The Role of Zinc in GM-CSF-Induced Signaling in Human Polymorphonuclear Leukocytes.

SCOPE: Zinc is suggested to be necessary for functional signaling induced by certain growth factors. The granulocyte-macrophage colony-stimulating factor (GM-CSF) is a key factor for differentiation and activation of myeloid cells. This report analyses the impact of different zinc concentrations on GM-CSF-induced signaling in mature polymorphonuclear leukocytes (PMN). METHODS AND RESULTS: As measured by flow cytometry, zinc increases surface GM-CSF receptor (GM-CSFR) in PMN, whereas monocytes respond with decreased GM-CSFR surface expression. Since total cellular GM-CSFR expression remains unaffected, the observed zinc-induced GM-CSFR surface dynamics may be explained by receptor redistribution. In PMN, zinc enhanced phosphorylation of mitogen-activated protein kinases (MAPK) in a dose-dependent manner as found in western blot. Zinc-induced MAPK phosphorylation is additionally augmented by moderate GM-CSF stimulation. CONCLUSION: The present study demonstrates the opposing influence of zinc on GM-CSFR surface expression in monocytes and PMN. Zinc and GM-CSF, use in optimized concentrations, augment MAPK signaling, and increase expression of MAPK-induced myeloid cell leukemia-1 (Mcl-1) in PMN. Thus, this study concludes that zinc strengthens growth factor-induced signaling. Hence, the study provides a basis for further in vivo studies, focusing on the therapeutic value of zinc in patients with a disturbed GM-CSF signaling.

Yolk-sac-derived macrophages progressively expand in the mouse kidney with age.

Renal macrophages represent a highly heterogeneous and specialized population of myeloid cells with mixed developmental origins from the yolk-sac and hematopoietic stem cells (HSC). They promote both injury and repair by regulating inflammation, angiogenesis, and tissue remodeling. Recent reports highlight differential roles for ontogenically distinct renal macrophage populations in disease. However, little is known about how these populations change over time in normal, uninjured kidneys. Prior reports demonstrated a high proportion of HSC-derived macrophages in the young adult kidney. Unexpectedly, using genetic fate-mapping and parabiosis studies, we found that yolk-sac-derived macrophages progressively expand in number with age and become a major contributor to the renal macrophage population in older mice. This chronological shift in macrophage composition involves local cellular proliferation and recruitment from circulating progenitors and may contribute to the distinct immune responses, limited reparative capacity, and increased disease susceptibility of kidneys in the elderly population.

Older people are more likely to develop kidney disease, which increases their risk of having other conditions such as a heart attack or stroke and, in some cases, can lead to their death. Older kidneys are less able to repair themselves after an injury, which may help explain why aging contributes to kidney disease. Another possibility is that older kidneys are more susceptible to excessive inflammation. Learning more about the processes that lead to kidney inflammation in older people might lead to better ways to prevent or treat their kidney disease. Immune cells called macrophages help protect the body from injury and disease. They do this by triggering inflammation, which aides healing. Too much inflammation can be harmful though, making macrophages a prime suspect in age-related kidney harm. Studying these immune cells in the kidney and how they change over the lifespan could help scientists to better understand age-related kidney disease. Now, Ide, Yahara et al. show that one type of macrophage is better at multiplying in older kidneys. In the experiments, mice were genetically engineered to make a fluorescent red protein in one kind of macrophage. This allowed Ide, Yahara et al. to track these immune cells as the mice aged. The experiments showed that this subgroup of cells is first produced when the mice are embryos. They stay in the mouse kidneys into adulthood, and are so prolific that, over time, they eventually become the most common macrophage in older kidneys. The fact that one type of embryonically derived macrophage takes over with age may explain the increased inflammation and reduced repair capacity seen in aging kidneys. More studies will help scientists to understand how these particular cells contribute to age-related changes in susceptibility to kidney disease.

Role of GM-CSF in a mouse model of experimental autoimmune prostatitis.

