candidate drug for silicosis.

[Intervention effect of apocynin on silicosis induced by silica in rats].

Objective: To investigate the intervention effect and its mechanism of apocynin, an inhibitor of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) on silicosis induced by silica (SiO(2)) in rats. Methods: In October 2021, 24 SPF SD male rats were divided into control group, silicosis model group and apocynin intervention group according to random number table method, with 8 rats in each group. SiO(2) was exposed by one-time intratracheal instillation. The rats in the apocynin intervention group were intraperitoneally injected with apocynin 50 mg/kg, 3 times a week, on the second day after treatment. The rats were sacrificed 28 days later, and lung coefficients were calculated after lung tissues were weighed. Hematoxylin-eosin staining and Masson staining were used to observe the lung histopathological changes in each group, respectively. The levels of NOX, reactive oxygen species (ROS), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) in lung tissue were detected. The expressions of interleukin-1 beta (IL-1ß), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were determined by Enzyme-Linked Immunosorbent Assay (ELISA). The level of hydroxyproline (HYP) was detected by alkaline hydrolysate. The expressions of transforming growth factor beta 1 (TGF-ß1), E-cadherin (E-cad) and α-smooth muscle actin (α-SMA) in lung tissue were detected by Western blotting. Results: Compared with the control group, the body weight of silicosis model group was decreased, the lung tissue showed obvious inflammatory infiltration and fibrosis, and the levels of lung coefficient, IL-1ß, IL-6, TNF-α and TGF-ß1 were significantly increased (P<0.05). Compared with the silicosis model group, the lung tissue injury in the apocynin intervention group was significantly improved, the lung coefficient, NOX, ROS, MDA, IL-1ß, IL-6, TNF-α and TGF-ß1 levels were decreased, and the activity of GSH-Px was increased (P<0.05). Compared with the silicosis model group, the expressions of HYP and α-SMA were decreased and the level of E-cad was increased in the apocynin intervention group (P<0.05) . Conclusion: Apocynin may alleviate SiO(2)-induced fibrosis in silicosis rats by reducing oxidative stress, the release of inflammatory factors and inhibiting the process of epithelial-mesenchymal transition.

Nebulized inhalation of LPAE-HDAC10 inhibits acetylation-mediated ROS/NF-κB pathway for silicosis treatment.

Silicosis is a serious silica-induced respiratory disease for which there is currently no effective treatment. Irreversible pulmonary fibrosis caused by persistent inflammation is the main feature of silicosis. As an underlying mechanism, acetylation regulated by histone deacetylases (HDACs) are believed to be closely associated with persistent inflammation and pulmonary fibrosis. However, details of the mechanisms associated with the regulation of acetylated modification in silicosis have yet to be sufficiently established. Furthermore, studies on the efficient delivery of DNA to lung tissues by nebulized inhalation for the treatment of silicosis are limited. In this study, we established a mouse model of silicosis successfully. Differentially expressed genes (DEGs) between the lung tissues of silicosis and control mice were identified based on transcriptomic analysis, and HDAC10 was the only DEG among the HDACs. Acetylomic and combined acetylomic/proteomic analysis were performed and found that the differentially expressed acetylated proteins have diverse biological functions, among which 12 proteins were identified as the main targets of HDAC10. Subsequently, HDAC10 expression levels were confirmed to increase following nebulized inhalation of linear poly(ß-amino ester) (LPAE)-HDAC10 nanocomplexes. The levels of oxidative stress, the phosphorylation of IKKß, IκBα and p65, as well as inflammation were inhibited by HDAC10. Pulmonary fibrosis, and lung function in silicosis showed significant improvements in response to the upregulation of HDAC10. Similar results were obtained for the silica-treated macrophages in vitro. In conclusion, HDAC10 was identified as the main mediator of acetylation in silicosis. Nebulized inhalation of LPAE-HDAC10 nanocomplexes was confirmed to be a promising treatment option for silicosis. The ROS/NF-κB pathway was identified as an essential signaling pathway through which HDAC10 attenuates oxidative stress, inflammation, and pulmonary fibrosis in silicosis. This study provides a new theoretical basis for the treatment of silicosis.

Apelin Prevents and Alleviates Crystalline Silica-induced Pulmonary Fibrosis via Inhibiting Transforming Growth Factor Beta 1-triggered Fibroblast Activation.

