CD200-CD200R imbalance correlates with microglia and pro-inflammatory activation in rat spinal cords exposed to amniotic fluid in retinoic acid-induced spina bifida

Characterizing neuroinflammation and identifying prenatal diagnostic markers for neural tube defects through integrated multi-omics analysis

BACKGROUND

Neural Tube Defects (NTDs) are congenital malformations of the central nervous system resulting from the incomplete closure of the neural tube during early embryonic development. Neuroinflammation refers to the inflammatory response in the nervous system, typically resulting from damage to neural tissue. Immune-related processes have been identified in NTDs, however, the detailed relationship and underlying mechanisms between neuroinflammation and NTDs remain largely unclear. In this study, we utilized integrated multi-omics analysis to explore the role of neuroinflammation in NTDs and identify potential prenatal diagnostic markers using a murine model.

METHODS

Nine public datasets from Gene Expression Omnibus (GEO) and ArrayExpress were mined using integrated multi-omics analysis to characterize the molecular landscape associated with neuroinflammation in NTDs. Special attention was given to the involvement of macrophages in neuroinflammation within amniotic fluid, as well as the dynamics of macrophage polarization and their interactions with neural cells at single-cell resolution. We also used qPCR assay to validate the key TFs and candidate prenatal diagnostic genes identified through the integrated analysis in a retinoic acid-induced NTDs mouse model.

RESULTS

Our analysis indicated that neuroinflammation is a critical pathological feature of NTDs, regulated both transcriptionally and epigenetically within central nervous system tissues. Key alterations in gene expression and pathways highlighted the crucial role of STATs molecules in the JAK-STAT signaling pathway in regulating NTDs-associated neuroinflammation. Furthermore, single-cell resolution analysis revealed significant polarization of macrophages and their interaction with neural cells in amniotic fluid, underscoring their central role in mediating neuroinflammation associated with NTDs. Finally, we identified a set of six potential prenatal diagnostic genes, including FABP7, CRMP1, SCG3, SLC16A10, RNASE6 and RNASE1, which were subsequently validated in a murine NTDs model, indicating their promise as prospective markers for prenatal diagnosis of NTDs.

CONCLUSIONS

Our study emphasizes the pivotal role of neuroinflammation in the progression of NTDs and underlines the potential of specific inflammatory and neural markers as novel prenatal diagnostic tools. These findings provide important clues for further understanding the underlying mechanisms between neuroinflammation and NTDs, and offer valuable insights for the future development of prenatal diagnostics.

Dysregulated CD200-CD200R signaling in early diabetes modulates microglia-mediated retinopathy

Diabetic retinopathy (DR) is a neurovascular complication of diabetes. Recent investigations have suggested that early degeneration of the neuroretina may occur prior to the appearance of microvascular changes; however, the mechanisms underlying this neurodegeneration have been elusive. Microglia are the predominant resident immune cell in the retina and adopt dynamic roles in disease. Here, we show that ablation of retinal microglia ameliorates visual dysfunction and neurodegeneration in a type I diabetes mouse model. We also provide evidence of enhanced microglial contact and engulfment of amacrine cells, ultrastructural modifications, and transcriptome changes that drive inflammation and phagocytosis. We show that CD200-CD200R signaling between amacrine cells and microglia is dysregulated during early DR and that targeting CD200R can attenuate high glucose-induced inflammation and phagocytosis in cultured microglia. Last, we demonstrate that targeting CD200R in vivo can prevent visual dysfunction, microglia activation, and retinal inflammation in the diabetic mouse. These studies provide a molecular framework for the pivotal role that microglia play in early DR pathogenesis and identify a potential immunotherapeutic target for treating DR in patients.

