Mechanism of action of mitochondrial DNA in alveolar epithelial type Ⅱ cells in silicotic fibrosis
- VernacularTitle:Ⅱ型肺泡上皮细胞线粒体DNA在矽肺纤维化中的作用机制
- Author:
Yu-fan QIN
1
;
Shang-cheng XU
1
Author Information
- Publication Type:Journal Article
- Keywords: silicosis; alveolar epithelial type Ⅱ cells; mitochondrial DNA; pulmonary fibrosis
- From: Journal of Regional Anatomy and Operative Surgery 2025;34(8):657-662
- CountryChina
- Language:Chinese
- Abstract: Objective To explore the mechanism of action of mitochondrial DNA(mtDNA)of alveolar epithelial type Ⅱ cells(AECⅡ)in silicotic fibrosis.Methods This study was divided into the animal experiment and cell experiment.Animal experiment:twenty-eight C57BL/6 mice were randomly divided into the saline group(n=14)and the silicosis model group(n=14),which were given 50 μL of sterile saline and 50 μL of 50 mg/mL of SiO2 suspension by tracheal perfusion respectively.HE staining and Masson staining were performed to observe the histopathological changes of mouse lung tissues after sampling with the exposure of 28 days and 56 days,and Western blot was used to detect the expression levels of functional proteins of pulmonary surfactant protein-D(SP-D),and Krebs von den Lungen-6(KL-6),and fibrotic protein of transforming growth factor-β1(TGF-β1)in mouse lung tissues.Cell experiment:AECⅡ cell line of A549 was exposed to different concentrations of SiO2 suspension.CCK-8 was used to detect cell viability,DAPI staining was used to observe cell apoptosis,Western blot was used to detect related protein expression,JC-1 was used to detect the changes of mitochondrial membrane potential,and RT-qPCR was used to detect mtDNA levels in whole cells,mitochondria,cytoplasm and supernatant.The expression levels of related proteins in AECⅡ were detected by Western blot after cleared mtDNA by DnaseⅠ.Results Histopathological examination of lung tissues showed that SiO2 exposure led to damage in mice lung tissues,with infiltration of inflammatory cell,silica nodules,and a significant increase of collagen fibers.After SiO2 exposure,the protein expressions of SP-D,KL-6 and TGF-β1 in lung tissues were up-regulated(P<0.05).DAPI staining and CCK-8 results showed a reduced activity and impaired apoptosis of AECⅡ after treated with 400 and 800 μg/mL SiO2.JC-1 assay results demonstrated that exposure to 800 μg/mL SiO2 caused a decrease of mitochondrial membrane potential in AECⅡ(P<0.05).RT-qPCR results showed that 800 μg/mL SiO2 exposure led to increased mtDNA levels in the cytoplasm and supernatant of AECⅡ(P<0.05).Western blot results showed that 800 μg/mL SiO2 exposure caused an increase in the levels of SP-D,KL-6,and TGF-β1 proteins,while which were ameliorated by Dnase Ⅰ treatment.Conclusion SiO2 exposure results in the escape and release of AECⅡ mtDNA and dysfunction of AECⅡ,thereby leading to the development of pulmonary fibrosis.
