Alpha-smooth muscle actin (alpha-SMA) and nestin expression in reactive astrocytes in multiple sclerosis lesions: potential regulatory role of transforming growth factor-beta 1 (TGF-beta1)

Mossy fiber expression of αSMA in human hippocampus and its relevance to brain evolution and neuronal development

α-Smooth muscle actin (αSMA) is best characterized as the building block of thin filaments in smooth muscle cells. We observed a clear αSMA immunolabeling in adult human hippocampal mossy fibers (MF), prompting us to explore this novel pattern in phylogenic and ontogenic perspectives in the present study. αSMA immunolabeling occurred distinctively at the hippocampal MF terminals in humans from infancy to elderly. Hippocampal MF αSMA immunolabeling was not observed in mice and rats, visible in CA3 in guinea pigs and cats, and prominent in CA3 and dentate hilus in Rhesus monkeys. MF αSMA immunolabeling in human hippocampus emerged and refined from the last gestational trimester to early infancy. A transient overall neuronal labeling of ɑSMA was observed in prenatal human brains. ɑSMA expression was detected in human and rat primary neuronal cultures. The specificity of ɑSMA antibodies was confirmed by ACTA2 small interfering RNA (siRNA) silencing in SH-SY5Y cells. With this validation, we detected a higher αSMA protein level in dentate gyrus lysates relative to other human brain areas. Taken together, αSMA is distinctly expressed in human hippocampal mossy fibers. This pattern is related to hippocampal evolution among mammals and involves a refinement of neuronal αSMA expression during brain development.

Neuroinflammation and neurodegeneration following traumatic brain injuries

Traumatic brain injuries (TBI) commonly occur following head trauma. TBI may result in short- and long-term complications which may lead to neurodegenerative consequences, including cognitive impairment post-TBI. When investigating the neurodegeneration following TBI, studies have highlighted the role reactive astrocytes have in the neuroinflammation and degeneration process. This review showcases a variety of markers that show reactive astrocyte presence under pathological conditions, including glial fibrillary acidic protein (GFAP), Crystallin Alpha-B (CRYA-B), Complement Component 3 (C3) and S100A10. Astrocyte activation may lead to white-matter inflammation, expressed as white-matter hyperintensities. Other white-matter changes in the brain following TBI include increased cortical thickness in the white matter. This review addresses the gaps in the literature regarding post-mortem human studies focussing on reactive astrocytes, alongside the potential uses of these proteins as markers in the future studies that investigate the proportions of astrocytes in the post-TBI brain has been discussed. This research may benefit future studies that focus on the role reactive astrocytes play in the post-TBI brain and may assist clinicians in managing patients who have suffered TBI.

MicroRNA-219 in the central nervous system: a potential theranostic approach

Despite the recent therapeutic advances in neurological disorders, curative therapy remains a serious challenge in many cases. Even though recent years have witnessed the development of gene therapy from among the different therapeutic approaches affecting pathophysiological mechanisms, intriguing aspects exist regarding the effectiveness, safety, and mechanism of action of gene therapies. Micro ribonucleic acid (microRNA-miRNA), as a fundamental gene regulator, regulates messenger ribonucleic acid (mRNA) by directly binding through the 3'-untranslated region (3'-UTR). MicroRNA-219 is a specific brain-enriched miRNA associated with neurodevelopmental disorders that play crucial roles in the differentiation of oligodendrocyte progenitorcells, promotion of oligodendrocyte maturation, remyelination, and cognitive functions to the extent that it can be considered a potential therapeutic option for demyelination in multiple sclerosis and spinal cord injury and reverse chronic inflammation pains. Additionally, miR-219 regulates the circadian clock, influencing the duration of the circadian clock period. This regulation can impact mood stability and is associated with phase fluctuations in bipolar patients. Furthermore, miR-219 also plays a role in modulating tau toxicity, which is relevant to the pathophysiology of Alzheimer's disease and schizophrenia. Finally, it reportedly has protective effects against seizures and Parkinson's disease, as well as neoplasms, by inhibiting proliferation, suppressing invasion, and inducing cell death in tumor cells. Exploring the miR-219 molecular pathways and their therapeutic effects on central nervous system disorders and the mechanisms involved, the present review study aims to illustrate how this information may change the future of gene therapy.

Development of Tissue-Engineered Model of Fibrotic Scarring after Spinal Cord Injury to Study Astrocyte Activation and Neurite Outgrowth In Vitro

Traumatic spinal cord injuries (SCI) are debilitating injuries affecting twenty-seven million people worldwide and cause functional impairments. Despite decades of research and medical advancements, current treatment options for SCI remain limited, in part due to the complex pathophysiology of spinal cord lesions including cellular transformation and extracellular matrix (ECM) remodeling. Recent studies have increased focus on fibrotic scarring after SCI, and yet much remains unclear about the impact of fibrotic scarring on SCI lesion progression. Here, using collagen and decellularized spinal cord-based composite hydrogels, a three-dimensional (3D) cell culture model mimicking the fibrous core of spinal cord lesions was implemented to investigate its influence on the surrounding astrocytes. To mimic the fibrotic milieu, collagen fibril thickness was tuned using previously established temperature-controlled casting methods. In our platforms, astrocytes in fibro-mimetic hydrogels exhibited increased levels of activation markers such as glial fibrillary acidic protein and N-cadherin. Furthermore, astrocytes in fibro-mimetic hydrogels deposited more fibronectin and laminin, further hinting that astrocytes may also contribute to fibrotic scarring. These markers were decreased when Rho-ROCK and integrin β1 were inhibited via pharmacological inhibitors. Mechanistic analysis of Yes-associated protein reveals that blocking integrin β1 prevents mechanosensing of astrocytes, contributing to altered phenotypes in variable culture conditions. In the presence of these inhibitors, astrocytes increased the secretion of brain-derived neurotrophic factor, and a greater degree of dorsal root ganglia neurite infiltration into the underlying hydrogels was observed. Altogether, this study presents a novel tissue-engineered platform to study fibrotic scarring after SCI and may be a useful platform to advance our understanding of SCI lesion aggravation.

Adrenergic receptors blockade alleviates dexamethasone-induced neurotoxicity in adult male Wistar rats: Distinct effects on β-arrestin2 expression and molecular markers of neural injury

BACKGROUND

Dexamethasone-induced neurotoxicity has been previously reported. However, the molecular mechanisms are still not completely understood.

OBJECTIVES

The current work aimed to investigate the modulatory effects of α- and β-adrenergic receptors on dexamethasone-induced neurotoxicity in rats focused on changes in β-arrestin2 and molecular markers of neural injury in cerebral cortex.

METHODS

Male Wistar rats were subcutaneously injected with dexamethasone (10 mg/kg/day) for 7 days to induce neural injury in the cerebral cortex. The experiment involved 5 groups: control, dexamethasone, carvedilol, propranolol, and doxazosin. In the last 3 groups, drugs were given 2 hours before dexamethasone injection. At the end of experiment, brain samples were collected for measurement of brain derived neurotrophic factor (BDNF), glial fibrillary acidic protein (GFAP), kinase activity of protein kinase B (Akt), diacylglycerol (DAG), α-smooth muscle actin (α-SMA), Smad3, β-amyloid and phospho-tau protein levels in addition to histopathological examination of brain tissue using hematoxylin-eosin, Nissl, and Sirius red stains. Moreover, β-arrestin2 levels in the cerebral cortex were measured using immunohistochemical examination.

RESULTS

Dexamethasone slightly reduced brain weight and significantly decreased BDNF, Akt kinase activity and β-arrestin2 but markedly induced degeneration of cortical neurons and significantly increased GFAP, DAG, α-SMA, Smad3, β-amyloid and phospho-tau protein levels compared to controls. Carvedilol, propranolol, and doxazosin reversed all dexamethasone-induced molecular changes and slightly ameliorated the histopathological changes. Carvedilol significantly increased brain weight and β-arrestin2 levels compared to dexamethasone, propranolol, and doxazosin groups.

CONCLUSION

blocking α- and/or β-adrenergic receptors alleviate dexamethasone-induced neurotoxicity despite their distinct effects on β-arrestin2 levels in the cerebral cortex.

