Pirfenidone ameliorates silica-induced lung inflammation and fibrosis in mice by inhibiting the secretion of interleukin-17A

Cannabidiol suppresses silica-induced pulmonary inflammation and fibrosis through regulating NLRP3/TGF-β1/Smad2/3 pathway

Silica-induced pulmonary fibrosis is an irreversible and progressive lung disease with limited treatments available. In this work, FDA-approved cannabidiol (CBD) was studied for its potential medical use in silicosis. In silicosis female C57BL/6 mice model, oral CBD or pirfenidone (PFD) on day 1 after intratracheal drip silica (150 mg/mL) and continued for 42 days. Lung inflammatory and fibrotic changes were studied using ELISA kits, H&E staining and Masson staining. Osteopontion (OPN) and α-smooth muscle actin (α-SMA) expression in lung tissues was determined using immunohistochemical staining. The results indicated that CBD attenuated silica-induced pulmonary inflammation and fibrosis. Human myeloid leukemia mononuclear cells (THP-1) were treated with silica (200 μg/mL) to induce cell damage, then CBD (10 μM, 20 μM) and PFD (100 μM) were incubated. In vitro experiments showed that CBD can effectively reduce the expression of NLRP3 inflammasome in THP-1 cells and subsequently block silica-stimulated transformation of fibromuscular-myofibroblast transition (FMT) by culturing human embryonic lung fibroblasts (MRC-5) in conditioned medium of THP-1 cells. Therefore, CBD exhibited the potential therapy for silicosis through inhibiting the silica-induced pulmonary inflammation and fibrosis via the NLRP3/TGF-β1/Smad2/3 signaling pathway.

The toxic effects and mechanisms of maternal exposure to Bisphenol F during gestation and lactation on lungs in female offspring mice

Epidemiologic studies suggest that prenatal exposure to bisphenols may increase the risk of respiratory disease in children. Bisphenol F (BPF), a member of the bisphenol family, is widely used in industrial production. However, the potential pulmonary toxic effects and mechanisms of BPF exposure on offspring remain unclear. In this study, maternal mice were exposed to 0, 40, 400, and 4000 μg/kg BPF during gestation and lactation. The results showed that an inflammatory response was observed in lungs of BPF-exposed female offspring mice, characterized by peribronchial inflammatory cell infiltration and an increase in the number of inflammatory cells in BALF. Subsequent transcriptome analysis identified a total of 685 differentially expressed genes (DEGs) were in lungs of female offspring mice exposed to high-dose BPF, with 526 upregulated genes and 159 downregulated genes. Among upregulated DEGs of top 10, most of the upregulated genes were associated with inflammatory responses. In addition, enrichment analysis showed that immunosuppression and oxidative damage were significantly enriched in lungs of female offspring mice, suggesting that BPF could induce immunosuppression and oxidative stress in lungs of female offspring mice. Overall, our findings provide mechanistic insights into the potential pulmonary toxicity associated with BPF exposure during gestation and lactation.

IL-17A's role in exacerbating radiation-induced lung injury: Autophagy impairment via the PP2A-mTOR pathway

OBJECTIVE

Radiation-induced lung injury (RILI) is a serious complication of radiotherapy, and the role of IL-17A in this process is not well understood. While IL-17A has been shown to modulate autophagy, conflicting reports exist regarding its activation or inhibition of autophagy. This study investigates the role of IL-17A in RILI and its effects on autophagy via the PP2A-mTOR pathway, with a focus on the PP2A B56α subunit.

METHODS

C57BL/6J mice and human lung epithelial cells (BEAS-2B) were exposed to radiation with or without recombinant IL-17A. Autophagy markers were analyzed using Western blotting, immunofluorescence, and autophagy flux assays. PP2A activity, specifically the B56α subunit, was measured. A PP2A agonist (DT-061) was used to verify its role in reversing IL-17A-mediated autophagy inhibition.

RESULTS

IL-17A inhibited autophagy in lung epithelial cells exposed to radiation by suppressing PP2A activity, particularly through downregulation of the B56α subunit, leading to mTOR activation and reduced autophagosome formation. Treatment with DT-061 restored autophagic activity and improved cell viability. These findings align with reports suggesting that IL-17A inhibits autophagy in certain contexts, while other studies have shown opposing effects.

CONCLUSION

IL-17A inhibits autophagy in RILI through the PP2A B56α-mTOR pathway, exacerbating lung damage. Further research is needed to clarify the role of IL-17A in different cell types and conditions. Targeting the IL-17A-PP2A B56α-mTOR axis may offer new therapeutic strategies for RILI management.

Cardamonin inhibits silicosis development through the PI3K-AKT signaling pathway

Silicosis is one of the most severe occupational diseases characterized by inflammatory cell infiltration, fibroblasts activation, and fibrosis in the lung. However, specific drug treatments are lacking. Cardamonin (CDM) has been reported to possess antitumor, anti-inflammatory/fibrotic effects. While, the effect of CDM on the progression of silicosis remains unknown. In this study, we established a SiO2-M stimulated fibroblast cell model, and explored the antifibrotic effect of CDM and the related molecular mechanism using WB, RT-qPCR, and immunofluorescence. The results indicate that CDM inhibits SiO2-M-induced fibroblast activation, proliferation, and migration. Furthermore, a silicosis mouse model was established through injecting silica suspension intratracheally. The results revealed that CDM retards the progression of pulmonary fibrosis. The RNA sequencing results suggest that the antifibrotic effect of CDM may be mediated by the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) signaling pathway. In conclusion, the results of this study demonstrate that CDM inhibits the development of silicosis via the PI3K-AKT signaling pathway, which could provide guidance for the development of drugs for silicosis treatment.

GAMG ameliorates silica-induced pulmonary inflammation and fibrosis via the regulation of EMT and NLRP3/TGF-β1/Smad signaling pathway

Silicosis is an occupational disease caused by exposure to silica characterized by pulmonary inflammation and fibrosis, for which there is a lack of effective drugs. Glycyrrhetinic acid 3-O-β-D-glucuronide (GAMG) can treat silicosis due to its anti-inflammatory and anti-fibrotic properties. Here, the effect of therapeutic interventions of GAMG was evaluated in early-stage and advanced silicosis mouse models. GAMG significantly improved fibrotic pathological changes and collagen deposition in the lungs, alleviated lung inflammation in the BALF, reduced the expression of TNF-α, IL-6, NLRP3, TGF-β1, vimentin, Col-Ⅰ, N-cadherin, and inhibited epithelial-mesenchymal transition (EMT), thereby ameliorating pulmonary fibrosis. Moreover, the dose of 100 mg/kg GAMG can effectively prevent early-stage silicosis, while that of 200 mg/kg was recommended for advanced silicosis. In vitro and in vivo study verified that GAMG can suppress EMT through the NLRP3/TGF-β1/Smad2/3 signaling pathway. Therefore, GAMG could be a promising preventive (early-stage silicosis) and therapeutic (advanced silicosis) strategy, which provides a new idea for formulating prevention and treatment strategies.