Toxic effects of exogenous retinoic acid on the neurodevelopment of zebrafish (Danio rerio) embryos

Endogenous retinoic acid (RA) is essential for embryonic development and maintaining adult physiological processes. Human-caused RA residues in the environment threaten the survival of organisms in the environment. We employed zebrafish as a model to explore the developmental impacts of excess RA. We used exogenous RA to raise the amount of RA signal in the embryos and looked at the effects of excess RA on embryonic morphological development. Upregulation of the RA signal significantly reduced embryo hatching and increased embryo malformation. To further understand the neurotoxic impact of RA signaling on early neurodevelopment, we measured the expression of neurodevelopmental marker genes and cell death and proliferation markers in zebrafish embryos. Exogenous RA disrupted stem cell (SC) and neuron marker gene expression and exacerbated apoptosis in the embryos. Furthermore, we looked into the links between the transcriptional coactivator RBM14 and RA signaling to better understand the mechanism of RA neurotoxicity. There was a negative interaction between RA signaling and the transcription coactivator RBM14, and the morpholino-induced RBM14 down-regulation can partially block the effects of RAR antagonist BMS493-induced RA signaling inhibition on embryonic malformation and cell apoptosis. In conclusion, exogenous RA causes neurodevelopmental toxicity, and RBM14 may be involved in this neurotoxic process.

Non-Targeted Metabolic Profiling of Cerebellum in Spina Bifida Fetal Rats

Spina bifida, known more commonly as myelomeningocele, is a neural tube defect that results in herniation of the cerebellum through the foramen magnum into the central canal as part of the Chiari II malformation. Effects stemming from the herniated cerebellum and its metabolic profile have not been extensively studied. The objective of this study is to examine the metabolic effects of this disease on the cerebellum in utero through the utilization of a retinoid acid-induced Spina bifida rat model. Analysis of this model at mid-late (day 15) and term (day 20) of gestation in comparison to both non-exposed and retinoic acid-exposed non-myelomeningocele controls, the observed metabolic changes suggest that mechanisms of oxidative stress and energy depletion are at play in this neuro tissue. These notable mechanisms are likely to result in further damage to neural tissue as the fetus grows and the compressed cerebellum develops and herniates more due to myelomeningocele.

The Central Nervous System Source Modulates Microglia Function and Morphology In Vitro

The regional heterogeneity of microglia was first described a century ago by Pio del Rio Hortega. Currently, new information on microglia heterogeneity throughout central nervous system (CNS) regions is being revealed by high-throughput techniques. It remains unclear whether these spatial specificities translate into different microglial behaviors in vitro. We cultured microglia isolated from the cortex and spinal cord and analyzed the effect of the CNS spatial source on behavior in vitro by applying the same experimental protocol and culture conditions. We analyzed the microglial cell numbers, function, and morphology and found a distinctive in vitro phenotype. We found that microglia were present in higher numbers in the spinal-cord-derived glial cultures, presenting different expressions of inflammatory genes and a lower phagocytosis rate under basal conditions or after activation with LPS and IFN-γ. Morphologically, the cortical microglial cells were more complex and presented longer ramifications, which were also observed in vivo in CX3CR1^+/GFP transgenic reporter mice. Collectively, our data demonstrated that microglial behavior in vitro is defined according to specific spatial characteristics acquired by the tissue. Thus, our study highlights the importance of microglia as a source of CNS for in vitro studies.

Effect of Photobiomodulation Combined with Physiotherapy on Functional Performance in Children with Myelomeningo-Cele-Randomized, Blind, Clinical Trial

BACKGROUND

This study aimed to evaluate the electrical activity of the rectus femoris, tibialis anterior, and lateral gastrocnemius muscles during the sit-to-stand task and functional mobility after a neurofunctional physiotherapy protocol associated with PBM.

METHODS

Twenty-five children were randomly allocated to either Active PBM + physiotherapy (n = 13) or PBM sham + physiotherapy (n = 12). PBM was carried out with a LED device (850 nm, 25 J, 50 s per point and 200 mW) at four points over the area with absence of a spiny process. Both groups completed a twelve-week supervised program with two weekly 45-60 min sessions. Pre-training and post-training assessments involved the Pediatric Evaluation of Disability Inventory (PEDI). Muscle activity was assessed using portable electromyography (BTS Engineering) and the electrodes were positioned on the lateral gastrocnemius, anterior tibialis, and rectus femoris muscles. The RMS data were recorded and analyzed.

RESULTS

After 24 sessions of the treatment protocol, improvements were found in the PEDI score. The participants presented greater independence in performing the tasks, requiring less assistance from their caregivers. More significant electrical activity was found in the three muscles evaluated between the rest period and execution of the sit-to-stand tasks, both in the more compromised or less compromised lower limbs.

CONCLUSION

Neurofunctional physiotherapy with or without PBM improved functional mobility and electrical muscle activity in children with myelomeningocele.

