Metformin Protects Against Traumatic Brain Injury by Switching M1/M2 Phenotypes and Regulating NLRP3 Inflammasome Activation

2021 ◽  
Author(s):  
Weiwei Gao ◽  
Weipeng Jin ◽  
Xin Xu ◽  
Dongpei Yin ◽  
Shuai Zhou ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Nlrp3 Inflammasome ◽  
Inflammasome Activation ◽  
Protective Effects ◽  
Microglial Polarization ◽  
Compound C ◽  
M2 Polarization ◽  
Bv2 Cells ◽  
Signaling Activation

Abstract Background: Traumatic brain injury (TBI) always lead to inflammatory responses unregulated characterized by excessive leukocytes infiltration, microglia activation and neuronal apoptosis. Metformin, recognized as an activator of AMPK, had been reported to exert protective effects in TBI models. However, whether metformin treatment switches post-TBI-induced microglia/macrophage polarization and its mechanism has not yet been fully elucidated.Methods: Firstly, we established a C57BL/6J mouse TBI model receiving an intraperitoneal injection of 50 mg/kg metformin daily from 2h post-injury until sacrifice to assess the leukocytes infiltration, microglial polarization and NLRP3 inflammasome signaling activation. Then, BV2 cells were pretreated with metformin for 2 hours followed by stimulated with LPS to determine the effects of metformin on microglial polarization and its mechanism. Results: We demonstrated that post-TBI metformin administration switched microglial M1 to M2 polarization and inhibited the NLRP3 inflammasome signaling activation, thus reducing neurological deficits, brain edema, cells death and leukocytes infiltration at day 3 after TBI. Then, these findings were further confirmed in BV2 cell experiments, in which these protective effects mediated by metformin was lessened by the administration of Compound C, an AMPK inhibitor.Conclusion: Metformin may be a potential therapeutic method to improve neurological recovery following TBI, partly by regulating microglia M1/M2 polarization and inhibiting NLPR3 inflammasome activation dependent on the activation of AMPK.

scholarly journals NADPH Oxidase 2 Regulates NLRP3 Inflammasome Activation in the Brain after Traumatic Brain Injury

2017 ◽  
Vol 2017 ◽  
pp. 1-18 ◽  
Author(s):  
Merry W. Ma ◽  
Jing Wang ◽  
Krishnan M. Dhandapani ◽  
Darrell W. Brann
Keyword(s):  
Oxidative Stress ◽  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Nadph Oxidase ◽  
Nlrp3 Inflammasome ◽  
Healing Process ◽  
Inflammasome Activation ◽  
Nlrp3 Inflammasome Activation ◽  
Nadph Oxidase 2

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. After the initial primary mechanical injury, a complex secondary injury cascade involving oxidative stress and neuroinflammation follows, which may exacerbate the injury and complicate the healing process. NADPH oxidase 2 (NOX2) is a major contributor to oxidative stress in TBI pathology, and inhibition of NOX2 is neuroprotective. The NLRP3 inflammasome can become activated in response to oxidative stress, but little is known about the role of NOX2 in regulating NLRP3 inflammasome activation following TBI. In this study, we utilized NOX2 knockout mice to study the role of NOX2 in mediating NLRP3 inflammasome expression and activation following a controlled cortical impact. Expression of NLRP3 inflammasome components NLRP3 and apoptosis-associated speck-like protein containing a CARD (ASC), as well as its downstream products cleaved caspase-1 and interleukin-1β (IL-1β), was robustly increased in the injured cerebral cortex following TBI. Deletion of NOX2 attenuated the expression, assembly, and activity of the NLRP3 inflammasome via a mechanism that was associated with TXNIP, a sensor of oxidative stress. The results support the notion that NOX2-dependent inflammasome activation contributes to TBI pathology.

scholarly journals miR-29a-5p Alleviates Traumatic Brain Injury- (TBI-) Induced Permeability Disruption via Regulating NLRP3 Pathway

