LOX-1 mediates inflammatory activation of microglial cells through the p38-MAPK/NF-κB pathways under hypoxic-ischemic conditions
Abstract Background Microglial cells play an important role in the immune system in the brain. Activated microglial cells are not only injurious but also neuroprotective. We confirmed marked lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) expression in microglial cells in pathologica...
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| Format: | Article |
| Language: | English |
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BMC
2023-06-01
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| Series: | Cell Communication and Signaling |
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| Online Access: | https://doi.org/10.1186/s12964-023-01048-w |
| _version_ | 1797811363749298176 |
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| author | Yoshinori Aoki Hongmei Dai Fumika Furuta Tomohisa Akamatsu Takuya Oshima Naoto Takahashi Yu-ichi Goto Akira Oka Masayuki Itoh |
| author_facet | Yoshinori Aoki Hongmei Dai Fumika Furuta Tomohisa Akamatsu Takuya Oshima Naoto Takahashi Yu-ichi Goto Akira Oka Masayuki Itoh |
| author_sort | Yoshinori Aoki |
| collection | DOAJ |
| description | Abstract Background Microglial cells play an important role in the immune system in the brain. Activated microglial cells are not only injurious but also neuroprotective. We confirmed marked lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) expression in microglial cells in pathological lesions in the neonatal hypoxic-ischemic encephalopathy (nHIE) model brain. LOX-1 is known to be an activator of cytokines and chemokines through intracellular pathways. Here, we investigated a novel role of LOX-1 and the molecular mechanism of LOX-1 gene transcription microglial cells under hypoxic and ischemic conditions. Methods We isolated primary rat microglial cells from 3-day-old rat brains and confirmed that the isolated cells showed more than 98% Iba-1 positivity with immunocytochemistry. We treated primary rat microglial cells with oxygen glucose deprivation (OGD) as an in vitro model of nHIE. Then, we evaluated the expression levels of LOX-1, cytokines and chemokines in cells treated with or without siRNA and inhibitors compared with those of cells that did not receive OGD-treatment. To confirm transcription factor binding to the OLR-1 gene promoter under the OGD conditions, we performed a luciferase reporter assay and chromatin immunoprecipitation assay. In addition, we analyzed reactive oxygen species and cell viability. Results We found that defects in oxygen and nutrition induced LOX-1 expression and led to the production of inflammatory mediators, such as the cytokines IL-1β, IL-6 and TNF-α; the chemokines CCL2, CCL5 and CCL3; and reactive oxygen/nitrogen species. Then, the LOX-1 signal transduction pathway was blocked by inhibitors, LOX-1 siRNA, the p38-MAPK inhibitor SB203580 and the NF-κB inhibitor BAY11-7082 suppressed the production of inflammatory mediators. We found that NF-κB and HIF-1α bind to the promoter region of the OLR-1 gene. Based on the results of the luciferase reporter assay, NF-κB has strong transcriptional activity. Moreover, we demonstrated that LOX-1 in microglial cells was autonomously overexpressed by positive feedback of the intracellular LOX-1 pathway. Conclusion The hypoxic/ischemic conditions of microglial cells induced LOX-1 expression and activated the immune system. LOX-1 and its related molecules or chemicals may be major therapeutic candidates. Video abstract |
| first_indexed | 2024-03-13T07:22:36Z |
| format | Article |
| id | doaj.art-c601080a670f43a59035a34ea080107a |
| institution | Directory Open Access Journal |
| issn | 1478-811X |
| language | English |
| last_indexed | 2024-03-13T07:22:36Z |
| publishDate | 2023-06-01 |
| publisher | BMC |
| record_format | Article |
| series | Cell Communication and Signaling |
| spelling | doaj.art-c601080a670f43a59035a34ea080107a2023-06-04T11:34:33ZengBMCCell Communication and Signaling1478-811X2023-06-0121111310.1186/s12964-023-01048-wLOX-1 mediates inflammatory activation of microglial cells through the p38-MAPK/NF-κB pathways under hypoxic-ischemic conditionsYoshinori Aoki0Hongmei Dai1Fumika Furuta2Tomohisa Akamatsu3Takuya Oshima4Naoto Takahashi5Yu-ichi Goto6Akira Oka7Masayuki Itoh8Department of Mental Retardation and Birth Defect Research, National Institute of Neurology, National Center of Neurology and PsychiatryDepartment of Mental Retardation and Birth Defect Research, National Institute of Neurology, National Center of Neurology and PsychiatryDepartment of Mental Retardation