Endogenous Interleukin-8 (IL-8) Surge in Granulocyte Colony-Stimulating Factor–Induced Peripheral Blood Stem Cell Mobilization

SARS-CoV-2-Infection (COVID-19): Clinical Course, Viral Acute Respiratory Distress Syndrome (ARDS) and Cause(s) of Death

SARS-CoV-2-infected symptomatic patients often suffer from high fever and loss of appetite which are responsible for the deficit of fluids and of protein intake. Many patients admitted to the emergency room are, therefore, hypovolemic and hypoproteinemic and often suffer from respiratory distress accompanied by ground glass opacities in the CT scan of the lungs. Ischemic damage in the lung capillaries is responsible for the microscopic hallmark, diffuse alveolar damage (DAD) characterized by hyaline membrane formation, fluid invasion of the alveoli, and progressive arrest of blood flow in the pulmonary vessels. The consequences are progressive congestion, increase in lung weight, and progressive hypoxia (progressive severity of ARDS). Sequestration of blood in the lungs worsens hypovolemia and ischemia in different organs. This is most probably responsible for the recruitment of inflammatory cells into the ischemic peripheral tissues, the release of acute-phase mediators, and for the persistence of elevated serum levels of positive acute-phase markers and of hypoalbuminemia. Autopsy studies have been performed mostly in patients who died in the ICU after SARS-CoV-2 infection because of progressive acute respiratory distress syndrome (ARDS). In the death certification charts, after respiratory insufficiency, hypovolemic heart failure should be mentioned as the main cause of death.

Etoposide-mediated interleukin-8 secretion from bone marrow stromal cells induces hematopoietic stem cell mobilization

Background

We assessed the mechanism of hematopoietic stem cell (HSC) mobilization using etoposide with granulocyte-colony stimulating factor (G-CSF), and determined how this mechanism differs from that induced by cyclophosphamide with G-CSF or G-CSF alone.

Methods

We compared the clinical features of 173 non-Hodgkin’s lymphoma patients who underwent autologous peripheral blood stem cell transplantation (auto-PBSCT). Additionally, we performed in vitro experiments to assess the changes in human bone marrow stromal cells (hBMSCs), which support the HSCs in the bone marrow (BM) niche, following cyclophosphamide or etoposide exposure. We also performed animal studies under standardized conditions to ensure the following: exclude confounding factors, mimic the conditions in clinical practice, and identify the changes in the BM niche caused by etoposide-induced chemo-mobilization or other mobilization methods.

Results

Retrospective analysis of the clinical data revealed that the etoposide with G-CSF mobilization group showed the highest yield of CD34+ cells and the lowest change in white blood cell counts during mobilization. In in vitro experiments, etoposide triggered interleukin (IL)-8 secretion from the BMSCs and caused long-term BMSC toxicity. To investigate the manner in which the hBMSC-released IL-8 affects hHSCs in the BM niche, we cultured hHSCs with or without IL-8, and found that the number of total, CD34+, and CD34+/CD45- cells in IL-8-treated cells was significantly higher than the respective number in hHSCs cultured without IL-8 (p = 0.014, 0.020, and 0.039, respectively). Additionally, the relative expression of CXCR2 (an IL-8 receptor), and mTOR and c-MYC (components of IL-8-related signaling pathways) increased 1 h after IL-8 treatment. In animal studies, the etoposide with G-CSF mobilization group presented higher IL-8-related cytokine and MMP9 expression and lower SDF-1 expression in the BM, compared to the groups not treated with etoposide.

Conclusion

Collectively, the unique mechanism of etoposide with G-CSF-induced mobilization is associated with IL-8 secretion from the BMSCs, which is responsible for the enhanced proliferation and mobilization of HSCs in the bone marrow; this was not observed with mobilization using cyclophosphamide with G-CSF or G-CSF alone. However, the long-term toxicity of etoposide toward BMSCs emphasizes the need for the development of more efficient and safe chemo-mobilization strategies.

Longitudinal relationships between rheumatoid factor and cytokine expression by immunostimulated peripheral blood lymphocytes from patients with rheumatoid arthritis: New insights into B-cell activation

To identify associations between immunostimulated cytokine production and disease characteristics, peripheral blood lymphocytes were collected from 155 adult patients with rheumatoid arthritis (RA) before and after a 5-year interval. The lymphocytes were activated in vitro with T-cell stimulants, cytosine-phosphate-guanine (CpG) oligonucleotide, and medium alone (negative control). Expression of 17 cytokines was evaluated with immunoassays, and factor analysis was used to reduce data complexity and identify cytokine combinations indicative of cell types preferentially activated by each immunostimulant. The findings showed that the highest numbers of correlations were between cytokine levels and rheumatoid factor (RF) positivity and between cytokine levels and disease duration. Scores for cytokines driven by CpG and medium alone were negatively associated with RF positivity and disease duration at baseline but positively associated with both at 5 years. Our findings suggest that RF expression sustained over time increases activation of B cells and monocytes without requirements for T-cell functions.

The Biological and Clinical Relevance of G Protein-Coupled Receptors to the Outcomes of Hematopoietic Stem Cell Transplantation: A Systematized Review

Hematopoietic stem cell transplantation (HSCT) remains the only curative treatment for several malignant and non-malignant diseases at the cost of serious treatment-related toxicities (TRTs). Recent research on extending the benefits of HSCT to more patients and indications has focused on limiting TRTs and improving immunological effects following proper mobilization and engraftment. Increasing numbers of studies report associations between HSCT outcomes and the expression or the manipulation of G protein-coupled receptors (GPCRs). This large family of cell surface receptors is involved in various human diseases. With ever-better knowledge of their crystal structures and signaling dynamics, GPCRs are already the targets for one third of the current therapeutic arsenal. The present paper assesses the current status of animal and human research on GPCRs in the context of selected HSCT outcomes via a systematized survey and analysis of the literature.

Assessment of Neutrophil Chemotaxis Upon G-CSF Treatment of Healthy Stem Cell Donors and in Allogeneic Transplant Recipients

Neutrophils are crucial for the human innate immunity and constitute the majority of leukocytes in circulation. Thus, blood neutrophil counts serve as a measure for the immune system's functionality. Hematological patients often have low neutrophil counts due to disease or chemotherapy. To increase neutrophil counts and thereby preventing infections in high-risk patients, recombinant G-CSF is widely used as adjunct therapy to stimulate the maturation of neutrophils. In addition, G-CSF is utilized to recruit stem cells (SCs) into the peripheral blood of SC donors. Still, the actual functionality of neutrophils resulting from G-CSF treatment remains insufficiently understood. We tested the ex vivo functionality of neutrophils isolated from blood of G-CSF-treated healthy SC donors. We quantified chemotaxis, oxidative burst, and phagocytosis before and after treatment and detected significantly reduced chemotactic activity upon G-CSF treatment. Similarly, in vitro treatment of previously untreated neutrophils with G-CSF led to reduced chemotactic activity. In addition, we revealed that this effect persists in the allogeneic SC recipients up to 4 weeks after neutrophil engraftment. Our data indicates that neutrophil quantity, as a sole measure of immunocompetence in high-risk patients should be considered cautiously as neutrophil functionality might be affected by the primary treatment.

Cytokine Measurements for Diagnosing and Characterizing Leukemoid Reactions and Immunohistochemical Validation of a Granulocyte Colony-Stimulating Factor and CXCL8-Producing Renal Cell Carcinoma

Background

Various paraneoplastic syndromes are encountered in renal cell carcinomas. This case report illustrates that a paraneoplastic leukemoid reaction may precede the diagnosis of renal cell carcinoma and be explained by cytokine production from the cancer cells.

Case presentations

A 64-year-old man was referred for hematology workup due to pronounced leukocytosis. While being evaluated for a possible hematologic malignancy as the cause, he was found to have a metastasized renal cell carcinoma, and hyperleukocytosis was classified as a leukemoid reaction. A multiplex panel for measurement of 25 serum cytokines/chemokines showed highly elevated levels of granulocyte colony-stimulating factor (G-CSF) and CXCL8 (C-X-C-motif chemokine ligand 8, previously known as interleukin [IL]-8). By immunohistochemistry it was shown that the renal carcinoma cells expressed both these cytokines. Two additional, consecutive patients with renal cell carcinoma with paraneoplastic leukocytosis also showed elevated serum levels of CXCL8, but not of G-CSF. Nonparametric statistical evaluation showed significantly higher serum concentrations of CXCL8, IL-6, IL-10, monocyte chemoattractant protein 1 (MCP-1), and tumor necrosis factor, but lower interferon gamma (IFN-γ) and IL-1α, for the 3 renal cell carcinoma cases compared with healthy blood donors.

