Lipopolysaccharides may aggravate apoptosis through accumulation of autophagosomes in alveolar macrophages of human silicosis

Pectin-coated Malvidin-3-O-galactoside attenuates silica-induced pulmonary fibrosis by promoting mitochondrial autophagy and inhibiting cell apoptosis

BACKGROUND

Blueberries are a rich source of anthocyanins, which have been established to have multiple beneficial properties. However, the structure of anthocyanin monomers is unstable and their bioavailability is low. To date, whereas functional studies on anthocyanins have focused mainly on the effects of their monomers on liver and kidney, few have examined the interventional effects on pulmonary fibrosis.

PURPOSE

In this study, we combined malvidin-3-O-galactoside (M3G)1 derived from blueberries with pectin (PEC)2 to form an anthocyanin-pectin complex (M3G-PEC),3 the anti-fibrotic effects of which were examined by administering to mice with modeled pulmonary fibrosis induced by silica particles (SP).4 METHODS: To evaluate the therapeutic effects and mechanisms of action of M3G-PEC with respect to the progression of pulmonary fibrosis, we measured autophagy- and apoptosis-related indices in C57BL/6 mice and mouse alveolar macrophage cell line (MH-S).5 RESULTS: The results of in vivo and in vitro studies revealed that M3G-PEC can alleviate the degree of pulmonary fibrosis, enhances the expression of Microtubule-associated protein light chain 3 (LC3),6 PTEN-inducible putative kinase 1 (PINK1),7 Parkin and B-cell lymphoma-2 (BCL-2),8 and causes the down-regulation of Caspase-3, P62, p-mammalian target of rapamyein (p-mTOR),9 phosphorylated protein kinase B (p-Akt)10 and Bax. And then, M3G-PEC contributes to maintaining a steady mitochondrial membrane potential and reduces the release of cytochrome c (Cyt-C)11 in cells.

CONCLUSION

Collectively, these findings indicate that M3G-PEC can preserve the bioactivity of anthocyanins and effectively enhance their bioavailability. Moreover, by regulating the BECN-1/Akt/mTOR pathway, M3G-PEC can influence the progression of silica-induced pulmonary fibrosis.

A comprehensive retrospect on the current perspectives and future prospects of pneumoconiosis

Pneumoconiosis is a widespread occupational pulmonary disease caused by inhalation and retention of dust particles in the lungs, is characterized by chronic pulmonary inflammation and progressive fibrosis, potentially leading to respiratory and/or heart failure. Workers exposed to dust, such as coal miners, foundry workers, and construction workers, are at risk of pneumoconiosis. This review synthesizes the international and national classifications, epidemiological characteristics, strategies for prevention, clinical manifestations, diagnosis, pathogenesis, and treatment of pneumoconiosis. Current research on the pathogenesis of pneumoconiosis focuses on the influence of autophagy, apoptosis, and pyroptosis on the progression of the disease. In addition, factors such as lipopolysaccharide and nicotine have been found to play crucial roles in the development of pneumoconiosis. This review provides a comprehensive summary of the most fundamental achievements in the treatment of pneumoconiosis with the purpose of indicating the future direction of its treatment and control. New technologies of integrative omics, artificial intelligence, systemic administration of mesenchymal stromal cells have proved useful in solving the conundrum of pneumoconiosis. These directional studies will provide novel therapeutic targets for the treatment of pneumoconiosis.

Optimized method for higher yield of alveolar macrophage isolation for ex vivo studies

Alveolar macrophages (AMs) are a fully differentiated lung-resident immune cell population and are a critical component of lung immunity. AMs can be easily isolated from mice via bronchoalveolar lavage fluid (BALF) collection. The quality and quantity of AMs in BALF isolation are critical for generating reliable and high-quality data for ex vivo studies. Traditional techniques use ice-cold (4°C) buffer to collect AMs in BALF and result in low yield. Hence, a new method that consistently gives a higher yield of AMs is needed. We demonstrate here an optimized method that significantly increases the quantity of AM recovery in BALF (>2.8 times than the traditional method). Our method uses a warm-buffer (37°C) containing EDTA. We compared the viability and functional parameters (cytokine/chemokine expression, phagocytosis) of AMs isolated by our new and traditional methods. Our study revealed that AMs collected using our method have similar viability and functional characteristics to those collected using traditional method. Hence, our new method can be used for the collection of a higher number of AMs without altering their function. This protocol might also be useful for isolating tissue-resident immune cells from other anatomical sites for ex vivo and other downstream applications.

Toll-like receptor 4 mediated autophagy regulates airway smooth muscle cells behavior

OBJECTIVES

Airway remodeling, a prominent feature of asthma, involves aberrant proliferation, apoptosis, and migration of airway smooth muscle cells (ASMCs). Toll-like receptors (TLRs) are implicated in the regulation of the autophagy pathway. In this study, we aimed to investigate the influence of Toll-like receptor 4 (TLR4) on autophagy and its underlying mechanism in ASMC proliferation, apoptosis, and migration.

METHODS

Histopathological changes in the lungs of asthmatic mice assessed by Hematoxylin-Eosin (HE) and Masson staining. Cell proliferation, apoptosis and migration were evaluated utilizing CCK8, Edu, Flow cytometry and wound heading assays. The effectiveness of siRNA transfection and the expression of TLR4, autophagy, and proliferation-related proteins after siRNA treatment were examined through RT-PCR and Western blot (WB).

CONCLUSION

We observed an increase in TLR4 expression and autophagy in a mouse model of OVA-induced asthma. In vitro experiments showed that siRNA-mediated inhibition of TLR4 suppressed autophagy, proliferation, and migration of ASMCs, whereas TLR4 activation by lipopolysaccharide (LPS) had the opposite effect. Furthermore, the autophagy inhibitor 3-Methyladenine (3MA) inhibited ASMCs proliferation and migration while promoting apoptosis. Significantly, our study demonstrated that autophagy inhibition reversed the promotion effect of LPS on ASMC proliferation and migration. These findings suggest that TLR4 may modulate ASMC behavior through the regulation of autophagy.

Glycerol monolaurate regulates apoptosis and inflammation by suppressing lipopolysaccharide-induced ROS production and NF-κB activation in avian macrophages

Macrophages play a crucial role in both innate and adaptive immunity. However, their abnormal activation can lead to undesirable inflammatory reactions. This study aimed to investigate the effects of glycerol monolaurate (GML), a natural monoester known for its anti-inflammatory and immunoregulatory properties, on avian macrophages using the HD11 cell line. The results indicated that a concentration of 10 μg/mL of GML enhanced the phagocytic activity of HD11 cells (P < 0.05) without affecting cell viability (P > 0.05). GML decreased the expression of M1 macrophage polarization markers, such as CD86 and TNF-α genes (P < 0.05), while increasing the expression of M2 macrophage polarization markers, such as TGF-β1 and IL-10 genes (P < 0.05). GML suppressed ROS production, apoptosis, and the expression of proinflammatory genes (IL-1β and IL-6) induced by LPS (P < 0.05). GML also promoted the expression of TGF-β1 and IL-10 (P < 0.05), both in the presence and absence of LPS exposure. Moreover, GML suppressed the gene expression of TLR4 and NF-κB p65 induced by LPS (P < 0.05), as well as the phosphorylation of NF-κB p65 (P < 0.05). In conclusion, GML exhibited regulatory effects on the polarized state of avian macrophages and demonstrated significant anti-apoptotic and anti-inflammatory properties by suppressing intracellular ROS and the NF-κB signaling pathway.

Fraxetin pretreatment alleviates cisplatin-induced kidney injury by antagonizing autophagy and apoptosis via mTORC1 activation

Cisplatin-induced kidney injury (CKI) is a common complication of chemotherapy. Fraxetin, derived from Fraxinus bungeana A. DC. bark, has antioxidant, anti-inflammatory, and anti-fibrotic effects. This study aims to investigate fraxetin's effects on CKI and its underlying mechanism in vivo and in vitro. Tubular epithelial cells (TECs) and mice were exposed to cisplatin with and without fraxetin preconditioning assess fraxetin's role in CKI. TECs autophagy was observed using transmission electron microscopy. Apoptosis levels in animal tissues were measured using TUNEL staining. The protective mechanism of fraxetin was explored through pharmacological and genetic regulation of mTORC1. Molecular docking was used to identify potential binding sites between fraxetin and mTORC1. The results indicated that fraxetin pretreatment reduced cisplatin-induced kidney injury in a time- and concentration-dependent way. Fraxetin also decreased autophagy in TECs, as observed through electron microscopy. Tissue staining confirmed that fraxetin pretreatment significantly reduced cisplatin-induced apoptosis. Inhibition of mTORC1 using rapamycin or siRNA reversed the protective effects of fraxetin on apoptosis and autophagy in cisplatin-treated TECs, while activation of mTORC1 enhanced fraxetin's protective effect. Molecular docking analysis revealed that fraxetin can bind to HEAT-repeats binding site on mTORC1 protein. In  summary, fraxetin pretreatment alleviates CKI by antagonizing autophagy and apoptosis via mTORC1 activation. This provides evidence for the potential therapeutic application of fraxetin in CKI.