Pirfenidone targeted mechanisms for alleviating methotrexate-induced testiculopathy in Wistar rats

Testicular injury and affected spermatogenesis are major complications of methotrexate (MTX) use. Oxidative stress is one contributing process leading to inflammation and apoptosis induction. Pirfenidone (PFD) is a well-known anti-fibrotic drug prescribed for interstitial lung fibrosis, in addition to anti-inflammatory, antioxidative, and antiapoptotic capabilities. The study aimed to explore the potential protection afforded by PFD in a rat model of MTX-induced testiculopathy. The experimental design included four groups, each containing seven adult Wistar rats: control, PFD (500 mg/kg/day, orally)-, MTX (0.5 mg/kg, intraperitoneal, twice weekly)-, and PFD/MTX-treated groups. Treatment continued for 4 weeks. Blood and testicular samples were harvested for biochemical, histological, immunohistochemical, and polymerase chain reaction (PCR) analyses. Also, the testicular damage and spermatogenic activity were graded by the testicular injury and Johnsen scoring system, respectively. PFD positively affected the serum testosterone (TST) level, reduced the testicular inflammatory mediators [tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β)], reduced the testicular oxidative burden, increased superoxide dismutase (SOD), and protected the testicular histological structure. In addition, antifibrotic effects, anti-caspase-3, and PCNA enhancement activity were recorded. PFD exhibited a protective potential and mitigated the MTX-induced testiculopathy via suppression of testicular oxidative stress, inflammation, fibrosis, and apoptosis and retaining the testicular proliferative efficacy as confirmed by histological, immunohistochemical, and biochemical methods.

PKM2/Hif-1α signal suppression involved in therapeutics of pulmonary fibrosis with microcystin-RR but not with pirfenidone

To date there are only pirfenidone (PFD) and nintedanib to be given conditional recommendation in idiopathic pulmonary fibrosis (IPF) therapies with slowing disease progression, but neither has prospectively shown a reduced mortality. It is one of the urgent topics to find effective drugs for pulmonary fibrosis in medicine. Previous studies have demonstrated that microcystin-RR (MC-RR) effectively alleviates bleomycin-induced pulmonary fibrosis, but the mechanism has not been fully elucidated yet. We further conducted a comparison of therapeutic effect on the model animals of pulmonary fibrosis between MC-RR and PFD with histopathology and the expression of the molecular markers involved in differentiation, proliferation and metabolism of myofibroblasts, a major effector cell of tissue fibrosis. The levels of the enzyme molecules for maintaining the stability of interstitial structure were also evaluated. Our results showed that MC-RR and PFD effectively alleviated pulmonary fibrosis in model mice with a decreased signaling and marker molecules associated with myofibroblast differentiation and lung fibrotic lesion. In the meantime, both MC-RR and PFD treatment are beneficial to restore molecular dynamics of interstitial tissue and maintain the stability of interstitial architecture. Unexpectedly, MC-RR, rather than PFD, showed a significant effect on inhibiting PKM2-HIF-1α signaling and reducing the level of p-STAT3. Additionally, MC-RR showed a better inhibition effect on FGFR1 expression. Given that PKM2-HIF-1α and activated STAT3 molecular present a critical role in promoting the proliferation of myofibroblasts, MC-RR as a new strategy for IPF treatment has potential advantage over PFD.

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.

Use of pirfenidone in fibrotic interstitial lung diseases and beyond: a review

The pathophysiological mechanisms involved in fibrotic interstitial lung diseases (FILDs) are akin to those observed in idiopathic pulmonary fibrosis (IPF), implying the potential for shared therapeutic approaches. Pirfenidone exhibits antifibrotic and anti-inflammatory properties, making it the first small-molecule drug approved for treating IPF. Pirfenidone has been utilized in IPF treatment for more than one decade. However, guidelines for progressive pulmonary fibrosis (PPF) treatment suggest that further research and evidence are needed to fully comprehend its efficacy and safety across various PPF subtypes. In recent years, numerous studies have explored the use of pirfenidone in treating non-IPF FILD. Herein, we provide an overview of the latest research data on application of pirfenidone in occupational-related ILD, connective tissue disease-associated ILD, post-coronavirus disease-2019 pulmonary fibrosis, and other conditions. We summarize the level of evidence and highlight challenges associated with using pirfenidone in different FILDs to offer clinical guidance.

Integration of serum pharmacochemistry with network pharmacology to reveal the potential mechanism of Yangqing Chenfei formula for the treatment of silicosis

OBJECTIVE

To explore the mechanisms of Yangqing Chenfei formula (, YCF) in the treatment of silicosis through a comprehensive strategy consisting of serum pharmacochemistry, network pharmacology analysis, and in vitro validation.

METHODS

An ultrahigh-performance liquid chroma-tography-tandem mass spectrometry method was used to confirm the active components in YCF-medicated serum. Then, we obtained targets for active components and genes for silicosis from multiple databases. Furthermore, a protein-protein interaction network was constructed, and Kyoto Encyclopedia of Genes and Genomes pathway and biological process analyses were conducted to elucidate the mechanisms of YCF for the treatment of silicosis. Finally, we validated the important components and mechanisms in vitro.

RESULTS

Altogether, 19 active components were identified from rat serum after YCF administration. We identified 724 targets for 19 components, which were mainly related to inflammation [phosphatidy linositol 3 kinase/protein kinase B, forkhead box O, hypoxia inducible factor, and T-cell receptor signaling pathway, nitric oxide biosynthetic process], fibrotic processes [vascular endothelial growth factor signaling pathway, extracellular signal regulated kinase (ERK) 1 and ERK2 cascade, smooth muscle cell proliferation], and apoptosis (negative regulation of apoptotic process). In addition, 218 genes for silicosis were identified and were mainly associated with the inflammatory response and immune process [cytokine?cytokine receptor interaction, tumor necrosis factor alpha (TNF-α), toll-like receptor, and nucleotide binding oligomerization domain-like receptor signaling pathway]. Taking an intersection of active component targets and silicosis genes, we obtained 61 common genes that were mainly related to the inflammatory response and apoptosis, such as the phosphatidylinositol-3-kinase/protein kinase B signaling pathway, mitogen activated protein kinases signaling pathway, TNF signaling pathway, toll-like receptor signaling pathway, biosynthesis of nitric oxide, and apoptotic process. In the herb-component-gene-pathway network, paeoniflorin, rutin and nobiletin targeted the most genes. In vitro, paeoniflorin, rutin and nobiletin decreased the mRNA levels of inflammatory factors [interleukin (IL)-6, TNF-α, and IL-1β], suppressed p-AKT and cleaved caspase-3, and increased B cell lymphoma (Bcl)-2 protein expression in silica-induced macrophages in a concentration-dependent manner.

CONCLUSION

YCF could significantly relieve the inflammatory response of silicosis via suppression of the AKT/Bcl-2/Caspase-3 pathway.

