Altered microRNA expression links IL6 and TNF-induced inflammaging with myeloid malignancy [miR146aKO_ESLAM_SCBS]

Aging is associated with significant changes in the hematopoietic system, including increased inflammation, impaired hematopoietic stem cell (HSC) function, and increased incidence of myeloid malignancy. Inflammation of aging (“inflammaging”) has been proposed as a driver of age-related changes in HSC function and myeloid malignancy, but mechanisms linking these phenomena remain poorly defined. Here, we identify loss of miR-146a as driving aging-associated inflammation in AML patients. miR-146a expression declined in old wild-type mice, and loss of miR-146a promoted premature HSC aging and inflammation in young miR-146a-null mice, preceding development of aging-associated myeloid malignancy. Using single-cell assays of HSC quiescence, stemness, differentiation potential, and epigenetic state to probe HSC function and population structure, we found that loss of miR-146a depleted a subpopulation of primitive, quiescent HSCs. DNA methylation and transcriptome profiling implicated NF-?B, IL6, and TNF as potential drivers of HSC dysfunction, activating an inflammatory signaling relay promoting IL6 and TNF secretion from mature miR-146a-/- myeloid and lymphoid cells. Reducing inflammation by targeting Il6 or Tnf was sufficient to restore single-cell measures of miR-146a-/- HSC function and subpopulation structure, and reduced the incidence of hematological malignancy in miR 146a-/- mice. miR-146a-/- HSCs exhibited enhanced sensitivity to IL6 stimulation, indicating that loss of miR-146a affects HSC function via both cell-extrinsic inflammatory signals and increased cell-intrinsic sensitivity to inflammation. Thus, loss of miR 146a regulates cell-extrinsic and -intrinsic mechanisms linking HSC inflammaging to the development of myeloid malignancy. Overall design: 2 cell types, 2 genotypes, single-cell analysis: 64 WT LSK cells (see GSE89545), 83 WT ESLAM cells (see GSE89545), & 69 miR-146a-/- ESLAM cells, 43 passing QC (this series)

衰老与造血系统的一系列显著改变密切相关，包括炎症水平升高、造血干细胞（hematopoietic stem cell, HSC）功能受损以及髓系恶性肿瘤发病率上升。衰老相关炎症（inflammaging，即炎症衰老）被认为是驱动造血干细胞功能衰老相关改变以及髓系恶性肿瘤发生的关键因素，但连接这些现象的具体分子机制仍未明确。本研究证实，微RNA-146a（miR-146a）的缺失是急性髓系白血病（acute myeloid leukemia, AML）患者衰老相关炎症的驱动因素。老年野生型小鼠体内miR-146a的表达水平显著下降，而在年轻miR-146a敲除（miR-146a-/-）小鼠中，miR-146a的缺失会提前促进造血干细胞过早衰老与炎症反应，且早于衰老相关髓系恶性肿瘤的发生。本研究通过针对造血干细胞静息状态、干细胞干性、分化潜能以及表观遗传状态的单细胞检测技术，探究造血干细胞的功能与群体结构，发现miR-146a的缺失会耗竭原始静息造血干细胞亚群。DNA甲基化与转录组测序分析显示，核因子κB（nuclear factor kappa-light-chain-enhancer of activated B cells, NF-κB）、白细胞介素6（interleukin 6, IL-6）以及肿瘤坏死因子（tumor necrosis factor, TNF）是造血干细胞功能异常的潜在驱动因子，其激活的炎症信号通路可促进成熟miR-146a敲除髓系与淋巴系细胞分泌IL-6与TNF。通过靶向IL-6或TNF以降低炎症水平，足以恢复miR-146a敲除小鼠造血干细胞的单细胞功能检测指标与亚群结构，并降低miR-146a敲除小鼠血液系统恶性肿瘤的发病率。miR-146a敲除的造血干细胞对IL-6刺激的敏感性显著增强，表明miR-146a的缺失可通过细胞外炎症信号以及细胞固有炎症敏感性升高这两种途径影响造血干细胞功能。综上，miR-146a的缺失通过调控细胞外与细胞内的分子机制，将造血干细胞炎症衰老与髓系恶性肿瘤的发生联系起来。实验整体设计：包含2种细胞类型、2种基因型，共开展单细胞分析：64个野生型LSK细胞（详见GSE89545）、83个野生型ESLAM细胞（详见GSE89545）以及69个miR-146a-/- ESLAM细胞，其中43个通过质量控制（quality control, QC）（本数据集系列）