Granulocyte colony stimulating factor decreases brain amyloid burden and reverses cognitive impairment in Alzheimer's mice

Single cell RNA sequencing reveals immunomodulatory effects of stem cell factor and granulocyte colony-stimulating factor treatment in the brains of aged APP/PS1 mice

Alzheimers disease leads to progressive neurodegeneration and dementia. Alzheimers disease primarily affects older adults with neuropathological changes including amyloid beta deposition, neuroinflammation, and neurodegeneration. We have previously demonstrated that systemic treatment with combined stem cell factor, SCF, and granulocyte colony stimulating factor, GCSF, reduces amyloid beta load, increases amyloid beta uptake by activated microglia and macrophages, reduces neuroinflammation, and restores dendrites and synapses in the brains of aged APP-PS1 mice. However, the mechanisms underlying SCF-GCSF-enhanced brain repair in aged APP-PS1 mice remain unclear. This study used a transcriptomic approach to identify potential mechanisms by which SCF-GCSF treatment modulates microglia and peripheral myeloid cells to mitigate Alzheimers disease pathology in the aged brain. After injections of SCF-GCSF for 5 consecutive days, single cell RNA sequencing was performed on CD11b positive cells isolated from the brains of 28-month-old APP-PS1 mice. The vast majority of cell clusters aligned with transcriptional profiles of microglia in various activation states. However, SCF-GCSF treatment dramatically increased a cell population showing upregulation of marker genes related to peripheral myeloid cells. Flow cytometry data also revealed an SCF-GCSF-induced increase of cerebral CD45high-CD11b positive active phagocytes. SCF-GCSF treatment robustly increased the transcription of genes implicated in immune cell activation, including gene sets that regulate inflammatory processes and cell migration. Expression of S100a8 and S100a9 were robustly enhanced following SCF-GCSF treatment in all CD11b positive cell clusters. Moreover, the topmost genes differentially expressed with SCF-GCSF treatment were largely upregulated in S100a8-S100a9 positive cells, suggesting a well-conserved transcriptional profile related to SCF-GCSF treatment in resident and peripherally derived CD11b positive immune cells. This S100a8-S100a9-associated transcriptional profile contained notable genes related to proinflammatory and antiinflammatory responses, neuroprotection, and amyloid beta plaque inhibition or clearance. Altogether, this study reveals immunomodulatory effects of SCF-GCSF treatment in the aged brain with Alzheimers disease pathology, which will guide future studies to further uncover the therapeutic mechanisms.

Association of postoperative delirium with serum and cerebrospinal fluid proteomic profiles: a prospective cohort study in older hip fracture patients

Postoperative delirium (POD) is a common neuropsychiatric complication in geriatric inpatients after hip fracture surgery and its occurrence is associated with poor outcomes. The purpose of this study was to investigate the relationship between preoperative biomarkers in serum and cerebrospinal fluid (CSF) and the development of POD in older hip fracture patients, exploring the possibility of integrating objective methods into future predictive models of delirium. Sixty hip fracture patients were recruited. Blood and CSF samples were collected at the time of spinal anesthesia when none of the subjects had delirium. Patients were assessed daily using the 4AT scale, and based on these results, they were divided into POD and non-POD groups. The Olink® platform was used to analyze 45 cytokines. Twenty-one patients (35%) developed POD. In the subsample of 30 patients on whom proteomic analyses were performed, a proteomic profile was associated with the incidence of POD. Chemokine (C-X-C motif) ligand 9 (CXCL9) had the strongest correlation between serum and CSF samples in patients with POD (rho = 0.663; p < 0.05). Although several cytokines in serum and CSF were associated with POD after hip fracture surgery in older adults, there was a significant association with lower preoperative levels of CXCL9 in CSF and serum. Despite the small sample size, this study provides preliminary evidence of the potential role of molecular biomarkers in POD, which may provide a basis for the development of new delirium predictive models.

CSF biomarkers of immune activation and Alzheimer's disease for predicting cognitive impairment risk in the elderly

The immune system substantially influences age-related cognitive decline and Alzheimer's disease (AD) progression, affected by genetic and environmental factors. In a Mayo Clinic Study of Aging cohort, we examined how risk factors like APOE genotype, age, and sex affect inflammatory molecules and AD biomarkers in cerebrospinal fluid (CSF). Among cognitively unimpaired individuals over 65 (N = 298), we measured 365 CSF inflammatory molecules, finding age, sex, and diabetes status predominantly influencing their levels. We observed age-related correlations with AD biomarkers such as total tau, phosphorylated tau-181, neurofilament light chain (NfL), and YKL40. APOE4 was associated with lower Aβ42 and higher SNAP25 in CSF. We explored baseline variables predicting cognitive decline risk, finding age, CSF Aβ42, NfL, and REG4 to be independently correlated. Subjects with older age, lower Aβ42, higher NfL, and higher REG4 at baseline had increased cognitive impairment risk during follow-up. This suggests that assessing CSF inflammatory molecules and AD biomarkers could predict cognitive impairment risk in the elderly.

Dynamic neuroinflammatory profiles predict Alzheimer's disease pathology in microglia-containing cerebral organoids

Neuroinflammation and the underlying dysregulated immune responses of microglia actively contribute to the progression and, likely, the initiation of Alzheimer's disease (AD). Fine-tuned therapeutic modulation of immune dysfunction to ameliorate disease cannot be achieved without the characterization of diverse microglial states that initiate unique, and sometimes contradictory, immune responses that evolve over time in chronic inflammatory environments. Because of the functional differences between human and murine microglia, untangling distinct, disease-relevant reactive states and their corresponding effects on pathology or neuronal health may not be possible without the use of human cells. In order to profile shifting microglial states in early AD and identify microglia-specific drivers of disease, we differentiated human induced pluripotent stem cells (iPSCs) carrying a familial AD PSEN2 mutation or its isogenic control into cerebral organoids and quantified the changes in cytokine concentrations over time with Luminex XMAP technology. We used partial least squares (PLS) modeling to build cytokine signatures predictive of disease and age to identify key differential patterns of cytokine expression that inform the overall organoid immune milieu and quantified the corresponding changes in protein pathology. AD organoids exhibited an overall reduction in cytokine secretion after an initial amplified immune response. We demonstrate that reduced synapse density observed in the AD organoids is prevented with microglial depletion. Crucially, these differential effects of dysregulated immune signaling occurred without the accumulation of pathological proteins. In this study, we used microglia-containing AD organoids to quantitatively characterize an evolving immune milieu, made up of a diverse of collection of activation patterns and immune responses, to identify how a dynamic, overall neuroinflammatory state negatively impacts neuronal health and the cell-specific contribution of microglia.

Post-exposure self-recovery reverses oxidative stress, ameliorates pathology and neurotransmitters imbalance and rescues spatial memory after time-dependent aluminum exposure in rat brain

Aluminum is a potent neurotoxin, responsible for memory impairment and cognitive dysfunction. The neurotoxic effect of aluminum on cognitive impairment is well documented, however, exposure to aluminum in a time-dependent manner and post-exposure self-recovery still needs to be elaborated. This research aimed to (1) study the time-dependent effect of aluminum exposure by administering a total dose of 5850 mg/kg of Al over two different time periods: 30 and 45 days (130 and 195 mg/kg of AlCl3 respectively), and (2) study 20 days post-exposure self-recovery effect in both aluminum-exposed groups by giving distilled water. Cognitive abilities were investigated through Morris water maze test and hole board test and compared in both exposure and recovery groups. Oxidative stress markers and neurotransmitter levels were measured for both exposure and recovery groups. To understand the mechanism of aluminum exposure and recovery, immunohistochemical analysis of synaptophysin (Syp) and glial fibrillary acidic protein (GFAP) was performed. Results showed cognitive dysfunction, oxidative stress-induced damage, reduced neurotransmitter levels, decreased immunoreactivity of Syp, and increased GFAP. However, these parameters showed a larger improvement in the recovery group where rats were given aluminum for 30 days period in comparison to recovery group followed by 45 days of aluminum exposure. These results suggest that restoration of cognitive ability is affected by the duration of aluminum exposure. The study findings provide us with insight into the adverse effects of aluminum exposure and can be utilized to guide future preventive and therapeutic strategies against aluminum neurotoxicity.

Abnormal DNA methylation analysis of leucine-rich glioma-inactivated 1 antibody encephalitis reveals novel methylation-driven genes related to prognostic and clinical features

BACKGROUND

Aberrant DNA methylation occurs commonly during pathogenesis of neuroimmunological diseases and is of clinical value in various encephalitis subtypes. However, knowledge of the impact of DNA methylation changes on pathogenesis of leucine-rich glioma-inactivated 1 (LGI1) antibody encephalitis remains limited.

