Granulocyte colony-stimulating factor administration increases serum concentrations of soluble selectins

Platelet-derived circulating soluble P-selectin is sufficient to induce hematopoietic stem cell mobilization

BACKGROUND

Granulocyte colony-stimulating factor (G-CSF)-mediated mobilization of hematopoietic stem cells (HSCs) is a well-established method to prepare HSCs for transplantation nowadays. A sufficient number of HSCs is critical for successful HSC transplantation. However, approximately 2-6% of healthy stem cell donors are G-CSF-poor mobilizers for unknown reasons; thus increasing the uncertainties of HSC transplantation. The mechanism underlining G-CSF-mediated HSC mobilization remains elusive, so detailed mechanisms and an enhanced HSC mobilization strategy are urgently needed. Evidence suggests that P-selectin and P-selectin glycoprotein ligand-1 (PSGL-1) are one of the cell-cell adhesion ligand-receptor pairs for HSCs to keep contacting bone marrow (BM) stromal cells before being mobilized into circulation. This study hypothesized that blockage of PSGL-1 and P-selectin may disrupt HSC-stromal cell interaction and facilitate HSC mobilization.

METHODS

The plasma levels of soluble P-selectin (sP-sel) before and after G-CSF administration in humans and male C57BL/6J mice were analyzed using enzyme-linked immunosorbent assay. Male mice with P-selectin deficiency (Selp-/-) were further employed to investigate whether P-selectin is essential for G-CSF-induced HSC mobilization and determine which cell lineage is sP-sel derived from. Finally, wild-type mice were injected with either G-CSF or recombinant sP-sel to investigate whether sP-sel alone is sufficient for inducing HSC mobilization and whether it accomplishes this by binding to HSCs and disrupting their interaction with stromal cells in the BM.

RESULTS

A significant increase in plasma sP-sel levels was observed in humans and mice following G-CSF administration. Treatments of G-CSF induced a decrease in the level of HSC mobilization in Selp-/- mice compared with the wild-type (Selp+/+) controls. Additionally, the transfer of platelets derived from wild-type mice can ameliorate the defected HSC mobilization in the Selp-/- recipients. G-CSF induces the release of sP-sel from platelets, which is sufficient to mobilize BM HSCs into the circulation of mice by disrupting the PSGL-1 and P-selectin interaction between HSCs and stromal cells. These results collectively suggested that P-selectin is a critical factor for G-CSF-induced HSC mobilization.

CONCLUSIONS

sP-sel was identified as a novel endogenous HSC-mobilizing agent. sP-sel injections achieved a relatively faster and more convenient regimen to mobilize HSCs in mice than G-CSF. These findings may serve as a reference for developing and optimizing human HSC mobilization in the future.

Shuxuening injection facilitates neurofunctional recovery via down-regulation of G-CSF-mediated granulocyte adhesion and diapedesis pathway in a subacute stroke mouse model

Post-stroke neural damage is a serious health concern which does not yet have an effective treatment. We have shown previously that Shuxuening injection (SXNI), a Ginkgo biloba extract-based natural medicine, protects brain after an acute ischemic stroke, but its efficacy for post-stroke recovery is not known. This study was to investigate whether SXNI can improve the prognosis of stroke at a subacute phase. Mice with cerebral ischemia-reperfusion injury (CIRI) were established by middle cerebral artery occlusion (MCAO), and drugs or saline were injected by the tail vein every 12 h after reperfusion. The therapeutic effect of SXNI was evaluated by survival rate, modified neurologic severity scores (mNSS), open-field test, locomotive gait patterns, cerebral infarction volume, brain edema and histopathological changes. Subsequently, a combined method of RNA-seq and Ingenuity® Pathway Analysis (IPA) was performed to identify key targets and pathways of SXNI facilitating the prognosis of stroke in mouse brain. The results of the transcriptome analysis were verified by real time reverse transcription-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), western blot (WB) and immunohistochemistry (IHC). The experimental results showed that in the new subacute stroke model, SXNI markedly improves the survival rate, neurological and motor functions and histopathological changes, and significantly reduces cerebral infarction and edema volume. RNA-seq analysis of subacute stroke mice with or without SXNI (3 mL/kg) indicated 963 differentially expressed genes (DEGs) with a fold change ≥ 1.5 and a P-value ≤ 0.01. IPA analysis of DEGs showed that granulocyte adhesion and diapedesis ranked first in the pathway ranking, and the most critical gene regulated by SXNI was G-csf. Simultaneously, RT-PCR, ELISA, WB and IHC results demonstrated that SXNI not only obviously reduced the mRNA expression levels of key genes G-csf, Sele and Mac-1 in this pathway, but also significantly decreased the protein expression levels of G-CSF in serum and E-selectin and MAC-1 in brain tissues. In summary, our research suggested that SXNI can exert a remarkable neurofunctional therapeutic effect on stroke mice via down-regulating G-CSF to inhibit granulocyte adhesion and diapedesis. This study provides experimental evidence that SXNI may fulfill the need for stroke medicine targeting specifically at the recovery stage.