Blood-brain barrier biomarkers

The blood-brain barrier (BBB) is a dynamic interface that regulates the exchange of molecules and cells between the brain parenchyma and the peripheral blood. The BBB is mainly composed of endothelial cells, astrocytes and pericytes. The integrity of this structure is essential for maintaining brain and spinal cord homeostasis and protection from injury or disease. However, in various neurological disorders, such as traumatic brain injury, Alzheimer's disease, and multiple sclerosis, the BBB can become compromised thus allowing passage of molecules and cells in and out of the central nervous system parenchyma. These agents, however, can serve as biomarkers of BBB permeability and neuronal damage, and provide valuable information for diagnosis, prognosis and treatment. Herein, we provide an overview of the BBB and changes due to aging, and summarize current knowledge on biomarkers of BBB disruption and neurodegeneration, including permeability, cellular, molecular and imaging biomarkers. We also discuss the challenges and opportunities for developing a biomarker toolkit that can reliably assess the BBB in physiologic and pathophysiologic states.

PS-MPs promotes the progression of inflammation and fibrosis in diabetic nephropathy through NLRP3/Caspase-1 and TGF-β1/Smad2/3 signaling pathways

BACKGROUND

Diabetic nephropathy (DN) is a prevalent chronic microvascular complication of diabetes and the leading cause of end-stage renal disease (ESRD). Understanding the progressive etiology of DN is critical for the development of effective health policies and interventions. Recent research indicated that polystyrene microplastics (PS-MPs) contaminate our diets and accumulate in various organs, including the liver, kidneys, and muscles.

METHODS

In this study, ten-week-old db/db mice and db/m mice were fed. Besides, db/db mice were divided into two groups: PS-MPs group (oral administration of 0.5 µm PS-MPs) and an H2O group, and they were fed for three months. A type II diabetes model was established using db/db mice to investigate the effects of PS-MPs on body weight, blood glucose level, renal function, and renal fibrosis.

RESULTS

The results demonstrated that PS-MPs significantly exacerbated various biochemical indicators of renal tissue damage, including fasting blood glucose, serum creatinine, blood urea nitrogen, and blood uric acid. Additionally, PS-MPs worsened the pathological alterations and degree of fibrosis in renal tissue. An increased oxidative stress state and elevated levels of inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and monocyte chemoattractant protein-1 (MCP-1) were identified. Furthermore, PS-MPs significantly enhanced renal fibrosis by inhibiting the transition from epithelial cells to mesenchymal cells, specifically through the inhibition of the TGF-β/Smad signaling pathway. The expression levels of NOD-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), Caspase-1, and cleaved Caspase-1, which are inflammasome proteins, were significantly elevated in the PS-MPs group.

CONCLUSION

The findings suggested that PS-MPs could aggravate kidney injury and renal fibrosis in db/db mice by promoting NLRP3/Caspase-1 and TGF-β1/Smads signaling pathways. These findings had implications for elucidating the role of PS-MPs in DN progression, underscoring the necessity for additional research and public health interventions.

IOP and glaucoma damage: The essential role of optic nerve head and retinal mechanosensors

There are many unanswered questions on the relation of intraocular pressure to glaucoma development and progression. IOP itself cannot be distilled to a single, unifying value, because IOP level varies over time, differs depending on ocular location, and can be affected by method of measurement. Ultimately, IOP level creates mechanical strain that affects axonal function at the optic nerve head which causes local extracellular matrix remodeling and retinal ganglion cell death - hallmarks of glaucoma and the cause of glaucomatous vision loss. Extracellular tissue strain at the ONH and lamina cribrosa is regionally variable and differs in magnitude and location between healthy and glaucomatous eyes. The ultimate targets of IOP-induced tissue strain in glaucoma are retinal ganglion cell axons at the optic nerve head and the cells that support axonal function (astrocytes, the neurovascular unit, microglia, and fibroblasts). These cells sense tissue strain through a series of signals that originate at the cell membrane and alter cytoskeletal organization, migration, differentiation, gene transcription, and proliferation. The proteins that translate mechanical stimuli into molecular signals act as band-pass filters - sensing some stimuli while ignoring others - and cellular responses to stimuli can differ based on cell type and differentiation state. Therefore, to fully understand the IOP signals that are relevant to glaucoma, it is necessary to understand the ultimate cellular targets of IOP-induced mechanical stimuli and their ability to sense, ignore, and translate these signals into cellular actions.

Altered energy metabolism in Fatal Familial Insomnia cerebral organoids is associated with astrogliosis and neuronal dysfunction

Fatal familial insomnia (FFI) is a rare neurodegenerative disease caused by a dominantly inherited single amino acid substitution (D178N) within the prion protein (PrP). No in vitro human brain tissue model for this disease has previously been available. Consequently, how this mutation exerts its damaging effect on brain cells is still unknown. Using CRISPR-Cas9 engineered induced pluripotent stem cells, we made D178N cerebral organoids and compared these with isotype control organoids. We found that, in the absence of other hallmarks of FFI, the D178N organoids exhibited astrogliosis with cellular oxidative stress. Abnormal post-translational processing of PrP was evident but no tissue deposition or propagation of mis-folded PrP isoforms were observed. Neuronal electrophysiological function was compromised and levels of neurotransmitters, particularly acetylcholine and GABA, altered. Underlying these dysfunctions were changes in cellular energy homeostasis, with substantially increased glycolytic and Krebs cycle intermediates, and greater mitochondrial activity. This increased energy demand in D178N organoids was associated with increased mitophagy and depletion of lipid droplets, in turn resulting in shifts of cellular lipid composition. Using a double mutation (178NN) we could confirm that most changes were caused by the presence of the mutation rather than interaction with PrP molecules lacking the mutation. Our data strongly suggests that shifting biosynthetic intermediates and oxidative stress, caused by an imbalance of energy supply and demand, results in astrogliosis with compromised neuronal activity in FFI organoids. They further support that many of the disease associated changes are due to a corruption of PrP function and do not require propagation of PrP mis-folding.

Targeting the Type 5 Metabotropic Glutamate Receptor: A Potential Therapeutic Strategy for Neurodegenerative Diseases?

The type 5 metabotropic glutamate receptor, mGlu₅, has been proposed as a potential therapeutic target for the treatment of several neurodegenerative diseases. In preclinical neurodegenerative disease models, novel allosteric modulators have been shown to improve cognitive performance and reduce disease-related pathology. A common pathological hallmark of neurodegenerative diseases is a chronic neuroinflammatory response, involving glial cells such as astrocytes and microglia. Since mGlu₅ is expressed in astrocytes, targeting this receptor could provide a potential mechanism by which neuroinflammatory processes in neurodegenerative disease may be modulated. This review will discuss current evidence that highlights the potential of mGlu₅ allosteric modulators to treat neurodegenerative diseases, including Alzheimer’s disease, Huntington’s disease, Parkinson’s disease, and amyotrophic lateral sclerosis. Furthermore, this review will explore the role of mGlu₅ in neuroinflammatory responses, and the potential for this G protein-coupled receptor to modulate neuroinflammation.

High-Throughput Analysis of Astrocyte Cultures Shows Prevention of Reactive Astrogliosis by the Multi-Nutrient Combination Fortasyn Connect

Astrocytes are specialized glial cells that tile the central nervous system (CNS) and perform numerous essential functions. Astrocytes react to various forms of CNS insults by altering their morphology and molecular profile, through a process known as reactive astrogliosis. Accordingly, astrocyte reactivity is apparent in many neurodegenerative diseases, among which one is Alzheimer’s disease (AD). Recent clinical trials on early-stage AD have demonstrated that Fortasyn Connect (FC), a multi-nutrient combination providing specific precursors and cofactors for phospholipid synthesis, helps to maintain neuronal functional connectivity and cognitive performance of patients. Several studies have shown that FC may act through its effects on neuronal survival and synaptogenesis, leading to reduced astrocyte reactivity, but whether FC can directly counteract astrocyte reactivity remains to be elucidated. Hence, we developed an in vitro model of reactive astrogliosis using the pro-inflammatory cytokines TNF-α and IFN-γ together with an automated high-throughput assay (AstroScan) to quantify molecular and morphological changes that accompany reactive astrogliosis. Next, we showed that FC is potent in preventing cytokine-induced reactive astrogliosis, a finding that might be of high relevance to understand the beneficial effects of FC-based interventions in the context of neurodegenerative diseases.

