Silicosis, caused by inhalation of crystalline silica (SiO2), remains a serious and persistent public health concern. Puerarin (Pue), a bioactive isoflavone derived from Pueraria lobata, is known for its anti-inflammatory and antioxidant properties; however, its protective effects and underlying mechanisms in silicosis have not been fully elucidated. In this study, alveolar type II (AT2) cells and male C57BL/6 J mice were used to investigate the anti-aging and anti-fibrotic effects of Pue and Pue-enriched Pueraria lobata tea (Plt) in experimental silicosis. Transcriptomic and molecular analyses revealed that SiO2 exposure induced epithelial-mesenchymal transition (EMT) and cellular senescence in AT2 cells, accompanied by mitochondrial DNA (mtDNA) leakage into the cytoplasm and activation of the cGAS-STING signaling pathway. Pharmacological inhibition of mtDNA transcription and replication attenuated mtDNA leakage, thereby alleviating AT2 cell senescence and EMT. Notably, Pue significantly reduced senescence and EMT by suppressing mtDNA leakage in SiO2-exposed AT2 cells. Consistently, both Pue and Pue-enriched Plt ameliorated pulmonary aging and fibrosis in SiO2-inhaled C57BL/6 J mice. Collectively, these findings suggest that Pue and Plt alleviate SiO2-induced pulmonary fibrosis by mitigating mtDNA leakage-induced senescence and EMT, highlighting a potential preventive and interventional strategy based on natural bioactive compounds for SiO2-induced pulmonary fibrosis.

Osteopontin (SPP1) plays a critical role in the initiation and progression of silicosis, but whether macrophage-derived SPP1 regulates lipid metabolism during silicosis remains unclear. In this study, RNA sequencing of lung tissues from silicotic mice and silica-stimulated alveolar macrophages identified Spp1 as a differentially expressed gene, and pathway enrichment analysis revealed significant enrichment of lipid metabolism-related signaling pathways. Using in vivo and in vitro models of silicosis, we assessed changes in SPP1 expression and key fatty acid synthesis markers. Silica stimulation increased SPP1 expression, induced lipid droplet formation, and upregulated fatty acid synthesis-related proteins. Subsequent in vitro experiments, including Spp1 knockdown, overexpression, and recombinant protein treatment, demonstrated that Spp1 knockdown effectively suppressed silica-induced lipid droplet formation and fatty acid synthesis. Mechanistically, SPP1 activated the fatty acid synthesis pathway by binding to its receptor CD44, thereby promoting SREBP-1 processing and nuclear translocation. Notably, Cd44 silencing abrogated SPP1-induced lipid droplet formation, the upregulation of fatty acid synthesis enzymes, and the production of pro-inflammatory cytokines (TNF-α and IL-6). Moreover, macrophage-specific knockout of Spp1 significantly alleviated pulmonary fibrosis, improved lung function, and inhibited the fatty acid synthesis pathway in vivo. Collectively, this study elucidates a novel mechanism by which SPP1 regulates macrophage fatty acid metabolism through the CD44/SREBP-1 axis, providing a mechanistic basis for targeting SPP1 in silicosis treatment.

Pulmonary fibrosis, particularly idiopathic pulmonary fibrosis (IPF), is a chronic and progressive interstitial lung disease characterized by alveolar epithelial injury, fibroblast activation, and excessive extracellular matrix deposition, which collectively lead to respiratory failure. Despite the availability of antifibrotic agents, disease-modifying therapies remain limited. Emerging evidence has identified dysregulated sphingolipid metabolism, especially ceramide accumulation, as a key driver of fibrotic pathogenesis. Ceramide is a central bioactive lipid in the sphingolipid pathway that regulates multiple cellular processes, including apoptosis, inflammation, endothelial barrier dysfunction, and fibroblast activation, all of which contribute to pulmonary fibrosis. This review is a narrative review that systematically summarizes the biosynthetic and metabolic pathways of ceramide, with an emphasis on chain length-specific functions and the ceramide to S1P rheostat. We further discuss the mechanistic roles of ceramide in alveolar epithelial cell apoptosis, inflammatory responses, and vascular barrier disruption in fibrotic lung disease. Finally, we highlight emerging therapeutic strategies that target ceramide metabolism, including inhibitors of acid sphingomyelinase (ASMase) and serine palmitoyltransferase (SPT), and propose future directions for clinical translation.