The etiology of chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is still unknown. Granulocyte macrophage colony-stimulating factor (GM-CSF) has been shown to play an important role in the development of autoimmune and inflammatory diseases. Here, we investigated the expression and function of GM-CSF in patients with CP/CPPS and in a mouse model of experimental autoimmune prostatitis (EAP). GM-CSF mRNA levels were detected in expressed prostatic secretions samples from patients with CP/CPPS and in prostate tissue from a mouse model of EAP. The expression of GM-CSF receptor in mouse prostate and dorsal root ganglia were determined using PCR and immunohistochemistry. Behavioral testing and inflammation scoring were performed to evaluate the role of GM-CSF in disease development and symptom severity of EAP using GM-CSF knockout mice. mRNA levels of putative nociceptive and inflammatory markers were measured in the prostate after the induction of EAP. Elevated GM-CSF mRNA levels were observed in expressed prostatic secretions samples from patients with CP/CPPS compared with healthy volunteers. GM-CSF mRNA was also significantly increased in prostate tissue of the EAP mice model. The expression of GM-CSF receptors was confirmed in mouse prostate and dorsal root ganglia. GM-CSF knockout mice showed fewer Infiltrating leukocytes and pain symptoms after the induction of EAP. Deletion of GM-CSF significantly diminished EAP-induced increases of chemokine (C-C motif) ligand 2, chemokine (C-C motif) ligand 3, and nerve growth factor mRNA expression. The results indicated that GM-CSF plays a functional role in the pathogenesis of EAP. GM-CSF may function as a signaling mediator for both inflammation and pain transduction in CP/CPPS.

Chemotherapy-Induced IL34 Enhances Immunosuppression by Tumor-Associated Macrophages and Mediates Survival of Chemoresistant Lung Cancer Cells.

The ability of tumor cells to escape immune destruction and their acquired resistance to chemotherapy are major obstacles to effective cancer therapy. Although immune checkpoint therapies such as anti-PD-1 address these issues in part, clinical responses remain limited to a subpopulation of patients. In this report, we identified IL34 produced by cancer cells as a driver of chemoresistance. In particular, we found that IL34 modulated the functions of tumor-associated macrophages to enhance local immunosuppression and to promote the survival of chemoresistant cancer cells by activating AKT signaling. Targeting IL34 in chemoresistant tumors resulted in a remarkable inhibition of tumor growth when accompanied with chemotherapy. Our results define a pathogenic role for IL34 in mediating immunosuppression and chemoresistance and identify it as a tractable target for anticancer therapy. Cancer Res; 76(20); 6030-42. ©2016 AACR.

Interleukin (IL)-3/granulocyte macrophage-colony stimulating factor/IL-5 receptor alpha and beta chains are preferentially expressed in acute myeloid leukaemias with mutated FMS-related tyrosine kinase 3 receptor.

The common beta chain subunit (beta(c)), also known as CDw131, shared by the interleukin-3 (IL-3), granulocytic macrophage colony-stimulating factor (GM-CSF) and IL-5 receptors, is required for high-affinity ligand binding and signal transduction. The present study explored the expression of CDw131 in 105 de novo cases of acute myeloid leukaemia (AML). The levels of CDw131 expression were used to identify two AML subgroups characterized by low (75/105) and high (30/105) expression of this receptor chain. It was observed that (i) the level of CDw131 expression strictly correlated with the level of CD116 (GM-CSFalpha receptor chain) and CD123 (IL-3Ralpha chain); (ii) AMLs with high CDw131 expression were characterized by low CD34 expression and usually high CD11b, CD14 expression; (iii) AMLs with high CDw131 expression frequently co-expressed receptors for angiogenic growth factors (vascular endothelial growth factor R2, Tie-2); (iv) AMLs with high CDw131 expression were more cycling than those with low CDw131 expression; (v) AMLs with high CDw131 frequently displayed Feline Murine Sarcoma (FMS-related) tyrosine kinase 3 (FLT3) internal tandem duplication and constitutively activated Signal Transducer and Activator of Transcription-5 (STAT5). In conclusion, the analysis of the level of CDw131 expression enabled the identification of a subset of AMLs characterized by a high cycling status, the expression of myelo-monocytic markers, mutated FLT3 and the co-expression of receptors for angiogenic growth factors. These findings are of value for the development of new therapeutic strategies for the treatment of these AMLs.

