Induction and regulation of endogenous granulocyte colony-stimulating factor formation

Role of melatonin mediated G-CSF induction in hematopoietic system of gamma-irradiated mice

AIMS

Hematopoietic acute radiation syndrome (H-ARS) can cause lethality, and therefore, the necessity of a safe radioprotector. The present study was focused on investigating the role of melatonin in granulocytes colony-stimulating factor (G-CSF) and related mechanisms underlying the reduction of DNA damage in hematopoietic system of irradiated mice.

MAIN METHODS

C57BL/6 male mice were exposed to 2, 5, and 7.5Gy of whole-body irradiation (WBI), 30 min after intra-peritoneal administration of melatonin with different doses. Mice were sacrificed at different time intervals after WBI, and bone marrow, splenocytes, and peripheral blood lymphocytes were isolated for studying various parameters including micronuclei (MN), cell cycle, comet, γ-H2AX, gene expression, amino acid profiling, and hematology.

KEY FINDINGS

Melatonin100mg/kg ameliorated radiation (7.5Gy and 5Gy) induced MN frequency and cell death in bone marrow without mortality. At 24 h of post-WBI (2Gy), the frequency of micronucleated polychromatic erythrocytes (mnPCE) with different melatonin doses revealed 20 mg/kg as optimal i.p. dose for protecting the hematopoietic system against radiation injury. In comet assay, a significant reduction in radiation-induced % DNA tail (p ≤ 0.05) was observed at this dose. Melatonin reduced γ-H2AX foci/cell and eventually reached to the control level. Melatonin also decreased blood arginine levels in mice after 24 h of WBI. The gene expression of G-CSF, Bcl-2-associated X protein (BAX), and Bcl2 indicated the role of melatonin in G-CSF regulation and downstream pro-survival pathways along with anti-apoptotic activity.

SIGNIFICANCE

The results revealed that melatonin recovers the hematopoietic system of irradiated mice by inducing G-CSF mediated radioprotection.

G-CSF in tumors: Aggressiveness, tumor microenvironment and immune cell regulation

Granulocyte colony-stimulating factor (G-CSF) is a cytokine most well-known for maturation and mobilization of bone marrow neutrophils. Although it is used therapeutically to treat chemotherapy induced neutropenia, it is also highly expressed in some tumors. Case reports suggest that tumors expressing high levels of G-CSF are aggressive, more difficult to treat, and present with poor prognosis and high mortality rates. Research on this topic suggests that G-CSF has tumor-promoting effects on both tumor cells and the tumor microenvironment. G-CSF has a direct effect on tumor cells to promote tumor stem cell longevity and overall tumor cell proliferation and migration. Additionally, it may promote pro-tumorigenic immune cell phenotypes such as M2 macrophages, myeloid-derived suppressor cells, and regulatory T cells. Overall, the literature suggests a plethora of pro-tumorigenic activity that should be balanced with the therapeutic use. In this review, we present an overview of the multiple complex roles of G-CSF and G-CSFR in tumors and their microenvironment and discuss how clinical advances and strategies may open new therapeutic avenues.

Granulocyte Colony Stimulating Factor Expression in Breast Cancer and Its Association with Carbonic Anhydrase IX and Immune Checkpoints

Simple Summary

Preclinical studies suggest that interactions between granulocyte colony-stimulating factor (G-CSF) and hypoxia-induced carbonic anhydrase IX regulate the trafficking and function of immune cells in the tumour microenvironment. We investigated the clinical significance of this crosstalk by analyzing the protein expression of G-CSF and macrophage markers by immunohistochemistry on a well-characterized tissue microarray series of invasive breast cancers. We report that high expression of G-CSF on breast carcinoma cells is linked with significantly improved survival in an important group of breast cancers that do not respond to hormonal therapy. These tumours were infiltrated by immune cells expressing biomarkers that can be targeted with immune checkpoint inhibitor drugs. In contrast, carbonic anhydrase IX expression was associated with unfavourable outcomes.

Abstract

Purpose: Granulocyte colony-stimulating factor (G-CSF) and hypoxia modulate the tumour immune microenvironment. In model systems, hypoxia-induced carbonic anhydrase IX (CAIX) has been associated with G-CSF and immune responses, including M2 polarization of macrophages. We investigated whether these associations exist in human breast cancer specimens, their relation to breast cancer subtypes, and clinical outcome. Methods: Using validated protocols and prespecified scoring methodology, G-CSF expression on carcinoma cells and CD163 expression on tumour-associated macrophages were assayed by immunohistochemistry and applied to a tissue microarray series of 2960 primary excision specimens linked to clinicopathologic, biomarker, and outcome data. Results: G-CSF_high expression showed a significant positive association with ER negativity, HER2 positivity, presence of CD163+ M2 macrophages, and CAIX expression. In univariate analysis, G-CSF_high phenotype was associated with improved survival in non-luminal cases, although the CAIX+ subset had a significantly adverse prognosis. A significant positive association was observed between immune checkpoint biomarkers on tumour-infiltrating lymphocytes and both G-CSF- and CAIX-expressing carcinoma cells. Immune checkpoint biomarkers correlated significantly with favourable prognosis in G-CSF_high/non-luminal cases independent of standard clinicopathological features. Conclusions: The prognostic associations linking G-CSF to immune biomarkers and CAIX strongly support their immunomodulatory roles in the tumour microenvironment.

Modulation of Adipose-Derived Mesenchymal Stem/Stromal Cell Transcriptome by G-CSF Stimulation

Mesenchymal stem/stromal cells (MSCs) exhibit multidifferentiation potential, paralleled with immunomodulatory and trophic properties that make them viable alternative tools for the treatment of degenerative disorders, allograft rejection, autoimmune diseases, and tissue regeneration. MSC functional attributes can be modulated by exposing them to inflammatory-stimulating microenvironments (i.e., priming) before their therapeutic use. Granulocyte-colony stimulating factor (G-CSF) is a cytokine that plays key roles in immune response and hematopoiesis modulation through direct effects on hematopoietic progenitors' proliferation, survival, and mobilization. Despite the established roles of MSCs supporting hematopoiesis, the effects of G-CSF on MSCs biology have not been thoroughly explored. This study reveals that G-CSF has also direct effects on adipose-derived MSCs (ADSCs), modulating their functions. Herein, microarray-based transcriptomic analysis shows that G-CSF stimulation in vitro results in modulation of various signaling pathways including ones related with the metabolism of hyaluronan (HA), conferring a profile of cell mobilization to ADSCs, mediated in a cell-intrinsic fashion in part by reducing CD44 expression and HA synthesis-related genes. Collectively, these data suggest a direct modulatory effect of G-CSF on ADSC function, potentially altering their therapeutic capacity and thus the design of future clinical protocols.

