Glia Activation Research Articles

CSF Levels of CXCL12 and Osteopontin as Early Markers of Primary Progressive Multiple Sclerosis

Background and ObjectivesTo evaluate the extent of intrathecal inflammation in patients with primary progressive MS (PPMS) at the time of diagnosis and to define markers and a specific inflammatory profile capable of distinguishing progressive from relapsing-remitting multiple sclerosis (RRMS).MethodsLevels of 34 pro- and anti-inflammatory cytokines and chemokines in the CSF were evaluated at the diagnosis in 16 patients with PPMS and 80 with RRMS. All patients underwent clinical evaluation, including Expanded Disability Status Scale assessment and a 3T brain MRI to detect white matter and cortical lesion number and volume and global and regional cortical thickness.ResultsHigher levels of CXCL12 (odds ratio [OR] = 3.97, 95% CI [1.34–11.7]) and the monocyte-related osteopontin (OR = 2.24, 95% CI [1.01–4.99]) were detected in patients with PPMS, whereas levels of interleukin-10 (IL10) (OR = 0.28, 95% CI [0.09–0.96]) were significantly increased in those with RRMS. High CXCL12 levels were detected in patients with increased gray matter lesion number and volume (p = 0.001, r = 0.832 and r = 0.821, respectively). Pathway analysis confirmed the chronic inflammatory processes occurring in PPMS.ConclusionsAt the time of diagnosis, a specific CSF protein profile can recognize the presence of early intrathecal inflammatory processes, possibly stratifying PPMS with respect to RRMS. Elevated CSF levels of CXCL12 and osteopontin suggested a key role of brain innate immunity and glia activity in MS. These molecules could represent useful candidate markers of MS progression, with implications for the pathogenesis and treatment of progressive MS.Classification of EvidenceThis study provides Class III evidence that CXCL12 and monocyte-related osteopontin may be correlated with PPMS, and IL-10 may be related to RRMS. It is may be correlated due to Bonferroni correction negating the statistical correlations found in the study.

Electroacupuncture Improves M2 Microglia Polarization and Glia Anti-inflammation of Hippocampus in Alzheimer's Disease.

Background: Alzheimer’s disease (AD) is a neurodegenerative disease characterized by loss of recognition and memory. Neuroinflammation plays pivotal roles in the pathology of AD and affects the progression of the disease. Astrocyte and microglia, as main immune executors in the central nervous system (CNS), participate into the inflammatory response in AD. Glia polarize into different phenotypes during neurodegeneration. Pro-inflammatory glia produce cytokines (IL-1β, TNF-α, and IL-6) resulting into debris aggregates and neurotoxicity. Anti-inflammatory phenotypes produce cytokines (IL-4 and IL-10) to release the inflammation. Electroacupuncture is a useful treatment that has been found to slow the neurodegeneration in animals through experimentation and in humans through clinical trials. The aim of this study was to uncover the mechanisms of glia activation, microglia polarization, and cytokine secretion regulated by electroacupuncture as a treatment for AD.Methods: Twenty male Sprague–Dawley (SD) rats were randomly divided into four groups: Control group (Control), Normal saline group (NS), AD group (AD), and Electroacupuncture group (Acupuncture). The AD and Acupuncture groups were bilaterally injected with Aβ1–42 into the CA1 field of the hippocampus. The Acupuncture group received electroacupuncture stimulation on the acupoint “Baihui” (GV20) for 6 days per week for a total of 3 weeks. The Morris Water Maze (MWM) was used to evaluate learning and memory capacity. Immunofluorescence was used to stain GFAP and Iba1 of the DG and CA1 in the hippocampus, which, respectively, expressed the activation of astrocyte and microglia. The M1 microglia marker, inducible nitric oxide synthase (iNOS), and M2 marker Arginase 1 (Arg1) were used to analyze the polarization of microglia. The pro-inflammatory cytokines (IL-1β, TNF-α, and IL-6), anti-inflammatory cytokines (IL-4 and IL-10), and pathway-molecules (p65 and Stat6) were tested to analyze the glia inflammatory response by immunofluorescence and polymerase chain reaction (PCR).Results: The MWM results showed that electroacupuncture improves the escape latency time and the swimming distance of AD rats. The number of GFAP and Iba1 cells significantly increased in AD rats, but electroacupuncture decreased the cells. The iNOS-positive cells were significantly increased in AD, and electroacupuncture decreased the positive cells. Electroacupuncture elevated Arg1-positive cells in AD rats. Electroacupuncture decreased the glia pro-inflammatory cytokine expression and increased the anti-inflammatory cytokine expression in AD rats. Furthermore, electroacupuncture inhibited the NF-κB pathway molecule (p65) while raising the Stat6 pathway molecule (Stat6).Conclusion: These results provide evidence that electroacupuncture improves the recognition abilities and memory of AD rats. Electroacupuncture inhibits the activation of glia and polarizes microglia toward the M2 phenotype. Electroacupuncture decreased the pro-inflammatory cytokines (IL-1β, TNF-α, and IL-6) and increased the anti-inflammatory cytokines (IL-4 and IL-10). Furthermore, electroacupuncture affects the immune responses through inhibition of NF-κB pathway but activation of Stat6 pathway.

