Granulocyte colony-stimulating factor improves neuron survival in experimental spinal cord injury by regulating nucleophosmin-1 expression

Granulocyte colony-stimulating factor effects on neurological and motor function in animals with spinal cord injury: a systematic review and meta-analysis

Background

Spinal cord injury (SCI) is a severe neurological injury for which no effective treatment exists. Granulocyte colony-stimulating factor (G-CSF) is used to treat autologous bone marrow transplantation, chemotherapy-induced granulocytopenia, Acquired Immune Deficiency Syndrome (AIDS), etc. Recent research has revealed the potential application of G-CSF on neuroprotective effectiveness. In central nervous system diseases, G-CSF can be used to alleviate neuronal injury.

Objective

To investigate the effects of G-CSF on Basso, Beattie, and Bresnahan (BBB) scale score, inclined plane test, electrophysiologic exam, quantitative analysis of TUNEL-positive cells, and quantitative analysis of glial fibrillary acidic protein (GFAP) immunostaining images in animal models of SCI.

Methods

We searched PubMed, Web of Science, and Embase databases for all articles on G-CSF intervention with animal models of SCI reported before November 2022. A total of 20 studies met the inclusion criteria.

Results

Results revealed that G-CSF intervention could improve the BBB scale score in both groups at 3, 7, 14, 28, and 35 days [at 35  days, weighted mean differences (WMD) = 2.4, 95% CI: 1.92-2.87, p < 0.00001, I² = 69%]; inclined plane test score; electrophysiologic exam; quantitative analysis of TUNEL-positive cell numbers; quantitative analysis of GFAP immunostaining images in animal models of SCI. Subgroup analysis revealed that treatment with normal saline, phosphate-buffered saline, and no treatment resulted in significantly different neurological function effectiveness compared to the G-CSF therapy. SD rats and Wistar rats with SCI resulted in significant neurological function effectiveness. C57BL/6 mice showed no difference in the final effect. The T9-T10 or T10 segment injury model and the T8-T9 or T9 segment injury model resulted in significant neurological function effectiveness. The BBB score data showed no clear funnel plot asymmetry. We found no bias in the analysis result (Egger's test, p = 0.42). In our network meta-analysis, the SUCRA ranking showed that 15 mg/kg-20 mg/kg was an optimal dose for long-term efficacy.

Conclusion

Our meta-analysis suggests that G-CSF therapy may enhance the recovery of motor activity and have a specific neuroprotective effect in SCI animal models.Systematic review registration: PROSPERO, identifier: CRD42023388315.

A review of granulocyte colony-stimulating factor receptor signaling and regulation with implications for cancer

Granulocyte colony-stimulating factor receptor (GCSFR) is a critical regulator of granulopoiesis. Studies have shown significant upregulation of GCSFR in a variety of cancers and cell types and have recognized GCSFR as a cytokine receptor capable of influencing both myeloid and non-myeloid immune cells, supporting pro-tumoral actions. This systematic review aims to summarize the available literature examining the mechanisms that control GCSFR signaling, regulation, and surface expression with emphasis on how these mechanisms may be dysregulated in cancer. Experiments with different cancer cell lines from breast cancer, bladder cancer, glioma, and neuroblastoma are used to review the biological function and underlying mechanisms of increased GCSFR expression with emphasis on actions related to tumor proliferation, migration, and metastasis, primarily acting through the JAK/STAT pathway. Evidence is also presented that demonstrates a differential physiological response to aberrant GCSFR signal transduction in different organs. The lifecycle of the receptor is also reviewed to support future work defining how this signaling axis becomes dysregulated in malignancies.

Endogenous Expression of G-CSF in Rat Dorsal Root Ganglion Neurons after Nerve Injury

Granulocyte colony-stimulating factor (G-CSF) has been reported to modulate pain function following nerve injury. However, the expression of endogenous G-CSF in the dorsal root ganglion (DRG) and the response to nerve injury remain unclear. In the present study, we demonstrated that G-CSF and G-CSFR are mainly expressed in both small- and medium-diameter DRG neurons in rats and are responsible for transmitting pain responses. G-CSF and G-CSFR were co-expressed in certain nociceptive DRG neurons. In addition, G-CSF was expressed in satellite glial cells around large-diameter DRG neurons. After sciatic nerve injury, the number of G-CSF-positive DRG neurons was increased in both the ipsilateral and contralateral lesion sites in rats. However, G-CSF expression in satellite glial cells was not affected by nerve injury. To clarify the role of G-CSF in pain, exogenous G-CSF was administered to a rat model of neuropathic pain induced by partial sciatic nerve transaction (PST). Our results indicate that treatment with G-CSF did not attenuate but exacerbated neuropathic pain. In summary, G-CSF may directly activate sensory neurons and contribute to nociceptive signaling.