Mathematical analysis and drug exposure evaluation of pharmacokinetic models with endogenous production and simultaneous first-order and Michaelis-Menten elimination: the case of single dose

Drugs with an additional endogenous source often exhibit simultaneous first-order and Michaelis-Menten elimination and are becoming quite common in pharmacokinetic modeling. In this paper, we investigate the case of single dose intravenous bolus administration for the one-compartment model. Relying on a formerly introduced transcendent function, we were able to analytically express the concentration time course of this model and provide the pharmacokinetic interpretation of its components. Using the concept of the corrected concentration, the mathematical expressions for the partial and total areas under the concentration time curve (AUC) were also given. The impact on the corrected concentration and AUC is discussed as well as the relative contribution of the exogenous part in presence of endogenous production. The present findings theoretically elucidate several pharmacokinetic issues for the considered drug compounds and provide guidance for the rational estimation of their pharmacokinetic parameters.

Antagonizing Retinoic Acid Receptors Increases Myeloid Cell Production by Cultured Human Hematopoietic Stem Cells

Activities of the retinoic acid receptor (RAR)α and RARγ are important to hematopoiesis. Here, we have investigated the effects of receptor selective agonists and antagonists on the primitive human hematopoietic cell lines KG1 and NB-4 and purified normal human hematopoietic stem cells (HSCs). Agonizing RARα (by AGN195183) was effective in driving neutrophil differentiation of NB-4 cells and this agonist synergized with a low amount (10 nM) of 1α,25-dihydroxyvitamin D3 to drive monocyte differentiation of NB-4 and KG1 cells. Treatment of cultures of human HSCs (supplemented with stem cell factor ± interleukin 3) with an antagonist of all RARs (AGN194310) or of RARα (AGN196996) prolonged the lifespan of cultures, up to 55 days, and increased the production of neutrophils and monocytes. Slowing down of cell differentiation was not observed, and instead, hematopoietic stem and progenitor cells had expanded in number. Antagonism of RARγ (by AGN205728) did not affect cultures of HSCs. Studies of CV-1 and LNCaP cells transfected with RAR expression vectors and a reporter vector revealed that RARγ and RARβ are activated by sub-nM all-trans retinoic acid (EC50-0.3 nM): ~50-fold more is required for activation of RARα (EC50-16 nM). These findings further support the notion that the balance of expression and activity of RARα and RARγ are important to hematopoietic stem and progenitor cell expansion and differentiation.

The Essential Role of Type I Interferons in Differentiation and Activation of Tumor-Associated Neutrophils

Type I interferons (IFNs) were first characterized in the process of viral interference. However, since then, IFNs are found to be involved in a wide range of biological processes. In the mouse, type I IFNs comprise a large family of cytokines. At least 12 IFN-α and one IFN-β can be found and they all signal through the same receptor (IFNAR). A hierarchy of expression has been established for type I IFNs, where IFN-β is induced first and it activates in a paracrine and autocrine fashion a cascade of other type I IFNs. Besides its importance in the induction of the IFN cascade, IFN-β is also constitutively expressed in low amounts under normal non-inflammatory conditions, thus facilitating "primed" state of the immune system. In the context of cancer, type I IFNs show strong antitumor function as they play a key role in mounting antitumor immune responses through the modulation of neutrophil differentiation, activation, and migration. Owing to their plasticity, neutrophils play diverse roles during cancer development and metastasis since they possess both tumor-promoting (N2) and tumor-limiting (N1) properties. Notably, the differentiation into antitumor phenotype is strongly supported by type I IFNs. It could also be shown that these cytokines are critical for the suppression of neutrophil migration into tumor and metastasis site by regulating chemokine receptors, e.g., CXCR2 on these cells and by influencing their longevity. Type I IFNs limit the life span of neutrophils by influencing both, the extrinsic as well as the intrinsic apoptosis pathways. Such antitumor neutrophils efficiently suppress the pro-angiogenic factors expression, e.g., vascular endothelial growth factor and matrix metallopeptidase 9. This in turn restricts tumor vascularization and growth. Thus, type I IFNs appear to be the part of the natural tumor surveillance mechanism. Here we provide an up to date review of how type I IFNs influence the pro- and antitumor properties of neutrophils. Understanding these mechanisms is particularly important from a therapeutic point of view.

Leukemia Cells and the Cytokine Network: Therapeutic Prospects

The network and balance of cytokines is of major importance in maintaining proper homeostasis of hematopoiesis. Abnormalities in this network may result in a variety of blood disorders; however, the role of this network is not clear in leukemia. The use of antineoplastic agents has improved the survival rate of some types of leukemia, and adjunctive therapy with cytokines may be helpful. Chemotherapeutic approaches are no longer the best choice because cytotoxicity may affect normal and leukemic cells, and leukemic cells may develop resistance to the chemotherapeutic agent. Induction of differentiation to a mature phenotype and the control of apoptotic-gene expression have provided other possible alternative therapies. Combined effects of cytokines and vitamin derivatives such as retinoic acid (RA) and 1, 25 dihydroxyvitamin D3 (VD3) were found more beneficial than any of these agents individually. These agents exhibit cooperative effects, potentiate each other's effects, or both. Therefore, understanding the hematopoietic actions of these agents, their interactions with their receptors, and their differentiation signaling pathways may result In the design of new therapies. However, the role of cytokines in apoptosis is controversial because in some cases they were found to increase tumor cell resistance to apoptosis-inducing agents. Recent studies in the molecular biology of gene regulation, transcription factors, and repressors have led to new possible approaches such as differentiation therapy for the treatment of leukemia. In addition, the development of drugs that act on the molecular level such as imatinib is just the beginning of a new era in molecular targeted therapy in which the drug acts specifically on the leukemic cell. There are many possible combinations of cytokines, retinoids, and VD3, and perhaps the best therapeutic combination is yet to be described. This minireview is an update on the role of cytokines and the therapeutic potential of combinations with agents such as RA, VD3, and other chemotherapeutic agents.