Paeoniflorin mitigates MMP-12 inflammation in silicosis via Yang-Yin-Qing-Fei Decoction in murine models

BACKGROUND

Silicosis presents a significant clinical challenges and economic burdens, with Traditional Chinese Medicine (TCM) emerging as a potential therapeutic avenue. However, the precise effects and mechanisms of TCM in treating silicosis remain uncertain and subject to debate.

OBJECTIVE

The study aims to elucidate the therapeutic role and mechanisms of the Yang-Yin-Qing-Fei Decoction (YYQFD) and its key component, paeoniflorin, in silicosis using a murine model.

METHODS

Silicotic mice were treated with YYQFD, pirfenidone (PFD), or paeoniflorin. RAW264.7 cells and mouse lung fibroblasts (MLF) were stimulated with silica, matrix metalloproteinase-12 (MMP-12), or TGF-β1, followed by treatment with paeoniflorin, PFD, or relevant inhibitors. YYQFD constituents were characterized using High-Performance Liquid Chromatography (HPLC). Lung fibrosis severity was assessed via histopathological examination, micro-CT imaging, lung functions, and Western blot analysis. Transcriptome sequencing and bioinformatics analysis were employed to delineate the gene expression profile and target genes modulated by YYQFD in silicosis.

RESULTS

Treatment with YYQFD ameliorated silica-induced lung fibrosis. Transcriptome sequencing identified MMP-12 as a potential common target of YYQFD and PFD. Additionally, a potential pro-inflammatory role of MMP-12, regulated by silica-induced TLR4 signaling pathways, was revealed. Paeoniflorin, one of the most distinctive compounds in YYQFD, attenuated silica-induced MMP-12 increase and its derived inflammatory factors in macrophages through a direct binding effect. Notably, paeoniflorin treatment exerted anti-fibrotic effects by inhibiting MMP-12-derived inflammatory factors and TGF-β1-induced myofibroblast differentiation in silica-exposed mice.

CONCLUSIONS

This study underscores paeoniflorin as one of the most principal bioactive compounds in YYQFD, highlighting its capacity to attenuate lung inflammation driven by macrophage-derived MMP-12 and reduce lung fibrosis both in vivo and in vitro.

Arsenic exposure induced renal fibrosis via regulation of mitochondrial dynamics and the NLRP3-TGF-β1/SMAD signaling pathway

Environmental arsenic exposure is one of the major global public health problems. Studies have shown that arsenic exposure can cause renal fibrosis, but the underlying mechanism is still unclear. Integrating the in vivo and in vitro models, this study investigated the potential molecular pathways for arsenic-induced renal fibrosis. In this study, SD rats were treated with 0, 5, 25, 50, and 100 mg/L NaAsO2 for 8 weeks via drinking water, and HK2 cells were treated with different doses of NaAsO2 for 48 h. The in vivo results showed that arsenic content in the rats' kidneys increased as the dose increased. Body weight decreased and kidney coefficient increased at 100 mg/L. As a response to the elevated NaAsO2 dose, inflammatory cell infiltration, renal tubular injury, glomerular atrophy, tubulointerstitial hemorrhage, and fibrosis became more obvious indicated by HE and Masson staining. The kidney transcriptome profiles further supported the protein-protein interactions involved in NaAsO2-induced renal fibrosis. The in vivo results, in together with the in vitro experiments, have revealed that exposure to NaAsO2 disturbed mitochondrial dynamics, promoted mitophagy, activated inflammation and the TGF-β1/SMAD signaling pathway, and finally resulted in fibrosis. In summary, arsenic exposure contributed to renal fibrosis via regulating the mitochondrial dynamics and the NLRP3-TGF-β1/SMAD signaling axis. This study presented an adverse outcome pathway for the development of renal fibrosis due to arsenic exposure through drinking water.

Whole transcriptome sequencing identifies key lncRNAs,circRNAs, and mRNAs for exploring the pathogenesis and therapeutic target of mouse pneumoconiosis

BACKGROUND

Pneumoconiosis is a kind of lung dysfunction caused by the inhalation of mineral dust. However, the potential molecular mechanism of pneumoconiosis have not been fully elucidated.

METHODS

In this study, the silica-treated pneumoconiosis mice model was constructed and the transcriptome sequencing data including lncRNA, circRNA, and mRNA were obtained. Firstly, differentially expressed lncRNA, circRNA, and mRNA (DElncRNA, DEcircRNA, DEGs) between control and pneumoconiosis/silicosis samples were screened, the target miRNAs (co-pre-miRNAs) were obtained by intersecting the miRNAs predicted by DElncRNA and DEcircRNA, respectively, and the target mRNAs (co-mRNA) were obtained by intersecting the mRNAs predicted by target miRNA and DEGs. Then, the lncRNA/circRNA-miRNA-mRNA networks were constructed by Cytoscape. Next, the key mRNAs were obtained by protein-protein interaction (PPI) analysis, and the key lncRNAs/circRNAs were selected by correlation analysis. Moreover, the expression of the key lncRNAs, circRNAs and mRNAs on chromosome were studied by the "circlize" package. Furthermore, the TFs-miRNA-mRNA network was constructed and the function of DEGs were explored by Ingenuity Pathway Analysis (IPA). To demonstrate the feasibility and value of the constructed ceRNA networks, we validated key genes and mmu-miR-682 pathway. Finally, We used the Drug-Gene Interaction database to predict potential drugs that could interfere with key genes,which may help to find promising treatment.

RESULTS

There were 427 DElncRNAs, 107 DEcircRNAs and 1,597 DEGs between silicosis and control groups. Totals of 77 co-pre-miRNAs and 96 co-mRNA were screened, and the lncRNA/circRNA-miRNA-mRNA networks were constructed with 27 lncRNA/25 circRNAs, 74 miRNAs and 96 mRNAs. Then, 6 key mRNAs including Igf1, Klf4, Ptgs2, Epas1, Gnao1, and Il1a were obtained by PPI, and all of these key mRNAs and 10 key lncRNAs and 8 circRNAs were significantly different between the pneumoconiosis and normal groups, in which 10 lncRNAs and 9 circRNA that have not been previously studied in pneumoconiosis/silicosis can be used as new potential therapeutic targets. Moreover, the TFs-miRNA-mRNA network were constructed with 11 TFs, 1 key miRNA (mmu-miR-682) and 3 key mRNAs (Igf1, Epas1, Ptgs2). And the validation of key genes revealing by RNA-seq through experimental approaches shows the the predictive power of this study. Finally, IPA results indicated that 41 pathways were activated and 2 pathways were suppressed in pneumoconiosis/silicosis groups, and Pathogen Induced Cytokine Storm Signaling Pathway was the most significant pathway affected by pneumoconiosis/silicosis. In addition, 93 drugs were screened out by Drug-Gene Interaction database. Among them, Hydroxychloroquine was a kind of drug which associated with Il1a and Ptgs2, may be a promising treatment.

