Hematopoietic stem and progenitor cells (HSPCs) are known to produce short-lived mature blood cells via proliferation and differentiation in a process that depends partially on regulatory cytokines from the bone marrow (BM) microenvironment. Delayed BM recovery after tremendous damage to the hematopoietic system can lead to neutropenia, anemia, thrombopenia and even death. However, efficiently promote BM recovery is still a big problem to be solved. Here, the authors aim to use heat-inactivated Escherichia coli (HIEC) to enhance BM recovery and further to find out the potential mechanism.
X-rad was used to establish HIEC/IL-1β-induced radioprotection model. Single-cell RNA sequencing, RT-PCR, and western blotting were performed to detect the expression of IL-1R1 on HSPCs. Flow cytometry and automated hematology analyzer were used to analyze the percentage and absolute number of different populations of hematopoietic cells. The effects of IL-1β on HSPCs were studied using in vivo and in vitro experiments.
HIEC/IL-1β pre-treatment can significantly increase the survival rate of lethally irradiated mice, and these mice showed better hematopoietic regeneration compared with control group. IL-1R was expressed on HSPCs, and IL-1β could directly function on HSPCs to promote the proliferation and differentiation of HSPCs, and inhibit the apoptosis of HSPCs.
HIEC pre-treatment can rescue lethally irradiated mice by promoting hematopoietic recovery via IL-1β/IL-1R1 signaling, which can promote the proliferation of HSPCs by enhancing the cell cycle and attenuating the apoptosis of HSPCs.

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