Dioscin Exerts Protective Effects Against Crystalline Silica-induced Pulmonary Fibrosis in Mice

Crystalline silica-induced endoplasmic reticulum stress promotes the pathogenesis of silicosis by augmenting proinflammatory interstitial pulmonary macrophages

Crystalline silica (CS) particles are ubiquitously present in the environment, particularly in occupational settings, and exposure to respirable CS causes silicosis, imposing a significant disease burden. However, the pathogenesis of silicosis remains unclear. Exposure to external stimuli, such as CS, leads to the accumulation of unfolded proteins and triggers endoplasmic reticulum (ER) stress, disrupting tissue immune homeostasis and accelerating pathological progression. While pulmonary macrophages phagocytose CS particles to initiate the immune response, the role of ER stress in this process is unknown. Herein, we used a murine model of silicosis to simulate the pathological progression from acute inflammation to fibrosis in silicosis and conducted in vivo pharmacological inhibition of ER stress to explore the underlying mechanism. Using flow cytometry, we further classified pulmonary macrophages into monocyte-like macrophages (monocytes), interstitial macrophages (IMs), and alveolar macrophages (AMs). Our results showed that CS-induced ER stress primarily contributed to the augmentation of IMs and thereby exerted a significant impact on pulmonary macrophages. Despite coexpressing M1- and M2-like markers, IMs predominantly exhibited an M1-like polarization state and played a proinflammatory role by expressing the cytokines pro-IL-1β and TNF-α during the pathological progression of silicosis. Additionally, IMs recruited by CS-induced ER stress also exhibited high expression of MHCII and exerted active immunomodulatory effects. Overall, our study demonstrates that ER stress induced by CS particles triggers a proinflammatory immune microenvironment dominated by IMs and reveals novel insights into the pulmonary toxicological effects of CS particles.

Crystalline silica-induced recruitment and immuno-imbalance of CD4+ tissue resident memory T cells promote silicosis progression

Occupational crystalline silica (CS) particle exposure leads to silicosis. The burden of CS-associated disease remains high, and treatment options are limited due to vague mechanisms. Here we show that pulmonary CD4+ tissue-resident memory T cells (TRM) accumulate in response to CS particles, mediating the pathogenesis of silicosis. The TRM cells are derived from peripheral lymphocyte recruitment and in situ expansion. Specifically, CD69+CD103+ TRM-Tregs depend more on circulating T cell replenishment. CD69 and CD103 can divide the TRM cells into functionally distinct subsets, mirroring the immuno-balance within CD4+ TRM cells. However, targeting CD103+ TRM-Tregs do not mitigate disease phenotype since the TRM subsets exert immunosuppressive but not pro-fibrotic roles. After identifying pathogenic CD69+CD103- subsets, we highlight IL-7 for their maintenance and function, that present a promising avenue for mitigating silicosis. Together, our findings highlight the distinct role of CD4+ TRM cells in mediating CS-induced fibrosis and provide potential therapeutic strategies.

Nintedanib and miR-29b co-loaded lipoplexes in idiopathic pulmonary fibrosis: formulation, characterization, and in vitro evaluation

OBJECTIVE

This study was aimed to develop a cationic lipoplex formulation loaded with Nintedanib and miR-29b (LP-NIN-miR) as an alternative approach in the combination therapy of idiopathic pulmonary dibrosis (IPF) by proving its additive anti-fibrotic therapeutic effects through in vitro lung fibrosis model.

SIGNIFICANCE

This is the first research article reported that the LP-NIN-MIR formulations in the treatment of IPF.

METHODS

To optimize cationic liposomes (LPs), quality by design (QbD) approach was carried out. Optimized blank LP formulation was prepared with DOTAP, CHOL, DOPE, and DSPE-mPEG 2000 at the molar ratio of 10:10:1:1. Nintedanib loaded LP (LPs-NIN) were produced by microfluidization method and were incubated with miR-29b at room temperature for 30 min to obtain LP-NIN-miR. To evaluate the cellular uptake of LP-NIN-miR, NIH/3T3 cells were treated with 20 ng.mL-1 transforming growth factor-β1 (TGF-β1) for 96 h to establish the in vitro IPF model and incubated with LP-NIN-miR for 48 h.

RESULTS

The hydrodynamic diameter, polydispersity index (PDI), and zeta potential of the LP-NIN-miR were 87.3 ± 0.9 nm, 0.184 ± 0.003, and +24 ± 1 mV, respectively. The encapsulation efficiencies of Nintedanib and miR-29b were 99.8% ± 0.08% and 99.7% ± 1.2%, respectively. The results of the cytotoxicity study conducted with NIH/3T3 cells indicated that LP-NIN-miR is a safe delivery system.

CONCLUSIONS

The outcome of the transfection study proved the additive anti-fibrotic therapeutic effect of LP-NIN-miR and suggested that lipoplexes are effective delivery systems for drug and nucleic acid to the NIH/3T3 cells in the treatment of IPF.

Pulmonary osteoclast-like cells in silica induced pulmonary fibrosis

The pathophysiology of silicosis is poorly understood, limiting development of therapies for those who have been exposed to the respirable particle. We explored mechanisms of silica-induced pulmonary fibrosis in human lung samples collected from patients with occupational exposure to silica and in a longitudinal mouse model of silicosis using multiple modalities including whole-lung single-cell RNA sequencing and histological, biochemical, and physiologic assessments. In addition to pulmonary inflammation and fibrosis, intratracheal silica challenge induced osteoclast-like differentiation of alveolar macrophages and recruited monocytes, driven by induction of the osteoclastogenic cytokine, receptor activator of nuclear factor κΒ ligand (RANKL) in pulmonary lymphocytes, and alveolar type II cells. Anti-RANKL monoclonal antibody treatment suppressed silica-induced osteoclast-like differentiation in the lung and attenuated pulmonary fibrosis. We conclude that silica induces differentiation of pulmonary osteoclast-like cells leading to progressive lung injury, likely due to sustained elaboration of bone-resorbing proteases and hydrochloric acid. Interrupting osteoclast-like differentiation may therefore constitute a promising avenue for moderating lung damage in silicosis.

Inhibition of TGF-β1/Smad3 signaling by compound 5aa: A potential treatment for idiopathic pulmonary fibrosis

The incidence of idiopathic pulmonary fibrosis (IPF) has been steadily increasing each year, posing significant challenges in its treatment. In this study, we conducted the design and synthesis of 23 new inhibitors that specifically target the TGF-β1/Smad3 pathway. Initially, we employed a cell model of TGF-β-induced pulmonary fibrosis, using cell survival rate and HYP expression as indicators to identify the potent ingredient 5aa, which demonstrated significant anti-pulmonary fibrosis activity. Subsequently, we induced mice with bleomycin (BLM) to establish an experimental animal model of pulmonary fibrosis, and evaluated the pharmacodynamics of 5aa in vivo against pulmonary fibrosis. The alterations in HYP and collagen levels in BLM-induced pulmonary fibrosis mice were analyzed using ELISA and immunohistochemistry techniques. The results indicated that compound 5aa effectively suppressed the fibrotic response induced by TGF-β1, inhibited the expression of the fibrotic marker α-SMA, and hindered the EMT process in NIH3T3 cells. Additionally, oral administration of 5aa demonstrated significant therapeutic effects in a mouse model of IPF, comparable to the established drug Nintedanib. Moreover, compound 5aa exhibited higher bioavailability in vivo compared to Nintedanib. These collective outcomes suggest that 5aa holds promise as a potential inhibitor of TGF-β1/Smad3 signaling for the treatment of IPF.

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-β1/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.