Different effects of granulocyte colony-stimulating factor and erythropoietin on erythropoiesis

Background

Red blood cells are the most abundant cells in the blood that deliver oxygen to the whole body. Erythropoietin (EPO), a positive regulator of erythropoiesis, is currently the major treatment for chronic anemia. Granulocyte colony-stimulating factor (G-CSF) is a multifunctional cytokine and a well-known regulator of hematopoietic stem cell proliferation, differentiation, and mobilization. The use of EPO in combination with G-CSF has been reported to synergistically improve erythroid responses in a group of patients with myelodysplastic syndromes who did not respond to EPO treatment alone; however, the mechanism remains unclear.

Methods

C57BL/6 J mice injected with G-CSF or EPO were used to compare the erythropoiesis status and the efficiency of erythroid mobilization by flow cytometry.

Results

In this study, we found that G-CSF induced more orthochromatophilic erythroblast production than did EPO in the bone marrow and spleen. In addition, in contrast to EPO treatments, G-CSF treatments enhanced the efficiency of the mobilization of newly synthesized reticulocytes into peripheral blood. Our results demonstrated that the effects of G-CSF on erythropoiesis and erythrocytic mobilization were independent of EPO secretion and, in contrast to EPO, G-CSF promoted progression of erythropoiesis through transition of early stage R2 (basophilic erythroblasts) to late stage R4 (orthochromatophilic erythroblasts).

Conclusions

We demonstrate for the first time that G-CSF treatments induce a faster erythropoiesis-enhancing response than that of EPO. These findings suggest an alternative approach to treating acute anemia, especially when patients are experiencing a clinical emergency in remote areas without proper blood bank supplies.

Relapsing acute kidney injury associated with pegfilgrastim

We report a previously unrecognized complication of severe acute kidney injury (AKI) after the administration of pegfilgrastim with biopsy findings of mesangioproliferative glomerulonephritis (GN) and tubular necrosis. A 51-year-old white female with a history of breast cancer presented to the hospital with nausea, vomiting and dark urine 2 weeks after her third cycle of cyclophosphamide and docetaxel along with pegfilgrastim. She was found to have AKI with a serum creatinine (Cr) level of 6.9 mg/dl (baseline 0.7). At that time, her AKI was believed to be related to prior sepsis and/or daptomycin exposure that had occurred 5 weeks earlier. She was dialyzed for 6 weeks, after which her kidney function recovered to near baseline, but her urinalysis (UA) still showed 3.5 g protein/day and dysmorphic hematuria. Repeat blood cultures and serological workup (complement levels, hepatitis panel, ANA, ANCA and anti-GBM) were negative. She received her next cycle of chemotherapy with the same drugs. Two weeks later, she developed recurrent AKI with a Cr level of 6.7 mg/dl. A kidney biopsy showed mesangioproliferative GN, along with tubular epithelial damage and a rare electron-dense glomerular deposit. Pegfilgrastim was suspected as the inciting agent after exclusion of other causes. Her Cr improved to 1.4 mg/dl over the next 3 weeks, this time without dialysis. She had the next 2 cycles of chemotherapy without pegfilgrastim, with no further episodes of AKI. A literature review revealed a few cases of a possible association of filgrastim with mild self-limited acute GN. In conclusion, pegfilgrastim may cause GN with severe AKI. Milder cases may be missed and therefore routine monitoring of renal function and UA is important.

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.

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.