METHODS

A total of 44 cytokines and 10 immune checkpoint moleculars (ICMs) in the serum of patients with LGI1 encephalitis and healthy donors (HDs) were measured to evaluate the association of them with clinical parameters. Genome-wide DNA methylation profiles were performed in peripheral blood mononuclear cell (PBMC) from LGI1 encephalitis patients and HDs using reduced representation bisulfite sequencing (RRBS) and validated for the methylation status by pyrosequencing. MicroRNA profiles were acquired in serum exosome by small RNA sequencing. Targeted cytokines expression was assessed at the presence or absence of miR-2467-5p in PBMCs and the culture media, and the binding of miR-2467-5p and its targeted genes was validated by luciferase assay.

RESULTS

There existed significant difference in 22 cytokines/chemokines and 6 ICMs between LGI1 encephalitis patients and HDs. Decreased PDCD1 with increased ICAM1 could predict unfavorable prognosis in one-year follow-up for LGI1 encephalitis patients. Fifteen of cytokines/chemokines and ICMs presented DNA-methylated changes in the promoter and gene body using RRBS in which five were verified as methylation status by pyrosequencing, and the methylation level of CSF3, CCL2, and ICAM1 was conversely associated with their expression in PBMCs. By combining RRBS data with exosome-derived microRNA sequencing, we found that hypomethylated-driven hsa-miR-2467-5p presented elevated expression in serum exosomes and PBMCs in LGI1 encephalitis. Mechanically, miR-2467-5p significantly induced reduced expression of CSF3 and PDCD1 by binding with their 3`UTR while enhanced CCL15 expression, but not significantly correlated with peripheral blood CD19 + B cell proportion of LGI1 encephalitis patients.

CONCLUSIONS

Our results provided convincing evidence for DNA methylation changes, microRNA profiles in serum exosome for LGI1 encephalitis, and we also identified several novel cytokines related to clinical features in which some represented epigenetic modification of methylated-driven pattern and microRNA modulation. Our study contributed to develop treatment for epigenetic pathogenesis in LGI1 encephalitis.

Gut microbiome composition may be an indicator of preclinical Alzheimer's disease

Alzheimer's disease (AD) pathology is thought to progress from normal cognition through preclinical disease and ultimately to symptomatic AD with cognitive impairment. Recent work suggests that the gut microbiome of symptomatic patients with AD has an altered taxonomic composition compared with that of healthy, cognitively normal control individuals. However, knowledge about changes in the gut microbiome before the onset of symptomatic AD is limited. In this cross-sectional study that accounted for clinical covariates and dietary intake, we compared the taxonomic composition and gut microbial function in a cohort of 164 cognitively normal individuals, 49 of whom showed biomarker evidence of early preclinical AD. Gut microbial taxonomic profiles of individuals with preclinical AD were distinct from those of individuals without evidence of preclinical AD. The change in gut microbiome composition correlated with β-amyloid (Aβ) and tau pathological biomarkers but not with biomarkers of neurodegeneration, suggesting that the gut microbiome may change early in the disease process. We identified specific gut bacterial taxa associated with preclinical AD. Inclusion of these microbiome features improved the accuracy, sensitivity, and specificity of machine learning classifiers for predicting preclinical AD status when tested on a subset of the cohort (65 of the 164 participants). Gut microbiome correlates of preclinical AD neuropathology may improve our understanding of AD etiology and may help to identify gut-derived markers of AD risk.

An open-label multiyear study of sargramostim-treated Parkinson's disease patients examining drug safety, tolerability, and immune biomarkers from limited case numbers

BACKGROUND

The clinical utility and safety of sargramostim has previously been reported in cancer, acute radiation syndrome, autoimmune disease, inflammatory conditions, and Alzheimer's disease. The safety, tolerability, and mechanisms of action in Parkinson's disease (PD) during extended use has not been evaluated.

METHODS

As a primary goal, safety and tolerability was assessed in five PD patients treated with sargramostim (Leukine®, granulocyte-macrophage colony-stimulating factor) for 33 months. Secondary goals included numbers of CD4+ T cells and monocytes and motor functions. Hematologic, metabolic, immune, and neurological evaluations were assessed during a 5-day on, 2-day off therapeutic regimen given at 3 μg/kg. After 2 years, drug use was discontinued for 3 months. This was then followed by an additional 6 months of treatment.

RESULTS

Sargramostim-associated adverse events included injection-site reactions, elevated total white cell counts, and bone pain. On drug, blood analyses and metabolic panels revealed no untoward side effects linked to long-term treatment. Unified Parkinson's Disease Rating Scale scores remained stable throughout the study while regulatory T cell number and function were increased. In the initial 6 months of treatment, transcriptomic and proteomic monocyte tests demonstrated autophagy and sirtuin signaling. This finding paralleled anti-inflammatory and antioxidant activities within both the adaptive and innate immune profile arms.

CONCLUSIONS

Taken together, the data affirmed long-term safety as well as immune and anti-inflammatory responses reflecting clinical stability in PD under the sargramostim treatment. Confirmation in larger patient populations is planned in a future phase II evaluation.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03790670, Date of Registration: 01/02/2019, URL: https://clinicaltrials.gov/ct2/show/NCT03790670?cond=leukine+parkinson%27s&draw=2&rank=2 .

Changes in gene expression and neuroinflammation in the hippocampus of rats with poststroke cognitive impairment

Poststroke cognitive impairment (PSCI) often occurs during the stroke recovery period and greatly increases the difficulty of rehabilitation. Activation of neuroinflammation and long-term changes in gene expression patterns in the hippocampus could be essential in the development of PSCI. Therefore, this study aimed to identify neuroinflammation and changes in gene expression patterns in the hippocampus in rats with PSCI. Rats underwent transient middle cerebral artery occlusion (tMCAO) or sham surgery. The infarct volume was measured on day 3 after surgery. The Morris water maze (MWM) test was used to assess cognitive function. Microglial activation and white matter (WM) lesions in the hippocampus were evaluated on day 28 after surgery. In addition, we compared differentially expressed genes (DEGs) in the hippocampus between tMCAO group rats and sham group rats by RNA sequencing. Then, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-protein interaction (PPI) network analyses were conducted to investigate these DEGs. The results showed that the tMCAO group rats showed extensive infarction and cognitive dysfunction compared with the sham group rats. Microglial activation and WM damage were obvious in the hippocampus of tMCAO group rats. We found 43 DEGs by RNA sequencing: 29 genes with upregulated expression and 14 genes with downregulated expression. The GO analysis indicated that DEGs were mainly involved in cell proliferation and differentiation, cholesterol synthesis, and metabolism. The KEGG pathway analysis suggested that the DEGs were significantly enriched in intestinal immune network for IgA production and steroid biosynthesis. Acta2, Calb2, and Cxcl12 were notable in the PPI analysis. Our results suggest that microglial activation and WM damage are maintained in rats with PSCI. The mechanism may be related to the regulation of steroid biosynthesis, intestinal immunity, and potential key genes such as Acta2, Calb2, and Cxcl12 in the hippocampus.

The Role of the Oral Microbiome in the Development of Diseases

Periodontal disease (PD) is a complex and infectious illness that begins with a disruption of bacterial homeostasis. This disease induces a host inflammatory response, leading to damage of the soft and connective tooth-supporting tissues. Moreover, in advanced cases, it can contribute to tooth loss. The aetiological factors of PDs have been widely researched, but the pathogenesis of PD has still not been totally clarified. There are a number of factors that have an effect on the aetiology and pathogenesis of PD. It is purported that microbiological, genetic susceptibility and lifestyle can determine the development and severity of the disease. The human body’s defence response to the accumulation of plaque and its enzymes is known to be a major factor for PD. The oral cavity is colonised by a characteristic and complex microbiota that grows as diverse biofilms on all mucosal and dental surfaces. The aim of this review was to provide the latest updates in the literature regarding still-existing problems with PD and to highlight the role of the oral microbiome in periodontal health and disease. Better awareness and knowledge of the causes of dysbiosis, environmental risk factors and periodontal therapy can reduce the growing worldwide prevalence of PDs. The promotion of good oral hygiene, limiting smoking, alcohol consumption and exposure to stress and comprehensive treatment to decrease the pathogenicity of oral biofilm can help reduce PD as well as other diseases. Evidence linking disorders of the oral microbiome to various systemic diseases has increased the understanding of the importance of the oral microbiome in regulating many processes in the human body and, thus, its impact on the development of many diseases.