Investigation of the mechanism of silica-induced pulmonary fibrosis: The role of lung microbiota dysbiosis and the LPS/TLR4 signaling pathway

The widespread manufacture of silica and its extensive use, and potential release of silica into the environment pose a serious human health hazard. Silicosis, a severe global public health issue, is caused by exposure to silica, leading to persistent inflammation and fibrosis of the lungs. The underlying pathogenic mechanisms of silicosis remain elusive. Lung microbiota dysbiosis is associated with the development of inflammation and fibrosis. However, limited information is currently available regarding the role of lung microbiota in silicosis. The study therefore is designed to conduct a comprehensive analysis of the role of lung microbiota dysbiosis and establish a basis for future investigations into the potential mechanisms underlying silicosis. Here, the pathological and biochemical parameters were used to systematically assessed the degree of inflammation and fibrosis following silica exposure and treatment with combined antibiotics. The underlying mechanisms were studied via integrative multi-omics analyses of the transcriptome and microbiome. Analysis of 16S ribosomal DNA revealed dysbiosis of the microbial community in silicosis, characterized by a predominance of gram-negative bacteria. Exposure to silica has been shown to trigger lung inflammation and fibrosis, leading to an increased concentration of lipopolysaccharides in the bronchoalveolar lavage fluid. Furthermore, Toll-like receptor 4 was identified as a key molecule in the lung microbiota dysbiosis associated with silica-induced lung fibrosis. All of these outcomes can be partially controlled through combined antibiotic administration. The study findings demonstrate that the dysbiosis of lung microbiota enhances silica-induced fibrosis associated with the lipopolysaccharides/Toll-like receptor 4 pathway and provided a promising target for therapeutic intervention of silicosis.

Periodontitis promotes the progression of diabetes mellitus by enhancing autophagy

Objective

This study aims to identify the periodontitis factor that activates excessive autophagy in pancreatic β cells, resulting in organic lesions of pancreatic islet tissues and diminished insulin secretion, thereby accelerating the progression of diabetes mellitus (DM).

Methods

Sprague-Dawley (SD) rats were induced with periodontitis (PD), type 2 diabetes mellitus (T2DM), or the combination of T2DM and PD (DP) through a high-sugar/high-fat diet and ligation of the tooth neck with silk thread. Alveolar bone resorption was assessed using Micro-CT, blood glucose levels were measured with a blood glucose meter, pancreatic tissue pathology was examined through HE staining, and the expression of autophagy-related proteins Beclin1 and LC3II/LC3I was analyzed using Western blotting.

Results

Micro-CT results revealed more pronounced alveolar bone resorption and root bifurcation exposure in the PD and DP groups compared to the control group, with the DP group exhibiting the most severe condition. HE staining demonstrated the formation of periodontal pockets, severe alveolar bone destruction, and abnormal pancreatic islet tissue morphology in the PD and DP groups. The serum levels of IL-6, TNF-α, and IL-1β increased sequentially in the control, DM, PD, and DP groups (P < 0.05). Relative expressions of GCK and GLUT-2 mRNA decreased in the PD group compared to the control group (P > 0.05), while the mRNA expressions in the DP and DM groups increased (P < 0.05), with the DP group exhibiting higher levels than the DM group (P < 0.05). Western blot results indicated increased expression levels of autophagy proteins Beclin1 and LC3II/LC3I in the DM and DP groups compared to the control group (P < 0.05), with the DP group exhibiting higher levels than the DM group (P < 0.05).

Conclusion

The findings demonstrate that periodontal inflammatory factors may promote the enhancement of pancreatic cell autophagy in diabetic rats.

Bacterial lipoprotein plays an important role in the macrophage autophagy and apoptosis induced by Salmonella typhimurium and Staphylococcus aureus

This study aimed to determine the role of bacterial lipoprotein (BLP) in autophagy and apoptosis. Western blot was used to examine autophagy biomarkers in mouse bone marrow-derived macrophages (BMDMs) after infection with Salmonella typhimurium (S. typhimurium) and Staphylococcus aureus (S. aureus) and BLP stimulation. In BMDMs, enhanced protein expression of LC3-II was observed after S. typhimurium or S. aureus infection (P < 0.05) and BLP stimulation (P < 0.05). Autophagy inhibition by chloroquine resulted in increased levels of LC3-Ⅱ and p62 protein (P < 0.05). Persistently upregulated expressions of Atg3 and Atg7 were observed following BLP stimulation (P < 0.05), and knockdown of Atg3 or Atg7 significantly attenuated BLP-enhanced protein expression of LC3-Ⅱ in BMDMs. Furthermore, we found that the autophagy inhibitor 3-methyladenine prevented BLP- and infection-induced macrophage apoptosis. BLP is not only required for autophagy and apoptosis activation in macrophages but also for regulating the balance between autophagy and apoptosis.

Preliminary Study on the Effect and Molecular Mechanism of Tetrandrine in Alleviating Pulmonary Inflammation and Fibrosis Induced by Silicon Dioxide

This study aims to explore the molecular mechanism of tetrandrine (Tet) in alleviating pulmonary inflammation and fibrosis induced by silica (SiO2) from the perspective of autophagy. C57BL/6J mice were selected as experimental animals, and SiO2 was exposed by intranasal instillation. Tet was intervened by oral gavage. The mice were euthanized on the 7th and 42nd day of SiO2 exposure, and lung tissues were collected for histopathological, molecular biological, immunological, and transmission electron microscopy analysis. The results showed that SiO2 exposure could lead to significant lung inflammation and fibrosis, while Tet could significantly reduce SiO2 exposure-induced lung inflammation and fibrosis. Molecular mechanism research indicated that, compared with SiO2 expose group, Tet intervention could significantly reduce the expression levels of inflammatory cytokines and fibrosis markers (TNF-α, IL-1β, MCP-1, TGF-β1, HYP, Col-I, and Fn), and regulate the expression of key molecules ATG7, microtubule-associated protein 1 light chain 3B (LC3B), and P62 in the autophagy pathway to improve the blocking of autophagic flux, promote the recovery of autophagic lysosomal system function, and inhibit apoptosis. In summary, Tet can alleviate silica-induced lung inflammation and fibrosis, which may be achieved by regulating the expression of key molecules in the autophagy process and associated apoptotic pathway.

miR-29a-3p Regulates Autophagy by Targeting Akt3-Mediated mTOR in SiO2-Induced Lung Fibrosis

Silicosis is a refractory pneumoconiosis of unknown etiology that is characterized by diffuse lung fibrosis, and microRNA (miRNA) dysregulation is connected to silicosis. Emerging evidence suggests that miRNAs modulate pulmonary fibrosis through autophagy; however, its underlying molecular mechanism remains unclear. In agreement with miRNA microarray analysis, the qRT-PCR results showed that miR-29a-3p was significantly decreased in the pulmonary fibrosis model both in vitro and in vivo. Increased autophagosome was observed via transmission electron microscopy in lung epithelial cell models and lung tissue of silicosis mice. The expression of autophagy-related proteins LC3α/β and Beclin1 were upregulated. The results from using 3-methyladenine, an autophagy inhibitor, or rapamycin, an autophagy inducer, together with TGF-β1, indicated that autophagy attenuates fibrosis by protecting lung epithelial cells. In TGF-β1-treated TC-1 cells, transfection with miR-29a-3p mimics activated protective autophagy and reduced alpha-smooth muscle actin and collagen I expression. miRNA TargetScan predicted, and dual-luciferase reporter experiments identified Akt3 as a direct target of miR-29a-3p. Furthermore, Akt3 expression was significantly elevated in the silicosis mouse model and TGF-β1-treated TC-1 cells. The mammalian target of rapamycin (mTOR) is a central regulator of the autophagy process. Silencing Akt3 inhibited the transduction of the mTOR signaling pathway and activated autophagy in TGF-β1-treated TC-1 cells. These results show that miR-29a-3p overexpression can partially reverse the fibrotic effects by activating autophagy of the pulmonary epithelial cells regulated by the Akt3/mTOR pathway. Therefore, targeting miR-29a-3p may provide a new therapeutic strategy for silica-induced pulmonary fibrosis.

TLR4 Overexpression Aggravates Bacterial Lipopolysaccharide-Induced Apoptosis via Excessive Autophagy and NF-κB/MAPK Signaling in Transgenic Mammal Models

Gram-negative bacterial infections pose a significant threat to public health. Toll-like receptor 4 (TLR4) recognizes bacterial lipopolysaccharide (LPS) and induces innate immune responses, autophagy, and cell death, which have major impacts on the body's physiological homeostasis. However, the role of TLR4 in bacterial LPS-induced autophagy and apoptosis in large mammals, which are closer to humans than rodents in many physiological characteristics, remains unknown. So far, few reports focus on the relationship between TLR, autophagy, and apoptosis in large mammal levels, and we urgently need more tools to further explore their crosstalk. Here, we generated a TLR4-enriched mammal model (sheep) and found that a high-dose LPS treatment blocked autophagic degradation and caused strong innate immune responses and severe apoptosis in monocytes/macrophages of transgenic offspring. Excessive accumulation of autophagosomes/autolysosomes might contribute to LPS-induced apoptosis in monocytes/macrophages of transgenic animals. Further study demonstrated that inhibiting TLR4 downstream NF-κB or p38 MAPK signaling pathways reversed the LPS-induced autophagy activity and apoptosis. These results indicate that the elevated TLR4 aggravates LPS-induced monocytes/macrophages apoptosis by leading to lysosomal dysfunction and impaired autophagic flux, which is associated with TLR4 downstream NF-κB and MAPK signaling pathways. This study provides a novel TLR4-enriched mammal model to study its potential effects on autophagy activity, inflammation, oxidative stress, and cell death. These findings also enrich the biological functions of TLR4 and provide powerful evidence for bacterial infection.

