Microglial Pro-inflammatory Cytokine Research Articles

Dexmedetomidine Alleviates Microglia-Induced Spinal Inflammation and Hyperalgesia in Neonatal Rats by Systemic Lipopolysaccharide Exposure.

Noxious stimulus and painful experience in early life can induce cognitive deficits and abnormal pain sensitivity. As a major component of the outer membrane of gram-negative bacteria, lipopolysaccharide (LPS) injection mimics clinical symptoms of bacterial infections. Spinal microglial activation and the production of pro-inflammatory cytokines have been implicated in the pathogenesis of LPS-induced hyperalgesia in neonatal rats. Dexmedetomidine (DEX) possesses potent anti-neuroinflammatory and neuroprotective properties through the inhibition of microglial activation and microglial polarization toward pro-inflammatory (M1) phenotype and has been widely used in pediatric clinical practice. However, little is known about the effects of DEX on LPS-induced spinal inflammation and hyperalgesia in neonates. Here, we investigated whether systemic LPS exposure has persistent effects on spinal inflammation and hyperalgesia in neonatal rats and explored the protective role of DEX in adverse effects caused by LPS injection. Systemic LPS injections induced acute mechanical hyperalgesia, increased levels of pro-inflammatory cytokines in serum, and short-term increased expressions of pro-inflammatory cytokines and M1 microglial markers in the spinal cord of neonatal rats. Pretreatment with DEX significantly decreased inflammation and alleviated mechanical hyperalgesia induced by LPS. The inhibition of M1 microglial polarization and microglial pro-inflammatory cytokines expression in the spinal cord may implicate its neuroprotective effect, which highlights a new therapeutic target in the treatment of infection-induced hyperalgesia in neonates and preterm infants.

191. High-Dose Rifampin-containing Regimens for the Treatment of TB Meningitis

191. High-Dose Rifampin-containing Regimens for the Treatment of TB Meningitis

The influence of sleep-wake rhythms on AD-related pathology in 3xTgAD mice.

Age-associated fragmentation of the daily sleep-wake rhythm is believed to be significant in the development of AD. While it is known that sleep deprivation can worsen AD-related pathology, such as amyloid (Aβ) deposition and neuroinflammation, the effects of fragmentation of the daily sleep-wake rhythm are unknown. It is possible that sleep fragmentation (SF), as a less stressful approach to the manipulation of the sleep-wake cycle, could better model AD-related sleep disturbances. We tested this hypothesis by subjecting female 3x-TgAD mice to a chronic SF protocol for a period of 4 weeks. SF consisted of 4 daily x 1 hour sleep disruptions, evenly interspersed throughout the light phase. During SF, mice were kept awake with novel objects and gently stimulated with a paintbrush; control mice were left undisturbed (US) during these periods. Mice were individually housed in PiezoSleep cages (Signal Solutions LLC) for sleep recordings during the first and fourth weeks of the study and group-housed in regular cages during the second and third weeks. Per 24 hours, SF mice exhibited significantly lower levels of sleep in the light phase (∼18% reduction) and higher levels of sleep in the dark phase (∼15% increase), with only a modest decrease (∼4%) in the total amount of daily sleep. After SF, Aβ40 and Aβ42 levels were significantly higher in the RIPA soluble fraction, as assayed by ELISA. An examination of mRNA using TaqMan low-density gene expression arrays indicated that markers of both microglial activation (ctsd, cst7, and clec7a) and proinflammatory cytokines (TNFα, IL6, and IL-1β) were elevated in mice subjected to SF as compared to the US group. Interestingly, the increase in Aβ and markers of neuroinflammation found in the hippocampus was not observed in the cortex, indicating at least some degree of neuroanatomical specificity in the effects of SF. These findings demonstrate that a protocol for fragmenting the daily sleep-wake rhythm in 3x-TgAD mice can impact the development of AD-related pathology. These studies also support the concept that improving sleep consolidation in individuals at risk for AD may be beneficial for slowing the onset or progression of AD.

