Protective effect of recombinant murine granulocyte-macrophage colony-stimulating factor against Pseudomonas aeruginosa infection in leukocytopenic mice

Reversal of chemotherapy-induced leukopenia using granulocyte macrophage colony-stimulating factor promotes bone metastasis that can be blocked with osteoclast inhibitors

Hematopoietic growth factors are used to reverse chemotherapy-induced leukopenia. However, some factors such as granulocyte macrophage colony-stimulating factor (GM-CSF) induce osteoclast-mediated bone resorption that can promote cancer growth in the bone. Accordingly, we evaluated the ability of GM-CSF to promote bone metastases of breast cancer or prostate cancer in a mouse model of chemotherapy-induced leukopenia. In this model, GM-CSF reversed cyclophosphamide-induced leukopenia but also promoted breast cancer and prostate cancer growth in the bone but not in soft tissue sites. Bone growth was associated with the induction of osteoclastogenesis, yet in the absence of tumor GM-CSF, it did not affect osteoclastogenesis. Two osteoclast inhibitors, the bisphosphonate zoledronic acid and the RANKL inhibitor osteoprotegerin, each blocked GM-CSF-induced tumor growth in the bone but did not reverse the ability of GM-CSF to reverse chemotherapy-induced leukopenia. Our findings indicate that it is possible to dissociate the bone-resorptive effects of GM-CSF, to reduce metastatic risk, from the benefits of this growth factor in reversing leukopenia caused by treatment with chemotherapy.

G- and GM-CSF in oncology and oncological haematology

Administration of G- and GM-CSF increases the neutrophil counts in a number of clinical situations. GM-CSF shows the additional effect of increasing the number of monocytes and eosinophil granulocytes. Both G- and GM-CSF affect of neutrophil functions, in the case of GM-CSF there are some potentially negative effects on neutrophil migration and adhesiveness. The clinical relevance of the various effects on mature haematopoietic cells is not fully understood. Clinical data with G-CSF treatment indicate that increased levels of neutrophil granulocytes following cytotoxic chemotherapy may translate into clinical benefit such as a decreased rate of neutropenic infection and an increased cytotoxic chemotherapy dose even though the data are conflicting and the risk of "laboratory cosmetics" is apparent. Regarding treatment with GM-CSF following chemotherapy, the clinical benefit is unclear. The clinical benefit of GM-CSF-induced monocytes and eosinophils is unknown. G- and GM-CSF accelerates neutrophil recovery following autologous or allogeneic BMT. The influence on neutropenic infections is, however, less impressive. Pretreatment with G- or GM-CSF increases the yield of peripheral stem cell harvest, thereby reducing the number of leukaphereses needed. Transplantation of G- and GM-CSF primed autologous peripheral stem cells tends to reduce the period of post-transplant cytopenia, particularly thrombocytopenia, in comparison with traditional ABMT. In patients with MDS, G- and GM-CSF appear to increase the number of neutrophil granulocytes and there is some evidence that patients with severe infectious problems will benefit from this treatment. However, little influence was seen on the main clinical problems with these patients, which are anaemia and thrombocytopenia. In conclusion, G- and GM-CSF are two different proteins with different properties in vivo and in vitro. GM-CSF has, compared with G-CSF, more complex pharmacological effects and a more trouble-some side-effect profile. Early clinical development indicates that both compounds have a substantial influence on the levels of certain blood cells. Whether the increases in different blood cells translate into long-term clinical benefit for greater patient groups is the focus of ongoing research. The effects of G- and GM-CSF may be potentiated by other cytokines, an area which is presently being explored.

Effect of Granulocyte-Monocyte Colony-Stimulating Factor Therapy on Leukocyte Function and Clearance of Serious Infection in Nonneutropenic Patients

STUDY OBJECTIVE

Impaired leukocyte function in patients with serious infections may increase mortality. Granulocyte-monocyte colony-stimulating factor (GM-CSF) broadly activates peripheral monocytes and neutrophils. We performed a clinical trial of GM-CSF in septic, hemodynamically stable patients to see whether GM-CSF treatment improved leukocyte function and mortality.