Beyond the GFAP-Astrocyte Protein Markers in the Brain

The idea of central nervous system as one-man band favoring neurons is long gone. Now we all are aware that neurons and neuroglia are team players and constant communication between those various cell types is essential to maintain functional efficiency and a quick response to danger. Here, we summarize and discuss known and new markers of astroglial multiple functions, their natural heterogeneity, cellular interactions, aging and disease-induced dysfunctions. This review is focused on newly reported facts regarding astrocytes, which are beyond the old stereotypes. We present an up-to-date list of marker proteins used to identify a broad spectrum of astroglial phenotypes related to the various physiological and pathological nervous system conditions. The aim of this review is to help choose markers that are well-tailored for specific needs of further experimental studies, precisely recognizing differential glial phenotypes, or for diagnostic purposes. We hope it will help to categorize the functional and structural diversity of the astroglial population and ease a clear readout of future experimental results.

Reactive astrocyte nomenclature, definitions, and future directions

Reactive astrocytes are astrocytes undergoing morphological, molecular, and functional remodeling in response to injury, disease, or infection of the CNS. Although this remodeling was first described over a century ago, uncertainties and controversies remain regarding the contribution of reactive astrocytes to CNS diseases, repair, and aging. It is also unclear whether fixed categories of reactive astrocytes exist and, if so, how to identify them. We point out the shortcomings of binary divisions of reactive astrocytes into good-vs-bad, neurotoxic-vs-neuroprotective or A1-vs-A2. We advocate, instead, that research on reactive astrocytes include assessment of multiple molecular and functional parameters-preferably in vivo-plus multivariate statistics and determination of impact on pathological hallmarks in relevant models. These guidelines may spur the discovery of astrocyte-based biomarkers as well as astrocyte-targeting therapies that abrogate detrimental actions of reactive astrocytes, potentiate their neuro- and glioprotective actions, and restore or augment their homeostatic, modulatory, and defensive functions.

RGC-32 Regulates Generation of Reactive Astrocytes in Experimental Autoimmune Encephalomyelitis

Astrocytes are increasingly recognized as critical contributors to multiple sclerosis pathogenesis. We have previously shown that lack of Response Gene to Complement 32 (RGC-32) alters astrocyte morphology in the spinal cord at the peak of experimental autoimmune encephalomyelitis (EAE), suggesting a role for RGC-32 in astrocyte differentiation. In this study, we analyzed the expression and distribution of astrocytes and astrocyte progenitors by immunohistochemistry in spinal cords of wild-type (WT) and RGC-32-knockout (KO) mice with EAE and of normal adult mice. Our analysis showed that during acute EAE, WT astrocytes had a reactive morphology and increased GFAP expression, whereas RGC-32 KO astrocytes had a morphology similar to that of radial glia and an increased expression of progenitor markers such as vimentin and fatty acid binding protein 7 (FABP7). In control mice, GFAP expression and astrocyte density were also significantly higher in the WT group, whereas the number of vimentin and FABP7-positive radial glia was significantly higher in the RGC-32 KO group. In vitro studies on cultured neonatal astrocytes from WT and RGC-32 KO mice showed that RGC-32 regulates a complex array of molecular networks pertaining to signal transduction, growth factor expression and secretion, and extracellular matrix (ECM) remodeling. Among the most differentially expressed factors were insulin-like growth factor 1 (IGF1), insulin-like growth factor binding proteins (IGFBPs), and connective tissue growth factor (CTGF); their expression was downregulated in RGC-32-depleted astrocytes. The nuclear translocation of STAT3, a transcription factor critical for astrogliogenesis and driving glial scar formation, was also impaired after RGC-32 silencing. Taken together, these data suggest that RGC-32 is an important regulator of astrocyte differentiation during EAE and that in the absence of RGC-32, astrocytes are unable to fully mature and become reactive astrocytes.

IL-10 alleviates lipopolysaccharide-induced skin scarring via IL-10R/STAT3 axis regulating TLR4/NF-κB pathway in dermal fibroblasts

Hypertrophic scar (HS) is a severe fibrotic skin disease. It has always been a major problem in clinical treatment, mainly because its pathogenesis has not been well understood. The roles of bacterial contamination and prolonged wound inflammation were considered significant. IL‐10 is a potent anti‐inflammatory cytokine and plays a pivotal role in wound healing and scar formation. Here, we investigate whether IL‐10 alleviates lipopolysaccharide (LPS)‐induced inflammatory response and skin scarring and explore the possible mechanism of scar formation. Our results showed that the expression of TLR4 and pp65 was higher in HS and HS‐derived fibroblasts (HSFs) than their counterpart normal skin (NS) and NS‐derived fibroblasts (NSFs). LPS could up‐regulate the expression of TLR4, pp65, Col I, Col III and α‐SMA in NSFs, but IL‐10 could down‐regulate their expression in both HSFs and LPS‐induced NSFs. Blocking IL‐10 receptor (IL‐10R) or the phosphorylation of STAT3, their expression was up‐regulated. In addition, in vitro and in vivo models results showed that IL‐10 could alleviate LPS‐induced fibroblast‐populated collagen lattice (FPCL) contraction and scar formation. Therefore, IL‐10 alleviates LPS‐induced skin scarring via IL‐10R/STAT3 axis regulating TLR4/NF‐κB pathway in dermal fibroblasts by reducing ECM proteins deposition and the conversion of fibroblasts to myofibroblasts. Our results indicate that IL‐10 can alleviate the LPS‐induced harmful effect on wound healing, reduce scar contracture, scar formation and skin fibrosis. Therefore, the down‐regulation of inflammation may lead to a suitable scar outcome and be a better option for improving scar quality.

Heat Shock Protein 90 Involvement in the Development of Idiopathic Epiretinal Membranes

Purpose

This work was aimed to further characterize cells of idiopathic epiretinal membranes (iERMs). We wanted to determine the contribution of 90-kDa heat shock protein (HSP90) to sustain the transforming growth factor-β (TGF-β)-mediated signal transduction pathway in iERM.

Methods

Immunofluorescence and confocal microscopy were carried out on deplasticized sections from 36 epiretinal membranes processed for electron microscopy and on frozen sections from five additional samples with antibodies against α-smooth muscle actin (αSMA), vimentin, glial fibrillary acidic protein (GFAP), SMAD2, HSP90α, type-II TGF-β1 receptor (TβRII), type-I collagen, and type-IV collagen. In addition, Müller MIO-M1 cells were transfected with HSP90 and challenged with TGF-β1.

Results

Double and triple labeling experiments showed that a variable number of TβRII+ cells were present in 94.1% of tested iERMs and they were mostly GFAP-/αSMA+/vimentin+/HSP90α+. In almost half of the cases these cells contained type-I collagen, suggesting their involvement in matrix deposition. HSP90 overexpressing MIO-M1 cells challenged with TGF-β1 showed increased levels of TβRII, SMAD2, SMAD3, and phosphor-SMAD2. Nuclear SMAD2 staining could be observed in HSP90α+ cells on frozen sections of iERMs.

Conclusions

Cells in iERMs that express TβRII are also HSP90α+ and show the antigenic profile of myofibroblast-like cells as they are GFAP-/αSMA+/vimentin+. HSP90α-overexpressing MIO-M1 cells challenged with TGF-β1 showed an increased activation of the SMAD pathway implying that HSP90α might play a role in sustaining the TGF-β1-induced fibrotic response of iERM cells.