Elevated granulocyte colony stimulating factor (CSF) causes cerebellar deficits and anxiety in a model of CSF-1 receptor related leukodystrophy

Colony stimulating factor (CSF) receptor-1 (CSF-1R)-related leukoencephalopathy (CRL) is an adult-onset, demyelinating and neurodegenerative disease caused by autosomal dominant mutations in CSF1R, modeled by the Csf1r+/- mouse. The expression of Csf2, encoding granulocyte-macrophage CSF (GM-CSF) and of Csf3, encoding granulocyte CSF (G-CSF), are elevated in both mouse and human CRL brains. While monoallelic targeting of Csf2 has been shown to attenuate many behavioral and histological deficits of Csf1r+/- mice, including cognitive dysfunction and demyelination, the contribution of Csf3 has not been explored. In the present study, we investigate the behavioral, electrophysiological and histopathological phenotypes of Csf1r+/- mice following monoallelic targeting of Csf3. We show that Csf3 heterozygosity normalized the Csf3 levels in Csf1r+/- mouse brains and ameliorated anxiety-like behavior, motor coordination and social interaction deficits, but not the cognitive impairment of Csf1r+/- mice. Csf3 heterozygosity failed to prevent callosal demyelination. However, consistent with its effects on behavior, Csf3 heterozygosity normalized microglial morphology in the cerebellum and in the ventral, but not in the dorsal hippocampus. Csf1r+/- mice exhibited altered firing activity in the deep cerebellar nuclei (DCN) associated with increased engulfment of glutamatergic synapses by DCN microglia and increased deposition of the complement factor C1q on glutamatergic synapses. These phenotypes were significantly ameliorated by monoallelic deletion of Csf3. Our current and earlier findings indicate that G-CSF and GM-CSF play largely non-overlapping roles in CRL-like disease development in Csf1r+/- mice.

Advances in the study of the relationship between Alzheimer's disease and the gastrointestinal microbiome

There are many trillions of bacteria in the gastrointestinal microbiome (GM). Their ecological dysregulation can contribute to the development of certain neurodegenerative diseases, including Alzheimer's disease (AD). AD is common dementia and its incidence is increasing year by year. However, the relationship between GM and AD is unclear. Therefore, this review discusses the relationship between GM and AD, elaborates on the possible factors that can affect this relationship through the inflammation of the brain induced by blood-brain damage and accumulation of amyloid deposit, and proposes feasible ways to treat AD through GM-related substances, such as probiotics, Mega-3, and gut hormones, including their shortcomings as well.

Administration of Δ9-Tetrahydrocannabinol Following Controlled Cortical Impact Restores Hippocampal-Dependent Working Memory and Locomotor Function

Hypothesis: Administration of the phytocannabinoid Δ9-tetrahydrocannabinol (Δ9-THC) will enhance brain repair and improve short-term spatial working memory in mice following controlled cortical impact (CCI) by upregulating granulocyte colony-stimulating factor (G-CSF) and other neurotrophic factors (brain-derived neurotrophic factor [BDNF], glial-derived neurotrophic factor [GDNF]) in hippocampus (HP), cerebral cortex, and striatum. Materials and Methods: C57BL/6J mice underwent CCI and were treated for 3 days with Δ9-THC 3 mg/kg intraperitoneally (i.p.). Short-term working memory was determined using the spontaneous alternations test during exploratory behavior in a Y-maze. Locomotor function was measured as latency to fall from a rotating drum (rotometry). These behaviors were recorded at baseline and 3, 7, and 14 days after CCI. Groups of mice were euthanized at 7 and 14 days. Extent of microgliosis, astrocytosis, and G-CSF, BDNF, and GDNF expression were measured at 7 and 14 days in cerebral cortex, striatum, and HP on the side of the trauma. Levels of the most abundant endocannabinoid (2-arachidonoyl-glycerol [2-AG]) was also measured at these times. Results: Δ9-THC-treated mice exhibited marked improvement in performance on the Y-maze indicating that treatment with the phytocannabinoid could reverse the deficit in working memory caused by the CCI. Δ9-THC-treated mice ran on the rotarod longer than vehicle-treated mice and recovered to normal rotarod performance levels at 2 weeks. Δ9-THC-treated mice, compared with vehicle-treated animals, exhibited significant upregulation of G-CSF as well as BDNF and GDNF in the cerebral cortex, striatum, and HP. Levels of 2-AG were also increased in the Δ9-THC-treated mice. Conclusion: Administration of the phytocannabinoid Δ9-THC promotes significant functional recovery from traumatic brain injury (TBI) in the realms of working memory and locomotor function. This beneficial effect is associated with upregulation of brain 2-AG, G-CSF, BDNF, and GDNF. The latter three neurotrophic factors have been previously shown to mediate brain self-repair following TBI and stroke.

Recovery from Traumatic Brain Injury Following Treatment with Δ9-Tetrahydrocannabinol Is Associated with Increased Expression of Granulocyte-Colony Stimulating Factor and Other Neurotrophic Factors

Introduction: The hematopoietic cytokine granulocyte-colony stimulating factor (G-CSF) is well known to stimulate proliferation of blood stem/progenitor cells of the leukocyte lineage, but is also recognized as a neurotrophic factor involved in brain self-repair processes. G-CSF administration has been shown to promote recovery from experimental models of traumatic brain injury (TBI) and to modulate components of the endocannabinoid system (eCS). Conversely, Δ9-tetrahydrocannabinol (Δ9THC) treatment of normal mice has been shown to increase blood levels of G-CSF in the periphery. Hypothesis: Administration of the phytocannabinoid Δ9THC will enhance brain repair following controlled cortical impact (CCI) by upregulating G-CSF and other neurotrophic factors (brain-derived neurotrophic factor [BDNF] and glial-derived neurotrophic factor [GDNF]) in brain regions. Materials and Methods: C57BL/6J mice underwent CCI and were treated for 3 days with THC 3 mg/kg intraperitoneally. Motor function on a rotarod was recorded at baseline and 3, 7, and 14 days after CCI. Groups of mice were euthanized at 7 and 14 days. G-CSF, BDNF, and GDNF expression were measured at 7 and 14 days in cerebral cortex, striatum, and hippocampus on the side of the trauma. Results: Δ9THC-treated mice ran on the rotarod longer than vehicle-treated mice and recovered to normal rotarod performance levels at 2 weeks. These mice, compared to vehicle-treated animals, exhibited significant upregulation of G-CSF as well as BDNF and GDNF in cerebral cortex, striatum, and hippocampus. Conclusion: Administration of the phytocannabinoid Δ9THC promotes significant recovery from TBI and is associated with upregulation of brain G-CSF, BDNF, and GDNF, neurotrophic factors previously shown to mediate brain self-repair following TBI and stroke.

Self-Assembled Nanoscale Materials for Neuronal Regeneration: A Focus on BDNF Protein and Nucleic Acid Biotherapeutic Delivery

Enabling challenging applications of nanomedicine and precision medicine in the treatment of neurodegenerative disorders requires deeper investigations of nanocarrier-mediated biomolecular delivery for neuronal targeting and recovery. The successful use of macromolecular biotherapeutics (recombinant growth factors, antibodies, enzymes, synthetic peptides, cell-penetrating peptide–drug conjugates, and RNAi sequences) in clinical developments for neuronal regeneration should benefit from the recent strategies for enhancement of their bioavailability. We highlight the advances in the development of nanoscale materials for drug delivery in neurodegenerative disorders. The emphasis is placed on nanoformulations for the delivery of brain-derived neurotrophic factor (BDNF) using different types of lipidic nanocarriers (liposomes, liquid crystalline or solid lipid nanoparticles) and polymer-based scaffolds, nanofibers and hydrogels. Self-assembled soft-matter nanoscale materials show favorable neuroprotective characteristics, safety, and efficacy profiles in drug delivery to the central and peripheral nervous systems. The advances summarized here indicate that neuroprotective biomolecule-loaded nanoparticles and injectable hydrogels can improve neuronal survival and reduce tissue injury. Certain recently reported neuronal dysfunctions in long-COVID-19 survivors represent early manifestations of neurodegenerative pathologies. Therefore, BDNF delivery systems may also help in prospective studies on recovery from long-term COVID-19 neurological complications and be considered as promising systems for personalized treatment of neuronal dysfunctions and prevention or retarding of neurodegenerative disorders.