Conclusions

In suspected paraneoplastic leukocytosis, multiplex serum cytokine analyses may facilitate diagnosis and provide an understanding of the mechanisms for the reaction. In the index patient, combined G-CSF and CXCL8 protein expression by renal carcinoma cells was uniquely documented. A rapidly fatal course was detected in all 3 cases, congruent with the concept that autocrine/paracrine growth signaling in renal carcinoma cells may induce an aggressive tumor phenotype. Immune profiling studies could improve our understanding for possible targets when choosing therapies for patients with metastatic renal cell carcinoma.

The atrial appendage as a suitable source to generate cardiac-derived adherent proliferating cells for regenerative cell-based therapies

Cardiac-derived adherent proliferating (CardAP) cells obtained from endomyocardial biopsies (EMBs) with known anti-fibrotic and pro-angiogenic properties are good candidates for the autologous therapy of end-stage cardiac diseases such as dilated cardiomyopathy. However, due to the limited number of CardAP cells that can be obtained from EMBs, our aim is to isolate cells with similar properties from other regions of the heart with comparable tissue architecture. Here, we introduce the atrial appendage as a candidate region. Atrial appendage-derived cells were sorted with CD90 microbeads to obtain a CD90^low cell population, which were subsequently analysed for their surface marker and gene expression profiles via flow cytometry and micro array analysis. Enzyme-linked immunosorbent assays for vascular endothelial growth factor and interleukin-8 as well as tube formation assays were performed to investigate pro-angiogenic properties. Furthermore, growth kinetic assays were performed to estimate the cell numbers needed for cell-based products. Microarray analysis revealed the expression of numerous pro-angiogenic genes and strong similarities to CardAP cells with which they also share expression levels of defined surface antigens, that is, CD29⁺ , CD44⁺ , CD45^- , CD73⁺ , CD90^low , CD105⁺ , and CD166⁺ . High secretion levels of vascular endothelial growth factor and interleukin-8 as well as improved properties of vascular structures in vitro could be detected. Based on growth parameters, cell dosages for the treatment of more than 250 patients are possible using one appendage. These results lead to the conclusion that isolating cells with regenerative characteristics from atrial appendages is feasible and permits further investigations towards allogenic cell-based therapies.

Mobilization and collection of CD34(+) cells for autologous transplantation of peripheral blood hematopoietic progenitor cells in children: analysis of two different granulocyte-colony stimulating factor doses

INTRODUCTION

The use of peripheral hematopoietic progenitor cells (HPCs) is the cell choice in autologous transplantation. The classic dose of granulocyte-colony stimulating factor (G-CSF) for mobilization is a single daily dose of 10μg/kg of patient body weight. There is a theory that higher doses of granulocyte-colony stimulating factor applied twice daily could increase the number of CD34(+) cells collected in fewer leukapheresis procedures.

OBJECTIVE

The aim of this study was to compare a fractionated dose of 15μg G-CSF/kg of body weight and the conventional dose of granulocyte-colony stimulating factor in respect to the number of leukapheresis procedures required to achieve a minimum collection of 3×10(6) CD34(+) cells/kg body weight.

METHODS

Patients were divided into two groups: Group 10 - patients who received a single daily dose of 10μg G-CSF/kg body weight and Group 15 - patients who received a fractioned dose of 15μg G-CSF/kg body weight daily. The leukapheresis procedure was carried out in an automated cell separator. The autologous transplantation was carried out when a minimum number of 3×10(6) CD34(+) cells/kg body weight was achieved.

RESULTS

Group 10 comprised 39 patients and Group 15 comprised 26 patients. A total of 146 apheresis procedures were performed: 110 (75.3%) for Group 10 and 36 (24.7%) for Group 15. For Group 10, a median of three (range: 1-7) leukapheresis procedures and a mean of 8.89×10(6) CD34(+) cells/kg body weight (±9.59) were collected whereas for Group 15 the corresponding values were one (range: 1-3) and 5.29×10(6) cells/kg body weight (±4.95). A statistically significant difference was found in relation to the number of apheresis procedures (p-value <0.0001).

CONCLUSIONS

To collect a minimum target of 3×10(6) CD34(+) cells/kg body weight, the administration of a fractionated dose of 15μg G-CSF/kg body weight significantly decreased the number of leukapheresis procedures performed.

Inflammatory markers, oxidative stress, and antioxidant capacity in healthy allo-HSCT donors during hematopoietic stem cell mobilization

The aim of this study is to investigate the impact of mobilization with granulocyte colony stimulating factor (G-CSF) and apheresis procedure on inflammatory and oxidative stress markers, and antioxidant capacity in healthy allo-HSCT donors. The study was conducted in the Stem Cell Transplantation Unit of Gazi University Hospital between October 2010 and March 2011, and 25 consecutive allo-HSCT donors were included. The alteration in the serum levels of iron, iron binding capacity, albumin, ferritin, IL-6, hs-CRP, TAC, MDA, and AOPP were determined at five different time points. (1) Prior to the first dose of G-CSF (T0), (2) preapheresis (on the fourth day of G-CSF before the apeheresis procedure) (T1), (3) immediately postapheresis (T2), (4) 24 h postapheresis (T3), and (5) a week after apheresis (T4). Serum ferritin levels increased steadily after administration of G-CSF and remained high up toT4. Both serum IL-6 and hs-CRP levels began to increase in the T1 sampling and reached to a maximum level at T3 and decreased even below the basal levels at T4. Serum AOPP levels decreased at preapheresis and postapheresis time points, while they increased at T3 and T4 samples. Serum MDA levels decreased at T1, T2, T3, and T4 samples. Serum TAC increased significantly and steadily at all time points post G-CSF. In conclusion; mobilization with G-CSF and apheresis caused a transient inflammatory reaction and a protein limited oxidative stress in healthy allo-HCT donors.

Progenitor cell mobilization after exercise is related to systemic levels of G-CSF and muscle damage

Different types of exercise are characterized by the ability to induce specific physiological stimuli that might be able to induce the mobilization of progenitor cells. The aim of the current study was to investigate the mobilization of hematopoietic progenitor cells (HPCs) and endothelial progenitor cells (EPCs) in response to endurance, resistance, and eccentric endurance exercise and their relation to markers of muscle damage and inflammation. Healthy male subjects performed acute bouts of either endurance exercise, resistance exercise, or eccentric endurance exercise. Numbers of progenitor cells and several markers of muscle damage and inflammation were determined. Although the endurance exercise was followed by an immediate and short increase of both HPCs and EPCs, the eccentric exercise evoked a long lasting increase up to 24 h for HPCs and 48 h for EPCs (P < 0.05). After resistance exercise, an increase of HPCs was only found 3 h after exercise (P < 0.05). A correlation was found between mobilized progenitor cells and systemic levels of granulocyte colony-stimulating factor (G-CSF) levels (r = 0.54 and r = 0.51, P < 0.05) as well as for HPCs and creatine kinase levels (r = 0.57, P < 0.05). These results suggest that mobilization of progenitor cells is related to the type of exercise and possibly mediated by G-CSF and muscle damage.

Overcoming the response plateau in multiple myeloma: a novel bortezomib-based strategy for secondary induction and high-yield CD34+ stem cell mobilization

PURPOSE

This phase II study evaluated bortezomib-based secondary induction and stem cell mobilization in 38 transplant-eligible patients with myeloma who had an incomplete and stalled response to, or had relapsed after, previous immunomodulatory drug-based induction.

EXPERIMENTAL DESIGN

Patients received up to six 21-day cycles of bortezomib plus dexamethasone, with added liposomal doxorubicin for patients not achieving partial response or better by cycle 2 or very good partial response or better (≥VGPR) by cycle 4 (DoVeD), followed by bortezomib, high-dose cyclophosphamide, and filgrastim mobilization. Gene expression/signaling pathway analyses were conducted in purified CD34+ cells after bortezomib-based mobilization and compared against patients who received only filgrastim ± cyclophosphamide. Plasma samples were similarly analyzed for quantification of associated protein markers.