Blood oxidative status and selectins plasma levels in healthy donors receiving granulocyte-colony stimulating factor

Recombinant human G-CSF (rHuG-CSF) is used for hematopoietic progenitor cells (HPC) mobilization and collection. Activation of polymorphonuclear leukocytes (PMN) is present during rHuG-CSF treatment and is associated with endothelial cell dysfunction and hypercoagulation. We evaluated whether PMN activation by rHuG-CSF may alter the blood oxidative status and subsequently affect the vascular cell function. Fourteen healthy individuals received rHuG-CSF for HPC harvesting. Blood was drawn before starting rHuG-CSF (T0), on the last day of rHuG-CSF (T1) and 1 week after stopping rHuG-CSF (T2). Levels of CD11b, myeloperoxidase (MPO), hydroperoxides, nitric oxide (NO), and soluble endothelium (sES), leukocyte (sLS), and platelet (sPS) selectins were measured. During rHuG-CSF, CD11b, MPO and hydroperoxides significantly increased, while NO levels significantly decreased, compared with T0. At T2 all these markers returned to baseline values. Significant increments of all selectins were observed during rHuG-CSF. At T2 sES and sEP significantly decreased back to pre-treatment values, whereas sLS remained significantly high. These data show that rHuG-CSF induces a transient inflammatory status characterized by circulating activated PMN, which release reactive oxygen species and intracellular proteases, promoting the onset of an abnormal oxidative status. This process may modify the hemostatic balance towards a pro-thrombotic state.

Treatment with granulocyte colony-stimulating factor increases interleukin-1 receptor antagonist levels during engraftment following allogeneic stem-cell transplantation

BACKGROUND

The effect of treatment with granulocyte colony-stimulating factor (G-CSF) on interleukin-1 receptor antagonist (IL-1ra) plasma concentrations as well as the role of IL-1ra on leucocyte recovery and parameters of infection within the first 30 days after haematopietic stem-cell transplantation (HSCT) are not well known.

MATERIAL AND METHODS

Twenty-seven patients undergoing myeloablative therapy followed by allogeneic SCT for various haematological disorders were either treated with (n = 18) or without (n = 9) G-CSF. IL-1ra plasma levels were serially determined by ELISA starting at day - 1 and continued until patients were engrafted.

RESULTS

Patients receiving G-CSF had significantly shorter neutropenic periods and significantly lower mean C-reactive protein serum levels during the first 3 weeks succeeding bone marrow transplantation (BMT). Importantly, starting at day + 11 and paralleling the rise of peripheral blood leucocytes, increasing IL-1ra plasma concentrations were observed in both treatment groups. However, the magnitude of the IL-1ra surge was far greater in the G-CSF treatment group. Peak IL-1ra plasma level observed on day + 19 was 882.3 +/- 879.2 pg mL(-1) (mean +/- SD) in patients receiving G-CSF compared with 285.8 +/- 175.2 pg mL(-1) (mean +/- SD) in patients not receiving G-CSF (P = 0.0130). Furthermore, a direct correlation of IL-1ra with peripheral blood leucocytes was verified by the Spearman rank test (P = 0.0025).

CONCLUSION

Granulocyte colony-stimulating factor-mediated acceleration of neutrophil recovery following myeloablative therapy correlated with increased IL-1ra plasma concentrations. Our data suggest that IL-1ra constitutes an intrinsic component of the anti-inflammatory and neutrophil differentiating efficacy of G-CSF and, thus, IL-1ra may be required for the in vivo activity of G-CSF.

Serum levels of soluble E-selectin in women with breast cancer

Background

Increasing evidence suggests that E-selectin contributes to tumour growth and metastasis, possibly by increasing angiogenesis and the adhesion of tumour cells to endothelial cells at distant sites. This study aimed to examine the relationship between preoperative levels of circulating soluble E-selectin and breast cancer.

Methods

Sixty-four consecutive women undergoing surgery for invasive breast cancer were studied prospectively. Venous blood samples were collected before the operation. A control group consisted of 16 patients with a benign breast tumour (eight with fibrocystic disease and eight with fibroadenoma). Serum concentrations of soluble E-selectin were measured by the quantitative sandwich enzyme immunoassay technique and compared with clinicopathological information.

Results

The mean(s.d.) serum level of soluble E-selectin in patients with invasive breast cancer was 73·7(20·9) ng/ml, compared with 36·3(5·6) ng/ml in the control group (P < 0·001). Furthermore, the serum levels of soluble E-selectin were significantly higher in women with oestrogen receptor-negative tumours (P = 0·001), poorly differentiated tumours (P < 0·001), more advanced primary tumour stage (P < 0·001), involved lymph nodes (P < 0·001), distant metastases (P < 0·001) and more advanced tumour node metastasis (TNM) stage (P < 0·001). On multivariate analysis, TNM stage (P < 0·001) was found to be an independent factor with regard to higher serum levels of soluble E-selectin.

Conclusion

Preoperative serum levels of soluble E-selectin might reflect the severity of invasive breast cancer; further evaluation is warranted.