PD01-11 SENSORY GLIAL GQ-GPCR SIGNALING ALLEVIATES VISCERAL PAIN AND IMPROVES MICTURITION FUNCTION IN AN ANIMAL MODEL OF UROLOGICAL CHRONIC PELVIC PAIN SYNDROME

You have accessJournal of UrologyInfections/Inflammation/Cystic Disease of the Genitourinary Tract: Interstitial Cystitis (PD01)1 Sep 2021PD01-11 SENSORY GLIAL GQ-GPCR SIGNALING ALLEVIATES VISCERAL PAIN AND IMPROVES MICTURITION FUNCTION IN AN ANIMAL MODEL OF UROLOGICAL CHRONIC PELVIC PAIN SYNDROME Alison Xie, Randall Meacham, and Anna Malykhina Alison XieAlison Xie More articles by this author , Randall MeachamRandall Meacham More articles by this author , and Anna MalykhinaAnna Malykhina More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000001965.11AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Patients with urological chronic pelvic pain syndrome (UCPPS) experience chronic pelvic pain (CPP) and lower urinary tract symptoms (LUTS). Afferent hypersensitivity in bladder-projecting sensory neurons plays an important role in the generation and maintenance of UCPPS symptoms, especially visceral pain and urinary frequency. We found that Gq-GPCR activation in satellite glial cells (SGCs) in the sensory ganglia decreases afferent sensitivity in lumbar nociceptive pathways, and could be a promising and highly innovative approach to alleviate the symptoms of bladder overactivity and pain. In this study, we aimed to test if activation of lumbosacral sensory glial Gq-GPCR signaling alleviates visceral pain, and improves LUTS in UCPPS mouse models. METHODS: A mouse model of UCPPS was induced by intravesical instillation of recombinant mouse vascular endothelial growth factor (VEGFA). VEGF levels were associated with CPP in UCPPS patients, and in animal models of bladder overactivity. In mice, VEGFA induces sensory nerve remodeling in the urinary bladder, visceral mechanical hypersensitivity. Pharmacogenetic activation of spinal and sensory ganglionic glia was achieved by expressing Gq-coupled Designer Receptors Exclusively Activated by Designer Drugs (Gq-DREADD) in GFAP+ glia via Gfap-hM3Dq transgenic mice or targeted adeno-associated viral vector (AAV) delivery. Gq-DREADD agonist, clozapine N-oxide (CNO), was used to selectively activate Gq-GPCR signaling in GFAP+ glia and to decreases sensory neuronal excitability in vivo in awake animals. Afferent sensitivity and bladder function were evaluated by clinically-relevant visceral nociceptive assays and awake cystometry. RESULTS: Lumbosacral glial Gq-GPCR activation significantly attenuated VEGFA-induced visceral hypersensitivity, increased micturition efficiency, and shortened intermicturition intervals. The glia-mediated neuromodulatory effects were long-lasting and dose-dependent, suggesting broader implication of neuromodulation in treating pain and hypersensitivity in pelvic diseases. CONCLUSIONS: Our data demonstrated that sensory glial-mediated neuromodulation effectively alleviated visceral pain and regulated micturition in animal model of UCPPS by inhibiting afferent excitability in the lumbosacral spinal cord and respective sensory ganglia. These results suggest a strong therapeutic potential of targeting GFAP-expressing glia for the treatment of chronic pelvic pain and LUTS in UCPPS patients. Source of Funding: Colorado Pilot Program Mentored Award, CCTSI, PI: Alison Xiaoqiao XieR01 DK121506-01, PI: Anna Malykhina © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e35-e35 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Alison Xie More articles by this author Randall Meacham More articles by this author Anna Malykhina More articles by this author Expand All Advertisement Loading ...

