Seeing old friends from a different angle: Novel properties of hematopoietic growth factors in the healthy and diseased brain

Identification of a novel METTL23 gene variant in a patient with an intellectual development disorder: a literature review and case report

METTL23 belongs to a family of protein lysine methyltransferases that methylate non-histone proteins. Recently, the METTL23 gene has been reported to be related to an intellectual developmental disorder, autosomal recessive 44. Patients present with developmental delay, intellectual disability (ID), and variable dysmorphic features. Here, we report on a Chinese girl who presented with global developmental delay, abnormal brain structure, and multiple facial deformities, including a short/upturned nose with a sunken bridge, thin lips, and flat occiput. Whole-exome sequencing identified a novel variant (NM_001080510.5: c.322+1del) on the METTL23 gene. This variant was not collected on public human variants databases such as gnomAD, predicted to influence the splicing as a classical splicing variant, and classified as Pathogenic according to the American College of Medical Genetics and Genomics (ACMG) guidelines. Since patients with METTL23-related ID are rare, we summarize and compare the clinical phenotype of reported patients with METTL23 variants. Our report further expands the METTL23 variants and provides new evidence for clinical diagnosis of METTL23-related ID.

Clenbuterol attenuates immune reaction to lipopolysaccharide and its relationship to anhedonia in adolescents

While inflammation has been implicated in psychopathology, relationships between immune-suppressing processes and psychiatric constructs remain elusive. This study sought to assess whether β2-agonist clenbuterol (CBL) would attenuate immune activation in adolescents with mood and anxiety symptoms following ex vivo exposure of whole blood to lipopolysaccharide (LPS). Our focus on adolescents aimed to target a critical developmental period when psychiatric conditions often emerge and prior to chronicity effects. To capture a diverse range of immunologic and symptomatologic phenotypes, we included 97 psychotropic-medication free adolescents with mood and anxiety symptoms and 33 healthy controls. All participants had comprehensive evaluations and dimensional assessments of psychiatric symptoms. Fasting whole-blood samples were collected and stimulated with LPS in the presence and absence of CBL for 6 hours, then analyzed for 41 cytokines, chemokines, and hematopoietic growth factors. Comparison analyses used Bonferroni-corrected nonparametric tests. Levels of nine immune biomarkers-including IL-1RA, IL-1β, IL-6, IP-10, MCP-1, MIP-1α, MIP-1β, TGF-α, and TNF-α-were significantly reduced by CBL treatment compared to LPS alone. Exploratory factor analysis reduced 41 analytes into 5 immune factors in each experimental condition, and their relationships with psychiatric symptoms were examined as a secondary aim. CBL + LPS Factor 4-comprising EGF, PDGF-AA, PDGF-AB/BB, sCD40L, and GRO-significantly correlated with anticipatory and consummatory anhedonia, even after controlling for depression severity. This study supports the possible inhibitory effect of CBL on immune activation. Using a data-driven method, distinctive relationships between CBL-affected immune biomarkers and dimensional anhedonia were reported, further elucidating the role of β2-agonism in adolescent affective symptomatology.

Granulocyte-colony stimulating factor (G-CSF): an emerging therapeutic approach for amyotrophic lateral sclerosis (ALS)

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by neuronal degeneration and inflammation in the nerves. G-CSF is a 19.6-kDa hematopoietic growth factor which is essential for the proliferation and differentiation of granulocyte hematopoietic progenitors. G-CSF exerts neuroprotective activities by induction of neuronal regeneration, inhibition of neuronal apoptosis, mobilization of Hematopoietic stem cells (HSCs), regulation of pro and anti-inflammatory cytokines, and activation of angiogenesis. Pre-clinical studies have shown significant efficacy of G-CSF therapy in mSOD1^G93A mice models. G-CSF treatments were able to increase the survival of mice. However, clinical studies on ALS patients failed to clone pre-clinical results. Considering the potential role of G-CSF in nervous system regeneration, this study aimed to comprehensively review the clinical and pre-clinical studies addressing G-CSF in ALS treatment.

