Role of hematopoietic microenvironment in prolonged impairment of B cell regeneration in age‐related stromal‐cell‐impaired SAMP1 mouse: effects of a single dose of 5‐fluorouracil

Abstract

In this study, we examined the age-associated defect of stromal cells, which support B cell development, treated with 5-fluorouracil (5-FU) to induce severe perturbation of hematopoiesis, including B lymphocyte development, using SAMP1 mice exhibiting senescence-mimicking stromal-cell impairment after 30 weeks of age. Significant findings of this study are as follows: first, a marked and prolonged decrease in number of CFU-preB cells in non-SCI mice (58% of the steady-state level) associated with more markedly depressed number of CFU-preB cells in SCI mice (20% of the steady-state level), despite the absence of difference in the number of CFU-GMs during the period; second, in the non-SCI mice, a significant and prolonged up-regulation of GM-CSF and IL-6, positive regulators of myelopoiesis and suppressive factors of B lymphopoiesis, was observed. In SCI mice, greater and prolonged suppression of B lymphopoiesis was clearly demonstrated by the significant up-regulation of the negative regulator TNF-alpha associated with the concomitant marked down-regulation of the positive regulator SDF-1, although the increases of GM-CSF and IL-6 were limited. That is, 'negative complementation' makes preB recovery after 5-FU treatment impaired and prolonged. Principal component analysis clearly showed differences in the cytokine expression patterns in both early and later phases and the time course of the expression pattern of each cytokine between SCI and non-SCI mice without supervising information. An impaired regulation of the expressions of not only positive but also negative regulators after 5-FU treatment was, in part, the cause of the impaired regeneration of CFU-preB cells in SCI mice.

Differential Regulation of Lympho-Myelopoiesis by Stromal Cells in the Early and Late Phases in BALB/c Mice Repeatedly Exposed to Lipopolysaccharide

“…7,9) However, several reports showed that age-related deterioration of B lymphopoiesis is in part due to functional impairment of stromal cells. [10][11][12][13] The effect of chronic exposure of hematopoietic cells to LPS has been extensively studied. However, little is known about the effect of chronic exposure to LPS on stromal cell function.…”

“…B lymphoid-progenitor (CFU-preB) cells were assayed using MethoCult M3630 according to the manufacturer's protocol. 12,13) Cells were cultured in a humidified incubator at 37°C and 5% CO 2 . CFU-GM and CFU-preB cells were counted 7 d after plating the cells.…”

“…Specific primers and probes for murine G-CSF, GM-CSF, IL-6, stromal cell-derived factor (SDF)-1, IL-7, stem cell factor (SCF), TNF-α, transforming growth factor (TGF)-β, and glyceraldehyde phosphate dehydrogenase (GAPDH) genes were purchased from Applied Biosystems as described elsewhere. 6,13) PCR conditions and data analysis were performed in accordance with the instructions provided with the Sequence Detection System (ver. 2.0).…”

Mast Cell Development and Biostresses: Different Stromal Responses in Bone Marrow and Spleen after Treatment of Myeloablater, 5-Fluorouracil, and Inflammatory Stressor, Lipopolysaccharide

“…12) A control group of mice were injected with the same volume of pyrogen-free saline (i.e., 6 ml per bw kg). Three mice from each treatment group were then evaluated 1, 2, 3, 4, 5, 6, 7, 10 and 14 d after treatment with 5-FU or saline.…”

“…10) Mast cell progenitors have been reported to show sensitivity to 5-fluorouracil (5-FU) in a manner similar to that which has been observed for other hematopoietic progenitor cell lineages, such as granulocytemacrophage progenitor cells (colony-forming unit (CFU)-GMs) and B-lymphoid progenitor cells. 11,12) Furthermore, lipopolysaccharide (LPS) is known to be an inflammatory stressor. Thus, disruption of the balance of positive and negative regulation, by methods such as 5-FU and LPS treatment, might reveal how mast cell development is regulated by positive and negative signals.…”