Ethyl Pyruvate-Derived Transdifferentiation of Astrocytes to Oligodendrogenesis in Cuprizone-Induced Demyelinating Model

Astrocytes redifferentiate into oligodendrogenesis, raising the possibility that astrocytes may be a potential target in the treatment of adult demyelinated lesion. Upon the basis of the improvement of behavior abnormality and demyelination by ethyl pyruvate (EP) treatment, we further explored whether EP affects the function of astrocytes, especially the transdifferentiation of astrocytes into oligodendrogenesis. The results showed that EP treatment increased the accumulation of astrocytes in myelin sheath and promoted the phagocytosis of myelin debris by astrocytes in vivo and in vitro. At the same time, EP treatment induced astrocytes to upregulate the expression of CNTF and BDNF in the corpus callosum and striatum as well as cultured astrocytes, accompanied by increased expression of nestin, Sox2, and β-catenin and decreased expression of Notch1 by astrocytes. As a result, EP treatment effectively promoted the generation of NG2+ and PDGF-Ra+ oligodendrocyte precursor cells (OPCs) that, in part, express astrocyte marker GFAP. Further confirmation was performed by intracerebral injection of primary astrocytes labeled with carboxyfluorescein diacetate succinimidyl ester (CFSE). As expected, NG2+ OPCs expressing CFSE and Sox2 were elevated in the corpus callosum of mice treated with EP following transplantation, revealing that EP can convert astrocytes into myelinating cells. Our results indicate the possibility that EP lead to effective myelin repair in patients suffering from myelination deficit.Graphical Abstract The diagram of EP action for promoting myelin regeneration in CPZ model. EP promoted migration and enrichment of astrocytes to demyelinated tissue and induced astrocytes to express neurotrophic CNTF and BDNF as well as translation factor nestin, Sox2, and β-catenin, which should contribute to astrocytes to differentiate of oligodendrogenesis. At the same time, EP promoted astrocytes to phagocytized myelin debris for removing the harmful substances of myelin regeneration.

RGC-32 regulates reactive astrocytosis and extracellular matrix deposition in experimental autoimmune encephalomyelitis

Extracellular matrix (ECM) deposition in active demyelinating multiple sclerosis (MS) lesions may impede axonal regeneration and can modify immune reactions. Response gene to complement (RGC)-32 plays an important role in the mediation of TGF-β downstream effects, but its role in gliosis has not been investigated. To gain more insight into the role played by RGC-32 in gliosis, we investigated its involvement in TGF-β-induced ECM expression and the upregulation of the reactive astrocyte markers α-smooth muscle actin (α-SMA) and nestin. In cultured neonatal rat astrocytes, collagens I, IV, and V, fibronectin, α-SMA, and nestin were significantly induced by TGF-β stimulation, and RGC-32 silencing resulted in a significant reduction in their expression. Using astrocytes isolated from RGC-32 knock-out (KO) mice, we found that the expression of TGF-β-induced collagens I, IV, and V, fibronectin, and α-SMA was significantly reduced in RGC-32 KO mice when compared with wild-type (WT) mice. SIS3 inhibition of Smad3 phosphorylation was also associated with a significant reduction in RGC-32 nuclear translocation and TGF-β-induced collagen I expression. In addition, during experimental autoimmune encephalomyelitis (EAE), RGC-32 KO mouse astrocytes displayed an elongated, bipolar phenotype, resembling immature astrocytes and glial progenitors whereas those from WT mice had a reactive, hypertrophied phenotype. Taken together, our data demonstrate that RGC-32 plays an important role in mediating TGF-β-induced reactive astrogliosis in EAE. Therefore, RGC-32 may represent a new target for therapeutic intervention in MS.

iTRAQ-based quantitative proteomics reveals the neuroprotection of rhubarb in experimental intracerebral hemorrhage

ETHNOPHARMACOLOGICAL RELEVANCE

Rhubarb is a traditional Chinese medicine(TCM), that possesses neuroprotective, anti-inflammatory, antibacterial, antioxidative, purgative and anticancer properties, and has been used to treat intracerebral hemorrhage (ICH) and many other diseases.

AIMS OF THE STUDY

This study aimed to investigate the changes of brain protein in ICH rats treated with rhubarb and to explore the multi-target mechanism of rhubarb in the treatment of ICH via bioinformatics analysis of differentially expressed proteins (DEPs).

MATERIALS AND METHODS

Rats were subjected to collagenase-induced ICH and then treated orally with 3 or 12 g/kg rhubarb daily for 2 days following ICH. After sacrifice, total protein of brain tissue was extracted, and isobaric tag for relative and absolute quantification (iTRAQ)-based liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis was employed to quantitatively identify of the DEPs in two treatment groups compared with the vehicle group. The DEPs were analyzed by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and STRING databases. Bioinformatics Analysis Tool for Molecular mechanism of TCM (BATMAN-TCM) was used to predict the target of rhubarb and western blotting was used for verification.

RESULTS

In total, 1356 proteins were identified with a 1% false discovery rate (FDR). Among them, 55 DEPs were significantly altered in the sham, vehicle, low dose rhubarb group (LDR, 3 g/kg), and high dose rhubarb group (HDR, 12 g/kg). Enrichment analysis of GO annotations indicated that rhubarb mainly regulated expression of some neuron projection proteins involved in the response to drug and nervous system development. The dopaminergic synapse pathway was found to be the most significant DEP in the combined analysis of the KEGG and BATMAN-TCM databases. Based on the results of the STRING analysis, oxidative stress (OS), calcium binding protein regulation, vascularization, and energy metabolism were important in the rhubarb therapeutic process.

CONCLUSION

Rhubarb achieves its effects mainly through the dopaminergic synapse pathway in ICH treatment. The ICH-treating mechanisms of rhubarb may also involve anti-OS, calcium binding protein regulation, angiogenic regulation, and energy metabolism improvement. This study adds new evidence to clinical applications of rhubarb for ICH.

Maltol Mitigates Thioacetamide-induced Liver Fibrosis through TGF-β1-mediated Activation of PI3K/Akt Signaling Pathway

Our previous study has confirmed that maltol can attenuate alcohol-induced acute hepatic damage and prevent oxidative stress in mice. Therefore, maltol might have the capacity to improve thioacetamide (TAA)-induced liver fibrosis. The purpose of this work was to explore the antifibrotic efficacy and underlying mechanisms of maltol for TAA-treated mice. Progressive liver fibrosis was established with a dose-escalating protocol in which the mice received TAA intraperitoneal three times a week for a total duration of 9 weeks. The injection doses of TAA were 50 mg/kg for the first week, 100 mg/kg for the second and third weeks, and 150 mg/kg for the rest of the injections. Maltol with doses of 50 and 100 mg/kg was given by gavage after 4 weeks of intraperitoneal injection of TAA, respectively, once daily for 5 weeks. Results indicated that TAA intraperitoneal injection significantly increased serum activities of alanine aminotransferase (ALT) (52.93 ± 13.21 U/L vs 10.22 ± 3.36 U/L) and aspartate aminotransferase (AST) (67.58 ± 25.84 U/L vs 39.34 ± 3.89 U/L); these elevations were significantly diminished by pretreatment with maltol. Additionally, maltol ameliorated TAA-induced oxidative stress with attenuation in MDA ( p < 0.05 or p < 0.01) content; evident elevation in the GSH levels, GSH/GSSG ratio ( p < 0.05 or p < 0.01), and superoxide dismutase (SOD) ( p < 0.01); and restored liver histology accompanied by a decrease of α-smooth muscle actin (α-SMA) expression. Furthermore, maltol significantly suppressed the transforming growth factor-β1 (TGF-β1) expression and the PI3K/Akt pathway. This study suggested that maltol alleviated experimental liver fibrosis by suppressing the activation of HSCs and inducing apoptosis of activated HSCs through TGF-β1-mediated PI3K/Akt signaling pathway. These findings further clearly suggested that maltol is a potent therapeutic candidate for the alleviation of liver fibrosis.

TGF-β1 down-regulation in the mediobasal hypothalamus attenuates hypothalamic inflammation and protects against diet-induced obesity

BACKGROUND

The consumption of large amounts of dietary fats induces hypothalamic inflammation and impairs the function of the melanocortin system, leading to a defective regulation of caloric intake and whole-body energy expenditure. In mice fed a high-fat diet (HFD), TGF-β1 expression was increased and NF-κB signaling was activated in proopiomelanocortin neurons, which plays an important role in the obesity-associated hypothalamic inflammation scenario. However, whether excessive hypothalamic TGF-β1 impairs energy homeostasis remains unclear.

OBJECTIVES

We aimed to investigate the role of diet-induced hypothalamic TGF-β1 on inflammation and whole-body energy homeostasis.

METHODS

A TGF-β1 inhibitory lentiviral shRNA particle was stereotaxically injected bilaterally in the arcuate nucleus (ARC) of C57BL/6 mice fed a HFD. We assessed changes in body mass and adiposity, food intake, inflammatory markers, and the function of energy and glucose metabolism.

