scholarly journals Fundamentally different roles of neuronal TNF receptors in CNS pathology: TNFR1 and IKKβ promote microglial responses and tissue injury in demyelination while TNFR2 protects against excitotoxicity in mice

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Irini Papazian ◽  
Eleni Tsoukala ◽  
Athena Boutou ◽  
Maria Karamita ◽  
Konstantinos Kambas ◽  
...  

Abstract Background During inflammatory demyelination, TNF receptor 1 (TNFR1) mediates detrimental proinflammatory effects of soluble TNF (solTNF), whereas TNFR2 mediates beneficial effects of transmembrane TNF (tmTNF) through oligodendroglia, microglia, and possibly other cell types. This model supports the use of selective inhibitors of solTNF/TNFR1 as anti-inflammatory drugs for central nervous system (CNS) diseases. A potential obstacle is the neuroprotective effect of solTNF pretreatment described in cultured neurons, but the relevance in vivo is unknown. Methods To address this question, we generated mice with neuron-specific depletion of TNFR1, TNFR2, or inhibitor of NF-κB kinase subunit β (IKKβ), a main downstream mediator of TNFR signaling, and applied experimental models of inflammatory demyelination and acute and preconditioning glutamate excitotoxicity. We also investigated the molecular and cellular requirements of solTNF neuroprotection by generating astrocyte-neuron co-cultures with different combinations of wild-type (WT) and TNF and TNFR knockout cells and measuring N-methyl-d-aspartate (NMDA) excitotoxicity in vitro. Results Neither neuronal TNFR1 nor TNFR2 protected mice during inflammatory demyelination. In fact, both neuronal TNFR1 and neuronal IKKβ promoted microglial responses and tissue injury, and TNFR1 was further required for oligodendrocyte loss and axonal damage in cuprizone-induced demyelination. In contrast, neuronal TNFR2 increased preconditioning protection in a kainic acid (KA) excitotoxicity model in mice and limited hippocampal neuron death. The protective effects of neuronal TNFR2 observed in vivo were further investigated in vitro. As previously described, pretreatment of astrocyte-neuron co-cultures with solTNF (and therefore TNFR1) protected them against NMDA excitotoxicity. However, protection was dependent on astrocyte, not neuronal TNFR1, on astrocyte tmTNF-neuronal TNFR2 interactions, and was reproduced by a TNFR2 agonist. Conclusions These results demonstrate that neuronal TNF receptors perform fundamentally different roles in CNS pathology in vivo, with neuronal TNFR1 and IKKβ promoting microglial inflammation and neurotoxicity in demyelination, and neuronal TNFR2 mediating neuroprotection in excitotoxicity. They also reveal that previously described neuroprotective effects of solTNF against glutamate excitotoxicity in vitro are indirect and mediated via astrocyte tmTNF-neuron TNFR2 interactions. These results consolidate the concept that selective inhibition of solTNF/TNFR1 with maintenance of TNFR2 function would have combined anti-inflammatory and neuroprotective properties required for safe treatment of CNS diseases.

2021 ◽  
Author(s):  
Irini Papazian ◽  
Eleni Tsoukala ◽  
Maria Karamita ◽  
Athena Boutou ◽  
Lida Iliopoulou ◽  
...  

