Investigation of immune-cell differentiation and function is limited by shortcomings of suitable and scalable experimental systems. Here we show that retroviral delivery of an estrogen-regulated form of Hoxb8 into mouse bone marrow cells can be used along with Flt3 ligand to conditionally immortalize early hematopoietic progenitor cells (Hoxb8-FL cells). Hoxb8-FL cells have lost self-renewal capacity and potential to differentiate into megakaryocytes and erythrocytes but retain the potential to differentiate into myeloid and lymphoid cells. They differentiate in vitro and in vivo into macrophages, granulocytes, dendritic cells, B lymphocytes and T lymphocytes that are phenotypically and functionally indistinguishable from their primary counterparts. Quantitative in vitro assays indicate that myeloid and B-cell potential of Hoxb8-FL cells is comparable to that of primary lymphoid-primed multipotent progenitors, whereas T-cell potential is diminished. The simplicity of this system and the unlimited proliferative capacity of Hoxb8-FL cells will enable studies of immune-cell differentiation and function.
Hematopoietic progenitor cell lines with myeloid and lymphoid potential.
Specimen part
View SamplesIL-10 regulates anti-inflammatory signaling via the activation of STAT3, which in turn controls the induction of a gene expression program whose products execute inhibitory effects on pro-inflammatory mediator production. Here we show that IL-10 induces the expression of an ETS family transcriptional repressor, ETV3 and a helicase family co-repressor, SBNO2 (Strawberry notch homolog 2) in mouse and human macrophages. IL-10-mediated induction of ETV3 and SBNO2 expression was dependent upon both STAT3, and co-stimulus through the TLR pathway. We also observed that ETV3 expression was strongly induced by the STAT3 pathway induced by IL-10 but not STAT3 signaling activated by IL-6, which cannot activate the anti-inflammatory signaling pathway. ETV3 and SBNO2 specifically repressed NF-kB-mediated transcription and can physically interact. Collectively our data suggest that ETV3 and SBNO2 are components of the pathways that contribute to the downstream anti-inflammatory effects of IL-10.
Cutting edge: A transcriptional repressor and corepressor induced by the STAT3-regulated anti-inflammatory signaling pathway.
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View SamplesPatients relapsing with FLT3-ITD mutant acute myeloid leukemia (AML) after allogeneic hematopoietic cell transplantation (allo-HCT) have a one-year-survival below 20%. We observed that sorafenib increased IL-15 production by FLT3-ITD+-leukemia cells, which synergized with the allogeneic CD8+T-cell response, leading to long-term survival in murine and humanized FLT3-ITD+AML models. Using IL-15 deficiency in recipient tissues or leukemia cells, IL-15 production upon sorafenib-treatment could be attributed to leukemia cells. Sorafenib treatment-related IL-15 production caused an increase in CD8+CD107a+IFN-+ T-cells with features of longevity (Bcl-2high/reduced PD-1-levels), which eradicated leukemia in secondary recipients. Mechanistically, sorafenib reduced ATF4 expression, thereby blocking negative regulation of IRF7-activation, which enhances IL-15 transcription. Consistent with the mouse data, IL-15 and pIRF7 levels increased in leukemic blasts of FLT3-ITD+AML patients upon sorafenib treatment. Analysis of 130 patients with FLT3-ITD-mutant AML relapsing after allo-HCT showed the highest complete remission-rate and median overall-survival-rate in the sorafenib/donor lymphocyte infusion (DLI) group compared to all other groups (chemotherapy, chemotherapy/DLI, sorafenib alone). Our findings indicate that the synergism of DLI and sorafenib is mediated via reduced ATF4 expression, causing activation of the pIRF7/IL-15-axis in leukemia cells. The sorafenib/DLI strategy therefore has the potential for an immune-mediated cure of FLT3-ITD-mutant AML- relapse, an otherwise fatal complication after allo-HCT.
Sorafenib promotes graft-versus-leukemia activity in mice and humans through IL-15 production in FLT3-ITD-mutant leukemia cells.
Specimen part, Treatment, Time
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