T-cell apoptosis induced by granulocyte colony-stimulating factor is associated with retinoblastoma protein phosphorylation and reduced expression of cyclin-dependent kinase inhibitors

The effect of rhG-CSF on spleen transcriptome in mouse leukopenia model induced by cyclophosphamide

CONTEXT

RhG-CSF significantly elevates the otherwise reduced numbers of leukocytes following chemotherapy. However, prior work has predominantly focused on the effect of rhG-CSF on the hematopoietic system, and few studies have focused on the immune system.

OBJECTIVE

We aimed to investigate the effect of rhG-CSF on the immune system transcriptome in a mouse leukopenia model that was induced by cyclophosphamide.

MATERIALS AND METHODS

A cyclophosphamide leukopenia model was established in C57BL/6 mice, which were randomly divided into a normal control group (CK), a cyclophosphamide model group (CY) and a rhG-CSF treatment group (rhG-CSF). After 3 d of rhG-CSF treatment, a mouse gene expression microarray enabled evaluation of changes in the transcriptome in the mouse spleen.

RESULTS

About 3552 differentially expressed genes occurred among the three experimental groups, of which 74.9% (2659) concentrated on three gene expression patterns. Gene ontology and pathway analysis of 2659 differential genes showed that early in treatment when leukocyte counts remained low, rhG-CSF recovered the transcription of genes that were related to DNA damage repair and metabolism of nucleotides and amino acids. By contrast, rhG-CSF inhibited the transcription of genes involved in transendothelial migration and endocytosis, and dampened the transcription of genes associated with cell proliferation as compared with the CY group.

CONCLUSIONS

Our study suggests that rhG-CSF recovered metabolism in immune cells, suppressed in vivo immune defense, and attenuated immune cell proliferation in a cyclophosphamide induced leukopenia model. Use of gene expression microarrays can macroscopically and systematically inform the mechanism of rhG-CSF on immune cells.

Indoleamine 2,3-dioxygenase 1 (IDO1) activity correlates with immune system abnormalities in multiple myeloma

Background

Multiple myeloma (MM) is a plasma cell malignancy with a multifaceted immune dysfunction. Indoleamine 2,3-dioxygenase 1 (IDO1) degrades tryptophan into kynurenine (KYN), which inhibits effector T cells and promote regulatory T-cell (Treg) differentiation. It is presently unknown whether MM cells express IDO1 and whether IDO1 activity correlates with immune system impairment.

Methods

We investigated IDO1 expression in 25 consecutive patients with symptomatic MM and in 7 patients with either monoclonal gammopathy of unknown significance (MGUS; n=3) or smoldering MM (SMM; n=4). IDO1-driven tryptophan breakdown was correlated with the release of hepatocyte growth factor (HGF) and with the frequency of Treg cells and NY-ESO-1-specific CD8⁺ T cells.

Results

KYN was increased in 75% of patients with symptomatic MM and correlated with the expansion of CD4⁺CD25⁺FoxP3⁺ Treg cells and the contraction of NY-ESO-1-specific CD8⁺ T cells. In vitro, primary MM cells promoted the differentiation of allogeneic CD4⁺ T cells into bona fide CD4⁺CD25^hiFoxP3^hi Treg cells and suppressed IFN-γ/IL-2 secretion, while preserving IL-4 and IL-10 production. Both Treg expansion and inhibition of Th1 differentiation by MM cells were reverted, at least in part, by d,l-1-methyl-tryptophan, a chemical inhibitor of IDO. Notably, HGF levels were higher within the BM microenvironment of patients with IDO⁺ myeloma disease compared with patients having IDO^- MM. Mechanistically, the antagonism of MET receptor for HGF with SU11274, a MET inhibitor, prevented HGF-induced AKT phosphorylation in MM cells and translated into reduced IDO protein levels and functional activity.

Conclusions

These data suggest that IDO1 expression may contribute to immune suppression in patients with MM and possibly other HGF-producing cancers.

Effects of pegylated G-CSF on immune cell number and function in patients with gynecological malignancies

Background

Pegylated granulocyte colony-stimulating factor (G-CSF; pegfilgrastim) is a longer-acting form of G-CSF, whose effects on dendritic cell (DC) and regulatory T cell (Treg) mobilization, and on the in vivo and ex vivo release of immune modulating cytokines remain unexplored.