Hypothesis: Neuroglia Activation Due to Increased Peripheral and CNS Proinflammatory Cytokines/Chemokines with Neuroinflammation May Result in Long COVID

The COVID-19 pandemic has paralleled the great Spanish flu pandemic of 1918–1919 in the United States. Previous historical accounts have strongly suggested a post-viral syndrome and, currently, a post-COVID-19 viral syndrome is unquestionable, which shares many of the characteristics of myalgic encephalomyelitis/chronic fatigue syndrome that is present globally. The original term for this post-acute sequela of SARS-CoV-2 (PASC) was termed long haulers by those who were affected with this syndrome and it is now termed long COVID (LC) or PASC. International researchers and clinicians are desperately trying to better understand the pathobiological mechanisms possibly involved in this syndrome. This review aims to summarize many of the cumulated findings associated with LC/PASC and provides supportive and representative illustrations and transmission electron micrographic remodeling changes within brain tissues associated with a stress type of injury as occurs in the classic db/db and novel BTBR ob/ob obesity and diabetes mellitus mice models. These models are utilized to merely provide a response to metabolic stress injury wound healing mechanisms that are also present in humans. This review posits that neuroglial activation and chronic neuroinflammation may be a common denominator for the development of the complex LC/PASC syndrome following acute COVID-19 due to SARS-CoV-2.

Lipocalin 2 as a Putative Modulator of Local Inflammatory Processes in the Spinal Cord and Component of Organ Cross talk After Spinal Cord Injury.

Lipocalin 2 (LCN2), an immunomodulator, regulates various cellular processes such as iron transport and defense against bacterial infection. Under pathological conditions, LCN2 promotes neuroinflammation via the recruitment and activation of immune cells and glia, particularly microglia and astrocytes. Although it seems to have a negative influence on the functional outcome in spinal cord injury (SCI), the extent of its involvement in SCI and the underlying mechanisms are not yet fully known. In this study, using a SCI contusion mouse model, we first investigated the expression pattern of Lcn2 in different parts of the CNS (spinal cord and brain) and in the liver and its concentration in blood serum. Interestingly, we could note a significant increase in LCN2 throughout the whole spinal cord, in the brain, liver, and blood serum. This demonstrates the diversity of its possible sites of action in SCI. Furthermore, genetic deficiency of Lcn2 (Lcn2-/-) significantly reduced certain aspects of gliosis in the SCI-mice. Taken together, our studies provide first valuable hints, suggesting that LCN2 is involved in the local and systemic effects post SCI, and might modulate the impairment of different peripheral organs after injury.

Brain region specificity in reactive oxygen species production and maintenance of redox balance

The brain produces various reactive oxygen species in enzymatic and non-enzymatic reactions as a by-product of metabolism and/or for redox signaling. Effective antioxidant system in the brain cells maintains redox balance. However, neurons and glia from some brain regions are more vulnerable to oxidative stress in ischemia/reperfusion, epilepsy, and neurodegenerative disorders than the rest of the brain. Using fluorescent indicators in live cell imaging and confocal microscopy, we have measured the rate of cytosolic and mitochondrial reactive oxygen species production, lipid peroxidation, and glutathione levels in cortex, hippocampus, midbrain, brain stem and cerebellum in acute slices of rat brain. We have found that the basal rate of ROS production is at its highest in brain stem and cerebellum, and that it is mainly generated by glial cells. Activation of neurons and glia by glutamate and ATP led to maximal rates of ROS production in the midbrain compared to the rest of the brain. Mitochondrial ROS had only minor implication to the total ROS production with maximal values in the cortex and minimal in the midbrain. The basal rate of lipid peroxidation was higher in the midbrain and hippocampus, while the GSH level was similar in most brain regions with the lowest level in the midbrain. Thus, the rate of ROS production, lipid peroxidation and the level of GSH vary across brain regions.