Neurogenic Heterotopic Ossifications Develop Independently of Granulocyte Colony-Stimulating Factor and Neutrophils

Neurogenic heterotopic ossifications (NHOs) are incapacitating heterotopic bones in periarticular muscles that frequently develop following traumatic brain or spinal cord injuries (SCI). Using our unique model of SCI-induced NHO, we have previously established that mononucleated phagocytes infiltrating injured muscles are required to trigger NHO via the persistent release of the pro-inflammatory cytokine oncostatin M (OSM). Because neutrophils are also a major source of OSM, we investigated whether neutrophils also play a role in NHO development after SCI. We now show that surgery transiently increased granulocyte colony-stimulating factor (G-CSF) levels in blood of operated mice, and that G-CSF receptor mRNA is expressed in the hamstrings of mice developing NHO. However, mice defective for the G-CSF receptor gene Csf3r, which are neutropenic, have unaltered NHO development after SCI compared to C57BL/6 control mice. Because the administration of recombinant human G-CSF (rhG-CSF) has been trialed after SCI to increase neuroprotection and neuronal regeneration and has been shown to suppress osteoblast function at the endosteum of skeletal bones in human and mice, we investigated the impact of a 7-day rhG-CSF treatment on NHO development. rhG-CSF treatment significantly increased neutrophils in the blood, bone marrow, and injured muscles. However, there was no change in NHO development compared to saline-treated controls. Overall, our results establish that unlike monocytes/macrophages, neutrophils are dispensable for NHO development following SCI, and rhG-CSF treatment post-SCI does not impact NHO development. Therefore, G-CSF treatment to promote neuroregeneration is unlikely to adversely promote or affect NHO development in SCI patients. © 2020 American Society for Bone and Mineral Research.

Cellular cytokine receptor signaling and ATM pathway intersections affect hepatic DNA repair

Pathways involving ataxia telangiectasia mutated (ATM) gene and its downstream partners and effectors are critical for the DNA damage response. Cell survival, proliferation and tissue homeostasis are dependent upon preservation of DNA integrity but additional intracellular mechanisms contribute in these processes. As receptor-mediated signaling with beneficial intersections in ATM pathways could have therapeutic significance, we interrogated such intersections with assays using HuH-7 cells (hepatocytes). These cells were subjected to acetaminophen toxicity, which is a leading cause of hepatic injury and acute liver failure in people. The ATM pathway was examined in HuH-7-ATM-Prom-tdT cells containing fluorescent td-Tomato transgene reporter for ATM promoter activity. Titrated doses of specific growth factors were used as ligands for receptor-mediated signaling. The contribution of JAK/STAT3 signaling was defined by the loss-of-function approach with the JAK antagonist, ruxolitinib. In these assays, impairment in ATM-related DNA damage response following acetaminophen toxicity was ameliorated by selected growth factors, including fibroblast growth factors, granulocyte colony stimulating factor and vascular endothelial growth factor. The JAK/STAT3 signaling was exclusive to granulocyte colony stimulating factor but concerned additional pathways in cases of other growth factors. Antagonism of JAK/STAT3 by ruxolitinib abrogated benefits in ATM pathway-mediated DNA repair; and identification of the ruxolitinib-sensitive component of cytoprotection allowed separations of these pathway intersections. Therefore, this subtractive approach for ATM and other regulators in pathways will be informative for DNA damage response. These mechanisms will benefit therapeutic development for ATM-related tissue and organ injuries.