Nano-enabled delivery of diosgenin and emodin ameliorates respirable silica dust-induced pulmonary fibrosis silicosis in rats

Oxidative stress and inflammation play a fundamental role in the beginning and advancement of silicosis. Hence, questing active phytocompounds (APCs) with anti-oxidative and anti-inflammatory properties such as diosgenin (DG) and emodin (ED) can be a therapeutic intervention targeting silica-induced pulmonary inflammation and fibrosis. Hydrophobicity and low bioavailability are the barriers that restrict the therapeutic efficacy of DG and ED against pulmonary defects. Encapsulating these APCs in polymeric nanoparticles can overcome this limitation. The present study has thus explored the anti-inflammatory and anti-fibrotic effects of polylactic-co-glycolic acid (PLGA) nanoparticles (NPs) individually loaded with DG (DGn) or ED (EDn) and in combine DG+ED [(DG+ED)n] in respirable silica dust (RSD)-induced pulmonary fibrosis silicosis rat model. Our study found that individual and combined NPs revealed physiochemical characteristics appropriate for IV administration with sustained-drug release purposes. Physiological evaluations of RSD-induced silicosis rats suggested that no treatment could improve the body weight. Still, they reduced the lung coefficient by maintaining lung moisture. Only (DG+ED)n significantly cleared free lung silica. All interventions were found to attribute the increased per cent cell viability in BALF, reduce cytotoxicity via minimizing LDH levels, and balance the oxidant-antioxidant status in silicotic rats. The expression of inflammatory cytokines (TNF-α, IL-1β, IL-6, MCP-1, and TGF-β1) were efficiently down-regulated with NPs interventions compared to pure (DG+ED) treatment. All drug treatments significantly declined, the 8-HdG and HYP productions indicate that RSD-induced oxidative DNA damage and collagen deposition were successfully repaired. Moreover, histopathological investigations proposed that individual or combined drugs NPs interventions could decrease the fibrosis and alveolitis grades in RSD-induced silicosis rats. However, (DG+ED)n intervention significantly inhibited pulmonary fibrosis and alveolitis compared to pure (DG+ED) treatment. In conclusion, the RSD can induce oxidative stress and inflammation in rats, producing reactive oxygen species (ROS)-mediated cytotoxicity to pulmonary cells and leading to silicosis development. The IV administration of combined NP suppressed lung inflammation and collagen formation by maintaining oxidant-antioxidant status and effectively interrupting the fibrosis-silicosis progression. These results may be attributed to the improved bioavailability of DG and ED through their combined nano-encapsulation-mediated targeted drug delivery.

The multifaceted role of macrophage mitophagy in SiO2-induced pulmonary fibrosis: A brief review

Prolonged exposure to environments with high concentrations of crystalline silica (CS) can lead to silicosis. Macrophages play a crucial role in the pathogenesis of silicosis. In the process of silicosis, silica (SiO2) invades alveolar macrophages (AMs) and induces mitophagy which usually exists in three states: normal, excessive, and/or deficiency. Different mitophagy states lead to corresponding toxic responses, including successful macrophage repair, injury, necrosis, apoptosis, and even pulmonary fibrosis. This is a complex process accompanied by various cytokines. Unfortunately, the details have not been fully systematically summarized. Therefore, it is necessary to elucidate the role of macrophage mitophagy in SiO2-induced pulmonary fibrosis by systematic analysis on the literature reports. In this review, we first summarized the current data on the macrophage mitophagy in the development of SiO2-induced pulmonary fibrosis. Then, we introduce the molecular mechanism on how SiO2-induced mitophagy causes pulmonary fibrosis. Finally, we focus on introducing new therapies based on newly developed mitophagy-inducing strategies. We conclude that macrophage mitophagy plays a multifaceted role in the progression of SiO2-induced pulmonary fibrosis, and reprogramming the macrophage mitophagy state accordingly may be a potential means of preventing and treating pulmonary fibrosis.

Association between lipid-lowering drugs and allergic diseases: A Mendelian randomization study

Background

Several observational studies suggest a possible link between lipid-lowering drugs and allergic diseases. However, inferring causality from these studies can be challenging due to issues such as bias, reverse causation, and residual confounding. To investigate the potential causal effect of lipid-lowering drugs, proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors and 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR) inhibitors, on allergic diseases (allergic asthma, allergic conjunctivitis, atopic dermatitis, allergic rhinitis, and allergic urticaria), we performed a Mendelian randomization (MR)-based study.

Methods

We employed MR and summary-data-based MR (SMR), analyzing genome-wide association study (GWAS) data from people of European descent. Single nucleotide polymorphisms (SNPs) were employed as instrumental variables. We selected 2 types of genetic measures to represent the impact of lipid-lowering drugs, including genetic variants near or within drug target genes correlated with low-density lipoprotein cholesterol (LDL-C), and expression quantitative trait loci of drug target genes. The inverse-variance weighted (IVW)-MR approach was the primary utilized MR method, while sensitivity analyses were used to test the robustness of the results. We used SMR analysis as a supplementary analytical method, applying the heterogeneity in dependent instruments (HEIDI) test to assess if the observed correlation between gene expression and outcome was due to a linkage situation.

Results

The IVW-MR analysis revealed significant evidence for an association between PCSK9-mediated LDL-C reduction and a decrease in the risk of allergic asthma (odds ratio [OR] = 1.31, 95% confidence interval [CI] = 1.11-1.56; P < 0.01). Likewise, SMR analysis discovered an augmented expression of PCSK9 being linked with a heightened susceptibility to allergic asthma (OR = 1.21, 95% CI = 1.03-1.43; P = 0.02). No consistent evidence was found for other associations in either analysis.

Conclusion

Our findings support a potential causal relationship between PCSK9 activity and an increased risk of allergic asthma. Thus, PCSK9 inhibitors, which reduce PCSK9 activity, might be considered a priority in future clinical trials investigating drugs for allergic asthma prevention or treatment.

The role of mitochondrial dysfunction in macrophages on SiO2 -induced pulmonary fibrosis: A review

Several epidemiologic and toxicological studies have widely regarded that mitochondrial dysfunction is a popular molecular event in the process of silicosis from different perspectives, but the details have not been systematically summarized yet. Thus, it is necessary to investigate how silica dust leads to pulmonary fibrosis by damaging the mitochondria of macrophages. In this review, we first introduce the molecular mechanisms that silica dust induce mitochondrial morphological and functional abnormalities and then introduce the main molecular mechanisms that silica-damaged mitochondria induce pulmonary fibrosis. Finally, we conclude that the mitochondrial abnormalities of alveolar macrophages caused by silica dust are involved deeply in the pathogenesis of silicosis through these two sequential mechanisms. Therefore, reducing the silica-damaged mitochondria will prevent the potential occurrence and fatality of the disease in the future.

Dioscin: Therapeutic potential for diabetes and complications

Diabetes mellitus is a widespread metabolic disorder with increasing incidence worldwide, posing a considerable threat to human health because of its complications. Therefore, cost-effective antidiabetic drugs with minimal side effects are urgently needed. Dioscin, a naturally occurring compound, helps to reduce the complications of diabetes mellitus by regulating glucose and lipid metabolism, protecting islet β cells, improving insulin resistance, and inhibiting oxidative stress and inflammatory response. Plant-derived dioscin reduces the risk of toxicity and side effects associated with chemically synthesized drugs. It is a promising option for treating diabetes mellitus because of its preventive and therapeutic effects, which may be attributed to a variety of underlying mechanisms. However, data compiled by current studies are preliminary. Information about the molecular mechanism of dioscin remains limited, and no high-quality human experiments and clinical trials for testing its safety and efficacy have been conducted. As a resource for research in this area, this review is expected to provide a systematic framework for the application of dioscin in the treatment of diabetes mellitus and its complications.

Adverse effects of cigarette filter silica on lungs: Comparison with natural crystalline silica particles

As a common additive in cigarette filters, nanosilica has been implemented to reduce the release of harmful substances in cigarette smoke. However, the potential risk of occupational exposure for cigarette factory workers is unknown. We collected physical examination data from 710 cigarette factory workers to evaluate the adverse effects of cigarette filter silica exposure. We also established mouse models induced by cigarette filter silica and crystalline silica separately to compare the lung inflammation, pulmonary function, apoptosis, and fibrosis of the two models. Workers in the rolling and packing workshop exposed to cigarette filter silica had a higher rate of abnormal lung function (17.75%) than those in the cutting workshop (0.87%). Animal experiments showed that compared with the same dose of crystalline silica, cigarette filter silica resulted in higher levels of inflammatory factors in the bronchoalveolar lavage fluid (BALF) of mice at day 7, and lower levels of total lung capacity (TLC), inspiratory capacity (IC), vital capacity (VC), and forced vital capacity (FVC) in mice at day 28. Additionally, both exposed groups of mice showed increased levels of caspase 3, collagen I (Col-Ⅰ), α-smooth muscle actin (α-SMA) and hydroxyproline (HYP) in the lungs, as well as collagen accumulation and fibrous nodules at day 28, with no significant difference between the two groups. The results suggested that cigarette filter silica caused more severe early lung inflammation and late ventilation impairment than the same dose of crystalline silica. In the future, we need to pay more attention to nanosilica protection in cigarette factories to prevent pulmonary dysfunction in workers.

