背景:间质性肺病(ILD)是系统性硬化症(SSc)死亡的主要原因,一种以组织纤维化为特征的自身免疫性疾病。SSc相关ILD(SSc-ILD)更常见于30-55岁的女性,而特发性肺纤维化(IPF)在60-75岁的男性中更为普遍。SSc-ILD比IPF更早发生并且进展迅速。FCN1,FABP4和SPP1巨噬细胞参与肺纤维化的发病机理;SPP1巨噬细胞在SSc-ILD和IPF中均显示出上调的表达。为了使用单细胞分析确定SSc-ILD和IPF之间的差异,阐明其独特的病因,并提出预防和治疗的方向。
方法:我们对NCBI基因表达综合(GEO)数据库GSE159354和GSE212109进行了单细胞RNA测序,并分析了健康对照的肺组织样本,IPF,和SSc-ILD。主要测量是整合了批次校正的过滤基因和注释的细胞类型,用于区分SSc-ILD患者与健康对照。我们提出了一个SSc-ILD发病机制使用细胞-细胞相互作用推断,并使用SCENIC预测调控靶基因的转录因子。使用在线药物银行进行TF基因的药物靶标预测。
结果:一组巨噬细胞在氧化应激下激活MAPK信号通路。由于缺乏来自ANNEXIN的抑制反馈和自身免疫特征,与IPF相比,这导致肺纤维化的发病更早.在最初的肺损伤期间,成纤维细胞在SPP1肺泡巨噬细胞的影响下开始激活IL6通路,但IL6似乎与其他炎症和免疫细胞无关。这可以解释为什么托珠单抗(抗IL6受体抗体)仅保留早期SSc-ILD患者的肺功能。最后,我们确定BCLAF1和NFE2L2是巨噬细胞中MAPK激活的影响者。二甲双胍下调NFE2L2,可以作为一个重新利用的候选药物。
结论:SPP1肺泡巨噬细胞在IPF和SSc-ILD的促纤维化活性中起作用。然而,SSc-ILD受自身免疫和氧化应激的影响,导致巨噬细胞中MAPK的持续激活。这可能导致肺纤维化比IPF更早发作。这种差异可以作为早期预防和治疗的潜在研究方向。
BACKGROUND: Interstitial lung disease (ILD) is the primary cause of mortality in systemic sclerosis (SSc), an autoimmune disease characterized by tissue fibrosis. SSc-related ILD (SSc-ILD) occurs more frequently in females aged 30-55 years, whereas idiopathic pulmonary fibrosis (IPF) is more prevalent in males aged 60-75 years. SSc-ILD occurs earlier than IPF and progresses rapidly. FCN1, FABP4, and SPP1 macrophages are involved in the pathogenesis of lung fibrosis; SPP1 macrophages demonstrate upregulated expression in both SSc-ILD and IPF. To identify the differences between SSc-ILD and IPF using single-cell analysis, clarify their distinct pathogeneses, and propose directions for prevention and treatment.
METHODS: We performed single-cell RNA sequencing on NCBI Gene Expression Omnibus (GEO) databases GSE159354 and GSE212109, and analyzed lung tissue samples across healthy controls, IPF, and SSc-ILD. The primary measures were the filtered genes integrated with batch correction and annotated cell types for distinguishing patients with SSc-ILD from healthy controls. We proposed an SSc-ILD pathogenesis using cell-cell interaction inferences, and predicted transcription factors regulating target genes using SCENIC. Drug target prediction of the TF gene was performed using Drug Bank Online.
RESULTS: A subset of macrophages activates the MAPK signaling pathway under oxidative stress. Owing to the lack of inhibitory feedback from ANNEXIN and the autoimmune characteristics, this leads to an earlier onset of lung fibrosis compared to IPF. During initial lung injury, fibroblasts begin to activate the IL6 pathway under the influence of SPP1 alveolar macrophages, but IL6 appears unrelated to other inflammatory and immune cells. This may explain why tocilizumab (an anti-IL6-receptor antibody) only preserves lung function in patients with early SSc-ILD. Finally, we identified BCLAF1 and NFE2L2 as influencers of MAPK activation in macrophages. Metformin downregulates NFE2L2 and could serve as a repurposed drug candidate.
CONCLUSIONS: SPP1 alveolar macrophages play a role in the profibrotic activity of IPF and SSc-ILD. However, SSc-ILD is influenced by autoimmunity and oxidative stress, leading to the continuous activation of MAPK in macrophages. This may result in an earlier onset of lung fibrosis than in IPF. Such differences could serve as potential research directions for early prevention and treatment.