Induction of apoptosis on K562 cell line and double strand breaks on colon cancer cell line expressing high affinity receptor for granulocyte macrophage-colony stimulating factor (GM-CSF).

BACKGROUND: Immunotoxins are comprised of both the cell targeting and the cell killing moieties. We previously established a new immunotoxin, i.e. Shiga toxin granulocyte macrophage-colony stimulating factor (StxA1-GM-CSF), comprises of catalytic domain of Stx, as a killing moiety and GM-CSF, as a cell targeting moiety. In this study, the ability of the immunotoxin to induce apoptosis and double strand breaks (DSB) on different cell lines was investigated. METHODS: The recombinant hybrid protein was expressed in bacterial expression system and purified with nickel-nitrilotriacetate acid resin. The K562 (erythroid leukemia) cell line and LS174 (colon carcinoma) were used in this study. The neutral comet assay was carried out for the detection of DSB and Hoechst staining was performed for apoptosis. RESULTS: StxA1-GM-CSF effectively induced apoptosis on K562 cell line and DNA Double Strand Break (DSB) were observed on colon cancer cell line treated with StxA1-GM-CSF. CONCLUSION: This novel action i.e. DNA damage might be a relevant mechanism of action for StxA1-GM-CSF that is designed to act as immunotoxin, although further investigation is required.

Ski can negatively regulates macrophage differentiation through its interaction with PU.1.

In the hematopoietic cell system, the oncoprotein Ski dramatically affects growth and differentiation programs, in some cases leading to malignant leukemia. However, little is known about the interaction partners or signaling pathways involved in the Ski-mediated block of differentiation in hematopoietic cells. Here we show that Ski interacts with PU.1, a lineage-specific transcription factor essential for terminal myeloid differentiation, and thereby represses PU.1-dependent transcriptional activation. Consistent with this, Ski inhibits the biological function of PU.1 to promote myeloid cells to differentiate into macrophage colony-stimulating factor receptor (M-CSFR)-positive macrophages. Using a Ski mutant deficient in PU.1 binding, we demonstrate that Ski-PU.1 interaction is critical for Ski's ability to repress PU.1-dependent transcription and block macrophage differentiation. Furthermore, we provide evidence that Ski-mediated repression of PU.1 is due to Ski's ability to recruit histone deacetylase 3 to PU.1 bound to DNA. Since inactivation of PU.1 is closely related to the development of myeloid leukemia and Ski strongly inhibits PU.1 function, we propose that aberrant Ski expression in certain types of myeloid cell lineages might contribute to leukemogenesis.

Expression of the GM-CSF receptor in ovine spermatozoa: GM-CSF effect on sperm viability and motility of sperm subpopulations after the freezing-thawing process.

The granulocyte-macrophage colony stimulating factor (GM-CSF) is a pleiotropic cytokine capable of stimulating proliferation, maturation and function of haematopoietic cells. Receptors for this cytokine are composed of two subunits, alpha and beta, and are expressed in myeloid progenitors and mature mononuclear phagocytes, monocytes, eosinophils and neutrophils, as well as in other non-haematopoietic cells. We have previously demonstrated that bull spermatozoa express functional GM-CSF receptors that signal for increased glucose and vitamin-C uptake and enhance several parameters of sperm motility in the presence of glucose or fructose substrates. In this study, we have analyzed the expression of GM-CSF receptors in ovine spermatozoa and studied the effect of GM-CSF on sperm viability and motility after the freezing-thawing process. Immunolocalization and immunoblotting analyses demonstrated that ovine spermatozoa (Xisqueta race) expressed GM-CSF receptors. In addition, GM-CSF partially counteracted the impairing action of freezing/thawing on the percentage of total motility, as well as on the specific motility patterns of each of the separate, motile sperm subpopulations of ram ejaculates subjected to this protocol. These results suggest that GM-CSF can play a role in the resistance of ram spermatozoa to environmental thermal stress.

Unilineage monocytopoiesis in hematopoietic progenitor culture: switching cytokine treatment at all Mo developmental stages induces differentiation into dendritic cells.