NF-κB signaling contributes to the inhibitory effects of Bombyx batryticatus on neuroinflammation caused by MPTP toxicity

Bombyx batryticatus, the dried larvae of Bombyx mori infected by Beauveria bassiana, is a renowned traditional medicine. Previous report shows that B. batryticatus improved behavioral impairments, protected dopaminergic neurons, and maintained dopamine levels by inhibiting oxidative signaling in murine Parkinson’s disease model. In this study, the inhibitory effects of B. batryticatus on 1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson’s disease in mice was investigated and explored the corresponding molecular mechanisms, while focusing on NF-κB signaling. Consequently, it was found that B. batryticatus inhibited glial and microglial activation and the levels of neuroinflammatory mediators, such as Cox-2, iNOS, and NF-kB, in the substantia nigra pars compacta. Moreover, pre-inhibition of NF-κB by BAY 11-7082, a κB kinase inhibitor, could neutralize the inhibitory effects of B. batryticatus against the activation of glia and microglia formerly induced by MPTP. It can be considered that B. batryticatus holds implications in providing anti-inflammatory neuroprotection by regulating NF-κB signaling.

Glial glucose fuels the neuronal pentose phosphate pathway for long-term memory.

SummaryBrain function relies almost solely on glucose as an energy substrate. The main model of brain metabolism proposes that glucose is taken up and converted into lactate by astrocytes to fuel the energy-demanding neuronal activity underlying plasticity and memory. Whether direct neuronal glucose uptake is required for memory formation remains elusive. We uncover, in Drosophila, a mechanism of glucose shuttling to neurons from cortex glia, an exclusively perisomatic glial subtype, upon formation of olfactory long-term memory (LTM). In vivo imaging reveals that, downstream of cholinergic activation of cortex glia, autocrine insulin signaling increases glucose concentration in glia. Glucose is then transferred from glia to the neuronal somata in the olfactory memory center to fuel the pentose phosphate pathway and allow LTM formation. In contrast, our results indicate that the increase in neuronal glucose metabolism, although crucial for LTM formation, is not routed to glycolysis.

Critical Roles of Lysophospholipid Receptors in Activation of Neuroglia and Their Neuroinflammatory Responses.

Activation of microglia and/or astrocytes often releases proinflammatory molecules as critical pathogenic mediators that can promote neuroinflammation and secondary brain damages in diverse diseases of the central nervous system (CNS). Therefore, controlling the activation of glial cells and their neuroinflammatory responses has been considered as a potential therapeutic strategy for treating neuroinflammatory diseases. Recently, receptor-mediated lysophospholipid signaling, sphingosine 1-phosphate (S1P) receptor- and lysophosphatidic acid (LPA) receptor-mediated signaling in particular, has drawn scientific interest because of its critical roles in pathogenies of diverse neurological diseases such as neuropathic pain, systemic sclerosis, spinal cord injury, multiple sclerosis, cerebral ischemia, traumatic brain injury, hypoxia, hydrocephalus, and neuropsychiatric disorders. Activation of microglia and/or astrocytes is a common pathogenic event shared by most of these CNS disorders, indicating that lysophospholipid receptors could influence glial activation. In fact, many studies have reported that several S1P and LPA receptors can influence glial activation during the pathogenesis of cerebral ischemia and multiple sclerosis. This review aims to provide a comprehensive framework about the roles of S1P and LPA receptors in the activation of microglia and/or astrocytes and their neuroinflammatory responses in CNS diseases.

Modulation of Neuroinflammation by the Gut Microbiota in Prion and Prion-Like Diseases.

The process of neuroinflammation contributes to the pathogenic mechanism of many neurodegenerative diseases. The deleterious attributes of neuroinflammation involve aberrant and uncontrolled activation of glia, which can result in damage to proximal brain parenchyma. Failure to distinguish self from non-self, as well as leukocyte reaction to aggregation and accumulation of proteins in the CNS, are the primary mechanisms by which neuroinflammation is initiated. While processes local to the CNS may instigate neurodegenerative disease, the existence or dysregulation of systemic homeostasis can also serve to improve or worsen CNS pathologies, respectively. One fundamental component of systemic homeostasis is the gut microbiota, which communicates with the CNS via microbial metabolite production, the peripheral nervous system, and regulation of tryptophan metabolism. Over the past 10–15 years, research focused on the microbiota–gut–brain axis has culminated in the discovery that dysbiosis, or an imbalance between commensal and pathogenic gut bacteria, can promote CNS pathologies. Conversely, a properly regulated and well-balanced microbiome supports CNS homeostasis and reduces the incidence and extent of pathogenic neuroinflammation. This review will discuss the role of the gut microbiota in exacerbating or alleviating neuroinflammation in neurodegenerative diseases, and potential microbiota-based therapeutic approaches to reduce pathology in diseased states.