Human Retinal Progenitor Cells Derived Small Extracellular Vesicles Delay Retinal Degeneration: A Paradigm for Cell-free Therapy.

Retinal degeneration is a leading cause of irreversible vision impairment and blindness worldwide. Previous studies indicate that subretinal injection of human retinal progenitor cells (hRPCs) can delay the progression of retinal degeneration, preserve retinal function, and protect photoreceptor cells from death, albeit the mechanism is not well understood. In this study, small extracellular vesicles derived from hRPCs (hRPC-sEVs) were injected into the subretinal space of retinal dystrophic RCS rats. We find that hRPC-sEVs significantly preserve the function of retina and thickness of the outer nuclear layer (ONL), reduce the apoptosis of photoreceptors in the ONL, and suppress the inflammatory response in the retina of RCS rats. In vitro, we have shown that hRPC-sEV treatment could significantly reserve the low-glucose preconditioned apoptosis of photoreceptors and reduce the expression of pro-inflammatory cytokines in microglia. Pathway analysis predicted the target genes of hRPC-sEV microRNAs involved in inflammation related biological processes and significantly enriched in processes autophagy, signal release, regulation of neuron death, and cell cycle. Collectively, our study suggests that hRPC-sEVs might be a favorable agent to delay retinal degeneration and highlights as a new paradigm for cell-free therapy.

Chronic Fragmentation of the Daily Sleep-Wake Rhythm Increases Amyloid-beta Levels and Neuroinflammation in the 3xTg-AD Mouse Model of Alzheimer’s Disease

Fragmentation of the daily sleep-wake rhythm with increased nighttime awakenings and more daytime naps is correlated with the risk of development of Alzheimer’s disease (AD). To explore whether a causal relationship underlies this correlation, the present study tested the hypothesis that chronic fragmentation of the daily sleep-wake rhythm stimulates brain amyloid-beta (Aβ) levels and neuroinflammation in the 3xTg-AD mouse model of AD. Female 3xTg-AD mice were allowed to sleep undisturbed or were subjected to chronic sleep fragmentation consisting of four daily sessions of enforced wakefulness (one hour each) evenly distributed during the light phase, five days a week for four weeks. Piezoelectric sleep recording revealed that sleep fragmentation altered the daily sleep-wake rhythm to resemble the pattern observed in AD. Levels of amyloid-beta (Aβ40 and Aβ42) determined by ELISA were higher in hippocampal tissue collected from sleep-fragmented mice than from undisturbed controls. In contrast, hippocampal levels of tau and phospho-tau differed minimally between sleep fragmented and undisturbed control mice. Sleep fragmentation also stimulated neuroinflammation as shown by increased expression of markers of microglial activation and proinflammatory cytokines measured by q-RT-PCR analysis of hippocampal samples. No significant effects of sleep fragmentation on Aβ, tau, or neuroinflammation were observed in the cerebral cortex. These studies support the concept that improving sleep consolidation in individuals at risk for AD may be beneficial for slowing the onset or progression of this devastating neurodegenerative disease.

Ketamine abrogates sensorimotor deficits and cytokine dysregulation in a chronic unpredictable mild stress model of depression.

