Changes In Microglial Cells Research Articles

Abstract P162: Senolytic Treatment Attenuates Palmitic Acid-Induced Microglial Activation: Therapeutic Implications for Obesity-Induced Sympathoexcitation

Objective: Microglial dysfunction has been previously implicated in the pathogenesis of obesity-induced neuroinflammation and sympathoexcitation, both of which significantly increase the risk for cardiovascular diseases. However, the mechanisms underlying obesity-induced glial dysfunction are not clear. In the current study, we investigated the role of cellular senescence that culminates in irreversible proliferative arrest and inflammatory phenotype, in obesity-induced glial dysfunction. Methods: Human microglial cells (n=6 wells/group/expt) were treated with 35 μM palmitic acid (PA) for 24 hours to mimic an obese microenvironment. Subsequently, the cells were treated with senolytic drugs, Dasatinib (250 nM) and Quercetin (100 μM) (D+Q) for 48 hours after PA treatment. Real-time PCR, lipid profiling, and senescence-associated beta-galactosidase (SAβGAL) were performed to evaluate changes in microglia to PA and D+Q treatment. Immunofluorescence staining evaluated microglial activation and vesicular glutamate transporter (VGLUT1) expression. Results: Microglial activation was confirmed by upregulation of Iba1 and CD11b in PA-treated cells. Significant upregulation of senescence genes (p16 and p21), senescence-associated secretory phenotypes (SASPs such as TNFα, MMP3), and SAβGAL staining in the PA treatment group indicating cellular senescence. PA treatment, significantly upregulated glutamate transporters EAAT1 and EAAT2 suggesting a potential adaptive response to counteract excitotoxicity. Bodipy and Oil-Red-O (ORO) staining revealed increased lipid accumulation in PA group, indicating altered lipid metabolism. D+Q group showed a significant decrease in senescence markers (p16 and p21) and SAβGAL staining, along with a reduction in lipid markers such as perilipin 1 and 2, and decreases in activated microglial markers IBA1 and CD11b. A significant decrease in EAAT1 expression was also observed. Immunofluorescence showed a significant decrease in VGLUT1 expression in the D+Q compared to PA-treated group. Conclusions: The findings suggest that palmitic acid-induced changes in human microglial cells can contribute to oxidative stress, cellular senescence, and alterations in glutamate clearance pathway potentially leading to sympathetic overactivity in obesity. Senolytic treatment (D+Q) mitigated PA-induced lipid accumulation and inflammatory changes in the microglial cells indicating a promising therapeutic strategy for managing sympathoexcitation in obesity.

Region-specific response of central microglial cells to sciatic nerve demyelination through sensory and motor pathways.

Peripheral nerve injury can cause changes in microglial cells on the spinal dorsal and ventral horns. This region-specific response implies that central microglial cells could be activated through both sensory and motor pathways. In order to further determine how peripheral nerve injury activates central microglial cells through neural pathways, the sciatic nerve was selected as the target for neural tract tracing and demyelination. Firstly, we used cholera toxin subunit B (CTB) to map the central sensory and motor territories of the sciatic nerve. Secondly, we applied lysophosphatidylcholine to establish the model of sciatic nerve demyelination and examined the distribution of activated microglial cells via immunofluorescence with ionized calcium-binding adapter molecule 1. It was shown that CTB labeling included the transganglionically labeled sensory afferents and retrogradely labeled somata of motor neurons along the sensory and motor pathways of the sciatic nerve ipsilateral to the injection, in which sensory afferents terminated on the gracile nucleus, Clarke's nucleus, and spinal dorsal horn, while motor neurons located on the spinal ventral horn. Consistently, after sciatic nerve demyelination, the activated microglial cells were observed in the same territories as CTB-labeling, showing shortened processes and enlarged cell bodies. These results support the idea that central microglia might be activated by signals from the demyelinated sciatic nerve through both sensory and motor pathways.