CONCLUSION

This study constructed the lncRNA/circRNA-miRNA-mRNA and TFs-miRNA-mRNA networks, which could deepen the potential molecular regulatory mechanism of pneumoconiosis/silicosis.

Silica-induced macrophage pyroptosis propels pulmonary fibrosis through coordinated activation of relaxin and osteoclast differentiation signaling to reprogram fibroblasts

Silica nanoparticle (SiNP) exposure induces severe pulmonary inflammation and fibrosis, but the pathogenesis remains unclear, and effective therapies are currently lacking. To explore the mechanism underlying SiNPs-induced pulmonary fibrosis, we constructed in vivo silica exposure animal models and in vitro models of silica-induced macrophage pyroptosis and fibroblast transdifferentiation. We found that SiNP exposure elicits upregulation of pulmonary proteins associated with pyroptosis, including NLRP3, ASC, IL-1β, and GSDMD, while the immunofluorescence staining co-localized NLRP3 and GSDMD with macrophage-specific biomarker F4/80 in silica-exposed lung tissues. However, the NLRP3 inhibitor MCC950 and classical anti-fibrosis drug pirfenidone (PFD) were found to be able to alleviate silica-induced collagen deposition in the lungs. In in vitro studies, we exposed the fibroblast to a conditioned medium from silica-induced pyroptotic macrophages and found enhanced expression of α-SMA, suggesting increased transdifferentiation of fibroblast to myofibroblast. In line with in vivo studies, the combined treatment of MCC950 and PFD was demonstrated to inhibit the expression of α-SMA and attenuate fibroblast transdifferentiation. Mechanistically, we adopted high throughput RNA sequencing on fibroblast with different treatments and found activated signaling of relaxin and osteoclast differentiation pathways, where the expression of the dysregulated genes in these two pathways was examined and found to be consistently altered both in vitro and in vivo. Collectively, our study demonstrates that SiNP exposure induces macrophage pyroptosis, which subsequently causes fibroblast transdifferentiation to myofibroblasts, in which the relaxin and osteoclast differentiation signaling pathways play crucial roles. These findings may provide valuable references for developing new therapies for pulmonary fibrosis.

The role of inflammation in silicosis

Silicosis is a chronic illness marked by diffuse fibrosis in lung tissue resulting from continuous exposure to SiO2-rich dust in the workplace. The onset and progression of silicosis is a complicated and poorly understood pathological process involving numerous cells and molecules. However, silicosis poses a severe threat to public health in developing countries, where it is the most prevalent occupational disease. There is convincing evidence supporting that innate and adaptive immune cells, as well as their cytokines, play a significant role in the development of silicosis. In this review, we describe the roles of immune cells and cytokines in silicosis, and summarize current knowledge on several important inflammatory signaling pathways associated with the disease, aiming to provide novel targets and strategies for the treatment of silicosis-related inflammation.

Toward targeted treatments for silicosis

PURPOSE OF REVIEW

There has been a rapid increase in silicosis cases, particularly related to artificial stone. The key to management is avoidance of silica exposure. Despite this, many develop progressive disease and there are no routinely recommended treatments. This review provides a summary of the literature pertaining to pharmacological therapies for silicosis and examines the plausibility of success of such treatments given the disease pathogenesis.

RECENT FINDINGS

In-vitro and in-vivo models demonstrate potential efficacy for drugs, which target inflammasomes, cytokines, effector cells, fibrosis, autophagy, and oxidation.

SUMMARY

There is some evidence for potential therapeutic targets in silicosis but limited translation into human studies. Treatment of silicosis likely requires a multimodal approach, and there is considerable cross-talk between pathways; agents that modulate both inflammation, fibrosis, autophagy, and ROS production are likely to be most efficacious.

Results from omic approaches in rat or mouse models exposed to inhaled crystalline silica: a systematic review

BACKGROUND

Crystalline silica (cSiO2) is a mineral found in rocks; workers from the construction or denim industries are particularly exposed to cSiO2 through inhalation. cSiO2 inhalation increases the risk of silicosis and systemic autoimmune diseases. Inhaled cSiO2 microparticles can reach the alveoli where they induce inflammation, cell death, auto-immunity and fibrosis but the specific molecular pathways involved in these cSiO2 effects remain unclear. This systematic review aims to provide a comprehensive state of the art on omic approaches and exposure models used to study the effects of inhaled cSiO2 in mice and rats and to highlight key results from omic data in rodents also validated in human.

METHODS

The protocol of systematic review follows PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Eligible articles were identified in PubMed, Embase and Web of Science. The search strategy included original articles published after 1990 and written in English which included mouse or rat models exposed to cSiO2 and utilized omic approaches to identify pathways modulated by cSiO2. Data were extracted and quality assessment was based on the SYRCLE's Risk of Bias tool for animal studies.

RESULTS

Rats and male rodents were the more used models while female rodents and autoimmune prone models were less studied. Exposure of animals were both acute and chronic and the timing of outcome measurement through omics approaches were homogeneously distributed. Transcriptomic techniques were more commonly performed while proteomic, metabolomic and single-cell omic methods were less utilized. Immunity and inflammation were the main domains modified by cSiO2 exposure in lungs of mice and rats. Less than 20% of the results obtained in rodents were finally verified in humans.

CONCLUSION

Omic technics offer new insights on the effects of cSiO2 exposure in mice and rats although the majority of data still need to be validated in humans. Autoimmune prone model should be better characterised and systemic effects of cSiO2 need to be further studied to better understand cSiO2-induced autoimmunity. Single-cell omics should be performed to inform on pathological processes induced by cSiO2 exposure.

Single-cell transcriptomics reveals the pulmonary inflammation induced by inhalation of subway fine particles

People generally take the subway and inevitably inhale the fine particles (PM2.5) on subway platforms. This study revealed whether and how subway PM2.5 causes lung inflammation. Herein, the pulmonary inflammatory response to subway PM2.5 was observed in mice, manifesting as the inflammatory cells infiltration and collagen deposition in tissue, inflammatory cytokine enhancement in bronchoalveolar lavage fluid and Toll-like receptors signal pathway activation in the lungs. Furthermore, single-cell RNA sequencing unearthed subway PM2.5-induced cell-specific responses in the lungs. Twenty immune subsets were identified by the molecular and functional properties. Specific cell populations of CD4+ T and γδ T cells were regarded as the predominant sources of pneumonitis induced by subway PM2.5. Moreover, we demonstrated that the lung inflammatory injury was significantly more attenuated in Rag1-/- mice lacking functional T cells and B cells than that in wild type mice. We proved the slight inflammation of lung tissue in Rag1-/- mice may be dependent on monocytes and neutrophils by activation of the intracellular molecular network. This is the first experimental study on subway PM2.5 causing pulmonary inflammatory damage. It will set an alarm for people who usually travel by subway and efficient measures to reduce PM2.5 should be developed in subway stations.