Transcranial Electromagnetic Treatment “Rebalances” Blood and Brain Cytokine Levels in Alzheimer’s Patients: A New Mechanism for Reversal of Their Cognitive Impairment

Background

The immune system plays a critical role in the development and progression of Alzheimer’s disease (AD). However, there is disagreement as to whether development/progression of AD involves an over-activation or an under-activation of the immune system. In either scenario, the immune system’s cytokine levels are abnormal in AD and in need of rebalancing. We have recently published a pilot clinical trial (https://clinicaltrials.gov/ct2/show/NCT02958930) showing that 2 months of daily in-home Transcranial Electromagnetic Treatment (TEMT) was completely safe and resulted in reversal of AD cognitive impairment.

Methods

For the eight mild/moderate AD subjects in this published work, the present study sought to determine if their TEMT administration had immunologic effects on blood or CSF levels of 12 cytokines. Subjects were given daily in-home TEMT for 2 months by their caregivers, utilizing first-in-class MemorEM™ devices.

Results

For eight plasma cytokines, AD subjects with lower baseline cytokine levels always showed increases in those cytokines after both a single treatment or after 2-months of daily TEMT. By contrast, those AD subjects with higher baseline cytokine levels in plasma showed treatment-induced decreases in plasma cytokines at both time points. Thus, a gravitation to reported normal plasma cytokine levels (i.e., a “rebalancing”) occurred with both acute and long-term TEMT. In the CSF, TEMT-induced a similar rebalancing for seven measurable cytokines, the direction and extent of changes in individual subjects also being linked to their baseline CSF levels.

Conclusion

Our results strongly suggest that daily TEMT to AD subjects for 2-months can “rebalance” levels for 11 of 12 cytokines in blood and/or brain, which is associated with reversal of their cognitive impairment. TEMT is likely to be providing these immunoregulatory effects by affecting cytokine secretion from: (1) blood cells traveling through the head’s vasculature, and (2) the brain’s microglia/astrocytes, choroid plexus, or neurons. This rebalancing of so many cytokines, and in both brain and systemic compartments, appears to be a remarkable new mechanism of TEMT action that may contribute substantially to it’s potential to prevent, stop, or reverse AD and other diseases of aging.

Combined Effect of Co-administration of Stromal Cell-Derived Factor-1 and Granulocyte-Colony Stimulating Factor on Rat Model of Alzheimer’s Disease

Introduction

Alzheimer’s disease (AD) is a neurodegenerative disease that is characterized by amyloid plaque deposits, neuronal cell loss, and memory impairment. Granulocyte-colony stimulating factor (G-CSF) is a growth factor associated with AD improvement. Stromal cell-derived factor-1 (SDF-1) mediates therapeutic effects of G-CSF. This study investigated the effect of combination treatment of G-CSF and SDF-1 on amyloid plaque deposits, apoptosis, and behavior of AD rats.

Methods

Intracerebroventricular amyloid-beta [Aβ(1-42)] peptide was used to induce AD in Aβ rats. There were six groups including naive control, sham-operated, Aβ, Aβ + G-CSF, Aβ + SDF-1, and Aβ + G-CSF + SDF-1. SDF-1 intra-cerebroventricular (ICV), G-CSF Subcutaneous (SC), or a combination of them were administered to Aβ rats weekly for 2 months. The cognition and memory were assessed using the novel object recognition, passive avoidance, and Morris water maze tests. Next, rat brains were removed and the amyloid plaque and apoptosis were detected in the brain and hippocampus using immunohistochemistry and TUNEL assay, respectively.

Results

The amyloid-beta and apoptotic cell levels dropped in groups receiving SDF-1 and G-CSF combination compared to the Aβ group. Also, number of microglial cells increased significantly in the combination group compared to other treatment groups. Moreover, learning and memory were significantly improved in the combination group compared to the Aβ groups (P < 0.05).

Conclusion

SDF-1 and G-CSF combination therapy can offer a promising strategy for AD.

Advances in stem cell therapy in Alzheimer's disease: a comprehensive clinical trial review

Alzheimer's disease (AD) is the most common type of dementia responsible for more than 121,499 deaths from AD in 2019 making AD the sixth-leading cause in the United States. AD is a progressive neurodegenerative disorder characterized by decline of memory, behavioral impairments that affects a person's ability to function independently ultimately leading to death. The current pressing need for a treatment for (AD) and advances in the field of cell therapy, has rendered stem cell therapeutics a promising field of research. Despite advancements in stem cell technology, confirmed by encouraging pre-clinical utilization of stem cells in AD animal models, the number of clinical trials evaluating the efficacy of stem cell therapy is limited, with the results of many ongoing clinical trials on cell therapy for AD still pending. Mesenchymal stem cells (MSCs) have been the main focus in these studies, reporting encouraging results concerning safety profile, however their efficacy remains unproven. In the current article we review the latest advances regarding different sources of stem cell therapy and present a comprehensive list of every available clinical trial in national and international registries. Finally, we discuss drawbacks arising from AD pathology and technical limitations that hinder the transition of stem cell technology from bench to bedside. Our findings emphasize the need to increase clinical trials towards uncovering the mode of action and the underlying therapeutic mechanisms of transplanted cells as well as the molecular mechanisms controlling regeneration and neuronal microenvironment.

Colony stimulating factors in the nervous system

Although traditionally seen as regulators of hematopoiesis, colony-stimulating factors (CSFs) have emerged as important players in the nervous system, both in health and disease. This review summarizes the cellular sources, patterns of expression and physiological roles of the macrophage (CSF-1, IL-34), granulocyte-macrophage (GM-CSF) and granulocyte (G-CSF) colony stimulating factors within the nervous system, with a particular focus on their actions on microglia. CSF-1 and IL-34, via the CSF-1R, are required for the development, proliferation and maintenance of essentially all CNS microglia in a temporal and regional specific manner. In contrast, in steady state, GM-CSF and G-CSF are mainly involved in regulation of microglial function. The alterations in expression of these growth factors and their receptors, that have been reported in several neurological diseases, are described and the outcomes of their therapeutic targeting in mouse models and humans are discussed.

Alzheimer's disease clinical trial update 2019-2021

The current clinical trial landscape targeting Alzheimer's disease (AD) is reviewed in the context of studies completed from 2019 to 2021. This review focuses on available data for observational and phase II/III clinical trial results, which will have the most impact on the field. ClinicalTrials.gov, the United States (US) comprehensive federal registry, was queried to identify completed trials. There are currently 226 interventional clinical trials and 51 observational studies completed, suspended, terminated, or withdrawn within our selected time frame. This review reveals that the role of biomarkers is expanding and although many lessons have been learned, many challenges remain when targeting disease modification of AD through amyloid and tau. In addition, to halt or slow clinical progression of AD, new clinical and observational trials are focusing on prevention as well as the role of more diverse biological processes known to influence AD pathology.

Effect of Regular Physical Exercise on Gut Microbiota and Depressive Behaviors in Rats

Objective. The gut microbiota, as the critical mediator of the gut-brain axis, can produce and transport neuroactive substances, thus playing a significant role in the pathogenesis of depression. Although regular physical exercise is an important nondrug antidepressant, its specific effector mechanism is still unclear. Methods. Rats were randomly divided into four different groups (n = 10 for each group) as follows: normal group (G1), depression group (G2), fluoxetine treatment group (G3), and regular exercise treatment group (G4). All rats underwent forced swimming tests, tail suspension tests, open field tests, and elevated plus-maze tests to detect behavioristics. Then, corticosterone levels were detected by ELISA. Additionally, taxonomic analysis of the gut microbiota in all rats was performed after they were exercised regularly for 60 days. Results. Compared with the G1 group, the rats in the G2 group showed significant depression-like behaviors, with increased serum corticosterone levels. The proportions of Bacteroides, Actinomycetes, Proteobacteria, Saccharomyces, and Cyanobacteria in rats of the G2 group were lower than those in the G1 group, while the proportions of Firmicutes, Tenicotte, Deferrobacteria, and Fusobacteria were increased. Furthermore, after regular exercise treatment, the gut microbiota of rats was effectively improved, almost returning to the level of the G1 group, and depressive behavior and corticosterone levels were also restored, which was almost the same as the effect of fluoxetine treatment. Conclusion. Regular physical exercise could alleviate depressive-like behaviors by modulating the species and function of the gut microbiota.