Exercise as an Adjuvant Therapy for Hematopoietic Stem Cell Mobilization

Hematopoietic stem cell transplant (HSCT) using mobilized peripheral blood hematopoietic stem cells (HSPCs) is the only curative strategy for many patients suffering from hematological malignancies. HSPC collection protocols rely on pharmacological agents to mobilize HSPCs to peripheral blood. Limitations including variable donor responses and long dosing protocols merit further investigations into adjuvant therapies to enhance the efficiency of HSPCs collection. Exercise, a safe and feasible intervention in patients undergoing HSCT, has been previously shown to robustly stimulate HSPC mobilization from the bone marrow. Exercise-induced HSPC mobilization is transient limiting its current clinical potential. Thus, a deeper investigation of the mechanisms responsible for exercise-induced HSPC mobilization and the factors responsible for removal of HSPCs from circulation following exercise is warranted. The present review will describe current research on exercise and HSPC mobilization, outline the potential mechanisms responsible for exercise-induced HSPC mobilization, and highlight potential sites for HSPC homing following exercise. We also outline current barriers to the implementation of exercise as an adjuvant therapy for HSPC mobilization and suggest potential strategies to overcome these barriers.

Granulocyte colony-stimulating factor (G-CSF) increases histone-complexed DNA plasma levels in healthy volunteers

Granulocyte colony-stimulating factor (G-CSF) is an activator of neutrophil granulocytes. Neutrophil extracellular traps are a defensive mechanism consisting of neutrophils, platelets, DNA, histones and antimicrobial proteins. This study was performed to determine whether G-CSF increases histone-complexed DNA in the plasma of healthy volunteers. In total, 51 healthy volunteers (25 males and 26 females) were treated with G-CSF (18 with 300 µg single dose i.v., 27 with 5 µg/kg s.c. for 4 days) and six participants received a placebo. Histone-complexed DNA was measured by enzyme immunoassay in plasma samples at predefined time points (0, 2, 4, 6, 24 h after single dose, day 1, day 2 and day 5 after repeated doses). Histone levels were quantified by Western blotting. A single dose of G-CSF rapidly increased hc-DNA by about 50 % (p < 0.05 for 2-24 h). After repeated doses the increase was even more pronounced: hc-DNA increased by about 50 % (3.0 ± 0.9, p < 0.001 after 24 h and about fourfold after 96 h (p < 0.001)). A statistical significant increase in histone levels was detected as early as 4 h after G-CSF injection (0.43 ± 0.2 vs. 1.08 ± 0.3 µg/ml; p = 0.034). In the placebo group no significant changes occurred. Moreover, significantly higher levels of hc-DNA were measured in male compared to female subjects (226 ± 43 vs. 84 ± 19, p < 0.001). G-CSF injection substantially increases hc-DNA levels in healthy volunteers. There is a significant gender difference in hc-DNA at the baseline.

Pegfilgrastim for the prevention of chemotherapy-induced febrile neutropenia in patients with solid tumors

INTRODUCTION

Neutropenia and febrile neutropenia are the most common and most severe bone marrow toxicities of chemotherapy. Recombinant granulocyte-colony stimulating factors (G-CSFs), both daily (filgrastim and biosimilars, and lenograstim) and long-acting (pegfilgrastim and lipegfilgrastim) formulations, are currently available to counteract the negative consequences of these side effects.

AREAS COVERED

The purpose of this article is to review the physiopathology of chemotherapy-induced febrile neutropenia and its consequences, and the current evidence regarding the pharmacological properties, clinical efficacy and cost-effectiveness of pegfilgrastim as a strategy to prevent chemotherapy-induced febrile neutropenia in patients with solid tumors.

EXPERT OPINION

Chemotherapy-induced febrile neutropenia and its complications are still a major health-care concern, and the inappropriate employment of G-CSFs in clinical practice can partially explain its burden. Pegfilgrastim has pharmacological advantages over daily G-CSFs that makes it easily administrable, thus reducing the chance of incorrect delivery. The once-per-cycle administration might explain the findings derived from observational studies suggesting a possible superior efficacy of pegfilgrastim over daily G-CSFs. For patients at higher risk of failure with daily G-CSF prophylaxis (e.g. risk of non-compliance, difficulties on performing regular hemograms, high risk of developing febrile neutropenia), pegfilgrastim might be the most appropriate option.

NADPH oxidase controls neutrophilic response to sterile inflammation in mice by regulating the IL-1α/G-CSF axis

The leukocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase generates reactive oxygen species essential in microbial killing and regulation of inflammation. Inactivating mutations in this enzyme lead to chronic granulomatous disease (CGD), associated with increased susceptibility to both pyogenic infections and to inflammatory disorders. The role of the NADPH oxidase in regulating inflammation driven by nonmicrobial stimuli is poorly understood. Here, we show that NADPH oxidase deficiency enhances the early local release of interleukin-1α (IL-1α) in response to damaged cells, promoting an excessive granulocyte colony-stimulating factor (G-CSF)-regulated neutrophilic response and prolonged inflammation. In peritoneal inflammation elicited by tissue injury, X-linked Cybb-null (X-CGD) mice exhibited increased release of IL-1α and IL-1 receptor -mediated G-CSF production. In turn, higher levels of systemic G-CSF increased peripheral neutrophilia, which amplified neutrophilic peritoneal inflammation in X-CGD mice. Dampening early neutrophil recruitment by neutralization of IL-1α, G-CSF, or neutrophil depletion itself promoted resolution of otherwise prolonged inflammation in X-CGD. IL-1β played little role. Thus, we identified an excessive IL-1α/G-CSF response as a major driver of enhanced sterile inflammation in CGD in the response to damaged cells. More broadly, these results provide new insights into the regulation of sterile inflammation, and identify the NADPH oxidase in regulating the amplitude of the early neutrophilic response.

LPS-Induced G-CSF Expression in Macrophages Is Mediated by ERK2, but Not ERK1

Granulocyte colony-stimulating factor (G-CSF) selectively stimulates proliferation and differentiation of neutrophil progenitors which play important roles in host defense against infectious agents. However, persistent G-CSF production often leads to neutrophilia and excessive inflammatory reactions. There is therefore a need to understand the mechanism regulating G-CSF expression. In this study, we showed that U0126, a MEK1/2 inhibitor, decreases lipopolysaccharide (LPS)-stimulated G-CSF promoter activity, mRNA expression and protein secretion. Using short hairpin RNA knockdown, we demonstrated that ERK2, and not ERK1, involves in LPS-induced G-CSF expression, but not LPS-regulated expression of TNF-α. Reporter assays showed that ERK2 and C/EBPβ synergistically activate G-CSF promoter activity. Further chromatin immunoprecipitation (ChIP) assays revealed that U0126 inhibits LPS-induced binding of NF-κB (p50/p65) and C/EBPβ to the G-CSF promoter, but not their nuclear protein levels. Knockdown of ERK2 inhibits LPS-induced accessibility of the G-CSF promoter region to DNase I, suggesting that chromatin remodeling may occur. These findings clarify that ERK2, rather than ERK1, mediates LPS-induced G-CSF expression in macrophages by remodeling chromatin, and stimulates C/EBPβ-dependent activation of the G-CSF promoter. This study provides a potential target for regulating G-CSF expression.