Silicosis is a common and ultimately fatal occupational disease, yet the limited therapeutic option remains the major clinical challenge. Apelin, an endogenous ligand of the G-protein-coupled receptor (APJ), is abundantly expressed in diverse organs. The apelin-APJ axis helps to control pathological and physiological processes in lung. The role of apelin in the pathological process and its possible therapeutic effects on silicosis have not been elucidated. In this study, we found that lung expression and circulating levels of apelin were markedly decreased in silicosis patients and silica-induced fibrotic mice and associated with the severity. Furthermore, in vivo data demonstrated that pre-treatment from day 3 and post-treatment from day 15 with apelin could both alleviate silica-induced pulmonary fibrosis in mice. Besides, apelin inhibited pulmonary fibroblast activation via transforming growth factor beta 1 (TGF-ß1) signaling. Our study suggested that apelin could prevent and reverse silica-induced pulmonary fibrosis by inhibiting the fibroblast activation through TGF-ß1 signaling pathway, thus providing a new potential therapeutic strategy for silicosis and other pulmonary fibrosis.

Animal models of silicosis: fishing for new therapeutic targets and treatments.

Silicosis as an occupational lung disease has been present in our lives for centuries. Research studies have already developed and implemented many animal models to study the pathogenesis and molecular basis of the disease and enabled the search for treatments. As all experimental animal models used to date have their advantages and disadvantages, there is a continuous search for a better model, which will not only accelerate basic research, but also contribute to clinical aspects and drug development. We review here, for the first time, the main animal models developed to date to study silicosis and the unique advantages of the zebrafish model that make it an optimal complement to other models. Among the main advantages of zebrafish for modelling human diseases are its ease of husbandry, low maintenance cost, external fertilisation and development, its transparency from early life, and its amenability to chemical and genetic screening. We discuss the use of zebrafish as a model of silicosis, its similarities to other animal models and the characteristics of patients at molecular and clinical levels, and show the current state of the art of inflammatory and fibrotic zebrafish models that could be used in silicosis research.

Unraveling the mechanism of tetrandrine combined with Buyang Huanwu Decoction against silicosis using network pharmacology and molecular docking analyses.

Silicosis is an incurable chronic disease characterized by lung fibrosis and inflammation. The combination of tetrandrine and Buyang Huanwu Decoction (BYHWD) has a curative effect on silicosis. However, the mechanism of action and the key active constituent in BYHWD are still unclear. The present study employed network pharmacology and molecular docking to determine the mechanism of action and the key active components of BYHWD of Tetrandrine in combination with BYHWD for silicosis. The primary elements and targets of BYHWD were obtained from the Traditional Chinese Medicine Systems Pharmacology and analysis platform. The targets associated with tetrandrine and silicosis were identified and extracted from the Comparative Toxicogenomics Database and GeneCards database. The potential targets for the treatment of silicosis using a combination of Tetrandrine and BYHWD were identified by considering the overlapping targets between compound drugs and silicosis. These targets were then utilized to construct protein-protein interaction networks, compound drug-ingredient-target networks, and perform enrichment analyses. The top 5 active ingredients present in the compound drug-ingredient-target network are tetrandrine, quercetin, luteolin, kaempferol, and beta-carotene. Similarly, the top 6 hub genes in the protein-protein interaction network are FGF2, MMP-9, MMP-1, IL-10, IL-17A, and IL-6. The molecular docking suggested that the active components may easily access the active pocket of the hub gene. The in-silico investigation suggested that quercetin might be the active component in BYHWD responsible for therapeutic effectiveness against silicosis. This study identified the active compound and potential molecular mechanism underlying the therapeutic effects of BYHWD in combination with tetrandrine for treating silicosis. Notably, we found that quercetin may serve as the key compound in BYHWD for the treatment of silicosis.

Baicalin alleviates silica-induced lung inflammation and fibrosis by inhibiting TLR4/NF-?B pathway in rats.