Abstract BACKGROUNDDuring inflammatory demyelination TNF receptor 1 (TNFR1) mediates detrimental proinflammatory effects of soluble TNF, whereas TNFR2 mediates beneficial effects of transmembrane TNF through oligodendrocytes, microglia, and possibly other cell types. This model supports use of selective inhibitors of soluble TNF/TNFR1 as antinflammatory drugs for CNS disease. A potential obstacle is the neuroprotective effect of soluble TNF pretreatment described in cultured neurons, but the in vivo relevance is unknown. METHODSTo address this question we generated mice with neuron-specific depletion of TNFR1, TNFR2 or IKKβ and applied experimental models of inflammatory demyelination and acute and preconditioning glutamate excitotoxicity. We also investigated the molecular and cellular requirements of soluble TNF (and therefore TNFR1) neuroprotection by generating astrocyte-neuron co-cultures with different combinations of wildtype and TNF and TNF receptor knockout cells and measuring NMDA excitotoxicity in vitro.RESULTSNeither neuronal TNFR1 nor TNFR2 protected mice during inflammatory demyelination. In fact, both neuronal TNFR1 and neuronal IKKβ promoted microglial responses and tissue injury, and TNFR1 was further required for oligodendrocyte loss and axonal damage in cuprizone demyelination. In contrast, neuronal TNFR2 increased preconditioning protection in a kainic acid excitotoxicity model in mice, and limited hippocampal neuron death. The neuroprotective effects of neuronal TNFR2 observed in vivo were further investigated in vitro. Here as expected, pretreatment of astrocyte-neuron co-cultures with soluble TNF protected them against NMDA excitotoxicity. However, protection was dependent on astrocyte, not neuronal TNFR1, on astrocyte transmembrane TNF-neuronal TNFR2 interactions, and was reproduced by a TNFR2 agonist. CONCLUSIONSThese results demonstrate that neuronal TNF receptors perform fundamentally different roles in CNS pathology in vivo, with neuronal TNFR1 and IKKβ promoting microglial inflammation and neurotoxicity in demyelination, and neuronal TNFR2 mediating neuroprotection in excitotoxicity. They also reveal that previously-described neuroprotective effects of soluble TNF (and therefore TNFR1) against glutamate excitotoxicity in vitro are indirect, and mediated by astrocyte transmembrane TNF-neuron TNFR2 interactions. These results consolidate the concept that selective inhibition of soluble TNF/TNFR1 with maintenance of TNFR2 function would have anti-inflammatory and neuroprotective properties required for the safe treatment of CNS disease.


2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Danfeng Tian ◽  
Yangyang Guo ◽  
Dandan Zhang ◽  
Qiang Gao ◽  
Ganlu Liu ◽  
...  

Abstract Background Synaptic damage and glutamate excitotoxicity have been implicated in the pathogenesis of vascular dementia (VD). Clathrin, RAB5B and N-methyl-d-aspartic acid receptor 1 (NMDAR1) proteins play a vital role in endocytosis of synaptic vesicles in neurons and glutamate over accumulation. Previous researches have been confirmed that Shenzhi Jiannao (SZJN) formula has an anti-apoptotic and neuroprotective effect in VD, but the underlying mechanisms are still unclear. In this study, we aimed to explore the effect of SZJN formula on cognitive impairment and glutamate excitotoxicity via clathrin-mediated endocytosis (CME) in vivo and in vitro. Methods SZJN formula consists of Panax ginseng C.A.Mey., Anemarrhena asphodeloides Bunge, and Paeonia anomala subsp. veitchii (Lynch) D.Y.Hong & K.Y.Pan. All herbs were prepared into granules. Both common carotid arteries were permanent occluded (2‐vessel occlusion, 2VO) in male Sprague Dawley (SD) rats to model VD. One day after operation, the rats began daily treatment with SZJN formula for 2 weeks. The neuroprotective effects of SZJN formula was subsequently assessed by the novel object recognition test, Morris water maze, hematoxylin–eosin (HE) staining and Nissl staining. Glutamate cytotoxicity was assessed by detecting cell viability and cell death of PC12 cells. Immunohistochemistry, immunofluorescence, Western blot, and quantitative real‐time PCR were used to detect the expression levels of clathrin, RAB5B, and NMDAR1. Results Administration of SZJN formula effectively improved short-term memory and spatial memory. SZJN formula treatment significantly reduced hippocampal neuronal loss, and recovered the arrangement and morphology of neurons and Nissl bodies. Moreover, SZJN formula promoted the proliferation of PC12 cells and inhibited glutamate-induced cell death. The down-regulation of clathrin and RAB5B, as well as the upregulation of NMDAR1 in the brain induced by 2VO or glutamate was also notably reversed by SZJN formula at both the protein and mRNA levels, which may contribute to SZJN formula induced improved neurological function. Conclusions Taken together, our findings provide evidence that the neuroprotective effects of SZJN formula in experimental VD maybe mediated through promoting the expression of clathrin-mediated endocytosis and reducing NMDARs‐associated glutamate excitotoxicity. SZJN formula serves as a promising alternative therapy and may be a useful herbal medicine for preventing progression of VD. Graphic abstract


2021 ◽  
Author(s):  
Danfeng Tian ◽  
Yangyang Guo ◽  
Dandan Zhang ◽  
Qiang Gao ◽  
Ganlu Liu ◽  
...  