Silicosis is an irreversible occupational disease, but its pathogenesis remains incompletely understood. Although secreted phosphoprotein 1 (SPP1) and lipid dysregulation have been implicated in silicosis, their functional interplay is unclear. In this study, we demonstrated that macrophage-specific Spp1 knockout in mice attenuated silica-induced pulmonary fibrosis, improved lung function, and suppressed aberrant lipid metabolism both in vivo and in vitro. Specifically, silica-induced intracellular SPP1 (iSPP1) regulated the ceramide synthesis pathway by promoting the ubiquitination of fibronectin type III domain-containing 5 (FNDC5). This action attenuated FNDC5-mediated ubiquitination and subsequent downregulation of Δ4-dihydroceramide desaturase 1 (DEGS1), a key enzyme in de novo ceramide synthesis within the endoplasmic reticulum. Overall, we identified the interaction of SPP1, FNDC5, and DEGS1, providing a mechanistic basis and a potential therapeutic strategy for targeting lipid dysregulation in silicosis.

Silicosis, one of the most common and severe forms of pneumoconiosis, remains a major occupational health concern worldwide. Given the lack of effective therapies, understanding the underlying molecular mechanisms is urgently needed. Here, we report that ALKB homolog 1 (ALKBH1), an N6-methyladenosine (m6A) demethylase, is upregulated in silica-induced pulmonary fibrosis and plays a pro-fibrotic role. The antifibrotic peptide Ac-SDKP inhibited Alkbh1 expression and alleviated pulmonary fibrosis. Mechanistically, ALKBH1 suppressed the biosynthesis of miR-129-5p by removing m6A modification from pri-miR-129-5p, thereby reducing DGCR8-mediated processing and leading to decreased mature miR-129-5p levels. Ac-SDKP reversed this process, restoring miR-129-5p expression. Functionally, overexpression of miR-129-5p attenuated silica-induced pulmonary fibrosis by suppressing macrophage activation. Collectively, these findings identify the Ac-SDKP-ALKBH1-miR-129-5p axis as a critical regulatory mechanism, with ALKBH1-mediated m6A demethylation of pri-miR-129-5p representing a key node and a promising therapeutic target for silicosis.

Late-onset silicosis is characterized by the progression of pulmonary fibrosis long after cessation of silica exposure, yet its underlying mechanisms remain poorly understood. This study aimed to determine whether a brief silica exposure could initiate a sustaining fibrotic process and to characterize the associated pathological and molecular alterations. A rat model of silicosis was established by short-term silica inhalation for two weeks, followed by a recovery period of up to 46 weeks. Histopathological and micro-CT analyses demonstrated progressive fibrotic development even after exposure cessation. Notably, fibrotic pulmonary dust foci (fPDFs) emerged as a predominant lesion, characterized by alveolar remodeling and diffuse collagen deposition distinct from classical silicotic nodules. These lesions were associated with alveolar type II (AT2) cell dysfunction, evidenced by aberrant differentiation, loss of homeostatic markers such as ATP-binding cassette subfamily A member 3 (ABCA3), lysophosphatidylcholine acyltransferase 1 (LPCAT1), and fatty acid synthase (FAS), and gain of transitional markers keratin 8 (KRT8) and stratifin (SFN). Integrated proteomic and lipidomic analyses revealed profound metabolic reprogramming, with significant dysregulation of lipid metabolism pathways. Key enzymes involved in lipid synthesis and remodeling were identified in AT2 cells and downregulated in fPDF regions. Our findings establish that short-term silica exposure initiates a sustaining fibrotic cascade, highlight fPDFs as a critical pathological entity, and suggest that AT2 cell dysfunction and metabolic reprogramming are closely associated with the progression of silicosis, highlighting them as potential key correlates of the sustaining fibrotic cascade. These insights provide a novel framework for understanding disease progression and identifying therapeutic targets.