We have developed a new culture system whereby human hematopoietic progenitors purified from adult peripheral blood extensively proliferate and gradually differentiate into >95% pure monocytic (Mo) cells. At all developmental stages treatment with interleukin (IL)-4+granulocyte-macrophage colony-stimulating factor or IL-4+c-Kit-ligand+FLT-3 ligand switched the Mo precursors into dendritic cells (DCs). The switching capacity decreased only at the end of the culture, when most Mo cells matured to macrophages. Moreover, the Mo precursors were highly susceptible to transduction with lentiviral vectors: once switched to DCs, they maintained the transgene expression, as well as the phenotype and function of the DC lineage. Our results provide new insight into the potential role of the Mo lineage as a reservoir of DCs in vivo. Furthermore, the methodology for transduction of Mo precursors provides a tool to generate genetically modified, normally functioning DCs potentially useful for immunotherapy.

Granulocyte macrophage colony stimulating factor (GM-CSF) activity is regulated by a GM-CSF binding molecule in Wallerian degeneration following injury to peripheral nerve axons.

The hematopoietic factor and inflammatory cytokine GM-CSF is involved in PNS and CNS injury and disease, and in macrophage and microglia function regulation. We presently document that injury to PNS axons induces in vivo production of GM-CSF-inhibitor and GM-CSF-augmenter activities. GM-CSF-inhibitor activity was detected in extract and conditioned medium (CM) of injured PNS but not in extract of intact PNS, and was removed from CM by GM-CSF affinity chromatography, suggesting it is carried by a secreted GM-CSF binding molecule. CM further displayed GM-CSF-augmenter activity along with GM-CSF-inhibitor activity but at contrasting concentrations; augmentation at lowest and inhibition at highest. GM-CSF activity is thus regulated during Wallerian degeneration (WD); augmenter activity characterizes the onset and inhibitor activity the later stages of WD.

Enforced granulocyte/macrophage colony-stimulating factor signals do not support lymphopoiesis, but instruct lymphoid to myelomonocytic lineage conversion.

We evaluated the effects of ectopic granulocyte/macrophage colony-stimulating factor (GM-CSF) signals on hematopoietic commitment and differentiation. Lineage-restricted progenitors purified from mice with the ubiquitous transgenic human GM-CSF receptor (hGM-CSFR) were used for the analysis. In cultures with hGM-CSF alone, hGM-CSFR-expressing (hGM-CSFR+) granulocyte/monocyte progenitors (GMPs) and megakaryocyte/erythrocyte progenitors (MEPs) exclusively gave rise to granulocyte/monocyte (GM) and megakaryocyte/erythroid (MegE) colonies, respectively, providing formal proof that GM-CSF signals support the GM and MegE lineage differentiation without affecting the physiological myeloid fate. hGM-CSFR transgenic mice were crossed with mice deficient in interleukin (IL)-7, an essential cytokine for T and B cell development. Administration of hGM-CSF in these mice could not restore T or B lymphopoiesis, indicating that enforced GM-CSF signals cannot substitute for IL-7 to promote lymphopoiesis. Strikingly, >50% hGM-CSFR+ common lymphoid progenitors (CLPs) and >20% hGM-CSFR+ pro-T cells gave rise to granulocyte, monocyte, and/or myeloid dendritic cells, but not MegE lineage cells in the presence of hGM-CSF. Injection of hGM-CSF into mice transplanted with hGM-CSFR+ CLPs blocked their lymphoid differentiation, but induced development of GM cells in vivo. Thus, hGM-CSF transduces permissive signals for myeloerythroid differentiation, whereas it transmits potent instructive signals for the GM differentiation to CLPs and early T cell progenitors. These data suggest that a majority of CLPs and a fraction of pro-T cells possess plasticity for myelomonocytic differentiation that can be activated by ectopic GM-CSF signals, supporting the hypothesis that the down-regulation of GM-CSFR is a critical event in producing cells with a lymphoid-restricted lineage potential.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) acts independently of the beta common subunit of the GM-CSF receptor to prevent inner cell mass apoptosis in human embryos.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is expressed in the female reproductive tract during early pregnancy and can promote the growth and development of preimplantation embryos in several species. We have demonstrated with in vitro experiments that the incidence of blastulation in human embryos is increased approximately twofold when GM-CSF is present in the culture medium. In the present study, we investigated the mechanisms underlying the embryotrophic actions of GM-CSF. Using reverse transcription-polymerase chain reaction and immunocytochemistry, expression of mRNA and protein of the GM-CSF-receptor alpha subunit (GM-Ralpha) was detected in embryos from the first-cleavage through blastocyst stages of development, but the GM-CSF-receptor beta common subunit (betac) could not be detected at any stage. When neutralizing antibodies reactive with GM-Ralpha were added to embryo culture experiments, the development-promoting effect of GM-CSF was ablated. In contrast, GM-CSF activity in embryos was not inhibited either by antibodies to betac or by E21R, a synthetic GM-CSF analogue that acts to antagonize betac-mediated GM-CSF signaling. Unexpectedly, E21R was found to mimic native GM-CSF in promoting blastulation. When embryos were assessed for apoptosis and cell number by confocal microscopy after TUNEL and propidium iodine staining, it was found that blastocysts cultured in GM-CSF contained 50% fewer apoptotic nuclei and 30% more viable inner cell mass cells. Together, these data indicate that GM-CSF regulates cell viability in human embryos and that this potentially occurs through a novel receptor mechanism that is independent of betac.

