Administration Of Macrophage Colony-stimulating Factor Research Articles

Human CD56+CD39+ dNK cells support fetal survival through controlling trophoblastic cell fate: immune mechanisms of recurrent early pregnancy loss.

Decidual natural killer (dNK) cells are the most abundant immune cells at the maternal-fetal interface during early pregnancy in both mice and humans, and emerging single-cell transcriptomic studies have uncovered various human dNK subsets that are disrupted in patients experiencing recurrent early pregnancy loss (RPL) at early gestational stage, suggesting a connection between abnormal proportions or characteristics of dNK subsets and RPL pathogenesis. However, the functional mechanisms underlying this association remain unclear. Here, we established a mouse model by adoptively transferring human dNK cells into pregnant NOG (NOD/Shi-scid/IL-2Rγnull) mice, where human dNK cells predominantly homed into the uteri of recipients. Using this model, we observed a strong correlation between the properties of human dNK cells and pregnancy outcome. The transfer of dNK cells from RPL patients (dNK-RPL) remarkably worsened early pregnancy loss and impaired placental trophoblast cell differentiation in the recipients. These adverse effects were effectively reversed by transferring CD56+CD39+ dNK cells. Mechanistic studies revealed that CD56+CD39+ dNK subset facilitates early differentiation of mouse trophoblast stem cells (mTSCs) towards both invasive and syncytial pathways through secreting macrophage colony-stimulating factor (M-CSF). Administration of recombinant M-CSF to NOG mice transferred with dNK-RPL efficiently rescued the exacerbated pregnancy outcomes and fetal/placental development. Collectively, this study established a novel humanized mouse model featuring functional human dNK cells homing into the uteri of recipients and uncovered the pivotal role of M-CSF in fetal-supporting function of CD56+CD39+ dNK cells during early pregnancy, highlighting that M-CSF may be a previously unappreciated therapeutic target for intervening RPL.

Macrophage colony-stimulating factor induces prolactin expression in rat pituitary gland.

We investigated the role of macrophage colony-stimulating factor (M-CSF) in the pituitary gland to understand the effect of M-CSF on pituitary hormones and the relationship between the endocrine and immune systems. When we attempted to establish pituitary cell lines from a thyrotropic pituitary tumor (TtT), a macrophage cell line, TtT/M-87, was established. We evaluated M-CSF-like activity in conditioned media (CM) from seven pituitary cell lines using TtT/M-87 cells. TtT/M-87 proliferation significantly increased in the presence of CM from TtT/GF cells, a pituitary folliculostellate (FS) cell line. M-CSF mRNA was detected in TtT/GF and MtT/E cells by reverse transcriptase-polymerase chain reaction (RT-PCR), and its expression in TtT/GF cells was increased in a lipopolysaccharide (LPS) dose-dependent manner. M-CSF mRNA expression was also increased in rat anterior pituitary glands by LPS. M-CSF receptor (M-CSFR) mRNA was only detected in TtT/ M-87 cells and increased in the LPS-stimulated rat pituitary glands. In rat pituitary glands, M-CSF and M-CSFR were found to be localized in FS cells and prolactin (PRL)-secreting cells, respectively, by immunohistochemistry. The PRL concentration in rat sera was significantly increased at 24 h after M-CSF administration, and mRNA levels significantly increased in primary culture cells of rat anterior pituitary glands. In addition, TNF-α mRNA was increased in the primary culture cells by M-CSF. These results revealed that M-CSF was secreted from FS cells and M-CSF regulated PRL expression in rat pituitary glands.

Macrophage colony-stimulating factor and its receptor signaling augment glycated albumin-induced retinal microglial inflammation in vitro