[Effect of granulocyte colony-stimulating factor mobilizing bone marrow mesenchymal stell cells homing to injury sites in spinal cord injury of rats]

Objective

To investigate the effect of granulocyte colony-stimulating factor (G-CSF) mobilizing the bone marrow mesenchymal stem cells (BMSCs) homing to the spinal cord injury sites in rats, and to evaluate the feasibility of G-CSF mobilizing the BMSCs home to the injured spinal cord.

Methods

Twenty-four healthy adult female Sprague Dawley rats were injected with 1 mL green fluorescence protein labeled BMSCs (GFP-BMSCs, 1×10 ⁶ cells/mL) into tail vein at 12 hours before operation. They were randomly divided into sham operation group (group A), sham operation+G-CSF group (group B), spinal cord injury group (group C), and spinal cord injury+G-CSF group (group D), with 6 rats in each group. In groups C and D, spinal cord injury model was established by T ₁₀ level spinal cord hemisection. In groups A and B, only laminectomy was performed without injury to the spinal cord. Groups B and D were injected with G-CSF (10 μg/kg·d) at 1 hour after operation for 3 consecutive days, and groups A and C were injected with the same amount of saline. The Basso-Beattie-Bresnahan (BBB) score was used to estimate the neurological function of rats and the expressions of tumor necrosis factor α (TNF-α) and stromal-derived factor 1 (SDF-1) were detected by ELISA method at 1, 3, 7, 14, 21, and 28 days after operation. The spinal cord samples of rats were sacrificed at 28 days after operation for immunohistochemical staining to observe the expression of cytokines, including SDF-1, brain derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), and TNF-α, and immunofluorescence staining to observe GFP-BMSCs positive cells, double-stained fluorescent yellow GFP/neuronal nuclear antigen (NeuN) positive neurons, and GFP/glial fibrillary acidic protein (GFAP) positive neurons. The number of glial cells and apoptosis were detected by TUNEL method.

Results

The BBB score of groups A and B had no significant change at each time point after operation. At 1 day after operation, the BBB score of groups C and D decreased to the lowest level, and then gradually increased. The BBB score of group D was significantly higher than that of group C at all time points except 1 day after operation ( P<0.05). At 3, 7, 14, 21, 28 days after operation, the levels of TNF-α and SDF-1 in groups C and D were significantly higher than those in groups A and B ( P<0.05), but the levels of TNF-α in group D were significantly lower than those in group C at each time point, and the levels of SDF-1 were significantly higher than those in group C ( P<0.05). Immunohistochemical staining showed that the expressions of SDF-1, BDNF, VEGF, and TNF-α in groups C and D were significantly higher than those in groups A and B ( P<0.05); the expressions of SDF-1, BDNF, and VEGF in group D were significantly higher than those in group C, and the expression of TNF-α was significantly lower than that in group C ( P<0.05). Immunofluorescence staining showed that the number of GFP-BMSCs, GFP/NeuN, and GFP/GFAP positive cells in groups C and D were significantly higher than those in groups A and B, and in group D than in group C ( P<0.05). TUNEL assay showed that the number of apoptotic cells in groups C and D was significantly lower than that in groups A and B, and in group D than in group C ( P<0.05).

Conclusion

G-CSF can mobilize BMSCs to the spinal cord injury site and promote repair effect by down-regulating TNF-α to promote the anti-apoptosis function and up-regulating SDF-1, BDNF, VEGF to promote BMSCs migration.

Regulation of Inflammatory Cytokines for Spinal Cord Injury Repair Through Local Delivery of Therapeutic Agents

The balance of inflammation is critical to the repair of spinal cord injury (SCI), which is one of the most devastating traumas in human beings. Inflammatory cytokines, the direct mediators of local inflammation, have differential influences on the repair of the injured spinal cord. Some inflammatory cytokines are demonstrated beneficial to spinal cord repair in SCI models, while some detrimental. Various animal researches have revealed that local delivery of therapeutic agents efficiently regulates inflammatory cytokines and promotes repair from SCI. Quite a few clinical studies have also shown the promotion of repair from SCI through regulation of inflammatory cytokines. However, local delivery of a single agent affects only a part of the inflammatory cytokines that need to be regulated. Meanwhile, different individuals have differential profiles of inflammatory cytokines. Therefore, future studies may aim to develop personalized strategies of locally delivered therapeutic agent cocktails for effective and precise regulation of inflammation, and substantial functional recovery from SCI.