Background Idiopathic pulmonary fibrosis (IPF) is an irreversible, fatal lung disease. Methylophiopogonanone A (MOA), derived from the Chinese medicinal herb Ophiopogon japonicus, has been shown to exhibit anti-inflammatory and antioxidant properties. However, the effects of MOA on pulmonary fibrosis remain unclear. This study aims to evaluate the antifibrotic effect of MOA.Methods The antifibrotic efficacy of MOA was evaluated in a bleomycin (BLM)-induced pulmonary fibrosis mouse model, using pirfenidone (PFD) as a positive control. Assessments included histopathology, micro-computed tomography (micro-CT), lung function tests, and serum biochemistry. In vitro, RAW 264.7 murine monocyte/macrophage cells were stimulated with BLM, lipopolysaccharide (LPS), interleukin 4 (IL-4), recombinant secreted phosphoprotein 1 (SPP1) protein, or Spp1 overexpression (OE-spp1) and treated with MOA, PFD, spp1 shRNA (sh-spp1), or the PI3K inhibitor LY294002. Transcriptomics, molecular docking, microscale thermophoresis (MST), immunohistochemistry, immunofluorescence, and Western blot were used for mechanistic exploration.Results MOA administration significantly attenuated BLM-induced lung fibrosis and collagen deposition, improved lung function, and did not induce hepatorenal toxicity. Integrated transcriptomic and bioinformatics analyses identified SPP1 as a key potential target. Molecular docking simulation and MST assays further confirmed a favorable binding affinity between SPP1 and MOA. MOA potently inhibited both M1 and M2 macrophage polarization in vivo and in vitro. Mechanistically, MOA attenuated BLM-induced pulmonary fibrosis by suppressing SPP1-mediated macrophage polarization via inhibition of the PI3K/Akt pathway.Conclusions This study identifies that MOA is a promising natural compound that alleviates pulmonary fibrosis by inhibiting SPP1-mediated macrophage polarization via the PI3K/Akt pathway.

Silicosis remains a critical occupational health concern worldwide, lacking effective treatments due to unclear mechanisms. In this study, we investigated the citrullinated proteomic profile and its effects in mice exposed to silica. Our findings demonstrated elevated levels of citrullinated peptides and citrullinated vimentin (Cit-Vim) in silicotic mice and silica-treated macrophages, regulated by peptidylarginine deiminase (PADI2). Unlike vimentin, Cit-Vim amplified the production of tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6), and IL-1β in silica-treated macrophages through interaction with Toll-like receptor 4 (TLR4) signaling. RNA sequencing revealed that early growth response protein 1 (EGR1) is a target of PADI2, with Cit-Vim inducing lung inflammation via EGR1 signaling. Pharmacological inhibition or genetic knockout of Padi2 attenuated silica-induced lung inflammation and fibrosis. These findings suggest that targeting PADI2 may represent a novel therapeutic strategy of silicosis.

The role and mechanism of protein tyrosine phosphatase non-receptor type 2 (PTPN2) in silicosis remain unclear. In this study, transcriptome sequencing, microcomputed tomography, histological examination, and western blot analysis were used to evaluate the effects of PTPN2 on the retinol metabolism signaling pathway, the transforming growth factor-beta 1 (TGF-β1) signaling pathway, cellular senescence, and pulmonary fibrosis in silicosis. The results demonstrated that overexpression of PTPN2 significantly reduced the degree of pulmonary fibrosis in silicosis model mice, whereas alveolar endothelial cell-specific knockout of PTPN2 exacerbated fibrosis. PTPN2 overexpression ameliorated fibrosis by regulating key enzymes in retinol metabolism, downregulating the TGF-β1 signaling pathway, and decreasing the expression of senescence-related signals. Both in vitro and in vivo results showed that PTPN2 overexpression upregulated the expression of retinol metabolism signaling pathway-related molecules (ALDH1A2, RDH10, and DHRS3), reversed the expression of TGF-β1 signaling pathway-related components (TGF-β1, TGF-βR1, and TGF-βR2) and the phosphorylation of Smad2/3, and downregulated the expression of senescence-associated factors (β-galactosidase, p-p53, p21, and p16). These findings suggest that PTPN2 may alleviate silicotic pulmonary fibrosis by inhibiting the senescence of type II alveolar epithelial cells via influencing retinol metabolism regulated by ALDH1A2.