INFLUENCE OF FIBROBLAST GROWTH FACTOR-2 ON THE ACTIVATION OF MOUSE HIPPOCAMPAL MICROGLIA IN A LIPOPOLYSACCHARIDE-INDUCED NEUROINFLAMMATION MODEL IN VITRO

Introduction. Activation of the pro-inflammatory phenotype of microglia may be one of the causes of chronic neuroinflammation and, as a result, can lead to pathological conditions of the brain. The use of neurotrophic factors, such as FGF2, may become one of the promising methods for correcting neurodegenerative diseases, but the question of the influence of this factor on microglia activation is still open. The purpose of this work was to study the effect of FGF2 on the activation of mouse hippocampal microglia in an in vitro model of neuroinflammation induced by lipopolysaccharide. Material and methods. The study was carried out on a culture of primary mixed glial cells of the mouse hippocampus. To quantify, area, and morphological changes in microglial cells in response to the effects of LPS and FGF2, immunocytochemical analysis was performed for markers of astrocytes (GFAP) and microglia (Iba-1). Analysis of the expression level of IL-1β, IL-6, IL-10, TNF-α was carried out by quantitative PCR. Results. In response to LPS exposure, there was an increase in the percentage of Iba-1+ cells, their surface area, changes in morphological characteristics, together with an increase in the level of expression of pro-inflammatory cytokines IL-1β, IL-6, TNF-α and anti-inflammatory cytokine IL-10 both within 6, so 12 hours of exposition. The addition of FGF2 led to a decrease in the percentage of Iba-1+ cells in culture and a decrease in the surface area of microglia. A decrease in the relative level of expression of IL-1β and IL-6 was noted in the groups where LPS and FGF2 were added, while the expression of TNF-α did not change. With an increase in cultivation time up to 12 hours, an increased expression of IL-10 was detected in this group. Conclusion. Stimulation with LPS promotes the transition of microglia from a resting to an activated pro-inflammatory phenotype, as evidenced by increased proliferative activity of Iba-1+ cells in combination with an increase in the level of expression of pro-inflammatory cytokines. Inhibition of two of the three pro-inflammatory cytokines (IL-1β and IL-6) and a significant increase in the level of IL-10 in cell culture suggests an anti-inflammatory effect of FGF2.

Sitagliptin, an anti‐diabetic drug, inhibits the pro‐inflammatory microglia reactivity via dipeptidyl peptidase‐4 (DPP4)

Aims/Purpose: Diabetic retinopathy is characterized by a chronic low‐grade retinal neuroinflammation triggered by diabetes and mediated, at least in part, by microglial cells. We previously showed that sitagliptin, an oral drug for type 2 diabetes, developed to inhibit dipeptidyl peptidase 4 (DPP4) and increase insulin release, can prevent retinal neuroinflammation in diabetic rat models and the LPS‐induced morphological changes of microglial cells in retinal organotypic cultures. However, the mechanisms underlying these effects are not clarified. We hypothesize that sitagliptin is able to directly inhibit microglia reactivity via Dpp4.Methods: BV‐2 microglia cell line was exposed to a non‐toxic dose of lipopolysaccharide (LPS, 0.1 μg/mL) in the presence or absence of 200 μM sitagliptin. The expression of Dpp4, iNOS, IL‐1 beta and TNF were assessed by Western Blot and/or RT‐qPCR. The BV‐2 phagocytic efficiency was assessed using fluorescent microbeads. The metabolic activity and proliferation of BV‐2 cells were assessed by resazurin assay and Edu staining, respectively. Dpp4 deletion in BV‐2 cells was generated using Crispr‐cas9 method.Results: Sitagliptin inhibited the LPS‐induced increase in protein levels of iNOS, IL‐1 beta and TNF to 39.9 ± 6.3%, 47.2 ± 8.1% and 34.0 ± 7.2%, respectively, comparing to LPS. Sitagliptin reduced the LPS‐induced increase in phagocytic efficiency by approximately 40%. Sitagliptin did not affect the metabolism and proliferation of BV‐2. BV‐2 cells express Dpp4. Dpp4 deletion does not affect the LPS‐induced phagocytosis but abrogated the effect of sitagliptin on the reduction of BV‐2 phagocytic efficiency (approx. 320% as in LPS).Conclusions: Sitagliptin exerts direct anti‐inflammatory effects on microglia, mediated by DPP4. These results suggest that sitagliptin can potentially be used in retinal pathologies characterized by microglia‐mediated neuroinflammation.Support.FCT‐Portugal: PEst UID/NEU/04539/2013, UIDB/04539/2020 and UIDP/04539/2020 and PTDC/NEU‐OSD/1113/2012. COMPETE‐FEDER.

