How would the cells respond to Aβ? Mancuso injected 5 μL of 10 μM synthetic oligomers into the mouse brain ventricles eight to 10 weeks after transplanting the human microglia. In reaction to this insult, endogenous mouse microglia shifted their transcriptomes sequentially from homeostatic to cytokine responsive, to activated, with the latter partially overlapping with disease-associated microglial (DAM) signatures described previously (Jun 2017 news). Human microglia in the mice underwent a transcriptional transformation as well, but analysis of more than 10,000 orthologous genes indicated poor correlation between human and mouse microglial responses. Of 207 differentially activated genes, 112 were up in human but not mouse microglia; they included GWAS hits BIN1 and PICALM. "We saw that human microglia responded very differently to Aβ oligomers. This emphasizes the need to look specifically at human cells in the context of AD," said De Strooper.. Blurton-Jones and colleagues took a ...
Surveillant parenchymal microglial cells are extremely plastic and provide the first line of defense within the CNS. Resident microglial cells are morphologically and functionally distinct from other mononuclear CNS populations, such as perivascular macrophages, supraependymal macrophages, epiplexus cells of the choroids plexus, and meningeal macrophages (24, 25). In the naive brain, microglia display small cell bodies with thin, long, and branched processes (1). Although microglial functions are intended to be protective, it is documented that dysregulated microglial responses lead to neurotoxicity in vitro and in vivo (12). Recent data have clearly shown that activation of microglia might be beneficial in some pathological settings. More specifically, absence of CX3CR1 in two different models of Alzheimers disease correlated to reduced β-amyloid deposition because of enhanced phagocytosis by activated microglia (26, 27). Upon activation, because of inflammation of neuronal damage, microglial ...
Our data show for the first time that Cu(II) enhances the effect of Aβ on microglial activation and the subsequent neurotoxicity. This activating effect is NF-κB-dependent and involves NOX-independent, mitochondria-derived ROS.. Cu(II) is suggested to bind monomeric Aβ peptides (predominantly with 1:1 stoichiometry) with high affinity, leading to the formation of Cu(II)-Aβ complex [7-9]. In the present study, the results of an assay of Aβ aggregation by sedimentation, thioflavin T fluorescence assay, and dot blot analysis indicate the formation of Cu(II)-Aβ complex, whose conformation or nature differs from fibrillar or oligomeric Aβ and monomeric Aβ.. In the following experiments, we found that Cu(II)-Aβ induced an activating morphological phenotype of microglia and microglial release of TNF-α and nitric oxide. The increase in nitric oxide production was accompanied by an increase in iNOS expression. Moreover, a subneurotoxic concentration of Cu(II)-Aβ produced an indirect, ...
TY - JOUR. T1 - Heterogeneity of antigen expression and lectin labeling on microglial cells in the olfactory bulb of adult rats. AU - Wu, C. H.. AU - Chien, H. F.. AU - Chang, C. Y.. AU - Ling, E. A.. PY - 1997/5. Y1 - 1997/5. N2 - Microglia in different layers of the rat olfactory bulb expressed a variety of membrane antigens except for CD4 (OX-35). Bulb microglial cells bearing complement receptor type 3 (OX-42) were ubiquitous and their immunoreactivity varied considerably in different bulb layers. Although very few in number, labeled microglia in all layers also expressed major histocompatibility complex class I antigen (OX-18), leukocyte common antigen (OX-1) and unknown macrophage antigen (ED-2). The latter was localized in cells distributed almost exclusively in the perivascular spaces. The immunoreactivity of ED-1, an unknown cytoplasmic or lysosomal membrane antigen in macrophages, was localized in labeled microglia which were concentrated mainly in the granule cell layer and ...
Modulation of Microglial Activation with Laser Therapy". The biological effects of laser therapy (LT), also known as low level light therapy, are currently theorized to follow the Arndt-Schulz law, in which low to moderate energy densities induce activity while higher doses result in inhibition. However, in microglia, there is a range of possible responses, including activation into either a pro-inflammatory (M1) or an anti-inflammatory (M2) state, rather than simple activation and inhibition, excluding them from the Arndt-Schulz law. We therefore aim to show that LT at 810 nm has a differential effect on microglial activation state, depending on energy density. Specifically, we hypothesize that activation of microglia at a low power density will induce an M1 microglial phenotype, while a higher power density will induce an M2 phenotype. These studies will determine if LT can non-invasively modulate microglial phenotype after injury, which would have significant therapeutic potential in the ...
Microglia, central nervous system (CNS) resident phagocytic cells, persistently police the integrity of CNS tissue and respond to any kind of damage or pathophysiological changes. These cells sense and rapidly respond to danger and inflammatory signals by changing their cell morphology; by release of cytokines, chemokines, or nitric oxide; and by changing their MHC expression profile. We have shown previously that microglial biosynthesis of the complement subcomponent C1q may serve as a reliable marker of microglial activation ranging from undetectable levels of C1q biosynthesis in resting microglia to abundant C1q expression in activated, nonramified microglia. In this study, we demonstrate that cultured microglial cells respond to extrinsic C1q with a marked intracellular Ca2+ increase. A shift toward proinflammatory microglial activation is indicated by the release of interleukin-6, tumor necrosis factor-alpha, and nitric oxide and the oxidative burst in rat primary microglial cells, an ...
