二氧化硅纳米颗粒(SiNP)暴露诱导严重的肺部炎症和纤维化,但其发病机制尚不清楚,目前缺乏有效的治疗方法。探讨SiNPs诱导肺纤维化的机制,我们构建了体内二氧化硅暴露动物模型和体外二氧化硅诱导的巨噬细胞焦亡和成纤维细胞转分化模型。我们发现,SiNP暴露引起与焦亡相关的肺蛋白上调,包括NLRP3,ASC,IL-1β,和GSDMD,而免疫荧光染色将NLRP3和GSDMD与巨噬细胞特异性生物标志物F4/80共定位在暴露于二氧化硅的肺组织中。然而,研究发现,NLRP3抑制剂MCC950和经典抗纤维化药物吡非尼酮(PFD)能够缓解二氧化硅诱导的肺胶原沉积.在体外研究中,我们将成纤维细胞暴露于二氧化硅诱导的变性巨噬细胞的条件培养基中,发现α-SMA的表达增强,提示成纤维细胞向肌成纤维细胞转分化增加。根据体内研究,MCC950和PFD的联合治疗被证明可以抑制α-SMA的表达并减弱成纤维细胞转分化。机械上,我们对不同处理的成纤维细胞进行高通量RNA测序,发现松弛素和破骨细胞分化通路的激活信号,其中检查了这两种途径中失调基因的表达,发现在体外和体内均发生了一致的变化。总的来说,我们的研究表明,SiNP暴露诱导巨噬细胞焦亡,随后导致成纤维细胞转分化为肌成纤维细胞,其中松弛素和破骨细胞分化信号通路起关键作用。这些发现可能为开发肺纤维化的新疗法提供有价值的参考。
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.