Major depressive disorder (MDD) is a serious mental disorder with influence across the functional systems of the body. The pathogenesis of MDD has been known to involve the alteration of normal body functions responsible for the normal inflammation processes within the CNS; this along with other effects results in the depreciation of the sensorimotor performance of the body. Ketamine hydrochloride, a novel antidepressant agent, has been used as a therapeutic agent to treat MDD with its efficacy stretching as far as enhancing sensorimotor performance and restoring normal cytokine levels of the CNS. While these therapeutic actions of ketamine may or may not be related, this study made use of chronic unpredictable mild stress (CUMS) to generate the mouse model of depression. The efficacy of ketamine as an antidepressant following sequential exposure and co-administrative treatment protocols of administration was evaluated using behavioural tests for sensorimotor performance and depressive-like behaviours. Its effect in managing CNS inflammation was assessed via the biochemical analysis of inflammatory cytokine levels in the cerebrum, spinal cord and cerebellum; and immunohistochemical demonstration of microglial activity in the corpus striatum and cerebellum. The sensorimotor performance which had been diminished by CUMS showed greater improvement under the sequential exposure regimen of ketamine. Ketamine was also efficacious in decreasing the level of inflammation with an evident reduction in microglial activation and pro-inflammatory cytokines in the studied regions, following CUMS exposure. Taken together, our study indicates that ketamine therapy can improve sensorimotor deficits co-morbid with a depressive disorder in parallel with modulation of the inflammatory system.

Dopamine inhibits the expression of proinflammatory cytokines of microglial cells through the formation of dopamine quinone in the mouse striatum

We previously reported that dopamine (DA) attenuated lipopolysaccharide (LPS)-induced expression of proinflammatory cytokines through the formation of DA quinone (DAQ) in murine microglial cell line BV-2 and primary murine microglial cells. To reveal whether DA inhibits the expression of proinflammatory cytokines of microglial cells through the formation of DAQ in the central nervous system (CNS), in this study, we examined the effect of DAQ on LPS-induced mRNA expression of proinflammatory cytokines in C57BL/6 mouse brain under two experimental conditions: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration and l-dopa/carbidopa administration. Acute MPTP administration reduced the number of tyrosine hydroxylase-positive cells in the substantia nigra, and decreased the level of quinoprotein, an indicator of DAQ formation, in the striatum. Real-time RT-PCR analysis revealed that intraperitoneal administration of LPS increased the mRNA levels of proinflammatory cytokines, including tumor-necrosis factor-α and interleukin-1β, in the striatum. These increases were enhanced in MPTP-treated mice. On the other hand, l-dopa/carbidopa administration increased the level of quinoprotein, attenuated the LPS-induced mRNA expression of proinflammatory cytokines, and reduced the LPS-induced increase in the number of microglial cells in the striatum. These results suggest that DA attenuate the expression of proinflammatory cytokines in microglia through the formation of DAQ in the CNS.

Genetic loss-of-function of activating transcription factor 3 but not C-type lectin member 5A prevents diabetic peripheral neuropathy

We investigated the mediating roles of activating transcription factor 3 (ATF3), an injury marker, or C-type lectin member 5A (CLEC5A), an inflammatory response molecule, in the induction of endoplasmic reticulum (ER) stress and neuroinflammation in diabetic peripheral neuropathy in ATF3 and CLEC5A genetic knockout (aft3−/− and clec5a−/−, respectively) mice. ATF3 was expressed intranuclearly and was upregulated in mice with diabetic peripheral neuropathy (DN) and clec5a−/− mice. The DN and clec5a−/− groups also exhibited neuropathic behavior, but not in the aft3−/− group. The upregulation profiles of cytoplasmic polyadenylation element-binding protein, a protein translation–regulating molecule, and the ER stress-related molecules of inositol-requiring enzyme 1α and phosphorylated eukaryotic initiation factor 2α in the DN and clec5a−/− groups were correlated with neuropathic behavior. Ultrastructural evidence confirmed ER stress induction and neuroinflammation, including microglial enlargement and proinflammatory cytokine release, in the DN and clec5a−/− mice. By contrast, the induction of ER stress and neuroinflammation did not occur in the aft3−/− mice. Furthermore, the mRNA of reactive oxygen species–removing enzymes such as superoxide dismutase, heme oxygenase-1, and catalase were downregulated in the DN and clec5a−/− groups but were not changed in the aft3−/− group. Taken together, the results indicate that intraneuronal ATF3, but not CLEC5A, mediates the induction of ER stress and neuroinflammation associated with diabetic neuropathy.Neuroinflammation and endoplasmic reticulum stress is a critical process that leads to diabetic peripheral neuropathy (DPN). Activating transcription factor 3 (ATF3) is a susceptible molecule, and loss-of-function of ATF3, but not C-type lectin member 5A (CLEC5A), prevents the development of neuroinflammation and ER stress. Functional blockade of ATF3 may be a potential treatment for diabetic peripheral neuropathy by inhibiting neuroinflammation and cellular stress-induced ER stress.