Phytochemical Extract from Carica papaya Leaves and Punica granatum Seeds as Therapy Against Cognitive Impairment in a Murine Model

Mild cognitive impairment (MCI) is defined as inter-stage between normal cognitive aging and major neurocognitive disorder (MND). This state of decay is a crucial factor in treatment to prevent the progression to MND. In this study, our group developed a virtual screening process to evaluate 2568 phytochemical compounds against 5 key proteins associated with MCI and MND. As a result, two potential candidates were identified: carpaine, found in Carica papaya leaves, and punicalagin, present in Punica granatum. A model of cognitive impairment (CI) was developed in 10-month-old male Sprague Dawley rats by administering aluminum chloride (AlCl3) at a dose of 100 mg/kg/day for 30 days. After AlCl3 administration period, one of the groups received carpaine and punicalagin in a phytochemical extract (PE) by oral gavage for 30 days. Novel object recognition test (NOR) was assessed at three different time points (T1 - before CI, T2 - after CI, and T3 - after PE treatment). Glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) were identified in the hippocampus of rats at the end of the study period. After administration of AlCl3, a reduction in discrimination index vs control rats (CI = 0.012 ± 0.08 vs Control = 0.076 ± 0.03), was observed. After phytochemical extract treatment, a significant increase in discrimination index values was observed in the PE group 0.4643 ± 0.13 vs CI group 0.012 ± 0.08. Additionally, the evaluation of immunohistochemistry showed an increase in GFAP positivity in the hippocampus of the CI groups, while a slight decrease was observed in the PE group. This work addressed a comprehensive methodology that utilized in silico tools to identify phytochemical compounds (carpaine and punicalagin) as potential candidates for affecting key proteins in CI. The phytochemical extract containing carpaine and punicalagin resulted in a trend in the decrease of GFAP expression in the hippocampus and improved recognition memory in rats with CI induced by age and AlCl3 administration.

Inhibition of macrophage pyroptosis ameliorates silica-induced pulmonary fibrosis

Macrophage pyroptosis has recently been involved in some inflammatory and fibrosis diseases, however, the role of macrophage pyroptosis in silica-induced pulmonary fibrosis has not been fully elucidated. In this study, we explored the role of macrophage pyroptosis in silicosis in vivo and in vitro. A mouse model of silicosis was established and mice were sacrificed at 7, 14, and 28 days after exposure of silica. The results revealed that the expression of GSDMD and other pyroptosis-related indicators was up-regulated obviously at 14 days after silica exposure, indicating that silica induced pyroptosis in vivo. In vitro, human monocytic leukemia cells (THP-1) and human lung fibroblasts (MRC-5) were used to detect the relationship between macrophage pyroptosis and lung fibroblasts. It showed that silica increased the levels of GSDMD and other pyroptosis-related indicators remarkably in macrophages and the supernatant of macrophage stimulated by silica could promote the upregulation of fibrosis markers in fibroblasts. However, GSDMD knockdown suppressed silica-induced macrophage pyroptosis and alleviated the upregulation of fibrosis markers in fibroblasts, suggesting the important role of macrophage pyroptosis in the activation of myofibroblasts during the progression of silicosis. Taken together, it showed that silica could induce macrophage pyroptosis and inhibiting macrophage pyroptosis could be a feasible clinical strategy to alleviate silicosis.

Dioscorea nipponica Makino: A comprehensive review of its chemical composition and pharmacology on chronic kidney disease

Chronic kidney disease (CKD) is a widespread ailment that significantly impacts global health. It is characterized by high prevalence, poor prognosis, and substantial healthcare costs, making it a major public health concern. The current clinical treatments for CKD are not entirely satisfactory, leading to a high demand for alternative therapeutic options. Chinese herbal medicine, with its long history, diverse varieties, and proven efficacy, offers a promising avenue for exploration. One such Chinese herbal medicine, Dioscorea nipponica Makino (DNM), is frequently used to treat kidney diseases. In this review, we have compiled studies examining the mechanisms of action of DNM in the context of CKD, focusing on five primary areas: improvement of oxidative stress, inhibition of renal fibrosis, regulation of metabolism, reduction of inflammatory response, and regulation of autophagy.

Emerging trends in silicosis research: a scientometric review

Silicosis is a global disease whose prevention efforts cannot be ignored today. Although numerous silicosis-related data have been published recently, emphasizing the characteristics and nature of silicosis, a summary of the developmental laws of research is lacking, especially in the visual analysis of the literature. We aim to address this issue through a scientometric review. The Web of Science Core Collection and the All Databases were searched with "silicosis" as the topic, excluding unrelated publications, and obtained data from 9802 and 1613 publications, respectively. The data was then analyzed using the Web of Science's online scientometric analysis function and CiteSpace's visual analysis functionality, including publication volume analysis, co-occurrence analysis, co-citation analysis, cluster analysis, and explosive detection. The results identify the "respiratory system" as the most influential area over a century. Furthermore, the publication's number was correlated with the gross domestic product. We ranked countries and institutions based on the frequency of publications and discovered that Europe, the USA, and China are the leading regions for silicosis research, with the USA and Europe having a stronger influence. Many reports related to artificial stone and denim jean production have been studied through citation analysis, indicating new epidemic trends in silicosis. Besides, silicosis-related diseases and the pathogenesis of silicosis were the research hotspots of silicosis through co-occurrence keyword analysis and outbreak detection. Furthermore, related diseases include coal workers' pneumoconiosis and tuberculosis, while the mechanism of silicosis includes studies on inflammation and fibrosis, oxidative stress, alveolar macrophages, apoptosis, and pathways.

The role of cGAS-STING signaling in pulmonary fibrosis and its therapeutic potential

Pulmonary fibrosis is a progressive and ultimately fatal lung disease, exhibiting the excessive production of extracellular matrix and aberrant activation of fibroblast. While Pirfenidone and Nintedanib are FDA-approved drugs that can slow down the progression of pulmonary fibrosis, they are unable to reverse the disease. Therefore, there is an urgent demand to develop more efficient therapeutic approaches for pulmonary fibrosis. The intracellular DNA sensor called cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) synthase (cGAS) plays a crucial role in detecting DNA and generating cGAMP, a second messenger. Subsequently, cGAMP triggers the activation of stimulator of interferon genes (STING), initiating a signaling cascade that leads to the stimulation of type I interferons and other signaling molecules involved in immune responses. Recent studies have highlighted the involvement of aberrant activation of cGAS-STING contributes to fibrotic lung diseases. This review aims to provide a comprehensive summary of the current knowledge regarding the role of cGAS-STING pathway in pulmonary fibrosis. Moreover, we discuss the potential therapeutic implications of targeting the cGAS-STING pathway, including the utilization of inhibitors of cGAS and STING.

Fermented cordyceps powder alleviates silica-induced pulmonary inflammation and fibrosis in rats by regulating the Th immune response

BACKGROUND

Silicosis is an important occupational disease caused by inhalation of free silica and is characterized by persistent pulmonary inflammation, subsequent fibrosis and lung dysfunction. Until now, there has been no effective treatment for the disease due to the complexity of pathogenesis. Fermented cordyceps powder (FCP) has a similar effect to natural cordyceps in tonifying the lung and kidney. It has started to be used in the adjuvant treatment of silicosis. This work aimed to verify the protective effects of FCP against silicosis, and to explore the related mechanism.

METHODS

Wistar rats were randomly divided into four groups including the saline-instilled group, the silica-exposed group, the silica + FCP (300 mg/kg) group and the silica + FCP (600 mg/kg) group. Silicosis rat models were constructed by intratracheal instillation of silica (50 mg). Rats in the FCP intervention groups received the corresponding dose of FCP daily by intragastric gavage. Rats were sacrificed on days 7, 28 and 56 after treatment, then samples were collected for further analysis.

RESULTS

FCP intervention reduced the infiltration of inflammatory cells and the concentration of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and transforming growth factor-β1 (TGF-β1) at days 7, 28, 56, and decreased the expression of collagen, α-smooth muscle actin (α-SMA) and fibronectin (FN) at days 28 and 56 in the lung of silicosis rats. FCP also decreased the immune response of Th1 and Th17 at days 7, 28, 56 and inhibited the enhancement of the Th2 response at day 56.

CONCLUSIONS

FCP intervention could alleviate silica-induced pulmonary inflammation and fibrosis, the protective effect may be achieved by reducing Th1 and Th17 immune responses and inhibiting the enhancement of the Th2 response.