BackgroundMicroglial activation and the proinflammatory response are controlled by a complex regulatory network. Among the various candidates, macrophage colony-stimulating factor (M-CSF) is considered an important cytokine. The up-regulation of M-CSF and its receptor CSF-1R has been reported in brain disease, as well as in diabetic complications; however, the mechanism is unclear. An elevated level of glycated albumin (GA) is a characteristic of diabetes; thus, it may be involved in monocyte/macrophage-associated diabetic complications.ResultsThe basal level of expression of M-CSF/CSF-1R was examined in retinal microglial cells in vitro. Immunofluorescence, real-time PCR, immunoprecipitation, and Western blot analyses revealed the up-regulation of CSF-1R in GA-treated microglial cells. We also detected increased expression and release of M-CSF, suggesting that the cytokine is produced by activated microglia via autocrine signaling. Using an enzyme-linked immunosorbent assay, we found that GA affects microglial activation by stimulating the release of tumor necrosis factor-α and interleukin-1β. Furthermore, the neutralization of M-CSF or CSF-1R with antibodies suppressed the proinflammatory response. Conversely, this proinflammatory response was augmented by the administration of M-CSF.ConclusionsWe conclude that GA induces microglial activation via the release of proinflammatory cytokines, which may contribute to the inflammatory pathogenesis of diabetic retinopathy. The increased microglial expression of M-CSF/CSF-1R not only is a response to microglial activation in diabetic retinopathy but also augments the microglial inflammation responsible for the diabetic microenvironment.

Macrophage colony stimulating factor (M-CSF) exacerbates ALS disease in a mouse model through altered responses of microglia expressing mutant superoxide dismutase

Macrophage colony stimulating factor (M-CSF) is a cytokine that regulates the survival, proliferation and maturation of microglial cells. Administration of M-CSF can promote neuronal survival in various models of central nervous system (CNS) injury. Here, in an attempt to induce a neuroprotective microglial cell phenotype and enhance motor neuron survival, mutant SOD1 G37R transgenic mice were treated, weekly, with M-CSF starting at onset of disease. Unexpectedly, M-CSF accelerated disease progression in SOD1 G37R mouse model of ALS. The shortened survival of M-CSF-treated animals was associated with diminished muscle innervation and enhanced adoption of a macrophage-like phenotype by microglial cells characterised by the upregulation of pro-inflammatory cytokines TNF-α and IL-1β and of the phagocytic marker CD68.

Bone marrow mobilization with granulocyte macrophage colony-stimulating factor improves endothelial dysfunction and exercise capacity in patients with peripheral arterial disease

We hypothesized that granulocyte macrophage colony-stimulating factor (GM-CSF) administration will be safe and will improve endothelial dysfunction and exercise capacity by mobilizing progenitor cells in patients with peripheral arterial disease (PAD). Forty-five patients with PAD received thrice-weekly injections for 2 weeks of 3, 6, or 10 microg/kg per day of GM-CSF or placebo in successive cohorts of 15 subjects randomized 2:1 to drug or placebo. CD34+ mononuclear cell subsets and colony formation assay, endothelial function, ankle-brachial index, and walking capacity were measured. Granulocyte macrophage colony-stimulating factor administration was safe. After pooling data from GM-CSF cohorts, at 2 weeks, there was a significant increase in total leukocytes (43%, P < .0001), CD34+ cells (46%, P = .035), and colony-forming units (31%, P = .026, week 1). At 12 weeks, endothelial function improved with GM-CSF (flow-mediated vasodilation increased by 59%, P < .01) as did pain-free treadmill walking time (38 seconds, P = .008) and total treadmill walking time (55 seconds, P = .016). Corresponding changes were not observed in the placebo group. Granulocyte macrophage colony-stimulating factor therapy in patients with PAD was associated with mobilization of progenitor cells, improvement of endothelial dysfunction, and exercise capacity. The efficacy of strategies designed to mobilize bone marrow progenitors warrants further study in patients with PAD.

Macrophage Colony-Stimulating Factor Attenuated the Severity of Chronic Graft-Versus-Host Disease after Unrelated Bone Marrow Transplantation