Microglia are the principal immune cells of the CNS continually surveying their micro-environment for endogenous and exogenous stimuli which may threaten the immunological balance. Recent studies have suggested that activated microglia, like macrophages, adopt different phenotypes depending on the stimulus; IFNy induces classical activation of microglia, whereas IL-4 induces an alternative activation state. A deactivation state has been described in which the interaction between ligand-receptor pairs, for example CD200-CD200R, suppress the immune response. The focus of this study was to investigate the modulatory role of CD200 on different microglial phenotypes ...
Microglia are the resident immune cells of the central nervous system (CNS) and play an important role in innate immune defense as well as tissue homeostasis. Chronic microglial reactivity, microgliosis, is a general hallmark of inflammatory and degenerative diseases that affect the CNS, including the retina. There is increasing evidence that chronic microgliosis is more than just a bystander effect, but rather actively contributes to progression of degeneration through processes such as toxic nitric oxide (NO) production and even phagocytosis of stressed but viable photoreceptors. Therefore immunmodulation of microglia presents a possible therapeutic strategy for retinal degenerations. Notably, the expression of the mitochondrial translocator protein 18 (κDa) (TSPO) is highly elevated in reactive microglia as seen in several neuroinflammatory diseases such as Alzheimers disease, Parkinsons disease and multiple sclerosis. Therefore it is used as a gliosis biomarker in the brain. Moreover TSPO ...
Any pathologic event in the brain leads to the activation of microglia, the immunocompetent cells of the central nervous system. In recent decades diverse molecular pathways have been identified by which microglial activation is controlled and by which the activated microglia affects neurons. In the normal brain microglia were considered "resting," but it has recently become evident that they constantly scan the brain environment and contact synapses. Activated microglia can remove damaged cells as well as dysfunctional synapses, a process termed "synaptic stripping." Here we summarize evidence that molecular pathways characterized in pathology are also utilized by microglia in the normal and developing brain to influence synaptic development and connectivity, and therefore should become targets of future research. Microglial dysfunction results in behavioral deficits, indicating that microglia are essential for proper brain function. This defines a new role for microglia beyond being a mere ...
Like other neurodegenerative diseases, Alzheimer Disease (AD) has a prominent inflammatory component mediated by brain microglia. Reducing microglial inflammation could potentially halt or at least slow the neurodegenerative process. A major challenge in the development of treatments targeting brain inflammation is the sheer complexity of the molecular mechanisms that determine whether microglia become inflammatory or take on a more neuroprotective phenotype. The process is highly multifactorial, raising the possibility that a multi-target/multi-drug strategy could be more effective than conventional monotherapy. This study takes a computational approach in finding combinations of approved drugs that are potentially more effective than single drugs in reducing microglial inflammation in AD. This novel approach exploits the distinct advantages of two different computer programming languages, one imperative and the other declarative. Existing programs written in both languages implement the same model of
We investigated the expression of the alpha- and beta-subunits of the lysosomal enzyme beta-N-acetylhexosaminidase in the BV-2 microglial cell line under different culture conditions. Beta-N-acetylhexosaminidase from BV-2 microglia cells was separated into its constituent isoenzymes on diethylaminoethyl (DEAE) cellulose, and its activity was monitored with 4-methylumbelliferyl-beta-N-acetylglucosamine and 4-methylumbelliferyl-beta-N-acetylglucosamine-6-sulphate substrates. Forms corresponding to the mouse isoenzymes A and B were present in the cells incubated in serum-supplemented medium as well as in serum-free medium. Lipopolysaccharide, a well-known activator of microglia in vitro, added to the BV-2 cells in serum-supplemented medium induced a decrease in the specific enzymatic activity determined with the 4-methylumbelliferyl-beta-N-acetylglucosamine substrate. Lipopolysaccharide had no effect on hexosaminidase isoenzyme pattern of BV-2 cells in serum-supplemented medium. The level of ...
Diabetic retinopathy induces an inflammatory response in the retina characterized by an increase in inflammatory cytokines and the activation of microglia. The degree of microglia activation may influence the extent of retina injury following retinal metabolic stress. We have previously shown that DR rats have elevated levels of advanced glycation end products (AGEs) in their blood. We have also suggested that AGEs might be involved in microglial activation and production of tumor necrosis factor alpha (TNF alpha). In this study, we attempted to confirm that AGEs induce the release of TNF alpha from rat retinal microglia using an in vitro microglia culture system, and concurrently to explore the mediating mechanisms. AGEs increased the protein secretion and mRNA expression of TNF alpha in cultured rat retinal microglia. These effects of AGEs were primarily mediated by reactive oxygen species (ROS). Furthermore, the inhibitors for mitogen-activated protein kinases (MAPK; p38, JNK and ERK 1/2) and ...