BACKGROUND:It is well recognized that developing new animal models, refining the existing mouse models, and thoroughly characterizing their features are essential for gaining a deeper understanding of rosacea pathogenesis and for advancing therapeutic strategies in this direction. Accordingly, we aimed to characterize the pathological features of a long-term LL-37-induced mouse model of rosacea and to compare the disease manifestations and pathophysiological characteristics between short-term and long-term LL-37-induced models. A key focus was to investigate differential gene expression and the underlying mechanisms of immune system dysregulation in these models. METHODS:We comparatively assessed skin lesion manifestations, the extent of inflammatory infiltration, sebaceous gland alterations, fibrosis, and angiogenesis in both models. Assessments were performed using photographic documentation, hematoxylin-eosin (HE) staining, Van Gieson's (VG) staining, immunohistochemistry, and Western blotting. Furthermore, we employed RNA sequencing to analyze differential gene expression in mouse skin. The RNA sequencing data were validated using immunofluorescence staining and Western blotting, with a specific focus on gene variations and mechanisms related to immune system dysregulation. RESULTS:Mice subjected to long-term LL-37 induction developed rosacea-like pathological features, including angiogenesis, thickened skin tissue, and sebaceous gland hypertrophy. In the short-term LL-37-induced model, immune dysregulation primarily involved the innate immune response. However, long-term LL-37 induction resulted in significant activation of both innate and adaptive immune responses. CONCLUSION:The long-term LL-37-induced mouse model offers a valuable animal model for the detailed investigation of the pathological mechanisms driving moderate-to-severe rosacea with prolonged disease duration. Importantly, this model provides a significant experimental foundation for exploring the potential role of immune system dysregulation in rosacea pathogenesis.

Monocyte-derived macrophages (MoMacs) are the most important effector cells that cause pulmonary fibrosis. However, the characteristics of MoMac differentiation in silicosis and the mechanisms by which MoMacs affect the progression of pulmonary fibrosis remain unclear. Integration of single-cell and spatial transcriptomic analyses revealed that the silicosis niche was occupied by a subset of MoMacs, identified as Spp1hiMacs, which remain in an immature transitional state of differentiation during silicosis. This study investigated the mechanistic foundations of mitochondrial damage induced by the lipoprotein-associated phospholipase A2 (Lp-PLA2, encoded by Pla2g7)–acyl-CoA:lysocardiolipin acyltransferase-1 (ALCAT1)–cardiolipin (CL) signaling pathway, which interferes with Spp1hiMac differentiation. We demonstrated that in SiO2-induced MoMacs, Lp-PLA2 induces abnormal CL acylation through the activation of ALCAT1, resulting in impaired mitochondrial localization of PINK1 and LC3B and mitochondrial autophagy defects. Simultaneously, lysosomal dysfunction causes the release of the lysosomal protein cathepsin B into the cytoplasm, which involves M1 and M2 macrophage polarization and the activation of proinflammatory and profibrotic pathways. Furthermore, we assessed the efficacy of the Lp-PLA2 inhibitor darapladib in ameliorating silica-induced pulmonary fibrosis in a murine model. Our findings enhance our understanding of silicosis pathogenesis and offer promising opportunities for developing targeted therapies to mitigate fibrotic progression and maintain lung function in affected individuals.