RESULTS

The response rate to DoVeD relative to the pre-DoVeD baseline was 61%, including 39% ≥ VGPR. Deeper responses were achieved in 10 of 27 patients who received bortezomib-based mobilization; postmobilization response rate was 96%, including 48% ≥ VGPR, relative to the pre-DoVeD baseline. Median CD34+ cell yield was 23.2 × 10(6) cells/kg (median of 1 apheresis session). After a median follow-up of 46.6 months, median progression-free survival was 47.1 months from DoVeD initiation; 5-year overall survival rate was 76.4%. Grade ≥ 3 adverse events included thrombocytopenia (13%), hand-foot syndrome (11%), peripheral neuropathy (8%), and neutropenia (5%). Bortezomib-based mobilization was associated with modulated expression of genes involved in stem cell migration.

CONCLUSION

Bortezomib-based secondary induction and mobilization could represent an alternative strategy for elimination of tumor burden in immunomodulatory drug-resistant patients that does not impact stem cell yield.

G-CSF-activated STAT3 enhances production of the chemokine MIP-2 in bone marrow neutrophils

Neutrophil mobilization from the bone marrow is a critical aspect of the innate immune response, enabling a rapid deployment of phagocytes to infected or inflamed tissue. The cytokine G-CSF, which is induced rapidly during infection, elicits a swift and potent mobilizing response, yet its mechanisms of action remain poorly understood. Here, we studied the role of G-CSF and its principal signal transducer STAT3 in regulating expression of the neutrophil chemoattractant MIP-2. Our studies revealed Gr-1(hi) mature neutrophils as major sources of Cxcl2 (MIP-2) mRNA in bone marrow and G-CSF-responsive MIP-2 protein production. Induction of Cxcl2 was regulated directly by G-CSF-activated STAT3 via interaction at a STAT consensus element in the Cxcl2 promoter. G-CSF coordinately stimulated the association of STAT3, induction of the transcriptionally active H3K4me3 modification, and recruitment of RNA Pol II at the Cxcl2 proximal promoter, as well as the promoter region of Il8rb, encoding the MIP-2 receptor. These results suggest that the G-CSF-STAT3 pathway directly regulates transcriptional events that induce neutrophil mobilization.

Changes of cytokine levels during granulocyte-colony-stimulating factor stem cell mobilization in healthy donors: association with mobilization efficiency and potential predictive significance

BACKGROUND

Peripheral blood stem cells are an important source of hematopoietic stem cells (HSCs) for allogeneic transplantations. Some allogeneic donors mobilize HSCs poorly in response to the granulocyte--colony-stimulating factor (G-CSF). The estimation of the mobilization result in an individual donor is difficult due to the absence of suitable predictive factors.

STUDY DESIGN AND METHODS

We analyzed the concentrations and kinetics of certain cytokines induced by G-CSF in 76 healthy donors and compared them with the mobilization efficiency.

RESULTS

The levels of the most cytokines increased after the G-CSF application: sICAM, sVCAM, MMP-9, interleukin (IL)-6, TNF-α, sE-selectin, and fibronectin. The concentrations of SDF-1α and IL-8 decreased and VEGF and fractalkine remained unchanged. The premobilization concentrations of IL-6 (p = 0.0093) and TNF-a (p = 0.0006) correlated with preapheresis CD34+ cell count. The comparison of premobilization cytokine levels between better and worse mobilizers showed a difference for TNF-α (p = 0.0006) and IL-6 (p = 0.0682). The TNF-α level below cutoff of 3.6 pg/mL implied approximately 20 times higher risk of poor mobilization (odds ratio, 19.9; p = 0.0002). The immunophenotyping of CD34+ cells suggested a negative correlation between Day +5 CD34+ count and expression of CD11a (p = 0.0319) and a positive correlation with CD44 antigen expression (p = 0.0096).

CONCLUSION

The concentrations of certain cytokines corresponded to the quality of HSC mobilization in healthy donors. Their levels measured before mobilization could probably serve as predictive factors for mobilization efficacy and prospectively detect donors who might profit from new mobilization molecules.

STAT3 controls the neutrophil migratory response to CXCR2 ligands by direct activation of G-CSF-induced CXCR2 expression and via modulation of CXCR2 signal transduction

Neutrophil mobilization, the release of neutrophils from the bone marrow reserve into circulating blood, is important to increase peripheral neutrophil amounts during bacterial infections. Granulocyte colony-stimulating factor (G-CSF) and chemokines, such as macrophage-inflammatory protein-2 (MIP-2; CXCL2), can induce neutrophil mobilization, but the mechanism(s) they use remain unclear. Signal transducers and activator of transcription 3 (STAT3) is the principal intracellular signaling molecule activated upon G-CSF ligation of its receptor. Using a murine model with conditional STAT3 deletion in bone marrow, we demonstrated previously that STAT3 regulates acute G-CSF-responsive neutrophil mobilization and MIP-2-dependent neutrophil chemotaxis. In this study, we show STAT3 is also necessary for MIP-2-elicited neutrophil mobilization. STAT3 appears to function by controlling extracellular signal-regulated kinase (ERK) activation, which is important for MIP-2-mediated chemotaxis. In addition, we demonstrate that G-CSF stimulates the expression of the MIP-2 receptor via STAT3-dependent transcriptional activation of Il8rb. G-CSF treatment also induces STAT3-dependent changes in bone marrow chemokine expression levels which may further affect neutrophil retention and release. Taken together, our study demonstrates that STAT3 regulates multiple aspects of chemokine and chemokine receptor expression and function within the bone marrow, indicating a central role in the neutrophil mobilization response.

Double apheresis of peripheral blood stem cells in a single day in children mobilized by granulocyte colony-stimulating factor for transplantation

Due to the movement of hematopoietic stem cells through the bone marrow environment, it may be possible to effectively harvest peripheral blood stem cells in a second apheresis within a few hours after a first apheresis. In a retrospective analysis, 107 aphereses were performed in consecutive 33 pediatric and six healthy pediatric donors who received granulocyte-colony stimulating factor at 10 microg/kg/day or 400 microg/m(2)/day for five days. The median age and weight of cases were seven yr (range 1-19) and 20 kg (range 8-87). The toxicities related to apheresis procedure were minimal in both aphereses. In 22 double aphereses, the average number of CD34-positive cells per body weight (kg) collected was 5.3 +/- 4.2 (range 0.6-16.6) and 4.7 +/- 3.1 (range 0.2-10.9) x 10(6) in the first and second aphereses, respectively (p = 0.569). Multivariate analysis showed that number of CD34-positive cells collected in the first apheresis (p = 0.008) was an independent factor of increased CD34-positive cells in the second apheresis. Double apheresis in a single day was feasible and this procedure may be able to lessen the burden of apheresis compared to two consecutive-day apheresis.

Effects and safety of granulocyte colony-stimulating factor in healthy volunteers

PURPOSE OF REVIEW

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is now widely used in normal donors for collection of peripheral blood progenitor cells for allogeneic transplantation and granulocytes for transfusion. Currently available data on biologic and molecular effects, and safety of rhG-CSF in normal healthy volunteers are reviewed.

RECENT FINDINGS

In addition to its known activating role on neutrophil kinetics and functional status, rhG-CSF administration can affect monocytes, lymphocytes and the hemostatic system. Granulocyte colony-stimulating factor receptors were identified in a variety of nonmyeloid tissues, although their role and functional activity have not always been well defined. Moreover, rhG-CSF is capable of modulating complex cytokine networks and can impact the inflammatory response. In addition to its known mobilizing role for peripheral blood progenitor cells, rhG-CSF can mobilize dendritic and endothelial progenitor cells as well. On a clinical level, serious rhG-CSF-related adverse events are well described (e.g. splenic rupture) but remain rare.

SUMMARY

rhG-CSF effects in healthy volunteers, although normally transient and self-limiting, are now believed to be more complex and heterogeneous than previously thought. Although rhG-CSF administration to healthy volunteers continues to have a favorable risk-benefit profile, these new findings have implications for safeguarding the safety of normal individuals.