The therapeutic effect of exosomal lncRNA MSTRG.91634.7 on mitochondrial dysfunction during SiO2-induced lung fibrosis

Long-term silica (SiO₂) exposure led to irreversible lung fibrosis, in which epithelial-mesenchymal transition (EMT) played an essential role. A novel lncRNA MSTRG.91634.7 in the peripheral exosomes of silicosis patients was reported in our previous study, which could remold the pathological process of silicosis. However, whether its regulatory role on the development of silicosis was related to EMT process is unclear, and its mechanism remains to be further studied. In this study, up-regulating lncRNA MSTRG91634.7 restricted SiO₂-activated EMT and restored mitochondrial homeostasis binding to PINK1 in vitro. Moreover, overexpressing PINK1 could inhibit SiO₂-activated EMT in pulmonary inflammation and fibrosis in mice. Meanwhile, PINK1 contributed to restoring the SiO₂-induced mitochondrial dysfunction in mice lung. Our results revealed that exosomal lncRNA MSTRG.91634.7 from macrophages could restore mitochondrial homeostasis to restrict the SiO₂-activated EMT by binding to PINK1 during pulmonary inflammation and fibrosis due to SiO₂ exposure.

Role of endoplasmic reticulum autophagy in acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), the prime causes of morbidity and mortality in critically ill patients, are usually treated by general supportive treatments. Endoplasmic reticulum autophagy (ER-phagy) maintains cellular homeostasis by degrading damaged endoplasmic reticulum (ER) fragments and misfolded proteins. ER-phagy is crucial for maintaining ER homeostasis and improving the internal environment. ER-phagy has a particular role in some aspects, such as immunity, inflammation, cell death, pathogen infection, and collagen quality. In this review, we summarized the definition, epidemiology, and pathophysiology of ALI/ARDS and described the regulatory mechanisms and functions of ER-phagy as well as discussed the potential role of ER-phagy in ALI/ARDS from the perspectives of immunity, inflammation, apoptosis, pathogen infection, and fibrosis to provide a novel and effective target for improving the prognosis of ALI/ARDS.

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.

PKM2 deficiency exacerbates gram-negative sepsis-induced cardiomyopathy via disrupting cardiac calcium homeostasis

Sepsis is a life-threatening syndrome with multi-organ dysfunction in critical care medicine. With the occurrence of sepsis-induced cardiomyopathy (SIC), characterized by reduced ventricular contractility, the mortality of sepsis is boosted to 70-90%. Pyruvate kinase M2 (PKM2) functions in a variety of biological processes and diseases other than glycolysis, and has been documented as a cardioprotective factor in several heart diseases. It is currently unknown whether PKM2 influences the development of SIC. Here, we found that PKM2 was upregulated in cardiomyocytes treated with LPS both in vitro and in vivo. Pkm2 inhibition exacerbated the LPS-induced cardiac damage to neonatal rat cardiomyocytes (NRCMs). Furthermore, cardiomyocytes lacking PKM2 aggravated LPS-induced cardiomyopathy, including myocardial damage and impaired contractility, whereas PKM2 overexpression and activation mitigated SIC. Mechanism investigation revealed that PKM2 interacted with sarcoplasmic/endoplasmic reticulum calcium ATPase 2a (SERCA2a), a key regulator of the excitation-contraction coupling, to maintain calcium homeostasis, and PKM2 deficiency exacerbated LPS-induced cardiac systolic dysfunction by impairing SERCA2a expression. In conclusion, these findings highlight that PKM2 plays an essential role in gram-negative sepsis-induced cardiomyopathy, which provides an attractive target for the prevention and treatment of septic cardiomyopathy.

Difference in Intestinal Flora and Characteristics of Plasma Metabonomics in Pneumoconiosis Patients

From the two perspectives of intestinal flora and plasma metabolomics, the mechanism of occurrence and development of pneumoconiosis was explored to provide a new target for the prevention and treatment of pneumoconiosis. In this study, 16S ribosome DNA (16SrDNA) gene sequencing technology was used to analyze the differences in intestinal flora of each research group through operational taxonomic units (OUT) analysis, cluster analysis, principal component analysis (PCA), partial least square discriminant analysis (PLS-DA), Kyoto Encyclopedia of Genes and Genomes (KEGG), and other analytical methods were used to analyze the differences in plasma metabolites between the study groups. Metabonomics analysis showed that the plasma metabolites of pneumoconiosis patients were significantly different from those of normal people. Fold change > 2; vip > 1; p < 0.05 were the screening criteria. In the positive and negative mode, we screened ten types of differential metabolites. These ten metabolites were upregulated to varying degrees in the pneumoconiosis patients. Seven metabolic pathways were obtained by analyzing the metabolic pathways of different metabolites. Among them, the aminoacyl tRNA biosynthesis pathway changed most obviously. The α diversity of two groups of intestinal flora was analyzed using the 16SrDNA technique. The results showed that there was no significant difference in ACE, Chao1, Shannon, or Simpson in the two groups (p > 0.05). Beta diversity analysis showed that there were differences in microbial communities. In pneumoconiosis patients, the abundance of Prevotellaceae increased, and the other nine species decreased. Compared to the control group, the abundance of Prevotellaceae in the intestinal flora of pneumoconiosis increased, and the abundance of the other nine species decreased. Compared to controls, ten substances in the plasma metabolites of pneumoconiosis patients were upregulated. Seven metabolic pathways were obtained by analyzing the metabolic pathways of different metabolites. Among them, the aminoacyl tRNA biosynthesis pathway changed most significantly. This provided a theoretical basis for further study on the pathogenesis, early prevention, and treatment of pneumoconiosis.

Inhibition of Gas6 promotes crystalline silica-induced inflammatory response of macrophages via blocking autophagy flux

Inhalation of crystalline silica (CS) can cause silicosis, which is one of the most serious interstitial lung diseases worldwide. Autophagy dysfunction is an essential step in silicosis progression. In this study, we aim to identify the effect of growth arrest-specific protein 6 (Gas6) during autophagy induction and macrophage inflammatory response caused by CS. After RAW 264.7 macrophages exposed to CS, the levels of Gas6 and autophagy markers (p62, Beclin1, and LC3-II/LC3-I) were increased, accompanied with enhanced inflammatory cytokines secretion. Using autophagy activator (rapamycin) repressed, whereas autophagy inhibitor (3-methyladenine) promoted inflammatory cytokines release. Besides, inhibition of Gas6 aggravated CS-induced inflammatory response, and autophagy inhibition facilitated the promoted effect of Gas6 silencing, resulting in elevated expression of inflammatory cytokines. These findings reveal the protective effects of Gas6 and autophagy in macrophages in response to CS exposure, and highlight the autophagy regulated by Gas6 may be a potential prevention target for CS-induced lung inflammatory response.

Pulmonary Toxicity of Silica Linked to Its Micro- or Nanometric Particle Size and Crystal Structure: A Review

Silicon dioxide (SiO2) is a mineral compound present in the Earth’s crust in two mineral forms: crystalline and amorphous. Based on epidemiological and/or biological evidence, the pulmonary effects of crystalline silica are considered well understood, with the development of silicosis, emphysema, chronic bronchitis, or chronic obstructive pulmonary disease. The structure and capacity to trigger oxidative stress are recognized as relevant determinants in crystalline silica’s toxicity. In contrast, natural amorphous silica was long considered nontoxic, and was often used as a negative control in experimental studies. However, as manufactured amorphous silica nanoparticles (or nanosilica or SiNP) are becoming widely used in industrial applications, these paradigms must now be reconsidered at the nanoscale (<100 nm). Indeed, recent experimental studies appear to point towards significant toxicity of manufactured amorphous silica nanoparticles similar to that of micrometric crystalline silica. In this article, we present an extensive review of the nontumoral pulmonary effects of silica based on in vitro and in vivo experimental studies. The findings of this review are presented both for micro- and nanoscale particles, but also based on the crystalline structure of the silica particles.

Caveolin-1 scaffolding domain peptide abrogates autophagy dysregulation in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most common and fatal form of interstitial lung disease. IPF is characterized by irreversible scarring of the lungs leading to lung function decline. Although the etiology remains poorly understood, dysregulated autophagy in alveolar-epithelial cells (AECs) together with interplay between apoptotic-AECs and proliferative-myofibroblasts have been strongly implicated in IPF pathogenesis. Recent studies have revealed that a caveolin-1-derived 7-mer peptide, CSP7, mitigates established PF at least in part by improving AEC viability. In the present study, we aimed to determine whether and how CSP7 regulates autophagy in fibrotic-lung AECs. We found that p53 and autophagic proteins were markedly upregulated in AECs from mice with single/multi-doses of bleomycin—or silica-induced PF. This was abolished following treatment of PF-mice with CSP7. Further, CSP7 abrogated silica- or bleomycin-induced p53 and autophagy proteins in AECs. Immunoprecipitation further revealed that CSP7 abolishes the interaction of caveolin-1 with LC3BII and p62 in AECs. AEC-specific p53-knockout mice resisted silica- or bleomycin-induced changes in autophagy proteins, or CSP7 treatment. Our findings provide a novel mechanism by which CSP7 inhibits dysregulated autophagy in injured AECs and mitigates existing PF. These results affirm the potential of CSP7 for treating established PF, including IPF and silicosis.