Macrophage colony-stimulating factor (M-CSF) is a growth factor for cells from the monocyte-macrophage lineage and has been used in Japan after chemotherapy and bone marrow transplantation (BMT) to induce early recovery of neutrophils and to reduce the incidence of febrile neutropenia. A tolerogenic action of M-CSF was recently reported during induction of dendritic cells from cord blood. To study the effects of M-CSF administration on the long-term outcomes of unrelated BMT, We retrospectively analyzed the data of patients who had undergone their first BMT through the Japan Marrow Donor Program between 1993 and 2005 and for whom complete data concerning age, sex, HLA compatibility, and colony-stimulating factor were available. Fifty-four patients received M-CSF administration within 8 days of undergoing a BMT for a median length of 13 days, and the data of 500 patients who did not receive any CSF was used as the control. There were no significant differences in the patients' age, sex, donor's age, ATG administration, infused nucleated cell number, GVHD prophylaxis, or HLA compatibility. The M-CSF cohort (M) received more transplants from male donors (M, 77.8% vs. control, 62.3%, p = 0.020), and contained more standard-risk diseases than the control cohort (M, 64.8% vs. control, 47.8%, p = 0.014). Overall survival of the M cohort was superior to that of the control cohort (M, 57.7% vs. control, 46.4% at 5 years after transplantation), but the difference was not significant (log rank test, p = 0.084). There were no significant differences in the incidence or grade of acute GVHD between the two cohorts (log rank test, all acute GVHD, p = 0.710; grade 2 to 4, p = 0.680; grade 3 to 4, p = 0.653). The incidence of chronic GVHD was lower in the M cohort than in the control, but the difference was not significant (log rank test, p = 0.224). The incidence of extended type chronic GVHD of the M cohort was significantly lower than in the control (log rank test, p = 0.004). The observed occurrence of extended type chronic GVHD was 8.9% in the M cohort and 24.3% in the control. Multivariate analysis revealed that M-CSF administration was a significant factor (relative risk: 0.73, 95% CI: 0.55 – 0.94, p = 0.012), as was the age of patients and donors, underlying disease, and acute GVHD. Although chronic GVHD is associated with a lower relapse rate of the underlying malignant disease, we did not observe any increase of relapse in the M cohort (log rank test, p = 0.067). Our observation suggests the potential clinical use of M-CSF for preventing severe chronic GVHD.In patients with chronic GVHD, both the serum IL-10 level and IL-10 production from mononuclear cells have been shown to decrease after stimulation. After stimulation with LPS, M-CSF-induced macrophages are known to produce large amounts of IL-10 instead of IL-12. Recent reports have shown that M-CSF induced dendritic cells (DCs) with IL-4 in a culture from human cord blood and that these DCs produced high amounts of IL-10, but no IL-12, a pattern similar to that seen in M-CSF-induced macrophages. The low incidence and severity of both acute and chronic GVHD after cord blood transplantation regardless of HLA disparity is well documented. M-CSF is elevated during pregnancy and in cord blood. Taken together the above statements offer possible explanations for the low incidence and severity of GVHD in cord blood transplantation. In this context, our observation suggests that M-CSF administration after UR-BMT might decrease the severity of chronic GVHD through the induction of certain types of macrophages and DCs.

Powerful beneficial effects of macrophage colony-stimulating factor on -amyloid deposition and cognitive impairment in Alzheimer's disease

Alzheimer's disease is a major cause of dementia in humans. The appearance of cognitive decline is linked to the overproduction of a short peptide called beta-amyloid (Abeta) in both soluble and aggregate forms. Here, we show that injecting macrophage colony-stimulating factor (M-CSF) to Swedish beta-amyloid precursor protein (APP(Swe))/PS1 transgenic mice, a well-documented model for Alzheimer's disease, on a weekly basis prior to the appearance of learning and memory deficits prevented cognitive loss. M-CSF also increased the number of microglia in the parenchyma and decreased the number of Abeta deposits. Senile plaques were smaller and less dense in the brain of M-CSF-treated mice compared to littermate controls treated with vehicle solution. Interestingly, a higher ratio of microglia internalized Abeta in the brain of M-CSF-treated animals and the phagocytosed peptides were located in the late endosomes and lysosomes. Less Abeta(40) and Abeta(42) monomers were also detected in the extracellular protein enriched fractions of M-CSF-treated transgenic mice when compared with vehicle controls. Finally, treating APP(Swe)/PS1 mice that were already demonstrating installed Abeta pathology stabilized the cognitive decline. Together these results provide compelling evidence that systemic M-CSF administration is a powerful treatment to stimulate bone marrow-derived microglia, degrade Abeta and prevent or improve the cognitive decline associated with Abeta burden in a mouse model of Alzheimer's disease.