A DAP12-Dependent Signal Promotes Pro-Inflammatory Polarization in Microglia Following Nerve Injury and Exacerbates Degeneration of Injured NeuronsA DAP12-Dependent Signal Promotes Pro-Inflammatory Polarization in Microglia Following Nerve Injury and Exacerbates Degeneration of Injured Neurons ...
The accumulation of phagocytic microglia in the brain could be good or bad for AD patients. Some evidence suggests the microglia can eat up Aβ and clear plaques, but their activation can also lead to harmful neuroinflammation (see ARF related news story). A new report from Joseph El Khoury and colleagues of Harvard Medical School, published this week in the Journal of Neuroscience, finds a way to reconcile these two opposing functions. By tracking gene expression over time in microglia freshly isolated from AD mouse models, El Khoury and coauthors Suzanne Hickman and Elizabeth Allison report that the cells seem to start out by battling the buildup of amyloid. However, over time, the microglia lose their ability to take up and degrade Aβ, and instead show increased expression of inflammatory cytokines. The Alzforum previously reported on some of the data after they were presented last fall in Boston (see ARF related news story).. "We have found in the past that microglia can be both protective ...
The activation of microglia, resident immune cells of the central nervous system, and inflammation-mediated neurotoxicity are typical features of neurodegenerative diseases, for example, Alzheimers and Parkinsons diseases. An unexpected role of caspase-3, commonly known to have executioner role for apoptosis, was uncovered in the microglia activation process. A central question emerging from this finding is what prevents caspase-3 during the microglia activation from killing those cells? Caspase-3 activation occurs as a two-step process, where the zymogen is first cleaved by upstream caspases, such as caspase-8, to form intermediate, yet still active, p19/p12 complex; thereafter, autocatalytic processing generates the fully mature p17/p12 form of the enzyme. Here, we show that the induction of cellular inhibitor of apoptosis protein 2 (cIAP2) expression upon microglia activation prevents the conversion of caspase-3 p19 subunit to p17 subunit and is responsible for restraining caspase-3 in ...
Microglia are innate immune cells that survey the central nervous system (CNS) and respond almost immediately to any disturbance in CNS homeostasis. They are derived from primitive yolk sac myeloid progenitors and in the mouse colonize the CNS during fetal development. As a population, microglia have the potential to expand rapidly in response to inflammatory stimuli, injury, or any other pathological changes, due to a high capacity for proliferation. In addition, apoptotic mechanisms can be evoked to retract the microglial population, as reactivity declines. In the normal CNS, a low rate of proliferation and apoptosis maintain a low rate of microglial turnover. Here, we describe quantitative analysis of proliferation and apoptosis of microglial cells isolated from individual adult mice by flow cytometry, which allows distinction from perivascular or infiltrating macrophages, based on differential expression of CD45. These methods can be applied to analyze microglial turnover in various models ...
In this study, we investigated the effect of Teri and MMF in the context of HIV-mediated monocyte/microglial inflammation due to their well characterized anti-inflammatory properties. The ultimate goal was to reduce inflammation-related neurotoxicity. We demonstrate that Teri and MMF lead to reduced chemotactic and pro-inflammatory cytokine secretion in a co-culture system of microglia with HIV-transduced monocytoid cells. This was associated with reduced neurotoxicity of supernatant in human fetal neurons.. One limitation of this study is the use of monocytoid and microglial cell lines. However, our experiments performed with primary adult human microglia corroborated data generated using the HMC3 microglia cell line. Also, similar to the results obtained with primary embryonic microglia [4], HMC3 secrete more CXCL10, CCL5, CCL2, and IL-6 in contact with HIV vector-transduced monocytoid cells than after contact with HIV particles alone. This finding as well as lack of neurotoxicity of microglia ...