Enriched Environment Prevents Surgery-Induced Persistent Neural Inhibition and Cognitive Dysfunction.

Perioperative neurocognitive disorders (PND) encompass short-term delirium and long-term cognitive dysfunction. Aging increases the susceptibility to PND, yet the neural mechanism is not known. In this study, we monitored the dynamic changes of neuronal activity in the prelimbic cortex before and after surgery. We found that anesthesia combined with surgery, but not anesthesia alone, induced a prolonged decrease in neuronal activity during the post-operation period in the aged mice, but not in the adult mice. The prolonged decrease in neuronal activity was accompanied by surgery-induced microglial activation and proinflammatory cytokines expression. Importantly, we found that the enriched environment (EE) completely prevented both the prolonged neural inhibition and neuroinflammation, and improved cognitive function in the aged mice. These results indicate that the prolonged neural inhibition correlated to PND and that EE before the surgery could effectively alleviate the surgery- induced cognitive dysfunction.

Endogenous neural stem cells modulate microglia and protect against demyelination.

SummaryIn response to corpus callosum (CC) demyelination, subventricular zone-derived neural progenitors (SVZdNPs) are mobilized and generate new myelinating oligodendrocytes (OLG). Here, we examine the putative immunomodulatory properties of endogenous SVZdNPs during demyelination in the cuprizone model. SVZdNP density was higher in the lateral and rostral CC regions, and demyelination was inversely correlated with activated microglial density and pro-inflammatory cytokine levels. Single-cell RNA sequencing showed that CC areas with high levels of SVZdNP mobilization were enriched in a microglial cell subpopulation with an immunomodulatory signature. We propose MFGE8 (milk fat globule-epidermal growth factor-8) and β3 integrin as a ligand/receptor pair involved in dialogue between SVZdNPs and microglia. Immature SVZdNPs mobilized to the demyelinated CC were found highly enriched in MFGE8, which promoted the phagocytosis of myelin debris in vitro. Overall, these results demonstrate that, in addition to their cell replacement capacity, endogenous progenitors have immunomodulatory properties, highlighting a new role for endogenous SVZdNPs in myelin regeneration.

Neuroinflammation in Schizophrenia

Schizophrenia is a chronic debilitating mental illness. In many aspects, the neuropathology of schizophrenia is closely associated with neuroinflammation, especially microglial activation. Microglial hyperactivity, which is characterized by the predominant release of proinflammatory cytokines serves as the basis of the neuroinflammation hypothesis in schizophrenia. The enhanced inflammatory induce neuronal susceptibility to oxidative stress and trigger, glutamatergic synaptic dysregulation, especially in the mesolimbic and mesocortical pathways. Many in vitro studies, in vivo animal evidence, post-mortem examinations, neuroimaging evaluations with Positron Emission Tomography (PET), anti-inflammatory and antipsychotic use converge upon the central role of microglial activation and proinflammatory cytokines as common of features schizophrenia.

Triptolide protects against white matter injury induced by chronic cerebral hypoperfusion in mice.