G-CSF secreted by mutant IDH1 glioma stem cells abolishes myeloid cell immunosuppression and enhances the efficacy of immunotherapy

Mutant isocitrate-dehydrogenase 1 (mIDH1) synthesizes the oncometabolite 2-hydroxyglutarate (2HG), which elicits epigenetic reprogramming of the glioma cells’ transcriptome by inhibiting DNA and histone demethylases. We show that the efficacy of immune-stimulatory gene therapy (TK/Flt3L) is enhanced in mIDH1 gliomas, due to the reprogramming of the myeloid cells’ compartment infiltrating the tumor microenvironment (TME). We uncovered that the immature myeloid cells infiltrating the mIDH1 TME are mainly nonsuppressive neutrophils and preneutrophils. Myeloid cell reprogramming was triggered by granulocyte colony-stimulating factor (G-CSF) secreted by mIDH1 glioma stem/progenitor-like cells. Blocking G-CSF in mIDH1 glioma–bearing mice restores the inhibitory potential of the tumor-infiltrating myeloid cells, accelerating tumor progression. We demonstrate that G-CSF reprograms bone marrow granulopoiesis, resulting in noninhibitory myeloid cells within mIDH1 glioma TME and enhancing the efficacy of immune-stimulatory gene therapy.

Systemic inflammatory regulators and risk of Alzheimer's disease: a bidirectional Mendelian-randomization study

BACKGROUND

Systemic inflammation has been suggested to be associated with Alzheimer's-disease progression, although whether it is a cause or a downstream effect is still controversial. This study aims to assess the effect of systemic inflammatory regulators on Alzheimer's disease within a bidirectional Mendelian-randomization design.

METHODS

Genetic associations with Alzheimer's disease were obtained from the largest and most up-to-date genome-wide association study (GWAS) (cases and proxy cases: 71 880; controls: 383 378) and with inflammatory regulators from two recent GWASs on the human proteome and cytokines. Estimates were obtained by inverse-variance weighting with sensitivity analyses using MR-Egger, weighted median and MR-PRESSO. Possible bias due to selective survival and competing risk was also considered.

RESULTS

None of 41 systemic inflammatory regulators was associated with risk of Alzheimer's disease with consistent results in validation analysis. Conversely, Alzheimer's disease was suggestively associated with five systemic inflammatory regulators, i.e. basic fibroblast growth factor, granulocyte-colony-stimulating factor, interferon gamma, interleukin-13 and interleukin-7.

CONCLUSION

The systemic inflammatory regulators considered did not appear to be associated with the risk of Alzheimer's disease. Conversely, specific systemic inflammatory regulators may be downstream effects of Alzheimer's disease or consequences of common factors causing both inflammation and Alzheimer's disease.

Immunotherapies for Neurodegenerative Diseases

The current treatments for neurodegenerative diseases are mostly symptomatic without affecting the underlying cause of disease. Emerging evidence supports a potential role for immunotherapy in the management of disease progression. Numerous reports raise the exciting prospect that either the immune system or its derivative components could be harnessed to fight the misfolded and aggregated proteins that accumulate in several neurodegenerative diseases. Passive and active vaccinations using monoclonal antibodies and specific antigens that induce adaptive immune responses are currently under evaluation for their potential use in the development of immunotherapies. In this review, we aim to shed light on prominent immunotherapeutic strategies being developed to fight neuroinflammation-induced neurodegeneration, with a focus on innovative immunotherapies such as vaccination therapy.

Stem cell in neurodegenerative disorders; an emerging strategy

Neurodegenerative disorders are a diversity of disorders, surrounding Alzheimer's (AD), Parkinson's (PD), Huntington's diseases (HD), and amyotrophic lateral sclerosis (ALS) accompanied by some other less common diseases generally characterized by either developed deterioration of central or peripheral nervous system structurally or functionally. Today, with the viewpoint of an increasingly aging society, the number of patients with neurodegenerative diseases and sociomedical burdens will spread intensely. During the last decade, stem cell technology has attracted great attention for treating neurodegenerative diseases worldwide because of its unique attributes. As acknowledged, there are several categories of stem cells being able to proliferate and differentiate into various cellular lineages, highlighting their significance in the context of regenerative medicine. In preclinical models, stem cell therapy using mesenchymal stem/stromal cells (MSCs), hematopoietic stem cells (HSCs), and neural progenitor or stem cells (NPCs or NSCs) along with pluripotent stem cells (PSCs)-derived neuronal cells could elicit desired therapeutic effects, enabling functional deficit rescue partially. Regardless of the noteworthy progress in our scientific awareness and understanding of stem cell biology, there still exist various challenges to defeat. In the present review, we provide a summary of the therapeutic potential of stem cells and discuss the current status and prospect of stem cell strategy in neurodegenerative diseases, in particular, AD, PD, ALS, and HD.

Different changes in granulocyte-colony stimulating factor and its correlation with inflammatory biomarkers in patients after traumatic brain injury

OBJECTIVE

This study analyzed changes in granulocyte-colony stimulating factor (G-CSF) and its correlation with leukocyte and neutrophil counts in patients after traumatic brain injury (TBI).

METHODS

Sixty TBI patients were included retrospectively. The serum levels of G-CSF, tumor necrosis factor-α (TNF-α), and peripheral leukocyte and neutrophil counts at different time points were measured and analyzed, and the 6-month functional outcomes were monitored.

RESULTS

The levels of G-CSF in mild and moderate TBI groups were higher than the control at the first three time points. G-CSF in the severe TBI group increased slowly and peaked at day 7, and was only significantly different from the control at day 7 and 14. The leukocyte and neutrophil counts of the mild group gradually decreased, but a second increase after day 4 was observed in the severe group. The cell counts were higher in the severe group compared to other groups. A positive correlation between G-CSF and leukocyte and neutrophil counts was observed in the severe group at day 1. G-CSF positively correlated with TNF-α in the severe group at day 4 and 7. In severe patients with a good outcome, G-CSF level at day 7 was significantly higher than those with a poor outcome.

CONCLUSION

The G-CSF levels in the severe TBI group exhibited a different pattern from those in the mild and moderate TBI groups, and these levels positively correlated with inflammatory biomarkers. Higher G-CSF levels in severe TBI at day 7 indicated a good outcome at 6 months.

Neuroprotection through G-CSF: recent advances and future viewpoints

Granulocyte-colony stimulating factor (G-CSF), a member of the cytokine family of hematopoietic growth factors, is 19.6 kDa glycoprotein which is responsible for the proliferation, maturation, differentiation, and survival of neutrophilic granulocyte lineage. Apart from its proven clinical application to treat chemotherapy-associated neutropenia, recent pre-clinical studies have highlighted the neuroprotective roles of G-CSF i.e., mobilization of haemopoietic stem cells, anti-apoptotic, neuronal differentiation, angiogenesis and anti-inflammatory in animal models of neurological disorders. G-CSF is expressed by numerous cell types including neuronal, immune and endothelial cells. G-CSF is released in autocrine manner and binds to its receptor G-CSF-R which further activates numerous signaling transduction pathways including PI3K/AKT, JAK/STAT and MAP kinase, and thereby promote neuronal survival, proliferation, differentiation, mobilization of hematopoietic stem and progenitor cells. The expression of G-CSF receptors (G-CSF-R) in the different brain regions and their upregulation in response to neuronal insult indicates the autocrine protective signaling mechanism of G-CSF by inhibition of apoptosis, inflammation, and stimulation of neurogenesis. These observed neuroprotective effects of G-CSF makes it an attractive target to mitigate neurodegeneration associated with neurological disorders. The objective of the review is to highlight and summarize recent updates on G-CSF as a therapeutically versatile neuroprotective agent along with mechanisms of action as well as possible clinical applications in neurodegenerative disorders including AD, PD and HD.

Reparative Effects of Stem Cell Factor and Granulocyte Colony-Stimulating Factor in Aged APP/PS1 Mice

Alzheimer's disease (AD), characterized by the accumulation of β-amyloid (Aβ) plaques and tau neurofibrillary tangles in the brain, neuroinflammation and neurodegeneration, is the most common form of neurodegenerative disease among the elderly. No effective treatment is available now in restricting the pathological progression of AD. The aim of this study is to determine the therapeutic efficacy of stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF) (SCF+G-CSF) in aged APPswe/PS1dE9 (APP/PS1) mice. SCF+G-CSF was subcutaneously injected for 12 days to 25-month-old male APP/PS1 mice. We observed that SCF+G-CSF treatment reduced the Aβ plaques in both the cortex and hippocampus. SCF+G-CSF treatment increased the association of TREM2+/Iba1+ cells with Aβ plaques and enhanced Aβ uptake by Iba1+ and CD68+cells in the brains of aged APP/PS1 mice. Importantly, cerebral expression area of P2RY12+and TMEM119+ homeostatic microglia and the branches of P2RY12+ homeostatic microglia were increased in the SCF+G-CSF-treated aged APP/PS1 mice. SCF+G-CSF treatment also decreased NOS-2 and increased IL-4 in the brains of aged APP/PS1 mice. Moreover, the loss of MAP2+dendrites and PSD-95+post-synapses and the accumulation of aggregated tau in the brains of aged APP/PS1 mice were ameliorated by SCF+G-CSF treatment. Furthermore, the density of P2RY12+ microglia was negatively correlated with Aβ deposits, but positively correlated with the densities of MAP2+ dendrites and PSD-95+ puncta in the brains of aged APP/PS1 mice. These findings reveal the therapeutic potential of SCF+G-CSF treatment in ameliorating AD pathology at the late stage.