Inflammatory cell infiltration of tumors: Jekyll or Hyde

Inflammatory cell infiltration of tumors contributes either positively or negatively to tumor invasion, growth, metastasis, and patient outcomes, creating a Dr. Jekyll or Mr. Hyde conundrum when examining mechanisms of action. This is due to tumor heterogeneity and the diversity of the inflammatory cell phenotypes that infiltrate primary and metastatic lesions. Tumor infiltration by macrophages is generally associated with neoangiogenesis and negative outcomes, whereas dendritic cell (DC) infiltration is typically associated with a positive clinical outcome in association with their ability to present tumor antigens (Ags) and induce Ag-specific T cell responses. Myeloid-derived suppressor cells (MDSCs) also infiltrate tumors, inhibiting immune responses and facilitating tumor growth and metastasis. In contrast, T cell infiltration of tumors provides a positive prognostic surrogate, although subset analyses suggest that not all infiltrating T cells predict a positive outcome. In general, infiltration by CD8(+) T cells predicts a positive outcome, while CD4(+) cells predict a negative outcome. Therefore, the analysis of cellular phenotypes and potentially spatial distribution of infiltrating cells are critical for an accurate assessment of outcome. Similarly, cellular infiltration of metastatic foci is also a critical parameter for inducing therapeutic responses, as well as establishing tumor dormancy. Current strategies for cellular, gene, and molecular therapies are focused on the manipulation of infiltrating cellular populations. Within this review, we discuss the role of tumor infiltrating, myeloid-monocytic cells, and T lymphocytes, as well as their potential for tumor control, immunosuppression, and facilitation of metastasis.

Elevated serum levels of human matrix metalloproteinase-9 (MMP-9) during the induction of peripheral blood stem cell mobilization by granulocyte colony-stimulating factor (G-CSF)

To investigate the role of matrix metalloproteinases (MMPs) in the mobilization of peripheral blood stem cells stimulated by granulocyte colony-stimulating factor (G-CSF), we analyzed MMP serum levels in 11 healthy donors and 9 patients who had hematological malignancies or germ cell tumors. A dose of 5-10 microg/kg per day of G-CSF (lenograstim) was administered for 4-8 days to each subject. The serum levels of MMP-2, and MMP-9; interleukin-3, -6, -8, and -10; stem cell factor; interferon-gamma; and tumor necrosis factor-alpha were measured both before and during G-CSF administration. MMP-9 was found to be increased in both the cancer patients and the healthy donor group. In contrast, the levels of each of the other factors tested were unchanged. No significant positive correlation was observed between the MMP-9 levels and the number of CD34+ cells. Hence, we found no significant role for MMPs during the mobilization of peripheral blood stem cells stimulated by G-CSF.

Biologic and molecular effects of granulocyte colony-stimulating factor in healthy individuals: recent findings and current challenges

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is widely used in healthy donors for collection of peripheral blood progenitor cells (PBPCs) for allogeneic transplantation and granulocytes for transfusion. The spectrum of its biologic and molecular activities in healthy individuals is coming into sharper focus, creating a unique set of challenges and clarifying the need to monitor and safeguard donor safety. Accumulating evidence indicates that rhG-CSF effects are not limited to the myeloid cell lineage. This may reflect the presence of functional G-CSF receptors on other cell types and tissues, as well as rhG-CSF-induced modulation of cytokine networks. While most rhG-CSF-induced effects are transient and self-limiting, preliminary, provocative data have suggested the possibility of a more durable effect on the chromosomal integrity of lymphocytes. While these reports have not been validated and have been subject to criticism, they are prompting prospective studies and monitoring efforts to determine whether there is a significant risk of long-term adverse events (eg, hematologic malignancies) in healthy PBPC and granulocyte donors. Based on the totality of information that is currently available, the administration of rhG-CSF to healthy donors for the purpose of PBPC donation continues to have a favorable risk-benefit profile.

Simvastatin enhances endothelial differentiation of peripheral blood mononuclear cells in hypercholesterolemic patients and induces pro-angiogenic cytokine IL-8 secretion from monocytes

BACKGROUND

Statins are known to have pleiotropic effects. We examined the effect and mechanism of simvastatin therapy on EPC differentiation and pro-angiogenic cytokines in patients with hypercholesterolemia.

METHODS

Twenty-two hypercholesterolemia patients without any other modifiable cardiovascular risk factors or history of previous lipid-lowering therapy were given simvastatin 20 mg/day for 4 weeks. Blood were drawn pre- and post-therapy. The in vitro effects of simvastatin were studied in a separate set of experiments.

RESULTS

Simvastatin treatment significantly increased the number of DiI-acLDL, UEA-1 lectin double-positive EPCs and facilitated its appearance. By FACS analysis of freshly isolated PBMNCs, KDR (+) cells increased after simvastatin treatment while there were no differences in CD34, AC133, and VE-cadherin. Also, serum concentration of IL-8 was markedly increased, while VEGF was only slightly increased. In vitro, PBMNCs co-cultured with simvastatin showed increased cluster formation at day 7, and simvastatin facilitated the appearance and networking of EPCs compared with vehicle. Simvastatin-co-cultured PBMNCs showed significantly increased KDR (+) cells, in contrast to CD34, CD31, and VE-Cadherin (+) cells. In response to simvastatin, IL-8 was mainly increased in monocyte culture supernatants while VEGF increased in smooth muscle cell culture supernatants. These cytokines were associated with increased EPC migratory function. The increase in IL-8 secretion from monocytes by statin treatment was associated with phosphorylation and inactivation of GSK3beta, which was reversed by constitutive activation of GSK-3beta.

CONCLUSION

Simvastatin enhances endothelial differentiation of peripheral blood mononuclear cells in patients with hypercholesterolemia and increases pro-angiogenic cytokine IL-8 secretion from monocytes. Our results may explain the pro-angiogenic effects associated with statin therapy and offer further evidence of statin pleiotropism.

Simultaneous analysis of cytokines and co-stimulatory molecules concentrations by ELISA technique and of probabilities of measurable concentrations of interleukins IL-2, IL-4, IL-5, IL-6, CXCL8 (IL-8), IL-10, IL-13 occurring in plasma of healthy blood donors

Background. The cytokine network remarkably influences homeostasis. There is not a complex analysis describing physiological values of soluble cytokines in healthy individuals. Methods. Authors used the ELISA method to detect soluble cytokines and costimulatory molecules simultaneously in the plasma of 30 blood donors. Results. Data are shown as (a range of concentrations; median) IL-2 (0–74.48 pg/mL; 0), IL-4 (0–65.18 pg/mL; 0), IL-5 (0–86.69 pg/mL; 0), IL-6 (0–73.17 pg/mL; 0), IL-8 (0–74.8 pg/mL; 0), IL-10 (0–12.6 pg/mL; 0), IL-13 (0–3.9 pg/mL; 0), sCD40L (0–3.5 ng/mL; 0), and TNF-α (0–67.6; 0). For the IL-6 receptor, the concentration was 75.89 ± 35.83 ng/mL (average ± SD), sCD23 28.9 ± 15.22 ng/mL, and TGFβ1 14.98 ± 12.39 ng/mL. A special approach was taken for the analysis of values, which had median 0. A model for the probability of detectable level's occurrence for each interleukin was formulated with intervals of confidence. Conclusion. These results provide reference values for cytokine levels in the plasma of healthy individuals.

Hematopoietic progenitor cell mobilization in mice by sustained delivery of granulocyte colony-stimulating factor

The objective of these studies was to determine the effect of sustained delivery of growth factors (GFs) on hematopoietic progenitor cells (HPCs) in mice. In these studies, granulocyte colony-stimulating factor (G-CSF) was administered using the poloxamer-based matrix, ProGelz (PG) and G-CSF, and pharmacokinetics (PKs) and HPC mobilization was assessed. A single injection of G-CSF formulated in PG (17% poloxamer-407 and 5% hydroxypropyl methylcellulose [HPMC]) administered to BALB/c mice mobilized HPC significantly more rapidly to the spleen, but not the blood, than multiple injections of saline-formulated G-CSF. Two days after a single injection of PG G-CSF, the frequency of colony-forming unit-culture (CFU-c) in the spleen was increased 289-fold compared with an 8-fold increase after 2 days of twice-daily injections of saline-formulated G-CSF. Indeed, 4 days of twice-daily G-CSF injections were required to achieve the same level of HPC mobilization. In contrast, a similar mobilization of HPC to the blood was observed between PG and saline-formulated G-CSF. The mechanism for the accelerated and increased mobilization to the spleen by the PG-formulation of G-CSF is due, in part, to its increased bioavailability (>1.5-fold), T(max) (6-fold), and prolonged elimination (Tbeta) half-life (>3-fold) as compared with a saline formulation. In addition, we observed a more rapid trafficking of the PG G-CSF to the marrow, which could also facilitate mobilization.