DESIGN

Randomized, unblinded, placebo-controlled, prospective study.

SETTING

A 600-bed academic tertiary care center with a 120-bed ICU census with a high proportion of immunocompromised, solid-organ transplant recipients.

PATIENTS

Forty adult patients with infections meeting the criteria for the systemic inflammatory response syndrome but without hemodynamic instability or shock.

INTERVENTIONS

Patients with sepsis and a documented infection were randomized to a 72-h infusion of GM-CSF (125 microg/m2) or placebo.

MEASUREMENTS AND MAIN RESULTS

GM-CSF infusion caused the up-regulation of the beta2-integrin adhesion molecule CD11b and the appearance of the activated ("sticky" or "avid") form of the molecule on circulating neutrophils and monocytes. CD11b density and avidity increases in response to the administration of tumor necrosis factor-alpha were blunted prior to treatment in these patients with serious infection. GM-CSF partially repaired this blunted response on both monocytes and neutrophils. It also caused the down-regulation of the adhesion molecule L-selectin on neutrophils and the up-regulation of human leukocyte antigen on monocytes. These changes were consistent with a broad activation of the circulating leukocyte pool. Although mortality and organ failure scores were similar in both groups, infection resolved significantly more often in patients receiving GM-CSF.

CONCLUSIONS

GM-CSF infusion up-regulated the functional markers of inflammation on circulating neutrophils and monocytes and was associated with both the clinical and microbiological resolution of infection. There was no detectable exacerbation of sepsis-related organ failure or other deleterious side effects with the administration of this proinflammatory agent to patients with serious infections.

Transgenic mice showing inflammation-inducible overexpression of granulocyte macrophage colony-stimulating factor

We used the promoter of the human C-reactive protein (CRP) gene to drive inflammation-inducible overexpression of the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) in transgenic mice. Transgenic mice carrying a CRP/GM-CSF fusion gene show a >150-fold increases in circulating levels of GM-CSF within 6 h of intraperitoneal inoculation with 25 microg of lipopolysaccharide. However, some of the transgenic mice also display relatively high basal levels of GM-CSF in the absence of any obvious inflammatory stimulus. Raised basal levels of GM-CSF are associated with a number of pathological changes, including enlarged and histologically abnormal livers and spleens and with increases in the number and activation state of macrophages and granulocytes in the peripheral blood. Despite problems associated with the expression of such a potent pleiotropic cytokine as GM-CSF, the principle of inflammation-inducible expression of chimeric constructs has been shown to be feasible. Inducible expression systems such as that described here could be of potential use in the study of the role of cytokines in health and disease and in the development of disease-resistant strains of livestock.

Selective early production of CCL20, or macrophage inflammatory protein 3alpha, by human mast cells in response to Pseudomonas aeruginosa

Mast cells are important as sentinel cells in host defense against bacterial infection. Much of their effectiveness depends upon recruiting other immune cells; however, little is known about the mechanisms of this response. CCL20, also known as macrophage inflammatory protein-3alpha (MIP-3alpha), Exodus, and LARC, is a chemokine known to be a potent chemoattractant for immature dendritic cells and T cells. In this study, we examined the human mast cell production of both CCL20 and granulocyte-macrophage colony-stimulating factor (GM-CSF), a critical cytokine for innate immune responses in the lung, in response to Pseudomonas aeruginosa. Reverse transcription-PCR and Western blot analysis demonstrated that the human mast cells (HMC-1) express CCL20 mRNA and are able to produce a significant amount (32.4 ng/ml) of CCL20 protein following stimulation by calcium ionophore and phorbol myristate acetate. Importantly, P. aeruginosa potently stimulated CCL20 production in human cord blood-derived mast cells (CBMC), with production peaking at 6 h after stimulation. This time course of expression was distinct from that of GM-CSF, which peaked after 24 to 48 h. Significant CCL20 production did not occur following immunoglobulin E-mediated activation of CBMC under conditions which induced a substantial GM-CSF response. Interestingly, the CCL20 response of mast cells to P. aeruginosa was relatively resistant to inhibition by the corticosteroid dexamethasone, interleukin-10, or cyclosporine, while GM-CSF production was potently inhibited. However, P. aeruginosa-induced CCL20 production was blocked by the protein kinase C (PKC) inhibitor Ro 31-8220 and a PKC pseudosubstrate. These results support a role for human mast cells in the initiation of immune responses to P. aeruginosa infection.