Dysregulation of the granulocyte-macrophage colony-stimulating factor receptor is one of the causes of defective expression of CD80 antigen in systemic lupus erythematosus.

CD80 and CD86, expressed on the antigen-presenting cells (APCs) provide costimulatory signals for T lymphocytes. Recently, defective expression of CD80 has been reported in systemic lupus erythematosus (SLE) although its mechanism is unclear. Here, expression of the B7 antigens induced by interferon-gamma, interleukin-4 or granulocyte-macrophage stimulating-factor (GM-CSF) along the differentiation process of APCs was investigated. In contrast to CD86, expression of CD80 on the CD14+ cells induced by GM-CSF was reduced in SLE. GM-CSF receptor (GM-CSFR) was down-regulated by GM-CSF or phorbol 12-myristate 13-acetate in both of the normal controls and SLE patients, while this change was more remarkable in the latter. In the presence of 1-(5-isoquinolinsulfonyl)-2-methylpiperazine, an inhibitor of protein kinase C, the PMA-induced down-regulation of GM-CSFR was reversed in the normal controls but not in SLE. These data suggest that dysregulation of the GM-CSFR might be associated with the defective expression of CD80, leading to dysfunction of the APCs in SLE.

Bone and bone marrow interactions: hematological activity of osteoblastic growth peptide (OGP)-derived carboxy-terminal pentapeptide. II. Action on human hematopoietic stem cells.

Osteogenic growth peptide (OGP) is a peptide exerting regulatory effects on the bone and on bone marrow. The carboxy-terminal pentapeptide (OGP10-14) is the biologically active portion of OGP. We evaluated OGP10-14 hematopoietic activity performing colony-forming tests on human stem cells derived by bone marrow, peripheral blood and cord blood. Granulocyte-macrophage colony-forming unit (CFU) were significantly increased in OGP10-14-treated samples, while granulocyte-erythrocyte-monocyte-megakaryocyte CFU and burst-forming unit (BFU) erythroid were increased only in the cord blood test.Moreover, OGP10-14 preserves stem cells self renewal potential in long-term culture (LTC) initiating cells and acts directly on CD34+ enriched cells or by increasing activity of stem cell factor (SCF) and granulocyte-megakaryocyte colony-stimulating factor.

Granulocyte macrophage colony-stimulating factor in adenomyosis and autologous endometrium.