Eriodictyol Alleviated LPS/D-GalN-Induced Acute Liver Injury by Inhibiting Oxidative Stress and Cell Apoptosis via PI3K/AKT Signaling Pathway

Eriodictyol occurs naturally in a variety of fruits and vegetables, and has drawn significant attention for its potential health benefits. This study aims to look into the effects of eriodictyol on acute liver injury (ALI) induced by LPS/D-GalN and elucidate its potential molecular biological mechanisms. A total of 47 targets were predicted for the treatment of ALI with eriodictyol, and the PI3K/AKT signaling pathway played a key role in the anti-ALI processing of this drug. The in vivo experiment showed that eriodictyol can effectively reduce liver function-related biochemical indicators such as ALT, AST, and AKP. Eriodictyol can also up-regulate the levels of SOD and GSH, and inhibit the release of IL-1β, IL-6, and TNF-α. Additionally, TUNEL staining, immunohistochemistry, and RT-PCR experiments showed that eriodictyol activated the PI3K/AKT pathway and decreased the expression of Bax, caspase3, and caspase8 while increasing the expression of Bcl-2 m-RNA. Finally, molecular docking experiments and molecular dynamics simulations confirmed the stable binding between eriodictyol and PI3K, AKT molecules. This study showed that eriodictyol can activate the PI3K/AKT signaling pathway to alleviate ALI-related oxidative stress and apoptosis.

Crystalline Silica-Induced Proinflammatory Interstitial Macrophage Recruitment through Notch3 Signaling Promotes the Pathogenesis of Silicosis

Crystalline silica (CS) particles are ubiquitous in the environment, especially in occupational conditions, and exposure to respirable CS causes silicosis. The initial response to CS is mediated by innate immunity, where pulmonary macrophages act as central orchestrators. However, the repercussions of CS on functionally distinct macrophage subsets remain to be inconclusive. Herein, to study the effects of inhaled CS, we divided macrophages into three subsets: circulating monocytes, interstitial macrophages (IMs), and alveolar macrophages (AMs). CS-induced massive IMs increase in the lung, the phenotype and function of which differed from those of tissue-resident AMs and circulating monocytes. The augmented IMs were driven by recruitment of circulating macrophages rather than cell proliferation in situ. Moreover, the IMs predominantly exerted a classic activated (M1) phenotype and expressed proinflammatory cytokines, contributing to CS-induced lung injury. Notably, we demonstrated that IMs augmented Notch3 expression. Mechanistically, using myeloid-specific Notch3-knockout mice, we demonstrated that Notch3 signaling not only promoted IMs recruitment by regulating CCR2 expression but also manipulated the proinflammatory phenotype. Mice with conditional Notch3-knockout exhibited alleviation of CS-induced inflammation and fibrosis in lung. Overall, our study identifies IMs as critical mediators in response to CS and highlights the role of Notch3 in IMs recruitment and activation, providing new insights into CS toxicological effects in the lung.

Exposure to nonylphenol in early life causes behavioural deficits related with autism spectrum disorders in rats

Early-life exposure to environmental endocrine disruptors (EDCs) is a potential risk factor for autism spectrum disorder (ASD). Exposure to nonylphenol (NP), a typical EDC, is known to cause some long-term behavioural abnormalities. Moreover, these abnormal behaviours are the most frequent psychiatric co-morbidities in ASD. However, the direct evidence for the link between NP exposure in early life and ASD-like behavioural phenotypes is still missing. In the present study, typical ASD-like behaviours induced by valproic acid treatment were considered as a positive behavioural control. We investigated impacts on social behaviours following early-life exposure to NP, and explored effects of this exposure on neuronal dendritic spines, mitochondria function, oxidative stress, and endoplasmic reticulum (ER) stress. Furthermore, primary cultured rat neurons were employed as in vitro model to evaluate changes in dendritic spine caused by exposure to NP, and oxidative stress and ER stress were specifically modulated to further explore their roles in these changes. Our results indicated rats exposed to NP in early life showed mild ASD-like behaviours. Moreover, we also found the activation of ER stress triggered by oxidative stress may contribute to dendritic spine decrease and synaptic dysfunction, which may underlie neurobehavioural abnormalities induced by early-life exposure to NP.

Yangqing Chenfei formula alleviates crystalline silica induced pulmonary inflammation and fibrosis by suppressing macrophage polarization

OBJECTIVE

To explore the underlying mechanisms of the effects of Yangqing Chenfei formula (, YCF) on inflammation and fibrosis in silicosis via inhibition of macrophage polarization.

METHODS

A silicotic rat model was established via a single intratracheal instillation of silica particles on the first day of week 0. Subsequently, YCF was administered intragastrically to silicotic rats during weeks 0-2 and 5-8 twice daily. The mouse-derived alveolar macrophage cell line was used to investigate the mechanisms of YCF in M1/M2 polarization.

RESULTS

YCF treatment effectively inhibited lung pathological changes, including inflammatory cell infiltration and tissue damage, and increased the forced expiratory volume in the first 0.3 s, functional residual capacity, and maximal mid-expiratory flow in weeks 2 and 8. Furthermore, the treatment improved lung functions by upregulating tidal volume, pause increase, and expiratory flow at 50% tidal volume from weeks 5 to 8. Moreover, YCF could significantly suppressed the progression of inflammation and fibrosis, by reducing the levels of inflammatory cytokines, as well as collagen- I and III. YCF treatment also decreased the numbers of macrophages and M1/M2 macrophages and the level of transforming growth factor-β (TGF-β). Additionally, YCF5, the effective substance in YCF, decreased lipopolysaccharide and interferon-γ-induced M1 macrophage polarization in a concentration-dependent manner. The mechanism of anti-M1 polarization might be related to a decrease in extracellular signal-regulated kinase, c-JUN N-terminal kinase, P38, and P65 phosphorylation. Furthermore, YCF5 inhibited interleukin-4-induced M2 macrophages by decreasing the protein and mRNA expressions of arginase-1 and CD206 as well as the levels of profibrotic factors, such as TGF-β and connective tissue growth factor. The mechanisms underlying the anti-M2 polarization of YCF5 were primarily associated with the inhibition of the nuclear translocation of phosphorylated signal transducer and activator of transcription 6 (p-STAT6).

CONCLUSION

YCF significantly inhibits inflammation and fibrosis in silicotic rats probably via the suppression of M1/M2 macrophage polarization mediated by the inhibition of mitogen-activated protein kinase and nuclear factor kappa B signaling pathways and Janus kinase/STAT6 pathways.

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.

Targeting STING-mediated pro-inflammatory and pro-fibrotic effects of alveolar macrophages and fibroblasts blunts silicosis caused by silica particles

Silica is utilized extensively in industrial and commercial applications as a chemical raw material, increasing its exposure and hazardous potential to populations, with silicosis serving as an important representative. Silicosis is characterized by persistent lung inflammation and fibrosis, for which the underlying pathogenesis of silicosis is unclear. Studies have shown that the stimulating interferon gene (STING) participates in various inflammatory and fibrotic lesions. Therefore, we speculated that STING might also play a key role in silicosis. Here we found that silica particles drove the double-stranded DNA (dsDNA) release to activate the STING signal pathway, contributing to alveolar macrophages (AMs) polarization by secreting diverse cytokines. Then, multiple cytokines could generate a micro-environment to exacerbate inflammation and promote the activation of lung fibroblasts, hastening fibrosis. Intriguingly, STING was also crucial for the fibrotic effects induced by lung fibroblasts. Loss of STING could effectively inhibit silica particles-induced pro-inflammatory and pro-fibrotic effects by regulating macrophages polarization and lung fibroblasts activation to alleviate silicosis. Collectively, our results have revealed a novel pathogenesis of silica particles-caused silicosis mediated by the STING signal pathway, indicating that STING may be regarded as a promising therapeutic target in the treatment of silicosis.

Searching for Novel Candidate Small Molecules for Ameliorating Idiopathic Pulmonary Fibrosis: a Narrative Review

Idiopathic pulmonary fibrosis (IPF) can be defined as a progressive chronic pulmonary disease showing scarring in the lung parenchyma, thereby resulting in increase in mortality and decrease in the quality of life. The pathophysiologic mechanism of fibrosis in IPF is still unclear. Repetitive microinjuries to alveolar epithelium with genetical predisposition and an abnormal restorative reaction accompanied by excessive deposition of collagens are involved in the pathogenesis. Although the two FDA-approved drugs, pirfenidone and nintedanib, are under use for retarding the decline in lung function of patients suffered from IPF, they are not able to improve the survival rate or quality of life. Therefore, a novel therapeutic agent acting on the major steps of the pathogenesis of disease and/or, at least, managing the clinical symptoms of IPF should be developed for the effective regulation of this incurable disease. In the present review, we tried to find a potential of managing the clinical symptoms of IPF by natural products derived from medicinal plants used for controlling the pulmonary inflammatory diseases in traditional Asian medicine. A multitude of natural products have been reported to exert an antifibrotic effect in vitro and in vivo through acting on the epithelial-mesenchymal transition pathway, transforming growth factor (TGF)-β-induced intracellular signaling, and the deposition of extracellular matrix. However, clinical antifibrotic efficacy of these natural products on IPF have not been elucidated yet. Thus, those effects should be proven by further examinations including the randomized clinical trials, in order to develop the ideal and optimal candidate for the therapeutics of IPF.