Infection mobilizes hematopoietic stem cells through cooperative NOD-like receptor and Toll-like receptor signaling

Adult hematopoietic stem cells (HSCs) are maintained in specialized niches within the bone marrow under steady-state conditions and mobilize for extramedullary hematopoiesis during periods of stress such as bacterial infections. However, the underlying mechanisms are unclear. We show that systemic infection of mice with Escherichia coli, commonly associated with bacteremia in humans, mobilizes functional HSCs to the spleen. Accumulation of splenic HSCs (CD150+CD48-Lin(-/low)Sca1+cKit+) was diminished in TLR4-deficient and RIPK2-deficient mice, implicating TLRs and cytosolic NOD1/NOD2 signaling in the process. Accordingly, dual stimulation of NOD1 and TLR4 in radio-resistant cells alone was sufficient to mobilize HSCs, while TLR4 expression on HSCs was dispensable. Mechanistically, TLR4 and NOD1 synergistically induced granulocyte colony-stimulating factor (G-CSF), which was required for extramedullary HSC accumulation. Mobilized HSCs and progenitor cells gave rise to neutrophils and monocytes and contributed to limiting secondary infection.

SAA does not induce cytokine production in physiological conditions

SAA has been shown to have potential proinflammatory properties in inflammatory diseases such as atherosclerosis. These include induction of tumor necrosis factor α, interleukin-6, and monocyte chemoattractant protein 1 in vitro. However, concern has been raised that these effects might be due to use of recombinant SAA with low level of endotoxin contaminants or its non-native forms. Therefore, physiological relevance has not been fully elucidated. In this study, we investigated the role of SAA in the production of inflammatory cytokines. Stimulation of mouse monocyte J774 cells with lipid-poor recombinant human SAA and purified SAA derived from cardiac surgery patients, but not ApoA-I and ApoA-II, elicited pro-inflammatory cytokines like granulocyte colony stimulating factor (G-CSF). However, HDL-associated SAA failed to stimulate production of these cytokines. Using neutralizing antibodies against toll like receptor (TLR) 2 and 4, we could evaluate that TLR 2 is responsible for G-CSF production by lipid-poor SAA. To confirm these data in vivo, we expressed mouse SAA in SAA deficient C57BL/6 mice using an adenoviral vector. G-CSF was identically expressed in SAA-Adenoviral infected mice as well as in control null-Adenoviral mice at the early time points (4-8h) and could not be detected in plasma 24h after infection when plasma SAA levels were maximally elevated, indicating that adenoviral vector rather than SAA affected G-CSF levels. Taken together, our findings suggest that lipid-poor SAA, but not HDL-associated SAA, stimulates G-CSF production and this stimulation is mediated through TLR 2 in J774 cells. However, its physiological role in vivo remains ambiguous.

Role of macrophages in mobilization of hematopoietic progenitor cells from bone marrow after hemorrhagic shock

The release of hematopoietic progenitor cells (HPCs) from bone marrow (BM) is under tight homeostatic control. Under stress conditions, HPCs migrate from BM and egress into circulation to participate in immune response, wound repair, or tissue regeneration. Hemorrhagic shock with resuscitation (HS/R), resulting from severe trauma and major surgery, promotes HPC mobilization from BM, which, in turn, affects post-HS immune responses. In this study, we investigated the mechanism of HS/R regulation of HPC mobilization from BM. Using a mouse HS/R model, we demonstrate that the endogenous alarmin molecule high-mobility group box 1 mediates HS/R-induced granulocyte colony-stimulating factor secretion from macrophages (Mϕ in a RAGE [receptor for advanced glycation end products] signaling-dependent manner. Secreted granulocyte colony-stimulating factor, in turn, induces HPC egress from BM. We also show that activation of β-adrenergic receptors on Mϕ by catecholamine mediates the HS/R-induced release of high-mobility group box 1. These data indicate that HS/R, a global ischemia-reperfusion stimulus, regulates HPC mobilization through a series of interacting pathways that include neuroendocrine and innate immune systems, in which Mϕ play a central role.

Growth factors in ischemic stroke

Data from pre-clinical and clinical studies provide evidence that colony-stimulating factors (CSFs) and other growth factors (GFs) can improve stroke outcome by reducing stroke damage through their anti-apoptotic and anti-inflammatory effects, and by promoting angiogenesis and neurogenesis. This review provides a critical and up-to-date literature review on CSF use in stroke. We searched for experimental and clinical studies on haemopoietic GFs such as granulocyte CSF, erythropoietin, granulocyte-macrophage colony-stimulating factor, stem cell factor (SCF), vascular endothelial GF, stromal cell-derived factor-1α and SCF in ischemic stroke. We also considered studies on insulin-like growth factor-1 and neurotrophins. Despite promising results from animal models, the lack of data in human beings hampers efficacy assessments of GFs on stroke outcome. We provide a comprehensive and critical view of the present knowledge about GFs and stroke, and an overview of ongoing and future prospects.

G-CSF influences mouse skeletal muscle development and regeneration by stimulating myoblast proliferation

Granulocyte colony-stimulating factor and its receptor are needed for skeletal muscle development and injury-induced regeneration in mice.

After skeletal muscle injury, neutrophils, monocytes, and macrophages infiltrate the damaged area; this is followed by rapid proliferation of myoblasts derived from muscle stem cells (also called satellite cells). Although it is known that inflammation triggers skeletal muscle regeneration, the underlying molecular mechanisms remain incompletely understood. In this study, we show that granulocyte colony-stimulating factor (G-CSF) receptor (G-CSFR) is expressed in developing somites. G-CSFR and G-CSF were expressed in myoblasts of mouse embryos during the midgestational stage but not in mature myocytes. Furthermore, G-CSFR was specifically but transiently expressed in regenerating myocytes present in injured adult mouse skeletal muscle. Neutralization of endogenous G-CSF with a blocking antibody impaired the regeneration process, whereas exogenous G-CSF supported muscle regeneration by promoting the proliferation of regenerating myoblasts. Furthermore, muscle regeneration was markedly impaired in G-CSFR–knockout mice. These findings indicate that G-CSF is crucial for skeletal myocyte development and regeneration and demonstrate the importance of inflammation-mediated induction of muscle regeneration.

