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Chung J, Jernigan J, Menees KB, Lee JK. RGS10 mitigates high glucose-induced microglial inflammation via the reactive oxidative stress pathway and enhances synuclein clearance in microglia. Front Cell Neurosci 2024; 18:1374298. [PMID: 38812790 PMCID: PMC11133718 DOI: 10.3389/fncel.2024.1374298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Accepted: 04/22/2024] [Indexed: 05/31/2024] Open
Abstract
Microglia play a critical role in maintaining brain homeostasis but become dysregulated in neurodegenerative diseases. Regulator of G-protein Signaling 10 (RGS10), one of the most abundant homeostasis proteins in microglia, decreases with aging and functions as a negative regulator of microglia activation. RGS10-deficient mice exhibit impaired glucose tolerance, and high-fat diet induces insulin resistance in these mice. In this study, we investigated whether RGS10 modulates microglia activation in response to hyperglycemic conditions, complementing our previous findings of its role in inflammatory stimuli. In RGS10 knockdown (KD) BV2 cells, TNF production increased significantly in response to high glucose, particularly under proinflammatory conditions. Additionally, glucose uptake and GLUT1 mRNA levels were significantly elevated in RGS10 KD BV2 cells. These cells produced higher ROS and displayed reduced sensitivity to the antioxidant N-Acetyl Cysteine (NAC) when exposed to high glucose. Notably, both BV2 cells and primary microglia that lack RGS10 exhibited impaired uptake of alpha-synuclein aggregates. These findings suggest that RGS10 acts as a negative regulator of microglia activation not only in response to inflammation but also under hyperglycemic conditions.
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Affiliation(s)
| | | | | | - Jae-Kyung Lee
- Department of Physiology and Pharmacology, University of Georgia College of Veterinary Medicine, Athens, GA, United States
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Kato H, Iwashita K, Iwasa M, Kato S, Yamakage H, Suganami T, Tanaka M, Satoh-Asahara N. Imeglimin Exhibits Novel Anti-Inflammatory Effects on High-Glucose-Stimulated Mouse Microglia through ULK1-Mediated Suppression of the TXNIP-NLRP3 Axis. Cells 2024; 13:284. [PMID: 38334676 PMCID: PMC10854746 DOI: 10.3390/cells13030284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 01/30/2024] [Accepted: 02/02/2024] [Indexed: 02/10/2024] Open
Abstract
Type 2 diabetes mellitus (T2DM) is an epidemiological risk factor for dementia and has been implicated in multifactorial pathologies, including neuroinflammation. In the present study, we aimed to elucidate the potential anti-inflammatory effects of imeglimin, a novel antidiabetic agent, on high-glucose (HG)-stimulated microglia. Mouse microglial BV2 cells were stimulated with HG in the presence or absence of imeglimin. We examined the effects of imeglimin on the levels of proinflammatory cytokines, intracellular reactive oxygen species (ROS), mitochondrial integrity, and components related to the inflammasome or autophagy pathways in these cells. Our results showed that imeglimin suppressed the HG-induced production of interleukin-1beta (IL-1β) by reducing the intracellular ROS levels, ameliorating mitochondrial dysfunction, and inhibiting the activation of the thioredoxin-interacting protein (TXNIP)-NOD-like receptor family pyrin domain containing 3 (NLRP3) axis. Moreover, the inhibitory effects of imeglimin on the TXNIP-NLRP3 axis depended on the imeglimin-induced activation of ULK1, which also exhibited novel anti-inflammatory effects without autophagy induction. These findings suggest that imeglimin exerted novel suppressive effects on HG-stimulated microglia through the ULK1-TXNIP-NLRP3 axis, and may, thereby, contribute to the development of innovative strategies to prevent T2DM-associated cognitive impairment.