Unraveling the Mechanisms of Clinical Drugs-Induced Neural Tube Defects Based on Network Pharmacology and Molecular Docking Analysis

Chemotherapeutic agents such as methotrexate (MTX), raltitrexed (RTX), 5-fluorouracil (5-FU), hydroxyurea (HU), and retinoic acid (RA), and valproic acid (VPA), an antiepileptic drug, all can cause malformations in the developing central nervous system (CNS), such as neural tube defects (NTDs). However, the common pathogenic mechanisms remain unclear. This study aimed to explore the mechanisms of NTDs caused by MTX, RTX, 5-FU, HU, RA, and VPA (MRFHRV), based on network pharmacology and molecular biology experiments. The MRFHRV targets were integrated with disease targets, to find the potential molecules related to MRFHRV-induced NTDs. Protein-protein interaction analysis and molecular docking were performed to analyze these common targets. Utilizing the kyoto encyclopedia of genes and genomes (KEGG) signaling pathways, we analyzed and searched the possible causative pathogenic mechanisms by crucial targets and the signaling pathway. Results showed that MRFHRV induced NTDs through several key targets (including TP53, MAPK1, HSP90AA1, ESR1, GRB2, HDAC1, EGFR, PIK3CA, RXRA, and FYN) and multiple signaling pathways such as PI3K/Akt pathway, suggesting that abnormal proliferation and differentiation could be critical pathogenic contributors in NTDs induced by MRFHRV. These results were further validated by CCK8 assay in mouse embryonic stem cells and GFAP staining in embryonic brain tissue. This study indicated that chemotherapeutic and antiepileptic agents induced NTDs might through predicted targets TP53, MAPK1, GRB2, HDAC1, EGFR, PIK3CA, RXRA, and FYN and multiple signaling pathways. More caution was required for the clinical administration for women with childbearing potential and pregnant.

The Mechanism of Bladder Injury in Fetal Rats With Myelomeningocele

Background

Bladder dysfunction has been implicated as a major cause of progressive renal failure in children with neurogenic bladder. However, its pathogenesis remains unclear. This study aimed to compare the expression of proliferation, apoptosis, and neuromuscular-related proteins during the development of the bladder in myelomeningocele fetal rats, and to explore the characteristics of its abnormal development.

Methods

For the myelomeningocele group, Sprague Dawley pregnant rats were intragastrically injected with retinoic acid on the 10th day of gestation to induce myelomeningocele fetal rats. For the control group, the same amount of olive oil was injected to induce normal fetal rats. Bladders were harvested at embryonic days E16, E18, E20, and E22. Real-time quantitative polymerase chain reaction and western blotting were used to detect the protein levels of proliferating cell nuclear antigen (PCNA), cleaved caspase-3, neuron-specific nuclear-binding protein (NeuN), α-smooth muscle actin (α-SMA), and mRNA at E16-E22; immunohistochemistry was used to detect the expression of cleaved caspase-3 at E22.

Results

The proliferation of bladder tissue cells was inhibited, with suppressed PCNA expression in myelomeningocele bladder tissue compared with that in control tissue at the early stage (E16). Myelomeningocele bladders showed increased tissue apoptosis in the late embryonic stage, with significantly higher cleaved caspase-3 protein expression than in the control bladders at E20 and E22. NeuN protein expression increased along with embryonic stage, although the expression at E20 and E22 was significantly lower in myelomeningocele bladders than in control bladders. α-SMA protein expression in myelomeningocele bladders increased gradually with the progression of pregnancy, although its expression was lower than that for control bladders at E22. Immunohistochemistry showed abundant positive staining for cleaved caspase-3 in the bladder mucosa and muscle layer of myelomeningocele bladders, and the expression of cleaved caspase-3 was significantly higher in myelomeningocele bladders than in control bladders.

Conclusions

Bladder dysfunction in myelomeningocele fetal rats is related to the inhibition of proliferation, promotion of apoptosis, and reduction of bladder nerve and smooth muscle-related protein synthesis.