Relationship between the cAMP levels in leukocytes and the cytokine balance in patients surviving gram negative bacterial pneumonia

Lipopolysaccharide-stimulated leukocytes secrete proinflammatory cytokines including tumor necrosis factor-α and interleukin-12. Over-activation of host defense systems may result in severe tissue damage and requires regulation. Granulocyte colony-stimulating factor and interleukin-10 are candidate cytokines for inducing tolerance to lipopolysaccharide re-stimulation. We compared cytokines secreted by lipopolysaccharide-stimulated blood cells from patients who had survived gram negative bacterial pneumonia (Pseudomonas aeruginosa, Escherichia coli or Proteus mirabilis, n = 26) and age-matched healthy volunteers (n = 18). Interleukin-12p70 and tumor necrosis factor-α expression was significantly lower in patients (p = 0.0039 and p<0.001) compared to healthy controls, while granulocyte colony-stimulating factor production was markedly higher in patients (p<0.001). Levels of interleukin-10 were comparable. Granulocyte colony-stimulating factor expression was inversely correlated with interleukin-12p70 (R = -0.71, p<0.001) and tumor necrosis factor-α (R = -0.64, p<0.001) expression; interleukin-10 showed no significant correlation. In unstimulated leukocytes from patients, cAMP levels were significantly raised (p = 0.020) and were correlated inversely with interleukin-12p70 levels (R = -0.81, p<0.001) and directly with granulocyte colony-stimulating factor (R = 0.72, p = 0.0020), matrix metalloproteinase-9 (R = 0.67, p = 0.0067) and interleukin-10 (R = 0.54, p = 0.039) levels. Our results demonstrate that granulocyte colony-stimulating factor production by lipopolysaccharide-stimulated leukocytes is a useful indicator of tolerance induction in surviving pneumonia patients and that measuring cAMP in freshly isolated leukocytes may also be clinically significant.

Inhibition by rapamycin of the lipoteichoic acid-induced granulocyte-colony stimulating factor expression in mouse macrophages

Granulocyte-colony stimulating factor (G-CSF) is a cytokine which involves in anti-inflammation and inflammation as well. Rapamycin is an inhibitor of mTOR which also plays a role in innate immunity. This study investigated the effect of rapamycin on the lipoteichoic acid (LTA)-induced expression of G-CSF in macrophages and its underlying mechanism. Our data show that LTA induced G-CSF expression in RAW264.7 and bone marrow-derived macrophages and that this effect was inhibited by rapamycin. Analysis of the G-CSF 5' flanking sequence revealed that the -283 to +35 fragment, which contains CSF and octamer elements, was required for maximal promoter activity in response to LTA stimulation. Western blot analyses of proteins that bind to the CSF and octamer element show that LTA increased protein levels of NF-κB, C/EBPβ and Oct-2, and that rapamycin inhibited the LTA-induced increase in Oct-2 protein levels, but not the others. Knockdown of Oct-2 by RNA interference resulted in a decrease in LTA-induced G-CSF mRNA levels. Moreover, forced expression of Oct-2 by transfection with the pCG-Oct-2 plasmid overcame the inhibitory effect of rapamycin on the LTA-induced increase in G-CSF mRNA levels and promoter activity. This study demonstrates that rapamycin reduces G-CSF expression in LTA-treated macrophages by inhibiting Oct-2 expression.

Rapamycin inhibits lipopolysaccharide induction of granulocyte-colony stimulating factor and inducible nitric oxide synthase expression in macrophages by reducing the levels of octamer-binding factor-2

This article reports an inhibitory effect of rapamycin on the lipopolysaccharide (LPS)-induced expression of both inducible nitric oxide synthase (iNOS) and granulocyte-colony stimulating factor (G-CSF) in macrophages and its underlying mechanism. The study arose from an observation that rapamycin inhibited the LPS-induced increase in octamer-binding factor-2 (Oct-2) protein levels through a mammalian target of rapamycin (mTOR)-dependent pathway in mouse RAW264.7 macrophages. As both iNOS and G-CSF are potential Oct-2 target genes, we tested the effect of rapamycin on their expression and found that it reduced the LPS-induced increase in iNOS and G-CSF mRNA levels and iNOS and G-CSF protein levels. Blocking of mTOR-signaling using a dominant-negative mTOR expression plasmid resulted in inhibition of the LPS-induced increase in iNOS and G-CSF protein levels, supporting the essential role of mTOR. Forced expression of Oct-2 using the pCG-Oct-2 plasmid overcame the inhibitory effect of rapamycin on the LPS-induced increase in iNOS and G-CSF mRNA levels. Chromatin immunoprecipitation assays showed that LPS enhanced the binding of Oct-2 to the iNOS and G-CSF promoters and that this effect was inhibited by pretreatment with rapamycin. Moreover, RNA interference knockdown of Oct-2 reduced iNOS and G-CSF expression in LPS-treated cells. The inhibitory effect of rapamycin on the LPS-induced increase in Oct-2 protein levels and on the iNOS and G-CSF mRNA levels was also detected in human THP-1 monocyte-derived macrophages. This study demonstrates that rapamycin reduces iNOS and G-CSF expression at the transcription level in LPS-treated macrophages by inhibiting Oct-2 expression.

Progenitor cell self-renewal and cyclic neutropenia

OBJECTIVES

Cyclic neutropenia (CN) is a rare genetic disorder where patients experience regular cycling of numbers of neutrophils and various other haematopoietic lineages. The nadir in neutrophil count is the main source of problems due to risk of life-threatening infections. Patients with CN benefit from granulocyte colony stimulating factor therapy, although cycling persists. Mutations in neutrophil elastase gene (ELA2) have been found in more than half of patients with CN. However, neither connection between phenotypic expression of ELA2 and CN nor the mechanism of cycling is known.

MATERIALS AND METHODS

Recently, a multicompartment model of haematopoiesis that couples stem cell replication with marrow output has been proposed. In the following, we couple this model of haematopoiesis with a linear feedback mechanism via G-CSF.

RESULTS

We propose that the phenotypic effect of ELA2 mutations leads to reduction in self-renewal of granulocytic progenitors. The body responds by overall relative increase of G-CSF and increasing progenitor cell self-renewal, leading to cell count cycling.

CONCLUSION

The model is compatible with available experimental data and makes testable predictions.

Neutrophil mobilization and clearance in the bone marrow

The bone marrow is the site of neutrophil production, a process that is regulated by the cytokine granulocyte colony-stimulating factor (G-CSF). Mature neutrophils are continually released into the circulation, with an estimated 10(11) neutrophils exiting the bone marrow daily under basal conditions. These leucocytes have a short half-life in the blood of approximately 6.5 hr, and are subsequently destroyed in the spleen, liver and indeed the bone marrow itself. Additionally, mature neutrophils are retained in the bone marrow by the stromal cell-derived factor (SDF-1alpha)/chemokine (C-X-C motif) receptor 4 (CXCR4) chemokine axis and form the bone marrow reserve. Following infection or inflammatory insult, neutrophil release from the bone marrow reserve is substantially elevated and this process is mediated by the co-ordinated actions of cytokines and chemokines. In this review we discuss the factors and molecular mechanisms regulating the neutrophil mobilization and consider the mechanisms and functional significance of neutrophil clearance via the bone marrow.

