二氧化硅通过Raf/ERK-SP1信号轴调控巨噬细胞CCL22分泌及其对肺上皮细胞纤维化的影响OA

[Background]Silicosis is a fatal form of pulmonary fibrosis caused by the inhalation of silica dust.Although the underlying pathogenesis remains unclear,and the macrophage-mediated immune response plays a central role in its development. [Objective]To investigate the expression,functional role,and upstream regulatory mechanism of C-C motif chemokine ligand 22(CCL22)in silica-induced pulmonary fibrosis. [Methods]Through bioinformatics analysis,we identified CCL22 as a potential key factor in pulmonary fibrosis.We established in vitro models by stimulating human monocytic leukemia cells(THP-1)and peripheral blood mononuclear cell-derived macrophages(PBMC-m)with crystalline silica(CS).The regulation of CCL22 expression by CS was validated using quantitative real-time polymerase chain reaction(qRT-PCR)and enzyme-linked immunosorbent assay(ELISA).Subsequently,a conditioned co-culture system comprising macrophages and lung epithelial cells(BEAS-2B)was developed to evaluate the effects of CCL22 on lung epithelial cell function.Furthermore,the molecular mechanisms underlying CS-induced CCL22 secretion by macrophages were investigated using bioinformatics analysis,Western blot,specific inhibitors,qRT-PCR,and ELISA. [Results]Bioinformatics analysis identified CCL22 as a key upregulated molecule in pulmonary fibrosis.In vitro experiments confirmed that CS treatment significantly enhanced CCL22 mRNA transcription and protein secretion in THP-1 and PBMC-m cells(P<0.0001).In the co-culture system,supernatant from CS-stimulated macrophages with stable CCL22 knockdown significantly inhibited the scratch-healing ability and fibrotic process of BEAS-2B cells,and reversed the epithelial-mesenchymal transition(EMT)phenotype compared to the control group.Mechanism studies found that,compared to other transcription factors such as signal transducer and activator of transcription 3(STAT3)and nuclear factor-κB(NF-κB),the inhibition of of specific protein 1(SP1)most significantly attenuated the CS-induced upregulation of CCL22.Furthermore,pathway inhibition experiments demonstrated that inhibiting extracellular signal-regulated kinase(ERK)reduced both CCL22 expression and p-SP1.Conversely,SP1 intervention did not affect ERK activation. [Conclusion]CS promotes CCL22 secretion by macrophages through the Raf/ERK-Sp1 signaling pathway,thereby driving fibrotic changes in pulmonary epithelial cells.