Prenatal infection and adolescent social adversity affect microglia, synaptic density, and behavior in male rats

Maternal infection during pregnancy and childhood social trauma have been associated with neurodevelopmental and affective disorders, such as schizophrenia, autism spectrum disorders, bipolar disorder and depression. These disorders are characterized by changes in microglial cells, which play a notable role in synaptic pruning, and synaptic deficits. Here, we investigated the effect of prenatal infection and social adversity during adolescence – either alone or in combination – on behavior, microglia, and synaptic density. Male offspring of pregnant rats injected with poly I:C, mimicking prenatal infection, were exposed to repeated social defeat during adolescence. We found that maternal infection during pregnancy prevented the reduction in social behavior and increase in anxiety induced by social adversity during adolescence. Furthermore, maternal infection and social adversity, alone or in combination, induced hyperlocomotion in adulthood. Longitudinal in vivo imaging with [11C]PBR28 positron emission tomography revealed that prenatal infection alone and social adversity during adolescence alone induced a transient increase in translocator protein TSPO density, an indicator of glial reactivity, whereas their combination induced a long-lasting increase that remained until adulthood. Furthermore, only the combination of prenatal infection and social adversity during adolescence induced an increase in microglial cell density in the frontal cortex. Prenatal infection increased proinflammatory cytokine IL-1β protein levels in hippocampus and social adversity reduced anti-inflammatory cytokine IL-10 protein levels in hippocampus during adulthood. This reduction in IL-10 was prevented if rats were previously exposed to prenatal infection. Adult offspring exposed to prenatal infection or adolescent social adversity had a higher synaptic density in the frontal cortex, but not hippocampus, as evaluated by synaptophysin density. Interestingly, such an increase in synaptic density was not observed in rats exposed to the combination of prenatal infection and social adversity, perhaps due to the long-lasting increase in microglial density, which may lead to an increase in microglial synaptic pruning. These findings suggest that changes in microglia activity and cytokine release induced by prenatal infection and social adversity during adolescence may be related to a reduced synaptic pruning, resulting in a higher synaptic density and behavioral changes in adulthood.

A Distinct Microglial Cell Population Expressing Both CD86 and CD206 Constitutes a Dominant Type and Executes Phagocytosis in Two Mouse Models of Retinal Degeneration.

Microglial cells are the key regulators of inflammation during retinal degeneration (RD) and are conventionally classified as M1 or M2. However, whether the M1/M2 classification exactly reflects the functional classification of microglial cells in the retina remains debatable. We examined the spatiotemporal changes of microglial cells in the blue-LED and NaIO3-induced RD mice models using M1/M2 markers and functional genes. TUNEL assay was performed to detect photoreceptor cell death, and microglial cells were labeled with anti-IBA1, P2RY12, CD86, and CD206 antibodies. FACS was used to isolate microglial cells with anti-CD206 and CD86 antibodies, and qRT-PCR was performed to evaluate Il-10, Il-6, Trem-2, Apoe, and Lyz2 expression. TUNEL-positive cells were detected in the outer nuclear layer (ONL) from 24 h to 72 h post-RD induction. At 24 h, P2RY12 was decreased and CD86 was increased, and CD86/CD206 double-labeled cells occupied the dominant population at 72 h. And CD86/CD206 double-labeled cells showed a significant increase in Apoe, Trem2, and Lyz2 levels but not in those of Il-6 and Il-10. Our results demonstrate that microglial cells in active RD cannot be classified as M1 or M2, and the majority of microglia express both CD86 and CD206, which are involved in phagocytosis rather than inflammation.

Moderate intrinsic phenotypic alterations in C9orf72 ALS/FTD iPSC-microglia despite the presence of C9orf72 pathological features.

While motor and cortical neurons are affected in C9orf72 amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD), it remains largely unknown if and how non-neuronal cells induce or exacerbate neuronal damage. We differentiated C9orf72 ALS/FTD patient-derived induced pluripotent stem cells into microglia (iPSC-MG) and examined their intrinsic phenotypes. Similar to iPSC motor neurons, C9orf72 ALS/FTD iPSC-MG mono-cultures form G4C2 repeat RNA foci, exhibit reduced C9orf72 protein levels, and generate dipeptide repeat proteins. Healthy control and C9orf72 ALS/FTD iPSC-MG equally express microglial specific genes and perform microglial functions, including inflammatory cytokine release and phagocytosis of extracellular cargos, such as synthetic amyloid beta peptides and healthy human brain synaptoneurosomes. RNA sequencing analysis revealed select transcriptional changes of genes associated with neuroinflammation or neurodegeneration in diseased microglia yet no significant differentially expressed microglial-enriched genes. Moderate molecular and functional differences were observed in C9orf72 iPSC-MG mono-cultures despite the presence of C9orf72 pathological features suggesting that a diseased microenvironment may be required to induce phenotypic changes in microglial cells and the associated neuronal dysfunction seen in C9orf72 ALS/FTD neurodegeneration.