Triglycerides potentiate the inflammatory response in rat Kupffer cells

Accumulation of fat in the liver, also known as steatosis, may lead to inflammation and tissue damage. Kupffer cells (KCs) are the resident macrophages of the liver and have an important role in inflammatory reactions. The inflammatory response of isolated rat KCs to endotoxin in the presence of lipids was investigated in this study. KCs were treated with lipopolysaccharide (LPS) and triglycerides (TGs) alone or in combination. TGs had no effect on the expression of pro-inflammatory mediators, but adding TGs to LPS enhanced the induction of inducible nitric oxide synthase (iNOS), tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), and granulocyte colony-stimulating factor (G-CSF), compared with LPS treatment alone. Increased DNA binding of NF-kappaB transcription factor was seen on simultaneous exposure of the cells to TGs and LPS, which was accompanied by decreased intracellular ROS production and increased GSH levels. The inflammation-potentiating effect of TGs on iNOS expression was abolished on NF-kappaB inhibition. This enhanced inflammatory response might indicate a contribution of lipids to the inflammatory conditions in the fatty liver by increased activation of KCs.

Serum amyloid A induces G-CSF expression and neutrophilia via Toll-like receptor 2

The acute-phase protein serum amyloid A (SAA) is commonly considered a marker for inflammatory diseases; however, its precise role in inflammation and infection, which often result in neutrophilia, remains ambiguous. In this study, we demonstrate that SAA is a potent endogenous stimulator of granulocyte colony-stimulated factor (G-CSF), a principal cytokine-regulating granulocytosis. This effect of SAA is dependent on Toll-like receptor 2 (TLR2). Our data demonstrate that, in mouse macrophages, both G-CSF mRNA and protein were significantly increased after SAA stimulation. The induction of G-CSF was blocked by an anti-TLR2 antibody and markedly decreased in the TLR2-deficient macrophages. SAA stimulation results in the activation of nuclear factor-kappaB and binding activity to the CK-1 element of the G-CSF promoter region. In vitro reconstitution experiments also support that TLR2 mediates SAA-induced G-CSF expression. In addition, SAA-induced secretion of G-CSF was sensitive to heat and proteinase K treatment, yet insensitive to polymyxin B treatment, indicating that the induction is a direct effect of SAA. Finally, our in vivo studies confirmed that SAA treatment results in a significant increase in plasma G-CSF and neutrophilia, whereas these responses are ablated in G-CSF- or TLR2-deficient mice.

Induction of granulocyte colony-stimulating factor by globular adiponectin via the MEK-ERK pathway

Adiponectin, an adipocyte-derived cytokine, affects a number of physiological processes, including immune function and inflammation. We investigated whether globular adiponectin (gAd) affects the expression of inflammation-related genes in murine macrophages (RAW264 cells). DNA microarray analysis indicated that granulocyte colony-stimulating factor (G-CSF) showed the largest increase in expression in gAd-stimulated RAW264 cells. The gAd-induced secretion of G-CSF increased in a time- and dose-dependent manner. U0126 (MEK1/2 inhibitor) and PD98059 (MEK1 inhibitor) reduced the gAd-induced G-CSF mRNA expression and G-CSF protein production. gAd induced the phosphorylation of MEK1/2 and ERK1/2 in RAW264 cells. In addition, the gAd-induced phosphorylation of MEK1/2 and ERK1/2 was dramatically reduced by PD98059 and U0126, respectively. Collectively, these results suggest that MEK1/2-ERK1/2 signaling is involved in the adiponectin-induced secretion of G-CSF.

The role of the bone marrow in neutrophil clearance under homeostatic conditions in the mouse

In humans, 10(11) neutrophils are released from the bone marrow per day, and these cells have a half-life in the blood of only approximately 6.5 h. Although it is generally believed that neutrophils are cleared from the circulation via the liver and spleen, in this study using (111)In-labeled senescent neutrophils, we show that in mice, 32% of neutrophils are cleared from the circulation via the bone marrow. We have previously shown that senescent neutrophils home to the bone marrow in a CXCR4-dependent manner, and we show here that pretreatment of neutrophils with pertussis toxin significantly inhibits neutrophil clearance via the bone marrow (75%), consistent with a role for chemokines in this process. By labeling senescent neutrophils with inert fluorescent microspheres, we have tracked their fate and shown that in vivo, they are ultimately phagocytosed by bone marrow stromal macrophages. Finally, we show that under noninflammatory conditions, circulating levels of neutrophils are regulated by granulocyte-colony stimulating factor (G-CSF), but not interleukin-17. Interestingly, we report that the uptake of apoptotic neutrophils by bone marrow macrophages stimulates their production of G-CSF in vitro. Taken together, these data provide evidence that the bone marrow represents a major site of neutrophil clearance in mice.

Differential effects of antibiotics in combination with G-CSF on survival and polymorphonuclear granulocyte cell functions in septic rats

BACKGROUND

In addition to their antimicrobial activity, antibiotics modulate cellular host defence. Granulocyte-colony stimulating factor (G-CSF) is also a well known immunomodulator; however little is known about the interactions of G-CSF with antibiotics. We investigated in septic rats the effects of two antibiotic combinations with G-CSF.

METHODS

In two clinic modelling randomised trials (CMRTs), male Wistar rats were anesthetized, given antibiotic prophylaxis, had a laparotomy with peritoneal contamination and infection (PCI), and were randomly assigned (n = 18 rats/group) to: 1) PCI only; 2) PCI+antibiotic; and, 3) PCI+antibiotic+G-CSF prophylaxis (20 mug/kg, three times). This sequence was conducted first with 10 mg/kg coamoxiclav, and then with ceftriaxone/metronidazole (Cef/met, 10/3 mg/kg). In additional animals, the blood cell count, migration and superoxide production of PMNs, systemic TNF-alpha and liver cytokine mRNA expression levels were determined.

RESULTS

Only the combination coamoxiclav plus G-CSF improved the survival rate (82 vs. 44%, p < 0.001). Improved survival with this combination was accompanied by normalised antimicrobial PMN migratory activity and superoxide production, along with normalised systemic TNF-alpha levels and a reduced expression of TNF-alpha and IL-1 in the liver.