Accelerated recovery from cyclophosphamide-induced leukopenia in mice administered a Japanese ethical herbal drug, Hochu-ekki-to

The effect of a Japanese ethical herbal drug, Hochu-ekki-to (HOT), on recovery from leukopenia induced by cyclophosphamide (CY) was investigated. Daily oral administration of 1000 mg/kg HOT into CY-treated mice significantly prevented decrease of leukocyte numbers in the peripheral blood and accelerated recovery from leukopenia. Ginsenoside Rgl extracted from Ginseng radix, a major herb of HOT, was one of the active ingredients. HOT increased numbers of neutrophils and monocytes in the peripheral blood compared with CY-treated control. Moreover, HOT augmented the resistance against Pseudomonas aeruginosa infection. The number of colony-forming units in the spleen (CFU-S) also increased in HOT-treated mice. The frequencies of IL-3-, GM-CSF- and IFN-gamma-producing cells increased in the spleen, bone marrow, liver and IEL on HOT treatment, and HOT clearly augmented the expressions of IL-3, GM-CSF and IFN-gamma mRNA in the spleen, bone marrow, liver and IEL except IL-3 and IFN-gamma mRNA in the IEL. These results suggest that HOT enhances the production of hematopoietic lymphokines, stimulates the proliferation of hematopoietic progenitor cells and consequently accelerates recovery from leukopenia in CY-treated mice. Additionally, IFN-gamma which HOT-augmented the production may contribute the protective effect against the bacterial infection by activating of phagocyte cells.

Effect of granulocyte-macrophage colony-stimulating factor on the number of leucocytes and course of Listeria monocytogenes infection in naive and leucocytopenic mice

This study concerns the effect of recombinant murine granulocyte-macrophage colony-stimulating factor (GM-CSF) on the number of circulating leucocytes, activation of peritoneal macrophages and proliferation of Listeria monocytogenes in various organs of naive and leucocytopenic mice. Mice were rendered leucocytopenic by sublethal total body irradiation or cyclophosphamide treatment. GM-CSF treatment enhanced the number of granulocytes and monocytes in peripheral blood during L. monocytogenes infection in naive mice, but not in irradiated or cyclophosphamide-treated mice. In naive mice, irradiated and cyclophosphamide-treated mice, GM-CSF did not affect the course of L. monocytogenes infection in thigh muscle, spleen and liver. However, GM-CSF treatment significantly increased the number of macrophages in the peritoneal cavity of naive mice during infection; these macrophages were more enlarged and showed a higher frequency of binucleated and multinucleated cells relative to non-GM-CSF-treated mice. Together, these results demonstrated that GM-CSF increased the number of circulating granulocytes and monocytes, and the number of peritoneal macrophages during infection with L. monocytogenes in naive mice, but did not affect the course of the infection in thigh muscle, spleen or liver of these mice. In leucocytopenic mice, however, GM-CSF did not affect the number of circulating phagocytes, which explains that this factor had no effect on the proliferation of the bacteria in the various organs.

Cytokines in the treatment of fungal infections

The incidence of invasive fungal infections in the immunocompromized host has increased during the past decade. Even the recently developed antifungal drugs are unable to cure these infections in patients with severely impaired host defense mechanisms. Cytokines have great potential to augment host resistance and as adjunctive therapy of invasive mycoses. We discuss the mechanisms of host defense against invasive candidiasis, aspergillosis, and cryptococcosis, and review the use of cytokines and growth factors in this setting. Interleukin-1 has been shown effective in an animal model of disseminated candidiasis, even during severe granulocytopenia. Interferon-gamma has been very effective as a modulator of resistance against a variety of fungal infections in vitro. The effect of interferon-gamma against disseminated candidiasis has been demonstrated in a mouse model. Activation of neutrophils is the main mechanism by which interferon-gamma enhances the elimination of Candida, and consequently the agent is not effective in severely granulocytopenic animals. Data on the role of colony-stimulating factors against fungal pathogens are accumulating, and trials with these agents for hematologic patients with invasive fungal infections are now being performed.

