AAV9-HGF cooperating with TGF-beta/Smad inhibitor attenuates silicosis fibrosis via inhibiting ferroptosis.

Silicosis is a devastating interstitial lung disease characterized by silicon nodules and diffuse pulmonary fibrosis. To date, inefficient therapy is still a challenge of this disease due to its complicated pathogenesis. Hepatocyte growth factor (HGF) which is highly expressed in hepatocyte with anti-fibrotic and anti-apoptotic function was downregulated in silicosis. In addition, the upregulation of transforming growth factor-beta (TGF-ß), another pathological molecular was observed to aggravate the severity and accelerate the progression of silicosis. Here AAV expressed HGF with targeting pulmonary capillaries and SB431542, the inhibitor of TGF-ß signal pathway, were simultaneously adopted to synergistically reduce silicosis fibrosis. In vivo result demonstrated that the cooperation of HGF with SB431542 showed strong anti-fibrosis effects on the silicosis mice via tracheal administration of silica, compared to the separate treatment. The high efficacy was mainly achieved by remarkably by reducing ferroptosis of lung tissue. In our point, the combination of AAV9-HGF with SB431542 provide an alternative to relieve silicosis fibrosis from the perspective of targeting pulmonary capillaries.

SiO2-induced ferroptosis in macrophages promotes the development of pulmonary fibrosis in silicosis models.

Silicosis is a devastating disease that, without effective treatment, endangers the health of miners. Therefore, studies exploring the pathogenesis of SiO2-induced pulmonary fibrosis are necessary to develop treatments for silicosis. Although macrophages are known to play a pivotal role in SiO2-induced pulmonary fibrosis, the underlying mechanism remains unknown. Here, we explored whether ferroptosis was involved in SiO2-induced pulmonary fibrosis. To this end, C57BL/6 mice and mouse macrophage (RAW264.7) cells and mouse lung fibroblast (MLF) cells were subjected to iron content, cell viability, enzyme-linked immunosorbent assay, immunofluorescence staining, histological, western blotting, quantitative reverse transcription-PCR, reactive oxygen species, and lipid peroxidation analysis. In vivo, SiO2 was found to damage the lung alveolar structure, cause infiltration of inflammatory cells, and facilitate fibrosis. Additionally, it increased the iron concentration and lipid peroxidation as well as altered the expression of ferroptosis-related genes and the mitochondrial morphology in macrophages. In vitro, ferroptosis occurred in SiO2-treated RAW264.7 cells, which showed iron overload, lipid peroxidation, and gene alterations. Furthermore, ferrostatin-1 (Fer-1) attenuated ferroptosis in SiO2-treated RAW264.7 cells by inhibiting lipid peroxidation and cell death and regulating ferroptosis-related genes expression, in addition to attenuating the secretion of pro-fibrotic cytokines and fibrosis. Collectively, SiO2 induces ferroptosis in macrophages, which leads to the secretion of pro-fibrotic cytokines and fibrosis.