CONCLUSION

There are substantial differences in the interaction of antibiotics with G-CSF. Therefore, the selection of the antibiotic for combination with G-CSF in sepsis treatment should be guided not only by the bacteria to be eliminated, but also by the effects on antimicrobial functions of PMNs and the cytokine response.

The multiple roles of osteoclasts in host defense: bone remodeling and hematopoietic stem cell mobilization

Bone remodeling by bone-forming osteoblasts and bone-resorbing osteoclasts dynamically alters the bone inner wall and the endosteum region, which harbors osteoblastic niches for hematopoietic stem cells. Investigators have recently elucidated mechanisms of recruitment and mobilization; these mechanisms consist of stress signals that drive migration of leukocytes and progenitor cells from the bone marrow reservoir to the circulation and drive their homing to injured tissues as part of host defense and repair. The physical bone marrow vasculature barrier that is crossed by mobilized cells actively transmits chemotactic signals between the blood and the bone marrow, facilitating organ communication and cell trafficking. Osteoclasts play a dual role in regulation of bone resorption and homeostatic release or stress-induced mobilization of hematopoietic stem/progenitor cells. In this review, we discuss the orchestrated interplay between bone remodeling, the immune system, and the endosteal stem cell niches in the context of stem cell proliferation and migration during homeostasis, which are accelerated during alarm situations.

The neutrophil/Th1 lymphocyte balance and the therapeutic effect of granulocyte colony-stimulating factor in TNBS-induced colitis of rat strains

Intramucosal neutrophil infiltration is related to the activity of ulcerative colitis, and Th1 immunity is responsible for the onset of Crohn's disease. We examined the therapeutic effects of recombinant human granulocyte colony-stimulating factor (rHuG-CSF) in the two types of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis of five rat strains. SD and DA rats showed much lower mRNA expression levels of endogenous G-CSF in lipopolysaccharide (LPS)-stimulated splenocytes than did Lewis, F344, and BN rats. On day 7 after anal instillation of TNBS, SD and DA rats demonstrated massive lymphocyte infiltration with an interferon-gamma (IFN-gamma) mRNA upregulation, whereas Lewis, F344, and BN rats showed an intense submucosal neutrophil accumulation with high tumor necrosis factor-alpha (TNF-alpha) mRNA levels. A 5-day course of rHuG-CSF pretreatment (250 microg/kg/day, s.c.) reduced the elevated levels of both cytokines. The treatment improved the survival rate of DA and reduced the degree of body weight loss of SD, while not significantly influencing the wasting disease of other strains. Interleukin-10 (IL-10) mRNA levels were highly upregulated by rHuG-CSF treatment on day 1 in the neutrophil-dominant lesions of F344 but not in the Th1-type lesions of SD, and IL-12p35 mRNA levels were downregulated in both. A supply of G-CSF prevents the onset of Th1-type TNBS colitis and does not deteriorate neutrophil-dominant chronic colitis in hosts showing higher expression of endogenous G-CSF.

Potentiation of neurogenesis and angiogenesis by G-CSF after focal cerebral ischemia in rats

Recently, granulocyte colony-stimulating factor (G-CSF) is expected to demonstrate beneficial effects on cerebral ischemia. Here, we showed the potential benefit of G-CSF administration after transient middle cerebral artery occlusion (tMCAO). Adult male Wistar rats received vehicle or G-CSF (50 microg/kg) subcutaneously after reperfusion, and were treated with 5-bromodeoxyuridine (BrdU, 50 mg/kg) once daily by the intraperitoneal route for 3 days after tMCAO. Nissl-stained sections at 7 days after tMCAO showed significant reduction of the infarction area (31%, P<0.01). At 7 days after tMCAO, BrdU plus NeuN double-positive cells increased by 43.3% in the G-CSF-treated group (P<0.05), and BrdU-positive endothelial cells were increased 2.29 times in the G-CSF-treated group, to a level as high as that in the vehicle-treated group (P<0.01), in the periischemic area. Our results indicate that G-CSF caused potentiation of neuroprotection and neurogenesis and is expected to have practical therapeutic potential in treating individuals after ischemic brain injury.

Increased local levels of granulocyte colony-stimulating factor are associated with the beneficial effect of pre-elafin (SKALP/trappin-2/WAP3) in experimental emphysema

Few therapeutic options are offered to treat inflammation and alveolar wall destruction in emphysema. The effect of recombinant human pre-elafin, an elastase inhibitor, was evaluated in porcine pancreatic elastase (PPE)-induced emphysema in C57BL/6 mice. In a first protocol, mice received a single instillation of pre-elafin (17.5 pmol/mouse) at 1 h post-PPE and were sacrificed up to 72 h post-PPE. A single instillation of pre-elafin significantly reduced PPE-induced neutrophil accumulation in lungs, as assessed by bronchoalveolar lavage (BAL), by 51%, 71% and 67% at 24, 48 and 72 h, respectively. In a second protocol, mice also received a single dose of PPE, but pre-elafin three times a week for 2 weeks. After 2 weeks, pre-elafin significantly reduced the PPE-induced increase in BAL macrophage numbers, airspace dimensions and lung hysteresivity by 74%, 62% and 52%, respectively. Since G-CSF was previously shown to reduce emphysematous changes in mice, the BAL levels of this mediator were measured 6 h post-PPE in animals treated as described in the first protocol. Pre-elafin significantly increased G-CSF levels in PPE-exposed mice compared to sham- and PPE only-exposed animals. This suggests that the beneficial effects of pre-elafin could be mediated, at least in part, by its ability to increase G-CSF levels in the lung.

A new strategy for the synthesis of dinucleotides loaded with glycosylated amino acids--investigations on in vitro non-natural amino acid mutagenesis for glycoprotein synthesis

The in vitro non-natural amino acid mutagenesis method provides the opportunity to introduce non-natural amino acids site-specifically into proteins. To this end, a chemically synthesised aminoacylated dinucleotide is enzymatically ligated to a truncated suppressor transfer RNA. The loaded suppressor tRNA is then used in translation reactions to read an internal stop codon. Here we report an advanced and general strategy for the synthesis of the aminoacyl dinucleotide. The protecting group pattern developed for the dinucleotide facilitates highly efficient aminoacylation, followed by one-step global deprotection. The strategy was applied to the synthesis of dinucleotides loaded with 2-acetamido-2-deoxy-glycosylated amino acids, including N- and O-beta-glycosides and O- and C-alpha-glycosides of amino acids, thus enabling the extension of in vitro non-natural amino acid mutagenesis towards the synthesis of natural glycoproteins of high biological interest. We demonstrate the incorporation of the glycosylamino acids--although with low suppression efficiency--into the human interleukin granulocyte-colony stimulating factor (hG-CSF), as verified by the ELISA technique.