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Aijun Zhang ◽  
Youming Lu ◽  
Lei Yuan ◽  
Pengqi Zhang ◽  
Dongdong Zou ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Endothelial Cells ◽  
Brain Injury ◽  
Water Content ◽  
Nlrp3 Inflammasome ◽  
Cell Permeability ◽  
Luciferase Reporter ◽  
Inflammasome Activation ◽  
Nlrp3 Inflammasome Activation

Objective. Inactivation of NLRP3 inflammasome plays a role in reducing the permeability of endothelial cells and improving blood-brain barrier (BBB) dysfunction following traumatic brain injury (TBI). However, the mechanism controlling NLRP3 inflammasome activation remains unclear. This study is aimed at defining the role of miR-29a-5p in NLRP3 inflammasome activation and permeability of endothelial cells under TBI. Methods. The scratch injury model on brain bEnd.3 microvascular endothelial cells was used as in vitro TBI model cells. Effects of miR-29a mimics and inhibitors on TBI model cells were observed by examining their action on FITC, TEER, and protein contents of ZO-1 and occludin, and cell permeability-associated protein. Luciferase reporter assay evaluated miR-29a-5p targeting to NLRP3. ELISA examined of IL-1β and IL-18 levels. miR-29a-5p mimic was injected into TBI mouse and its effect on BBB, indicated by Evans blue (EB) staining assay and cerebral water content, and NLRP3 activation was examined. Results. miR-29a-3p and miR-29a-5p mimics decrease the concentration of FITC, and increase TEER and the protein contents of ZO-1 and occludin in TBI model cells. miR-29a-5p silencing disrupted the permeability of mouse bEnd.3 cells. miR-29a-5p targets to NLRP3 through the binding on its 3 ′ UTR and negatively regulates its expression in TBI model cells. NLRP3 inhibition and miR-29a-5p silencing together caused significantly decreased FITC concentration and increased TEER value and release of IL-1β and IL-18. miR-29a-5p mimic alleviated the BBB and cerebral water content and inactivates NLRP3 in the mouse TBI model. Conclusions. miR-29a-5p mimics protect TBI-induced increased endothelial cell permeability and BBB dysfunction via suppressing NLRP3 expression and activation.

scholarly journals FTO Regulates Microglia-Induced Inflammation by Stabilizing ADAM17 Expression After Experimental Traumatic Brain Injury

2022 ◽  
Author(s):  
Xiangrong Chen ◽  
Jieran Yao ◽  
Yue Chen ◽  
Wenqi Lv ◽  
Yuanxiang Lin ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Epigenetic Modification ◽  
Down Regulation ◽  
Neuroinflammatory Response ◽  
Microglial Polarization ◽  
Bv2 Cells ◽  
Tnf Α ◽  
Experimental Traumatic Brain Injury

Abstract Background The neuroinflammatory response mediated by microglial polarization plays an important role in the secondary nerve injury of traumatic brain injury (TBI). The post-transcriptional modification of n6-methyladenosine (m6A) is ubiquitous in the immune response of the central nervous system. The fat mass and obesity (FTO)-related protein can regulate the splicing process of pre-mRNA. However, after experimental traumatic brain injury (TBI), the role of FTO in microglial polarization and the subsequent neuroinflammatory response is still unclear. Methods TBI mice model was established by the Feeney weight-drop method. Neurological severity score, brain water content measurement and Nissl staining were used to detect the role of FTO in microglial polarization and the molecular mechanism of targeted RNA epigenetic modification. In vitro and in vivo experiments were conducted to evaluate microglial polarization and the neuroinflammatory response by down-regulation of FTO expression. The level of m6A modification in M1 activated microglia was detected by qRT-PCR, m6A-MeRIP and m6A high-throughput sequencing. Fluorescent in situ hybridization combined with immunofluorescence imaging were used to detect the epigenetic regulation of ADAM17 mediated by an FTO-m6A-dependent mechanism. Results The expression of FTO was significantly down-regulated in BV2 cells treated with lipopolysaccharide and mice with TBI. Down-regulation of FTO expression increased the level of m6A in M1 microglia at the level of the entire transcriptome. Meanwhile, after FTO interference, M1/M0 phenotype detection experiments revealed the BV2 cells shifted from an M0 to M1 phenotype as the population rate of CD11b+/CD86+ increased and secretion of pro-inflammatory cytokines was enhanced. Methylated RNA immunoprecipitation assay showed that the m6A peaks located in the ADAM17 and TNF-α genes increased. Taken together, the results indicated that FTO can affect the transcription modification of ADAM17 and the expression of the downstream TNF-α/NF-kB pathway. In turn, ADAM17 can block the M1-phenotypic transition of microglia driven by FTO-m6A modification. Conclusions The down-regulation of FTO expression leads to the abnormally high expression of ADAM17 in microglia. The activation of microglia and neuroinflammatory response regulated by FTO-related m6A modification play an important role in the early pro-inflammatory process of TBI secondary injury.

