Sudo Takao, Yokota Takafumi, Okuzaki Daisuke, Ueda Tomoaki, Ichii Michiko, Ishibashi Tomohiko, Isono Tomomi, Habuchi Yoko, Oritani Kenji, Kanakura Yuzuru
Department of Hematology and Oncology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
DNA Chip Development Center, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan.
PLoS One. 2016 Apr 25;11(4):e0154189. doi: 10.1371/journal.pone.0154189. eCollection 2016.
Numerous red blood cells are generated every second from proliferative progenitor cells under a homeostatic state. Increased erythropoietic activity is required after myelo-suppression as a result of chemo-radio therapies. Our previous study revealed that the endothelial cell-selective adhesion molecule (ESAM), an authentic hematopoietic stem cell marker, plays essential roles in stress-induced hematopoiesis. To determine the physiological importance of ESAM in erythroid recovery, ESAM-knockout (KO) mice were treated with the anti-cancer drug, 5-fluorouracil (5-FU). ESAM-KO mice experienced severe and prolonged anemia after 5-FU treatment compared to wild-type (WT) mice. Eight days after the 5-FU injection, compared to WT mice, ESAM-KO mice showed reduced numbers of erythroid progenitors in bone marrow (BM) and spleen, and reticulocytes in peripheral blood. Megakaryocyte-erythrocyte progenitors (MEPs) from the BM of 5-FU-treated ESAM-KO mice showed reduced burst forming unit-erythrocyte (BFU-E) capacities than those from WT mice. BM transplantation revealed that hematopoietic stem/progenitor cells from ESAM-KO donors were more sensitive to 5-FU treatment than that from WT donors in the WT host mice. However, hematopoietic cells from WT donors transplanted into ESAM-KO host mice could normally reconstitute the erythroid lineage after a BM injury. These results suggested that ESAM expression in hematopoietic cells, but not environmental cells, is critical for hematopoietic recovery. We also found that 5-FU treatment induces the up-regulation of ESAM in primitive erythroid progenitors and macrophages that do not express ESAM under homeostatic conditions. The phenotypic change seen in macrophages might be functionally involved in the interaction between erythroid progenitors and their niche components during stress-induced acute erythropoiesis. Microarray analyses of primitive erythroid progenitors from 5-FU-treated WT and ESAM-KO mice revealed that various signaling pathways, including the GATA1 system, were impaired in ESAM-KO mice. Thus, our data demonstrate that ESAM expression in hematopoietic progenitors is essential for erythroid recovery after a BM injury.
在稳态下，增殖性祖细胞每秒会产生大量红细胞。化疗放疗导致骨髓抑制后，需要增强红细胞生成活性。我们之前的研究表明，内皮细胞选择性黏附分子（ESAM）作为一种真正的造血干细胞标志物，在应激诱导的造血过程中发挥着重要作用。为了确定ESAM在红细胞恢复中的生理重要性，我们用抗癌药物5-氟尿嘧啶（5-FU）处理了ESAM基因敲除（KO）小鼠。与野生型（WT）小鼠相比，ESAM-KO小鼠在接受5-FU治疗后出现了严重且持续时间较长的贫血。在5-FU注射8天后，与WT小鼠相比，ESAM-KO小鼠骨髓（BM）和脾脏中的红系祖细胞数量以及外周血中的网织红细胞数量均减少。5-FU处理的ESAM-KO小鼠骨髓中的巨核细胞-红细胞祖细胞（MEP）形成红细胞集落单位（BFU-E）的能力比WT小鼠的MEP降低。骨髓移植显示，在WT宿主小鼠中，来自ESAM-KO供体的造血干/祖细胞比来自WT供体的造血干/祖细胞对5-FU治疗更敏感。然而，将来自WT供体的造血细胞移植到ESAM-KO宿主小鼠中，在骨髓损伤后能够正常重建红系谱系。这些结果表明，造血细胞而非环境细胞中的ESAM表达对造血恢复至关重要。我们还发现，5-FU处理会诱导原始红系祖细胞和巨噬细胞中ESAM的上调，而在稳态条件下这些细胞并不表达ESAM。巨噬细胞中观察到的表型变化可能在应激诱导的急性红细胞生成过程中红系祖细胞与其龛位成分之间的相互作用中发挥功能作用。对5-FU处理的WT和ESAM-KO小鼠的原始红系祖细胞进行微阵列分析发现，包括GATA1系统在内的各种信号通路在ESAM-KO小鼠中受损。因此，我们的数据表明，造血祖细胞中的ESAM表达对于骨髓损伤后的红细胞恢复至关重要。