Level-Specific Differences in Systemic Expression of Pro- and Anti-Inflammatory Cytokines and Chemokines after Spinal Cord Injury

While over half of all spinal cord injuries (SCIs) occur in the cervical region, the majority of preclinical studies have focused on models of thoracic injury. However, these two levels are anatomically distinct—with the cervical region possessing a greater vascular supply, grey-white matter ratio and sympathetic outflow relative to the thoracic region. As such, there exists a significant knowledge gap in the secondary pathology at these levels following SCI. In this study, we characterized the systemic plasma markers of inflammation over time (1, 3, 7, 14, 56 days post-SCI) after moderate-severe, clip-compression cervical and thoracic SCI in a rat model. Using high-throughput ELISA panels, we observed a clear level-specific difference in plasma levels of VEGF, leptin, IP10, IL18, GCSF, and fractalkine. Overall, cervical SCI had reduced expression of both pro- and anti-inflammatory proteins relative to thoracic SCI, likely due to sympathetic dysregulation associated with higher level SCIs. However, contrary to the literature, we did not observe level-dependent splenic atrophy with our incomplete SCI model. This is the first study to compare the systemic plasma-level changes following cervical and thoracic SCI using level-matched and time-matched controls. The results of this study provide the first evidence in support of level-targeted intervention and also challenge the phenomenon of high SCI-induced splenic atrophy in incomplete SCI models.

Granulocyte-colony stimulating factor administration for neurological improvement in patients with postrehabilitation chronic incomplete traumatic spinal cord injuries: a double-blind randomized controlled clinical trial

OBJECTIVE

Granulocyte-colony stimulating factor (G-CSF) is a major growth factor for activation and differentiation of granulocyte colonies in the bone marrow. This cytokine has been widely and safely employed in different conditions over many years. The purpose of this study was to investigate the efficacy of G-CSF administration for traumatic spinal cord injury (TSCI).

METHODS

This double-blind parallel randomized, placebo-controlled, clinical trial, a phase III study, was performed from June 2013 to June 2016 in the Brain and Spinal Cord Injury Research (BASIR) center at Tehran University of Medical Sciences (TUMS). It included 120 patients with incomplete chronic TSCI, American Spinal Injury Association (ASIA) Impairment Scale (AIS) B, C, or D, of at least 6 months’ duration. Sixty patients were allocated into the treatment group and 60 patients into the control group. All the patients had completed an outpatient rehabilitation program in the postacute period and were in a neurological and functional plateau. Patients were assessed with the ASIA grading system, the Spinal Cord Independence Measure (SCIM-III), and the International Association of Neurorestoratology-Spinal Cord Injury Functional Rating Scale (IANR-SCIFRS) just before intervention and at 1, 3, and 6 months after 7 subcutaneous administrations of 300 μg/day of G-CSF in the treatment group and placebo in the control group (administered once per day over the course of 1 week). Randomization was performed with randomized block design, and the patients and evaluators were blinded regarding the treatment groups. One patient did not receive the entire allocated intervention and 5 patients were lost to follow-up. Thus data from 114 patients were included in the analysis.

RESULTS

One hundred twenty patients were randomized and allocated into the study groups. Among them, 56 patients (93.3%) in the G-CSF group and 58 patients (96.6%) in the placebo group completed the study protocol. After 6 months of follow-up, AIS in the placebo group remained unchanged, whereas in the G-CSF group, 1 patient improved from AIS B to C, and 4 patients improved from AIS C to D. The mean (± SE) improvement in ASIA motor score in the G-CSF group was 5.5 ± 0.62, which was significantly more than in the placebo group (0.77 ± 0.20) (p < 0.001). The mean light touch and pinprick sensory scores, respectively, increased by 6.1 ± 1.1 and 8.7 ± 1.5 in the G-CSF group and by 1.3 ± 0.52 and 0.89 ± 0.44 scores in the placebo group (p < 0.001). Evaluation of functional improvement by the IANR-SCIFRS instrument revealed significantly more improvement in the G-CSF group (3.5 ± 0.37) than in the placebo group (0.41 ± 0.12) (p < 0.001). Also, a significant difference was observed in functional improvement between the 2 groups as measured by SCIM-III instrument (7.5 ± 0.95 vs 2.1 ± 0.51, p < 0.001).