Therapeutic Effect of BDNF-Overexpressing Human Neural Stem Cells (F3.BDNF) in a Contusion Model of Spinal Cord Injury in Rats.

The most common type of spinal cord injury is the contusion of the spinal cord, which causes progressive secondary tissue degeneration. In this study, we applied genetically modified human neural stem cells overexpressing BDNF (brain-derived neurotrophic factor) (F3.BDNF) to determine whether they can promote functional recovery in the spinal cord injury (SCI) model in rats. We transplanted F3.BDNF cells via intrathecal catheter delivery after a contusion of the thoracic spinal cord and found that they were migrated toward the injured spinal cord area by MR imaging. Transplanted F3.BDNF cells expressed neural lineage markers, such as NeuN, MBP, and GFAP and were functionally connected to the host neurons. The F3.BDNF-transplanted rats exhibited significantly improved locomotor functions compared with the sham group. This functional recovery was accompanied by an increased volume of spared myelination and decreased area of cystic cavity in the F3.BDNF group. We also observed that the F3.BDNF-transplanted rats showed reduced numbers of Iba1- and iNOS-positive inflammatory cells as well as GFAP-positive astrocytes. These results strongly suggest the transplantation of F3.BDNF cells can modulate inflammatory cells and glia activation and also improve the hyperalgesia following SCI.

Glia-Driven Neuroinflammation and Systemic Inflammation in Alzheimer's Disease.

The neuroinflammatory hypothesis of Alzheimer’s disease (AD) was proposed more than 30 years ago. The involvement of the two main types of glial cells microglia and astrocytes, in neuroinflammation, was suggested early on. In this review, we highlight that the exact contributions of reactive glia to AD pathogenesis remain difficult to define, likely due to the heterogeneity of glia populations and alterations in their activation states through the stages of AD progression. In the case of microglia, it is becoming apparent that both beneficially and adversely activated cell populations can be identified at various stages of AD, which could be selectively targeted to either limit their damaging actions or enhance beneficial functions. In the case of astrocytes, less information is available about potential subpopulations of reactive cells; it also remains elusive whether astrocytes contribute to the neuropathology of AD by mainly gaining neurotoxic functions or losing their ability to support neurons due to astrocyte damage. We identify L-type calcium channel blocker, nimodipine, as a candidate drug for AD, which potentially targets both astrocytes and microglia. It has already shown consistent beneficial effects in basic experimental and clinical studies. We also highlight the recent evidence linking peripheral inflammation and neuroinflammation. Several chronic systemic inflammatory diseases, such as obesity, type 2 diabetes mellitus, and periodontitis, can cause immune priming or adverse activation of glia, thus exacerbating neuroinflammation and increasing risk or facilitating the progression of AD. Therefore, reducing peripheral inflammation is a potentially effective strategy for lowering AD prevalence.

Ergosta-7,9(11),22-trien-3β-ol Alleviates Intracerebral Hemorrhage-Induced Brain Injury and BV-2 Microglial Activation.

Intracerebral hemorrhage (ICH) is a devastating neurological disorder characterized by an exacerbation of neuroinflammation and neuronal injury, for which few effective therapies are available at present. Inhibition of excessive neuroglial activation has been reported to alleviate ICH-related brain injuries. In the present study, the anti-ICH activity and microglial mechanism of ergosta-7,9(11),22-trien-3β-ol (EK100), a bioactive ingredient from Asian medicinal herb Antrodia camphorate, were evaluated. Post-treatment of EK100 significantly attenuated neurobehavioral deficit and MRI-related brain lesion in the mice model of collagenase-induced ICH. Additionally, EK100 alleviated the inducible expression of cyclooxygenase (COX)-2 and the activity of matrix metalloproteinase (MMP)-9 in the ipsilateral brain regions. Consistently, it was shown that EK100 concentration-dependently inhibited the expression of COX-2 protein in Toll-like receptor (TLR)-4 activator lipopolysaccharide (LPS)-activated microglial BV-2 and primary microglial cells. Furthermore, the production of microglial prostaglandin E2 and reactive oxygen species were attenuated by EK100. EK100 also attenuated the induction of astrocytic MMP-9 activation. Among several signaling pathways, EK100 significantly and concentration-dependently inhibited activation of c-Jun N-terminal kinase (JNK) MAPK in LPS-activated microglial BV-2 cells. Consistently, ipsilateral JNK activation was markedly inhibited by post-ICH-treated EK100 in vivo. In conclusion, EK100 exerted the inhibitory actions on microglial JNK activation, and attenuated brain COX-2 expression, MMP-9 activation, and brain injuries in the mice ICH model. Thus, EK100 may be proposed and employed as a potential therapeutic agent for ICH.