Methods

Twelve patients with gynecological cancers received carboplatin/paclitaxel chemotherapy and single-dose pegfilgrastim as prophylaxis of febrile neutropenia. Peripheral blood was collected prior to pegfilgrastim administration (day 0) and on days +7, +11 and +21, to quantify immunoregulatory cytokines and to assess type 1 DC (DC1), type 2 DC (DC2) and Treg cell mobilization. In vitro-differentiated, monocyte-derived DC were used to investigate endocytic activity, expression of DC maturation antigens and ability to activate allogeneic T-cell proliferation.

Results

Pegfilgrastim increased the frequency of circulating DC1 and DC2 precursors. In contrast, CD4⁺FoxP3⁺ bona fide Treg cells were unchanged compared with baseline. Serum levels of hepatocyte growth factor and interleukin (IL)-12p40, but not transforming growth factor-β1 or immune suppressive kynurenines, significantly increased after pegfilgrastim administration. Interestingly, pegfilgrastim fostered in vitro monocytic secretion of IL-12p40 and IL-12p70 when compared with unconjugated G-CSF. Finally, DC populations differentiated in vitro after clinical provision of pegfilgrastim were phenotypically mature, possessed low endocytic activity, and incited a robust T-cell proliferative response.

Conclusions

Pegfilgrastim induced significant changes in immune cell number and function. The enhancement of monocytic IL-12 secretion portends favorable implications for pegfilgrastim administration to patients with cancer, a clinical context where the induction of immune deviation would be highly undesirable.

The effect of rhG-CSF on the conformation of LFA-1 on CD4+ T cells in hemopoietic stem cell transplantation

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) modulates donor T cell function in hemopoietic stem cell transplantation. The effects of rhG-CSF on the activation of CD4(+) T cells have been poorly investigated. We investigated whether rhG-CSF mobilization influenced the activation and proliferation capacity of CD4(+) T cells. Cell treatment with phorbol 12-myristate 13-acetate (PMA) plus ionomycin or the CD3 mAb OKT3 plus intercellular cell adhesion molecule-1 (ICAM-1) at 37 degrees C for 6 h induced a dramatic increase in CD25, CD69 and MEM148 epitope exposure. rhG-CSF mobilization decreased CD25, CD69 and MEM148 epitope expression on activated CD4(+) T cells compared with cells before mobilization. The transcription factor Jun activation domain-binding protein 1 (JAB1) plays a role in the activation of CD4(+) T cells, and the rhG-CSF mobilization changed the level of nuclear JAB1 protein. rhG-CSF mobilization also decreased the adhesion of CD4(+) T cells to ICAM-1, but had no effect on the levels of donor CD4+CD25+ regulatory T cells. Overall, these data suggest the rhG-CSF mobilization can influence CD4(+) T cell activation through LFA-1/ICAM-1 costimulatory signaling in HSC transplantation.

Granulocyte colony-stimulating factor treatment in chronic Chagas disease: preservation and improvement of cardiac structure and function

This study investigates the effects of granulocyte colony-stimulating factor (G-CSF) therapy in experimental chronic chagasic cardiomyopathy. Chagas disease is one of the leading causes of heart failure in Latin America and remains without an effective treatment other than cardiac transplantation. C57BL/6 mice were infected with 10(3) trypomastigotes of Trypanosoma cruzi, and chronic chagasic mice were treated with G-CSF or saline (control). Evaluations following treatment were functional, immunological, and histopathological. Comparing hearts of G-CSF-treated mice showed reduced inflammation and fibrosis compared to saline-treated chagasic mice. G-CSF treatment did not alter the parasite load but caused an increase in the number of apoptotic inflammatory cells in the heart. Cardiac conductance disturbances in all infected animals improved or remained stable due to the G-CSF treatment, whereas all of the saline-treated mice deteriorated. The distance run on a treadmill and the exercise time were significantly greater in G-CSF-treated mice when compared to chagasic controls, as well as oxygen consumption (VO(2)), carbon dioxide production (VCO(2)), and respiratory exchange ration (RER) during exercise. Administration of G-CSF in experimental cardiac ischemia had beneficial effects on cardiac structure, which were well correlated with improvements in cardiac function and whole animal performance.