Premature Neural Progenitor Cell Differentiation Into Astrocytes in Retinoic Acid-Induced Spina Bifida Rat Model

During embryonic spinal cord development, neural progenitor cells (NPCs) generate three major cell lines: neurons, oligodendrocytes, and astrocytes at precise times and locations within the spinal cord. Recent studies demonstrate early astrogenesis in animal models of spina bifida, which may play a role in neuronal dysfunction associated with this condition. However, to date, the pathophysiological mechanisms related to this early astrocytic response in spina bifida are poorly understood. This study aimed to characterize the development of early astrogliosis over time from Pax6+, Olig2+, or Nkx2.2+ NPCs using a retinoic acid-induced spina bifida rat model. At three gestational ages (E15, E17, and E20), spinal cords from fetuses with retinoic acid-induced spina bifida, their healthy sibling controls, or fetuses treated with the vehicle control were analyzed. Results indicated that premature astrogliosis and astrocytic activation were associated with an altered presence of Pax6+, Olig2+, and Nkx2.2+ NPCs in the lesion compared to the controls. Finally, this response correlated with an elevation in genes involved in the Notch-BMP signaling pathway. Taken together, changes in NPC patterning factor expression with Notch-BMP signaling upregulation may be responsible for the altered astrogenesis patterns observed in the spinal cord in a retinoic acid-induced spina bifida model.

Time Course Transcriptome Analysis of Spina Bifida Progression in Fetal Rats

A better understanding of the transcriptomic modifications that occur in spina bifida may lead to identify mechanisms involved in the progression of spina bifida in utero and the development of new therapeutic strategies that aid in spinal cord regeneration after surgical interventions. In this study, RNA-sequencing was used to identify differentially expressed genes in fetal spinal cords from rats with retinoic acid-induced spina bifida at E15, E17, and E20. Gene ontology, KEGG, and protein–protein interaction analysis were conducted to predict pathways involved in the evolution of the disease. Approximately 3000, 1000 and 300 genes were differentially expressed compared to the control groups at E15, E17 and E20, respectively. Overall, the results suggest common alterations in certain pathways between gestational time points, such as upregulation in p53 and sonic hedgehog signaling at E15 and E17 and downregulation in the myelin sheath at E17 and E20. However, there were other modifications specific to gestational time points, including skeletal muscle development at E15, downregulated glucose metabolism at E17, and upregulated inflammation at E20. In conclusion, this work provides evidence that gestational age during spina bifida repair may be a significant variable to consider during the development of new regenerative therapeutics approaches.

The Unique Properties of Placental Mesenchymal Stromal Cells: A Novel Source of Therapy for Congenital and Acquired Spinal Cord Injury

Spinal cord injury (SCI) is a devasting condition with no reliable treatment. Spina bifida is the most common cause of congenital SCI. Cell-based therapies using mesenchymal stem/stromal cells (MSCS) have been largely utilized in SCI. Several clinical trials for acquired SCI use adult tissue-derived MSC sources, including bone-marrow, adipose, and umbilical cord tissues. The first stem/stromal cell clinical trial for spina bifida is currently underway (NCT04652908). The trial uses early gestational placental-derived mesenchymal stem/stromal cells (PMSCs) during the fetal repair of myelomeningocele. PMSCs have been shown to exhibit unique neuroprotective, angiogenic, and antioxidant properties, all which are promising applications for SCI. This review will summarize the unique properties and current applications of PMSCs and discuss their therapeutic role for acquired SCI.

Microglia regulation of synaptic plasticity and learning and memory

Microglia are the resident macrophages of the central nervous system. Microglia possess varied morphologies and functions. Under normal physiological conditions, microglia mainly exist in a resting state and constantly monitor their microenvironment and survey neuronal and synaptic activity. Through the C1q, C3 and CR3 “Eat Me” and CD47 and SIRPα “Don’t Eat Me” complement pathways, as well as other pathways such as CX3CR1 signaling, resting microglia regulate synaptic pruning, a process crucial for the promotion of synapse formation and the regulation of neuronal activity and synaptic plasticity. By mediating synaptic pruning, resting microglia play an important role in the regulation of experience-dependent plasticity in the barrel cortex and visual cortex after whisker removal or monocular deprivation, and also in the regulation of learning and memory, including the modulation of memory strength, forgetfulness, and memory quality. As a response to brain injury, infection or neuroinflammation, microglia become activated and increase in number. Activated microglia change to an amoeboid shape, migrate to sites of inflammation and secrete proteins such as cytokines, chemokines and reactive oxygen species. These molecules released by microglia can lead to synaptic plasticity and learning and memory deficits associated with aging, Alzheimer’s disease, traumatic brain injury, HIV-associated neurocognitive disorder, and other neurological or mental disorders such as autism, depression and post-traumatic stress disorder. With a focus mainly on recently published literature, here we reviewed the studies investigating the role of resting microglia in synaptic plasticity and learning and memory, as well as how activated microglia modulate disease-related plasticity and learning and memory deficits. By summarizing the function of microglia in these processes, we aim to provide an overview of microglia regulation of synaptic plasticity and learning and memory, and to discuss the possibility of microglia manipulation as a therapeutic to ameliorate cognitive deficits associated with aging, Alzheimer’s disease, traumatic brain injury, HIV-associated neurocognitive disorder, and mental disorders.