Unilateral facial injection of Botulinum neurotoxin A attenuates bilateral trigeminal neuropathic pain and anxiety-like behaviors through inhibition of TLR2-mediated neuroinflammation in mice

ObjectivesIn this study, we investigated the possible analgesic effects of Botulinum toxin type A (BoNT/A) on trigeminal neuralgia (TN). A modified TN mouse model was established by chronic constriction injury of the distal infraorbital nerve (dIoN-CCI) in mice, and the possible roles of microglia toll-like receptor 2 (TLR2) and neuroinflammation was investigated.MethodsMale C57BL/6 mice were divided into 3 groups, including sham group, vehicle-treated TN group and BoNT/A-treated TN group. Bilateral mechanical pain hypersensitivity, anxiety-like and depressive-like behaviors were evaluated by using von Frey test, open field, elevated plus-maze testing, and forced swimming test in mice, respectively. The mRNA or protein expression levels of toll-like receptors (TLRs), glia activation markers and proinflammatory factors in the trigeminal nucleus caudalis (TNC) were tested by RT-qPCR, immunofluorescence and Western blotting. We also tested the pain behaviors of TN in Tlr2−/− mice.ResultsWe found that unilateral subcutaneous injection of BoNT/A into the whisker pad on the ipsilateral side of dIoN-CCI mice significantly attenuated bilateral mechanical pain hypersensitivity and anxiety-like behaviors induced by dIoN-CCI surgery in mice. The dIoN-CCI surgery significantly up-regulated the expression of TLR2, MyD88, CD11b (a microglia marker), IL-1β, TNF-α and IL-6 in the ipsilateral TNC in mice, and BoNT/A injection significantly inhibited the expression of these factors. Immunostaining results confirmed that BoNT/A injection significantly inhibited the microglia activation in the ipsilateral TNC in dIoN-CCI mice. TLR2 deficiency also alleviated bilateral mechanical pain hypersensitivity and the up-regulation of MyD88 expression in the TNC of dIoN-CCI mice.ConclusionThese results indicate that unilateral injection of BoNT/A attenuated bilateral mechanical pain hypersensitivity and anxiety-like behaviors in dIoN-CCI mice, and the analgesic effects of BoNT/A may be associated with the inhibition of TLR2-mediated neuroinflammation in the TNC.

Single intracerebroventricular progranulin injection adversely affects the blood-brain barrier in experimental traumatic brain injury.

Progranulin (PGRN) is a neurotrophic and anti-inflammatory factor with protective effects in animal models of ischemic stroke, subarachnoid hemorrhage, and traumatic brain injury (TBI). Administration of recombinant (r) PGRN prevents exaggerated brain pathology after TBI in Grn-deficient mice, suggesting that local injection of recombinant progranulin (rPGRN) provides therapeutic benefit in the acute phase of TBI. To test this hypothesis, we subjected adult male C57Bl/6N mice to the controlled cortical impact model of TBI, administered a single dose of rPGRN intracerebroventricularly (ICV) shortly before the injury, and examined behavioral and biological effects up to 5days post injury (dpi). The anti-inflammatory bioactivity of rPGRN was confirmed by its capability to inhibit the inflammation-induced hypertrophy of murine primary microglia and astrocytes in vitro. In C57Bl/6N mice, however, ICV administration of rPGRN failed to attenuate behavioral deficits over the 5-day observation period. (Immuno)histological gene and protein expression analyses at 5dpi did not reveal a therapeutic benefit in terms of brain injury size, brain inflammation, glia activation, cell numbers in neurogenic niches, and neuronal damage. Instead, we observed a failure of TBI-induced mRNA upregulation of the tight junction protein occludin and increased extravasation of serum immunoglobulin G into the brain parenchyma at 5dpi. In conclusion, single ICV administration of rPGRN had not the expected protective effects in the acute phase of murine TBI, but appeared to cause an aggravation of blood-brain barrier disruption. The data raise questions about putative PGRN-boosting approaches in other types of brain injuries and disease.

