Department of Pediatrics and Microbiology and Immunology, Pulmonary Immunology and Physiology Laboratory, Pennsylvania State University College of Medicine, PA, USA.
Department of Pediatrics and Microbiology and Immunology, Pulmonary Immunology and Physiology Laboratory, Pennsylvania State University College of Medicine, PA, USA; Department of Pediatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Immunobiology. 2021 Nov;226(6):152150. doi: 10.1016/j.imbio.2021.152150. Epub 2021 Oct 25.
Macrophages play an important role in maintaining tissue homeostasis, from regulating the inflammatory response to pathogens to resolving inflammation and aiding tissue repair. The surfactant protein A (SP-A) receptor SP-R210 (MYO18A) has been shown to affect basal and inflammatory macrophage states. Specifically, disruption of the longer splice isoform SP-R210/MYO18Aα renders macrophages hyper-inflammatory, although the mechanism by which this occurs is not well understood. We asked whether disruption of the L isoform led to the hyper-inflammatory state via alteration of global genomic responses. RNA sequencing analysis of L isoform-deficient macrophages (SP-R210(DN)) revealed basal and influenza-induced upregulation of genes associated with inflammatory pathways, such as TLR, RIG-I, NOD, and cytoplasmic DNA signaling, whereas knockout of both SP-R210 isoforms (L and S) only resulted in increased RIG-I and NOD signaling. Chromatin immunoprecipitation sequencing (ChIP-seq) analysis showed increased genome-wide deposition of the pioneer transcription factor PU.1 in SP-R210(DN) cells, with increased representation around genes relevant to inflammatory pathways. Additional ChIP-seq analysis of histone H3 methylation marks showed decreases in both repressive H3K9me3 and H3K27me3 marks with a commensurate increase in transcriptionally active (H3K4me3) histone marks in the L isoform deficient macrophages. Influenza A virus (IAV) infection, known to stimulate a wide array of anti-viral responses, caused a differential redistribution of PU.1 binding between proximal promoter and distal sites and decoupling from Toll-like receptor regulated gene promoters in SP-R210(DN) cells. These finding suggest that the inflammatory differences seen in SP-R210-deficient macrophages are a result of transcriptional differences that are mediated by epigenetic changes brought about by differential expression of the SP-R210 isoforms. This provides an avenue to explore how the signaling pathways downstream of the receptor and the ligands can modulate the macrophage inflammatory response.
巨噬细胞在维持组织内稳态方面发挥着重要作用，从调节对病原体的炎症反应到解决炎症和帮助组织修复。表面活性蛋白 A (SP-A) 受体 SP-R210 (MYO18A) 已被证明会影响基础和炎症巨噬细胞状态。具体来说，较长剪接异构体 SP-R210/MYO18Aα 的破坏使巨噬细胞呈过度炎症状态，尽管其发生的机制尚不清楚。我们想知道 L 异构体的破坏是否通过改变全基因组反应导致了过度炎症状态。L 异构体缺陷型巨噬细胞 (SP-R210(DN)) 的 RNA 测序分析显示，基础状态和流感诱导的与炎症途径相关的基因上调，如 TLR、RIG-I、NOD 和细胞质 DNA 信号，而 SP-R210 两种异构体 (L 和 S) 的敲除仅导致 RIG-I 和 NOD 信号增加。染色质免疫沉淀测序 (ChIP-seq) 分析显示，SP-R210(DN) 细胞中广泛沉积了先驱转录因子 PU.1，在与炎症途径相关的基因周围的代表性增加。对组蛋白 H3 甲基化标记的进一步 ChIP-seq 分析显示，在 L 异构体缺陷型巨噬细胞中，抑制性 H3K9me3 和 H3K27me3 标记减少，而转录活性 (H3K4me3) 组蛋白标记增加。流感病毒 (IAV) 感染已知会刺激广泛的抗病毒反应，导致 SP-R210(DN) 细胞中近端启动子和远端结合位点的 PU.1 结合的差异分布，并与 Toll 样受体调节基因启动子解耦。这些发现表明，SP-R210 缺陷型巨噬细胞中观察到的炎症差异是由转录差异引起的，而转录差异是由 SP-R210 异构体的差异表达引起的表观遗传变化介导的。这为探索受体和配体下游的信号通路如何调节巨噬细胞炎症反应提供了一个途径。