RESULTS

TGF-β1 down-regulation in the ARC-attenuated body-mass gain, reduced fat-mass accumulation, decreased hypothalamic inflammatory markers, and protected against HFD-induced lipohypertrophy of brown adipose tissue. In addition, the inhibition of hypothalamic TGF-β1 increased the locomotor activity and improved whole-body lipid metabolism, which attenuated hepatic fat accumulation and serum triglyceride levels. No changes were observed in food intake and glucose homeostasis.

CONCLUSION

Hypothalamic TGF-β1 down-regulation attenuates hypothalamic inflammation and improves energy metabolism, resulting in lower body-mass gain and lower fat-mass accumulation, which protects mice from the development of obesity. Our data suggest that modulation of hypothalamic TGF-β1 expression might be an effective strategy to treat obesity.

Role of proteoglycans in neuro-inflammation and central nervous system fibrosis

Fibrosis is defined as the thickening and scarring of connective tissue, usually as a consequence of tissue damage. The central nervous system (CNS) is special in the sense that fibrogenic cells are restricted to vascular and meningeal areas. Inflammation and the disruption of the blood-brain barrier can lead to the infiltration of fibroblasts and trigger fibrotic response. While the initial function of the fibrotic tissue is to restore the blood-brain barrier and to limit the site of injury, it also demolishes the structure of extracellular matrix and impedes the healing process by producing inhibitory molecules and forming a physical and biochemical barrier that prevents axon regeneration. As a major constituent in the extracellular matrix, proteoglycans participate in the neuro-inflammation, modulating the fibrotic process. In this review, we will discuss the pathophysiology of fibrosis during acute injuries of the CNS, as well as during chronic neurodegenerative conditions such as Alzheimer's disease, Parkinson's disease, multiple sclerosis and age-related neurodegeneration with focus on the functional roles of proteoglycans.

Nestin-expressing cell types in the temporal lobe and hippocampus: Morphology, differentiation, and proliferative capacity

Nestin is expressed in immature neuroepithelial and progenitor cell types and transiently upregulated in proliferative neuroglial cells responding to acute brain injury, including following seizures. In 36 temporal lobe (TLobe) specimens from patients with TLobe epilepsy (age range 8-60 years) we studied the number, distribution and morphology of nestin-expressing cells (NEC) in the pes, hippocampus body, parahippocampal gyrus, amygdala, temporal cortex and pole compared with post mortem control tissues from 26 cases (age range 12 gestational weeks to 76 years). The proliferative fraction of NEC was evaluated in selected regions, including recognized niches, using MCM2. Their differentiation was explored with neuronal (DCX, mushashi, βIII tubulin, NeuN) and glial (GFAP, GFAPdelta, glutamine synthetase, aquaporin4, EAAT1) markers, both in sections or following culture. Findings were correlated with clinical parameters. A stereotypical pattern in the distribution and morphologies of NEC was observed, reminiscent of patterns in the developing brain, with increased densities in epilepsy than adult controls (p < .001). Findings included MCM2-positive radial glial-like cells in the periventricular white matter and rows of NEC in the hippocampal fimbria and sulcus. Nestin cells represented 29% of the hippocampal proliferative fraction in epilepsy cases; 20% co-expressed βIII tubulin in culture compared with 28% with GFAP. Significant correlations were noted between age at surgery, memory deficits and nestin populations. TLobe NEC with ongoing proliferative capacity likely represent vestiges of developmental migratory streams and resident reactive cell populations of potential relevance to hippocampal epileptogenesis, TLobe pathology, and co-morbidities, including memory decline.

Radiation suppresses neointimal hyperplasia through affecting proliferation and apoptosis of vascular smooth muscle cells

PURPOSE

To study the effect of x-ray radiotherapy on vascular smooth muscle cells (VSMCs) and elucidate the mechanisms in preventing neointimal hyperplasia of prosthetic vascular grafts.

MATERIALS AND METHODS

In model I, twelve mongrel dogs underwent revascularization with prosthetic grafts and half the dogs underwent irradiation of the grafts at 28 Gy. In model II, human VSMCs (hVSMCs) were maintained and divided into six groups to which external radiation was applied at six different doses: 0 Gy, 2 Gy, 8 Gy, 16 Gy, 24 Gy and 30 Gy. In both models, specimens were harvested and examined by using morphological, immunological, cellular and molecular methods.

RESULTS

After irradiation, the neointima thickness was significantly lower in irradiated groups (p≤0.01). The radiotherapy could up-regulate p27^kip1, and down-regulate proliferating cell nuclear antigen (PCNA) and S phase kinase associated protein 2 (Skp2). X-ray irradiation inhibits the proliferation of hVSMCs via acting on G1/S phase of cell cycle. The apoptosis of hVSMCs increased significantly with dose and time. The expression of PCNA and Skp2 were decreased after a first increasing trend with dose, but had a significant negative correlation with time. The expression of p27^kip1 had a significant positive correlation with dose and time.

CONCLUSIONS

Postoperative external fractionated irradiation after prosthetic vessel replacement of the abdominal aorta suppressed the development of hyperplasia in the graft neointima in the short term. There was a prominent time- and dose-dependent inhibition of VSMC proliferation by radiation when it was administered.

Autophagy protein LC3 regulates the fibrosis of hypertrophic scar by controlling Bcl-xL in dermal fibroblasts

Hypertrophic scar (HS) is a serious skin fibrotic disease characterized by excessive hypercellularity and extracellular matrix (ECM) component deposition. Autophagy is a tightly regulated physiological process essential for cellular maintenance, differentiation, development and homeostasis. However, during the formation of HS, whether and how autophagy is regulated in dermal fibroblasts are still far from elucidated. Here we detected the autophagic capacity in HS and normal skin (NS) counterparts, explored and verified the key regulatory molecules of autophagy in HS-derived fibroblasts (HSFs), and validated the data using rabbit ear scar model. Transmission electron microscopy (TEM) and immunostaining data showed that LC3-positive cells and autophagosomes in HS/HSFs were more intensive relative to those in NS/NSFs groups. Knockdown of LC3 (shLC3) could significantly block the expressionof type I collagen (Col 1, p < 0.01) and type III collagen (Col 3, p < 0.01) and thus inhibit the fibrosis of HSFs. shLC3 resistant to autophagy was shown to be Bcl-xL-, not Bcl-2-dependent, and silencing of Bcl-xL (sibcl-xL) significantly increased apoptosis of HSFs (p < 0.01). Immunofluorescence results showed that instead of inhibiting α-SMA protein expression, shLC3 could change its architecture arrangement in HSFs. sibcl-xL showed that Bcl-xL was a key signaling molecule involved in HSFs autophagy. More importantly, both shLC3 and sibcl-xL obviously improved the appearance and architecture of the rabbit ear scar, and reduced scar formation on the rabbit ear. Therefore, the aberration of LC3 protein processing compromised autophagy in HS might associate with its pathogenesis in wound repair. LC3 regulated HS fibrosis by controlling the expression of Bcl-xL in HSFs. Thus, Bcl-xL might serve as a potential molecular target, providing a novel strategy for HS therapy.

Isolation of Astrocytes Displaying Myofibroblast Properties and Present in Multiple Sclerosis Lesions

A wide heterogeneity of lesions can affect the central nervous system (CNS). In all situations where neurons are damaged, including multiple sclerosis (MS), a common reactive astrocytosis is present. Sedimentation field-flow fractionation (SdFFF) was used to sort astrocyte subpopulations. After SdFFF elution, cells, prepared from rat newborn cortex, were cultured and analyzed by immunocytofluorescence for glial fibrillary acidic protein (GFAP) and α-smooth muscle (SM) actin (a specific marker for myofibroblasts) expression. Cell contractile capacity was studied. Samples from patients with MS were also analyzed. Three main fractions (F1, F2, and F3) were isolated and compared with the total eluted population (TP). TP, F1, F2, and F3, contained respectively 74, 96, 12, and 98% of GFAP expressing astrocytes. In F3, astrocytes only expressed GFAP while in F1, astrocytes expressed both GFAP and α-SM actin. In F2 and TP, α-SM actin expression was barely detected. F3-derived cells showed higher contractile capacities compared with F1-derived cells. In one specific case of MS known as Baló's concentric MS, astrocytes expressing both GFAP and α-SM actin were detected. Using SdFFF, a population of astrocytes presenting myofibroblast properties was isolated. This subpopulation of astrocytes was also observed in a MS sample suggesting that it could be involved in lesion formation and remodeling during CNS pathologies.