Yangqing Chenfei formula alleviates silica-induced pulmonary inflammation in rats by inhibiting macrophage M1 polarization

BACKGROUND

Yangqing Chenfei formula (YCF) is a traditional Chinese medicine formula for early-stage silicosis. However, the therapeutic mechanism is unclear. The purpose of this study was to determine the mechanism for the effects of YCF on early-stage experimental silicosis.

METHODS

The anti-inflammatory and anti-fibrotic effects of YCF were determined in a silicosis rat model, which was established by intratracheal instillation of silica. The anti-inflammatory efficacy and molecular mechanisms of YCF were examined in a lipopolysaccharide (LPS)/interferon (IFN)-γ-induced macrophage inflammation model. Network pharmacology and transcriptomics were integrated to analyze the active components, corresponding targets, and anti-inflammatory mechanisms of YCF, and these mechanisms were validated in vitro.

RESULTS

Oral administration of YCF attenuated the pathological changes, reduced inflammatory cell infiltration, inhibited collagen deposition, decreased the levels of inflammatory factors, and reduced the number of M1 macrophages in the lung tissue of rats with silicosis. YCF5, the effective fraction of YCF, significantly attenuated the inflammatory factors induced by LPS and IFN-γ in M1 macrophages. Network pharmacology analysis showed that YCF contained 185 active components and 988 protein targets, which were mainly associated with inflammation-related signaling pathways. Transcriptomic analysis showed that YCF regulated 117 reversal genes mainly associated with the inflammatory response. Integrative analysis of network pharmacology and transcriptomics indicated that YCF suppressed M1 macrophage-mediated inflammation by regulating signaling networks, including the mTOR, mitogen-activated protein kinases (MAPK), PI3K-Akt, NF-κB, and JAK-STAT signaling pathways. In vitro studies confirmed that the active components of YCF significantly decreased the levels of p-mTORC1, p-P38, and p-P65 by suppressing the activation of related-pathways.

CONCLUSION

YCF significantly attenuated the inflammatory response in rats with silicosis via the suppression of macrophage M1 polarization by inhibiting a "multicomponent-multitarget-multipathway" network.

Neutralization of interleukin-11 attenuates silica particles-induced pulmonary inflammation and fibrosis in vivo

Environmental exposure to crystalline silica particles can lead to silicosis, which is one of the most serious pulmonary interstitial fibrosis around the world. Unfortunately, the exact mechanism on silicosis is unclear, and the effective treatments are lacking to date. In this study, we aim to explore the molecular mechanism by which interleukin-11 (IL-11) affects silica particles-induced lung inflammation and fibrosis. We observed that IL-11 expressions in mouse lungs were significantly increased after silica exposure, and maintained at high levels across both inflammation and fibrosis phase. Immunofluorescent dual staining further revealed that the overexpression of IL-11 mainly located in mouse lung epithelial cells and fibroblasts. Using neutralizing anti-IL-11 antibody could effectively alleviate the overexpression of pro-inflammatory cytokines (i.e., interleukin-6 and tumor necrosis factor-α) and fibrotic proteins (i.e., collagen type I and matrix metalloproteinase-2) induced by silica particles. Most importantly, the expressions of IL-11 receptor subunit α (IL-11Rα), Glycoprotein 130 (GP130), and phosphorylated extracellular signal-regulated kinase (p-ERK) were significantly increased in response to silica, whereas blocking of IL-11 markedly reduced their levels. All findings suggested that the overexpression of IL-11 was involved in the pathological of silicosis, while neutralizing IL-11 antibody could effectively alleviate the silica-induced lung inflammation and fibrosis by inhibiting the IL-11Rα/GP130/ERK signaling pathway. IL-11 might be a promising therapeutic target for lung inflammation and fibrosis caused by silica particles exposure.

Exosomal Non-Coding RNAs: Novel Regulators of Macrophage-Linked Intercellular Communication in Lung Cancer and Inflammatory Lung Diseases

Macrophages are innate immune cells and often classified as M1 macrophages (pro-inflammatory states) and M2 macrophages (anti-inflammatory states). Exosomes are cell-derived nanovesicles that range in diameter from 30 to 150 nm. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), are abundant in exosomes and exosomal ncRNAs influence immune responses. Exosomal ncRNAs control macrophage-linked intercellular communication via their targets or signaling pathways, which can play positive or negative roles in lung cancer and inflammatory lung disorders, including acute lung injury (ALI), asthma, and pulmonary fibrosis. In lung cancer, exosomal ncRNAs mediated intercellular communication between lung tumor cells and tumor-associated macrophages (TAMs), coordinating cancer proliferation, migration, invasion, metastasis, immune evasion, and therapy resistance. In inflammatory lung illnesses, exosomal ncRNAs mediate macrophage activation and inflammation to promote or inhibit lung damage. Furthermore, we also discussed the possible applications of exosomal ncRNA-based therapies for lung disorders.

Dioscin ameliorates silica-aggravated systemic lupus erythematosus via suppressing apoptosis and improving LC3-associated phagocytosis in MRL/lpr mice

Inhalation of silica not only directly leads to silicosis locally, but also results in various types of autoimmune diseases systemically, most commonly systemic lupus erythematosus (SLE). Little is known about the etiopathogenesis of silica-aggravated SLE to date, however, abnormal apoptosis and impaired apoptotic clearance have been reported to be closely related to the occurrence of SLE. LC3-associated phagocytosis (LAP) is a non-canonical form of autophagy, which plays a crucial role in mediating the clearance of apoptotic cells. Here we showed that the excessive accumulation of apoptotic debris in MRL/lpr mice exposed to silica might be due to the increased cell apoptosis and defective LAP caused by silica, thus accelerating the occurrence and progression of silica-aggravated SLE. Dioscin is an active ingredient in the family of Dioscoreaceae and is reported to possess multiple pharmacological activities, including anti-inflammatory, anti-apoptotic and autophagy-promoting properties. However, its role in SLE aggravated by silica exposure has not been investigated. In our study, we confirmed that dioscin decreased the accumulation of apoptotic debris by suppressing the excessive cell apoptosis and improving the LAP of immune cells in lung and spleen, leading to subsequent dramatically ameliorated lupus-like symptoms in silica-exposed MRL/lpr mice.

Dioscin modulates macrophages polarization and MDSCs differentiation to inhibit tumorigenesis of colitis-associated colorectal cancer

It has been reported that colitis is one of risk factors in colorectal cancer (CRC). Intervention of intestinal inflammation and in the early stage of tumorigenesis is of great significance to control the incidence and mortality of CRC. In recent years, natural active products of traditional Chinese medicine have been confirmed that they had made great progress in disease prevention. Here, we showed that Dioscin, a natural active product of Dioscorea nipponica Makino, inhibited initiation and tumorigenesis of AOM/DSS-induced colitis-associated colon cancer (CAC), including alleviating colonic inflammation, improving intestinal barrier function and decreasing tumor burden. In addition, we also explored the immunoregulatory effect of Dioscin on mice. The results showed that Dioscin modulated M1/M2 macrophages phenotype in spleen and decreased monocytic myeloid-derived suppressor cells (M-MDSCs) population in blood and spleen of mice. The in vitro assay demonstrated that Dioscin promoted M1 as well as inhibited M2 macrophages phenotype in LPS- or IL-4-induced bone marrow-derived macrophages (BMDMs) model. Based on the plasticity of MDSCs and its ability to differentiate into M1/M2 macrophages, we here found that Dioscin increased M1- and decreased M2-like phenotype during the process of MDSCs differentiation in vitro, suggesting Dioscin promoted MDSCs differentiate into M1 as well as inhibited its differentiation into M2 macrophages. Taken together, our study indicated that Dioscin had the inhibitory effect on the initial of tumorigenesis at early stage of CAC via the ant-inflammatory effect, which provided a natural active candidate for effective prevention of CAC.

Pulmonary osteoclast-like cells in silica induced pulmonary fibrosis

The pathophysiology of silicosis is poorly understood, limiting development of therapies for those who have been exposed to the respirable particle. We explored the mechanisms of silica-induced pulmonary fibrosis in a mouse model using multiple modalities including whole-lung single-nucleus RNA sequencing. These analyses revealed that in addition to pulmonary inflammation and fibrosis, intratracheal silica challenge induced osteoclast-like differentiation of alveolar macrophages and recruited monocytes, driven by induction of the osteoclastogenic cytokine, receptor activator of nuclear factor-κB ligand (RANKL) in pulmonary lymphocytes and alveolar type II cells. Furthermore, anti-RANKL monoclonal antibody treatment suppressed silica-induced osteoclast-like differentiation in the lung and attenuated silica-induced pulmonary fibrosis. We conclude that silica induces osteoclast-like differentiation of distinct recruited and tissue resident monocyte populations, leading to progressive lung injury, likely due to sustained elaboration of bone resorbing proteases and hydrochloric acid. Interrupting osteoclast-like differentiation may therefore constitute a promising avenue for moderating lung damage in silicosis.

