Effects of colony-stimulating factors on cellular cytotoxicity

Osteopontin inhibits macrophage nitric oxide synthesis to enhance tumor proliferation

BACKGROUND

Interactions between tumor cells and their host environment can play a major role in regulating survival programs required for tumor progression. Osteopontin (OPN) is a glycophosphoprotein overexpressed by tumors, and is a key molecule for tumor progression and metastasis. OPN also inhibits expression of autocrine and paracrine inducible nitric oxide synthase (iNOS). Given the cytotoxic effects of macrophage NO expression, we hypothesized that tumor-derived OPN inhibits expression of local macrophage iNOS to potentiate tumor survival.

METHODS

We used a coculture system of murine CT26 colorectal cancer cells with RAW264.7 murine macrophage cells. CT26 expresses OPN at high levels. RNA interference was utilized to produce long-term specific silencing of OPN in CT26.

RESULTS

Inhibition of constitutive OPN synthesis in CT26 upregulates local NO production with inhibition of CT26 proliferation and promotion of CT26 apoptosis. Macrophage iNOS expression is accompanied by increased binding activity of nuclear factor-kappaB DNA. When the CT26 culture media were examined for a panel of proinflammatory cytokines, elevated concentrations of granulocyte colony-stimulating factor (G-CSF) were found. Subsequently, in CT26 cells treated with antisense-G-CSF, NO levels in CT26-RAW cocultures were significantly decreased.

CONCLUSION

In our system of CT26-RAW264.7 coculture, we conclude that inhibition of OPN synthesis in CT26 results in G-CSF-mediated induction of macrophage iNOS expression with resultant inhibition of CT26 proliferation via increased apoptosis. Our results suggest that tumor-derived OPN may enhance tumor survival by down regulating expression of NO in the local microenvironment. This is one mechanism by which OPN may potentiate cancer survival and progression.

Sequential activation of NKT cells and NK cells provides effective innate immunotherapy of cancer

The CD1d reactive glycolipid, α-galactosylceramide (α-GalCer), potently activates T cell receptor-α type I invariant NKT cells that secondarily stimulate the proliferation and activation of other leukocytes, including NK cells. Here we report a rational approach to improving the antitumor activity of α-GalCer by using delayed interleukin (IL)-21 treatment to mature the α-GalCer–expanded pool of NK cells into highly cytotoxic effector cells. In a series of experimental and spontaneous metastases models in mice, we demonstrate far superior antitumor activity of the α-GalCer/IL-21 combination above either agent alone. Superior antitumor activity was critically dependent upon the increased perforin-mediated cytolytic activity of NK cells. Transfer of α-GalCer–pulsed dendritic cells (DCs) followed by systemic IL-21 caused an even more significant reduction in established (day 8) metastatic burden and prolonged survival. In addition, this combination prevented chemical carcinogenesis more effectively. Combinations of IL-21 with other NK cell–activating cytokines, such as IL-2 and IL-12, were much less effective in the same experimental metastases models, and these cytokines did not substitute effectively for IL-21 in combination with α-GalCer. Overall, the data suggest that NK cell antitumor function can be enhanced greatly by strategies that are designed to expand and differentiate NK cells via DC activation of NKT cells.

rhG-CSF does not affect the phenotype of adult donor peripheral blood NK cells

Considerable evidence in preclinical models as well as in human transplantation now suggests that donor-derived natural killer (NK) cells can contribute to alloimmune recognition of recipient residual tumour cells. This makes the NK cell population an attractive target for in vitro or in vivo manipulations, in order to improve the antitumour effect of allogeneic transplantation. However, conditions in which allogeneic donor cells are collected vary; several reports have emphasised the different phenotypic and functional properties of T cells derived from marrow, cord blood or mobilised peripheral blood grafts; others have demonstrated different clinical outcomes following blood or marrow transplantation after myeloablative conditioning regimens. NK cells have been examined in this setting; the availability of new tools to study the expression of a variety of surface antigens that are involved in the control of NK cell activity offered us an opportunity to extensively characterise the phenotypic properties of NK cells from donors, before and after administration of pharmacological doses of rhG-CSF used for haematopoietic progenitor mobilisation. Our study suggests that rhG-CSF does not reproducibly alter blood NK cell phenotype in normal individuals, and thus that donor-derived cells are fully equipped to exert their potential antitumour effect.