Silicosis is an occupational lung disease caused by inhaling silica dust. The disease is characterized by early lung inflammation and late irreversible pulmonary fibrosis. Here we report the effect of Baicalin, a main flavonoid compound from the roots of Chinese herbal medicine Huang Qin on silicosis in a rat model. Results showed Baicalin (50 or 100 mg/kg/day) can mitigate the silica-induced lung inflammation and reduce the harm of alveolar structure and the blue region of collagen fibers in rat lung at 28 days after administration. At the same time, Baicalin also diminished the level of interleukin-1beta (IL-1beta, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) in lung tissues. The protein expression of collagen I (Col-1), alpha-smooth muscle actin (alpha-SMA) and vimentin were down-regulated while E-cadherin (E-cad) was increased in Baicalin-treated rats. In addition, the Toll Like Receptor 4 (TLR4)/ nuclear factor kappaB (NF-kappaB) pathway was enabled at 28 days after silica infusion, and the treatment of Baicalin diminished the expression of TLR4 and NF-?B in the lungs of rat with silicosis. These results suggested that Baicalin inhibited the pulmonary inflammatory and fibrosis in a rat model of silicosis, which could be attributed to inhibition of the TLR4/NF-kappaB pathway.

Crystalline silica-induced macrophage pyroptosis interacting with mitophagy contributes to pulmonary fibrosis via modulating mitochondria homeostasis.

Environmental exposure to crystalline silica (CS) can lead to silicosis. Alveolar macrophages (AMs) play a crucial role in the pathogenesis of silicosis. Previously, we demonstrated that enhancing AMs mitophagy exerted protective effects on silicosis with a restrained inflammatory response. However, the exact molecular mechanisms are elusive. Pyroptosis and mitophagy are two different biological processes that determine cell fate. Exploring whether there were interactions or balances between these two processes in AMs would provide new insight into treating silicosis. Here we reported that crystalline silica induced pyroptosis in silicotic lungs and AMs with apparent mitochondria injury. Notably, we identified a reciprocal inhibitory effect between mitophagy and pyroptosis cascades in AMs. By enhancing or diminishing mitophagy, we demonstrated that PINK1-mediated mitophagy helped clear damaged mitochondria to negatively regulate CS-induced pyroptosis. While constraining pyroptosis cascades by NLRP3, Caspase1, and GSDMD inhibitors, respectively, displayed enhanced PINK1-dependent mitophagy with lessened CS-injured mitochondria. These observed effects were echoed in the mice with enhanced mitophagy. Therapeutically, we demonstrated abolishing GSDMD-dependent pyroptosis by disulfiram attenuated CS-induced silicosis. Collectively, our data demonstrated that macrophage pyroptosis interacting with mitophagy contributes to pulmonary fibrosis via modulating mitochondria homeostasis, which may provide potential therapeutic targets.

From Basic Research to Clinical Practice: Considerations for Treatment Drugs for Silicosis.

Silicosis, characterized by irreversible pulmonary fibrosis, remains a major global public health problem. Nowadays, cumulative studies are focusing on elucidating the pathogenesis of silicosis in order to identify preventive or therapeutic antifibrotic agents. However, the existing research on the mechanism of silica-dust-induced pulmonary fibrosis is only the tip of the iceberg and lags far behind clinical needs. Idiopathic pulmonary fibrosis (IPF), as a pulmonary fibrosis disease, also has the same problem. In this study, we examined the relationship between silicosis and IPF from the perspective of their pathogenesis and fibrotic characteristics, further discussing current drug research and limitations of clinical application in silicosis. Overall, this review provided novel insights for clinical treatment of silicosis with the hope of bridging the gap between research and practice in silicosis.

Atractylenolide III Ameliorated Autophagy Dysfunction via Epidermal Growth Factor Receptor-Mammalian Target of Rapamycin Signals and Alleviated Silicosis Fibrosis in Mice.

Atractylenolide III (ATL-III) is a major active constituent of the natural plant Atractylodes rhizome. Our previous study has shown that ATL-III may alleviate alveolar macrophage apoptosis via the inhibition of the mammalian target of rapamycin (mTOR)-mediated autophagy of human silicosis. Therefore, we aimed to further explore the function of ATL-III in autophagy, apoptosis, and pulmonary fibrosis by establishing the ATL-III-intervened silicosis mouse model in this study. Meanwhile, we sought and then verified potential autophagy-related signaling pathways by matching differentially expressed genes (attained by RNA sequencing) and the autophagy database. In this study, RNA-sequencing results implied that the epidermal growth factor receptor, the crucial upstream activator of mTOR, was seen as a potential autophagy-regulatory molecule in the ATL-III-intervened silicosis mouse model. The finding of this study was that ATL-III might improve the disorder of autophagic degradation via the activation of epidermal growth factor receptor-mTOR signals in the pulmonary tissue of the silicosis mouse model. ATL-III also alleviated cell apoptosis and silicotic fibrosis. Overall, we supposed that ATL-III might be a potential protective medicine, which had a regulatory effect on autophagy, for the intervention of silicotic fibrosis. In the future, the therapeutic drugs for silicosis should be further focused on the development and application of such natural autophagy agents.