Key Modules and Hub Genes Identified by Coexpression Network Analysis for Revealing Novel Biomarkers for Spina Bifida

Spina bifida is a common neural tube defect (NTD) accounting for 5–10% of perinatal mortalities. As a polygenic disease, spina bifida is caused by a combination of genetic and environmental factors, for which the precise molecular pathogenesis is still not systemically understood. In the present study, we aimed to identify the related gene module that might play a vital role in the occurrence and development of spina bifida by using weighted gene co-expression network analysis (WGCNA). Transcription profiling according to an array of human amniocytes from patients with spina bifida and healthy controls was downloaded from the Gene Expression Omnibus database. First, outliers were identified and removed by principal component analysis (PCA) and sample clustering. Then, genes in the top 25% of variance in the GSE4182 dataset were then determined in order to explore candidate genes in potential hub modules using WGCNA. After data preprocessing, 5407 genes were obtained for further WGCNA. Highly correlated genes were divided into nineteen modules. Combined with a co-expression network and significant differentially expressed genes, 967 candidate genes were identified that may be involved in the pathological processes of spina bifida. Combined with our previous microRNA (miRNA) microarray results, we constructed an miRNA–mRNA network including four miRNAs and 39 mRNA among which three key genes were, respectively, linked to two miRNA-associated gene networks. Following the verification of qRT-PCR and KCND3 was upregulated in the spina bifida. KCND3 and its related miR-765 and miR-142-3p are worthy of further study. These findings may be conducive for early detection and intervention in spina bifida, as well as be of great significance to pregnant women and clinical staff.

Cholinergic Modulation of Glial Function During Aging and Chronic Neuroinflammation

Aging is a complex biological process that increases the risk of age-related cognitive degenerative diseases such as dementia, including Alzheimer’s disease (AD), Lewy Body Dementia (LBD), and mild cognitive impairment (MCI). Even non-pathological aging of the brain can involve chronic oxidative and inflammatory stress, which disrupts the communication and balance between the brain and the immune system. There has been an increasingly strong connection found between chronic neuroinflammation and impaired memory, especially in AD. While microglia and astrocytes, the resident immune cells of the central nervous system (CNS), exerting beneficial effects during the acute inflammatory phase, during chronic neuroinflammation they can become more detrimental. Central cholinergic circuits are involved in maintaining normal cognitive function and regulating signaling within the entire cerebral cortex. While neuronal-glial cholinergic signaling is anti-inflammatory and anti-oxidative, central cholinergic neuronal degeneration is implicated in impaired learning, memory sleep regulation, and attention. Although there is evidence of cholinergic involvement in memory, fewer studies have linked the cholinergic anti-inflammatory and anti-oxidant pathways to memory processes during development, normal aging, and disease states. This review will summarize the current knowledge of cholinergic effects on microglia and astroglia, and their role in both anti-inflammatory and anti-oxidant mechanisms, concerning normal aging and chronic neuroinflammation. We provided details on how stimulation of α7 nicotinic acetylcholine (α7nACh) receptors can be neuroprotective by increasing amyloid-β phagocytosis, decreasing inflammation and reducing oxidative stress by promoting the nuclear factor erythroid 2-related factor 2 (Nrf2) pathways and decreasing the release of pro-inflammatory cytokines. There is also evidence for astroglial α7nACh receptor stimulation mediating anti-inflammatory and antioxidant effects by inhibiting the nuclear factor-κB (NF-κB) pathway and activating the Nrf2 pathway respectively. We conclude that targeting cholinergic glial interactions between neurons and glial cells via α7nACh receptors could regulate neuroinflammation and oxidative stress, relevant to the treatment of several neurodegenerative diseases.