Morphological comparison of the microglial cell population between organotypic retinal cultures and axotomised retinas in vivo

AbstractPurpose: Retinal organotypic cultures (ROCs) have been used since the early 1930s as in vivo surrogates to study retinal ganglion cell (RGC) loss and neuroprotection. In this work we purposed to analyse and compare the morphological changes of microglial cells (MCs) along time in ROCs and axotomised retinas.Methods: C57/Bl6 mice were used. For the in vitro model, retinas were dissected and cultured in supplemented medium. In the in vivo model, the left optic nerve (ONC) was crushed. In both models, retinas were analysed at 24‐h intervals for up to 7 days. MCs were then immunodetected with anti‐Iba1 antibody and then photographed in the ganglion cell layer (GCL) of the retina using a confocal microscope. Finally, their morphology was quantitatively analysed using the free Image J Fiji software.Results: After ONC, the number of MC processes decreased significantly from day 1 to 7 compared to intact retinas. Similarly, we observed a significant decrease in the number of processes of in vitro MCs, which was significantly greater than after axotomy in vivo The total length of the processes decreased in both models up to 7 days. When studying the size of the MCs, it was observed that from 1 to 7 days MCs were bigger in vitro than in vitro and in both models than in intact retinas.Conclusions: The morphology of MCs differs in vivo and in vitro, suggesting a differential activation.

Raman spectroscopy based molecular signatures of methamphetamine and HIV induced mitochondrial dysfunction

METH and HIV Tat treatment results in increased oxidative stress which affects cellular metabolism and causes DNA damage in the treated microglia. Both, METH ± HIV Tat impair mitochondrial respiration, leading to dysfunction in bioenergetics and increased ROS in microglial cells. Our data indicate that mitochondrial dysfunction may be key to the METH and/or HIV Tat-induced neuropathology. METH and/or HIV Tat induced changes in the protein, lipid and nucleotide concentration in microglial cells were measured by Raman Spectroscopy, and we speculate that these fundamental molecular-cellular changes in microglial cells contribute to the neuropathology that is associated with METH abuse in HIV patients.

Axial resolution improvement of two-photon microscopy by multi-frame reconstruction and adaptive optics.

Two-photon microscopy (TPM) has been widely used in biological imaging owing to its intrinsic optical sectioning and deep penetration abilities. However, the conventional TPM suffers from poor axial resolution, which makes it difficult to recognize some three-dimensional fine features. We present multi-frame reconstruction two-photon microscopy (MR-TPM) using a liquid lens as a fast axial scanning engine. A sensorless adaptive optics (AO) approach is adopted to correct the aberrations caused by both the liquid lens and the optical system. By overcoming the effect of optical aberrations, inadequate sampling, and poor focusing capability of a conventional TPM, the axial resolution can be improved by a factor of 3 with a high signal-to-noise ratio. The proposed technology is compatible with the conventional TPM and requires no optical post-processing. We demonstrate the proposed method by imaging fluorescent beads, in vitro imaging of the neural circuit of mouse brain slice, and in vivo time-lapse imaging of the morphological changes of microglial cells in septic mice model. The results suggest that the axon of the neural circuit and the process of microglia along the axial direction, which cannot be resolved using conventional TPM, become distinguishable using the proposed AO MR-TPM.

A maternal Western diet during gestation and lactation modifies offspring’s microglial cell density and morphology in the hippocampus and prefrontal cortex in Yucatan minipigs