Involvement of Proteases in Cytokine-Induced Hematopoietic Stem Cell Mobilization

The number of circulating stem cells and progenitor cells can be increased by physiological stress, such as exercise, stress, and infections. The process of shifting the stem cells from the bone marrow into the peripheral blood is referred to as "mobilization" or "egress." Cytokine-mobilized hematopoietic progenitor cells (HPCs) are currently used for autologous or allogeneic stem cell transplantation in a variety of malignant and nonmalignant diseases. In spite of the wide-spread use of mobilized peripheral blood stem cells for transplantation, the mechanisms underlying mobilization are still incompletely understood. Here we discuss the role of neutrophils and proteases as mediators of stem cell mobilization.

Hematopoietic Progenitor Cell Mobilization by Granulocyte Colony-Stimulating Factor and Erythropoietin in the Absence of Matrix Metalloproteinase-9

The use of mobilized hematopoietic progenitor cells (HPC) has largely replaced the use of bone marrow HPC for autologous and allogeneic transplantation; however, the mechanisms of HPC mobilization remain unclear. A better understanding of these mechanisms, may allow the development of improved (potentially more rapid and/or higher yield) HPC mobilization strategies, especially for patients who mobilize poorly using current mobilization protocols. Clinically, granulocyte colony-stimulating factor (G-CSF) is widely used to induce HPC mobilization, and evidence suggests that metalloproteinase enzymes released by activated granulocytes play an important role in the G-CSF-induced HPC mobilization. These enzymes may act to disrupt putative cell-cell and/or cell-extracellular matrix interactions within the hematopoietic microenvironment thereby releasing HPC into the blood. Matrix metalloproteinase-9 (MMP-9) appears to be important for G-CSF-induced mobilization. Using an MMP-9 knock-out (KO) mouse model, we investigated the role of MMP-9 in G-CSF and erythropoietin (EPO)-based HPC mobilization at clinically relevant cytokine doses. There were few hematologic or hematopoietic differences between the wild-type and MMP-9KO mice during steady-state hematopoiesis. When treated subcutaneously with EPO (500 U/kg per day) and G-CSF (15 microg/kg per day) for 5 days and assayed on day 6, similarly increased extramedullary hematopoiesis and numbers of HPC in the spleen and blood were observed for both the wild-type and MMP-9KO mice. These data demonstrate that MMP-9 is not required for EPO + G-CSF mobilization and that alternative mobilization mechanisms must be active at clinically relevant cytokine concentrations.

Interleukin-8, Neutropenia, and Graft Failure in Human Stem Cell Transplantation

We studied the role of interleukin (IL)-8 during engraftment after hematopoietic stem cell transplantation. In 40 consecutive patients undergoing either allogeneic marrow (n=32) or autologous peripheral blood stem cell transplantation (n=8), IL-8 plasma levels were serially determined. Median IL-8 concentrations peaked during the neutropenic phase and, subsequently, subsided to pretransplant levels in patients achieving engraftment. In all patients, we observed an inverse correlation of IL-8 with leukocytes (P<0.0001) and a direct correlation of IL-8 with the extent of neutropenia (P<0.0001). Four patients who developed graft failure showed sustained median IL-8 concentrations of >300 pg/mL together with persistent neutropenia. This marked elevation of IL-8 was statistically significant as early as day 11 after transplantation, at a time when no other evidence alluded to imminent graft failure. Our data suggest that IL-8 may play an important role during engraftment after hematopoietic stem cell transplantation.

Granulocyte colony-stimulating-factor-induced psoriasiform dermatitis resembles psoriasis with regard to abnormal cytokine expression and epidermal activation

Psoriasis is a chronic inflammatory skin disorder characterized by accumulation of Th1-type T cells and neutrophils, regenerative keratinocyte proliferation and differentiation, and enhanced epidermal production of antimicrobial peptides. The underlying cause is unknown, but there are some similarities with the immunologic defense program against bacteria. Development of psoriasiform skin lesions has been reported after administration of granulocyte colony-stimulating factor (G-CSF), a cytokine induced in monocytes by bacterial antigens. To further investigate the relation between this type of cytokine-induced dermatitis and psoriasis, we analyzed the cutaneous cytokine profile [tumor necrosis factor-alpha (TNF-alpha), interferon-gamma, transforming growth factor-beta1 (TGF-beta1), interleukin-10 (IL-10), IL-12p35 and p40, and IL-8] and expression of markers of epidermal activation [Ki-67, cytokeratin-16, major histocompatibility complex (MHC) class II, intercellular adhesion molecule-1 (ICAM-1)] in a patient who developed G-CSF-induced psoriasiform dermatitis by using quantitative real-time reverse transcriptase-polymerase chain reaction and immunohistology. The histologic picture resembled psoriasis with regard to epidermal hyperparakeratosis and the accumulation of lymphocytes in the upper corium. CD8(+) T cells were found to infiltrate the epidermis which was associated with an aberrant expression of Ki-67, cytokeratin-16, MHC class II, and ICAM-1 on adjacent keratinocytes. As compared to normal skin (n = 7), there was an increased expression of TNF-alpha, IL-12p40, and IL-8, a decreased expression of TGF-beta1, and a lack of IL-10, similar to the findings in active psoriasis (n = 8). Therefore, G-CSF may cause a lymphocytic dermatitis that, similar to psoriasis, is characterized by a pro-inflammatory Th1-type cytokine milieu and an epidermal phenotype indicative of aberrant maturation and acquisition of non-professional immune functions.

Leukocyte circulation: one-way or round-trip? Lessons from primary immunodeficiency patients

The identification of chemokines has profoundly changed the way we interpret the immune response, elucidating the mechanism by which inflammatory cells are recruited to the site of infection by local secretion of chemoattractants such as CXC chemokine ligand 8 (CXCL8)/interleukin-8, chemokine ligand 2 (CCL2)/monocyte chemoattractant protein 1. This novel view of the immune response has been remodeled further following observations that lymphoid tissue development derives from the coordinated secretion of homeostatic chemokines such as CCL19, CCL21, and CXCL13, which mediate recruitment and clustering of the cells involved in lymphoid organogenesis. The study of primary immunodeficiencies has demonstrated that the number of circulating leukocytes is dependent on migration amongst bone marrow, blood circulation, and inflamed tissues. Defects of leukocyte adhesion and chemotaxis as a result of mutations of beta2-integrins lead to abnormal leukocytosis and susceptibility to skin infections, as observed in leukocyte adhesion deficiency. Conversely, neutropenia in children with myelokathexis is a result of leukocyte retention in the bone marrow because of the mutations of CXC chemokine receptor 4, which affect the capacity of cells to recirculate between blood and bone marrow. Moreover, the identification of the genetic basis of primary immunodeficiencies has shown that many primary immunodeficiencies such as Wiskott-Aldrich syndrome and common variable immunodeficiencies are characterized by altered migration of leukocytes and/or disregulation of cellular response to chemokines. This paper will be focused on the interpretation of primary immunodeficiencies as defects in leukocyte circulation between blood and primary and secondary organs.

Use of matrix metalloproteinase (MMP)-9 knockout mice demonstrates that MMP-9 activity is not absolutely required for G-CSF or Flt-3 ligand-induced hematopoietic progenitor cell mobilization or engraftment

Recombinant growth factors (GFs) are used to mobilize hematopoietic stem cells (HSCs) for autologous and allogeneic transplantation; however, little is known about the mechanism(s) critical to this process. Increased levels of serum matrix metalloproteinase (MMP)-9 are detected during mobilization by G-CSF in humans or interleukin (IL)-8 in primates and mice, suggesting a role for this molecule in mobilization. Further, antibodies to MMP-9 block IL-8-induced mobilization. To investigate the role of MMP-9, we compared G-CSF and Flt-3 ligand (Flt-3L)-induced mobilization in wild-type (WT) and MMP-9 knockout (KO) mice. The absence of MMP-9 in the KO mice was confirmed by zymography, which also revealed that serum MMP-9 levels were elevated in WT mice following G-CSF administration. We report that MMP-9 KO mice did not have impaired G-CSF- or Flt-3L-induced hematopoietic progenitor mobilization, suggesting that MMP-9 is not an absolute requirement for this process. In addition, MMPs produced by HSCs have been demonstrated to be important for their transmigration; however, we demonstrate that the engraftment of MMP-9-deficient bone marrow HSCs was not impaired in sublethally irradiated WT recipients. We conclude that while MMP-9 may play an important role in GF-induced hematopoietic progenitor mobilization and engraftment in WT animals, compensatory upregulation of enzymes with a similar activity profile to MMP-9 may obscure the impact of MMP-9 deficiency in the KO model.