Microglia in Neuroinflammation and Neurodegeneration: From Understanding to Therapy

Microglia are the resident macrophages of the central nervous system (CNS) acting as the first line of defense in the brain by phagocytosing harmful pathogens and cellular debris. Microglia emerge from early erythromyeloid progenitors of the yolk sac and enter the developing brain before the establishment of a fully mature blood-brain barrier. In physiological conditions, during brain development, microglia contribute to CNS homeostasis by supporting cell proliferation of neural precursors. In post-natal life, such cells contribute to preserving the integrity of neuronal circuits by sculpting synapses. After a CNS injury, microglia change their morphology and down-regulate those genes supporting homeostatic functions. However, it is still unclear whether such changes are accompanied by molecular and functional modifications that might contribute to the pathological process. While comprehensive transcriptome analyses at the single-cell level have identified specific gene perturbations occurring in the "pathological" microglia, still the precise protective/detrimental role of microglia in neurological disorders is far from being fully elucidated. In this review, the results so far obtained regarding the role of microglia in neurodegenerative disorders will be discussed. There is solid and sound evidence suggesting that regulating microglia functions during disease pathology might represent a strategy to develop future therapies aimed at counteracting brain degeneration in multiple sclerosis, Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis.

Circulating granulocyte colony-stimulating factor and functional outcome after ischemic stroke: an observational study

Objectives: While granulocyte colony-stimulating factor (G-CSF) has shown beneficial effects in experimental ischemic stroke (IS), these effects have not been reproduced clinically. Small-to-medium-sized observational studies have reported varying associations for G-CSF with stroke severity and post-stroke functional outcome, prompting their investigation in a larger study.Methods: Endogenous serum G-CSF (S-GCSF) was measured in the acute phase and after 3 months in patients with IS (N = 435; 36% females; mean age, 57 years) from the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS). Stroke severity was scored according to the National Institutes of Health Stroke Scale (NIHSS), and the modified Rankin Scale (mRS) assessed functional outcomes at 3-month and 2-year post-stroke. Correlation and logistic regression analyses with confounder adjustments assessed the relationships.Results: The acute S-GCSF level was 23% higher than at 3-month post-stroke (p < 0.001). Acute G-CSF correlated weakly with stroke severity quintiles (r = 0.12, p = 0.013) and with high-sensitivity C-reactive protein (r = 0.29, p < 0.001). The association between S-GCSF (as quintiles, q) and poor functional outcome at 3 months (mRS 3-6; S-GCSF-q5 vs. S-GCSF-q1, age- and sex-adjusted odds ratio: 4.27, 95% confidence interval: 1.82-9.99; p = 0.001) withstood adjustment for cardiovascular risk factors and stroke subtype, but not additional correction for stroke severity. Post-stroke changes in S-GSCF and absolute 3-month S-GCSF were not associated with 3-month or 2-year functional outcomes.Discussion: Early post-stroke S-GCSF is increased in severe IS and associated with 3-month poor functional outcomes. The change in S-GCSF and the 3-month S-GCSF appear to be less-important, and S-GCSF likely reflects inflammation in large infarctions.

The intestinal microbiome and Alzheimer's disease: A review

Alzheimer's disease (AD) is an increasingly common neurodegenerative disease. Since the intestinal microbiome is closely related to nervous system diseases, alterations in the composition of intestinal microbiota could potentially contribute to the pathophysiology of AD. However, how the initial interactions with intestinal microbes alter events later in life, such as during neurodegenerative diseases, is still unclear. This review summarizes what is known about the relationship between the intestinal microbiome and AD.

Goldfish (Carassius auratus L.) as a model system to study the growth factors, receptors and transcription factors that govern myelopoiesis in fish

The process of myeloid cell development (myelopoiesis) in fish has mainly been studied in three cyprinid species: zebrafish (Danio rerio), ginbuna carp (Carassius auratus langsdorfii) and goldfish (C. auratus, L.). Our studies on goldfish myelopoiesis have utilized in vitro generated primary kidney macrophage (PKM) cultures and isolated primary kidney neutrophils (PKNs) cultured overnight to study the process of macrophage (monopoiesis) and neutrophil (granulopoiesis) development and the key growth factors, receptors, and transcription factors that govern this process in vitro. The PKM culture system is unique in that all three subpopulations of macrophage development, namely progenitor cells, monocytes, and mature macrophages, are simultaneously present in culture unlike mammalian systems, allowing for the elucidation of the complex mixture of cytokines that regulate progressive and selective macrophage development from progenitor cells to fully functional mature macrophages in vitro. Furthermore, we have been able to extend our investigations to include the development of erythrocytes (erythropoiesis) and thrombocytes (thrombopoiesis) through studies focusing on the progenitor cell population isolated from the goldfish kidney. Herein, we review the in vitro goldfish model systems focusing on the characteristics of cell sub-populations, growth factors and their receptors, and transcription factors that regulate goldfish myelopoiesis.