Changes in microglial development and morphology can be induced by inflammatory conditions and associated with eating or mood disorders, such as hyperphagia or depression. In a previous paper in the minipig model, we showed that maternal Western diet during gestation and lactation decreased hippocampus neurogenesis and food-rewarded cognitive abilities in the progeny. Whether these alterations are concomitant with a central inflammatory process in brain structures involved in learning and memory (hippocampus, HPC), cognitive (prefrontal cortex, PFC), or hedonic (orbitofrontal cortex, OFC) control of food intake is still unknown. In the present study, Yucatan minipigs (Sus scrofa) sows were exposed to two different diets during gestation and lactation (standard, SD N = 7 vs. Western diet, WD N = 9). Iba1 is a calcium-binding protein specifically expressed in microglia in the brain, which plays an important role in the regulation of the microglia function. Iba1 expression was examined by immunohistochemical analyses in the PFC, OFC and HPC of piglets. The density of microglial cells, as well as their morphology, were assessed in order to have an indirect insight of microglial cell activation state possibly in relationship with neuroinflammation. The density of Iba1-positive cells was higher in the PFC but not in the HPC of WD compared to SD piglets (p < 0.001). In the HPC, anterior and dorsolateral PFC, WD piglets had more unipolar cells, contrary to SD that had more multipolar cells (P < 0.0001). Opposite effects were observed in the OFC, with SD presenting more unipolar (P < 0.001) microglial cells compared to WD. We showed here that maternal diet during pregnancy and lactation had significant effects on morphological changes of microglial cells in the offspring, and that these effects differed between the HPC and PFC, suggesting different response mechanisms to the early nutritional environment.

Identification of Microglial Cell Molecular Markers During Chick Embryo Brain Development and Human Xenograft Tumor Formation

Glioblastoma (GBM) is the most aggressive and invasive human brain tumor, which despite advancement in surgery and immunology, only 10% of patients survive 18 months after diagnosis. The Galileo lab studies GBM, focusing on the role of the protein L1CAM on increasing the motility, proliferation, and invasiveness of GBM cells using in vitro cell tracking and a novel xenograft chick embryo brain tumor model. The work here focused on microglial cells, which are resident brain immune system cells that are not well understood. Studies in rodents and GBM patients showed that microglia play a critical role in promoting GBM growth via an activation of complex network of cytokines, chemokines and other metabolic factors that occur in the extracellular matrix. In the context of brain tumors, microglia promote neuroinflammation, which induces the BBB breakdown and inhibits antitumor immune responses. The first aim for my project was to find biomarkers that specifically identify microglial cells in normal chick embryo brain during development. The second aim was to use those markers in xenograft tumors in the chick embryo brain to look for any proinflammatory changes in microglial cells. Chick embryo brains were fixed, frozen, and cut into serial cryostat sections or fixed and vibratome sectioned, followed by immunofluorescent staining using antibodies or lectins that specifically identified microglial cells and endothelial cells in other model organisms. The optimal staining protocol required overnight primary antibody/lectin with 0.1% Triton X‐100 detergent and 5% normal goat serum in phosphate buffered saline. The antibodies and lectins investigated included Isolectin B4, Tomato (Lycopersicon esculentum) lectin, anti‐ferritin, anti‐laminin and CD45. Immunofluorescence analysis revealed CD45 to stain microglial cells with the most specificity. CD45 staining reveal microglial cell morphology to progressively change from a compact ameboid shape (E5) into ramified branched shape (E12 and E15). In addition to the increased quantity of ramified microglial cells in chick brain with xenograft human tumors, the microglia also appeared to be localized near endothelia. Further investigations are needed to verify the increased presence of reactive microglial cells and their interaction with tumor cells and angiogenesis.Support or Funding InformationThis work was supported by the Delaware INBRE program, with a grant from the National Institute of General Medical Sciences‐NIGMS (8 P20 GM103446‐16) from the National Institutes of Health, a grant to DSG from the National Cancer Institute, and a generous gift from Pamela S. Simpson ‘97 Translational Cancer Research Fund. I would like to thank Tyler Hellmig and Emily Kollenbroich for their guidance.

Granulins Regulate Aging Kinetics in the Adult Zebrafish Telencephalon.

Granulins (GRN) are secreted factors that promote neuronal survival and regulate inflammation in various pathological conditions. However, their roles in physiological conditions in the brain remain poorly understood. To address this knowledge gap, we analysed the telencephalon in Grn-deficient zebrafish and identified morphological and transcriptional changes in microglial cells, indicative of a pro-inflammatory phenotype in the absence of any insult. Unexpectedly, activated mutant microglia shared part of their transcriptional signature with aged human microglia. Furthermore, transcriptome profiles of the entire telencephali isolated from young Grn-deficient animals showed remarkable similarities with the profiles of the telencephali isolated from aged wildtype animals. Additionally, 50% of differentially regulated genes during aging were regulated in the telencephalon of young Grn-deficient animals compared to their wildtype littermates. Importantly, the telencephalon transcriptome in young Grn-deficent animals changed only mildly with aging, further suggesting premature aging of Grn-deficient brain. Indeed, Grn loss led to decreased neurogenesis and oligodendrogenesis, and to shortening of telomeres at young ages, to an extent comparable to that observed during aging. Altogether, our data demonstrate a role of Grn in regulating aging kinetics in the zebrafish telencephalon, thus providing a valuable tool for the development of new therapeutic approaches to treat age-associated pathologies.