White matter injury is the major pathological alteration of subcortical ischemic vascular dementia (SIVD) caused by chronic cerebral hypoperfusion. It is characterized by progressive demyelination, apoptosis of oligodendrocytes and microglial activation, which leads to impairment of cognitive function. Triptolide exhibits a variety of pharmacological activities including anti-inflammation, immunosuppression and antitumor, etc. In this study, we investigated the effects of triptolide on white matter injury and cognitive impairments in mice with chronic cerebral hypoperfusion induced by the right unilateral common carotid artery occlusion (rUCCAO). We showed that triptolide administration alleviated the demyelination, axonal injury, and oligodendrocyte loss in the mice. Triptolide also improved cognitive function in novel object recognition test and Morris water maze test. In primary oligodendrocytes following oxygen-glucose deprivation (OGD), application of triptolide (0.001-0.1 nM) exerted concentration-dependent protection. We revealed that the protective effect of triptolide resulted from its inhibition of oligodendrocyte apoptosis via increasing the phosphorylation of the Src/Akt/GSK3β pathway. Moreover, triptolide suppressed microglial activation and proinflammatory cytokines expression after chronic cerebral hypoperfusion in mice and in BV2 microglial cells following OGD, which also contributing to its alleviation of white matter injury. Importantly, mice received triptolide at the dose of 20 μg·kg-1·d-1 did not show hepatotoxicity and nephrotoxicity even after chronic treatment. Thus, our results highlight that triptolide alleviates whiter matter injury induced by chronic cerebral hypoperfusion through direct protection against oligodendrocyte apoptosis and indirect protection by inhibition of microglial inflammation. Triptolide may have novel indication in clinic such as the treatment of chronic cerebral hypoperfusion-induced SIVD.

Chinese Medicine Formula Kai-Xin-San Ameliorates Neuronal Inflammation of CUMS-Induced Depression-like Mice and Reduces the Expressions of Inflammatory Factors via Inhibiting TLR4/IKK/NF-κB Pathways on BV2 Cells.

Kai-Xin-San (KXS) is a traditional Chinese medicinal formula composed of Ginseng Radix et Rhizoma, Polygalae Radix, Acori Tatarinowii Rhizoma, and Poria for relieving major depressive disorder and Alzheimer’s disease in traditional Chinese medicine (TCM) clinics. Previous studies on the antidepressant mechanism of KXS mainly focused on neurotransmitter and neurotrophic factor regulation, but few reports exist on neuronal inflammation regulation. In the current study, we found that KXS exerted antidepressant effects in chronic unpredictable mild stress-induced depression-like mice according to the results of behavioral tests. Meanwhile, KXS also inhibited the activation of microglia and significantly reduced the expression of pro-inflammatory cytokines such as IL-1β, IL−2, and TNF-α in the hippocampus of mice. In mice BV2 microglia cell lines, KXS extract reduced the expression of inflammatory factors in BV2 cells induced by lipopolysaccharide via inhibiting TLR4/IKK/NF-κB pathways, which was also validated by the treatment of signaling pathway inhibitors such as TAK-242 and JSH-23. T0hese data implied that the regulation of pro-inflammatory cytokines in microglia might account for the antidepressant effect of KXS, thereby providing more scientific information for the development of KXS as an alternative therapy for major depressive disorder.

RGS10 physically and functionally interacts with STIM2 and requires store-operated calcium entry to regulate pro-inflammatory gene expression in microglia