The Peptide DHα-(4-pentenyl)-ANPQIR-NH2 Exhibits Antifibrotic Activity in Multiple Pulmonary Fibrosis Models Induced by Particulate and Soluble Chemical Fibrogenic Agents

Interstitial lung diseases (ILDs) are a group of restrictive lung diseases characterized by interstitial inflammation and pulmonary fibrosis. The incidence of ILDs associated with exposure to multiple hazards such as inhaled particles, fibers, and ingested soluble chemicals is increasing yearly, and there are no ideal drugs currently available. Our previous research showed that the novel and low-toxicity peptide DHα-(4-pentenyl)-ANPQIR-NH2 (DR3penA) had a strong antifibrotic effect on a bleomycin-induced murine model. Based on the druggability of DR3penA, we sought to investigate its effects on respirable particulate silicon dioxide (SiO2)- and soluble chemical paraquat (PQ)-induced pulmonary fibrosis in this study by using western blot, quantitative reverse-transcription polymerase chain reaction (RT-qPCR), immunofluorescence, H&E and Masson staining, immunohistochemistry, and serum biochemical assays. The results showed that DR3penA alleviated the extent of fibrosis by inhibiting the expression of fibronectin and collagen I and suppressed oxidative stress and epithelial-mesenchymal transition (EMT) in vitro and in vivo. Further study revealed that DR3penA may mitigate pulmonary fibrosis by negatively regulating the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway and mitogen-activated protein kinase (MAPK) pathway. Unexpectedly, through the conversion of drug bioavailability under different routes of administration, DR3penA exerted antifibrotic effects equivalent to those of the positive control drug pirfenidone (PFD) at lower doses. In summary, DR3penA may be a promising lead compound for various fibrotic ILDs. SIGNIFICANCE STATEMENT: Our study verified that DHα-(4-pentenyl)-ANPQIR-NH2 (DR3penA) exhibited positive antifibrotic activity in pulmonary fibrosis induced by silicon dioxide (SiO2) particles and soluble chemical paraquat (PQ) and demonstrated a low-dose advantage compared to the small-molecule drug pirfenidone (PFD). The peptide DR3penA can be further developed for the treatment of multiple fibrotic lung diseases.

Identifying the Anti-inflammatory Effects of Astragalus Polysaccharides in Anti-N-Methyl-D-Aspartate Receptor Encephalitis: Network Pharmacology and Experimental Validation

BACKGROUND

Astragalus polysaccharides (APS), a group of bioactive compounds obtained from the natural source Astragalus membranaceus (AM), exhibits numerous pharmacological actions in the central nervous system, such as anti-inflammatory, antioxidant, and immunomodulatory properties. Despite the remarkable benefits, the effectiveness of APS in treating anti- N-methyl-D-aspartate receptor (NMDAR) encephalitis and the corresponding mechanism have yet to be fully understood. As such, this study aims to investigate the impact of APS on anti-NMDAR encephalitis and explore the potential molecular network mechanism.

METHODS

The impact of APS intervention on mice with anti-NMDAR encephalitis was assessed, and the possible molecular network mechanism was investigated utilizing network pharmacology and bioinformatics techniques such as Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG),protein-protein interaction (PPI) network, and molecular docking. Enzymelinked immunosorbent assay (ELISA) was applied to detect the expression of core target proteins.

RESULTS

APS significantly ameliorated cognitive impairment and reduced susceptibility to PTZinduced seizures in mice with anti-NMDAR encephalitis, confirming the beneficial effect of APS on anti-NMDAR encephalitis. Seventeen intersecting genes were identified between APS and anti- NMDAR encephalitis. GO and KEGG analyses revealed the characteristics of the intersecting gene networks. STRING interaction in the PPI network was applied to find crucial molecules. The results of molecular docking suggested that APS may regulate interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) as potential targets in anti-NMDAR encephalitis. Furthermore, the levels of IL-1β, IL-6, and TNF-α detected by ELISA in anti-NMDAR encephalitis mice were significantly downregulated in response to the administration of APS.

CONCLUSION

The findings of this study demonstrate the significant role of APS in the treatment of anti-NMDAR encephalitis, as it effectively suppresses inflammatory cytokines. These results suggest that APS has the potential to be considered as a viable herbal medication for the treatment of anti-NMDAR encephalitis.

Exercise training inhibits macrophage-derived IL-17A-CXCL5-CXCR2 inflammatory axis to attenuate pulmonary fibrosis in mice exposed to silica

Exposure to crystalline silica leads to health effects beyond occupational silicosis. Exercise training's potential benefits on pulmonary diseases yield inconsistent outcomes. In this study, we utilized experimental silicotic mice subjected to exercise training and pharmacological interventions, including interleukin-17A (IL-17A) neutralizing antibody or clodronate liposome for macrophage depletion. Findings reveal exercise training's ability to mitigate silicosis progression in mice by suppressing scavenger receptor B (SRB)/NOD-like receptor thermal protein domain associated protein 3 (NLRP3) and Toll-like receptor 4 (TLR4) pathways. Macrophage-derived IL-17A emerges as primary source and trigger for silica-induced pulmonary inflammation and fibrosis. Exercise training effectively inhibits IL-17A-CXC motif chemokine ligand 5 (CXCL5)-Chemokine (C-X-C motif) Receptor 2 (CXCR2) axis in silicotic mice. Our study evidences exercise training's potential to reduce collagen deposition, preserve elastic fibers, slow pulmonary fibrosis advancement, and enhance pulmonary function post silica exposure by impeding macrophage-derived IL-17A-CXCL5-CXCR2 axis.

Evaluation of prevention and treatment effects of fibroblast growth factor-21 in BLM-induced pulmonary fibrosis

Pulmonary fibrosis is a progressive and fatal fibrotic lung disease and associated with a high mortality rate. In the study, the prevention and treatment effects of fibroblast growth factor-21 (FGF-21) in bleomycin (BLM)-induced pulmonary fibrosis were investigated in vivo and vitro. In the prevention of pulmonary fibrosis studies, the results showed that interdict of FGF-21 could reduce the related gene and protein expression levels of pulmonary fibrosis. In addition, FGF-21 significantly reduced both the aggregation of inflammatory cells and deposition of collagen in the lung by histopathology. In therapy of pulmonary fibrosis studies, the results indicated that treatment with FGF-21 resulted in an amelioration of the pulmonary fibrosis in mice with reductions of the pathological score, collagen deposition and transforming growth factor (TGF)-β and α-smooth muscle actin (α-SMA) expressions in the lung tissues at fibrotic stage, and late administration was also able to reduce the degree of pulmonary fibrosis and even better than these in the prevention group. Furthermore, BLM-induced THP-1 macrophage model was verified using FGF-21; the result showed that FGF-21 decreased the related gene expression level of pulmonary fibrosis. FGF-21 may have preventive and therapeutic effects on BLM-induced pulmonary fibrosis via inhibiting myofibroblast differentiation and inflammatory. Thus, FGF-21 represents a potential drug for the prevention and treatment of pulmonary fibrosis.