As a consequence of aging, the brain is subject to chronic neuroinflammatory conditions. The resident immune cells of the brain, microglia, act similarly to peripheral macrophages to protect the brain from insults, infection, and physical trauma. However, without proper regulation of their respective host defense mechanisms, these actions can become neurotoxic. In the healthy brain neurons have several signaling systems that directly interact with microglia in order to maintain a calming influence upon their actions, one of particular interest is the chemokine CX3CL1. This chemokine is found predominantly on neurons, while its cognate receptor CX3CR1 is found exclusively on microglia. There has been a recent surge in literature as to the exact role CX3CL1 signaling plays various physiological and neuropathological animal models, with still no well-defined role. In an attempt to address the current discordance regarding the role of CX3CL1 signaling we have used three different models. The first examines
Microglia are multifunctional cells that are key players in brain development and homeostasis. Recent years have seen tremendous growth in our understanding of the role microglia play in neurodegeneration, CNS injury, and developmental disorders. Given that microglia show diverse functional phenotypes, there is a need for more precise tools to characterize microglial states. Here, we experimentally define gene modules as the foundation for describing microglial functional states. In an effort to develop a comprehensive classification scheme, we profiled transcriptomes of mouse microglia in a stimulus panel with 96 different conditions. Using the transcriptomic data, we generated fine-resolution gene modules that are robustly preserved across datasets. These modules served as the basis for a combinatorial code that we then used to characterize microglial activation under various inflammatory stimulus conditions. The microglial gene modules described here were robustly preserved, and could be applied to
Diabetic patients are prone to developing Alzheimers disease (AD), in which microglia play a critical role. However, the direct effect of high glucose (HG) on microglia and the role of extracellular-signal-regulated kinase 5 (ERK5) signaling in this interaction have not been examined before. Here, these questions were addressed in microglia cultured in HG versus normal glucose (NG) conditions. Initially, HG induced microglial differentiation into the M2a phenotype with concomitant ERK5 activation. However, longer exposure to HG further induced differentiation of microglia into the M2b-like phenotype, followed by the M1-like subtype, concomitant with a gradual loss of ERK5 activation. BIX021895, a specific inhibitor of ERK5 activation, prevented M2a- differentiation of microglia, but induced earlier M2b-like polarization followed by M1-like polarization. Transfection of microglia with a sustained activated form of MEK5 (MEK5DD) prolonged the duration of the M2a phenotype, and prevented later
Microglial cells undergo cell division in vitro, as well as in vivo after brain injury. Mitotic activity of microglia suggests that they have limited life spans and rely on self-renewal to replace senescent cells. In the current study we examined long-term effects of antioxidants vitamin E and alpha-lipoic acid on cultured rat microglia with respect to proliferative ability, telomere length, telomerase activity, and interleukin-1beta (IL-1beta) production. We report that vitamin E induces dramatic microglial proliferation, as measured by MTT assay and BrdU incorporation, surpassing that of the well-known microglial mitogen granulocyte macrophage-colony stimulating factor, and therefore establishing vitamin E as the most potent, known mitogen for microglia in vitro ...
Masitinib is a selective, oral tyrosine kinase inhibitor with neuroprotective capability demonstrated via numerous preclinical studies. Two of masitinibs main cellular targets are the mast cell and microglia cell. It is well-established that mast cells play a prominent role in neuroinflammatory processes. Microglia, resident immune cells of the central nervous system (CNS), also constitute an important source of neuroinflammatory mediators and may have fundamental roles in numerous neurodegenerative disorders. The development of masitinib in ALS is therefore based on the pharmacological action of masitinib in microglia cells and mast cells, thereby slowing microglial-related disease progression, reducing neuro-inflammation, and modulating the neuronal microenvironment in both central and peripheral nervous systems. This is a multicenter, double-blind, randomized, placebo-controlled, parallel-group (two ascending dose titrations of masitinib and matching placebo), comparative study of oral ...
In short, the microglia are the resident immune cells within the central nervous system. They are known to exist in two different states, and while in the "surveillance mode", they play a key role in both cleaning up debris such as dead neurons (brain cells), in addition to fighting off infection within the nervous system. That "surveillance mode" role of the microglia, can be shifted into an inflammatory and destructive state where they secrete toxic substances (glutamate) and break down the neurons. That destructive state is referred to as "microglial activation". Research indicates that the bodys ability to maintain adequate amounts of antioxidants, in particular glutathione and superoxide dismutase, play key roles in determining the threshold by which the microglia may be shifted into the destructive activation state.(12). To reiterate a previous post, the role that Monsanto plays in microglial activation is related to the fact that their genetically modified crops (corn, soy, canola, sugar ...
In short, the microglia are the resident immune cells within the central nervous system. They are known to exist in two different states, and while in the "surveillance mode", they play a key role in both cleaning up debris such as dead neurons (brain cells), in addition to fighting off infection within the nervous system. That "surveillance mode" role of the microglia, can be shifted into an inflammatory and destructive state where they secrete toxic substances (glutamate) and break down the neurons. That destructive state is referred to as "microglial activation". Research indicates that the bodys ability to maintain adequate amounts of antioxidants, in particular glutathione and superoxide dismutase, play key roles in determining the threshold by which the microglia may be shifted into the destructive activation state.(12). To reiterate a previous post, the role that Monsanto plays in microglial activation is related to the fact that their genetically modified crops (corn, soy, canola, sugar ...
Abstract. It is now well appreciated that the immune system, in addition to its traditional role in defending the organism against pathogens, communicate in a well-organized fashion with the brain to maintain homeostasis and regulate a set of neural functions. Perturbation in this brain-immune interactions due to inflammatory responses may lead to psychiatric and neurological disorders. Microglia are one of the essential cells involved in the brain-immune interactions. Microglial cells are now not simply regarded as resident tissue macrophages in the brain. These cells are derived from myeloid progenitor cells in the yolk sac in early gestation, travel to the brain parenchyma and interact actively with neurons during the critical period of neurogenesis. Microglia provide a trophic support to developing neurons and take part in the neural wiring through the activity-dependent synapse elimination via direct neuron-microglia interactions. Altered microglial functions including changes in the gene ...
