骨髓生长因子途径基因（如JAK2）和参与表观遗传调控的基因（如TET2）在造血干细胞（HSCs）中的体细胞突变会导致不确定潜力的克隆性造血，从而增加造血恶性肿瘤和心血管疾病的风险。吸烟行为与克隆性扩张的发生频繁相关，但吸烟是否作为环境炎症应激剂促进克隆扩张的机制尚未研究。我们对野生型（WT）小鼠和携带Jak2V617F突变和Tet2基因敲除（Tet-/-）细胞的移植小鼠进行了体内烟熏暴露，以确定香烟对HSC区域以及有利于突变细胞扩张的影响。暴露于烟雾中的WT小鼠表现出长期HSCs中的氧化应激增加以及造血干细胞和前体细胞群的抑制，但是烟雾暴露并没有导致一次性骨髓移植的造血能力受损。骨髓造血细胞的基因表达分析发现Th17和Treg免疫细胞之间存在不平衡，暗示了局部炎症环境。我们还观察到在体内暴露于烟雾和体外香烟烟雾提取物（CSE）中，Jak2V617F细胞的存活增强。WT/Jak2V617F嵌合小鼠骨髓造血细胞在烟雾暴露后显示中性粒细胞数量增加以及骨髓基质抗原2（Bst2）和早期维甲酸转录本1（Raet1）靶标的明显过度表达。Bst2和Raet1表示干扰素信号和细胞胁迫（包括氧化应激和DNA损伤）增加。在同时含有WT和Tet2-/-细胞的嵌合小鼠中，我们观察到在香烟熏蒸后与预暴露水平相比，周围血液循环中突变细胞的百分比增加，而在空气暴露对照组中不存在这种差异。总之，这些发现表明，香烟熏蒸导致骨髓环境发炎，为现有的JAK2V617F和TET2功能缺失等CHIP突变提供了选择压力。

Somatic mutations in myeloid growth factor pathway genes, such as JAK2, and genes involved in epigenetic regulation, such as TET2, in hematopoietic stem cells (HSCs) leads to clonal hematopoiesis of indeterminate potential (CHIP) which presents a risk factor for hematologic malignancy and cardiovascular disease. Smoking behavior has been repeatedly associated with the occurrence of CHIP but whether smoking is an environmental inflammatory stressor in promoting clonal expansion has not been investigated.We performed in vivo smoke exposures in both wildtype (WT) mice and transplanted mice carrying Jak2V617F mutant and Tet2 knockout (Tet-/-) cells to determine the impact of cigarette smoke (CS) in the HSC compartment as well as favoring mutant cell expansion.WT mice exposed to smoke displayed increased oxidative stress in long-term HSCs and suppression of the hematopoietic stem and progenitor compartment but smoke exposure did not translate to impaired hematopoietic reconstitution in primary bone marrow transplants. Gene expression analysis of hematopoietic cells in the bone marrow identified an imbalance between Th17 and Treg immune cells suggesting a local inflammatory environment. We also observed enhanced survival of Jak2V617F cells exposed to CS in vivo and cigarette smoke extract (CSE) in vitro. WT bone marrow hematopoietic cells from WT/Jak2V617F chimeric mice exposed to CS demonstrated an increase in neutrophil abundance and distinct overexpression of bone marrow stromal antigen 2 (Bst2) and retinoic acid early transcript 1 (Raet1) targets. Bst2 and Raet1 are indicative of increased interferon signaling and cellular stress including oxidative stress and DNA damage, respectively. In chimeric mice containing both WT and Tet2-/- cells, we observed an increased percentage of circulating mutant cells in peripheral blood post-cigarette smoke exposure when compared to pre-exposure levels while this difference was absent in air-exposed controls.Altogether, these findings demonstrate that CS results in an inflamed bone marrow environment that provides a selection pressure for existing CHIP mutations such as Jak2V617F and Tet2 loss-of-function.Copyright © 2023 Ramanathan, Chen, Mehrotra, Trieu, Huang, Mas, Monterrosa Mena, Bliss, Herman, Kleinman and Fleischman.