Macrophage-derived GPNMB trapped by fibrotic extracellular matrix promotes pulmonary fibrosis

Pulmonary fibrosis (PF) is a form of progressive lung disease characterized by chronic inflammation and excessive extracellular matrix (ECM) deposition. However, the protein changes in fibrotic ECM during PF and their contribution to fibrosis progression are unclear. Here we show that changes in expression of ECM components and ECM remodeling had occurred in silica-instilled mice. The macrophage-derived glycoprotein nonmetastatic melanoma protein B (GPNMB) captured by fibrotic ECM may activate resident normal fibroblasts around the fibrotic foci. Functional experiments demonstrated the activation of fibroblasts in fibrotic ECM, which was alleviated by GPNMB-neutralizing antibodies or macrophage deletion in the ECM of silica-instilled mice. Moreover, the Serpinb2 expression level was increased in fibroblasts in fibrotic ECM, and the expression of CD44 was increased in silica-instilled mice. In conclusion, macrophage-derived GPNMB is trapped by fibrotic ECM during transport and may activate fibroblasts via the CD44/Serpinb2 pathway, thus leading to the further development of fibrosis.

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

BACKGROUND

Yangqing Chenfei formula (YCF) has been demonstrated its clinical efficiency on silicosis patients. However, the effect of YCF against silicotic fibrosis and its mechanism remain unclear.

PURPOSE

This study is aimed to investigate active compounds and molecular mechanism of YCF in treating silicosis.

METHOD

YCF was orally administrated to silicosis rats induced by crystalline silica. The effective fraction of YCF and the compounds was isolated and identified by using macroporous resin and HPLC-MS, respectively. The targets and potential molecular mechanism of YCF against silicotic fibrosis were investigated through pharmacological network and RNA-sequencing analysis and in vitro-experimental validation.

RESULTS

YCF could remarkably improve the lung function and pathological changes of silicotic rats, reduce the aggregation of fibrocytes and deposition of ECM, such as collagen I, III, FN, and α-SMA, and suppress the TGF-β/Smad3 signaling. Furthermore, YCF6, the effective fraction derived from YCF, could significantly inhibit fibroblast activation induced by TGF-β. Then, 135 compounds were identified from YCF6 by using HPLC-MS, and Network pharmacology analysis predicted total 941 targets for these compounds. Moreover, 409 differentially expressed genes of fibroblast activation induced by TGF-β were identified. Then, integrated analysis of the 941 targets with 409 differentially expressed genes showed that YCF6 contains multiple compounds, such as tangeretin, L-Malic acid, 2-Monolinolein etc., which inhibits fibroblast activation probably by targeting different proteins, such as PIK3CA, AKT1, JAK2, STAT3, GSK3β, leading to regulate the signal network, such as PI3K/AKT signaling pathway, JAK/STAT signaling pathway, and Wnt signaling pathway. Finally, in vitro experiment indicated that tangeretin, the active compound contained in YCF6, could significantly inhibit TGF-β induced fibroblast activation. Moreover, YCF6 and tangeretin could markedly inhibit the activation of PI3K/AKT, JAK/STAT, and Wnt pathway.

CONCLUSION

YCF contained multiple compounds and targeted various proteins that regulated the fibroblast activation, which might be the molecular mechanisms of it in treating silicosis.

Human umbilical cord mesenchymal stem cell-derived extracellular vesicles alleviated silica induced lung inflammation and fibrosis in mice via circPWWP2A/miR-223-3p/NLRP3 axis

Silicosis is a progressive inflammatory disease with poorly defined mechanisms and limited therapeutic options. Recent studies found that microRNAs (miRNAs) and circular RNAs (circRNAs) were involved in the development of respiratory diseases; however, the function of non-coding RNAs in silicosis was still needed to be further explored. We found that miR-223-3p was significantly decreased in macrophages and lung tissues of mice after silica treatment, which were consistent with the results of GEO database microarray analysis. Notably, NLRP3 is a target gene downstream of miR-223-3p. And circular RNA PWWP2A (circPWWP2A) was significantly elevated after silica stimulation. To elucidate the role of these RNAs in silica-induced inflammation in macrophages and lung tissues, we investigated the upstream molecular mechanisms of circPWWP2A on the inflammatory response. The inhibitory effect of miR-223-3p on its target NLRP3 was suppressed by circPWWP2A, which led to lung fibrosis. Our study found that circPWWP2A could adsorb miR-223-3p to regulate NLRP3 after silica stimulation in pulmonary fibrosis. And our results revealed that the circPWWP2A-miR-223-3p-NLRP3 axis was potentially instrumental in managing silica-induced inflammation and fibrosis. Previous studies have demonstrated that human umbilical cord mesenchymal stem cell-derived extracellular vesicles (hucMSC-EVs) exhibit anti-inflammatory and anti-fibrotic effects in multiple organs. However, the potential effectiveness of hucMSC-EVs against silicosis or the underlying mechanisms of their biological outcomes remains unclear. Therefore, we used 3D culture technology to extract hucMSC-EVs and observed their effects in macrophages and lung tissues, respectively. According to the EVmiRNA database, miR-223-3p was abundant in MSC-EVs. In addition, hucMSC-EVs may modulate lung function, reduce the secretion of inflammatory factors (NLRP3, IL-1β, IL-18 and cleaved Caspase-1) and attenuate the deposition of fibrosis-related factors (Collagen Ⅰ, Collagen Ⅲ, fibronectin and α-SMA). In vitro results evinced that hucMSC-EVs reduced the inflammatory response of macrophages and restricted the activation and proliferation of fibroblasts. Moreover, our study showed that hucMSCs-EVs acted as a mediator to transfer miR-223-3p to suppress circPWWP2A, thereby alleviating pulmonary fibrosis through the NLRP3 signaling pathway. These data may provide potentially novel strategies for investigating the pathogenesis of silicosis and developing novel treatments for this disease.

Saponins: Research Progress and Their Potential Role in the Post-COVID-19 Pandemic Era

In the post-COVID-19 pandemic era, the new global situation and the limited therapeutic management of the disease make it necessary to take urgent measures in more effective therapies and drug development in order to counteract the negative global impacts caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its new infectious variants. In this context, plant-derived saponins-glycoside-type compounds constituted from a triterpene or steroidal aglycone and one or more sugar residues-may offer fewer side effects and promising beneficial pharmacological activities. This can then be used for the development of potential therapeutic agents against COVID-19, either as a therapy or as a complement to conventional pharmacological strategies for the treatment of the disease and its prevention. The main objective of this review was to examine the primary and current evidence in regard to the therapeutic potential of plant-derived saponins against the COVID-19 disease. Further, the aim was to also focus on those studies that highlight the potential use of saponins as a treatment against SARS-CoV-2. Saponins are antiviral agents that inhibit different pharmacological targets of the virus, as well as exhibit anti-inflammatory and antithrombotic activity in relieving symptoms and clinical complications related to the disease. In addition, saponins also possess immunostimulatory effects, which improve the efficacy and safety of vaccines for prolonging immunogenicity against SARS-CoV-2 and its infectious variants.

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.

Identification of circRNA expression profiles and the potential role of hsa_circ_0006916 in silicosis and pulmonary fibrosis

Circular RNAs (circRNAs) are emerging as novel regulators in the biological development of various diseases, but their expression profiles, functions and mechanisms in silicosis and pulmonary fibrosis remain largely unexplored. In this study, we constructed a mouse model of pulmonary fibrosis by intratracheal injection of silica particles and then performed transcriptome RNA sequencing of lung tissues. The results showed that 78 circRNAs, 39 miRNAs and 262 mRNAs were differentially expressed. Among them, five circRNAs, three miRNAs and four mRNAs were further selected, and their abnormal expression was verified in mouse fibrotic lung tissues by RT-qPCR assay. The circRNA-associated ceRNA network including 206 ceRNA triplets was constructed based on abnormally expressed circRNAs, miRNAs and mRNAs, and miR-199b-5p, miR-296-5p and miR-708-5p were identified as hub miRNAs connected to circRNAs and mRNAs. Subsequently, GO and KEGG pathway enrichment analyses were performed to detect the potential roles of differentially expressed mRNAs in pulmonary fibrosis, which were mainly involved in immune response, Th17 cell differentiation, NF-κB signaling pathway and PI3K-Akt signaling pathway. Furthermore, we identified that hsa_circ_0006916 was up-regulated in pulmonary fibrosis. To characterize the potential role of hsa_circ_0006916, we transfected siRNA targeting hsa_circ_0006916 into alveolar macrophages and found that knockdown of hsa_circ_0006916 significantly increased the expression levels of M1 molecules IL-1β and TNF-α and reduced the expression level of M2 molecule TGF-β1, indicating that hsa_circ_0006916 may play an important role in the activation of M1-M2 polarization effect in macrophages. Our results provided important evidence on the possible contribution of these abnormal circRNAs to the development of silicosis and pulmonary fibrosis.