scholarly journals Saffron extract attenuates neuroinflammation in rmTBI mouse model by suppressing NLRP3 inflammasome activation via SIRT1

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0257211
Author(s):  
Mariam J. Shaheen ◽  
Amira M. Bekdash ◽  
Hana A. Itani ◽  
Jamilah M. Borjac
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Inflammatory Response ◽  
Neurodegenerative Diseases ◽  
Nlrp3 Inflammasome ◽  
Inflammasome Activation ◽  
Nuclear Factor ◽  
Caspase 1 ◽  
Nlrp3 Inflammasome Activation ◽  
Saffron Extract

Traumatic brain injury (TBI) remains a major cause of morbidity and disability worldwide and a healthcare burden. TBI is an important risk factor for neurodegenerative diseases hallmarked by exacerbated neuroinflammation. Neuroinflammation in the cerebral cortex plays a critical role in secondary injury progression following TBI. The NOD-like receptors (NLR) family pyrin domain containing 3 (NLRP3) inflammasome is a key player in initiating the inflammatory response in various central nervous system disorders entailing TBI. This current study aims to investigate the role of NLRP3 in repetitive mild traumatic brain injury (rmTBI) and identify the potential neuroprotective effect of saffron extract in regulating the NLRP3 inflammasome. 24 hours following the final injury, rmTBI causes an upregulation in mRNA levels of NLRP3, caspase-1, the apoptosis-associated speck-like protein containing a CARD (ASC), nuclear factor kappa B (NF-κB), interleukin-1Beta (IL-1β), interleukin 18 (IL-18), nuclear factor erythroid 2–related factor 2 (NRF2) and heme oxygenase 1 (HMOX1). Protein levels of NLRP3, sirtuin 1 (SIRT1), glial fibrillary acidic protein (GFAP), ionized calcium-binding adaptor molecule 1 (Iba1), and neuronal nuclei (Neu N) also increased after rmTBI. Administration of saffron alleviated the degree of TBI, as evidenced by reducing the neuronal damage, astrocyte, and microglial activation. Pretreatment with saffron inhibited the activation of NLRP3, caspase-1, and ASC concurrent to reduced production of the inflammatory cytokines IL-1β and IL-18. Additionally, saffron extract enhanced SIRT1 expression, NRF2, and HMOX1 upregulation. These results suggest that NLRP3 inflammasome activation and the subsequent inflammatory response in the mice cortex are involved in the process of rmTBI. Saffron blocked the inflammatory response and relieved TBI by activating detoxifying genes and inhibiting NLRP3 activation. The effect of saffron on the NLRP3 inflammasome may be SIRT1 and NF-κB dependent in the rmTBI model. Thus, brain injury biomarkers will help in identifying a potential therapeutic target in treating TBI-induced neurodegenerative diseases.

scholarly journals HMGB1 mediates cognitive impairment caused by the NLRP3 inflammasome in the late stage of traumatic brain injury