Targeting the prodromal stage of spinocerebellar ataxia type 17 mice: G-CSF in the prevention of motor deficits via upregulating chaperone and autophagy levels

Spinocerebellar ataxia type 17 (SCA17), an autosomal dominant cerebellar ataxia, is a devastating, incurable disease caused by the polyglutamine (polyQ) expansion of transcription factor TATA binding protein (TBP). The polyQ expansion causes misfolding and aggregation of the mutant TBP, further leading to cytotoxicity and cell death. The well-recognized prodromal phase in many forms of neurodegeneration suggests a prolonged period of partial neuronal dysfunction prior to cell loss that may be amenable to therapeutic intervention. The objective of this study was to assess the effects and molecular mechanisms of granulocyte-colony stimulating factor (G-CSF) therapy during the pre-symptomatic stage in SCA17 mice. Treatment with G-CSF at the pre-symptomatic stage improved the motor coordination of SCA17 mice and reduced the cell loss, insoluble mutant TBP protein, and vacuole formation in the Purkinje neurons of these mice. The neuroprotective effects of G-CSF may be produced by increases in Hsp70, Beclin-1, LC3-II and the p-ERK survival pathway. Upregulation of chaperone and autophagy levels further enhances the clearance of mutant protein aggregation, slowing the progression of pathology in SCA17 mice. Therefore, we showed that the early intervention of G-CSF has a neuroprotective effect, delaying the progression of SCA17 in mutant mice via increases in the levels of chaperone expression and autophagy.

The Granulocyte-colony stimulating factor has a dual role in neuronal and vascular plasticity

Granulocyte-colony stimulating factor (G-CSF) is a growth factor that has originally been identified several decades ago as a hematopoietic factor required mainly for the generation of neutrophilic granulocytes, and is in clinical use for that. More recently, it has been discovered that G-CSF also plays a role in the brain as a growth factor for neurons and neural stem cells, and as a factor involved in the plasticity of the vasculature. We review and discuss these dual properties in view of the neuroregenerative potential of this growth factor.

METTL23, a transcriptional partner of GABPA, is essential for human cognition

Whereas many genes associated with intellectual disability (ID) encode synaptic proteins, transcriptional defects leading to ID are less well understood. We studied a large, consanguineous pedigree of Arab origin with seven members affected with ID and mild dysmorphic features. Homozygosity mapping and linkage analysis identified a candidate region on chromosome 17 with a maximum multipoint logarithm of odds score of 6.01. Targeted high-throughput sequencing of the exons in the candidate region identified a homozygous 4-bp deletion (c.169_172delCACT) in the METTL23 (methyltransferase like 23) gene, which is predicted to result in a frameshift and premature truncation (p.His57Valfs*11). Overexpressed METTL23 protein localized to both nucleus and cytoplasm, and physically interacted with GABPA (GA-binding protein transcription factor, alpha subunit). GABP, of which GABPA is a component, is known to regulate the expression of genes such as THPO (thrombopoietin) and ATP5B (ATP synthase, H+ transporting, mitochondrial F1 complex, beta polypeptide) and is implicated in a wide variety of important cellular functions. Overexpression of METTL23 resulted in increased transcriptional activity at the THPO promoter, whereas knockdown of METTL23 with siRNA resulted in decreased expression of ATP5B, thus revealing the importance of METTL23 as a regulator of GABPA function. The METTL23 mutation highlights a new transcriptional pathway underlying human intellectual function.

Identification of a therapeutic dose of continuously delivered erythropoietin in the eye using an inducible promoter system

Erythropoietin (EPO) can protect the retina from acute damage, but long-term systemic treatment induces polycythemia. Intraocular gene delivery of EPO is not protective despite producing high levels of EPO likely due to its bellshaped dose curve. The goal of this study was to identify a therapeutic dose of continuously produced EPO in the eye. We packaged a mutated form of EPO (EPOR76E) that has equivalent neuroprotective activity as wild-type EPO and attenuated erythropoietic activity into a recombinant adeno-associated viral vector under the control of the tetracycline inducible promoter. This vector was injected into the subretinal space of homozygous postnatal 5-7 day retinal degeneration slow mice, that express the tetracycline transactivators from a retinal pigment epithelium specific promoter. At weaning, mice received a single intraperitoneal injection of doxycycline and were then maintained on water with or without doxycycline until postnatal day 60. Intraocular EPO levels and outer nuclear layer thickness were quantified and correlated. Control eyes contained 6.1 ± 0.1 (SEM) mU/ml EPO. The eyes of mice that received an intraperitoneal injection of doxycycline contained 11.8 ± 2.0 (SEM) mU/ml EPO-R76E. Treatment with doxycycline water induced production of 35.9 ± 2.4 (SEM) mU/ml EPO-R76E in the eye. The outer nuclear layer was approximately 8 μm thicker in eyes of mice that received doxycycline water as compared to the control groups. Our data indicates that drug delivery systems should be optimized to deliver at least 36 mU/ml EPO into the eye since this dose was effective for the treatment of a progressive retinal degeneration.