Down‐regulation of Connexions and Pannexin‐1 Coincides with Excitatory Amino‐Acid Transporters Up‐regulation on Glia Cells to Maintain Glutamate Homeostasis after IκB Kinase (IKK) Inhibition

Background and objectives Inflammatory pathway and dysregulation of glutamate level are connected at the level of the glia, leading to numerous neurological disorders. In vitro models have revealed that the channel connexions (Cxs) are implied in glutamate release, while excitatory amino-acid transporters (EAATs) are crucial for glutamate re-uptake. Additionally, pannexin-1 (Panx-1) is involved in glutamate induced neuronal degeneration. However, the pattern of their expressions during inflammation and the effects of nuclear factor-kappa B (NF-κB) inhibition on the inflammatory- induced glutamate imbalance remain unknown. The aim of the study was to explore the roles of Cxs, Panx-1 and EAATS on glutamate induced neurotoxicity, and to clarify the relationship between NK-FB activation and the expressions of Cxs, Panx-1 and EAATS in lipopolysaccharide-induced neuroinflammation. Hypothesis we hypothesized that NF-κB may be involved in the development of glutamate neurotoxicity via regulating the expressions of Cxs, Panx-1 and EAATS on the activated glia cells. Material & Methods To study this, 30 male albino rats were injected with saline or lipopolysaccharide. Subsequently, LPS challenged rats were treated with either vehicle or BAY-117082 (an inhibitor of IκB Kinase (IKK)). Thereafter, reverse transcription polymerase chain reaction (RT-PCR), western blot, enzyme-linked immunosorbent assay (ELISA), and immune-histological analysis were carried out to assess the glia activity, NFKB activation, and glutamate level. Concomitantly, measurement of Cxs, Panx-1, and EAAts expressions in the brain was conducted. The electroencephalography (EEG) was used to record the neuronal activity. The present study was conducted following the FASEB Statement of Principles for the use of Animals in research and Education, and was approved by the Institutional Animal Care Committee (CU Ш F 55 17). Results Our results confirm the previous in- vitro findings that paradoxical changes in the expressions of Cxs, Panx-1, and EAATs may participate significantly in glutamate accumulation and subsequent neurotoxicity. Nuclear factor-kB (NF-κB) pathway significantly impacted the glutamate balance via regulating the expressions of Cxs, Panx-1, and EAATs. BAY-117082 ameliorated gliosis and provided a neuroprotection. Figure 1. Conclusion We concluded that NF-κB is a critical key player in the remodeling of Cxs, panx-1, and EAATs expressions and the initiation of glutamate toxicity.

The Emerging Role of the Interplay Among Astrocytes, Microglia, and Neurons in the Hippocampus in Health and Disease.

For over a century, neurons have been considered the basic functional units of the brain while glia only elements of support. Activation of glia has been long regarded detrimental for survival of neurons but more it appears that this is not the case in all circumstances. In this review, we report and discuss the recent literature on the alterations of astrocytes and microglia during inflammaging, the low-grade, slow, chronic inflammatory response that characterizes normal brain aging, and in acute inflammation. Becoming reactive, astrocytes and microglia undergo transcriptional, functional, and morphological changes that transform them into cells with different properties and functions, such as A1 and A2 astrocytes, and M1 and M2 microglia. This classification of microglia and astrocytes in two different, all-or-none states seems too simplistic, and does not correspond to the diverse variety of phenotypes so far found in the brain. Different interactions occur among the many cell populations of the central nervous system in health and disease conditions. Such interactions give rise to networks of morphological and functional reciprocal reliance and dependency. Alterations affecting one cell population reverberate to the others, favoring or dysregulating their activities. In the last part of this review, we present the modifications of the interplay between neurons and glia in rat models of brain aging and acute inflammation, focusing on the differences between CA1 and CA3 areas of the hippocampus, one of the brain regions most susceptible to different insults. With triple labeling fluorescent immunohistochemistry and confocal microscopy (TIC), it is possible to evaluate and compare quantitatively the morphological and functional alterations of the components of the neuron-astrocyte-microglia triad. In the contiguous and interconnected regions of rat hippocampus, CA1 and CA3 Stratum Radiatum, astrocytes and microglia show a different, finely regulated, and region-specific reactivity, demonstrating that glia responses vary in a significant manner from area to area. It will be of great interest to verify whether these differential reactivities of glia explain the diverse vulnerability of the hippocampal areas to aging or to different damaging insults, and particularly the higher sensitivity of CA1 pyramidal neurons to inflammatory stimuli.