Age is the greatest risk factor for visceral adiposity, inflammation and metabolic disease. Tissue resident immune cells are critical players in maintaining tissue homeostasis, but also in permitting or driving the dysregulation and loss of metabolic capacity that is seen in aged individuals. There are a number of transcriptional, epigenetic, proteomic (etc) that may occur within immune cells that contribute to their ability to promote inflammation and drive metabolic disease. The lab has previously identified roles for adipose tissue macrophages and adipose tissue B cells that are still incompletely understood, but seem to involve inflammasome-driven changes and the resulting changes in cell frequency. The Camell lab will continue to investigate tissue resident immune cells and the cellular and molecular mechanisms that drive impaired metabolic capacity in adipose tissue.. We are seeking a post-doc to join our growing team. The individual will take on projects that focus on candidate ...
Primary cultures of mouse microglia were exposed to TLR agonists: tripalmitoyl-S-glyceryl-cysteine (Pam3CSK4 at 0.1 μg/ml; TLR2), endotoxin (LPS at 0.01 μg/ml; TLR4) and oligonucleotides containing unmethylated cytosin-guanosin motifs (CpG at 1 μg/ml; TLR9) for 24 h. TLR agonists were used at the lowest concentrations inducing the maximum stimulation of microglia cells in terms of NO release. After stimulation, cultures were challenged with two S. pneumoniae strains: the encapsulated D39 or the unencapsulated R6 strains were added at a ratio of 100 bacteria per cell. Phagocytosis was left to proceed for 30 and 90 min at 37°C + 5% CO2. For phagocytosis inhibition studies, 10 μM cytochalasin D (CD) was used. After washing, the microglial cultures were incubated in medium containing gentamicin (200 μg/ml) for 1 h to kill extracellular bacteria. Thereafter, cells were washed and lysed with distilled water. Viable intracellular bacteria were enumerated by quantitative plating of serial 10-fold ...
TAM tyrosine kinases play multiple functional roles, including regulation of the target genes important in homeostatic regulation of cytokine receptors or TLR-mediated signal transduction pathways. In this study, we show that TAM receptors affect adult hippocampal neurogenesis and loss of TAM receptors impairs hippocampal neurogenesis, largely attributed to exaggerated inflammatory responses by microglia characterized by increased MAPK and NF-κB activation and elevated production of proinflammatory cytokines that are detrimental to neuron stem cell proliferation and neuronal differentiation. Injection of LPS causes even more severe inhibition of BrdU incorporation in the Tyro3−/−Axl−/−Mertk−/− triple-knockout (TKO) brains, consistent with the LPS-elicited enhanced expression of proinflammatory mediators, for example, IL-1β, IL-6, TNF-α, and inducible NO synthase, and this effect is antagonized by coinjection of the anti-inflammatory drug indomethacin in wild-type but not TKO ...
Microglial cells are the resident tissue macrophages of the CNS and are widely recognized for their immune surveillance of the healthy CNS. In addition to this well-accepted function, recent findings point to major roles for microglia in instructing and regulating the proper function of the neuronal networks in the adult CNS, but these cells are also involved in creating neuronal networks by orchestrating construction of the whole network during development. In this Review, we highlight recent findings about the steady-state functions of microglial cells, the factors that are important for physiological microglial function, and how microglia help to maintain tissue homeostasis in the CNS.. ...
Ia are activated within the formalin inflammatory pain model144. Within this extensively utilised inflammatory discomfort model, five formalin is injected subcutaneously in to the hind paw of a rat or mouse. Fu et al. observed spinal cord microglia activation, defined as enhanced immunoreactive signaling of microglia markers, following formalin Oxybuprocaine hydrochloride injection in male rats, starting on day 1 and peaking on day 7 post injection143. Interestingly, pre-treatment of neighborhood anesthetic bupivacaine will not block formalin-induced spinal cord microglia activation, despite the fact that it successfully blocks formalin-evoked pain behaviors145, indicating that the nociceptive input in the acute inflammatory response of formalin will not be necessary for spinal cord microglia activation. Subsequently, it was reported that p38 MAPK is activated within the spinal cord microglia just after formalin injection in male rats146, and this activation of p38 MAPK occurs in two phases147. ...