Chronic activation of microglia is a driving factor in the progression of neuroinflammatory diseases, and mechanisms that regulate microglial inflammatory signaling are potential targets for novel therapeutics. Regulator of G protein Signaling 10 is the most abundant RGS protein in microglia, where it suppresses inflammatory gene expression and reduces microglia-mediated neurotoxicity. In particular, microglial RGS10 downregulates the expression of pro-inflammatory mediators including cyclooxygenase 2 (COX-2) following stimulation with lipopolysaccharide (LPS). However, the mechanism by which RGS10 affects inflammatory signaling is unknown and is independent of its canonical G protein targeted mechanism. Here, we sought to identify non-canonical RGS10 interacting partners that mediate its anti-inflammatory mechanism. Through RGS10 co-immunoprecipitation coupled with mass spectrometry, we identified STIM2, an endoplasmic reticulum (ER) localized calcium sensor and a component of the store-operated calcium entry (SOCE) machinery, as a novel RGS10 interacting protein in microglia. Direct immunoprecipitation experiments confirmed RGS10-STIM2 interaction in multiple microglia and macrophage cell lines, as well as in primary cells, with no interaction observed with the homologue STIM1. We further determined that STIM2, Orai channels, and the calcium-dependent phosphatase calcineurin are essential for LPS-induced COX-2 production in microglia, and this pathway is required for the inhibitory effect of RGS10 on COX-2. Additionally, our data demonstrated that RGS10 suppresses SOCE triggered by ER calcium depletion and that ER calcium depletion, which induces SOCE, amplifies pro-inflammatory genes. In addition to COX-2, we also show that RGS10 suppresses the expression of pro-inflammatory cytokines in microglia in response to thrombin and LPS stimulation, and all of these effects require SOCE. Collectively, the physical and functional links between RGS10 and STIM2 suggest a complex regulatory network connecting RGS10, SOCE, and pro-inflammatory gene expression in microglia, with broad implications in the pathogenesis and treatment of chronic neuroinflammation.

Imaging and Manipulation of Stem and Progenitor Cells for Revealing the Novel Mechanism of Local Tissue Maintenance in the Brain

We have been investigating the physiological and pathological roles of stem cells and progenitor cells in the central nervous system using multimodal imaging methods, including positron emission tomography (PET), in vivo optical imaging, and light as well as electron microscopy. Furthermore, we generated transgenic rats for selective ablation of these cells. Imaging studies have demonstrated the proliferation and dynamics of neural stem cells in neurogenic regions and glial progenitor cells expressing a chondroitin sulfate proteoglycan (neuron-glial antigen 2; NG2) in the brain of adult rodents. Glial progenitor cells change their direction of differentiation into mature oligodendrocytes or astrocytes by neural activity following their proliferation. This phenomenon was thought to control the local tissue structure for maintenance of moderate neural activity. Furthermore, selective ablation of glial progenitor cells in the brain induced defects of neurons via neuroinflammation with microglial activation and proinflammatory cytokine production in the region. Thus, we have proposed a novel concept that glial progenitor cells regulate the neuro-immune system in the central nervous system, in addition to their role as germinal cells, giving rise to mature glial cells. Neuroinflammation is associated with the onset and progression of depression, chronic fatigue syndrome, and neurodegenerative diseases, including Alzheimer's disease. Anti-inflammatory effects of glial progenitor cells might bring about the possibility of these cells as the new therapeutic targets for such neurological disorders.

Sirtuin 3 protects against anesthesia/surgery-induced cognitive decline in aged mice by suppressing hippocampal neuroinflammation

BackgroundPostoperative cognitive dysfunction (POCD) is a very common complication that might increase the morbidity and mortality of elderly patients after surgery. However, the mechanism of POCD remains largely unknown. The NAD-dependent deacetylase protein Sirtuin 3 (SIRT3) is located in the mitochondria and regulates mitochondrial function. SIRT3 is the only sirtuin that specifically plays a role in extending lifespan in humans and is associated with neurodegenerative diseases. Therefore, the aim of this study was to evaluate the effect of SIRT3 on anesthesia/surgery-induced cognitive impairment in aged mice.MethodsSIRT3 expression levels were decreased after surgery. For the interventional study, an adeno-associated virus (AAV)-SIRT3 vector or an empty vector was microinjected into hippocampal CA1 region before anesthesia/surgery. Western blotting, immunofluorescence staining, and enzyme-linked immune-sorbent assay (ELISA) were used to measure the oxidative stress response and downstream microglial activation and proinflammatory cytokines, and Golgi staining and long-term potentiation (LTP) recording were applied to evaluate synaptic plasticity.ResultsOverexpression of SIRT3 in the CA1 region attenuated anesthesia/surgery-induced learning and memory dysfunction as well as synaptic plasticity dysfunction and the oxidative stress response (superoxide dismutase [SOD] and malondialdehyde [MDA]) in aged mice with POCD. In addition, microglia activation (ionized calcium binding adapter molecule 1 [Iba1]) and neuroinflammatory cytokine levels (tumor necrosis factor-alpha [TNF-α], interleukin [IL]-1β and IL-6) were regulated after anesthesia/surgery in a SIRT3-dependent manner.ConclusionThe results of the current study demonstrate that SIRT3 has a critical effect in the mechanism of POCD in aged mice by suppressing hippocampal neuroinflammation and reveal that SIRT3 may be a promising therapeutic and diagnostic target for POCD.