Autocrine signaling based selection of combinatorial antibodies that transdifferentiate human stem cells

We report here the generation of antibody agonists from intracellular combinatorial libraries that transdifferentiate human stem cells. Antibodies that are agonists for the granulocyte colony stimulating factor receptor were selected from intracellular libraries on the basis of their ability to activate signaling pathways in reporter cells. We used a specialized "near neighbor" approach in which the entire antibody library and its target receptor are cointegrated into the plasma membranes of a population of reporter cells. This format favors unusual interactions between receptors and their protein ligands and ensures that the antibody acts in an autocrine manner on the cells that produce it. Unlike the natural granulocyte-colony stimulating factor that activates cells to differentiate along a predetermined pathway, the isolated agonist antibodies transdifferentiated human myeloid lineage CD34+ bone marrow cells into neural progenitors. This transdifferentiation by agonist antibodies is different from more commonly used methods because initiation is agenetic. Antibodies that act at the plasma membrane may have therapeutic potential as agents that transdifferentiate autologous cells.

Pharmacologic inhibition of CXCL10 in combination with anti-malarial therapy eliminates mortality associated with murine model of cerebral malaria

Despite appropriate anti-malarial treatment, cerebral malaria (CM)-associated mortalities remain as high as 30%. Thus, adjunctive therapies are urgently needed to prevent or reduce such mortalities. Overproduction of CXCL10 in a subset of CM patients has been shown to be tightly associated with fatal human CM. Mice with deleted CXCL10 gene are partially protected against experimental cerebral malaria (ECM) mortality indicating the importance of CXCL10 in the pathogenesis of CM. However, the direct effect of increased CXCL10 production on brain cells is unknown. We assessed apoptotic effects of CXCL10 on human brain microvascular endothelial cells (HBVECs) and neuroglia cells in vitro. We tested the hypothesis that reducing overexpression of CXCL10 with a synthetic drug during CM pathogenesis will increase survival and reduce mortality. We utilized atorvastatin, a widely used synthetic blood cholesterol-lowering drug that specifically targets and reduces plasma CXCL10 levels in humans, to determine the effects of atorvastatin and artemether combination therapy on murine ECM outcome. We assessed effects of atorvastatin treatment on immune determinants of severity, survival, and parasitemia in ECM mice receiving a combination therapy from onset of ECM (day 6 through 9 post-infection) and compared results with controls. The results indicate that CXCL10 induces apoptosis in HBVECs and neuroglia cells in a dose-dependent manner suggesting that increased levels of CXCL10 in CM patients may play a role in vasculopathy, neuropathogenesis, and brain injury during CM pathogenesis. Treatment of ECM in mice with atorvastatin significantly reduced systemic and brain inflammation by reducing the levels of the anti-angiogenic and apoptotic factor (CXCL10) and increasing angiogenic factor (VEGF) production. Treatment with a combination of atorvastatin and artemether improved survival (100%) when compared with artemether monotherapy (70%), p<0.05. Thus, adjunctively reducing CXCL10 levels and inflammation by atorvastatin treatment during anti-malarial therapy may represent a novel approach to treating CM patients.

Neural stem cell survival factors

Neural stem and progenitor cells (NSCs and NPs) give rise to the central nervous system (CNS) during embryonic development. NSCs and NPs differentiate into three main cell-types of the CNS; astrocytes, oligodendrocytes, and neurons. NSCs are present in the adult CNS and are important in maintenance and repair. Adult NSCs hold great promise for endogenous or self-repair of the CNS. Intriguingly, NSCs have been implicated as the cells that give rise to brain tumors. Thus, the balance between survival, growth and differentiation is a critical aspect of NSC biology, during development, in the adult, and in disease processes. In this review, we survey what is known about survival factors that control both embryonic and adult NSCs. We discuss the neurosphere culture system as this is widely used to measure NSC activity and behavior in vitro and emphasize the importance of clonality. We define here NSC survival factors in their broadest sense to include any factor that influences survival and proliferation of NSCs and NPs. NSC survival factors identified to date include growth factors, morphogens, proteoglycans, cytokines, hormones, and neurotransmitters. Understanding NSC and NP interaction in response to these survival factors will provide insight to CNS development, disease and repair.