Function and dysfunction of dendritic cells in autoimmune rheumatic diseases

Dendritic cells (DC) have been implicated both in initiation of immunity and in immune tolerance. The mechanisms whereby tolerogenic DC may induce and maintain peripheral tolerance include the generation or expansion of regulatory T cells (Treg) and the promotion of T-cell anergy or deletion. A wide spectrum of hematopoietic growth factors and cytokines are endowed with the ability to differentiate tolerogenic DC both in vitro and in vivo. Based on this knowledge, therapeutic vaccination with cytokine-modulated tolerogenic DC has been applied to animal models of autoimmune disorders. This article will review the current experimental evidence underpinning DC dysfunction in rheumatic autoimmune diseases and will discuss how the manipulation of DC and Treg number and function may control undesired T-cell responses.

Granulocyte colony-stimulating factor for the induction of T-cell tolerance

In recent years, investigators have unraveled a previously unrecognized role for granulocyte colony-stimulating factor (G-CSF) in the regulation of T-cell and dendritic cell functions. The experimental evidence in favor of G-CSF-mediated immune regulation includes the ability to skew T-cell cytokine secretion to T-helper type 2 responses, and to promote regulatory T-cell and tolerogenic dendritic cell differentiation. Accordingly, beneficial effects of G-CSF have been detected in animal models of immune-mediated diseases, including posttransplantation graft-versus-host disease, experimental autoimmune encephalomyelitis, lupus nephritis, inflammatory bowel disease, and diabetes. The growing body of evidence supporting a novel role for G-CSF in the induction of T-cell tolerance is reviewed herein.

Granulocyte colony-stimulating factor: a novel mediator of T cell tolerance

In recent years, several investigators have unraveled a previously unrecognized role for G-CSF in the regulation of T cell and dendritic cell functions. The experimental evidence in favor of G-CSF-mediated immune regulation includes the ability to switch T cell cytokine secretion profile to Th2 responses and the promotion of regulatory T cell and tolerogenic dendritic cell differentiation. Interestingly, G-CSF is beneficial in animals for the prevention and/or treatment of immune-mediated diseases, e.g., graft-vs-host disease, multiple sclerosis, systemic lupus erythematosus, inflammatory bowel disease, and diabetes, suggesting a potential role in human autoimmune diseases. This review summarizes the growing body of evidence that supports a critical role for G-CSF as a novel mediator of T cell tolerance.

Granulocyte colony-stimulating factor enhances the in vitro cytotoxicity of gemtuzumab ozogamicin against acute myeloid leukemia cell lines and primary blast cells

OBJECTIVE

To evaluate the effects of granulocyte colony-stimulating factor (G-CSF) on the in vitro sensitivity of acute myeloid leukemia (AML) cell lines and primary AML blast cells to gemtuzumab ozogamicin (GO).

MATERIALS AND METHODS

AML cell lines and primary blasts from 10 patients with AML were first incubated for 72 hours in the presence of G-CSF (5 or 100 ng/mL) and then exposed to increasing concentrations of GO (1-1,000 ng/mL) for an additional 72 hours.

RESULTS

Pretreatment with G-CSF translated into significant enhancement of GO-induced cytotoxicity in the GO-sensitive HL-60 and NB-4 cells. Conversely, the response of GO-insensitive KG-1a, TF-1, and K562 cells was unaffected by in vitro priming with G-CSF. In vitro exposure to G-CSF augmented GO-induced apoptosis in 7 of 10 primary AML samples and rendered blast cells from three refractory patients sensitive to killing effect of GO. The G-CSF-induced increase of the cytocidal activity of GO was independent of effects on the cell cycle and on the expression levels of CD33 antigen. Of potential interest, G-CSF induced dose-dependent inhibition of P-glycoprotein (P-gp/ABCB1) function in the GO-sensitive HL-60 and NB-4 cells and in blasts from three patients with AML that we tested.

CONCLUSION

Collectively, our findings point to G-CSF as a potential sensitizing agent that can be exploited therapeutically to improve the clinical efficacy of GO.

Accelerated recovery of 5-fluorouracil-damaged bone marrow after rosiglitazone treatment

Our preliminary data indicate that rosiglitazone may be myeloprotective. We investigated whether it can modify bone marrow recovery. Five-day pre-treatment with rosiglitazone significantly accelerated recovery of 5-fluorouracil-damaged bone marrow in mice. Frequency and femoral content of granulocyte-macrophage progenitors reached mean baseline faster in pre-treated groups than in 5-fluorouracil-treated controls. Consequently, neutropenia was milder. Five-day insulin pre-treatment had similar effects in vivo. Insulin supports in vitro hematopoiesis. The observed myeloprotection demonstrated the importance of insulin in vivo. Clinical use of insulin to moderate myelotoxicity is impractical but rosiglitazone, an insulin sensitizer, could offer hope. Although rosiglitazone tends to increase plasma insulin levels, the significant myeloprotection was partly due to direct effects on progenitors. In vitro rosiglitazone enhanced the survival of both murine progenitor and human mobilized blood stem cells in the presence of 5-fluorouracil, the effect of which was neutralized by a peroxisome-proliferator-activated receptor-gamma antagonist.