Early low-dose ghrelin intervention via miniosmotic pumps could protect against the progressive dopaminergic neuron loss in Parkinson's disease mice

Ghrelin has been identified as a multifunctional peptide that has a potential application for treating Parkinson's disease (PD). The objective of this study was to assess the effects of subcutaneous administration of low-dose ghrelin via miniosmotic pumps on PD progression. The decreased levels of total and active ghrelin in plasma were rescued by ghrelin administration in PD mice. Interestingly, ghrelin did not affect weight gain in wild-type mice but improved weight loss in PD mice. We observed the attenuation of dopaminergic neuron loss in substantia nigra and a low level of dopamine content in the striatum in PD mice with ghrelin treatment. Ghrelin administration could improve the microenvironment of dopaminergic neurons by inhibiting microglial proliferation and proinflammatory cytokine expression and could enhance cell survival by upregulating Bcl-2/Bax ratio and superoxide dismutase1 protein level in the substantia nigra of PD mice. Subcutaneous administration of low-dose ghrelin could prevent the onset of the progression of PD and also provide a possible method for ghrelin application to cure PD.

Imidazoline ligand BU224 reverses cognitive deficits, reduces microgliosis and enhances synaptic connectivity in a mouse model of Alzheimer's disease.

Activation of type 2 imidazoline receptors has been shown to exhibit neuroprotective properties including anti-apoptotic and anti-inflammatory effects, suggesting a potential therapeutic value in Alzheimer's disease (AD). Here, we explored the effects of the imidazoline-2 ligand BU224 in a model of amyloidosis. Six-month-old female transgenic 5XFAD and wild-type (WT) mice were treated intraperitoneally with 5-mg·kg-1 BU224 or vehicle twice a day for 10 days. Behavioural tests were performed for cognitive functions and neuropathological changes were investigated by immunohistochemistry, Western blot, elisa and qPCR. Effects of BU224 on amyloid precursor protein (APP) processing, spine density and calcium imaging were analysed in brain organotypic cultures and N2a cells. BU224 treatment attenuated spatial and perirhinal cortex-dependent recognition memory deficits in 5XFAD mice. Fear-conditioning testing revealed that BU224 also improved both associative learning and hippocampal- and amygdala-dependent memory in transgenic but not in WT mice. In the brain, BU224 reduced levels of the microglial marker Iba1 and pro-inflammatory cytokines IL-1β and TNF-α and increased the expression of astrocytic marker GFAP in 5XFAD mice. These beneficial effects were not associated with changes in amyloid pathology, neuronal apoptosis, mitochondrial density, oxidative stress or autophagy markers. Interestingly, ex vivo and in vitro studies suggested that BU224 treatment increased the size of dendritic spines and induced a threefold reduction in amyloid-β (Aβ)-induced functional changes in NMDA receptors. Sub-chronic treatment with BU224 restores memory and reduces inflammation in transgenic AD mice, at stages when animals display severe pathology.