Oridonin attenuates LPS-induced early pulmonary fibrosis by regulating impaired autophagy, oxidative stress, inflammation and EMT

CONTEXT

Oridonin (Ori) possesses anti-inflammatory, antioxidant and antitumor properties. However, the effects of Ori on Lipopolysaccharide (LPS)-induced early pulmonary fibrosis remain unclear.

OBJECTIVE

We evaluated the protective effects of Ori on the mice model of pulmonary fibrosis.

MATERIALS AND METHODS

The BALB/C mice were given LPS (1 mg/kg) or Ori (20 mg/kg) according to experimental grouping. Then the left lung tissues were used for HE, immunohistochemical and Masson staining, and the right lung tissues were used for hydroxyproline measurement and western blot experiments. Bronchoalveolar lavage fluid was collected for Giemsa staining.

RESULTS

The high levels of hydroxyproline induced by LPS were reduced by Ori treatment. Immunohistochemical staining and western blot analysis showed that Ori inhibited the increased levels of fibrosis-related proteins (α-smooth muscle actin, transforming growth factor-β, Collagen Ⅰ and phosphorylated-smad). Additionally, Ori treatment increased E-cadherin levels and decreased in Snail and Slug levels. Besides, Ori could suppress LPS-induced the infiltration of neutrophils and activation of the NLRP3 inflammasome. In addition, LPS caused the upregulation of NADPH oxidase 4 and exacerbated lung fibrosis. As the activator of NF-E2 related factor-2, Ori exerted protective effects in this animal model. Moreover, Ori reversed the LPS-triggered increases in Beclin-1, P62/sequestosome 1, autophagy related 3 and LC3.

CONCLUSIONS

These findings suggested that Ori protected against LPS-induced early pulmonary fibrosis by inhibiting NLRP3-dependent inflammation, NADPH oxidase 4-dependent oxidative stress, the impaired autophagy and epithelial mesenchymal transformation.

Another One Fights the Dust - Targeting the NLRP3 Inflammasome for the Treatment of Silicosis

Silicosis is a multifaceted lung disease, characterised by persistent inflammation and structural remodelling. Despite its poor prognosis, there are no treatments currently available for patients with silicosis. Recent pre-clinical findings in models of lung fibrosis have suggested a major role for the nucleotide binding domain and leucine-rich repeat pyrin domain containing 3 (NLRP3) inflammasome in silica-driven inflammation and fibrosis. This review outlines the beneficial effects of targeting the NLRP3 inflammasome in in vitro cell experiments and in in vivo animal models, whereby inflammation and fibrosis are abrogated following NLRP3 inflammasome inhibition. While preclinical evidence is promising, studies which explore NLRP3 inflammasomes in the clinical setting are warranted. In particular, there is still a need to identify biomarkers which may be helpful for the early detection of silicosis and to fully elucidate mechanisms underlying these beneficial effects to further develop or repurpose existing anti-NLRP3 drugs as novel treatments that limit disease progression.

Mechanisms of TLR4-Mediated Autophagy and Nitroxidative Stress

Pathogenic infections have badly affected public health and the development of the breeding industry. Billions of dollars are spent every year fighting against these pathogens. The immune cells of a host produce reactive oxygen species and reactive nitrogen species which promote the clearance of these microbes. In addition, autophagy, which is considered an effective method to promote the destruction of pathogens, is involved in pathological processes. As research continues, the interplay between autophagy and nitroxidative stress has become apparent. Autophagy is always intertwined with nitroxidative stress. Autophagy regulates nitroxidative stress to maintain homeostasis within an appropriate range. Intracellular oxidation, in turn, is a strong inducer of autophagy. Toll-like receptor 4 (TLR4) is a pattern recognition receptor mainly involved in the regulation of inflammation during infectious diseases. Several studies have suggested that TLR4 is also a key regulator of autophagy and nitroxidative stress. In this review, we describe the role of TLR4 in autophagy and oxidation, and focus on its function in influencing autophagy-nitroxidative stress interactions.

Bacterial Infections Affect Male Fertility: A Focus on the Oxidative Stress-Autophagy Axis

Numerous factors trigger male infertility, including lifestyle, the environment, health, medical resources and pathogenic microorganism infections. Bacterial infections of the male reproductive system can cause various reproductive diseases. Several male reproductive organs, such as the testicles, have unique immune functions that protect the germ cells from damage. In the reproductive system, immune cells can recognize the pathogen-associated molecular patterns carried by pathogenic microorganisms and activate the host's innate immune response. Furthermore, bacterial infections can lead to oxidative stress through multiple signaling pathways. Many studies have revealed that oxidative stress serves dual functions: moderate oxidative stress can help clear the invaders and maintain sperm motility, but excessive oxidative stress will induce host damage. Additionally, oxidative stress is always accompanied by autophagy which can also help maintain host homeostasis. Male reproductive system homeostasis disequilibrium can cause inflammation of the genitourinary system, influence spermatogenesis, and even lead to infertility. Here, we focus on the effect of oxidative stress and autophagy on bacterial infection in the male reproductive system, and we also explore the crosslink between oxidative stress and autophagy during this process.

The impact of airborne endotoxin exposure on rheumatoid arthritis-related joint damage, autoantigen expression, autoimmunity, and lung disease

Airborne biohazards are risk factors in the development and severity of rheumatoid arthritis (RA) and RA-associated lung disease, yet the mechanisms explaining this relationship remain unclear. Lipopolysaccharide (LPS, endotoxin) is a ubiquitous inflammatory agent in numerous environmental and occupational air pollutant settings recognized to induce airway inflammation. Combining repetitive LPS inhalation exposures with the collagen induced arthritis (CIA) model, DBA1/J mice were assigned to either: sham (saline injection/saline inhalation), CIA (CIA/saline), LPS (saline/LPS 100 ng inhalation), or CIA + LPS for 5 weeks. Serum anti-citrullinated (CIT) protein antibody (ACPA) and anti-malondialdehyde-acetaldehyde (MAA) antibodies were strikingly potentiated with co-exposure (CIA + LPS). CIT- and MAA-modified lung proteins were increased with co-exposure and co-localized across treatment groups. Inhaled LPS exacerbated arthritis with CIA + LPS > LPS > CIA versus sham. Periarticular bone loss was demonstrated in CIA and CIA + LPS but not in LPS alone. LPS induced airway inflammation and neutrophil infiltrates were reduced with co-exposure (CIA + LPS). Potentially signaling transition to pro-fibrotic processes, there were increased infiltrates of activated CD11c+CD11b+ macrophages and transitioning CD11c+CD11bint monocyte-macrophage populations with CIA + LPS. Moreover, several lung remodeling proteins including fibronectin and matrix metalloproteinases as well as complement C5a were potentiated with CIA + LPS compared to other treatment groups. IL-33 concentrations in lung homogenates were enhanced with CIA + LPS with IL-33 lung staining driven by LPS. IL-33 expression was also significantly increased in lung tissues from patients with RA-associated lung disease (N = 8) versus controls (N = 7). These findings suggest that patients with RA may be more susceptible to developing interstitial lung disease following airborne biohazard exposures enriched in LPS.

3-methyadenine inhibits lipopolysaccharides-induced pulmonary inflammation at the early stage of silicosis via blocking NF-κB signaling pathway

Occupational exposure to silica dust is related to pulmonary inflammation and silicosis. Lipopolysaccharides (LPSs) could aggravate apoptosis in alveolar macrophages (AMs) of human silicosis through autophagy, yet how the reduction of autophagy attenuated LPS-induced lung injury and the related mechanisms need to be investigated. In the study, we aim to understand the role of 3-methyladenine (3-MA), an inhibitor of autophagy, in LPS-mediated inflammatory responses and fibrosis. We collected AMs from observers/silicosis patients. The results showed that LPS induced NF-κB-related pulmonary inflammation in observers and silicosis patients, as confirmed by an increase in the expression of IL-1β, IL-6, TNF-α, and p65, which could be inhibited by 3-MA treatment. In mice models, at the early stage (7d) of silicosis, but not the late (28d) stage, blocking autophagy reversed the increased levels of IL-1β, IL-6, TNF-α, and p65 caused by LPS. Mechanism study revealed that LPS triggered the expression of LC3 II, p62, and cleaved caspase-3 at the early stage exposed to silica, which could be restored by 3-MA, while there was no difference in the expression of LAMP1 either at the early or late stage of silicosis in different groups. Similarly, 3-MA treatment did not prevent fibrosis characterized by destroyed alveoli, collagen deposition, and increased expression of α-SMA and Col-1 induced by LPS at the late stage of silicosis. The results suggested that 3-MA has a role in the protection of lung injury at the early stage of silicosis and provided an experimental basis for preventive strategies of pulmonary inflammation and silicosis.