Enhancement of suppression oxidative stress and inflammation of quercetin by nano-decoration for ameliorating silica-induced pulmonary fibrosis.

Silicosis is a life-threatening lung fibrotic disease caused by excessive inhalation of environmental exposure to crystalline silica-containing dust, whereas achieving therapeutic cures are constrained. Antioxidation and anti-inflammation are currently recognized as effective strategies to counteract organ fibrosis. Using naturally occurring phytomedicines quercetin (Qu) has emerged in antagonizing fibrotic disorders involving oxidative stress and inflammation, but unfortunately the hydrophilicity deficiency. Herein, chitosan-assisted encapsulation of Qu in nanoparticles (Qu/CS-NPs) was first fabricated for silicosis-associated fibrosis treatment by pulmonary delivery. Qu/CS-NPs with spherical diameters of ~160 nm, demonstrated a high Qu encapsulated capability, excellent hydrophilic stability, fantastic oxidation radical scavenging action, and outstanding controlled as well as slow release Qu action. A silicosis rat model induced by intratracheal instillation silica was established to estimate the anti-fibrosis effect of Qu/CS-NPs. After intratracheal administration, CS-NPs markedly enhanced Qu anti-fibrotic therapy efficacy, accompanying the evident changes in reducing ROS and MDA production to mitigate oxidative stress, inhibiting IL-1ß and TNF-α release, improving lung histological architecture, down-regulating α-SAM levels and suppressing ECM deposition, and thereby ameliorating silica-induced pulmonary fibrosis. Results manifested that the augmented antioxidant and anti-inflammatory activities of Qu by CS-NPs delivery was a result of achieving this remarkable improvement in curative effects. Combined with negligible systemic toxicity, nano-decorated Qu may provide a feasible therapeutic option for silicosis therapy.

AAV9-HGF cooperating with TGF-beta/Smad inhibitor attenuates silicosis fibrosis via inhibiting ferroptosis.

Silicosis is a devastating interstitial lung disease characterized by silicon nodules and diffuse pulmonary fibrosis. To date, inefficient therapy is still a challenge of this disease due to its complicated pathogenesis. Hepatocyte growth factor (HGF) which is highly expressed in hepatocyte with anti-fibrotic and anti-apoptotic function was downregulated in silicosis. In addition, the upregulation of transforming growth factor-beta (TGF-ß), another pathological molecular was observed to aggravate the severity and accelerate the progression of silicosis. Here AAV expressed HGF with targeting pulmonary capillaries and SB431542, the inhibitor of TGF-ß signal pathway, were simultaneously adopted to synergistically reduce silicosis fibrosis. In vivo result demonstrated that the cooperation of HGF with SB431542 showed strong anti-fibrosis effects on the silicosis mice via tracheal administration of silica, compared to the separate treatment. The high efficacy was mainly achieved by remarkably by reducing ferroptosis of lung tissue. In our point, the combination of AAV9-HGF with SB431542 provide an alternative to relieve silicosis fibrosis from the perspective of targeting pulmonary capillaries.

Effects of Green Tea Polyphenol Epigallocatechin-3-Gallate on Markers of Inflammation and Fibrosis in a Rat Model of Pulmonary Silicosis.