Honokiol Alleviates Hypertrophic Scar by Targeting Transforming Growth Factor-β/Smad2/3 Signaling Pathway

Hypertrophic scar (HPS) presents as excessive extracellular matrix deposition and abnormal function of fibroblasts. However, there is no single satisfactory method to prevent HPS formation so far. Here, we found that honokiol (HKL), a natural compound isolated from Magnolia tree, had an inhibitory effect on HPS both in vitro and in vivo. Firstly, HKL could dose-dependently down-regulate the mRNA and protein levels of type I collagen, type III collagen, and α-smooth muscle actin (α-SMA) in hypertrophic scar-derived fibroblasts (HSFs). Secondly, HKL suppressed the proliferation, migration abilities of HSFs and inhibited HSFs activation to myofibroblasts, but had no effect on cell apoptosis. Besides, the in vivo rabbit ear scar model further affirmed the inhibitory effects of HKL on collagen deposition, proliferating cell nuclear antigen and α-SMA. Finally, Western blot results showed that HKL reduced the phosphorylation status of Smad2/3, as well as affected the protein levels of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase1. Taken together, this study demonstrated that HKL alleviated HPS by suppressing fibrosis-related molecules and inhibiting HSFs proliferation, migration as well as activation to myofibroblasts via Smad-dependent pathway. Therefore, HKL could be used as a potential agent for treating HPS and other fibrotic diseases.

Curcumin inhibits glial scar formation by suppressing astrocyte-induced inflammation and fibrosis in vitro and in vivo

Spinal cord injury (SCI) leads to glial scar formation by astrocytes, which severely hinders neural regeneration. Curcumin (cur) can inhibit glial scar formation, but the underlying mechanism is not fully understood. Using both in vivo and in vitro experiments, the current study investigated the phenotypic transformation of astrocytes following cur and siRNA intervention during the processes of inflammation and fibrosis and determined details of the relationship between cur treatment and the glial scar components GFAP and CSPG. We found that cur and NF-κb p65 siRNA could inhibit astrocyte activation through suppressing NF-κb signaling pathway, which led to down-regulate the expression of chemokines MCP-1, RANTES and CXCL10 released by astrocytes and decreased macrophage and T-cell infiltration, thus reducing the inflammation in the glial scar. In addition, silencing SOX-9 may reduce the deposition of extracellular matrix CSPG; whereas its over-expression could increase the CSPG expression. Cur suppressedSOX-9-inducedCSPG deposition, reduced α-SMA (an important symbol of fibrosis) expression in astrocytes, altered astrocyte phenotype, and inhibited glial scar formation by regulating fibrosis. This study confirmed that cur could regulate both the NF-κb and SOX9 signaling pathways and reduce the expression of intracellular and extracellular glial scar components through dual-target regulating both inflammation and fibrosis after SCI in the rat. This study provides an important hypothesis centered on the dual inhibition of intracellular and extracellular glial scar components as a treatment strategy for SCI.

Alpha-Smooth Muscle Actin mRNA and Protein Are Increased in Isolated Brain Vessel Extracts of Alzheimer Mice

Alzheimer's disease (AD) is a severe neurodegenerative disorder of the brain, characterized by extracellular beta-amyloid (Aβ) plaques, intracellular tau pathology, neurodegeneration and inflammation. There is clear evidence that the blood-brain barrier is damaged in AD and that vessel function is impaired. Alpha-smooth muscle actin (αSMA) is a prominent protein expressed on brain vessels, especially in cells located closer to the arteriole end of the capillaries, which possibly influences the blood vessel contraction. The aim of the present study was to observe αSMA protein and mRNA expression in isolated brain vessel extracts and cortex in an Alzheimer mouse model with strong Aβ plaque deposition. Our data revealed a prominent expression of αSMA protein in isolated brain vessel extracts of AD mice by Western blot analysis. Immunostaining showed that these vessels were associated with Aβ plaques. Quantitative real-time PCR analysis confirmed this increase at the mRNA expression level and showed a significant increase of transforming growth factor beta-1 mRNA expression in AD mice. In situ hybridization demonstrated a strong expression pattern of αSMA mRNA in the whole cortex and hippocampus. In conclusion, our data provide evidence that αSMA protein and mRNA are enhanced in vessels in an AD mouse model, possibly counteracting vessel malfunction in AD.

Cells transplanted onto the surface of the glial scar reveal hidden potential for functional neural regeneration

Cell transplantation therapy has long been investigated as a therapeutic intervention for neurodegenerative disorders, including spinal cord injury, Parkinson's disease, and amyotrophic lateral sclerosis. Indeed, patients have high hopes for a cell-based therapy. However, there are numerous practical challenges for clinical translation. One major problem is that only very low numbers of donor cells survive and achieve functional integration into the host. Glial scar tissue in chronic neurodegenerative disorders strongly inhibits regeneration, and this inhibition must be overcome to accomplish successful cell transplantation. Intraneural cell transplantation is considered to be the best way to deliver cells to the host. We questioned this view with experiments in vivo on a rat glial scar model of the auditory system. Our results show that intraneural transplantation to the auditory nerve, preceded by chondroitinase ABC (ChABC)-treatment, is ineffective. There is no functional recovery, and almost all transplanted cells die within a few weeks. However, when donor cells are placed on the surface of a ChABC-treated gliotic auditory nerve, they autonomously migrate into it and recapitulate glia- and neuron-guided cell migration modes to repair the auditory pathway and recover auditory function. Surface transplantation may thus pave the way for improved functional integration of donor cells into host tissue, providing a less invasive approach to rescue clinically important neural tracts.

Effects of the Four-Herb Compound ANBP on Wound Healing Promotion in Diabetic Mice

Wound healing is a troublesome problem in diabetic patients. Besides, there is also an increased risk of postsurgical wound complications for diabetic patient. It has been revealed that traditional Chinese medicine may promote healing and inhibit scar formation, while the changes of morphology and physiology of wounds on such medicine treatment still remain elusive. In this study, we first used the ultralow temperature preparation method to produce mixed superfine powder from Agrimonia pilosa (A), Nelumbo nucifera (N), Boswellia carteri (B), and Pollen typhae (P), named as ANBP. Applying ANBP on 40 streptozotocin (STZ)-induced diabetic C57BL/6 mice (4-6 weeks, 20 ± 2 g), we observed that the wound healing process was accelerated and the wound healing time was shortened (14 days, P < .05). Pathological observation using hematoxylin-eosin staining indicated that inflammatory cells were reduced (P < .05) while the thickness of granulation tissue and length of epithelial tongue were increased (P < .05). The vascular density was increased on 7 and 14 days after ANBP treatment. Masson and Sirius red staining showed that, at the early stage of trauma, the expressions of Col I and Col III, especially Col III, were increased in the ANBP group (P < .05). Studies in vitro demonstrated that tubular formation was significantly increased after ANBP treatment on human vascular endothelial cells in a dose-dependent way. Taken together, our studies revealed that ANBP treatment could accelerate wound healing, promote vascularization, and inhibit inflammation, suggesting the potential clinic application of ANBP for diabetes mellitus and refractory wounds.