EFFECT OF THERMAL INJURY ON SPLENIC MYELOPOIESIS

Thermal injury increases the number of macrophage progenitors in the bone marrow but leads to a decrease in the number of granulocyte progenitors. In the spleen, thermal injury increases the numbers of myeloid progenitors, but the lineage commitment of these cells is unknown. In this study mice were given a scald burn, and the number of splenic myeloid progenitors as well as their progeny was determined. BrdU uptake was used to monitor the de novo production of splenocytes for 8 days after the burn. Burn injury increased the numbers of splenic granulocyte-macrophage (GM), granulocyte (G), and macrophage (M) progenitors at postburn day 8 by 12-, 11-, and 18-fold, respectively. Scald injury increased the number of mature PMN (CD11b GR1(bright)) in the spleen and increased the number of white pulp monocyte/macrophages. Increased numbers of BrdU-positive PMN and monocyte/macrophages were seen after injury. Burn macrophages produced increased levels of the anti-inflammatory hematopoietic cytokine G-CSF. Our work clearly shows that the increased myelopoiesis observed postinjury leads to the production of mature myeloid cells. However, the effects of thermal injury on progenitors in the spleen and marrow are not equivalent.

Association of endogenous G-CSF with anti-inflammatory mediators in patients with acute respiratory distress syndrome

Upregulation of the anti-inflammatory mediators, soluble tumor necrosis factor-alpha receptors I and II (sTNFRI/RII) and interleukin-1 receptor antagonist (IL-1RA), by granulocyte colony-stimulating factor (G-CSF) may contribute to the pathophysiology of lung injury. We determined the relation of endogenous G-CSF to proinflammatory and anti-inflammatory mediators in bronchoalveolar lavage fluid (BALF) and serum of patients with acute respiratory distress syndrome (ARDS) and acute lung injury (ALI). Nineteen patients with ARDS and 10 with ALI were included in this prospective investigation. BAL was performed within 12 h and 24 h after onset of lung injury. Concentrations of G-CSF, TNF-alpha, IL-6, sTNFRI and sTNFRII, IL-1RA and IL-10 in BALF as well as in serum were determined by ELISA. G-CSF was associated with alveolar neutrophilia. Results in patients with ARDS and ALI exhibited significant positive correlations in BALF of G-CSF levels with that of IL-6, sTNFRII, and IL-1RA and of G-CSF levels in serum with that of serum IL-6, IL-1RA, and IL-10. Given the potential of G-CSF to directly induce anti-inflammatory cytokines in vitro, significant associations of endogenous G-CSF levels with these mediators early in the development of severe lung injury suggest an endogenous anti-inflammatory role of G-CSF in vivo.

Dependence of Positive Effects of Granulocyte Colony-stimulating Factor on the Antibiotic Regimen: Evaluation in Rats with Polymicrobial Peritonitis

We tested the hypothesis that the ability of granulocyte colony-stimulating factor (G-CSF) to prevent death from fecal peritonitis is influenced by the composition of the antibiotic regimen with which it is administered. We used a rodent model of polymicrobial peritoneal contamination and infection and the concept of clinical modeling randomized trials (CMRTs), which includes the conditions of randomized, clinical trials and complex clinical interventions (e.g., anesthesia, volume substitution, antibiotics, surgery, postoperative analgesia). With the peritonitis model we obtained a mortality dose-response curve that was sensitive to antibiotic prophylaxis. G-CSF was most efficacious when it was administered both prophylactically and after the onset of peritonitis. Cefuroxime/metronidazole, ofloxacin/metronidazole, and amoxicillin/clavulanate improved survival in combination with G-CSF best, whereas cefotaxime or ceftriaxone with and without metronidazole did not. G-CSF administration was associated with improved polymorphonuclear neutrophil phagocytosis and enhanced bacterial clearance. Pro-inflammatory cytokine release (tumor necrosis factor-a, interleukin-6, macrophage inflammatory protein-2) was decreased in plasma and in the peritoneal fluid. Their expression was lowered in various organs on the protein and mRNA level. The results were used to design a clinical trial to test the ability of G-CSF to prevent serious infections in patients with colorectal cancer surgery. In this trial G-CSF application and antibiotic prophylaxis were performed with the most effective scheduling and combinations (cefuroxime/metronidazole and ofloxacin/metronidazole) as defined here.

Alveolar granulocyte colony-stimulating factor and alpha-chemokines in relation to serum levels, pulmonary neutrophilia, and severity of lung injury in ARDS

OBJECTIVES

To determine granulocyte colony-stimulating factor (G-CSF), epithelial neutrophil-activating peptide (ENA)-78, and interleukin (IL)-8 in BAL fluid (BALF), epithelial lining fluid (ELF), and serum for establishing the concentration gradient of G-CSF, ENA-78, and IL-8 between the blood and the alveolar space in ARDS and acute lung injury (ALI); and to evaluate the relationship of G-CSF, IL-8, and ENA-78 to pulmonary neutrophilia and severity of lung injury.

DESIGN

Prospective study.

SETTING

An adult trauma/surgical ICU.

PATIENTS

Nineteen patients with ARDS and 10 patients with ALI.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

BAL and blood sampling simultaneously within 12 h and 24 h after onset of ARDS/ALI; G-CSF was detected in BALF in 18 of 19 patients with ARDS, in 7 of 10 patients with ALI, and in all serum samples. G-CSF in BALF and serum was significantly higher in ARDS than in ALI. ENA-78 was detected in BALF in 14 of 19 patients with ARDS, in 8 of 10 patients with ALI, and in serum of all patients. Levels in BALF and serum were not different between ARDS and ALI. IL-8 was detected in all patients; concentrations in BALF in ARDS were significantly higher than in ALI. Concentrations of G-CSF, ENA-78, and IL-8 in ELF were significantly higher than in serum. G-CSF in BALF and serum and IL-8 in BALF correlated positively with pulmonary neutrophilia. G-CSF in serum and IL-8 in BALF correlated negatively with PaO(2)/fraction of inspired oxygen (FIO(2)) ratio. However, ENA-78 did not show a correlation with neutrophil count or with PaO(2)/FIO(2) ratio.

CONCLUSIONS

G-CSF may be pathophysiologically important for accumulation and activation of neutrophils in ARDS. Local G-CSF production is the likely driving force for neutrophils rather than elevation of circulating levels. In comparison to ENA-78, IL-8 seems to be the predominant neutrophil chemoattractant in the early phase of ARDS.