Chinese medicinal plant Polygonum cuspidatum ameliorates silicosis via suppressing the Wnt/β-catenin pathway

Polygonum cuspidatum (PC) extract has effect on silica-induced pulmonary fibrosis. This study aimed to explore the anti-pulmonary-fibrosis effects and mechanism of PC. Sprague–Dawley rat model was constructed by inhalation of silicon dioxide suspension through tracheal intubation method. And histopathological examination showed that PC inhibited inflammatory cell infiltration, fibrous and collagen hyperplasia, and protected the normal structure of alveoli. TUNEL assay declared that PC retarded cell apoptosis. Meanwhile, up-regulation of basic fibroblast growth factor, plated-derived growth factor, and TNF-α in silicosis rats was decreased by PC addition. In addition, human fetal lung fibroblasts (HFL-1) cells were stimulated with transforming growth factor-β1 (TGF-β1). PC administration increased the proliferation and invasion of TGF-β1-stimulated HFL-1 cells whereas decreased cell apoptosis. Moreover, western blotting exhibited that PC treatment decreased the expression of α-smooth muscle actin, collagen I, and collagen III in silicosis rats and TGF-β1-stimulated HFL-1 cells. Furthermore, the levels of Wnt/β-catenin pathway proteins were up-regulated in silicosis rats and TGF-β1-stimulated HFL-1 cells, which were weakened by PC treatment. Meanwhile, Wnt3a (an activator of Wnt/β-catenin) addition reversed the effect of PC addition. In conclusion, PC prevents silica-induced fibrosis through inhibiting the Wnt/β-catenin pathway.

Vitamin D protects silica particles induced lung injury by promoting macrophage polarization in a KLF4-STAT6 manner

Silicosis is one of the severest occupational diseases worldwide, manifesting as infiltration of inflammatory cells, excessive secretion of pro-inflammatory mediators and pulmonary diffuse fibrosis. Macrophages polarization to M2 is one of the major strategies that attenuates inflammatory response. Our previous study found that vitamin D could protect against silica-induced lung injury by damping the secretion of pro-inflammatory cytokines. Here we further identified that vitamin D attenuated silica particles-induced lung inflammation by regulating macrophage polarization in a KLF4-STAT6 manner. Myeloid-specific Stat6 knockout (cKO) mice were generated for in vivo studies. Primary macrophages purified from bronchoalveolar lavage fluid (BALF) of wildtype or Stat6 cKO mice and differentiated THP-1 cells were used for in vitro studies. Vitamin D was found to promote alveolar macrophage polarizing to M2 phenotype through the STAT6 signaling pathway, as demonstrated by worse lung inflammation and ablated protection of vitamin D in silica particles-instilled Stat6 cKO mice. Mechanismly, vitamin D upregulated KLF4 expression in the alveolar macrophage, which synergistically activated STAT6. Additionally, KLF4 was found to upregulate macrophages autophagy, which protected them from silica particles-induced oxidative stress and cell apoptosis. The protective effects of vitamin D were dismissed by silencing KLF4. Our study demonstrates the potential mechanism of vitamin D-mediated macrophage polarization and reveals the therapeutic application of vitamin D in inflammatory disease.

Pulmonary Fibrosis as a Result of Acute Lung Inflammation: Molecular Mechanisms, Relevant In Vivo Models, Prognostic and Therapeutic Approaches

Pulmonary fibrosis is a chronic progressive lung disease that steadily leads to lung architecture disruption and respiratory failure. The development of pulmonary fibrosis is mostly the result of previous acute lung inflammation, caused by a wide variety of etiological factors, not resolved over time and causing the deposition of fibrotic tissue in the lungs. Despite a long history of study and good coverage of the problem in the scientific literature, the effective therapeutic approaches for pulmonary fibrosis treatment are currently lacking. Thus, the study of the molecular mechanisms underlying the transition from acute lung inflammation to pulmonary fibrosis, and the search for new molecular markers and promising therapeutic targets to prevent pulmonary fibrosis development, remain highly relevant tasks. This review focuses on the etiology, pathogenesis, morphological characteristics and outcomes of acute lung inflammation as a precursor of pulmonary fibrosis; the pathomorphological changes in the lungs during fibrosis development; the known molecular mechanisms and key players of the signaling pathways mediating acute lung inflammation and pulmonary fibrosis, as well as the characteristics of the most common in vivo models of these processes. Moreover, the prognostic markers of acute lung injury severity and pulmonary fibrosis development as well as approved and potential therapeutic approaches suppressing the transition from acute lung inflammation to fibrosis are discussed.

Macrophage autophagy in macrophage polarization, chronic inflammation and organ fibrosis

As the essential regulators of organ fibrosis, macrophages undergo marked phenotypic and functional changes after organ injury. These changes in macrophage phenotype and function can result in maladaptive repair, causing chronic inflammation and the development of pathological fibrosis. Autophagy, a highly conserved lysosomal degradation pathway, is one of the major players to maintain the homeostasis of macrophages through clearing protein aggregates, damaged organelles, and invading pathogens. Emerging evidence has shown that macrophage autophagy plays an essential role in macrophage polarization, chronic inflammation, and organ fibrosis. Because of the high heterogeneity of macrophages in different organs, different macrophage types may play different roles in organ fibrosis. Here, we review the current understanding of the function of macrophage autophagy in macrophage polarization, chronic inflammation, and organ fibrosis in different organs, highlight the potential role of macrophage autophagy in the treatment of fibrosis. Finally, the important unresolved issues in this field are briefly discussed. A better understanding of the mechanisms that macrophage autophagy in macrophage polarization, chronic inflammation, and organ fibrosis may contribute to developing novel therapies for chronic inflammatory diseases and organ fibrosis.

Dioscin ameliorates slow transit constipation in mice by up-regulation of the BMP2 secreted by muscularis macrophages

Objectives

The loss of enteric neurons has been shown to be a major cause of slow transit constipation (STC). Gut microbiota and muscularis macrophages (MMs) are associated with the enteric nervous system (ENS) development and gastrointestinal (GI) motility. This study aimed to investigate whether Dioscin (DIO) increased GI motility and inhibited neuron loss by modulating gut microbiota profile, improving inflammation in the ENS microenvironment.

Materials and Methods

The STC model was established by loperamide. The alteration of the gut microbiota was analyzed by 16S rDNA sequencing. The longitudinal muscle and myenteric plexus (LMMP) from the colon were prepared for flow cytometry, immunofluorescence, western blot, and qRT-PCR.

Results

DIO increased the stool number, stool water content and shortened whole gut transit time, helped to recover the gut microbial diversity and microbiota community structure, and increased the abundance of Muribaculaceae in STC mice. Compared with the STC group, the number of MMs and the level of the iNOS, IL-6, and TNFα genes were significantly decreased following DIO treatment. Moreover, DIO may increase the number of HuC/D⁺ neurons per ganglion by up-regulating the BMP2 secreted by MMs and activating the BMP2/p-Smad1/5/9 signaling pathway. Furthermore, the level of excitatory neurotransmitter AchE in colon tissues exhibited a substantial increase in the DIO group. However, the level of inhibitory neurotransmitter VIP was markedly decreased.

Conclusion

Our results provide that DIO increases GI motility and inhibits neuron loss by modulating gut microbiota profile, improving inflammation in the ENS microenvironment and up-regulating the BMP2 secreted by MMs.