Wnt/β-catenin signaling pathway promotes abnormal activation of fibroblast-like synoviocytes and angiogenesis in rheumatoid arthritis and the intervention of Er Miao San

BACKGROUND

Er Miao San (EMS) is an important herbal formula and a representative prescription for the treatment of the downwards flow of damp-heat syndrome. Clinical practice has proven that EMS can effectively treat rheumatoid arthritis (RA). Previous studies have demonstrated that EMS regulates the functions of T cells and dendritic cells and affects the polarization of macrophages. However, it is not clear whether the inhibitory effect of EMS on RA is related to the regulation of abnormal synovial activation and angiogenesis.

PURPOSE

The aim of this study was to elucidate the effect and potential mechanisms of EMS on the abnormal activation and angiogenesis of fibroblast-like synoviocytes (FLSs) in RA.

METHODS

The effect of EMS on rats with adjuvant arthritis (AA) and MH7A cells was examined by X-ray, haematoxylin-eosin (HE) staining, immunohistochemistry (IHC), ELISA and western blotting. Angiogenesis in AA rats was measured by a small animal ultrasound imaging system, immunofluorescence (IF) analysis and ELISA. An exchange between MH7A cells and HUVECs was induced using conditioned media that mimicked the microenvironment in vivo. CCK-8, western blotting, and scratch healing and Transwell migration assays were used to evaluate the effect of EMS on the Wnt/β-catenin signaling pathway and angiogenesis in the inflammatory microenvironment of RA.

RESULTS

Our results showed that EMS had a protective effect on AA rats. On the one hand, there was a decrease in paw swelling, the arthritis index, organ indices and proinflammatory factor levels, as well as relief of joint damage. On the other hand, blood flow, the number of immature blood vessels and proangiogenic factors were decreased. Furthermore, EMS reduced the expression of the Wnt/β-catenin signaling pathway in the synovial tissue of AA rats and MH7A cells. In the inflammatory microenvonrment of RA, the results were consistent.

CONCLUSION

This study demonstrated that EMS could protect against RA by inhibiting the abnormal activation and angiogenesis of FLSs, and the mechanism may be related to inhibiting the activation of the Wnt/β-catenin signaling pathway.

ISRIB inhibits the senescence of type II pulmonary epithelial cells to alleviate pulmonary fibrosis induced by silica in mice

The role and mechanisms of integrated stress response inhibitor (ISRIB) on silicosis are still not well defined. In the present study, the effects of ISRIB on cellular senescence and pulmonary fibrosis in silicosis were evaluated by RNA sequencing, micro-computed tomography, pulmonary function assessment, histological examination, and Western blot analysis. The results showed that ISRIB significantly reduced the degree of pulmonary fibrosis in mice with silicosis and reduced the expression of type I collagen, fibronectin, α-smooth muscle actin, and transforming growth factor-β1. Both in vivo and in vitro results showed that ISRIB reversed the expression of senescence-related factors β-galactosidase, phosphor-ataxia telangiectasia mutated, phosphor-ataxia telangiectasia and Rad3-related protein, p-p53, p21, p16, and plasminogen activator inhibitor type 1. The aforementioned results were consistent with the sequencing results. These findings implied that ISRIB might reduce the degree of pulmonary fibrosis in mice with silicosis by inhibiting the cellular senescence of alveolar epithelial cell type II.

Total sesquiterpenoids from Eupatorium lindleyanum DC. attenuate bleomycin-induced lung fibrosis by suppressing myofibroblast transition

Eupatorium lindleyanum DC. has been used as a functional food in China for a long time. However, the antifibrotic activity of total sesquiterpenoids from Eupatorium lindleyanum DC. (TS-EL) is still unknown. In this study, we discovered that TS-EL reduced the increase in α-smooth muscle actin (α-SMA), type I collagen and fibronectin content, the formation of cell filaments and collagen gel contraction in transforming growth factor-β1-stimulated human lung fibroblasts. Intriguingly, TS-EL did not change the phosphorylation of Smad2/3 and Erk1/2. TS-EL decreased the levels of serum response factor (SRF), a critical transcription factor of α-SMA, and SRF knockdown alleviated the transition of lung myofibroblasts. Furthermore, TS-EL significantly attenuated bleomycin (BLM)-induced lung pathology and collagen deposition and reduced the levels of two profibrotic markers, total lung hydroxyproline and α-SMA. TS-EL also decreased the levels of SRF protein expression in BLM-induced mice. These results suggested that TS-EL attenuates pulmonary fibrosis by inhibiting myofibroblast transition via the downregulation of SRF.

The vascular perspective on acute and chronic lung disease

The pulmonary vasculature has been frequently overlooked in acute and chronic lung diseases, such as acute respiratory distress syndrome (ARDS), pulmonary fibrosis (PF), and chronic obstructive pulmonary disease (COPD). The primary emphasis in the management of these parenchymal disorders has largely revolved around the injury and aberrant repair of epithelial cells. However, there is increasing evidence that the vascular endothelium plays an active role in the development of acute and chronic lung diseases. The endothelial cell network in the capillary bed and the arterial and venous vessels provides a metabolically highly active barrier that controls the migration of immune cells, regulates vascular tone and permeability, and participates in the remodeling processes. Phenotypically and functionally altered endothelial cells, and remodeled vessels, can be found in acute and chronic lung diseases, although to different degrees, likely because of disease-specific mechanisms. Since vascular remodeling is associated with pulmonary hypertension, which worsens patient outcomes and survival, it is crucial to understand the underlying vascular alterations. In this Review, we describe the current knowledge regarding the role of the pulmonary vasculature in the development and progression of ARDS, PF, and COPD; we also outline future research directions with the hope of facilitating the development of mechanism-based therapies.

MiR-26a-5p from HucMSC-derived extracellular vesicles inhibits epithelial mesenchymal transition by targeting Adam17 in silica-induced lung fibrosis

Silicosis is one of several potentially fatal occupational pathologies caused by the prolonged inhalation of respirable crystalline silica. Previous studies have shown that lung epithelial-mesenchymal transition (EMT) plays a significant role in the fibrosis effect of silicosis. Human umbilical cord mesenchymal stem cells-derived Extracellular vesicles (hucMSC-EVs) have attracted great interest as a potential therapy of EMT and fibrosis-related diseases. However, the potential effects of hucMSC-EVs in inhibiting EMT in silica-induced fibrosis, as well as its underlying mechanisms, remain largely unknown. In this study, we used the EMT model in MLE-12 cells and observed the effects and mechanism of hucMSC-EVs inhibition of EMT. The results revealed that hucMSC-EVs can indeed inhibit EMT. MiR-26a-5p was highly enriched in hucMSC-EVs but was down-regulated in silicosis mice. We found that miR-26a-5p in hucMSC-EVs was over-expressed after transfecting miR-26a-5p expressing lentivirus vectors into hucMSCs. Subsequently, we explored if miR-26a-5p, attained from hucMSC-EVs, was involved in inhibiting EMT in silica-induced lung fibrosis. Our findings suggested that hucMSC-EVs could deliver miR-26a-5p into MLE-12 cells and cause the inhibition of the Adam17/Notch signalling pathway to ameliorate EMT in silica-induced pulmonary fibrosis. These findings might represent a novel insight into treating silicosis fibrosis.