Metformin Attenuates Silica-Induced Pulmonary Fibrosis by Activating Autophagy via the AMPK-mTOR Signaling Pathway

Long-term exposure to crystalline silica particles leads to silicosis characterized by persistent inflammation and progressive fibrosis in the lung. So far, there is no specific treatment to cure the disease other than supportive care. In this study, we examined the effects of metformin, a prescribed drug for type || diabetes on silicosis and explored the possible mechanisms in an established rat silicosis model in vivo, and an in vitro co-cultured model containing human macrophages cells (THP-1) and human bronchial epithelial cells (HBEC). Our results showed that metformin significantly alleviated the inflammation and fibrosis of lung tissues of rats exposed to silica particles. Metformin significantly reduced silica particle-induced inflammatory cytokines including transforming growth factor-β1 (TGF-β1), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in rat lung tissue and HBEC culture supernatant. The protein levels of Vimentin and α-smooth muscle actin (α-SMA) were significantly decreased by metfomin while expression level of E-cadherin (E-Cad) increased. Besides, metformin increased the expression levels of phosphorylated adenosine 5′-monophosphate (AMP)-activated protein kinase (p-AMPK), microtubule-associated protein (MAP) light chain 3B (LC3B) and Beclin1 proteins, and reduced levels of phosphorylated mammalian target of rapamycin (p-mTOR) and p62 proteins in vivo and in vitro. These results suggest that metformin could inhibit silica-induced pulmonary fibrosis by activating autophagy through the AMPK-mTOR pathway.

The Mechanism and Effect of Autophagy, Apoptosis, and Pyroptosis on the Progression of Silicosis

Silicosis remains one of the most severe pulmonary fibrotic diseases worldwide, caused by chronic exposure to silica dust. In this review, we have proposed that programmed cell death (PCD), including autophagy, apoptosis, and pyroptosis, is closely associated with silicosis progression. Furthermore, some autophagy, apoptosis, or pyroptosis-related signaling pathways or regulatory proteins have also been summarized to contribute greatly to the formation and development of silicosis. In addition, silicosis pathogenesis depends on the crosstalk among these three ways of PCD to a certain extent. In summary, more profound research on these mechanisms and effects may be expected to become promising targets for intervention or therapeutic methods of silicosis in the future.

ZBTB28 induces autophagy by regulation of FIP200 and Bcl-XL facilitating cervical cancer cell apoptosis

Background

Among the common preventable cancers of women, cervical cancer has the highest morbidity. It is curable if detected at an early stage. However, reliable diagnostic and prognostic markers, which relate to physiologic and pathologic regulation of cervical cancer, are not available. In this study, one such potential marker, ZBTB28, was evaluated for its potential usefulness in cervical cancer assessment.

Methods

Public database analysis, reverse-transcription polymerase chain reaction (PCR), and methylation-specific PCR were employed to analyze ZBTB28 expression and promoter methylation. The importance of ZBTB28 in cervical cancer cells was assessed by cellular and molecular analysis in vitro and in vivo.

Results

This study assessed the anti-tumor effects of the transcription factor, ZBTB28, which is often silenced in cervical cancer due to CpG methylation of its promoter. We found ZBTB28 to directly affect cervical cancer cell proliferation, apoptosis, autophagy, and tumorigenesis. Also, it increased cancer cell chemosensitivity to Paclitaxel, Cisplatin, and 5-fluorouracil. Ectopic ZBTB28 expression inhibited the growth of cervical cancer xenografts in nude mice. Furthermore, electron microscopy demonstrated ZBTB28 to induce autophagosomes in cervical cancer cells. ZBTB28 induced cellular autophagy by the degradation of Bcl-XL, reduction of the Bcl-XL-BECN1 complex, and by interaction with the autophagy-related gene FIP200. ZBTB28-induced autophagy of cervical cancer cells was shown to mediate cellular apoptosis through the regulation of FIP200.

Conclusion

These findings identify ZBTB28 as a tumor suppressor gene that can induce autophagy-related apoptosis in cervical cancer cells. As such, ZBTB28 may be a target for the treatment of uterine-cervical carcinoma. Further, ZBTB28 promoter methylation analysis may offer a new objective strategy for cervical cancer screening.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01948-0.

Capsaicin protects cardiomyocytes against lipopolysaccharide-induced damage via 14-3-3γ-mediated autophagy augmentation

Background: The myocardium is susceptible to lipopolysaccharide (LPS)-induced damage in sepsis, and cardiac dysfunction is a leading cause of mortality in patients with sepsis. The changes in cardiomyocyte autophagy in sepsis and the effects and mechanism of action of capsaicin (Cap) remain unclear.

Methods and Results: The potential pathway of 14-3-3γ-dependent autophagy and the effects and mechanisms of Cap were studied in LPS-induced injury to primary cultured neonatal rat cardiomyocytes. The results showed that cardiomyocyte viability decreased, lactate dehydrogenase and creatine kinase activities increased, 14-3-3γ expression was downregulated, and autophagy was inhibited after LPS challenge. Cap pretreatment augmented autophagy by upregulating 14-3-3γ expression and activating AMP-activated protein kinase (AMPK) and unc-51 like autophagy-activating kinase 1 (ULK1), suppressing mammalian target of rapamycin (mTOR), alleviating cardiac dysfunction and improving the inflammation response, whereas pAD/14-3-3γ-shRNA nullified the above effects. Cap pretreatment also decreased the levels of IL-1β, TNF-α, IL-6, and IL-10; suppressed intracellular oxidative stress; reduced the intracellular/mitochondrial reactive oxygen species (ROS); balanced GSH/GSSG; increased GSH-Px, catalase, and SOD activities; and decreased MDA contents. It also increased ATP content, activated complex Ⅰ and complex Ⅲ, stabilized the mitochondrial membrane potential, and decreased the mitochondrial permeability transition pore opening, thereby improving mitochondrial function.

Conclusion: Pretreatment with Cap can regulate autophagy by upregulating 14-3-3γ expression, inhibiting oxidative stress and inflammation, maintaining mitochondrial function, and protecting cardiomyocytes against LPS-induced injury.

DDRGK1, a crucial player of ufmylation system, is indispensable for autophagic degradation by regulating lysosomal function

DDRGK domain-containing protein 1 (DDRGK1) is an important component of the newly discovered ufmylation system and its absence has been reported to induce extensive endoplasmic reticulum (ER) stress. Recently, emerging evidence indicates that the ufmylation system is correlated with autophagy, although the exact mechanism remains largely unknown. To explore the regulation mechanism of DDRGK1 on autophagy, in this study, we established an immortalized mouse embryonic fibroblast (MEF) cell lines harvested from the DDRGK1F/F:ROSA26-CreERT2 mice, in which DDRGK1 depletion can be induced by 4-hydroxytamoxifen (4-OHT) treatment. Here, we show that DDRGK1 deficiency in MEFs has a dual effect on autophagy, which leads to a significant accumulation of autophagosomes. On one hand, it promotes autophagy induction by impairing mTOR signaling; on the other hand, it blocks autophagy degradation by inhibiting autophagosome-lysosome fusion. This dual effect of DDRGK1 depletion on autophagy ultimately aggravates apoptosis in MEFs. Further studies reveal that DDRGK1 loss is correlated with suppressed lysosomal function, including impaired Cathepsin D (CTSD) expression, aberrant lysosomal pH, and v-ATPase accumulation, which might be a potential trigger for impairment in autophagy process. Hence, this study confirms a crucial role of DDRGK1 as an autophagy regulator by controlling lysosomal function. It may provide a theoretical basis for the treatment strategies of various physiological diseases caused by DDRGK1 deficiency.

Taurine Antagonizes Macrophages M1 Polarization by Mitophagy-Glycolysis Switch Blockage via Dragging SAM-PP2Ac Transmethylation

The excessive M1 polarization of macrophages drives the occurrence and development of inflammatory diseases. The reprogramming of macrophages from M1 to M2 can be achieved by targeting metabolic events. Taurine promotes for the balance of energy metabolism and the repair of inflammatory injury, preventing chronic diseases and complications. However, little is known about the mechanisms underlying the action of taurine modulating the macrophage polarization phenotype. In this study, we constructed a low-dose LPS/IFN-γ-induced M1 polarization model to simulate a low-grade pro-inflammatory process. Our results indicate that the taurine transporter TauT/SlC6A6 is upregulated at the transcriptional level during M1 macrophage polarization. The nutrient uptake signal on the membrane supports the high abundance of taurine in macrophages after taurine supplementation, which weakens the status of methionine metabolism, resulting in insufficient S-adenosylmethionine (SAM). The low availability of SAM is directly sensed by LCMT-1 and PME-1, hindering PP2Ac methylation. PP2Ac methylation was found to be necessary for M1 polarization, including the positive regulation of VDAC1 and PINK1. Furthermore, its activation was found to promote the elimination of mitochondria by macrophages via the mitophagy pathway for metabolic adaptation. Mechanistically, taurine inhibits SAM-dependent PP2Ac methylation to block PINK1-mediated mitophagy flux, thereby maintaining a high mitochondrial density, which ultimately hinders the conversion of energy metabolism to glycolysis required for M1. Our findings reveal a novel mechanism of taurine-coupled M1 macrophage energy metabolism, providing novel insights into the occurrence and prevention of low-grade inflammation, and propose that the sensing of taurine and SAM availability may allow communication to inflammatory response in macrophages.