CONCLUSIONS

Administration of G-CSF for incomplete chronic spinal cord injuries is associated with significant motor, sensory, and functional improvement.

Clinical trial registration no.: IRCT201108297441N1 (www.irct.ir)

Combined Transcriptomics, Proteomics and Bioinformatics Identify Drug Targets in Spinal Cord Injury

Spinal cord injury (SCI) causes irreversible tissue damage and severe loss of neurological function. Currently, there are no approved treatments and very few therapeutic targets are under investigation. Here, we combined 4 high-throughput transcriptomics and proteomics datasets, 7 days and 8 weeks following clinically-relevant rat SCI to identify proteins with persistent differential expression post-injury. Out of thousands of differentially regulated entities our combined analysis identified 40 significantly upregulated versus 48 significantly downregulated molecules, which were persistently altered at the mRNA and protein level, 7 days and 8 weeks post-SCI. Bioinformatics analysis was then utilized to identify currently available drugs with activity against the filtered molecules and to isolate proteins with known or unknown function in SCI. Our findings revealed multiple overlooked therapeutic candidates with important bioactivity and established druggability but with unknown expression and function in SCI including the upregulated purine nucleoside phosphorylase (PNP), cathepsins A, H, Z (CTSA, CTSH, CTSZ) and proteasome protease PSMB10, as well as the downregulated ATP citrate lyase (ACLY), malic enzyme (ME1) and sodium-potassium ATPase (ATP1A3), amongst others. This work reveals previously unappreciated therapeutic candidates for SCI and available drugs, thus providing a valuable resource for further studies and potential repurposing of existing therapeutics for SCI.

Granulocyte Colony-Stimulating Factor (G-CSF) for the Treatment of Spinal Cord Injury

Spinal cord injury (SCI) is a common medical condition with a poor prognosis for recovery and catastrophic effects on a patient's quality of life. Available treatments for SCI are limited, and the evidence suggesting their harmful side effects is more consistent than any suggestion of clinical benefit. Developing novel safe and effective therapeutic options for SCI is crucial. Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic cytokine with known multifaceted effects on the central nervous system. Herein, we review the accumulating preclinical evidence for the beneficial effects of G-CSF on functional and structural outcomes after SCI. Meanwhile we present and discuss multiple mechanisms for G-CSF's neuroprotective and neuroregenerative actions through the results of these studies. In addition, we present the available clinical evidence indicating the efficacy and safety of G-CSF administration for the treatment of acute and chronic traumatic SCI, compression myelopathy, and SCI-associated neuropathic pain. Our review indicates that although the quality of clinical evidence regarding the use of G-CSF in SCI is inadequate, the encouraging available preclinical and clinical data warrant its further clinical development, and bring new hope to the longstanding challenge that is treatment of SCI.

Early applications of granulocyte colony-stimulating factor (G-CSF) can stabilize the blood-optic-nerve barrier and ameliorate inflammation in a rat model of anterior ischemic optic neuropathy (rAION)

Granulocyte colony-stimulating factor (G-CSF) was reported to have a neuroprotective effect in a rat model of anterior ischemic optic neuropathy (rAION model). However, the therapeutic window and anti-inflammatory effects of G-CSF in a rAION model have yet to be elucidated. Thus, this study aimed to determine the therapeutic window of G-CSF and investigate the mechanisms of G-CSF via regulation of optic nerve (ON) inflammation in a rAION model. Rats were treated with G-CSF on day 0, 1, 2 or 7 post-rAION induction for 5 consecutive days, and a control group were treated with phosphate-buffered saline (PBS). Visual function was assessed by flash visual evoked potentials at 4 weeks post-rAION induction. The survival rate and apoptosis of retinal ganglion cells were determined by FluoroGold labeling and TUNEL assay, respectively. ON inflammation was evaluated by staining of ED1 and Iba1, and ON vascular permeability was determined by Evans Blue extravasation. The type of macrophage polarization was evaluated using quantitative real-time PCR (qRT-PCR). The protein levels of TNF-α and IL-1β were analyzed by western blotting. A therapeutic window during which G-CSF could rescue visual function and retinal ganglion cell survival was demonstrated at day 0 and day 1 post-infarct. Macrophage infiltration was reduced by 3.1- and 1.6-fold by G-CSF treatment starting on day 0 and 1 post-rAION induction, respectively, compared with the PBS-treated group (P<0.05). This was compatible with 3.3- and 1.7-fold reductions in ON vascular permeability after G-CSF treatment compared with PBS treatment (P<0.05). Microglial activation was increased by 3.8- and 3.2-fold in the early (beginning treatment at day 0 or 1) G-CSF-treated group compared with the PBS-treated group (P<0.05). Immediate (within 30 mins of infarct) treatment with G-CSF also induced M2 microglia/macrophage activation. The cytokine levels were lower in the group that received immediate G-CSF treatment compared to those in the later G-CSF treatment group (P<0.05). Early treatment with G-CSF stabilized the blood-ON barrier to reduce macrophage infiltration and induced M2 microglia/macrophage polarization to decrease the expressions of pro-inflammatory cytokines in this rAION model.