Important Roles for Macrophage Colony-stimulating Factor, CC Chemokine Ligand 2, and Mononuclear Phagocytes in the Pathogenesis of Pulmonary Fibrosis

An increase in the number of mononuclear phagocytes in lung biopsies from patients with idiopathic pulmonary fibrosis (IPF) worsens prognosis. Chemokines that recruit mononuclear phagocytes, such as CC chemokine ligand 2 (CCL2), are elevated in bronchoalveolar lavage (BAL) fluid (BALF) from patients with IPF. However, little attention is given to the role of the mononuclear phagocyte survival and recruitment factor, macrophage colony-stimulating factor (M-CSF), in pulmonary fibrosis. To investigate the role of mononuclear phagocytes and M-CSF in pulmonary fibrosis. Wild-type, M-CSF-/-, or CCL2-/- mice received intraperitoneal bleomycin. Lung inflammation and fibrosis were measured by immunohistochemistry, ELISA, collagen assay, BAL differentials, real-time polymerase chain reaction, and Western blot analysis. Human and mouse macrophages were stimulated with M-CSF for CCL2 expression. BALF from patients with IPF was examined for M-CSF and CCL2. M-CSF-/- and CCL2-/- mice had less lung fibrosis, mononuclear phagocyte recruitment, collagen deposition, and connective tissue growth factor (CTGF) expression after bleomycin administration than wild-type littermates. Human and mouse macrophages stimulated with M-CSF had increased CCL2 production, and intratracheal administration of M-CSF in mice induced CCL2 production in BALF. Finally, BALF from patients with IPF contained significantly more M-CSF and CCL2 than BALF from normal volunteers. Elevated levels of M-CSF were associated with elevated CCL2 in BALF and the diagnosis of IPF. These data suggest that M-CSF contributes to the pathogenesis of pulmonary fibrosis in mice and in patients with IPF through the involvement of mononuclear phagocytes and CCL2 production.

Macrophage Colony-Stimulating Factor Aggravates Rather than Regenerates Emphysematous Lungs in Mice

Background: Lung regeneration is an innovative strategy that may cure pulmonary emphysema. The bone marrow (BM) harbors pulmonary stem cells. Hematopoietic cytokine-driven mobilization of BM cells may thus support lung regeneration. Objectives: The aim of this study was to determine whether systemic administration of macrophage colony-stimulating factor (M-CSF) leads to the regeneration of lungs in a murine model of elastase-induced emphysema. Methods: C57BL/6J mice were administered elastase intratracheally. Four weeks later, in the absence or presence of elastase treatment, mice were intraperitoneally given either M-CSF or saline on days 1–5 each week for 3 weeks. Lung tissue was harvested 24 h after the last injection. Results: M-CSF administration without prior elastase did not affect the mean linear intercept, surface area, or surface area/lung volume. In contrast, M-CSF administration following elastase injury caused a greater increase in the mean linear intercept and greater decreases in surface area and surface area/lung volume than saline administration following elastase, indicating that M-CSF aggravated emphysema. This aggravation of emphysema was accompanied by accumulation of pulmonary alveolar macrophages (AMs) expressing metalloproteinase (MMP)-9 and MMP-12. M-CSF stimulated AMs to express MMPs in vitro. Conclusions: These results suggest that M-CSF administration does not support lung regeneration but rather aggravates the lung destruction associated with elastase injury.

Macrophage colony stimulating factor (M-CSF) protects spiral ganglion neurons following auditory nerve injury: morphological and functional evidence

Because hearing disturbance due to auditory nerve dysfunction imposes a formidable burden on human beings, intense efforts have been expended in experimental and clinical studies to discover ways to restore normal hearing. However, the great majority of these investigations have focused on the peripheral process side of bipolar auditory neurons, and very few trials have focused on ways to halt degenerative processes in auditory neurons from the central process side (in the cerebellopontine angle). In the present study, we investigated whether administration of macrophage colony-stimulating factor (M-CSF) could protect auditory neurons in a rat model of nerve injury. The electrophysiological and morphological results of our study indicated that M-CSF could ameliorate both anterograde (Wallerian) and retrograde degeneration in both the CNS and PNS portions of the auditory nerve. We attribute the success of M-CSF therapy to the reported functional dichotomy (having the potential to cause both neuroprotective and neurotoxic effects) of microglia and macrophages. Whether the activities of microglia/macrophages are neuroprotective or neurotoxic may depend upon the nature of the stimulus that activates the cells. In the present study, the neuroprotective effects of M-CSF that were observed could have been due to M-CSF we administered and to M-CSF released from endothelial cells, resident cells of the CNS parenchyma, or infiltrating macrophages. Another possibility is that M-CSF ameliorated apoptotic auditory neuronal death, although this hypothesis remains to be proved in future studies.