Soluble l-selectin (sCD62L) in relapsed childhood acute lymphoblastic leukaemia

Soluble l-selectin (sCD62L) plasma concentrations at diagnosis and outcome were investigated in 193 children at first relapse of acute lymphoblastic leukaemia (ALL) after treatment according to the Berlin-Frankfurt-Münster relapsed ALL multicentre trials, ALL-REZ BFM 95 and 96. sCD62L was low (< fifth paediatric reference percentile) in 63 (33%) and high (> 95th percentile) in 36 (19%) children, and was independent of remission duration, sex, BCR-ABL fusion or extramedullary disease. High sCD62L was associated with circulating blasts and T-cell phenotype. More initial adverse events occurred in children with high and low levels of sCD62L (23 out of 99) than in those with normal levels (9 out of 94, P = 0.018). Among 75 worst-prognosis patients (risk groups S3/S4, isolated bone marrow relapse occurring less than 6 months after elective cessation of front-line therapy, or T-cell phenotype with bone marrow involvement), 27 had low sCD62L and decreased event-free survival (EFS) probability (PEFS5 = 0.09 at 5 years) and duration (219 d) compared with normal sCD62L (29 out of 75, PEFS5 = 0.24, 640 d, P = 0.01). Low (44 out of 118), normal (72 out of 118), and high (19 out of 118) sCD62L non-S3/S4 patients fared similarly (average PEFS5 = 0.45, 1369 d; P = 0.5). Low sCD62L may be a marker of malignant blasts replacing normal sCD62L-producing haematopoietic cells. In children with first relapse of ALL and worst prognosis, plasma sCD62L may be useful for risk-adapted stratification.

Expression, purification, and in vitro biological activities of recombinant bovine granulocyte-colony stimulating factor

Neutrophils are essential components of the innate immune system and they play a critical role in the defense of host against bacterial and fungal infections. The colony stimulating factors are a class of glycoproteins that are required for proliferation, differentiation, and functional activation of hematopoietic progenitor cells. Granulocyte-colony stimulating factor (G-CSF) is a member of this regulatory family of cytokines that specifically stimulates proliferation and maturation of precursor cells in the bone marrow into fully differentiated and functional neutrophils. G-CSF also modulates the biological activities of mature neutrophils in circulation. A bovine G-CSF (bG-CSF) cDNA clone (previously isolated and sequenced in our laboratory) was expressed in Escherichia coli and the biological activities of the solubilized protein from purified inclusion bodies were examined. Flow cytometric analysis of membrane antigen density of neutrophils activated with bG-CSF revealed an upregulation in the expression of CD11a (>114%), CD11b (>148%), CD11c (>87%), and CD18 (>109%). Expression of L-selectin was decreased by more than 43%. There was no change, however, in the expression of CD14. These findings indicate that recombinant bG-CSF (rbG-CSF) expressed in E. coli is biologically active and exerts the same type of effects on neutrophils in vitro as those of human G-CSF (hG-CSF).

Pretreatment with granulocyte colony-stimulating factor attenuates the inflammatory response but not the bacterial load in cerebrospinal fluid during experimental pneumococcal meningitis in rabbits

A possible immunomodulatory role of granulocyte colony-stimulating factor (G-CSF) was investigated in an experimental pneumococcal meningitis model in rabbits. Animals were pretreated with G-CSF (10 micrograms/kg subcutaneously twice a day) starting 48 h before in vivo and ex vivo experiments, causing a five- to six-fold increase in the peripheral leukocyte level. Meningitis was induced by intracisternal inoculation of approximately 4 x 10(5) CFU of Streptococcus pneumoniae type 3. Neutrophil pleocytosis and interleukin-8 (IL-8) levels were significantly attenuated in G-CSF-pretreated animals compared to untreated animals (P < 0.05). Furthermore, G-CSF pretreatment significantly delayed alterations in cerebrospinal fluid (CSF) tumor necrosis factor alpha and IL-1beta levels, as well as protein and glucose levels (P < 0.05). No difference in CSF bacterial concentrations was found, whereas the blood bacterial concentration was significantly decreased in G-CSF-pretreated animals (P < 0.05). Ex vivo chemotaxis of neutrophils isolated from G-CSF-pretreated animals was significantly decreased compared to that of neutrophils from untreated animals (P < 0.05). In conclusion, G-CSF pretreatment attenuates meningeal inflammation and enhances systemic bacterial killing. Further preclinical studies are required to investigate whether this may affect the clinical course of meningitis and thus whether G-CSF treatment may have a beneficial role in pneumococcal meningitis.