Loureirin B inhibits fibroblast proliferation and extracellular matrix deposition in hypertrophic scar via TGF-β/Smad pathway

The ethanolic extract of Resina Draconis (RDEE) has been reported beneficial to normal wound healing yielding more regularly arranged collagen fibres. Loureirin B, a major component in RDEE, has been supposed to be effective on the prevention and treatment of pathological scars. To investigate the therapeutic effects of loureirin B on hypertrophic scar (HS), fibroblasts from human HS and normal skin (NS) were isolated. Results showed that loureirin B dose-dependently downregulated both mRNA and protein levels of type I collagen (ColI), type III collagen (ColIII) and α-smooth muscle actin (α-SMA) in HS fibroblasts. Loureirin B also suppressed fibroblast proliferative activity and redistributed cell cycle, but did not affect cell apoptosis. In vivo rabbit ear scar model, loureirin B significantly improved the arrangement and deposition of collagen fibres, decreased protein levels of ColI, ColIII and α-SMA and suppressed myofibroblast differentiation and scar proliferative activity. In NS fibroblasts, loureirin B effectively inhibited TGF-β1-induced upregulation of ColI, ColIII and α-SMA levels, myofibroblast differentiation and the activation of Smad2 and Smad3. Loureirin B also affected mRNA levels of major MMPs and TIMPs in TGF-β1-stimulated fibroblasts. Taken together, this study demonstrates that loureirin B could downregulate the expression of fibrosis-related molecules by regulating MMPs and TIMPs levels, inhibit scar fibroblast proliferation and suppress TGF-β1-induced fibrosis, during which TGF-β1/Smad2/3 pathway is likely involved. These findings suggest that loureirin B is a potential therapeutic compound for HS treatment.

4R-cembranoid protects against diisopropylfluorophosphate-mediated neurodegeneration

Many organophosphorous esters synthesized for applications in industry, agriculture, or warfare irreversibly inhibit acetylcholinesterase, and acute poisoning with these compounds causes life-threatening cholinergic overstimulation. Following classical emergency treatment with atropine, an oxime, and a benzodiazepine, surviving victims often suffer brain neurodegeneration. Currently, there is no pharmacological treatment to prevent this brain injury. Here we show that a cyclic diterpenoid, (1S,2E,4R,6R,7E,11E)-cembra-2,7,11-triene-4,6-diol (4R) ameliorates the damage caused by diisopropylfluorophosphate (DFP) in the hippocampal area CA1. DFP has been frequently used as a surrogate for the warfare nerve agent sarin. In rats, DFP is lethal at the dose used to cause brain damage. Therefore, to observe brain damage in survivors, the death rate was reduced by pre-administration of the peripherally acting antidotes pyridostigmine and methyl atropine or its analog ipratropium. Pyridostigmine bromide, methyl atropine nitrate, and ipratropium bromide were dissolved in saline and injected intramuscularly at 0.1mg/kg, 20mg/kg, and 23mg/kg, respectively. DFP (9mg/kg) dissolved in cold water was injected intraperitoneally. 4R (6mg/kg) dissolved in DMSO was injected subcutaneously, either 1h before or 5 or 24h after DFP. Neurodegeneration was assessed with Fluoro-Jade B and amino cupric silver staining; neuroinflammation was measured by the expression of nestin, a marker of activated astrocytes. Forty-eight hours after DFP administration, 4R decreased the number of dead neurons by half when injected before or after DFP. 4R also significantly decreased the number of activated astrocytes. These data suggest that 4R is a promising new drug that could change the therapeutic paradigm for acute poisoning with organophosphorous compounds by the implementation of a second-stage intervention after the classical countermeasure treatment.

Activation of the TRPV1 cation channel contributes to stress-induced astrocyte migration

Astrocytes provide metabolic, structural, and synaptic support to neurons in normal physiology and also contribute widely to pathogenic processes in response to stress or injury. Reactive astrocytes can undergo cytoskeletal reorganization and increase migration through changes in intracellular Ca(2+) mediated by a variety of potential modulators. Here we tested whether migration of isolated retinal astrocytes following mechanical injury (scratch wound) involves the transient receptor potential vanilloid-1 channel (TRPV1), which contributes to Ca(2+)-mediated cytoskeletal rearrangement and migration in other systems. Application of the TRPV1-specific antagonists, capsazepine (CPZ) or 5'-iodoresiniferatoxin (IRTX), slowed migration by as much as 44%, depending on concentration. In contrast, treatment with the TRPV1-specific agonists, capsaicin (CAP) or resiniferatoxin (RTX) produced only a slight acceleration over a range of concentrations. Chelation of extracellular Ca(2+) with EGTA (1 mM) slowed astrocyte migration by 35%. Ratiometric imaging indicated that scratch wound induced a sharp 20% rise in astrocyte Ca(2+) that dissipated with distance from the wound. Treatment with IRTX both slowed and dramatically reduced the scratch-induced Ca(2+) increase. Both CPZ and IRTX influenced astrocyte cytoskeletal organization, especially near the wound edge. Taken together, our results indicate that astrocyte mobilization in response to mechanical stress involves influx of extracellular Ca(2+) and cytoskeletal changes in part mediated by TRPV1 activation.

A spatiotemporal study of gliosis in relation to depth electrode tracks in drug-resistant epilepsy

Key questions remain regarding the processes governing gliogenesis following central nervous system injury that are critical to understanding both beneficial brain repair mechanisms and any long-term detrimental effects, including increased risk of seizures. We have used cortical injury produced by intracranial electrodes (ICEs) to study the time-course and localization of gliosis and gliogenesis in surgically resected human brain tissue. Seventeen cases with ICE injuries of 4–301 days age were selected. Double-labelled immunolabelling using a proliferative cell marker (MCM2), markers of fate-specific transcriptional factors (PAX6, SOX2), a microglial marker (IBA1) and glial markers (nestin, GFAP) was quantified in three regions: zone 1 (immediate vicinity: 0–350 μm), zone 2 (350–700 μm) and zone 3 (remote ≥2000 μm) in relation to the ICE injury site. Microglial/macrophage cell densities peaked at 28–30 days post-injury (dpi) with a significant decline in proliferating microglia with dpi in all zones. Nestin-expressing cells (NECs) were concentrated in zones 1 and 2, showed the highest regenerative capacity (MCM2 and PAX6 co-expression) and were intimately associated with capillaries within the organizing injury cavity. There was a significant decline in nestin/MCM2 co-expressing cells with dpi in zones 1 and 2. Nestin-positive fibres remained in the chronic scar, and NECs with neuronal morphology were noted in older injuries. GFAP-expressing glia were more evenly distributed between zones, with no significant decline in density or proliferative capacity with dpi. Colocalization between nestin and GFAP in zone 1 glial cells decreased with increasing dpi. In conclusion, NECs at acute injury sites are a proliferative, transient cell population with capacity for maturation into astrocytes with possible neuronal differentiation observed in older injuries.

Dual role of Response gene to complement-32 in multiple sclerosis

Response gene to complement (RGC)-32 is a novel molecule that plays an important role in cell proliferation. We investigated the expression of RGC-32 in multiple sclerosis (MS) brain and in peripheral blood mononuclear cells (PBMCs) obtained from patients with relapsing-remitting multiple sclerosis. We found that CD3(+), CD68(+), and glial fibrillar acidic protein (GFAP)(+) cells in MS plaques co-localized with RGC-32. Our results show a statistically significant decrease in RGC-32 mRNA expression in PBMCs during relapses when compared to the levels in stable MS patients. This decrease might be useful in predicting disease activity in patients with relapsing-remitting MS. RGC-32 expression was also correlated with that of FasL mRNA during relapses. FasL mRNA expression was significantly reduced after RGC-32 silencing, indicating a role for RGC-32 in the regulation of FasL expression. In addition, the expression of Akt1, cyclin D1, and IL-21 mRNA was significantly increased during MS relapses when compared to levels in healthy controls. Furthermore, we investigated the role of RGC-32 in TGF-β-induced extracellular matrix expression in astrocytes. Blockage of RGC-32 using small interfering RNA significantly inhibits TGF-β induction of procollagen I, fibronectin and of the reactive astrocyte marker α-smooth muscle actin (α-SMA). Our data suggest that RGC-32 plays a dual role in MS, both as a regulator of T-cells mediated apoptosis and as a promoter of TGF-β-mediated profibrotic effects in astrocytes.

The neuroprotective functions of transforming growth factor beta proteins

Transforming growth factor beta (TGF-β) proteins are multifunctional cytokines whose neural functions are increasingly recognized. The machinery of TGF-β signaling, including the serine kinase type transmembrane receptors, is present in the central nervous system. However, the 3 mammalian TGF-β subtypes have distinct distributions in the brain suggesting different neural functions. Evidence of their involvement in the development and plasticity of the nervous system as well as their functions in peripheral organs suggested that they also exhibit neuroprotective functions. Indeed, TGF-β expression is induced following a variety of types of brain tissue injury. The neuroprotective function of TGF-βs is most established following brain ischemia. Damage in experimental animal models of global and focal ischemia was shown to be attenuated by TGF-βs. In addition, support for their neuroprotective actions following trauma, sclerosis multiplex, neurodegenerative diseases, infections, and brain tumors is also accumulating. The review will also describe the potential mechanisms of neuroprotection exerted by TGF-βs including anti-inflammatory, -apoptotic, -excitotoxic actions as well as the promotion of scar formation, angiogenesis, and neuroregeneration. The participation of these mechanisms in the neuroprotective effects of TGF-βs during different brain lesions will also be discussed.