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Si-Wei Tan ◽  
Yan Zhao ◽  
Ping Li ◽  
Ya-Lei Ning ◽  
Zhi-Zhong Huang ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Cognitive Impairment ◽  
Brain Injury ◽  
Nlrp3 Inflammasome ◽  
Late Stage ◽  
Long Term Potentiation ◽  
Neuronal Cultures ◽  
Inflammasome Activation ◽  
Post Injury

Abstract Background Cognitive impairment in the late stage of traumatic brain injury (TBI) is associated with the NOD-, LRR and pyrin domain-containing protein 3 (NLRP3) inflammasome, which plays an important role in neuroinflammation. Although classical inflammatory pathways have been well-documented in the late stage of TBI (4–8 weeks post-injury), the mechanism by which the NLRP3 inflammasome impairs cognition is still unclear. Methods Mice lacking the gene encoding for NLRP3 (NLRP3-knockout mice) and their wild-type littermates were used in a controlled cortical impact model of TBI. Levels of NLRP3 inflammasome and inflammatory factors such as IL-1β and HMGB1 were detected in post-injury hippocampal tissue, as well as long-term potentiation. Behaviors were assessed by T-maze test, novel object recognition, and nesting tests. Glycyrrhizin was used to antagonize HMGB1. Calcium imaging were performed on primary neuronal cultures. Results By using the NLRP3-knockout TBI model, we found that the continuous activation of the NLRP3 inflammasome and high mobility group box 1 (HMGB1) release were closely related to cognitive impairment. We also found that inhibition of HMGB1 improved LTP reduction and cognitive function by increasing the phosphorylation level of the NMDAR1 subunit at serine 896 while reducing NLRP3 inflammasome activation. Conclusion NLRP3 inflammasome damages memory in the late stage of TBI primarily through HMGB1 upregulation and provides an explanation for the long-term progression of cognitive dysfunction.

scholarly journals Aggregated Tau-PHF6 (VQIVYK) Potentiates NLRP3 Inflammasome Expression and Autophagy in Human Microglial Cells

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1652
Author(s):  
Chinmaya Panda ◽  
Clara Voelz ◽  
Pardes Habib ◽  
Christian Mevissen ◽  
Thomas Pufe ◽  
...  
Keyword(s):  
Tau Protein ◽  
Nlrp3 Inflammasome ◽  
Time Dependent ◽  
Microglial Cells ◽  
Inflammasome Activation ◽  
Dependent Manner ◽  
Progressive Dementia ◽  
Microglial Polarization ◽  
Protein Levels ◽  
Pyrin Domain

Intra-neuronal misfolding of monomeric tau protein to toxic β-sheet rich neurofibrillary tangles is a hallmark of Alzheimer’s disease (AD). Tau pathology correlates not only with progressive dementia but also with microglia-mediated inflammation in AD. Amyloid-beta (Aβ), another pathogenic peptide involved in AD, has been shown to activate NLRP3 inflammasome (NOD-like receptor family, pyrin domain containing 3), triggering the secretion of proinflammatory interleukin-1β (IL1β) and interleukin-18 (IL18). However, the effect of tau protein on microglia concerning inflammasome activation, microglial polarization, and autophagy is poorly understood. In this study, human microglial cells (HMC3) were stimulated with the unaggregated and aggregated forms of the tau-derived PHF6 peptide (VQIVYK). Modulation of NLRP3 inflammasome was examined by qRT-PCR, immunocytochemistry, and Western blot. We demonstrate that fibrillar aggregates of VQIVYK upregulated the NLRP3 expression at both mRNA and protein levels in a dose- and time-dependent manner, leading to increased expression of IL1β and IL18 in HMC3 cells. Aggregated PHF6-peptide also activated other related inflammation and microglial polarization markers. Furthermore, we also report a time-dependent effect of the aggregated PHF6 on BECN1 (Beclin-1) expression and autophagy. Overall, the PHF6 model system-based study may help to better understand the complex interconnections between Alzheimer’s PHF6 peptide aggregation and microglial inflammation, polarization, and autophagy.

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