Administration of macrophage colony-stimulating factor mobilized both CD11b +CD11c + cells and NK1.1 + cells into peripheral blood

We attempted the phenotypic characterization of peripheral blood (PB) cells after daily administration of macrophage colony-stimulating factor (M-CSF) in mice. The number of CD11b + cells was increased by M-CSF treatment (2- and 5-day injections). Notably, CD11b brightCD11c dim, CD11b +CD11c + and CD11b +CD80 + cells were significantly increased by 2-day treatment of M-CSF. On the other hand, the number of NK1.1 + cells was not changed by the 2-day treatment, but it was significantly increased by the 5-day treatment. However, the numbers of CD3 + and NK1.1 +CD3 + cells were not changed by M-CSF treatment. Then, mononuclear cells (MNCs) were separated from the PB of mice treated with saline or M-CSF, and they were incubated with GM-CSF+IL-4 or IL-2. Compared with the saline-treated one (S-MNCs), the MNCs of M-CSF-treated mice (M-MNCs) showed strong proliferation by the GM-CSF+IL-4 stimulation. The MNCs could stimulate proliferation of allo-T cells in the mixed lymphocyte reaction (MLR), especially the M-MNCs showed strong reaction. On the other hand, the stimulation by IL-2 induced strong cell growth of MNCs. And M-CSF treatment enhanced this response. Furthermore, the M-MNCs (stimulated by IL-2 in vitro) exhibited greater cytotoxicity against Yac-1 cells than the S-MNCs. In conclusion, we found that administration of M-CSF mobilized CD11b +, CD11b +CD11c +, CD11b +CD80 +, and NK1.1 +cells into PB. And the injection of M-CSF facilitates the generation of dendritic and natural killer cells from PB cells in vitro. These results suggest that the mobilized cells may provide for application of immunotherapy.

Macrophage colony-stimulating factor inhibits tumor necrosis factor production and prolongs skin graft survival.

Despite the availability of a variety of immunosuppressive agents, acute rejection and infection after organ transplantation remain serious problems. We examined the effect of macrophage colony-stimulating factor (M-CSF) on the production of tumor necrosis factor (TNF) in a Bacille de Calmette Guérin-lipopolysaccharide-challenged mouse model. Both serial and repeated injections of M-CSF inhibited TNF production in a dose-dependent manner. Electrophoretic mobility shift assay showed that M-CSF-induced inhibition of TNF production was a result of suppression of nuclear factor-kappaB. High-dose M-CSF significantly prolonged skin graft survival in mice with orthotopic transplantation compared with the control and low-dose M-CSF groups. The combined administration of low-dose M-CSF and cyclosporine also significantly prolonged graft survival compared with the control and low-dose single agent-treated groups. Our results indicate that M-CSF at a high dose is a potent inhibitor of cytokine production and can potentially be used as an immunosuppressive agent for allograft rejection.

Clinical usefulness of macrophage colony-stimulating factor for ovarian cancers: Long-term prognosis after five years

We performed a randomized double blind study between 1992 and 1995 in which 214 patients with FIGO stage I to III ovarian cancers received administration of 10(6) units (low dose group) or 8x10(6) units (high dose group) of macrophage colony-stimulating factor (M-CSF) after cyclophosphamide/adriamycin/cisplatin (CAP) therapy. The period required to finish a set of intensive chemotherapy, which was the primary endpoint, was significantly shortened (p=0.0004), and the incidence of febrile neutropenia significantly decreased (p=0.04). In this study, we followed the patients for a prolonged period. The patients were divided into two groups: patients with complete tumor excision and those with incomplete excision, then the relapse rate and survival rate 5 years after initiation of the clinical study were compared. The relapse rate tended to be lower in the high dose group than in the low dose group in patients with no residual tumor (p=0.0750). However, there was no difference in the relapse rate between the two dose groups in patients with residual tumor. Although there were no significant differences in the survival rate between the high and low dose groups in patients with or without residual tumor, the survival rate in mucinous adenocarcinoma patients with no residual tumor was 64.3% in the low dose group (n=14) and 92.3% in the high dose group (n=14), showing a significantly higher rate (p=0.0436), and the survival rate tended to be higher in the high dose group in patients with serous adenocarcinoma (p=0.0786). Furthermore, in patients aged 40 years or younger with no residual tumor, the survival rates were 73.9 and 100% in the low and high dose groups, respectively, showing a significantly higher rate in the high dose group (p=0.0310). Our results suggest that administration of M-CSF can improve the long-term prognosis of ovarian cancer patients with no residual tumor, but further prospective randomized trials with a primary endpoint of relapse-preventing effect are needed.