Neuromodulation of Glial Function During Neurodegeneration

Glia, a non-excitable cell type once considered merely as the connective tissue between neurons, is nowadays acknowledged for its essential contribution to multiple physiological processes including learning, memory formation, excitability, synaptic plasticity, ion homeostasis, and energy metabolism. Moreover, as glia are key players in the brain immune system and provide structural and nutritional support for neurons, they are intimately involved in multiple neurological disorders. Recent advances have demonstrated that glial cells, specifically microglia and astroglia, are involved in several neurodegenerative diseases including Amyotrophic lateral sclerosis (ALS), Epilepsy, Parkinson's disease (PD), Alzheimer's disease (AD), and frontotemporal dementia (FTD). While there is compelling evidence for glial modulation of synaptic formation and regulation that affect neuronal signal processing and activity, in this manuscript we will review recent findings on neuronal activity that affect glial function, specifically during neurodegenerative disorders. We will discuss the nature of each glial malfunction, its specificity to each disorder, overall contribution to the disease progression and assess its potential as a future therapeutic target.

Aging and sex: Impact on microglia phagocytosis

Microglia dysfunction and activation are important hallmarks of the aging brain and are concomitant with age-related neurodegeneration and cognitive decline. Age-associated changes in microglia migration and phagocytic capacity result in maladaptive responses, chronic neuroinflammation, and worsened outcomes in neurodegenerative disorders. Given the sex bias in the incidence, prevalence, and therapy response of most neurological disorders, we have here examined whether the phagocytic activity of aged microglia is different in males and females. With this aim, the phagocytosis activity of male and female cells was compared in an in vitro aged microglia model and in microglia isolated from adult (5-month-old) or aged (18-month-old) mice. In both models, the phagocytosis of neural debris increased with aging in male and female cells and was higher in aged female microglia than in aged male cells. However, female aged microglia lost its ability to adapt its phagocytic activity to inflammatory conditions. These findings suggest that microglia phagocytosis of neural debris may represent a previously unexplored neuroprotective characteristic of aged microglia that may contribute to the generation of sex differences in the manifestation of neurodegenerative diseases.

Nitric Oxide Modulation by Folic Acid Fortification

Folic acid (FA) can be protected the neural tube defects (NTDs) causing nitric oxide (NO) induction, but the alleviation mechanism of the detailed FA function against NO has not yet been clarified. This study focused on elucidation of the interaction of FA and NO. FA suppressed nitrite accumulation as the NO indicator in lipopolysaccharide (LPS)-stimulated RAW264.7 cells, then the expression of the iNOS gene due to the LPS treatment was not inhibited by FA, suggesting that FA can modulate against NO or nitrogen radicals. NOR3 (4-ethyl-2-hydroxyamino-5-nitro-3-hexenamide) as the NO donor was used for evaluation of the NO scavenging activity of FA. FA suppressed the nitrite accumulation in a dose-dependent manner. To confirm the reaction product of FA and NO (FA-NO), liquid chromatography–mass spectrometry (LC/MS) was used to measure a similar system containing NOR3 and FA, and then detected the mass numbers of the FA-NO as m/z 470.9 (M + H)⁺ and m/z 469.1 (M − H)⁻. In addition, the adducts of the FA-NO derived from ¹⁴NO and ¹⁵NO gave individual mass numbers of the isotopic ratio of nitrogen for the following products: FA-¹⁴NO, m/z 471.14 (M + H)⁺; m/z 469.17 (M − H)⁻ and FA-¹⁵NO, m/z 472.16 (M + H)⁺; m/z 470.12 (M − H)^–. To clarify the detailed NO scavenging action of FA, an electron spin resonance (ESR) study for radical detecting of the system containing carboxy-PTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) as an NO detection reagent in the presence of NOR3 and FA was performed. The carboxy-PTI (2-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl) radical produced from the reaction with NO reduced in the presence of FA showing that FA can directly scavenge NO. These results indicated that NO scavenging activity of FA reduced the accumulation of nitrite in the LPS-stimulated RAW264.7 cells. The NO modulation due to FA would be responsible for the alleviation from the failure in neural tube formation causing a high level of NO production.