Pan-SHIP1/2 inhibitors promote microglia effector functions essential for CNS homeostasis

We show here that both SHIP1 (Inpp5d) and its paralog SHIP2 (Inppl1) are expressed at protein level in microglia. To examine whether targeting of SHIP paralogs might influence microglial physiology and function, we tested the capacity of SHIP1-selective, SHIP2-selective and pan-SHIP1/2 inhibitors for their ability to impact on microglia proliferation, lysosomal compartment size and phagocytic function. We find that highly potent pan-SHIP1/2 inhibitors can significantly increase lysosomal compartment size, and phagocytosis of dead neurons and amyloid beta (Aβ)1-42 by microglia in vitro We show that one of the more-potent and water-soluble pan-SHIP1/2 inhibitors, K161, can penetrate the blood-brain barrier. Consistent with this, K161 increases the capacity of CNS-resident microglia to phagocytose Aβ and apoptotic neurons following systemic administration. These findings provide the first demonstration that small molecule modulation of microglia function in vivo is feasible, and suggest that dual inhibition of the SHIP1 and 2 paralogs can provide a novel means to enhance basal microglial homeostatic functions for therapeutic purposes in Alzheimer's disease and, possibly, other types of dementia where increased microglial function could be beneficial.

LW-AFC, a new formula from the traditional Chinese medicine Liuwei Dihuang decoction, as a promising therapy for Alzheimer's disease: Pharmacological effects and mechanisms

LW-AFC is a new formula derived from the Liuwei Dihuang decoction, a classical traditional Chinese medicine prescription. Based on our research, LW-AFC is a promising drug for Alzheimer's disease (AD). The studies were conducted primarily in two typical AD mouse models: SAMP8 and APP/PS1 mice. The results showed that LW-AFC could improve many cognitive behaviors, such as spatial learning and memory ability, passive and active avoidance response, and object recognition memory capability. In addition, LW-AFC could also alleviate the AD-like pathology in animal models, such as neuron loss and Aβ deposition. Subsequent studies found that LW-AFC could rebalance hypothalamic-pituitary-adrenal (HPA) axis and hypothalamic-pituitary-gonadal (HPG) axis, and modulate the disturbance of immune system and gut flora. These data suggested that the anti-AD effects of LW-AFC might be mainly via modulating the neuroendocrine immunomodulation (NIM) network. As inhibiting the immune function by immunosuppressant could abolish the protective effects of LW-AFC against long-term potentiation (LTP) impairment model, it is likely that LW-AFC balancing the NIM network is initiated by modulating the immune system.

Successes and Hurdles in Stem Cells Application and Production for Brain Transplantation

Brain regenerative strategies through the transplantation of stem cells hold the potential to promote functional rescue of brain lesions caused either by trauma or neurodegenerative diseases. Most of the positive modulations fostered by stem cells are fueled by bystander effects, namely increase of neurotrophic factors levels and reduction of neuroinflammation. Nevertheless, the ultimate goal of cell therapies is to promote cell replacement. Therefore, the ability of stem cells to migrate and differentiate into neurons that later become integrated into the host neuronal network replacing the lost neurons has also been largely explored. However, as most of the preclinical studies demonstrate, there is a small functional integration of graft-derived neurons into host neuronal circuits. Thus, it is mandatory to better study the whole brain cell therapy approach in order to understand what should be better comprehended concerning graft-derived neuronal and glial cells migration and integration before we can expect these therapies to be ready as a viable solution for brain disorder treatment. Therefore, this review discusses the positive mechanisms triggered by cell transplantation into the brain, the limitations of adult brain plasticity that might interfere with the neuroregeneration process, as well as some strategies tested to overcome some of these limitations. It also considers the efforts that have been made by the regulatory authorities to lead to better standardization of preclinical and clinical studies in this field in order to reduce the heterogeneity of the obtained results.

Method for Stimulation of Hippocampal Neurogenesis by Transient Microneedle Insertion

Brief stereotaxic insertion and removal of a microneedle into the hippocampus of mice result in stimulation of hippocampal neurogenesis. This approach has been previously applied to a mouse model of Alzheimer's disease (Song et al., Cell Transplant 25:1853-1861, 2016). Further studies of fundamental cellular mechanisms of the brain's response to micro-injury will be useful for investigation of potential neuroprotective and deleterious effects of targeted microlesions and deep brain stimulation in neurodegenerative diseases.

Granulocyte Colony Stimulating Factor Enhances Reward Learning through Potentiation of Mesolimbic Dopamine System Function

Deficits in motivation and cognition are hallmark symptoms of multiple psychiatric diseases. These symptoms are disruptive to quality of life and often do not improve with available medications. In recent years there has been increased interest in the role of the immune system in neuropsychiatric illness, but to date no immune-related treatment strategies have come to fruition. The cytokine granulocyte-colony stimulating factor (G-CSF) is known to have trophic and neuroprotective properties in the brain, and we recently identified it as a modulator of neuronal and behavioral plasticity. By combining operant tasks that assess discrete aspects of motivated behavior and decision-making in male mice and rats with subsecond dopamine monitoring via fast-scan cyclic voltammetry, we defined the role of G-CSF in these processes as well as the neural mechanism by which it modulates dopamine function to exert these effects. G-CSF enhanced motivation for sucrose as well as cognitive flexibility as measured by reversal learning. These behavioral outcomes were driven by mesolimbic dopamine system plasticity, as systemically administered G-CSF increased evoked dopamine release in the nucleus accumbens independent of clearance mechanisms. Importantly, sustained increases in G-CSF were required for these effects as acute exposure did not enhance behavioral outcomes and decreased dopamine release. These effects seem to be a result of the ability of G-CSF to alter local inflammatory signaling cascades, particularly tumor necrosis factor α. Together, these data show G-CSF as a potent modulator of the mesolimbic dopamine circuit and its ability to appropriately attend to salient stimuli.SIGNIFICANCE STATEMENT Emerging evidence has highlighted the importance of the immune system in psychiatric diseases states. However, the effects of peripheral cytokines on motivation and cognitive function are largely unknown. Here, we report that granulocyte-colony stimulating factor (G-CSF), a pleiotropic cytokine with known trophic and neuroprotective properties in the brain, acts directly on dopaminergic circuits to enhance their function. These changes in dopaminergic dynamics enhance reward learning and motivation for natural stimuli. Together, these results suggest that targeting immune factors may provide a new avenue for therapeutic intervention in the multiple psychiatric disorders that are characterized by motivational and cognitive deficits.

Combination of drug and stem cells neurotherapy: Potential interventions in neurotrauma and traumatic brain injury

Traumatic brain injury (TBI) has been recognized as one of the major public health issues that leads to devastating neurological disability. As a consequence of primary and secondary injury phases, neuronal loss following brain trauma leads to pathophysiological alterations on the molecular and cellular levels that severely impact the neuropsycho-behavioral and motor outcomes. Thus, to mitigate the neuropathological sequelae post-TBI such as cerebral edema, inflammation and neural degeneration, several neurotherapeutic options have been investigated including drug intervention, stem cell use and combinational therapies. These treatments aim to ameliorate cellular degeneration, motor decline, cognitive and behavioral deficits. Recently, the use of neural stem cells (NSCs) coupled with selective drug therapy has emerged as an alternative treatment option for neural regeneration and behavioral rehabilitation post-neural injury. Given their neuroprotective abilities, NSC-based neurotherapy has been widely investigated and well-reported in numerous disease models, notably in trauma studies. In this review, we will elaborate on current updates in cell replacement therapy in the area of neurotrauma. In addition, we will discuss novel combination drug therapy treatments that have been investigated in conjunction with stem cells to overcome the limitations associated with stem cell transplantation. Understanding the regenerative capacities of stem cell and drug combination therapy will help improve functional recovery and brain repair post-TBI. This article is part of the Special Issue entitled "Novel Treatments for Traumatic Brain Injury".