Dahuang Zhechong Pills Suppress Silicosis Fibrosis Progression via p38 MAPK/TGF-β1/Smad Pathway In Vitro

Background

Dahuang Zhechong pills (DHZCP) is a classic Chinese medicinal prescription in “Treatise on Cold Pathogenic and Miscellaneous Diseases (Shanghan Zabing Lun),” and it has the function of tonifying blood, nourishing Yin, and removing blood stasis. Previous studies have shown that DHZCP could alleviate SiO₂ induced pulmonary fibrosis in mice. This study aims to further explore the preventive and therapeutic effects of DHZCP against silicosis fibrosis and the underlying mechanisms in vitro.

Methods

We used the experimental model of SiO₂-induced MH-S cells to evaluate the therapeutic potential of DHZCP. MH-S cells induced by SiO₂ were intervened with the drug-containing serum of DHZCP, and the effects of drug-containing serum of DHZCP on the MH-S cells were detected by CCK8, ELISA, flow cytometry, western blot, and immunofluorescence.

Results

DHZCP improved cell viability by reducing apoptosis. It also decreased the levels of TNF-α, IL-1β, IL-6 in the supernatant of MH-S cells induced by SiO₂, inhibited the expression of p38 MAPK, blocked the activation of NF-κB, and controlled the upstream inflammatory response by multiple targeting. Concomitantly, we observed upregulation of Smad7 and a marked decline in TGF-β1, α-SMA, Smad2, Smad3 expression in MH-S cells treated with DHZCP.

Conclusion

To sum up, we conclude that DHZCP protects against SiO₂-induced silicosis by reducing the persistent irritation of inflammation, regulating the p38 MAPK/TGF-β1/Smad pathway.

Hirsutella sinensis mycelium regulates autophagy of alveolar macrophages via TLR4/NF-κB signaling pathway

Background: Hirsutella sinensis mycelium (HSM) has potent anti-pulmonary fibrotic activities and has been proposed as an effective treatment for idiopathic pulmonary fibrosis. Macrophages are the main innate immune cells in the lung tissue, playing key roles in pulmonary fibrosis repair and homeostasis. Excessive macrophage autophagy plays a vital role in pulmonary fibrosis. The protective effect of HSM on macrophages of bleomycin (BLM)-induced pulmonary fibrotic mice remain unclear. Methods: In this study, we collected lung tissue and bronchoalveolar lavage fluid (BALF) samples from pulmonary fibrotic mice. Meanwhile, alveolar macrophages were isolated and murine macrophage RAW264.7 cell line was cultured for further study of HSM autophagy. Results: First, we found that HSM decreased the number of autophagosomes, as well as the levels of LC3B and ATG5, and increased the protein level of P62 during the development of pulmonary fibrosis. Meanwhile, HSM reduced alveolar macrophages infiltration into the BALF and inhibited their accumulation in the fibrotic lung tissue. Flow cytometry analysis showed that HSM administration inhibited the autophagy marker LC3B expression in CD11bloCD11chi alveolar macrophages in BLM-induced lung fibrosis without affecting CD11bhiCD11clo interstitial macrophages. Transmission electron microscopy and JC-1 staining for mitochondrial membrane potential of alveolar macrophages also verified that the HSM significantly decreased autophagy in the alveolar macrophages of BLM-treated mice. In vitro, autophagosomes-lysosome fusion inhibitor chloroquine (CQ) was pre-incubated with RAW264.7 cells, and HSM reduced CQ-induced autophagosomes accumulation. TLR4 signaling inhibitor CLI095 reversed the above effects, suggesting HSM could reduce the cumulation of autophagosomes dependent on TLR4. Furthermore, lipopolysaccharide (LPS)-stimulated TLR4-related autophagy was significantly inhibited by HSM treatment. In addition, the protein expressions of TLR4 and phospho-NF-κB p65 were markedly inhibited in cells treated with HSM. Conclusions: These results indicated that HSM could inhibit the autophagy of alveolar macrophages through TLR4/NF-κB signaling pathway to achieve anti-fibrotic effect.

Macrophage autophagy protects mice from cerium oxide nanoparticle-induced lung fibrosis

BACKGROUND

Cerium (Ce) is a rare earth element, rapidly oxidizing to form CeO2, and currently used in numerous commercial applications, especially as nanoparticles (NP). The potential health effects of Ce remain uncertain, but literature indicates the development of rare earth pneumoconiosis accompanied with granuloma formation, interstitial fibrosis and inflammation. The exact underlying mechanisms are not yet completely understood, and we propose that autophagy could be an interesting target to study, particularly in macrophages. Therefore, the objective of our study was to investigate the role of macrophagic autophagy after pulmonary exposure to CeO2 NP in mice. Mice lacking the early autophagy gene Atg5 in their myeloid lineage and their wildtype counterparts were exposed to CeO2 NP by single oropharyngeal administration and sacrificed up to 1 month after. At that time, lung remodeling was thoroughly characterized (inflammatory cells infiltration, expression of fibrotic markers such as αSMA, TGFβ1, total and type I and III collagen deposition), as well as macrophage infiltration (quantification and M1/M2 phenotype).

RESULTS

Such pulmonary exposure to CeO2 NP induces a progressive and dose-dependent lung fibrosis in the bronchiolar and alveolar walls, together with the activation of autophagy. Blockage of macrophagic autophagy protects from alveolar but not bronchiolar fibrosis, via the modulation of macrophage polarization towards M2 phenotype.

CONCLUSION

In conclusion, our findings bring novel insight on the role of macrophagic autophagy in lung fibrogenesis, and add to the current awareness of pulmonary macrophages as important players in the disease.

Roles of circRNAs on tumor autophagy

Circular RNAs (circRNAs) are a type of special noncoding RNA. circRNAs are highly stable and are found mainly in the cytoplasm. Most circRNAs are conserved and usually exhibit tissue specificity and timing specificity. In addition to the regulation mode of competitive endogenous RNA (ceRNA), circRNAs can also bind to RNA-binding proteins (RBPs), regulate alternative splicing, encode proteins or polypeptides, and regulate the expression of parent genes affecting biological pathways in which coded proteins are involved. Autophagy is an important cellular mechanism that plays an essential role in normal cell physiological processes and in diseases, especially tumors. Studies reported that circRNAs have an important effect on autophagic processes. What are the detailed biological functions and mechanisms of circRNAs in autophagy? In this article, we summarize the relationship between circRNAs and autophagy and the regulatory function and mechanism (especially as microRNA [miRNA] sponges and binding to RBPs) of circRNAs in autophagy. In addition, we discuss the dysregulation and functional and clinical applications of autophagy-associated circRNAs in a variety of diseases. Autophagy-associated circRNAs have the potential to be essential biomarkers of diagnosis and treatment and to be beneficial to the research and development of targeted drugs for tumor or non-tumor diseases.

Macrophage Autophagy and Silicosis: Current Perspective and Latest Insights

Silicosis is an urgent public health problem in many countries. Alveolar macrophage (AM) plays an important role in silicosis progression. Autophagy is a balanced mechanism for regulating the cycle of synthesis and degradation of cellular components. Our previous study has shown that silica engulfment results in lysosomal rupture, which may lead to the accumulation of autophagosomes in AMs of human silicosis. The excessive accumulation of autophagosomes may lead to apoptosis in AMs. Herein, we addressed some assumptions concerning the complex function of autophagy-related proteins on the silicosis pathogenesis. We also recapped the molecular mechanism of several critical proteins targeting macrophage autophagy in the process of silicosis fibrosis. Furthermore, we summarized several exogenous chemicals that may cause an aggravation or alleviation for silica-induced pulmonary fibrosis by regulating AM autophagy. For example, lipopolysaccharides or nicotine may have a detrimental effect combined together with silica dust via exacerbating the blockade of AM autophagic degradation. Simultaneously, some natural product ingredients such as atractylenolide III, dioscin, or trehalose may be the potential AM autophagy regulators, protecting against silicosis fibrosis. In conclusion, the deeper molecular mechanism of these autophagy targets should be explored in order to provide feasible clues for silicosis therapy in the clinical setting.

Multi-omics study of silicosis reveals the potential therapeutic targets PGD2 and TXA2

Rationale: Silicosis is a severe occupational lung disease. Current treatments for silicosis have highly limited availability (i.e., lung transplantation) or, do not effectively prolong patient survival time (i.e., lung lavage). There is thus an urgent clinical need for effective drugs to retard the progression of silicosis.

Methods: To systematically characterize the molecular changes associated with silicosis and to discover potential therapeutic targets, we conducted a transcriptomics analysis of human lung tissues acquired during transplantation, which was integrated with transcriptomics and metabolomics analyses of silicosis mouse lungs. The results from the multi-omics analyses were then verified by qPCR, western blot, and immunohistochemistry. The effect of Ramatroban on the progression of silicosis was evaluated in a silica-induced mouse model.

Results: Wide metabolic alterations were found in lungs from both human patients and mice with silicosis. Targeted metabolite quantification and validation of expression of their synthases revealed that arachidonic acid (AA) pathway metabolites, prostaglandin D₂ (PGD₂) and thromboxane A₂ (TXA₂), were significantly up-regulated in silicosis lungs. We further examined the effect of Ramatroban, a clinical antagonist of both PGD₂ and TXA₂ receptors, on treating silicosis using a mouse model. The results showed that Ramatroban significantly alleviated silica-induced pulmonary inflammation, fibrosis, and cardiopulmonary dysfunction compared with the control group.