Nestin overexpression precedes caspase-3 upregulation in rats exposed to controlled cortical impact traumatic brain injury

Our understanding of biological mechanisms and treatment options for traumatic brain injury (TBI) is limited. Here, we employed quantitative real-time PCR (QRT-PCR) and immunohistochemical analyses to determine the dynamic expression of cell proliferation and apoptosis in an effort to provide insights into the therapeutic window for developing regenerative strategies for TBI. For this purpose, young adult Sprague-Dawley rats were subjected to experimental TBI using a controlled cortical impactor, then euthanized 1-48 hours after TBI for QRT-PCR and immunohistochemistry. QRT-PCR revealed that brains from TBI exposed rats initially displayed nestin mRNA expression that modestly increased as early as 1-hour post-TBI, then significantly peaked at 8 hours, but thereafter reverted to pre-TBI levels. On the other hand, caspase-3 mRNA expression was slightly elevated at 8 hours post-TBI, which did not become significantly upregulated until 48 hours. Immunofluorescent microscopy revealed a significant surge in nestin immunoreactive cells in the cortex, corpus callosum, and subventricular zone at 24 hours post-TBI, whereas a significant increase in the number of active caspase-3 immunoreactive cells was only found in the cortex and not until 48 hours. These results suggest that the injured brain attempts to repair itself via cell proliferation immediately after TBI, but that this endogenous regenerative mechanism is not sufficient to abrogate the secondary apoptotic cell death. Treatment strategies designed to amplify cell proliferation and to prevent apoptosis are likely to exert maximal benefits when initiated at the acute phase of TBI.

Insights into intermediate filament regulation from development to ageing

Intermediate filament (IF) proteins comprise a large family with more than 70 members. Initially, IFs were assumed to provide only structural reinforcement for the cell. However, IFs are now known to be dynamic structures that are involved in a wide range of cellular processes during all stages of life, from development to ageing, and during homeostasis and stress. This Commentary discusses some lesser-known functional and regulatory aspects of IFs. We specifically address the emerging roles of nestin in myogenesis and cancer cell migration, and examine exciting evidence on the regulation of nestin and lamin A by the notch signalling pathway, which could have repercussions for our understanding of the roles of IF proteins in development and ageing. In addition, we discuss the modulation of the post-translational modifications of neuronally expressed IFs and their protein-protein interactions, as well as IF glycosylation, which not only has a role in stress and ageing, but might also regulate IFs during development. Although many of these recent findings are still preliminary, they nevertheless open new doors to explore the functionality of the IF family of proteins.

Different collagen types define two types of idiopathic epiretinal membranes

AIMS

To identify differences in extracellular matrix contents between idiopathic epiretinal membranes (IEM) of cellophane macular reflex (CMRM) or preretinal macular fibrosis (PMFM) type.

METHODS AND RESULTS

Idiopathic epiretinal membranes were analysed by light and quantitative transmission electron microscopy, immunohistochemistry and Western blotting. Substantial differences between CMRM and PMFM were observed regarding the nature of extracellular fibrils. In CMRM the fibrils were thin, with diameters between 6 and 15 nm. Between the fibrils, aggregates of long-spacing collagen were observed. In PMFM the diameters of fibrils measured either 18-26 or 36-56 nm. Using immunogold electron microscopy, 6-15 nm fibrils in CMRM were labelled for collagen type VI, while the fibrils in PMFM remained unstained. Using Western blotting and immunohistochemistry, a strong signal for collagen type VI was observed in all CMRM, while immunoreactivity was weak or absent in PMFM. In contrast, PMFM showed immunoreactivity for collagen types I and II, which was weak or absent in CMRM. Both types of membranes showed immunoreactivity for collagen types III and IV, laminin and fibronectin with similar intensity.

CONCLUSION

The presence of high amounts of collagen type VI in CMRM and the relative absence of collagen types I and II is the major structural difference to PMFM.

Neuro-muscular differentiation of adult porcine skin derived stem cell-like cells

Background

Due to the genetic relationship to humans, porcine stem cells are a very important model system to investigate cell differentiation, associated cell signaling pathways, and cell fate. Porcine skin derived stem cells have been isolated from mid-gestation porcine fetus recently. To our knowledge, stem cells from the skin of the adult porcine organism have not been isolated until now. Hence, to our knowledge, we here describe the isolation, expansion, characterization and differentiation of multipotent porcine skin derived stem cell-like cells (pSSCs) from the adult porcine organism for the first time.

Methodology/Principal Findings

pSSCs had a spindle shaped morphology similar to mesenchymal stem cells (MSCs). They could be maintained proliferatively active in vitro for more than 120 days and were able to form colonies from single cells. pSSCs expressed Sox2 and Oct3/4, both transcription factors essential to the pluripotent and self-renewing phenotypes of embryonic stem cells, which recently gained attention due to their function in inducing pluripotent stem cells. Furthermore, the expression of the progenitor marker nestin, the somatic stem cell markers Bcrp1/ABCG2, Bmi1, and Stat3 was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in undifferentiated pSSCs. Flow cytometry revealed the expression of the MSC related proteins CD9, CD29, CD44 and CD105, but not CD90. After neuronal differentiation cells with a characteristic morphology of neuronal and smooth muscle-like cells were present in the cultures. Subsequent immunochemistry and flow cytometry revealed the down-regulation of nestin and the up-regulation of the neuron specific protein beta-III-tubulin and the astrocyte marker GFAP. Also, alpha-SMA expressing cells increased during differentiation suggesting the neuro-muscular differentiation of these skin derived cells. pSSCs could also be induced to differentiate into adipocyte-like cells when cultured under specific conditions.

Conclusions/Significance

Adult porcine skin harbors a population of stem cell-like cells (pSSCs) that can be isolated via enzymatic digestion. These pSSCs show characteristic features of MSCs originated in other tissues and express the embryonic stem cell marker Oct3/4, Sox2, and Stat3. Furthermore, pSSCs have the potential to differentiate into cells from two different germ lines, the ectoderm (neurons, astrocytes) and the mesoderm (smooth muscle cells, adipocytes).

Mechanically induced reactive gliosis causes ATP-mediated alterations in astrocyte stiffness

Reactive gliosis is a process triggered in astrocytes after traumatic injury, yet the exact consequences of gliosis on cellular survival and neural regenerative processes in the injured brain remain only partly understood. One recently discovered feature influencing neuronal growth and differentiation is the physical stiffness of the environment surrounding pioneering neurites. In this study, the mechanical properties of cultured cortical astrocytes are measured following a mechanical stretch injury that induces reactive gliosis. In mechanically injured cultures, there was a significant increase in glial fibrillary acidic protein (GFAP) immunoreactivity 24 h following a rapid, transient 15% strain. In these same cultures, astrocytes in the surrounding region--the "mechanical penumbra"--also exhibited increased GFAP immunoreactivity compared to naive cultures. Correlated with these changes in GFAP was a general softening of the non-nuclear regions of the astrocytes, both in the injured and penumbra cells, as measured by atomic force microscopy (AFM). The elastic modulus in naive cultures was observed to be 57.7+/-5.8 kPa in non-nuclear regions of naive cultures, while 24 h after injury the modulus was observed to be 26.4+/-4.9 kPa in the same region of injured cells. In the penumbra of injured cultures, the modulus was 23.7+/-3.6 kPa. Alterations in astrocyte stiffness in the area of injury and mechanical penumbra were ameliorated by pretreating cultures with a nonselective P2 receptor antagonist (PPADS). Since neuronal cells generally prefer softer substrates for growth and neurite extension, these findings may indicate that the mechanical characteristics of reactive astrocytes are favorable for neuronal recovery after traumatic brain injury.