Project description:Recent studies demonstrate that inflammatory signals regulate hematopoietic stem cells (HSCs). Granulocyte-colony stimulating factor (G-CSF) is often induced with infection and plays a key role in the stress granulopoiesis response. However, its effects on HSCs are less clear. Herein, we show that treatment with G-CSF induces expansion and increased quiescence of phenotypic HSCs, but causes a marked, cell-autonomous HSC repopulating defect associated with induction of toll-like receptor (TLR) expression and signaling. The G-CSF-mediated expansion of HSCs is reduced in mice lacking TLR2, TLR4 or the TLR signaling adaptor MyD88. Induction of HSC quiescence is abrogated in mice lacking MyD88 or in mice treated with antibiotics to suppress intestinal flora. Finally, loss of TLR4 or germ free conditions mitigates the G-CSF-mediated HSC repopulating defect. These data suggest that low level TLR agonist production by commensal flora contributes to the regulation of HSC function and that G-CSF negatively regulates HSCs, in part, by enhancing TLR signaling. RNA from KSL SLAM cells (Lineage- c-Kit+ Sca-1+ CD150+ CD48- CD41-) from bone marrow of 5-10 mice per group treated with G-CSF or saline alone was prepared using the RNA XS column kit (Machery-Nagel), amplified using the NuGen Ovation system (NuGen) and hybridized to the MoGene 1.0 ST array. This array includes 3 independent PBS control and 3 G-CSF treated groups.
Project description:Recent studies demonstrate that inflammatory signals regulate hematopoietic stem cells (HSCs). Granulocyte-colony stimulating factor (G-CSF) is often induced with infection and plays a key role in the stress granulopoiesis response. However, its effects on HSCs are less clear. Herein, we show that treatment with G-CSF induces expansion and increased quiescence of phenotypic HSCs, but causes a marked, cell-autonomous HSC repopulating defect associated with induction of toll-like receptor (TLR) expression and signaling. The G-CSF-mediated expansion of HSCs is reduced in mice lacking TLR2, TLR4 or the TLR signaling adaptor MyD88. Induction of HSC quiescence is abrogated in mice lacking MyD88 or in mice treated with antibiotics to suppress intestinal flora. Finally, loss of TLR4 or germ free conditions mitigates the G-CSF-mediated HSC repopulating defect. These data suggest that low level TLR agonist production by commensal flora contributes to the regulation of HSC function and that G-CSF negatively regulates HSCs, in part, by enhancing TLR signaling. RNA from KSL SLAM cells (Lineage- c-Kit+ Sca-1+ CD150+ CD48- CD41-) from bone marrow of 5-10 mice per group treated with G-CSF or saline alone was prepared using the RNA XS column kit (Machery-Nagel), amplified using the NuGen Ovation system (NuGen) and hybridized to the MoGene 1.0 ST array. This array includes 4 independent PBS control and 4 G-CSF treated groups.
Project description:Although hematopoietic stem and progenitor cells (HSPCs) become activated in the cell-cycle status after chemotherapy to supply hematopoietic loss, the detailed mechanisms of activation remain unknown. Here we show that Sca1+ macrophages play a key role for bone marrow (BM) recovery through granulocyte-macrophage colony-stimulating factor (GM-CSF) secretion. By analyzing gene expression profiles of HSPCs lodged in 5-fluolouracil (5-FU)-treated mice, we found GM-CSF as a key proliferative signal. Sca1+ macrophages in BM after 5-FU treatment expressed high levels of GM-CSF. GM-CSF-knockout mice treated with 5-FU were lethal because of severe BM suppression. Up-regulation of Csf2 in Sca1+ macrophages by 5-FU was suppressed in MyD88-knockout mice, suggesting that TLR signaling via damage-associated molecular patterns caused by cell death is critical for up-regulation of Csf2. In 5-FU treated BM, majority of Sca1+ macrophages and transplanted HSPCs locate perivascular areas. These findings together indicate that Sca1+ macrophages induce HSPCs to proliferate through GM-CSF signaling in the stressed BM environments.
Project description:Although hematopoietic stem and progenitor cells (HSPCs) become activated in the cell-cycle status after chemotherapy to supply hematopoietic loss, the detailed mechanisms of activation remain unknown. Here we show that Sca1+ macrophages play a key role for bone marrow (BM) recovery through granulocyte-macrophage colony-stimulating factor (GM-CSF) secretion. By analyzing gene expression profiles of HSPCs lodged in 5-fluolouracil (5-FU)-treated mice, we found GM-CSF as a key proliferative signal. Sca1+ macrophages in BM after 5-FU treatment expressed high levels of GM-CSF. GM-CSF-knockout mice treated with 5-FU were lethal because of severe BM suppression. Up-regulation of Csf2 in Sca1+ macrophages by 5-FU was suppressed in MyD88-knockout mice, suggesting that TLR signaling via damage-associated molecular patterns caused by cell death is critical for up-regulation of Csf2. In 5-FU treated BM, majority of Sca1+ macrophages and transplanted HSPCs locate perivascular areas. These findings together indicate that Sca1+ macrophages induce HSPCs to proliferate through GM-CSF signaling in the stressed BM environments.
