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BACKGROUND:Indolepropionic acid has been shown to reduce diabetes-induced central nervous system inflammation.However,there is a lack of research on whether to inhibit microglia M1 polarization for the treatment of spinal cord injury. OBJECTIVE:To investigate the mechanism of indolepropionic acid inhibition of microglial cell M1 polarization for the treatment of spinal cord injury through cell and animal experiments. METHODS:(1)In vitro experiments:BV2 cell viability was assessed using the CCK-8 assay to determine optimal concentrations of indolepropionic acid.Subsequently,BV2 cells were categorized into control group,administration group(50 μmol/L indolepropionic acid),lipopolysaccharide group(100 ng/mL lipopolysaccharide),and treatment group(100 ng/mL lipopolysaccharide + 50 μmol/L indolepropionic acid).Nitric oxide content was quantified using the Griess method.Real-time quantitative PCR and western blot assay were employed to measure mRNA and protein levels of pro-inflammatory factors.Cell immunofluorescence staining was conducted to assess inducible nitric oxide synthase expression.The Seahorse assay was employed to assess glycolytic stress levels in BV2 cells.(2)In vivo experiments:30 SD rats were randomly divided into three groups:sham surgery group,spinal cord injury group,and indolepropionic acid group.Motor function recovery in rats after spinal cord injury was assessed using BBB scoring and the inclined plane test.Immunofluorescence staining of spinal cord tissue was conducted to evaluate the expression of inducible nitric oxide synthase in microglial cells.ELISA was employed to measure protein expression levels of the pro-inflammatory cytokines interleukin-1β and tumor necrosis factor-α in spinal cord tissue. RESULTS AND CONCLUSION:(1)In vitro experiments:Indolepropionic acid exhibited significant suppression of BV2 cell viability when its concentration exceeded 50 μmol/L.Indolepropionic acid achieved this by inhibiting the activation of the nuclear factor κB signaling pathway,thereby suppressing the mRNA and protein expression levels of pro-inflammatory cytokines(interleukin-1β and tumor necrosis factor-α),as well as the M1 polarization marker,inducible nitric oxide synthase,in BV2 cells.Additionally,indolepropionic acid notably reduced the glycolytic level in BV2 cells induced by lipopolysaccharides.(2)In vivo experiments:Following indolepropionic acid intervention in spinal cord injury rats,there was a noticeable increase in BBB scores and the inclined plane test angle.There was also a significant decrease in the number of M1-polarized microglial cells in spinal cord tissue,accompanied by a marked reduction in the protein expression levels of pro-inflammatory cytokines(interleukin-1β and tumor necrosis factor-α).(3)These results conclude that indolepropionic acid promotes functional recovery after spinal cord injury by improving the inflammatory microenvironment through inhibition of microglia M1 polarization.
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The results clearly demonstrate the close relationship between the evolution of microglia and the mechanisms underlying aging.Monitoring the status of microglia can greatly contribute to diagnosing aging and related neurodegenerative diseases.Furthermore, protecting the function of microglia is a viable strategy for slowing down brain aging and preserving brain function.This approach offers a feasible intervention strategy for tackling aging and degenerative diseases.This paper provides a comprehensive summary of the changes that occur in microglia during the aging process.It also examines the impact of these changes in microglia function on neurons and astrocytes in the brain.
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Objective:To identify the potential intracranial inflammation in neuromyelitis optica spectrum disorders(NMOSD) patients without supratentorial MRI lesions using quantitative susceptibility mapping (QSM).Methods:Seventy NMOSD patients and 35 age- and gender-matched healthy controls (NC) underwent QSM, 3D-T 1, diffusion MRI from Beijing Tiantan Hospital during June 2019 to June 2021. Susceptibility was compared among NMOSD patients with acute attack (ANMOSD), NMOSD patients in chronic phase (CNMOSD) and NC. The correlation between susceptibility in several brain regions and the cerebrospinal fluid levels of inflammatory makers were analyzed. Results:NMOSD patients showed different susceptibility in several brain regions including bilateral hippocampus, precuneus, right cuneus, putamen, superior parietal and inferior temporal ( P<0.001) and the posr-hoc showed it is higher than normal. Compared to CNMOSD patients, the ANMOSD patients showed increased susceptibility in the cuneus (0.009 ± 0.004 vs. 0.005 ± 0.004, P<0.05). There was significant positive correlations between susceptibility and CSF levels of sTREM2 which reflect the active of microglial cells ( r = 0.494, P<0.05). Conclusions:Despite the absence of supratentorial lesions on MRI, increased susceptibility suggests underlying inflammation in the cerebral cortex in both patients with ANMOSD and CNMOSD, and some of them are obviously related to inflammatory markers in CSF. QSM sequence can be used to explore the potential inflammation in NMOSD patients without obvious supratentorial lesions.