Pirfenidone Inhibits Alveolar Bone Loss in Ligature-Induced Periodontitis by Suppressing the NF-κB Signaling Pathway in Mice

There has been increasing interest in adjunctive use of anti-inflammatory drugs to control periodontitis. This study was performed to examine the effects of pirfenidone (PFD) on alveolar bone loss in ligature-induced periodontitis in mice and identify the relevant mechanisms. Experimental periodontitis was established by ligating the unilateral maxillary second molar for 7 days in mice (n = 8 per group), and PFD was administered daily via intraperitoneal injection. The micro-computed tomography and histology analyses were performed to determine changes in the alveolar bone following the PFD administration. For in vitro analysis, bone marrow macrophages (BMMs) were isolated from mice and cultured with PFD in the presence of RANKL or LPS. The effectiveness of PFD on osteoclastogenesis, inflammatory cytokine expression, and NF-κB activation was determined with RT-PCR, Western blot, and immunofluorescence analyses. PFD treatment significantly inhibited the ligature-induced alveolar bone loss, with decreases in TRAP-positive osteoclasts and expression of inflammatory cytokines in mice. In cultured BMM cells, PFD also inhibited RANKL-induced osteoclast differentiation and LPS-induced proinflammatory cytokine (IL-1β, IL-6, TNF-a) expression via suppressing the NF-κB signal pathway. These results suggest that PFD can suppress periodontitis progression by inhibiting osteoclastogenesis and inflammatory cytokine production via inhibiting the NF-κB signal pathway, and it may be a promising candidate for controlling periodontitis.

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

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

Sunitinib displays pulmonary fibrosis in experimental rats: Role of IL-17A dependent pathway

Sunitinib (SUN) is an FDA approved first line drug for management of metastatic renal cancers and advanced cancerous states of gastrointestinal tract, however, side effects including fibrosis has been reported. Secukinumab (Secu) is an immunoglobulin G1 monoclonal antibody that exhibits anti-inflammatory activity by inhibiting several cellular signaling molecules. This study aimed to examine pulmonary protective potential of Secu in SUN-induced pulmonary fibrosis mediated through inhibition of inflammation via targeting IL-17A associated signaling pathway and using pirfenidone (PFD), an antifibrotic drug approved in 2014 for treatment of pulmonary fibrosis with IL-17A as one of its targets, as a reference drug. Wistar rats (160-200 g) were divided randomly into 4 groups (n = 6); Group 1 served as normal control; Group 2 served as disease control where it was exposed to SUN (25 mg/kg; 3 times weekly orally for 28 days); Group 3 was administered SUN and Secu (3 mg/kg subcutaneous at 0,14 and 28 days) and Group 4 was administered SUN and PFD (100 mg/kg/day orally for 28 days). Pro-inflammatory cytokines IL-1β, IL-6 and TNF-α were measured in addition to components of IL-17A signaling pathway (TGF-β, collagen, hydroxyproline). Results revealed that IL-17A-associated signaling pathway was activated in fibrotic lung tissue induced by SUN. Relative to normal control, SUN administration significantly elevated lung organ coefficient, IL-1β, IL-6, TNF-α, IL-17A, TGF-β, hydroxyproline and collagen expression. Secu or PFD treatment restored the altered levels to nearly normal values. Our study indicates that IL-17A participates in the development and progression of pulmonary fibrosis in a TGF-β dependent manner. Hence, components of IL-17A signaling pathway represent potential therapeutic targets for protection and treatment of fibro-proliferative lung disease.

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.

Modeling the Effects of Cypermethrin Toxicity on Ovalbumin-Induced Allergic Pneumonitis Rats: Macrophage Phenotype Differentiation and p38/STAT6 Signaling Are Candidate Targets of Pirfenidone Treatment

Although the classic form of asthma is characterized by chronic pneumonitis with eosinophil infiltration and steroid responsivity, asthma has multifactorial pathogenesis and various clinical phenotypes. Previous studies strongly suggested that chemical exposure could influence the severity and course of asthma and reduce its steroid responsiveness. Cypermethrin (CYP), a common pesticide used in agriculture, was investigated for the possible aggravation of the ovalbumin (OVA)-induced allergic pneumonitis and the possible induction of steroid resistance in rats. Additionally, it was investigated whether pirfenidone (PFD) could substitute dexamethasone, as an alternative treatment option, for the induced steroid resistance. Fifty-six male Wistar albino rats were randomly divided into seven groups: control, PFD alone, allergic pneumonitis, CYP alone, allergic pneumonitis/CYP-exposed, allergic pneumonitis/CYP/dexamethasone (Dex), and allergic pneumonitis/CYP/PFD-treated groups. Allergic pneumonitis was induced by three intraperitoneal OVA injections administered once a week, followed by an intranasal OVA instillation challenge. CYP (25 mg/kg/d), Dex (1 mg/kg/d), and PFD (100 mg/kg/d) were administered orally from day 15 to the end of the experiment. Bronchoalveolar lavage fluid (BALF) was analyzed for cytokine levels. Hematoxylin and eosin (H&E) and periodic acid Schiff (PAS)-stained lung sections were prepared. Immunohistochemical identification of p38 MAPK and lung macrophages was performed. The inflammatory/oxidative status of the lung and PCR-quantification of the STAT6, p38 MAPK, MUC5AC, and IL-13 genes were carried out. The allergic pneumonitis-only group showed eosinophil-mediated inflammation (p < 0.05). Further CYP exposure aggravated lung inflammation and showed steroid-resistant changes, p38 activation, neutrophil-mediated, M1 macrophage-related inflammation (p < 0.05). All changes were reversed (p < 0.05) by PFD, meanwhile not by dexamethasone treatment. Pirfenidone could replace dexamethasone treatment in the current rat model of CYP-induced severe steroid-resistant asthma via inhibiting the M1 macrophage differentiation through modulation of the STAT6/p38 MAPK pathway.

Cyclophilin A accelerates SiO2-induced macrophage foaming

Silicosis is a common occupational disease characterized by lung inflammation, fibrosis and pulmonary dysfunction caused by long-term inhalation of free SiO₂. Cell foaming and the change of CyPA have been observed in SiO₂-induced macrophages, but the specific mechanism of CyPA in SiO₂-induced foam cells remains poorly understood. The purpose of this study is to explore the mechanism of CyPA in SiO₂-induced macrophage foaming and its effect on silicosis. We found that overexpression of CyPA promoted the macrophage foaming and the expression of COL I and α-SMA, while silencing CyPA inhibites the macrophage foaming and the expression of COL I and α-SMA. After blocking the expression of CD36 on the basis of overexpression CyPA, we found it inhibites the macrophage foaming. In conclusion, CyPA can affect the foaming of macrophages and may participate in silicosis fibrosis.