Granulocyte macrophage colony-stimulating factor improves survival in two models of gut-derived sepsis by improving gut barrier function and modulating bacterial clearance

OBJECTIVE

The effect of recombinant murine granulocyte macrophage colony-stimulating factor (rmGM-CSF) on survival and host defense was studied using two clinically relevant models of infection that included transfusion-induced immunosuppression.

SUMMARY BACKGROUND DATA

Granulocyte macrophage colony-stimulating factor improves resistance in several models of infection, but its role in transfusion-induced immunosuppression and bacterial translocation (gut-derived sepsis) has not been defined.

METHODS

Balb/c mice were treated with 100 ng of rmGM-CSF or placebo for 6 days in a model of transfusion, burn, and gavage, or cecal ligation and puncture (CLP). Translocation was studied in the first model.

RESULTS

Survival after transfusion, burn, and gavage was 90% in rmGM-CSF-treated animals versus 35% in the control group (p < 0.001). After CLP, survival was 75% in the rmGM-CSF group versus 30% in the control group (p = 0.01). Less translocation and better killing of bacteria was observed in the tissues in animals treated with rmGM-CSF.

CONCLUSION

The ability of rmGM-CSF to improve gut barrier function and enhance killing of translocated organisms after burn injury-induced gut origin sepsis was associated with improved outcome. Granulocyte macrophage colony-stimulating factor also improved survival after CLP.

Peptides related to the carboxyl terminus of human platelet factor IV with antibacterial activity

A peptide (C13) corresponding to the last 13 amino acids of the carboxyl terminus of human platelet factor IV was found to be antibacterial. Amino acid substitutions predicted to disrupt either the amphipathic or alpha-helical nature of C13 rendered the peptide inactive. Antibacterial activity was demonstrated in normal human serum on bacteria which had been previously exposed to low levels of cefepime, a beta-lactam antibiotic. Peptide analogues were examined for more potent antibacterial activity in an antibacterial assay that employed normal human serum and low levels of cefepime. A peptide analogue (C18G) with 80-fold more antibacterial activity than C13 was identified. Studies in C8-deficient sera confirmed an essential role of human serum complement for optimal antibacterial activity. Additional studies showed low levels of cefepime, although not essential, enhanced the antibacterial activity of C18G. Animal protection experiments demonstrated that either peptide C18G or an analogue with all D amino acids (C18X) significantly increased the survival of neutropenic mice when coadministered with a low level of cefepime. This work has resulted in the identification of a new group of antibacterial peptides.

The effects of recombinant human granulocyte-macrophage colony-stimulating factor on the induction of lymphokine-activated killer cells in vitro

Granulocyte-macrophage colony-stimulating factor (GM-CSF) was added to a culture of human peripheral blood mononuclear cells in the presence of interleukin 2 (IL-2) in vitro to elucidate its effect on the induction of lymphokine-activated killer (LAK) cells. Viable cell counts of cultured cells and their cytotoxic effects against natural killer (NK) cell-resistant Daudi cells and NK cell-sensitive K562 cells were measured using the trypan blue dye exclusion test and a 51Cr release assay from the tumor cells, respectively. Although GM-CSF alone did not influence either the cytotoxicities or the surface phenotypes of the cultured cells, the viable cell counts were significantly increased by the addition of GM-CSF in the presence of IL-2 (P less than 0.01). These findings indicate that the addition of GM-CSF in the presence of IL-2 during the induction of LAK cells is useful for obtaining a larger number of effector cells which possess substantial cytotoxic activity.