Differential Effects of LPS and 6-OHDA on Microglia's Morphology in Rats: Implications for Inflammatory Model of Parkinson's Disease.

Parkinson's disease (PD) is an idiopathic and progressive neurodegenerative disease characterized by the loss of ~ 80% of dopaminergic neurons in substantia nigra pars compacta (SNpc). Because activation of the innate cellular immune response, mediated by microglia, has been linked to the neurodegeneration in PD, in the present study, we evaluated the effects of lipopolysaccharide (LPS) and 6-hydroxydopamine (6-OHDA) on microglia's morphology, reflective of their activity, as well as tyrosine hydroxylase (TH)-positive neurons in SNpc and motor behavior. Adult male Wistar rats were stereotactically injected with LPS or 6-OHDA into the left dorsolateral striatum. Control groups received appropriate vehicle. The morphological changes of microglial cells and neurotoxic effects were examined at 1, 7, and 14 post-injection days. Both LPS and 6-OHDA caused activation and morphological changes in microglial cells as well as loss of dopaminergic neurons in SNpc. These effects were maximal at 14days post-injection where motor impairments were also evident. However, our findings indicate that 6-OHDA causes a low degree of microglia activation compared to LPS. Hence, it may be concluded that LPS model of PD might be a better representation of inflammatory involvement in this devastating disease.

Glucocorticoid-Driven NLRP3 Inflammasome Activation in Hippocampal Microglia Mediates Chronic Stress-Induced Depressive-Like Behaviors.

Chronic stress is a key risk factor for depression, and microglia have been implicated in the pathogenesis of the disease. Recent studies show that the Nod-like receptor protein 3 (NLRP3) inflammasome is expressed in microglia and may play a crucial role in depression. However, the mechanism of NLRP3 inflammasome activation in hippocampal microglia and its role in depressive-like behaviors remain poorly understood. In this study, rats were subjected to 6 h of restraint stress per day for 21 days to produce a model of stress-induced depression. Behavioral tests and serum corticosterone were used to assess the success of the model. Furthermore, HAPI cells were pretreated with dexamethasone (5 × 10–7 M) to assess stress-induced changes in microglial cells in culture. The microglial marker Iba-1, reactive oxygen species (ROS), nuclear factor kappa B (NF-κB) and key components of the NLRP3 inflammasome and its downstream inflammatory effectors (IL-1β and IL-18) were measured. Chronic stress induced depressive-like behavior, increased serum corticosterone levels and produced hippocampal structural changes. Chronic stress and dexamethasone both increased Iba-1 expression and ROS formation and also elevated levels of NF-κB, NLRP3, cleaved caspase-1, IL-1β and IL-18. After use of the NF-κB inhibitor BAY 117082 and knocked out NLRP3 in vitro decreased ROS formation and the expression of Iba-1, NF-κB and NLRP3 as well as levels of cleaved caspase-1, IL-1β and IL-18. These findings suggest that activation of the glucocorticoid receptor-NF-κB-NLRP3 pathway in hippocampal microglia mediates chronic stress-induced hippocampal neuroinflammation and depression-like behavior.

Innate immune alterations are elicited in microglial cells before plaque deposition in the Alzheimer\u2019s disease mouse model 5xFAD

Alzheimer’s disease (AD) is the most common form of dementia characterized by the formation of amyloid plaques (Aβ). Over the last decade, the important role of the innate immune system for the disease development has been established. Chronic activation of microglial cells creates a proinflammatory environment, which is believed to be central for the development of the disease as well as its progression. We used the AD mouse model 5xFAD to investigate if inflammatory alterations are present in microglial cells before plaque deposition. We applied mass spectrometry and bioinformation analysis to elucidate early microglial alterations. Interestingly, we found the cytokines IL1β and IL10 to be elevated in the 5xFAD brain after the formation of Aβ plaque at 10 weeks only. Using mass spectrometry analysis of microglial cells with bioinformation analysis, we found JAK/STAT, p38 MAPK and Interleukin pathways affected in microglial cells before plaque deposition at 6 weeks. At 10 weeks, GO analysis showed affected pathways related to interferon-gamma regulation and MAPK pathways. Our study points toward early inflammatory changes in microglial cells even before the accumulation of Aβ.