Effect of Coadministration of M-CSF and IFN-αon NK1.1+Cells in Mice

The purpose of this study was to evaluate the effect of coadministration of macrophage colony-stimulating factor (M-CSF) and interferon-alpha (IFN-alpha) on NK1.1(+) cells in mice. Administration of M-CSF, but not IFN-alpha, increased the number of NK1.1(+) cells and CD11b(+) cells in spleen and blood. Coadministration of the two agents induced a greater increase in NK1.1(+) cells than did administration of M-CSF alone. Administration of M-CSF or IFN-alpha augmented the clearance activity of Yac-1 cells in lung, and coadministration of these agents further augmented this effect. The combination of M-CSF and IFN-alpha effectively reduced the formation of tumor nodules in lung and liver in an experimental metastasis model using B16 melanoma. The combination of M-CSF and IFN-alpha induced the increase and activation of NK1.1(+) cells more than either agent alone. These effects may contribute to the antimetastatic reaction by NK1.1(+) cells in vivo.

Effects of macrophage colony-stimulating factor (M-CSF) on anti-fungal activity of mononuclear phagocytes against Trichosporon asahii.

Trichosporon asahii is an emerging opportunistic pathogen in immunocompromised patients. Little is known about the mechanisms of host defence against T. asahii. We investigated the fungicidal activity of human peripheral blood monocytes and murine peritoneal macrophages against T. asahii isolates, and the effects of M-CSF on the anti-fungal activity of mononuclear phagocytes. We also established a neutropenic mouse model of disseminated trichosporonosis with T. asahii. M-CSF enhanced the phagocytic fungicidal activity of mononuclear cells, and infected mice treated with human M-CSF at 10 x 106 U/kg showed a significant improvement in survival rate, with fewer fungal colony counts in the lung compared with control mice. Mice treated with human M-CSF showed higher concentrations of tumour necrosis factor-alpha (TNF-alpha) in the lung and plasma compared with control mice. The survival rate was significantly reduced in mice treated with anti-mouse TNF-alpha. Our results showed that M-CSF enhanced the fungicidal activity of mononuclear phagocytes partly by production of TNF-alpha, and suggest that the administration of M-CSF to patients with disseminated trichosporonosis may be a useful adjunct to conventional anti-microbial therapy and prophylaxis.

RECOMBINANT HUMAN MACROPHAGE COLONY-STIMULATING FACTOR AUGMENTS PULMONARY HOST DEFENCES AGAINST ASPERGILLUS FUMIGATUS

The in vivo and ex vivo effects of macrophage colony-stimulating factor (M-CSF) were studied in a profoundly neutropenic rabbit model in order to determine its potential to augment pulmonary host defence againstAspergillus . M-CSF (100–600μg/kg/d) was administered prophylactically to neutropenic rabbits with pulmonary aspergillosis starting three days pre-inoculation and then throughout neutropenia. Rabbits receiving M-CSF had significantly increased survival (P=0.01) and decreased pulmonary injury, as measured by decreased pulmonary infarction (P=0.004), when compared with untreated controls. Microscopic studies demonstrated greater numbers of activated pulmonary alveolar macrophages (PAMs) in lung tissue of rabbits receiving M-CSF, in comparison to controls (P<0.001). PAMs harvested from rabbits treated with M-CSF had a significantly greater percent phagocytosis ofAspergillus fumigatus conidia than did PAMs from controls (P=0.04). These data indicate that prophylactic administration of M-CSF augments pulmonary host defence against A. fumigatus and suggest a potential role for this cytokine as adjunctive therapy in the treatment of pulmonary aspergillosis in the setting of profound neutropenia.

Repopulation of Kupffer cells in op/op mice after administration of liposome-encapsulated dichloromethylene diphosphonate

Kupffer cells were selectively eliminated in the macrophage colony stimulating factor (M-CSF)-deficient osteopetrotic (op/op) mice by intravenous administration of liposome-entrapped dichloromethylene diphosphonate. Repopulation of Kupffer cells was observed in the Kupffer cell-depleted littermate mouse (op/+) liver by 14 days after treatment. In contrast, repopulation of Kupffer cells was not observed in the Kupffer cell-depleted op/op mice through the observation period of 56 days. Daily administration of M-CSF induced remarkable repopulation of Kupffer cells and proliferation of macrophage precursor cells, whereas GM-CSF and IL-3 were less effective. These findings indicated that M-CSF plays a major role in Kupffer cell development.