Elevation of serum hepatocyte growth factor during granulocyte colony-stimulating factor-induced peripheral blood stem cell mobilization

We examined serum levels of the angiogenic factors, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and hepatocyte growth factor (HGF), in normal donors for allogeneic peripheral blood stem cell (PBSC) transplantation. Granulocyte colony-stimulating factor (G-CSF) (filgrastim 400 microg/m2/d) was administered to 23 donors for 5 d and aphereses were performed on days 4 and 5. Although bFGF remained at similar levels after G-CSF treatment, serum VEGF and HGF levels increased 1.5-fold (n = 13; P = 0.02) and 6.8-fold (n = 23; P < 0.0001) respectively. The serum HGF level before G-CSF administration on day 1 correlated inversely with mobilized CD34+ cell numbers. Time course kinetics of HGF showed that on the day after G-CSF administration (day 2), serum HGF levels increased to 3678 pg/ml. For auto PBSC mobilization with chemotherapy and G-CSF 200 microg/m2/d (n = 8), we observed similar HGF elevation, which appeared to be dose-dependent on the G-CSF administered.

Stromal-derived factor 1 and matrix metalloproteinase 9 levels in bone marrow and peripheral blood of patients mobilized by granulocyte colony-stimulating factor and chemotherapy. Relationship with mobilizing capacity of haematopoietic progenitor cells

The roles of the chemokine stromal-derived factor 1 (SDF-1) and the matrix metalloproteinase 9 (MMP-9) in haematopoietic progenitor cell (HPC) mobilization are still unclear, particularly when patients are mobilized by granulocyte colony-stimulating factor (G-CSF) plus chemotherapy. We determined bone marrow (BM) and peripheral blood (PB) plasma levels of SDF-1, together with CXC-chemokine receptor 4 (CXCR-4) expression on CD34+ cells, and interleukin 8 (IL-8) and MMP-9 in 55 patients mobilized for autologous PB transplantation compared with 10 normal BM and PB samples. Plasma samples were tested at steady state (SS-) and after mobilization by cyclophosphamide and G-CSF administration (M-). SDF-1, CXCR-4, IL-8 and MMP-9 levels were significantly lower in SS- and M-PB than in SS-BM. Differences in SDF-1 levels between SS-PB and SS-BM were also observed after mobilization. We showed for the first time a clear relationship between the levels of circulating HPC, both at steady state and after mobilization, and those of secreted MMP-9 but not of SDF-1 or IL-8. However, a negative correlation was observed between mobilizing capacity and CXCR-4 expression on CD34+ cells. These findings suggest that G-CSF-induced mobilization of HPC from BM involves MMP-9, without reversing the positive gradient of SDF-1 between BM and PB.

Peripheral blood stem cell mobilization. A role for CXC chemokines

Chemokines induce rapid hematopoietic stem and progenitor cell mobilization and synergize with hematopoietic cytokines in mobilizing stem and progenitor cells. These proteins alone and in combination offer new paradigms for autologous and allogeneic peripheral blood stem cell transplantation (PBSCT). The mechanisms responsible for hematopoietic stem cell (HSC) mobilization either with growth factors or chemokines are largely unknown, but a better understanding of these mechanisms will permit the development of novel, more rapid and efficacious regimens. Studies presented herein indicate that the CXCR2 chemokine receptor that interacts with selective chemokine ligands, particularly GRObeta/CXCL2 and GRObeta-T, may be the dominant receptor mediating hematopoietic cell mobilization, and that polymorphonuclear neutrophils may be the primary CXCR2 expressing target cell for stem and progenitor cell mobilization.

Plasma stromal cell-derived factor-1 during granulocyte colony-stimulating factor-induced peripheral blood stem cell mobilization

In this report, we examined plasma stromal cell-derived factor-1 levels in normal healthy donors for allogeneic peripheral blood stem cell transplantation (PBSCT) and in patients for autologous PBSCT using an enzyme-linked immunosorbent assay. The average level of plasma stromal cell-derived factor-1 was 2197 pg/ml before granulocyte colony-stimulating factor administration and 1899 pg/ml on day 4, demonstrating a significant decrease in the peripheral blood of healthy donors (P=0.0003). In patients for autologous PBSCT, a significant decrease of plasma stromal cell-derived factor-1 in the peripheral blood was also observed (P=0.0464). However, the physiologic gradient of stromal cell-derived factor-1 between peripheral blood and bone marrow was never inverted in normal healthy donors or in autologous PBSCT patients. Our results suggest that stromal cell-derived factor-1 may not be involved in the granulocyte colony-stimulating factor-induced release of CD34(+) cells to the peripheral blood. Further studies of a possible additive effect of granulocyte colony-stimulating factor and stromal cell-derived factor-1 are warranted.

Effect of granulocyte colony-stimulating factor on bone metabolism during peripheral blood stem cell mobilization

Granulocyte colony-stimulating factor (G-CSF) has been shown to affect the biochemical markers of bone metabolism, including serum bone alkaline phosphatase (BALP), serum osteocalcin, and urine deoxypyridinoline. To determine the association between bone resorption and formation and the G-CSF-induced mobilization of peripheral blood stem cells (PBSC), we examined these markers during mobilization in 19 healthy donors. The average (+/- SEM) serum BALP level before treatment was 81.6 +/- 17.0 IU/dL, and the level increased significantly to 117.7 +/- 15.8 IU/dL on day 5 of G-CSF administration (P < .0001). The urine deoxypyridinoline level before treatment was 12.3 +/- 2.4 nmol/mmol creatinine, and this level also increased significantly to 19.4 +/- 3.0 nmol/mmol creatinine on day 5 of G-CSF administration (P < .0001). In contrast, the average level of serum osteocalcin significantly decreased from 8.07 +/- 2.88 ng/mL to 1.53 +/- 0.18 ng/mL on day 5 (P = .0353). During G-CSF administration, we also studied the serum levels of various cytokines (IL-1beta, osteoclastogenesis inhibitory factor [OCIF], IL-6, tumor necrosis factor alpha, transforming growth factor beta, interferon-gamma, macrophage colony-stimulating factor) related to bone metabolism. Only the kinetics of OCIF were significantly affected. The serum level of OCIF increased immediately after the start of G-CSF administration and remained high during G-CSF administration. These results demonstrate that high-dose G-CSF affects bone metabolism and that OCIF may play a role in bone metabolism. Consistent with the notion that G-CSF affects bone metabolism, a significant correlation was observed between CD34+ cell yield and the increase in urine deoxypyridinoline but not for the changes in serum BALP and osteocalcin levels. This result suggests that bone resorption is either directly or indirectly related to the mobilization of PBSC by G-CSF.

Comparative study and effects of macrophage colony-stimulating factor (M-CSF) administration on NK1.1+ cells in mouse spleen and bone marrow

We conducted a comparative study of NK1.1+ cells in spleen and bone marrow and the effects of administration of M-CSF on them. Administration of M-CSF to mice increased the number of NK1.1+ cells in spleen but not in bone marrow. The NK1.1+ cells in spleen (Spl-NK1.1) and bone marrow (BM-NK1.1) were purified by magnetic cell sorter. Their cell surface markers and functions were then examined. The percentage of Mac-1 antigen-positive cells (and F4/80 antigen-positive cells) was higher among BM-NK1.1 than Spl-NK1.1. Moreover, the administration of M-CSF increased the number of Mac-1 and F4/80 antigen-positive cells in both Spl-Nk1.1 and BM-NK1.1. The functions (cytolytic activity and IFN-gamma production) of Spl-NK1.1 and BM-NK1.1 were the same and were enhanced by the administration of M-CSF. But Spl-NK1.1 produced more IFN-gamma than BM-NK1.1 when M-CSF was administered. BM-NK1.1 showed a greater proliferative response to IL-2 than Spl-NK1.1. Administration of M-CSF augmented this response. BM-NK1.1 proliferated in response to IL-4 and IL-15, but Spl-NK1.1 responded only slightly. However, administration of M-CSF stimulated Spl-NK1.1 to respond to these cytokines. Both Spl-NK1.1 and BM-NK1.1 showed only a weak response to M-CSF in vitro. But the expression of c-fms antigen (M-CSFR) increased after the M-CSF injections in vivo. These results suggested that there are phenotypical and functional differences between Spl-NK1.1 and BM-NK1.1. The administration of M-CSF led to an accumulation of NK1.1+ cells which were mobilized from bone marrow in spleen.