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Affiliation(s)
- Hisashi Kato
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, NHO Kyoto Medical Center, Kyoto 612-8555, Japan; (H.K.)
| | - Kaori Iwashita
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, NHO Kyoto Medical Center, Kyoto 612-8555, Japan; (H.K.)
| | - Masayo Iwasa
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, NHO Kyoto Medical Center, Kyoto 612-8555, Japan; (H.K.)
| | - Sayaka Kato
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, NHO Kyoto Medical Center, Kyoto 612-8555, Japan; (H.K.)
- Department of Endocrinology and Metabolism, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Hajime Yamakage
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, NHO Kyoto Medical Center, Kyoto 612-8555, Japan; (H.K.)
| | - Takayoshi Suganami
- Department of Molecular Medicine and Metabolism, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan
- Department of Immunometabolism, Nagoya University Graduate School of Medicine, Nagoya 464-8601, Japan
- Institute of Nano-Life-Systems, Institutes of Innovation for Future Society, Nagoya University, Nagoya 464-8601, Japan
- Center for One Medicine Innovative Translational Research (COMIT), Nagoya University, Nagoya 464-8601, Japan
| | - Masashi Tanaka
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, NHO Kyoto Medical Center, Kyoto 612-8555, Japan; (H.K.)
- Department of Rehabilitation, Health Science University, Minamitsuru-gun 401-0380, Japan
| | - Noriko Satoh-Asahara
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, NHO Kyoto Medical Center, Kyoto 612-8555, Japan; (H.K.)
- Department of Metabolic Syndrome and Nutritional Science, Research Institute of Environmental Medicine, Nagoya University, Nagoya 466-8550, Japan
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Iwasa M, Kato H, Iwashita K, Yamakage H, Kato S, Saito S, Ihara M, Nishimura H, Kawamoto A, Suganami T, Tanaka M, Satoh-Asahara N. Taxifolin Suppresses Inflammatory Responses of High-Glucose-Stimulated Mouse Microglia by Attenuating the TXNIP-NLRP3 Axis. Nutrients 2023; 15:2738. [PMID: 37375642 DOI: 10.3390/nu15122738] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 06/12/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023] Open
Abstract
Type 2 diabetes mellitus is associated with an increased risk of dementia, potentially through multifactorial pathologies, including neuroinflammation. Therefore, there is a need to identify novel agents that can suppress neuroinflammation and prevent cognitive impairment in diabetes. In the present study, we demonstrated that a high-glucose (HG) environment elevates the intracellular reactive oxygen species (ROS) levels and triggers inflammatory responses in the mouse microglial cell line BV-2. We further found that thioredoxin-interacting protein (TXNIP), a ROS-responsive positive regulator of the nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, was also upregulated, followed by NLRP3 inflammasome activation and subsequent interleukin-1beta (IL-1β) production in these cells. Conversely, caspase-1 was not significantly activated, suggesting the involvement of noncanonical pathways in these inflammatory responses. Moreover, our results demonstrated that taxifolin, a natural flavonoid with antioxidant and radical scavenging activities, suppressed IL-1β production by reducing the intracellular ROS levels and inhibiting the activation of the TXNIP-NLRP3 axis. These findings suggest the novel anti-inflammatory effects of taxifolin on microglia in an HG environment, which could help develop novel strategies for suppressing neuroinflammation in diabetes.