FcεRI deficiency alleviates silica-induced pulmonary inflammation and fibrosis

Silicosis is one of the most important occupational diseases worldwide, caused by inhalation of silica particles or free crystalline silicon dioxide. As a disease with high mortality, it has no effective treatment and new therapeutic targets are urgently needed. Recent studies have identified FCER1A, encoding α-subunit of the immunoglobulin E (IgE) receptor FcεRI, as a candidate gene involved in the biological pathways leading to respiratory symptoms. FcεRI is known to be important in allergic asthma, but its role in silicosis remains unclear. In this study, serum IgE concentrations and FcεRI expression were assessed in pneumoconiosis patients and silica-exposed mice. The role of FcεRI was explored in a silica-induced mouse model using wild-type and FcεRI-deficient mice. The results showed that serum IgE concentrations were significantly elevated in both pneumoconiosis patients and mice exposed to silica compared with controls. The mRNA and protein expression of FcεRI were also significantly increased in the lung tissue of patients and silica-exposed mice. FcεRI deficiency significantly attenuated the changes in lung function caused by silica exposure. Silica-induced elevations of IL-1β, IL-6, and TNF-α were significantly attenuated in the lung tissue and bronchoalveolar lavage fluid (BALF) of FcεRI-deficient mice compared with wild-type controls. Additionally, FcεRI-deficient mice showed a significantly lower score of pulmonary fibrosis than wild-type mice following exposure to silica, with significantly lower hydroxyproline content and expression of fibrotic genes Col1a1 and Fn1. Immunofluorescent staining suggested FcεRI mainly on mast cells. Mast cell degranulation took place after silica exposure, as shown by increased serum histamine levels and β-hexosaminidase activity, which were significantly reduced in FcεRI-deficient mice compared with wild-type controls. Together, these data showed that FcεRI deficiency had a significant protective effect against silica-induced pulmonary inflammation and fibrosis. Our findings provide new insights into the pathophysiological mechanisms of silica-induced pulmonary fibrosis and a potential target for the treatment of silicosis.

Pirfenidone ameliorates pulmonary inflammation and fibrosis in a rat silicosis model by inhibiting macrophage polarization and JAK2/STAT3 signaling pathways

Macrophages play an important role in causing silicosis eventually becoming an irreversible fibrotic disease, and there are no specific drugs for silicosis in the clinic so far. Pirfenidone has consistently been shown to have anti-inflammatory and anti-fibrotic effects, but the specific mechanism by which it ameliorates fibrosis in silicosis is unclear. A rat silicosis model was established in this study, and lung tissues and serum were collected by batch execution at 14, 28, and 56 days. Also, the effects of Pirfenidone on macrophage polarization and pulmonary fibrosis were evaluated in silicosis with early intervention and late treatment by histological examination, Enzyme-linked immunosorbent assay, Hydroxyproline assay, Western blot and Quantitative reverse transcription polymerase chain reaction. The results showed that Pirfenidone significantly reduced pulmonary fibrosis in rats with silicosis, and both early intervention and late treatment effectively inhibited the expression of α-SMA, Col-I, Vimentin, Hydroxyproline, IL-1β, IL-18, and the M2 macrophage marker CD206 and Arg-1, while only early intervention effectively inhibited E-cad, TGF-β1, TNF-α, and the M1 macrophage marker iNOS, CD86. Furthermore, Pirfenidone dramatically reduced the mRNA expression of the JAK2/STAT3. These findings imply that Pirfenidone may reduce pulmonary fibrosis in silicosis rats by inhibiting macrophage polarization via the JAK2/STAT3 signaling pathway.

Inflammation and fibrosis in the coal dust-exposed lung described by confocal Raman spectroscopy

Background

Coal workers' pneumoconiosis (CWP) is an occupational disease that severely damages the life and health of miners. However, little is known about the molecular and cellular mechanisms changes associated with lung inflammation and fibrosis induced by coal dust. As a non-destructive technique for measuring biological tissue, confocal Raman spectroscopy provides accurate molecular fingerprints of label-free tissues and cells. Here, the progression of lung inflammation and fibrosis in a murine model of CWP was evaluated using confocal Raman spectroscopy.

Methods

A mouse model of CWP was constructed and biochemical analysis in lungs exposed to coal dust after 1 month (CWP-1M) and 3 months (CWP-3M) vs control tissues (NS) were used by confocal Raman spectroscopy. H&E, immunohistochemical and collagen staining were used to evaluate the histopathology alterations in the lung tissues.

Results

The CWP murine model was successfully constructed, and the mouse lung tissues showed progression of inflammation and fibrosis, accompanied by changes in NF-κB, p53, Bax, and Ki67. Meanwhile, significant differences in Raman bands were observed among the different groups, particularly changes at 1,248, 1,448, 1,572, and 746 cm^-1. These changes were consistent with collagen, Ki67, and Bax levels in the CWP and NS groups.

Conclusion

Confocal Raman spectroscopy represented a novel approach to the identification of the biochemical changes in CWP lungs and provides potential biomarkers of inflammation and fibrosis.

Minute Cellular Nodules as Early Lesions in Rats with Silica Exposure via Inhalation

Mechanisms of silicosis have yet to be clarified, and pathological conditions are inaccurately described in some experimental studies on silicosis. This study was aimed at describing initial lesions in silicosis, as observed in rats with silica exposure via inhalation, and major histopathologic alterations. Male Wistar rats were exposed to silica for 24 weeks. Hematoxylin and eosin staining indicated the presence of “cellular nodule+ macrophage alveolitis” in rats exposed to silica from the 2–16 weeks time points and “fibrotic cellular + cellular nodule” in rats exposed to silica via inhalation for 24 weeks. By immunohistochemistry, the following were noted: a continual increase in the positive expression of CD68 in macrophages in the lungs of rats exposed to silica; hyperplasia in alveolar type II cells (AT2); loss of original phenotypes in fibrotic cellular nodules, macrophages, and AT2 cells; loss of endothelial cells in silicotic nodules; and positive expression of α-smooth muscle actin in macrophages. Typical pathological changes in silicosis were also summarized. Among these changes were macrophage alveolitis, cellular nodules, and fibrotic cellular nodules, including an increase in minute cellular nodules in the early stages and the formation of fibrotic cellular nodules in the late stages.

Early Identification, Accurate Diagnosis, and Treatment of Silicosis

Silicosis is a global problem, and it has brought about great burdens to society and patients' families. The etiology of silicosis is clear, preventable, and controllable, but the onset is hidden and the duration is long. Thus, it is difficult to diagnose it early and treat it effectively, leaving workers unaware of the consequences of dust exposure. As such, a lack of details in the work history and a slow progression of lung disease contribute to the deterioration of patients until silicosis has advanced to fibrosis. These issues are the key factors impeding the diagnosis and the treatment of silicosis. This article reviews the literature on the early identification, diagnosis, and treatment of silicosis as well as analyzes the difficulties in the diagnosis and the treatment of silicosis and discusses its direction of future development.

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.