Institut Pasteur, INSERM U1201, Unité de Parasitologie Moléculaire et Signalisation, Département des Parasites et Insectes Vecteurs, Paris, France.
Pasteur Institute of Shanghai, Innate Immunity Unit, Key Laboratory of Molecular Virology and Immunology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
Front Immunol. 2020 Jun 9;11:1098. doi: 10.3389/fimmu.2020.01098. eCollection 2020.
parasites are the causative agents of human leishmaniases. They infect professional phagocytes of their mammalian hosts, including dendritic cells (DCs) that are essential for the initiation of adaptive immune responses. These immune functions strictly depend on the DC's capacity to differentiate from immature, antigen-capturing cells to mature, antigen-presenting cells-a process accompanied by profound changes in cellular phenotype and expression profile. Only little is known on how intracellular affects this important process and DC transcriptional regulation. Here, we investigate these important open questions analyzing phenotypic, cytokine profile and transcriptomic changes in murine, immature bone marrow-derived DCs (iBMDCs) infected with antibody-opsonized and non-opsonized () amastigotes. DCs infected by non-opsonized amastigotes remained phenotypically immature whereas those infected by opsonized parasites displayed a semi-mature phenotype. The low frequency of infected DCs in culture led us to use Red2-transgenic parasites allowing for the enrichment of infected BMDCs by FACS. Sorted infected DCs were then subjected to transcriptomic analyses using Affymetrix GeneChip technology. Independent of parasite opsonization, infection induced expression of genes related to key DC processes involved in MHC Class I-restricted antigen presentation and alternative NF-κB activation. DCs infected by non-opsonized parasites maintained an immature phenotype and showed a small but significant down-regulation of gene expression related to pro-inflammatory TLR signaling, the canonical NF-kB pathway and the NLRP3 inflammasome. This transcriptomic profile was further enhanced in DCs infected with opsonized parasites that displayed a semi-mature phenotype despite absence of inflammasome activation. This paradoxical DC phenotype represents a -specific signature, which to our knowledge has not been observed with other opsonized infectious agents. In conclusion, systems-analyses of our transcriptomics data uncovered important and previously unappreciated changes in the DC transcription factor landscape, thus revealing a novel immune subversion strategy directly acting on transcriptional control of gene expression. Our data raise important questions on the dynamic and reciprocal interplay between -acting and epigenetic regulators in establishing permissive conditions for intracellular infection and polarization of the immune response.
寄生虫是人类利什曼病的病原体。它们感染哺乳动物宿主的专业吞噬细胞,包括树突状细胞(DCs),这些细胞对于启动适应性免疫反应至关重要。这些免疫功能严格依赖于 DC 从不成熟、抗原捕获细胞分化为成熟、抗原呈递细胞的能力——这一过程伴随着细胞表型和表达谱的深刻变化。关于细胞内如何影响这一重要过程和 DC 转录调控,我们知之甚少。在这里,我们通过分析被抗体调理和非调理的()无鞭毛体感染的小鼠、未成熟骨髓来源的树突状细胞(iBMDCs)的表型、细胞因子谱和转录组变化来研究这些重要的开放性问题。被非调理无鞭毛体感染的 DCs 保持表型不成熟,而被调理寄生虫感染的 DCs 则表现出半成熟表型。由于培养物中感染的 DC 频率较低,我们使用了 Red2 转基因寄生虫,通过 FACS 对感染的 BMDC 进行富集。然后对分选的感染 DC 进行 Affymetrix GeneChip 技术的转录组分析。独立于寄生虫调理,感染诱导了与 MHC 类限制抗原呈递和替代 NF-κB 激活相关的关键 DC 过程的基因表达。被非调理寄生虫感染的 DCs 保持不成熟表型,并且与促炎 TLR 信号、经典 NF-kB 途径和 NLRP3 炎性小体相关的基因表达表现出小但显著的下调。这种转录组谱在被调理寄生虫感染的 DCs 中进一步增强,尽管没有炎症小体激活,但这些 DCs 显示出半成熟表型。这种矛盾的 DC 表型代表了一种特定的特征,据我们所知,其他调理感染剂没有观察到这种特征。总之,我们的转录组数据分析的系统分析揭示了 DC 转录因子景观中的重要和以前未被认识到的变化,从而揭示了一种新的寄生虫免疫逃避策略,直接作用于基因表达的转录控制。我们的数据提出了关于在建立允许细胞内寄生虫感染和免疫反应极化的许可条件下,寄生虫作用和表观遗传调节剂之间的动态和相互作用的重要问题。
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