OBJECTIVE: Granulocyte macrophage colony-stimulating factor (GM-CSF) has been related to macrophage recruitment and activation and has been identified in the human endometrium. We determined whether adenomyosis expresses GM-CSF, and if present, compared GM-CSF protein expression in adenomyosis with that in autologous endometrium. METHODS: We examined ectopic and eutopic endometrium from 16 premenopausal women who had hysterectomies for abnormal uterine bleeding, pelvic pain, or uterine prolapse. Serial sections of premenopausal uteri containing endometrium and adenomyosis were analyzed by immunohistochemistry for GM-CSF ligand and receptor and CD68 macrophages. We analyzed the intensity of staining for GM-CSF ligand and receptor and macrophages in the glandular epithelium and stroma of adenomyosis and autologous endometrium. RESULTS: The GM-CSF ligand localized primarily in the glandular epithelium and myometrium with only light stromal staining. Staining for GM-CSF ligand was significantly higher in adenomyotic glands compared with autologous endometrial glands (P = .002), especially during the secretory phase of the menstrual cycle. There were no statistical differences in the amount and intensity of staining of the GM-CSF receptor in adenomyosis and autologous endometrium. Adenomyotic tissue contained significantly more macrophages than matched autologous endometrium (P = .0004). CONCLUSIONS: Adenomyotic glandular epithelium had greater expression of the GM-CSF ligand compared with autologous endometrium from premenopausal women, which indicates that GM-CSF may play a role in increasing the levels of activated macrophages in women with adenomyosis.

Perilesional injection of r-GM-CSF in patients with cutaneous melanoma metastases.

Based on evidence that granulocyte-macrophage colony stimulating factor (GM-CSF) induces a potent systemic antitumor immunity, we tested recombinant GM-CSF in advanced melanoma. Seven patients with histologically confirmed cutaneous melanoma metastases were treated with perilesional intracutaneous injections of recombinant GM-CSF and observed for a follow-up time of 5 y. All but two patients had a decrease in the total number of metastases. At the end of the 5 y follow-up three of the seven patients are still alive with only one patient receiving other than surgical therapy, and one patient died tumor free at the age of 93. The remaining three patients died from progressive melanoma. Perilesional intradermal GM-CSF therapy resulted in a mean survival time of 33 mo. The treatment was well tolerated and no side-effects other than local erythema at the injection sites and mild drowsiness were seen. Immunohistochemical analysis with staining for CD14 and GM-CSF receptor demonstrated an increased infiltration of monocytes into both injected and noninjected cutaneous melanoma metastases compared with lesions excised prior to the initiation of therapy. The same was true for CD4- and CD8-positive lymphocytes. This phenomenon, together with GM-CSF-induced leukocyte counts of more than 20,000 during therapy, support the possible impact of a systemic over a locally induced reaction by GM-CSF. To our knowledge this is the first report that intracutaneously injected GM-CSF results in long-lasting reduction of melanoma metastases.

Effects of inducible MEK1 activation on the cytokine dependency of lymphoid cells.

The Raf/MEK/MAP kinase cascade plays a critical role in transducing growth signals from activated cell surface receptors. Using deltaMEK1:ER, a conditionally active form of MEK1, we demonstrate the ability of this dual specificity protein kinase to abrogate the cytokine dependency of the murine lymphoid hematopoietic cell line FL5.12. Cytokine-independent cells were obtained from FL5.12 cells at a frequency of 1 x 10(-7), indicating that a low frequency of cells expressing deltaMEK1:ER were factor-independent. In general, cells that were converted to a cytokine-independent phenotype displayed a higher level of MAP kinase activity in response to deltaMEK1:ER activation than those that remained cytokine-dependent. deltaMEK1:ER-responsive cells could be maintained long-term in the presence of beta-estradiol, as well as the estrogen-receptor antagonist 4-hydroxy-tamoxifen. Removal of hormone led to the rapid cessation of cell growth in a manner similar to that observed when cytokine is withdrawn from the parental cells. GM-CSF mRNA transcripts were detected in the MEK1-responsive cells indicating that activated deltaMEK1:ER may induce a pathway leading to autocrine proliferation. Cytokine-dependent deltaMEK1:ER cells were found to increase the expression of GM-CSF receptor alpha (GM-CSFRalpha) in response to beta-estradiol. In contrast, MEK1-responsive cells were found to express constitutively lower levels of GM-CSFRalpha and beta common (betac) chains indicating that constitutive GM-CSF expression resulted in a decrease in GM-CSFR expression. Treatment of parental cells with supernatant from MEK1-responsive FL5.12 cells was sufficient to promote [3H]-thymidine incorporation. GM-CSF was found to enhance the viability of FL5.12 cells. The cell lines described here will be useful for elaborating the ability of the MAP kinase pathway to regulate cell proliferation in hematopoietic cells.