G-CSF induces stem cell mobilization by decreasing bone marrow SDF-1 and up-regulating CXCR4

Granulocyte colony-stimulating factor (G-CSF) induced hematopoietic stem cell mobilization is widely used for clinical transplantation; however, the mechanism is poorly understood. We report here that G-CSF induced a reduction of the chemokine stromal cell derived factor 1 (SDF-1) and an increase in its receptor CXCR4 in the bone marrow (BM), whereas their protein expression in the blood was less affected. The gradual decrease of BM SDF-1, due mostly to its degradation by neutrophil elastase, correlated with stem cell mobilization. Elastase inhibition reduced both activities. Human and murine stem cell mobilization was inhibited by neutralizing CXCR4 or SDF-1 antibodies, demonstrating SDF-1 CXCR4 signaling in cell egress. We suggest that manipulation of SDF-1 CXCR4 interactions may be a means with which to control the navigation of progenitors between the BM and blood to improve the outcome of clinical stem cell transplantation.

Proteolytic enzyme levels are increased during granulocyte colony-stimulating factor-induced hematopoietic stem cell mobilization in human donors but do not predict the number of mobilized stem cells

Previous studies from our laboratory indicate that functional, mature neutrophils are essential for interleukin-8 (IL-8)-induced stem cell mobilization. To study a possible role of neutrophils in granulocyte colony-stimulating factor (G-CSF) induced hematopoietic mobilization, we assessed the number of circulating CD34+ cells in healthy allogeneic stem cell donors on days 3, 4, and 5 of mobilization for comparison with the number of peripheral blood neutrophils and the plasma levels of IL-8, Flt3 ligand (FL), matrix metalloproteinase-9 (MMP-9), and human neutrophil elastase (HNE). Thirty-seven of 45 donors required 1 day of apheresis to obtain 5 x 10(6) CD34+/kg recipient body weight (high responders), the remaining 8 donors required 1 extra day of apheresis on day 6 (low responders). On day 5, CD34+ numbers in the blood were significantly highe in high responders (116 x 10(3) +/- 10.4/ml) than in low responders (54.1 x 10(3) +/- 10.3, p < 0.001). In all donors, MMP-9 and HNE levels were increased compared to nonmobilized individuals, but in high responders, plasma MMP-9 levels on days 3-5 of mobilization were substantially higher than in low responders (p < or = 0.02 for MMP-9 and p = 0.89, p = 0.05 and p = 0.52 for HNE on days 3, 4, and 5, respectively). These results are in accordance with the hypothesis that neutrophils play a role in G-CSF-induced mobilization through the release of proteases such as MMP-9 and elastase. No change in plasma levels of IL-8 or Flt3 ligand was observed, suggesting that these cytokines do not play a role in stem cell mobilization. However, because stem cell numbers could not be predicted by proteolytic enzyme levels and/or neutrophil numbers, other undefined factors may be more important.

Hematopoietic stem cells are uniquely selective in their migratory response to chemokines

Although hematopoietic stem cell (HSC) migration into and out of sites of active hematopoiesis is poorly understood, it is a critical process that underlies modern clinical stem cell transplantation and may be important for normal hematopoietic homeostasis. Given the established roles of chemotactic cytokine (chemokine)-directed migration of other leukocyte subsets, the migration of murine HSC to a large panel of CC and CXC chemokines was investigated. HSC migrated only in response to stromal derived factor-1alpha, the ligand for the CXC chemokine receptor 4 (CXCR4). CXCR4 expression by HSC was confirmed by reverse transcription polymerase chain reaction analysis. Surprisingly, HSC also expressed mRNA for CCR3 and CCR9, although they failed to migrate to the ligands for these receptors. The sharply restricted chemotactic responsiveness of HSC is unique among leukocytes and may be necessary for the specific homing of circulating HSC to bone marrow, as well as for the maintenance of HSC in hematopoietic microenvironments.

Leukocyte elastase negatively regulates Stromal cell-derived factor-1 (SDF-1)/CXCR4 binding and functions by amino-terminal processing of SDF-1 and CXCR4

Activation of CXCR4 by the CXC chemokine stromal cell-derived factor-1 (SDF-1) requires interaction of the amino-terminal domains of both molecules. We report that proteinases released from either mononucleated blood cells or polymorphonuclear neutrophils degranulated by inflammatory stimuli generate an SDF-1 fragment that is deleted from amino-terminal residues Lys(1)-Pro(2)-Val(3), as characterized by mass spectrometry analysis. The proteolyzed chemokine fails to induce agonistic functions and is unable to prevent the fusogenic capacity of CXCR4-tropic human immunodeficiency viruses. Furthermore, we observed that exposure of CXCR4-expressing cells to leukocyte proteinases results in the proteolysis of the extracellular amino-terminal domain of the receptor, as assessed by flow cytometry analysis and electrophoretic separation of immunoprecipitated CXCR4. Blockade of SDF-1 and CXCR4 proteolysis by the specific leukocyte elastase inhibitor, N-methoxysuccinyl-alanine-alanine-proline-valine-chloromethyl ketone, identified elastase as the major enzyme among leukocyte-secreted proteinases that accounts for inactivation of both SDF-1 and CXCR4. Indeed, purified leukocyte elastase generated in either SDF-1 or CXCR4 a pattern of cleavage indistinguishable from that observed with leukocyte-secreted proteinases. Our findings suggest that elastase-mediated proteolysis of SDF-1/CXCR4 is part of a mechanism regulating their biological functions in both homeostatic and pathologic processes.

Matrix metalloproteinase-9 (gelatinase B) is elevated during mobilization of peripheral blood progenitor cells by G-CSF

BACKGROUND

Matrix metalloproteinase-9 (MMP-9 or gelatinase B) has recently been implicated in the IL-8-induced mobilization of HPCs in rhesus monkeys and mice. It is not known whether administration of G-CSF causes expression of MMP-9 during HPC mobilization.

STUDY DESIGN AND METHODS

Blood samples from 15 allogeneic progenitor cell donors were collected before and during G-CSF-induced HPC mobilization. The expression of the gelatinases MMP-2 and MMP-9 in the plasma of the donors was analyzed by ELISA and zymographic analysis. Gelatinolytic activity was measured with a fluorometric assay that was specific for gelatinases. Expression of IL-6, IL-8, and soluble vascular cell adhesion molecule (VCAM) was measured by ELISA.

RESULTS

Highly elevated latent gelatinolytic activity was found on Days 4 and 5 of G-CSF treatment in comparison to pretreatment activity. ELISA and zymographic analyses revealed pro-MMP-9 as the major source of the latent gelatinolytic plasma activity during mobilization. Pro-MMP-2 was not elevated compared with pretreatment levels. As IL-8 has been implicated in the expression of MMP-9, IL-8 concentrations were measured in plasma samples from donors and patients immediately before the start of HPC apheresis, but no significantly elevated IL-8 concentrations were noted. In contrast, pro-MMP-9 and latent gelatinolytic activity was highly correlated with IL-6, which was strongly elevated during mobilization therapy. Finally, soluble VCAM was equally significantly elevated on the days of apheresis.

CONCLUSIONS

G-CSF mobilization treatment induces MMP-9, IL-6, and soluble VCAM. Expression of MMP-9 might be involved in the mobilization of human HPCs and might be a final common pathway of different mobilization therapies. Our data do not support a role of IL-8 in G-CSF-induced mobilization. In contrast, IL-6 might be involved in the G-CSF-induced expression of MMP-9.

In vitro safety profile of G-CSF-mobilized whole blood after storage for 7 days in an infusable-grade L15 medium

BACKGROUND

G-CSF-mobilized whole blood (WB) is a cost-reducing and simple alternative for peripheral blood progenitor cell transplantation. Recently, it was demonstrated that mobilized WB supplemented with Leibovitz's L15 medium permitted prolonged preservation of clonogenic cells at ambient temperature. In this study, an infusable-grade L15 medium (IG-L15) was developed, and the safety profile of mobilized WB after 7 days of storage was investigated.

STUDY DESIGN AND METHODS

IG-L15 was manufactured in a closed system under good manufacturing practice conditions. Proinflammatory cytokine levels and hemolysis in mobilized WB were determined after 7 days of storage in different containers and were compared with current clinical mobilized WB values after 1 to 3 days of storage at 4 degrees C.