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Objective To explore the effect of activation of mammalian target of rapmycin complex 2(mTORC2)/Akt signaling pathway on dopaminergic neurons and behavior in 6-hydroxydopamine (6-OHDA) model mice and its possible mechanism. Methods Selecting 36 mice which The Nestin-CreERTM and ROSA26-LacZ reporter genes were detected at the same time in 3-month-old male C57BL/6J mice weighing 20-25 g divideng them into 4 gruops, NS+ corn oil group, 6-OHDA+corn oil group, 6-OHDA+PP242 group and 6-OHDA+A-443654 group, and 6-OHDA was injected into the right striatum of the brain to replicate the Parkinson’s disease (PD) model of mice, and then daily intraperitoneal injection of mTORC2/Akt signaling pathway agonist A-443654 or inhibitor PP242. Serum interleukin-1β (IL-1β) and tumor necrosis factor-α(TNF-α)levels were measured by enzyme-linked immunosorbent assay. Immunohistochemistry and immunofluorescence staining were performed to investigate the change of microglia, dopaminergic neurons as well as neural progenitor cells (NPCs). Western blotting was used to detect the expression of related protein of mTORC2/Akt signaling pathway including rictor, p-Akt and regulated in development and DNA dgmage responses 1(REDD1) and the interaction between them were verified by immunoprecipitation. Finally, the behavioral performance of each group of mice was observed. Results With the activation of microglia and the increase of inflammatory factors in PD model mice, the number of dopaminergic neurons in the substantia nigra(SN) decreased significantly, and the motor function of the mice was impaired, but the number of NPCs increased significantly compared with the control mice, mTORC2/Akt signaling pathway related protein expression was also significantly up-regulated. A-443654 treatment further up-regulated the expression of these proteins, meanwhile the indicators mentioned above were ameliorated. However, the inhibitor PP242 treatment group showed completely opposite result with the agonist group. Conclusion A-443654 can promote the proliferation of NPCs and the number of new-born dopaminergic neurons by up-regulating related proteins of mTORC2/Akt signaling pathway, and reducing the activation of microglia and the level of inflammation factors, which ultimately lead to the amelioration of SN-striatal dopaminergic neurons and behavioral performance in PD model mice.
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Objective:To verify the protective effect of terazosin on cognitive function of rats after whole-brain irradiation (WBI) and to investigate its mechanism.Methods:A total of 64 1-month-old male SD rats were randomly divided into the untreated control group, terazosin group, irradiation group and irradiation plus terazosin group (combination group). WBI was administered at a single dose of 20 Gy in the irradiation and combination groups. The open field test and the Morris water maze (MWM) test were used to evaluate the effect of terazosin on cognitive function after WBI.Starting from the three aspects of juvenile neuron apoptosis, neurogenesis disorderand microglia activation, the possible cellular mechanism wasassayed by double-label immunofluorescence staining for BrdU (bromodeoxyuridine) / NeuN, DCX(Doublecortin) / Caspase-3 and single-label immunofluorescence staining for Iba-1 (ionized calcium binding adaptor molecule-1).Results:Terazosin intervention improved the short-term memory retention of irradiated rats ( P=0.032). After terazosin treatment, the number of DCX + cells in the combination groupwas increased by approximately 35% compared with that in the irradiation group ( P=0.038). The number of BrdU +/NeuN + cells in the combination group was increased by approximately 15% than that in the irradiation group ( P>0.05). The number of Iba-1 + cells in the irradiation plus terazosin group was decreased by 49% compared with that in the irradiation group ( P=0.036). Conclusion:Terazosin may reduce the hippocampal juvenile neuron loss and inhibit neuroinflammation via microglia activation, which can alleviate WBI-induced cognitive dysfunction to a certain extent.