The role of microglia in neuroprogressive disorders: mechanisms and possible neurotherapeutic effects of induced ketosis

A comprehensive review of molecular mechanisms involved in the promotion and maintenance of distinct microglia phenotypes is provided. The acquisition and perpetuation of predominantly pro-inflammatory microglial phenotypes have been implicated in the pathophysiology of several neuroprogressive diseases and is associated with reduced ATP production via oxidative phosphorylation, increased ATP generation by glycolysis, elevated oxidative and nitrosative stress and other metabolic, inflammatory and hormonal insults. Microglia can also adopt a predominantly anti-inflammatory phenotypes with neuroprotective properties. Strategies that promote and maintain a predominantly anti-inflammatory phenotype may hold promise as novel therapeutic opportunities for neuroprogressive illness. Induced ketosis may promote a transition towards predominantly anti-inflammatory microglial states/phenotypes by several mechanisms, including inhibition of glycolysis and increased NAD⁺ production; engagement of microglial GPR109A receptors; histone deacetylase inhibition; and elevated n-3 polyunsaturated fatty acids levels. Since microglia activation can now be assessed in vivo, these data provide a clear rationale for the design of transdiagnostic randomized controlled trials of the ketogenic diet and other ketosis-inducing strategies for neuroprogressive diseases, which may also provide mechanistic insights through the assessment of "target engagement".

Increased CD200 levels in peripheral blood mononuclear cells of patients with primary Sjögren's syndrome

OBJECTIVES

Primary Sjögren's syndrome (pSS) is a chronic autoimmune disease with an unknown etiology. CD200 is associated with many autoimmune diseases, but little is known about its role in pSS. This study aims to correlate the expression of CD200 with pSS and evaluate its significance.

METHODS

Plasma CD200, CD200R, and interleukin (IL)-17 levels were measured and analyzed by enzyme-linked immunosorbent assay. Messenger RNA levels of CD200 and CD200R in peripheral blood mononuclear cells (PBMCs) were quantified by quantitative real-time polymerase chain reaction (RT-qPCR). Following pretreatment of CD200-Fc, the protein levels of IL-17A were measured in PBMCs from patients and healthy controls.

RESULTS

Results showed that, compared to CD200 in healthy controls, the relative levels in PBMCs from pSS were greater than 2-fold. In addition, CD200 levels in plasma positively correlated with IL-17 levels, as well as between plasma CD200 and pSS activity indexes (including immunoglobulin G and European League Against Rheumatism SS Disease Activity Index). While CD200R levels were significantly decreased in pSS patients, no correlation could be found. Furthermore, the protein level of IL-17 decreased after pretreatment of CD200-Fc in PBMCs from pSS patients.

CONCLUSION

Our results suggested that the CD200/CD200R pathway is involved in pSS pathogenesis. It is hypothesized that regulation of IL-17 expression affects Th17 differentiation. This newly discovered pathway could give rise to a novel targeted therapy for pSS.

Cell necrosis, intrinsic apoptosis and senescence contribute to the progression of exencephaly to anencephaly in a mice model of congenital chranioschisis

Exencephaly/anencephaly is one of the leading causes of neonatal mortality and the most extreme open neural tube defect with no current treatments and limited mechanistic understanding. We hypothesized that exencephaly leads to a local neurodegenerative process in the brain exposed to the amniotic fluid as well as diffuse degeneration in other encephalic areas and the spinal cord. To evaluate the consequences of in utero neural tissue exposure, brain and spinal cord samples from E17 exencephalic murine fetuses (maternal intraperitoneal administration of valproic acid at E8) were analyzed and compared to controls and saline-injected shams (n = 11/group). Expression of apoptosis and senescence genes (p53, p21, p16, Rbl2, Casp3, Casp9) was determined by qRT-PCR and protein expression analyzed by western blot. Apoptosis was measured by TUNEL assay and PI/AV flow cytometry. Valproic acid at E8 induced exencephaly in 22% of fetuses. At E17 the fetuses exhibited the characteristic absence of cranial bones. The brain structures from exencephalic fetuses demonstrated a loss of layers in cortical regions and a complete loss of structural organization in the olfactory bulb, hippocampus, dental gyrus and septal cortex. E17 fetuses had reduced expression of NeuN, GFAP and Oligodendrocytes in the brain with primed microglia. Intrinsic apoptotic activation (p53, Caspase9 and 3) was upregulated and active Caspase3 localized to the layer of brain exposed to the amniotic fluid. Senescence via p21-Rbl2 was increased in the brain and in the spinal cord at the lamina I-II of the somatosensory dorsal horn. The current study characterizes CNS alterations in murine exencephaly and demonstrates that degeneration due to intrinsic apoptosis and senescence occurs in the directly exposed brain but also remotely in the spinal cord.