A comparison of the action of amifostine and melatonin on DNA-damaging effects and apoptosis induced by idarubicin in normal and cancer cells

Amifostine is a well-known cell protector and its actions involve free radical scavenging, which is also considered as a mechanism underlying the protective actions of melatonin, a secretory product of the pineal gland. In this work we compared the action of 14 mM amifostine and 50 microM melatonin on DNA damage and apoptosis induced by idarubicin in normal human lymphocytes, leukemic K562 cells and HeLa cancer cells. We employed the alkaline comet assay and pulse-field gel electrophoresis to estimate DNA damage. Apoptosis was evaluated by caspase 3 activity assay assisted by the comet assay to evaluate DNA fragmentation and DAPI staining for detection of morphological changes in chromatin. We found that idarubicin induced apoptosis in normal and cancer cells and its level was correlated with the extent of DNA strand breaks. Amifostine reduced apoptosis and DNA damage in normal cells, but it potentiated these effects in cancer cells in this in vitro study. Melatonin protected both normal and cancer cells against genotoxic treatment and apoptosis induced by idarubicin. We conclude that despite its recognized potential as an antioxidant, melatonin should be considered with caution when used in combination with cancer chemotherapy agents, especially in the case of leukemias.

Regulatory T cells and tolerogenic dendritic cells: from basic biology to clinical applications

The induction of antigen (Ag)-specific tolerance is critical for the prevention of autoimmunity and maintenance of immune homeostasis. Recently, attention has been focused on induction of active suppression by regulatory T cells (Treg cells). Also, a role for dendritic cells (DCs) in the promotion of peripheral tolerance has been demonstrated by several studies and is the subject of intensive investigation. It is currently believed that the maturation/activation state of DCs might be a control point for the induction of peripheral tolerance through modifications of the activation state of T cells. Several lines of experimental evidence suggest that unique DC subsets or discrete functional states of the DCs might be devoted to the promotion of Treg cell differentiation. The present review summarizes the emerging literature on the developmental origin and function of human Treg cells and tolerogenic/regulatory DCs. Furthermore, clinical implications of these studies for cellular therapy of immune-mediated pathologies are discussed.

Role for granulocyte colony-stimulating factor in the generation of human T regulatory type 1 cells

Granulocyte colony-stimulating factor (G-CSF) may affect T-cell homeostasis by multiple mechanisms, inducing polarization of cytokine secretion, inhibition of T-cell proliferation, and enhancement of T-cell apoptosis. We analyzed the production of interleukin-10 (IL-10) and transforming growth factor-beta1 (TGF-beta1) by T cells from healthy volunteer donors treated with recombinant human G-CSF. Highly purified CD4(+) T cells obtained before and after G-CSF administration (pre-G and post-G, respectively) were activated using the allogeneic mixed leukocyte reaction. Post-G CD4(+) T cells produced high levels of IL-10 but undetectable levels of IL-2 and IL-4, whereas the level of TGF-beta1 release was comparable to that of pre-G CD4(+) T cells. Notably, post-G CD4(+) T cells proliferated poorly in response to alloantigens and to recall antigens and suppressed the proliferation of autologous CD4(+) T cells in a cell contact-independent and an antigen-nonspecific manner. TGF-beta1 and IL-10 were not dispensable for post-G CD4(+) T cells to mediate suppression, as shown by neutralization studies. Compared with pre-G CD4(+) T cells, alloantigen-activated post-G CD4(+) T cells preferentially expressed markers associated with memory T cells, in conjunction with reduced levels of CD28 and CD62L. Collectively, these data demonstrate that CD4(+) T cells exposed to G-CSF in vivo acquire the properties of T regulatory (Tr) cells once triggered in vitro through the T-cell receptor, including a peculiar cytokine production profile (IL-10(++)TGF-beta1(+)IL-2(low/-)IL-4(low/-)), an intrinsic low proliferative capacity, and a contact-independent suppression of antigen-driven proliferation. Tr cells generated ex vivo after exposure to G-CSF might be clinically relevant for transplantation medicine and for the treatment of human immune-mediated diseases.