BackgroundProtein tyrosine phosphatase non-receptor type II (PTPN2) is essential for the regulation of inflammation and immunity, but the specific mechanism of action of Ptpn2 in silicosis is unknown.ObjectiveTo investigate the regulatory role of overexpression of Ptpn2 in SiO2-mediated inflammatory response in alveolar type II epithelial cells based on transcriptome sequencing.MethodsThis study was an in vitro study. A negative control group (vector transferred) and an overexpression of Ptpn2 group of mouse lung epithelial cell line MLE-12 cells were firstly constructed. Transcriptome sequencing was performed to detect differentially expressed genes (DEGs), differentially expressed mRNAs, and differentially expressed ncRNAs in the two groups of MLE-12 cells, and then the DEGs were analyzed by the Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). Constructed MLE-12 cells and A549 cells were stimulated using SiO2 suspension, and divided into a negative control group (vector transferred), an overexpression of Ptpn2 group, a negative control + SiO2 group, and an overexpression of Ptpn2 + SiO2 group, respectively. Protein expressions of tumor necrosis factor-α (TNF-α) and interleukin (IL)-17A, IL-2, IL-1β were detected by Western blot. Positive TNF-α expression was detected by immunofluorescence staining. ResultsThe results of Western blot showed that the protein expression level of PTPN2 was up-regulated in the overexpressed Ptpn2 group compared with the negative control group (P < 0.05). The volcano plot and clustering heat map showed that there were 1122 DEGs, 3681 differentially expressed mRNAs, and 474 differentially expressed ncRNAs in the overexpressed Ptpn2 group compared with the negative control group. The results of GO enrichment showed that, in terms of the biological process, the DEGs were mainly related to the regulation of metal ion transport, extracellular matrix organization, and extracellular structural organization; in terms of cellular composition, the DEGs were mainly related to collagen-containing extracellular matrix, receptor complexes, and basement membranes; in terms of molecular function, the DEGs were mainly related to the extracellular matrix structural constituents, glycosaminoglycan binding, and semaphorin receptor binding. The results of KEGG enrichment showed that the DEGs were closely related to cytokin-cytokine receptor interaction, IL-17 signaling pathway, TNF signaling pathway, and chemokine signaling pathway. In MLE-12 and A549 cells, the results of Western blot showed that the protein expression levels of TNF-α , IL-17A, IL-2, and IL-1β were up-regulated in the negative control + SiO2 group compared with the negative control group (P < 0.05), and the protein expression levels of TNF-α, IL-17A, IL-2, and IL-1β were down-regulated in the overexpression of Ptpn2 + SiO2 group compared with the negative control + SiO2 group (P < 0.05). The immunofluorescence staining showed that the expression of TNF-α was increased in the negative control + SiO2 group compared with the negative control group, and decreased in the overexpression of Ptpn2 + SiO2 group compared with the negative control + SiO2 group. ConclusionOverexpression of Ptpn2 inhibits SiO2-mediated inflammatory response in MLE-12 cells and A549 cells.

BackgroundPneumoconiosis is the most serious occupational disease in China, among which silicosis accounts for more than 50%. microRNA (miRNA) plays an important role in the occurrence process of silicosis fibrosis, but the mechanism of it has not been fully clarified yet.ObjectiveTo explore the molecular mechanism by which miR-411-3p modulates the ubiquitination degradation of SMAD specific E3 ubiquitin protein ligase (SMURF) 2/Smad7, thereby suppressing epithelial-mesenchymal transition (EMT) in mouse alveolar type II epithelial cells and counteracting silica-induced pulmonary fibrosis.MethodsTwenty-four 8-week-old SPF male C57BL/6J mice were randomly divided into four groups: Control group, silica group, silica +miR-411-3p agomir-NC group, and silica +miR-411-3p agomir group, with 6 mice in each group. Silicosis model was prepared by a one-time bronchial infusion of silicon dioxide (SiO2) (200 mg·mL-1, 50 μL). In vitro MLE-12 cells were divided into (1) control group and SiO2 group, (2) SiO2+negative control siRNA (siRNA-NC) group and SiO2+Smurf2 gene silencing (si-Smurf2) group, (3) SiO2+solvent (DMSO) group and SiO2+protease inhibitor (MG132) group, (4) mutant sequence plasmid (Mut)+miR-411-3p mimic control (miR-NC) group, Mut+miR-411-3p mimic group, wild sequence plasmid (Wt)+miR-NC group, and Wt+miR-411-3p mimic group, (5) SiO2+miR-NC group and SiO2+miR-411-3p mimic group. The pathological morphology and collagen deposition of lung tissue were observed after staining. Detection of miR-411-3p and proteins was conducted by real-time fluorescent quantitative PCR and Western blot. The binding of SMURF2 to Smad7 protein and Smad7 to ubiquitin (Ub) were detected by co-immunoprecipitation (Co-IP) method. Dual-luciferase reporter gene assay was adopted to verify the regulatory effect of miR-411-3p on Smurf2.ResultsIn the SiO2-induced MLE-12 cells, compared to the control group, the SiO2-treated group showed significantly upregulated expressions of N-cadherin (N-Cad), collagen I (CoL I), SMURF2, transforming growth factor-β1 (TGF-β1), and phosphorylated Smad2/3 (p-Smad2/3). In contrast, the expressions of E-cadherin (E-Cad), Smad7, and miR-411-3p were significantly downregulated (P<0.05). The dual-luciferase reporter gene assay revealed a regulatory effect of miR-411-3p on Smurf2 (P<0.05). Meanwhile, in the MLE-12 cells induced by SiO2, the miR-411-3p mimic down-regulated the protein expressions of SMURF2, N-Cad, CoL I, TGF-β1, and p-Smad2/3, while up-regulated the protein expressions of E-Cad and Smad7 (P<0.05). The silenced Smurf2 gene inhibited the expressions of N-Cad, CoL I, and p-Smad2/3 proteins, while promoted the expressions of E-Cad and Smad7 proteins in the MLE-12 cells (P<0.05). The Co-IP results showed that the binding of SMURF2 to Smad7 was enhanced, and the ubiquitin binding ability of Smad7 was enhanced in the SiO2 group. In the lung tissue of mice, the results of pathological observation with hematoxylin-eosin (HE) and sirius red (VG) staining showed that compared with the agomir-NC, the lesion was relieved in the lung tissue of the miR-411-3p agomir group. Meanwhile, the expressions of SMURF2, N-Cad, CoL I, TGF-β1, and p-Smad2/3 were significantly down-regulated, while the expressions of E-Cad and Smad7 were significantly up-regulated (P<0.05).ConclusionMiR-411-3p alleviates the EMT of alveolar type II epithelial cells and antagonizes silicosis fibrosis progression in mice by inhibiting SMURF2-mediated ubiquitination and degradation of Smad7.

