Bujko Kamila, Adamiak Mateusz, Konopko Adrian, Chumak Vira, Ratajczak Janina, Brzezniakiewicz-Janus Katarzyna, Kucia Magdalena, Ratajczak Mariusz Z
Stem Cell Institute at James Graham Brown Cancer Center, University of Louisville, 500 S. Floyd Street, Rm. 107, Louisville, KY, 40202, USA.
Center for Preclinical Studies and Technology, Laboratory of Regenerative Medicine at Medical, University of Warsaw, Warsaw, Poland.
Stem Cell Rev Rep. 2025 Jan;21(1):45-58. doi: 10.1007/s12015-024-10775-7. Epub 2024 Aug 13.
NADPH oxidase 2 (Nox2), a superoxide-generating enzyme, is a source of reactive oxygen species (ROS) that regulate the intracellular redox state, self-renewal, and fate of hematopoietic stem/progenitor cells (HSPCs). Nox2 complex expressed on HSPCs associated with several activated cell membrane receptors increases the intracellular level of ROS. In addition, ROS are also released from mitochondria and, all together, are potent activators of intracellular pattern recognition receptor Nlrp3 inflammasome, which regulates the trafficking, proliferation, and metabolism of HSPCs. In the current study, we noticed that Nox2-deficient mice, despite the increased number of HSPCs in the bone marrow (BM), show hematopoietic defects illustrated by delayed recovery of peripheral blood (PB) hematopoietic parameters after sublethal irradiation and mobilize fewer HSPCs after administration of G-CSF and AMD3100. Moreover, Nox2-deficient HSPCs engraft poorly after transplantation into normal syngeneic recipients. To explain these defects at the molecular level, we hypothesized that Nox2-KO decreased ROS level does not efficiently activate Nlrp3 inflammasome, which plays a crucial role in regulating the trafficking of HSPCs. Herein, we report Nox2-deficient HSPCs display i) defective migration to major chemoattractant, ii) impaired intracellular activation of Nlrp3 inflammasome, and iii) a defect in membrane lipid raft (MLRs) formation that is required for a proper chemotactic response to pro-migratory factors. We conclude that Nox2-derived ROS enhances in Nlrp3 inflammasome-dependent manner HSPCs trafficking by facilitating MLRs assemble on the outer cell membranes, and defect in Nox2 expression results in impaired activation of Nlrp3 inflammasome, which affects HSPCs migration.
NADPH氧化酶2（Nox2）是一种产生超氧化物的酶，是活性氧（ROS）的来源，可调节造血干/祖细胞（HSPCs）的细胞内氧化还原状态、自我更新和命运。HSPCs上表达的Nox2复合物与几种活化的细胞膜受体相关，可增加细胞内ROS水平。此外，ROS也从线粒体释放，并且共同作为细胞内模式识别受体Nlrp3炎性小体的有效激活剂，该炎性小体调节HSPCs的运输、增殖和代谢。在本研究中，我们注意到Nox2缺陷小鼠尽管骨髓（BM）中HSPCs数量增加，但表现出造血缺陷，表现为亚致死剂量照射后外周血（PB）造血参数恢复延迟，并且在给予粒细胞集落刺激因子（G-CSF）和AMD3100后动员的HSPCs较少。此外，Nox2缺陷的HSPCs移植到正常同基因受体后植入情况不佳。为了在分子水平上解释这些缺陷，我们假设Nox2基因敲除导致的ROS水平降低不能有效激活Nlrp3炎性小体，而Nlrp3炎性小体在调节HSPCs的运输中起关键作用。在此，我们报告Nox2缺陷的HSPCs表现出：i）向主要趋化因子迁移的缺陷；ii）Nlrp3炎性小体的细胞内激活受损；iii）膜脂筏（MLRs）形成缺陷，而膜脂筏形成是对促迁移因子产生适当趋化反应所必需的。我们得出结论，Nox2衍生的ROS以Nlrp3炎性小体依赖性方式通过促进MLRs在外细胞膜上组装来增强HSPCs运输，并且Nox2表达缺陷导致Nlrp3炎性小体激活受损，从而影响HSPCs迁移。