Transcriptome-wide association study identifies PSMB9 as a susceptibility gene for coal workers' pneumoconiosis

Coal workers' pneumoconiosis (CWP) is a type of typical occupational lung disease caused by prolonged inhalation of coal mine dust. The individuals' different genetic background may underlie their different susceptibility to develop pneumoconiosis, even under the same exposure level. This study aimed to identify susceptibility genes associated with CWP. Based on our previous genome-wide association study (GWAS, 202 CWP cases vs. 198 controls) and gene expression data obtained by analyzing human lungs and whole blood from the Genotype-Tissue Expression (GTEx) Portal, a transcriptome-wide association study (TWAS) was applied to identify CWP risk-related genes. Luciferase report gene assay, qRT-PCR, Western blot, immunofluorescence assay, and TUNEL assay were conducted to explore the potential role of the candidate gene in CWP. Proteasome 20S subunit beta 9 (PSMB9) was identified as a strong risk-related gene of CWP in both lungs and whole blood (Lungs: P_TWAS  = 4.22 × 10^-4 ; Whole blood: P_TWAS  = 2.11 × 10^-4 ). Single nucleotide polymorphisms (SNPs) rs2071480 and rs1351383, which locate in the promoter region and the first intron of the PSMB9 gene, were in high linkage disequilibrium (LD, r²  = 0.98) with the best GWAS SNP rs4713600 (G>T, OR = 0.55, 95% CI: 0.42-0.74, P = 6.86 × 10^-5 ). Both rs2071480 and rs1351383 significantly enhanced the transcriptional activity of PSMB9. Functional experiments revealed that silica exposure remarkably reduced the PSMB9 expression and caused cell apoptosis, while overexpression of PSMB9 markedly abolished silica-induced cell apoptosis. We here identified PSMB9 as a novel susceptibility gene for CWP and provided important insights into the further exploration of the CWP pathogenesis.

Tauroursodeoxycholic acid (TUDCA) disparate pharmacological effects to lung tissue-resident memory T cells contribute to alleviated silicosis

Exposure to crystalline silica (CS) results in a persistent pulmonary inflammatory response, which results in abnormal tissue repair and excessive matrix deposition. Due to vague pathogenesis, there is virtually no practical therapeutic approach. Here we showed the pharmacological effects of TUDCA on CS-induced pulmonary inflammation and fibrosis. It also helped a faster recovery of CS-impaired pulmonary function. Mechanistically, TUDCA suppressed interferon (IFN)-γ and interleukin (IL)-17A productions by pulmonary helper T (Th) cells. We demonstrated that CS-boosted cytokine-producing Th cells were effector memory (T_EM) phenotype. TUDCA decreased the pathogenic T_EM cells expansion in the lung. Using in vivo labeling method, we discovered the T_EM cells were lung tissue residency with CD103 expression. TUDCA's anti-fibrotic effects were linked to decreasing IFN-γ producing CD103^- T_EM-like and IL-17A producing CD103⁺ T_RM-like T cells as well as restricting T_RM-like Treg cells in the lung. Specifically, TUDCA could restrain CD103⁺ T_RM-like Treg cell proliferation but not limit the CD103^- ones. Further characterization study proved that though the Tregs originally came from the thymus, the expressing levels of ST-2 were different, which provides insights into TUDCA's various effects on cell proliferation. Collectively, our data paved the way to understanding the pathogenesis of silicosis and may provide new treatments for this pulmonary fibrotic disease.

Dioscin ameliorates inflammatory bowel disease by up-regulating miR-125a-5p to regulate macrophage polarization

PURPOSE

Dioscin has been proven to have anti-cancer, anti-inflammatory, and anti-infection roles. However, the role of Dioscin in inflammatory bowel disease (IBD) and its related mechanisms is unclear and needs further study.

METHODS

The colitis model in mice was established. After Dioscin (20, 40, or 80 mg/kg) treatment, the colon length was measured by a ruler. Histopathology, inflammatory cytokines, gut permeability, tight junction proteins, macrophage infiltration, macrophage polarization, and miR-125a-5p level were detected by hematoxylin-eosin staining, enzyme-linked immunosorbent assay, quantitative real-time polymerase chain reaction (qRT-PCR), FITC-dextran, Western blot, and flow cytometry. In vitro experiments, after RAW264.7 cells induced by lipopolysaccharide (LPS)/interleukin-4 (IL-4), were treated with Dioscin and miR-125a-5p inhibitor, miR-125a-5p level, cell vitality, inflammatory cytokines, and M1/M2 marker genes were measured by qRT-PCR and MTT assay.

RESULTS

Dioscin (20, 40, or 80 mg/kg) relieved DSS-triggered colitis and restrained the serum and colon of pro-inflammatory cytokines expression. Meanwhile, different concentrations' Dioscin weakened M1 macrophage polarization but facilitated tight junction protein expressions, M2 macrophage polarization, and miR-125a-5p level in colitic mice. Moreover, miR-125a-5p inhibitor reversed the modulation of Dioscin on miR-125a-5p expression, cell vitality, and inflammatory cytokines in lipopolysaccharide (LPS)-induced RAW264.7 cells. We further discovered that Dioscin restrained M1 marker gene (CD16) expression while intensifying M2 marker genes (CD206 and Arginase-1) expressions in vitro, which was reversed by miR-125a-5p inhibitor.

CONCLUSION

Dioscin modulated macrophage polarization by increasing miR-125a-5p, thereby improving the intestinal epithelial barrier function and reducing IBD.

Dioscin exhibits protective effects on in vivo and in vitro asthma models via suppressing TGF-β1/Smad2/3 and AKT pathways

Dioscin is a natural product that possesses protective effects on multiple chronic injuries, but its effects on asthma are not fully understood. Herein, we evaluated its effects on asthmatic mice established by ovalbumin (OVA) sensitization and challenges and further explored the mechanism. Inflammatory cells in bronchoalveolar lavage fluids (BALFs) were analyzed using Diff-Quik staining. OVA-specific immunoglobulin E (IgE)/IgG1 in serum and inflammatory cytokines (interleukin 4[IL-4], IL-5, IL-13, and tumor necrosis factor-α) in BALFs and lung tissues were measured using Enzyme-Linked Immunosorbent Assay Kits. Hematoxylin and eosin, periodic acid-Schiff, and immunohistochemistry staining showed histopathological changes in lung tissues. Epithelial-mesenchymal transition (EMT) in human bronchial epithelial (16HBE) cells was assessed by immunofluorescence staining. Hydroxyproline content was used to evaluate collagen deposition. Polymerase chain reaction and Western blot were performed to measure messenger RNA and protein expression. We found that dioscin treatment (particularly at the dose of 80 mg/kg) significantly inhibited pulmonary inflammation in asthmatic mice, as evidenced by the decreased serum OVA-specific IgE/IgG1 and the reduced inflammatory cells and cytokines in BALFs and lung tissues. Moreover, dioscin effectively ameliorated the goblet cell hyperplasia, mucus hypersecretion, collagen deposition, and smooth muscle hyperplasia in the airways of asthmatic mice. Mechanistically, dioscin restrained the activated TGF-β1/Smad2/3 and protein kinase B (AKT) signal pathways in lung tissues and potently reversed the TGF-β1-induced EMT and phosphorylation of Smad2/3 and AKT in 16HBE cells. Collectively, dioscin displayed protective effects on OVA-induced asthmatic mice via adjusting TGF-β1/Smad2/3 and AKT signal pathways, supporting the fact that dioscin could be a candidate for chronic asthma prevention in the future.

A Novel N-Arylpyridone Compound Alleviates the Inflammatory and Fibrotic Reaction of Silicosis by Inhibiting the ASK1-p38 Pathway and Regulating Macrophage Polarization

Silicosis is one of the potentially fatal occupational diseases characterized by respiratory dysfunction, chronic interstitial inflammation, and fibrosis, for which treatment options are limited. Previous studies showed that a novel N-arylpyridone compound named AKEX0011 exhibited anti-inflammatory and anti-fibrotic effects in bleomycin-induced pulmonary fibrosis; however, it is unknown whether it could also be effective against silicosis. Therefore, we sought to investigate the preventive and therapeutic roles of AKEX0011 in a silicosis rodent model and in a silica-stimulated macrophage cell line. In vivo, our results showed that AKEX0011 ameliorated silica-induced imaging lung damages, respiratory dysfunction, reduced the secretion of inflammatory and fibrotic factors (TNF-α, IL-1β, IL-6, TGF-β, IL-4, and IL-10), and the deposition of fibrosis-related proteins (collagen I, fibronectin, and α-SMA), regardless of early or advanced therapy. Specifically, we found that AKEX0011 attenuated silicosis by inhibiting apoptosis, blocking the ASK1-p38 MAPK signaling pathway, and regulating polarization of macrophages. In vitro, AKEX0011 inhibited macrophages from secreting inflammatory cytokines and inhibited apoptosis of macrophages in pre-treated and post-treated models, concurrent with blocking the ASK1-p38 pathway and inhibiting M1 polarization. Collectively, AKEX0011, as a novel N-arylpyridone compound, exerted protective effects for silica-induced pulmonary inflammation and fibrosis both in vivo and in vitro, and hence, it could be a strong drug candidate for the treatment of silicosis.