The therapeutic effect of exosomal lncRNA MSTRG.91634.7 on mitochondrial dysfunction during SiO2-induced lung fibrosis

Elevating VAPB-PTPIP51 integration repairs damaged mitochondria-associated endoplasmic reticulum membranes and inhibits lung fibroblasts activation

Long-term silica exposure to silica dust leads to irreversible pulmonary fibrosis, during which lung fibroblast activation plays an essential role. Mitochondria-associated endoplasmic reticulum membranes (MAMs) is a structural interface for communication between the outer mitochondrial membrane and the endoplasmic reticulum. VAPB-PTPIP51 is a key complex on MAMs. However, the role of VAPB-PTPIP51-linked MAMs in lung fibroblast activation remains under investigation. In this study, we observed mitochondrial damage and endoplasmic reticulum stress in a SiO2-induced lung fibrosis model using C57BL/6J mice. In the model of TGF-β1-induced mouse lung fibroblast (MLG) activation, interventions with Dioscin and TUDCA reduced mitochondrial damage and alleviated endoplasmic reticulum stress by repairing damaged MAMs. Additionally, TUDCA may restore the MAMs structure by enhancing the interaction between VAPB and PTPIP51. Our findings indicate that MAMs may play a crucial role in linking mitochondrial damage and endoplasmic reticulum stress, suggesting their potential involvement in fibroblast activation.

lncRNA Profiling of Exosomes and Its Communication Role in Regulating Silica-Stimulated Macrophage Apoptosis and Fibroblast Activation

Long-term silica particle exposure leads to interstitial pulmonary inflammation and fibrosis, called silicosis. Silica-activated macrophages secrete a wide range of cytokines resulting in persistent inflammation. In addition, silica-stimulated activation of fibroblast is another checkpoint in the progression of silicosis. The pathogenesis after silica exposure is complex, involving intercellular communication and intracellular signaling pathway transduction, which was ignored previously. Exosomes are noteworthy because of their crucial role in intercellular communication by delivering bioactive substances, such as lncRNA. However, the expression profile of exosomal lncRNA in silicosis has not been reported yet. In this study, exosomes were isolated from the peripheral serum of silicosis patients or healthy donors. The exosomal lncRNAs were profiled using high-throughput sequencing technology. Target genes were predicted, and functional annotation was performed using differentially expressed lncRNAs. Eight aberrant expressed exosomal lncRNAs were considered to play a key role in the process of silicosis according to the OPLS-DA. Furthermore, the increased expression of lncRNA MSTRG.43085.16 was testified in vitro. Its target gene PARP1 was critical in regulating apoptosis based on bioinformatics analysis. In addition, the effects of exosomes on macrophage apoptosis and fibroblast activation were checked based on a co-cultured system. Our findings suggested that upregulation of lncRNA MSTRG.43085.16 could regulate silica-induced macrophage apoptosis through elevating PARP1 expression, and promote fibroblast activation, implying that the exosomal lncRNA MSTRG.43085.16 might have potential as a biomarker for the early diagnosis of silicosis.