Conclusion: Our results revealed the importance of AA metabolic reprogramming, especially PGD₂ and TXA₂ in the progression of silicosis. By blocking the receptors of these two prostanoids, Ramatroban may be a novel potential therapeutic drug to inhibit the progression of silicosis.

[Role of autophagy in lipopolysaccharide-induced apoptosis of odontoblasts]

OBJECTIVE

To investigate the role of autophagy in lipopolysaccharide (LPS)-induced apoptosis of murine odontoblasts.

METHODS

Murine odontoblasts (mDPC-23 cells) were treated with 5 μg/mL LPS for 6, 12 and 24 h, and the changes in cell viability was examined using CCK8 kit and cell apoptosis was detected by TUNEL staining. The changes in the protein levels of LC3, Beclin1, Atg5, AKT, p-AKT, mTOR and p-mTOR were detected using Western blotting. The effect of 3-MA treatment for 24 h on LPS-induced apoptosis of mDPC-23 cells was evaluated by detecting the expressions of apoptosis-related proteins caspase-3 and Bax using Western blotting.

RESULTS

Stimulation with LPS for 6 and 12 h did not cause significant changes in the proliferation or apoptosis of mDPC-23 cells, but LPS treatment for 24 h significantly suppressed cell proliferation (P < 0.05) and promoted cell apoptosis as shown by TUNEL assay (P < 0.05). Stimulation with LPS for 24 significantly increased the expression levels of LC3, Beclin1 and Atg5, decreased the expressions of p-AKT and p-mTOR (P < 0.05), and obviously upregulated the expressions of caspase-3 and Bax (P < 0.05). Treatment with 3-MA markedly lowered caspase-3 and Bax protein expressions in LPS-stimulated cells (P < 0.05).

CONCLUSIONS

LPS stimulation induces autophagy to promote apoptosis of mDPC-23 cells, and suppression of autophagy attenuates LPS-induced apoptosis. Autophagy may play an important role in the injury of inflamed pulp tissues.

Gas6 or Mer deficiency ameliorates silica-induced autophagosomes accumulation in mice lung

Published evidences have shown that autophagy plays an important role in silica-induced lung inflammation and collagen deposition. Our previous study found that the level of growth arrest-specific protein 6 (Gas6) in bronchoalveolar lavage fluid was increased after silica exposure. However, it is unclear whether Gas6 is involved in the regulation of silica-induced autophagy dysfunction. In this study, we observed an autophagosomes accumulation in wild-type C57BL/6 (WT) mice lung after silica intratracheal instillation and then investigated whether genetic loss of Gas6 (Gas6^-/-) could ameliorate it. Our data showed that Gas6^-/- mice exhibited a limited autophagosomes accumulation from days 7-84 after silica exposure, revealed by reduced induction and increased degradation of autophagosomes in mice lung tissue. Interestingly, silica particles could elevate the expression of Mer receptor, which was significantly decreased in Gas6^-/- mice (P < 0.05). Furthermore, we found that Mer deficiency (Mer^-/-) could also reduce the formation of autophagosomes and restore the function of impaired lysosomes in silica-treated mice. Taken together, our results indicate that genetic loss of Gas6 attenuates silica-induced autophagosomes accumulation partly through down-regulating the expression of Mer receptor. Targeting Gas6/Mer-mediated autophagy pathway may provide a novel insight into the prevention and therapy of silica-induced pulmonary fibrosis.

Atractylenolide III alleviates the apoptosis through inhibition of autophagy by the mTOR-dependent pathway in alveolar macrophages of human silicosis

Silica-induced apoptosis of alveolar macrophages (AMs) is an essential part of silicosis formation. Autophagy tends to present a bidirectional effect on apoptosis. Our previous study found that the blockade of autophagy degradation might aggravate the apoptosis of AMs in human silicosis. We presume that targeting the autophagic pathway is regarded as a promising new strategy for silicosis fibrosis. As a main active component of the Atractylodes rhizome, Atractylenolide III (ATL-III) has been widely applied in clinical anti-inflammation. However, the effect and mechanism of ATL-III on autophagy in AMs of silicosis are unknown. In this study, we found that ATL-III might inhibit autophagy by mTOR-dependent manner, thereby improving the blockage of autophagic degradation in AMs. ATL-III alleviated the apoptosis of AMs in human silicosis. Furthermore, Rapamycin reversed the protective effect of ATL-III in AMs. These results indicate that ATL-III may be a potentially protective ingredient targeting autophagy for workers exposed to silica dust. These findings also suggest that inhibition of autophagy may be an effective way to alleviate the apoptosis of AMs in silicosis.

Nicotine induces apoptosis through exacerbation of blocked alveolar macrophage autophagic degradation in silicosis

Silica dust mainly attacks alveolar macrophages (AMs). The apoptosis of AMs is correlated with the progress of silicosis. Our previous study showed that autophagic degradation was blocked in AMs from silicosis patients. However, the effects of nicotine on AM autophagy and apoptosis in silicosis are unknown. In this study, we collected AMs from twenty male workers exposed to silica and divided them into observer and silicosis patient groups, according to the tuberous pathological changes observed by X-ray. The AMs from both groups were exposed to nicotine. We found increased levels of LC3, p62, and cleaved caspase-3, decreased levels of LAMP2, and damaged lysosomes after nicotine stimulation of the AMs from both groups. We also found that the autophagy inhibitor 3-methyladenine (3MA) inhibited nicotine-induced apoptosis in the AMs. Furthermore, 3MA reversed both the nicotine-induced decrease in Bcl-2 and the increase in Bax in both groups. These results suggest that nicotine may induce apoptosis by blocking AM autophagic degradation in human silicosis.

Urocortin participates in LPS-induced apoptosis of THP-1 macrophages via S1P-cPLA2 signaling pathway

There is little literature showing the effect of urocortin (UCN) on macrophage apoptosis. The underlying mechanism is also unclear. This work was to investigate the involvement of UCN in the regulation of LPS-induced macrophage apoptosis and hence in the prevention from the atherosclerotic lesion development through targeting PLA2. Flow cytometry analysis showed that cell apoptosis was increased by more than 50% after LPS treatment in human THP-1 macrophage. Lp-PLA2 and cPLA2 were found to mediate LPS-induced macrophage apoptosis and NF-κB differentially influenced the expression of Lp-PLA2 and cPLA2. However, the reverse regulation of the expression of Lp-PLA2 and cPLA2 by NF-κB suggested that NF-κB may not be a key target for regulating macrophage apoptosis. Interestingly, we found that the approximate three folds upregulation of cPLA2 was in line with the induction of S1P formation and cell apoptosis by LPS. Inversely, LPS obviously decreased UCN expression by about 50% and secretion by about 25%. Both the enzyme inhibitor and knockdown expression of cPLA2 could completely abolish LPS-induced cell apoptosis. In addition, suppression of S1P synthesis by Sphk1 inhibitor PF-543 reduced the expression of cPLA2 and cell apoptosis but at the same time restored the normal level of UCN in cell culture supernatant. Furthermore, addition of exogenous UCN also reversed LPS-induced expression of cPLA2 and apoptosis. Taken together, UCN may be the reverse regulator of LPS-S1P-cPLA2-apoptosis pathway, thereby contributing to the prevention from the formation of unstable plaques.

Trehalose alleviates apoptosis by protecting the autophagy-lysosomal system in alveolar macrophages during human silicosis

BACKGROUND

Alveolar macrophages (AMs) are the primary targets of silicosis. Blockade of autophagy may aggravate the apoptosis of AMs. Trehalose (Tre), a transcription factor EB (TFEB) activator, may impact the autophagy-lysosomal system in AMs during silicosis. However, the mechanism by which Tre acts upon AMs in silicosis is unknown.

METHODS

We collected AMs from twenty male workers exposed to silica and divided them into observer and silicosis patient groups. AMs from the two groups were then exposed to Tre. Western blot was used to measure the expression of autophagy-associated proteins. Lysosomal-associated membrane protein 1 (LAMP1) expression was observed using immunofluorescence and western blot. Apoptosis of the AMs was detected by TUNEL assay and western blot.

RESULTS

Tre induced localization of TFEB to the nucleus in the AMs of both groups. After Tre exposure, LAMP1 levels increased and LC3 levels decreased in the AMs of both groups, suggesting that Tre may increase the function of the autophagy-lysosomal system. The LC3-II/I ratio in the Tre-exposed AMs was lower than in the AMs not exposed to Tre. The LC3-II/I ratio in AMs subjected to Tre plus Bafilomycin (Baf) was higher than the ratio in cells exposed to Tre or Baf individually. Additionally, p62 levels decreased after Tre stimulation in the AMs of both groups. This indicates that Tre may accelerate the process of autophagic degradation. We also found decreased levels of cleaved caspase-3 after Tre treatment in the AMs of both groups. However, p-mTOR (Ser2448) and p-mTOR (Ser2481) levels did not change significantly after Tre treatment, suggesting that the mTOR signaling pathway was not affected by Tre treatment.

CONCLUSION

Our findings suggest that the restoration of autophagy-lysosomal function by Tre may be a potential protective strategy against silicosis.