RESULTS

IG-L15 and L15 maintained clonogenic cells equally. In the samples of mobilized WB that were returned to the patient, cytokine levels were not elevated in comparison with freshly collected mobilized WB. By using IG-L15 in polystyrene-coated cell culture bags, median (range) levels of 9.4 (2.2-69.8) pg per mL (IL-1beta), 31.6 (6.1-146.5) pg per mL (TNF-alpha), 76.9 (15.5-934.9) pg per mL (IL-6), and 7195 (104-205,600) pg per mL (IL-8) were found after 7 days. Higher cytokine levels were found with L15 and different containers. He- molysis was less than 0.5 g per dL in all cases.

CONCLUSION

The storage of mobilized WB for 7 days in IG-L15 at ambient temperature is possible with adequate preservation of clonogenic cells, but cytokine levels may require plasma removal before return.

Neutrophil gelatinase B and chemokines in leukocytosis and stem cell mobilization

Leukocytosis is a physiopathological mechanism primarily to combat infections, whereas stem cell mobilization is induced for therapeutical purposes. Both processes are dependent on the balance between leukocyte and stem cell retention and mobilization. The retention is mediated by the specific architecture of the bone marrow, adhesion molecules and the production of chemokines in the bone marrow, which attract escaped immature cells to the marrow. Mobilization is the effect of the action of "peripheral" chemokines, such as interleukin-8 (IL-8 or CXCL8) and the remodeling of the matrix and basement membranes by matrix enzymes, such as gelatinase B (MMP-9). Recent studies lead to the conclusion that neutrophils, IL-8/CXCL8 and gelatinase B/MMP-9 play control roles in leukocytosis and stem cell mobilization. Neutrophils are the predominant circulating leukocyte type and IL-8/CXCL8 is the major neutrophil chemoattractant in humans. Gelatinase B and no gelatinase A is rapidly released from prestored granules after activation of neutrophils by IL-8/CXCL8. Moreover, neutrophils do not produce TIMP-1 and can chemically activate latent progelatinase B. Activated gelatinase B catalyses the aminoterminal truncation of IL-8/CXCL8 into a tenfold more potent chemokine. This implies that, when IL-8/CXCL8 appears in the circulation, the bone marrow is instructed to release neutrophils and concomitantly stem cells. These studies suggest that IL-8/CXCL8 and gelatinase B/MMP-9 are targets for the modulation of stem cell mobilization.

Vascular cell adhesion molecule-1 (CD106) is cleaved by neutrophil proteases in the bone marrow following hematopoietic progenitor cell mobilization by granulocyte colony-stimulating factor

Mobilized progenitor cells currently represent the most commonly used source of hematopoietic progenitor cells (HPCs) to effect hematopoietic reconstitution following myeloablative chemotherapies. Despite their widespread use, the molecular mechanisms responsible for the enforced egress of HPCs from the bone marrow (BM) into the circulation in response to mobilizing agents such as cytokines remain to be determined. Results of this study indicate that expression of vascular cell adhesion molecule-1 (VCAM-1) is strongly reduced in vivo in the BM during HPC mobilization by granulocyte colony-stimulating factor (G-CSF) and stem cell factor. Two serine proteases, namely, neutrophil elastase and cathepsin G, were identified, which cleave VCAM-1 and are released by neutrophils accumulating in the BM during the course of immobilization induced by G-CSF. The proposal is made that an essential step contributing to the mobilization of HPCs is the proteolytic cleavage of VCAM-1 expressed by BM stromal cells, an event triggered by the degranulation of neutrophils accumulating in the BM in response to the administration of G-CSF.

Il-17 mobilizes peripheral blood stem cells with short- and long-term repopulating ability in mice

Autologous and allogeneic bone marrow transplantations have evolved as important cancer therapy modalities. For both indications, peripheral blood has been shown to have distinct advantages over bone marrow as the stem cell source. Cytokine combinations for mobilization have enhanced stem cell yield and accelerated engraftment. However, novel mobilizing agents and strategies are needed to further improve clinical outcomes. Within the donor graft, the dynamic equilibrium between T cells and stem cells critically influences engraftment and transplantation results. IL-17 is a cytokine produced almost exclusively from activated T cells. IL-17 was expressed in vivo with adenovirus technology. Here, proof-of-principle studies demonstrate that IL-17 effectively mobilizes hemopoietic precursor cells (CFU-granulocyte-erythrocyte-macrophage-monocyte, CFU-high proliferative potential) and primitive hemopoietic stem cells (Lin(-/low)c-kit(+)Sca1(+)). Moreover, mouse IL-17 adenovirus-mobilized peripheral blood stem cells rescued lethally irradiated mice. Bone marrow was found to be 45-75% of donor origin at 1 year. In secondary recipients, donor-derived bone marrow cells ranged from 45 to 95%. These data show that IL-17 mobilizes stem cells in mice with short- and long-term reconstituting capacity. Additional comparative studies are needed as well as studies in tumor models to refine distinct potential clinical applications for IL-17-mobilized peripheral blood stem cells.

Kinetics of PBPC mobilization by cyclophosphamide, as compared with that by epirubicin/paclitaxel followed by G-CSF support: implications for optimal timing of PBPC harvest

BACKGROUND

Limited information is available on the mobilization kinetics of autologous PBPCs after induction with various chemotherapy regimens. With PBPC mobilization in patients with breast cancer used as a model for chemotherapy-induced PBPC recruitment, the kinetics of progenitor cells mobilized either with cyclophosphamide (CY) or epirubicin/paclitaxel (EPI-TAX) followed by the administration of G-CSF was compared.

STUDY DESIGN AND METHODS

The study included a total of 86 patients with breast cancer (stage II-IV) receiving either CY (n = 39) or EPI-TAX (n = 47), both followed by G-CSF support. The progenitor cell content in peripheral blood and apheresis components was monitored by flow cytometric enumeration of CD34+ cells. PBPC collection was started when the threshold of >20 x 10(6) CD34+ cells per L of peripheral blood was reached.

RESULTS

The PBPC collection was begun a median of 9 days after the administration of EPI-TAX followed by G-CSF support, as compared to a median of 13 days after mobilization with CY plus G-CSF. After treatment with CY, the total numbers of PBPCs peaked on Day 1 of apheresis, and they rapidly declined thereafter. In contrast, treatment with EPI-TAX followed by G-CSF administration led to a steady mobilization of CD34+ cells during leukapheresis. The difference in the mobilization patterns with CY and EPI-TAX resulted in a greater yield of CD34+ cells per L of processed blood volume. Compared to EPI-TAX, mobilization with CY required the overall processing of 30 percent less whole-blood volume to reach the target yield of > or = 10 x 10(6) CD34+ cells per kg of body weight. After a median of three apheresis procedures, however, both CY+G-CSF and EPI-TAX+G-CSF were equally effective in obtaining this target yield.

CONCLUSION

These results imply that specific PBPC mobilization as part of a given chemotherapy regimen should be taken into consideration before the planning of a PBPC harvest.

Increased Serum Flt3-Ligand in Healthy Donors Undergoing Granulocyte Colony-Stimulating Factor-Induced Peripheral Stem Cell Mobilization

The effect of granulocyte colony-stimulating factor (G-CSF) induced mobilization of peripheral blood progenitor cells (PBPC) on the endogenous serum levels of cytokines stem cell factor (SCF) and flt3-ligand (flt3-L) was studied in 18 healthy subjects undergoing allogeneic PBPC donation. Donors received a standardized mobilization regime consisting of a 4-day course of G-CSF, with leukapheresis on day 5. Endogenous serum flt3-L and SCF were determined prior to G-CSF administration, on the day of leukapheresis, and followed up until day +100 after cessation of G-CSF administration. The administration of G-CSF resulted in a transient elevation of endogenous flt3-L serum levels. At the day of leukapheresis serum flt3-L showed a median increase of 75% compared to serum flt3-L levels obtained before G-CSF treatment. The increase in serum flt3-L levels showed no correlation with the total number of progenitor cells mobilized. Cessation of G-CSF treatment led to normalization of serum flt3-L within 7 days post G-CSF administration. In contrast, serum CSF levels remained unchanged in response to G-CSF administration. Our results demonstrate a transient surge in serum flt3-L in relation to G-CSF-induced PBPC mobilization, although the assessment of endogenous flt3-L give no information regarding the ability for G-CSF-induced PBPC recruitment in healthy individuals.