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Affiliation(s)
- Masayo Iwasa
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan
| | - Hisashi Kato
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan
| | - Kaori Iwashita
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan
| | - Hajime Yamakage
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan
| | - Sayaka Kato
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan
- Department of Endocrinology and Metabolism, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan
| | - Satoshi Saito
- Department of Neurology, National Cerebral and Cardiovascular Center, Osaka 564-8565, Japan
| | - Masafumi Ihara
- Department of Neurology, National Cerebral and Cardiovascular Center, Osaka 564-8565, Japan
| | - Hideo Nishimura
- Translational Research Center for Medical Innovation, Foundation for Biomedical Research and Innovation at Kobe, Kobe 650-0047, Japan
| | - Atsuhiko Kawamoto
- Translational Research Center for Medical Innovation, Foundation for Biomedical Research and Innovation at Kobe, Kobe 650-0047, Japan
| | - Takayoshi Suganami
- Department of Molecular Medicine and Metabolism, Research Institute of Environmental Medicine, Nagoya University, Nagoya 464-8601, Japan
- Department of Immunometabolism, Nagoya University Graduate School of Medicine, Nagoya 464-8601, Japan
- Institute of Nano-Life-Systems, Institutes of Innovation for Future Society, Nagoya University, Nagoya 464-8601, Japan
- Center for One Medicine Innovative Translational Research, Gifu University Institute for Advanced Study, Gifu 501-1193, Japan
| | - Masashi Tanaka
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan
- Department of Rehabilitation, Health Science University, Minamitsuru-gun 401-0380, Japan
| | - Noriko Satoh-Asahara
- Department of Endocrinology, Metabolism and Hypertension Research, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto 612-8555, Japan
- Department of Metabolic Syndrome and Nutritional Science, Research Institute of Environmental Medicine, Nagoya University, Nagoya 466-8550, Japan
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Matsumura Y, Kitabatake M, Kayano SI, Ito T. Dietary Phenolic Compounds: Their Health Benefits and Association with the Gut Microbiota. Antioxidants (Basel) 2023; 12:antiox12040880. [PMID: 37107256 PMCID: PMC10135282 DOI: 10.3390/antiox12040880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/23/2023] [Accepted: 03/24/2023] [Indexed: 04/08/2023] Open
Abstract
Oxidative stress causes various diseases, such as type II diabetes and dyslipidemia, while antioxidants in foods may prevent a number of diseases and delay aging by exerting their effects in vivo. Phenolic compounds are phytochemicals such as flavonoids which consist of flavonols, flavones, flavanonols, flavanones, anthocyanidins, isoflavones, lignans, stilbenoids, curcuminoids, phenolic acids, and tannins. They have phenolic hydroxyl groups in their molecular structures. These compounds are present in most plants, are abundant in nature, and contribute to the bitterness and color of various foods. Dietary phenolic compounds, such as quercetin in onions and sesamin in sesame, exhibit antioxidant activity and help prevent cell aging and diseases. In addition, other kinds of compounds, such as tannins, have larger molecular weights, and many unexplained aspects still exist. The antioxidant activities of phenolic compounds may be beneficial for human health. On the other hand, metabolism by intestinal bacteria changes the structures of these compounds with antioxidant properties, and the resulting metabolites exert their effects in vivo. In recent years, it has become possible to analyze the composition of the intestinal microbiota. The augmentation of the intestinal microbiota by the intake of phenolic compounds has been implicated in disease prevention and symptom recovery. Furthermore, the “brain–gut axis”, which is a communication system between the gut microbiome and brain, is attracting increasing attention, and research has revealed that the gut microbiota and dietary phenolic compounds affect brain homeostasis. In this review, we discuss the usefulness of dietary phenolic compounds with antioxidant activities against some diseases, their biotransformation by the gut microbiota, the augmentation of the intestinal microflora, and their effects on the brain–gut axis.
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Affiliation(s)
- Yoko Matsumura
- Department of Nutrition, Faculty of Health Sciences, Kio University, Kitakatsuragi-gun, Nara 635-0832, Japan
- Department of Immunology, Nara Medical University, Kashihara, Nara 634-8521, Japan
| | - Masahiro Kitabatake
- Department of Immunology, Nara Medical University, Kashihara, Nara 634-8521, Japan
| | - Shin-ichi Kayano
- Department of Nutrition, Faculty of Health Sciences, Kio University, Kitakatsuragi-gun, Nara 635-0832, Japan
| | - Toshihiro Ito
- Department of Immunology, Nara Medical University, Kashihara, Nara 634-8521, Japan
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