A traditional Chinese herbal medicine, ren-shen-yang-rong-tang (Japanese name: ninjin-yoei-to) augments the production of granulocyte-macrophage colony-stimulating factor from human peripheral blood mononuclear cells in vitro

Ren-shen-yang-rong-tang (Japanese name: Ninjin-yoei-to, NYT) is a traditional Chinese herbal medicine. Leukocytosis and elevated levels of colony-stimulating factor (CSF) in peripheral blood were found previously after the administration of this compound to mice. In this study, human peripheral blood mononuclear cells (PBMC) were cultured in the presence of NYT in vitro, and the levels of granulocyte-macrophage CSF (GM-CSF) and granulocyte CSF (G-CSF) in the supernatant of cultured PBMC were measured using a sensitive enzyme-linked immunosorbent assays. NYT significantly (P less than 0.01) augmented GM-CSF production but not G-CSF production by PBMC in vitro.

Colony-stimulating factors

Recombinant hematopoietic colony-stimulating factors have profound effects on developing and mature granulocytes, macrophages, and lymphocytes. Use of these agents for treatment of disease may result in a variety of adverse cutaneous reactions. The recent discovery of colony-stimulating factor production by keratinocytes and dermal cells suggests that these agents may also be significant in cutaneous homeostasis and in the pathogenesis of cutaneous diseases.

Antibacterial resistance induced by recombinant interleukin 1 in myelosuppressed mice: effect of treatment schedule and correlation with colony-stimulating activity in the bloodstream

We have investigated the effects of interleukin 1 (IL-1) administration on the ability of neutropenic mice to resist Pseudomonas aeruginosa challenge in vivo. Cyclophosphamide-treated mice received human rIL-1 beta at 7.0, 0.7, or 00.7 micrograms/kg, according to different regimens, to be challenged with a lethal ip inoculum of pseudomonas cells 5 days after myelosuppression. The repeated exposure of the neutropenic mice to an overall cytokine dosage of 7.0 or 0.7 micrograms/kg during the 4 days after myelosuppression was found to optimally restore the animals' antibacterial resistance. However, when administered as a single injection 24 hr before challenge, the same dosages of IL-1 had lower or no effect in enhancing survival, primarily leading only to a reduction in the amount of antipseudomonal chemotherapy required for cure. The regimen of IL-1 administration conferring optimal protection also resulted in a decrease in the number of pseudomonas cells recovered from the peritoneal cavity of infected mice. This regimen accelerated hematopoietic recovery in cyclophosphamide-treated mice. Assay of serum colony-stimulating activity (CSA) revealed that (a) cyclophosphamide treatment alone significantly increased the level of circulating CSA, (b) administration of a single dose of IL-1 to neutropenic mice induced an early, further increase in serum CSA, followed by depression, (c) a biphasic pattern of CSA response was also evident in mice repeatedly treated with IL-1. These results suggest that regulation of hematopoiesis may have an important role in the induction of antibacterial resistance in myelosuppressed hosts repeatedly treated with low dosages of IL-1.

Muroctasin [MDP-Lys(18)] augments the production of granulocyte colony-stimulating factor (G-CSF) from human peripheral blood mononuclear cells in vitro

N2-[(N-acetylmuramoyl)-L-alanyl-D-isoglutaminyl]-N6-stearoyl-L-Lysine (MDP-Lys(L18), muroctasin) is an immunopotentiating substance. Neutrophilia and elevated levels of colony-stimulating factor (CSF) in peripheral blood were previously found after the administration of this compound in both mice and humans. To specify the type of CSF and to elucidate the mechanisms of the neutrophilia, we cultured human peripheral blood mononuclear cells (PBMC) in the presence of muroctasin and measured the levels of granulocyte CSF (G-CSF) in the culture supernatants using our sensitive enzyme-linked immunosorbent assay. G-CSF is an active hematopoietic growth factor specific for cells of a neutrophilic lineage, and muroctasin was found to significantly augment the G-CSF production from PBMC in vitro (P less than 0.01). Furthermore, production of G-CSF from human PBMC in the presence of muroctasin was also supported by the Northern blot analysis using cDNA encoding G-CSF as a probe.