Microglia, the immunocompetent cells of the central nervous system (CNS), act as neuropathology sensors and are neuroprotective under physiological conditions. Microglia react to injury and degeneration with immune-phenotypic and morphological changes, proliferation, migration, and inflammatory cytokine production. An uncontrolled microglial response secondary to sustained CNS damage can put neuronal survival at risk due to excessive inflammation. A neuroinflammatory response is considered among the etiological factors of the major aged-related neurodegenerative diseases of the CNS, and microglial cells are key players in these neurodegenerative lesions. The retina is an extension of the brain and therefore the inflammatory response in the brain can occur in the retina. The brain and retina are affected in several neurodegenerative diseases, including Alzheimers disease (AD), Parkinsons disease (PD), and glaucoma. AD is an age-related neurodegeneration of the CNS characterized by neuronal and synaptic
Rat microglial interleukin-3.: Interleukin-3 (IL-3, multi-CSF) is a growth factor for a variety of hematopoietic progenitor cells. Recently, microglial cells, t
Purpose : We recently reported that retinal microglia in adult mice are maintained locally without significant contribution from hematopoiesis. An important emerging question is whether local paracrine factors in the retina are needed to help maintain normal microglia. We addressed this problem by focusing on CSF1R - a receptor required for microglia development and survival. By focusing on CSF1 and IL34, the known cognate ligands for CSF1R, we were able to expose important clues on how microglia are sustained under normal physiologic conditions. Methods : RNA was extracted from retina, skin, and lymph nodes of C57Bl/6 mice and used to measure mRNA levels of CSF1, IL34, and GAPDH. Separately, retinas from IL34 deficient mice (IL34LacZ/LacZ) and littermate controls (IL34LacZ/+) were harvested and fixed/frozen for immunofluorescence analysis. Cryosections were stained for Iba-1 (microglia) or Brn3a (retinal ganglion cells) and β-gal. Confocal images were collected for analysis. Results : For mRNA ...
Traditional concepts of microglia are currently changing (Hanisch and Kettenmann, 2007). Recent in vivo time-lapse imaging of microglia especially challenged the view of resting and activated microglia (Davalos et al., 2005; Nimmerjahn et al., 2005; Wake et al., 2009). Microglia are not resting or functionally dormant, as previously thought. They exert a highly active scanning behaviour of their motile processes. One important function of these resting or surveying microglia is the patrol of brain parenchyma to detect invasion of pathogens and other foreign material (Hanisch and Kettenmann, 2007). Surveying microglia also have another important function. They remove damaged structures such as apoptotic cells and obsolete synaptic connections from the extracellular space (Kreutzberg, 1996). Whereas the uptake of foreign material leads to microglial activation to engage an immunological response, ingestion of apoptotic bodies is associated with an anti-inflammatory reaction (Magnus et al., ...
Alzheimers disease (AD) is the most common form of dementia in elderly and is characterized by beta-amyloid (Abeta) aggregates forming plaques in the brain and neurofibrillary tangles. Abeta-oligomers in particular, cause neurotoxicity and cell death in AD brains. Abeta plaques in the AD brain are surrounded by activated microglia which implies an important role for these cells in the progression of AD. Therefore, microglia can be an interesting therapeutic target for AD but so far, no promising microglial therapies have been developed yet. It has been suggested that defects in synapses have a central role in age-associated changes in the central nervous system. Synapses are especially vulnerable to damage and age-related synaptic dysfunction is thought to precipitate neurological degeneration in neurodegenerative diseases such as AD.. Early in postnatal development neurons generate more synaptic connections than those that are retained in the adult brain tissue. Recently, it has been shown ...
We found mouse neural progenitor cells (NPCs) secrete a different set of signaling proteins than other brain cells and that they are capable of modulating the activation, proliferation and phagocytosis of the brains main immune cells, the microglia. NPC-derived vascular endothelial growth factor was necessary and sufficient to exert at least some of these effects in mice. Thus, neural precursor cells may not only be shaped by microglia, but also regulate microglia functions and activity ...
Six brains from patients with clinicopathologically verified AD (age, 67 to 88 years; five men and one woman) were used in this study. Ischemic lesions caused by atherosclerotic vascular changes were absent or, at most, minimal in these cases. Brain blocks from the temporal lobe were fixed in 4% paraformaldehyde for 2 days. After cryoprotection with 15% sucrose, 60-μm-thick floating sections were cut on a freezing microtome. The three-color immunolabeling was performed as described previously.14 Briefly, the affinity purified rabbit polyclonal IgG (E-50) against a synthetic peptide corresponding to residues 17 to 31 of Aβ was conjugated with biotin (Sp-1200, Vector). Before they were stained, sections were treated in formic acid (,99%) for 1 minute. After a preincubation with the blocking serum (5%, goat) in phosphate-buffered saline containing 0.3% Triton X-100, sections were incubated with the anti-von Willebrand factor (1:500, polyclonal IgG made in rabbit, DAKO) to label vascular ...
Brain diseases are a burdensome problem for modern societies. Not surprisingly, therefore, substantial resources are invested in neuroscience research, which depends heavily on animal models. In this respect, microglia have assumed an important role. Animals are sacrificed for brain excision and the collection of cells of in-vitro studies. Animals are also used for in-vivo experiments. Depending on the aim of the study and on the nature of the procedure adopted, the in-vivo animal experiments involve different levels of invasiveness and suffering, which may include injuries to the brain and the spinal cord, if microglial response to trauma is being investigated, as well as exposure to toxic and infectious agents. Most of these experiments are conducted with human diseases in mind, even though animal microglia behave in many respects differently to human ones. The need to improve human in-vitro models of microglia is thus pressing.. Microglia are the unique resident immune cells of the brain. ...