Mapping Network Activity in Sleep.

It was in the influenza pandemic of 1918 that von Economo identified specific brain regions regulating sleep and wake. Since then researchers have used a variety of tools to determine how the brain shifts between states of consciousness. In every enterprise new tools have validated existing data, corrected errors and made new discoveries to advance science. The brain is a challenge but new tools can disentangle the brain network. We summarize the newest tool, a miniature microscope, that provides unprecedented view of activity of glia and neurons in freely behaving mice. With this tool we have observed that the activity of a majority of GABA and MCH neurons in the lateral hypothalamus is heavily biased toward sleep. We suggest that miniscope data identifies activity at the cellular level in normal versus diseased brains, and also in response to specific hypnotics. Shifts in activity in small networks across the brain will help identify point of criticality that switches the brain from wake to sleep.

Suppression of TLR4-MyD88 signaling pathway attenuated chronic mechanical pain in a rat model of endometriosis

BackgroundAs a classic innate immunity pathway, Toll-like receptor 4 (TLR4) signaling has been intensively investigated for its function of pathogen recognition. The receptor is located not only on immune cells but also on sensory neurons and spinal glia. Recent studies revealed the involvement of neuronal TLR4 in different types of pain. However, the specific role of TLR4 signaling in the pain symptom of endometriosis (EM) remains obscure.MethodsThe rat endometriosis model was established by transplanting uterine horn tissue into gastrocnemius. Western blotting and/or immunofluorescent staining were applied to detect high mobility group box 1 (HMGB1), TLR4, myeloid differentiation factor-88 adaptor protein (MyD88), and nuclear factor kappa-B-p65 (NF-κB-p65) expression, as well as the activation of astrocyte and microglia. The antagonist of TLR4 (LPS-RS-Ultra, LRU) and MyD88 homodimerization inhibitory peptide (MIP) were intrathecally administrated to assess the behavioral effects of blocking TLR4 signaling on endometriosis-related pain.ResultsMechanical hyperalgesia was observed at the graft site, while HMGB1 was upregulated in the implanted uterine tissue, dorsal root ganglion (DRG), and spinal dorsal horn (SDH). Compared with sham group, upregulated TLR4, MyD88, and phosphorylated NF-κB-p65 were detected in the DRG and SDH in EM rats. The activation of astrocytes and microglia in the SDH was also confirmed in EM rats. Intrathecal application of LRU and MIP alleviated mechanical pain on the graft site of EM rats, with decreased phosphorylation of NF-κB-p65 in the DRG and reduced activation of glia in the SDH.ConclusionsHMGB1-TLR4-MyD88 signaling pathway in the DRG and SDH may involve in endometriosis-related hyperpathia. Blockade of TLR4 and MyD88 might serve as a potential treatment for pain in endometriosis.

Molecular mechanisms of neurodegeneration in the entorhinal cortex that underlie its selective vulnerability during the pathogenesis of Alzheimer's disease.

ABSTRACTThe entorhinal cortex (EC) is a vital component of the medial temporal lobe, and its contributions to cognitive processes and memory formation are supported through its extensive interconnections with the hippocampal formation. During the pathogenesis of Alzheimer's disease (AD), many of the earliest degenerative changes are seen within the EC. Neurodegeneration in the EC and hippocampus during AD has been clearly linked to impairments in memory and cognitive function, and a growing body of evidence indicates that molecular and functional neurodegeneration within the EC may play a primary role in cognitive decline in the early phases of AD. Defining the mechanisms underlying molecular neurodegeneration in the EC is crucial to determining its contributions to the pathogenesis of AD. Surprisingly few studies have focused on understanding the mechanisms of molecular neurodegeneration and selective vulnerability within the EC. However, there have been advancements indicating that early dysregulation of cellular and molecular signaling pathways in the EC involve neurodegenerative cascades including oxidative stress, neuroinflammation, glia activation, stress kinases activation, and neuronal loss. Dysfunction within the EC can impact the function of the hippocampus, which relies on entorhinal inputs, and further degeneration within the hippocampus can compound this effect, leading to severe cognitive disruption. This review assesses the molecular and cellular mechanisms underlying early degeneration in the EC during AD. These mechanisms may underlie the selective vulnerability of neuronal subpopulations in this brain region to the disease development and contribute both directly and indirectly to cognitive loss.This paper has an associated Future Leader to Watch interview with the first author of the article.