Abstract Background: Synaptic damage and glutamate excitotoxicity have been implicated in the pathogenesis of vascular dementia (VD). Clathrin, RAB5B and N-methyl-d-aspartic acid receptor 1 (NMDAR1) proteins play a vital role in endocytosis of synaptic vesicles in neurons and glutamate over accumulation. Previous researches have been confirmed that Shenzhi Jiannao (SZJN) formula has an anti-apoptotic and neuroprotective effect in VD, but the underlying mechanisms are still unclear. In this study, we aimed to explore the effect of SZJN formula on cognitive impairment and glutamate excitotoxicity via clathrin-mediated endocytosis (CME) in vivo and in vitro. Methods: Both common carotid arteries were permanent occluded (2‐vessel occlusion, 2VO) in male Sprague Dawley (SD) rats to model VD. One day after operation, the rats began daily treatment with SZJN formula for two weeks. The neuroprotective effects of SZJN formula was subsequently assessed by the novel object recognition test, Morris water maze, hematoxylin-eosin (HE) staining and Nissl staining. Glutamate cytotoxicity was assessed by detecting cell viability and cell death of PC12 cells. Immunohistochemistry, immunofluorescence, Western blot, and quantitative real‐time PCR were used to detect the expression levels of clathrin, RAB5B, and NMDAR1.Results: Administration of SZJN formula effectively improved short-term memory and spatial memory. SZJN treatment significantly reduced hippocampal neuronal loss, and recovered the arrangement and morphology of neurons and Nissl bodies. Moreover, SZJN formula promoted the proliferation of PC12 cells and inhibited glutamate-induced cell death. The down-regulation of clathrin and RAB5B, as well as the upregulation of NMDAR1 in the brain induced by 2VO or glutamate was also notably reversed by SZJN formula at both the protein and mRNA levels, which may contribute to SZJN formula induced improved neurological function. Conclusions: Taken together, our findings provide evidence that the neuroprotective effects of SZJN formula in experimental VD maybe mediated through promoting the expression of clathirn-mediated endocytosis and reducing NMDARs‐associated glutamate excitotoxicity. SZJN formula serves as a promising alternative therapy and may be a useful herbal medicine for preventing progression of VD.


2021 ◽  
pp. 1-13
Author(s):  
Claire Rühlmann ◽  
David Dannehl ◽  
Marcus Brodtrück ◽  
Andrew C. Adams ◽  
Jan Stenzel ◽  
...  

Background: To date, there are no effective treatments for Alzheimer’s disease (AD). Thus, a significant need for research of therapies remains. Objective: One promising pharmacological target is the hormone fibroblast growth factor 21 (FGF21), which is thought to be neuroprotective. A clinical candidate for medical use could be the FGF21 analogue LY2405319 (LY), which has a specificity and potency comparable to FGF21. Methods: The present study investigated the potential neuroprotective effect of LY via PPARγ/apoE/abca1 pathway which is known to degrade amyloid-β (Aβ) plaques by using primary glial cells and hippocampal organotypic brain slice cultures (OBSCs) from 30- and 50-week-old transgenic APPswe/PS1dE9 (tg) mice. By LY treatment of 52-week-old tg mice with advanced Aβ deposition, we further aimed to elaborate the effect of LY on AD pathology in vivo. Results: LY application to primary glial cells caused an upregulation of pparγ, apoE, and abca1 mRNA expression and significantly decreased number and area of Aβ plaques in OBSCs. LY treatment in tg mice increased cerebral [18F] FDG uptake and N-acetylaspartate/creatine ratio indicating enhanced neuronal activity and integrity. Although LY did not reduce the number of Aβ plaques in tg mice, the number of iba1-positive cells was significantly decreased indicating reduced microgliosis. Conclusion: These data identified LY in vitro as an activator of Aβ degrading genes leading to cerebral Aβ load amelioration in early and late AD pathology. Although Aβ plaque reduction by LY failed in vivo, LY may be used as therapeutic agent to treat AD-related neuroinflammation and impaired neuronal integrity.


2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Hailong Yu ◽  
Xiang Cao ◽  
Wei Li ◽  
Pinyi Liu ◽  
Yuanyuan Zhao ◽  
...  