Effects of chronic stress on depressive-like behaviors and JMJD3 expression in the prefrontal cortex and hippocampus of C57BL/6 and ob/ob mice

BackgroundDepression is a psychiatric disorder which is accompanied by neuroinflammatory responses. Obesity is considered as a low-grade inflammatory state. Studies have found that obese individuals are more likely to suffer from depression, but its possible mechanism has not been specifically illuminated. The Jumonji domain protein 3 (JMJD3) is a specific histone demethylase of trimethylation at lysine 27 of histone-H3 (H3K27me3). Over-expressions of JMJD3 induces the demethylation of H3K27me3 and results in the expression of pro-inflammatory genes, while its upregulation may be limited by adiponectin (APN). However, the role of JMJD3 in susceptibility to neuroinflammation and depression in obesity has not been clarified. MethodsChronic unpredictable mild stress (CUMS) was selected to build depression model in C57BL/6 and ob/ob mice. Sucrose preference test, tail suspension test, open field test and Morris water maze test were used to detect depressive-like behaviors and memory impairment. Microglial activation, pro-inflammatory cytokines, APN, NF-ĸB, JMJD3 and H3K27me3 expressions in the serum, prefrontal cortex (PFC) and hippocampus (HIP) were examined in C57BL/6 and ob/ob mice. Meanwhile, GSK-J4 was used to inhibit JMJD3 expression. ResultsCUMS led to depressive-like behaviors and memory impairment, microglial activation, increased expressions of pro-inflammatory cytokines, NF-κB and JMJD3, decreased expression of H3K27me3 in the PFC and HIP in C57BL/6 and ob/ob mice. Meanwhile, ob/ob mice showed worse behavioral injury and memory impairment, microglial excessively activation, over-expression of pro-inflammatory cytokines and NF-ĸB and decreased H3K27me3 levels than C57BL/6 mice. CUMS also decreased the APN levels in the serum and brain tissues in ob/ob mice compared to C57BL/6 mice. But GSK-J4 could relieve these alterations. ConclusionsJMJD3 might be involved in the susceptibility to depressive-like behaviors and neuroinflammation of obese mice by the demethylation of H3K27me3, and decreased levels of APN could reduce Enhancer of zeste homolog 2 (EZH2) binding with H3K27me3. The role of JMJD3 in severer inflammatory state in the comorbidity of obesity and depression was considered.

Prophylactic inhibition of NF-\u03baB expression in microglia leads to attenuation of hypoxic ischemic injury of the immature brain

BackgroundPeriventricular leukomalacia (PVL), a devastating brain injury affecting premature infants, is the most common cause of cerebral palsy. PVL is caused by hypoxia ischemia (HI) and is characterized by white matter necrotic lesions, microglial activation, upregulation of NF-κB, and neuronal death. The microglia is the main cell involved in PVL pathogenesis. The goal of this study was to investigate the role of microglial NF-κB activity and its prophylactic inhibition in a neonate mouse model of HI.MethodsTransgenic mice with specific knockout NF-κB in microglia and colony stimulating factor 1 receptor Cre with floxed IKKβ (CSF-1R Cre + IKKβflox/wt ) were used. Postnatal day 5 (P5) mice underwent sham or bilateral temporary carotid artery ligation followed by hypoxia. After HI insult, inflammatory cytokines, volumetric MRI, histopathology, and immunohistochemistry for oligodendroglia and microglial activation markers were analyzed. Long-term neurobehavioral assessment, including grip strength, rotarod, and open field testing, was performed at P60.ResultsWe demonstrate that selective inhibition of NF-κB in microglia decreases HI-induced brain injury by decreasing microglial activation, proinflammatory cytokines, and nitrative stress. Rescue of oligodendroglia is evidenced by immunohistochemistry, decreased ventriculomegaly on MRI, and histopathology. This selective inhibition leads to attenuation of paresis, incoordination, and improved grip strength, gait, and locomotion.ConclusionWe conclude that NF-κb activation in microglia plays a major role in the pathogenesis of hypoxic ischemic injury of the immature brain, and its prophylactic inhibition offers significant neuroprotection. Using a specific inhibitor of microglial NF-κB may offer a new prophylactic or therapeutic alternative in preterm infants affected by HI and possibly other neurological diseases in which microglial activation plays a role.