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Microglia play multiple roles in such processes as brain development, homeostasis, and pathology. Due to their diverse mechanisms of functions, the complex sub-classifications, and the large differences between different species, especially compared with humans, very different or even opposite conclusions can be drawn from studies with different research models. The choice of appropriate research models and the associated tools are thus key ingredients of studies on microglia. Mice are the most commonly used animal models. In this review, we summarize in vitro and in vivo models of mouse and human-derived microglial research models, including microglial cell lines, primary microglia, induced microglia-like cells, transgenic mice, human-mouse chimeric models, and microglial replacement models. We also summarize recent developments in novel single-cell and in vivo imaging technologies. We hope our review can serve as an efficient reference for the future study of microglia.
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Objective To investigate the mechanism of TREM2 modulating the polarization of M2 microglia treated by oxygen-glucose deprivation/reoxygenation (OGD/R). Methods Mouse N9 microglial cells were cultured in vitro. N9 cells were transfected with lenti virus for TREM-2-overexpression (LV-TREM2), and LV-scramble acted as control group. OGD/R model was established. The OGD/R cells were randomly divided into OGD/R, OGD/R+LV-scramble and OGD/R+LV-TREM2 groups. Real-time PCR was used to detect the expression of TREM2 mRNA in OGD/R N9 cells within 72 hours after re-oxygenation. Immunofluorescence was applied to observe transfection of lentivirus LV-scramble and LV-TREM2 for normal N9 microglia, and Real-time PCR and Western blotting were used to verify the efficiency of lentivirus transfection. The mRNA and protein contents of Ml microglial markers tumor necrosis factor-a (TNF-α), interleukin-lβ (IL-lβ) and inducible nitric oxide synthase (iNOS), M2 microglial markers arginase-1 (Arg-1) and interleukin-10 (IL-10) were detected by Real-time PCR and ELISA. The expressions of phosphorylated-phosphatidylinositol 3-kinases (p-PI3K), PI3K, phosphorylated protein kinase B (p-Akt), Akt, phosphorylated inhibitor of nuclear factor-κB ( NF-κB)α (p-lκBα) and IκBα protein were detected by Western blotting. The distribution of NF-κB P65 (NF-κB P65) protein in N9 cells was analyzed by immunofluorescence method. Results TREM2 mRNA content in the OGD/R group cells increased significantly within 72 hours after re-oxygenation, and peaked at hour 24 and hour 48. Lenti virus LV- TREM2 effectively promoted the expression of TREM2 mRNA and protein of N9 cells in OGD/R model (P<0.001, P<0.01). Compared with the OGD/R group, the mRNA and protein content of TNF-α, IL-lβ and iNOS decreased significantly, while Arg-1 and IL-10 in OGD/R+LV-TREM2 group increased significantly(P<0.05). Besides, the ratios of P-PI3K/PI3K and p-Akt/Akt increased obviously (P<0.05), the ratio of p-IκBα/IκBα decreased significantly in OGD/ R+ LV-TREM2 group (P<0.001), and the nuclear translocation of NF-κB P65 protein was obviously weakened. Conclusion TREM-2 overexpression exerts anti-inflammatory effect by modulating the polarization of microglia from Ml to M2 type, which is associated with PI3K/Akt and NF-κB signaling pathways regulated by TREM2 in N9 microglia with OGD/R model.