Mirimostim (macrophage colony-stimulating factor; M-CSF) improves chemotherapy-induced impaired natural killer cell activity, Th1/Th2 balance, and granulocyte function

The purpose of this study was to clarify the effects of mirimostim (macrophage colony-stimulating factor; M-CSF) on immunological functions after chemotherapy. The percentage of natural killer (NK) cells in peripheral blood mononuclear cells (PBMCs), NK cell activity, T-helper cell 1/T-helper cell 2 (Th1/Th2) ratio, and superoxide anion production by granulocytes (granulocyte function) were measured as immunological parameters before and after chemotherapy in 44 patients with primary ovarian cancer who received at least three consecutive courses of postoperative chemotherapy. Patients were observed during the first course of chemotherapy, and 39 patients who presented grade III or IV neutropenia were entered into this study and randomly allocated to an M-CSF-administered group (group 1; 19 patients) and a non-M-CSF-administered group (group 2; 20 patients) for the second course. For the third course, a crossover trial was conducted. In the observation period, chemotherapy significantly impaired the immunological parameters. In particular, those parameters were significantly decreased at day 14 compared to the level before chemotherapy. The values of the parameters of group 1 were significantly higher than those of group 2. In the course of chemotherapy during which M-CSF was administered, 19 of the 39 patients presented grade IV neutropenia, and received granulocyte colony-stimulating factor (G-CSF) between days 7 and 14. We compared the changes of those immunological parameters in the M-CSF alone group and the M-CSF + G-CSF group, and found that the concomitant use of G-CSF did not further improve the parameters. These results indicate that chemotherapy markedly impaired the immunological functions, and that the administration of M-CSF significantly improved the impaired immunological functions.

Changes in cellular immunity during chemotherapy for testicular cancer

BACKGROUND

The changes in vivo in immunocyte functions during chemotherapy that is administered in combination with granulocyte colony-stimulating factor (G-CSF) in humans have not been fully investigated. This study was designed to examine neutrophil functions and the activities of natural killer (NK) cells, during the administration of chemotherapy and G-CSF for the treatment of testicular cancer.

METHODS

Seven patients with germ cell tumors at stage IIA, IIB or IIIB, who were treated with bleomycin, etoposide and cisplatin (BEP), were enrolled in the study. Numbers and activities of neutrophils and NK cells were measured at various times during and after the first course of chemotherapy. Neutrophil phagocytosis was quantitated by flow cytometry with fluorescent latex beads. Bactericidal activity was measured in terms of colony-forming units. The activity of NK cells was measured by monitoring the release of 51Cr.

RESULTS

After BEP chemotherapy, CD16+ and CD56+ cell counts, and neutrophil granulocyte counts decreased while there were no significant changes in the number of lymphocytes. Phagocytosis by neutrophils was enhanced after administration of G-CSF. The activity of NK cells was severely impaired after chemotherapy and did not change after administration of G-CSF.

CONCLUSIONS

After BEP chemotherapy for testicular cancer with G-CSF, neutrophil function was not at all inferior to those before treatment. Natural killer cell activity was suppressed by the BEP chemotherapy and did not change after administration of G-CSF.

A new approach in the management of urothelial tumors using GM-CSF on marker lesions: an ultrastructural and immunohistochemical study on the macrophage population in bladder mucosa

Our purpose was to investigate a new therapeutic model, GM-CSF-targeted immunomodulation on transitional cell carcinoma (TCC) marker lesions and to evaluate the immunologic response of the bladder mucosa. Eleven patients with pTa or pT1 bladder cancer were eligible for the study. All lesions were removed by transurethral resection (TUR) except for a marker lesion. All patients received 8 weekly instillations of 300 microg of GM-CSF, after which cystoscopy with bladder biopsies +/- TUR was repeated on adjacent urothelium or tumor or both. Paraffin-embedded sections were immunohistochemically stained with CD68, which labels monocytes and macrophages. The CD68+ cell population was evaluated as 1+ to 3+. Comparable specimens were routinely processed for ultrastructural analysis. Complete response was observed in 6 patients (55%), persistent tumor occurred in 4 patients (approximately 36.4%), and 1 patient (8.6%) showed recurrence. Immunohistochemically, an at least twofold increase in the number of the CD68+ cells was observed in all responders. Submicroscopically, migration of macrophages to the surface layer occurred. Macrophages showed an extensive lysosomal system and pseudopodia. This study indicates that the prophylactic treatment of TCC with GM-CSF may induce immunomodulatory effects on macrophage activities, which could be associated with the clinical evolution of the disease.

Augmentation of natural killer cell activity in mice by oral administration of transforming growth factor-beta

The latent form of transforming growth factor-beta (TGF-beta) in human milk and platelets was converted to the active form when conscious, pylorus-ligated mice were given human milk and platelets by intragastric intubation. Oral administration of TGF-beta exerted enhancing effects on the natural killer (NK)-cell activities in spleen and liver. Augmentation of NK-cell activities in spleen was observed for 7 days after oral administration of TGF-beta. TGF-beta at concentrations of 5 and 20 ng produced the greatest augmentation of NK-cell activities in spleen. However, NK-cell activities in spleen were unaffected when TGF-beta was given intravenously. Interleukin (IL)-12 production in spleen was enhanced by oral administration of TGF-beta, but not by intravenous administration of TGF-beta. These findings suggest that large amounts of TGF-beta in human milk are involved in early antiviral protection through the augmentation of NK-cell activities.