MPCs occur at a low-frequency so it is not surprising that they have not been previously described. We have serendipitously observed them in the cortex, hippocampus, amygdala, and striatum, suggesting that MPCs are a general feature of microglial behaviors in the brain. We found that both in slices and in vivo the kinetics of MPCs was local (microglia responded within 30 μm from the focal contact point), rapid (with processes extending at up to ∼2-4 μm/min) and transient (with focal contact lasting ∼4 min). At present, microglial functions upon focal contact are not clear. However, MPCs could be one of the homeostatic features of microglial activities.. With respect to the target(s) of MPCs, we found that such processes never targeted a microglial element. Astrocytes have been reported to sense extracellular calcium reductions in slices and release ATP (Torres et al., 2012). However, we failed to observe microglial process convergence toward SR101-labeled astrocytic elements. Because SR101 ...
Microglia and astrocytes contribute to Alzheimer’s disease (AD) etiology and may mediate early neuroinflammatory responses. Despite their possible role in disease progression and despite the fact that they can respond to amyloid deposition in model systems, little is known about whether astro- or microglia can undergo proliferation in AD and whether this is related to the clinical symptoms or to local neuropathological changes. Previously, proliferation was found to be increased in glia-rich regions of the presenile hippocampus. Since their phenotype was unknown, we here used two novel triple-immunohistochemical protocols to study proliferation in astro- or microglia in relation to amyloid pathology. We selected different age-matched cohorts to study whether proliferative changes relate to clinical severity or to neuropathological changes. Proliferating cells were found across the hippocampus but never in mature neurons or astrocytes. Almost all proliferating cells were colabeled with Iba1+,
Dendropanax morbifera (D. morbifera), a species endemic to Korea, is largely distributed throughout the southern part of the country. Its leaves, stems, roots, and seeds have been used as a form of alternative medicine for various diseases and neurological disorders including paralysis, stroke, and migraine. However, the molecular mechanisms that underlie the remedial effects of D. morbifera remain largely unknown. In this paper, extracts from D. morbifera leaves were prepared using ethyl acetate as a solvent (abbreviated as DMLE). The modulatory effects of DMLE on neuroinflammation were studied in a lipopolysaccharide (LPS)-stimulated BV2 murine microglial cell line. Production of pro-inflammatory cytokines, activation of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB), and different M1/M2 activation states of microglia were examined. DMLE treatment suppressed the production of pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α), interleukin-6 ...
TY - JOUR. T1 - Interferon regulatory factor 3 plays an anti-inflammatory role in microglia by activating the PI3K/Akt pathway. AU - Tarassishin, Leonid. AU - Suh, Hyeon Sook. AU - Lee, Sunhee C.. PY - 2011/12/30. Y1 - 2011/12/30. N2 - Background: Microglia are the principal cells involved in the innate immune response in the CNS. Activated microglia produce a number of proinflammatory cytokines implicated in neurotoxicity but they also are a major source of anti-inflammatory cytokines, antiviral proteins and growth factors. Therefore, an immune therapy aiming at suppressing the proinflammatory phenotype while enhancing the anti-inflammatory, growth promoting phenotype would be of great benefit. In the current study, we tested the hypothesis that interferon regulatory factor 3 (IRF3), a transcription factor required for the induction of IFNβ following TLR3 or TLR4 activation, is critical to the microglial phenotype change from proinflammatory to anti-inflammatory, and that this phenotype change ...
Define Microglial cells. Microglial cells synonyms, Microglial cells pronunciation, Microglial cells translation, English dictionary definition of Microglial cells. microglia cells. Translations. English: mi·crog·li·a cells, microglial cellsn. células de microglia, pequeñas células intersticiales.
a. Microglia in Normal and Injured CNSs. Microglia constitute a distinct glial population in the CNS [1-4]. Unlike neurons and macroglia that are of neuroepithelial origin, microglia are mesodermal (i.e., bone marrow) in origin and seed the brain early in embryogenesis: during development, mono-cytes migrate to the brain through the vessels located in specific regions of the brain. (called glial fountains in humans). These areas are concentrated around the subven-tricular zones where active neurogenesis occurs. These ameboid tissue macrophages then migrate throughout the entire brain parenchyma and differentiate into resident microglial cells. In the mature CNS, microglia are ubiquitously present as highly ramified cells (resting microglia) [5,6]. They respond to changes in the CNS microenvironment in a variety of disorders with or without the participation of the systemic monocytes. Although in degenerative disorders such as AD and Parkinsons disease there is little evidence to support ...
Alzheimers disease (AD), the most common form of dementia in the elderly, is characterized by the presence of extracellular plaques composed of amyloid β (Aβ) peptides and intracellular tau aggregates. The plaques are surrounded by microglia, the brains resident immune cells, which likely participate in the clearance of Aβ by phagocytosis. The microglia that are associated with plaques display an abnormal ameboid morphology and do not respond to tissue damage, in contrast to microglia in healthy brains. Here, we used time lapse confocal microscopy to perform a detailed real-time examination of microglial motility in acute hippocampal brain slices from the 5xFAD mouse model of AD, which was crossed to Cx3cr1 GFP/GFP mice to achieve microglia-specific GFP expression for visualization. During baseline conditions, microglia around plaques appeared hypermotile, moving the processes that were pointing away from plaques at higher speed than microglia not associated with plaques. Yet, neither ...