and Birth Defect Research, National Institute of Neurology, National Center of Neurology and PsychiatryDepartment of Mental Retardation and Birth Defect Research, National Institute of Neurology, National Center of Neurology and PsychiatryDepartment of Mental Retardation and Birth Defect Research, National Institute of Neurology, National Center of Neurology and PsychiatryDepartment of Pediatrics, Graduate School of Medicine, The University of TokyoDepartment of Mental Retardation and Birth Defect Research, National Institute of Neurology, National Center of Neurology and PsychiatryDepartment of Pediatrics, Graduate School of Medicine, The University of TokyoDepartment of Mental Retardation and Birth Defect Research, National Institute of Neurology, National Center of Neurology and PsychiatryAbstract Background Microglial cells play an important role in the immune system in the brain. Activated microglial cells are not only injurious but also neuroprotective. We confirmed marked lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) expression in microglial cells in pathological lesions in the neonatal hypoxic-ischemic encephalopathy (nHIE) model brain. LOX-1 is known to be an activator of cytokines and chemokines through intracellular pathways. Here, we investigated a novel role of LOX-1 and the molecular mechanism of LOX-1 gene transcription microglial cells under hypoxic and ischemic conditions. Methods We isolated primary rat microglial cells from 3-day-old rat brains and confirmed that the isolated cells showed more than 98% Iba-1 positivity with immunocytochemistry. We treated primary rat microglial cells with oxygen glucose deprivation (OGD) as an in vitro model of nHIE. Then, we evaluated the expression levels of LOX-1, cytokines and chemokines in cells treated with or without siRNA and inhibitors compared with those of cells that did not receive OGD-treatment. To confirm transcription factor binding to the OLR-1 gene promoter under the OGD conditions, we performed a luciferase reporter assay and chromatin immunoprecipitation assay. In addition, we analyzed reactive oxygen species and cell viability. Results We found that defects in oxygen and nutrition induced LOX-1 expression and led to the production of inflammatory mediators, such as the cytokines IL-1β, IL-6 and TNF-α; the chemokines CCL2, CCL5 and CCL3; and reactive oxygen/nitrogen species. Then, the LOX-1 signal transduction pathway was blocked by inhibitors, LOX-1 siRNA, the p38-MAPK inhibitor SB203580 and the NF-κB inhibitor BAY11-7082 suppressed the production of inflammatory mediators. We found that NF-κB and HIF-1α bind to the promoter region of the OLR-1 gene. Based on the results of the luciferase reporter assay, NF-κB has strong transcriptional activity. Moreover, we demonstrated that LOX-1 in microglial cells was autonomously overexpressed by positive feedback of the intracellular LOX-1 pathway. Conclusion The hypoxic/ischemic conditions of microglial cells induced LOX-1 expression and activated the immune system. LOX-1 and its related molecules or chemicals may be major therapeutic candidates. Video abstracthttps://doi.org/10.1186/s12964-023-01048-wHypoxiaIschemiaMicrogliap38-MAPKNF‐kappa B (NF‐κB)OLR-1 |
| spellingShingle | Yoshinori Aoki Hongmei Dai Fumika Furuta Tomohisa Akamatsu Takuya Oshima Naoto Takahashi Yu-ichi Goto Akira Oka Masayuki Itoh LOX-1 mediates inflammatory activation of microglial cells through the p38-MAPK/NF-κB pathways under hypoxic-ischemic conditions Cell Communication and Signaling Hypoxia Ischemia Microglia p38-MAPK NF‐kappa B (NF‐κB) OLR-1 |
| title | LOX-1 mediates inflammatory activation of microglial cells through the p38-MAPK/NF-κB pathways under hypoxic-ischemic conditions |
| title_full | LOX-1 mediates inflammatory activation of microglial cells through the p38-MAPK/NF-κB pathways under hypoxic-ischemic conditions |
| title_fullStr | LOX-1 mediates inflammatory activation of microglial cells through the p38-MAPK/NF-κB pathways under hypoxic-ischemic conditions |
| title_full_unstemmed | LOX-1 mediates inflammatory activation of microglial cells through the p38-MAPK/NF-κB pathways under hypoxic-ischemic conditions |
| title_short | LOX-1 mediates inflammatory activation of microglial cells through the p38-MAPK/NF-κB pathways under hypoxic-ischemic conditions |
| title_sort | lox 1 mediates inflammatory activation of microglial cells through the p38 mapk nf κb pathways under hypoxic ischemic conditions |
| topic | Hypoxia Ischemia Microglia p38-MAPK NF‐kappa B (NF‐κB) OLR-1 |
| url | https://doi.org/10.1186/s12964-023-01048-w |
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