Priming Effects of Macrophage Colony-Stimulating Factor on Monocytic Leukemia Cells in Combination with Chemotherapy: Induction of Programmed Cell Death In Vivo

Two elderly patients with chronic myelomonocytic leukemia were treated with cytosine ara-binoside (Ara-C) and aclarubicin (ACR) under simultaneous administrations of macrophage colony-stimulating factor (M-CSF) (CAM), and both obtained good responses. Examination of apoptosis using flow cytometry revealed induction of apoptotic death of leukemia cells by CAM in Patient 2, while neither induction of apoptotic death of leukemia cells nor clinical response were seen with CAG (Ara-C, ACR, and granulocyte colony-stimulating factor) given prior to CAM in Patient 1. These findings suggested that chemotherapy combined with simultaneous administration of M-CSF could effectively reduce monocytic leukemia cells by inducing programmed cell death.

Exposure-based safety evaluation of recombinant human macrophage colony-stimulating factor (M-CSF) in cynomolgus monkeys.

The safety of M-CSF was assessed in cynomolgus monkeys in an intravenous dosing regimen. Exposure (AUC0-24) multiples (monkey vs human) were calculated using the no observable adverse effect level (NOAEL) observed in this study and correlated with known M-CSF-induced toxicities in a previous continuous intravenous infusion (civ) study in monkeys. M-CSF was administered by daily intravenous infusion (2 h) to cynomolgus monkeys (2/sex/ group) at 0.1, 0.3, 0.7, and 1.0 mg/kg/day, for 28 consecutive days. Control animals (2/sex) received placebo. The 0.7 mg/kg/day group was held for an additional 4-week recovery period. Criteria evaluated included physical observations, ophthalmoscopy, electrocardiography, body weight, food consumption, clinical pathology, antibody formation, pharmacokinetics, necropsy, organ weights, and histopathology. The only effect previously seen in monkeys after intravenously administered M-CSF occurred in animals in the 0.7 and 1.0 mg/kg/day groups. They exhibited a slight decrease in platelets between days 4 and 12 with subsequent recovery. No effects related to M-CSF administration were evident in macroscopic or microscopic evaluations and there was no evidence of anti-M-CSF antibody production. M-CSF at all dose levels was completely eliminated within each dosing interval with no accumulation. Clearance of M-CSF was enhanced during the first week of dosing, but returned to baseline clearance levels by day 27. This dosing regimen was shown to be remarkably free of toxicities noted in a previous monkey study where M-CSF was given by civ at similar daily doses. At the high dose, which was considered to be the NOAEL, the AUC0-24 was 40-fold greater than the AUC0-24 in clinical trials where 2.0 mg/m2 was administered by a daily 2-h infusion.

Transient Thrombocytopenia Produced by Administration of Macrophage Colony-Stimulating Factor: Investigations of the Mechanism

Administration of macrophage colony-stimulating factor (M-CSF) to mice (2 to 8 mg/kg/d × 5d) produced dose-dependent thrombocytopenia, which reached its nadir on days 4 to 5, followed by rapid recovery. Surprisingly, when administration of M-CSF was prolonged, the thrombocytopenia completely resolved, despite continued treatment. Splenectomy did not prevent the thrombocytopenia. Readministration of M-CSF after various intervals continued to produce the thrombocytopenic effect, even after 35 days. Measurements of Meg-CFC and megakaryocyte ploidy during the periods of M-CSF treatment and recovery of normal platelet levels showed no evidence of bone marrow suppression. Platelet survival was markedly decreased after 5 days of M-CSF (at the platelet count nadir) and after 9 days of continued M-CSF treatment, when the platelet count had returned to normal. Platelets from M-CSF–treated donors demonstrated normal survival when transfused into normal recipients. We concluded that thrombocytopenia produced by M-CSF was not due to suppression of thrombopoiesis, but to increased activity of the monocyte/macrophage system, which caused shortened platelet survival, and that subsequently, increased platelet production compensated for ongoing platelet destruction and resulted in normal platelet levels.