Effect of administration timing of postchemotherapy granulocyte colony-stimulating factor on host-immune cell recovery and CD8+ T-cell response

Immunomodulatory Effects of Lepidium meyenii Walp. Polysaccharides on an Immunosuppression Model Induced by Cyclophosphamide

Background

Lepidium meyenii Walp. (Maca) has emerged as a functional plant food and traditional herb owing to its biological activities; Maca polysaccharides as an important active component of Maca have good immunomodulatory effect; however, studies on the immunomodulatory effect of Maca polysaccharides are mainly focused on macrophages; little attention has been devoted to the mechanisms and other immune cells. This study is aimed at investigating the immunomodulatory effects and mechanisms of Maca polysaccharides.

Methods

Sixty mice were divided into five groups, and the mice were injected with cyclophosphamide to establish an immunosuppression model except for those in the common group. The body weights were measured, as well as immune-related indices, such as organ indices, haematological parameters, lymphocyte cycle, and proliferation, cytokine, and protein expression levels.

Results

The weight loss and immune organ index decline caused by cyclophosphamide could be reversed by MP. Furthermore, MP increased WBC and HGB counts and reduced the ratio of G0/G1 phase obviously, increased the proportion of S phase and G2/M phase in peripheral blood lymphocytes, increased the counts of CD4+ T cells and the ratio of CD4+/CD8+, and reduced the inhibition rate of splenic lymphocytes. MP affected the production of cytokines by increasing IFN-γ, TNF-α, and IL-2 levels and by decreasing IL-4 levels. MP increased the mRNA expression of T-bet and the protein expression of Bcl-2 in the spleen and decreased the protein expression of caspase-3 and Bax.

Conclusions

Maca polysaccharides might be the basic material for Maca's immunomodulatory effect. The mechanism was perhaps related to inhibiting lymphocyte apoptosis and promoting the balance of Th1/Th2 cell subsets.

Beneficial Modulatory Effects of Treatment With Bone Marrow Lysate on Hematopoietic Stem Cells and Myeloid Cells in Tumor-Bearing Mice

Introduction: Leukopenia is one of the major side effects of myelosuppressive chemotherapy such as cyclophosphamide (CTX). We and others have used CTX either alone or in combination with G-CSF for the mobilization of hematopoietic stem cells (HSCs). This mobilization can induce expansion of myeloid cells with immunosuppressive phenotype. In this pilot study, we aimed to test whether bone marrow lysate (BML)/CTX, a rich source of growth factors, can lower the expansion of myeloid cells with immunosuppressive phenotypes in tumor-bearing mice without interfering with the anti-tumor effects of CTX or with the mobilization of HSCs.

Methods: Female CD1 mice were treated on day 0 with an i.p. injection of Ehrlich ascites carcinoma (EAC). On day 7, the mice were i.p. injected with CTX followed by s.c. injection of G-CSF for 5 consecutive days, single s.c. injection of BML/PBS or BML/CTX or single i.v. injection of BMC/PBS or BMC/CTX.

Results: Treatment of EAC-bearing mice with BML/PBS or BML/CTX did not interfere with the anti-tumor effect of CTX. EAC increased the numbers of immature polymorphonuclear cells (iPMN; neutrophils) in both blood and spleen. Treatment of EAC-bearing mice with CTX further increased the numbers of these cells, which were decreased upon treatment with BML/CTX. Treatment with BML/PBS or BML/CTX increased the numbers of stem cells (C.Kit⁺Sca^-1⁺) in BM; the effect of BML/CTX was higher, but with no significant effect on the numbers of HSCs. Future studies are needed to analyze the molecular components in BM lysate and to determine the underlying mechanisms.

G-CSF induces CD15+ CD14+ cells from granulocytes early in the physiological environment of pregnancy and the cancer immunosuppressive microenvironment

Objectives

Recombinant granulocyte colony-stimulating factor (G-CSF) is frequently administered to patients with cancer to enhance granulocyte recovery post-chemotherapy. Clinical trials have also used G-CSF to modulate myeloid cell function in pregnancy and inflammatory diseases. Although the contribution of G-CSF to expanding normal granulocytes is well known, the effect of this cytokine on the phenotype and function of immunosuppressive granulocytic cells remains unclear. Here, we investigate the impact of physiological and iatrogenic G-CSF on an as yet undescribed granulocyte phenotype and ensuing outcome on T cells in the settings of cancer and pregnancy.

Methods

Granulocytes from patients treated with recombinant G-CSF, patients with late-stage cancer and women enrolled on a trial of recombinant G-CSF were phenotyped by flow cytometry. The ability and mechanism of polarised granulocytes to suppress T-cell proliferation were assessed by cell proliferation assays, flow cytometry and ELISA.

Results

We observed that G-CSF leads to a significant upregulation of CD14 expression on CD15⁺ granulocytes. These CD15⁺CD14⁺ cells are identified in the blood of patients with patients undergoing neutrophil mobilisation with recombinant G-CSF, and physiologically in women early in pregnancy or in those treated as a part of a clinical trial. Immunohistochemistry of tumor tissue or placental tissue identified the expression of G-CSF. The G-CSF upregulates the release of reactive oxygen species (ROS) in CD15⁺CD14⁺ cells leading to the suppression of T-cell proliferation.

Conclusions

G-CSF induces a population of ROS⁺ immunosuppressive CD15⁺CD14⁺ granulocytes. Strategies for how recombinant G-CSF can be scheduled to reduce effects on T-cell therapies should be developed in future clinical studies.

Neutrophils are mediators of metastatic prostate cancer progression in bone

Bone metastatic prostate cancer (BM-PCa) significantly reduces overall patient survival and is currently incurable. Current standard immunotherapy showed promising results for PCa patients with metastatic, but less advanced, disease (i.e., fewer than 20 bone lesions) suggesting that PCa growth in bone contributes to response to immunotherapy. We found that: (1) PCa stimulates recruitment of neutrophils, the most abundant immune cell in bone, and (2) that neutrophils heavily infiltrate regions of prostate tumor in bone of BM-PCa patients. Based on these findings, we examined the impact of direct neutrophil-prostate cancer interactions on prostate cancer growth. Bone marrow neutrophils directly induced apoptosis of PCa in vitro and in vivo, such that neutrophil depletion in bone metastasis models enhanced BM-PCa growth. Neutrophil-mediated PCa killing was found to be mediated by suppression of STAT5, a transcription factor shown to promote PCa progression. However, as the tumor progressed in bone over time, neutrophils from late-stage bone tumors failed to elicit cytotoxic effector responses to PCa. These findings are the first to demonstrate that bone-resident neutrophils inhibit PCa and that BM-PCa are able to progress via evasion of neutrophil-mediated killing. Enhancing neutrophil cytotoxicity in bone may present a novel therapeutic option for bone metastatic prostate cancer.