Abstract Background In the central nervous system (CNS), connexin 43 (Cx43) is mainly expressed in astrocytes and regulates astrocytic network homeostasis. Similar to Cx43 overexpression, abnormal excessive opening of Cx43 hemichannels (Cx43Hcs) on reactive astrocytes aggravates the inflammatory response and cell death in CNS pathologies. However, the role of excessive Cx43Hc opening in intracerebral hemorrhage (ICH) injury is not clear. Methods Hemin stimulation in primary cells and collagenase IV injection in C57BL/6J (B6) mice were used as ICH models in vitro and in vivo. After ICH injury, the Cx43 mimetic peptide Gap19 was used for treatment. Ethidium bromide (EtBr) uptake assays were used to measure the opening of Cx43Hcs. Western blotting and immunofluorescence were used to measure protein expression. qRT-PCR and ELISA were used to determine the levels of cytokines. Coimmunoprecipitation (Co-IP) and the Duolink in situ proximity ligation assay (PLA) were applied to measure the association between proteins. Results In this study, Cx43 expression upregulation and excessive Cx43Hc opening was observed in mice after ICH injury. Delayed treatment with Gap19 significantly alleviated hematoma volume and neurological deficits after ICH injury. In addition, Gap19 decreased inflammatory cytokine levels in the tissue surrounding the hematoma and decreased reactive astrogliosis after ICH injury in vitro and in vivo. Intriguingly, Cx43 transcriptional activity and expression in astrocytes were significantly increased after hemin stimulation in culture. However, Gap19 treatment downregulated astrocytic Cx43 expression through the ubiquitin-proteasome pathway without affecting Cx43 transcription. Additionally, our data showed that Gap19 increased Yes-associated protein (YAP) nuclear translocation. This subsequently upregulated SOCS1 and SOCS3 expression and then inhibited the TLR4-NFκB and JAK2-STAT3 pathways in hemin-stimulated astrocytes. Finally, the YAP inhibitor, verteporfin (VP), reversed the anti-inflammatory effect of Gap19 in vitro and almost completely blocked its protective effects in vivo after ICH injury. Conclusions This study provides new insight into potential treatment strategies for ICH injury involving astroglial Cx43 and Cx43Hcs. Suppression of abnormal astroglial Cx43 expression and Cx43Hc opening by Gap19 has anti-inflammatory and neuroprotective effects after ICH injury.


2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Ying Chen ◽  
Haiyan Sun ◽  
Liyong Huang ◽  
Juxiang Li ◽  
Wenke Zhou ◽  
...  

Redox homeostasis has been implicated in subarachnoid hemorrhage (SAH). As a result, antioxidants and/or free radical scavengers have become an important therapeutic modality. Considering that radix trichosanthis (RT) saponins exhibited strong antioxidant ability bothin vivoandin vitro, the present study aimed to reveal whether the neuroprotective activities of RT saponins were mediated by p38/p53 signal pathway after SAH. An established SAH model was used and superoxide dismutase (SOD), malondialdehyde (MDA), induced nitric oxide synthase (iNOS), nitric oxide (NO), lactate dehydrogenase (LDH), p-p38, and p53 activation were detected after 48 h of SAH. The results showed that RT saponins inhibited iNOS expression to restore NO to basal level. Moreover, compared with Cu/Zn-SOD, RT saponins (2 mg/kg/d dosage) significantly increased Mn-SOD activity after SAH. Accompanied with lowered NO and elevated SOD, decreased p38 phosphorylation and p53 activities were observed, especially for RT saponins at 2 mg/kg/d dosage. In this setting, the neurological outcome was also improved with less neuronal cells damage after RT saponins pretreatment. Our findings demonstrated the beneficial effects of RT saponins in enhancing neuroprotective effects by deducing iNOS activity, normalizing SOD level, and inhibiting p-p38 and p53 expression, hence offering significant therapeutic implications for SAH.


2009 ◽  
Vol 2009 ◽  
pp. 1-9 ◽  
Author(s):  
Qun Shan ◽  
Jun Lu ◽  
Yuanlin Zheng ◽  
Jing Li ◽  
Zhong Zhou ◽  
...  

Purple sweet potato color (PSPC), a naturally occurring anthocyanin, has a powerful antioxidant activity in vitro and in vivo. This study explores whether PSPC has the neuroprotective effect on the aging mouse brain induced by D-galactose (D-gal). The mice administrated with PSPC (100 mg/kg.day, 4 weeks, from 9th week) via oral gavage showed significantly improved behavior performance in the open field and passive avoidance test compared with D-gal-treated mice (500 mg/kg.day, 8 weeks). We further investigate the mechanism involved in neuroprotective effects of PSPC on mouse brain. Interestingly, we found, PSPC decreased the expression level of glial fibrillary acidic protein (GFAP), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2), inhibited nuclear translocation of nuclear factor-kappaB (NF-κB), increased the activity of copper/zinc superoxide dismutase (Cu/Zn-SOD) and catalase (CAT), and reduced the content of malondialdehyde (MDA), respectively. Our data suggested that PSPC attenuated D-gal-induced cognitive impairment partly via enhancing the antioxidant and anti-inflammatory capacity.