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Objective:To observe the changes of inflammatory damage in the brain of rats after focal cerebral ischemia-reperfusion, and explore the effect of the initiation of IκB kinases β (IKKβ), which is the key protein of activating nuclear factor (NF)-kappa B signaling pathway in inflammatory response, and the mechanism of electroacupuncture inhibiting inflammatory damage. Methods:A total of 240 male Sprague-Dawley rats were randomly divided into sham group, ischemia-reperfusion group, electroacupuncture group, IKKβ silencing group, IKKβ overexpression group and IKKβ overexpression + electroacupuncture group, each group was further divided into six hours, twelve hours, 24 hours, 48 hours and 72 hours subgroups. The right middle cerebral artery occlusion reperfusion model was established by modified thread embolization. The IKKβ gene was intervened by gene silencing and gene overexpression technology. Results:Compared with the model group, the neurological function score increased (P < 0.05), the cerebral infarction volume decreased (P < 0.05), the activation of NF-κB p65 was inhibited, and the content of proinflammatory factors decreased (P < 0.05) in IKKβ silencing group. Compared with IKKβ silencing group, the above results were significantly worse in IKKβ overexpression group (P < 0.05), and microglia in cerebral ischemic cortex were significantly activated. The activation of microglia and activation of IKKβ were significantly inhibited in IKKβ overexpression + electroacupuncture group. Conclusion:IKKβ gene silencing could inhibit the inflammatory response of cerebral ischemic cortex mediated by NF-κB signaling pathway, and over-expression of IKKβ could lead to severe inflammatory damage in ischemic cortex. Electroacupuncture could inhibit the inflammatory damage after focal cerebral ischemia-reperfusion by regulating the activity of IKKβ.
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@#Tauroursodeoxycholic acid(TUDCA)is formed by taurine conjugated of ursodeoxycholic acid(UDCA). It has the role of neurotrophic factor in anti-inflammatory, anti-apoptosis and reducing the activation of microglial cells. These effects may be one of the most critical of all pathological stages of retinitis pigmentosa. Preclinical trials have shown that TUDCA had potential therapeutic value for retinal degeneration disease. This article discusses how TUDCA can slow down the process of retinal degeneration.
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The etiology underlying ischemic stroke is still elusive. Previous studies have indicated that inflammation might play a key role in the pathogenesis, which provided a novel insight into the therapeutic strategy of ischemic stroke. In this review, we summarize some drugs which regulate the activation and polarization of microglia and further alleviate neurological symptoms.
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This paper was aimed to summarize functional and morphologic changes of neurogliocytes exposure to stress,and the regulating effect of traditional Chinese medicine (TCM) on functional and morphologic changes of neurogliocytes,in order to provide new ideas for mechanism development of stress pathogenesis and TCM regulating effect.
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Objective It remains to be confirmed whether tissue kallikrein has neuroprotective effect in diabetes-induced stroke.This study was to investigate the neuroprotection of tissue kallikrein against cerebral ischemia-reperfusion injury in diabetic rats. Methods Healthy male SD rats were randomly divided into a sham operation, a saline control, and a tissue kallikrein group.Diabetes mellitus was induced in the animals by intraperitoneal injection of streptozotocin and the model of focal cerebral ischemia-reperfusion was made with an intraluminal vascular occlusion method. At 24 hours after modeling, we obtained the neurological deficit score, in-farct size, and brain water content, counted Iba1-and MPO-positive cells by immunohistochemistry, and determined the expressions of ICAM-1 and VCAM-1 by real-time PCR. Results In comparison with the saline controls, the rats treated with tissue kallirein showed significant decreases in the neurological deficit score (P<0.01), the infarct size ([23.57 ±5.79] vs [47.97 ±1.19]%, P<0.01), brain edema ([81.73 ±2.10] vs [84.94 ±2.34]%, P<0.05), the counts of Iba1-and MPO-positive cells (12.33 ±4.46 vs 31.83 ±8.13 and 13.83 ±4.49 vs 37.50 ±7.64, both P<0.01), and the expressions of ICAM-1 and VCAM-1 (both P<0.05). Conclusion Tissue kallikrein has a neuroprotective effect against cerebral ischemia-reperfusion injury in diabetic rats, which may be associated with its anti-inflammation property.
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Naegleria fowleri, a ubiquitous free-living ameba, causes fatal primary amebic meningoencephalitis in humans. N. fowleri trophozoites are known to induce cytopathic changes upon contact with microglial cells, including necrotic and apoptotic cell death and pro-inflammatory cytokine release. In this study, we treated rat microglial cells with amebic lysate to probe contact-independent mechanisms for cytotoxicity, determining through a combination of light microscopy and scanning and transmission electron microscopy whether N. fowleri lysate could effect on both necrosis and apoptosis on microglia in a time- as well as dose-dependent fashion. A 51Cr release assay demonstrated pronounced lysate induction of cytotoxicity (71.5%) toward microglial cells by 24 hr after its addition to cultures. In an assay of pro-inflammatory cytokine release, microglial cells treated with N. fowleri lysate produced TNF-alpha, IL-6, and IL-1beta, though generation of the former 2 cytokines was reduced with time, and that of the last increased throughout the experimental period. In summary, N. fowleri lysate exerted strong cytopathic effects on microglial cells, and elicited pro-inflammatory cytokine release as a primary immune response.