Anti-angiogenic and anti-inflammatory effects of CD200-CD200R1 axis in oxygen-induced retinopathy mice model

OBJECTIVE

In this study, the expression changes and the potential effects of CD200 and its receptors during the process of retinal neovascularization (RNV) development had been detected, using a classic oxygen-induced retinopathy (OIR) mice model and CD200Fc (a CD200R1 agonist) intravitreal injection.

MATERIALS AND METHODS

7 day postnatal (P7) C57BL/6J mice were raised in hyperoxia incubators with 75±2% oxygen for 5 days, and returned to room air at P12. All animals were subdivided into three groups: normoxia control, OIR, and OIR+CD200Fc group. The mice of OIR+CD200Fc group were intravitreal injected with CD200Fc (2μg/μL, 0.5μL) at P12. Retinas and vitreous samples were harvested at P17. The expression and localization of CD200 and its receptors were analyzed by Western blot, quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), and retinal whole-mount immunofluorescence. To investigate the effects of CD200Fc treatment, vascular endothelial growth factor (VEGF)-A, platelet-derived growth factor (PDGF)-BB, pro-inflammatory cytokines, NV area, and microglial activation were detected respectively.

RESULTS

In OIR group, both protein and RNA levels of CD200 and CD200R1 were significantly up-regulated. The increased CD200 and CD200R1 were co-localized with Alex594-labeled Griffonia simplicifolia isolectin B4 (IB4) on vascular endothelial cells in NV area of OIR samples, and CD200R1 was co-expressed with ionized calcium-bind adapter molecule 1 (iba1) on microglia in OIR samples at the same time. CD200Fc intravitreal injection could significantly reduce the release of VEGF-A, PDGF-BB, and pro-inflammatory cytokines; shrink the NV area; and inhibit the activation of microglia in OIR mice.

CONCLUSION

These findings suggested that the up-regulation of CD200 and CD200R1 was closely related to RNV development, and the antiangiogenic effects of CD200Fc in OIR model might be realized by inhibition of inflammatory response and microglia activation. The results may provide a new therapeutic target for RNV diseases.

CD200-CD200R Interaction: An Important Regulator After Stroke

The high mortality and morbidity rate of stroke is a chronic problem that plagues human society. The activation of microglia is one of the principal reasons why neuroinflammation induces cerebral dysfunction. Because of their vital functions in the regulation of neuroinflammation, microglia constitute an important target for stroke. Given that there is an innate self-preservation mechanism between neurons and microglia, the transmembrane glycoproteins on the surface of their membranes, namely CD200 and CD200R, have become a popular topic of research. Numerous studies have demonstrated that CD200-CD200R interaction, microglial activation, and poststroke neuroinflammatory damage are inextricably linked. In this review, we describe the above relationship from a new perspective. We specifically focus on neuroinflammation after stroke. The role of crosstalk of CD200-CD200R inhibitory immune ligand receptors in immune regulation will also be illustrated. Thus, we will see how poststroke injury can be influenced by the CD200-CD200R crosstalk. Finally, we will discuss the possibility of clinical application of the result of CD200-CD200R interaction to manage neuroinflammatory injury after stroke.

CD200Fc Improves Neurological Function by Protecting the Blood-brain Barrier after Intracerebral Hemorrhage

CD200 is widely distributed in the central nervous system and plays an essential role in the immune response in neurological diseases. However, little is currently known about the effects of CD200 signaling on the blood–brain barrier (BBB) function after intracerebral hemorrhage (ICH). In this study, the role of CD200 during ICH in an autologous blood induced mouse ICH model was investigated. Following ICH, critical protein expression, BBB permeability, and neurological function were measured with or without CD200Fc administration. Our results showed that both the expression of CD200 and CD200R1 decreased after ICH and administration of CD200Fc attenuated BBB leakage and improved neurological functions. In conclusion, our work demonstrated that CD200Fc might be a potential treatment option for ICH by protecting the BBB and improving functional outcomes.