2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Yiyi Jin ◽  
Jianchang Qian ◽  
Xin Ju ◽  
Xiaodong Bao ◽  
Li Li ◽  
...  

Inflammation is a key factor in the pathogenesis of ALI. Therefore, suppression of inflammatory response could be a potential strategy to treat LPS-induced lung injury. Osthole, a natural coumarin extract, has been reported to protect against acute kidney injury through an anti-inflammatory mechanism, but its effect on ALI is poorly understood. In this study, we investigated whether osthole ameliorates inflammatory sepsis-related ALI. Results from in vitro studies indicated that osthole treatment inhibited the LPS-induced inflammatory response in mouse peritoneal macrophages through blocking the nuclear translocation of NF-κB. Consistently, the in vivo studies indicated that osthole significantly prolonged the survival of septic mice which was accompanied by inflammation suppression. In the ALI mouse model, osthole effectively inhibited the development of lung tissue injury, leukocytic recruitment, and cytokine productions, which was associated with inhibition of NF-κB nuclear translocation. These findings provide evidence that osthole was a potent inhibitor of NF-κB and inflammatory injury and suggest that it could be a promising anti-inflammatory agent for therapy of septic shock and acute lung injury.


2021 ◽  
Author(s):  
Maria Trapali ◽  
Vasiliki Lagouri

Pomegranate (Punica granatum L.) is one of the oldest edible fruits in the Mediterranean area and has been used extensively in the folk medicine. Popularity of pomegranate has increased especially in the last decade because of the health effects of the fruit. Polyphenols, represent the predominant class of phytochemicals of pomegranate, mainly consisting of hydrolysable tannins and ellagic acid. Pomegranate is a rich source of the ellagitannin punicalagin, which has aroused considerable interest in pomegranate fruit as a new therapeutic agent in recent years. Most studies on the effects of pomegranate juice have focused on its ability to cure diabetes and atherosclerosis. The present review summarizes some recent studies on the vasculoprotective and neuroprotective effect of various parts of pomegranate and its main compounds especially hydrolysable tannins ellagitannins, ellagic acid and their metabolites. The in vitro and in vivo studies, showed that the whole parts of pomegranate as well as its main components had a positive influence on blood glucose, lipid levels, oxidation stress and neuro/inflammatory biomarkers. They could be used as a future therapeutic agent towards several vascular and neurodegenerative disorders such as hypertension, coronary heart disease and Alzheimer.


2021 ◽  
Vol 12 ◽  
Author(s):  
Md. Shahazul Islam ◽  
Cristina Quispe ◽  
Rajib Hossain ◽  
Muhammad Torequl Islam ◽  
Ahmed Al-Harrasi ◽  
...  

Quercetin (QUR) is a natural bioactive flavonoid that has been lately very studied for its beneficial properties in many pathologies. Its neuroprotective effects have been demonstrated in many in vitro studies, as well as in vivo animal experiments and human trials. QUR protects the organism against neurotoxic chemicals and also can prevent the evolution and development of neuronal injury and neurodegeneration. The present work aimed to summarize the literature about the neuroprotective effect of QUR using known database sources. Besides, this review focuses on the assessment of the potential utilization of QUR as a complementary or alternative medicine for preventing and treating neurodegenerative diseases. An up-to-date search was conducted in PubMed, Science Direct and Google Scholar for published work dealing with the neuroprotective effects of QUR against neurotoxic chemicals or in neuronal injury, and in the treatment of neurodegenerative diseases. Findings suggest that QUR possess neuropharmacological protective effects in neurodegenerative brain disorders such as Alzheimer’s disease, Amyloid β peptide, Parkinson’s disease, Huntington's disease, multiple sclerosis, and amyotrophic lateral sclerosis. In summary, this review emphasizes the neuroprotective effects of QUR and its advantages in being used in complementary medicine for the prevention and treatment o of different neurodegenerative diseases.


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