Neuroprotective Effects of Filgrastim in Rotenone-Induced Parkinson's Disease in Rats: Insights into its Anti-Inflammatory, Neurotrophic, and Antiapoptotic Effects

All current treatments of Parkinson's disease (PD) focus on enhancing the dopaminergic effects and providing symptomatic relief; however, they cannot delay the disease progression. Filgrastim, a recombinant methionyl granulocyte colony-stimulating factor, demonstrated neuroprotection in many neurodegenerative and neurological diseases. This study aimed to assess the neuroprotective effects of filgrastim in rotenone-induced rat model of PD and investigate the potential underlying mechanisms of filgrastim actions. The effects of two doses of filgrastim (20 and 40 μg/kg) on spontaneous locomotion, catalepsy, body weight, histology, and striatal dopamine (DA) content, as well as tyrosine hydroxylase (TH) and α-synuclein expression, were evaluated. Then, the effective dose was further tested for its potential anti-inflammatory, neurotrophic, and antiapoptotic effects. Filgrastim (40 μg/kg) prevented rotenone-induced motor deficits, weight reduction, striatal DA depletion, and histological damage. Besides, it significantly inhibited rotenone-induced decrease in TH expression and increase in α-synuclein immunoreactivity in the midbrains and striata of the rats. These effects were associated with reduction of rotenone-induced neuroinflammation, apoptosis, and brain-derived neurotrophic factor depletion. Collectively, these results suggest that filgrastim might be a good candidate for management of PD.

The Gut Microbiome Alterations and Inflammation-Driven Pathogenesis of Alzheimer's Disease-a Critical Review

One of the most important scientific discoveries of recent years was the disclosure that the intestinal microflora takes part in bidirectional communication between the gut and the brain. Scientists suggest that human gut microflora may even act as the “second brain” and be responsible for neurodegenerative disorders like Alzheimer’s disease (AD). Although human-associated microbial communities are generally stable, they can be altered by common human actions and experiences. Enteric bacteria, commensal, and pathogenic microorganisms, may have a major impact on immune system, brain development, and behavior, as they are able to produce several neurotransmitters and neuromodulators like serotonin, kynurenine, catecholamine, etc., as well as amyloids. However, brain destructive mechanisms, that can lead to dementia and AD, start with the intestinal microbiome dysbiosis, development of local and systemic inflammation, and dysregulation of the gut-brain axis. Increased permeability of the gut epithelial barrier results in invasion of different bacteria, viruses, and their neuroactive products that support neuroinflammatory reactions in the brain. It seems that, inflammatory-infectious hypothesis of AD, with the great role of the gut microbiome, starts to gently push into the shadow the amyloid cascade hypothesis that has dominated for decades. It is strongly postulated that AD may begin in the gut, and is closely related to the imbalance of gut microbiota. This is promising area for therapeutic intervention. Modulation of gut microbiota through personalized diet or beneficial microbiota intervention, alter microbial partners and their products including amyloid protein, will probably become a new treatment for AD.

Granulocyte-macrophage colony-stimulating factor neuroprotective activities in Alzheimer's disease mice

We investigated the effects of granulocyte-macrophage colony stimulating factor (GM-CSF) on behavioral and pathological outcomes in Alzheimer's disease (AD) and non-transgenic mice. GM-CSF treatment in AD mice reduced brain amyloidosis, increased plasma Aβ, and rescued cognitive impairment with increased hippocampal expression of calbindin and synaptophysin and increased levels of doublecortin-positive cells in the dentate gyrus. These data extend GM-CSF pleiotropic neuroprotection mechanisms in AD and include regulatory T cell-mediated immunomodulation of microglial function, Aβ clearance, maintenance of synaptic integrity, and induction of neurogenesis. Together these data support further development of GM-CSF as a neuroprotective agent for AD.

Granulocyte-colony stimulating factor controls neural and behavioral plasticity in response to cocaine

Cocaine addiction is characterized by dysfunction in reward-related brain circuits, leading to maladaptive motivation to seek and take the drug. There are currently no clinically available pharmacotherapies to treat cocaine addiction. Through a broad screen of innate immune mediators, we identify granulocyte-colony stimulating factor (G-CSF) as a potent mediator of cocaine-induced adaptations. Here we report that G-CSF potentiates cocaine-induced increases in neural activity in the nucleus accumbens (NAc) and prefrontal cortex. In addition, G-CSF injections potentiate cocaine place preference and enhance motivation to self-administer cocaine, while not affecting responses to natural rewards. Infusion of G-CSF neutralizing antibody into NAc blocks the ability of G-CSF to modulate cocaine's behavioral effects, providing a direct link between central G-CSF action in NAc and cocaine reward. These results demonstrate that manipulating G-CSF is sufficient to alter the motivation for cocaine, but not natural rewards, providing a pharmacotherapeutic avenue to manipulate addictive behaviors without abuse potential.

Differential regulation of NSC phenotype and genotype by chronically activated microglia within cocultures

Under disease or injury conditions in the central nervous system (CNS), activated microglia release cytokines and chemokines to modulate the microenvironment and influence tissue remodeling. To exploit the full potential of neural stem cell (NSC) transplantation approaches, a permissive microenvironment needs to be created for their survival, homing and differentiation. To investigate the role of chronically activated microglia in the fate of NSCs, spontaneously immortalized murine microglial cells (SIM-A9) were cocultured with embryonic murine cortical NSCs on 2D substrates or within 3D gels. Standalone NSC cultures served as controls. Cytokines and chemokines released by NSCs and SIM-A9 cells in standalone and cocultures were quantified. Coculturing with SIM-A9 cells suppressed NSC viability, neurite outgrowth, neural differentiation and TUJ1 gene expression, and promoted glia formation in both 2D and 3D cultures, over a 10-day period. The seven most-abundantly released analytes by microglia (MCP-1, MIP2, G-CSF, MIP-1α, MIP-1β, TNF-α, IL-6) were tested for their individual effects on NSCs, to investigate if the outcomes in cocultures were due to the synergistic effects of analytes or the influence of any individual analyte. All the seven analytes significantly suppressed cell survival compared to controls, but exposure to MIP-1β, IL-6, or MCP-1 enhanced neurite outgrowth and neural lineage commitment. Results attest to (i) the strong role of activated microglia in regulating NSC fate, (ii) the utility of selective analytes released by activated microglia in promoting neurogenesis and neuritogenesis, and (iii) the need to protect transplanted NSCs from the host inflammatory microenvironment to ensure their survival and functionality in treating neurological disorders.

Granulocyte-colony stimulating factor and umbilical cord blood cell transplantation: Synergistic therapies for the treatment of traumatic brain injury

Traumatic brain injury (TBI) is now characterized as a progressive, degenerative disease and continues to stand as a prevalent cause of death and disability. The pathophysiology of TBI is complex, with a variety of secondary cell death pathways occurring which may persist chronically following the initial cerebral insult. Current therapeutic options for TBI are minimal, with surgical intervention or rehabilitation therapy existing as the only viable treatments. Considering the success of stem-cell therapies in various other neurological diseases, their use has been proposed as a potential potent therapy for patients suffering TBI. Moreover, stem cells are highly amenable to adjunctive use with other therapies, providing an opportunity to overcome the inherent limitations of using a single therapeutic agent. Our research has verified this additive potential by demonstrating the efficacy of co-delivering human umbilical cord blood (hUCB) cells with granulocyte-colony stimulating factor (G-CSF) in a murine model of TBI, providing encouraging results which support the potential of this approach to treat patients suffering from TBI. These findings justify ongoing research toward uncovering the mechanisms which underlie the functional improvements exhibited by hUCB + G-CSF combination therapy, thereby facilitating its safe and effect transition into the clinic. This paper is a review article. Referred literature in this paper has been listed in the reference section. The datasets supporting the conclusions of this article are available online by searching various databases, including PubMed. Some original points in this article come from the laboratory practice in our research center and the authors’ experiences.