Changes in neocortical and hippocampal microglial cells during hibernation.

Mammalian hibernation proceeds alongside a wide range of complex brain adaptive changes that appear to protect the brain from extreme hypoxia and hypothermia. Using immunofluorescence, confocal microscopy, quantitative analysis methods and intracellular injections, we have characterized microglia morphological changes that occur in the neocortex and hippocampus of the Syrian hamster during hibernation. In euthermic hamsters, microglial cells showed the typical ramified/resting morphology with multiple long, thin and highly-branched processes homogeneously immunostained for Iba-1. However, during torpor, microglial cell process numbers increase significantly accompanied by a shortening of the Iba-1 immunoreactive processes, which show a fragmented appearance. Adaptative changes of microglial cells during torpor coursed with no expression of microglial cell activation markers. We discuss the possibility that these morphological changes may contribute to neuronal damage prevention during hibernation.

Retraction Statement: Anti-inflammatory properties of tianeptine on lipopolysaccharide-induced changes in microglial cells involve toll-like receptor-related pathways.

'Anti-inflammatory properties of tianeptine on lipopolysaccharide-induced changes in microglial cells involve toll-like receptor-related pathways' by Slusarczyk, J., Trojan, E., Glombik, K., Piotrowska, A., Budziszewska, B., Kubera, M., Popiolek-Barczyk, K., Lason, W., Mika, J. and Basta-Kaim, A. The above article from the Journal of Neurochemistry published on 14 February 2016 on Wiley Online Library ( www.onlinelibrary.com), and in Volume 136, pp. 958-970, is being retracted by agreement between the corresponding author Agnieszka Basta-Kaim, the Journal's Editor-in-Chief Jörg Schulz, and John Wiley & Sons Ltd. The Editorial Office was alerted by a science journalist that the same Western Blot lane had been used to represent two different proteins. The Western Blot signal of iNOS in Fig.4a was supposedly identical to the Western Blot signal of phospho-JNK in Fig.6b. The corresponding author stated that "on the final step of figure 6 preparation the first author made, by mistake, an incorrect attachment of representative p-JNK blots." A corrected Fig.6b is enclosed below. The second concern reaching the Editorial Office was that the same Western Blot signal appeared to have been used to represent two different experimental conditions: the iNOS control signal (-/- LPS/TIA Fig.4a) appears as a horizontal and vertical mirror image of the last signal in this line (+/10 LPS/TIA Fig.4a). The raw membrane which was used to produce Fig.4a is enclosed on the next page and highlights the steps that were undertaken during figure preparation. Although the initial concern was not proven, concerns remained regarding the question how an inadvertent flipping of the first Western blot lane could happen. A corrected Fig.4a prepared by the corresponding author from the raw image of iNOS western blot depicted above, without flipped first lane, is presented below: Although the corresponding author provided a large amount of evidence to explain disparities in the presentation of Western Blot images, due to the number of inconsistencies that were revealed during review of the provided evidence and the inability to confirm the nature of the steps that led to them, it was felt that the above mentioned Western Blot images presented in this publication were not reliable, even if the conclusions may still be valid. The first author would like to apologize to the readers, reviewers and editors of Journal of Neurochemistry for the errors. Reference Slusarczyk J., Trojan E., Glombik K., Piotrowska A., Budziszewska B., Kubera M., Popiolek-Barczyk K., Lason W., Mika J. and Basta-Kaim A. (2016) Anti-inflammatory properties of tianeptine on lipopolysaccharide-induced changes in microglial cells involve toll-like receptor-related pathways. J. Neurochem. 136, 958-970. https://doi.org/10.1111/jnc.13452.