Lipopolysaccharides promote pulmonary fibrosis in silicosis through the aggravation of apoptosis and inflammation in alveolar macrophages

Alveolar macrophages (AMs) play an important defensive role by removing dust and bacteria from alveoli. Apoptosis of AMs is associated with lung fibrosis; however, the relationship between this apoptotic event and environmental factors, such as the presence of lipopolysaccharides (LPSs) in the workplace, has not yet been addressed. To investigate whether exposure to LPS can exacerbate fibrosis, we collected AMs from 12 male workers exposed to silica and incubated them in the presence and absence of LPS for 24 h. We show that the levels of cleaved caspase-3 and pro-inflammatory cytokines interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha were increased in these AMs following LPS treatment. Moreover, we demonstrate that LPS exposure aggravated apoptosis and the release of inflammatory factors in AMs in a mouse model of silicosis, which eventually promoted pulmonary fibrosis. These results suggest that exposure to LPS may accelerate the progression of pulmonary fibrosis in silicosis by increasing apoptosis and inflammation in AMs.

Silica dust exposure induces autophagy in alveolar macrophages through switching Beclin1 affinity from Bcl-2 to PIK3C3

Increased deposition of silica dust in pulmonary interstitial tissues leads to silicosis, in which autophagy plays a defensive role in silica dust-associated stress response and cell death. Our previous studies revealed that silica dust exposure contributed to autophagy in pulmonary macrophages in vivo, while the specific regulatory mechanism is still unclear. This study aimed to figure out the regulatory mechanism as well as the role of autophagy in the pathogenesis of experimental silicosis. We used 3-methyladenine (3-MA) and ABT-737 to suppress the expression of phosphatidylinositol 3-kinase catalytic subunit type 3 (PIK3C3) and B cell leukemia/lymphoma 2 (Bcl-2), two critical initiators of autophagy, and detected and evaluated the autophagy in NR8383 cells with or without silica dust exposure. We found that exposure of silica dust increased autophagy in NR8383 cells and elevated the expression of Beclin1 and PIK3C3, but it reduced the expression of Bcl-2. The relationship among Beclin1, PIK3C3, and Bcl-2 were then investigated using immunoprecipitation analysis, and we found that suppression of PIK3C3 and/or Bcl-2 using 3-MA and/or ABT-737 could alter the autophagy induced by silica dust in NR8383 cells, and the complexes of Beclin1/PIK3C3 and Beclin1/Bcl-2 were both downregulated, which may be that inhibition of PIK3C3 and Bcl-2 altered the affinity of Beclin1 with PIK3C3 and Bcl-2 and lead to the silence of PIK3C3 signaling. These findings indicate that silica dust exposure induces autophagy via changing the connectivity of Beclin1 from Bcl-2 to PIK3C3.

Triiodothyronine Attenuates Silica-Induced Oxidative Stress, Inflammation, and Apoptosis via Thyroid Hormone Receptor α in Differentiated THP-1 Macrophages

Alveolar macrophage (AM) injury and inflammatory response are key processes in pathological damage caused by silica. However, the role of triiodothyronine (T3) in silica-induced AM oxidative stress, inflammation, and mitochondrial apoptosis remained unknown. To investigate the possible effects and underlying mechanism of T3 in silica-induced macrophage damage, differentiated human acute monocytic leukemia cells (THP-1) were exposed to different silica concentrations (0, 50, 100, 200, and 400 μg/mL) for 24 h. Additionally, silica-activated THP-1 macrophages were treated with gradient-dose T3 (0, 5, 10, 20, and 40 nM) for 24 h. To illuminate the potential mechanism, we used short hairpin RNA to knock down the thyroid hormone receptor α (TRα) in the differentiated THP-1 macrophages. The results showed that T3 decreased lactate dehydrogenase and reactive oxygen species levels, while increasing cell viability and superoxide dismutase in silica-induced THP-1 macrophages. In addition, silica increased the expression of interleukin 1 beta (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α), and T3 treatment reduced those pro-inflammatory cytokines secretion. Compared with silica-alone treated groups, cells treated with silica and T3 restored the mitochondrial membrane potential loss and had reduced levels of cytochrome c and cleaved caspase-3 expressions. Lastly, we observed that TRα-knockdown inhibited the protective effects of T3 silica-induced THP-1 macrophages. Together, these findings revealed that T3 could serve as a potential therapeutic target for protection against silica-induced oxidative stress, inflammatory response, and mitochondrial apoptosis, which are mediated by the activation of the T3/TRα signal pathway.

The Lipid Virulence Factors of Mycobacterium tuberculosis Exert Multilayered Control over Autophagy-Related Pathways in Infected Human Macrophages

Autophagy is an important innate immune defense mechanism that controls Mycobacterium tuberculosis (Mtb) growth inside macrophages. Autophagy machinery targets Mtb-containing phagosomes via xenophagy after damage to the phagosomal membrane due to the Type VII secretion system Esx-1 or via LC3-associated phagocytosis without phagosomal damage. Conversely, Mtb restricts autophagy-related pathways via the production of various bacterial protein factors. Although bacterial lipids are known to play strategic functions in Mtb pathogenesis, their role in autophagy manipulation remains largely unexplored. Here, we report that the lipid virulence factors sulfoglycolipids (SLs) and phthiocerol dimycocerosates (DIMs) control autophagy-related pathways through distinct mechanisms in human macrophages. Using knock-out and knock-in mutants of Mtb and Mycobacterium bovis BCG (Bacille Calmette Guerin) and purified lipids, we found that (i) Mtb mutants with DIM and SL deficiencies promoted functional autophagy via an MyD88-dependent and phagosomal damage-independent pathway in human macrophages; (ii) SLs limited this pathway by acting as TLR2 antagonists; (iii) DIMs prevented phagosomal damage-independent autophagy while promoting Esx-1-dependent xenophagy; (iv) and DIMs, but not SLs, limited the acidification of LC3-positive Mtb compartments. In total, our study reveals an unexpected and intricate role for Mtb lipid virulence factors in controlling autophagy-related pathways in human macrophages, thus providing further insight into the autophagy manipulation tactics deployed by intracellular bacterial pathogens.

Effects of tetrandrine combined with acetylcysteine on exercise tolerance, pulmonary function and serum TNF-β1 and MMP-7 in silicosis patients

The aim of the study was to investigate the effects of tetrandrine combined with acetylcysteine on exercise tolerance, pulmonary function, transforming growth factor-β1 (TGF-β1) and matrix metalloproteinase 7 (MMP-7) in silicosis patients. A retrospective analysis was performed on 149 silicosis patients admitted to the Maternal and Child Health Care Hospital of Zhangqiu District between August, 2015 and September, 2017. Of the 149 patients, 70 patients treated with acetylcysteine comprised the control group, and 79 treated with tetrandrine combined with acetylcysteine constituted the study group. The concentrations of serum TGF-β1 and MMP-7 before and after treatment were detected by enzyme-linked immunosorbent assay (ELISA), and the exercise tolerance and pulmonary function were compared. Chest distress, chest pain, cough, expectoration and dyspnea in the two groups were relieved after treatment, and the improvement rates of chest distress, chest pain and dyspnea in the study group were significantly higher than those in the control group (P<0.05). Before treatment, there was no significant difference in the results of the 6-minute walk test (6MWT) between the two groups (P>0.05). After treatment, the 6MWT in the two groups was significantly increased (P<0.05), and the improvement effect in the study group was more marked than that in the control group (P<0.05). There was no significant difference in the pulmonary function indexes between the two groups before treatment (P>0.05). Before treatment, there was no significant difference in serum TGF-β1 and MMP-7 expression levels between the two groups (P>0.05). By contrast, after treatment, the levels in the two groups were significantly decreased, with the levels in the study group being significantly lower than that the control group (P<0.05). In conclusion, tetrandrine combined with acetylcysteine can improve pulmonary function and exercise tolerance of patients with silicosis by inhibiting the expressions of TGF-β1 and MMP-7, thus improving clinical efficacy.

Trehalose Alleviates Crystalline Silica-Induced Pulmonary Fibrosis via Activation of the TFEB-Mediated Autophagy-Lysosomal System in Alveolar Macrophages

Silicosis is an occupational lung disease characterized by persistent inflammation and irreversible fibrosis. Crystalline silica (CS) particles are mainly phagocytized by alveolar macrophages (AMs), which trigger apoptosis, inflammation, and pulmonary fibrosis. Previously, we found that autophagy-lysosomal system dysfunction in AMs was involved in CS-induced inflammation and fibrosis. Induction of autophagy and lysosomal biogenesis by transcription factor EB (TFEB) nuclear translocation can rescue fibrotic diseases. However, the role of TFEB in silicosis is unknown. In this study, we found that CS induced TFEB nuclear localization and increased TFEB expression in macrophages both in vivo and in vitro. However, TFEB overexpression or treatment with the TFEB activator trehalose (Tre) alleviated lysosomal dysfunction and enhanced autophagic flux. It also reduced apoptosis, inflammatory cytokine levels, and fibrosis. Both pharmacologically inhibition of autophagy and TFEB knockdown in macrophages significantly abolished the antiapoptotic and anti-inflammatory effects elicited by either TFEB overexpression or Tre treatment. In conclusion, these results uncover a protective role of TFEB-mediated autophagy in silicosis. Our study suggests that restoration of autophagy-lysosomal function by Tre-induced TFEB activation may be a novel strategy for the treatment of silicosis.