For todays neuropathologist it must be hard to believe that microglia were once considered an endangered species. Yet, a few years ago, it was suggested that the existence of the microglia is in doubt and that their name should be abandoned (1). What can be regarded a gross scientific error by todays standards (2,3) has a long and complicated history. Discovered independently by Nissl (4) and Robertson (5), microglia were first studied in detail by del Rio-Hortega (6). He also deserves the credit for establishing valuable knowledge on the role of microglia in CNS pathology. However, in the following years, and mainly due to a lack of cell type-specific markers, controversy arose around microglial embryonic development and their nature as well as their cellular identity. Thus, in the mid-1980s, microglia were rediscovered with the advent of immunocytochemistry and lectin markers. Meanwhile, the esoteric debate that surrounded microglia for decades had given way to research activity ...
TY - JOUR. T1 - Regulatory role of NADPH oxidase 2 in the polarization dynamics and neurotoxicity of microglia/macrophages after traumatic brain injury. AU - Wang, Jing. AU - Ma, Merry W.. AU - Dhandapani, Krishnan M.. AU - Brann, Darrell W.. PY - 2017/12. Y1 - 2017/12. N2 - Traumatic brain injury (TBI) is a leading cause of death and disability. Secondary injuries that develop after the initial trauma contribute to long-lasting neurophysiological deficits. Polarization of microglia/macrophages toward a pro-inflammatory (M1) phenotype may increase the progression of secondary injury following TBI; however, the regulatory and functional mechanisms underlying these changes remain poorly defined. In the present study, we showed elevated expression of NADPH oxidase 2 (NOX2) and activation of nuclear factor-kappa B (NF-κB) predominantly in microglia/macrophages at 4- and 7-days after controlled cortical impact in mice. Delayed inhibition of NOX2, beginning one day after TBI, reduced reactive oxygen ...
Glioma cells recruit and exploit microglia (the resident immune cells of the brain) for their proliferation and invasion ability. The underlying molecular mechanism used by glioma cells to transform microglia into a tumor-supporting phenotype has remained elusive. We found that glioma-induced microglia conversion was coupled to a reduction in the basal activity of microglial caspase-3 and increased S-nitrosylation of mitochondria-associated caspase-3 through inhibition of thioredoxin-2 activity, and that inhibition of caspase-3 regulated microglial tumor-supporting function. Furthermore, we identified the activity of nitric oxide synthase 2 (NOS2, also known as iNOS) originating from the glioma cells as a driving stimulus in the control of microglial caspase-3 activity. Repression of glioma NOS2 expression in vivo led to a reduction in both microglia recruitment and tumor expansion, whereas depletion of microglial caspase-3 gene promoted tumor growth. Our results provide evidence that inhibition ...
Innate immune signaling is important in the pathophysiology of ischemia/reperfusion (stroke) induced injury and recovery. Several lines of evidence support a central role for microglia in these processes. Recent work has identified Toll-like receptors (TLRs) and type I interferon (IFN) signaling in both ischemia/reperfusion-induced brain injury and ischemic preconditioning-mediated neuroprotection. To determine the effects of ischemia/reperfusion-like conditions on microglia we carried out genomic analyses on wild-type (WT) and TLR4-/- cultured microglia following sequential exposure to hypoxia/hypoglycemia and normoxia/normoglycemia (H/H-N/N). We observed increased expression of type 1 IFN-stimulated genes (ISGs) as the predominant transcriptomal feature of H/H-N/N-exposed WT, but not TLR4-/-, microglia. Microarray analysis on ex vivo sorted microglia from ipsilateral male mouse cortex following a transient in vivo ischemic pulse also demonstrated robust expression of ISGs. Type 1 IFNs, ...
Phagocytosis of axonal debris is shown by type 1 and 2 microglia. (A) A model of rat cortical explant culture is shown. After the chopped cortex (300-600 μm) was placed in a poly-l-lysine-coated dish, axons grew radially within 7 to 10 days. Explant was subjected to immunofluorescence analysis using an anti-Tuj1 antibody (green) and an anti-Iba1 antibody (red). Scale bar: 500 μm. (B) Coculture of microglia and axonal debris is shown. After primary microglia (4 × 105 cells/dish) were added to the explant culture dish, axons were transected with a scalpel blade (white dotted line). Scale bar: 200 μm. (C) Ninety-six hours after transection of the axons, immunostaining analysis was performed using anti-Tuj1 (green) and anti-Iba1 (red) antibodies. Nuclei were stained with DAPI (blue). Scale bar: 200 μm. (D) High-magnification view of the boxed region in C. Phagocytosed axonal debris was found within the microglia (arrows). Scale bar: 100 μm. (E, F) Type 1 or type 2 microglia (MG) were incubated ...