Integration of apaQTL and eQTL analysis reveals novel SNPs associated with occupational pulmonary fibrosis risk

Senescent endothelial cell-derived Galectin 3 promotes silicosis through endothelial-fibroblast and endothelial-macrophage crosstalk

Silicosis is an occupational and irreversible interstitial lung disease, which is caused by the inhalation of respirable crystalline silica. Recent studies suggested that the senescence of endothelial cells is implicated in the pathogenesis of lung diseases. However, the role of senescent endothelial cells in silicosis remains poorly understood. By establishing multiple endothelial cell senescence models, and a silica-induced pulmonary fibrosis mouse model, we found that silica-induced endothelial cell senescence was accompanied by the increased expression of Galectin 3 (Gal3, gene name LGALS3). Mechanistically, silica-induced senescent cells synthesized a substantial amount of Gal3, which was subsequently released into the cellular microenvironment. Then, Gal3 directly binds to TGFBR1 on the cell membrane of lung fibroblasts and TLR4 on the macrophages, respectively. This cell communication facilitates the progression of silicosis by promoting fibroblast-myofibroblast transition (FMT) and NLRP3 inflammasome activation. Furthermore, Gal3 is regulated by the transcriptional regulatory factor CEBPB (CCAAT/ enhancer-binding protein beta) in senescent endothelial cells. In vivo, the administration of Lgals3 siRNA-loaded liposomes significantly ameliorated silica-induced pulmonary fibrosis. Collectively, our study demonstrated the critical role of endothelial cell senescence through the secretion of Gal3, which contributes to pulmonary fibrosis by promoting endothelial-fibroblast and endothelial-macrophage crosstalk.

Puerarin alleviates silicon dioxide-induced pulmonary inflammation and fibrosis via improving Autophagolysosomal dysfunction in alveolar macrophages of murine mice

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.

LGALS3 regulates endothelial-to-mesenchymal transition via PI3K/AKT signaling pathway in silica-induced pulmonary fibrosis

Silicosis is a progressive and chronic occupational lung disease characterized by lung inflammation, silicotic nodule formation, and diffuse pulmonary fibrosis. Emerging evidence indicates that endothelial-mesenchymal transition (EndoMT) plays a crucial role in the development of silicosis. Herein, we conducted a SiO2-induced EndoMT model and established a mouse model with pulmonary fibrosis by silica. We identified that SiO2 effectively increased the expression of mesenchymal markers while decreasing the levels of endothelial markers in endothelial cells. It's further demonstrated that SiO2 induced the PI3K/Akt signaling pathway activation via LGALS3 synthesis. Next, interfering LGALS3 blocked the process of EndoMT by inhibiting the activity of PI3K/AKT signaling. In vivo, the administration of a specific PI3K inhibitor LY294002 significantly alleviated silica-induced pulmonary fibrosis. Collectively, these results identified that the LGALS3/PI3K/AKT pathway provided a rationale target for the clinical treatment and intervention of silicosis.

Multi-omics and multi-stages integration identified a novel variant associated with silicosis risk

Assessing the association between candidate single-nucleotide polymorphisms (SNPs) identified by multi-omics approaches and susceptibility to silicosis. RNA-seq analysis was performed to screen the differentially expressed mRNAs in the fibrotic lung tissues of mice exposed to silica particles. Following this, we integrated the SNPs located in the above human homologenes with the silicosis-related genome-wide association study (GWAS) data to select the candidate SNPs. Then, expression quantitative trait locus (eQTL)-SNPs were identified by the GTEx database. Next, we validated the associations between the functional eQTL-SNPs and silicosis susceptibility by additional case-control study. And the contribution of the identified SNP and its host gene in the fibrosis process was further validated by functional experiments. A total of 12 eQTL-SNPs were identified in the screening stage. The results of the validation stage suggested that the variant T allele of rs419540 located in IL12RB1 significantly increased the risk of developing silicosis [additive model: odds ratio (OR) = 1.78, 95% confidence interval (CI) 1.11-2.85, P = 0.017]. Furthermore, the combination of GWAS and the results of validation stage also indicated that the variant T allele of rs419540 in IL12RB1 was associated with increased silicosis risk (additive model: OR = 2.07, 95% CI 1.38-3.12, P < 0.001). Additionally, after knockdown or overexpression of IL12RB1, the levels of pro-inflammatory factors, such as IL-12, IFN-γ, and other pro-inflammatory factors, were correspondingly decreased or increased. The novel eQTL-SNP, rs419540, might increase the risk of silicosis by modulating the expression levels of IL12RB1.