Inhalation of silica particles causes inflammatory changes leading to fibrotizing silicosis. Considering a lack of effective therapy, and a growing information on the wide actions of green tea polyphenols, particularly epigallocatechin-3-gallate (EGCG), the aim of this study was to evaluate the early effects of EGCG on markers of inflammation and lung fibrosis in silicotic rats. The silicosis model was induced by a single transoral intratracheal instillation of silica (50 mg/mL/animal), while controls received an equivalent volume of saline. The treatment with intraperitoneal EGCG (20 mg/kg, or saline in controls) was initiated the next day after silica instillation and was given twice a week. Animals were euthanized 14 or 28 days after the treatment onset, and the total and differential counts of leukocytes in the blood and bronchoalveolar lavage fluid (BALF), wet/dry lung weight ratio, and markers of inflammation, oxidative stress, and fibrosis in the lung were determined. The presence of collagen and smooth muscle mass in the walls of bronchioles and lung vessels was investigated immunohistochemically. Early treatment with EGCG showed some potential to alleviate inflammation, and a trend to decrease oxidative stress-induced changes, including apoptosis, and a prevention of fibrotic changes in the bronchioles and pulmonary vessels. However, further investigations should be undertaken to elucidate the effects of EGCG in the lung silicosis model in more detail. In addition, because of insufficient data from EGCG delivery in silicosis, the positive and eventual adverse effects of this herbal compound should be carefully studied before any preventive use or therapy with EGCG may be recommended.

Inhibition of Oncogenic Src Ameliorates Silica-Induced Pulmonary Fibrosis via PI3K/AKT Pathway.

Silicosis is a refractory disease. Previous studies indicate that damaged alveolar epithelial cells act as a driver in pulmonary fibrosis. Our results show that epithelial cells that acquire the mesenchymal phenotype are associated with the pathogenesis of silicosis. c-Src kinase, a non-receptor tyrosine kinase, has been shown to be a positive regulator of organ fibrosis, but specific mechanisms remain unclear and rarely researched in silicosis. The activated Phosphatidylinositol-3 kinases/AKT(PI3K/AKT) pathway promotes fibrosis. We aimed to determine whether c-Src regulates fibrosis via the PI3K/AKT signaling pathway in the development of silicosis. C57/BL mice were intratracheally perfused with 10 mg silica suspension to establish a model of silicosis. In vivo, silica particles induced lung fibrosis. The profibrotic cytokine transforming growth factor-ß1 (TGF-ß1) exhibited a high expression in pulmonary fibrosis. The phosphorylated c-Src protein was increased and the PI3K/AKT pathway was activated in model lung tissue. In vitro, silica increased the expression of TGF-ß1- and TGF-ß1-induced mesenchymal phenotype and fibrosis in a mouse epithelial cells line. siRNA-Src inhibited the c-Src, the phosphorylation of the PI3K/AKT pathway, and the mesenchymal phenotype induced by TGF-ß1. LY294002, a specific inhibitor of PI3K, suppressed the phosphorylation of PI3K/AKT but did not affect Src activation. SU6656, a selective Src inhibitor, attenuated fibrosis in silicosis model. In summary, c-Src promotes fibrosis via the PI3K/AKT pathway in silica-induced lung fibrosis, and Src kinase inhibitors are potentially effective for silicosis treatment.

VX-765 attenuates silica-induced lung inflammatory injury and fibrosis by modulating alveolar macrophages pyroptosis in mice.

Silicosis is a diffuse fibrotic lung disease in which excessive inflammatory responses are triggered by silica exposure. Pyroptosis, a pro-inflammatory mode of programmed cell death, is mediated by gasdermin and may play a pivotal role in the development of silicosis. The caspase-1 inhibitor, VX-765, was used in vivo and in vitro to investigate the effects of silica-induced early inflammatory injury and later lung fibrosis. Our findings show that VX-765 reduces inflammatory lung injury by inhibiting silica-induced pyroptosis of alveolar macrophages in a silicosis mouse model. VX-765 limits the infiltration of inflammatory M1 alveolar macrophages, decreasing expression of inflammatory cytokines, including IL-1ß, TNF-α, IL-6, CCL2, and CCL3, and down-regulating endogenous DAMPs and inflammatory immune-related cell pattern recognition receptors TLR4 and NLRP3. Furthermore, VX-765 alleviates fibrosis by down-regulating α-smooth muscle actin (α-SMA), collagen, and fibronectin. In this study, we illustrate that Alveolar macrophages pyroptosis occur in the early stages of silicosis, and VX-765 can alleviate the development of silicosis by inhibiting the pyroptosis signaling pathway. These results may provide new insight into the prevention and treatment of early-stage silicosis.