Toxoplasma Modulates Signature Pathways of Human Epilepsy, Neurodegeneration & Cancer

One third of humans are infected lifelong with the brain-dwelling, protozoan parasite, Toxoplasma gondii. Approximately fifteen million of these have congenital toxoplasmosis. Although neurobehavioral disease is associated with seropositivity, causality is unproven. To better understand what this parasite does to human brains, we performed a comprehensive systems analysis of the infected brain: We identified susceptibility genes for congenital toxoplasmosis in our cohort of infected humans and found these genes are expressed in human brain. Transcriptomic and quantitative proteomic analyses of infected human, primary, neuronal stem and monocytic cells revealed effects on neurodevelopment and plasticity in neural, immune, and endocrine networks. These findings were supported by identification of protein and miRNA biomarkers in sera of ill children reflecting brain damage and T. gondii infection. These data were deconvoluted using three systems biology approaches: "Orbital-deconvolution" elucidated upstream, regulatory pathways interconnecting human susceptibility genes, biomarkers, proteomes, and transcriptomes. "Cluster-deconvolution" revealed visual protein-protein interaction clusters involved in processes affecting brain functions and circuitry, including lipid metabolism, leukocyte migration and olfaction. Finally, "disease-deconvolution" identified associations between the parasite-brain interactions and epilepsy, movement disorders, Alzheimer's disease, and cancer. This "reconstruction-deconvolution" logic provides templates of progenitor cells' potentiating effects, and components affecting human brain parasitism and diseases.

Effects of an Inhibitor of Monocyte Recruitment on Recovery from Traumatic Brain Injury in Mice Treated with Granulocyte Colony-Stimulating Factor

Administration of the hematopoietic growth factor granulocyte-colony stimulating Factor (G-CSF) has been reported to enhance recovery from controlled cortical impact (CCI) in rodent models. G-CSF exerts actions in both the periphery (stimulation of hematopoiesis) and in the brain, where it serves as a neurotrophic factor, promoting neuronal survival and stimulating neural stem/progenitor cell proliferation in the hippocampus. In order to distinguish the direct CNS actions of G-CSF from its peripheral actions, experiments were designed to block the recruitment of peripheral monocytes to the site of the lesion produced by CCI. The selective C-C motif receptor 2 (CCR2) antagonist (RS504303) was co-administered with G-CSF for three days after CCI in a chimeric mouse previously transplanted with GFP-expressing (GFP+) blood stem-progenitor cells. Results: The drug significantly impaired infiltration of GFP+ bone marrow-derived cells to the frontal cortex and striatum without impeding recovery performance and hippocampal neurogenesis in the behavioral test, the Radial Arm Water Maze (RAWM). Administration of the CCR2 antagonist alone, without G-CSF, was effective in promoting recovery in RAWM. These results support the hypothesis that the direct action of G-CSF on neural cells, independent of its hematopoietic effects, is primarily responsible for enhanced recovery from CCI. In addition, this study confirms the importance of CCR2 and its ligand, monocyte chemotactic protein-1 (MCP-1), in mediating the inflammatory response following CCI.

Microbiota modulation counteracts Alzheimer's disease progression influencing neuronal proteolysis and gut hormones plasma levels

Gut microbiota has a proven role in regulating multiple neuro-chemical pathways through the highly interconnected gut-brain axis. Oral bacteriotherapy thus has potential in the treatment of central nervous system-related pathologies, such as Alzheimer’s disease (AD). Current AD treatments aim to prevent onset, delay progression and ameliorate symptoms. In this work, 3xTg-AD mice in the early stage of AD were treated with SLAB51 probiotic formulation, thereby affecting the composition of gut microbiota and its metabolites. This influenced plasma concentration of inflammatory cytokines and key metabolic hormones considered therapeutic targets in neurodegeneration. Treated mice showed partial restoration of two impaired neuronal proteolytic pathways (the ubiquitin proteasome system and autophagy). Their cognitive decline was decreased compared with controls, due to a reduction in brain damage and reduced accumulation of amyloid beta aggregates. Collectively, our results clearly prove that modulation of the microbiota induces positive effects on neuronal pathways that are able to slow down the progression of Alzheimer’s disease.

Brain Perivascular Macrophages Initiate the Neurovascular Dysfunction of Alzheimer Aβ Peptides

RATIONALE

Increasing evidence indicates that alterations of the cerebral microcirculation may play a role in Alzheimer disease, the leading cause of late-life dementia. The amyloid-β peptide (Aβ), a key pathogenic factor in Alzheimer disease, induces profound alterations in neurovascular regulation through the innate immunity receptor CD36 (cluster of differentiation 36), which, in turn, activates a Nox2-containing NADPH oxidase, leading to cerebrovascular oxidative stress. Brain perivascular macrophages (PVM) located in the perivascular space, a major site of brain Aβ collection and clearance, are juxtaposed to the wall of intracerebral resistance vessels and are a powerful source of reactive oxygen species.

OBJECTIVE

We tested the hypothesis that PVM are the main source of reactive oxygen species responsible for the cerebrovascular actions of Aβ and that CD36 and Nox2 in PVM are the molecular substrates of the effect.

METHODS AND RESULTS

Selective depletion of PVM using intracerebroventricular injection of clodronate abrogates the reactive oxygen species production and cerebrovascular dysfunction induced by Aβ applied directly to the cerebral cortex, administered intravascularly, or overproduced in the brain of transgenic mice expressing mutated forms of the amyloid precursor protein (Tg2576 mice). In addition, using bone marrow chimeras, we demonstrate that PVM are the cells expressing CD36 and Nox2 responsible for the dysfunction. Thus, deletion of CD36 or Nox2 from PVM abrogates the deleterious vascular effects of Aβ, whereas wild-type PVM reconstitute the vascular dysfunction in CD36-null mice.

CONCLUSIONS

The data identify PVM as a previously unrecognized effector of the damaging neurovascular actions of Aβ and unveil a new mechanism by which brain-resident innate immune cells and their receptors may contribute to the pathobiology of Alzheimer disease.

G-CSF administration attenuates brain injury in rats following carbon monoxide poisoning via different mechanisms

Acute severe carbon monoxide (CO) poisoning induces hypoxia that leads to cardiovascular and nervous systems disturbances. Different complex mechanisms lead to CO neurotoxicity including lipid peroxidation, inflammatory and immune-mediated reactions, myelin degeneration and finally neuronal apoptosis and necrosis. Granulocyte colony-stimulating factor (G-CSF) is considered to be a novel neuroprotective agent. In this study, we evaluated the efficacy of G-CSF therapy on CO neurotoxicity in rats with acute CO poisoning. Rats were exposed to 3000 ppm CO in air (0.3%) for 1 h, and then different doses (50,100, and 150 µg/kg) of G-CSF or normal saline were administrated intraperitoneally. Water content of brain as an indicator for total edema and blood brain barrier integrity (Evans blue extravasation) were evaluated. Malondialydehyde was determined in order to evaluate the effect of G-CSF on CO-induced lipid peroxidation in brain tissues. Also, the effect of G-CSF on myeloperoxidase activity in the brain tissue was evaluated. The effect of G-CSF administration on induced apoptosis in the brain was measured using TUNEL method. To evaluate the level of MBP, STAT3 and pSTAT3 and HO-1 proteins and the effect of G-CSF on these proteins Western blotting was carried out. G-CSF reduced water content of the edematous poisoned brains (100 µg/kg) and BBB permeability (100 and 150 µg/kg) (P < 0.05). G-CSF (150 µg/kg) reduced the MDA level in the brain tissues (P < 0.05 as compared to CO poisoned animals). G-CSF did not decrease the MPO activity after CO poisoning in any doses. G-CSF significantly reduced the number of apoptotic neurons and Caspase 3 protein levels in the brain. Western blotting results showed that G-CSF treatment enhanced expression of HO-1 and MBP, STAT3 and pSTAT3 proteins in the brain tissues. Based on our results, a single dose of G-CSF immediately after CO poisoning significantly attenuates CO neurotoxicity via different mechanisms. © 2015 Wiley Periodicals, Inc. Environ Toxicol 32: 37-47, 2017.

Young microglia restore amyloid plaque clearance of aged microglia

Alzheimer's disease (AD) is characterized by deposition of amyloid plaques, neurofibrillary tangles, and neuroinflammation. In order to study microglial contribution to amyloid plaque phagocytosis, we developed a novel ex vivo model by co-culturing organotypic brain slices from up to 20-month-old, amyloid-bearing AD mouse model (APPPS1) and young, neonatal wild-type (WT) mice. Surprisingly, co-culturing resulted in proliferation, recruitment, and clustering of old microglial cells around amyloid plaques and clearance of the plaque halo. Depletion of either old or young microglial cells prevented amyloid plaque clearance, indicating a synergistic effect of both populations. Exposing old microglial cells to conditioned media of young microglia or addition of granulocyte-macrophage colony-stimulating factor (GM-CSF) was sufficient to induce microglial proliferation and reduce amyloid plaque size. Our data suggest that microglial dysfunction in AD may be reversible and their phagocytic ability can be modulated to limit amyloid accumulation. This novel ex vivo model provides a valuable system for identification, screening, and testing of compounds aimed to therapeutically reinforce microglial phagocytosis.