Project description:Granulocyte colony-stimulating factor (G-CSF) has been utilized to treat neutropenia in various clinical settings. Although clearly beneficial, there are concerns that use of G-CSF in certain conditions increases the risk of myelodysplastic syndrome (MDS) and/or acute myeloid leukemia (AML). The most striking example is in severe congenital neutropenia (SCN). SCN patients develop MDS/AML at a high rate that is directly correlated to the cumulative lifetime dosage of G-CSF. MDS and AML that arise in these settings are commonly associated with chromosomal deletions. We demonstrate that chronic G-CSF treatment in mice results in expansion of the hematopoietic stem cell population. Furthermore, primitive hematopoietic progenitors from G-CSF–treated mice show evidence of DNA damage as demonstrated by an increase in double strand breaks and recurrent chromosomal deletions. Concurrent treatment with genistein, a natural soy isoflavone, limits DNA damage in this population. The protective effect of genistein appears to be related to its preferential inhibition of G-CSF–induced proliferation of hematopoietic stem cells. Importantly, genistein does not impair G-CSF–induced proliferation of committed hematopoietic progenitors, nor diminish neutrophil production. The protective effect of genistein was accomplished with plasma levels that are easily attainable through dietary supplementation. aCGH was performed using NimbleGen
Project description:Current therapies for metastatic colorectal cancer only prolong life for approximately 2 years. A more innovative therapy that prolongs life significantly or even cures is needed. Bone marrow transplantation is a curative therapy for patients with leukemias and lymphomas. Tumor eradication in the case of transplantation of the patient’s own marrow (autologous transplantation) is based on the intensive chemotherapy and/or radiotherapy used for conditioning. Tumor eradication in the case of transplantation using the marrow of a normal donor is based on both tumor reduction from conditioning and the immune elimination of tumor cells by T cells in the donor transplant that recognize the foreign tissue antigens expressed by the tumor cells and kill these cells. The use of bone marrow transplantation to treat tumors other than leukemia and lymphoma has been limited, and studies of transplantation of the patient’s own marrow for the treatment of advanced /metastatic breast cancer have not conclusively shown benefit beyond conventional therapy.
Recently, the Strober lab developed a preclinical model that effectively treated colon cancer in mice by combining immunotherapy and autologous bone marrow transplantation in order to markedly augment the anti-tumor potency of immunotherapy. They used the CT26 colon cancer as the therapeutic target either as a single subcutaneous tumor nodule, as a disseminated tumor in the lungs and peritoneum, or as a metastatic tumor in the liver depending on the route of administration of the tumor cells in BALB/c mice. Mice were vaccinated mice with established primary tumors or disseminated/ metastatic disease with irradiated tumor cells mixed with the adjuvant CpG, and found that vaccination alone had no effect on tumor growth. Similarly radiation conditioning of tumor bearing hosts followed by transplantation of bone marrow and spleen cells or purified T cells and hematopoietic stem cells from unvaccinated donors of the same strain had no effect. In contrast, radiation conditioning of mice followed by transplantation of hematopoietic and immune cells from donors of the same strain vaccinated with tumor cells and CpG cured almost all subcutaneous primary as well as disseminated and metastatic tumors in the hosts. A similar result was obtained after autologous transplantation of hematopoietic and immune cells from tumor bearing mice that had been vaccinated after tumor establishment. Investigation of tumor infiltrating cells showed that the injected donor T cells do not accumulate in the tumors unless the host has been irradiated before injection.
Based on this model, we have assembled a team of Stanford University faculty members with expertise in gastrointestinal cancers, immunotherapy, radiation oncology, and bone marrow transplantation in the Departments of Medicine and Pathology to translate the preclinical findings into a Phase I safety and feasibility clinical study for the treatment of 10 patients with metastatic colorectal cancer. Resected tumor cells will be irradiated and mixed with CpG to create a vaccine. Patients will receive subcutaneous vaccination at weeks 1 and 2 after resection. Six weeks later, immune T cells and then G-CSF "mobilized" purified blood progenitor cells will be harvested from the blood and cryopreserved. If needed patients will receive chemotherapy for tumor reduction. When disease is controlled off chemotherapy, patients will receive a conditioning regimen of fludarabine (30mg/m2 daily x 3 days) followed by intensive fractionated total body irradiation. The dose of fTBI will be escalated using a 3+3 design to ensure safety and will range from 400 to 800 gray. The patient will then undergo hematopoietic and immune cell rescue. They will undergo a third vaccination within 7-14 days after transplant. Thereafter, serial monitoring of tumor burden will continue.
Immune monitoring will occur before and after vaccination as well as after transplantation. Tests will include in vitro anti-tumor immune responses of T cells (proliferation, cytotoxicity, cytokine secretion etc.) to stimulation with whole tumor cells and tumor cell lysates pulsed on to antigen presenting cells, anti-tumor antibody responses, and immune reconstitution after transplantation.