School of Medicine, Southwest Jiaotong University, Laboratory of Allergy and Precision Medicine, Chengdu Institute of Respiratory Health, The Third People's Hospital of Chengdu, Affiliated Hospital of Southwest Jiaotong University, Chengdu 610031, China; Department of Pulmonary and Critical Care Medicine, Chengdu Third People's Hospital Branch of National Clinical Research Center for Respiratory Disease, Affiliated Hospital of ChongQing Medical University, Chengdu 610031, China.
Department of Pulmonary and Critical Care Medicine, Sichuan Friendship Hospital, Chengdu 610000, China.
Int Immunopharmacol. 2023 Dec;125(Pt B):111209. doi: 10.1016/j.intimp.2023.111209. Epub 2023 Nov 15.
PM2.5 exposure increases asthma exacerbation risk and worsens airway inflammation and mucus secretion, but the underlying mechanisms, especially the epigenetic modification changes, are not fully understood.
ATAC-seq was conducted in Beas-2B cells to explore the differential chromatin accessibilities before and after exposure to PM2.5. RNA-seq was applied to screen the differentially expressed genes (DEGs) as well. The integrated analysis of ATAC-seq and RNA-seq was performed. The key up-regulated genes in the ferroptosis signaling pathway were identified by combined analysis with the FerrDb database and then verified. Meanwhile, to access the role of PM2.5-induced ferroptosis in asthma mice, house dust mites (HDM) were employed to conduct an allergic asthma mice model, and the ferroptosis-specific inhibitor (Ferrostatin-1, Fer-1) was used. The H&E staining, PAS staining, airway hyperresponsiveness, and bronchoalveolar lavage fluid (BALF) cell counting were used to investigate the impact of PM2.5-induced ferroptosis in asthma mice.
A total of 4,921 regions with differential accessibility were identified, encompassing 4,031 unique genes. Among these, 250 regions exhibited increased accessibility while 4,671 regions displayed reduced accessibility. Through the integrated analysis of ATAC-seq and RNA-seq, ferroptosis was determined as the key enriched pathway based on up-regulated DEGs and increased chromatin accessibilities. Furthermore, the decreased cell viability, accelerated lipid peroxide and morphological changes in mitochondria observed upon PM2.5 exposure were rescued by Fer-1, which are indicative of ferroptosis. By overlapping with ferroptosis-related genes from the FerrDb database, FTH1 and FTL were identified as the prominent up-regulated genes with increased chromatin accessibility in ferroptosis pathway. In addition, ChIP-qPCR analysis indicated that histone modification like H3K4me3 and H3K27ac positively regulated FTH1 and FTL expression. Subsequently, in PM2.5-exposed asthmatic mice, inhibition of ferroptosis effectively attenuated airway inflammation and mucus secretion.
These findings shed light on the molecular mechanisms underlying PM2.5-induced asthma exacerbation, with epigenetic modifications playing a pivotal role. Furthermore, it suggests the therapeutic potential of targeting ferroptosis as an intervention strategy.
PM2.5 暴露会增加哮喘恶化的风险，并加重气道炎症和黏液分泌，但潜在机制，特别是表观遗传修饰变化，尚不完全清楚。
在 Beas-2B 细胞中进行 ATAC-seq，以探索暴露于 PM2.5 前后的染色质可及性差异。应用 RNA-seq 筛选差异表达基因（DEGs）。对 ATAC-seq 和 RNA-seq 的综合分析。通过与 FerrDb 数据库的联合分析，确定铁死亡信号通路中关键上调基因，并进行验证。同时，为了研究 PM2.5 诱导的铁死亡在哮喘小鼠中的作用，采用屋尘螨（HDM）构建过敏性哮喘小鼠模型，并使用铁死亡特异性抑制剂（Ferrostatin-1，Fer-1）。采用 H&E 染色、PAS 染色、气道高反应性和支气管肺泡灌洗液（BALF）细胞计数来研究 PM2.5 诱导的铁死亡对哮喘小鼠的影响。
共鉴定出 4921 个具有差异可及性的区域，包含 4031 个独特的基因。其中，250 个区域的可及性增加，而 4671 个区域的可及性降低。通过 ATAC-seq 和 RNA-seq 的综合分析，根据上调的 DEGs 和增加的染色质可及性，确定铁死亡为关键富集途径。此外，PM2.5 暴露后细胞活力降低、脂质过氧化物加速和线粒体形态改变，这些铁死亡的特征均被 Fer-1 挽救，提示铁死亡的发生。通过与 FerrDb 数据库中的铁死亡相关基因重叠，发现 FTH1 和 FTL 是铁死亡途径中上调最显著的基因，其染色质可及性增加。此外，ChIP-qPCR 分析表明，组蛋白修饰如 H3K4me3 和 H3K27ac 正向调节 FTH1 和 FTL 的表达。随后，在 PM2.5 暴露的哮喘小鼠中，铁死亡抑制可有效减轻气道炎症和黏液分泌。
这些发现揭示了 PM2.5 诱导哮喘恶化的分子机制，表观遗传修饰起着关键作用。此外，它提示靶向铁死亡作为一种干预策略的治疗潜力。