Granulocyte-macrophage colony-stimulating factor promotes glucose transport and blastomere viability in murine preimplantation embryos.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) secretion from epithelial cells lining the female reproductive tract is induced during early pregnancy by ovarian steroid hormones and constituents of seminal plasma. In this study we have investigated the influence of GM-CSF on development of preimplantation mouse embryos. Blastocyst-stage embryos were found to specifically bind (125)I-GM-CSF and analysis of GM-CSF mRNA receptor expression by reverse transcriptase-polymerase chain reaction indicated expression of the low-affinity alpha subunit of the GM-CSF receptor, but not the affinity-converting beta subunit (beta(c)), or GM-CSF ligand. GM-CSF receptor mRNA was present in the fertilized oocyte and all subsequent stages of development, and in blastocysts it was expressed in both inner cell mass and trophectoderm cells. In vitro culture of eight-cell embryos in recombinant GM-CSF accelerated development of blastocysts to hatching and implantation stages, with a maximum response at a concentration of 2 ng/ml (77 pM). Blastocysts recovered from GM-CSF-null mutant (GM-/-) mice on Day 4 of natural pregnancy or after superovulation showed retarded development, with the total cell number reduced by 14% and 18%, respectively, compared with GM+/+ embryos. Blastocysts generated in vitro from two-cell GM-/- and GM+/+ embryos were larger when recombinant GM-CSF was added to the culture medium (20% and 24% increases in total cell numbers in GM+/+ and GM-/- blastocysts, respectively). Incubation of blastocysts with recombinant GM-CSF elicited a 50% increase in the uptake of the nonmetabolizable glucose analogue, 3-O-methyl glucose. In conclusion, these data indicate that GM-CSF signaling through the low-affinity GM-CSF receptor in blastocysts is associated with increased glucose uptake and enhanced proliferation and/or viability of blastomeres. Together, the findings implicate a physiological role for maternal tract-derived GM-CSF in targeting the preimplantation embryo, and suggest that defective blastocyst development contributes to compromised pregnancy outcome in GM-CSF-null mutant mice.

Granulocyte/macrophage-colony-stimulating factor augments lymphokine-activated killer activity from lymphocytes via macrophages in lung cancer patients.

INTRODUCTION: Therapies with granulocyte/macrophage-colony-stimulating factor (GM-CSF) and interleukin(IL)-2 are designed to activate macrophages and lymphocytes. We investigated whether combined treatment with GM-CSF and IL-2 induced macrophage-mediated antitumor activity and/or T-cell-mediated antitumor activity in lung cancer patients. PATIENTS AND METHODS: Macrophages in the pleural cavity (PCM), lymphocytes in the pleural cavity (PLY), and peripheral blood lymphocytes (PBL) were separated from 48 patients with resectable lung cancer. Lymphokine-activated killer (LAK) activity was assayed by measuring 51Cr release. The proportion of PCM positive for the GM-CSF receptor (GM-CFSR) alpha chain was examined by flow-cytometric analysis and the expression of GM-CSFR alpha chain mRNA in PCM was examined by reverse transcription/polymerase chain reaction analysis. RESULTS: Treatment with GM-CSF developed no significant antitumor activity in PCM, PLY, or PBL. LAK activity was developed by PLY and PBL after incubation with IL-2. Stimulation with GM-CSF augmented LAK activities in PLY and PBL significantly, when these cells were cultured with autologous PCM (P < 0.05, P < 0.01). Moreover, GM-CSFR-alpha-chain-positive PCM had a higher potential to augmented LAK activities in PLY and PBL than had GM-CSFR-alpha-chain-negative PCM. CONCLUSION: These findings suggest that GM-CSF may stimulate GM-CSFR-alpha-chain-positive PCM and that these PCM may augment LAK activities developed by PLY and PBL. Combined treatment with GM-CSF and IL-2, therefore, may be a reasonable approach to treating lung cancer patients.