Maximizing neuroprotection: where do we stand?

Brain and spinal cord traumas include blunt and penetrating trauma, disease, and required surgery. Such traumas trigger events such as inflammation, infiltration of inflammatory and other cells, oxidative stress, acidification, excitotoxicity, ischemia, and the loss of calcium homeostasis, all of which cause neurotoxicity and neuron death. To prevent trauma-induced neurological deficits and death, each of the many neurotoxic events that occur in parallel or sequentially must be minimized or prevented. Although neuroprotective techniques have been developed that block single neurotoxic events, most provide only limited neuroprotection and are only applied singly. However, because many neurotoxicity triggers arise from common events, an approach for invoking more effective neuroprotection is to apply multiple neuroprotective methods simultaneously before the many neurotoxic triggers and cascades are initiated and become irreversible. This paper first discusses some triggers of neurotoxicity and neuroprotective mechanisms that block them, including hypothermia, alkalinization, and the administration of adenosine. It then examines how the simultaneous application of these techniques provides significantly greater neuroprotection than is provided by any technique alone. The paper also stresses the importance of determining whether the neuroprotection provided by these techniques can be further enhanced by combining them with additional techniques, such as the systemic administration of glucocorticoids. Finally, the paper stresses the absolute critical importance of applying these techniques within the "golden hour" following trauma, before the many neurotoxic events and cascades are manifest and before the neurotoxic cascades become irreversible.

Characterization of granulocyte colony stimulating factor receptor of the goldfish (Carassius auratus L.)

Granulocyte colony stimulating factor receptor (GCSFR) is a member of the class I cytokine receptor superfamily and signaling through this receptor is important for the proliferation, differentiation and activation of neutrophils and their precursors. In this study we report on the cloning and molecular characterization of goldfish GCSFR. The identified goldfish GCSFR sequence possesses the conserved Ig-like domain, the cytokine receptor homology domain (CRH), three fibronectin domains as well as several intracellular signaling motifs characteristic of other vertebrate GCSFRs. Goldfish gcsfr mRNA was highly expressed in kidney and spleen, and in primary kidney neutrophils. The neutrophils have significantly higher mRNA levels of the transcription factors pu.1 and cebpα, and down-regulated levels of transcription factors important for macrophage development such as egr1 and cjun, compared to progenitor cells from the kidney. The gcsfr mRNA was present in the kidney progenitor cells, albeit at much lower levels compared to the neutrophils, and the expression of gcsfr in progenitor cells was not affected by duration of cultivation. Furthermore, gcsfr mRNA levels were up-regulated in neutrophils after treatment with heat-killed Aeromonas salmonicida A449 or with mitogens. Our results indicate that GCSFR may be a useful marker for fish neutrophils.

Granulocyte colony stimulating factor attenuates inflammation in a mouse model of amyotrophic lateral sclerosis

BACKGROUND

Granulocyte colony stimulating factor (GCSF) is protective in animal models of various neurodegenerative diseases. We investigated whether pegfilgrastim, GCSF with sustained action, is protective in a mouse model of amyotrophic lateral sclerosis (ALS). ALS is a fatal neurodegenerative disease with manifestations of upper and lower motoneuron death and muscle atrophy accompanied by inflammation in the CNS and periphery.

METHODS

Human mutant G93A superoxide dismutase (SOD1) ALS mice were treated with pegfilgrastim starting at the presymptomatic stage and continued until the end stage. After long-term pegfilgrastim treatment, the inflammation status was defined in the spinal cord and peripheral tissues including hematopoietic organs and muscle. The effect of GCSF on spinal cord neuron survival and microglia, bone marrow and spleen monocyte activation was assessed in vitro.

RESULTS

Long-term pegfilgrastim treatment prolonged mutant SOD1 mice survival and attenuated both astro- and microgliosis in the spinal cord. Pegfilgrastim in SOD1 mice modulated the inflammatory cell populations in the bone marrow and spleen and reduced the production of pro-inflammatory cytokine in monocytes and microglia. The mobilization of hematopoietic stem cells into the circulation was restored back to basal level after long-term pegfilgrastim treatment in SOD1 mice while the storage of Ly6C expressing monocytes in the bone marrow and spleen remained elevated. After pegfilgrastim treatment, an increased proportion of these cells in the degenerative muscle was detected at the end stage of ALS.

CONCLUSIONS

GCSF attenuated inflammation in the CNS and the periphery in a mouse model of ALS and thereby delayed the progression of the disease. This mechanism of action targeting inflammation provides a new perspective of the usage of GCSF in the treatment of ALS.