Aqueous extract from the Withania somnifera leaves as a potential anti-neuroinflammatory agent: a mechanistic study

BackgroundMicroglial-mediated neuroinflammation is a key factor underlying the pathogenesis of various neurodegenerative diseases and also an important target for the development of the neuroinflammation-targeted therapeutics. Conventionally, the nonsteroidal anti-inflammatory drugs (NSAIDs) are prescribed, but they are associated with long-term potential risks. Natural products are the cornerstone of modern therapeutics, and Ashwagandha is one such plant which is well known for its immunomodulatory properties in Ayurveda.MethodsThe current study was aimed to investigate the anti-neuroinflammatory potential of Ashwagandha (Withania somnifera) leaf water extract (ASH-WEX) and one of its active chloroform fraction (fraction IV (FIV)) using β-amyloid and lipopolysaccharide (LPS)-stimulated primary microglial cells and BV-2 microglial cell line. Iba-1 and α-tubulin immunocytochemistry was done to study the LPS- and β-amyloid-induced morphological changes in microglial cells. Inflammatory molecules (NFkB, AP1), oxidative stress proteins (HSP 70, mortalin), apoptotic markers (Bcl-xl, PARP), cell cycle regulatory proteins (PCNA, Cyclin D1), and MHC II expression were analyzed by Western blotting. Mitotracker and CellRox Staining, Sandwich ELISA, and Gelatin Zymography were done to investigate ROS, pro-inflammatory cytokines, and matrix metalloproteinase production, respectively. Ashwagandha effect on microglial proliferation, migration, and its apoptosis-inducing potential was studied by cell cycle analysis, migration assay, and Annexin-V FITC assay, respectively.ResultsASH-WEX and FIV pretreatment was seen to suppress the proliferation of activated microglia by causing cell cycle arrest at Go/G1 and G2/M phase along with decrease in cell cycle regulatory protein expression such as PCNA and Cyclin D1. Inhibition of microglial activation was revealed by their morphology and downregulated expression of microglial activation markers like MHC II and Iba-1. Both the extracts attenuated the TNF-α, IL-1β, IL-6, RNS, and ROS production via downregulating the expression of inflammatory proteins like NFkB and AP1. ASH-WEX and FIV also restricted the migration of activated microglia by downregulating metalloproteinase expression. Controlled proliferation rate was also accompanied by apoptosis of activated microglia. ASH-WEX and FIV were screened and found to possess Withaferin A and Withanone as active phytochemicals.ConclusionsThe current data suggests that ASH-WEX and FIV inhibit microglial activation and migration and may prove to be a potential therapeutic candidate for the suppression of neuroinflammation in the treatment of neurodegenerative diseases.

Anti-inflammatory properties of tianeptine on lipopolysaccharide-induced changes in microglial cells involve toll-like receptor-related pathways.

Accumulating evidence suggests that activation of microglia plays a key role in the pathogenesis of depression. Activated microglia produce a wide range of factors whose prolonged or excessive release may lead to brain disorders. Thus, the inhibition of microglial cells may be beneficial in the treatment of depressive diseases. Tianeptine is an atypical antidepressant drug with proven clinical efficacy, but its mechanism of action remains still not fully understood. In the present study, using microglial cultures we investigated whether tianeptine modifies microglial activation after lipopolysaccharide (LPS) stimulation and which intracellular pathways are involved in the activity of this antidepressant. Our study shows that tianeptine attenuated the LPS-evoked inflammatory activation of microglia by decreasing the expression of proinflammatory cytokines such as IL-1β, IL-18, IL-6 and tumor necrosis factor α (TNF-α), the release of nitric oxide (NO) and reactive oxygen species (ROS) as well as the expression of inducible nitric oxide synthase. Analyses of signaling pathways demonstrate that tianeptine led to the suppression of LPS-induced TLR4 expression and ERK1/2 phosphorylation. Furthermore, our study reveals the inhibitory impact of tianeptine on caspase-3-induced PKCδ degradation and consequently on the activation of NF-κB factor in microglial cells. Taken together, present results show anti-inflammatory properties of tianeptine in microglial cultures stimulated by LPS. This study provides evidence that the inhibition of microglial activation may underlie the therapeutic activity of tianeptine. Our findings show the anti-inflammatory effect of tianeptine (TIA) in lipopolisaccharide (LPS)-stimulated microglial cells. The beneficial tianeptine action is mediated through the inhibition of Toll-like receptor 4 (TLR4) expression as well as the TLR4-related pathways: extracellular signal-regulated kinase 1/2 (ERK1/2), caspase-3-dependent protein kinase δ (PKCδ) cleavage and the expression of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). These findings may provide a new therapeutic strategy for treatment of disorders based on neuroinflammation, including depression.