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Animals , Humans , Rats , Cell Death , Chromium Radioisotopes/metabolism , Cytokines/metabolism , Microglia/cytology , Microscopy , Naegleria fowleri/pathogenicity , Staining and LabelingABSTRACT
Objective: To observe the change of microglia activity after fast decompressing and/or hyperbaric oxygenation (HBO)-induced central nervous system (CNS) damage, so as to study the role of microglia in CNS dysbaric injury and the effects of HBO on microglia. Methods: Rats were randomly divided into the following groups: normal control, safe decompressing, fast decompressing (FD) injured, and HBO treated groups. Rat models of dysbaric injury were established by FD; 6 h later the rat models were subjected to HBO treatment. The activated microglia were detected by FITC-linked Isolectin B4; TNF-α and TNF-α converting enzyme (TACE) positive cells were detected immunohistochernically; and neural apoptosis was detected by TUNEL assay. TNF-α contents in CNS tissue were determined by ELISA and the bioactivity of sTNF-α in cerebrospinal fluid (CSF) were determined by L929 cell cytotoxicity bioassay. Results: 1134 positive microglia appeared in rats' CNS 6 h after FD treatment, peaked after 24 h, and declined thereafter. The activated microglia had morphological changes. Cell apoptosis indices of CNS reached its peak 48 h after FD treatment. Activated microglia and apoptotic neurons had similar distribution. TNF-α was detected in the brain and spinal cord 6 h after FD, significantly increased after 24 h, and peaked after 48 h. The content of TNF-α was positively correlated with IB4 positive cells and apoptosis index (P<0.05). TNF-α bioactivity in CSF of FD group had a similar change to TNF-α content in CNS tissue. The IHC results showed that, TNF-α and TACE positive cells had the same morphology and distribution to those of IB4 positive cells. HBO treatment significantly decreased IB4 positive cells after 24 h, 48 h, and 72 h; reduced TNF-α content in CNS tissues and TNF-α cytotoxicity in CSF; and decreased the apoptosis index after 48 h and 72 h. Conclusion: Microglial cells are quickly activated after dysbaric-induced injury of CNS. The activated microglia play a role in secondary injury through increasing TNF-α and TACE expression. HBO therapy can protect the neurons through depressing the activation and proliferation of microglia and reducing secretion of neurotoxin.
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Microglial cell activation is known to contribute to neuropathic pain following spinal sensory nerve injuries. In this study, I investigated its mechanisms in the case of trigeminal sensory nerve injuries by which microglial cell and p38 mitogen-activated protein kinase (p38 MAPK) activation in the medullary dorsal horn (MDH) would contribute to the facial pain hypersensitivity following mandibular nerve transection (MNT). And also investigated the changes of trigeminal ganglion neurons and ERK, p38 MAPK manifestations. Activation of microglial cells was monitored at 1, 3, 7, 14, 28 and 60 day using immunohistochemical analyses. Microglial cell activation was primarily observed in the superficial laminae of the MDH. Microglial cell activation was initiated at postoperative 1 day, maximal at 3 day, maintained until 14 day and gradually reduced and returned to the basal level by 60 days after MNT. Pain hypersensitivity was also initiated and attenuated almost in parallel with microglial cell activation pattern. To investigate the contribution of the microglial cell activation to the pain hypersensitivity, minocycline, an inhibitor of microglial cell activation by means of p38 MAPK inhibition, was administered. Minocycline dose-dependently attenuated the development of the pain hypersensitivity in parallel with inhibition of microglial cell and p38 MAPK activation following MNT. Mandibular nerve transection induced the activation of ERK, but did not p38 MAPK in the trigeminal ganglion. These results suggest that microglial cell activation in the MDH and p38 MAPK activation in the hyperactive microglial cells play an important role in the development of facial neuropathic pain following MNT. The results also suggest that ERK activation in the trigeminal ganglion contributes microglial cell activation and facial neuropathic pain.