Silicosis,a major persistent occupational disease in China,is a progressive and irreversible pulmonary fibrosis disease with unclear pathogenesis.Cellular senescence,a state of stable cell cycle arrest that is recognized as a key underlying factor in age-related fibroproliferative disorders,plays an important role in chronic lung diseases,particularly pulmonary fibrosis.We previously reported that SiO2-stimulated mice and alveolar type II epithelial cells develop cellular senescence,which is involved in silicosis formation in alveolar type II epithelial cells[1].Cellular senescence may play an important role in silicosis development;however,the exact underlying mechanisms are not fully understood.

This study is concerned with the development of a long non-coding RNA (lncRNA) BCRT1 bio-platform based on tetrahydroxyborate-bismuth vandate ([B(OH)4]--BiVO4) for early diagnosis of cervical cancer (CC). A biosensor based on ([B(OH)4]--BiVO4 was constructed towards CC exosomal lncRNA biomarker. Formation of [B(OH)4]- ligand passivated BiVO4 helps to eliminate surface defects, reducing charge recombination. [B(OH)4]--BiVO4 serves as a base material with excellent photoelectric properties, showing a signal response up to 0.89 mA∙cm-2. This study focused on designing a capture probe for exosomal lncRNA BCRT1 in order to effectively detect early warning signs of the CC. The probe achieved a low detection limit of 5.53 fmol∙L-1 within a range of 0.01-10000 pmol∙L-1, demonstrating good stability, reproducibility and selectivity. This research offers a promising method for the early diagnosis of CC.

Silicosis, caused by the inhalation of silicon dioxide (SiO2), is one of the most pressing public health problems. Nevertheless, there is currently no effective treatment. This study employed male C57BL/6 J mice and mouse alveolar macrophage cell line MH-S to investigate the biological mechanism in the development of silicosis, with a view to exploring the potential applications of puerarin (Pue) in the improvement of pulmonary inflammation and fibrosis in SiO2-exposed mice. This study elucidated that SiO2 could induce expression of inflammatory factors, accompanied by autophagy flux block, lysosome alkalization and membrane permeability in MH-S cells. Pue pretreatment could effectively inhibit expression of inflammatory factors in SiO2-exposed MH-S cells via alleviating autophagolysosomal dysfunction, and suppress TGF-β-induced myofibroblast differentiation. In addition, Pue was also been demonstrated to mitigate autophagolysosomal dysfunction, pulmonary inflammation and fibrosis in SiO2-exposed C57BL/6 J mice. Furthermore, the ingestion of Pue-enriched pueraria lobata tea (Plt), a traditional Chinese tea substitute that possesses anti-inflammatory, antioxidant, and cardiovascular benefits, was determined to improve imbalance of lysosome homeostasis, pulmonary inflammation and fibrosis in SiO2-exposed mice. This study illustrates the anti-inflammatory and antifibrotic properties of Pue and Plt by alleviating autophagolysosomal dysfunction and, consequently, reducing pulmonary inflammation and fibrosis. These findings provide insights into the pathogenesis mechanism of silicosis and indicate potential avenues for application of Pue and Plt in the mitigation of silicosis.