G-CSF promotes autophagy and reduces neural tissue damage after spinal cord injury in mice

Granulocyte colony-stimulating factor (G-CSF) was investigated for its capacity to induce autophagy and related neuroprotective mechanisms in an acute spinal cord injury model. To accomplish this goal, we established a mouse spinal cord hemisection model to test the effects of recombinant human G-CSF. The results showed that autophagy was activated after spinal cord injury and G-CSF appears to induce a more rapid activation of autophagy within injured spinal cords as compared with that of non-treated animals. Apoptosis as induced in mechanically injured neurons with G-CSF treatment was enhanced after inhibiting autophagy by 3-methyladenine (3-MA), which partially blocked the neuroprotective effect of autophagy as induced by G-CSF. In addition, G-CSF inhibited the activity of the NF-κB signal pathway in neurons after mechanical injury. We conclude that G-CSF promotes autophagy by inhibiting the NF-κB signal pathway and protects neuronal structure after spinal cord injury. We therefore suggest that G-CSF, which rapidly induces autophagy after spinal cord injury to inhibit neuronal apoptosis, may thus provide an effective auxiliary therapeutic intervention for spinal cord injury.

Insights into the regulation of neuronal viability by nucleophosmin/B23

The vastness of the neuronal network that constitutes the human brain proves challenging when trying to understand its complexity. Furthermore, due to the senescent state they enter into upon maturation, neurons lack the ability to regenerate in the face of insult, injury or death. Consequently, their excessive death can be detrimental to the proper functioning of the brain. Therefore, elucidating the mechanisms regulating neuronal survival is, while challenging, of great importance as the incidence of neurological disease is becoming more prevalent in today's society. Nucleophosmin/B23 (NPM) is an abundant and ubiquitously expressed protein that regulates vital cellular processes such as ribosome biogenesis, cell proliferation and genomic stability. As a result, it is necessary for proper embryonic development, but has also been implicated in many cancers. While highly studied in the context of proliferative cells, there is a lack of understanding NPM's role in post-mitotic neurons. By exploring its role in healthy neurons as well as its function in the regulation of cell death and neurodegeneration, there can be a better understanding of how these diseases initiate and progress. Owing to what is thus far known about its function in the cell, NPM could be an attractive therapeutic target in the treatment of neurodegenerative diseases.

Neutrophil contribution to spinal cord injury and repair

Spinal cord injuries remain a critical issue in experimental and clinical research nowadays, and it is now well accepted that the immune response and subsequent inflammatory reactions are of significant importance in regulating the damage/repair balance after injury. The role of macrophages in such nervous system lesions now becomes clearer and their contribution in the wound healing process has been largely described in the last few years. Conversely, the contribution of neutrophils has traditionally been considered as detrimental and unfavorable to proper tissue regeneration, even if there are very few studies available on their precise impact in spinal cord lesions. Indeed, recent data show that neutrophils are required for promoting functional recovery after spinal cord trauma. In this review, we gathered recent evidence concerning the role of neutrophils in spinal cord injuries but also in some other neurological diseases, highlighting the need for further understanding the different mechanisms involved in spinal cord injury and repair.