Effects of sleep disorders on hematopoietic stem cells in bone marrow of irradiated mice / 中华放射医学与防护杂志

ABSTRACT

Objective:To investigate the effects of sleep disorders (SD) on the radiation injury of hematopoietic stem cells (HSCs) in bone marrow (BM).Methods:Totolly 56 C57BL/6J male mice aged 6-8 weeks were enrolled in this study. They were subjected to whole body irradiation of 60Co γ-rays with doses of 5.0 and 7.5 Gy. A SD model was established using a SD device. According to the random number table method, the mice were divided into seven groups: the control group (Con group), the SD group, the mere radiation group (IR group), the group of post-irradiation SD (IR+ SD group), the group of post-irradiation SD treated with phosphate buffer solution (IR+ SD+ PBS group), the group of post-irradiation SD treated with GSK2795039 (IR+ SD+ GSK group), and the group of post-irradiation SD treated with N-acetylcysteine (IR+ SD+ NAC group), with in eight mice each group. The changes in the peripheral blood of the mice after 5.0 Gy irradiation were detected using the collected tail venous blood, and the survival rates of the mice after 7.5 Gy irradiation were observed. The changes in the density and count of bone marrow cells were observed using hematoxylin and eosin (HE) staining. The number of hematopoietic stem cells in bone marrow (LSK cells), as well as their apoptosis level and changes in cell cycle, were detected using flow cytometry. Furthermore, indicators of LSK, such as reactive oxygen species(ROS) and mitochondrial-derived reactive oxygen species (mtROS), were analyzed. Nicotinamide adenine dinucleotide phosphate (NADP+ /NADPH) and glutathione (GSSG/GSH) were detected using an enzyme microplate reader in order to observe the oxidative stress level of LSK. Furthermore, flow cytometry was employed to sort the LSK cells from the mice, and flow cytometry was used to detect the expression of NADPH oxidase 2(NOX2) and cysteinyl aspartate specific proteinnase-1(Caspase-1), and polymerase chain reaction (PCR) was used to detect the expression of inflammatory factors such as NOX1-4, interleukin 1β (IL-1β), interleukin 6 (IL-6), interleukin 18 (IL-18), and tumor necrosis factor α (TNF-α). Results:Compared to the IR group, the IR+ SD group exhibited significantly slower recovery of white blood cells (WBC) and platelets (PLT) ( t = 4.39, 6.37, P < 0.05), the bone marrow cell count decreasing from (2.14 ± 0.38) × 10 7 to (3.59 ± 0.29) × 10 7 ( t = 8.55, P < 0.05), significantly decreased proportion of G 0-phase LSK cells, significantly increased proportion of apoptotic cells ( t = 7.53, 8.21, P < 0.05), and significantly increased DCFH-DA, MitoSOX, and NADP+ /NADPH ( t = 22.99, 29.47, 3.77, P<0.05). In the case of IR, SD further promoted the activation of NOX2 and led to increases in the mRNA expression of downstream inflammatory factors such as IL-1β, IL-6, IL-18, and TNF-α ( t = 6.95, 6.01, 8.39, 4.91, 5.56, P < 0.05). Inhibition of NOX2-ROS could prevent the SD-induced aggravation of post-irradiation hematopoietic injury. This significantly reduced the apoptotic rate of LSK cells and the expression of inflammatory factors, ultimately accelerating the hematopoietic recovery of LSK cells ( t = 9.24, 3.92, P < 0.05). Conclusions:SD can aggravate the IR-induced injury of hematopoietic stem cells in bone marrow, primarily by activating the NOX2-ROS-Caspase-1 axis. This will increase the levels of intracellular inflammatory factors and ROS, promote cell apoptosis, and ultimately inhibit the hematopoietic recovery of bone marrow.