Targeting macrophage SCTR mitigates integrated profibrotic, inflammatory, ER stress, and senescent pathways, preserving lung function and revealing a novel therapeutic strategy for silicosis.

BackgroundThe senescence of alveolar type II epithelial cells is an important driving factor for the progression of silicotic fibrosis, and the regulatory effects of oxamate on the senescence of alveolar type II epithelial cells is still unclear.ObjectiveTo explore whether lactate dehydrogenase inhibitor oxamate can alleviate silicotic fibrosis in mice by inhibiting senescence of alveolar type II epithelial cellsMethodsThis study was divided into two parts: in vivo experiments and in vitro experiments. In the first part, forty SPF C57BL/6J male mice were randomly divided into four groups with 10 in each group: control group, silicosis model group, low-dose oxamate treatment group, and high-dose oxamate treatment group. The silicotic mouse model was established by intratracheal instillation of 50 μL SiO2 suspension (100 mg·mL−1). The treatment models were prepared by intraperitoneal injection of 100 μL oxamate (225 mmol·L−1 and 1125 mmol·L−1). In the second part, induction of MLE-12 mouse alveolar type II epithelial cells was conducted with SiO2. The in vitro experimental groups were ① SiO2 induction groups: control group, 50 μg·mL−1 SiO2 group, 100 μg·mL−1 SiO2 group, and 200 μg·mL−1 SiO2 group, and ② oxamate treatment groups: control group, SiO2 group (100 μg·mL−1), low-dose oxamate (25 mmol·L−1) treatment group, and high-dose oxamate (50 mmol·L−1) treatment group. Pathological morphology of lung tissues was evaluated after hematoxylin-eosin (HE) staining; deposition of collagen in lung tissues was evaluated after sirius red staining; positive co-expression of prosurfactant protein C (Pro-SPC) and β-galactosidase was detected by immunofluorescence staining; positive expression of β-galactosidase in MLE-12 cells was detected by immunofluorescence staining. The protein expression levels of collagen type I (CoL I), fibronectin1 (FN1), hexokinase 2 (HK2), pyruvate kinase isozyme type M2 (PKM2), lactate dehydrogenase A (LDHA), p-ataxia telangiectasia and Rad3-related kinase (ATR), and cyclin-dependent kinase inhibitors p21, and p16 were detected by Western blotting.ResultsCompared with the control group, the protein expression levels of HK2, PKM2, LDHA, p-ATR, p21, and p16 were significantly upregulated in the silicosis model group and the SiO2-induced MLE-12 cells (P＜0.05). The in vivo studies showed that, compared with the control group, the silicon nodule area, the collagen deposition area, the proportion of β-galactosidase positive cells, and the protein expression levels of CoL I, FN1, LDHA, p-ATR, p21, and p16 were significantly upregulated in the silicosis model group (P＜0.05). Compared with the silicosis model group, the oxamate treatment groups showed significant downregulation of the silicon nodule area, the collagen deposition area, the proportion of β-galactosidase positive cells, and the the CoL I, FN1, LDHA, p-ATR, p21, and p16 protein expression levels, and the high-dose oxamate treatment group showed a higher efficacy on these indicators than the low-dose oxamate treatment group (P＜0.05). The in vitro studies showed that, compared with the control group, the proportion of β-galactosidase positive cells and the protein expression levels of p-ATR, p21, and p16 were significantly upregulated in the SiO2-induced group (P＜0.05). Compared with the SiO2 group, the proportion of β-galactosidase positive cells and the LDHA, p-ATR, p21 and p16 protein expression levels were significantly downregulated in the oxamate treatment groups, and the high-dose oxamate treatment group showed a higher efficacy on these indicators than the low-dose oxamate treatment group (P＜0.05).ConclusionLactate dehydrogenase inhibitor oxamate can alleviate silicotic fibrosis in mice by inhibiting the senescence of alveolar type II epithelial cells.